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1. Underwater image enhancement by using transmission optimization and background light estimation via principal component analysis fusion.

Author

Mishra, Amarendra Kumar, Kumar, Manjeet, and Choudhry, Mahipal Singh

Abstract

The optical properties of water exacerbate the problems that arise in underwater imaging, including low contrast, color cast, noise, and haze. Pre-processing techniques are required in order to extract relevant information from these images. To solve the above problem, a new underwater image enhancement by using transmission optimization and background light estimation via Principal component analysis (TOBPCA) is proposed. Firstly, the background light of the degraded underwater image is computed using a dark channel prior; secondly, the degraded underwater RGB images are converted to CIELAB color space. Then, the transmission map of the lightness (L) component of CIELAB color space is represented and optimization of the transmission map is performed. Then, the Principal component analysis is used to fuse the background light and optimized transmission map. Finally, color correction is applied to enhance the underwater image. The proposed method is evaluated on the underwater color cast set (UCCS), underwater image quality set (UIQS), and underwater image enhancement benchmark (UIEB) Database based on Patch-based contrast quality index (PCQI), underwater color image quality evaluation (UCIQE), Underwater image quality measure (UIQM), Structural similarity index (SSIM), Peak signal to noise ratio (PSNR), and discrete entropy (DE) parameters. To verify the efficacy of the proposed method, a qualitative and quantitative comparison has been made on the UCCS, UIQS, and UIEB datasets. The result demonstrates that the proposed method outperforms the state-of-the-art method, in terms of PCQI, UCIQE, SSIM, and DE parameters. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Distance-Independent Background Light Estimation Method.

Author

Yu, Aidi, Wang, Yujia, and Zhou, Sixing

Subjects
IMAGE reconstruction
Abstract

A distance-independent background light estimation method is proposed for underwater overhead images. The method addresses the challenge of the absence of the farthest point in underwater overhead images by adopting a global perspective to select the optimal solution and estimate the background light by minimizing the loss function. Moreover, to enhance the information retention in the images, a translation function is employed to adjust the transmission map values within the range of [0.1, 0.95]. Additionally, the method capitalizes on the redundancy of image information and the similarity of adjacent frames, resulting in higher computational efficiency. The comparative experimental results show that the proposed method has better restoration performance on underwater images in various scenarios, especially in handling color bias and preserving information. [ABSTRACT FROM AUTHOR]

Published
2023
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3. Free-Space Optical Data Receivers with Avalanche Detectors for Satellite Downlinks Regarding Background Light.

Author

Giggenbach, Dirk

Subjects
*OPTICAL receivers, *AVALANCHE photodiodes, *FREE-space optical technology, *DETECTORS, *BINARY sequences, *OPTICAL communications, *HIGH voltages, *SEMICONDUCTOR optical amplifiers
Abstract

Data receiving frontends using avalanche photodiodes are used in optical free-space communications for their effective sensitivity, large detection area, and uncomplex operation. Precise control of the high voltage necessary to trigger the avalanche effect inside the photodiode depends on the semiconductor's excess noise factor, temperature, received signal power, background light, and also the subsequent thermal noise behavior of the transimpedance amplifier. Several prerequisites must be regarded and are explained in this document. We focus on the application of using avalanche photodiodes as data receivers for the on/off-keying of modulated bit streams with a 50% duty cycle. Also, experimental verification of the performance of the receiver with background light is demonstrated. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Gate-Width Optimisation Based on Time-Gated Single Photon Avalanche Diode Receiver for Optical Wireless Communications.

Author

Mu, Yu, Du, Xiaoxiao, Wang, Chao, Ye, Ziwei, and Zhu, Yijun

Subjects
AVALANCHE diodes, OPTICAL communications, OPTICAL receivers, WIRELESS communications, BIT error rate, PHOTON counting, INTERSTIMULUS interval
Abstract

Using a single photon avalanche diode (SPAD) as a receiver in an optical wireless communications (OWC) system can effectively expand the transmission distance. However, the performance of the SPAD receiver is usually affected with the bit error rate (BER) lower bound determined by background light and the inter-symbol interference (ISI) distortion caused by dead time. In this paper, external time-gated technology is employed, and the SPAD is only activated within the set gate-ON time to alleviate the influence of background light and ISI distortion. The SPAD photon counting model and the communication BER model are established according to the external time-gated characteristics. Considering the functional relationship among the gate-ON time, signal light flux, background light flux and blocking time, we take the minimum BER as the optimization target, the optimal gate-ON time is derived. The numerical results show that whenever the signal light flux or the background light flux is higher, the BER performance of the time-gated mode is apparently better than the free-running mode. For example, when signal photons and background photons are 30 and 10 per symbol time, respectively, the BER of free-running SPAD converges to 0.1, while the BER of the time-gated scheme is about 10 − 6 . [ABSTRACT FROM AUTHOR]

Published
2022
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6. Distance-Independent Background Light Estimation Method

Author

Aidi Yu, Yujia Wang, and Sixing Zhou

Subjects
background light, underwater image restoration, distance-independent, Naval architecture. Shipbuilding. Marine engineering, VM1-989, Oceanography, GC1-1581
Abstract

A distance-independent background light estimation method is proposed for underwater overhead images. The method addresses the challenge of the absence of the farthest point in underwater overhead images by adopting a global perspective to select the optimal solution and estimate the background light by minimizing the loss function. Moreover, to enhance the information retention in the images, a translation function is employed to adjust the transmission map values within the range of [0.1, 0.95]. Additionally, the method capitalizes on the redundancy of image information and the similarity of adjacent frames, resulting in higher computational efficiency. The comparative experimental results show that the proposed method has better restoration performance on underwater images in various scenarios, especially in handling color bias and preserving information.

Published
2023
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8. Measurement-based characterization of atmospheric background light in satellite-to-ground quantum key distribution scenarios.

Author

Häusler, Stefanie, Orsucci, Davide, Vollmann, Leonard, Peev, Eltimir, and Moll, Florian

Subjects
*PHOTONS, *INFORMATION-theoretic security, *QUANTUM communication, *FREE-space optical technology, *OPTICAL losses, *ERROR rates, *OPTICAL fibers, *OPTICAL communications
Abstract

Quantum key distribution (QKD) enables private communication with information theoretic security. Free-space optical communication allows one to implement QKD without the limitations imposed by fiber networks such as the exponential scaling of transmission losses in optical fibers. Therefore, free-space QKD via satellite links is a promising technology to provide long-distance quantum communication connections. In free-space QKD systems, background light is the main source of noise, which has to be suppressed by means of spectral, spatial, and temporal filtering to reach a sufficiently low quantum bit error rate (QBER). Only then a quantum key can be exchanged successfully. To be able to define the requirements for a free-space QKD system, the background light must be examined more closely. Current considerations concentrate on cloud-free skies and rural environments. Free-space QKD will also take place when the sky is partly clouded and most likely also in urban environments. Here, an overview of physical causes of background light for downlink scenarios is given. Furthermore, the relation between QBER and background light is derived for a decoy-state BB84 protocol with polarization-encoded qubits to give an example of the dependency. Moreover, a setup to experimentally investigate the background light is shown. Measurement data were taken with this setup in Oberpfaffenhofen near Munich (Germany) in C-band. The measurement data are used to verify a background light simulation tool. The outcome underlines that simulation tools are sufficient for clear sky scenarios. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Imaging multiple objects through scattering medium under strong background illumination.

Author

Niu, Yuhao, Liu, Yubin, Chen, Guang, Zhao, Jieming, Deng, Lin, Sa, Ye, and Gao, Zhan

Subjects
*IMAGE denoising, *SPECKLE interference, *OPTICAL limiting, *PRINCIPAL components analysis, *SPECKLE interferometry, *LIGHTING
Abstract

• A new method for isolating speckle pattern of each object with an image difference process is proposed. • A new image denoising method for effectively eliminating the interference of the background noise is proposed. • The image denoising method is robust to the interference of difference background noise condition. Speckle correlation imaging is a typical method to image through strongly scattering medium. However, limited by the optical memory effect range, this method is hard to image multiple objects that are randomly distributed on the object plane with strong background illumination. To solve this problem, we proposed a new method that allows to image multiple objects with strong background illumination. It consists of isolating speckle pattern of each object with an image difference process and eliminating the interference of the background noise with the principal components analysis (PCA) technique. Our method can realize imaging of more than two objects through the scattering medium, and compared with other methods, our method can provide better observations of the objects in the bright field scenarios. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Enhancement method for non-uniform scattering images of turbid underwater based on neural network.

Author

Liu, Ke and Liang, Yongquan

Subjects
*IMAGE enhancement (Imaging systems), *LIGHT absorption, *CONVOLUTIONAL neural networks, *IMAGE intensifiers, *IMAGE segmentation, *PROBLEM solving
Abstract

Due to the influence of light absorption and scattering in the water medium, underwater images often appear with different degrees of blur, color distortion, and so on. The physical model-based method needs to establish image degradation processes and improve image quality by assuming and estimating complex parameters, which limits the generalization ability and practical application effect of these methods. To solve the above problems, this paper proposes an image enhancement method of non-uniform scattering in turbid underwater based on neural network. First, the high-frequency and low-frequency components of underwater images were obtained through the difference of gaussian (DOG) and bilateral filtering (BF), respectively. Then, for the high-frequency component, pulse coupled neural networks (PCNN) to improve the edge details of the image. For low-frequency components, it is carried out in two steps: an adaptive automatic white balance and polynomial regression (AAWBPR) algorithm is proposed, which can effectively eliminate the color bias under different color temperatures and improve the brightness of images; the adaptive color and contrast enhancement (ACCE) method is used to further enhance the color and contrast of images. Finally, Decom-Net and the improved U-Net method are used to reduce the errors caused by the non-uniform scattering effect, weaken the noise interference, and enhance the overall effect of images. Extensive experiments show that the proposed method can effectively improve the quality of turbid underwater non-uniform scattering images, enhance the contrast of images, reduce the complexity of parameters, and has good generalization performance and practical application effects. • A suppression algorithm of heterogeneous scattering in turbid water is proposed. • An adaptive automatic white balance and polynomial regression algorithm is proposed. • It reduces the image deviation, and improve the problem of complex model parameters. • It is applied to image segmentation, saliency detection, and keypoint detection. • This method can get better training results in small dataset. [ABSTRACT FROM AUTHOR]

Published
2023
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11. Photodetector resistant to background light noise with extended dynamic range of input signals

Author

Yu. Dobrovolsky, V. V. Ryukhtin, and V. M. Lipka

Subjects
Physics, dynamic range, Noise, background light noise, Dynamic range, Acoustics, Photodetector, Electrical engineering. Electronics. Nuclear engineering, Background light, photodetector, TK1-9971
Abstract

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

Published
2021

12. Quantification of Light Scattering Detection Efficiency and Background in Flow Cytometry

Author

Rienk Nieuwland, Edwin van der Pol, Ton G. van Leeuwen, Leonie de Rond, Frank A. W. Coumans, Joshua A. Welsh, Biomedical Engineering and Physics, Graduate School, Laboratory Specialized Diagnostics & Research, ACS - Atherosclerosis & ischemic syndromes, ACS - Microcirculation, and CCA - Imaging and biomarkers

Subjects
Physics, standardization, Histology, business.industry, detection limit, Coefficient of variation, flow cytometry, Detector, Cell Biology, Photoelectric effect, sensitivity, Fluorescence, light scattering, Light scattering, Pathology and Forensic Medicine, Background noise, Optics, Scattering, Radiation, background light, optical efficiency, photoelectron scale, resolution limit, business, Sensitivity (electronics), Refractive index
Abstract

Knowledge of the sensitivity of a flow cytometer is essential for data interpretation and comparison. However, light scatter sensitivity currently cannot be quantified due to a lack of a standardized unit. Analogous to the QB approach for fluorescence, we show that it is possible to derive the detection efficiency Q and background B for light scatter detectors, using the scattering cross section (σs) in nm2 as a standardized unit. Side scatter of a mixture of polystyrene beads with known diameter and refractive index was measured at different illumination powers on a customized BD FACSCanto. Poisson statistics was used to derive the number of statistical photoelectrons from the measured coefficient of variation of the bead populations. The resulting light scatter sensitivity was expressed as Q in photoelectrons/nm2, B in nm2, and a resolution limit (R) in nm2. As expected, Q scales linearly with the illumination power (R2 = 0.999), and B is constant over the illumination power (difference < 15%). The resulting R decreased from 1.75·105 nm2 at 20 mW, to 4.03·104 nm2 at 200 mW, which resembles the light scattering of a 450 nm and a 314 nm polystyrene bead, respectively. Comparison of R with the side scatter histograms confirmed that R describes the lower limit at which light scatter signals can be fully discriminated from the background noise. In conclusion, as a proof of principle, we derived Q, B, and R for a scatter detector of a flow cytometer where photon noise associated with the light scattering signal originating from the particle is the dominant source of the measured variation. To quantify the sensitivity of scatter detectors with nanoparticle (

Published
2021

13. Gate-Width Optimisation Based on Time-Gated Single Photon Avalanche Diode Receiver for Optical Wireless Communications

Author

Yu Mu, Xiaoxiao Du, Chao Wang, Ziwei Ye, and Yijun Zhu

Subjects
Computer Networks and Communications, Hardware and Architecture, Control and Systems Engineering, Signal Processing, Electrical and Electronic Engineering, single photon avalanche diode (SPAD), optical wireless communications (OWC), time-gated SPAD, optimal gate-ON time, background light
Abstract

Using a single photon avalanche diode (SPAD) as a receiver in an optical wireless communications (OWC) system can effectively expand the transmission distance. However, the performance of the SPAD receiver is usually affected with the bit error rate (BER) lower bound determined by background light and the inter-symbol interference (ISI) distortion caused by dead time. In this paper, external time-gated technology is employed, and the SPAD is only activated within the set gate-ON time to alleviate the influence of background light and ISI distortion. The SPAD photon counting model and the communication BER model are established according to the external time-gated characteristics. Considering the functional relationship among the gate-ON time, signal light flux, background light flux and blocking time, we take the minimum BER as the optimization target, the optimal gate-ON time is derived. The numerical results show that whenever the signal light flux or the background light flux is higher, the BER performance of the time-gated mode is apparently better than the free-running mode. For example, when signal photons and background photons are 30 and 10 per symbol time, respectively, the BER of free-running SPAD converges to 0.1, while the BER of the time-gated scheme is about 10−6.

Published
2022
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14. Determination of background, signal-to-noise, and dynamic range of a flow cytometer: A novel practical method for instrument characterization and standardization.

Author

Giesecke, Claudia, Feher, Kristen, von Volkmann, Konrad, Kirsch, Jenny, Radbruch, Andreas, and Kaiser, Toralf

Abstract

A well-defined scale calibration in flow cytometry can improve many aspects of data acquisition such as cytometer setup, instrument comparison and sample comparison. The theory for scale calibration was proposed by Steen over two decades ago, but it has never been put into regular use due to the lack of a widely available precision light source. The introduction of such a light source, the quantiFlashTM , gave this possibility. Here, we describe how this light source can be used to characterize a cytometer's PMT performance. We, therefore, characterized the instrument's response over the entire PMT voltage range. As a consequence, we propose a practical method to characterize a cytometer's signal-to-noise ratio (SNR) and dynamic range (DNR). This allows the selection of a voltage/gain corresponding to a PMT's maximum efficiency and hence the lowest electronic noise, which can help with experiment design. We further introduced a decibel (dB) scale for the presentation of SNR and DNR values. SNR and DNR are stand-alone values that allow the direct comparison of different instruments. Finally, with this method, it becomes clear that increased SNR comes at the expense of DNR and thus the limiting factor of modern cytometers is the DNR. © 2017 International Society for Advancement of Cytometry [ABSTRACT FROM AUTHOR]

Published
2017
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15. The extragalactic gamma-ray sky in the Fermi era.

Author

Massaro, Francesco, Thompson, David, and Ferrara, Elizabeth

Subjects
*GAMMA ray astronomy, *GAMMA ray bursts, *GALAXIES, *FERMI energy, UNIVERSE
Abstract

The Universe is largely transparent to $$\gamma $$ -rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After 7 years of operation, the Fermi Gamma-ray Space Telescope has produced a wealth of information about the high-energy sky. This review focuses on extragalactic $$\gamma $$ -ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the $$\gamma $$ -rays, as well as providing indirect measurements of the extragalactic background light and intergalactic magnetic fields. Population studies of the $$\gamma $$ -ray source classes compared to the extragalactic $$\gamma $$ -ray background place constraints on some models of dark matter. Ongoing searches for the nature of the large number of $$\gamma $$ -ray sources without obvious counterparts at other wavelengths remain an important challenge. [ABSTRACT FROM AUTHOR]

Published
2016
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16. Design of LED setup for measuring tandem solar cell subcell J-V behaviour

Author

Bergström, Kristina, Kamalmaz, Mohammed Nour, and Lindvall, Erik

Subjects
subcell, arduino, bias, LED, processing, background light, Tandem solar cell, Electrical Engineering, Electronic Engineering, Information Engineering, Elektroteknik och elektronik
Abstract

The need to accurately measure multi-junction (MJ) tandem solar cells' subcell current-voltage characteristics is increasing due to the vital information they provide about the efficiency, stability, and longevity of the cells. These measurements are rather difficult compared to their counterpart single-layer solar cell measurements. The purpose of this project is to construct an instrument that is able to successfully bias multiple subcells in a tandem solar cell. This would allow accurate measurements of the J-V behaviours of individual subcells within the stack and by extent, allow analysis to optimise future tandem cell technology. The instrument made is a controllable multi-chromatic light-emitting diode array, consisting of six wavelength-different LEDs ranging between ultraviolet and infrared light, which the intensity of is controlled bya slider control Graphical User Interface (GUI). This instrument will bemounted on a laboratory station at the institution of solar cell technology, Ångström laboratory. Although not perfect, the instrumentcan provide sufficient background light for biasing subcells of an MJ solar cell for a wide selection of cell band gaps

Published
2022

17. Fluorescence imaging under background light with a self-reset complementary metal–oxide–semiconductor image sensor

Author

Takahiro Yamaguchi, Yoshinori Sunaga, Makito Haruta, Mayumi Motoyama, Yasumi Ohta, Hiroaki Takehara, Toshihiko Noda, Kiyotaka Sasagawa, Takashi Tokuda, and Jun Ohta

Subjects
CMOS image sensors, biological techniques, fluorescence, proteins, fluorescence imaging, background light, self reset complementary metal–oxide–semiconductor image sensor, green fluorescence protein, brain slice, pixel saturation, Engineering (General). Civil engineering (General), TA1-2040
Abstract

The authors propose and demonstrate the fluorescence imaging of green fluorescence protein (GFP) expressed in a brain slice with a self-reset complementary metal–oxide–semiconductor image sensor under background light. By using a self-reset function to avoid pixel saturation, the weak fluorescence of GFP was successfully observed, even under background light. The result suggests that the sensor can be applied to in vivo imaging of laboratory animals during light–dark cycles, so that they can observe the different responses to bright and dark environments.

Published
2015
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18. Various stable spatial solitons based on photoisomerization.

Author

Jiang, X., Liang, J., Song, J., and Cai, Z.

Abstract

We find that gray solitons, dark solitons and bright solitons can stably propagate in organic polymer based on a single nonlinearity named photoisomerization. In order to obtain bright solitons in this negative nonlinear material, the wavelength of signal light should locate near the absorption valley of the organic material and meanwhile the wavelength of controlling light, a homogeneously distributed background light, should locate in the right side of absorption spectrum of the material. In addition, the background should be intense enough. All bright solitons can stably propagate in this material; nevertheless some of the gray solitons associated with photoisomerization are unstable. [ABSTRACT FROM AUTHOR]

Published
2016
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19. The extragalactic gamma-ray sky in the Fermi era.

Author

Massaro, Francesco, Thompson, David, and Ferrara, Elizabeth

Subjects
*EXTRAGALACTIC distances, *GAMMA rays, *PHOTONS, *STAR formation, *STELLAR spectra, *STAR observations
Abstract

The Universe is largely transparent to $$\gamma $$ -rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After 7 years of operation, the Fermi Gamma-ray Space Telescope has produced a wealth of information about the high-energy sky. This review focuses on extragalactic $$\gamma $$ -ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the $$\gamma $$ -rays, as well as providing indirect measurements of the extragalactic background light and intergalactic magnetic fields. Population studies of the $$\gamma $$ -ray source classes compared to the extragalactic $$\gamma $$ -ray background place constraints on some models of dark matter. Ongoing searches for the nature of the large number of $$\gamma $$ -ray sources without obvious counterparts at other wavelengths remain an important challenge. [ABSTRACT FROM AUTHOR]

Published
2015
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20. How to Report Light Exposure in Human Chronobiology and Sleep Research Experiments

Author

Oliver Stefani, Steven W. Lockley, Robert J. Lucas, Claude Gronfier, Manuel Spitschan, and Peter Blattner

Subjects
medicine.medical_specialty, retina, Spectral power distribution, Computer science, 0211 other engineering and technologies, 02 engineering and technology, Audiology, Stimulus (physiology), reproducible research, Article, 03 medical and health sciences, environmental psychology, light exposure, 0302 clinical medicine, 021105 building & construction, medicine, Sleep research, sleep research, General Environmental Science, Light exposure, Chronobiology, reporting, Light sensitivity, Illuminance, non-visual function, General Earth and Planetary Sciences, Background light, chronobiology, 030217 neurology & neurosurgery
Abstract

Exposure to light has short- and long-term impacts on non-visual responses in humans. While many aspects related to non-visual light sensitivity have been characterised (such as the action spectrum for melatonin suppression), much remains to be elucidated. Here, we provide a set of minimum reporting guidelines for reporting the stimulus conditions involving light as an intervention in chronobiology, sleep research and environmental psychology experiments. Corresponding to the current state-of-the-art knowledge (June 2019), these are (i) measure and report the spectral power distribution of the acute stimulus from the observer’s point of view; (ii) measure and report the spectral power distribution of the background light environment from the observer’s point of view; (iii), make spectra available in tabulated form, (iv) report α-opic (ir)radiances and illuminance; (v) describe the timing properties of stimulus (duration and pattern); (vi) describe the spatial properties of stimulus (spatial arrangement and extent), and (vii) report measurement conditions and equipment. We supplement the minimum reporting guidelines with optional reporting suggestions and discuss limitations of the reporting scheme.

Published
2019

21. Light Attenuation Display: Subtractive See-Through Near-Eye Display via Spatial Color Filtering

Author

Tobias Langlotz, Kiyoshi Kiyokawa, Daisuke Iwai, Yuta Itoh, and Toshiyuki Amano

Subjects
Image formation, Eye Movements, Optical Phenomena, Computer science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Color, 02 engineering and technology, law.invention, Rendering (computer graphics), User-Computer Interface, Optics, law, Color gel, Computer Graphics, 0202 electrical engineering, electronic engineering, information engineering, Humans, ComputingMethodologies_COMPUTERGRAPHICS, Birefringence, Liquid-crystal display, Spatial light modulator, Subtractive color, Pixel, business.industry, Attenuation, Virtual Reality, Optical Devices, 020207 software engineering, Optical polarization, Equipment Design, Computer Graphics and Computer-Aided Design, Virtual image, Signal Processing, Computer Vision and Pattern Recognition, Background light, business, Software
Abstract

We present a display for optical see-through near-eye displays based on light attenuation, a new paradigm that forms images by spatially subtracting colors of light. Existing optical see-through head-mounted displays (OST-HMDs) form virtual images in an additive manner-they optically combine the light from an embedded light source such as a microdisplay into the users' field of view (FoV). Instead, our light attenuation display filters the color of the real background light pixel-wise in the users' see-through view, resulting in an image as a spatial color filter. Our image formation is complementary to existing light-additive OST-HMDs. The core optical component in our system is a phase-only spatial light modulator (PSLM), a liquid crystal module that can control the phase of the light in each pixel. By combining PSLMs with polarization optics, our system realizes a spatially programmable color filter. In this paper, we introduce our optics design, evaluate the spatial color filter, consider applications including image rendering and FoV color control, and discuss the limitations of the current prototype.

Published
2019

22. The importance of including position and viewing direction when measuring and assessing the lighting conditions of office workers

Author

Helianthe Kort, Mariëlle P.J. Aarts, J. van Duijnhoven, Building Lighting, Building Performance, and Health in the Built Environment

Subjects
Adult, Light, Computer science, SDG 3 – Goede gezondheid en welzijn, Office workers, SDG 3 - Good Health and Well-being, Human–computer interaction, Humans, Attention, Workplace, Lighting, alertness, Netherlands, Measure (data warehouse), Computers, Rehabilitation, Public Health, Environmental and Occupational Health, Individual level, personal lighting conditions, Alertness, ergonomics, Sunlight, Position (finance), Light measurements, Background light, non-image-forming effects, Research Article
Abstract

BACKGROUND:Light and alertness studies have applied different measurement methodologies to determine lighting conditions. However, it has been demonstrated that researchers rarely measure or describe the lighting conditions of their studies in sufficient detail to generalize conclusions or derive universal guidelines.OBJECTIVE:Part I of this paper summarizes the current measurement methodologies used in light and alertness studies to potentially identify methodological issues. Part II determines the differences in lighting conditions for different viewing directions within an office environment.METHODS:A literature review (part I) and both experimental studies and an observational study (part II) were undertaken in this study.RESULTS:Part I demonstrates that most light and alertness studies include photometric quantities; however, it is recommended that one should measure radiometric quantities as well. Further, the light measurements should be performed at the individual level. Part II demonstrates large differences in lighting conditions between viewing directions. For example, when looking toward the window, vertical illuminances were at least 12 times higher when compared to looking in the opposite direction.CONCLUSIONS:Our findings suggest that when analysing or designing an office environment, office workers’ positions and viewing direction should be included in the determination of personal lighting conditions.

Published
2019

23. Introductory survey for wireless infrared communications

Author

Munsif Ali Jatoi and Nidal Kamel

Subjects
optical links, optical transmitters, optical receivers, error correction, decoding, error statistics, wireless infrared communications, free space optical links, infrared radiation, link configurations, transmitter efficiency, receiver responsivity, background light, field theory, bit error rate, signal-to-noise ratio, wavelength 400 nm to 700 nm, Engineering (General). Civil engineering (General), TA1-2040
Abstract

Wireless infrared communications can be defined as the propagation of light waves in free space using infrared radiation whose range is 400–700 nm. This range corresponds to frequencies of hundreds of terahertz, which is high for higher data rate applications. Wireless infrared is applied for higher data rates applications such as wireless computing, wireless video and wireless multimedia communication applications. Introduced by Gfeller, this field has grown with different link configurations, improved transmitter efficiency, increased receiver responsivity and various multiple access techniques for improved quality. Errors are caused because of background light, which causes degradation overall system performance. Error correction techniques are used to remove the errors caused during transmission. This study provides a brief account on field theory used for error correction in wireless infrared systems. The results are produced in terms of bit error rate and signal-to-noise ratio for various bit lengths to show the ability of encoding and decoding algorithms.

Published
2014
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24. Large-Scale Fabrication of Photonic Nanojet Array via Template-Assisted Self-Assembly

Author

Pengcheng Zhang, Xi Chen, and Hui Yang

Subjects
Materials science, Fabrication, lcsh:Mechanical engineering and machinery, Physics::Optics, template-assisted self-assembly, 02 engineering and technology, Photonic nanojet, 01 natural sciences, Article, Microsphere, 010309 optics, 0103 physical sciences, Nano, lcsh:TJ1-1570, Electrical and Electronic Engineering, patterning efficiency, business.industry, Mechanical Engineering, self-assembly, 021001 nanoscience & nanotechnology, Template, Control and Systems Engineering, photonic nanojet, Optoelectronics, Self-assembly, Background light, Photonics, 0210 nano-technology, business, photonic nanojet array
Abstract

A large-scale homogenized photonic nanojet array with defined pattern and spacing facilitates practical applications in super-resolution imaging, subwavelength-resolution nanopatterning, nano objects trapping and detection technology. In this paper, we present the fabrication of a large-scale photonic nanojet array via the template-assisted self-assembly (TASA) approach. Templates of two-dimensional (2D) large-scale microwell array with defined pattern and spacing are fabricated. Melamine microspheres with excellent size uniformity are utilized to pattern on the template. It is found that microwells can be filled at a yield up to 95%. These arrayed microspheres on the template serve as microlenses and can be excited to generate large-scale photonic nanojets. The uniformly-sized melamine spheres are beneficial for the generation of a homogenized photonic nanojet array. The intensity of the photonic nanojets in water is as high as ~2 fold the background light signal. Our work shows a simple, robust, and fast means for the fabrication of a large-scale homogenized photonic nanojet array.

Published
2020

26. The PAU survey:background light estimation with deep learning techniques

Author

Enrique Fernández, Ramon Miquel, Juan Garcia-Bellido, Martin Eriksen, A. Alarcon, M. Siudek, I. Sevilla-Noarbe, C. Neissner, J. Carretero, Ricard Casas, S. Serrano, Enrique Gaztanaga, C. Padilla, Pau Tallada, Adam Amara, Luca Tortorelli, F. J. Castander, Henk Hoekstra, E. J. Sanchez, L. Cabayol-Garcia, European Commission, European Research Council, Ministerio de Economía y Competitividad (España), and Generalitat de Catalunya

Subjects
Physics, 010308 nuclear & particles physics, photometric [Techniques], FOS: Physical sciences, Library science, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, photometers [Instrumentation], Light pollution, Space and Planetary Science, 0103 physical sciences, media_common.cataloged_instance, European union, Background light, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common
Abstract

In any imaging survey, measuring accurately the astronomical background light is crucial to obtain good photometry. This paper introduces BKGNET, a deep neural network to predict the background and its associated error. BKGNET has been developed for data from the Physics of the Accelerating Universe Survey (PAUS), an imaging survey using a 40 narrow-band filter camera (PAUCam). The images obtained with PAUCam are affected by scattered light: an optical effect consisting of light multiply reflected that deposits energy in specific detector regions affecting the science measurements. Fortunately, scattered light is not a random effect, but it can be predicted and corrected for. We have found that BKGNET background predictions are very robust to distorting effects, while still being statistically accurate. On average, the use of BKGnet improves the photometric flux measurements by 7 per cent and up to 20 per cent at the bright end. BKGNET also removes a systematic trend in the background error estimation with magnitude in the i band that is present with the current PAU data management method. With BKGNET, we reduce the photometric redshift outlier rate by 35 per cent for the best 20 per cent galaxies selected with a photometric quality parameter., Funding for PAUS has been provided by Durham University (via the ERC StG DEGAS-259586), ETH Zurich, Leiden University (via ERC StG ADULT-279396 and Netherlands Organisation for Scientific Research (NWO) Vici grant 639.043.512) and University College London. The PAUS participants from Spanish institutions are partially supported by MINECO under grants CSD2007-00060, AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IEEC and IFAE are partially funded by the CERCA program of the Generalitat de Catalunya. The PAU data center is hosted by the Port d’Informacio Cientifica (PIC), maintained through a collaboration of CIEMAT and IFAE, with additional support from Universitat Autonoma de Barcelona and ERDF. CosmoHub has been developed by PIC and was partially funded by the ‘Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion program of the Spanish government. We gratefully acknowledge the support of NVIDIA Corporation with the donation of the Titan V GPU used for this research. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776247. AA is supported by a Royal Society Wolfson Fellowship. MS has been supported by the National Science Centre (grant UMO2016/23/N/ST9/02963).

Published
2020

27. Improvement of the signal to noise ratio of Lidar echo signal based on wavelet de-noising technique.

Author

Zhou, Zhirong, Hua, Dengxin, Wang, Yufeng, Yan, Qing, Li, Shichun, Li, Yan, and Wang, Hongwei

Subjects
*SIGNAL-to-noise ratio, *LIDAR, *SIGNAL processing, *WAVELET transforms, *SIMULATION methods & models, *FEASIBILITY studies
Abstract

Abstract: According to the characteristics of a Lidar echo signal contaminated by noise, especially in strong background light, an effective de-noising method of wavelets based on a soft threshold is proposed to reduce the Lidar echo signal noise and improve the signal to noise ratio of system. The principles and methods of wavelet transforms and wavelet de-noising are utilized to de-noise the noisy signals. Some preliminary simulations are carried out to reduce the noise of the simulated signals in order to verify the feasibility of the de-noising method. In addition, using experimental data of the Lidar echo signals contaminated by noise in the strong background light, the de-noising range-square-corrected signals and the retrieved aerosol extinction coefficient are obtained. The results show evidence of the de-noising effects and demonstrate that this method can effectively de-noise the noisy Lidar signals in strong background light and achieve improvement in the signal to noise ratio of system. [Copyright &y& Elsevier]

Published
2013
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28. Research on PWMapplied inwater turbiditymeasurement.

Author

Kai Zhang, Yu-jun Zhang, Gao-fang Yin, Zhi-gang Wang, Chao-yi Shi, Xue Xiao, Huan-bo Wang, Jing-bo Duan, Nan-jing Zhao, and Wen-qing Liu

Subjects
*TURBIDITY, *PULSE width modulation, *MICROCONTROLLERS, *SCATTERING (Physics), *STANDARD deviations, *DEMODULATION, *ELECTRIC circuit analysis
Abstract

ABSTRACT In this paper, three common measuring methods for the principles of water turbidity, namely, scattering, transmission and the ratio method are introduced. A method combined with modulation and demodulation techniques based on pulse width modulation (PWM) pulse for turbidity measurement using light intensity modulation is proposed. The experimental system that is, the realizing circuit of modulation and demodulation is described in detail. The experimental system was used to measure Formazine Standard Solution turbidity of different values. The experimental results are shown, and then turbidity values are calculated using the three methods. Through the analysis and comparison of the experimental results, it is shown that when using the ratio method combined with the modulation technique, the interference of background light can be eliminated effectively, so the measuring accuracy is significantly improved. [ABSTRACT FROM AUTHOR]

Published
2011
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29. Imaging of diffuse HI absorption structure in the SSA22 protocluster region at z = 3.1

Author

Yuichi Matsuda, Akio K. Inoue, Masami Ouchi, Shiro Mukae, Takuya Otsuka, Hideki Umehata, Tomoki Hayashino, Toru Yamada, and Ken Mawatari

Subjects
Physics, COSMIC cancer database, Field (physics), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Galaxy, Space and Planetary Science, galaxies: high-redshift, Intergalactic medium, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, intergalactic medium, large-scale structure of Universe, Background light, Absorption (electromagnetic radiation), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Using galaxies as background light sources to map intervening Lya absorption is a novel approach to study the interplay among galaxies, the circum-galactic medium (CGM), and the intergalactic medium (IGM). Introducing a new measure of z = 3.1$ HI Lya absorption relative to the cosmic mean, Delta_NB497, estimated from photometric data of star-forming galaxies at 3.3 < z < 3.5, we have made two-dimensional Delta_NB497 maps in the z = 3.1 SSA22 proto-cluster region and two control fields (SXDS and GOODS-N fields) with a spatial resolution of ~ 5 comoving Mpc. The Delta_NB497 measurements in the SSA22 field are systematically larger than those in the control fields, and this HI absorption enhancement extends more than 50 comoving Mpc. The field-averaged (i.e., ~50 comoving Mpc scale) Delta_NB497 and the overdensity of Lya emitters (LAEs) seem to be correlated, while there is no clear dependency of the Delta_NB497 on the local LAE overdensity in a few comoving Mpc scale. These results suggest that diffuse HI gas spreads out in/around the SSA22 proto-cluster. We have also found an enhancement of Delta_NB497 at a projected distance < 100 physical kpc from the nearest z = 3.1 galaxies at least in the SSA22 field, which is probably due to HI gas associated with the CGM of individual galaxies. The HI absorption enhancement in the CGM-scale tends to be weaker around galaxies with stronger Lya emission, which suggests that the Lya escape fraction from galaxies depends on hydrogen neutrality in the CGM., 13 pages, 11 figures, 1 table, accepted to MNRAS

Published
2017

30. Wireless optical communications via diversity reception and optical preamplification.

Author

Razavi, M. and Shapiro, J.H.

Abstract

Atmospheric optical communication systems that use optical preamplifiers and diversity reception are addressed. The particular diversity techniques that are investigated include aperture averaging, linear combining, and adaptive optics. On-off keying and binary pulse position modulation are considered. The effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, and receiver thermal noise are studied in the context of a semiclassical photon-counting approach. Numerical results are presented using a conditional Gaussian approximation method. By this method, we can measure the power penalty incurred under various operating conditions as well as the link margin improvement due to optical preamplification and diversity reception. [ABSTRACT FROM PUBLISHER]

Published
2005
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31. The influence of ambient room lighting on the pattern electroretinogram (PERG).

Author

Bach, Michael and Schumacher, Margret

Abstract

It has been suggested that low ambient lighting conditions increase the amplitude of the PERG, but no data has been available on this issue. We recorded the transient PERG (0.8° check size) and steady-state PERG (15 rev/s, 0.8° and 16° check size) under three lighting conditions: dark room, only illuminated by the stimulus (resulting in 30 lux), our standard room lighting (windows occluded, one lighted lamp, 200 lux) and fully lit room (full ceiling illumination with eight fluorescent tubes) resulting in rather bright 2300 lux. The stimulus luminance was 50 cd/m2. The sequence of lighting conditions varied for each subject and followed a balanced permutation of an ABCCBA scheme. Results showed a significant effect (P<0.01) across lighting conditions, with no relevant difference between the 30 and 200 lux conditions, but a reduction down to 70% at the 2300 lux condition. This obtained across all check sizes and temporal conditions. As an example, the transient PERG P50-amplitudes were as follows: dark, 5.6±0.8 μV; medium, 5.3±0.6 μV and bright, 3.8± μV (mean ± SEM). Peak times decreased significantly with illumination (dark, medium or bright): 45.9±0.9, 43.1±0.6 or 40.8±0.8 ms. Contrast measurements quantitatively explained the noticeable reduction of PERG amplitude at the brightest illumination level simply by straylight, which reduced the display contrast. This suggests that bright sunlight should be excluded, and that lighting conditions should be moderately standardized at low or medium luminance levels for reproducible amplitudes and peak times. [ABSTRACT FROM AUTHOR]

Published
2002
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33. Compensation method of PSD's background light based on improved BP neural network.

Author

Zhang, Feimeng, Li, Yi, Li, Hao, and Gu, Guo-hua

Abstract

Position sensitive detector (PSD) is an optoelectronic device that can directly detect the position of the spot light on its photosensitive surface. It is commonly used in non-contact precision dynamic displacement detection. According to the principle and the characteristic equation of the PSD, the existence of the characteristics of the PSD output signal when the backlight based on neural network of the PSD background optical nonlinear compensation method is proposed to improve the detection accuracy and reliability. The simulation shows that this method can effectively eliminate the influence of background light. [ABSTRACT FROM PUBLISHER]

Published
2012
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38. Red fluorescence of the triplefin Tripterygion delaisi is increasingly visible against background light with increasing depth

Author

Ulrike K. Harant, Nico K. Michiels, Shelby E. Temple, Roland Fritsch, Connor M. Champ, and Pierre-Paul Bitton

Subjects
0106 biological sciences, 0301 basic medicine, genetic structures, Tripterygion delaisi, Intraspecific signal, 010603 evolutionary biology, 01 natural sciences, Fluorescence, 03 medical and health sciences, Optics, 14. Life underwater, visual model, Absorption (electromagnetic radiation), lcsh:Science, Red fluorescence, Photoreceptor, Multidisciplinary, biology, Ecology, business.industry, visual communication, Visual model, intraspecific signal, Biology (Whole Organism), biology.organism_classification, photoreceptor, Wavelength, 030104 developmental biology, lcsh:Q, fluorescence, Background light, business, Visual communication, Research Article
Abstract

The light environment in water bodies changes with depth due to the absorption of short and long wavelengths. Below 10 m depth, red wavelengths are almost completely absent rendering any red-reflecting animal dark and achromatic. However, fluorescence may produce red coloration even when red light is not available for reflection. A large number of marine taxa including over 270 fish species are known to produce red fluorescence, yet it is unclear under which natural light environment fluorescence contributes perceptively to their colours. To address this question we: (i) characterized the visual system ofTripterygion delaisi,which possesses fluorescent irides, (ii) separated the colour of the irides into its reflectance and fluorescence components and (iii) combined these data with field measurements of the ambient light environment to calculate depth-dependent perceptual chromatic and achromatic contrasts using visual modelling. We found that triplefins have cones with at least three different spectral sensitivities, including differences between the two members of the double cones, giving them the potential for trichromatic colour vision. We also show that fluorescence contributes increasingly to the radiance of the irides with increasing depth. Our results support the potential functionality of red fluorescence, including communicative roles such as species and sex identity, and non-communicative roles such as camouflage.

Published
2017

39. Galaxy Zoo: A Catalog of Overlapping Galaxy Pairs for Dust Studies

Author

William C. Keel, Anna M. Manning, Benne W. Holwerda, Massimo Mezzoprete, Chris J. Lintott, Kevin Schawinski, Pamela Gay, and Karen L. Masters

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Extinction (astronomy), Galaxy type, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy, Space and Planetary Science, Sky, 0103 physical sciences, Surface brightness, Background light, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, media_common, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Analysis of galaxies with overlapping images offers a direct way to probe the distribution of dust extinction and its effects on the background light. We present a catalog of 1990 such galaxy pairs selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the Galaxy Zoo project. We highlight subsamples which are particularly useful for retrieving such properties of the dust distribution as UV extinction, the extent perpendicular to the disk plane, and extinction in the inner parts of disks. The sample spans wide ranges of morphology and surface brightness, opening up the possibility of using this technique to address systematic changes in dust extinction or distribution with galaxy type. This sample will form the basis for forthcoming work on the ranges of dust distributions in local disk galaxies, both for their astrophysical implications and as the low-redshift part of a study of the evolution of dust properties. Separate lists and figures show deep overlaps, where the inner regions of the foreground galaxy are backlit, and the relatively small number of previously-known overlapping pairs outside the SDSS DR7 sky coverage., Comment: PASP, in press. Full catalog and additional data are available at http://data.galaxyzoo.org/overlaps.html

Published
2016

40. The extragalactic gamma-ray sky in the Fermi era

Author

Francesco Massaro, D. J. Thompson, and Elizabeth C. Ferrara

Subjects
Active galactic nucleus, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Extragalactic astronomy, 0103 physical sciences, BL Lac objects, 010306 general physics, Blazar, 010303 astronomy & astrophysics, Quasars, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Active galactic nuclei, Gamma rays , Extragalactic astronomy , Active galactic nuclei , Quasars , BL Lac objects , Background light, Gamma rays, Astronomy and Astrophysics, Galaxy, Extragalactic background light, Space and Planetary Science, Background light, Intergalactic travel, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

The Universe is largely transparent to $\gamma$ rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After seven years of operation, the Fermi {\it Gamma-ray Space Telescope} has produced a wealth of information about the high-energy sky. This review focuses on extragalactic $\gamma$-ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the $\gamma$ rays, as well as providing indirect measurements of the extragalactic background light and intergalactic magnetic fields. Population studies of the $\gamma$-ray source classes compared to the extragalactic $\gamma$-ray background place constraints on some models of dark matter. Ongoing searches for the nature of the large number of $\gamma$-ray sources without obvious counterparts at other wavelengths remains an important challenge., Comment: 61 pages, 23 figures, 3 tables, Accepted for publication on Astronomy and Astrophysics Review (pre-proof version)

Published
2016

41. Fluorescence imaging under background light with a self-reset complementary metal–oxide–semiconductor image sensor

Author

Jun Ohta, Kiyotaka Sasagawa, Takahiro Yamaguchi, Yoshinori Sunaga, Makito Haruta, Takashi Tokuda, Toshihiko Noda, Hiroaki Takehara, Yasumi Ohta, and Mayumi Motoyama

Subjects
Fluorescence-lifetime imaging microscopy, Materials science, genetic structures, Energy Engineering and Power Technology, CMOS image sensors, Green fluorescent protein, Optics, Slice preparation, fluorescence imaging, background light, Image sensor, Pixel, business.industry, fungi, General Engineering, biological techniques, Fluorescence, pixel saturation, proteins, green fluorescence protein, brain slice, CMOS, lcsh:TA1-2040, Optoelectronics, self reset complementary metal–oxide–semiconductor image sensor, fluorescence, business, lcsh:Engineering (General). Civil engineering (General), Software, Preclinical imaging
Abstract

The authors propose and demonstrate the fluorescence imaging of green fluorescence protein (GFP) expressed in a brain slice with a self-reset complementary metal–oxide–semiconductor image sensor under background light. By using a self-reset function to avoid pixel saturation, the weak fluorescence of GFP was successfully observed, even under background light. The result suggests that the sensor can be applied to in vivo imaging of laboratory animals during light–dark cycles, so that they can observe the different responses to bright and dark environments.

Published
2015

42. Rapid determination of leaf area and plant height by using light curtain arrays in four species with contrasting shoot architecture

Author

Andreas Ulbrich, Ulrich Schurr, Christoph Briese, Alexander Putz, Fabio Fiorani, Silke Kleinen, Dimitrios Fanourakis, and Johannes Fj Max

Subjects
Rapeseed, Shoot profile, Methodology, Overlapping plants, Plant Science, 15. Life on land, Leaf area estimation, Sensor-to-plant system, Data set, ddc:580, Phenotyping, Maximum height estimation, Sensor speed, Shoot silhouette, Shoot, Botany, Genetics, Background light, Biological system, Multiple view, Biotechnology, Mathematics
Abstract

Background Light curtain arrays (LC), a recently introduced phenotyping method, yield a binary data matrix from which a shoot silhouette is reconstructed. We addressed the accuracy and applicability of LC in assessing leaf area and maximum height (base to the highest leaf tip) in a phenotyping platform. LC were integrated to an automated routine for positioning, allowing in situ measurements. Two dicotyledonous (rapeseed, tomato) and two monocotyledonous (maize, barley) species with contrasting shoot architecture were investigated. To evaluate if averaging multiple view angles helps in resolving self-overlaps, we acquired a data set by rotating plants every 10° for 170°. To test how rapid these measurements can be without loss of information, we evaluated nine scanning speeds. Leaf area of overlapping plants was also estimated to assess the possibility to scale this method for plant stands. Results The relation between measured and calculated maximum height was linear and nearly the same for all species. Linear relations were also found between plant leaf area and calculated pixel area. However, the regression slope was different between monocotyledonous and dicotyledonous species. Increasing the scanning speed stepwise from 0.9 to 23.4 m s−1 did not affect the estimation of maximum height. Instead, the calculated pixel area was inversely proportional to scanning speed. The estimation of plant leaf area by means of calculated pixel area became more accurate by averaging consecutive silhouettes and/or increasing the angle between them. Simulations showed that decreasing plant distance gradually from 20 to 0 cm, led to underestimation of plant leaf area owing to overlaps. This underestimation was more important for large plants of dicotyledonous species and for small plants of monocotyledonous ones. Conclusions LC offer an accurate estimation of plant leaf area and maximum height, while the number of consecutive silhouettes that needs to be averaged is species-dependent. A constant scanning speed is important for leaf area estimations by using LC. Simulations of the effect of varying plant spacing gave promising results for method application in sets of partly overlapping plants, which applies also to field conditions during and after canopy closure for crops sown in rows.

Published
2014

43. Determination of the Point-spread Function for the Fermi Large Area Telescope from On-orbit Data and Limits on Pair Halos of Active Galactic Nuclei

Author

G. Busetto, Brian L Winer, S. Cutini, A. A. Moiseev, Katsuaki Asano, Francesco Longo, Gudlaugur Johannesson, F. Loparco, E. Do Couto E Silva, W. Mitthumsiri, T. A. Porter, A. P. Waite, T. J. Brandt, Jean Ballet, Stefan Funk, Daniel Sánchez, Claudia Lavalley, Sho Nishino, Alex Drlica-Wagner, Justin Vandenbroucke, T. E. Stephens, A. Morselli, V. Vitale, Jeffrey D. Scargle, P. Fusco, Stefano Ciprini, Igor V. Moskalenko, Matthew Kerr, A. W. Borgland, I. A. Grenier, S. Germani, T. Ohsugi, Eleonora Troja, Miranda Jackson, Nicola Omodei, Guido Barbiellini, S. J. Fegan, Olaf Reimer, Zhenwei Yang, Elliott D. Bloom, G. Godfrey, Kent S. Wood, T. Jogler, Carmelo Sgrò, Riccardo Rando, Soebur Razzaque, Jay P. Norris, M. Razzano, P. Fortin, L. S. Rochester, C. Favuzzi, V. Vasileiou, R. Claus, Matthew Wood, Stephan Zimmer, J. F. Ormes, N. Gehrels, James Chiang, Hiroyasu Tajima, Gino Tosti, Jan Conrad, F. de Palma, R. E. Hughes, E. Wallace, Dario Gasparrini, Patrick Weltevrede, E. Nuss, Paola Grandi, P. Lubrano, Hiromitsu Takahashi, M. Brigida, Sylvain Chaty, A. Chekhtman, David Paneque, Claudia Cecchi, S. Rainò, J. G. Thayer, T. Kamae, Tsunefumi Mizuno, Randall P. Johnson, Rodrigo Nemmen, R. Dubois, E. Orlando, J. M. Casandjian, D. Horan, F. D'Ammando, W. B. Focke, M. Kuss, C. Monte, M. E. Monzani, Gloria Spandre, P. Spinelli, M. N. Mazziotta, Jun Kataoka, Pascal Bruel, J. Mehault, Emanuele Bonamente, R. Buehler, J. E. Grove, S. Larsson, T. L. Usher, Francesco Giordano, D. J. Thompson, Daniela Hadasch, M. Roth, Yasushi Fukazawa, T. H. Burnett, A. S. Johnson, M. Orienti, S. Murgia, O. Tibolla, Benoit Lott, Peter F. Michelson, Marcello Giroletti, Takaaki Tanaka, F. Piron, A. Snyder, Keith Bechtol, Johan Bregeon, Johann Cohen-Tanugi, Alice Allafort, Roberto Mignani, Eric Charles, Julie McEnery, Morihiro Hayashida, E. Hays, Steven Ritz, D. J. Suson, C. C. Cheung, W. McConville, L. C. Reyes, Marco Ajello, J. B. Thayer, M. Naumann-Godo, L. Tibaldo, W. B. Atwood, J. S. Perkins, Nicola Giglietto, F. Gargano, Luca Latronico, G. A. Caliandro, H. Poon, S. Colafrancesco, M. N. Lovellette, P. A. Caraveo, Persis S. Drell, M. Tinivella, Elizabeth C. Ferrara, V. Pelassa, E. J. Siskind, J. H. Panetta, Markus Ackermann, A. N. Cillis, R. A. Cameron, Luca Baldini, M. Pierbattista, Denis Bastieri, A. von Kienlin, C. Romoli, J. Lande, Sylvain Guiriec, A. Reimer, S. Buson, P. M. Saz Parkinson, Suk-Han Lee, Melissa Pesce-Rollins, T. Glanzman, Jürgen Knödlseder, G. Pivato, Eugenio Bottacini, Charles D. Dermer, X. Hou, Giacomo Vianello, Ronaldo Bellazzini, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Istituto Nazionale di Fisica Nucleare, sezione di Bari (INFN, sezione di Bari), Istituto Nazionale di Fisica Nucleare (INFN), GLAST, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Ackermann, M., Ajello, M., Allafort, A., Asano, K., Atwood, W. B., Baldini, L., Ballet, J., BARBIELLINI AMIDEI, Guido, Bastieri, D., Bechtol, K., Bellazzini, R., Bloom, E. D., Bonamente, E., Borgland, A. W., Bottacini, E., Brandt, T. J., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Burnett, T. H., Busetto, G., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Casandjian, J. M., Cecchi, C., Charles, E., Chaty, S., Chekhtman, A., Cheung, C. C., Chiang, J., Cillis, A. N., Ciprini, S., Claus, R., Cohen Tanugi, J., Colafrancesco, S., Conrad, J., Cutini, S., D'Ammando, F., de Palma, F., Dermer, C. D., Silva, E. do Couto e., Drell, P. S., Drlica Wagner, A., Dubois, R., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Fortin, P., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grandi, P., Grenier, I. A., Grove, J. E., Guiriec, S., Hadasch, D., Hayashida, M., Hays, E., Horan, D., Hou, X., Hughes, R. E., Jackson, M. S., Jogler, T., Jóhannesson, G., Johnson, R. P., Johnson, A. S., Kamae, T., Kataoka, J., Kerr, M., Knödlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lavalley, C., Lee, S. H., Longo, Francesco, Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Mazziotta, M. N., Mcconville, W., Mcenery, J. E., Mehault, J., Michelson, P. F., Mignani, R. P., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Naumann Godo, M., Nemmen, R., Nishino, S., Norris, J. P., Nuss, E., Ohsugi, T., Omodei, N., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Panetta, J. H., Pelassa, V., Perkins, J. S., Pesce Rollins, M., Pierbattista, M., Piron, F., Pivato, G., Poon, H., Porter, T. A., Rainò, S., Rando, R., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Reyes, L. C., Ritz, S., Rochester, L. S., Romoli, C., Roth, M., Sanchez, D. A., Saz Parkinson, P. M., Scargle, J. D., Sgrò, C., Siskind, E. J., Snyder, A., Spandre, G., Spinelli, P., Stephens, T. E., Suson, D. J., Tajima, H., Takahashi, H., Tanaka, T., Thayer, J. G., Thayer, J. B., Thompson, D. J., Tibaldo, L., Tibolla, O., Tinivella, M., Tosti, G., Troja, E., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vianello, G., Vitale, V., von Kienlin, A., Waite, A. P., Wallace, E., Weltevrede, P., Winer, B. L., Wood, K. S., Wood, M., Yang, Z., Zimmer, S., Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Ackermann M, Ajello M, Allafort A, Asano K, Atwood WB, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Bloom ED, Bonamente E, Borgland AW, Bottacini E, Brandt TJ, Bregeon J, Brigida M, Bruel P, Buehler R, Burnett TH, Busetto G, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Charles E, Chaty S, Chekhtman A, Cheung CC, Chiang J, Cillis AN, Ciprini S, Claus R, Cohen-Tanugi J, Colafrancesco S, Conrad J, Cutini S, DAmmando F, de Palma F, Dermer CD, Silva EDE, Drell S, Drlica-Wagner A, Dubois R, Favuzzi C, Fegan SJ, Ferrara EC, Focke WB, Fortin P, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grandi P, Grenier IA, Grove JE, Guiriec S, Hadasch D, Hayashida M, Hays E, Horan D, Hou X, Hughes RE, Jackson MS, Jogler T, Johannesson G, Johnson RP, Johnson AS, Kamae T, Kataoka J, Kerr M, Knodlseder J, Kuss M, Lande J, Larsson S, Latronico L, Lavalley C, Lee SH, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Mazziotta MN, McConville W, McEnery JE, Mehault J, Michelson PF, Mignani RP, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Naumann-Godo M, Nemmen R, Nishino S, Norris JP, Nuss E, Ohsugi T, Omodei N, Orienti M, Orlando E, Ormes JF, Paneque D, Panetta JH, Pelassa V, Perkins JS, Pesce-Rollins M, Pierbattista M, Piron F, Pivato G, Poon H, Porter TA, Raino S, Rando R, Razzano M, Razzaque S, Reimer A, Reimer O, Reyes LC, Ritz S, Rochester LS, Romoli C, Roth M, Sanchez DA, Parkinson PMS, Scargle JD, Sgro C, Siskind EJ, Snyder A, Spandre G, Spinelli P, Stephens TE, Suson DJ, Tajima H, Takahashi H, Tanaka T, Thayer JG, Thayer JB, Thompson DJ, Tibaldo L, Tibolla O, Tinivella M, Tosti G, Troja E, Usher TL, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, von Kienlin A, Waite AP, Wallace E, Weltevrede P, Winer BL, Wood KS, Wood M, Yang Z, Zimmer S, National Institute for Nuclear Physics (INFN), and Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ciencias Físicas, EXTRAGALACTIC MAGNETIC-FIELDS, halo [galaxies], galaxies: halos, Astrophysics, 01 natural sciences, galaxies, [gamma rays], law.invention, Spitzer Space Telescope, law, 1ES 0229+200, SPACE-TELESCOPE, 010303 astronomy & astrophysics, Physics, TEV BLAZARS, detector [instrumentation], [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::Instrumentation and Methods for Astrophysics, detectors, intergalactic medium [instrumentation], VHE GAMMA-RAYS, galaxies: active – galaxies: halos – gamma rays: galaxies – instrumentation: detectors – intergalactic medium, halos [galaxies], active [galaxies], intergalactic medium, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Point spread function, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, Astrophysics::Cosmology and Extragalactic Astrophysics, Telescope, 0103 physical sciences, gamma rays: galaxies, instrumentation: detectors, galaxie [gamma rays], Blazar, SOURCE CATALOG, Astrophysics::Galaxy Astrophysics, BACKGROUND LIGHT, 010308 nuclear & particles physics, Astronomy, CONSTRAINTS, Astronomy and Astrophysics, Quasar, PULSAR, Galaxy, DISCOVERY, Astronomía, Space and Planetary Science, ddc:520, Fermi Gamma-ray Space Telescope
Abstract

The astrophysical journal 765(1), 54 (2013). doi:10.1088/0004-637X/765/1/54, The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from ≈20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of γ rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broader than the pre-launch PSF. We checked for dependence of the PSF on the class of γ-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. We found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229+200 and 1ES0347–121, Published by Univ.11032, Chicago, Ill. [u.a.]

Published
2013

44. Deep-Sea Bioluminescence Blooms after Dense Water Formation at the Ocean Surface

Author

LO PRESTI, Domenico, Christian, Tamburini, Canals, M, Durrieu de Madron, X, Houpert, L, Lefe`vre, D, Se´verine, Martini1, 2, Fabrizio, D’Ortenzio5, Anne, Robert1, Pierre, Testor6, Juan Antonio Aguilar7, Imen Al Samarai8, Arnaud, Albert9, Michel Andre´ 10, Marco, Anghinolfi11, Gisela, Anton12, Shebli, Anvar13, Miguel, Ardid14, Ana Carolina Assis Jesus15, Astraatmadja15¤a, Tri L., Jean Jacques Aubert8, Bruny, Baret16, Ste´phane, Basa17, Vincent, Bertin8, Simone, Biagi18, Armando, Bigi20, Ciro, Bigongiari7, Claudio, Bogazzi15, Manuel Bou Cabo14, Boutayeb, Bouhou16, Bouwhuis15, Mieke C., Jurgen, Brunner8¤b, Jose´, Busto8, Francisco, Camarena14, Antonio, Capone21, Christina, Caˆrloganu23, Giada, Carminati18, 19¤c, John, Carr8, Stefano, Cecchini18, Ziad, Charif8, Philippe, Charvis25, Tommaso, Chiarusi18, Marco, Circella26, Rosa, Coniglione27, Heide, Costantini8, Paschal, Coyle8, Christian, Curtil8, Patrick, Decowski15, Ivan, Dekeyser1, Anne, Deschamps25, Corinne, Donzaud16, Damien, Dornic7, 8, Dorosti29, Hasankiadeh Q., Doriane, Drouhin9, Thomas, Eberl12, Umberto, Emanuele7, Jean Pierre Ernenwein8, Ste´phanie, Escoffier8, Paolo, Fermani21, Marcelino, Ferri14, Vincenzo, Flaminio20, Florian, Folger12, Ulf, Fritsch12, Jean Luc Fuda1, 2¤d, Salvatore Galata`, 8, Pascal, Gay23, Giorgio, Giacomelli18, Valentina, Giordano27, Juan Pablo Go´mez Gonza´ lez7, Kay, Graf12, Goulven, Guillard23, Garadeb, Halladjian8, Gregory, Hallewell8, Hans van Haren31, Joris, Hartman15, Heijboer15, Aart J., Yann, Hello25, Juan Jose Herna´ndez Rey7, Bjoern, Herold12, Jurgen Ho¨ ßl12, Ching Cheng Hsu15, Marteen de Jong15¤a, Matthias, Kadler32, Oleg, Kalekin12, Alexander, Kappes12, Uli, Katz12, Oksana, Kavatsyuk29, Paul, Kooijman15, 34, 33, Claudio, Kopper12, Antoine, Kouchner16, Ingo Kreykenbohm 32, Vladimir, Kulikovskiy11, Robert, Lahmann12, Patrick, Lamare13, Giuseppina, Larosa14, Dario, Lattuada27, Gordon, Lim15, Domenico Lo Presti36, Herbert, Loehner29, Sotiris, Loucatos38, Salvatore, Mangano7, Michel, Marcelin17, Annarita, Margiotta18, Juan Antonio Martinez Mora14, Athina, Meli12, Teresa, Montaruli26, Luciano, Moscoso16, 38{, Holger, Motz12, Max, Neff12, Emma nuel Nezri17, Dimitris, Palioselitis15, Pa˘va˘ las¸40, Gabriela E., Kevin, Payet38, Patrice, Payre8, Jelena, Petrovic15, Paolo, Piattelli27, Nicolas Picot Clemente8, Vlad, Popa40, Thierry, Pradier41, Eleonora, Presani15, Chantal, Racca9, Corey, Reed15, Giorgio, Riccobene27, Carsten, Richardt12, Roland, Richter12, Colas Rivie` re8, Kathrin, Roensch12, Andrei, Rostovtsev42, Joaquin Ruiz Rivas7, Marius, Rujoiu40, Russo36, Valerio G., Francisco, Salesa7, Augustin Sa´nchez Losa7, Piera, Sapienza27, Friederike Scho¨ ck12, Jean Pierre Schuller38, Fabian, Schussler38, Rezo, Shanidze12, Francesco, Simeone21, Andreas, Spies12, Maurizio, Spurio18, Steijger15, Jos J. M., Thierry, Stolarczyk38, Taiuti11, Mauro G. F., Simona, Toscano7, Bertrand, Vallage38, Ve´ronique Van Elewyck16, Giulia, Vannoni38, Manuela, Vecchi8, Pascal, Vernin38, Guus, Wijnker15, Jorn, Wilms32, Els de Wolf15, Harold, Yepes7, Dmitry, Zaborov42, Juan De Dios Zornoza7, Juan Zu´ n˜ iga7, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Couplage physique-biogéochimie-carbone (PHYBIOCAR), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Variabilité de l'Océan et de la Glace de mer (VOG), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Groupe de Recherche en Physique des Hautes Energies (GRPHE), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-IUT de Colmar, Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA)), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Istituto Nazionale di Fisica Nucleare, Sezione di Catania (INFN), Università degli studi di Catania = University of Catania (Unict), Royal Netherlands Institute for Sea Research (NIOZ), Laboratori Nazionali del Sud (LNS), Istituto Nazionale di Fisica Nucleare (INFN), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), ANTARES, ANR-05-BLAN-0161,POTES,Pressure effects On marine prokaryoTES(2005), European Project: 202955,EC:FP7:ENV,FP7-ENV-2007-1,EUROSITES(2008), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut Universitaire de Technologie de Colmar, Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Università degli studi di Catania [Catania], Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), KVI - Center for Advanced Radiation Technology, John Murray Robert, Christian Tamburini, Miquel Canal, Xavier Durrieu de Madron, Loïc Houpert, Dominique Lefèvre, Séverine Martini, Fabrizio D'Ortenzio, Anne Robert, Pierre Testor, Juan Antonio Aguilar, Imen Al Samarai, Arnaud Albert, Michel André, Marco Anghinolfi, Gisela Anton, Shebli Anvar, Miguel Ardid, Ana Carolina Assis Jesu, Tri L. Astraatmadja, Jean-Jacques Aubert, Bruny Baret, Stéphane Basa, Vincent Bertin, Simone Biagi, Armando Bigi, Ciro Bigongiari, Claudio Bogazzi, Manuel Bou-Cabo, Boutayeb Bouhou, Mieke C. Bouwhui, Jurgen Brunner, José Busto, Francisco Camarena, Antonio Capone, Christina Cârloganu, Giada Carminati, John Carr, Stefano Cecchini, Ziad Charif, Philippe Charvi, Tommaso Chiarusi, Marco Circella, Rosa Coniglione, Heide Costantini, Paschal Coyle, Christian Curtil, Patrick Decowski, Ivan Dekeyser, Anne Deschamp, Corinne Donzaud, Damien Dornic, Hasankiadeh Q. Dorosti, Doriane Drouhin, Thomas Eberl, Umberto Emanuele, Jean-Pierre Ernenwein, Stéphanie Escoffier, Paolo Fermani, Marcelino Ferri, Vincenzo Flaminio, Florian Folger, Ulf Fritsch, Jean-Luc Fuda, Salvatore Galatà, Pascal Gay, Giorgio Giacomelli, Valentina Giordano, Juan-Pablo Gómez-González, Kay Graf, Goulven Guillard, Garadeb Halladjian, Gregory Hallewell, Hans van Haren, Joris Hartman, Aart J. Heijboer, Yann Hello, Juan Jose Hernández-Rey, Bjoern Herold, Jurgen Hößl, Ching-Cheng Hsu, Marteen de Jong, Matthias Kadler, Oleg Kalekin, Alexander Kappe, Uli Katz, Oksana Kavatsyuk, Paul Kooijman, Claudio Kopper, Antoine Kouchner, Ingo Kreykenbohm, Vladimir Kulikovskiy, Robert Lahmann, Patrick Lamare, Giuseppina Larosa, Dario Lattuada, Gordon Lim, Domenico Lo Presti, Herbert Loehner, Sotiris Loucato, Salvatore Mangano, Michel Marcelin, Annarita Margiotta, Juan Antonio Martinez-Mora, Athina Meli, Teresa Montaruli, Luciano Moscoso, Holger Motz, Max Neff, Emma nuel Nezri, Dimitris Palioseliti, Gabriela E. Păvălaş, Kevin Payet, Patrice Payre, Jelena Petrovic, Paolo Piattelli, Nicolas Picot-Clemente, Vlad Popa, Thierry Pradier, Eleonora Presani, Chantal Racca, Corey Reed, Giorgio Riccobene, Carsten Richardt, Roland Richter, Colas Rivière, Kathrin Roensch, Andrei Rostovtsev, Joaquin Ruiz-Riva, Marius Rujoiu, Valerio G. Russo, Francisco Salesa, Augustin Sánchez-Losa, Piera Sapienza, Friederike Schöck, Jean-Pierre Schuller, Fabian Schussler, Rezo Shanidze, Francesco Simeone, Andreas Spie, Maurizio Spurio, Jos J. M. Steijger, Thierry Stolarczyk, Mauro G. F. Taiuti, Simona Toscano, Bertrand Vallage, Véronique Van Elewyck, Giulia Vannoni, Manuela Vecchi, Pascal Vernin, Guus Wijnker, Jorn Wilm, Els de Wolf, Harold Yepe, Dmitry Zaborov, Juan De Dios Zornoza, Juan Zúñiga, Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), National Institute for Nuclear Physics (INFN), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), ANR-05-BLAN-0161,POTES,Projet POTES - Pressure effects On marine prokaryoTES(2005), Universitat de Barcelona, Institut Universitaire de Technologie de Colmar-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Centre Tecnològic de Vilanova i la Geltrú, and Universitat Politècnica de Catalunya. LAB - Laboratori d'Aplicacions Bioacústiques

Subjects
Desenvolupament humà i sostenible::Medi ambient [Àrees temàtiques de la UPC], 0106 biological sciences, DYNAMICS, Salinity, ANTARES NEUTRINO TELESCOPE, 010504 meteorology & atmospheric sciences, Naturwissenschaftliche Fakultät -ohne weitere Spezifikation, IMPACT, Ocean Circulation, Psychologie appliquée, lcsh:Medicine, Cell Count, Astronomical Sciences, Oceanografia, Astrophysics, Oceanography, Ecologia marina, 01 natural sciences, Bathyal zone, NEUTRINO TELESCOPES, Mediterranean sea, Oceans, lcsh:Science, deep-sea bioluminescenceantares, Ecosistemes marins, Multidisciplinary, CLIMATE-CHANGE, Ecology, Mediterrània (Mar), Mediterranean Region, Marine Ecology, MEDITERRANEAN SEA, Eutrophication, Biogeochemistry, Sciences bio-médicales et agricoles, Deep sea, INTERANNUAL VARIABILITY, Light emission, Seasons, ddc:500, Bioluminescence, Biologie, Research Article, ATLANTIC, GULF, Oceans and Seas, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Marine Biology, Convection, Fluorescence, Microbial Ecology, Carbon Cycle, Marine ecology, Astroparticle Physics, Mediterranean Sea, Animals, Water Column, Ecosystem, Seawater, 14. Life underwater, Salinitat, Neutrinos, Biology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Marine plankton, BACKGROUND LIGHT, 010604 marine biology & hydrobiology, Biological Oceanography, lcsh:R, Plàncton, Pelagic zone, Marine and aquatic sciences, Earth sciences, Light intensity, Sea water, Geochemistry, 13. Climate action, CONVECTION, FISICA APLICADA, Luminescent Measurements, Aigua de mar, Environmental science, lcsh:Q, Physical Oceanography
Abstract

The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in the properties of deep waters. Such changes are triggered by the winter cooling and evaporation experienced by the upper ocean layer in the Gulf of Lion that leads to the formation and subsequent sinking of dense water through a process known as "open-sea convection". It episodically renews the deep water of the study area and conveys fresh organic matter that fuels the deep ecosystems. Luminous bacteria most likely are the main contributors to the observed deep-sea bioluminescence blooms. Our observations demonstrate a consistent and rapid connection between deep open-sea convection and bathypelagic biological activity, as expressed by bioluminescence. In a setting where dense water formation events are likely to decline under global warming scenarios enhancing ocean stratification, in situ observatories become essential as environmental sentinels for the monitoring and understanding of deep-sea ecosystem shifts. © 2013 Tamburini et al., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2013

45. Mid-latitude ozone monitoring with the GOMOS-ENVISAT experiment version 5: the noise issue

Author

A. van Gijsel, Philippe Keckhut, Jean-Loup Bertaux, Klemens Hocke, Andrea Pazmino, Laurent Blanot, Alain Hauchecorne, Gilbert Barrot, Erkki Kyrölä, Sophie Godin-Beekmann, STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Analytic and Computational Research, Inc. - Earth Sciences (ACRI-ST), Institut für angewandte Physik [Bern] (IAP), Universität Bern [Bern], Oeschger Centre for Climate Change Research (OCCR), University of Bern, Finnish Meteorological Institute (FMI), National Institute for Public Health and the Environment [Bilthoven] (RIVM), and Universität Bern [Bern] (UNIBE)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, Ozone, 010504 meteorology & atmospheric sciences, Meteorology, Chemistry, Detector, 01 natural sciences, lcsh:QC1-999, lcsh:Chemistry, chemistry.chemical_compound, Noise, lcsh:QD1-999, 13. Climate action, Middle latitudes, 0103 physical sciences, Ozone layer, Background light, Spurious relationship, 010303 astronomy & astrophysics, lcsh:Physics, 0105 earth and related environmental sciences, Remote sensing, Recovery phase
Abstract

The GOMOS ozone profiles have been analysed to evaluate the GOMOS ability to capture the long-term ozone evolution at mid-latitudes during the expected recovery phase of the ozone layer. Version 5 of the operational GOMOS ozone data has been compared with data from two of the longest ground-based instruments based on different techniques and already involved with many other previous space instrument validations. Comparisons between ground-based and GOMOS data confirm the occurrence of spurious retrievals mainly occurring since 2006. Using a selected set of data it is shown that some bad retrievals are induced by the increasing dark charge of the detectors combined with an inadequate method for its correction. This effect does not only induce a continuous bias, but is rather exhibiting a bimodal distribution including the correct profiles and the bad retrievals. For long-term analyses it is recommended filtering the data according to background light conditions and star temperature (spectrum shape). The new method of the dark charge estimate proposed to be implemented in the version 6 of the ESA algorithm seems to significantly reduce the occurrence of such effects and should allow to monitor stratospheric ozone using GOMOS data with greater confidence.

Published
2010

46. HESS observations of $\gamma$-ray bursts in 2003-2007

Author

F. Aharonian, A. G. Akhperjanian, U. Barres de Almeida, A. R. Bazer-Bachi, B. Behera, W. Benbow, K. Bernlöhr, C. Boisson, A. Bochow, V. Borrel, I. Braun, E. Brion, J. Brucker, P. Brun, R. Bühler, T. Bulik, I. Büsching, T. Boutelier, S. Carrigan, P. M. Chadwick, A. Charbonnier, R. C. G. Chaves, A. Cheesebrough, L.-M. Chounet, A. C. Clapson, G. Coignet, M. Dalton, B. Degrange, C. Deil, H. J. Dickinson, A. Djannati-Ataï, W. Domainko, L. O'C. Drury, F. Dubois, G. Dubus, J. Dyks, M. Dyrda, K. Egberts, D. Emmanoulopoulos, P. Espigat, C. Farnier, F. Feinstein, A. Fiasson, A. Förster, G. Fontaine, M. Füßling, S. Gabici, Y. A. Gallant, L. Gérard, B. Giebels, J. F. Glicenstein, B. Glück, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, S. Heinz, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, A. Hoffmann, W. Hofmann, M. Holleran, S. Hoppe, D. Horns, A. Jacholkowska, O. C. de Jager, I. Jung, K. Katarzyński, S. Kaufmann, E. Kendziorra, M. Kerschhaggl, D. Khangulyan, B. Khélifi, D. Keogh, Nu. Komin, K. Kosack, G. Lamanna, J.-P. Lenain, T. Lohse, V. Marandon, J. M. Martin, O. Martineau-Huynh, A. Marcowith, D. Maurin, T. J. L. McComb, M. C. Medina, R. Moderski, E. Moulin, M. Naumann-Godo, M. de Naurois, D. Nedbal, D. Nekrassov, J. Niemiec, S. J. Nolan, S. Ohm, J.-F. Olive, E. de Oña Wilhelmi, K. J. Orford, J. L. Osborne, M. Ostrowski, M. Panter, G. Pedaletti, G. Pelletier, P.-O. Petrucci, S. Pita, G. Pühlhofer, M. Punch, A. Quirrenbach, B. C. Raubenheimer, M. Raue, S. M. Rayner, M. Renaud, F. Rieger, J. Ripken, L. Rob, S. Rosier-Lees, G. Rowell, B. Rudak, C. B. Rulten, J. Ruppel, V. Sahakian, A. Santangelo, R. Schlickeiser, F. M. Schöck, R. Schröder, U. Schwanke, S. Schwarzburg, S. Schwemmer, A. Shalchi, J. L. Skilton, H. Sol, D. Spangler, Ł. Stawarz, R. Steenkamp, C. Stegmann, G. Superina, P. H. Tam, J.-P. Tavernet, R. Terrier, O. Tibolla, C. van Eldik, G. Vasileiadis, C. Venter, L. Venter, J. P. Vialle, P. Vincent, M. Vivier, H. J. Völk, F. Volpe, S. J. Wagner, M. Ward, A. A. Zdziarski, and A. Zech

Subjects
Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Flux, bursts [gamma rays], observations [gamma rays], Astronomy and Astrophysics, Astrophysics, Photon energy, 01 natural sciences, Redshift, Space and Planetary Science, 0103 physical sciences, Background light, Gamma-ray burst, 010303 astronomy & astrophysics, Cherenkov radiation
Abstract

Very-high-energy (VHE; >~100 GeV) gamma-rays are expected from gamma-ray bursts (GRBs) in some scenarios. Exploring this photon energy regime is necessary for understanding the energetics and properties of GRBs. GRBs have been one of the prime targets for the H.E.S.S. experiment, which makes use of four Imaging Atmospheric Cherenkov Telescopes (IACTs) to detect VHE gamma-rays. Dedicated observations of 32 GRB positions were made in the years 2003-2007 and a search for VHE gamma-ray counterparts of these GRBs was made. Depending on the visibility and observing conditions, the observations mostly start minutes to hours after the burst and typically last two hours. Results from observations of 22 GRB positions are presented and evidence of a VHE signal was found neither in observations of any individual GRBs, nor from stacking data from subsets of GRBs with higher expected VHE flux according to a model-independent ranking scheme. Upper limits for the VHE gamma-ray flux from the GRB positions were derived. For those GRBs with measured redshifts, differential upper limits at the energy threshold after correcting for absorption due to extra-galactic background light are also presented.

Published
2009

48. Stable single photon source in near infrared

Author

Joerg Wrachtrup, Fedor Jelezko, M. Domhan, Torsten Gaebel, A. Gruber, and I. Popa

Subjects
Quantum Physics, Photon, Materials science, business.industry, Bandwidth (signal processing), Near-infrared spectroscopy, General Physics and Astronomy, Diamond, FOS: Physical sciences, engineering.material, Wavelength, Single-photon source, engineering, Optoelectronics, Background light, business, Quantum Physics (quant-ph), Excitation
Abstract

Owing to their unsurpassed photostability, defects in solids may be ideal candidates for single photon sources. Here we report on generation of single photons by optical excitation of a yet unexplored defect in diamond, the nickel-nitrogen complex (NE8) centre. The most striking feature of the defect is its emission bandwidth of 1.2 nm at room temperature. The emission wavelength of the defect is around 800 nm, which is suitable for telecom fibres. In addition, in this spectral region little background light from the diamond bulk material is detected. Consequently, a high contrast in antibunching measurements is achieved., 8 pages, 4 figures

Published
2004

49. The Measure of Cosmological Parameters

Author

Wendy L. Freedman

Subjects
Physics, Nuclear and High Energy Physics, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Cosmological constant, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Space (mathematics), Measure (mathematics), Atomic and Molecular Physics, and Optics, Cosmology, symbols.namesake, Observational cosmology, Dark energy, symbols, Background light, Hubble's law
Abstract

New, large, ground and space telescopes are contributing to an exciting and rapid period of growth in observational cosmology. The subject is now far from its earlier days of being data-starved and unconstrained, and new data are fueling a healthy interplay between observations and experiment and theory. I briefly review here the status of measurements of a number of quantities of interest in cosmology: the Hubble constant, the total mass-energy density, the matter density, the cosmological constant or dark energy component, and the total optical background light., 12 pages, 4 figures, to be published in "2001: A Spacetime Odyssey: Proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics", Michael J. Duff & James T. Liu, eds., (World Scientific, Singapore), in press

Published
2002

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