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The article describes a model and method for calculating beta-exposure doses to secretory and basal cells of the tracheobronchial part of the respiratory tract when a point source of 1 Bq activity moves along the inner surface of respiratory formations. The calculations, that used for proposed model, were performed by using a 90Y point source as an example. The dose calculation model takes into account the speed o f movement of the radiation source in each respiratory formation, the size of the respiratory formations, and the depth of the secretory and basal cells. The dose calculation is based on the dose rate attenuation functions published by W. G. Cross et al. (DOI: 10.1097/00004032-199208000-00002). The calculations were performed for a cylindrical model of a respiratory formation. Two kinds of cells were considered for the dose estimation: cells irradiated without beta-particle exit into bronchial lumen (type 1 cells) and cells irradiated due to beta-par­ticle exit into bronchial lumen (type 2 cells). The results of calculations showed, that as far as the generation number increasing, the average irradiation doses of the type 1 cells are 10 or more times greater than those of the type 2 cells. With increasing generation number in the tracheobronchial tree, doses per cells increase by several orders of magnitude. The highest doses are formed in bronchioles of generations 9-15, reaching units and tens of mGy. In spite of the fact that the number of generation increases, the total number of irradiated cells decreases, the collective doses of irradiated cells (sum of doses to all cells of the respiratory formation) in the last generations are 30-50 times higher than the doses of the first generations. Thus, in case of a single point source, there is a significant (by many orders of magnitude) scatter of doses to individual cells in indi­vidual respiratory formation, as well as significant differences in average doses of trachea, individual bronchi and bronchioles.

The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), has been used since 2000 to protect high-value trees and stands throughout western North America. Operational treatments involve placing individual releasers on a 12 m × 12 m grid throughout the area to be protected. In this study, six widely spaced trap lines were established with aggregation attractant–baited traps located 1, 3, 9, 27, and 81 m from a location where an operational MCH release device was alternately either present or absent, and changes in catches caused by the MCH device were assessed at all distances. Trap catches were suppressed by about 70% at one and three metres, by 50% at nine metres, by 30% at 27 m, and not at all at 81 m. Inhibition by the MCH device varied with distance (m) from the source according to the function 0.79 − 0.092x0.51 (R2 = 0.986). Decline of attractant inhibition with distance from the MCH device was much less steep than would have been expected if catch inhibition had varied directly with the average airborne concentration of MCH.

We consider an interior inverse scattering problem of reconstructing the shape of a cavity. The measurements are the scattered fields on a curve inside the cavity due to only one point source. In this paper, we employ the extending sampling method to reconstruct the cavity based on limited data. Numerical examples are provided to show the effectiveness of the method.

Atmospheric Transport Modelling (ATM) results were combined with 7Be observations collected during the 2009–2015 period by the three radionuclide stations from the International Monitoring System (IMS), located in Mauritania (18.1 N, 15.9 W), Kuwait (29.3 N, 47.9 E) and Panama (9.0 N, 79.5 W), to study the influence of Saharan dust on changes in 7Be surface concentrations. It is demonstrated that for long-range transport (>3000 km), the overall impact of Sahara can be reproduced using a single point source located in the Bodele depression (17.0 N, 18.0 E). To monitor the arrival time of dust plumes at the IMS stations, a series of 14-day forward simulations with daily releases from the Bodele, during dusty episodes between 2009 and 2015, were generated. In total 1020 simulations with the output at the surface level (0–150 m) and 420 simulations with the output at 9 vertical layers ranging from the surface up to 10 km, were analysed. In the simulations, the analysed meteorological input data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) were used. It is demonstrated that an influx of dust at high levels (3–10 km) tends to locally increase surface 7Be concentrations in area under the influence of subsiding dust plume. It is also shown that an influx of dust at lower altitudes (up to 1 km) will have the opposite effect on surface concentrations. In case dust is present in the whole column of atmosphere, its final impact depends on the ratio between its amount in the upper layers (3–10 km) and lower layers (0–1 km). In consequence an increase up to 30% or a decrease up 20% in daily 7Be surface values may be observed during such an episode. On a monthly scale a few episodes related to an increase of 7Be values or its decrease may follow each other. It was estimated that on average the presence of dust leads to the increase of 7Be mean monthly surface values. The largest increase was noted at the station MRP43, of about 4.1 ± 1.3%; and the smallest at the stations KWP40, of about 2.0 ± 1.6% and PAP50, of about 2.0 ± 1.0%, respectively.

In this paper, a novel method based on net function interpolation is proposed to reconstruct nuclear radiation field on the basis of the sparse observed data. In the grid space, the missing data of grid line is filled by means of constructing function. Then, the value of grid interior points is obtained by use of the net function interpolation method. To demonstrate the feasibility of the proposed method, the simulation experiment concerning a single point source is carried out. Compared with the simulation results of Monte Carlo method, the calculation results perform well. To make the simulation environment real, another experiment with multiple volumetric sources is done. The inversion results are also satisfactory. What's more, as the sampling data increases, the degree of reduction is further improved. It is worthwhile mentioning that the results have relative errors of 1.91%, 5.47% and 1.22% respectively. In this paper, the radiation field is restored very well according to the sparse sampling data. Hence, the proposed method is a quite effective way for the inversion of nuclear radiation field.

In order to further explore the change rule of soil wetting characteristics in surge and spring root irrigation, the single-point source flooding test of jujube micro-irrigation demonstration base in northern mountainous area was studied. Under different flow conditions, Soil wetting front migration distance and water distribution of the law, the results show that: wetting wet front movement quickly, with the passage of time and gradually slow down. The wetting radius of the horizontal flow increases with the increase of the drip flow. In the process of water redistribution, the wetting peak velocity of the small droplet shows a “failure” phenomenon, and the wet front migration rate larger drip flow significantly slows down. The general trend of soil moisture content of the single-point source moisturizing source is: the farther away from the straight line of the drip, the lower the water content of the soil; at the end of the irrigation, the soil water content decreases along the depth direction. As time goes on, the areas with high water content gradually migrate down from the surface layer, and finally the soil moisture distribution characteristics of low surface layer, high middle layer and low bottom layer are formed.

Atmospheric dust affects climate, biogeochemistry, and human health, with total emissions estimated at 1,500 to 3,000 Tg yr−1. The Bodele Depression, Chad (17˚N, 18˚E) in the Saharan Desert is the largest single point source of dust in the world, and dust from the Bodele, and the Sahara in general, has been tracked across much of the world, including to the Caribbean and the Americas. Although it has been linked to negative health effects in sink regions, few have worked to understand its local health effects in Africa. The lack of ground-based stations in North Africa and the inaccessibility of much of the region call for a remote technique to track dust concentration and composition as it moves across Africa. Such a method would provide a more detailed understanding of dust dynamics in North Africa and reveal the potential health effects of dust in the region. Here, we combine aerosol optical thickness measurements from MODIS and dust concentrations from the DREAM model with hyperspectral imagery from t...

We present new late-time, high-resolution observations of the sites of supernovae (SNe) 2008cn, 2009kr and 2009md, acquired with the Hubble Space Telescope. In all instances, significant flux from the SNe is still recovered at late times. We show that the previous identification of the progenitor of SN 2008cn was actually a blend of two sources, whose locations are resolved in these new observations. We suggest that the progenitor of SN 2008cn was actually a red supergiant with M-init < 16 M-circle dot. In the late-time observations of SN 20091cr, we find that the pre-explosion source (previously thought to be a yellow supergiant) is most probably a small compact cluster with mass similar to 6000 M-circle dot. In late-time F814W observations of the site of SN 2009md, we find a single point source with identical brightness to the pre-explosion source, suggesting some caution in assuming that the pre-explosion source was the progenitor.

The production of petroleum coke (petcoke) in the refineries is progressively peaking up because of the trend of processing heavy crudes and in turn, a renewed interest in delayed coking process. Therefore, an efficient, economical, and environmentally safe utilisation of petcoke has become imperative in the current petroleum refining scenario. Gasification of petcoke has emerged as one of the attractive options and is gaining increasing attention to convert the petcoke to value-added products. The process offers the refiners a variety of product slates mainly via synthesis gas route. The products include steam, hydrogen, electricity, chemicals (viz. methanol, ammonia, etc.), liquid fuels via Fischer–Tropsch (F-T) synthesis and so on. Petcoke has been identified as a potential feedstock for about 15% of the total planned gasification capacity worldwide. In the present communication, the published literature pertaining to petcoke gasification has been extensively analysed and a state-of-the-art review has been written that includes: (1) the importance of petcoke gasification in the present petroleum refining scenario; (2) petcoke gasification reaction mechanism, kinetics, and typical product profile; (3) parametric sensitivity of the operating variables such as temperature and pressure; (4) various gasifiers for petcoke gasification; (5) modelling efforts on different types of gasifiers and (6) future prospects of petcoke gasification. An attempt has been made to get the afore-mentioned aspects together in a thematic framework so that the information is available at a glance and is expected to be useful as a single point source to the researchers and practicing refiners.

We investigate the super-Brownian motion with a single point source in dimensions 2 and 3 as constructed by Fleischmann and Mueller in 2004. Using analytic facts we derive the long time behavior of the mean in dimensions 2 and 3 thereby complementing previous work of Fleischmann, Mueller and Vogt. Using spectral theory and martingale arguments we prove a version of the strong law of large numbers for the two dimensional superprocess with a single point source and finite variance.

CALMET/CALPUFF modeling system is frequently used in the study of atmospheric processes and pollution, and several validation tests were performed until now; nevertheless, most of them were based on experiments with a large compilation of surface and aloft meteorological measurements, rarely available. At the same time, the use of a large operational smokestack as tracer/pollutant source is not usual. In this work, first CALMET meteorological diagnostic model is nested to WRF meteorological prognostic model simulations (3x3 km2 horizontal resolution) over a complex terrain and coastal domain at NW Spain, covering 100x100 km2, with a coal-fired power plant emitting SO2. Simulations were performed during three different periods when SO2 hourly glc peaks were observed. NCEP reanalysis were applied as initial and boundary conditions. Yong Sei University-Pleim-Chang (YSU) PBL scheme was selected in the WRF model to provide the best input to three different CALMET horizontal resolutions, 1x1 km2, 0.5x0.5 km2, and 0.2x0.2 km2. The best results, very similar between them, were achieved using the last two resolutions; therefore, the 0.5x0.5 km2 resolution was selected to test different CALMET meteorological inputs, using several combinations of WRF outputs and/or surface and upper-air measurements available in the simulation domain. With respect to meteorological aloft models output, CALMET PBL depth estimations are very similar to PBL depth estimations using upper-air measurements (rawinsondes), and significantly better than WRF PBL depth results. Regarding surface models surface output, the available meteorological sites were divided in two groups, one to provide meteorological input to CALMET (when applied), and another to models validation. Comparing WRF and CALMET outputs against surface measurements (from sites for models validation) the lowest RMSE was achieved using as CALMET input dataset WRF output combined with surface measurements (from sites for CALMET model input). Following, CALPUFF model was applied to simulate the local atmospheric diffusion of SO2 (as an inert tracer) from a large power plant smokestack (with four parallel independent liners), considering two different stack configurations (one single point source as a summa of four liners vs. one point source per liner) and two different CALMET meteorological simulations (using as input dataset only the WRF model output vs. only surface and upper-air meteorological measurements). Comparison of those CALPUFF simulations results against the hourly average ground level concentration (glc) measurements shows that the best model performance was obtained by using only WRF model output as CALMET input; also, better glc results are obtained considering one point source per liner in CALPUFF simulations.

Many rivers and streams in Taiwan receive significant BOD and ammonia loads from domestic and industrial wastewaters. These loads are characterized by excessive strength (high concentrations and wastewater flows) – often with great spatial intensity. In many cases, an additional significant load enters the stream before the upstream input is fully stabilized in the receiving water. The classic DO sag and recovery curve in rivers associated with single point source BOD loads (as found in most textbooks) are therefore rare in Taiwan’s rivers. As a result, a different modeling approach must be adopted to address technical challenges associated with modeling for water quality management in Taiwan. In this paper, the modeling results of two rivers in Taiwan are presented to demonstrate the associated technical issues and difficulties, as well as recommend further effort to meet these challenges.

A novel stochastic technique combining a dilute source grid of $\mathbb{Z}_3$ noise with iterative momentum-smearing is used to study the proton correlation function at rest and in boosted frames on two lattice volumes. The technique makes use of the baryonic version of the so-called one-end trick, and the decomposition into signal and noise terms of the resulting stochastic proton correlation function is made explicit. The number and location of the source points in the dilute grid should be chosen so that the benefits of averaging over many locations overcomes the additional statistical error introduced by the noise terms in the desired fitting region. At all nontrivial momentum values considered we find that the choice of $N=4$--$8$ maximally separated source locations is shown to be optimal, providing a reduced statistical error when compared with a single point source. This enables us to successfully fit the proton energy at momentum values as high as $|\vec{p}| \simeq 3.75$ GeV and $|\vec{p}| \simeq 2.82$ GeV on the small and large volume respectively., Comment: 13 pages, 12 figures

With many transportation professionals soon reaching retirement age, the industry is facing challenges. A key component to the success of the profession is recruiting new employees with the technical and managerial skills to take on future challenges. This paper outlines how one civil engineering school addressed the challenge of declining enrollments by working cooperatively with industry to meet three goals: to increase the visibility of civil engineering as a career, to expand coordination with employers, and to enhance recruitment of students. To meet the goals, a number of strategies were pursued; these included expanding activities for freshmen, participating in K–12 outreach programs, revising the civil engineering career course, expanding the career fair to include a freshman showcase, facilitating civil engineering internships for freshmen, designating a single point source for industry communications, enhancing tools for coordination with employers, increasing opportunities for student employment, updating recruiting materials, using students and alumni as ambassadors, and fostering student interaction through activities. The recruiting activities discussed in this paper not only brought in new students but also fostered cooperation with industry and the engagement of existing students, which may contribute to enhanced retention. Many activities described in this paper can be implemented at other colleges, and some of the strategies identified are appropriate for employers seeking to enhance the effectiveness of their activities on campus.

We report results of a preliminary study of particulate and dissolved organic carbon transport in the Ayeyarwady and Thanlwin Rivers of Myanmar, based on 52 suspended sediment samples and 9 water samples collected during conditions of low and high flow in 2005 and 2006. The Ayeyarwady transports 2.2–4.3 MtC/yr as POC with a weighted average δ 13 C value of - 24.8 ‰ , while the Thanlwin transports an additional 2.4–3.4 MtC/yr with a δ 13 C value of - 25.3 ‰ . In addition, the Ayeyarwady transports ∼ 0.9 Mt / yr , and the Thanlwin ∼ 0.23 Mt / yr , of DOC with a δ 13 C value of - 26.2 ‰ and - 27.1 ‰ , respectively. The Ayeyarwady and Thanlwin catchments adjoin each other, debouching into the Indian Ocean over a length scale similar to the deltas of the Ganges–Brahmaputra or the Amazon. Therefore, the Ayeyarwady and Thanlwin rivers should be considered a single point source contributing to the global ocean. This combined river system transports 5.7–8.8 MtC/yr of organic carbon, suggesting that it may be the second largest point source of organic carbon to the global ocean after the Amazon. The implied organic carbon yield from the catchments is 8.4–12.9 t/km2/yr, which is clearly amongst the highest in the world among rivers of similarly large size. The high organic carbon yields are likely to be the result of (i) a strongly monsoonal climate, (ii) the large area of highly productive forest present on steep slopes in a region of active tectonism, and (iii) the comparatively small area of floodplain in the catchments.

We present new NuSTAR and Chandra observations of NGC 3393, a galaxy reported to host the smallest separation dual AGN resolved in the X-rays. While past results suggested a 150 pc separation dual AGN, three times deeper Chandra imaging, combined with adaptive optics and radio imaging suggest a single, heavily obscured, radio-bright AGN. Using VLA and VLBA data, we find an AGN with a two-sided jet rather than a dual AGN and that the hard X-ray, UV, optical, NIR, and radio emission are all from a single point source with a radius 0.2, but would detect an unobscured AGN of this luminosity out to high redshift (z=5)., Accepted for publication in ApJ. 15 Figures and 4 tables

A three-dimensional dispersion air pollution model with point sources is considered in a limited region. The adjoint model and the duality principle are used to pose a variational short-term control problem with the aim of determining optimal emission rates of the sources. The existence and uniqueness of the optimal control problem solution are proved. A numerical scheme using a process of orthogonal projections is given for approximating the optimal solution. The computing efficiency of the scheme is shown. Numerical results obtained in the case of a single point source demonstrate the method's ability.

Light field cameras allow us to digitally refocus a photograph after the time of capture. However, recording a light field requires either a significant loss in spatial resolution [11, 21, 10] or a large number of images to be captured [12]. In this paper, we propose incoherent holography for digital refocusing without loss of spatial resolution from only 3 captured images. The main idea is to capture 2D coherent holograms of the scene instead of the 4D light fields. The key properties of coherent light propagation are that the coherent spread function (hologram of a single point source) encodes scene depths and has a broadband spatial frequency response. These properties enable digital refocusing with 2D coherent holograms, which can be captured on sensors without loss of spatial resolution. Incoherent holography does not require illuminating the scene with high power coherent laser, making it possible to acquire holograms even for passively illuminated scenes. We provide an in-depth performance comparison between light field and incoherent holographic cameras in terms of the signal-to-noise-ratio (SNR). We show that given the same sensing resources, an incoherent holography camera outperforms light field cameras in most real world settings. We demonstrate a prototype incoherent holography camera capable of performing digital refocusing from only 3 acquired images. We show results on a variety of scenes that verify the accuracy of our theoretical analysis.

A holographic imaging technique, previously used in underwater acoustics, is applied to the solar inverse source problem. This problem consists of forming acoustic images so as to localize impulsive sources in space and time in the solar interior. The difficulty with such an imaging method is that the image of a single point source is spatiotemporally extended and will produce significant overlap between images of separated sources if the source density is large. I propose a modification of the existing method in order to make reliable source images also in the case for large source density. It is suggested that the method can be used on solar observations to detect relatively strong and impulsive wave sources inside the sun and to perhaps clarify unanswered problems regarding excitation of p modes.

Freeform lenses can be designed for diverse illumination profiles with good uniformity. However, most of the previous studies formulated for a single point source and the lens to design has a spherical bottom. In this study, the formulation is extended for multiple point sources and for lenses with a flat bottom in favor of prototyping and manufacturing. The extended formulation requires only a freeform surface to design. However, it could be over determined if the light rays emitted from the multiple point sources overlap at the near field. The weighted least-square method is introduced to solve the over-determined problem. A weighting function correlated with the emitting intensities of the sources is proposed to design for illumination profile fit and uniformity in trade-off. The adequacy of the extended formulation is demonstrated by simulation. Circular and rectangular illuminations of multiple point sources in different layouts are illustrated. The simulation results show that profile fit and uniformity could be significantly affected by a source offset. With the offset taken into account in the extended formulation, the effects can be properly collimated.

The transport of contaminated sediment out of Lake Erie is an important process controlling the fate of potentially toxic organic compounds in the lower Great Lakes. This transport was investigated by electron capture gas chromatographic mass spectrometry analysis of 2,4-di-tert-pentylphenol (24DP) and 2-chloro-4,6-di-tert-pentylphenol (24DP6Cl) derivatized with pentafluorobenzyl bromide (PFBBr) to give PFB ether derivatives. 24DP and 24DP6Cl are unusual sediment-bound pollutants originating from a single point source on the Trenton Channel of the Detroit River. The concentrations of these compounds were determined in suspended solids collected between 1980 and 1993 in the Niagara River

The effect of spatially randomizing a system of pointlike sources on the propagation of reaction-diffusion fronts is investigated in multidimensions. The dynamics of the reactive front are modeled by superimposing the solutions for diffusion from a single point source. A nondimensional parameter is introduced to quantify the discreteness of the system, based on the characteristic reaction time of sources compared to the diffusion time between sources. The limits to propagation and the average velocity of propagation are expressed as probabilistic quantities to account for the influence of the randomly distributed sources. In random systems, two- and three-dimensional fronts are able to propagate beyond a limit previously found for systems with regularly distributed sources, while a propagation limit in one dimension that is independent of domain size cannot be defined. The dimensionality of the system is seen to have a strong influence on the front propagation velocity, with higher dimensional systems propagating faster than lower dimensional systems. In a three-dimensional system, both the limit to propagation and average front velocity revert to a solution that assumes a spatially continuous source function as the discreteness parameter is increased to the continuum limit. The results indicate that reactive systems are able to exploit local fluctuations in source concentration to extend propagation limits and increase the velocity in comparison to regularly spaced systems.

Diffraction patterns are explained using a matrix of identical coherent point sources, which emit elementary waves. Such a matrix is equivalent to a single point source, whose resultant wave is found by means of well known trigonometric formulas.

In the surface-related multiple elimination (SRME) method the source array is assumed to act as a single stable source. When the behavior of the source array differs too much from this assumption it effects the primary estimation. We will demonstrate this with two cases; unstable sources and large source arrays. We will discuss which measures to take to incorporate the source array in SRME. On the same synthetic data examples we will demonstrate that it is very easy to bring in the source array into the recently introduced estimation of primaries by sparse inversion (EPSI) method. For the unstable source case EPSI can estimate the source wavelet that was used during each shot. For the case of large source arrays EPSI can estimate primary impulse responses from the data as if they came from a single point source acquisition, thus removing the blending effect from the source array.

The scanning properties of shaped reflectors, both offset and circularly symmetric, are examined and compared to conic section scanning characteristics. Scanning of the pencil beam is obtained by lateral and axial translation of a single point source feed. The feed is kept pointed toward the center of the subreflector. The effects of power spillover and aperture phase error as a function beam scanning are examined for several different types of large reflector design including dual-offset, circularly symmetric large f/D, and smaller f/D dual reflector antenna system. It is shown that the Abbe-sine condition for improved scanning of an optical system cannot, inherently, be satisfied in a dual-shaped reflector system that is shaped for high gain and low feed spillover. The gain loss, with scanning, of a high-gain shaped reflector pair is demonstrated to be due to both aperture phase error loss and power spillover loss. >

Responses of Rhagoletis pomonella (Wash) (Diptera: Tephritidae) to synthetic host fruit violates were studied in the field. Individually marked females were released in the centre of a 25 m2 patch containing twenty-five host trees (Crataegus mollis var, toba) and followed as they moved within and between trees. Fly response to three experimental conditions was studied: (1) ‘clean’ air; (2) synthetic host fruit violates (apple) permeating the patch; and (3) a single point source of odour placed c 1m away from the edge of the patch. Files in a patch permeated with host odour moved faster, exhibited more straightened-out moves, and reached the edges of the patch more quickly than those exposed to clean air. Flies exposed to a point source of odour exhibited clear orientation responses, arriving consistently at the tree harbouring the source of odour. Odour exposure was intermittent and usually brief (c. 20s-1 exposure) with intervals between exposure periods averaging 103s. Wind speed and direction were highly variable. Flies moved during wind ranging in speed form 0.5 to 4.4 m s-1, with their activity being greatest at winds below 2m s-1. Strong winds (>3.5 ms-1) either arrested movement or enhanced downwind displacement. Our observations tend to support the ‘series-of-steps’ hypothesis reviewed by Gibson & Brandy (1985) as a mechanism of close-range host location (1-5m from odour source). Our findings are discussed with respect to theoretical and practical implications of insect orientation mechanisms to odours, dispersal, and control strategies.

In this work, a procedure is suggested to assess the rate of biogas emitted by the Bellolampo landfill (Palermo, Italy), starting from the data acquired by two of the stations for monitoring meteorological parameters and polluting gases. The data used refer to the period November 2005–July 2006. The methane concentration, measured in the CEP suburb of Palermo, has been analysed together with the meteorological data collected by the station situated inside the landfill area. In the present study, the methane has been chosen as a tracer of the atmospheric pollutants produced by the dump. The data used for assessing the biogas emission refer to night time periods characterized by weak wind blowing from the hill toward the city. The methane rate emitted by the Bellolampo dump has been evaluated using a Gaussian model and considering the landfill both as a single point source and as a multiple point one. The comparison of the results shows that for a first approximation it is sufficient to consider the landfill of Palermo as a single point source. Starting from the monthly percentage composition of the biogas, estimated for the study period, the rate of biogas produced by the dump was evaluated. The total biogas produced by the landfill, obtained as the sum of the emitted component and the recovered one, ranged from 7519.97 to 10,153.7 m3/h. For the study period the average monthly estimations of biogas emissions into the atmosphere amount to about 60% of the total biogas produced by the landfill, a little higher than the one estimated by the company responsible for the biogas recovery plant at the landfill.

Cn2 profile monitoring usually relies on the exploitation of wavefront slopes correlations or of scintillation pattern correlations in the pupil. Scintillation is rather sensitive to high turbulence layers whereas wavefront correlations are mainly due to layers close to the receiving plane. Reaping the benefits of both phenomenon could ease C n 2 profile restoration. In the small perturbation approximation, correlations of wavefront slopes and scintillation indices recorded with a Shack Hartmann Wavefront Sensor (SHWFS) have been described analytically. We propose to apply this analytical formalism to C n 2 profile retrieval. Two measurement techniques are exposed. In CO-SLIDAR (Coupled SLODAR SCIDAR), SHWFS data recorded on a binary source are exploited to compute both autocorrelations and cross-correlations between the two components of the binary of wavefront slopes, scintillation indices and of their coupling. C n 2 profile is retrieved from the experimentally estimated correlations. SCO-SLIDAR (Single CO-SLIDAR) relies on the same principle as CO-SLIDAR but SHWFS data are recorded on a single point source. Only autocorrelations of wavefront slopes, scintillation indices and of their coupling are exploited. The analytical background of CO-SLIDAR and SCO-SLIDAR C n 2 profile monitoring is reviewed and both techniques are tested on end to end simulation data.

The discovery of the point-like radio source at the center of the Galaxy, colloquially termed Sgr A*, was made in February 1974 by Balick and Brown using the then-new 35km baseline interferometer between Green Bank and a remote site near Huntersville, WV. The highly unusual properties of the radio source are now well studied; however, the story behind the discovery is equally interesting. Although the signal from the source was strong (∼0.5 Jy) and the peak measured surface brightness quite high (∼107K), the interpretation of the signal as a single point source was initially obscured by the odd geometry of the synthesized aperture. In addition, two groups unknowingly competed to make the detection observations, both based on very different scientific rationales. The other group, comprising Downes and Goss, correctly anticipated the astronomical significance of the discovery but could not make their way from Europe to Green Bank when their observations were scheduled in the fall of 1973.

With the smaller physical scale of distributing the radio frequency signal in buildings, distributed antenna systems, which may be too expensive in outdoor systems, become affordable. This paper explores quantitatively and qualitatively the advantages of distributed antenna systems over single point source antenna systems, and develops theorems comparing the two systems based on a two slope path loss model. >

Consider the $\sigma$-finite measure-valued diffusion corresponding to the evolution equation $u_t = Lu + \beta (x) u - f(x,u)$, where $$f(x,u) = \alpha (x)u^2 + \int_0^{\infty} (e^{-ku} - 1 + ku)n(x,dk)$$ and $n$ is a smooth kernel satisfying an integrability condition. We assume that $\beta, \alpha \in C^{\eta}(\mathbb{R}^d)$ with $\eta \in (0,1]$, and $\alpha > 0$. Under appropriate spectral theoretical assumptions we prove the existence of the random measure $$\lim_{t \uparrow \infty} e^{-\lambda_c t} X_t (dx)$$ (with respect to the vague topology), where $\lambda_c$ is the generalized principal eigenvalue of $L + \beta$ on $\mathbb{R}^d$ and it is assumed to be finite and positive, completing a result of Pinsky on the expectation of the rescaled process. Moreover, we prove that this limiting random measure is a nonnegative nondegenerate random multiple of a deterministic measure related to the operator $L + \beta$. ¶ When $\beta$ is bounded from above, $X$ is finite measure-valued. In this case, under an additional assumption on $L + \beta$, we can actually prove the existence of the previous limit with respect to the weak topology. ¶ As a particular case, we show that if $L$ corresponds to a positive recurrent diffusion $Y$ and $\beta$ is a positive constant, then $$\lim_{t \uparrow \infty} e^{-\beta t} X_t (dx)$$ exists and equals a nonnegative nondegenerate random multiple of the invariant measure for $Y$. ¶ Taking $L = 1/2 \Delta$ on $\mathbb{R}$ and replacing $\beta$ by $\delta_0$ (super-Brownian motion with a single point source), we prove a similar result with $\lambda_c$ replaced by 1/2 and with the deterministic measure $e^{-|x| dx$, giving an answer in theaffirmative to a problem proposed by Engländer and Fleischmann [Stochastic Process. Appl. 88 (2000) 37–58]. ¶ The proofs are based upon two new results on invariant curves of strongly continuous nonlinear semigroups.

A ray tracing method is introduced for helping adjustment and spectra analysis of the grazing incidence flat-field imaging soft X-ray spectrometer. For a single point source, the spectra images obtained by separate components, the toroidal mirror, and the grazing incidence flat-field concave grating with varied line spaces are given respectively. The calculated spectral images of the single point source by the spectrometer are also given for comparison with measurements with different experimental alignments.

Mucociliary clearance is impaired in many diseases of the respiratory system. We have developed a method for measuring tracheal mucus velocity by the dynamic study of a single point source of radioactivity deposited in the trachea by cricothyroid injection. Preliminary results suggest that patients with airways disease have very low tracheal mucus velocities (

A screening model (CISP) is presented for the calculation of maximum predicted concentrations from a single point source, which is particularly useful in situations where on-site meteorological measurements are limited or unavailable. CISP utilizes an analytical solution of the advection diffusion equation which is non-Gaussian in form. CISP performance in evaluating maximum ground-level concentrations was compared with that of the Environmental Protection Agency (EPA) Regulatory PTPLU2 Gaussian model.

To calibrate pinhole MicroSPECT system, two improved methods using only a single point source were proposed. The uniqueness of calibration result by the proposed methods was proved theoretically. And simulation calibration of a dual-head system was carried out to validate the performance of the proposed methods. The simulation results show that reasonable calibration error is given by both proposed methods.

Superlenses based on metamaterials are promising candidates for achieving subwavelength resolution. We report here our experimental studies on super-resolution imaging from one-dimensional (1D) negative index metamaterial superlenses at microwave frequencies. The metamaterial structure under investigation is shown to have a left-handed transmission band at frequencies where both effective permittivity and permeability are negative. The retrieved effective parameters are in good agreement with the measurements. We achieved a resolution of 0.2λ by imaging a single point source from a 1D superlens. Moreover, the effect of the superlens' thickness on the resolution is studied. A thicker superlens suffers from more losses, which in turn reduces the resolution. Two point sources that were separated by distances that were smaller than a half-wavelength were successfully resolved with the negative index superlens.