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Non‐invasive wide‐field imaging through dynamic random media is a sought‐after goal with important applications ranging from medical diagnosis to remote sensing. However, some existing methods, such as speckle correlation‐based techniques, are limited in field of view due to the memory effect; while some other methods, such as wavefront shaping and transmission matrix techniques, face considerable challenges when applied in dynamic scenarios because of the complexity involved in modulation and measurement. These limitations significantly impede the effectiveness and applicability of these approaches. Here, the concept of virtual reference light (VRL), which allows for the reconstruction of the original object with just a single‐shot detection of the speckle is proposed. Experimental results demonstrate that the imaging field achieves a 3.8‐fold memory effect range. In the experimental setup, the light source and detector are positioned on one side of the random medium, while the sample is placed on the opposite side, enabling non‐invasive detection. Imaging results with both static and dynamic scattering media are presented to verify the feasibility of the proposed method, offering an effective solution for real‐time target imaging and detection. [ABSTRACT FROM AUTHOR]

The near‐infrared (NIR) light polarization metrology is crucial in a broad area of applications, such as optical sensing, imaging, and communications. The conventional measurement of NIR light polarization requires bulky polarization optics by the spatial or temporal splitting of the input light beam with expensive infrared detectors. Here, an intelligent fiber‐integrated NIR polarimeter based on upconversion nanoparticles (UCNPs) is demonstrated. Er‐doped UCNPs are synthesized in core–shell structures for bright upconversion luminescence (UCL), and the tapered multimode fiber (MMF) is designed for random Rayleigh‐distributed speckles. It is demonstrated for the first time that spectra‐polarization‐dependent upconverted speckle patterns captured by a cost‐effective visible image sensor can be accurately decoded via a deep neural network (ResNet50). The experimental results show that ResNet50 has a recognition accuracy of over 99.5% for the full‐Stokes parameters of NIR light polarization, along with 100% accuracy for the light wavelength ranging from 1535 nm to 1565 nm. The developed intelligent optical sensors provide a new design paradigm for fiber‐integrated multi‐dimensional NIR light field detection and can be applied in fiber‐optic sensors and communications networks. [ABSTRACT FROM AUTHOR]

Speckle tracking imaging is a relatively new technique for obtaining myocardial strain based on the tracking of speckles in gray-scale echocardiographic images. Speckles are acoustic markers that can be tracked from frame to frame over the cardiac cycle, providing non-Doppler information about global and segmental myocardial deformation. In this article, the general principles of good practice of echocardiography will be revisited in order to obtain a better evaluation of myocardial deformition and to optimize these clinical contributions in current practice. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of gradient interface on the mechanical properties of Cu/WCP functional gradient materials, digital image correlation technique was used to analyze the mechanical characteristics of laminated Cu/WCP functional gradient material under tension load in the layer direction. In this paper, the deformation information of the specimens is obtained by the digital image correlation method. In order to obtain high-precision measurement results, speckle patterns with small spots and uniform distribution are prepared on the specimen surface by using small sample speckle preparation technology. The tensile experimental results showed that the incorporation of WC particles significantly improved the stiffness and strength of Cu/WCP composites. Meanwhile, the plastic strain and plastic strain rate are non-uniform in each layer of the five-layer Cu/WCP functional gradient material under the tension load along the layer direction. The plastic strain and plastic strain rate in each layer gradually increase along with the decreasing direction of WC content. It is found, from the analysis of experimental results, the existence of the gradient interface has an obvious inhibitory effect on the increase in plastic strain rate along the decreasing direction of WC content, and the specimen fracture location also has a certain relationship with the plastic strain rate, which reflects the important influence of the gradient interface on the mechanical properties of Cu/WCP functional gradient materials. [ABSTRACT FROM AUTHOR]

Plastic strains arising in the zone of fatigue crack initiation are estimated with the aid of time-averaged speckle images on a sample of 09G2S steel with two grooves 2.5 mm in radius. It is shown that the fatigue fracture appears owing to localization of irreversible processes in the region less than 1 mm and the limit value of tension plastic strains is on the order of 10–1. As an indication of fracture, it is proposed to use the fact that the normed temporal autocorrelation function of radiation intensity reduces to a negative value. [ABSTRACT FROM AUTHOR]

The assembly and activation of the spliceosome rely upon the phosphorylation of an essential family of splicing factors known as the serine–arginine (SR) proteins. Although it has been demonstrated recently that two enzyme families, the SR protein kinases (SRPKs) and the Cdc2‐like kinases (CLKs), can function as a complex to efficiently phosphorylate these SR proteins in the nucleus, the molecular features involved in such a connection are unknown. In this study, we identified a group of conserved residues in the large lobe of SRPK1 that interact with the N terminus of CLK1 stabilizing the SRPK1‐CLK1 complex. Mutations in this motif not only disrupt formation of the kinase–kinase complex but also impair SRPK1‐dependent release of the phospho‐SR protein from CLK1. The binding motif potently up‐regulates CLK1‐specific phosphorylation sites, enhances SR protein diffusion from nuclear speckles, and impacts the alternative splicing of several target genes. These results indicate that CLK1 binds a conserved, electronegative surface on SRPK1, thereby controlling SR protein phosphorylation levels for enhanced subnuclear trafficking and alternative splicing regulation. [ABSTRACT FROM AUTHOR]

Paper described a simplified speckled elimination algorithm for the reconstruction of continuous-wave (CW) Doppler ultrasound spectrogram. Standard Nonlinear Anisotropic Diffusion (SNAD) technique fails to eliminate the speckle noise, blurs the interregional area of neighbouring speckle clusters and regulates the heat flow to preserve the systolic and diastolic peaks in the spectrogram. To resolve this problem, author modelled a kernel, conductance and diffusion function to regulate the blurring of speckle clusters and sharpen the high-contrast edges over low-contrast ones. Paper analysed the performance based on the variation of conductance (C), signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), mean square error (MSE), root mean square error (RMSE) and structural similarity index (SSIM) of each pairs of speckled and despeckled spectrograms. Quantitative analysis reveals that the minimised version of the kernel effectively regulates the flow of heat at edges with a high SNR (8 dB) and PSNR (>20 dB) for a low-frequency range of 20-25 Hz. SSIM (>0.9) shows an efficient structural reconstruction that identifies the lower and higher local SSIM indices as dark and bright pixels on SSIM maps. Hence, the algorithm performs its best at lower peak frequencies in the Doppler spectrograms. [ABSTRACT FROM AUTHOR]

RNAs play diverse roles in formation and function of subnuclear compartments, most of which are associated with active genes. NEAT1 and NEAT2/MALAT1 exemplify long non-coding RNAs (lncRNAs) known to function in nuclear bodies; however, we suggest that RNA biogenesis itself may underpin much nuclear compartmentalization. Recent studies show that active genes cluster with nuclear speckles on a genome-wide scale, significantly advancing earlier cytological evidence that speckles (aka SC-35 domains) are hubs of concentrated pre-mRNA metabolism. We propose the 'karyotype to hub' hypothesis to explain this organization: clustering of genes in the human karyotype may have evolved to facilitate the formation of efficient nuclear hubs, driven in part by the propensity of ribonucleoproteins (RNPs) to form large-scale condensates. The special capacity of highly repetitive RNAs to impact architecture is highlighted by recent findings that human satellite II RNA sequesters factors into abnormal nuclear bodies in disease, potentially co-opting a normal developmental mechanism. [ABSTRACT FROM AUTHOR]

The mammalian genome is complex and presents a dynamic structural organization that reflects function. Organization of the genome inside the mammalian nucleus impacts all nuclear processes including but not limited to transcription, replication and repair, and in many biological contexts such as early development, differentiation and physiological adaptations. However, there is limited understating of how 3D organization of the mammalian genome regulates different nuclear processes. Recent advances in microscopy and a myriad of genomics methods—propelled by next-generation sequencing—have advanced our knowledge of genome organization to a great extent. In this review, we discuss nuclear compartments in general and recent advances in the understanding of how mammalian genome is organized in these compartments with an emphasis on dynamics at the nuclear periphery. [ABSTRACT FROM AUTHOR]

On the basis of fragments of time-averaged speckle images registered with no stopping of cyclic loading, the features of nucleation, onset, and propagation of a crack in the bulk of a transparent prismatic sample with a sharp V-shaped notch have been found. It has been shown that the first signs of fatigue damage occur not at the top of the notch, but at a distance of 400 μm from it in the sample center within an area with a diameter of 200 μm. After the beginning of the development ("onset") of the crack, the size of the zone of irreversible processes exhibits an increase by an order of magnitude. The distribution of the refractive index and the density around the crack has been studied based on changing speckle images and with the use of ellipsometry. It has been shown that the maximum value of relative change in density being at least 2 × 10–3, is located near the crack. The speckle method can serve a basis for the development of nondestructive testing tools and techniques that make it possible to assess the time preceding crack onset according to the changing rate and the limiting values of the refractive index and material density, as well as according to other parameters affecting the change in the optical paths of waves within small areas about 10 μm in size. [ABSTRACT FROM AUTHOR]

In the article "Intelligent Optical Fiber-Integrated Near-Infrared Polarimeter Based on Upconversion Nanoparticles," Yi Xu, Ai-Hua Li, Huanyang Chen, Jin-hui Chen, and colleagues present a new design for an intelligent fiber-integrated near-infrared (NIR) light field sensor. The sensor is based on upconversion nanoparticles (UCNPs) and tapered multimode fiber. The researchers demonstrate that the sensor can accurately decode spectra-polarization-dependent upconverted speckled patterns using a deep neural network. This development has potential applications in fiber-optic sensors and communications networks, providing a new design paradigm for multi-dimensional NIR light field detection. [Extracted from the article]

Triangulation-based three-dimensional (3-D) optical metrology utilizing structured illumination requires the projector and camera to be geometrically calibrated. The projection of laser speckle structures in temporal correlation-based methods has been found to be useful for high-speed 3-D measurement. However, it requires the use of a stereo-camera configuration as speckle projection does not utilize conventional projection optics. Previously, we have shown a model-less method to calibrate these unconventional projection systems. This re-enabled singlecamera setups where stereo systems used to be required. Due to the random nature of speckle production, speckle structures were not suitable as a set of repeatable illumination structures is needed for the model-less calibration method to succeed. A projection apparatus is proposed, which enables the production of a repeatable set of speckle structures. This device is then utilized in a single-camera optical metrology 3-D measurement system. [ABSTRACT FROM AUTHOR]

Speckle techniques, such as DIC (Digital Image Correlation) and DSP (Digital Speckle Photography), are frequently used to determine the high-temperature mechanical properties of materials. Speckle techniques require the creation of a random speckle pattern on the surface of the specimen. The most commonly used approach to creating a high-contrast speckle pattern is to spray a layer of black paint particles on a white background. However, in a high-temperature environment, the paint particles tend to peel off or burn off. In this paper, we present an approach that uses a novel laser-engraving technology, where the created speckles will sustain temperatures as high as the melting temperature of the specimen. The size, density, depth and distribution of the speckles can be controlled to suit a particular situation. Since the pattern is part of the specimen, it will never disappear, until the melting temperature of the metal is reached. As an application, we used the technique to determine the elastic modulus of Ti up to 600°C and tungsten up to 1000°C. [ABSTRACT FROM AUTHOR]

Myosin VI (MVI) is a unique actin-based motor protein moving towards the minus end of actin filaments, in the opposite direction than other known myosins. Besides well described functions of MVI in endocytosis and maintenance of Golgi apparatus, there are few reports showing its involvement in transcription. We previously demonstrated that in neurosecretory PC12 cells MVI was present in the cytoplasm and nucleus, and its depletion caused substantial inhibition of cell migration and proliferation. Here, we show an increase in nuclear localization of MVI upon cell stimulation, and identification of potential nuclear localization (NLS) and nuclear export (NES) signals within MVI heavy chain. These signals seem to be functional as the MVI nuclear presence was affected by the inhibitors of nuclear import (ivermectin) and export (leptomycin B). In nuclei of stimulated cells, MVI colocalized with active RNA polymerase II, BrUTP-containing transcription sites and transcription factor SP1 as well as SC35 and PML proteins, markers of nuclear speckles and PML bodies, respectively. Mass spectrometry analysis of samples of a GST-pull-down assay with the MVI tail domain as a "bait" identified several new potential MVI binding partners. Among them are proteins involved in transcription and post-transcriptional processes. We confirmed interaction of MVI with heterogeneous nuclear ribonucleoprotein U (hnRNPU) and nucleolin, proteins involved in pre-mRNA binding and transport, and nucleolar function, respectively. Our data provide an insight into mechanisms of involvement of MVI in nuclear processes via interaction with nuclear proteins and support a notion for important role(s) for MVI in gene expression. [ABSTRACT FROM AUTHOR]

Single sensor (pixel) signals require scanning of the sample in order to obtain spatial information. In this paper we show that using interference, optically induced signals can be reconstructed when recorded using interference pattern excitation, rather than a point illumination. This method reduces the need for dense scanning and requires a small number of scans, or can eliminate the need for scanning in some cases. It is shown that this method can be used in particular in 2D photo-acoustic imaging. [ABSTRACT FROM AUTHOR]

Stochastic interference of fluorescence light outgoing from a dye-doped coarse-grained random medium, which was pumped by the continuous-wave laser radiation, was experimentally studied. It was found that the contrast of random interference patterns highly correlates with the wavelength-dependent fluorescence intensity and reaches its minimum in the vicinity of the cusp of emission spectrum. The decay in the contrast of spectrally selected speckle patterns was interpreted in terms of the pathlength distribution broadening for fluorescence radiation propagating in the medium. This broadening is presumably caused by the wavelength-dependent negative absorption of the medium. [ABSTRACT FROM AUTHOR]

The advance in biochemical and microscopy techniques has revealed the complexity and intricate nucleoplasm structure. Several subcompartments were identified in nucleus and the importance of these subcompartments in processes crucial for normal nuclear activity has been demonstrated. In this mini-review, we will give an overview about the composition, function, and importance of the major nuclear subcompartments. Also, we will show the impact that perturbing these structures can cause in normal nuclear activity, and how these can contribute to the development of some human diseases. [ABSTRACT FROM AUTHOR]

Theory of the speckle dynamics arises in the image plane of the object as a result of deterministic and random displacements of point scattering centers are considered. It was shown that time-average radiation intensity and the correlation coefficient of the speckle image segment depend on the average value, variance, and the correlation time of displacement difference of the scattering center pairs. The sensitivity, accuracy, and calibration of the method are considered. Application of the technique in studies of micro-and macroprocesses in high-cycle fatigue of metals and in a monolayer of live cells is given. [ABSTRACT FROM AUTHOR]

The use of objective speckles as patterns is of high interest for the ongoing development of stereo photogrammetry. The depth of focus of the projected speckle patterns, which can be found to be several meters, can hardly be matched by other projection principles. On the downside, the use of coherent light leads to subjective speckles generated by the rough surface of the object under test. This effect decreases the accuracy under which objects can be reconstructed. We show how laser-based stereo photogrammetry can be adjusted to increase the measurement accuracy of three-dimensional (3-D)-surface measurements while preserving the advantages of speckles projection. Therefore, we present a method to decrease the contrast of subjective speckles in the images by pixel-wise shifting the cameras orthogonally to their viewing direction and back shifting the taken images numerically, accordingly. This leads to an increase in 3-D-reconstruction quality, as seen in a decrease in standard deviation, peak-to-valley value and in an increase in the number of reconstructed points for measured test objects. [ABSTRACT FROM AUTHOR]

A frequently observed characteristic of electromagnetic scattering by a disordered particulate medium is the absence of pronounced speckles in angular patterns of the scattered light. It is known that such diffuse speckle-free scattering patterns can be caused by averaging over randomly changing particle positions and/or over a finite spectral range. To get further insight into the possible physical causes of the absence of speckles, we use the numerically exact superposition T -matrix solver of the Maxwell equations and analyze the scattering of plane-wave and Gaussian beams by representative multi-sphere groups. We show that phase and amplitude variations across an incident Gaussian beam do not serve to extinguish the pronounced speckle pattern typical of plane-wave illumination of a fixed multi-particle group. Averaging over random particle positions and/or over a finite spectral range is still required to generate the classical diffuse speckle-free regime. [ABSTRACT FROM AUTHOR]

The data on changes in light scattering intensity with time at 330°C after stabilization of the sample at 200°C were obtained using the temperature jump method. It was found that the time dependence of the polarized component at 330°C can be divided into two stages. The first stage involves the initial times and is characterized by the formation of the maximum, which corresponds to the universal effect caused by the emergence of a peak of intensity in the glass-transition interval of oxide glass. The second stage is associated with a decrease in intensities with the characteristic times being significantly longer than the structural relaxation times. The anisotropic scattering intensity was found to increase during low-temperature stabilization at 200°C, while the isotropic scattering intensity remained constant. The behavior of intensity became nonergodic as a result of the long-term heating of the sample: the intensity started to depend on the position of the scattering volume. It was demonstrated that the shape of the fleck from the primary light beam that has passed through the sample can be significantly changed and acquire a speckle structure. A hypothesis was put forward that the detected features in the behavior of light scattering intensity are associated with the development of large-scale structures in the glass volume. [ABSTRACT FROM AUTHOR]

• Speckle preparation by femtosecond laser engraving for digital image correlation with fully manipulatable features, minimized damage and heat effect was proposed in this work. • Laser parameters were optimized based on speckle quality and measurement errors. • Damage of femtosecond laser to thin film sample was calculated by two-temperature model, which agrees well with experiment results. Deformation measurement in thin films at elevated temperatures is critical for assessing the reliability and performance of microelectronic devices. Digital image correlation (DIC) is a full-field, noncontact deformation measurement technique. However, the traditional DIC approach requires spraying paints for speckles, which is not suitable for high-temperature applications. The aim of this work is to propose a fully customizable speckle preparation method by pulsed laser that can deliver ideal speckle pattern, good contrast and consistency and controllable damage to sample for deformation measurement at elevated temperatures by DIC. Al thin films deposited on Si substrates were used for speckle preparation by FLs at different powers (10 mW, 8 mW, 6 mW and 4 mW). Serial images of speckles were captured as the temperature increased from room temperature to 325 °C, followed by data analysis. A finite element model was built to evaluate the deviation of measured strains in Al thin film from ideal values. To evaluate the damage of laser to sample surface during speckle preparation, a two-temperature model (TTM) was used to evaluate the ideal ablation depth at different laser fluences. Scanning electron microscopy and white light interferometry were also used to examine the surface damage and depth of holes. Based on our findings, speckles prepared by laser irradiation at 8 mW have the best speckle quality and measurement accuracy. The depth of speckles increased linearly with increasing laser power, ranging from 11.8 to 32.9 nm. The ideal depth calculated by the TTM was slightly lower than the experimental results, which can be attributed to the parameters of the model deviating from the actual sample (such as the reflectance of Al). DIC with speckles prepared by an FL can provide good measurement accuracy at elevated temperatures while causing minimal damage to the sample. [ABSTRACT FROM AUTHOR]

We report the results of modeling the speckle structure of an optical field, which arises due to scattering of laser radiation at the retina of the human eye. The presence of such a speckle structure in the scattered radiation leaving the eye affects the accuracy of wavefront measurements aimed at determining the overall aberrations of the eye. We compared two methods for suppressing such speckle structures based on spatial and spectral averaging of a variety of speckle field realizations. The results of both theoretical calculations and numerical simulations appeared to be in a good agreement with experimental data obtained with the eye model andin vivo. [ABSTRACT FROM PUBLISHER]

‘Flying Triangulation’ (FlyTri) is a recently developed principle which allows for a motion-robust optical 3D measurement of rough surfaces. It combines a simple sensor with sophisticated algorithms: a single-shot sensor acquires 2D camera images. From each camera image, a 3D profile is generated. The series of 3D profiles generated are aligned to one another by algorithms, without relying on any external tracking device. It delivers real-time feedback of the measurement process which enables an all-around measurement of objects. The principle has great potential for small-space acquisition environments, such as the measurement of the interior of a car, and motion-sensitive measurement tasks, such as the intraoral measurement of teeth. This article gives an overview of the basic ideas and applications of FlyTri. The main challenges and their solutions are discussed. Measurement examples are also given to demonstrate the potential of the measurement principle. [ABSTRACT FROM PUBLISHER]

In this paper we show how a novel photonic remote sensing system assembled on a robotic platform can extract vital biomedical parameters from cattle including their heart beating, breathing and chewing activity. The sensor is based upon a camera and a laser using self-interference phenomena. The whole system intends to provide an automatic solution for detection, identification and biomedical monitoring of a cow. The detection algorithm is based upon image processing involving probability map construction. The identification algorithms involve well known image pattern recognition techniques. The sensor is used on top of an automated robotic platform in order to support animal decision making. Field tests and computer simulated results are presented. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the localization properties of the single particle spectrum of a one-dimensional speckle potential in a box. We consider both the repulsive and the attractive cases. The system is controlled by two parameters: the size of the box and a rescaled potential intensity. The latter is a function of the particle mass, the correlation length and the average intensity of the field. Depending on both these parameters values and the considered energy level, the eigenstates exhibit different regimes of localization. In order to identify the regimes for the excited states, we use a technique developed in this work. Depending on the chosen parameters values, we find that it is possible not observing any effective mobility edge nor delocalization of the eigenstates due to the finite size of the system. [Copyright &y& Elsevier]

We examined the dynamics of two populations of self-trapped filaments of spatially and temporally incoherent white light. The populations consisted of (i) independent filaments generated through self-trapping of incandescent speckles, and (ii) co-dependent filaments created through modulation instability of a broad incandescent beam. Both filament populations were positionally stable in conditions where individual pairs of self-trapped beams interact strongly. Both also acquired significantly broad intensity distributions, which were independent of their parent optical fields; a small but persistent number of high-intensity filaments was identified in both cases. These studies provide accessible routes to weakly correlated ensembles, insight into their collective behaviour such as self-stabilization and self-selected intensity distributions, and reveal intriguing similarities between the dynamics of two populations of different origins. [ABSTRACT FROM AUTHOR]

Abstract: The effect of competition of laser light absorption and scattering in dispersive media (1μm polystyrene microspheres in ethylene glycol) with added dye (rhodamine 6G) was studied under the condition of near-resonant absorption of probe light in the host medium (solution of rhodamine 6G in ethylene glycol). The parameters of speckle modulation of transmitted light (the average speckle intensity and the oscillation index) were applied for characterization of light transport in the probed scattering systems as a function of dye concentration. The increase in dye concentration does not cause the expected decay in the transmittance of the examined dispersive systems for 532nm laser light, but results in the decrease of their turbidity. This effect is accompanied by the rise of the average intensity and the oscillation index of speckle-modulated light, and can be rationalized by partial matching of the real parts of refractive indices for the host medium and embedded scatterers. This interpretation was supported by statistical modeling of light transport through the examined scattering systems. [Copyright &y& Elsevier]

Abstract: In a coherent x-ray scattering experiment, interference of the waves diffracted across the sample is observed. This gives a speckle pattern in the observed scattering intensity, whereas a standard experiment leads to diffuse intensity or to broadening of a Bragg peak. Speckles correspond to the disorder configuration of the irradiated volume and their dynamics provide microscopic information of the time evolution of the sample microstructure. After a brief description of the techniques used for the observation of speckles in an x-ray experiment, some examples of measured time dynamics are given. These concern reversible fluctuations and irreversible decomposition of unmixing or ordering alloys. A few experiments in defect imaging are described and the studies opened by free electron lasers are briefly discussed. [Copyright &y& Elsevier]

Abstract: Using coherent X-ray scattering, we evidenced atomic step roughness at the (111) vicinal surface of a silicon monocrystal of 0.05° miscut. Close to the anti-Bragg position of the reciprocal space which is particularly sensitive to the (111) surface, the truncation rod exhibits a contrasted speckle pattern that merges into a single peak closer to the 111 Bragg peak of the bulk. The elongated shape of the speckles along the (111) direction confirms the monoatomic step sensitivity of the technique. This experiment opens the way towards studies of step dynamics on crystalline surfaces. [ABSTRACT FROM AUTHOR]

Extremal properties of the statistics of speckle pattern are studied in the context of so-called “optically smoothed” light beams of laser-matter interaction. It is shown that the asymptotic statistics of the highest intensity in a speckle pattern, which can be associated with the most intense speckles, follows a Gumbel law, which is in agreement with numerical simulations. It is found that the probability density function of the most intense speckle peaks around the value corresponding to the logarithm of the number of speckles in the considered volume times the average intensity value of the speckle pattern. This result is of great interest for nonlinear processes, like instabilities, where extreme speckles play an important role. [ABSTRACT FROM AUTHOR]

Abstract: Recently the investigation of non-stationary systems exhibiting spatial and dynamic heterogeneities has propelled the development of innovative optical techniques providing the missing link between the scattering and imaging approaches. The novel techniques are characterized by the fact that the scattered radiation is measured close to the sample. They allow to recover information on the structure and dynamics of the system under investigation equivalent to that available with scattering techniques, with the great advantage that they simultaneously allow to achieve a local characterization of the sample, which is lost in traditional scattering measurements. [Copyright &y& Elsevier]

The nucleus is highly compartmentalized through the formation of distinct classes of membraneless domains. However, the composition and function of many of these structures are not well understood. Using APEX2-mediated proximity labeling and RNA sequencing, we surveyed human transcripts associated with nuclear speckles, several additional domains, and the lamina. Remarkably, speckles and lamina are associated with distinct classes of retained introns enriched in genes that function in RNA processing, translation, and the cell cycle, among other processes. In contrast to the lamina-proximal introns, retained introns associated with speckles are relatively short, GC-rich, and enriched for functional sites of RNA-binding proteins that are concentrated in these domains. They are also highly differentially regulated across diverse cellular contexts, including the cell cycle. Thus, our study provides a resource of nuclear domain-associated transcripts and further reveals speckles and lamina as hubs of distinct populations of retained introns linked to gene regulation and cell cycle progression. [Display omitted] • Transcripts associated with diverse nuclear domains mapped using APEX2-seq • Speckles and lamina associate with functionally distinct classes of retained introns • Speckle-retained introns are enriched in RNA processing and cell-cycle factors • Speckle-associated retained intron splicing is linked to cell-cycle progression Barutcu, Wu et al. use marker proteins fused to APEX2 to survey coding and non-coding transcripts concentrated in diverse nuclear domains. Speckles and lamina are found to associate with structurally and functionally distinct classes of retained introns implicated in the control of core cellular processes, including the cell cycle. [ABSTRACT FROM AUTHOR]

The Monte Carlo method is used to simulate the light propagation in nano-fluids, and thus to understand the interesting phenomena, which are formed as speckles are when nano-fluids are illuminated by laser light [I]. A physical model has been created, considering the random collisions between photons and nano-particles and yet another model has been produced, which considered that nano-particles are evenly distributed in the vessel containing the nano-fluids. On the basis of these two models, light propagation in nano-fluids is simulated by tracking the movement of each photon thereby obtaining the photon distribution on the receiving screen. The simulation results are in good agreement with the experimental phenomenon and the speckle-formation-mechanism has been resolved. [ABSTRACT FROM AUTHOR]

Speckle structure of parametric down conversion light has recently received much attention owing to its relevance in view of applications to quantum imaging. The possibility of tailoring the speckle size by acting on the pump properties is an interesting tool for the applications to quantum imaging and in particular to the detection of a weak object under the shot-noise limit. Here we present a systematic detailed experimental study of the speckle structure produced in type II PDC with particular attention to its variation with pump beam properties. [ABSTRACT FROM AUTHOR]

Abstract: SR proteins are multidomain splicing factors which are important for spliceosome assembly and for regulation of alternative splicing. In mammalian nuclei these proteins localise to speckles from where they are recruited to transcription sites. By using fluorescent protein fusion technology and different experimental approaches it has been shown that Arabidopsis SR proteins, in addition to diffuse nucleoplasmic staining, localise into an irregular nucleoplasmic network resembling speckles in mammalian cells. As Arabidopsis SR proteins fall into seven conserved sub-families we investigated co-localisation of members of the different sub-families in transiently transformed tobacco protoplast. Here we demonstrate the new finding that members of different SR protein sub-families localise into distinct populations of nuclear speckles with no, partial or complete co-localisation. This is particularly interesting as we also show that these proteins do interact in a yeast two-hybrid assay as well as in pull-down and in co-immunopreciptiation assays. Our data raise the interesting possibility that SR proteins are partitioned into distinct populations of nuclear speckles to allow a more specific recruitment to the transcription/pre-mRNA processing sites of particular genes depending on cell type and developmental stage. [Copyright &y& Elsevier]

Abstract: In this paper we study an initial-boundary-value problem for the Zakharov equations, describing the space propagation of a laser beam entering a plasma. We prove a strong instability result and prove that the mathematical problem is ill-posed in Sobolev spaces. We also show that it is well posed in spaces of analytic functions. Several consequences for the physical consistency of the model are discussed. [Copyright &y& Elsevier]

Abstract: This article reviews the literature on X-ray fluctuation intensity spectroscopy or, as it is often called, X-ray photon correlation spectroscopy. It highlights measurements using different types of diffuse scattering. To cite this article: M. Sutton, C. R. Physique 9 (2008). [Copyright &y& Elsevier]

Abstract: A novel method is proposed for motion imaging of objects in layers hidden by a scattering medium in a depth-resolved manner by means of the intensity difference in a temporal sequence of low-coherence speckle images. Depth-resolved motion imaging was demonstrated with a semi-transparent scattering plate and an aluminum diffusive plate behind Intralipid solution. Experimental results confirmed feasibility of the proposed method for imaging of moving objects by their relative velocity. [Copyright &y& Elsevier]

Abstract: Lamin A/C is the most studied nucleoskeletal constituent. Lamin A/C expression indicates cell differentiation and is also a structural component of nuclear speckles, which are involved in gene expression regulation. Hypertonicity has been reported to induce renal epithelial cell differentiation and expression of TonEBP (NFAT5), a transcriptional activator of hypertonicity-induced gene transcription. In this paper, we investigate the effect of hypertonicity on lamin A/C expression in MDCK cells and the involvement of TonEBP. Hypertonicity increased lamin A/C expression and its distribution to nucleoplasm with speckled pattern. Microscopy showed codistribution of TonEBP and lamin A/C in nucleoplasmic speckles, and immunoprecipitation demonstrated their interaction. TonEBP silencing caused lamin A/C redistribution from nucleoplasmic speckles to the nuclear rim, followed by lamin decrease, thus showing that hypertonicity induces lamin A/C speckles through a TonEBP-dependent mechanism. We suggest that lamin A/C speckles could serve TonEBP as scaffold thus favoring its role in hypertonicity. [Copyright &y& Elsevier]

Abstract: High-dynamic range imaging from space in the visible light range, aiming, in particular, at the detection of terrestrial exoplanets, necessitates not only the use of a coronagraph, but also of adaptive optics to correct optical defects in real time. Indeed, these defects scatter light and give birth to speckles in the image plane. Speckles can be cancelled by driving a deformable mirror to measure and compensate wavefront aberrations. In a first approach, targeted speckle nulling, speckles are cancelled iteratively by starting with the brightest ones. This first method has demonstrated a contrast better than 109 in laboratory. In a second approach, zonal speckle nulling, the total energy of speckles is minimized in a given zone of the image plane. This second method has the advantage of tackling simultaneously all speckles from the targeted zone, but it still needs better experimental demonstration. To cite this article: P. Bordé, W. Traub, C. R. Physique 8 (2007). [Copyright &y& Elsevier]

Abstract: During transcription inactivation, the nuclear bodies in the mammalian cells often undergo reorganization. In particular, the interchromatin granule clusters, or IGCs, become colocalized with RNA polymerase II (RNAP II) upon treatment with transcription inhibitors. This colocalization has also been observed in untreated but transcriptionally inactive cells. We report here that the reorganized IGC domains are unique substructure consisting of outer shells made of SC35, ERK2, SF2/ASF, and actin. The apparently hollow holes of these domains contain clusters of RNAP II, mostly phosphorylated, and the splicing regulator SMN. This class of complexes are also the sites where prominent transcription activities are detected once the inhibitors are removed. Furthermore, actin polymerization is required for reorganization of the IGCs. In connection with this, immunoprecipitation and immunostaining experiments showed that nuclear actin is associated with IGCs and the reorganized IGC domains. The study thus provides further evidence for the existence of an actin-based nuclear skeleton structure in association with the dynamic reorganization processes in the nucleus. Overall, our data suggest that mammalian cells have adapted to utilize the reorganized, uniquely shaped IGC domains as the temporary storage sites of RNAP II transcription machineries in response to certain transient states of transcription inactivation. [Copyright &y& Elsevier]

A straightforward way of measuring X-ray intensity fluctuation spectroscopy in a small-angle X-ray scattering configuration is demonstrated using heterodyne techniques. Two examples are presented: the Brownian motion of latex spheres in glycerol, and a Doppler velocity experiment demonstrating the motion and the relaxation of carbon-black-filled elastomers after uniaxial stretching. In the latter case the effects of mechanical relaxation can be separated from those of aggregate diffusion. The results suggest that the dynamics of these filled elastomers are similar to the universal features observed in disordered jammed systems. [ABSTRACT FROM AUTHOR]

Abstract: Wilm''s tumor protein 1 (WT1), a protein implicated in various cancers and developmental disorders, consists of two major isoforms: WT1(−KTS), a transcription factor, and WT1(+KTS), a post-transcriptional regulator that binds to RNA and can interact with splicing components. Here we show that WT1 interacts with the novel splicing regulator RBM4. Each protein was found to colocalize in nuclear speckles and to cosediment with supraspliceosomes in glycerol gradients. RBM4 conferred dose-dependent and cell-specific regulation of alternative splicing of pre-mRNAs transcribed from several reporter genes. We found that overexpressed WT1(+KTS) abrogated this effect of RBM4 on splice-site selection, whereas WT1(−KTS) did not. We conclude that the (+KTS) form of WT1 is able to inhibit the effect of RBM4 on alternative splicing. [Copyright &y& Elsevier]

Abstract: In this paper, a filtering technique based upon two-dimensional continuous wavelet transform (2D-CWT) is used to eliminate the low frequency components of fringe patterns. The filtered fringe patterns are subsequently demodulated using a standard Fourier transform profilometry (FTP) algorithm. This image pre-filtering stage improves the noise performance of the FTP algorithm and enables the FTP method to demodulate fringe patterns with larger bandwidths. Also, the 2D-CWT technique reduces speckle noise significantly. Moreover, only a single fringe pattern is required in this technique. The 2D-CWT algorithm is capable of separating low frequency terms from the high frequency terms that contain phase-modulated fringe information, even when both interfere, greatly, in the frequency domain. The proposed algorithm is tested, both via computer simulation and using real fringe patterns. This revealed the robustness of this algorithm and also demonstrably enables the demodulation of a wider range of fringe patterns using the FTP technique. [Copyright &y& Elsevier]

Basonuclin (bn) 1 possesses three separated pairs of zinc fingers and a nuclear localization signal. It is largely confined to the basal cells of stratified squamous epithelia and to reproductive germ cells. bn1 can shuttle between the nucleus and the cytoplasm, and its location is correlated with the proliferative potential of the cell. The recently discovered bn2 also possesses three separated pairs of zinc fingers and a nuclear localization signal. Conservation of the zinc fingers and the nuclear localization signal by bn1 and bn2 indicates a common origin. However, in contrast to bn1, bn2 is found in virtually every cell type and is confined to the nucleus. Bn2 but not bn1 colocalizes with SC35 in nuclear speckles and, therefore, is likely to have a function in nuclear processing of mRNA. [ABSTRACT FROM AUTHOR]

Abstract: We show that the time evolution of near-field scattering speckles, originated by a fluid suspension of particles, provides information about the velocity field in the fluid. This information can be extracted from a statistical analysis of speckle fields taken at different times, either by measuring their cross-correlation function or by recovering the power spectrum corresponding to the difference between the two speckle fields. Experimental data are in accordance to the expected behaviors. The results are independent of the scatterer''s size, allowing one to exploit the technique also with sub-wavelength tracking particles. [Copyright &y& Elsevier]

Abstract: We report on a technique to recover the spatial resolution of digitally recorded and reconstructed holograms of large objects. Due to the high-contrast speckle noise diminishes the spatial resolution in coherent imaging systems our proposal is based on the reduction of the contrast of it. This aim is achieved through the superposition on an intensity basis of digitally reconstructed holograms of the same static scene. We show a theoretical justification of the procedure and experimentally-obtained results of applying the technique with digitally reconstructed holograms of an object with very poor optical contrast. [Copyright &y& Elsevier]