On the Digital Holographic Interferometry of Fibrous Material, I. Optical Properties of Polymer and Optical Fibers

The digital holographic interferometry (DHI) was utilized for investigating the optical properties of polymer and optical fibers. The samples investigated here were polyvinylidene fluoride (PVDF) polymer fiber and graded-index (GRIN) optical fiber. The phase shifting Mach-Zehnder interferometer was used to obtain five phase-shifted holograms, in which the phase difference between two successive holograms is pi/2, for each fiber sample. These holograms were recorded using a CCD camera and were combined to gain a complex wavefield, which was numerically reconstructed using the convolution approach into amplitude and phase distributions. The reconstructed phase distribution was used to determine the refractive index, birefringence and refractive index profile of the studied samples. The mean refractive index has been measured with accuracy up to 4 {\times} 10-4. The main advantage of DHI is to overcome the manual focusing limitations by means of the numerical focusing. The results showed accurate measurements of the optical properties of fibers.Comment: abstract, reference

Nonlocal similarity image filtering

Abstract. We exploit the recurrence of structures at different locations, orientations and scales in an image to perform denoising. While previous methods based on “nonlocal filtering ” identify corresponding patches only up to translations, we consider more general similarity transformations. Due to the additional computational burden, we break the problem down into two steps: First, we extract similarity invariant descriptors at each pixel location; second, we search for similar patches by matching descriptors. The descriptors used are inspired by scale-invariant feature transform (SIFT), whereas the similarity search is solved via the minimization of a cost function adapted from local denoising methods. Our method compares favorably with existing denoising algorithms as tested on several datasets.

The incremental validity of borderline personality disorder relative to major depressive disorder for suicidal ideation and deliberate self-harm in adolescents

Few studies have examined the relation between suicide-related behaviors and Borderline Personality Disorder (BPD) in adolescent samples. The current study investigated the incremental validity of BPD relative to Major Depressive Disorder (MDD) for suicide-related behaviors in a psychiatric sample of adolescents at the cross-sectional level of analysis. The sample included N = 156 consecutive admissions (55.1% female; M age = 15.47; SD = 1.41), to the adolescent treatment program of an inpatient treatment facility. Of the sample 19.2% (n = 30) met criteria for BPD on the Child Interview for DSM-IV Borderline Personality Disorder and 39.1% (n = 61) met criteria for MDD on the Computerized Diagnostic Interview Schedule for Children-IV. Results showed that BPD conferred additional risk for suicidal ideation and deliberate self-harm. Our findings support the clinical impression that BPD should be evaluated in inpatient samples of adolescents either through intake interviews or more structured assessments

Noninvasive optical inhibition with a red-shifted microbial rhodopsin

Optogenetic inhibition of the electrical activity of neurons enables the causal assessment of their contributions to brain functions. Red light penetrates deeper into tissue than other visible wavelengths. We present a red-shifted cruxhalorhodopsin, Jaws, derived from Haloarcula (Halobacterium) salinarum (strain Shark) and engineered to result in red light–induced photocurrents three times those of earlier silencers. Jaws exhibits robust inhibition of sensory-evoked neural activity in the cortex and results in strong light responses when used in retinas of retinitis pigmentosa model mice. We also demonstrate that Jaws can noninvasively mediate transcranial optical inhibition of neurons deep in the brains of awake mice. The noninvasive optogenetic inhibition opened up by Jaws enables a variety of important neuroscience experiments and offers a powerful general-use chloride pump for basic and applied neuroscience.McGovern Institute for Brain Research at MIT (Razin Fellowship)United States. Defense Advanced Research Projects Agency. Living Foundries Program (HR0011-12-C-0068)Harvard-MIT Joint Research Grants Program in Basic NeuroscienceHuman Frontier Science Program (Strasbourg, France)Institution of Engineering and Technology (A. F. Harvey Prize)McGovern Institute for Brain Research at MIT. Neurotechnology (MINT) ProgramNew York Stem Cell Foundation (Robertson Investigator Award)National Institutes of Health (U.S.) (New Innovator Award 1DP2OD002002)National Institute of General Medical Sciences (U.S.) (EUREKA Award 1R01NS075421)National Institutes of Health (U.S.) (Grant 1R01DA029639)National Institutes of Health (U.S.) (Grant 1RC1MH088182)National Institutes of Health (U.S.) (Grant 1R01NS067199)National Science Foundation (U.S.) (Career Award CBET 1053233)National Science Foundation (U.S.) (Grant EFRI0835878)National Science Foundation (U.S.) (Grant DMS0848804)Society for Neuroscience (Research Award for Innovation in Neuroscience)Wallace H. Coulter FoundationNational Institutes of Health (U.S.) (RO1 MH091220-01)Whitehall FoundationEsther A. & Joseph Klingenstein Fund, Inc.JPB FoundationPIIF FundingNational Institute of Mental Health (U.S.) (R01-MH102441-01)National Institutes of Health (U.S.) (DP2-OD-017366-01)Massachusetts Institute of Technology. Simons Center for the Social Brai

Reciprocal relationships between trajectories of depressive symptoms and screen media use during adolescence

Adolescents are constantly connected with each other and the digital landscape through a myriad of screen media devices. Unprecedented access to the wider world and hence a variety of activities, particularly since the introduction of mobile technology, has given rise to questions regarding the impact of this changing media environment on the mental health of young people. Depressive symptoms are one of the most common disabling health issues in adolescence and although research has examined associations between screen use and symptoms of depression, longitudinal investigations are rare and fewer still consider trajectories of change in symptoms. Given the plethora of devices and normalisation of their use, understanding potential longitudinal associations with mental health is crucial. A sample of 1,749 (47% female) adolescents (10-17 years) participated in six waves of data collection over two years. Symptoms of depression, time spent on screens, and on separate screen activities (social networking, gaming, web browsing, TV/passive) were self-reported. Latent growth curve modelling revealed three trajectories of depressive symptoms (Low-Stable, High-Decreasing, and Low-Increasing) and there were important differences across these groups on screen use. Some small, positive associations were evident between depressive symptoms and later screen use, and between screen use and later depressive symptoms. However, a Random Intercept Cross Lagged Panel Model revealed no consistent support for a longitudinal association. The study highlights the importance of considering differential trajectories of depressive symptoms and specific forms of screen activity to understand these relationships

Combined Elastic and Raman Light Scattering of Human Eye Lenses

The distribution of the scattering coefficient (as defined in the appendix) at a wavelength of 647·1 nm along the visual axis of human eye lenses was investigated using a specially designed set-up for spatially resolved measurements of the intensity of the scattered light. For the same lenses, the distribution of the protein content was measured using confocal Raman microspectroscopy. Data collected by both methods were processed in terms of a recently developed theory of short-range, liquid-like order of crystallin proteins that accounts for eye lens transparency. Seven fresh intact human lenses of varying age have been investigated. In addition, elastic and Raman scattering measurements have been performed on fixed lenses.\ud \ud The main results and conclusions are: (1) Fixation significantly affects the light scattering properties of the eye lens. The average level of scattering increases and a change in the distribution of scattered light intensity along the visual axis occurs. Protein content and average distribution were not altered by fixation. (2) There are significant differences between the distribution of the scattering coefficient for lenses of different ages. For young lenses (18 and 20 years) regions with a low protein content (anterior and posterior cortex) show a higher level of elastic light scattering, while for older lenses (42-78 years old) there is no obvious correlation between the scattering level and protein content. (3) Changes in the level of light scattering along the visual axis of the lens cannot be explained by protein concentration effects. Therefore, these changes must be caused by changes in the supramolecular organization of lens proteins in the fibre cytoplasm. (4) The observed changes in light scattering may be related to the zones of discontinuity as observed in slitlamp and Scheimpflug photography of human lenses