Optically powered communication system with distributed amplifiers

An optically powered communication system with distributed amplification is demonstrated using either distributed parametric amplification (DPA) or distributed Raman amplification (DRA) within the dispersion-shifted fiber (DSF) and single-mode fiber (SMF). At the fiber output the residual pump after the distributed amplification is recycled to power the receiver component. Our scheme is also a potential candidate for the last mile transmission. Based on our scheme, 4 channels of 10 Gb/s WDM signals are used to obtain practical performance evaluation. In the presence of 10-dB gain for signals, the power penalties of-dB at the BER of are achieved for DPA in DSF, and as the comparing counterpart of DPA, counter-pumping DRA induce approximately the same level of power penalty in DSF and -dB in SMF. Co-pumping DRA are also tested in both kind of fibers. Finally, the energy-efficiency issue for different pumping schemes is analyzed. © 2006 IEEE.published_or_final_versio

Low infra red laser light irradiation on cultured neural cells: effects on mitochondria and cell viability after oxidative stress

<p>Abstract</p> <p>Background</p> <p>Considerable interest has been aroused in recent years by the well-known notion that biological systems are sensitive to visible light. With clinical applications of visible radiation in the far-red to near-infrared region of the spectrum in mind, we explored the effect of coherent red light irradiation with extremely low energy transfer on a neural cell line derived from rat pheochromocytoma. We focused on the effect of pulsed light laser irradiation vis-à-vis two distinct biological effects: neurite elongation under NGF stimulus on laminin-collagen substrate and cell viability during oxidative stress.</p> <p>Methods</p> <p>We used a 670 nm laser, with extremely low peak power output (3 mW/cm²) and at an extremely low dose (0.45 mJ/cm²). Neurite elongation was measured over three days in culture. The effect of coherent red light irradiation on cell reaction to oxidative stress was evaluated through live-recording of mitochondria membrane potential (MMP) using JC1 vital dye and laser-confocal microscopy, in the absence (photo bleaching) and in the presence (oxidative stress) of H₂O₂, and by means of the MTT cell viability assay.</p> <p>Results</p> <p>We found that laser irradiation stimulates NGF-induced neurite elongation on a laminin-collagen coated substrate and protects PC12 cells against oxidative stress.</p> <p>Conclusion</p> <p>These data suggest that red light radiation protects the viability of cell culture in case of oxidative stress, as indicated by MMP measurement and MTT assay. It also stimulates neurite outgrowth, and this effect could also have positive implications for axonal protection.</p

Boundary Conditions for the Diffusion Equation in Radiative Transfer

Using the method of images, we examine the three boundary conditions commonly applied to the surface of a semi-infinite turbid medium. We find that the image-charge configurations of the partial-current and extrapolated-boundary conditions have the same dipole and quadrupole moments and that the two corresponding solutions to the diffusion equation are approximately equal. In the application of diffusion theory to frequency-domain photon-migration (FDPM) data, these two approaches yield values for the scattering and absorption coefficients that are equal to within 3%. Moreover, the two boundary conditions can be combined to yield a remarkably simple, accurate, and computationally fast method for extracting values for optical parameters from FDPM data. FDPM data were taken both at the surface and deep inside tissue phantoms, and the difference in data between the two geometries is striking. If one analyzes the surface data without accounting for the boundary, values deduced for the optical coefficients are in error by 50% or more. As expected, when aluminum foil was placed on the surface of a tissue phantom, phase and modulation data were closer to the results for an infinite-medium geometry. Raising the reflectivity of a tissue surface can, in principle, eliminate the effect of the boundary. However, we find that phase and modulation data are highly sensitive to the reflectivity in the range of 80–100%, and a minimum value of 98% is needed to mimic an infinite-medium geometry reliably. We conclude that noninvasive measurements of optically thick tissue require a rigorous treatment of the tissue boundary, and we suggest a unified partial-current-extrapolated boundary approach

Asymmetrical crossing barriers in angiosperms

Patterns of reproductive isolation between species may provide insight into the mechanisms and evolution of barriers to interspeci¢c gene exchange. We used data from published interspeci¢c hybridization experiments from 14 genera of angiosperms in order to test for the presence of asymmetrical barriers to gene exchange. Reproductive isolation was examined at three life-history stages: the ability of interspeci¢c crosses to produce seeds, the viability of F 1 hybrids, and the fertility of F 1 hybrids. Statistically signi¢cant asymmetries in the strength of reproductive isolation between species were detected in all genera and at each of the three life-history stages. Asymmetries in seed production may be caused by a variety of mechanisms including di¡erences in stigma/style lengths, self compatibility and di¡erential fruit abortion. Asymmetries in post-zygotic isolation are probably caused by nuclear^cytoplasmic interactions. Asymmetrical reproductive isolation between plant taxa may have important implications for the dynamics of hybrid zones, the direction of genetic introgression and the probability of reinforcement

Remotely acting SMCHD1 gene regulatory elements: in silico prediction and identification of potential regulatory variants in patients with FSHD

Background: Facioscapulohumeral dystrophy (FSHD) is commonly associated with contraction of the D4Z4 macro-satellite repeat on chromosome 4q35 (FSHD1) or mutations in the SMCHD1 gene (FSHD2). Recent studies have shown that the clinical manifestation of FSHD1 can be modified by mutations in the SMCHD1 gene within a given family. The absence of either D4Z4 contraction or SMCHD1 mutations in a small cohort of patients suggests that the disease could also be due to disruption of gene regulation. In this study, we postulated that mutations responsible for exerting a modifier effect on FSHD might reside within remotely acting regulatory elements that have the potential to interact at a distance with their cognate gene promoter via chromatin looping. To explore this postulate, genome-wide Hi-C data were used to identify genomic fragments displaying the strongest interaction with the SMCHD1 gene. These fragments were then narrowed down to shorter regions using ENCODE and FANTOM data on transcription factor binding sites and epigenetic marks characteristic of promoters, enhancers and silencers

Barriers to women entering surgical careers: a global study into medical student perceptions

Background Barriers to female surgeons entering the field are well documented in Australia, the USA and the UK, but how generalizable these problems are to other regions remains unknown. Methods A cross-sectional survey was developed by the International Federation of Medical Students' Associations (IFMSA)'s Global Surgery Working Group assessing medical students' desire to pursue a surgical career at different stages of their medical degree. The questionnaire also included questions on students' perceptions of their education, resources and professional life. The survey was distributed via IFMSA mailing lists, conferences and social media. Univariate analysis was performed, and statistically significant exposures were added to a multivariate model. This model was then tested in male and female medical students, before a further subset analysis by country World Bank income strata. Results 639 medical students from 75 countries completed the survey. Mentorship [OR 3.42 (CI 2.29–5.12) p = 0.00], the acute element of the surgical specialties [OR 2.22 (CI 1.49–3.29) p = 0.00], academic competitiveness [OR 1.61 (CI 1.07–2.42) p = 0.02] and being from a high or upper-middle-income country (HIC and UMIC) [OR 1.56 (CI 1.021–2.369) p = 0.04] all increased likelihood to be considering a surgical career, whereas perceived access to postgraduate training [OR 0.63 (CI 0.417–0.943) p = 0.03], increased year of study [OR 0.68 (CI 0.57–0.81) p = 0.00] and perceived heavy workload [OR 0.47 (CI 0.31–0.73) p = 0.00] all decreased likelihood to consider a surgical career. Perceived quality of surgical teaching and quality of surgical services in country overall did not affect students' decision to pursue surgery. On subset analysis, perceived poor access to postgraduate training made women 60% less likely to consider a surgical career [OR 0.381 (CI 0.217–0.671) p = 0.00], whilst not showing an effect in the men [OR 1.13 (CI 0.61–2.12) p = 0.70. Concerns about high cost of training halve the likelihood of students from low and low-middle-income countries (LICs and LMICs) considering a surgical career [OR 0.45 (CI 0.25–0.82) p = 0.00] whilst not demonstrating a significant relationship in HIC or UMIC countries. Women from LICs and LMICs were 40% less likely to consider surgical careers than men, when controlling for other factors [OR 0.59 CI (0.342–1.01 p = 0.053]. Conclusion Perceived poor access to postgraduate training and heavy workload dissuade students worldwide from considering surgical careers. Postgraduate training in particular appears to be most significant for women and cost of training an additional factor in both women and men from LMICs and LICs. Mentorship remains an important and modifiable factor in influencing student's decision to pursue surgery. Quality of surgical education showed no effect on student decision-making

Expression Analysis of the Ligands for the Natural Killer Cell Receptors NKp30 and NKp44

BACKGROUND: The natural cytotoxicity receptors (NCR) are important to stimulate the activity of Natural Killer (NK) cells against transformed cells. Identification of NCR ligands and their level of expression on normal and neoplastic cells has important implications for the rational design of immunotherapy strategies for cancer. METHODOLOGY/PRINCIPAL FINDINGS: Here we analyze the expression of NKp30 ligand and NKp44 ligand on 30 transformed or non-transformed cell lines of different origin. We find intracellular and surface expression of these two ligands on almost all cell lines tested. Expression of NKp30 and NKp44 ligands was variable and did not correlate with the origin of the cell line. Expression of NKp30 and NKp44 ligand correlated with NKp30 and NKp44-mediated NK cell lysis of tumor cells, respectively. The surface expression of NKp30 ligand and NKp44 ligand was sensitive to trypsin treatment and was reduced in cells arrested in G(2)/M phase. CONCLUSION/SIGNIFICANCE: These data demonstrate the ubiquitous expression of the ligands for NKp30 and NKp44 and give an important insight into the regulation of these ligands

The support model for people with legally modified abilities according to United Nations

Este artículo se basa en una investigación social sobre el sistema de protección jurídica de las personas con algún tipo de discapacidad o en situación de dependencia que se encuentran sometidas a las figuras de tutela o curatela, en aplicación de lo previsto y establecido en el Código Civil Español, en sus artículos 199 y 200, así como en la Ley de Enjuiciamiento Civil. La investigación se plantea como un estudio comparado entre diferentes países de la Unión Europea para ver su adecuación a lo establecido en el artículo 12 de la Convención de Naciones Unidas sobre derechos de las Personas con Discapacidad (en adelante, CDPD) en los procedimientos de incapacitación. Los resultados se analizan sobre la base de modelos técnico-sociales de intervención, los análisis jurídicos y la experiencia adquirida por las Fundación Tutelares de Castilla y León. Se proponen y diseñan algunas alternativas y servicios que pueden mejorar la calidad de vida de las personas adultas incapacitadas judicialmente y el tipo de apoyos que se les puede prestar, de acuerdo a lo establecido en la Convención de Naciones Unidas.This article is based on social research into the system of legal protection for persons with disabilities or in a situation of dependence who are subject to the figures of guardianship or conservatorship pursuant to the provisions in the Spanish Civil Code, sections 199 and 200, as well as the Code of Civil Procedure. The research is presented as a comparative study between different countries of the European Union regarding the adaptation to the provisions of Article 12 of the UN Convention on Rights of Persons with Disabilities (hereinafter CRPD) Incapacitation procedures. The results are analyzed on the basis of technical-social intervention models, legal analysis and the experience of Guardianship Foundations of Castilla y León. Some alternatives and services are proposed and designed that can improve the quality of life of legally incapacitated persons and the type of support that can be provided to them in accordance with the provisions of the United Nations Convention

Genetic variation at CHRNA5-CHRNA3-CHRNB4 interacts with smoking status to influence body mass index

Cigarette smoking is associated with lower body mass index (BMI), and a commonly cited reason for unwillingness to quit smoking is a concern about weight gain. Common variation in the CHRNA5-CHRNA3-CHRNB4 gene region (chromosome 15q25) is robustly associated with smoking quantity in smokers, but its association with BMI is unknown. We hypothesized that genotype would accurately reflect smoking exposure and that, if smoking were causally related to weight, it would be associated with BMI in smokers, but not in never smokers