Two-photon excited photoluminescence in InGaN multi-quantum-wells structures

In this work, we report on the two-photon absorption induced luminescence of InGaN multiple quantum wells grown on sapphire. When the sample was excited by femtosecond near-infrared laser pulses at room temperature, an intense luminescence signal peaked at ∼415 nm from the sample was observed, which indicates strong nonlinear optical effect in InGaN quantum well structures. The interferometric autocorrelated luminescence traces were recorded to verify the second order nonlinearity of the luminescence. In addition, the strong second harmonic generation signal of the excitation laser was also observed. The mechanism of the two-photon excited photoluminescence in InGaN quantum wells was discussed.published_or_final_versionpublished_or_final_versio

Emission bands of nitrogen-implantation induced luminescent centers in ZnO crystals: experiment and theory

High quality ZnO crystals with the sharp band-edge excitonic emission and very weak green emission were implanted by nitrogen ions. An additional red emission band was observed in the as-implanted ZnO crystal and investigated as a function of temperature. By employing the underdamped multimode Brownian oscillator model for the general electron-phonon coupling system, both the original green and nitrogen-implantation induced red emission bands were theoretically reproduced at different temperatures. Excellent agreement between the theory and the experiment enables us determine the energetic positions of the pure electronic levels associated with the green and red emission bands, respectively. The determined energy level of the red emission band is in good agreement with the data obtained from the deep-level transient spectroscopy measurements. © 2012 American Institute of Physics.published_or_final_versio

Shallow optically active structural defect in wurtzite GaN epilayers grown on stepped 4H-SiC substrates

Shallow optically active structural defect in wurtzite GaN epilayers grown on stepped 4H-SiC substrates was investigated. The GaN epilayers grown with plasma-assisted molecular-beam epitaxy were optically characterized by photoluminescence and excitation spectra. Results showed that the localized states which were induced by the structural defect located about 100 meV above the maximum valence band of GaN.published_or_final_versio

Cross-domain neurobiology data integration and exploration

<p>Abstract</p> <p>Background</p> <p>Understanding the biomedical implications of data from high throughput experiments requires solutions for effective cross-scale and cross-domain data exploration. However, existing solutions do not provide sufficient support for linking molecular level data to neuroanatomical structures, which is critical for understanding high level neurobiological functions.</p> <p>Results</p> <p>Our work integrates molecular level data with high level biological functions and we present results using anatomical structure as a scaffold. Our solution also allows the sharing of intermediate data exploration results with other web applications, greatly increasing the power of cross-domain data exploration and mining.</p> <p>Conclusions</p> <p>The Flex-based PubAnatomy web application we developed enables highly interactive visual exploration of literature and experimental data for understanding the relationships between molecular level changes, pathways, brain circuits and pathophysiological processes. The prototype of PubAnatomy is freely accessible at:[<url>http://brainarray.mbni.med.umich.edu/Brainarray/prototype/PubAnatomy</url>]</p

Systemic Risk and Default Clustering for Large Financial Systems

As it is known in the finance risk and macroeconomics literature, risk-sharing in large portfolios may increase the probability of creation of default clusters and of systemic risk. We review recent developments on mathematical and computational tools for the quantification of such phenomena. Limiting analysis such as law of large numbers and central limit theorems allow to approximate the distribution in large systems and study quantities such as the loss distribution in large portfolios. Large deviations analysis allow us to study the tail of the loss distribution and to identify pathways to default clustering. Sensitivity analysis allows to understand the most likely ways in which different effects, such as contagion and systematic risks, combine to lead to large default rates. Such results could give useful insights into how to optimally safeguard against such events.Comment: in Large Deviations and Asymptotic Methods in Finance, (Editors: P. Friz, J. Gatheral, A. Gulisashvili, A. Jacqier, J. Teichmann) , Springer Proceedings in Mathematics and Statistics, Vol. 110 2015

Cardiomyocyte-restricted overexpression of extracellular superoxide dismutase increases nitric oxide bioavailability and reduces infarct size after ischemia/reperfusion

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Phytoestrogens

Collectively, plants contain several different families of natural products among which are compounds with weak estrogenic or antiestrogenic activity toward mammals. These compounds, termed phytoestrogens, include certain isoflavonoids, flavonoids, stilbenes, and lignans. The best-studied dietary phytoestrogens are the soy isoflavones and the flaxseed lignans. Their perceived health beneficial properties extend beyond hormone-dependent breast and prostate cancers and osteoporosis to include cognitive function, cardiovascular disease, immunity and inflammation, and reproduction and fertility. In the future, metabolic engineering of plants could generate novel and exquisitely controlled dietary sources with which to better assess the potential health beneficial effects of phytoestrogens

In vitro production of bovine embryos derived from individual donors in the Corral® dish

Background: Since the identity of the embryo is of outmost importance during commercial in vitro embryo production, bovine oocytes and embryos have to be cultured strictly per donor. Due to the rather low yield of oocytes collected after ovum pick-up (OPU) per individual cow, oocyte maturation and embryo culture take place in small groups, which is often associated with inferior embryo development. The objective of this study was to improve embryonic development in small donor groups by using the Corral (R) dish. This commercial dish is designed for human embryo production. It contains two central wells that are divided into quadrants by a semi-permeable wall. In human embryo culture, one embryo is placed per quadrant, allowing individual follow-up while embryos are exposed to a common medium. In our study, small groups of oocytes and subsequently embryos of different bovine donors were placed in the Corral (R) dish, each donor group in a separate quadrant. Results: In two experiments, the Corral (R) dish was evaluated during in vitro maturation (IVM) and/or in vitro culture (IVC) by grouping oocytes and embryos of individual bovine donors per quadrant. At day 7, a significantly higher blastocyst rate was noted in the Corral (R) dish used during IVM and IVC than when only used during IVM (12.9% +/- 2.10 versus 22.8% +/- 2.67) (P < 0.05). However, no significant differences in blastocyst yield were observed anymore between treatment groups at day 8 post insemination. Conclusions: In the present study, the Corral (R) dish was used for in vitro embryo production (IVP) in cattle; allowing to allocate oocytes and/or embryos per donor. As fresh embryo transfers on day 7 have higher pregnancy outcomes, the Corral (R) dish offers an added value for commercial OPU/IVP, since a higher blastocyst development at day 7 is obtained when the Corral (R) dish is used during IVM and IVC

Three dimensional structure directs T-cell epitope dominance associated with allergy

<p>Abstract</p> <p>Background</p> <p>CD4+ T-cell epitope immunodominance is not adequately explained by peptide selectivity in class II major histocompatibility proteins, but it has been correlated with adjacent segments of conformational flexibility in several antigens.</p> <p>Methods</p> <p>The published T-cell responses to two venom allergens and two aeroallergens were used to construct profiles of epitope dominance, which were correlated with the distribution of conformational flexibility, as measured by crystallographic B factors, solvent-accessible surface, COREX residue stability, and sequence entropy.</p> <p>Results</p> <p>Epitopes associated with allergy tended to be excluded from and lie adjacent to flexible segments of the allergen.</p> <p>Conclusion</p> <p>During the initiation of allergy, the N- and/or C-terminal ends of proteolytic processing intermediates were preferentially loaded into antigen presenting proteins for the priming of CD4+ T cells.</p