4,088 research outputs found

    Timescale Spectra in High Energy Astrophysics

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    A technique of timescale analysis performed directly in the time domain has been developed recently. We have applied the technique to studying rapid variabilities of hard X-rays from neutron star and black hole binaries, gamma-ray bursts and terrestrial gamma-ray flashes. The results indicate that the time domain method of spectral analysis is a powerful tool in revealing the underlying physics in high-energy processes in objects.Comment: 7 pages, 4 figures. Invited talk at the 6th Pacific Rim Conference on Steller Astrophysic

    Photosynthesis responses of endemic shrubs of Taklimakan Desert to adverse temperature, humidity and radiation

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    Under the native habitat conditions, the seasonal gas exchange characteristics of two natural endemic plant species, Calligonum taklimakanensis B.R. Pan & GM. Shen and Tamarix taklamakanensis M.T. Liu, which are located in the hinterland of the Taklimakan Desert, are measured and compared by Li-6400 photosynthesis system. The results indicate that temperature (degrees C), solar radiation (PAR), soil water content (SWC), and other environmental factors have obvious seasonal variations and the gas exchange characteristics of two plants have different changes in different growing seasons. For C. taklimakanensis, both in July and September, its daily changes of net photosynthetic rate tend to be obvious double peak curve, but in July its peak appeared earlier. Besides its maximum net photosynthetic rate (P-max), apparent quantum efficiency (Phi), range of effective photosynthetic radiation significantly less than that in September. Moreover, its water use efficiency (WUE) in July was also lower than that in September due to the higher transpiration rate (T-r). For T. taklamakanensis, although its daily change of net photosynthetic rate is a single peak curve in September, its peak time has not changed, and except that its WUE is higher in September like C. taklimakanensis, the maximum net photosynthetic rate (P-max), apparent quantum efficiency (Phi), light saturation point, and range of effective photosynthetic radiation has not changed or slightly declined. That is to say C. taklimakanensis select a season that habitat was better (like September) to progress relative effectively photosynthesis accumulation, in contrast, T. taklamakanensis still keep a relatively stable photosynthesis rate in different growth seasons. The difference of gas exchange characteristics of the two plants in different seasons shows that adaptation strategies of the two plants to extreme conditions in desert are different. Besides, both the higher photosynthetic accumulation rate and the higher water use efficiency in September also indicate that these two endemic desert shrubs possess the abilities and strategies to make the best of limited natural resources

    Accretion Disks Around Black Holes: Twenty Five Years Later

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    We study the progress of the theory of accretion disks around black holes in last twenty five years and explain why advective disks are the best bet in explaining varied stationary and non-stationary observations from black hole candidates. We show also that the recently proposed advection dominated flows are incorrect.Comment: 30 Latex pages including figures. Kluwer Style files included. Appearing in `Observational Evidence for Black Holes in the Universe', ed. Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland

    The first microbial colonizers of the human gut: composition, activities, and health implications of the infant gut microbiota

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    The human gut microbiota is engaged in multiple interactions affecting host health during the host's entire life span. Microbes colonize the neonatal gut immediately following birth. The establishment and interactive development of this early gut microbiota are believed to be (at least partially) driven and modulated by specific compounds present in human milk. It has been shown that certain genomes of infant gut commensals, in particular those of bifidobacterial species, are genetically adapted to utilize specific glycans of this human secretory fluid, thus representing a very intriguing example of host-microbe coevolution, where both partners are believed to benefit. In recent years, various metagenomic studies have tried to dissect the composition and functionality of the infant gut microbiome and to explore the distribution across the different ecological niches of the infant gut biogeography of the corresponding microbial consortia, including those corresponding to bacteria and viruses, in healthy and ill subjects. Such analyses have linked certain features of the microbiota/microbiome, such as reduced diversity or aberrant composition, to intestinal illnesses in infants or disease states that are manifested at later stages of life, including asthma, inflammatory bowel disease, and metabolic disorders. Thus, a growing number of studies have reported on how the early human gut microbiota composition/development may affect risk factors related to adult health conditions. This concept has fueled the development of strategies to shape the infant microbiota composition based on various functional food products. In this review, we describe the infant microbiota, the mechanisms that drive its establishment and composition, and how microbial consortia may be molded by natural or artificial interventions. Finally, we discuss the relevance of key microbial players of the infant gut microbiota, in particular bifidobacteria, with respect to their role in health and disease

    Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor beta 1

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    Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1

    Control of interneuron dendritic growth through NRG1/erbB4-mediated kalirin-7 disinhibition.

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    Neuregulin 1 (NRG1) is a secreted trophic factor that activates the postsynaptic erbB4 receptor tyrosine kinase. Both NRG1 and erbB4 have been repeatedly associated with schizophrenia, but their downstream targets are not well characterized. ErbB4 is highly abundant in interneurons, and NRG1-mediated erbB4 activation has been shown to modulate interneuron function, but the role for NRG1-erbB4 signaling in regulating interneuron dendritic growth is not well understood. Here we show that NRG1/erbB4 promote the growth of dendrites in mature interneurons through kalirin, a major dendritic Rac1-GEF. Recent studies have shown associations of the KALRN gene with schizophrenia. Our data point to an essential role of phosphorylation in kalirin-7's C terminus as the critical site for these effects. As reduced interneuron dendrite length occurs in schizophrenia, understanding how NRG1-erbB4 signaling modulates interneuron dendritic morphogenesis might shed light on disease-related alterations in cortical circuits

    Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

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    BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

    Evaluation of the association between the common E469K polymorphism in the ICAM-1 gene and diabetic nephropathy among type 1 diabetic patients in GoKinD population

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    <p>Abstract</p> <p>Background</p> <p>The ICAM-1 gene is a strong positional and biological candidate for susceptibility to the development of T1D and DN. We have recently demonstrated that SNP rs5498(E469K) confers susceptibility to the development of T1D and might be associated with DN in Swedish Caucasians. The present study aimed to further evaluate the association between the ICAM-1 genetic polymorphisms and DN.</p> <p>Methods</p> <p>Two common non-synonymous SNPs, including rs5498(E469K) and rs1799969(R241G), in the ICAM-1 gene were genotyped in 662 (312 female/350 male) T1D patients with DN and 620 (369/251) without DN. All patients were selected from the GoKinD study.</p> <p>Results</p> <p>Genotype distributions of both SNPs were in Hardy-Weinberg equilibrium but SNP rs5498(E469K) had high heterozygous index. In this SNP, the heterozygosity and positivity for the allele G were found to be significantly associated with DN in female T1D patients (P = 0.010, OR = 0.633, CI 95% 0.447–0.895 and P = 0.026, OR = 0.692, CI 95% 0.500–0.958). Furthermore, the female patients without DN carrying three genotypes A/A, A/G and G/G had different cystatin levels (0.79 ± 0.17, 0.81 ± 0.14 and 0.75 ± 0.12 mg/L, P = 0.021). No significant association of SNP rs1799969 (R241G) with DN was found.</p> <p>Conclusion</p> <p>The present study provides further evidence that SNP rs5498(E469K) in the ICAM-1 gene presents a high heterozygous index and the allele G of this polymorphism may confers the decreased risk susceptibility to the development of DN in female T1D patients among the GoKinD population.</p
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