22,049 research outputs found
Landscape genetics of an endangered lemur (Propithecus tattersalli) within its entire fragmented range
Habitat fragmentation may strongly reduce individuals' dispersal among resource patches and hence influence population distribution and persistence. We studied the impact of landscape heterogeneity on the dispersal of the golden-crowned sifaka (Propithecus tattersalli), an endangered social lemur species living in a restricted and highly fragmented landscape. We combined spatial analysis and population genetics methods to describe population units and identify the environmental factors which best predict the rates and patterns of genetic differentiation within and between populations. We used non-invasive methods to genotype 230 individuals at 13 microsatellites in all the main forest fragments of its entire distribution area. Our analyses suggest that the Manankolana River and geographical distance are the primary structuring factors, while a national road crossing the region does not seem to impede gene flow. Altogether, our results are in agreement with a limited influence of forest habitat connectivity on gene flow patterns (except for North of the species' range), suggesting that dispersal is still possible today among most forest patches for this species. Within forest patches, we find that dispersal is mainly among neighbouring social groups, hence confirming previous behavioural observation
Rotating Black Hole Entropy from Two Different Viewpoints
Using the brick-wall method, we study the entropy of Kerr-Newman black hole
from two different viewpoints, a rest observer at infinity and zero angular
momentum observer near horizon. We investigate this with scalar field in the
canonical quantization approach. An observer at infinity can take one of the
two possible frequency ranges; one is with positive frequencies only and the
other is with the whole range including negative frequencies. On the other
hand, a zero angular momentum observer near horizon can take positive
frequencies only. For the observer at infinity the superradiant modes appear in
either choice of the frequency ranges and the two results coincide. For the
zero angular momentum observer superradiant modes do not appear due to absence
of ergoregion. The resulting entropies from the two viewpoints turn out to be
the same.Comment: LaTeX 18 pages, 2 figures, Minor modifications in section 3(ZAMO
The Mass Function of Newly Formed Stars (Review)
The topic of the stellar "original mass function" has a nearly 50 year
history,dating to the publication in 1955 of Salpeter's seminal paper. In this
review I discuss the many more recent results that have emerged on the initial
mass function (IMF), as it is now called, from studies over the last decade of
resolved populations in star forming regions and young open clusters.Comment: 9 pages, 1 figure; to appear in "The Dense Instellar Medium in
Galaxies -- 4'th Cologne-Bonn-Zermatt-Symposium" editted by S. Pfalzner, C.
Kramer, C. Straubmeier and A. Heithausen, Springer-Verlag (2004
The electric dipole response of Se above 4 MeV
The dipole response of Se in the energy range 4 to 9 MeV has been
analyzed using a polarized photon scattering
technique, performed at the High Intensity -Ray Source facility, to
complement previous work performed using unpolarized photons. The results of
this work offer both an enhanced sensitivity scan of the dipole response and an
unambiguous determination of the parities of the observed J=1 states. The
dipole response is found to be dominated by excitations, and can
reasonably be attributed to a pygmy dipole resonance. Evidence is presented to
suggest that a significant amount of directly unobserved excitation strength is
present in the region, due to unobserved branching transitions in the decays of
resonantly excited states. The dipole response of the region is underestimated
when considering only ground state decay branches. We investigate the electric
dipole response theoretically, performing calculations in a 3D cartesian-basis
time-dependent Skyrme-Hartree-Fock framework.Comment: 20 pages, 18 figures, to be submitted to PR
Diffusion and jump-length distribution in liquid and amorphous CuZr
Using molecular dynamics simulation, we calculate the distribution of atomic
jum ps in CuZr in the liquid and glassy states. In both states
the distribution of jump lengths can be described by a temperature independent
exponential of the length and an effective activation energy plus a
contribution of elastic displacements at short distances. Upon cooling the
contribution of shorter jumps dominates. No indication of an enhanced
probability to jump over a nearest neighbor distance was found. We find a
smooth transition from flow in the liquid to jumps in the g lass. The
correlation factor of the diffusion constant decreases with decreasing
temperature, causing a drop of diffusion below the Arrhenius value, despite an
apparent Arrhenius law for the jump probability
Proceeding of The International Seminar on Chemistry
Abstract Studies on the crude bark extract of Goniothalamus andersonii have enabled the isolation of stigmasterol, goniothalamin and two mixtures of sesquiterpenes.Their chemical structures were determined by using spectroscopic techniques like ¹H NMR, ¹³C NMR, GC-MS and Infrared spectroscopy.The crude n-hexane and etanol stem bark extracts of Goniothalamus andersonii were tested for their larvicidal activity against the larvae of Aedes aegypti. The n-hexane and methanol extracts of Goniothalamus andersonii were susceptible to the larvae with an LC50 value 42.3 µg/ml. This indicated very strong larvicidal activity. The ethanol extract showed larvicidal activity with an LC50 values of 58.1 µg/ml. This is also good larvicidal activity
Exclusive neuronal expression of SUCLA2 in the human brain
SUCLA2 encodes the ATP-forming subunit (A-SUCL-) of succinyl-CoA ligase, an enzyme of the citric acid cycle. Mutations in SUCLA2 lead to a mitochondrial disorder manifesting as encephalomyopathy with dystonia, deafness and lesions in the basal ganglia. Despite the distinct brain pathology associated with SUCLA2 mutations, the precise localization of SUCLA2 protein has never been investigated. Here we show that immunoreactivity of A-SUCL- in surgical human cortical tissue samples was present exclusively in neurons, identified by their morphology and visualized by double labeling with a fluorescent Nissl dye. A-SUCL- immunoreactivity co-localized >99% with that of the d subunit of the mitochondrial F0-F1 ATP synthase. Specificity of the anti-A-SUCL- antiserum was verified by the absence of labeling in fibroblasts from a patient with a complete deletion of SUCLA2. A-SUCL- immunoreactivity was absent in glial cells, identified by antibodies directed against the glial markers GFAP and S100. Furthermore, in situ hybridization histochemistry demonstrated that SUCLA2 mRNA was present in Nissl-labeled neurons but not glial cells labeled with S100. Immunoreactivity of the GTP-forming subunit (G-SUCL-) encoded by SUCLG2, or in situ hybridization histochemistry for SUCLG2 mRNA could not be demonstrated in either neurons or astrocytes. Western blotting of post mortem brain samples revealed minor G-SUCL- immunoreactivity that was however, not upregulated in samples obtained from diabetic versus non-diabetic patients, as has been described for murine brain. Our work establishes that SUCLA2 is expressed exclusively in neurons in the human cerebral cortex
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Surrounding Greenness and Biological Aging Based on DNA Methylation: A Twin and Family Study in Australia.
BACKGROUND: High surrounding greenness has many health benefits and might contribute to slower biological aging. However, very few studies have evaluated this from the perspective of epigenetics. OBJECTIVES: We aimed to evaluate the association between surrounding greenness and biological aging based on DNA methylation. METHODS: We derived Horvath's DNA methylation age (DNAmAge), Hannum's DNAmAge, PhenoAge, and GrimAge based on DNA methylation measured in peripheral blood samples from 479 Australian women in 130 families. Measures of DNAmAge acceleration (DNAmAgeAC) were derived from the residuals after regressing each DNAmAge metric on chronological age. Greenness was represented by satellite-derived Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) metrics within 300-, 500-, 1,000-, and 2,000-m buffers surrounding participant addresses. Greenness-DNAmAgeAC associations were estimated using a within-sibship design fitted by linear mixed effect models, adjusting for familial clustering and important covariates. RESULTS: Greenness metrics were associated with significantly lower DNAmAgeAC based on GrimAge acceleration, suggesting slower biological aging with higher greenness based on both NDVI and EVI in 300-2,000m buffer areas. For example, each interquartile range increase in NDVI within 1,000m was associated with a 0.59 (95% CI: 0.18, 1.01)-year decrease in GrimAge acceleration. Greenness was also inversely associated with three of the eight components of GrimAge, specifically, DNA methylation-based surrogates of serum cystatin-C, serum growth differentiation factor 15, and smoking pack years. Associations between greenness and biological aging measured by Horvath's and Hannum's DNAmAgeAC were less consistent, and depended on neighborhood socioeconomic status. No significant associations were estimated for PhenoAge acceleration. DISCUSSION: Higher surrounding greenness was associated with slower biological aging, as indicated by GrimAge age acceleration, in Australian women. Associations were also evident for three individual components of GrimAge, but were inconsistent for other measures of biological aging. Additional studies are needed to confirm our results. https://doi.org/10.1289/EHP8793
Exploring the work–life challenges and dilemmas faced by managers and professionals who live alone
This article aims to question the dominant understanding of work–life balance or conflict as primarily a ‘work–family’ issue. It does this by exploring the experiences of managers and professionals who live alone and do not have children – a group of employees traditionally overlooked in work–life policy and research but, significantly, a group on the rise within the working age population. Semi-structured interviews with 36 solo-living managers and professionals were carried out in the UK, spanning a range of occupations. In addition to previously identified work–life issues, four themes emerged that were pressing for and specific to solo-living managers and professionals. These are articulated here as challenges and dilemmas relating to: assumptions about work and non-work time; the legitimacy of their work–life balance; lack of support connected to financial and emotional well-being; and work-based vulnerabilities
Structure-based design and synthesis of antiparasitic pyrrolopyrimidines targeting pteridine reductase 1
The treatment of Human African Trypanosomiasis remains a major unmet health need in sub-Saharan Africa. Approaches involving new molecular targets are important and pteridine reductase 1 (PTR1), an enzyme that reduces dihydrobiopterin in Trypanosoma spp. has been identified as a candidate target and it has been shown previously that substituted pyrrolo[2,3-d]pyrimidines are inhibitors of PTR1 from T. brucei (J. Med. Chem. 2010, 53, 221-229). In this study, 61 new pyrrolo[2,3-d]pyrimidines have been prepared, designed with input from new crystal structures of 23 of these compounds complexed with PTR1, and evaluated in screens for enzyme inhibitory activity against PTR1 and in vitro antitrypanosomal activity. 8 compounds were sufficiently active in both screens to take forward to in vivo evaluation. Thus although evidence for trypanocidal activity in a stage I disease model in mice was obtained, the compounds were too toxic to mice for further development
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