673 research outputs found
Seasonal deuterium excess in a Tien Shan ice core: Influence of moisture transport and recycling in Central Asia
Stable water isotope (ÎŽ18O, ÎŽD) data from a high elevation (5100 masl) ice core recovered from the Tien Shan Mountains, Kyrgyzstan, display a seasonal cycle in deuterium excess (d = ÎŽD â 8*ÎŽ18O) related to changes in the regional hydrologic cycle during 1994â2000. While there is a strong correlation (r2 = 0.98) between ÎŽ18O and ÎŽD in the ice core samples, the regression slope (6.9) and mean d value (23.0) are significantly different than the global meteoric water line values. The resulting time-series ice core d profile contains distinct winter maxima and summer minima, with a yearly d amplitude of âŒ15â20â°. Local-scale processes that may affect d values preserved in the ice core are not consistent with the observed seasonal variability. Data from Central Asian monitoring sites in the Global Network of Isotopes in Precipitation (GNIP) have similar seasonal d changes. We suggest that regional-scale hydrological conditions, including seasonal changes in moisture source, transport, and recycling in the Caspian/Aral Sea region, are responsible for the observed spatial and temporal d variability
Phylogenetic relationships of Indian caecilians (Amphibia: Gymnophiona) inferred from mitochondrial rRNA gene sequences
India has a diverse caecilian fauna, including representatives of three of the six currently recognized families, the Caeciliidae, Ichthyophiidae, the endemic Uraeotyphlidae, but previous molecular phylogenetic studies of caecilians have not included sequences for any Indian caecilians. Partial 12S and 16S mitochondrial gene sequences were obtained for a single representative of each of the caecilian families found in India and aligned against previously reported sequences for 13 caecilian species. The resulting alignment (16 taxa, 1200 sites, of which 288 cannot be aligned unambiguously) was analyzed using parsimony, maximum-likelihood, and distance methods. As judged by bootstrap proportions, decay indices, and leaf stabilities, well-supported relationships of the Indian caecilians are recovered from the alignment. The data (1) corroborate the hypothesis, based on morphology, that the Uraeotyphlidae and Ichthyophiidae are sister taxa, (2) recover a monophyletic Ichthyophiidae, including Indian and South East Asian representatives, and (3) place the Indian caeciliid Gegeneophis ramaswamii as the sister group of the caeciliid caecilians of the Seychelles. Rough estimates of divergence times suggest an origin of the Uraeotyphlidae and Ichthyophiidae while India was isolated from Laurasia and Africa and are most consistent with an Indian origin of these families and subsequent dispersal of ichthyophiids into South East Asia
Improving the identification of boneâspecific physical activity using wristâworn accelerometry: A crossâsectional study in 11â12âyearâold Australian children
This is the final version. Available from Wiley via the DOI in this record.âŻDATA AVAILABILITY STATEMENT:
The LSAC and CheckPoint data are available under license at https://
growingupinaustralia.gov.au/dataâandâdocumentation/accessingâlsac
âdata. To access raw accelerometry data, please contact the MCRI's
LifeCourse initiative https://lifecourse.melbournechildrens.comPhysical activity (PA) during childhood and adolescence is important for the accrual
of maximal peak bone mass. The precise dose that benefits bone remains unclear as
methods commonly used to analyze PA data are unsuitable for measuring boneâ
relevant PA. Using improved accelerometry methods, this study identified the
amount and intensity of PA most strongly associated with bone outcomes in 11â12â
yearâolds. Participants (n = 770; 382 boys) underwent tibial peripheral quantitative
computed tomography to assess trabecular and cortical density, endosteal and
periosteal circumference and polar stressâstrain index. Sevenâday wristâworn raw
acceleration data averaged over 1âs epochs was used to estimate time accumulated
above incremental PA intensities (50 milliâgravitational unit (mg) increments from
200 to 3000 mg). Associations between time spent above each 50 mg increment and
bone outcomes were assessed using multiple linear regression, adjusted for age, sex,
height, weight, maturity, socioeconomic position, muscle crossâsectional area and
PA below the intensity of interest. There was a gradual increase in mean R2 change
across all boneârelated outcomes as the intensity increased in 50 mg increments
from >200 to >700 mg. All outcomes became significant at >700 mg (R2
change = 0.6%â1.3% and p = 0.001â0.02). Any further increases in intensity led to a
reduction in mean R2 change and associations became nonâsignificant for all outcomes >1500 mg. Using more appropriate accelerometry methods (1âs epochs; no a
priori application of traditional cutâpoints) enabled us to identify that ~10 min/day
of PA >700 mg (equivalent to running ~10 km/h) was positively associated with
pQCTâderived measures of bone density, geometry and strength in 11â12âyearâ
olds.Australian National Health and Medical Research CouncilAustralian National Health and Medical Research CouncilRoyal Children's Hospital FoundationNIHR Leicester Biomedical Research CentreVictorian Deaf Education InstituteEconomic and Social Research CouncilUniversity of MelbourneNational Heart Foundation of AustraliaCollaboration for Leadership in Applied Health Research and Care East MidlandsFinancial Markets Foundation for ChildrenFinancial Markets Foundation for ChildrenNHMCR Principal Research FellowshipMurdoch Children's Research Institut
The zCOSMOS Survey. The dependence of clustering on luminosity and stellar mass at z=0.2-1
We study the dependence of galaxy clustering on luminosity and stellar mass
at redshifts z ~ [0.2-1] using the first zCOSMOS 10K sample.
We measure the redshift-space correlation functions xi(rp,pi) and its
projection wp(rp) for sub-samples covering different luminosity, mass and
redshift ranges. We quantify in detail the observational selection biases and
we check our covariance and error estimate techniques using ensembles of
semi-analytic mock catalogues. We finally compare our measurements to the
cosmological model predictions from the mock surveys.
At odds with other measurements, we find a weak dependence of galaxy
clustering on luminosity in all redshift bins explored. A mild dependence on
stellar mass is instead observed. At z~0.7, wp(rp) shows strong excess power on
large scales. We interpret this as produced by large-scale structure dominating
the survey volume and extending preferentially in direction perpendicular to
the line-of-sight. We do not see any significant evolution with redshift of the
amplitude of clustering for bright and/or massive galaxies.
The clustering measured in the zCOSMOS data at 0.5<z<1 for galaxies with
log(M/M_\odot)>=10 is only marginally consistent with predictions from the mock
surveys. On scales larger than ~2 h^-1 Mpc, the observed clustering amplitude
is compatible only with ~1% of the mocks. Thus, if the power spectrum of matter
is LCDM with standard normalization and the bias has no unnatural
scale-dependence, this result indicates that COSMOS has picked up a
particularly rare, ~2-3 sigma positive fluctuation in a volume of ~10^6 h^-1
Mpc^3. These findings underline the need for larger surveys of the z~1 Universe
to appropriately characterize the level of structure at this epoch.Comment: 18 pages, 21 figures, accepted for publication in Astronomy and
Astrophysic
DinĂąmica da dormĂȘncia de gemas de videira e quivizeiro em regiĂŁo de baixa ocorrĂȘncia de frio
Physical activity characterization:Does one site fit all?
Background: It is evident that a growing number of studies advocate a wrist-worn accelerometer for the assessment of patterns of physical activity a priori, yet the veracity of this site rather than any other body-mounted location for its accuracy in classifying activity is hitherto unexplored. Objective: The objective of this review was to identify the relative accuracy with which physical activities can be classified according to accelerometer site and analytical technique. Methods: A search of electronic databases was conducted using Web of Science, PubMed and Google Scholar. This review included studies written in the English language, published between database inception and December 2017, which characterized physical activities using a single accelerometer and reported the accuracy of the technique. Results: A total of 118 articles were initially retrieved. After duplicates were removed and the remaining articles screened, 32 full-text articles were reviewed, resulting in the inclusion of 19 articles that met the eligibility criteria. Conclusion: There is no 'one site fits all' approach to the selection of accelerometer site location or analytical technique. Research design and focus should always inform the most suitable location of attachment, and should be driven by the type of activity being characterized
Rapid and Efficient Clearance of Blood-borne Virus by Liver Sinusoidal Endothelium
The liver removes quickly the great bulk of virus circulating in blood, leaving only a small fraction to infect the host, in a manner characteristic of each virus. The scavenger cells of the liver sinusoids are implicated, but the mechanism is entirely unknown. Here we show, borrowing a mouse model of adenovirus clearance, that nearly all infused adenovirus is cleared by the liver sinusoidal endothelial cell (LSEC). Using refined immunofluorescence microscopy techniques for distinguishing macrophages and endothelial cells in fixed liver, and identifying virus by two distinct physicochemical methods, we localized adenovirus 1 minute after infusion mainly to the LSEC (âŒ90%), finding âŒ10% with Kupffer cells (KC) and none with hepatocytes. Electron microscopy confirmed our results. In contrast with much prior work claiming the main scavenger to be the KC, our results locate the clearance mechanism to the LSEC and identify this cell as a key site of antiviral activity
Superconductivity-induced Resonance Raman Scattering in Multi-layer High-Tc Superconductors
Resonant Raman scattering below Tc has been discovered in several Bi-, Hg-,
Tl-based high-Tc superconductors with three or four CuO2-layers. For
Bi2Si2Ca2Cu3O10+d, we found an unexpected crossover of the pair-breaking peak
in the A1g-spectrum from a broad bump at hw = 6kBTc for Eexc = 2.54eV to a
sharp peak at hw = 8kBTc for Eexc = 2.18eV, together with a strong enhancement
of the Ca-phonons. Under resonant conditions, the relative positions of the
pair breaking peaks in A1g, B1g, and B2g channels are 2Delta(A1g) = 2Delta(B1g)
> 2Delta(B2g). This relation implies that the A1g Raman channel is free from
the Coulomb screening effect, just as predicted theoretically for a d-wave
multi-layer superconductor but have never been observed experimentally thus
far. The observed resonance effect is the evidence that the electronic state in
the inner CuO2-planes is different from that of the outer CuO2-planes.Comment: 16 pages, 6 figures. submitted to Phys.Rev.
All-In-One: Advanced preparation of Human Parenchymal and Non-Parenchymal Liver Cells
BACKGROUND & AIMS: Liver cells are key players in innate immunity. Thus, studying primary isolated liver cells is necessary for determining their role in liver physiology and pathophysiology. In particular, the quantity and quality of isolated cells are crucial to their function. Our aim was to isolate a large quantity of high-quality human parenchymal and non-parenchymal cells from a single liver specimen. METHODS: Hepatocytes, Kupffer cells, liver sinusoidal endothelial cells, and stellate cells were isolated from liver tissues by collagenase perfusion in combination with low-speed centrifugation, density gradient centrifugation, and magnetic-activated cell sorting. The purity and functionality of cultured cell populations were controlled by determining their morphology, discriminative cell marker expression, and functional activity. RESULTS: Cell preparation yielded the following cell counts per gram of liver tissue: 2.0+/-0.4x107 hepatocytes, 1.8+/-0.5x106 Kupffer cells, 4.3+/-1.9x105 liver sinusoidal endothelial cells, and 3.2+/-0.5x105 stellate cells. Hepatocytes were identified by albumin (95.5+/-1.7%) and exhibited time-dependent activity of cytochrome P450 enzymes. Kupffer cells expressed CD68 (94.5+/-1.2%) and exhibited phagocytic activity, as determined with 1mum latex beads. Endothelial cells were CD146+ (97.8+/-1.1%) and exhibited efficient uptake of acetylated low-density lipoprotein. Hepatic stellate cells were identified by the expression of alpha-smooth muscle actin (97.1+/-1.5%). These cells further exhibited retinol (vitamin A)-mediated autofluorescence. CONCLUSIONS: Our isolation procedure for primary parenchymal and non-parenchymal liver cells resulted in cell populations of high purity and quality, with retained physiological functionality in vitro. Thus, this system may provide a valuable tool for determining liver function and disease
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