389 research outputs found
Practical drift conditions for subgeometric rates of convergence
We present a new drift condition which implies rates of convergence to the
stationary distribution of the iterates of a \psi-irreducible aperiodic and
positive recurrent transition kernel. This condition, extending a condition
introduced by Jarner and Roberts [Ann. Appl. Probab. 12 (2002) 224-247] for
polynomial convergence rates, turns out to be very convenient to prove
subgeometric rates of convergence. Several applications are presented including
nonlinear autoregressive models, stochastic unit root models and
multidimensional random walk Hastings-Metropolis algorithms
BioNLP Shared Task 2011 - Bacteria Gene Interactions and Renaming
Document Type : Proceedings Paper Conference Date : JUN 23-24, 2011 Conference Location : Portland, ORInternational audienceWe present two related tasks of the BioNLP Shared Tasks 2011: Bacteria Gene Renaming (Rename) and Bacteria Gene Interactions (GI). We detail the objectives, the corpus specification, the evaluation metrics, and we summarize the participants' results. Both issued from PubMed scientific literature abstracts, the Rename task aims at extracting gene name synonyms, and the GI task aims at extracting genic interaction events, mainly about gene transcriptional regulations in bacteria
Exhumation, crustal deformation, and thermal structure of the Nepal Himalaya derived from the inversion of thermochronological and thermobarometric data and modeling of the topography
Two endâmember kinematic models of crustal shortening across the Himalaya are
currently debated: one assumes localized thrusting along a single major thrust fault, the
Main Himalayan Thrust (MHT) with nonuniform underplating due to duplexing, and the
other advocates for outâofâsequence (OOS) thrusting in addition to thrusting along the
MHT and underplating. We assess these two models based on the modeling of
thermochronological, thermometric, and thermobarometric data from the central Nepal
Himalaya. We complement a data set compiled from the literature with 114 ^(40)Ar/^(39)Ar,
10 apatite fission track, and 5 zircon (UâTh)/He thermochronological data. The data are
predicted using a thermokinematic model (PECUBE), and the model parameters are
constrained using an inverse approach based on the Neighborhood Algorithm. The model
parameters include geometric characteristics as well as overthrusting rates, radiogenic heat
production in the High Himalayan Crystalline (HHC) sequence, the age of initiation of
the duplex or of out-of-sequence thrusting. Both models can provide a satisfactory fit to the
inverted data. However, the model with out-of-sequence thrusting implies an unrealistic
convergence rate â„30 mm yr^(â1). The out-of-sequence thrust model can be adjusted to fit the
convergence rate and the thermochronological data if the Main Central Thrust zone is
assigned a constant geometry and a dip angle of about 30° and a slip rate of <1 mm yr^(â1). In
the duplex model, the 20 mm yr^(â1) convergence rate is partitioned between an overthrusting
rate of 5.8 ± 1.4 mm yr^(â1) and an underthrusting rate of 14.2 ± 1.8 mm yr^(â1). Modern rock
uplift rates are estimated to increase from about 0.9 ± 0.31 mm yr^(â1) in the Lesser Himalaya to
3.0 ± 0.9 mm yr^(â1) at the front of the high range, 86 ± 13 km from the Main Frontal Thrust.
The effective friction coefficient is estimated to be 0.07 or smaller, and the radiogenic
heat production of HHC units is estimated to be 2.2 ± 0.1 ”Wm^(â3). The midcrustal
duplex initiated at 9.8 ± 1.7 Ma, leading to an increase of uplift rate at front of the High
Himalaya from 0.9 ± 0.31 to 3.05 ± 0.9 mm yr^(â1). We also run 3-D models by coupling
PECUBE with a landscape evolution model (CASCADE). This modeling shows that the
effect of the evolving topography can explain a fraction of the scatter observed in the data but
not all of it, suggesting that lateral variations of the kinematics of crustal deformation and
exhumation are likely. It has been argued that the steep physiographic transition at the foot of
the Greater Himalayan Sequence indicates OOS thrusting, but our results demonstrate
that the best fit duplex model derived from the thermochronological and thermobarometric
data reproduces the present morphology of the Nepal Himalaya equally well
In Vitro Red Blood Cell Segregation in Sickle Cell Anemia
Red blood cells in sickle cell anemia (sRBC) are more heterogeneous in their physical properties than healthy red blood cells, spanning adhesiveness, rigidity, density, size, and shape. sRBC with increased adhesiveness to the vascular wall would trigger vaso-occlusive like complications, a hallmark of sickle cell anemia. We investigated whether segregation occurs among sRBC flowing in micron-sized channels and tested the impact of aggregation on segregation. Two populations of sRBC of different densities were separated, labeled, and mixed again. The mixed suspension was flowed within glass capillary tubes at different pressure-drops, hematocrit, and suspending media that promoted or not cell aggregation. Observations were made at a fixed channel position. The mean flow velocity was obtained by using the cells as tracking particles, and the cell depleted layer (CDL) by measuring the distance from the cell core border to the channel wall. The labeled sRBC were identified by stopping the flow and scanning the cells within the channel section. The tube hematocrit was estimated from the number of fluorescence cells identified in the field of view. In non-aggregating media, our results showed a heterogeneous distribution of sRBC according to their density: low-density sRBC population remained closer to the center of the channel, while the densest cells segregated towards the walls. There was no impact of the mean flow velocity and little impact of hematocrit. This segregation heterogeneity could influence the ability of sRBC to adhere to the vascular wall and slow down blood flow. However, promoting aggregation inhibited segregation while CDL thickness was enhanced by aggregation, highlighting a potential protective role against vaso-occlusion in patients with sickle cell anemia
SAMCO: Adaptation de la société aux risques en montagne dans un contexte de changement global
National audienceLe projet SAMCO (Society Adaptation for coping with Mountain risks in a global change COntext, 2013-2016) a pour but de développer un ensemble d'outils méthodologiques permettant d'améliorer la résilience des sociétés soumises aux impacts des risques en milieux montagneux. Ces outils visent à mesu-rer la capacité d'adaptation des écosystÚmes et des sociétés à partir de l'analyse de cas réels provenant de 3 sites pilotes représentatifs
SAMCO: Society adaptation for coping with mountain risks in a global change context
International audienceThe SAMCO project is intended to contribute to the development of a proactive resilience framework enhancing the overall resilience of societies on the impacts of mountain risks
STARs in the CNS
Abstract STAR (signal transduction and activation of RNA) proteins regulate splicing of target genes that have roles in neural connectivity, survival and myelination in the vertebrate nervous system. These regulated splicing targets include mRNAs such as the Neurexins (Nrxn), SMN2 (survival of motor neuron) and MAG (myelinassociated glycoprotein). Recent work has made it possible to identify and validate STAR protein splicing targets in vivo by using genetically modified mouse models. In this review, we will discuss the importance of STAR protein splicing targets in the CNS (central nervous system)
Picosecond polarized supercontinuum generation controlled by intermodal four-wave mixing for fluorescence lifetime imaging microscopy
International audienceWe present the generation of a picosecond polarized supercontinuum in highly birefringent multimodal microstructured fiber. The initial steps of the spectral broadening are dominated by intermodal four-wave mixing controlled by the specific fiber design. Using a low repetition rate ultra-stable solid state laser, a pulse train well-suited for versatile time-domain fluorescence lifetime imaging applications is obtaine
Höhere Analysis fĂŒr Ingenieure / von John Perry. Deutsche Bearbeitung von Robert Fricke und Fritz SĂŒchting
International audienc
Arctic seabirds and shrinking sea ice: egg analyses reveal the importance of ice-derived resources
In the Arctic, sea-ice plays a central role in the functioning of marine food webs and its rapid shrinking has large effects on the biota. It is thus crucial to assess the importance of sea-ice and ice-derived resources to Arctic marine species. Here, we used a multi-biomarker approach combining Highly Branched Isoprenoids (HBIs) with ÎŽ13C and ÎŽ15N to evaluate how much Arctic seabirds rely on sea-ice derived resources during the pre-laying period, and if changes in sea-ice extent and duration affect their investment in reproduction. Eg
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