bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of platelet function testing to the bedside
Authors: Cherala Ganesh , Serebruany Victor , Williams Craig 
Published: November 2009

SummaryThe ability to test platelet reactivity in clinical practice could help in making informed decisions on both initiation and titration of anti-platelet drug therapies. However, many barriers still remain to the effective implementation of such techniques. Many tests used in the research literature are not yet available for practical, clinical use. Platelet aggregometry, while informative and currently available for bedside use, needs additional research before routine clinical use can be recommended. This review will highlight and update contemporary issues of bedside platelet testing for the clinician and comment on future areas of clinical research.
The effects of exercise stress testing, diurnal variation and temporal decline on circulating progenitor cells
Authors: Karthikeyan Vellore , Jessani Shahirose , Goon Patrick , Watson Timothy , Shantsila Eduard , Lip Gregory 
Published: November 2009

SummaryEndothelial damage/dysfunction is involved in numerous cardiovascular disease processes. Given that the mature endothelial cells have limited capacity for self regeneration, circulating progenitor cells (CPCs) may modulate the balance between vascular damage and regeneration. The three aims of the present study were 1) to define the influence of exercise treadmill testing (ETT) on peripheral CPC levels; 2) to assess the diurnal variation of CPC counts; and 3) to investigate the rate of temporal decline in CPCs once ex vivo. The dynamics of CPC count changes following an ETT were assessed on consecutive 20 patients referred to our ‘rapid-access’ chest pain clinic (70% male, age 69.9 ± 7.8) with venous blood samples taken pre-exercise, immediately post-exercise and at 30 minutes post-exercise. Diurnal variation in CPCs was assessed in 13 stable in-hospital patients (46% male, age 69.1 ± 7.5 years) with blood samples were taken five times every 6 hours. To investigate the temporal decline, blood samples from 12 patients (58.3% male, age 69.9 ± 7.9 years) were reprocessed for CPC counts at 4 hours and at 24 hours after sample collection. Plasma levels of von Willebrand factor (vWf) and soluble E-selectin (sE-selectin) were assessed by ELISA. CPCs were enumerated with flow cytometry as CD34+, CD133+, CD45dim events. Exercise led to significant increases in vWF and sE-selectin levels, but no significant influence on CPC counts were observed. Baseline CPC numbers demonstrated a negative correlation with vWf (r=-0.551, p=0.012) and sE-selectin levels (r=-0.494, p=0.027). CPC counts showed a significant diurnal variation, being significantly higher at 12 a.m. compared to 12 p.m. (p=0.046) and 6 p.m. (p=0.023). A 4 hour delay in sample preparation did not affect CPCs counts, but there was a significant decline in CPC recovery when sample processing was delayed by 24 hours (p<0.05). Routine exercise stress testing does not significantly affect CPC counts. Peripheral CPC levels showed a significant diurnal variation. Delays in sample preparation for CPC counts should be avoided as they may influence the accuracy of the test by resulting in a significant decline in CPC recovery. Thus, various factors may affect accuracy of CPC enumeration that may limit their role as a reliable clinical marker and biomarker of endothelial damage.
Aspirin therapy: An attempt to explain the events of prothrombotic complications after treatment discontinuation
Authors: Aguejouf Omar , Desplat Vanessa , Eizayaga Francisco , Doutremepuich Christian 
Published: November 2009

SummaryAspirin remains the most widely used drug for prevention of vascular events. Recent observational epidemiological evidence has raised the concern that aspirin withdrawal for treatment non-compliance, surgery or side effects can carry an increased thrombotic risk. The delay to the thrombotic event was between 7 to 30 days in most reports and most frequently 7 to 10 days. The mechanism underlying this effect remains poorly understood. Using an in vivo model of laser-induced thrombosis, aspirin injected in one single dose of 100 mg/kg bw has also shown a prothrombotic activity in the rat 8 to 10 days after injection in the normal rat. The hypothesis was made that minimal concentrations of aspirin or ultra-low dose aspirin (ULDA) could induce this effect. ULDA showed prothrombotic properties in the same model of induced thrombosis that were very similar to those described after aspirin withdrawal, but the effect was observed only one hour after aspirin administration. This prothrombotic effect of ULDA is very similar to the effect observed after COX 2 selective inhibition with NS 398. The administration of both the selective COX 2 inhibitor and ULDA did not produce further changes. High-dose ASA counterbalances the lack of COX 2 with an antithrombotic effect. No effect of residual ASA was observed in COX 2 -/- mice, thus confirming the existence of a COX 2 inhibition pathway. COX 2 inhibition produced by residual ASA is the probable cause of ischaemic accidents and drug-eluting stents thrombosis a few days after ASA withdrawal.
TRPC channels in vascular cell function
Authors: Gudermann Thomas , Dietrich Alexander , Kalwa Hermann 
Published: November 2009

SummaryThe mammalian transient receptor potential (TRP) superfamily of non-selective cation channels can be divided into six major families. Among them, the “classical” or “canonical” TRPC family is most closely related to Drosophila TRP, the founding member of the superfamily. All seven channels of this family designated TRPC1–7 share the common property of receptor-operated activation through phospholipase C (PLC)-coupled receptors, but their regulation by store-dependent mechanisms involving the proteins STIM and ORAi is still discussed controversially. This review will focus on the proposed functions of TRPC proteins in cells of the vascular system (e.g. platelets, smooth muscle cells and endothelial cells) and will present data concerning their physiological functions analysed in isolated tissues with down-regulated channel activity and in gene-deficient mouse models.
Hantavirus regulation of endothelial cell functions
Authors: Gavrilovskaya Irina , Mackow Erich 
Published: November 2009

SummaryHantaviruses cause two vascular permeability-based diseases and primarily infect endothelial cells which form the primary fluid barrier of the vasculature. Since hantavirus infections are not lytic, the mechanisms by which hantaviruses cause haemorrhagic fever with renal syndrome (HFRS) or Hantavirus Pulmonary Syndrome (HPS) are indeterminate. HPS is associated with acute pulmonary oedema and HFRS with moderate haemorrhage and renal sequelae, perhaps reflecting the location of vast microvascular beds and endothelial cell reservoirs available for hantavirus infection. Endothelial cells regulate capillary integrity, and hantavirus infection provides a primary means for alteing vascular permeability that contributes to pathogenesis. The central importance of endothelial cells in regulating oedema, vascular repair, angiogenesis, immune cell recruitment, platelet deposition as well as gas exchange and solute delivery suggest that a multitude of inputs and cellular responses may be influenced by hantavirus infection and contribute to pathogenic changes in vascular permeability. Here we focus on understanding hantavirus interactions with endothelial cells which are linked to vascular permeability, and provide insight into the contribution of endothelial cell responses in hantavirus pathogenesis.
The Commonality of Neural Networks for Verbal and Visual Short-term Memory
Authors: Majerus Steve , D'Argembeau Arnaud , Martinez Perez Trecy , Belayachi Sanaâ , Van der Linden Martial , Collette Fabienne , Salmon Eric , Seurinck Ruth , Fias Wim , Maquet Pierre 
Published: November 2009

Abstract
Although many neuroimaging studies have considered verbal and visual short-term memory (STM) as relying on neurally segregated short-term buffer systems, the present study explored the existence of shared neural correlates supporting verbal and visual STM. We hypothesized that networks involved in attentional and executive processes, as well as networks involved in serial order processing, underlie STM for both verbal and visual list information, with neural specificity restricted to sensory areas involved in processing the specific items to be retained. Participants were presented sequences of nonwords or unfamiliar faces, and were instructed to maintain and recognize order or item information. For encoding and retrieval phases, null conjunction analysis revealed an identical fronto-parieto-cerebellar network comprising the left intraparietal sulcus, bilateral dorsolateral prefrontal cortex, and the bilateral cerebellum, irrespective of information type and modality. A network centered around the right intraparietal sulcus supported STM for order information, in both verbal and visual modalities. Modality-specific effects were observed in left superior temporal and mid-fusiform areas associated with phonological and orthographic processing during the verbal STM tasks, and in right hippocampal and fusiform face processing areas during the visual STM tasks, wherein these modality effects were most pronounced when storing item information. The present results suggest that STM emerges from the deployment of modality-independent attentional and serial ordering processes toward sensory networks underlying the processing and storage of modality-specific item information.
Daytime Precipitation Estimation Using Bispectral Cloud Classification System
Authors: Behrangi Ali , Hsu Koulin , Imam Bisher , Sorooshian Soroosh 
Published: November 2009

Abstract
Two previously developed Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) algorithms that incorporate cloud classification system (PERSIANN-CCS) and multispectral analysis (PERSIANN-MSA) are integrated and employed to analyze the role of cloud albedo from Geostationary Operational Environmental Satellite-12 (GOES-12) visible (0.65 μm) channel in supplementing infrared (10.7 mm) data. The integrated technique derives finescale (0.04° × 0.04° latitude–longitude every 30 min) rain rate for each grid box through four major steps: 1) segmenting clouds into a number of cloud patches using infrared or albedo images; 2) classification of cloud patches into a number of cloud types using radiative, geometrical, and textural features for each individual cloud patch; 3) classification of each cloud type into a number of subclasses and assigning rain rates to each subclass using a multidimensional histogram matching method; and 4) associating satellite gridbox information to the appropriate corresponding cloud type and subclass to estimate rain rate in grid scale. The technique was applied over a study region that includes the U.S. landmass east of 115°W. One reference infrared-only and three different bispectral (visible and infrared) rain estimation scenarios were compared to investigate the technique’s ability to address two major drawbacks of infrared-only methods: 1) underestimating warm rainfall and 2) the inability to screen out no-rain thin cirrus clouds. Radar estimates were used to evaluate the scenarios at a range of temporal (3 and 6 hourly) and spatial (0.04°, 0.08°, 0.12°, and 0.24° latitude–longitude) scales. Overall, the results using daytime data during June–August 2006 indicate that significant gain over infrared-only technique is obtained once albedo is used for cloud segmentation followed by bispectral cloud classification and rainfall estimation. At 3-h, 0.04° resolution, the observed improvement using bispectral information was about 66% for equitable threat score and 26% for the correlation coefficient. At coarser 0.24° resolution, the gains were 34% and 32% for the two performance measures, respectively.
Energy Flux and Wavelet Diagnostics of Secondary Mountain Waves
Authors: Woods Bryan K. , Smith Ronald B. 
Published: November 2009

Abstract
In recent years, aircraft data from mountain waves have been primarily analyzed using velocity and temperature power spectrum and momentum flux estimation. Herein it is argued that energy flux wavelets (i.e., pressure–velocity wavelet cross-spectra) provide a more powerful tool for locating and classifying different types of mountain waves. In the first part of the paper, pressure–velocity cross-spectra using various linear mountain-wave solutions are shown to be capable of disentangling collocated waves with different propagation directions and wavelength. A field of group velocity vectors can also be determined.
In the second part, the energy flux wavelet technique is applied to five cases of mountain waves entering the stratosphere from the Terrain-Induced Rotor Experiment (T-REX) in 2006. Perturbation pressure along the flight track is determined using aircraft static pressure corrected hydrostatically with GPS altitude. In four of the cases, collocated long up-propagating and short down-propagating waves are seen in the stratosphere. These waves have strong, but opposite, p′w′ cospectra. In one of these cases, a patch of turbulence is collocated with the up and down waves. In two other cases, trapped waves riding on the tropopause inversion layer (TIL) are seen. These trapped waves have p′w′ quadrature spectra that reverse sign across the tropopause. These newly discovered wave types may arise from secondary wave generation (i.e., a nonlinear transfer of energy from the long vertically propagating waves to shorter modes).
Can Climate Models Capture the Structure of Extratropical Cyclones?
Authors: Catto Jennifer L. , Shaffrey Len C. , Hodges Kevin I. 
Published: November 2009

Abstract
Composites of wind speeds, equivalent potential temperature, mean sea level pressure, vertical velocity, and relative humidity have been produced for the 100 most intense extratropical cyclones in the Northern Hemisphere winter for the 40-yr ECMWF Re-Analysis (ERA-40) and the high resolution global environment model (HiGEM). Features of conceptual models of cyclone structure—the warm conveyor belt, cold conveyor belt, and dry intrusion—have been identified in the composites from ERA-40 and compared to HiGEM. Such features can be identified in the composite fields despite the smoothing that occurs in the compositing process. The surface features and the three-dimensional structure of the cyclones in HiGEM compare very well with those from ERA-40. The warm conveyor belt is identified in the temperature and wind fields as a mass of warm air undergoing moist isentropic uplift and is very similar in ERA-40 and HiGEM. The rate of ascent is lower in HiGEM, associated with a shallower slope of the moist isentropes in the warm sector. There are also differences in the relative humidity fields in the warm conveyor belt. In ERA-40, the high values of relative humidity are strongly associated with the moist isentropic uplift, whereas in HiGEM these are not so strongly associated. The cold conveyor belt is identified as rearward flowing air that undercuts the warm conveyor belt and produces a low-level jet, and is very similar in HiGEM and ERA-40. The dry intrusion is identified in the 500-hPa vertical velocity and relative humidity. The structure of the dry intrusion compares well between HiGEM and ERA-40 but the descent is weaker in HiGEM because of weaker along-isentrope flow behind the composite cyclone. HiGEM’s ability to represent the key features of extratropical cyclone structure can give confidence in future predictions from this model.
Coupling the ISBA Land Surface Model and the TOPMODEL Hydrological Model for Mediterranean Flash-Flood Forecasting: Description, Calibration, and Validation
Authors: Bouilloud Ludovic , Chancibault Katia , Vincendon Béatrice , Ducrocq Véronique , Habets Florence , Saulnier Georges-Marie , Anquetin Sandrine , Martin Eric , Noilhan Joel 
Published: November 2009

Abstract
Innovative coupling between the soil–vegetation–atmosphere transfer (SVAT) model Interactions between Soil, Biosphere, and Atmosphere (ISBA) and the hydrological model TOPMODEL has been specifically designed for flash-flood forecasting in the Mediterranean area. The coupled model described in this study combines the advantages of the two types of model: the accurate representation of water and energy transfer between the soil and the atmosphere within the SVAT column and an explicit representation of the lateral transfer of water over the hydrological catchment unit. Another advantage of this coupling is that the number of parameters to be calibrated is reduced by two, as only two parameters instead of four parameters concern the TOPMODEL formulation used here. The parameters to be calibrated concern only the water transfer. The model was calibrated for the simulation of flash-flood events on the three main watersheds covering the French Cévennes–Vivarais region using a subset of past flash-flood events having occurred since 2000. The complementary subset of flash-flood events was then used to carry out an objective verification of the coupled model after calibration. The evaluation on these six independent past flash-flood events shows satisfactory results. The comparison of the observed and simulated hydrographs demonstrates that no flash-flood peaks are missed. Relevant information for flash-flood forecasting can always be inferred from the simulations, even for those with quite poor results, making the system useful for real-time and operational flash-flood forecasting.
Satellite-Scale Snow Water Equivalent Assimilation into a High-Resolution Land Surface Model
Authors: De Lannoy Gabriëlle J. M. , Reichle Rolf H. , Houser Paul R. , Arsenault Kristi R. , Verhoest Niko E. C. , Pauwels Valentijn R. N. 
Published: November 2009

Abstract
Four methods based on the ensemble Kalman filter (EnKF) are tested to assimilate coarse-scale (25 km) snow water equivalent (SWE) observations (typical of passive microwave satellite retrievals) into finescale (1 km) land model simulations. Synthetic coarse-scale observations are assimilated directly using an observation operator for mapping between the coarse and fine scales or, alternatively, after disaggregation (regridding) to the finescale model resolution prior to data assimilation. In either case, observations are assimilated either simultaneously or independently for each location. Results indicate that assimilating disaggregated finescale observations independently (method 1D-F1) is less efficient than assimilating a collection of neighboring disaggregated observations (method 3D-Fm). Direct assimilation of coarse-scale observations is superior to a priori disaggregation. Independent assimilation of individual coarse-scale observations (method 3D-C1) can bring the overall mean analyzed field close to the truth, but does not necessarily improve estimates of the finescale structure. There is a clear benefit to simultaneously assimilating multiple coarse-scale observations (method 3D-Cm) even as the entire domain is observed, indicating that underlying spatial error correlations can be exploited to improve SWE estimates. Method 3D-Cm avoids artificial transitions at the coarse observation pixel boundaries and can reduce the RMSE by 60% when compared to the open loop in this study.
Conditional Nonlinear Optimal Perturbations: Adjoint-Free Calculation Method and Preliminary Test
Authors: Wang Bin , Tan Xiaowei 
Published: November 2009

Abstract
An ensemble-based approach is proposed to obtain conditional nonlinear optimal perturbation (CNOP), which is a natural extension of linear singular vector to a nonlinear regime. The new approach avoids the use of adjoint technique during maximization and is thus more attractive. Comparisons among CNOPs of a simple theoretical model generated by the ensemble-based, adjoint-based, and simplex-search methods, respectively, not only show potential equivalence of the first two approaches in application according to their very similar spatial structures and time evolutions of the CNOPs, but also reveal the limited performance of the third measure, an existing adjoint-free algorithm, due to its inconsistent spatial distribution and weak net growth ratio of norm square of CNOP comparing with the results of the first two methods. Because of its attractive features, the new approach is likely to make it easier to apply CNOP in predictability or sensitivity studies using operational prediction models.
Intercomparison of Variational Data Assimilation and the Ensemble Kalman Filter for Global Deterministic NWP. Part I: Description and Single-Observation Experiments
Authors: Buehner Mark , Houtekamer P. L. , Charette Cecilien , Mitchell Herschel L. , He Bin 
Published: November 2009

Abstract
An intercomparison of the Environment Canada variational and ensemble Kalman filter (EnKF) data assimilation systems is presented in the context of global deterministic NWP. In an EnKF experiment having the same spatial resolution as the inner loop in the four-dimensional variational data assimilation system (4D-Var), the mean of each analysis ensemble is used to initialize the higher-resolution deterministic forecasts. Five different variational data assimilation experiments are also conducted. These include both 4D-Var and 3D-Var (with first guess at appropriate time) experiments using either (i) prescribed background-error covariances similar to those used operationally, which are static in time and include horizontally homogeneous and isotropic correlations; or (ii) flow-dependent covariances computed from the EnKF background ensembles with spatial covariance localization applied. The fifth variational data assimilation experiment is a new approach called the Ensemble-4D-Var (En-4D-Var). This approach uses 4D flow-dependent background-error covariances estimated from EnKF ensembles to produce a 4D analysis without the need for tangent-linear or adjoint versions of the forecast model. In this first part of a two-part paper, results from a series of idealized assimilation experiments are presented. In these experiments, only a single observation or vertical profile of observations is assimilated to explore the impact of various fundamental differences among the EnKF and the various variational data assimilation approaches considered. In particular, differences in the application of covariance localization in the EnKF and variational approaches are shown to have a significant impact on the assimilation of satellite radiance observations. The results also demonstrate that 4D-Var and the EnKF can both produce similar 4D background-error covariances within a 6-h assimilation window. In the second part, results from medium-range deterministic forecasts for the study period of February 2007 are presented for the EnKF and the five variational data assimilation approaches considered.