1,528 research outputs found
Modeling L- and X-band backscattering of wheat and tests over fields of Pampas
A discrete scattering model and a detailed set of ground measurements are used to simulate the backscattering coefficients of wheat fields during the whole growth cycle. Simulations are carried out at L- and X-band, and at HH, VV, and HV polarizations. Wheat fields are located in Pampas (Argentina), and are characterized by low values of plant density. Simulations show that the backscattering coefficient is driven by variations of soil moisture at L-band, particularly for HH polarization, with low vegetation effects. Conversely, the attenuation of vegetation is dominant in producing variations of backscattering coefficients at X-band, particularly for VV polarization. Simulations are compared against experimental data collected over the same Pampas region, using airborne SARAT SAR at L-band and COSMO-SKYMED at X-band. Assuming a surface height standard deviation in a 0.4–0.7 cm range, the simulations generally agree with experimental data, with an RMSE lower than about 2 dB at L-band and X-band, except a limited number of cases. Discrepancies observed in specific conditions are discussed. Overall, the results indicate that a joint use of L- and X-band has a good potential to monitor both soil moisture and vegetation growth
Narrative-based computational modelling of the Gp130/JAK/STAT signalling pathway.
BACKGROUND: Appropriately formulated quantitative computational models can support researchers in understanding the dynamic behaviour of biological pathways and support hypothesis formulation and selection by "in silico" experimentation. An obstacle to widespread adoption of this approach is the requirement to formulate a biological pathway as machine executable computer code. We have recently proposed a novel, biologically intuitive, narrative-style modelling language for biologists to formulate the pathway which is then automatically translated into an executable format and is, thus, usable for analysis via existing simulation techniques. RESULTS: Here we use a high-level narrative language in designing a computational model of the gp130/JAK/STAT signalling pathway and show that the model reproduces the dynamic behaviour of the pathway derived by biological observation. We then "experiment" on the model by simulation and sensitivity analysis to define those parameters which dominate the dynamic behaviour of the pathway. The model predicts that nuclear compartmentalisation and phosphorylation status of STAT are key determinants of the pathway and that alternative mechanisms of signal attenuation exert their influence on different timescales. CONCLUSION: The described narrative model of the gp130/JAK/STAT pathway represents an interesting case study showing how, by using this approach, researchers can model biological systems without explicitly dealing with formal notations and mathematical expressions (typically used for biochemical modelling), nevertheless being able to obtain simulation and analysis results. We present the model and the sensitivity analysis results we have obtained, that allow us to identify the parameters which are most sensitive to perturbations. The results, which are shown to be in agreement with existing mathematical models of the gp130/JAK/STAT pathway, serve us as a form of validation of the model and of the approach itself
The role of electroencephalography in the prognostication of clinical outcomes in critically ill children: A review
Electroencephalography (EEG) is a neurologic monitoring modality that allows for the identification of seizures and the understanding of cerebral function. Not only can EEG data provide real-time information about a patient\u27s clinical status, but providers are increasingly using these results to understand short and long-term prognosis in critical illnesses. Adult studies have explored these associations for many years, and now the focus has turned to applying these concepts to the pediatric literature. The aim of this review is to characterize how EEG can be utilized clinically in pediatric intensive care settings and to highlight the current data available to understand EEG features in association with functional outcomes in children after critical illness. In the evaluation of seizures and seizure burden in children, there is abundant data to suggest that the presence of status epilepticus during illness is associated with poorer outcomes and a higher risk of mortality. There is also emerging evidence indicating that poorly organized EEG backgrounds, lack of normal sleep features and lack of electrographic reactivity to clinical exams portend worse outcomes in this population. Prognostication in pediatric critical illness must be informed by the comprehensive evaluation of a patient\u27s clinical status but the utilization of EEG may help contribute to this assessment in a meaningful way
On the novel free porphyrins corallistin B, C, D, and E : isolation from the demosponge Corallistes sp. of the Coral Sea and reactivity of their nickel (2) complexes toward formylating reagents
Reported here are the novel free corallistin B, C, D, and E, isolated as methyl esters 2a, 3a, 4a, and 5a, respectively, from the sponge #Corallistes sp.(#Lithistida) collected at the basis of the South New Caledonian coral reef. A protocol is also established for formulation of their NiII complexes, which show a different reactivity pattern toward DMF/POCI3 from metal complexes of deuteroporphyrin IX (isolate as 6a) also present in the sponge, the new corallistins, which may be thought to derive from protoporphyrin via heme, account for an amazing 60% of the etOH extract from the sponge. (Résumé d'auteur
Deep Radio Imaging of Globular Clusters and the Cluster Pulsar Population
We have obtained deep multifrequency radio observations of seven globular
clusters using the Very Large Array and the Australia Telescope Compact Array.
Five of these, NGC 6440, NGC 6539, NGC 6544, NGC 6624 and Terzan 5 had
previously been detected in a shallower survey for steep spectrum radio sources
in globular clusters (Fruchter and Goss 1990). The sixth, the rich globular
cluster, Liller 1, had heretofore been undetected in the radio, and the
seventh, 47 Tucanae, was not included in our original survey. High resolution 6
and 20 cm images of three of the clusters, NGC 6440, NGC 6539, NGC 6624 reveal
only point sources coincident with pulsars which have been discovered
subsequent to our first imaging survey. 21 and 18 cm images reveal several
point sources within a few core-radii of the center of 47 Tuc. Two of these are
identified pulsars, and a third, which is both variable and has a steep
spectrum, is also most likely a pulsar previously identified by a pulsed
survey. However, the 6, 20 and 90 cm images of NGC 6544, Liller 1 and Terzan 5
display strong steep-spectrum emission which cannot be associated with known
pulsars. The image of the rich cluster Terzan 5 displays numerous point sources
within , or 4 core radii of the cluster center. The density of these
objects rises rapidly toward the core, where an elongated region of emission is
found. The brightest individual sources, as well as the extended emission,
possess the steep spectra expected of pulsars. Furthermore, the flux
distribution of the sources agrees well with the standard pulsar luminosity
function. The total luminosity and number of objects observed suggest that
Terzan 5 contains more pulsars than any other Galactic globular cluster.Comment: 33 pages, 6 Postscript figures; Accepted for publication in the
Astrophysical Journal; abstract abridged. PDF version also available at
http://nemesis.stsci.edu/~fruchter/fg99/fg99.pd
PREDICTION OF DEFORMATION CAUSED BY LANDSLIDES BASED ON GRAPH CONVOLUTION NETWORKS ALGORITHM AND DINSAR TECHNIQUE
Abstract. Around the world, the occurrence of landslides has become one of the greatest threats to human life, property, infrastructure, and natural environments. Despite extensive research and discussions on the spatiotemporal dependence of landslide displacements, there is still a lack of understanding concerning the factors that appear to control displacement distribution in landslides because of their significant variations. This paper implements a Graph Convolutional Network (GCN) to predict displacement following the Moio della Civitella landslide in southern Italy and identify factors that may affect the distribution of movement following the landslide. An interferometric technique, known as permanent scatter interferometry (PSI), has been developed based on Synthetic Aperture Radar (SAR) satellite imagery to derive permanent scatter points that can be used to represent the deformation of landslides. This study utilized the GCN regression model applied to PSs points and data reflecting geological and geomorphological factors to extract the interdependency between paired data points, resulting in an adjacency matrix of the interval [0, 0,8). The proposed model outperforms conventional machine learning and deep learning algorithms such as linear regression (LR), K-nearest neighbors (KNN), Support vector regression (SVR), Decision tree, lasso, and artificial neural network (ANN). The absolute error between the actual and predicted deformation is used to evaluate the proposed model, which is less than 2 millimeters for most test set points
Change-of-direction deficit vs. deceleration deficit: a comparison of limb dominance and inter-limb asymmetry between forwards and backs in elite male rugby union players
The aims of the present study were to: 1) determine whether limb dominance and inter-limb asymmetry were the same across both change of direction (COD) and deceleration (DEC) deficits and, 2) determine the association between the COD and DEC-deficits and other physical performance tests in elite male rugby union players. Twenty five players performed a series of bilateral jumps, linear and COD speed tests at the end of the pre-season period. COD and DEC-deficits were calculated for both left and right sides, and inter-limb asymmetry thereafter. Kappa coefficients revealed moderate levels of agreement in limb dominance between COD and DEC-deficits (Kappa = 0.41 on left; 0.48 on right). For the direction of asymmetry, perfect levels of agreement (Kappa = 1) were evident between 505 time and COD-deficit, but only moderate levels of agreement (Kappa = 0.41) between other asymmetry measures. Pearson’s r correlations showed moderate to large relationships between jumps and linear (r = -0.42 to -0.68) and COD speed (r = -0.41 to -0.58), but not with the COD-deficit (r = 0.15 to -0.31), DEC-deficit (r = 0.01 to -0.32) or asymmetry (r = 0.16 to -0.29). When analyzing by playing position, backs were significantly faster than forwards over 15-m (ES = -0.86) and across all jump tests (ES = 0.86-0.94), with the exception of the squat jump. This study is the first to provide a direct comparison of the COD and DEC-deficits and highlights that limb dominance and asymmetry cannot be guaranteed between tasks
Differential diagnosis of endometriosis by ultrasound: A rising challenge
Ultrasound is an effective tool to detect and characterize endometriosis lesions. Variances in endometriosis lesions’ appearance and distorted anatomy secondary to adhesions and fibrosis present as major difficulties during the complete sonographic evaluation of pelvic endometriosis. Currently, differential diagnosis of endometriosis to distinguish it from other diseases represents the hardest challenge and affects subsequent treatment. Several gynecological and non-gynecological conditions can mimic deep-infiltrating endometriosis. For example, abdominopelvic endometriosis may present as atypical lesions by ultrasound. Here, we present an overview of benign and malignant diseases that may resemble endometriosis of the internal genitalia, bowels, bladder, ureter, peritoneum, retroperitoneum, as well as less common locations. An accurate diagnosis of endometriosis has significant clinical impact and is important for appropriate treatment
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