673 research outputs found

    Exploring field scale salinity using simulation modeling, example for Rudasht area, Esfahan Province, Iran

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    Salinity / Simulation models / Soil-water-plant relationships / Soil properties / Climate / Irrigated farming / Water quality / Iran / Esfahan Province / Rudasht Area

    Adsorption Study of Cyanate Ion on the Single-wall BC2N Nanotubes: a Computational Study

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    Cyanate adsorption on the external surface of H-capped (6,0) zigzag single-walled BC2N nanotube was studied by using density functional theory calculations. We present the nature of the cyanate interaction in different sites of the nanotube. This nanotube can absorb the cyanate ion in its pristine form without manipulating its structure through doping, chemical functionalization, making defect, etc, and the nanotube can be used as cyanate storage. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3518

    Electric Field Effect in CO Adsorption on the (6,0) Zigzag Single-walled Aluminum Nitride Nanotube: an Ideal Method for CO Adsorption

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    The behavior of the monoxide carbon (CO) adsorbed on the external surface of H-capped (6,0) zigzag single-walled aluminum nitride nanotube was studied under the parallel and transverse electric fields with strengths 0-140 × 10-4 a.u. by using density functional calculations. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 suite of programs. The binding energies obtained from these calculations at different applied parallel and transverse electric field strengths indicate that with increasing parallel electric field intensity, the binding energy values are increased, especially in the higher parallel field strength, whereas the BE values for the applied transverse electric field show a significant reverse trend. Results of this study indicate that with increasing parallel electric field intensity the pristine AlNNT can be used as CO storage and the parallel electric field effect is an ideal method for adsorption, storage, and fabrication of CO sensors. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3518

    A spatially-organized multicellular innate immune response in lymph nodes limits systemic pathogen spread

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    The lymphatic network that transports interstitial fluid and antigens to lymph nodes constitutes a conduit system that can be hijacked by invading pathogens to achieve systemic spread unless dissemination is blocked in the lymph node itself. Here, we show that a network of diverse lymphoid cells (natural killer cells, γδ T cells, natural killer T cells, and innate-like CD8+ T cells) are spatially prepositioned close to lymphatic sinus-lining sentinel macrophages where they can rapidly and efficiently receive inflammasome-generated IL-18 and additional cytokine signals from the pathogen-sensing phagocytes. This leads to rapid IFNγ secretion by the strategically positioned innate lymphocytes, fostering antimicrobial resistance in the macrophage population. Interference with this innate immune response loop allows systemic spread of lymph-borne bacteria. These findings extend our understanding of the functional significance of cellular positioning and local intercellular communication within lymph nodes while emphasizing the role of these organs as highly active locations of innate host defense

    Tuning of antigen sensitivity by T cell receptor-dependent negative feedback controls T cell effector function inflammed tissues

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    Activated T cells must mediate effector responses sufficient to clear pathogens while avoiding excessive tissue damage. Here we have combined dynamic intravital microscopy with ex vivo assessments of T cell cytokine responses to generate a detailed spatiotemporal picture of CD4+ T cell effector regulation in the skin. In response to antigen, effector T cells arrested transiently on antigen presenting cells, briefly producing cytokine and then resuming migration. Antigen recognition led to PD-1 upregulation of the programmed death-1 (PD-1) glycoprotein by T cells and blocking its canonical ligand, programmed death-ligand 1 (PD-L1), lengthened the duration of migration arrest and cytokine production, showing that PD-1 interaction with PD-L1 is a major negative feedback regulator of antigen responsiveness. We speculate that the immune system employs a mechanism involving T cell recruitment, transient activation, and rapid desensitization, allowing the T cell response to rapidly adjust to changes in antigen presentation and minimize collateral injury to the host

    A COMPARISON OF KINEMATICS BETWEEN ELITE HANDBALL PLAYERS WITH AND WITHOUT SHOULDER PAIN AFTER A FUNCTIONAL FATIGUE PROTOCOL

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    Shoulder pain are common in team handball, and players often continue playing despite pain. The aim of the study was to investigate whether a functional fatigue protocol(FFP) affects throwing kinematics, and whether this effect was different between players with and without shoulder pain. Thirty female players performed maximal standing throws before and after a FFP, while joint kinematics were measured with eight cameras (Vicon T40, Oxford, UK). The main findings were that fatigue affected throwing velocity positively. Some kinematic parameters in both groups were affected, but the effect on kinematics was not the same in both groups, especially timing of the maximal shoulder extension and minimal internal shoulder rotations seems to change differently between the groups after a FFP. No previous studies have investigated, whether functional fatigue influences throwing kinematic differently at team handball players who are playing with or without shoulder pain. KEYWORDS: Throwing kinematics, Team Handball, Overhead athletes, fatigue protocol, shoulder pain, risk factor

    Brazilian disk tests: Circular holes and size effects

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    Abstract Size effects related to circular notched samples imply that the strength of the structure decreases as the hole radius increases. In this framework, Brazilian disk tests are carried out on brittle samples containing a circular hole. By considering two different polymers, namely Polymethyl-methacrylate (PMMA) and General-purpose Polystyrene (GPPS), respectively, five different notch radii were machined and tested for each material, keeping low the hole to disk diameter ratio in order to reproduce an infinite geometry. Under this assumption, analytical relationship for the stress field and the stress intensity factor can be implemented without loss of accuracy. The coupled finite fracture mechanics (FFM) is then applied to catch the recorded failure stresses, allowing a complete description of the experimental size effects. On the contrary, the smallest radius leads to a locally negative geometry, opening the discussion on the stability of crack propagation in circularly notched plates under generic biaxial loadings

    Prediction of fracture loads in PMMA specimens using the Equivalent Material Concept and the Theory of Critical Distances combined criterion

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    This paper provides a methodology for the prediction of fracture loads in notched materials that combines the Equivalent Material Concept with the Theory of Critical Distances. The latter has a linear-elastic nature, and requires material (critical distance) calibration in those cases where the non-linear material behaviour is significant. The calibration may be performed by fracture testing on notched specimens, finite elements modelling or a combination of fracture and simulation. In any case, it may constitute a major issue when applying the Theory of Critical Distances on an industrial level. The proposed methodology sets out to define an equivalent linear-elastic material on which the Theory of Critical Distances may be applied through its basic formulation and without any previous calibration of the corresponding critical distance. It has been applied to PMMA Single Edge Notch Bending specimens, providing accurate predictions of fracture loads.The authors of this work would like to express their gratitude to the Spanish Ministry of Science and Innovation for the financial support of the project MAT2014-58443-P: “Análisis del comportamiento en fractura de componentes estructurales con defectos en condiciones debajo confinamiento tensional”, on the results of which this paper is based

    Muscle Synergy Analysis in Transtibial Amputee during Ramp Ascending Activity

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    In developed countries, the highest number of amputees are elderly with transtibial amputation. Walking on inclined surfaces is difficult for amputees due to loss of muscle volume and strength thereby transtibial amputees (TA) rely on the intact limb to maintain stability. The aim of this study was to use the concatenated non-negative matrix factorization (CNMF) technique to calculate muscle synergy components and compare the difference in muscle synergies and their associated activation profiles in the healthy and amputee groups during ramp ascending (RA) activity. Healthy subjects' dominant leg and amputee's intact leg (IL) were considered for recording surface electromyography (sEMG). The muscle synergies comparison showed a reasonable correlation between the healthy and amputee groups. This suggests the central nervous system (CNS) activates the same group of muscles synergistically. However, the activation coefficient profile (C) results indicated statistically significant difference (p <; 0.05) in some parts of the gait cycle (GC) in healthy and amputee groups. The difference exhibited in activation profiles of amputee's IL could be due to the instability of the prosthetic leg during the GC which resulted in alteration of the IL muscles activations. This information will be useful in rehabilitation and in the future development of prosthetic devices by using the IL muscles information to control the prostheses

    Classical and delayed orthostatic hypotension in patients with unexplained syncope and severe orthostatic intolerance

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    Background: Orthostatic hypotension (OH) is a major sign of cardiovascular autonomic failure leading to orthostatic intolerance and syncope. Orthostatic hypotension is traditionally divided into classical OH (cOH) and delayed OH (dOH), but the differences between the two variants are not well-studied. We performed a systematic clinical and neuroendocrine characterization of OH patients in a tertiary syncope unit. Methods: Among 2,167 consecutive patients (1,316 women, 60.7%; age, 52.6 ± 21.0 years) evaluated for unexplained syncope and severe orthostatic intolerance with standardized cardiovascular autonomic tests including head-up tilt (HUT), we identified those with a definitive diagnosis of cOH and dOH. We analyzed patients' history, clinical characteristics, hemodynamic variables, and plasma levels of epinephrine, norepinephrine, C-terminal-pro-arginine-vasopressin (CT-proAVP), C-terminal-endothelin-1, mid-regional-fragment of pro-atrial-natriuretic-peptide and pro-adrenomedullin in the supine position and at 3-min HUT. Results: We identified 248 cOH and 336 dOH patients (27% of the entire cohort); 111 cOH and 152 dOH had blood samples collected in the supine position and at 3-min HUT. Compared with dOH, cOH patients were older (68 vs. 60 years, p < 0.001), more often male (56.9 vs. 39.6%, p < 0.001), had higher systolic blood pressure (141 vs. 137 mmHg, p = 0.05), had lower estimated glomerular filtration rate (73 vs. 80 ml/min/1.73 m2, p = 0.003), more often pathologic Valsalva maneuver (86 vs. 49 patients, p < 0.001), pacemaker-treated arrhythmia (5 vs. 2%, p = 0.04), Parkinson's disease (5 vs. 1%, p = 0.008) and reported less palpitations before syncope (16 vs. 29%, p = 0.001). Supine and standing levels of CT-proAVP were higher in cOH (p = 0.022 and p < 0.001, respectively), whereas standing norepinephrine was higher in dOH (p = 0.001). After 3-min HUT, increases in epinephrine (p < 0.001) and CT-proAVP (p = 0.001) were greater in cOH, whereas norepinephrine increased more in dOH (p = 0.045). Conclusions: One-quarter of patients with unexplained syncope and severe orthostatic intolerance present orthostatic hypotension. Classical OH patients are older, more often have supine hypertension, pathologic Valsalva maneuver, Parkinson's disease, pacemaker-treated arrhythmia, and lower glomerular filtration rate. Classical OH is associated with increased vasopressin and epinephrine during HUT, but blunted increase in norepinephrine
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