A time-dependent multi-layered mathematical model of filtration and solute exchange, the revised Starling principle and the Landis experiments

Cell oxygenation and nutrition is vitally important for human and animal life. Oxygen and nutrients are transported by the blood stream and cross microvessel walls to penetrate the cell's membrane. Pathological alterations in the transport of oxygen, and other nutrition elements, across microvessel walls may have serious consequences to cell life, possibly leading to localized cell necrosis. We present a transient model of plasma filtration and solute transport across microvessel walls by coupling flow and transport equations, the latter being non-linear in solute concentration. The microvessel wall is modeled through the superimposition of two or more membranes with different physical properties, representing key structural elements. With this model, the combined effect of the endothelial cells, the glycocalyx and other coating membranes specific of certain microvessels, can be analyzed. We investigate the role of transient external pressures in the study of trans-vascular filtration and solute exchange during the drop of blood capillary pressure due to the pathological decrease of blood volume called hypovolaemia, as well as hemorrhage. We discuss the advantage of using a multi-layered model, rather than a model considering the microvessel wall as a single and homogeneous membrane

modelling the thermo mechanical behavior of a redesigned tool holder to reduce the component geometrical deviations in cryogenic machining

Abstract In recent years cryogenic cooling based on Liquid Nitrogen has been adopted to improve the titanium alloys machinability mainly in rough operations. However, when applied to semi-finishing machining, the very low temperatures may significantly affect the component final geometry. To this aim, the paper presents the thermal-mechanical modeling of a new tool holder properly designed to reduce the component geometrical deviations from its nominal geometry during cryogenic machining. The model was calibrated and validated through turning trials on wrought Ti6Al4V samples, proving a reliable prediction of the tool holder behavior during cryogenic machining

Wireless Sensor Network Deployment for Monitoring Soil Moisture Dynamics at the Field Scale

AbstractWe describe the deployment of a Wireless Sensor Network (WSN), composed of 135 soil moisture and 27 temperature sensors, in an apple tree orchard of about 5000 m2, located in the municipality of Cles, a small town in the Alpine region, northeastern Italy. The orchard is divided into three parcels each one subjected to a different irrigation schedule. The objective of the present work is to monitor soil moisture dynamics in the top soil to a detail, in both space and time, suitable to analyze the interplay between soil moisture dynamics and plant physiology. The deployment consists of 27 locations (verticals) connected by a multi hop WSN, each one equipped with 5 soil moisture sensors deployed at the depths of 10, 20, 30, 50 and 80 cm, and a temperature sensor at the depth of 20 cm. The proposed monitoring system is based on totally independent sensor nodes, which allow both real time and historic data management and are connected through an input/output interface to a WSN platform. Meteorological data are monitored by a weather station located at a distance of approximately 100 m from the experimental site.Great care has been posed to calibration of the capacitance sensors, both in the laboratory, with soil samples, and on site, after deployment, in order to minimize the noise caused by small oscillations in the input voltage and uncertainty in the calibration curves. In this work we report the results of a preliminary analysis on the data collected during the growing season 2009. We observed that the WSN greatly facilitates the collection of detailed measurements of soil moisture, thereby increasing the amount of information useful for exploring hydrological processes, but they should be used with care since the accuracy of collected data depends critically on the capability of the system to maintain constant the input voltage and on the reliability of calibration curves. Finally, we studied the spatial and temporal distribution of soil moisture in all the irrigated parcels, and explored how different irrigation schedules influence orchard's production

Calcium as a key player in arrhythmogenic cardiomiopathy : adhesion disorder or intracellular alteration?

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease characterized by sudden death in young people and featured by fibro-adipose myocardium replacement, malignant arrhythmias, and heart failure. To date, no etiological therapies are available. Mutations in desmosomal genes cause abnormal mechanical coupling, trigger pro-apoptotic signaling pathways, and induce fibro-adipose replacement. Here, we discuss the hypothesis that the ACM causative mechanism involves a defect in the expression and/or activity of the cardiac Ca2+ handling machinery, focusing on the available data supporting this hypothesis. The Ca2+ toolkit is heavily remodeled in cardiomyocytes derived from a mouse model of ACM defective of the desmosomal protein plakophilin-2. Furthermore, ACM-related mutations were found in genes encoding for proteins involved in excitation\u2012contraction coupling, e.g., type 2 ryanodine receptor and phospholamban. As a consequence, the sarcoplasmic reticulum becomes more eager to release Ca2+, thereby inducing delayed afterdepolarizations and impairing cardiac contractility. These data are supported by preliminary observations from patient induced pluripotent stem-cell-derived cardiomyocytes. Assessing the involvement of Ca2+ signaling in the pathogenesis of ACM could be beneficial in the treatment of this life-threatening disease

\u3cem\u3eIn situ\u3c/em\u3e pressure study of Rb\u3csub\u3e4\u3c/sub\u3eC\u3csub\u3e60\u3c/sub\u3e insulator to metal transition by Compton scattering

Compton scattering has been shown to be a powerful tool for studying the ground state electronic density in real materials. Using synchrotron radiation, we have studied pressure effects on Rb4C60 by measuring the Compton profiles below and above the insulator to metal transition at 0.8 GPa. The experimental results are compared with the corresponding calculated results, obtained from new ab initio energy band structure calculations. These results allow us to quantitatively evaluate contributions to the Compton profiles resulting from the contraction of the unit cell as well as from the contraction of the C60 molecule itself. In this paper, we point out an unexpected contraction of the volume of the C60 molecule, leading to a major effect on the electronic density of the Rb4C60 compound