A Combine On-Line Acoustic Flowmeter and Fluorocarbon Coolant Mixture Analyzer for The ATLAS Silicon Tracker

An upgrade to the ATLAS silicon tracker cooling control system may require a change from C3F8 (octafluoro-propane) to a blend containing 10-30% of C2F6 (hexafluoro-ethane) to reduce the evaporation temperature and better protect the silicon from cumulative radiation damage with increasing LHC luminosity. Central to this upgrade is a new acoustic instrument for the real-time measurement of the C3F8/C2F6 mixture ratio and flow. The instrument and its Supervisory, Control and Data Acquisition (SCADA) software are described in this paper. The instrument has demonstrated a resolution of 3.10-3 for C3F8/C2F6 mixtures with ~20%C2F6, and flow resolution of 2% of full scale for mass flows up to 30gs-1. In mixtures of widely-differing molecular weight (mw), higher mixture precision is possible: a sensitivity of < 5.10-4 to leaks of C3F8 into the ATLAS pixel detector nitrogen envelope (mw difference 160) has been seen. The instrument has many potential applications, including the analysis of mixtures of hydrocarbons, vapours for semi-conductor manufacture and anaesthesia

Development of a Multilayer MODIS IST-Albedo Product of Greenland

A new multilayer IST-albedo Moderate Resolution Imaging Spectroradiometer (MODIS) product of Greenland was developed to meet the needs of the ice sheet modeling community. The multiple layers of the product enable the relationship between IST and albedo to be evaluated easily. Surface temperature is a fundamental input for dynamical ice sheet models because it is a component of the ice sheet radiation budget and mass balance. Albedo influences absorption of incoming solar radiation. The daily product will combine the existing standard MODIS Collection-6 ice-surface temperature, derived melt maps, snow albedo and water vapor products. The new product is available in a polar stereographic projection in NetCDF format. The product will ultimately extend from March 2000 through the end of 2017

Development of a custom on-line ultrasonic vapour analyzer/flowmeter for the ATLAS inner detector, with application to gaseous tracking and Cherenkov detectors

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom electronics, currently in use in the ATLAS inner detector, with numerous potential applications. The instrument has demonstrated ~0.3% mixture precision for C3F8/C2F6 mixtures and < 10-4 resolution for N2/C3F8 mixtures. Moderate and high flow versions of the instrument have demonstrated flow resolutions of +/- 2% F.S. for flows up to 250 l.min-1, and +/- 1.9% F.S. for linear flow velocities up to 15 ms-1; the latter flow approaching that expected in the vapour return of the thermosiphon fluorocarbon coolant recirculator being built for the ATLAS silicon tracker.Comment: Paper submitted to TWEPP2012; Topical Workshop on Electronics for Particle Physics, Oxford, UK, September 17-21, 2012. KEYWORDS: Sonar; Saturated fluorocarbons; Flowmetry; Sound velocity, Gas mixture analysis. 8 pages, 7 figure

Etiology of the membrane potential of rat white fat adipocytes

The plasma membrane potential (Vm) is key to many physiological processes, however its ionic aetiology in white fat adipocytes is poorly characterised. To address this question, we have employed the perforated patch current-clamp and cell-attached patch-clamp methods in isolated primary white fat adipocytes and their cellular model: 3T3-L1. The resting Vm of primary and 3T3-L1 adipocytes were -32.1±1.2mV (n=95) and -28.8±1.2mV (n=87), respectively. Vm was independent of cell size and fat content. Elevation of extracellular [K+] to 50mM by equimolar substitution of bath Na+ did not affect Vm, whereas substitution of bath Na+ with the membrane impermeant cation N-methyl-D-glucamine+ hyperpolarized Vm by 16mV, data indicative of a non-selective cation permeability. Substitution of 133mM extracellular Cl- with gluconate, depolarised Vm to +5.5, whereas Cl- substitution with I- caused a -9mV hyperpolarization. Isoprenaline (10µM) but not insulin (100nM) significantly depolarized Vm. Single-channel ion activity was voltage independent; currents were indicative for Cl- with an inward slope conductance of 16±1.3pS (n=11) and a reversal potential close to the Cl- equilibrium potential: -29±1.6mV. Reduction of extracellular Cl- elevated the intracellular Ca2+ of adipocytes. In conclusion, the Vm of white fat adipocyte is well described by the Goldman-Hodgkin-Katz equation with a predominant permeability to Cl-. Consequently, changes in serum Cl- homeostasis or the adipocyte’s permeability to this anion via drugs will affect its Vm, intracellular Ca2+ and ultimately its function and its role in metabolic control

Dense active matter model of motion patterns in confluent cell monolayers

Epithelial cell monolayers show remarkable displacement and velocity correlations over distances of ten or more cell sizes that are reminiscent of supercooled liquids and active nematics. We show that many observed features can be described within the framework of dense active matter, and argue that persistent uncoordinated cell motility coupled to the collective elastic modes of the cell sheet is sufficient to produce swirl-like correlations. We obtain this result using both continuum active linear elasticity and a normal modes formalism, and validate analytical predictions with numerical simulations of two agent-based cell models, soft elastic particles and the self-propelled Voronoi model together with in-vitro experiments of confluent corneal epithelial cell sheets. Simulations and normal mode analysis perfectly match when tissue-level reorganisation occurs on times longer than the persistence time of cell motility. Our analytical model quantitatively matches measured velocity correlation functions over more than a decade with a single fitting parameter.Comment: updated version accepted for publication in Nat. Com

A Multilayer Surface Temperature, Surface Albedo, and Water Vapor Product of Greenland from MODIS

A multilayer, daily ice surface temperature (IST)-albedo-water vapor product of Greenland, extending from March 2000 through December 2016, has been developed using standard MODerate-resolution Imaging Spectroradiometer (MODIS) data products from the Terra satellite. To meet the needs of the ice sheet modeling community, this new Earth Science Data Record (ESDR) is provided in a polar stereographic projection in NetCDF format, and includes the existing standard MODIS Collection 6.1 IST and derived melt maps, and Collection 6 snow albedo and water vapor maps, along with ancillary data, and is provided at a spatial resolution of ~0.78 km. This ESDR enables relationships between IST, surface melt, albedo, and water vapor to be evaluated easily. We show examples of the components of the ESDR and describe some uses of the ESDR such as for comparison with skin temperature, albedo, and water vapor output from Modern Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). Additionally, we show validation of the MODIS IST using in situ and aircraft data, and validation of MERRA-2 skin temperature maps using MODIS IST and in situ data. The ESDR has been assigned a DOI and will be available through the National Snow and Ice Data Center by the summer of 2018

Obesity: A Biobehavioral Point of View

Excerpt: If you ask an overweight person, “Why are you fat?’, you will, almost invariably, get the answer, “Because 1 eat too much.” You will get this answer in spite of the fact that of thirteen studies, six find no significant differences in the caloric intake of obese versus nonobese subjects, five report that the obese eat significantly less than the nonobese, and only two report that they eat significantly more