3,056 research outputs found
Sample-free operation in cell-culture simulations using single-use pH sensor with built- in self-calibration capability
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Single-Use pH sensor via a coplanar pH glass electrode design
The elimination of high temperature and high pressure sterilization processes by the advent of Single-Use-Systems (SUS) opens up a new era for the glass electrode based pH sensor. Without the requirement for pretreatment of a pH glass electrode under high temperature and pressure, the classic pH sensing technology delivers a more reliable, more rugged, and more accurate pH measurement. However, the innovative and unique SUS practice also posts new challenges, such as the long shelf-life requirement and the limitation of access to the sensor for calibration once on site,.
At Broadley-James Corporation, a new manufacturing technology has been developed to allow a coplanar pH glass electrode design. This innovative sensor design will allow the sensing surface to transfer from a storage/calibration position to a measurement position while maintaining a fully closed and sterile system status. A single use pH sensor based on this design exhibits features such as shelf life up to 2 years post gamma, on site calibration capability, post use validation capability, and 2 – 12 pH range coverage. This poster will present a coplanar tubular glass electrode design for upstream (bag) installation, as well as a coplanar flat glass electrode design for downstream (flow path) installation. Sensor accuracy verification, design details, and preliminary test results will also be presented
Measuring Slepton Masses and Mixings at the LHC
Flavor physics may help us understand theories beyond the standard model. In
the context of supersymmetry, if we can measure the masses and mixings of
sleptons and squarks, we may learn something about supersymmetry and
supersymmetry breaking. Here we consider a hybrid gauge-gravity supersymmetric
model in which the observed masses and mixings of the standard model leptons
are explained by a U(1) x U(1) flavor symmetry. In the supersymmetric sector,
the charged sleptons have reasonably large flavor mixings, and the lightest is
metastable. As a result, supersymmetric events are characterized not by missing
energy, but by heavy metastable charged particles. Many supersymmetric events
are therefore fully reconstructible, and we can reconstruct most of the charged
sleptons by working up the long supersymmetric decay chains. We obtain
promising results for both masses and mixings, and conclude that, given a
favorable model, precise measurements at the LHC may help shed light not only
on new physics, but also on the standard model flavor parameters.Comment: 24 pages; v2: fixed a typo in our computer program that led to some
miscalculated branching ratios, various clarifications and minor
improvements, conclusions unchanged, published versio
Analysis of energy expenditure in diet-induced obese rats
Development of obesity in animals is affected by energy intake, dietary composition, and metabolism. Useful models for studying this metabolic problem are Sprague-Dawley rats fed low-fat (LF) or high-fat (HF) diets beginning at 28 days of age. Through experimental design, their dietary intakes of energy, protein, vitamins, and minerals per kg body weight (BW) do not differ in order to eliminate confounding factors in data interpretation. The 24-h energy expenditure of rats is measured using indirect calorimetry. A regression model is constructed to accurately predict BW gain based on diet, initial BW gain, and the principal component scores of respiratory quotient and heat production. Time-course data on metabolism (including energy expenditure) are analyzed using a mixed effect model that fits both fixed and random effects. Cluster analysis is employed to classify rats as normal-weight or obese. HF-fed rats are heavier than LF-fed rats, but rates of their heat production per kg non-fat mass do not differ. We conclude that metabolic conversion of dietary lipids into body fat primarily contributes to obesity in HF-fed rats
Shape programming lines of concentrated Gaussian curvature
Liquid crystal elastomers (LCEs) can undergo large reversible contractions
along their nematic director upon heating or illumination. A spatially
patterned director within a flat LCE sheet thus encodes a pattern of
contraction on heating, which can morph the sheet into a curved shell, akin to
how a pattern of growth sculpts a developing organism. Here we consider,
theoretically, numerically and experimentally, patterns constructed from
regions of radial and circular director, which, in isolation, would form cones
and anticones. The resultant surfaces contain curved ridges with sharp V-shaped
cross-sections, associated with the boundaries between regions in the patterns.
Such ridges may be created in positively and negatively curved variants and,
since they bear Gauss curvature (quantified here via the Gauss-Bonnet theorem),
they cannot be flattened without energetically prohibitive stretch. Our
experiments and numerics highlight that, although such ridges cannot be
flattened isometrically, they can deform isometrically by trading the
(singular) curvature of the V angle against the (finite) curvature of the ridge
line. Furthermore, in finite thickness sheets, the sharp ridges are inevitably
non-isometrically blunted to relieve bend, resulting in a modest smearing out
of the encoded singular Gauss curvature. We close by discussing the use of such
features as actuating linear features, such as probes, tongues and limbs, and
highlighting the similarities between these patterns of shape change and those
found during the morphogenesis of several biological systems.F.F. and M.W. were supported by the EPSRC [grant number EP/P034616/1]. M.W. is grateful for support from the ELBE Visiting Faculty Program, Dresden. D.D. was supported by the EPSRC Centre for Doctoral Training in Computational Methods for Materials Science [grant no. EP/L015552/1]. J.S.B. was supported by a UKRI “future leaders fellowship” [grant number MR/S017186/1].
This material is partially based upon work supported by the National Science Foundation under Grant DMR 2041671
Determining the Contribution of Epidermal Cell Shape to Petal Wettability Using Isogenic Antirrhinum Lines
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Multi-Constellation GNSS Multipath Mitigation Using Consistency Checking
In a typical urban environment, a mixture of multipath-free,
multipath-contaminated and non-line-of-sight
(NLOS) propagated GNSS signals are received. The
errors caused by multipath-contaminated and NLOS
reception are the dominant source of reduced consumer-grade
positioning accuracy in the urban environment.
Many conventional receiver-based and antenna-based
techniques have been developed to mitigate either
multipath or NLOS reception with mixed success.
Nevertheless, the positioning accuracy can be maximised
based on the simple principle of selecting only those
signals least contaminated by multipath and NLOS
propagation to form the navigation solution. The advent
of multi-constellation GNSS provides the opportunity to
realise this technique that is potentially low-cost and
effective for consumer-grade devices. It may also be
implemented as an augmentation to other multipath
mitigation techniques.
The focus of this paper is signal selection by consistency
checking, whereby measurements from different satellites
are compared with each other to identify the NLOS and
most multipath-contaminated signals. The principle of
consistency checking is that multipath-contaminated and
NLOS measurements produce a less consistent navigation
solution than multipath-free measurements. RAIM-based
fault detection operates on the same principle.
Three consistency-checking schemes based on single-epoch
least-squares residuals are assessed: single sweep,
recursive checking and a hybrid version of the first two.
Two types of weighting schemes are also considered:
satellite elevation-based and signal C/N0-based weighting.
The paper also discussed the different observables that
may be used by a consistency-checking algorithm for
different applications and their effect on detection
sensitivity.
Test results for the proposed algorithms are presented
using data from both static positioning and stand-alone
dynamic positioning experiments. The static data was
collected using a pair of survey-grade multi-constellation
GNSS receivers using both GPS and GLONASS signals
at open sky and urban canyon locations, while the
dynamic data was collected using a consumer-grade
GPS/GLONASS receiver on a car in a mixed urban
environment. Significant improvements in position
domain are demonstrated using the weighted recursive
methods in the open environments. However in the urban
environments, there are insufficient directly received
signals for the conventional RAIM-based signal selection
to be effective all the time. Both positioning
improvements and risky outliers are demonstrated. More
advanced techniques have been identified for
investigation in future research
Phosgene in the Upper Troposphere and Lower Stratosphere: A Marker for Product Gas Injection Due to Chlorine‐Containing Very Short Lived Substances
Phosgene in the atmosphere is produced via the degradation of carbon tetrachloride, methyl chloroform, and a number of chlorine‐containing very short lived substances (VSLS). These VSLS are not regulated by the Montreal Protocol even though they contribute to stratospheric ozone depletion. While observations of VSLS can quantify direct stratospheric source gas injection, observations of phosgene in the upper troposphere/lower stratosphere can be used as a marker of product gas injection of chlorine‐containing VSLS. In this work we report upper troposphere/lower stratosphere measurements of phosgene made by the ACE‐FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument and compare with results from the TOMCAT/SLIMCAT three‐dimensional chemical transport model to constrain phosgene trends over the 2004–2016 period. The 13‐year ACE‐FTS time series provides the first observational evidence for an increase in chlorine product gas injection. In 2016, VSLS accounted for 27% of modeled stratospheric phosgene, up from 20% in the mid‐2000s
Filamin-A Regulates Neutrophil Uropod Retraction through RhoA during Chemotaxis
Filamin-A (FLNa) has been shown to be a key cross-linker of actin filaments in the leading edge of a motile melanoma cell line, however its role in neutrophils undergoing chemotaxis is unknown. Using a murine transgenic model in which FLNa is selectively deleted in granulocytes, we report that, while neutrophils lacking FLNa show normal polarization and pseudopod extension, they exhibit obvious defects in uropod retraction. This uropod retraction defect was found to be a direct result of reduced FLNa mediated activation of the small GTPase RhoA and myosin mediated actin contraction in the FLNa null cells. This results in a neutrophil recruitment defect in FLNa null mice. The compensatory increase in FLNb levels that was observed in the FLNa null neutrophils may be sufficient to compensate for the lack of FLNa at the leading edge allowing for normal polarization, however this compensation is unable to regulate RhoA activated tail retraction at the rear of the cell
Glycine receptor in rat hippocampal and spinal cord neurons as a molecular target for rapid actions of 17-β-estradiol
Glycine receptors (GlyRs) play important roles in regulating hippocampal neural network activity and spinal nociception. Here we show that, in cultured rat hippocampal (HIP) and spinal dorsal horn (SDH) neurons, 17-β-estradiol (E2) rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly). In outside-out membrane patches from HIP neurons devoid of nuclei, E2 similarly inhibited IGly, suggesting a non-genomic characteristic. Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERα and ERβ) antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs. In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing α2, α2β or α3β subunits, suggesting that either α2-containing or α3β-GlyRs mediate the E2 effect observed in neurons. Furthermore, E2 inhibited the GlyR-mediated tonic current in pyramidal neurons of HIP CA1 region, where abundant GlyR α2 subunit is expressed. We suggest that the neuronal GlyR is a novel molecular target of E2 which directly inhibits the function of GlyRs in the HIP and SDH regions. This finding may shed new light on premenstrual dysphoric disorder and the gender differences in pain sensation at the CNS level
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