182 research outputs found
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Ion cyclotron resonant heating 2 x 170/sup 0/ loop antenna for the Tandem Mirror Experiment-Upgrade
This paper reviews the mechanical design and improvements that have taken place on the loop type ion cyclotron resonance heating (ICRH) antennas that are located in the center cell region of the Tandem Mirror Experiment-Upgrade (TMX-U)
A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL
A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse repetition frequency exceeding 1 Hz. Capable of delivering requisite fast risetime, 17 kV flattop pulses into a 6 {Omega} load, the pulser employs a modular architecture characteristic of the inductive adder technology, pioneered at LLNL for use in acceleration applications, which keeps primary voltages low (and well within the capabilities of existing FET technology), reduces fabrication costs and is amenable to rapid assembly and quick field repairs
Micro-fabrication of Carbon Structures by Pattern Miniaturization in Resorcinol-Formaldehyde Gel
A simple and novel method to fabricate and miniaturize surface and
sub-surface micro-structures and micro-patterns in glassy carbon is proposed
and demonstrated. An aqueous resorcinol-formaldehyde (RF) sol is employed for
micro-molding of the master-pattern to be replicated, followed by controlled
drying and pyrolysis of the gel to reproduce an isotropically shrunk replica in
carbon. The miniaturized version of the master-pattern thus replicated in
carbon is about one order of magnitude smaller than original master by
repeating three times the above cycle of molding and drying. The
micro-fabrication method proposed will greatly enhance the toolbox for a facile
fabrication of a variety of Carbon-MEMS and C-microfluidic devices.Comment: 16 pages, 5 figure
Automatic multi-seed detection for MR breast image segmentation
In this paper an automatic multi-seed detection method for magnetic resonance (MR) breast image segmentation is presented. The proposed method consists of three steps: (1) pre-processing step to locate three regions of interest (axillary and sternal regions); (2) processing step to detect maximum concavity points for each region of interest; (3) breast image segmentation step. Traditional manual segmentation methods require radiological expertise and they usually are very tiring and time-consuming. The approach is fast because the multi-seed detection is based on geometric properties of the ROI. When the maximum concavity points of the breast regions have been detected, region growing and morphological transforms complete the segmentation of breast MR image. In order to create a Gold Standard for method effectiveness and comparison, a dataset composed of 18 patients is selected, accordingly to three expert radiologists of University of Palermo Policlinico Hospital (UPPH). Each patient has been manually segmented. The proposed method shows very encouraging results in terms of statistical metrics (Sensitivity: 95.22%; Specificity: 80.36%; Precision: 98.05%; Accuracy: 97.76%; Overlap: 77.01%) and execution time (4.23 s for each slice)
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Solid-State Modulators for RF And Fast Kickers
As the switching capabilities of solid-state devices increase, these devices are being incorporated into modulator designs for high voltage accelerator applications. Solid-state modulators based on inductive adder circuit topology have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. Additionally, these modulators are capable of being scaled to higher output voltage and power levels. An explanation of the basic circuit operation will be presented as well as test data of several different hardware systems
Tailoring 3D single-walled carbon nanotubes anchored to indium tin oxide for natural cellular uptake and intracellular sensing.
The ability to monitor intracellular events in real time is paramount to advancing fundamental biological and clinical science. We present the first demonstration of a direct interface of vertically aligned single-walled carbon nanotubes (VASWCNTs) with eukaryotic cells, RAW 264.7 mouse macrophage cell line. The cells were cultured on indium tin oxide with VASWCNTs. VASWCNTs entered the cells naturally without application of any external force and were shown to sense the intracellular presence of a redox active moiety, methylene blue. The technology developed provides an alluring platform to enable electrochemical study of an intracellular environment
Reduced response to IKr blockade and altered hERG1a/1b stoichiometryin human heart failure
Heart failure (HF) claims 250,000 lives per year in the US, and nearly half of these deaths are sudden and presumably
due to ventricular tachyarrhythmias. QT interval and action potential (AP) prolongation are hallmark proarrhythmic
changes in the failing myocardium, which potentially result from alterations in repolarizing potassium currents.
Thus,we aimed to examinewhether decreased expression of the rapid delayed rectifier potassiumcurrent, IKr, contributes
to repolarization abnormalities in human HF. Tomap functional IKr expression across the left ventricle (LV),
we optically imaged coronary-perfused LV free wall from donor and end-stage failing human hearts. The LV wedge
preparation was used to examine transmural AP durations at 80% repolarization (APD80), and treatment with the
IKr-blocking drug, E-4031, was utilized to interrogate functional expression. We assessed the percent change in
APD80 post-IKr blockade relative to baseline APD80 (ΔAPD80) and found that ΔAPD80s are reduced in failing versus
donor hearts in each transmural region, with 0.35-, 0.43-, and 0.41-fold reductions in endo-, mid-, and epicardium,
respectively (p = 0.008, 0.037, and 0.022). We then assessed hERG1 isoform gene and protein expression levels
using qPCR and Western blot. While we did not observe differences in hERG1a or hERG1b gene expression between
donor and failing hearts, we found a shift in the hERG1a:hERG1b isoform stoichiometry at the protein level. Computer
simulations were then conducted to assess IKr block under E-4031 influence in failing and nonfailing conditions.
Our results confirmed the experimental observations and E-4031-induced relative APD80 prolongationwas greater
in normal conditions than in failing conditions, provided that the cellularmodel of HF included a significant downregulation
of IKr. In humanHF, the response to IKr blockade is reduced, suggesting decreased functional IKr expression.
This attenuated functional response is associated with altered hERG1a:hERG1b protein stoichiometry in the
failing human LV, and failing cardiomyoctye simulations support the experimental findings. Thus, of IKr protein
and functional expression may be important determinants of repolarization remodeling in the failing human LV.We thank the Translational Cardiovascular Biobank & Repository (TCBR) at Washington University for provision of donor/patient records. The TCBR is supported by the NIH/CTSA (UL1 TR000448), Children's Discovery Institute, and Richard J. Wilkinson Trust. We also thank the laboratory of Dr. Sakiyama-Elbert for the use of the StepOnePlus equipment We appreciate the critical feedback on the manuscript by Dr. Jeanne Nerbonne. This work has been supported by the National Heart, Lung & Blood Institute (NHLBI, R01 HL114395). K. Holzem has been supported by the American Heart Association (12PRE12050315) and the NHLBI (F30 HL114310).Holzem, KM.; Gómez García, JF.; Glukhov, AV.; Madden, EJ.; Koppel, AC.; Ewald, GA.; Trénor Gomis, BA.... (2016). Reduced response to IKr blockade and altered hERG1a/1b stoichiometryin human heart failure. Journal of Molecular and Cellular Cardiology. 96:82-92. https://doi.org/10.1016/j.yjmcc.2015.06.008S82929
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