311 research outputs found

    Results of the Excitation Test of the LHD Helical Coils Cooled by Subcooled Helium

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    Large helical device, the largest superconducting stellarator, has been operated for the research of fusion plasma since 1998. The toroidal field of almost 3 T is produced by a pair of pool-cooled helical coils, in the innermost layers of which a normal-zone had been induced several times at the bottom of the coil at higher currents than 11.0 kA. Since the field is not the highest there, the local cooling conditions are probably deteriorated by bubbles gathered by buoyancy. In order to improve the cryogenic stability by subcooling, an additional cooler with two-stage cold compressors was installed at the inlet of the coil in 2006. The inlet and outlet temperatures of the coils were successfully lowered to 3.2 K and 3.8 K, respectively, with a mass flow of 50 g/s. In spite of a half charging rate to reduce AC losses, a normal-zone was induced near the top of the coil at 11.45 kA. It propagated to one side and stopped near the inner equator, where the field is the highest. In comparison with the stability tests with a model coil, the local temperatures of the innermost layers near the top is considered to have been raised up to almost the saturated temperature of 4.4 K by charging. The excitation method was revised to waiting cool-down at 11.0 kA, and the excitations up to 11.5 kA have been attained

    A semiconductor strain gage tactile transducer

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    Abstract -This paper describes the development of a semiconductor strain gage tactile transducer. It was designed with the goal of measuring finger forces without aflecting the hand dmzerity. The transducer structure was manufactured with stainless steel and has small dimensions ( 4 mm dameter and 1 mm thickness). It is light and suitable to connect to the finger pads. It has a device that prevents its damage when overforces are applied The semiconductor strain gage was used due its small size and high sensitivity, although it has high temperature sensitivity. Theory, design and construction details are presented The signal conditioning circuit is very simple because the semiconductor strain gage sensitivity is high. It presents linear response from 0 to 100 N, 0.5 N resolution, fall time of 7.2 ms, good repeatability, and small hysteresis. The semiconductor strain gage transducer has characteristics that can make it very useful in Rehabilitafion Engineering, Robotics, and Medicine. Kev-words -Semiconductor strain gage, tactile transducer, force sensor, finger force, semiconductor sensor

    Robust Non-Interactive Multiparty Computation Against Constant-Size Collusion

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    Non-Interactive Multiparty Computations (Beimel et al., Crypto 2014) is a very powerful notion equivalent (under some corruption model) to garbled circuits, Private Simultaneous Messages protocols, and obfuscation. We present robust solutions to the problem of Non-Interactive Multiparty Computation in the computational and information-theoretic models. Our results include the first efficient and robust protocols to compute any function in NC1NC^1 for constant-size collusions, in the information-theoretic setting and in the computational setting, to compute any function in PP for constant-size collusions, assuming the existence of one-way functions. Our constructions start from a Private Simultaneous Messages construction (Feige, Killian Naor, STOC 1994 and Ishai, Kushilevitz, ISTCS 1997) and transform it into a Non-Interactive Multiparty Computation for constant-size collusions. We also present a new Non-Interactive Multiparty Computation protocol for symmetric functions with significantly better communication complexity compared to the only known one of Beimel et al

    Telomere shortening occurs in Asian Indian Type 2 diabetic patients

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    Aim: Telomere shortening has been reported in several diseases including atherosclerosis and Type 1 diabetes. Asian Indians have an increased predilection for Type 2 diabetes and premature coronary artery disease. The aim of this study was to determine whether telomeric shortening occurs in Asian Indian Type 2 diabetic patients. Methods: Using Southern‐blot analysis we determined mean terminal restriction fragment (TRF) length, a measure of average telomere size, in leucocyte DNA. Type 2 diabetic patients without any diabetes‐related complications (n = 40) and age‐ and sex‐matched control non‐diabetic subjects (n = 40) were selected from the Chennai Urban Rural Epidemiology Study (CURES). Plasma level of malondialdehyde (MDA), a marker of lipid peroxidation, was measured by TBARS (thiobarbituric acid reactive substances) using a fluorescence method. Results: Mean (± SE) TRF lengths of the Type 2 diabetic patients (6.01 ± 0.2 kb) were significantly shorter than those of the control subjects (9.11 ± 0.6 kb) (P = 0.0001). Among the biochemical parameters, only levels of TBARS showed a negative correlation with shortened telomeres in the diabetic subjects (r = −0.36; P = 0.02). However, telomere lengths were negatively correlated with insulin resistance (HOMA‐IR) (r = −0.4; P = 0.01) and age (r = −0.3; P = 0.058) and positively correlated with HDL levels (r = 0.4; P = 0.01) in the control subjects. Multiple linear regression (MLR) analysis revealed diabetes to be significantly (P < 0.0001) associated with shortening of TRF lengths. Conclusions: Telomere shortening occurs in Asian Indian Type 2 diabetic patients

    Uncovering Algebraic Structures in the MPC Landscape

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    A fundamental problem in the theory of secure multi-party computation (MPC) is to characterize functions with more than 2 parties which admit MPC protocols with information-theoretic security against passive corruption. This question has seen little progress since the work of Chor and Ishai (1996), which demonstrated difficulties in resolving it. In this work, we make significant progress towards resolving this question in the important case of aggregating functionalities, in which m parties P1, . . . , Pm hold inputs x1, . . . , xm and an aggregating party P0 must learn f(x1,...,xm). We uncover a rich class of algebraic structures that are closely related to secure computability, namely, “Commuting Permutations Systems” (CPS) and its variants. We present an extensive set of results relating these algebraic structures among themselves and to MPC, including new protocols, impossibility results and separations. Our results include a necessary algebraic condition and slightly stronger sufficient algebraic condition for a function to admit information-theoretically secure MPC protocols. We also introduce and study new models of minimally interactive MPC (called UNIMPC and UNIMPC*), which not only help in understanding our positive and negative results better, but also open up new avenues for studying the cryptographic complexity landscape of multi-party functionalities. Our positive results include novel protocols in these models, which may be of independent practical interest. Finally, we extend our results to a definition that requires UC security as well as semi-honest security (which we term strong security). In this model we are able to carry out the characterization of all computable functions, except for a gap in the case of aggregating functionalities

    Telomere shortening may be associated with human keloids

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    <p>Abstract</p> <p>Background</p> <p>Keloids are benign skin tumors that are the effect of a dysregulated wound-healing process in genetically predisposed patients. They are inherited with an autosomal dominant mode with incomplete clinical penetrance and variable expression. Keloids are characterized by formation of excess scar tissue beyond the boundaries of the wound. The exact etiology is still unknown and there is currently no appropriate treatment for keloid disease.</p> <p>Methods</p> <p>We analyzed sample tissues were obtained from 20 patients with keloid skin lesions and normal skin was obtained from 20 healthy donors. The telomeres were measured by Terminal Restriction Fragment (TRF) analysis and Real-Time PCR assay. Quantitative Real-Time RT-PCR analysis of hTERT gene expression was performed and intracellular ROS generation was measured.</p> <p>Results</p> <p>In this study, we determined whether telomeric shortening and the expression of human telomerase reverse transcriptase (hTERT) occurs in keloid patients. Using Terminal Restriction Fragment (TRF) analysis and Real-Time PCR assay, we detected a significant telomere shortening of 30% in keloid specimens compared to normal skin. Using quantitative Real-Time RT-PCR, telomerase activity was found absent in the keloid tissues. Moreover, an increase in ROS generation was detected in fibroblasts cell cultures from keloid specimens as more time elapsed compared to fibroblasts from normal skin.</p> <p>Conclusion</p> <p>Telomere shortening has been reported in several metabolic and cardiovascular diseases. We found that telomere shortening can also be associated with human keloids. Chronic oxidative stress plays a major role in the pathophysiology of several chronic inflammatory diseases. Here we found increased ROS generation in fibroblasts from keloid fibroblasts cell cultures when compared to normal skin fibroblasts. Hence we conclude that oxidative stress might be an important modulator of telomere loss in keloid because of the absence of active telomerase that counteracts telomere shortening.</p

    Medical Student Authorship Trends: A 10-Year Analysis of Four Major Orthopaedic Journals

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    Introduction: Orthopaedic surgery continues to be an increasingly competitive specialty for medical students to match into. Recent studies have identified the United States Medical Licensing Exam (USMLE) Step 1 and Step 2 CK scores, Alpha Omega Alpha Medical Honor Society induction, and mean number of research products as independent factors contributing to a successful match into orthopaedic surgery. Of these metrics, orthopaedic research is the only one that can be continuously improved over the course of medical school. Orthopaedic-specific research demonstrates scholarly activity, as well as interest in and commitment to the specialty. Given the rising competitiveness of matching into orthopaedic surgery residency and emphasis placed on research, the purpose of this study was to analyze medical student publication trends in four major orthopaedic journals over a 10-year period. Objectives: Identify the proportion of medical student publications in major orthopaedic journals and how these trends have changed over time. Methods: Websites of four major orthopaedic journals (American Journal of Sports Medicine, Clinical Orthopaedics and Related Research, Journal of Arthroplasty, and Journal of Bone and Joint Surgery) were accessed to identify articles published between 2011 and 2020. Articles were reviewed for the year, number of authors, degree(s) of each author, sex of each author, country, and state (if USA). Non-clinical studies were defined as basic science, biomechanical, technique, and educational studies. Country and state were determined based on affiliation of the senior author. Medical students were defined as authors who held a bachelor’s only degree. Editorials and letters to the editor were not included. Results: 15740 articles were included in this review (13510 clinical, 2230 non-clinical). The total number of authors was 82837. MDs constituted the majority of first authors in this study (64.5%). A total of 5242 medical students were listed as authors on 3769 publications (21.49% of overall publications). Out of the 3769 publications, 919 (24.38%) were first author publications. Linear regression demonstrated an increasing annual trend of first author (p=0.001) and any author (p<0.001) medical student publications over the study period, with increases of 291% and 206%, respectively, from 2011 to 2020. Linear regression demonstrated an increasing annual trend of female first author medical student publications (p=0.01), with an increase of 346% from 2011 to 2020. Overall number of publications did not significantly change over the study period. States with the most first author medical students were New York (111/919, 12.1%), Pennsylvania (96/919, 10.5%), and California (82/919, 8.9%). States with the most any author medical student studies were New York (514/3769, 13.6%), Pennsylvania (347/3769, 9.2%), and California (298/3769, 7.9%). Discussion: First author and any author medical student publications increased over the last 10 years, despite a constant number in overall orthopaedic publications. Additionally, the growing female medical student involvement in the literature highlights the importance and efficacy of advocacy, mentorship, and opportunities in improving diversity in orthopaedics and medicine. Lastly, states with the most first-author and any author medical student publications contain institutions with ample research funding, providing access and opportunities for students at the institution and others within geographic range. Target Audience: Medical students, orthopaedic chairs, and program director

    Single-Dose Intravenous Toxicity Study of IRDye 800CW in Sprague-Dawley Rats

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    Objective: Fluorophore-labeled contrast imaging agents are moving toward clinical use for a number of applications. The near-infrared dye IRDye 800CW is frequently used in its N-hydroxysuccinamide (NHS) ester form for labeling these agents. Following conjugation or breakdown of a labeled ligand, excess NHS ester is converted to the carboxylate form. To prepare for clinical use as a near-infrared fluorophore, a toxicity study was conducted on IRDye 800CW carboxylate. Methods: Male and female Sprague–Dawley rats were given a single intravenous or intradermal administration of IRDye 800CW carboxylate; Indocyanine Green was used as a comparative control. Animals were injected with varying doses of the test and control articles and observed for up to 14 days. Clinical chemistry, hematological, and pharmacokinetic analyses were performed on subgroups of animals. Organs were analyzed for content of the test article. Tissues were analyzed microscopically for pathological changes. Results: Based on hematologic, clinical chemistry, and histopathologic evaluation, single administration of IRDye 800CW carboxylate intravenously at dose levels of 1, 5, and 20 mg/kg or 20 mg/kg intradermally produced no pathological evidence of toxicity. Conclusion: A dose of 20 mg/kg was identified as the no observed adverse effect level following IV or ID routes of administration of IRDye 800CW
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