283 research outputs found

    State determined system of a circadian rhythm in scorpion

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    Near-Field Acoustical Characterization of Clustered Rocket Engines

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    This paper presents an approach for the prediction and characterization of the near-field acoustic levels from closely-spaced clustered rocket engines. The calculations are based on the method proposed by Eldred, wherein the flowfield from the clustered rockets is divided into two zones. Zone 1 contains the isolated nozzles which produce noise independently, and extends up to a distance where the individual flows completely mix to form an equivalent single nozzle flow. Zone 2 is occupied by the single mixed stream starting from the station where the jets merge. The acoustic fields from the two zones are computed separately on the basis of the NASA-SP method of Eldred developed for a single equivalent nozzle. A summation of the spectra for the two zones yields the total effective sound pressure level for the clustered engines. Under certain conditions of nozzle spacing and flow parameters, the combined sound pressure level spectrum for the clustered nozzles displays a double peak. Test cases are presented here to demonstrate the importance of hydrodynamic interactions responsible for the double peak in the sound spectrum in the case of clustered rocket nozzles, and the role of ground reflections in the case of non-interfering jets. A graphics interface (Rocket Acoustic Prediction Tool) has been developed to take into account the effects of clustered nozzles and ground reflections

    Improved magnetization and reduced leakage current in Sm and Sc co-substituted BiFeO3

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    BiFeO3 (BFO) and Bi0.85Sm0.15Fe0.90Sc0.10O3 (BSFSO) ceramics were synthesized by conventional solid state route. X-ray diffraction measurements revealed that an orthorhombic Pnma structure evolved with a phase fraction of 84% in the rhombohedral R3c structure of BFO upon the substitution of Sm and Sc. The changes in the intensity and the frequency of Raman modes also corroborated the structural transformation in the BSFSO compound. A decrease in grain size, reduction in porosity, and improved density were observed in the BSFSO compound. An enhanced remanent magnetization of 0.2 emu/g and coercive field of 6.2 kOe were observed, which were attributed to the structural change as well as the destruction of the spin structure with the substitution. Impedance and leakage current measurements revealed that the insulating character of BFO was improved with the substitution of Sm and Sc in BFO and was explained based on the bond enthalpy concept. The enhanced magnetic properties along with the improved insulating character of BSFSO compound will be suitable for device applications

    A study on the prevalence of obesity and metabolic syndrome among students of a medical college

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    Background: Obesity is emerging as a serious problem throughout the world. The overall life expectancy is significantly shortened and the quality of life decreased in those who are excessively overweight. Metabolic syndrome (MetS) is characterized by a constellation of individual risk factors of cardiovascular disease. Central obesity is a key feature of this syndrome, reflecting the fact that the syndrome’s prevalence is driven by strong relationship between waist circumference and increasing obesity. Awareness about MetS in medical students is the need of the hour.Methods: This cross-sectional study was conducted at Dr. PSIMS and RF, Chinnoutpalli, Andhra Pradesh, India involving 400 medical students. A pre-tested questionnaire, measurement of blood pressure, fasting glucose level, fasting lipid profile, anthropometric variables such as height, weight, waist circumference and hip circumference were taken. Metabolic syndrome was defined based on the International Diabetes Federation criteria. Data was processed using SPSS version 16. T-test, chi-square test, fisher’s exact test, anova and odd’s ratio were used for statistical analysis.Results: 59% of the study population was female. The prevalence of obesity was 4%, with majority being males (81.25%) The MetS prevalence as per the International diabetes federation (IDF) criteria was 6% (n=24). The prevalence of MetS in males was 12.19% (n=20) and in females 1.69%. (n=4). The risk of developing metabolic syndrome is high among those who smoke, consume alcohol, consume junk food and sleep for longer durations.Conclusions: The prevalence of metabolic syndrome is 6%. A significant association is established between life style habits like smoking, alcohol consumption, junk food consumption, sleep duration and MetS

    Bestimmung der Haftfestigkeit von aufgedampften, metallischen Dickschichten auf Polymersubstrat

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    Inaktivkomponenten in der Batterieherstellung, wie z. B. Stromsammler, Separator oder die Kontaktierungstaps rücken zunehmend in den Fokus der Forschung. Der Wechsel zu leichteren und günstigeren Materialien ist Gegenstand aktueller Forschungsarbeiten. In diesem Zusammenhang wird auch das Potential von Verbundstromkollektoren näher betrachtet. Dabei handelt es sich um Polymerfolien, die beidseitig mit 0,5 µm bis 1,5 µm dicken Aluminium- oder Kupferschichten metallisiert sind. Als Verbundmaterial müssen dabei im Vergleich zu konventionellen, metallischen Stromkollektoren zusätzliche Materialeigenschaften betrachtet werden. Dazu gehört vor allem die Haftfestigkeit der metallischen Beschichtungen auf den Folien. Es muss ausgeschlossen werden, dass durch wechselnde mechanische Beanspruchungen oder chemische Wechselwirkungen (z.B. mit dem Elektrolyten) in der Li-Ionen-Batteriezelle Delaminationen auftreten und sich die Metallisierung ablöst. Dazu ist eine quantitative Methode zur Bestimmung der Haftfestigkeit notwendig. Nur so kann eine Korrelation zwischen der Haftfestigkeit und dem Verhalten in der Zelle hergestellt werden. Bisherige Versuchsmethoden decken den Anwendungsfall von beidseitig metallisierten Polymersubstraten als Stromkollektorfolie jedoch nicht ab. Aus diesem Grund werden in dieser Studie Prüfverfahren zur Bestimmung der Haftfestigkeit, die bereits in Normen spezifiziert werden, zur Bewertung der Haftfestigkeiten der Verbundfolien adaptiert und bewertet. Die betrachteten Verfahren umfassen Schälversuche, Stirnabzugs- und Zugschertests, welche hinsichtlich ihrer Eignung zur Beurteilung der Haftfestigkeit von Verbundstromkollektoren evaluiert werden. Dabei werden Verbundfolien mit unterschiedlicher Schicht- sowie Substratdicke und variierendem Beschichtungsmaterial berücksichtigt, sodass die Sensitivität der Verfahren zur Bestimmung der Haftfestigkeit aufgelöst und darauf aufbauend deren Eignung zur Charakterisierung der Verbundfolien bewertet werden kann

    Interference Alignment and Cancellation

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    The throughput of existing MIMO LANs is limited by the number of antennas on the AP. This paper shows how to overcome this limit. It presents interference alignment and cancellation (IAC), a new approach for decoding concurrent sender-receiver pairs in MIMO networks. IAC synthesizes two signal processing techniques, interference alignment and interference cancellation, showing that the combination applies to scenarios where neither interference alignment nor cancellation applies alone. We show analytically that IAC almost doubles the throughput of MIMO LANs. We also implement IAC in GNU-Radio, and experimentally demonstrate that for 2x2 MIMO LANs, IAC increases the average throughput by 1.5x on the downlink and 2x on the uplink.United States. Defense Advanced Research Projects Agency. Information Theory for Mobile Ad-Hoc Networks Progra

    A De Novo Mutation in the Sodium-Activated Potassium Channel KCNT2 Alters Ion Selectivity and Causes Epileptic Encephalopathy.

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    Early infantile epileptic encephalopathies (EOEE) are a debilitating spectrum of disorders associated with cognitive impairments. We present a clinical report of a KCNT2 mutation in an EOEE patient. The de novo heterozygous variant Phe240Leu SLICK was identified by exome sequencing and confirmed by Sanger sequencing. Phe240Leu rSlick and hSLICK channels were electrophysiologically, heterologously characterized to reveal three significant alterations to channel function. First, [Cl-]i sensitivity was reversed in Phe240Leu channels. Second, predominantly K+-selective WT channels were made to favor Na+ over K+ by Phe240Leu. Third, and consequent to altered ion selectivity, Phe240Leu channels had larger inward conductance. Further, rSlick channels induced membrane hyperexcitability when expressed in primary neurons, resembling the cellular seizure phenotype. Taken together, our results confirm that Phe240Leu is a "change-of-function" KCNT2 mutation, demonstrating unusual altered selectivity in KNa channels. These findings establish pathogenicity of the Phe240Leu KCNT2 mutation in the reported EOEE patient

    Formative evaluation and adaptation of a hypertension Extension for Community Health Outcomes program for healthcare workers within the Federal Capital Territory, Nigeria

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    BACKGROUND: The Extension for Community Health Outcomes (ECHO) model has been used extensively to link care providers in rural communities with experts with the aim of improving local patient care. OBJECTIVE: The aim of this qualitative research study was to assess the feasibility, acceptability, perceived needs, and contextual factors to guide implementation of a hypertension focused ECHO program for Community Health Extension Workers (CHEWs) in the Federal Capital Territory, Nigeria. METHODS: From September 2020 to December 2020, key informant interviews were performed with seven global organizations (hubs) providing ECHO training focused on cardiovascular disease or nephrology to identify contextual factors and implementation strategies used by each hub. In February 2022, seven focus group discussions were performed with 42 frontline healthcare workers in the Federal Capital Territory to inform local adaptation of a hypertension ECHO program. Directed content analysis identified major themes which were mapped to the Consolidated Framework for Implementation Research. Qualitative analyses were performed using Dedoose, and results were synthesized using the Implementation Research Logic Model. RESULTS: We found both barriers and facilitators across the Consolidated Framework for Implementation Research domains that mapped to a number of constructs in each one. The results of these analyses confirmed that the core components of the ECHO model are a feasible and appropriate intervention for hypertension education of healthcare workers. However, implementing the ECHO program within the Federal Capital Territory may require strategies such as utilizing communications resources effectively, developing incentives to motivate initial participation, and providing rewards or recognition for ongoing engagement. CONCLUSIONS: These results provide valuable formative insights to guide implementation of our proposed hypertension ECHO program for CHEWs in the Federal Capital Territory, Nigeria. This information was used for key decisions around: 1) scope and content of training, 2) format and frequency, 3) selection of implementation strategies, and 4) building a community of practice

    Integrating exome sequencing into a diagnostic pathway for epileptic encephalopathy: Evidence of clinical utility and cost effectiveness

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    © 2017 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc. Background: Epileptic encephalopathies are a devastating group of neurological conditions in which etiological diagnosis can alter management and clinical outcome. Exome sequencing and gene panel testing can improve diagnostic yield but there is no cost-effectiveness analysis of their use or consensus on how to best integrate these tests into clinical diagnostic pathways. Methods: We conducted a retrospective cost-effectiveness study comparing trio exome sequencing with a standard diagnostic approach, for a well-phenotyped cohort of 32 patients with epileptic encephalopathy, who remained undiagnosed after “first-tier” testing. Sensitivity analysis was included with a range of commercial exome and multigene panels. Results: The diagnostic yield was higher for the exome sequencing (16/32; 50%) than the standard arm (2/32; 6.2%). The trio exome sequencing pathway was cost-effective compared to the standard diagnostic pathway with a cost saving of AU5,236(955,236 (95% confidence intervals 2,482; $9,784) per additional diagnosis; the standard pathway cost approximately 10 times more per diagnosis. Sensitivity analysis demonstrated that the majority of commercial exome sequencing and multigene panels studied were also cost-effective. The clinical utility of all diagnoses was reported. Conclusion: Our study supports the integration of exome sequencing and gene panel testing into the diagnostic pathway for epileptic encephalopathy, both in terms of cost effectiveness and clinical utility. We propose a diagnostic pathway that integrates initial rapid screening for treatable causes and comprehensive genomic screening. This study has important implications for health policy and public funding for epileptic encephalopathy and other neurological conditions

    DDoS defense by offense

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    This article presents the design, implementation, analysis, and experimental evaluation of speak-up, a defense against application-level distributed denial-of-service (DDoS), in which attackers cripple a server by sending legitimate-looking requests that consume computational resources (e.g., CPU cycles, disk). With speak-up, a victimized server encourages all clients, resources permitting, to automatically send higher volumes of traffic. We suppose that attackers are already using most of their upload bandwidth so cannot react to the encouragement. Good clients, however, have spare upload bandwidth so can react to the encouragement with drastically higher volumes of traffic. The intended outcome of this traffic inflation is that the good clients crowd out the bad ones, thereby capturing a much larger fraction of the server's resources than before. We experiment under various conditions and find that speak-up causes the server to spend resources on a group of clients in rough proportion to their aggregate upload bandwidths, which is the intended result.National Science Foundation (U.S.) (NSF grant CNS-0225660)National Science Foundation (U.S.) (NSF grant CNS-0520241)United States. Dept. of Defense (National Security Science and Engineering Faculty Fellowship
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