6,518 research outputs found

    Representative systems for space exploration

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    The topics are presented in viewgraph form and include the following: an overview of the synthesis report; specific architecture 4 implementations; and specific power systems/environment issues

    Life Ascending: Mechanism and Process in Physiological Adaptation to High-Altitude Hypoxia

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    To cope with the reduced availability of O2 at high altitude, air-breathing vertebrates have evolved myriad adjustments in the cardiorespiratory system to match tissue O2 delivery with metabolic O2 demand. We explain how changes at interacting steps of the O2 transport pathway contribute to plastic and evolved changes in whole-animal aerobic performance under hypoxia. In vertebrates native to high altitude, enhancements of aerobic performance under hypoxia are attributable to a combination of environ- mentally induced and evolved changes in multiple steps of the pathway. Additionally, evidence suggests that many high-altitude natives have evolved mechanisms for attenuating maladaptive acclimatization responses to hypoxia, resulting in counter-gradient patterns of altitudinal variation for key physiological phenotypes. For traits that exhibit counteracting environmental and genetic effects, evolved changes in phenotype may be cryptic under field conditions and can only be revealed by rearing representatives of high- and low-altitude populations under standardized environmental conditions to control for plasticity

    Towards Hardware-Based Application Fingerprinting with Microarchitectural Signals for Zero Trust Environments

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    The interactions between software and hardware are increasingly important to computer system security. This research collects sequences of microprocessor control signals to develop machine learning models that identify software tasks. The proposed approach considers software task identification in hardware as a general problem with attacks treated as a subset of software tasks. Two lines of effort are presented. First, a data collection approach is described to extract sequences of control signals labeled by task identity during real (i.e., non-simulated) system operation. Second, experimental design is used to select hardware and software configuration to train and evaluate machine learning models. The machine learning models significantly outperform a Naive classifier based on Euclidean distances from class means. Various configurations produce balanced accuracy scores between 26.08% and 96.89%

    Hybrid phase-space simulation method for interacting Bose fields

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    We introduce an approximate phase-space technique to simulate the quantum dynamics of interacting bosons. With the future goal of treating Bose-Einstein condensate systems, the method is designed for systems with a natural separation into highly occupied (condensed) modes and lightly occupied modes. The method self-consistently uses the Wigner representation to treat highly occupied modes and the positive-P representation for lightly occupied modes. In this method, truncation of higher-derivative terms from the Fokker-Planck equation is usually necessary. However, at least in the cases investigated here, the resulting systematic error, over a finite time, vanishes in the limit of large Wigner occupation numbers. We tested the method on a system of two interacting anharmonic oscillators, with high and low occupations, respectively. The Hybrid method successfully predicted atomic quadratures to a useful simulation time 60 times longer than that of the positive-P method. The truncated Wigner method also performed well in this test. For the prediction of the correlation in a quantum nondemolition measurement scheme, for this same system, the Hybrid method gave excellent agreement with the exact result, while the truncated Wigner method showed a large systematic error.Comment: 13 pages; 6 figures; references added; figures correcte

    Detection of Toxicity in Ruminants Consuming Leucaena (\u3cem\u3eLeucaena leucocephala\u3c/em\u3e) Using a Urine Colorimetric Test

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    Leucaena (Leucaena leucocephala), a productive leguminous shrub for feeding ruminant livestock, contains the toxic amino acid, mimosine which post- ingestion is converted to 3,4-DHP and 2,3-DHP, isomers of dihydroxy-pyridone. While DHP generally does not exhibit acute toxic symptoms, it has been suggested that it is an appetite suppressant that reduces animal live weight gain (Jones 1994). With no observable symptoms, subclinical toxicity is difficult to detect (Phaikaew et al. 2012). In 1982 the DHP-degrading rumen bacterium named Synergistes jonesii was introduced into Australia as a potential solution to DHP toxicity as it spreads easily throughout cattle herds grazing leucaena (Jones 1994). However, toxicity events reported since the 2003 drought suggest that the toxicity status of herds, previously understood as being protected, may have changed. This may be the result of loss of effective S. jonesii bacteria from the rumen. Widespread subclinical leucaena toxicity has since been confirmed representing a significant economic threat to the beef industry (Dalzell et al. 2012). At present the testing for toxicity requires a sophisticated chemical analysis of urine samples using high performance liquid chromatography (HPLC). Producers, however, require a robust and reliable means to routinely test for toxicity in their herds. A colorimetric urine test protocol is available based on the colour reaction of mimosine and DHP with FeCl3 solution (Jones 1997). When this simpler colorimetric test has been used under a wide range of conditions false negatives have been reported. The aim of this study was to improve the reliability of the FeCL3 urine colour test

    IronNetInjector: Weaponizing .NET Dynamic Language Runtime Engines

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    As adversaries evolve their Tactics, Techniques, and Procedures (TTPs) to stay ahead of defenders, Microsoft’s .NET Framework emerges as a common component found in the tradecraft of many contemporary Advanced Persistent Threats (APTs), whether through PowerShell or C#. Because of .NET’s ease of use and availability on every recent Windows system, it is at the forefront of modern TTPs and is a primary means of exploitation. This article considers the .NET Dynamic Language Runtime as an attack vector, and how APTs have utilized it for offensive purposes. The technique under scrutiny is Bring Your Own Interpreter (BYOI), which is the ability of developers to embed dynamic languages into .NET using an engine. The focus of this analysis is an adversarial use case in which APT Turla utilized BYOI as an evasion technique, using an IronPython .NET Injector named IronNetInjector. This research analyzes IronNetInjector and how it was used to reflectively load .NET assemblies. It also evaluates the role of Antimalware Scan Interface (AMSI) in defending Windows. Due to AMSI being at the core of Windows malware mitigation, this article further evaluates the memory patching bypass technique by demonstrating a novel AMSI bypass method in IronPython using Platform Invoke (P/Invoke)

    The connexin mimetic peptide Gap27 and Cx43-Knockdown reveal differential roles for Connexin43 in wound closure events in skin model systems

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    In the epidermis, remodelling of Connexin43 is a key event in wound closure. However, controversy between the role of connexin channel and non-channel functions exist. We compared the impact of SiRNA targeted to Connexin43 and the connexin mimetic peptide Gap27 on scrape wound closure rates and hemichannel signalling in adult keratinocytes (AK) and fibroblasts sourced from juvenile foreskin (JFF), human neonatal fibroblasts (HNDF) and adult dermal tissue (ADF). The impact of these agents, following 24 h exposure, on (encoding Connexin43), and gene expression, and Connexin43 and pSmad3 protein expression levels, were examined by qPCR and Western Blot respectively. In all cell types Gap27 (100-100 μM) attenuated hemichannel activity. In AK and JFF cells, Gap27 (100 nM-100 μM) enhanced scrape wound closure rates by ~50% but did not influence movement in HNDF or ADF cells. In both JF and AK cells, exposure to Gap27 for 24 h reduced the level of Cx43 protein expression but did not affect the level in ADF and HNDF cells. Connexin43-SiRNA enhanced scrape wound closure in all the cell types under investigation. In HDNF and ADF, Connexin43-SiRNA enhanced cell proliferation rates, with enhanced proliferation also observed following exposure of HDNF to Gap27. By contrast, in JFF and AK cells no changes in proliferation occurred. In JFF cells, Connexin43-SiRNA enhanced levels and in JFF and ADF cells both Connexin43-SiRNA and Gap27 enhanced pSmad3 protein expression levels. We conclude that Connexin43 signalling plays an important role in cell migration in keratinocytes and foreskin derived fibroblasts, however, different pathways are evoked and in dermal derived adult and neonatal fibroblasts, inhibition of Connexin43 signalling plays a more significant role in regulating cell proliferation than cell migration

    A meta-analytic review of play therapy with emphasis on outcomes measures

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    A meta-analysis of 100 studies of outcomes of play therapy interventions was conducted to determine overall effect of intervention. Different from the Bratton, Ray, Rhine, and Jones (2005), but more consistent with the Lin and Bratton (2015), findings, there was a significant moderate effect for play therapy interventions across all outcomes (d = .44). When 4 studies with aberrantly large effects were removed, this effect was d = .36. These moderate effects are consistent with other meta-analyses that find lower effect sizes for nonbehavioral interventions. Overall study quality was poor with no studies meeting the criteria of randomized control trials. Research on play therapy interventions also does not use diagnostic criteria as part of study inclusion, thus preventing play therapy interventions from being considered as empirically supported treatments. Meta-analytic findings differed by type of measure used, with measures of family functioning/relationships finding larger results than other types of measures. There was not strong consistency in measures used across the studies, with only a few measures being used across more than 1 or 2 studies. Of the more frequently used measures, the Measurement of Empathy in Adult Child Interaction (MEACI) resulted in much larger effects than other measures used, and should be further evaluated in terms of appropriate interpretation and use. Effect sizes also differed based on the reporting source, with teachers tending to rate lower impacts of treatment than other reporters

    Paper Session III-B - Journey into Tomorrow: Developing Nuclear Propulsion for the Space Exploration Initiative

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    The Space Exploration Initiative (SEI) calls for a return to the Moon and carrying out human exploration of Mars. Trips to Mars involve considerably more time and more complex operations than trips to the Moon; hence, there is a keen interest in developing better space transportation systems. Nuclear propulsion, either nuclear thermal propulsion (NTP) or nuclear electric propulsion (NEP), offers the potential of reduced trip times and/or reduced mass into low Earth orbit, compared to chemical propulsion systems . In addition, the greater performance benefits of nuclear propulsion can provide the added margin for greater operational flexibility, including mission abort options and increased launch windows. During the 1950\u27s and 1960\u27s, experimental and analytical studies showed the feasibility of nuclear propulsion. NASA, in cooperation with other agencies and organizations, is currently planning a technology development program for nuclear propulsion. The overall objective is to develop at least one NTP concept and one NEP concept for piloted and robotic (e.g., cargo) missions to Mars
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