3,458 research outputs found

    Comparison of Risk from Orbital Debris and Meteoroid Environment Models on the Extravehicular Mobility Unit (EMU)

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    A well-known hazard associated with exposure to the space environment is the risk of failure from an impact from a meteoroid and orbital debris (MMOD) particle. An extravehicular mobility unit (EMU) spacesuit impact during a US extravehicular activity (EVA) is of great concern as a large leak could prevent an astronaut from safely reaching the airlock in time resulting in a loss of life. A risk assessment is provided to the EVA office at the Johnson Space Center (JSC) by the Hypervelocity Impact Technology (HVIT) group prior to certification of readiness for each US EVA. Need to understand the effect of updated meteoroid and orbital debris environment models to EMU risk

    Equiangular tight frames and fourth root seidel matrices

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    AbstractIn this paper we construct complex equiangular tight frames (ETFs). In particular, we study the grammian associated with an ETF whose off-diagonal entries consist entirely of fourth roots of unity. These ETFs are classified, and we also provide some computational techniques which give rise to previously undiscovered ETFs

    Merger and Acquisition Due Diligence: A Proposed Framework to Incorporate Data Privacy, Information Security, E-Discovery, and Information Governance into Due Diligence Practices

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    Merger and Acquisition or “M&A” deals are both figuratively and literally big business, where the stakes for the organization are often the highest. While casual observers might expect that the importance attached to these deals makes each new deal the vanguard for incorporating metrics and practices regarding every efficiency and contingency, existing research demonstrates that this is decidedly not the case

    Beavers, Castor canadensis, Feeding on Salmon Carcasses: Opportunistic Use of a Seasonally Superabundant Food Source

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    We report observations of Beavers (Castor canadensis) foraging and feeding on discarded Chinook Salmon (Oncorhynchus tshawytscha) carcasses within the confines of the Susitna River drainage in southcentral Alaska on three separate occasions between 1999 and 2004. In all three instances, Beavers were observed actively seeking out freshly discarded carcasses or transporting “fresh” salmon carcasses in their mouths. In one instance, Beavers were seen using their dextrous forefeet to “handle” chunks of salmon while hunched over carcasses and in this case we actually witnessed Beavers “chewing” and ingestion was assumed. In the other two instances, Beavers were observed swimming with salmon carcasses in their mouths. Though unique within the framework of Beaver foraging ecology, we suggest this behavior may be a fairly common strategy employed by Beavers in Alaskan streams and rivers to take advantage of a seasonally superabundant source of protein

    Redox-mediated bypass of restriction point via skipping of G1pm

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    BACKGROUND: It is well known that cancer cells bypass the restriction point, R, and undergo uncontrolled cell proliferation. HYPOTHESIS AND EVIDENCE: We suggest here that fibrosarcoma cells enter G(1ps )directly from M, skipping G(1pm), hence bypassing R, in response to redox modulation. Evidence is presented from the published literature that demonstrate a shortening of the cycle period of transformed fibroblasts (SV-3T3) compared to the nontransformed 3T3 fibroblasts, corresponding to the duration of G(1pm )in the 3T3 fibroblasts. Evidence is also presented that demonstrate that redox modulation can induce the CUA-4 fibroblasts to bypass R, resulting in a cycle period closely corresponding to the cycle period of fibrosarcoma cells (HT1080). CONCLUSION: The evidence supports our hypothesis that a low internal redox potential can cause fibrosarcoma cells to skip the G(1pm )phase of the cell cycle

    Merger and Acquisition Due Diligence Part II- The Devil in the Details

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    Our prior scholarship examined the legal and technical challenges involved in modern Merger & Acquisition ( M&A ) due diligence practices associated with transactions ( Deals ), given recent but steady advances in technology and related increases in sophistication seen in Deal participants-primarily the organizations or assets targeted (the Targets ) as part of the Deal, and the organizations that pursued and/or resulted from the Deal (the Acquirers ). We then proposed a framework addressing five particular verticals of interest and concern: data privacy ( DP ), information security ( IS ), e-Discovery, information governance ( IG ), and the due diligence and record keeping associated with the Deal itself ( Deal Information ) (collectively, the Framework )

    Polypharmacy or medication washout: an old tool revisited

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    There has been a rapid increase in the use of polypharmacy in psychiatry possibly due to the introduction of newer drugs, greater availability of these newer drugs, excessive confidence in clinical trial results, widespread prescribing of psychotropic medications by primary care, and pressure to augment with additional medications for unresolved side effects or greater efficacy. Even the new generation of medications may not hold significant advantages over older drugs. In fact, there may be additional safety risks with polypharmacy being so widespread. Washout, as a clinical tool, is rarely done in medication management today. Studies have shown that augmenting therapy with additional medications resulted in 9.1%–34.1% dropouts due to intolerance of the augmentation, whereas studies of medication washout demonstrated only 5.9%–7.8% intolerance to the washout procedure. These perils justify reconsideration of medication washout before deciding on augmentation. There are unwarranted fears and resistance in the medical community toward medication washout, especially at the moment a physician is trying to decide whether to washout or add more medications to the treatment regimen. However, medication washout provides unique benefits to the physician: it establishes a new baseline of the disorder, helps identify medication efficacy from their adverse effects, and provides clarity of diagnosis and potential reduction of drug treatments, drug interactions, and costs. It may also reduce overall adverse events, not to mention a potential to reduce liability. After washout, physicians may be able to select the appropriate polypharmacy more effectively and safely, if necessary. Washout, while not for every patient, may be an effective tool for physicians who need to decide on whether to add potentially risky polypharmacy for a given patient. The risks of washout may, in some cases, be lower and the benefits may be clearly helpful for diagnosis, understanding medication effects, the doctor/patient relationship, and safer use of polypharmacy if indicated

    Extravehicular Activity Micrometeoroid and Orbital Debris Risk Assessment Methodology

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    A well-known hazard associated with exposure to the space environment is the risk of vehicle failure due to an impact from a micrometeoroid and orbital debris (MMOD) particle. Among the vehicles of importance to NASA is the extravehicular mobility unit (EMU) spacesuit used while performing a US extravehicular activity (EVA). An EMU impact is of great concern as a large leak could prevent an astronaut from safely reaching the airlock in time resulting in a loss of life. For this reason, a risk assessment is provided to the EVA office at the Johnson Space Center (JSC) prior to certification of readiness for each US EVA
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