4,123 research outputs found

    REFLECTIONS ON SINO-US SPACE COOPERATION

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    Since 2006, the US Air Force Academy’s Eisenhower Center for Space and Defense Studies has sponsored an annual workshop examining the strategic impact and implications of China’s space program. This workshop series has blossomed into a Track-II process, with participants from the People’s Republic of China (PRC), and unofficial US government presence. A key focus of many of the discussions during these workshops has been the prospects for Sino-US cooperation in space. This issue has gained prominence since the 2007 PRC ASAT test, and the US subsequent 2008 American destruction of a malfunctioning satellite. Sino-US space cooperation is seen as potentially serving a confidence-building function, allowing the two sides to familiarize themselves with each other. This paper will examine some of the proposals laid out in these workshops for proposal, and discuss the potential pitfalls that confront them. It will then make some suggestions about how cooperation might be fostered

    A Good Starting Point for Deterrence

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    A central focus for much of the Cold War was determining what would deter the Soviet Union; this was a topic upon which many of the West’s best and brightest labored to determine. In order to deter the former Soviet Union, a huge intellectual edifice was erected, which helped guide a variety of military programs, including not only the American strategic triad of land-based and sea-based missiles and manned bombers, but tactical nuclear weapons, hardened command and control, and space-based early warning systems. It also incorporated concepts, such as “extended deterrence,” “escalation dominance,” and “mutual assured destruction.

    Activation of estrogen receptor β-dependent nitric oxide signaling mediates the hypotensive effects of estrogen in the rostral ventrolateral medulla of anesthetized rats

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    Abstract Background Apart from their well-known peripheral cardiovascular effects, emerging evidence indicates that estrogen acts as a modulator in the brain to regulate cardiovascular functions. The underlying mechanisms of estrogen in central cardiovascular regulation, however, are poorly understood. The present study investigated the cardiovascular effects of 17β-estradiol (E2β) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, and delineated the engagement of nitric oxide (NO) in E2β-induced cardiovascular responses. Methods In male Sprague-Dawley rats maintained under propofol anesthesia, the changes of blood pressure, heart rate and sympathetic vasomotor tone after microinjection bilaterally into the RVLM of a synthetic estrogen, E2β were examined for at least 120 min. The involvement of ERα and/or ERβ subtypes was determined by microinjection of selective ERα or ERβ agonist into bilateral RVLM. Different NO synthase (NOS) inhibitors were used to evaluate the involvement of differential of NOS isoforms in the cardiovascular effects of E2β. Results Bilateral microinjection of E2β (0.5, 1, or 5 pmol) into the RVLM dose-dependently decreased systemic arterial pressure (SAP) and the power density of the vasomotor components of SAP signals, our experimental index for sympathetic neurogenic vasomotor tone. These cardiovascular depressive effects of E2β (1 pmol) were abolished by co-injection of ER antagonist ICI 182780 (0.25 or 0.5 pmol), but not a transcription inhibitor actinomycin D (10 nmol). Like E2β, microinjection bilaterally into the RVLM of a selective ERβ agonist 2,3-bis(4-hydroxyphenyl) propionitrile (DPN, 1, 2, or 5 pmol) induced significant decreases in these hemodynamic parameters in a dose-dependent manner. In contrast, the selective ERα agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (5 pmol) did not influence the same cardiovascular parameters. Co-administration bilaterally into the RVLM of NOS inhibitor NG-nitro-L-arginine methyl ester (5 nmol) or selective inducible NOS (iNOS) inhibitor S-methylisothiourea (25 pmol), but not selective neuronal NOS inhibitor 7-nitroindazole (0.5 pmol) or endothelial NOS inhibitor N5-(1-Iminoethyl)-L-ornithine (2.5 pmol), significantly attenuated the cardiovascular depressive effects elicited by DPN (2 pmol). Conclusion Our results indicate that E2β in the RVLM elicited short-term cardiovascular depressive effects via an ERβ-dependent nontranscriptional mechanism. These vasodepressor effects of E2β are likely to be mediated by the iNOS-derived NO in the RVLM.</p

    Learning of Temporal Motor Patterns: An Analysis of Continuous Versus Reset Timing

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    Our ability to generate well-timed sequences of movements is critical to an array of behaviors, including the ability to play a musical instrument or a video game. Here we address two questions relating to timing with the goal of better understanding the neural mechanisms underlying temporal processing. First, how does accuracy and variance change over the course of learning of complex spatiotemporal patterns? Second, is the timing of sequential responses most consistent with starting and stopping an internal timer at each interval or with continuous timing? To address these questions we used a psychophysical task in which subjects learned to reproduce a sequence of finger taps in the correct order and at the correct times – much like playing a melody at the piano. This task allowed us to calculate the variance of the responses at different time points using data from the same trials. Our results show that while “standard” Weber’s law is clearly violated, variance does increase as a function of time squared, as expected according to the generalized form of Weber’s law – which separates the source of variance into time-dependent and time-independent components. Over the course of learning, both the time-independent variance and the coefficient of the time-dependent term decrease. Our analyses also suggest that timing of sequential events does not rely on the resetting of an internal timer at each event. We describe and interpret our results in the context of computer simulations that capture some of our psychophysical findings. Specifically, we show that continuous timing, as opposed to “reset” timing, is consistent with “population clock” models in which timing emerges from the internal dynamics of recurrent neural networks

    Interactive Force Control Based on Multimodal Robot Skin for Physical Human-Robot Collaboration

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    This work proposes and realizes a control architecture that can support the deployment of a large-scale robot skin in a Human-Robot Collaboration scenario. It is shown, how whole-body tactile feedback can extend the capabilities of robots during dynamic interactions by providing information about multiple contacts across the robot\u27s surface. Specifically, an uncalibrated skin system is used to implement stable force control while simultaneously handling the multi-contact interactions of a user. The system formulates control tasks for force control, tactile guidance, collision avoidance, and compliance, and fuses them with a multi-priority redundancy resolution strategy. The approach is evaluated on an omnidirectional mobile-manipulator with dual arms covered with robot skin. Results are assessed under dynamic conditions, showing that multi-modal tactile information enables robust force control while at the same time remaining responsive to a user\u27s interactions

    Rotating-Pump Design Code

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    Pump Design (PUMPDES) is a computer program for designing a rotating pump for liquid hydrogen, liquid oxygen, liquid nitrogen, water, methane, or ethane. Using realistic properties of these fluids provided by another program called GASPAK, this code performs a station-by-station, mean-line analysis along the pump flow path, obtaining thermodynamic properties of the pumped fluid at each station and evaluating hydraulic losses along the flow path. The variables at each station are obtained under constraints that are consistent with the underlying physical principles. The code evaluates the performance of each stage and the overall pump. In addition, by judiciously choosing the givens and the unknowns, the code can perform a geometric inverse design function: that is, it can compute a pump geometry that yields a closest approximation of given design point. The code contains two major parts: one for an axial-rotor/inducer and one for a multistage centrifugal pump. The inducer and the centrifugal pump are functionally integrated. The code can be used in designing and/or evaluating the inducer/centrifugal-pump combination or the centrifugal pump alone. The code is written in standard Fortran 77

    Attenuation of Cellular Inflammation Using Glucocorticoid-Functionalized Copolymers

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    This work has demonstrated the functionalization of an amphiphilic diblock copolymer, comprised of polyethylene oxide-polymethyl methacrylate (PEO-PMMA), as well as a triblock copolymer comprised of polymethyloxazoline-polydimethylsiloxane-polymethyloxazoline(PMOXA-PDMS-PM OXA) with the dexamethasone (Dex) glucocorticoid anti-inflammatory. Interfacial deposition of the copolymer and the Dex molecules and subsequent transfer of the hybrid materials to solid substrates were characterized to evaluate the potential of utilizing this composite material as a suppressor of cyto-inflammation to enhance implant biocompatibility. Given the extremely thin dimensions of the film (~4nm), this material would have negligible impact upon the size of the coated device to preclude biological stress. The composite films were interfaced with the RAW264.7 murine macrophages which served as a model cell line for the evaluation of nuclear factor-kappaB (NF-KB)-induced production of a host of inflammatory cytokines including interleukin-6, interleukin-12, tumor necrosis factor-alpha (TNFalpha), as well as the inducible nitric oxide synthase signaling factor which is known to be involved with stress-related processes such as neuronal damage. Lipopolysaccharide or LPS is a component of bacterial membranes that elicits cellular stress following application to RAW cell cultures. Following the induced stress response, significant reductions in the expression of genes associated with the aforementioned cytokines and signaling molecules indicated that macrophages in direct contact with the functionalized copolymer were able to collect Dex that was released from within the polymer network to attenuate cyto-inflammation mechanisms. This composite membrane represents a medically-relevant technology to promote chronic implant functionality and preclusion of bio-fouling

    Erenumab in chronic migraine: Patient-reported outcomes in a randomized double-blind study.

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    OBJECTIVE: To determine the effect of erenumab, a human monoclonal antibody targeting the calcitonin gene-related peptide receptor, on health-related quality of life (HRQoL), headache impact, and disability in patients with chronic migraine (CM). METHODS: In this double-blind, placebo-controlled study, 667 adults with CM were randomized (3:2:2) to placebo or erenumab (70 or 140 mg monthly). Exploratory endpoints included migraine-specific HRQoL (Migraine-Specific Quality-of-Life Questionnaire [MSQ]), headache impact (Headache Impact Test-6 [HIT-6]), migraine-related disability (Migraine Disability Assessment [MIDAS] test), and pain interference (Patient-Reported Outcomes Measurement Information System [PROMIS] Pain Interference Scale short form 6b). RESULTS: Improvements were observed for all endpoints in both erenumab groups at month 3, with greater changes relative to placebo observed at month 1 for many outcomes. All 3 MSQ domains were improved from baseline with treatment differences for both doses exceeding minimally important differences established for MSQ-role function-restrictive (≥3.2) and MSQ-emotional functioning (≥7.5) and for MSQ-role function-preventive (≥4.5) for erenumab 140 mg. Changes from baseline in HIT-6 scores at month 3 were -5.6 for both doses vs -3.1 for placebo. MIDAS scores at month 3 improved by -19.4 days for 70 mg and -19.8 days for 140 mg vs -7.5 days for placebo. Individual-level minimally important difference was achieved by larger proportions of erenumab-treated participants than placebo for all MSQ domains and HIT-6. Lower proportions of erenumab-treated participants had MIDAS scores of severe (≥21) or very severe (≥41) or PROMIS scores ≥60 at month 3. CONCLUSIONS: Erenumab-treated patients with CM experienced clinically relevant improvements across a broad range of patient-reported outcomes. CLINICALTRIALSGOV IDENTIFIER: NCT02066415. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with CM, erenumab treatment improves HRQoL, headache impact, and disability
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