1,020 research outputs found

    A medium-range air combat game solution by a pilot advisory system

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    Air-to-air combat between two aggressive aircraft , both equipped with medium-range guided missiles, is .a key element of future air warfare. This dynamic coni lict can be viewed as an interaction of a twotarget diiferential game (between the air--craft) and two independent missileaircraft pursuit-evasion games. The information structure is, however, rather intricate: though perfect information can be assumed between the two aircraft, the missiles have a limited detection range, beyond which information has to be forwarded by the launching aircraft. Moreover, missile firing cannot be assumed detectable. Problems of such complexity haven't been treated yet in the frame of\ud classical differential game theory. In this paper a prototype Pilot Advisory\ud System (PADS), designed to solve the problems facing the pilot in such an\ud engagement, is described. PADS proposed to be an expert System, which operates in real--time and has a "knowledge base" incorporating differential game concepts and solution elements. PADS simultaneously evalua.tes potential success with the respective risks and advises the pilot when to fire his missile and when to start an evasive maneuver. This advisory system can guarantee survival when so desired by the pilot. but in most situations it maximizes the probability of victory with an accepted level of' risk

    Chemical Reactions: Marijuana, Opioids, and Our Families

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    Chemical Reactions: Marijuana, Opioids, and Our Families is the seventh Massachusetts Family Impact Seminar. This seminar was designed to emphasize a family perspective in policymaking on issues related to the legalization of marijuana and managing the opioid abuse crisis in the Commonwealth. In general, Family Impact Seminars analyze the consequences an issue, policy, or program may have for families

    Repeatability and reproducibility of multiparametric magnetic resonance imaging of the liver

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    As the burden of liver disease reaches epidemic levels, there is a high unmet medical need to develop robust, accurate and reproducible non-invasive methods to quantify liver tissue characteristics for use in clinical development and ultimately in clinical practice. This prospective cross-sectional study systematically examines the repeatability and reproducibility of iron-corrected T1 (cT1), T2*, and hepatic proton density fat fraction (PDFF) quantification with multiparametric MRI across different field strengths, scanner manufacturers and models. 61 adult participants with mixed liver disease aetiology and those without any history of liver disease underwent multiparametric MRI on combinations of 5 scanner models from two manufacturers (Siemens and Philips) at different field strengths (1.5T and 3T). We report high repeatability and reproducibility across different field strengths, manufacturers, and scanner models in standardized cT1 (repeatability CoV: 1.7%, bias -7.5ms, 95% LoA of -53.6 ms to 38.5 ms; reproducibility CoV 3.3%, bias 6.5 ms, 95% LoA of -76.3 to 89.2 ms) and T2* (repeatability CoV: 5.5%, bias -0.18 ms, 95% LoA -5.41 to 5.05 ms; reproducibility CoV 6.6%, bias -1.7 ms, 95% LoA -6.61 to 3.15 ms) in human measurements. PDFF repeatability (0.8%) and reproducibility (0.75%) coefficients showed high precision of this metric. Similar precision was observed in phantom measurements. Inspection of the ICC model indicated that most of the variance in cT1 could be accounted for by study participants (ICC = 0.91), with minimal contribution from technical differences. We demonstrate that multiparametric MRI is a non-invasive, repeatable and reproducible method for quantifying liver tissue characteristics across manufacturers (Philips and Siemens) and field strengths (1.5T and 3T)

    The effects of aerobic and resistance exercise on state anxiety and cognitive function

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    Background: There is a paucity of data directly comparing the effects of aerobic versus resistance exercise within a single cohort. Objective: The study aimed to investigate the effects of an acute bout of aerobic and resistance exercise on state anxiety and cognitive function. Equipment and methods: Participants completed three laboratory visits randomized between aerobic exercise (cycling at a self-selected intensity), resistance exercise (three sets; 10 repetitions; six exercises), and a control condition (seated rest). State anxiety and cognitive function were assessed before and after each condition. Results: Reductions in state anxiety that approached significance were seen immediately following aerobic exercise yet were non-significant in the resistance and control conditions. Cognitive function significantly improved following aerobic exercise yet this was not evident in the resistance or control conditions. Conclusion: Acute aerobic exercise at a self-selected intensity may be an effective way of reducing state anxiety and improving cognitive function, when compared to seated rest or resistance training

    Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update of the evidence-based guidelines from the world society of emergency surgery ASBO working group

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    Background Adhesive small bowel obstruction (ASBO) is a common surgical emergency, causing high morbidity and even some mortality. The adhesions causing such bowel obstructions are typically the footprints of previous abdominal surgical procedures. The present paper presents a revised version of the Bologna guidelines to evidence-based diagnosis and treatment of ASBO. The working group has added paragraphs on prevention of ASBO and special patient groups. Methods The guideline was written under the auspices of the World Society of Emergency Surgery by the ASBO working group. A systematic literature search was performed prior to the update of the guidelines to identify relevant new papers on epidemiology, diagnosis, and treatment of ASBO. Literature was critically appraised according to an evidence-based guideline development method. Final recommendations were approved by the workgroup, taking into account the level of evidence of the conclusion. Recommendations Adhesion formation might be reduced by minimally invasive surgical techniques and the use of adhesion barriers. Non-operative treatment is effective in most patients with ASBO. Contraindications for non-operative treatment include peritonitis, strangulation, and ischemia. When the adhesive etiology of obstruction is unsure, or when contraindications for non-operative management might be present, CT is the diagnostic technique of choice. The principles of non-operative treatment are nil per os, naso-gastric, or long-tube decompression, and intravenous supplementation with fluids and electrolytes. When operative treatment is required, a laparoscopic approach may be beneficial for selected cases of simple ASBO. Younger patients have a higher lifetime risk for recurrent ASBO and might therefore benefit from application of adhesion barriers as both primary and secondary prevention. Discussion This guideline presents recommendations that can be used by surgeons who treat patients with ASBO. Scientific evidence for some aspects of ASBO management is scarce, in particular aspects relating to special patient groups. Results of a randomized trial of laparoscopic versus open surgery for ASBO are awaited

    Spin Torques in Ferromagnetic/Normal Metal Structures

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    Recent theories of spin-current-induced magnetization reversal are formulated in terms of a spin-mixing conductance GmixG^{mix}. We evaluate GmixG^{mix} from first-principles for a number of (dis)ordered interfaces between magnetic and non-magnetic materials. In multi-terminal devices, the magnetization direction of a one side of a tunnel junction or a ferromagnetic insulator can ideally be switched with negligible charge current dissipation.Comment: 4 pages, 1 figur

    Photoassociation spectroscopy of cold calcium atoms

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    Photoassociation spectroscopy experiments on 40Ca atoms close to the dissociation limit 4s4s 1S0 - 4s4p 1P1 are presented. The vibronic spectrum was measured for detunings of the photoassociation laser ranging from 0.6 GHz to 68 GHz with respect to the atomic resonance. In contrast to previous measurements the rotational splitting of the vibrational lines was fully resolved. Full quantum mechanical numerical simulations of the photoassociation spectrum were performed which allowed us to put constraints on the possible range of the calcium scattering length to between 50 a_0 and 300 a_0
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