483 research outputs found

    Super-optimal approximation by meromorphic functions.

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    Let G be a matrix function of type m × n and suppose that G is expressible as the sum of an H∞ function and a continuous function on the unit circle. Suppose also that the (k – 1)th singular value of the Hankel operator with symbol G is greater than the kth singular value. Then there is a unique superoptimal approximant to G in : that is, there is a unique matrix function Q having at most k poles in the open unit disc which minimizes s∞(G – Q) or, in other words, which minimizes the sequence with respect to the lexicographic ordering, where and Sj(·) denotes the jth singular value of a matrix. This result is due to the present authors [PY1] in the case k = 0 (when the hypothesis on the Hankel singular values is vacuous) and to S. Treil[T2] in general. In this paper we give a proof of uniqueness by a diagonalization argument, a high level algorithm for the computation of the superoptimal approximant and a recursive parametrization of the set of all optimal solutions of a matrix Nehari—Takagi problem

    Space shuttle digital flight control system

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    The space shuttle digital, fly by wire, flight control system presents an interesting challenge in avionics system design. In residence in each of four redundant general purpose computers at lift off are the guidance, navigation, and control algorithms for the entire flight. The mission is divided into several flight segments: first stage ascent, second stage ascent; abort to launch site, abort once around; on orbit operations, entry, terminal area energy management; and approach and landing. The FCS is complicated in that it must perform the functions to fly the shuttle as a boost vehicle, as a spacecraft, as a reentry vehicle, and as a conventional aircraft. The crew is provided with both manual and automatic modes of operations in all flight phases including touchdown and rollout

    Influence of beta-blockers on endothelial function: A meta-analysis of randomized controlled trials

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    Background: Endothelial dysfunction (ED) frequently precedes cardiovascular diseases (CVD) and is a well-established risk factor of major adverse cardiac events. Beta-blockers are the fundamental drugs used in CVD treatment. Methods: A systematic literature search for randomized controlled trials investigating influence of beta-blockers on endothelial function assessed by flow-mediated dilation (FMD) was performed in the PubMed and Cochrane Databases. Results: Sixteen full-text studies involving a total of 1,273 patients were included in the final analysis. The mean age of participating patients ranged from 44.9 to 63.2 years, the follow-up duration from 1 to 12 months. The comparison of FMD change between the beta-blockers and placebo groups showed a statistically significant effect of beta-blockers on endothelial function (mean difference [MD] 0.83; 95% confidence interval [CI] 0.11–1.55; p = 0.02). Third generation beta-blockers improved FMD in a statistically significant manner compared with second generation beta-blockers (MD 1.65; 95% CI 0.17–3.11; p = 0.03). Beta-blockers gave an FMD change similar to that obtained with angiotensin receptor blockers (ARB), calcium channel blockers (CCB) or hydrochlorothiazide. The FMD value in the beta-blocker group was significantly lower compared with the group treated with angiotensin converting enzyme inhibitors (ACEI) (MD –0.79; 95% CI –1.37–(–0.21); p = 0.008) and higher than in the ivabradine group (1.6 ± 3.61 vs –0.3 ± 1.66; p = 0.02). Conclusions: Beta-blockers improve the endothelial function compared with placebo. More­over, third generation beta-blockers improve FMD values significantly better than the second generation ones. Beta-blockers had similar effect on endothelial function as did ARB, CCB or diuretics. However, the beneficial effect of beta-blockers was lower when confronted with ACEI

    Meromorphic Approximants to Complex Cauchy Transforms with Polar Singularities

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    We study AAK-type meromorphic approximants to functions FF, where FF is a sum of a rational function RR and a Cauchy transform of a complex measure λ\lambda with compact regular support included in (1,1)(-1,1), whose argument has bounded variation on the support. The approximation is understood in LpL^p-norm of the unit circle, p2p\geq2. We obtain that the counting measures of poles of the approximants converge to the Green equilibrium distribution on the support of λ\lambda relative to the unit disk, that the approximants themselves converge in capacity to FF, and that the poles of RR attract at least as many poles of the approximants as their multiplicity and not much more.Comment: 39 pages, 4 figure

    Construction of coarse-grained order-parameters in non-equilibrium systems

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    We develop a renormalization group (RG) procedure that includes important system-specific features. The key ingredient is to systematize the coarse graining procedure that generates the RG flow. The coarse graining technology comes from control and operator theoretic model reduction. The resulting "generalized" RG is a consistent generalization of the Wilsonian RG. We derive the form of the projection operator from the dynamics of a nonlinear wave equation and renormalize the distribution of initial conditions. The probability density of the initial conditions is chosen to be the Boltzmann weight for a standard ϕ4\phi^4-theory. In our calculation, we find that in contrast to conventional implementations of the RG, na\"ive power counting breaks down. The RG-equations that we derive are different from those derived from the conventional RG.Comment: 13 pages, 0 figure

    The interdependence of behavioral and somatic health: implications for conceptualizing health and measuring treatment outcomes

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    <b>Purpose:</b> The interdependence of behavioral and somatic aspects of various health conditions warrants greater emphasis on an integrated care approach.<br><br> <b>Theory:</b> We propose that integrated approaches to health and wellness require comprehensive and empirically-valid outcome measures to assess quality of care.<br><br> <b>Method:</b> We discuss the transition from independent to integrated treatment approaches and provide examples of new systems for integrated assessment of treatment outcome.<br><br> <b>Results:</b> Evidence suggests that support for an independent treatment approach is waning and momentum is building towards more integrated care. In addition, research evidence suggests integrated care improves health outcomes, and both physicians and patients have favorable impressions of integrated care.<br><br> <b>Conclusions:</b> As treatment goals in the integrated perspective expand to take into account the intimate relationships among mental illness, overall health, and quality of life, clinicians need to develop outcome measures that are similarly comprehensive. Discussion: Increased recognition, by researchers, providers, and insurers, of the interdependence between behavioral and physical health holds great promise for innovative treatments that could significantly improve patients' lives

    The relationship between structural game characteristics and gambling behavior: a population-level study

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    The aim of this study was to examine the relationship between the structural characteristics and gambling behavior among video lottery terminal (VLT) gamblers. The study was ecological valid, because the data consisted of actual gambling behavior registered in the participants natural gambling environment without intrusion by researchers. Online behavioral tracking data from Multix, an eight game video lottery terminal, were supplied by Norsk-Tipping (the state owned gambling company in Norway). The sample comprised the entire population of Multix gamblers (N = 31,109) who had gambled in January 2010. The individual number of bets made across games was defined as the dependent variable, reward characteristics of a game (i.e., payback percentage, hit frequency, size of winnings and size of jackpot) and bet characteristics of a game (i.e., range of betting options and availability of advanced betting options) served as the independent variables. Control variables were age and gender. Two separate cross-classified multilevel random intercepts models were used to analyze the relationship between bets made, reward characteristics and bet characteristics, where the number of bets was nested within both individuals and within games. The results show that the number of bets is positively associated with payback percentage, hit frequency, being female and age, and negatively associated with size of wins and range of available betting options. In summary, the results show that the reward characteristics and betting options explained 27 % and 15 % of the variance in the number of bets made, respectively. It is concluded that structural game characteristics affect gambling behavior. Implications of responsible gambling are discussed

    OCULUS study: Virtual reality-based education in daily clinical practice

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    Background: Atrial fibrillation (AF) is associated with high risk of stroke and other thromboembolic complications. The OCULUS study aimed to evaluate the effectiveness of the three-dimensional (3D) movie in teaching patients about the consequences of AF and pharmacological stroke prevention.  Methods: The study was based on a questionnaire and included 100 consecutive patients (38% women, 62% with AF history). Using the oculus glasses and a smartphone, a 3D movie describing the risk of stroke in AF was shown. Similar questions were asked immediately after, 1 week and 1 year after the projection.  Results: Before the projection 22/100 (22.0%) declared stroke a consequence of AF, while immediately after 83/100 (83.0%) (p &lt; 0.0001) patients declared this consequence. Seven days after, stroke as AF consequence was chosen by 74/94 (78.7%) vs. 22/94 (23.4%) when compared to the baseline knowledge; p &lt; 0.0001, a similar trend was also observed in 1-year follow-up (64/90 [71.1%] vs. 21/90 [23.3%]; p &lt; 0.0001). Before the projection 88.3% (83/94) patients responded, that drugs may reduce the risk of stroke, and after 1 week the number of patients increased to (94/94 [100%]; p = 0.001). After 1 year 87/90 (96.7%) answered that drugs may diminish the risk of stroke (p = 0.02 in comparison to the baseline survey 78/90 [86.7%]). Use of oral anticoagulation to reduce the risk of stroke was initially chosen by 66/94 (70.2%), by 90/94 (95.7%; p &lt; 0.0001) 7 days after and by 83/90 (92.2%; p &lt; 0.0001) 1 year after.  Conclusions: 3D movie is an effective tool in transferring knowledge about the consequences of AF and the pivotal role of oral anticoagulation in stroke prevention. Trial registration: ClinicalTrials.gov, NCT03104231. Registered on 28 March 2017
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