637 research outputs found

    Wigner instability analysis of the damped Hirota equation

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    We address the modulation instability of the Hirota equation in the presence of stochastic spatial incoherence and linear time-dependent amplification/attenuation processes via the Wigner function approach. We show that the modulation instability remains baseband type, though the damping mechanisms substantially reduce the unstable spectrum independent of the higher-order contributions (e.g. the higher-order nonlinear interaction and the third-order dispersion). Additionally, we find out that the unstable structure due to the Kerr interaction exhibits a significant resilience to the third-order-dispersion stabilizing effects in comparison with the higher-order nonlinearity, as well as a moderate Lorentzian spectrum damping may assist the rising of instability. Finally, we also discuss the relevance of our results in the context of current experiments exploring extreme wave events driven by the modulation instability (e.g. the generation of the so-called rogue waves).Comment: 7+4 pages. 3 figures. Comments are welcome. To appear in Physica

    Riesz transforms, Cauchy-Riemann systems and amalgam Hardy spaces

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    In this paper we study Hardy spaces Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d), 0<p,q<0<p,q<\infty, modeled over amalgam spaces (Lp,q)(Rd)(L^p,\ell^q)(\mathbb{R}^d). We characterize Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d) by using first order classical Riesz transforms and compositions of first order Riesz transforms depending on the values of the exponents pp and qq. Also, we describe the distributions in Hp,q(Rd)\mathcal{H}^{p,q}(\mathbb{R}^d) as the boundary values of solutions of harmonic and caloric Cauchy-Riemann systems. We remark that caloric Cauchy-Riemann systems involve fractional derivative in the time variable. Finally we characterize the functions in L2(Rd)Hp,q(Rd)L^2(\mathbb{R}^d) \cap \mathcal{H}^{p,q}(\mathbb{R}^d) by means of Fourier multipliers mθm_\theta with symbol θ(/)\theta(\cdot/|\cdot|), where θC(Sd1)\theta \in C^\infty(\mathbb{S}^{d-1}) and Sd1\mathbb{S}^{d-1} denotes the unit sphere in Rd\mathbb{R}^d.Comment: 24 page

    Twelfth degree spline with application to quadrature

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    Risk factors for unexpected admission following arthroscopic and open treatment of shoulder instability: a national database study of 11,230 cases

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    Background Shoulder instability procedures have low morbidity; however, complications can arise that result in readmission to an inpatient healthcare facility. The purpose of this study is to identify the demographics and risk factors associated with unplanned 30-day readmission and reoperation following arthroscopic and open treatment for shoulder instability. Methods The American College of Surgeons National Surgical Quality Improvement Program database was queried to find patients who underwent shoulder instability surgery from 2015 to 2019. Independent sample Student t-tests, chi-square, and (where appropriate) Fisher’s exact tests were used in univariate analyses to identify demographic, lifestyle, and perioperative variables related to 30-day readmission and reoperation following repair for shoulder instability. Multivariate logistic regression modeling was subsequently performed. Results Of the 11,230 cases included in our sample, only 0.54% were readmitted, and 0.23% underwent reoperation within the 30-day postoperative period. Multivariate logistic regression modeling confirmed that the following patient variables were associated with statistically significantly increased odds of readmission and reoperation: open repair, congestive heart failure (CHF), and hospital length of stay. Conclusions Unplanned 30-day readmission and reoperation after shoulder instability surgery is infrequent. Patients with American Society of Anesthesiologists class II, CHF, longer than average hospital length of stay, or an open procedure have higher odds of readmission than patients without those factors. Patients who have CHF, longer than average hospital length of stay, and open surgery have higher odds of reoperation than others. Arthroscopic procedures should be used to manage shoulder instability, if possible. Level of evidence III

    Theoretical and Experimental Study of the Absorption rate of H2S in CuSO4 Solutions. The Effect of Enhancement of Mass Transfer by a Precipitation Reaction

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    In this paper the desulphurization of gas streams using aqueous copper sulphate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulphurization is accomplished by a precipitation reaction that occurs when sulphide ions and metal ions are brought into contact with each other. Absorption experiments of H2S in aqueous CuSO4 solutions were carried out in a Mechanically Agitated Gas Liquid Reactor. The experiments were conducted at a temperature of 293 K and CuSO4 concentrations between 0.01 and 0.1 M. These experiments showed that the process efficiently removes H2S. Furthermore, the experiments indicate that the absorption of H2S in a CuSO4 solution may typically be considered a mass transfer limited process at, for this type of industrial process, relevant conditions. The extended model developed by Al-Tarazi et al. (2004) has been used to predict the rate of H2S absorption. This model describes the absorption and accompanying precipitation process in terms of, among others, elementary reaction steps, particle nucleation and growth. The results from this extended model and results obtained with a much simpler model, regarding the absorption of H2S in CuSO4 containing aqueous solutions as absorption of a gas accompanied by an instantaneous irreversible reaction were compared with experimental results. From this comparison it appeared that the absorption rate of H2S in a CuSO4 solution can, under certain conditions, be considered as a mass transfer rate controlled process. Under a much wider range of conditions the error that is made by assuming that the absorption process is a mass transfer controlled process, is still within engineering accuracy. Application of the simple model allows for a considerable reduction of the theoretical effort needed for the design of a gas-liquid contacting device, thereby still assuring that the desired gas specification can be met under a wide range of operating conditions. A comparison of the experimental results and the simulated results showed that the extended model gives an under prediction of the H2S absorption rate for the experimental conditions applied

    Neo-LVOT and Transcatheter Mitral Valve Replacement: Expert Recommendations

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    With the advent of transcatheter mitral valve replacement (TMVR), the concept of the neo-left ventricular outflow tract (LVOT) was introduced and remains an essential component of treatment planning. This paper describes the LVOT anatomy and provides a step-by-step computed tomography methodology to segment and measure the neo-LVOT while discussing the current evidence and outstanding challenges. It also discusses the technical and hemodynamic factors that play a major role in assessing the neo-LVOT. A summary of expert-based recommendations about the overall risk of LVOT obstruction in different scenarios is presented along with the currently available methods to reduce the risk of LVOT obstruction and other post-procedural complications

    Risk factors for unexpected readmission and reoperation following open procedures for shoulder instability: a national database study of 1,942 cases

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    Background The purpose of this study was to identify demographics and risk factors associated with unplanned 30-day readmission and reoperation following open procedures for shoulder instability and examine recent trends in open shoulder instability procedures. Methods The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried using current procedural terminology (CPT) codes 23455, 23460, and 23462 to find patients who underwent shoulder instability surgery from 2015 to 2019. Independent sample Student t-tests and chi-square tests were used in univariate analyses to identify demographic, lifestyle, and perioperative variables related to 30-day readmission following repair for shoulder instability. Multivariate logistic regression modeling was subsequently performed. Results In total, 1,942 cases of open surgical procedures for shoulder instability were identified. Within our study sample, 1.27% of patients were readmitted within 30 days of surgery, and 0.85% required reoperation. Multivariate logistic regression modeling confirmed that the following patient variables were associated with a statistically significant increase in the odds of readmission: open anterior bone block/Latarjet-Bristow procedure, being a current smoker, and a long hospital stay (all P<0.05). Multivariate logistic regression modeling confirmed statistically significant increased odds of reoperation with an open anterior bone block or Latarjet-Bristow procedure (P<0.05). Conclusions Unplanned 30-day readmission and reoperation after open shoulder instability surgery is infrequent. Patients who are current smokers, have an open anterior bone block or Latarjet-Bristow procedure, or a longer than average hospital stay have higher odds of readmission than others. Patients who undergo an open anterior bone block or Latarjet-Bristow procedure have higher odds of reoperation than those who undergo an open soft-tissue procedure. Level of evidenceIII

    Measurement of the WW Boson Mass

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    A measurement of the mass of the WW boson is presented based on a sample of 5982 WeνW \rightarrow e \nu decays observed in ppp\overline{p} collisions at s\sqrt{s} = 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a fit to the transverse mass spectrum, combined with measurements of the ZZ boson mass, the WW boson mass is measured to be MW=80.350±0.140(stat.)±0.165(syst.)±0.160(scale)GeV/c2M_W = 80.350 \pm 0.140 (stat.) \pm 0.165 (syst.) \pm 0.160 (scale) GeV/c^2.Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures (submitted to PRL

    Search for Top Squark Pair Production in the Dielectron Channel

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    This report describes the first search for top squark pair production in the channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using 74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence level upper limit on sigma*B is presented. The limit is above the theoretical expectation for sigma*B for this process, but does show the sensitivity of the current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report
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