178 research outputs found

    Comparison of High-Order and Low-Order Methods for Large-Eddy Simulation of a Compressible Shear Layer

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    The objective of this work is to compare a high-order solver with a low-order solver for performing large-eddy simulations (LES) of a compressible mixing layer. The high-order method is the Wave-Resolving LES (WRLES) solver employing a Dispersion Relation Preserving (DRP) scheme. The low-order solver is the Wind-US code, which employs the second-order Roe Physical scheme. Both solvers are used to perform LES of the turbulent mixing between two supersonic streams at a convective Mach number of 0.46. The high-order and low-order methods are evaluated at two different levels of grid resolution. For a fine grid resolution, the low-order method produces a very similar solution to the high-order method. At this fine resolution the effects of numerical scheme, subgrid scale modeling, and filtering were found to be negligible. Both methods predict turbulent stresses that are in reasonable agreement with experimental data. However, when the grid resolution is coarsened, the difference between the two solvers becomes apparent. The low-order method deviates from experimental results when the resolution is no longer adequate. The high-order DRP solution shows minimal grid dependence. The effects of subgrid scale modeling and spatial filtering were found to be negligible at both resolutions. For the high-order solver on the fine mesh, a parametric study of the spanwise width was conducted to determine its effect on solution accuracy. An insufficient spanwise width was found to impose an artificial spanwise mode and limit the resolved spanwise modes. We estimate that the spanwise depth needs to be 2.5 times larger than the largest coherent structures to capture the largest spanwise mode and accurately predict turbulent mixing

    Micro-Ramps for External Compression Low-Boom Inlets

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    The application of vortex generators for flow control in an external compression, axisymmetric, low-boom concept inlet was investigated using RANS simulations with three-dimensional (3-D), structured, chimera (overset) grids and the WIND-US code. The low-boom inlet design is based on previous scale model 1- by 1-ft wind tunnel tests and features a zero-angle cowl and relaxed isentropic compression centerbody spike, resulting in defocused oblique shocks and a weak terminating normal shock. Validation of the methodology was first performed for micro-ramps in supersonic flow on a flat plate with and without oblique shocks. For the inlet configuration, simulations with several types of vortex generators were conducted for positions both upstream and downstream of the terminating normal shock. The performance parameters included incompressible axisymmetric shape factor, separation area, inlet pressure recovery, and massflow ratio. The design of experiments (DOE) methodology was used to select device size and location, analyze the resulting data, and determine the optimal choice of device geometry. The optimum upstream configuration was found to substantially reduce the post-shock separation area but did not significantly impact recovery at the aerodynamic interface plane (AIP). Downstream device placement allowed for fuller boundary layer velocity profiles and reduced distortion. This resulted in an improved pressure recovery and massflow ratio at the AIP compared to the baseline solid-wall configuration

    Reduced-order model-based feedback controller design for subsonic cavity flows

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    This paper explores feedback controller design for cavity flows based on reduced-order models derived using Proper Orthogonal Decomposition (POD) along with Galerkin projection method. Our preliminary analysis shows that the equilibrium of the POD model is unstable and a static output feedback controller cannot stabilize it. We develop Linear Quadratic (LQ) optimal state feedback controllers and LQ optimal observers for the linearized models. The linear controllers and observers are applied to the nonlinear system using simulations. The controller robustness is numerically tested with respect to different POD models generated at different forcing frequencies. An estimation for the region of attraction of the linear controllers is also provided

    Prime movers : mechanochemistry of mitotic kinesins

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    Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation

    Increased therapeutic potential of an experimental anti-mitotic inhibitor SB715992 by genistein in PC-3 human prostate cancer cell line

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    BACKGROUND: Kinesin spindle proteins (KSP) are motor proteins that play an essential role in mitotic spindle formation. HsEg5, a KSP, is responsible for the formation of the bipolar spindle, which is critical for proper cell division during mitosis. The function of HsEg5 provides a novel target for the manipulation of the cell cycle and the induction of apoptosis. SB715992, an experimental KSP inhibitor, has been shown to perturb bipolar spindle formation, thus making it an excellent candidate for anti-cancer agent. Our major objective was a) to investigate the cell growth inhibitory effects of SB715992 on PC-3 human prostate cancer cell line, b) to investigate whether the growth inhibitory effects of SB715992 could be enhanced when combined with genistein, a naturally occurring isoflavone and, c) to determine gene expression profile to establish molecular mechanism of action of SB715992. METHODS: PC-3 cells were treated with varying concentration of SB715992, 30 μM of genistein, and SB715992 plus 30 μM of genistein. After treatments, PC-3 cells were assayed for cell proliferation, induction of apoptosis, and alteration in gene and protein expression using cell inhibition assay, apoptosis assay, microarray analysis, real-time RT-PCR, and Western Blot analysis. RESULTS: SB715992 inhibited cell proliferation and induced apoptosis in PC-3 cells. SB715992 was found to regulate the expression of genes related to the control of cell proliferation, cell cycle, cell signaling pathways, and apoptosis. In addition, our results showed that combination treatment with SB715992 and genistein caused significantly greater cell growth inhibition and induction of apoptosis compared to the effects of either agent alone. CONCLUSION: Our results clearly show that SB715992 is a potent anti-tumor agent whose therapeutic effects could be enhanced by genistein. Hence, we believe that SB715992 could be a novel agent for the treatment of prostate cancer with greater success when combined with a non-toxic natural agent like genistein

    Survival of patients with metastatic breast cancer: twenty-year data from two SEER registries

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    BACKGROUND: Many researchers are interested to know if there are any improvements in recent treatment results for metastatic breast cancer in the community, especially for 10- or 15-year survival. METHODS: Between 1981 and 1985, 782 and 580 female patients with metastatic breast cancer were extracted respectively from the Connecticut and San Francisco-Oakland registries of the Surveillance, Epidemiology, and End Results (SEER) database. The lognormal statistical method to estimate survival was retrospectively validated since the 15-year cause-specific survival rates could be calculated using the standard life-table actuarial method. Estimated rates were compared to the actuarial data available in 2000. Between 1991 and 1995, further 752 and 632 female patients with metastatic breast cancer were extracted respectively from the Connecticut and San Francisco-Oakland registries. The data were analyzed to estimate the 15-year cause-specific survival rates before the year 2005. RESULTS: The 5-year period (1981–1985) was chosen, and patients were followed as a cohort for an additional 3 years. The estimated 15-year cause-specific survival rates were 7.1% (95% confidence interval, CI, 1.8–12.4) and 9.1% (95% CI, 3.8–14.4) by the lognormal model for the two registries of Connecticut and San Francisco-Oakland respectively. Since the SEER database provides follow-up information to the end of the year 2000, actuarial calculation can be performed to confirm (validate) the estimation. The Kaplan-Meier calculation for the 15-year cause-specific survival rates were 8.3% (95% CI, 5.8–10.8) and 7.0% (95% CI, 4.3–9.7) respectively. Using the 1991–1995 5-year period cohort and followed for an additional 3 years, the 15-year cause-specific survival rates were estimated to be 9.1% (95% CI, 3.8–14.4) and 14.7% (95% CI, 9.8–19.6) for the two registries of Connecticut and San Francisco-Oakland respectively. CONCLUSIONS: For the period 1981–1985, the 15-year cause-specific survival for the Connecticut and the San Francisco-Oakland registries were comparable. For the period 1991–1995, there was not much change in survival for the Connecticut registry patients, but there was an improvement in survival for the San Francisco-Oakland registry patients

    Polo-Like Kinase-1 Controls Aurora A Destruction by Activating APC/C-Cdh1

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    Polo-like kinase-1 (Plk1) is activated before mitosis by Aurora A and its cofactor Bora. In mitosis, Bora is degraded in a manner dependent on Plk1 kinase activity and the E3 ubiquitin ligase SCF-βTrCP. Here, we show that Plk1 is also required for the timely destruction of its activator Aurora A in late anaphase. It has been shown that Aurora A destruction is controlled by the auxiliary subunit Cdh1 of the Anaphase-Promoting Complex/Cyclosome (APC/C). Remarkably, we found that Plk1-depletion prevented the efficient dephosphorylation of Cdh1 during mitotic exit. Plk1 mediated its effect on Cdh1, at least in part, through direct phosphorylation of the human phosphatase Cdc14A, controlling the phosphorylation state of Cdh1. We conclude that Plk1 facilitates efficient Aurora A degradation through APC/C-Cdh1 activation after mitosis, with a potential role for hCdc14A

    Search of Dark Matter Annihilation in the Galactic Centre using the ANTARES Neutrino Telescope

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    A search for high-energy neutrinos coming from the direction of the GalacticCentre is performed using the data recorded by the ANTARES neutrino telescopefrom 2007 to 2012. The event selection criteria are chosen to maximise thesensitivity to possible signals produced by the self-annihilation of weaklyinteracting massive particles accumulated around the centre of the Milky Waywith respect to the atmospheric background. After data unblinding, the numberof neutrinos observed in the line of sight of the Galactic Centre is found tobe compatible with background expectations. The 90% C.L. upper limits in termsof the neutrino+anti-neutrino flux, Φνμ+νˉμ\rm \Phi_{\nu_{\mu}+\bar{\nu}_\mu}, andthe velocity averaged annihilation cross-section, \rm , arederived for the WIMP self-annihilation channels into \rmb\bar{b},W^{+}W^{-},\tau^{+}\tau^{-},\mu^{+}\mu^{-},\nu\bar{\nu}. The ANTARESlimits for \rm are shown to be the most stringent for aneutrino telescope over the WIMP masses 25GeV<MWIMP<10TeV\rm 25\,GeV < M_{WIMP} < 10\,TeV

    Early high-titer plasma therapy to prevent severe Covid-19 in older adults

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    BACKGROUND: Therapies to interrupt the progression of early coronavirus disease 2019 (Covid-19) remain elusive. Among them, convalescent plasma administered to hospitalized patients has been unsuccessful, perhaps because antibodies should be administered earlier in the course of illness. METHODS We conducted a randomized, double-blind, placebo-controlled trial of convalescent plasma with high IgG titers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in older adult patients within 72 hours after the onset of mild Covid-19 symptoms. The primary end point was severe respiratory disease, defined as a respiratory rate of 30 breaths per minute or more, an oxygen saturation of less than 93% while the patient was breathing ambient air, or both. The trial was stopped early at 76% of its projected sample size because cases of Covid-19 in the trial region decreased considerably and steady enrollment of trial patients became virtually impossible. RESULTS A total of 160 patients underwent randomization. In the intention-to-treat population, severe respiratory disease developed in 13 of 80 patients (16%) who received convalescent plasma and 25 of 80 patients (31%) who received placebo (relative risk, 0.52; 95% confidence interval [CI], 0.29 to 0.94; P = 0.03), with a relative risk reduction of 48%. A modified intention-to-treat analysis that excluded 6 patients who had a primary end-point event before infusion of convalescent plasma or placebo showed a larger effect size (relative risk, 0.40; 95% CI, 0.20 to 0.81). No solicited adverse events were observed. CONCLUSIONS Early administration of high-titer convalescent plasma against SARS-CoV-2 to mildly ill infected older adults reduced the progression of Covid-19. (Funded by the Bill and Melinda Gates Foundation and the Fundación INFANT Pandemic Fund; Dirección de Sangre y Medicina Transfusional del Ministerio de Salud number, PAEPCC19, Plataforma de Registro Informatizado de Investigaciones en Salud number, 1421, and ClinicalTrials.gov number, NCT04479163.).Fil: Libster, Romina Paula. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Pérez Marc, Gonzalo. Hospital Militar Central, Buenos Aires; ArgentinaFil: Wappner, Diego. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Coviello, Silvina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Bianchi, Alejandra. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Braem, Virginia. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Esteban, Ignacio. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Caballero, Mauricio Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Wood, Cristian. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Berrueta, Mabel. Hospital Militar Central; ArgentinaFil: Rondan, Aníbal. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Lescano, Gabriela Mariel. Hospital Dr. Carlos Bocalandro; ArgentinaFil: Cruz, Pablo. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Ritou, Yvonne. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Fernández Viña, Valeria Silvina. Hospital Simplemente Evita; ArgentinaFil: Álvarez Paggi, Damián Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Esperante, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ferreti, Adrián. Hospital Dr. Carlos Bocalandro; ArgentinaFil: Ofman, Gaston. University of Oklahoma; Estados UnidosFil: Ciganda, Álvaro. Gobierno de la Provincia de Buenos Aires. Hospital Interzonal Especializado de Agudos y Cronicos San Juan de Dios.; ArgentinaFil: Rodriguez, Rocío. Hospital Simplemente Evita; ArgentinaFil: Lantos, Jorge. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Valentini, Ricardo. No especifíca;Fil: Itcovici, Nicolás. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Hintze, Alejandra. No especifíca;Fil: Oyarvide, M. Laura. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Etchegaray, Candela. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Neira, Alejandra. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Name, Ivonne. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Alfonso, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Swiss Medical Group; ArgentinaFil: López Castelo, Rocío. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Caruso, Gisela. Hospital Militar Central; ArgentinaFil: Rapelius, Sofía. Hospital Militar Central; ArgentinaFil: Alvez, Fernando. Hospital Militar Central; ArgentinaFil: Etchenique, Federico. Hospital Militar Central; ArgentinaFil: Dimase, Federico. Hospital Militar Central; ArgentinaFil: Alvarez, Darío. Hospital Militar Central; ArgentinaFil: Aranda, Sofía S.. Hospital Militar Central; ArgentinaFil: Sánchez Yanotti, Clara Inés. Hospital Militar Central; ArgentinaFil: De Luca, Julián. Hospital Militar Central; ArgentinaFil: Jares Baglivo, Sofía. Hospital Militar Central; ArgentinaFil: Laudanno, Sofía. Fundación Hematológica Sarmiento; ArgentinaFil: Nowogrodzki, Florencia. Swiss Medical Group; ArgentinaFil: Larrea, Ramiro. Hospital Municipal San Isidro; ArgentinaFil: Silveyra, María. Hospital Militar Central; ArgentinaFil: Leberzstein, Gabriel. No especifíca;Fil: Debonis, Alejandra. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Molinos, Juan. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: González, Miguel. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Perez, Eduardo. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Kreplak, Nicolás. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Pastor Argüello, Susana. Fundación para la Investigación en Infectología Infantil; ArgentinaFil: Gibbons, Luz. Hospital Municipal de San Isidro; ArgentinaFil: Althabe, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Bergel, Eduardo. Sanatorio Sagrado Corazón; ArgentinaFil: Polack, Fernando Pedro. Provincia de Buenos Aires. Ministerio de Salud; Argentin
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