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Search Results: 1 - 10 of 407524 matches for " T. S. Pham "
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Convergence of the Lasserre Hierarchy of SDP Relaxations for Convex Polynomial Programs without Compactness
V. Jeyakumar,T. S. Pham,G. Li
Mathematics , 2013,
Abstract: The Lasserre hierarchy of semidefinite programming (SDP) relaxations is an effective scheme for finding computationally feasible SDP approximations of polynomial optimization over compact semi-algebraic sets. In this paper, we show that, for convex polynomial optimization, the Lasserre hierarchy with a slightly extended quadratic module always converges asymptotically even in the face of non-compact semi-algebraic feasible sets. We do this by exploiting a coercivity property of convex polynomials that are bounded below. We further establish that the positive definiteness of the Hessian of the associated Lagrangian at a saddle-point (rather than the objective function at each minimizer) guarantees finite convergence of the hierarchy. We obtain finite convergence by first establishing a new sum-of-squares polynomial representation of convex polynomials over convex semi-algebraic sets under a saddle-point condition. We finally prove that the existence of a saddle-point of the Lagrangian for a convex polynomial program is also necessary for the hierarchy to have finite convergence.
The evolving role of alemtuzumab (Campath-1H) in renal transplantation
Phuong-Thu T Pham,Gerald S Lipshutz,Phuong-Truc T Pham,Joseph Kawahji
Drug Design, Development and Therapy , 2008,
Abstract: Phuong-Thu T Pham1, Gerald S Lipshutz2, Phuong-Truc T Pham3, Joseph Kawahji1, Jennifer S Singer4, Phuong-Chi T Pham51Division of Nephrology, Department of Medicine, Kidney and Pancreas Transplant Program, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 2Kidney and Pancreas Transplant Program, Department of Surgery and Urology, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 3Department of Science, Penn State University, Worthington-Scranton, Dunmore, Pennsylvania; 4Renal Transplantation and Pediatric Urology, Department of Urology, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 5Division of Nephrology, Department of Medicine, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, and Olive-View-UCLA Medical Center, Sylmar, California, USAAbstract: The introduction of new immunosuppressive agents into clinical transplantation in the 1990s has resulted in excellent short-term graft survival. Nonetheless, extended long-term graft outcomes have not been achieved due in part to the nephrotoxic effects of calcineurin inhibitors (CNIs) and the adverse effects of steroid on cardiovascular disease risk factors. Induction therapy with lymphocyte depleting antibodies has originally been introduced into renal transplantation to provide intense immunosuppression in the early post-transplant period to prevent allograft rejection. Over the past half decade, induction therapy with both non-lymphocyte depleting (basiliximab and daclizumab) and lymphocyte-depleting antibodies (antithymocyte antibodies, OKT3, alemtuzumab) has increasingly been utilized in steroid or CNI sparing protocols in the early postoperative period. Alemtuzumab is a humanized monoclonal antibody targeted against CD52 on the surface of circulatory mononuclear cells. The ability of alemtuzumab (Campath-1H) to provide rapid and profound depletion of lymphocytes from the peripheral blood has sparked interest in the use of this agent as induction therapy in steroid and/or CNI minimization or avoidance protocols. This article provides an overview of the literarure on the evolving role of alemtuzumab in renal transplantation.Keywords: alemtuzumab, Campath-1H, induction, renal transplantation, calcineurin inhibitor minimization, steroid avoidance
Elastomeric Polymers for Retrofitting of Reinforced Concrete Structures against the Explosive Effects of Blast
S. N. Raman,T. Ngo,P. Mendis,T. Pham
Advances in Materials Science and Engineering , 2012, DOI: 10.1155/2012/754142
Abstract: The main distinction of blast load from other types of dynamic loadings is its impulsive nature, where the loads usually act for a very short duration but transmit very high impulsive pressures. This paper presents an overview of the present retrofitting techniques in use to enhance the capacity of structural elements to withstand the effects of blast loads, and introduces an alternative retrofitting approach by utilizing polymer coatings. The authors have demonstrated the positive effects of this approach by conducting a numerical investigation on the behavior of an unretrofitted reinforced concrete panel subjected to the blast load from a 2?kg charge at 1.6?m stand-off distance, and subsequently comparing its performance with several polymer coated panels. The analysis was performed by using an explicit nonlinear finite element (FE) code. The results demonstrate the contributions of this technique in terms of panel displacement control and energy dissipation. Considering that the polymer coating can also act as a protective layer in improving the durability of structural materials, this technique can also be optimized favorably to enhance the overall sustainability of structures. 1. Introduction In recent years, buildings and critical infrastructures across the globe have become more vulnerable to extreme dynamic blast and impact loads due to the increase in terrorist activities, accidental explosions, proliferation of weapons, and so forth. The losses from such events cannot be measured from the economic aspects alone since many of the target structures are iconic and carry substantial heritage, architectural, and sentimental values. While substantial efforts in architecture and structural engineering have been focused towards optimal design and construction practices to meet the desires of sustainability and sustainable development, the need to preserve and protect existing critical infrastructures to meet the needs of the future should not be disregarded. Every effort should be undertaken to preserve and protect such structures, especially for future generations. The main distinction of blast load from other types of extreme loadings is its impulsive nature. Blast loads usually act for a very short duration (usually in milliseconds) but transmit very high impulsive pressures (101–103?kPa). The resulting damage to the structural system can be in several forms, such as damage to the external facade and structural frames of the building; collapse of walls; blowing out of concrete fragments, glass windows and fixtures; and shutting down of critical
The evolving role of alemtuzumab (Campath-1H) in renal transplantation
Phuong-Thu T Pham, Gerald S Lipshutz, Phuong-Truc T Pham, Joseph Kawahji, Jennifer S Singer, Phuong-Chi T Pham
Drug Design, Development and Therapy , 2009, DOI: http://dx.doi.org/10.2147/DDDT.S4179
Abstract: lving role of alemtuzumab (Campath-1H) in renal transplantation Review (6346) Total Article Views Authors: Phuong-Thu T Pham, Gerald S Lipshutz, Phuong-Truc T Pham, Joseph Kawahji, Jennifer S Singer, Phuong-Chi T Pham Published Date December 2008 Volume 2009:3 Pages 41 - 49 DOI: http://dx.doi.org/10.2147/DDDT.S4179 Phuong-Thu T Pham1, Gerald S Lipshutz2, Phuong-Truc T Pham3, Joseph Kawahji1, Jennifer S Singer4, Phuong-Chi T Pham5 1Division of Nephrology, Department of Medicine, Kidney and Pancreas Transplant Program, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 2Kidney and Pancreas Transplant Program, Department of Surgery and Urology, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 3Department of Science, Penn State University, Worthington-Scranton, Dunmore, Pennsylvania; 4Renal Transplantation and Pediatric Urology, Department of Urology, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, California; 5Division of Nephrology, Department of Medicine, University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, and Olive-View-UCLA Medical Center, Sylmar, California, USA Abstract: The introduction of new immunosuppressive agents into clinical transplantation in the 1990s has resulted in excellent short-term graft survival. Nonetheless, extended long-term graft outcomes have not been achieved due in part to the nephrotoxic effects of calcineurin inhibitors (CNIs) and the adverse effects of steroid on cardiovascular disease risk factors. Induction therapy with lymphocyte depleting antibodies has originally been introduced into renal transplantation to provide intense immunosuppression in the early post-transplant period to prevent allograft rejection. Over the past half decade, induction therapy with both non-lymphocyte depleting (basiliximab and daclizumab) and lymphocyte-depleting antibodies (antithymocyte antibodies, OKT3, alemtuzumab) has increasingly been utilized in steroid or CNI sparing protocols in the early postoperative period. Alemtuzumab is a humanized monoclonal antibody targeted against CD52 on the surface of circulatory mononuclear cells. The ability of alemtuzumab (Campath-1H) to provide rapid and profound depletion of lymphocytes from the peripheral blood has sparked interest in the use of this agent as induction therapy in steroid and/or CNI minimization or avoidance protocols. This article provides an overview of the literarure on the evolving role of alemtuzumab in renal transplantation.
Obesity and Preference-Weighted Quality of Life of Ethnically Diverse Middle School Children: The HEALTHY Study
R. P. Trevi?o,T. H. Pham,S. L. Edelstein
Journal of Obesity , 2013, DOI: 10.1155/2013/206074
Abstract: To date, studies examining the relation between body mass index percentile (BMI%) categories and health-related quality of life (QOL) measurements have not reported preference-weighted scores among ethnically diverse children. We report the associations between BMI% categories and preference-weighted scores among a large cohort of ethnically diverse sixth grade children who participated in the HEALTHY school-based type 2 diabetes risk factor prevention study. Health Utility Index 2 (HUI2) and Health Utility Index 3 (HUI3) and the feeling thermometer (FT) were the preference-weighted QOL instruments used to measure student’s preference scores. Of 6358 consented students, 4979 (78.3%) had complete QOL, height, weight, and covariate data. Mean (SD) preference scores were 0.846 (0.160), 0.796 (0.237), and 0.806 (0.161) for the HUI2, HUI3, and FT, respectively. After adjusting for age, sex, blood glucose and insulin, Tanner stage, race/ethnicity, family history of diabetes, and educational attainment, children with severe obesity (>99%) had significantly lower preference scores compared to normal weight on all three instruments (HUI2 ; HUI3 ; and FT ). Obese and severe obese categories were significantly associated with lower HUI2 functional ratings in the mobility domain and with lower HUI3 functional ratings in the speech domain. 1. Introduction The growing literature on the effects of obesity on children’s self-reported health-related quality of life (HRQOL) has shown negative associations between some body mass index percentile (BMI%) categories and HRQOL [1–9]. These studies, however, have mainly been clinic based, used small samples at the extreme ends of the BMI distribution, and included limited numbers of minority children, who suffer the greatest burden from obesity [10]. Although there were two community-based studies that analyzed the relationship between BMI and HRQOL among ethnically diverse children, the percentages of African American and Hispanic children were small and the HRQOL instrument used were health status and not preference weighted [3, 6]. Preference-weighted quality of life (QOL) measurements, also known as quality-adjusted life-years (QALYs), is the measurement recommended by the US Panel on Cost-Effectiveness in Health and Medicine for cost-effectiveness analysis (CEA) [11]. QALY measures are based on economic theories (utility and game theories) that quantify the way in which people make choices when faced with uncertainty [12]. Health status instruments ask people to describe the level of disability in several domains (e.g.,
CP violating phase $γ$ and the partial widths asymmetry in $B^- \to π^+ π^- K^-$ and $B^- \to K^+ K^- K^-$ decays
S. Fajfer,R. J. Oakes,T. N. Pham
Physics , 2002, DOI: 10.1016/S0370-2693(02)02030-0
Abstract: Motivated by recent Belle measurement of the branching ratios $B^- \to \pi^+ \pi^- K^-$ and $B^- \to K^+ K^- K^-$ and $B^\pm \to \chi_{c0} K^\pm$, we investigate the CP violating asymmetry in the partial widths for the decays $B^- \to \pi^+ \pi^- K^-$ and $B^- \to K^+ K^- K^-$, which results from the interference of the nonresonant decay amplitude with the resonant amplitude $B^\pm \to \chi_{c0} K^\pm $ $ \to\pi^+ \pi^- K^\pm $ and $B^\pm \to \chi_{c0} K^\pm$ $ \to K^+ K^- K^-$. By taking $\gamma \simeq 58^o$ we predict that the partial widths asymmetry is reaching 10% for the $B^- \to \pi^+ \pi^- K^-$ decay and 16% for the $B^- \to K^+ K^- K^-$decay.
Resonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays
B. Bajc,S. Fajfer,R. J. Oakes,T. N. Pham
Physics , 1997, DOI: 10.1103/PhysRevD.58.054009
Abstract: We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective Lagrangian developed previously to describe the decays D -> P l nu(l) and D -> V l nu(l). Light vector mesons are included in the model which combines the heavy quark effective Lagrangian and chiral perturbation theory approach. The nonresonant and resonant contributions are compared. With no new parameters the model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We also present useful nonresonant decay distributions. Finally, a similar model, but with a modified current which satisfies the soft pion theorems at the expense of introducing another parameter, is analyzed and the results of the models are compared.
The penguin operators in nonresonant $B^- \to M \bar M π^-$ $(M =π^-, K^-, K^0)$ decays
S. Fajfer,R. J. Oakes,T. N. Pham
Physics , 1998, DOI: 10.1103/PhysRevD.60.054029
Abstract: We investigate the contributions coming from the penguin operators in the nonresonant $B^- \to M \bar M \pi^-$ ($M =\pi^-, K^-, K^0$) decays. The effective Wilson coefficients of the the strong penguin operators $O_{4,6}$ are found to be relatively larger. We calculate the contributions arising from the $O_4$ and $O_6$ operators in the nonresonant decays $B^- \to M \bar M\pi^-$ ($M = \pi^-, K^-, \bar K^0$) using a model combining heavy quark symmetry and the chiral symmetry, developed previously. We find that the forbidden nonresonant $B^- \to K^0 \bar K^0 \pi^-$ decay occurs through the strong penguin operators. These penguin contributions affect the branching ratios for $B^- \to M \bar M\pi^-$ ($M = \pi^-, K^-$) by only a few percent. The branching ratio for $B^- \to K^0 \bar K^0 \pi^-$ is estimated to be of the order $ 10^{-6}$.
Convergent Semidefinite Programming Relaxations for Global Bilevel Polynomial Optimization Problems
V. Jeyakumar,J. B. Lasserre,G. Li,T. S. Pham
Mathematics , 2015,
Abstract: In this paper, we consider a bilevel polynomial optimization problem where the objective and the constraint functions of both the upper and the lower level problems are polynomials. We present methods for finding its global minimizers and global minimum using a sequence of semidefinite programming (SDP) relaxations and provide convergence results for the methods. Our scheme for problems with a convex lower-level problem involves solving a transformed equivalent single-level problem by a sequence of SDP relaxations; whereas our approach for general problems involving a non-convex polynomial lower-level problem solves a sequence of approximation problems via another sequential SDP relaxations.
Error Bounds for Parametric Polynomial Systems with Applications to Higher-Order Stability Analysis and Convergence Rates
G. Li,B. S. Mordukhovich,T. T. A. Nghia,T. S. Pham
Mathematics , 2015,
Abstract: The paper addresses parametric inequality systems described by polynomial functions in finite dimensions, where state-dependent infinite parameter sets are given by finitely many polynomial inequalities and equalities. Such systems can be viewed, in particular, as solution sets to problems of generalized semi-infinite programming with polynomial data. Exploiting the imposed polynomial structure together with powerful tools of variational analysis and semialgebraic geometry, we establish a far-going extension of the \L ojasiewicz gradient inequality to the general nonsmooth class of supremum marginal functions as well as higher-order (H\"older type) local error bounds results with explicitly calculated exponents. The obtained results are applied to higher-order quantitative stability analysis for various classes of optimization problems including generalized semi-infinite programming with polynomial data, optimization of real polynomials under polynomial matrix inequality constraints, and polynomial second-order cone programming. Other applications provide explicit convergence rate estimates for the cyclic projection algorithm to find common points of convex sets described by matrix polynomial inequalities and for the asymptotic convergence of trajectories of subgradient dynamical systems in semialgebraic settings.
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