661 research outputs found
Concepts for radically increasing the numerical convergence rate of the Euler equations
Integral equation and finite difference methods have been developed for solving transonic flow problems using linearized forms of the transonic small disturbance and Euler equations. A key element is the use of a strained coordinate system in which the shock remains fixed. Additional criteria are developed to determine the free parameters in the coordinate straining; these free parameters are functions of the shock location. An integral equation analysis showed that the shock is located by ensuring that no expansion shocks exist in the solution. The expansion shock appears as oscillations in the solution near the sonic line, and the correct shock location is determined by removing these oscillations. A second objective was to study the ability of the Euler equation to model separated flow
Pharmacogenomic strategy for individualizing antidepressant therapy
Despite remarkable progress, pharmacotherapy in general, including that for the treatment of depressive conditions, has often ignored the magnitude and clinical significance of the huge interindividual variations in pharmacokinetics and pharmacodynamics, resulting in poor compliance, suboptimal therapeutic effects, and treatment resistance. Advances in pharmacogenomics and computer modeling technologies hold promise for achieving the goals of “individualized” (“personalized”) medicine. However, the challenges for realizing such goals remain substantial. These include the packaging and interpretation of genotyping results, changes in medical practice (innovation diffusion), and infrasiructural, financing, ethical, and organizational issues related to the use of new information
Role of Endothelial Nitric Oxide Synthase Gene Polymorphisms (Glu298Asp) in Egyptian Patients with Recurrent Spontaneous Abortion
Background: Previous studies indicated an association between endothelial nitric oxide synthase (eNOS) activity and maintenance of pregnancy, but it is rather controversial whether polymorphisms of the gene encoding for eNOS are associated with recurrent spontaneous abortions (RSAs). Aim: The aim was to investigate whether the presence of maternal polymorphism Glu298Asp in exon seven of the eNOS gene increase the risk of RSA in Egyptian women.Subjects and Methods: Hundreds women were randomly selected as the case group. They had at least three RSA before 20th weeks of gestation, same partner and at least one live birth and compared with 100 women, same age range, with no history of abortions or complicated pregnancy as control group. All were investigated for the polymorphism using the polymerase chain reaction‑restriction fragment length polymorphisms method. Data were expressed descriptively as percentages for qualitative values and mean ± standard deviation for quantitative parametric data and comparison of qualitative data was done. Results: Frequency of GG genotype 50/100% in cases and 67/100% in control group. Heterozygous GT frequency was 46/100% in cases and 26/100% in control (P ≤ 0.01, odds ratio [OR] =2.37, and 95% confidence interval [CI] =1.30–4.34). Homozygous TT was 4/100% in the cases and at 7/100% in control (P = 0.68, OR = 0.77, and 95% CI = 0.21–2.76). GG genotype versus GT and GG (P = 0.01, OR = 2.03, and 95% CI = 1.15–3.60). Cases with TT genotype were more susceptible to abortion at an older age with a mean of 29 (4.76) (P = 0.02). Conclusion: In conclusion, (eNOS) Glu298Asp polymorphism was found to be associated with increased risk of RSA in this sample of Egyptian women.KEY WORDS: Endothelial nitric oxide, polymorphism, recurrent spontaneous abortions, synthas
On the Effect of Quantum Interaction Distance on Quantum Addition Circuits
We investigate the theoretical limits of the effect of the quantum
interaction distance on the speed of exact quantum addition circuits. For this
study, we exploit graph embedding for quantum circuit analysis. We study a
logical mapping of qubits and gates of any -depth quantum adder
circuit for two -qubit registers onto a practical architecture, which limits
interaction distance to the nearest neighbors only and supports only one- and
two-qubit logical gates. Unfortunately, on the chosen -dimensional practical
architecture, we prove that the depth lower bound of any exact quantum addition
circuits is no longer , but . This
result, the first application of graph embedding to quantum circuits and
devices, provides a new tool for compiler development, emphasizes the impact of
quantum computer architecture on performance, and acts as a cautionary note
when evaluating the time performance of quantum algorithms.Comment: accepted for ACM Journal on Emerging Technologies in Computing
System
An oil pipeline design problem
Copyright @ 2003 INFORMSWe consider a given set of offshore platforms and onshore wells producing known (or estimated) amounts of oil to be connected to a port. Connections may take place directly between platforms, well sites, and the port, or may go through connection points at given locations. The configuration of the network and sizes of pipes used must be chosen to minimize construction costs. This problem is expressed as a mixed-integer program, and solved both heuristically by Tabu Search and Variable Neighborhood Search methods and exactly by a branch-and-bound method. Two new types of valid inequalities are introduced. Tests are made with data from the South Gabon oil field and randomly generated problems.The work of the first author was supported by NSERC grant #OGP205041. The work of the second author was supported by FCAR (Fonds pour la Formation des Chercheurs et l’Aide à la Recherche) grant #95-ER-1048, and NSERC grant #GP0105574
The impact of random natural variability on aspartic acid racemization ratios in enamel from different types of human teeth
Strangeness Content in the Nucleon
I review recent studies of strangeness content in the nucleon pertaining to
the flavor-singlet , the matrix element and the strangeness
electric and magnetic form factors and , based on
lattice QCD calculations. I shall also discuss the relevance of incorporating
the strangeness content in nuclei in regard to strange baryon-antibaryon
productions from proton-nucleus and nucleus-nucleus collisions at SPS and RHIC
energies.Comment: 11 pages, 4 figures, Invited talk at V Int. Conf. on Strangeness in
Quark Matter, Berkeley, CA, July 20--25, 200
- …