350 research outputs found
The Vietnam War: A comparison of interpretations
This thesis is based on a quantitative analysis of Time magazine\u27s coverage of the Vietnam War. It demonstrates that Time held a pro-war bias in 1967, was neutral during 1968, and turned strongly against the war from 1969 through 1974. From mid-1969 on, some articles factually misrepresented what was happening in Vietnam in such a way as to promote the goals of the anti-war movement. If events admitted of both a pro-war and an anti-war interpretation Time published almost exclusively the anti-war view. By 1972, administration supporters had published a large body of verifiable evidence (summarized in chapter 3) demonstrating that progress was being made toward winning the war. Time reported on almost none of this evidence. Consequently, this thesis concludes that the previous authors who have written about the media\u27s role in the war (Herbert Gans, Clarence Wyatt and Daniel Hallin) were incorrect: Time\u27s heavily biased anti-war coverage did in fact hurt the war effort
On the use of a Modified Latin Hypercube Sampling (MLHS) approach in the estimation of a Mixed Logit model for vehicle choice
Quasi-random number sequences have been used extensively for many years in the simulation of integrals that do not have a closed-form expression, such as Mixed Logit and Multinomial Probit choice probabilities. Halton sequences are one example of such quasi-random number sequences, and various types of Halton sequences, including standard, scrambled, and shuffled versions, have been proposed and tested in the context of travel demand modeling. In this paper, we propose an alternative to Halton sequences, based on an adapted version of Latin Hypercube Sampling. These alternative sequences, like scrambled and shuffled Halton sequences, avoid the undesirable correlation patterns that arise in standard Halton sequences. However, they are easier to create than scrambled or shuffled Halton sequences. They also provide more uniform coverage in each dimension than any of the Halton sequences. A detailed analysis, using a 16-dimensional Mixed Logit model for choice between alternative-fuelled vehicles in California, was conducted to compare the performance of the different types of draws. The analysis shows that, in this application, the Modified Latin Hypercube Sampling (MLHS) outperforms each type of Halton sequence. This greater accuracy combined with the greater simplicity make the MLHS method an appealing approach for simulation of travel demand models and simulation-based models in general
Qubit-Qutrit Separability-Probability Ratios
Paralleling our recent computationally-intensive (quasi-Monte Carlo) work for
the case N=4 (quant-ph/0308037), we undertake the task for N=6 of computing to
high numerical accuracy, the formulas of Sommers and Zyczkowski
(quant-ph/0304041) for the (N^2-1)-dimensional volume and (N^2-2)-dimensional
hyperarea of the (separable and nonseparable) N x N density matrices, based on
the Bures (minimal monotone) metric -- and also their analogous formulas
(quant-ph/0302197) for the (non-monotone) Hilbert-Schmidt metric. With the same
seven billion well-distributed (``low-discrepancy'') sample points, we estimate
the unknown volumes and hyperareas based on five additional (monotone) metrics
of interest, including the Kubo-Mori and Wigner-Yanase. Further, we estimate
all of these seven volume and seven hyperarea (unknown) quantities when
restricted to the separable density matrices. The ratios of separable volumes
(hyperareas) to separable plus nonseparable volumes (hyperareas) yield
estimates of the separability probabilities of generically rank-six (rank-five)
density matrices. The (rank-six) separability probabilities obtained based on
the 35-dimensional volumes appear to be -- independently of the metric (each of
the seven inducing Haar measure) employed -- twice as large as those (rank-five
ones) based on the 34-dimensional hyperareas. Accepting such a relationship, we
fit exact formulas to the estimates of the Bures and Hilbert-Schmidt separable
volumes and hyperareas.(An additional estimate -- 33.9982 -- of the ratio of
the rank-6 Hilbert-Schmidt separability probability to the rank-4 one is quite
clearly close to integral too.) The doubling relationship also appears to hold
for the N=4 case for the Hilbert-Schmidt metric, but not the others. We fit
exact formulas for the Hilbert-Schmidt separable volumes and hyperareas.Comment: 36 pages, 15 figures, 11 tables, final PRA version, new last
paragraph presenting qubit-qutrit probability ratios disaggregated by the two
distinct forms of partial transpositio
Tailored intervention to increase dual-contraceptive method use: a randomized trial to reduce unintended pregnancies and sexually transmitted infections
Objective: The objective of the study was to determine whether a transtheoretical model–tailored expert system intervention increases dual-method contraceptive use, compared with a nontailored educational intervention.
Study Design: We performed a randomized clinical trial of 542 women at high risk for sexually transmitted infections (STIs) and unintended pregnancy. The intervention group received computer-based tailored feedback using a multimedia program. The control group received general contraceptive information and nontailored advice.
Results: Participants in the intervention group were more likely to report use of dual contraceptive methods during follow-up (adjusted hazard rate ratio 1.70, 95% confidence interval 1.09, 2.66), compared with controls. However, there were no differences in the rates of incident STI or unintended pregnancy between the 2 groups. Conclusions: The computer-based transtheoretical model–tailored intervention resulted in a 70% increase in reported dual-method contraceptive use in a group of women at high risk for STIs and unintended pregnancy. Inconsistent use of dual methods may explain the lack of effect on unintended pregnancy rates and incident STIs
The Interleukin-11/IL-11 receptor promotes glioblastoma survival and invasion under glucose-starved conditions through enhanced glutaminolysis
Glioblastoma cells adapt to changes in glucose availability through metabolic plasticity allowing for cell survival and continued progression in low-glucose concentrations. However, the regulatory cytokine networks that govern the ability to survive in glucose-starved conditions are not fully defined. In the present study, we define a critical role for the IL-11/IL-11
Simulation-based optimal Bayesian experimental design for nonlinear systems
The optimal selection of experimental conditions is essential to maximizing
the value of data for inference and prediction, particularly in situations
where experiments are time-consuming and expensive to conduct. We propose a
general mathematical framework and an algorithmic approach for optimal
experimental design with nonlinear simulation-based models; in particular, we
focus on finding sets of experiments that provide the most information about
targeted sets of parameters.
Our framework employs a Bayesian statistical setting, which provides a
foundation for inference from noisy, indirect, and incomplete data, and a
natural mechanism for incorporating heterogeneous sources of information. An
objective function is constructed from information theoretic measures,
reflecting expected information gain from proposed combinations of experiments.
Polynomial chaos approximations and a two-stage Monte Carlo sampling method are
used to evaluate the expected information gain. Stochastic approximation
algorithms are then used to make optimization feasible in computationally
intensive and high-dimensional settings. These algorithms are demonstrated on
model problems and on nonlinear parameter estimation problems arising in
detailed combustion kinetics.Comment: Preprint 53 pages, 17 figures (54 small figures). v1 submitted to the
Journal of Computational Physics on August 4, 2011; v2 submitted on August
12, 2012. v2 changes: (a) addition of Appendix B and Figure 17 to address the
bias in the expected utility estimator; (b) minor language edits; v3
submitted on November 30, 2012. v3 changes: minor edit
Sexual dysfunction among married couples living in Kumasi metropolis, Ghana
<p>Abstract</p> <p>Background</p> <p>Sexuality and its manifestation constitute some of the most complex of human behaviour and its disorders are encountered in community. Sexual dysfunction is more prevalent in women than in men. While studies examining sexual dysfunction among males and females in Ghana exist, there are no studies relating sexual problems in males and females as dyadic units. This study therefore investigated the prevalence and type of sexual disorders among married couples.</p> <p>Method</p> <p>The study participants consisted of married couples between the ages of 19 and 66 living in the province of Kumasi, Ghana. Socio-demographic information and Golombok-Rust Inventory of Sexual Satisfaction (GRISS) questionnaires were administered to 200 couples who consented to take part in the study. All 28 questions of the GRISS are answered on a five-point (Likert type) scale from "always", through "usually', "sometimes", and "hardly ever", to "never". Responses are summed up to give a total raw score ranging from 28-140. The total score and subscale scores are transformed using a standard nine point scale, with high scores indicating greater problems. Scores of five or more are considered to indicate SD. The study was conducted between July and September 2010.</p> <p>Results</p> <p>Out of a total of 200 married couples, 179 completed their questionnaires resulting in a response rate of 89.5%. The mean age of the participating couples as well as the mean duration of marriage was 34.8 ± 8.6 years and 7.8 ± 7.6 years respectively. The husbands (37.1 ± 8.6) were significantly older (p < 0.0001) than their corresponding wives (32.5 ± 7.9). After adjusting for age, 13-18 years of marriage life poses about 10 times significant risk of developing SD compared to 1-6 years of married life among the wives (OR: 10.8; CI: 1.1 - 49.1; p = 0.04). The total scores (6.0) as well as the percentage above the cut-off (59.2) obtained by the husbands compared to the total score (6.2) and the percentage above cut-off (61.5) obtained by the wives, indicates the likely presence of sexual dysfunction. The prevalence of impotence and premature ejaculation were 60.9% and 65.4% respectively from this study and the prevalence of vaginismus and anorgasmia were 69.3% and 74.9% respectively. The highest prevalence of SD subscales among the men was dissatisfaction with sexual act followed by infrequency, whereas the highest among the women was infrequency followed by anorgasmia. Dissatisfaction with sexual intercourse among men correlated positively with anorgasmia and wife's non-sensuality and infrequency of sex.</p> <p>Conclusion</p> <p>The prevalence of sexual dysfunction in married couples is comparable to prevalence rates in the general male and female population and is further worsened by duration of marriage. This could impact significantly on a couple's self-esteem and overall quality of life.</p
Parallel cross interpolation for high-precision calculation of high-dimensional integrals
We propose a parallel version of the cross interpolation algorithm and apply it to calculate high-dimensional integrals motivated by Ising model in quantum physics. In contrast to mainstream approaches, such as Monte Carlo and quasi Monte Carlo, the samples calculated by our algorithm are neither random nor form a regular lattice. Instead we calculate the given function along individual dimensions (modes) and use these values to reconstruct its behaviour in the whole domain. The positions of the calculated univariate fibres are chosen adaptively for the given function. The required evaluations can be executed in parallel along each mode (variable) and over all modes.
To demonstrate the efficiency of the proposed method, we apply it to compute high-dimensional Ising susceptibility integrals, arising from asymptotic expansions for the spontaneous magnetisation in two-dimensional Ising model of ferromagnetism. We observe strong superlinear convergence of the proposed method, while the MC and qMC algorithms converge sublinearly. Using multiple precision arithmetic, we also observe exponential convergence of the proposed algorithm. Combining high-order convergence, almost perfect scalability up to hundreds of processes, and the same flexibility as MC and qMC, the proposed algorithm can be a new method of choice for problems involving high-dimensional integration, e.g. in statistics, probability, and quantum physics
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