2,497 publications from this institution
Antigranulocyte scintigraphy with MoAbs has a sensitivity of 81% and a specificity of 77% in the diagnosis of osteomyelitis.
Umbrella reviews are systematic reviews of all systematic reviews on a given question and can provide a higher-level view of current available evidence on broad research topics. Given the importance and possible consequences of the insights derived from umbrella reviews, it is fundamental to ensure accurate, comprehensive reporting and methodological rigor in these papers. Here, we present the potential and limitations of these evolving evidence synthesis tools by looking at umbrella reviews published on vaccine research. Vaccines are essential tools in modern medicine for preventing disease and promoting public health. The scientific literature on vaccines grows rapidly as researchers work to improve existing vaccines and develop new ones. More than half a million scientific papers on vaccines have already been published, including several thousands of systematic reviews that aim to appraise and summarize this growing literature. However, as the published systematic reviews are only able to cover a small proportion of the literature it is important to also provide higher-level evidence syntheses. and discuss further improvements that could be made to integrate evidence on vaccines.
We studied predictors for losses to follow-up and the impact of such losses in the AIDS Clinical Trials Group 019 protocol, a long-term randomized trial of immediate versus deferred antiretroviral therapy in asymptomatic HIV-1-infected patients with >500 CD4 cells/mm3. The trial was selected because of its key importance in determining guidelines for antiretroviral therapy, and because it had the longest follow-up among all antiretroviral trials and the largest percentage of patients whose vital status was unknown at study end. Younger age, a history of parenteral drug use, and nonwhite race were associated with higher rates of loss to follow-up, but race was not an important predictor after adjusting for clinical site. There was large and statistically significant variability in the rates of losses among different clinical sites (p < 0.001). Patient retention was significantly better in clinical sites that enrolled many participants, with 25% of enrollees lost to follow-up in sites enrolling >100 patients and 44% in sites enrolling <33 patients each. As a group, patients lost to follow-up after the 2nd year had steeper declines of CD4 cell counts, and a significantly larger proportion had reached a CD4 cell count <300/mm3 in the year before being lost, compared with patients remaining in the study. Losses to follow-up probably decreased substantially the observed number of primary endpoints, curtailed the power of the trial to demonstrate any difference between immediate and deferred initiation of antiretroviral therapy, and may have introduced large bias in the estimated hazard ratio for the primary endpoint and its statistical significance.
The authors describe the design of a custom integrated circuit for the arithmetic operation of division. The chip uses self-timing to avoid the need for high-speed clocks and directly concatenates precharged function blocks without latches. Internal stages form a ring that cycles without any external signaling. The self-timed control introduces no serial overhead, making the total chip latency equal just the combinational logic delays of the data elements. The ring's data path uses embedded completion encoding and generates the mantissa of a 54-b (floating-point IEEE double-precision) result. Fabricated in 1.2- mu m CMOS, the ring occupies 7 mm/sup 2/ and generates a quotient and done indication in 45 to 160 ns, depending on the particular data operands.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
We have empirically assessed the distribution of published effect sizes and estimated power by analyzing 26,841 statistical records from 3,801 cognitive neuroscience and psychology papers published recently. The reported median effect size was D = 0.93 (interquartile range: 0.64-1.46) for nominally statistically significant results and D = 0.24 (0.11-0.42) for nonsignificant results. Median power to detect small, medium, and large effects was 0.12, 0.44, and 0.73, reflecting no improvement through the past half-century. This is so because sample sizes have remained small. Assuming similar true effect sizes in both disciplines, power was lower in cognitive neuroscience than in psychology. Journal impact factors negatively correlated with power. Assuming a realistic range of prior probabilities for null hypotheses, false report probability is likely to exceed 50% for the whole literature. In light of our findings, the recently reported low replication success in psychology is realistic, and worse performance may be expected for cognitive neuroscience.
This paper describes a method to perform linear AC analysis on mixed-signal systems which appear strongly nonlinear in the voltage domain but are linear in other variable domains. Common circuits like phase/delay-locked loops and duty-cycle correctors fall into this category, since they are designed to be linear with respect to phases, delays, and duty-cycles of the input and output clocks, respectively. The method uses variable domain translators to change the variables to which the AC perturbation is applied and from which the AC response is measured. By utilizing the efficient periodic AC (PAC) analysis available in commercial RF simulators, the circuit's linear transfer function in the desired variable domain can be characterized without relying on extensive transient simulations. Furthermore, the variable domain translators enable the circuits to be macromodeled as weakly-nonlinear systems in the chosen domain and then converted to voltage-domain models, instead of being modeled as strongly-nonlinear systems directly.
The IP security protocols are sufficiently mature to benefit from multiple independent implementations and worldwide deployment. Towards that goal, we implemented the protocols for the BSD/OS, Linux, OpenBSD and NetBSD. While some differences in the implementations exist due to the differences in the underlying operating system structures, the design philosophy is common. A radix tree, namely the one used by the BSD code for routing purposes, is used to implement the policy engine; a transform table switch is used to make addition of security transformations an easy process; a lightweight kernel-user communication mechanism is used to pass key material and other configuration information from user space to kernel space, and to report asynchronous events such as requests for new keys from the kernel space to a user-level keying daemon; and two distinct ways of intercepting outgoing packets and applying the IPsec transformations to them are employed. The techniques used in our implementations are explained, differences in approaches are analysed, and hints are given to potential future implementers of new transforms.
To make informative public policy decisions in battling the ongoing COVID-19 pandemic, it is important to know the disease prevalence in a population. There are two intertwined difficulties in estimating this prevalence based on testing results from a group of subjects. First, the test is prone to measurement error with unknown sensitivity and specificity. Second, the prevalence tends to be low at the initial stage of the pandemic and we may not be able to determine if a positive test result is a false positive due to the imperfect specificity of the test. The statistical inference based on large sample approximation or conventional bootstrap may not be sufficiently reliable and yield confidence intervals that do not cover the true prevalence at the nominal level. In this paper, we have proposed a set of 95% confidence intervals, whose validity is guaranteed and doesn't depend on the sample size in the unweighted setting. For the weighted setting, the proposed inference is equivalent to a class of hybrid bootstrap methods, whose performance is also more robust to the sample size than those based on asymptotic approximations. The methods are used to reanalyze data from a study investigating the antibody prevalence in Santa Clara county, California, which was the motivating example of this research, in addition to several other seroprevalence studies where authors had tried to correct their estimates for test performance. Extensive simulation studies have been conducted to examine the finite-sample performance of the proposed confidence intervals.