On the false positives and false negatives of the Jacobian Matrix in kinematically redundant parallel mechanisms

The Jacobian matrix is a highly popular tool for the control and performance analysis of closed-loop robots. Its usefulness in parallel mechanisms is certainly apparent, and its application to solve motion planning problems, or other higher level questions, has been seldom queried, or limited to non-redundant systems. In this paper, we discuss the shortcomings of the use of the Jacobian matrix under redundancy, in particular when applied to kinematically redundant parallel architectures with non-serially connected actuators. These architectures have become fairly popular recently as they allow the end-effector to achieve full rotations, which is an impossible task with traditional topologies. The problems with the Jacobian matrix in these novel systems arise from the need to eliminate redundant variables when forming it, resulting in both situations where the Jacobian incorrectly identifies singularities (false positive), and where it fails to identify singularities (false negative). These issues have thus far remained unaddressed in the literature. We highlight these limitations herein by demonstrating several cases using numerical examples of both planar and spatial architectures

Sex differences in eye gaze and symbolic cueing of attention

Observing a face with averted eyes results in a reflexive shift of attention to the gazed-at location. Here we present results that show that this effect is weaker in males than in females (Experiment 1). This result is predicted by the ‘extreme male brain’ theory of autism (Baron-Cohen, 2003), which suggests that males in the normal population should display more autism-like traits than females (e.g., poor joint attention). Indeed, participants′ scores on the Autism-Spectrum Quotient (Baron-Cohen, Wheelwright, Stott, Bolton, & Goodyear, 2001) negatively correlated with cueing magnitude. Furthermore, exogenous orienting did not differ between the sexes in two peripheral cueing experiments (Experiments 2a and 2b). However, a final experiment showed that using non-predictive arrows instead of eyes as a central cue also revealed a large gender difference. This demonstrates that reduced orienting from central cues in males generalizes beyond gaze cues. These results show that while peripheral cueing is equivalent in the male and female brains, the attention systems of the two sexes treat noninformative symbolic cues very differently

Concert recording 2013-05-29

[Track 01]. String quartet no. 14 in D minor D. 810. Allegro ; [Track 02]. Andante ; [Track 03]. Scherzo ; [Track 04]. Presto / Franz Schubert -- [Track 05]. String quartet in G minor op. 10. Anime et tres decide ; [Track 06]. Assez vif et bien rythme ; [Track 07]. Andantino, doucement expressif ; [Track 08]. Tres modere, En animant peu a peu, Tres mouvemente et avec passion / Claude Debussy

Effect of calcium supplements on risk of myocardial infarction and cardiovascular events : meta-analysis

Peer reviewedPublisher PD

On the Role of Dewetting Transitions in Host-Guest Binding Free Energy Calculations.

We use thermodynamic integration (TI) and explicit solvent molecular dynamics (MD) simulation to estimate the absolute free energy of host-guest binding. In the unbound state, water molecules visit all of the internally accessible volume of the host, which is fully hydrated on all sides. Upon binding of an apolar guest, the toroidal host cavity is fully dehydrated; thus, during the intermediate λ stages along the integration, the hydration of the host fluctuates between hydrated and dehydrated states. Estimating free energies by TI can be especially challenging when there is a considerable difference in hydration between the two states of interest. We investigate these aspects using the popular TIP3P and TIP4P water models. TI free energy estimates through MD largely depend on water-related interactions, and water dynamics significantly affect the convergence of binding free energy calculations. Our results indicate that wetting/dewetting transitions play a major role in slowing the convergence of free energy estimation. We employ two alternative approaches-one analytical and the other empirically based on actual MD sampling-to correct for the standard state free energy. This correction is sizable (up to 4 kcal/mol), and the two approaches provide corrections that differ by about 1 kcal/mol. For the system considered here, the TIP4P water model combined with an analytical correction for the standard state free energy provides higher overall accuracy. This observation might be transferable to other systems in which water-related contributions dominate the binding process

Dynamically Responsive Search Result Weblinks

When a general purpose search engine is used to search dynamic databases, outlinks in the search results page simply point to the relevant databases, without specifying the filtering parameters entered as part of the search query. When the user clicks on a search result and is redirected to the target webpage, the user is forced to re-enter filtering parameters that were already provided as part of the search query. This disclosure describes dynamic search result outlinks where user-provided search parameters are used, with user permission, to automatically fill information in the web page pointed to by the outlink. This ensures a better match between information entered by the user during search and information filled into the target web page, enabling the target web page to directly provide matching results, thus enabling greater convenience and fewer errors. Also described are techniques that enable the generation of dynamic descriptions and snippets based on user-specific query parameters for display in the search results

Patient Choice for Older People in English NHS Primary Care: Theory and Practice

In the English National Health Service (NHS), patients are now expected to choose the time and place of treatment and even choose the actual treatment. However, the theory on which patient choice is based and the implementation of patient choice are controversial. There is evidence to indicate that attitudes and abilities to make choices are relatively sophisticated and not as straightforward as policy developments suggest. In addition, and surprisingly, there is little research on whethermaking individual choices about care is regarded as a priority by the largest NHS patient group and the single largest group for most GPs—older people.This conceptual paper examines the theory of patient choice concerning accessing and engaging with healthcare provision and reviews existing evidence on older people and patient choice in primary care

Low radiation dose calcium scoring: evidence and techniques

Coronary computed tomography (CT) allows for the acquisition of thin slices of the heart and coronary arteries, which can be used to detect and quantify coronary artery calcium (CAC), a marker of atherosclerotic cardiovascular disease. Despite the proven clinical value in cardiac risk prognostication, there remain concerns regarding radiation exposure from CAC CT scans. There have been several recent technical advancements that allow for significant radiation dose reduction in CAC scoring. This paper reviews the clinical utility and recent literature in low radiation dose CAC scoring