A homoleptic phosphine adduct of Tl(I)

A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized

Administering Cognitive Tests Through Touch Screen Tablet Devices: Potential Issues

Mobile technologies, such as tablet devices, open up new possibilities for health-related diagnosis, monitoring, and intervention for older adults and healthcare practitioners. Current evaluations of cognitive integrity typically occur within clinical settings, such as memory clinics, using pen and paper or computer-based tests. In the present study, we investigate the challenges associated with transferring such tests to touch-based, mobile technology platforms from an older adult perspective. Problems may include individual variability in technical familiarity and acceptance; various factors influencing usability; acceptability; response characteristics and thus validity per se of a given test. For the results of mobile technology-based tests of reaction time to be valid and related to disease status rather than extraneous variables, it is imperative the whole test process is investigated in order to determine potential effects before the test is fully developed. Researchers have emphasized the importance of including the ‘user’ in the evaluation of such devices; thus we performed a focus group-based qualitative assessment of the processes involved in the administration and performance of a tablet-based version of a typical test of attention and information processing speed (a multi-item localization task), to younger and older adults. We report that although the test was regarded positively, indicating that using a tablet for the delivery of such tests is feasible, it is important for developers to consider factors surrounding user expectations, performance feedback, and physical response requirements and to use this information to inform further research into such applications

Nuclear Matrix Elements of Axial-Charge Exchange Currents Derived in Heavy-Fermion Chiral Perturbation Theory

We calculate shell-model matrix elements of the axial-charge exchange current operators that have been obtained up to the next-to-leading order from heavy-fermion chiral perturbation theory. It is found that loop corrections to the soft one-pion-exchange contribution are small (around 10 \%) and have no significant dependence on the nuclear mass number or on the valence-nucleon orbits. These results render further support to the chiral-filtering conjecture.Comment: 19 pages, LaTeX, SNUTP 94-29, USC(NT)-94-

Cosmic cookery : making a stereoscopic 3D animated movie.

This paper describes our experience making a short stereoscopic movie visualizing the development of structure in the universe during the 13.7 billion years from the Big Bang to the present day. Aimed at a general audience for the Royal Society's 2005 Summer Science Exhibition, the movie illustrates how the latest cosmological theories based on dark matter and dark energy are capable of producing structures as complex as spiral galaxies and allows the viewer to directly compare observations from the real universe with theoretical results. 3D is an inherent feature of the cosmology data sets and stereoscopic visualization provides a natural way to present the images to the viewer, in addition to allowing researchers to visualize these vast, complex data sets. The presentation of the movie used passive, linearly polarized projection onto a 2m wide screen but it was also required to playback on a Sharp RD3D display and in anaglyph projection at venues without dedicated stereoscopic display equipment. Additionally lenticular prints were made from key images in the movie. We discuss the following technical challenges during the stereoscopic production process; 1) Controlling the depth presentation, 2) Editing the stereoscopic sequences, 3) Generating compressed movies in display speci¯c formats. We conclude that the generation of high quality stereoscopic movie content using desktop tools and equipment is feasible. This does require careful quality control and manual intervention but we believe these overheads are worthwhile when presenting inherently 3D data as the result is signi¯cantly increased impact and better understanding of complex 3D scenes

The test case of HD26965: difficulties disentangling weak Doppler signals from stellar activity

We report the discovery of a radial velocity signal that can be interpreted as a planetary-mass candidate orbiting the K dwarf HD26965, with an orbital period of 42.364$\pm$0.015 days, or alternatively, as the presence of residual, uncorrected rotational activity in the data. Observations include data from HIRES, PFS, CHIRON, and HARPS, where 1,111 measurements were made over 16 years. Our best solution for HD26965 $b$ is consistent with a super-Earth that has a minimum mass of 6.92$\pm$0.79 M$_{\oplus}$ orbiting at a distance of 0.215$\pm$0.008 AU from its host star. We have analyzed the correlation between spectral activity indicators and the radial velocities from each instrument, showing moderate correlations that we include in our model. From this analysis, we recover a $\sim$38 day signal, which matches some literature values of the stellar rotation period. However, from independent Mt. Wilson HK data for this star, we find evidence for a significant 42 day signal after subtraction of longer period magnetic cycles, casting doubt on the planetary hypothesis for this period. Although our statistical model strongly suggests that the 42-day signal is Doppler in origin, we conclude that the residual effects of stellar rotation are difficult to fully model and remove from this dataset, highlighting the difficulties to disentangle small planetary signals and photospheric noise, particularly when the orbital periods are close to the rotation period of the star. This study serves as an excellent test case for future works that aim to detect small planets orbiting `Sun-like' stars using radial velocity measurements.Comment: 16 pages, 10 figures, 13 tables, accepted for publication in A

LHS6343C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission

We report the discovery of a brown dwarf that transits one member of the M+M binary system LHS6343AB every 12.71 days. The transits were discovered using photometric data from the Kelper public data release. The LHS6343 stellar system was previously identified as a single high-proper-motion M dwarf. We use high-contrast imaging to resolve the system into two low-mass stars with masses 0.45 Msun and 0.36 Msun, respectively, and a projected separation of 55 arcsec. High-resolution spectroscopy shows that the more massive component undergoes Doppler variations consistent with Keplerian motion, with a period equal to the transit period and an amplitude consistent with a companion mass of M_C = 62.8 +/- 2.3 Mjup. Based on an analysis of the Kepler light curve we estimate the radius of the companion to be R_C = 0.832 +/- 0.021 Rjup, which is consistent with theoretical predictions of the radius of a > 1 Gyr brown dwarf.Comment: Our previous analysis neglected the dependence of the scaled semimajor axis, a/R, on the transit depth. By not correcting a/R for the third-light contamination, we overestimated the mass of Star A, which led to an overestimate the mass and radius of the LHS6343

Sexual functioning in 4,418 postmenopausal women participating in UKCTOCS: a qualitative free-text analysis

Objective: Sexual well-being can contribute significantly to the overall quality of women's lives. This qualitative study aimed to examine sexual activity, functioning, and satisfaction in a large sample of postmenopausal women from the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) Methods: Thematic analysis was used to evaluate the free-text data of the Fallowfield Sexual Activity Questionnaire (FSAQ) completed by UKCTOCS participants at baseline before annual screening. Results: A total of 24,305 women completed the baseline FSAQ and 4,525 (19%) provided free-text data, with 4,418 comments eligible for analysis. Median age was 64 years; 65% had a partner and 22.5% were sexually active. Four interrelated themes were derived: partner availability, physical and sexual health, mental well-being, and interpersonal relationships. Primary reason for absence of sexual activity was lack of a partner, mainly due to widowhood (n = 1,000). Women discussed how partner's medical condition (27%) or sexual dysfunction (13.5%), their own physical health (18%) or menopause-related symptoms (12.5%), and prescribed medication (7%) affected sexual activity. Impact of low libido in self (16%) or partner (7%), relationship problems (10.5%) or logistics (6%), and perceptions of ageing (9%) were also mentioned. Few (3%) referred to positive sexual experiences or had sought medical help for sexual problems (6%). Conclusions: This qualitative analysis explored postmenopausal women's perspective on their sexual functioning. Having an intimate partner and good physical health are key factors for continuation of sexual activity and satisfaction. Further sexual education for healthcare professionals is needed to raise awareness about sexuality and sexual difficulties in later life

Nucleation, Growth And Transformations In Dna Linked Colloidal Assemblies

The use of short, synthetic DNA strands to mediate self-assembly of a collection of colloidal particles into ordered structures is now quite well established experimentally. However, it is increasingly apparent that DNA-linked colloidal assemblies (DLCA) are subject to many of the processing challenges relevant to atomic materials, including kinetic barriers related to nucleation and growth, defect formation, and even diffusionless transformations between different crystal symmetries. Understanding, and ultimately controlling, these phenomena will be required to truly utilize this technology to make new materials. Here, I describe a series of computational studies—based on a complementary suite of tools that includes Brownian dynamics, free energy calculations, vibrational mode theory, and hydrodynamic drag analysis—that address several issues related to the nucleation, growth, and stability of DNA-linked colloidal assemblies. The primary focus is on understanding the nature of the apparently enormous number of diffusionless solid-solid phase transformations that occur in crystallites assembled from DNA-functionalized colloidal particles. We find that the ubiquitous nature of these transformations is largely due to the short-ranged nature of DNA mediated interactions, which produces a panoply of zero-energy barrier pathways (or zero frequency vibrational modes) in a number of crystalline configurations. Furthermore, it is shown that hydrodynamic drag forces play a key role in biasing the transformations towards specific pathways, leading to unexpected order in the final arrangements. Additional studies also highlight how heterogeneity in the surface density of DNA strands grafted onto the particles may be used to improve nucleation and growth behavior, which is generally difficult in systems near the ‘sticky-sphere’ limit in which the interaction range is short relative to the particle size. In the final chapter of the thesis, a general and powerful technique is presented for extracting particle-particle interactions directly from particle trajectory data