Improvements in X-Ray Spectrometry for Planetary Surface Exploration

Recent innovations in X-ray instrumentation have enabled a new generation of planetary XRS instruments exhibiting performance matching terr estrial laboratory results

‘It's all the way you look at it, you know’: reading Bill ‘Bojangles’ Robinson's film career

This paper engages with a major paradox in African American tap dancer Bill ‘Bojangles’ Robinson's film image – namely, its concurrent adherences to and contestations of dehumanising racial iconography – to reveal the complex and often ambivalent ways in which identity is staged and enacted. Although Robinson is often understood as an embodiment of popular cultural imagery historically designed to dehumanise African Americans, this paper shows that Robinson's artistry displaces these readings by providing viewing pleasure for black, as much as white, audiences. Robinson's racially segregated scenes in Dixiana (1930) and Hooray for Love (1935) illuminate classical Hollywood's racial codes, whilst also showing how his inclusion within these otherwise all-white films provides grounding for creative and self-reflexive artistry. The films' references to Robinson's stage image and artistry overlap with minstrelsy-derived constructions of ‘blackness’, with the effect that they heighten possible interpretations of his cinematic persona by evading representational conclusion. Ultimately, Robinson's films should be read as sites of representational struggle that help to uncover the slipperiness of performances of African American identities in 1930s Hollywood

Association of fenofibrate therapy with long-term cardiovascular risk in statin-treated patients with type 2 diabetes

IMPORTANCE: Patients with type 2 diabetes are at high risk of cardiovascular disease (CVD) in part owing to hypertriglyceridemia and low high-density lipoprotein cholesterol. It is unknown whether adding triglyceride-lowering treatment to statin reduces this risk. OBJECTIVE: To determine whether fenofibrate reduces CVD risk in statin-treated patients with type 2 diabetes. DESIGN, SETTING, AND PARTICIPANTS: Posttrial follow-up of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Lipid Study between July 2009 and October 2014; 5 years of follow-up were completed for a total of 9.7 years at general community and academic outpatient research clinics in the United States and Canada. Of the original 5518 ACCORD Lipid Trial participants, 4644 surviving participants were selected based on the presence of type 2 diabetes and either prevalent CVD or CVD risk factors and high-density lipoprotein levels less than 50 mg/dL (<55 mg/dL for women and African American individuals). INTERVENTIONS: Passive follow-up of study participants previously treated with fenofibrate or masked placebo. MAIN OUTCOMES AND MEASURES: Occurrence of cardiovascular outcomes including primary composite outcome of fatal and nonfatal myocardial infarction and stroke in all participants and in prespecified subgroups. RESULTS: The 4644 follow-on study participants were broadly representative of the original ACCORD study population and included significant numbers of women (n = 1445; 31%), nonwhite individuals (n = 1094; 21%), and those with preexisting cardiovascular events (n = 1620; 35%). Only 4.3% of study participants continued treatment with fenofibrate following completion of ACCORD. High-density lipoprotein and triglyceride values rapidly equalized among participants originally randomized to fenofibrate or placebo. Over a median total postrandomization follow-up of 9.7 years, the hazard ratio (HR) for the primary study outcome among participants originally randomized to fenofibrate vs placebo (HR, 0.93; 95% CI, 0.83-1.05; P = .25) was comparable with that originally observed in ACCORD (HR, 0.92; 95% CI, 0.79-1,08; P = .32). Despite these overall neutral results, we continued to find evidence that fenofibrate therapy effectively reduced CVD in study participants with dyslipidemia, defined as triglyceride levels greater than 204 mg/dL and high-density lipoprotein cholesterol levels less than 34 mg/dL (HR, 0.73; 95% CI, 0.56-0.95). CONCLUSIONS AND RELEVANCE: Extended follow-up of ACCORD-lipid trial participants confirms the original neutral effect of fenofibrate in the overall study cohort. The continued observation of heterogeneity of treatment response by baseline lipids suggests that fenofibrate therapy may reduce CVD in patients with diabetes with hypertriglyceridemia and low high-density lipoprotein cholesterol. A definitive trial of fibrate therapy in this patient population is needed to confirm these findings. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000620

Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

Exafs studies and simulations of local anisotropy in Co-Cr films

Extended x-ray absorption fine structure measurements of a Co78Cr22 film were performed using normal and glancing incident radiation in order to investigate, respectively, the in-plane and out-of-plane local structure and chemistry. The Fourier transformed EXAFS data of the in-plane and out-of-plane structures around the Co and Cr atoms illustrates the presence of an anisotropy. Analysis of the local environments around Co for the two sample orientations indicates the presence of Co-enriched clusters, while similar studies of the Cr environments indicate preferential ordering parallel to the film plane. Quantitative analysis of the higher order Fourier transform peaks shows a greater amount of disorder perpendicular to the film plane beyond that expected for a textured hcp film. These results are consistent with earlier reports of a high density of stacking faults or twinning planes perpendicular to the growth axis, supporting the interpretation that a platelet-like texturing exists within the columnar microstructure

Deconvolution of Transition Metal LIII/LII-Edge EXAFS and Magnetic EXAFS (MEXAFS) Data

We describe the use of an iterative Van Cittert deconvolution approach to isolate the LUI-edge from the LII-edge EXAFS and MEXAFS signals for the 3d transition metals. The deconvoluted LIII-edge EXAFS data is in agreement with theoretically generated LIII-edge data, thus demonstrating the validity of this approach. Results from the deconvolution of the MEXAFS data also qualitatively agree with previously published MEXAFS data on the same elements at the K-edge

Determination of Site Specific Binding Environments of Surface Sorbed Cesium on Clay Minerals by Cs-EXAFS

Transport behavior of 137Cs in the environment is regulated by surface sorption reactions on clay mineral surfaces. To provide greater understanding of Cs transport processes, XAFS investigations of the local environments of 133Cs sorbed to clay minerals were conducted on Cs-Ca exchanged clay suspensions at the Cs LIII-edge. With decreased surface loadings of Cs, the Cs local environment exhibited increased long range order beyond 6 Å. Identification of Cs in expanded, semi-collapsed and collapsed interlayer environments was determined by correlating radial distances and Fourier transform peak amplitudes representing Cs-O and Cs-Al/Si in the octahedral and tetrahedral layers. Despite the difficulties of analyzing XAFS data of adsorbed atoms in multiple environments, isolation of Cs in more specific sites by selective exchange should allow detailed analysis and identification of predominant binding environments of cations to clay surfaces