Derek Denny-brown: O Homem Por Detrás Dos Gânglios

The authors present an historical review about the main contributions of Professor Derek Denny-Brown to neurology. Some of his achievements include the first description of sensory neuronopathies, and some of the essential textbooks on the function and anatomy of the basal ganglia. In 2016, on the 35th anniversary of his death, modern neurologists are still strongly influenced by his legacy. © 2017, Associacao Arquivos de Neuro-Psiquiatria. All rights reserved.75212712

Ab Initio Molecular Dynamics Simulation of Liquid Ga_xAs_{1-x} Alloys

We report the results of ab initio molecular dynamics simulations of liquid Ga_xAs_{1-x} alloys at five different concentrations, at a temperature of 1600 K, just above the melting point of GaAs. The liquid is predicted to be metallic at all concentrations between x = 0.2 and x = 0.8, with a weak resistivity maximum near x = 0.5, consistent with the Faber-Ziman expression. The electronic density of states is finite at the Fermi energy for all concentrations; there is, however, a significant pseudogap especially in the As-rich samples. The Ga-rich density of states more closely resembles that of a free-electron metal. The partial structure factors show only a weak indication of chemical short-range order. There is also some residue of the covalent bonding found in the solid, which shows up in the bond-angle distribution functions of the liquid state. Finally, the atomic diffusion coefficients at 1600K are calculated to be 2.1 \times 10^{-4} cm^2/sec for Ga ions in Ga_{0.8}As_{0.2} and 1.7 \times 10^{-4} cm^2/sec for As ions in Ga_{0.2}As_{0.8}.Comment: 29 pages, 10 eps figures, accepted for publication in Phys. Rev.

Performance of the 4-Level Pulmonary Embolism Clinical Probability Score (4PEPS) in the diagnostic management of pulmonary embolism:An external validation study

Background: The recently published 4-level Pulmonary Embolism Clinical Probability Score (4PEPS) integrates different aspects from currently available diagnostic strategies to further reduce imaging testing in patients with clinically suspected pulmonary embolism (PE). Aim: To externally validate the performance of 4PEPS in an independent cohort. Methods: In this post-hoc analysis of the prospective diagnostic management YEARS study, the primary outcome measures were discrimination, calibration, efficiency (proportion of imaging tests potentially avoided), and failure rate (venous thromboembolism (VTE) diagnosis at baseline or follow-up in patients with a negative 4PEPS algorithm). Multiple imputation was used for missing 4PEPS items. Based on 4PEPS, PE was considered ruled out in patients with a very low clinical pre-test probability (CPTP) without D-dimer testing, in patients with a low CPTP and D-dimer &lt;1000 μg/L, and in patients with a moderate CPP and D-dimer below the age-adjusted threshold. Results: Of the 3465 patients, 474 (14 %) were diagnosed with VTE at baseline or during 3-month follow-up. Discriminatory performance of the 4PEPS items was good (area under ROC-curve, 0.82; 95%CI, 0.80–0.84) as was calibration. Based on 4PEPS, PE could be considered ruled out without imaging in 58 % (95%CI 57–60) of patients (efficiency), for an overall failure rate of 1.3 % (95%CI 0.86–1.9). Conclusion: In this retrospective external validation, 4PEPS appeared to safely rule out PE with a high efficiency. Nevertheless, although not exceeding the failure rate margin by ISTH standards, the observed failure rate in our analysis appeared to be higher than in the original 4PEPS derivation and validation study. This highlights the importance of a prospective outcome study.</p

DXA-derived hip shape is related to osteoarthritis:findings from in the MrOS cohort

BF conducted this research whilst on a clinical research primer fellowship awarded by the Elizabeth Blackwell Institute, University of Bristol, UK. This study was funded by Arthritis Research UK project grant ref 20244. CG is funded by Arthritis Research UK grant ref 20000. The Osteoporotic Fractures in Men (MrOS) Study is supported by National Institutes of Health funding. The following institutes provide support: the National Institute on Aging (NIA), the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), the National Center for Advancing Translational Sciences (NCATS), and NIH Roadmap for Medical Research under the following grant numbers: R01 AR052000, K24 AR048841, U01 AG027810, U01 AG042124, U01 AG042139, U01 AG042140, U01 AG042143, U01 AG042145, U01 AG042168, U01 AR066160, and UL1 TR000128.Peer reviewedPostprin

Observational Constraints on Chaplygin Quartessence: Background Results

We derive the constraints set by several experiments on the quartessence Chaplygin model (QCM). In this scenario, a single fluid component drives the Universe from a nonrelativistic matter-dominated phase to an accelerated expansion phase behaving, first, like dark matter and in a more recent epoch like dark energy. We consider current data from SNIa experiments, statistics of gravitational lensing, FR IIb radio galaxies, and x-ray gas mass fraction in galaxy clusters. We investigate the constraints from this data set on flat Chaplygin quartessence cosmologies. The observables considered here are dependent essentially on the background geometry, and not on the specific form of the QCM fluctuations. We obtain the confidence region on the two parameters of the model from a combined analysis of all the above tests. We find that the best-fit occurs close to the $\Lambda$CDM limit ($\alpha=0$). The standard Chaplygin quartessence ($\alpha=1$) is also allowed by the data, but only at the $\sim2\sigma$ level.Comment: Replaced to match the published version, references update

HI in the Outskirts of Nearby Galaxies

The HI in disk galaxies frequently extends beyond the optical image, and can trace the dark matter there. I briefly highlight the history of high spatial resolution HI imaging, the contribution it made to the dark matter problem, and the current tension between several dynamical methods to break the disk-halo degeneracy. I then turn to the flaring problem, which could in principle probe the shape of the dark halo. Instead, however, a lot of attention is now devoted to understanding the role of gas accretion via galactic fountains. The current $\rm \Lambda$ cold dark matter theory has problems on galactic scales, such as the core-cusp problem, which can be addressed with HI observations of dwarf galaxies. For a similar range in rotation velocities, galaxies of type Sd have thin disks, while those of type Im are much thicker. After a few comments on modified Newtonian dynamics and on irregular galaxies, I close with statistics on the HI extent of galaxies.Comment: 38 pages, 17 figures, invited review, book chapter in "Outskirts of Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and Space Science Library, Springer, in pres

Standard addition method based on four-way PARAFAC decomposition to solve the matrix interferences in the determination of carbamate pesticides in lettuce using excitation–emission fluorescence data

The simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of PARAFAC decomposition and excitation–emission fluorescence matrices. A standard addition method for a calibration based on four-way data was applied using different dilutions of the extract from iceberg lettuce as a fourth way that provided the enough variation of the matrix to carry out the four-way analysis. A high fluorescent overlapping existed between the three analytes and the fluorophores of the matrix. The identification of two fluorescent matrix constituents through the four-way model enabled to know the matrix contribution in each dilution of the extract. This contribution was subtracted from the previous signals and a subsequent three-way analysis was carried out with the tensors corresponding to each dilution. The PARAFAC decomposition of these resulting tensors showed a CORCONDIA index equal to 99%. For the identification of the analytes, the correlation between the PARAFAC spectral loadings and the reference spectra has been used. The trueness of the method, in the concentration range studied, was guaranteed because there was neither constant nor proportional bias according to the appropriate hypothesis tests. The best recovery percentages were obtained with the data from the most diluted extract, being the results: 127.6% for carbaryl, 125.55% for carbendazim and 87.6% for 1-naphthol. When the solvent calibration was performed, the decision limit (CCα) and the capability of detection (CCβ) values, in x0=0, were 2.21 and 4.38 μg L−1 for carbaryl, 4.87 and 9.64 μg L−1 for carbendazim; and 3.22 and 6.38 μg L−1 for 1-naphthol, respectively, for probabilities of false positive and false negative fixed at 0.05. However, these values were 5.30 and 10.49 μg L−1 for carbaryl, 18.05 and 35.73 μg L−1 for carbendazim; and 1.92 and 3.79 μg L−1 for 1-naphthol, respectively, when the matrix-matched calibration using the most diluted extract was carried out in the recovery study.Ministerio de Economía y Competitividad(CTQ2011-26022) and JuntadeCastillayLeón(BU108A11-2)