Chirality in Bare and Passivated Gold Nanoclusters

Chiral structures have been found as the lowest-energy isomers of bare (Au$_{28}$ and Au$_{55}) and thiol-passivated (Au$_{28}(SCH$_{3})$_{16}$and Au$_{38}(SCH_{3})_{24}) gold nanoclusters. The degree of chirality existing in the chiral clusters was calculated using the Hausdorff chirality measure. We found that the index of chirality is higher in the passivated clusters and decreases with the cluster size. These results are consistent with the observed chiroptical activity recently reported for glutahione-passivated gold nanoclusters, and provide theoretical support for the existence of chirality in these novel compounds.Comment: 5 pages, 1 figure. Submitted to PR

Astrometry with "Carte du Ciel" plates, San Fernando zone. I. Digitization and measurement using a flatbed scanner

We present an original method of digitizing and astrometrically reducing "Carte du Ciel" plate material using an inexpensive flatbed scanner, to demonstrate that for this material there is an alternative to more specialized measuring machines that are very few in number and thus not readily available. The sample of plates chosen to develop this method are original "Carte du Ciel" plates of the San Fernando zone, photographic material with a mean epoch 1903.6, and a limiting photographic magnitude ~14.5, covering the declination range of -10 < dec < -2. Digitization has been made using a commercial flatbed scanner, demonstrating the internal precision that can be attained with such a device. A variety of post-scan corrections are shown to be necessary. In particular, the large distortion introduced by the non-uniform action of the scanner is modelled using multiple scans of each plate. We also tackle the specific problems associated with the triple-exposure images on some plates and the grid lines present on all. The final measures are reduced to celestial coordinates using the Tycho-2 Catalogue. The internal precision obtained over a single plate, 3microns ~ 0.18" in each axis, is comparable to what is realized with similar plate material using slower, less affordable, and less widely available conventional measuring machines, such as a PDS microdensitometer. The accuracy attained over large multi-plate areas, employing an overlapping plate technique, is estimated at 0.2".Comment: 16 pages, 19 figures and 3 tables. Accepted for publication in A&

Anti-aging therapy through fitness enhancement

Physical exercise is proposed as a highly effective means of treating and preventing the main causes of morbidity and mortality – most of which are associated with aging – in industrialized countries. Low physical fitness is an important risk factor for cardiovascular and all-causes morbidity and mortality; indeed, it is even a predictor of these problems. When properly measured, the assessment of physical fitness can be a highly valuable indicator of health and life expectancy and, therefore, should be performed routinely in the clinical setting. Individually adapted training programs could be prescribed based on fitness assessment results and an adequate knowledge of patient lifestyle and daily physical activity. Such training programs would allow people to develop their maximum physical potential, improve their physical and mental health, and attenuate the negative consequences of aging

Casein genetic variants in ovine Merino breed

The genetic polymorphism on Merina ewe milk was investigated, using polyacrylamide gel electrophoresis at pH 8.6 and ultra thin-layer isoelectric focusing techniques, according to Krause et al. (1988), and Chianese et al. (1992). The casein fractions identified were: - Seven as1-casein phenotypes: CC, BB, BC, AB, AC, BD and CD (Chianese et al.,1996). - Three as2-casein phenotypes, provisionally nominated F, S, and I. - Three b-casein phenotypes, also provisionally nominated K, L and M, because their genetic segregation is not well known yet. The phenotypical distribution of the observed casein fractions and their adjustment to a normal distribution is presented.El polimorfismo genético de la leche de oveja Merina fue investigado mediante electroforesis en gel de poliacrilamida a pH 8,6 (PAGE) e isoelectroenfoque en gel ultrafino (UTLIEF), siguiendo las técnicas descritas por Krause et al. (1988) y Chianese et al. (1992). Dentro de las fracciones caseínicas se identificaron siete fenotipos de as1-caseína (CC, BB, BC, AB, AC, BD y CD), según la nomenclatura establecida por Chianese et al. (1996). Mientras que, a nivel de as2- y b-caseína se han observado tres perfiles electroforéticos, denominados provisionalmente F, S e I; K, L y M respectivamente, ya que no se conoce su segregación genética. Se presenta la distribución fenotípica de las fracciones caseínicas estudiadas, así como su ajuste a la distribución normal

Sensitivity and specificity of four screening tests sleep-disordered breathing in patients with and without cardiovascular disease

Objectives: Polysomnogram is the gold standard for the diagnosis of sleep-disordered breathing (SDB); a sensitive and specific alternative strategy would be ideal, due to its low availability, and screening patients at high risk of OSA is very important. This study aimed to determine the operating characteristics of screening tests in patients with and without cardiovascular disease (CVD). Material and Methods: Epworth sleepiness scale (ESS), Berlin, STOP-bang and Pittsburgh sleep quality index (PSQI) were applied in adults with and without cardiovascular disease in three Colombian cities, as well as anthropometric measurements and a polysomnogram. Operating characteristics were calculated for each test and the best cut-off values in patients with and without CVD were obtained. Results: 964 patients (median age: 58), 662 with and 302 without CVD were included. The prevalence for SDB (AHI ≥5) were 43.4 % (OSA), 16.2% (central apnea), and 12.4 % (other). In patients without CVD, the highest sensitivity for OSA and central apnea was for PSQI (80-85%). The highest specificity was for STOP-bang (68%) and Berlin (78.6%). In CVD the best sensitivity was for PSQI (81.9%) followed by Berlin (71.9%) and the best specificity for STOP-bang (82.1%). No isolated questionnaire showed good diagnostic performance (AUC≤0.6) and the cut-off values had no variations except for ESS. Conclusion: Screening tests showed low operating characteristics for the diagnosis to SDB, but better performance in patients with CVD. They are not recommended as the only diagnostic test, but they can be useful to guide the initial diagnostic processQ2Objectives: Polysomnogram is the gold standard for the diagnosis of sleep-disordered breathing (SDB); a sensitive and specific alternative strategy would be ideal, due to its low availability, and screening patients at high risk of OSA is very important. This study aimed to determine the operating characteristics of screening tests in patients with and without cardiovascular disease (CVD). Material and Methods: Epworth sleepiness scale (ESS), Berlin, STOP-bang and Pittsburgh sleep quality index (PSQI) were applied in adults with and without cardiovascular disease in three Colombian cities, as well as anthropometric measurements and a polysomnogram. Operating characteristics were calculated for each test and the best cut-off values in patients with and without CVD were obtained. Results: 964 patients (median age: 58), 662 with and 302 without CVD were included. The prevalence for SDB (AHI ≥5) were 43.4 % (OSA), 16.2% (central apnea), and 12.4 % (other). In patients without CVD, the highest sensitivity for OSA and central apnea was for PSQI (80-85%). The highest specificity was for STOP-bang (68%) and Berlin (78.6%). In CVD the best sensitivity was for PSQI (81.9%) followed by Berlin (71.9%) and the best specificity for STOP-bang (82.1%). No isolated questionnaire showed good diagnostic performance (AUC≤0.6) and the cut-off values had no variations except for ESS. Conclusion: Screening tests showed low operating characteristics for the diagnosis to SDB, but better performance in patients with CVD. They are not recommended as the only diagnostic test, but they can be useful to guide the initial diagnostic processN/

Structural and energetic properties of nickel clusters: 2≤N≤1502 \le N \le 150

The four most stable structures of Ni$_N$ clusters with $N$ from 2 to 150 have been determined using a combination of the embedded-atom method in the version of Daw, Baskes and Foiles, the {\it variable metric/quasi-Newton} method, and our own {\it Aufbau/Abbau} method. A systematic study of energetics, structure, growth, and stability of also larger clusters has been carried through without more or less severe assumptions on the initial geometries in the structure optimization, on the symmetry, or on bond lengths. It is shown that cluster growth is predominantly icosahedral with $islands$ of {\it fcc}, {\it tetrahedral} and {\it decahedral} growth. For the first time in unbiased computations it is found that Ni$_{147}$ is the multilayer (third Mackay) icosahedron. Further, we point to an enhanced ability of {\it fcc} clusters to compete with the icosahedral and decahedral structures in the vicinity of N=79. In addition, it is shown that conversion from the {\it hcp}/anti-Mackay kind of icosahedral growth to the {\it fcc}/Mackay one occurs within a transition layer including several cluster sizes. Moreover, we present and apply different analytical tools in studying structural and energetic properties of such a large class of clusters. These include means for identifying the overall shape, the occurrence of atomic shells, the similarity of the clusters with, e.g., fragments of the {\it fcc} crystal or of a large icosahedral cluster, and a way of analysing whether the $N$-atom cluster can be considered constructed from the $(N-1)$-atom one by adding an extra atom. In addition, we compare in detail with results from chemical-probe experiment. Maybe the most central result is that first for clusters with $N$ above 80 general trends can be identified.Comment: 37 pages, 11 figure