University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

Measurement of proton-proton elastic scattering and total cross-section at \chem{\sqrt {s} = 7\,TeV}

Abstract: At the LHC energy of , under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (?5?beam) in a dedicated run with ?*?=?90?m, |t|-values down to 5?10?3?GeV2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B?=?(19.9???0.3)?GeV?2 over the large |t|-range from 0.005 to 0.2?GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t?=?0. With the luminosity from CMS, the elastic cross-section was determined to be (25.4???1.1)?mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6???2.2)?mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al), EPL, 95 (2011) 41001).

Weakly defective varieties

Abstract: A projective variety X is k-weakly defective' when its intersection with a general (k + 1)-tangent hyperplane has no isolated singularities at the k + 1 points of tangency. If X is k-defective, i.e. if the k-secant variety of X has dimension smaller than expected, then X is also k-weakly defective. The converse does not hold in general. A classification of weakly defective varieties seems to be a basic step in the study of defective varieties of higher dimension. We start this classification here, describing all weakly defective irreducible surfaces. Our method also provides a new proof of the classical Terracini's classification of k-defective surfaces.

Oxytocin enhances processing of positive versus negative emotional information in healthy male volunteers

Abstract: Animal studies have shown the role of oxytocin in affiliation and attachment, and recent evidence suggests that oxytocin is also involved in human models of approach behaviour, possibly by modulating the processing of emotionally valenced stimuli. Although oxytocin administration has been reported to decrease neural responses to facial emotional information, the effects on a wider range of behavioural measures of emotional processing shown to be sensitive to antidepressant manipulation have not been examined. The aim of this study was to investigate whether intranasally administered oxytocin affects the processing of positive and negative affective information in healthy male volunteers across tasks measuring attention, perception and memory. Twenty-nine male healthy volunteers were randomly allocated to receive a single dose of oxytocin nasal spray (24 UI) or placebo. 50 min later, participants completed a battery of psychological tests measuring emotional processing. A single dose of intranasally administered oxytocin slowed reaction time to correctly identify fearful facial expressions and reduced the misclassification of positive emotions as negative ones. These effects occurred in the absence of significant differences in subjective ratings of mood and anxiety. These results suggest that oxytocin modulates emotion processing in healthy male volunteers. This action may contribute to the emerging role of the neuropeptide in promoting affiliative and approach behaviours by reducing the salience of potentially ambiguous and threatening social stimuli.

Modern quantum chemistry with [Open]Molcas

Abstract: MOLCAS/OpenMolcas is an ab initio electronic structure program providing a large set of computational methods from Hartree-Fock and density functional theory to various implementations of multiconfigurational theory. This article provides a comprehensive overview of the main features of the code, specifically reviewing the use of the code in previously reported chemical applications as well as more recent applications including the calculation of magnetic properties from optimized density matrix renormalization group wave functions.