18,802 research outputs found
The spin structure of the proton at low and low in two-dimensional bins from COMPASS
The longitudinal double spin asymmetries and the spin dependent
structure function of the proton were extracted from COMPASS data in
the region of low Bjorken scaling variable and low photon virtuality .
The data were taken in 2007 and 2011 from scattering of polarised muons off
polarised protons, resulting in a sample that is 150 times larger than the one
from the previous experiment SMC that pioneered studies in this kinematic
region.
For the first time, and were evaluated in this region in
two-dimensional bins of kinematic variables: , ,
and . The following kinematic region was investigated: , ~(GeV/)~(GeV/) and
~GeV~GeV. The obtained results were confronted with theoretical
models.Comment: 5 pages, 3 figures, DIS 2016 Conference Proceedings, to appear in the
proceedings of the XXIV International Workshop on Deep-Inelastic Scattering
and Related Subjects, DESY Hamburg, Germany, April 11-15, 201
Longitudinal double spin asymmetry and spin-dependent structure function of the proton at low and low from COMPASS
The COMPASS experiment at CERN has collected a large sample of events of
inelastic scattering of longitudinally polarised muons off longitudinally
polarised protons in the non-perturbative region (four-momentum transfer
squared GeV/), with a Bjorken scaling variable in the range
. The data set is two orders of magnitude
larger than the similar sample collected by the SMC experiment. These data
complement our data for polarised deuterons. They allow the accurate
determination of the longitudinal double spin asymmetry and of the
spin-dependent structure function of the proton in the region of low
and low . The preliminary results of the analysis of these data yield
non zero and positive asymmetries and of the structure function . This
is the first time that spin effects are observed at such low .Comment: 4 pages, 6 figures, DSPIN-13 Conference Proceedings, to appear in the
proceedings of the XV Workshop on High Energy Spin Physics, Dubna, Russia,
October 8-12, 201
Information systems evaluation methodologies
Due to the prevalent use of Information Systems (IS) in modern organisations nowadays, evaluation research in this field is becoming more and more important. In light of this, a set of rigorous methodologies were developed and used by IS researchers and practitioners to evaluate the increasingly complex IS implementation used. Moreover, different types of IS and different focusing perspectives of the evaluation require the selection and use of different evaluation approaches and methodologies. This paper aims to identify, explore, investigate and discuss the various key methodologies that can be used in IS evaluation from different perspectives, namely in nature (e.g. summative vs. formative evaluation) and in strategy (e.g. goal-based, goal-free and criteria-based evaluation). The paper concludes that evaluation methodologies should be selected depending on the nature of the IS and the specific goals and objectives of the evaluation. Nonetheless, it is also proposed that formative criteria-based evaluation and summative criteria-based evaluation are currently among the most and more widely used in IS research. The authors suggest that the combines used of one or more of these approaches can be applied at different stages of the IS life cycle in order to generate more rigorous and reliable evaluation outcomes
Energy and volume of vector fields on spherical domains
We present in this paper a \boundary version" for theorems about minimality
of volume and energy functionals on a spherical domain of threedimensional
Euclidean sphere
Cerebral and cardiovascular effects of analgesic doses of ketamine during a target controlled general anesthesia: a prospective randomized study
Introduction: Ketamine is increasingly being used in various pain settings. The purpose of this study was to
assess the effect of an analgesic dose of ketamine in the bispectral index (BIS), spectral edge frequency (SEF-95), density spectral array (DSA), cerebral oximetry (rSO2) and mean arterial pressure (MAP) during general
anaesthesia with a target controlled infusion.
Methods: A prospective, single-blinded and randomized study on adult patients scheduled for elective spine
surgery was carried out. After anaesthesia induction with propofol, remifentanil and rocuronium, when a stable BIS
value (45-55) was achieved, an automatic recording of BIS, SEF-95, rSO2 and MAP values during 9 min was
performed to establish patients baseline values. Subsequently, patients were randomly assigned to receive a
ketamine bolus dose of 0.2 mg/kg, 0.5 mg/kg or 1 mg/kg; all variables were recorded for additional 9 min after the
ketamine bolus, in the absence of any surgical stimulus. A p-value <0.05 was considered significant in the statistical
analysis.
Results and discussion: Thirty-nine patients were enrolled in the study. Our results show a dose-related
increase of SEF-95 and BIS values. DSA demonstrate a shift in the frequency range and power distribution towards
higher frequencies. Our results do not show significant differences in MAP and rSO2 values.
Conclusion: When ketamine is used intraoperatively in analgesic doses, the anaesthetist should anticipate an
increase in SEF-95 and BIS values which will not be associated with the level of anaesthesia.info:eu-repo/semantics/publishedVersio
A Review on the Cosmology of the de Sitter Horndeski Models
We review the most general scalar-tensor cosmological models with up to
second-order derivatives in the field equations that have a fixed spatially
flat de Sitter critical point independent of the material content or vacuum
energy. This subclass of the Horndeski Lagrangian is capable of dynamically
adjusting any value of the vacuum energy of the matter fields at the critical
point. We present the cosmological evolution of the linear models and the
non-linear models with shift symmetry. We come to the conclusion that the shift
symmetric non-linear models can deliver a viable background compatible with
current observations.Comment: 7 pages, 2 figures. Proceedings accepted for publication in
"Universe", Special Issue "Varying Constants and Fundamental Cosmology" for
the VARCOSMOFUN16 in Szczecin, Poland, 12-17 September, 201
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