15,601 research outputs found
Electrochemical reduction of carbamazepine in ethanol and water solutions using a glassy carbon electrode
The electrochemical reduction of carbamazepine in ethanol and water using a glassy carbon electrode has been studied. In all experimental conditions of scan rate and concentration of carbamazepine an irreversible cathodic wave was observed by cyclic voltammetry (CV). Electrochemical parameters and a plausible EqC mechanism have been reported from the electrochemical measurements and digital simulation. The values of thermodynamic E1/2 were correlated with solvent polarity parameters that it can be interesting for biological, pharmaceutical and forensic purposes. Limits of Detection (LOD) for DPV are 1.1 and 9.0 g/mL (4.65x10-6 and 3.81x10-5 M) in ethanol and water, respectively. The precision and recoveries obtained for tablets and plasma samples showed that the method could be successfully used for analysis
Non-relativistic Extended Gravity and its applications across different astrophysical scales
Using dimensional analysis techniques we present an extension of Newton's
gravitational theory built under the assumption that Milgrom's acceleration
constant is a fundamental quantity of nature. The gravitational force converges
to Newton's gravity and to a MOND-like description in two different mass and
length regimes. It is shown that a modification on the force sector (and not in
the dynamical one as MOND does) is more convenient and can reproduce and
predict different phenomena usually ascribed to dark matter at the
non-relativistic level.Comment: 4 pages, 2 figures. To appear in the proceedings of the 2011 Spanish
Relativity Meeting (ERE2011) held in Madrid, Spai
Off-shell effects in the relativistic mean field model and their role in CC (anti)neutrino scattering at MiniBooNE kinematics
The relativistic mean field (RMF) model is used to describe nucleons in the
nucleus and thereby to evaluate the effects of having dynamically off-shell
spinors. Compared with free, on-shell nucleons as employed in some other
models, within the RMF nucleons are described by relativistic spinors with
strongly enhanced lower components. In this work it is seen that for MiniBooNE
kinematics, neutrino charged-current quasielastic cross sections show some
sensitivity to these off-shell effects, while for the antineutrino-nucleus case
the total cross sections are seen to be essentially independent of the
enhancement of the lower components. As was found to be the case when comparing
the RMF results with the neutrino-nucleus data, the present impulse
approximation predictions within the RMF also fall short of the MiniBooNE
antineutrino-nucleus data.Comment: 19 pages, 7 figures, submitted to Physics Letters
Gravitational shocks as a key ingredient of Gamma-Ray Bursts
We identify a novel physical mechanism that may be responsible for energy
release in -ray bursts. Radial perturbations in the neutron core,
induced by its collision with collapsing outer layers during the early stages
of supernova explosions, can trigger a gravitational shock, which can readily
eject a small but significant fraction of the collapsing material at
ultra-relativistic speeds. The development of such shocks is a strong-field
effect arising in near-critical collapse in General Relativity and has been
observed in numerical simulations in various contexts, including in particular
radially perturbed neutron star collapse, albeit for a tiny range of initial
conditions. Therefore, this effect can be easily missed in numerical
simulations if the relevant parameter space is not exhaustively investigated.
In the proposed picture, the observed rarity of -ray bursts would be
explained if the relevant conditions for this mechanism appear in only about
one in every core collapse supernovae. We also mention the
possibility that near-critical collapse could play a role in powering the
central engines of Active Galactic Nuclei.Comment: 9 pages, 3 figure
An effective theory of accelerated expansion
We work out an effective theory of accelerated expansion to describe general
phenomena of inflation and acceleration (dark energy) in the Universe. Our aim
is to determine from theoretical grounds, in a physically-motivated and model
independent way, which and how many (free) parameters are needed to broadly
capture the physics of a theory describing cosmic acceleration. Our goal is to
make as much as possible transparent the physical interpretation of the
parameters describing the expansion. We show that, at leading order, there are
five independent parameters, of which one can be constrained via general
relativity tests. The other four parameters need to be determined by observing
and measuring the cosmic expansion rate only, H(z). Therefore we suggest that
future cosmology surveys focus on obtaining an accurate as possible measurement
of to constrain the nature of accelerated expansion (dark energy and/or
inflation).Comment: In press; minor changes, results unchange
Technological requirements for solutions in the conservation and protection of historic monuments and archaeological remains
Executive summary: This Study has discovered many achievements associated with European support for
scientific and technological research for the protection and conservation of cultural
heritage. The achievements to date are:
1. Creation of an active research community
2. A body of research of unparalleled and enviable international quality and character
3. Ongoing effectiveness of research beyond initial funding
4. Substantial rate of publication
5. Imaginative tools of dissemination and publication
6. Clear spin-offs and contribution to European competitiveness often going outside
the European cultural heritage area
7. Contribution to emerging European legislation, for example, air quality
management.
The Study has also uncovered important research gaps associated with this field that have
yet to begin to be investigated. It has also discovered the need for continuing fine scale
advancement in areas where researchers have been active for a number of years. The
overall picture is that European research in the field of cultural heritage protection must be
put on a secure footing if it is to maintain its commanding lead over other regions of the
world.
This Study concludes that:
1. It would be invidious to attempt to separate basic and applied research in this area
of research. Like any other scientific endeavour, this field needs to integrate basic
and applied research if it is to continue to thrive.
2. Small, flexible, focused interdisciplinary teams responsive to European needs, must
be sustained, promoted and celebrated as models of sustainability and that what is
proposed under the European Research Area (ERA) for large and complex
research projects, could inflict serious damage on this area of research.
3. Resources cannot be delegated to Member States because of the interdisciplinary
nature of cultural heritage and the need for a co-ordinated pan-European
perspective across this research that helps to define the essential character of
European cultural heritage. National programmes only serve local needs, leading
to loss of strategic output, lessening of competitiveness and risk of duplication.
4. A mechanism needs to be created to help researchers working in this field to
communicate and exchange information with related sectors such as construction,
urban regeneration, land reclamation and agriculture.
5. There is overwhelming agreement over the need for sustainable research funding
for cultural heritage and for an iterative process of exchange among researchers,
decision-makers and end-users in order to maximize benefits from project
inception through to dissemination, audit and review.
For all the reasons mentioned above, the most significant recommendation in this Report is
the identification of the need for a European Panel on the Application of Science for Cultural Heritage (EPASCH)
Charged-current inclusive neutrino cross sections in the SuperScaling model including quasielastic, pion production and meson-exchange contributions
Charged current inclusive neutrino-nucleus cross sections are evaluated using
the superscaling model for quasielastic scattering and its extension to the
pion production region. The contribution of two-particle-two-hole vector
meson-exchange current excitations is also considered within a fully
relativistic model tested against electron scattering data. The results are
compared with the inclusive neutrino-nucleus data from the T2K and SciBooNE
experiments. For experiments where GeV, the
three mechanisms considered in this work provide good agreement with the data.
However, when the neutrino energy is larger, effects from beyond the
also appear to be playing a role. The results show that processes induced by
two-body currents play a minor role at the kinematics considered.Comment: 10 pages, 7 figure
- …