198 research outputs found
Towards a new approach to quantum gravity phenomenology
The idea that quantum gravity manifestations would be associated with a
violation of Lorentz invariance is very strongly bounded and faces serious
theoretical challenges. This leads us to consider an alternative line of
thought for such phenomenological search. We discuss the underlying viewpoint
and briefly mention its possible connections with current theoretical ideas. We
also outline the challenges that the experimental search of the effects would
seem to entail.Comment: 13 pages, no figures. Discussion added, same conclusion
Communication and Surveillance for Ground Transportation
For high speed intercity or low speed intracity operation, communications and surveillance are important aspects in the design of control systems for advanced ground transportation. New technological approaches in communications and surveillance can provide improvements in system capacity, operational economy, safety and passenger convenience.
A dielectric waveguide for communications and surveillance of vehicle characteristics (position and velocity) has been under experimental and analytical investigation for use along fixed guideways for ground transportation. This communication concept is nonradiating, has a broad bandwidth and provides a high rate of information transfer. Another important aspect of guideway surveillance is the detection of foreign obstacles that may cause vehicle damage or compromise passenger safety. For this application, an optical concept using a set of laser beams along the wayside is under investigation. The operating characteristics and method of deployment along TACV and railway guideways are presented
Threshold resummation at N LL 3 accuracy and approximate N3LO corrections to semi-inclusive DIS
We advance the threshold resummation formalism for semi-inclusive deep-inelastic scattering (SIDIS) to next-to-next-to-next-to-leading logarithmic (NLL3) order, including the three-loop hard factor. We expand the results in the strong coupling to obtain approximate next-to-next-to-next-to-leading order (N3LO) corrections for the SIDIS cross section. In Mellin moment space, these corrections include all terms that are logarithmically enhanced at threshold, or that are constant. We also consider a set of corrections that are suppressed near threshold. Our numerical estimates show modest changes of the cross section by the approximate N3LO terms, suggesting a very good perturbative stability of the SIDIS process.Fil: Abele, Maurizio. Eberhard Karls Universität Tübingen; AlemaniaFil: de Florian, Daniel Enrique. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Ciencias FÃsicas. - Universidad Nacional de San MartÃn. Instituto de Ciencias FÃsicas; ArgentinaFil: Vogelsang, Werner. Eberhard Karls Universität Tübingen; Alemani
Approximate NNLO QCD corrections to semi-inclusive DIS
We determine approximate next-to-next-to-leading order (NNLO) corrections to unpolarized and polarized semi-inclusive deep-inelastic scattering. They are derived using the threshold resummation formalism, which we fully develop to next-to-next-to-leading logarithmic accuracy, including the two-loop hard factor. The approximate NNLO terms are obtained by expansion of the resummed expression. They include all terms in Mellin space that are logarithmically enhanced at threshold, or that are constant. In terms of the customary semi-inclusive deep-inelastic scattering variables x and zthey include all double distributions (that is, ?plus? distributions and δ functions) in the partonic variables. We also investigate corrections that are suppressed at threshold and we determine the dominant terms among these. Our numerical estimates suggest much significance of the approximate NNLO terms, along with a reduction in scale dependence.Fil: Abele, Maurizio. Eberhard Karls Universität Tübingen; AlemaniaFil: de Florian, Daniel Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; ArgentinaFil: Vogelsang, Werner. Eberhard Karls Universität Tübingen; Alemani
Quantum Gravity Phenomenology without Lorentz Invariance Violation: a detailed proposal
We describe a scheme for the exploration of quantum gravity phenomenology
focussing on effects that could be thought as arising from a fundamental
granularity of space-time. In contrast with the simplest assumptions, such
granularity is assumed to respect Lorentz Invariance but is otherwise left
unspecified. The proposal is fully observer covariant, it involves non-trivial
couplings of curvature to matter fields and leads to a well defined
phenomenology. We present the effective Hamiltonian which could be used to
analyze concrete experimental situations, some of which are briefly described,
and we shortly discuss the degree to which the present proposal is in line with
the fundamental ideas behind the equivalence principle.Comment: LaTeX, 24 pages. To be published in Classical and Quantum Gravit
Project DECIDE, part 1: increasing the amount of valid advance directives in people with Alzheimer’s disease by offering advance care planning - a prospective double-arm intervention study
Finanziert im Rahmen der DEAL-Verträge durch die Universitätsbibliothek SiegenBackground
Everybody has the right to decide whether to receive specific medical treatment or not and to provide their free, prior and informed consent to do so. As dementia progresses, people with Alzheimer’s dementia (PwAD) can lose their capacity to provide informed consent to complex medical treatment. When the capacity to consent is lost, the autonomy of the affected person can only be guaranteed when an interpretable and valid advance directive exists. Advance directives are not yet common in Germany, and their validity is often questionable. Once the dementia diagnosis has been made, it is assumed to be too late to write an advance directive. One approach used to support the completion of advance directives is ‘Respecting Choices’®—an internationally recognised, evidence-based model of Advance Care Planning (ACP), which, until now, has not been evaluated for the target group of PwAD. This study’s aims include (a) to investigate the proportion of valid advance directives in a memory clinic population of persons with suspected AD, (b) to determine the predictors of valid advance directives, and (c) to examine whether the offer of ACP can increase the proportion of valid advance directives in PwAD.
Method
We intend to recruit at least N = 250 participants from two memory clinics in 50 consecutive weeks. Of these, the first 25 weeks constitute the baseline phase (no offer of ACP), the following 25 weeks constitute the intervention phase (offer of ACP). The existence and validity of an advance directive will be assessed twice (before and after the memory clinic appointment). Moreover, potential predictors of valid advance directives are assessed.
Discussion
The results of this study will enhance the development of consent procedures for advance directives of PwAD based on the ACP/Respecting Choices (R) approach. Therefore, this project contributes towards increasing the autonomy and inclusion of PwAD and the widespread acceptance of valid advance directives in PwAD
A window to quantum gravity phenomena in the emergence of the seeds of cosmic structure
Inflationary cosmology has, in the last few years,received a strong dose of
support from observations. The fact that the fluctuation spectrum can be
extracted from the inflationary scenario through an analysis that involves
quantum field theory in curved space-time, and that it coincides with the
observational data has lead to a certain complacency in the community, which
prevents the critical analysis of the obscure spots in the derivation. We argue
here briefly, as we have discussed in more detail elsewhere, that there is
something important missing in our understanding of the origin of the seeds of
Cosmic Structure, as is evidenced by the fact that in the standard accounts the
inhomogeneity and anisotropy of our universe seems to emerge from an exactly
homogeneous andisotropic initial state through processes that do not break
those symmetries. This article gives a very brief recount of the problems faced
by the arguments based on established physics. The conclusion is that we need
some new physics to be able to fully address the problem. The article then
exposes one avenue that has been used to address the central issue and
elaborates on the degree to which, the new approach makes different predictions
from the standard analyses. The approach is inspired on Penrose's proposals
that Quantum Gravity might lead to a real, dynamical collapse of the wave
function, a process that we argued has the properties needed to extract us from
the theoretical impasse described above.Comment: 13 pages, 3 figures. To appear in DICE 2008 conference proceeding
Design of the Magnet System of the Neutron Decay Facility PERC
The PERC (Proton and Electron Radiation Channel) facility is currently under
construction at the research reactor FRM II, Garching. It will serve as an
intense and clean source of electrons and protons from neutron beta decay for
precision studies. It aims to contribute to the determination of the
Cabibbo-Kobayashi-Maskawa quark-mixing element from neutron decay data
and to search for new physics via new effective couplings. PERC's central
component is a 12m long superconducting magnet system. It hosts an 8m long
decay region in a uniform field. An additional high-field region selects the
phase space of electrons and protons which can reach the detectors and largely
improves systematic uncertainties. We discuss the design of the magnet system
and the resulting properties of the magnetic field.Comment: Proceedings of the International Workshop on Particle Physics at
Neutron Sources PPNS 2018, Grenoble, France, May 24-26, 201
Appropriate relaxation of non-pharmaceutical interventions minimizes the risk of a resurgence in SARS-CoV-2 infections in spite of the Delta variant
We analyze the relaxation of non-pharmaceutical interventions (NPIs) under an increasing number of vaccinations in Germany. For the spread of SARS-CoV-2 we employ a SIR-type model that accounts for age-dependence and includes realistic contact patterns between age groups. The implementation of NPIs occurs on changed contact patterns, improved isolation, or reduced infectiousness when, e.g., wearing masks. We account for spatial heterogeneity and commuting activities in between regions in Germany, and the testing of commuters is considered as a further NPI. We include the ongoing vaccination process and analyze the effect of the B.1.617.2 (Delta) variant, which is considered to be \MJK{4}0\%-60\% more infectious then the currently dominant B.1.1.7 (Alpha) variant. We explore different opening scenarios under the ongoing vaccination process by assuming that local restrictions are either lifted in early July or August with or without continued wearing of masks and testing. Our results indicate that we can counteract the resurgence of SARS-CoV-2 despite the Delta variant with appropriate timing for the relaxation of NPIs. In all cases, however, school children are hit the hardest
Appropriate relaxation of non-pharmaceutical interventions minimizes the risk of a resurgence in SARS-CoV-2 infections in spite of the Delta variant
We analyze the relaxation of non-pharmaceutical interventions (NPIs) under an increasing number of vaccinations in Germany. For the spread of SARS-CoV-2 we employ a SIR-type model that accounts for age-dependence and includes realistic contact patterns between age groups. The implementation of NPIs occurs on changed contact patterns, improved isolation, or reduced infectiousness when, e.g., wearing masks. We account for spatial heterogeneity and commuting activities in between regions in Germany, and the testing of commuters is considered as a further NPI. We include the ongoing vaccination process and analyze the effect of the B.1.617.2 (Delta) variant, which is considered to be \MJK{4}0\%-60\% more infectious then the currently dominant B.1.1.7 (Alpha) variant. We explore different opening scenarios under the ongoing vaccination process by assuming that local restrictions are either lifted in early July or August with or without continued wearing of masks and testing. Our results indicate that we can counteract the resurgence of SARS-CoV-2 despite the Delta variant with appropriate timing for the relaxation of NPIs. In all cases, however, school children are hit the hardest
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