2,227 research outputs found
Location and Direction Dependent Effects in Collider Physics from Noncommutativity
We examine the leading order noncommutative corrections to the differential
and total cross sections for e+ e- --> q q-bar. After averaging over the
earth's rotation, the results depend on the latitude for the collider, as well
as the direction of the incoming beam. They also depend on scale and direction
of the noncommutativity. Using data from LEP, we exclude regions in the
parameter space spanned by the noncommutative scale and angle relative to the
earth's axis. We also investigate possible implications for phenomenology at
the future International Linear Collider.Comment: version to appear in PR
Positronium Hyperfine Splitting in Non-commutative Space at the Order
We obtain positronium Hyperfine Splitting owing to the non-commutativity of
space and show that, in the leading order, it is proportional to where, is the parameter of non-commutativity. It is also
shown that spatial non-commutativity splits the spacing between triplet
excited levels which provides an experimental test on
the non-commutativity of space.Comment: 7 pages, 2 figures, to appear in Phys. Rev.
Simplified model to predict the thermal demand profile of districts
Extensive research works have been carried out over the past few decades in the development of simulation tools to predict the thermal performance of buildings. These validated tools have been used in the design of the building and its components. However, limited simulation tools have been developed for modeling of district energy systems, which can potentially be a very laborious and time-consuming process. Besides many associated limitations, providing a realistic demand profile of the district energy systems is not a straightforward task due to high number of parameters involved in predicting a detail demand profile.
This paper reports the development of a simplified model for predicting the thermal demand profile of a district heating system. The paper describes the method used to develop two types of simplified models to predict the thermal load of a variety of buildings (residential, office, attached, detached, etc.). The predictions were also compared with those made by the detailed simulation models.
The simplified model was then utilized to predict the energy demand of a variety of districts types (residential, commercial or mix), and its prediction accuracy was compared with those made by detailed model: good agreement was observed between the results
Multiphysics discovery with moving boundaries using Ensemble SINDy and Peridynamic Differential Operator
This study proposes a novel framework for learning the underlying physics of
phenomena with moving boundaries. The proposed approach combines Ensemble SINDy
and Peridynamic Differential Operator (PDDO) and imposes an inductive bias
assuming the moving boundary physics evolve in its own corotational coordinate
system. The robustness of the approach is demonstrated by considering various
levels of noise in the measured data using the 2D Fisher-Stefan model. The
confidence intervals of recovered coefficients are listed, and the
uncertainties of the moving boundary positions are depicted by obtaining the
solutions with the recovered coefficients. Although the main focus of this
study is the Fisher-Stefan model, the proposed approach is applicable to any
type of moving boundary problem with a smooth moving boundary front without a
mushy region. The code and data for this framework is available at:
https://github.com/alicanbekar/MB_PDDO-SINDy.Comment: 26 pages, 22 figures, submitted to Proceedings of the Royal Society
Application of Screening Analyses for the Stability of Landslide in Seymareh Dam Project
Seymareh dam and hydropower plant project is located in western province of Ilam, in Iran. This concrete arch dam with 178m height and 196 m crest length is to be placed on Seymareh River, the axis of which is located on the north wing of an anticline including Asmari limestone layers. The dramatic variation of dip angle of bedding in this part of anticline has created many fractures that result in slides. In October 1st 2003, when excavation in the left bank was being operated to construct an access road to the valley, a large landslide triggered on the top of power tunnel intake. The landslide complete in November 10th 2003 few hours after an intensive rainfall by leaving some 300000 m3 mass of debris. The sliding was a planar failure on a thin marly limestone of 26° dip and 40 cm thick. Due to the future location of water intake structure at the entrance part of power tunnel, it was quite vital to save this structure from any further movements of the debris left by the landslide. Further investigations showed that this is possible to keep debris in place by flattening the material in forms of stable slopes and berms. In order to decrease the remedial costs, the new recommended method of screening analyses for seismic stability proposed by SP117 Guideline in southern California Earthquake Center (2002) was adopted. Finally using this method, a slope design with almost minimum costs was achieved. This paper contains a description to geotechnical conditions, the history of landslide, and remedy works to protect water intake structure
Generation of circular polarization of the CMB
According to the standard cosmology, near the last scattering surface, the
photons scattered via Compton scattering are just linearly polarized and then
the primordial circular polarization of the CMB photons is zero. In this work
we show that CMB polarization acquires a small degree of circular polarization
when a background magnetic field is considered or the quantum electrodynamic
sector of standard model is extended by Lorentz-noninvariant operators as well
as noncommutativity. The existence of circular polarization for the CMB
radiation may be verified during future observation programs and it represents
a possible new channel for investigating new physics effects.Comment: 28 pages, v3, Phys. Rev. D 81, 084035 (2010
Is Helicobacter pylori infection a risk factor for childhood periodic syndromes?
AbstractBackground and objectivesHelicobacter pylori (H. pylori) infection has been assumed to have roles in various extra-digestive diseases. The current study was designed to evaluate the incidence of H. pylori infection in patients with cyclic vomiting syndrome and its possible role in the etiology of this disease.Design and settingIn this case-control study, 120 cases with diagnoses of cyclic vomiting or abdominal migraine who were registered at the Gastroenterology Clinic at Shiraz University of Medical Sciences from 2010 to 2013 were enrolled.Materials and methodsPrimarily information regarding the patients' diseases were collected with a data gathering sheet, and fresh morning stool samples were collected from the patients and examined for H. pylori stool antigen with the H. pylori Ag EIA test kit. The results were compared with those of healthy children from the control group.ResultsA total of 120 patients with cyclic vomiting (47.5%) and abdominal migraine (52.5%) with a mean age of 7.1 ± 3.4 (range 2â16 years) and a male-to-female ratio of 1.6 were included. The HPs Ag tests were positive in only 7 (5.8%) patients in our case group, and the HPs Ag tests were positive in 13 (13%) of the children in the control group; this difference was statistically insignificant.ConclusionOur study did not support H. pylori infection as an etiological factor in CV or AM
Constraining noncommutative field theories with holography
An important window to quantum gravity phenomena in low energy noncommutative
(NC) quantum field theories (QFTs) gets represented by a specific form of UV/IR
mixing. Yet another important window to quantum gravity, a holography,
manifests itself in effective QFTs as a distinct UV/IR connection. In matching
these two principles, a useful relationship connecting the UV cutoff
, the IR cutoff and the scale of
noncommutativity , can be obtained. We show that an effective
QFT endowed with both principles may not be capable to fit disparate
experimental bounds simultaneously, like the muon and the masslessness of
the photon. Also, the constraints from the muon preclude any possibility
to observe the birefringence of the vacuum coming from objects at cosmological
distances. On the other hand, in NC theories without the UV completion, where
the perturbative aspect of the theory (obtained by truncating a power series in
) becomes important, a heuristic estimate of the region
where the perturbative expansion is well-defined , gets affected when holography is applied by providing the energy of the
system a -dependent lower limit. This may affect models
which try to infer the scale by using data from low-energy
experiments.Comment: 4 pages, version to be published in JHE
Neutrino-electron scattering in noncommutative space
Neutral particles can couple with the gauge field in the adjoint
representation at the tree level if the space-time coordinates are
noncommutative (NC). Considering neutrino-photon coupling in the NC QED
framework, we obtain the differential cross section of neutrino-electron
scattering. Similar to the magnetic moment effect, one of the NC terms is
proportional to , where is the electron recoil energy.
Therefore, this scattering provides a chance to achieve a stringent bound on
the NC scale in low energy by improving the sensitivity to the smaller electron
recoil energy.Comment: 12 pages, 2 figure
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