3,859 research outputs found
Emergent Cosmos in Einstein-Cartan Theory
Based on the Padmanabhan's proposal, the accelerated expansion of the
universe can be driven by the difference between the surface and bulk degrees
of freedom in a region of space, described by the relation
where and are the
degrees of freedom assigned to the surface area and the matter-energy content
inside the bulk such that the indexes and represent
energy-momentum and dark energy, respectively. In the present work, the
dynamical effect of the Weyssenhoff perfect fluid with intrinsic spin and its
corresponding spin degrees of freedom in the framework of Einstein-Cartan (EC)
theory are investigated. Based on the modification of Friedmann equations due
to the spin-spin interactions, a correction term for the Padmanabhan's original
relation including the number of degrees of
freedom related to this spin interactions is obtained through the modification
in term as leading to in which is the corresponding
degrees of freedom related to the intrinsic spin of the matter content of the
universe. Moreover, the validity of the unified first law and the generalized
second law of thermodynamics for the Einstein-Cartan cosmos are investigated.
Finally, by considering the covariant entropy conjecture and the bound
resulting from the emergent scenario, a total entropy bound is obtained. Using
this bound, it is shown that the for the universe as an expanding
thermodynamical system, the total effective Komar energy never exceeds the
square of the expansion rate with a factor of .Comment: 12 Pages, Accepted for Publication in Eur. Phys. J.
Psychometric assessment of beck scale for suicidal ideation (BSSI) in general population in Tehran
Background: Beck Scale for Suicidal Ideation (BSSI) is a widely used instrument to assess suicidality. However, there is only limited information about the psychometric characteristics of BSSI in the Persian language. In this study, we investigated the validity, reliability and factor structure of the BSSI in the general population of Tehran. Methods: Initially, 900 questionnaire packages were distributed to the general population of Tehran (response rate: 59 percent), using cluster random sampling method. The questionnaire package consisted of a demographic questionnaire, the Persian translation of the BSSI, Symptom checklist-90- Revised (SCL-90-R), Beck Hopelessness Inventory (BHI) and Philips Social Support Appraisal Scale. Internal consistency and correlations of the BSSI scores with other constructs were investigated. Factor analysis was done using principal component method. Results: The Cronbach's alpha coefficients of the screening part and the whole scale were satisfactory (>0.8). The scores of both the screening part and the total scale in individuals who experienced suicidal attempt were higher than others. Both the screening part and the total scale had a positive correlation with depression and Global Severity Index in SCL-90-R, and a negative correlation with social support. The scores of the screening part had a positive correlation with anxiety, psychoticism, hostility and hopelessness as well. The screening part consisted of a single factor which explains 60 of the total variance. Conclusion: The Persian translation of the BSSI has desirable psychometric properties in research setting. However, the clinical usage of the scale remains to be explored, and the factor structure of the whole questionnaire should be assessed in a clinical sample
SLIM at LHC: LHC search power for a model linking dark matter and neutrino mass
Recently a model has been proposed that links dark matter and neutrino
masses. The dark matter candidate which is dubbed as SLIM has a mass of MeV
scale and can show up at low energy experiments. The model also has a high
energy sector which consists of a scalar doublet, . We
discuss the potential of the LHC for discovering the new scalars. We focus on
the and production and the subsequent decay
of the charged scalar to a charged lepton and the SLIM which appears as missing
energy. Identifying the background, we estimate the signal significance and
find that it can exceed at 30 for the 14 TeV run at
the LHC. We comment on the possibility of extracting the flavor structure of
the Yukawa couplings which also determine the neutrino mass matrix. Finally, we
discuss the prospects of this search at the current 7 TeV run of the LHC.Comment: 26 pages, 21 figure
Effect of pipe size and location on water-main head loss in water distribution systems
This study discusses practical implications of considering unit head loss in different pipe sizes and in different locations of water distribution systems (WDSs) with regard to operation and maintenance. By visualizing unit head loss (using the Hazen-Williams relationship) in pipes obtained from 18 WDSs in North America, changes in unit head loss are put into perspective in different pipe sizes and different WDS locations. The results suggest that the importance of diameter is greater than that of the Hazen-Williams roughness factor, that flow rate plays a more important role than diameter in determination of head loss in pipes closer to water sources, and that diameter seems to be more important than flow rate in pipes at the periphery. Moreover, aging, tuberculation, and subsequently reduction in effective diameter can have a more critical effect on head loss in smaller pipes at the periphery of a system. Finally, effects of water conservation and pump scheduling in different locations of the network, as far as head loss is concerned, can potentially be more evident on larger pipes closer to the water source and in some cases on smaller pipes at the periphery. Therefore, it is suggested that network-level energy management decisions can have different effects on different pipe sizes in different locations
A small sealed Ta crucible for thermal analysis of volatile metallic samples
Differential thermal analysis on metallic alloys containing volatile elements
can be highly problematic. Here we show how measurements can be performed in
commercial, small-sample, equipment without modification. This is achieved by
using a sealed Ta crucible, easily fabricated from Ta tubing and sealed in a
standard arc furnace. The crucible performance is demonstrated by measurements
on a mixture of Mg and MgB, after heating up to 1470. We
also show data, measured on an alloy with composition GdMg, that
clearly shows both the liquidus and a peritectic, and is consistent with
published phase diagram data
Comparison of nasal carriage of Staphylococcus aureus and its antimicrobial resistance in various grades of medical students
Global Ultrasound Elastography Using Convolutional Neural Network
Displacement estimation is very important in ultrasound elastography and
failing to estimate displacement correctly results in failure in generating
strain images. As conventional ultrasound elastography techniques suffer from
decorrelation noise, they are prone to fail in estimating displacement between
echo signals obtained during tissue distortions. This study proposes a novel
elastography technique which addresses the decorrelation in estimating
displacement field. We call our method GLUENet (GLobal Ultrasound Elastography
Network) which uses deep Convolutional Neural Network (CNN) to get a coarse
time-delay estimation between two ultrasound images. This displacement is later
used for formulating a nonlinear cost function which incorporates similarity of
RF data intensity and prior information of estimated displacement. By
optimizing this cost function, we calculate the finer displacement by
exploiting all the information of all the samples of RF data simultaneously.
The Contrast to Noise Ratio (CNR) and Signal to Noise Ratio (SNR) of the strain
images from our technique is very much close to that of strain images from
GLUE. While most elastography algorithms are sensitive to parameter tuning, our
robust algorithm is substantially less sensitive to parameter tuning.Comment: 4 pages, 4 figures; added acknowledgment section, submission type
late
Hierarchy Style Application in Line Extension with Responsive Loads Evaluating the Dynamic Nature of Solar Units
This paper presents a model for line extension scheduled to participate in responsive loads in the power system aiming the improvement of techno-economical parameters. The model is studied with the presence of photovoltaic generators that produce variable power depending on the geographical condition. The investment cost of the transmission expansion plan, demand response operation cost, generation costs and the sum of the voltage deviations are the four indices that the optimization problem is designed based on these four criteria. Objective functions are dynamic variables that change daily due to variation in generation and load. A multi-objective optimization method based on the analytic hierarchy technique is employed to solve the problem. The Pareto-optimal set is extracted with gravitational search style and the best solution is fund by AHT manner. Studies are carried out on the modified 30-bus and 24-bus IEEE test system to confirm the capability of the presented model. Two frameworks are defined to compare the suggested manner. A different amount of PV penetration is discussed in several scenarios. Also, load uncertainty is formulated and involved based on probability distribution function
Right-Handed Sector Leptogenesis
Instead of creating the observed baryon asymmetry of the universe by the
decay of right-handed (RH) neutrinos to left-handed leptons, we propose to
generate it dominantly by the decay of the RH neutrinos to RH leptons. This
mechanism turns out to be successful in large regions of parameter space. It
may work, in particular, at a scale as low as ~TeV, with no need to
invoke quasi-degenerate RH neutrino masses to resonantly enhance the asymmetry.
Such a possibility can be probed experimentally by the observation at colliders
of a singlet charged Higgs particle and of RH neutrinos. Other mechanisms which
may lead to successful leptogenesis from the RH lepton sector interactions are
also briefly presented. The incorporation of these scenarios in left-right
symmetric and unified models is discussed.Comment: 14 pages, latex, axodraw; minor clarifications and references added,
extended discussion of the signatures at collider
Identification of factors that influence energy performance in water distribution system mains
This paper aims at identifying paramount hydraulic factors in energy dynamics of water mains, using Principal Components Analysis (PCA). The proposed method is applied to two large ensembles of leaky and non-leaky pipes comprising over 40,000 pipes selected from 18 North American water distribution systems to guarantee the versatility of pipe characteristics and statistical significance of the explored patterns. PCA mono-plots indicate energy metrics such as Net Energy Efficiency, Energy Lost to Friction and Energy Lost to Leakage serve better in identification of low from high efficiency pipes. In addition, PCA mono-plots and bi-plots reveal relative importance of hydraulic parameters and that average flow rate, hydraulic proximity to major components and average unit headloss can have more tangible effects on energy dynamics of pipes compared to leakage and average pressure. Some factors such as elevation, diameter and CHW are not as influential as expected in distinguishing high-efficiency from low-efficiency pipes. Further, a comparison between the approach used in this paper and a simplified common-practice replacement strategy points out the difference energy considerations can make, if included in a bigger asset management landscape
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