6,114 research outputs found
CP Violation in Fermion Pair Decays of Neutral Boson Particles
We study CP violation in fermion pair decays of neutral boson particles with
spin 0 or 1. We study a new asymmetry to measure CP violation in decays and discuss the possibility of measuring it
experimentally. For the spin-1 particles case, we study CP violation in the
decays of to octet baryon pairs. We show that these decays can
be used to put stringent constraints on the electric dipole moments of
, and .Comment: 14p, OZ-93/22, UM-93/89, OITS 51
Effect of isoprene emissions from major forests on ozone formation in the city of Shanghai, China
Ambient surface level concentrations of isoprene (C<sub>5</sub>H<sub>8</sub>) were measured in the major forest regions located south of Shanghai, China. Because there is a large coverage of broad-leaved trees in this region, high concentrations of isoprene were measured, ranging from 1 to 6 ppbv. A regional dynamical/chemical model (WRF-Chem) is applied for studying the effect of such high concentrations of isoprene on the ozone production in the city of Shanghai. The evaluation of the model shows that the calculated isoprene concentrations agree with the measured concentrations when the measured isoprene concentrations are lower than 3 ppb, but underestimate the measurements when the measured values are higher than 3 ppb. Isoprene was underestimated only at sampling sites near large bamboo plantations, a high isoprene source, indicating the need to include geospatially resolved bamboo distributions in the biogenic emission model. The assessment of the impact of isoprene on ozone formation suggests that the concentrations of peroxy radicals (RO<sub>2</sub>) are significantly enhanced due to the oxidation of isoprene, with a maximum of 30 ppt. However, the enhancement of RO<sub>2</sub> is confined to the forested regions. Because the concentrations of NO<sub>x</sub> were low in the forest regions, the ozone production due to the oxidation of isoprene (C<sub>5</sub>H<sub>8</sub> + OH &rarr; &rarr; RO<sub>2</sub> + NO &rarr; &rarr; O<sub>3</sub>) is low (less than 2–3 ppb h<sup>&minus;1</sup>). The calculation further suggests that the oxidation of isoprene leads to the enhancement of carbonyls (such as formaldehyde and acetaldehyde) in the regions downwind of the forests, due to continuous oxidation of isoprene in the forest air. As a result, the concentrations of HO<sub>2</sub> radical are enhanced, resulting from the photo-disassociation of formaldehyde and acetaldehyde. Because the enhancement of HO<sub>2</sub> radical occurs in regions downwind of the forests, the enhancement of ozone production (6–8 ppb h<sup>&minus;1</sup>) is higher than in the forest region, causing by higher anthropogenic emissions of NO<sub>x</sub>. This study suggests that the biogenic emissions in the major forests to the south of Shanghai have important impacts on the levels of ozone in the city, mainly due to the carbonyls produced by the continuous oxidation of isoprene in the forest air
A review of age estimation research to evaluate its inclusion in automated child pornography detection
The uses of artificial intelligence (AI) today seem limitless. It has helped organisations understand their customers more, provide them with better, more tailored services, and helped people with disabilities understand the world they previously could not. There are also many areas of current research for the use of AI. Aiding law-enforcement when they must analyse evidence of an indecent nature is one example where the use of AI, if successful, could enhance detection of indecent images and also reduce the workload and stress on the law enforcement staff employed in such activities. Working with indecent images of minors is particularly stressful. This paper reviews the current stage at which artificial intelligence finds itself when estimating a person’s age. By reviewing its accuracy, it is possible to evaluate the feasibility of its inclusion in an artificial-intelligence-aided evidence analysis tool. With artificial intelligence currently capable of estimating a person’s age to within a few years, its incorporation would most certainly allow photographs to be analysed and flagged if anyone is suspected of being underage
Cost-effectiveness of magnetic resonance imaging in cervical clearance of obtunded blunt trauma after a normal computed tomographic finding
© 2018 American Medical Association. All rights reserved. IMPORTANCE Magnetic resonance imaging (MRI) continues to be performed for cervical clearance of obtunded blunt trauma, despite poor evidence regarding its utility after a normal computed tomographic (CT) finding. OBJECTIVE To evaluate the utility and cost-effectiveness of MRI vs no follow-up after a normal cervical CT finding in patients with obtunded blunt trauma. DESIGN, SETTING AND PARTICIPANTS This cost-effectiveness analysis evaluated an average patient aged 40 years with blunt trauma from an institutional practice. The analysis used a Markov decision model over a lifetime horizon from a societal perspective with variables from systematic reviews and meta-analyses and reimbursement rates from the Centers for Medicare & Medicaid Services, National Spinal Cord Injury Database, and other large published studies. Data were collected from the most recent literature available. INTERVENTIONS No follow-up vs MRI follow-up after a normal cervical CT finding. RESULTS In the base case of a 40-year-old patient, the cost of MRI follow-up was 1059 with a health benefit of 24.11 QALY, and thus no follow-up was the dominant strategy. Probabilistic sensitivity analysis showed no follow-up to be the better strategy in all 10 000 iterations. No follow-up was the better strategy when the negative predictive value of the initial CT was relatively high (\u3e98%) or the risk of an injury treated with a cervical collar turning into a permanent neurologic deficit was higher than 25% or when the risk of a missed injury turning into a neurologic deficit was less than 58%. The sensitivity and specificity of MRI were varied simultaneously in a 2-way sensitivity analysis, and no follow-up remained the optimal strategy. CONCLUSIONS AND RELEVANCE Magnetic resonance imaging had a lower health benefit and a higher cost compared with no follow-up after a normal CT finding in patients with obtunded blunt trauma to the cervical spine, a finding that does not support the use of MRI in this group of patients. The conclusion is robust in sensitivity analyses varying key variables in the model. More literature on these key variables is needed before MRI can be considered to be beneficial in the evaluation of obtunded blunt trauma
Oxidation and mechanical properties of in situ hybrid (TiCp+TiBw)/Ti6Al4V composites with tailored network microstructure
Understanding entangled spins in QED
The stability of two entangled spins dressed by electrons is studied by
calculating the scattering phase shifts. The interaction between electrons is
interpreted by fully relativistic QED and the screening effect is described
phenomenologically in the Debye exponential form . Our results
show that if the (Einstein-Podolsky-Rosen-) EPR-type states are kept stable
under the interaction of QED, the spatial wave function must be
parity-dependent. The spin-singlet state and the polarized state along the z-axis\QTR{bf}{\}give rise to two
different kinds of phase shifts\QTR{bf}{.} Interestingly, the interaction
between electrons in the spin-singlet pair is found to be attractive. Such an
attraction could be very useful when we extract the entangled spins from
superconductors. A mechanism to filter the entangled spins is also discussed.Comment: 6 pages, 3 figures. changes adde
Magnetocaloric effect in bamboo-grained Ni-Mn-Ga microwires over a wide working temperature interval
Single Transverse Spin Asymmetries at Parton Level
Two factorization approaches have been proposed for single transverse spin
asymmetries. One is the collinear factorization, another is the
transverse-momentum-dependent factorization. They have been previously derived
in a formal way by using diagram expansion at hadron level. If the two
factorizations hold or can be proven, they should also hold when we replace
hadrons with parton states. We examine these two factorizations at parton level
with massless partons. It is nontrivial to generate these asymmetries at parton
level with massless partons because the asymmetries require helicity-flip and
nonzero absorptive parts in scattering amplitudes. By constructing suitable
parton states with massless partons we derive the two factorizations for the
asymmetry in Drell-Yan processes. It is found from our results that the
collinear factorization derived at parton level is not the same as that derived
at hadron level. Our results with massless partons confirm those derived with
single massive parton state in our previous works.Comment: shortened version to match published versio
REWAFL: Residual Energy and Wireless Aware Participant Selection for Efficient Federated Learning over Mobile Devices
Participant selection (PS) helps to accelerate federated learning (FL)
convergence, which is essential for the practical deployment of FL over mobile
devices. While most existing PS approaches focus on improving training accuracy
and efficiency rather than residual energy of mobile devices, which
fundamentally determines whether the selected devices can participate.
Meanwhile, the impacts of mobile devices' heterogeneous wireless transmission
rates on PS and FL training efficiency are largely ignored. Moreover, PS causes
the staleness issue. Prior research exploits isolated functions to force
long-neglected devices to participate, which is decoupled from original PS
designs. In this paper, we propose a residual energy and wireless aware PS
design for efficient FL training over mobile devices (REWAFL). REW AFL
introduces a novel PS utility function that jointly considers global FL
training utilities and local energy utility, which integrates energy
consumption and residual battery energy of candidate mobile devices. Under the
proposed PS utility function framework, REW AFL further presents a residual
energy and wireless aware local computing policy. Besides, REWAFL buries the
staleness solution into its utility function and local computing policy. The
experimental results show that REW AFL is effective in improving training
accuracy and efficiency, while avoiding "flat battery" of mobile devices
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