807 research outputs found
Correct path-integral formulation of quantum thermal field theory in coherent-state representation
The path-integral quantization of thermal scalar, vector and spinor fields is
performed newly in the coherent-state representation. In doing this, we choose
the thermal electrodynamics and theory as examples. By this
quantization, correct expressions of the partition functions and the generating
functionals for the quantum thermal electrodynamics and theory are
obtained in the coherent-state representation. These expressions allow us to
perform analytical calculations of the partition functions and generating
functionals and therefore are useful in practical applications. Especially, the
perturbative expansions of the generating functionals are derived specifically
by virtue of the stationary-phase method. The generating functionals formulated
in the position space are re-derived from the ones given in the coherent-state
representation
Phototunable biomemory based on light-mediated charge trap
Phototunable biomaterialâbased resistive memory devices and understanding of their underlying switching mechanisms may pave a way toward new paradigm of smart and green electronics. Here, resistive switching behavior of photonic biomemory based on a novel structure of metal anode/carbon dots (CDs)âsilk protein/indium tin oxide is systematically investigated, with Al, Au, and Ag anodes as case studies. The charge trapping/detrapping and metal filaments formation/rupture are observed by in situ Kelvin probe force microscopy investigations and scanning electron microscopy and energyâdispersive spectroscopy microanalysis, which demonstrates that the resistive switching behavior of Al, Au anodeâbased device are related to the spaceâchargeâlimitedâconduction, while electrochemical metallization is the main mechanism for resistive transitions of Ag anodeâbased devices. Incorporation of CDs with lightâadjustable charge trapping capacity is found to be responsible for phototunable resistive switching properties of CDsâbased resistive random access memory by performing the ultraviolet light illumination studies on asâfabricated devices. The synergistic effect of photovoltaics and photogating can effectively enhance the internal electrical field to reduce the switching voltage. This demonstration provides a practical route for nextâgeneration biocompatible electronics
Hamiltonian theory of gaps, masses and polarization in quantum Hall states: full disclosure
I furnish details of the hamiltonian theory of the FQHE developed with Murthy
for the infrared, which I subsequently extended to all distances and apply it
to Jain fractions \nu = p/(2ps + 1). The explicit operator description in terms
of the CF allows one to answer quantitative and qualitative issues, some of
which cannot even be posed otherwise. I compute activation gaps for several
potentials, exhibit their particle hole symmetry, the profiles of charge
density in states with a quasiparticles or hole, (all in closed form) and
compare to results from trial wavefunctions and exact diagonalization. The
Hartree-Fock approximation is used since much of the nonperturbative physics is
built in at tree level. I compare the gaps to experiment and comment on the
rough equality of normalized masses near half and quarter filling. I compute
the critical fields at which the Hall system will jump from one quantized value
of polarization to another, and the polarization and relaxation rates for half
filling as a function of temperature and propose a Korringa like law. After
providing some plausibility arguments, I explore the possibility of describing
several magnetic phenomena in dirty systems with an effective potential, by
extracting a free parameter describing the potential from one data point and
then using it to predict all the others from that sample. This works to the
accuracy typical of this theory (10 -20 percent). I explain why the CF behaves
like free particle in some magnetic experiments when it is not, what exactly
the CF is made of, what one means by its dipole moment, and how the comparison
of theory to experiment must be modified to fit the peculiarities of the
quantized Hall problem
Corrigendum to âCarbonate delta drift: A new sediment drift typeâ [Mar. Geol. 401 (2018) 98â111]
The authors regret the mistake in the drawing of the delta drift architecture in figure 11. The authors would like to apologise for any inconvenience caused. [Figure presented
Diagnostic Value of Aortic Valve Calcification Levels in the Assessment of Low-Gradient Aortic Stenosis
Background: In patients with low-gradient aortic stenosis (AS) and low transvalvular flow, dobutamine stress echocardiography (DSE) is recommended to determine AS severity, whereas the degree of aortic valve calcification (AVC) supposedly correlates with AS severity according to current European and American guidelines. Objectives: The purpose of this study was to assess the relationship between AVC and AS severity as determined using echocardiography and DSE in patients with aortic valve area <1 cm2 and peak aortic valve velocity <4.0 m/s. Methods: All patients underwent DSE to determine AS severity and multislice computed tomography to quantify AVC. Receiver-operating characteristics curve analysis was used to assess the diagnostic value of AVC for AS severity grading as determined using echocardiography and DSE in men and women. Results: A total of 214 patients were included. Median age was 78 years (25th-75th percentile: 71-84 years) and 25% were women. Left ventricular ejection fraction was reduced (<50%) in 197 (92.1%) patients. Severe AS was diagnosed in 106 patients (49.5%). Moderate AS was diagnosed in 108 patients (50.5%; in 77 based on resting transthoracic echocardiography, in 31 confirmed using DSE). AVC score was high (â„2,000 for men or â„1,200 for women) in 47 (44.3%) patients with severe AS and in 47 (43.5%) patients with moderate AS. AVC sensitivity was 44.3%, specificity was 56.5%, and positive and negative predictive values for severe AS were 50.0% and 50.8%, respectively. Area under the receiver-operating characteristics curve was 0.508 for men and 0.524 for women. Conclusions: Multi-slice computed tomographyâderived AVC scores showed poor discrimination between grades of AS severity using DSE and cannot replace DSE in the diagnostic work-up of low-gradient severe AS.</p
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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