4,470 research outputs found
Semiclassical and Quantum Black Holes and their Evaporation, de Sitter and Anti-de Sitter Regimes, Gravitational and String Phase Transitions
An effective string theory in physically relevant cosmological and black hole
space times is reviewed. Explicit computations of the quantum string entropy,
partition function and quantum string emission by black holes (Schwarzschild,
rotating, charged, asymptotically flat, de Sitter dS and AdS space times) in
the framework of effective string theory in curved backgrounds provide an
amount of new quantum gravity results as: (i) gravitational phase transitions
appear with a distinctive universal feature: a square root branch point
singularity in any space time dimensions. This is of the type of the de Vega -
Sanchez transition for the thermal self-gravitating gas of point particles.
(ii) There are no phase transitions in AdS alone. (iii) For background,
upper bounds of the Hubble constant H are found, dictated by the quantum string
phase transition.(iv) The Hawking temperature and the Hagedorn temperature are
the same concept but in different (semiclassical and quantum) gravity regimes
respectively. (v) The last stage of black hole evaporation is a microscopic
string state with a finite string critical temperature which decays as usual
quantum strings do in non-thermal pure quantum radiation (no information
loss).(vi) New lower string bounds are given for the Kerr-Newman black hole
angular momentum and charge, which are entirely different from the upper
classical bounds. (vii) Semiclassical gravity states undergo a phase transition
into quantum string states of the same system, these states are duals of each
other in the precise sense of the usual classical-quantum (wave-particle)
duality, which is universal irrespective of any symmetry or isommetry of the
space-time and of the number or the kind of space-time dimensions.Comment: review paper, no figures. to appear in Int Jour Mod Phys
Bone Conduction Audio Communication System for Musicians
poster abstractMusicians often perform their music live with an in-ear device to monitor select audio signals and specific tempos. While wearing conventional earphones as audio monitors enables musicians to coordinate rhythmically, it weakens the userâs awareness to their surrounding acoustic environment by closing off one, if not both ears. Disorientation is common for many musicians, such as saxophonists, violinists, and singers due the inability to fully hear oneâs own musical instrument and surrounding ambient environment. This presents the necessity of a better solution for musicians. Bone conduction is an open ear design that allows audio transmission to be heard through vibrations of the bone while allowing the ambient sound of a stage environment to be heard by live performers. Bone conduction, as a means of audio transmission, is a method of sonic communication already shown of value. It is currently implemented in hardware produced by the military and law enforcement. Unfortunately, military oriented products and solutions are not readily available or adaptable to the on-stage performance. Hence, designing a peripheral device specific for live musicians is needed. In our model/research, actual transmission of conducting signals was done with a BCE-1 22x 14mm bone conducting exciter in conjunction with a CBL ASSY 3.5mm slim adapter and ample THHN building wire. The adapter was soldered onto the exciter, which may be powered through the 3.5 mm output of user defined signal generating device of the userâs preference. Future testing of the device will be performed and ultimately used in live performance during one of Dr. Robin Coxâs ensemble rehearsals in the IUPUI Department of Music & Arts Technology
An accurate equation of state for the one component plasma in the low coupling regime
An accurate equation of state of the one component plasma is obtained in the
low coupling regime . The accuracy results from a smooth
combination of the well-known hypernetted chain integral equation, Monte Carlo
simulations and asymptotic analytical expressions of the excess internal energy
. In particular, special attention has been brought to describe and take
advantage of finite size effects on Monte Carlo results to get the
thermodynamic limit of . This combined approach reproduces very accurately
the different plasma correlation regimes encountered in this range of values of
. This paper extends to low 's an earlier Monte Carlo
simulation study devoted to strongly coupled systems for ({J.-M. Caillol}, {J. Chem. Phys.} \textbf{111}, 6538 (1999)). Analytical
fits of in the range are provided with a
precision that we claim to be not smaller than . HNC equation and
exact asymptotic expressions are shown to give reliable results for
only in narrow intervals, i.e. and respectively
Monte Carlo simulations of the screening potential of the Yukawa one-component plasma
A Monte Carlo scheme to sample the screening potential H(r) of Yukawa plasmas
notably at short distances is presented. This scheme is based on an importance
sampling technique. Comparisons with former results for the Coulombic
one-component plasma are given. Our Monte Carlo simulations yield an accurate
estimate of H(r) as well for short range and long range interparticle
distances.Comment: to be published in Journal of Physics A: Mathematical and Genera
Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction
Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux)
Semiclassical thermodynamics of scalar fields
We present a systematic semiclassical procedure to compute the partition
function for scalar field theories at finite temperature. The central objects
in our scheme are the solutions of the classical equations of motion in
imaginary time, with spatially independent boundary conditions. Field
fluctuations -- both field deviations around these classical solutions, and
fluctuations of the boundary value of the fields -- are resummed in a Gaussian
approximation. In our final expression for the partition function, this
resummation is reduced to solving certain ordinary differential equations.
Moreover, we show that it is renormalizable with the usual 1-loop counterterms.Comment: 24 pages, 5 postscript figure
Correlated Binomial Models and Correlation Structures
We discuss a general method to construct correlated binomial distributions by
imposing several consistent relations on the joint probability function. We
obtain self-consistency relations for the conditional correlations and
conditional probabilities. The beta-binomial distribution is derived by a
strong symmetric assumption on the conditional correlations. Our derivation
clarifies the 'correlation' structure of the beta-binomial distribution. It is
also possible to study the correlation structures of other probability
distributions of exchangeable (homogeneous) correlated Bernoulli random
variables. We study some distribution functions and discuss their behaviors in
terms of their correlation structures.Comment: 12 pages, 7 figure
Does gravitational wave propagate in the five dimensional space-time with Kaluza-Klein monopole?
The behavior of small perturbations around the Kaluza-Klein monopole in the
five dimensional space-time is investigated. The fact that the odd parity
gravitational wave does not propagate in the five dimensional space-time with
Kaluza-Klein monopole is found provided that the gravitational wave is constant
in the fifth direction.Comment: 10 @ages, LATE
An in-depth evaluation of personal barriers to technology adoption in irrigated agriculture in South Africa
Donor site morbidity of the fasciocutaneous radial forearm flap: what does the patient really bother?
The objective of this study was the evaluation of donor site morbidity in head and neck cancer patients after reconstruction using a free vascularized radial forearm flap with emphasis on subjective complaints. Fifty patients who underwent at least 6 months before a reconstruction using a free vascularized radial forearm flap were asked to fill out two questionnaires regarding cosmetics and sensibility and forearm disabilities. Furthermore, a function test including movement extensions (flexionâextension, ulnarâradial deviation and pronationâsupination), strength (pinch and grip) and temperature (digiti I and V) of the donor and non-donor site were measured and compared. Thirty-five percent of the patients reported no complaints regarding cosmetics and sensibility and 75% mentioned no forearm disabilities. There was no difference in movement extensions, temperature and grip strength between donor and non-donor sites. The difference in pinch strength appeared to be significant (p < 0.001). The total score of the questionnaire on forearm disabilities correlated significantly with extension, pronation and grip strength of the donor arm. Donor site morbidity of the radial forearm flap measured by objective functional tests was limited but subjective self-ratings revealed complaints regarding cosmestics and sensibility and to a lesser extent regarding forearm disability. The present data may be used for solid patient counselling
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