200 research outputs found
Thermodynamics of hairy black holes in Lovelock gravity
We perform a thorough study of the thermodynamic properties of a class of
Lovelock black holes with conformal scalar hair arising from coupling of a real
scalar field to the dimensionally extended Euler densities. We study the
linearized equations of motion of the theory and describe constraints under
which the theory is free from ghosts/tachyons. We then consider, within the
context of black hole chemistry, the thermodynamics of the hairy black holes in
the Gauss-Bonnet and cubic Lovelock theories. We clarify the connection between
isolated critical points and thermodynamic singularities, finding a one
parameter family of these critical points which occur for well-defined
thermodynamic parameters. We also report on a number of novel results,
including `virtual triple points' and the first example of a
`-line'---a line of second order phase transitions---in black hole
thermodynamics.Comment: 62 pages, 30 figures. Minor changes and typos corrected. Updated to
match published versio
Performance, emissions, and physical characteristics of a rotating combustion aircraft engine, supplement A
Testing was conducted using the basic RC2-75 engine, to which several modifications were incorporated which were designed to reduce the hydrocarbon emissions and reduce the specific fuel consumption. The modifications included close-in surface gap spark plugs, increased compression ratio rotors, and provisions for utilizing either side or peripheral intake ports, or a combination of the two if required. The proposed EPA emissions requirements were met using the normal peripheral porting. The specific fuel economy demonstrated for the modified RC2-75 was 283 g/kW-hr at 75% power and 101 brake mean effective pressure (BMEP) and 272.5 g/kW-hr at 75% power and 111 BMEP. The latter would result from rating the engine for takeoff at 285 hp and 5500 rpm, instead of 6000 rpm
Entanglement Harvesting with Moving Mirrors
We study the phenomenon of entanglement extraction from the vacuum of a
massless scalar field in dimensional spacetime in presence of a moving
Dirichlet boundary condition, i.e. mirror spacetime, using two inertial
Unruh-DeWitt detectors. We consider a variety of non-trivial trajectories for
these accelerating mirrors and find (1) an entanglement inhibition phenomenon
similar to that recently seen for black holes, as well as (2)
trajectory-independent entanglement enhancement in some regimes. We show that
the qualitative result obtained is the same for both linear and derivative
couplings of the detector with the field.Comment: 18 pages, 9 figure
Unruh phenomena and thermalization for qudit detectors
We study Unruh phenomena for a qudit detector coupled to a quantized scalar
field, comparing its response to that of a standard qubit-based Unruh-DeWitt
detector. We show that there are limitations to the utility of the detailed
balance condition as an indicator for Unruh thermality of higher-dimensional
qudit detector models. This can be traced to the fact that a qudit has multiple
possible transition channels between its energy levels, in contrast to the
2-level qubit model. We illustrate these limitations using two types of qutrit
detector models based on the spin-1 representations of and the
non-Hermitian generalization of the Pauli observables (the Heisenberg-Weyl
operators).Comment: 10+5 pages, no figures; RevTeX4-
Parameter estimation of the kinetic α-Pinene isomerization model using the MCSfilter algorithm
This paper aims to illustrate the application of a derivative-free multistart algorithm with coordinate search filter, designated as the MCSFilter algorithm. The problem used in this study is the parameter estimation problem of the kinetic α -pinene isomerization model. This is a well known nonlinear optimization problem (NLP) that has been investigated as a case study for performance testing of most derivative based methods proposed in the literature. Since the MCSFilter algorithm features a stochastic component, it was run ten times to solve the NLP problem. The optimization problem was successfully solved in all the runs and the optimal solution demonstrates that the MCSFilter provides a good quality solution.(undefined)info:eu-repo/semantics/publishedVersio
Three-dimensional dento-skeletal effects of mandibular midline distraction and surgically assisted rapid maxillary expansion:A retrospective study
It was the aim of the study to provide a three-dimensional evaluation of dento-skeletal effects following bone-borne vs tooth-borne mandibular midline distraction (MMD) and tooth-borne surgically assisted rapid maxillary expansion (SARME). A retrospective observational study was conducted. Cone beam computed tomography (CBCT) records were taken pre-operatively (T1), immediately post-distraction (T2) and 1 year post-operatively (T3). All included 30 patients had undergone MMD (20 bone-borne MMD; 10 tooth-borne MMD). A total of 20 bone-borne MMD and 8 tooth-borne MMD patients had simultaneously undergone tooth-borne SARME. At T1 vs T3, canine (p = 0.007; 26.0 ± 2.09 vs 29.2 ± 2.02) and first premolar (p = 0.005; 33.8 ± 2.70 vs 37.0 ± 2.43) showed significant expansion on the tip level for tooth-borne MMD. This was no significant on the apex level, indicating tipping. Bone-borne MMD showed a parallel distraction gap, whereas tooth-borne MMD showed a V-shape. There was a significant (p = 0.017; 138 ± 17.8 vs 141 ± 18.2) inter-condylar axes increase for bone-borne MMD. In conclusion, bone-borne vs tooth-borne MMD and tooth-borne SARME showed stable dento-skeletal effects at 1 year post-operatively. Bone-borne and tooth-borne MMD seemed not to be superior to each other. The choice of distractor type therefore depends more on anatomical and comfort factors.</p
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