273 research outputs found
Comment on "The black hole final state"
Horowitz and Maldacena have suggested that the unitarity of the black hole
S-matrix can be reconciled with Hawking's semiclassical arguments if a
final-state boundary condition is imposed at the spacelike singularity inside
the black hole. We point out that, in this scenario, departures from unitarity
can arise due to interactions between the collapsing body and the infalling
Hawking radiation inside the event horizon. The amount of information lost when
a black hole evaporates depends on the extent to which these interactions are
entangling.Comment: 4 pages, REVTe
Propagation of uncertainty in atmospheric parameters to hyperspectral unmixing
Atmospheric correction (AC) is important in pre-processing of airborne hyperspectral imagery. AC requires knowledge on the atmospheric state expressed by atmospheric condition parameters. Their values are affected by uncertainties that propagate to the application level. This study investigates the propagation of uncertainty from column water vapor (CWV) and aerosol optical depth (AOD) towards abundance maps obtained by means of spectral unmixing. Both Fully Constrained Least Squares (FCLS) and FCLS with Total Variation (FCLS-TV) are applied. We use five simulated datasets contaminated by various noise levels. Three datasets cover two spectral scenarios with different endmembers. A univariate and a bivariate analysis are carried out on CWV and AOD. The other two datasets are used to analyze the effect of surface albedo. The analysis identifies trends in performance degradation caused by the gradual shift in parameter values from their true value. The maximum achievable performance depends upon spectral characteristics of the datasets, noise level, and surface albedo. As expected, under noisy conditions FCLS-TV performs better than FCLS. Our research opens new perspectives for applications where estimation of reflectance is so far considered to be deterministic
Comment on "Estimate of the vibrational frequencies of spherical virus particles"
This comment corrects some errors which appeared in the calculation of an
elastic sphere eigenenergies. As a result, the symmetry of the mode having the
lowest frequency is changed. Also a direction for calculating the damping of
these modes for embedded elastic spheres is given.Comment: comment L. H. Ford Phys. Rev. E 67 (2003) 05192
Dermatophilose du bétail en République Populaire du Congo
La dermatophilose sĂ©vit au Congo. Elle est grave sur les bovins, particuliĂšrement sur les races europĂ©ennes et leurs mĂ©tis, alors que les N'Dama prĂ©sentent des formes bĂ©nignes. Les moutons peuvent aussi subir des pertes sĂ©vĂšres. FrĂ©quente chez les chevaux, elle y demeure sans grande gravitĂ©. Aucun cas n'a Ă©tĂ© observĂ© chez le porc. Les tests rĂ©alisĂ©s en laboratoire confirment que les pĂ©nicillines demeurent les antibiotiques les plus actifs in vitro. Mais in vivo, elles peuvent ĂȘtre incapables de dĂ©barrasser dĂ©finitivement les animaux de Dermatophilus congolensi
Electron-Phonon Dynamics in an Ensemble of Nearly Isolated Nanoparticles
We investigate the electron population dynamics in an ensemble of nearly
isolated insulating nanoparticles, each nanoparticle modeled as an electronic
two-level system coupled to a single vibrational mode. We find that at short
times the ensemble-averaged excited-state population oscillates but has a
decaying envelope. At long times, the oscillations become purely sinusoidal
about a ``plateau'' population, with a frequency determined by the
electron-phonon interaction strength, and with an envelope that decays
algebraically as t^-{1/2} We use this theory to predict electron-phonon
dynamics in an ensemble of Y_2 O_3 nanoparticles.Comment: 11 pages, 3 figure
High-Velocity clouds in the galactic all sky survey. i. catalog
We present a catalog of high-velocity clouds (HVCs) from the Galactic All Sky Survey (GASS) of southern sky neutral hydrogen, which has 57 mK sensitivity and 1 km s-1 velocity resolution and was obtained with the Parkes Telescope. Our catalog has been derived from the stray-radiation-corrected second release of GASS. We describe the data and our method of identifying HVCs and analyze the overall properties of the GASS population. We catalog a total of 1693 HVCs at declinations <0°, including 1111 positive velocity HVCs and 582 negative velocity HVCs. Our catalog also includes 295 anomalous velocity clouds (AVCs). The cloud line-widths of our HVC population have a median FWHM of âŒ19 km s-1, which is lower than that found in previous surveys. The completeness of our catalog is above 95% based on comparison with the HIPASS catalog of HVCs upon which we improve by an order of magnitude in spectral resolution. We find 758 new HVCs and AVCs with no HIPASS counterpart. The GASS catalog will shed unprecedented light on the distribution and kinematic structure of southern sky HVCs, as well as delve further into the cloud populations that make up the anomalous velocity gas of the Milky Wa
The Minimal Supersymmetric Fat Higgs Model
We present a calculable supersymmetric theory of a composite ``fat'' Higgs
boson. Electroweak symmetry is broken dynamically through a new gauge
interaction that becomes strong at an intermediate scale. The Higgs mass can
easily be 200-450 GeV along with the superpartner masses, solving the
supersymmetric little hierarchy problem. We explicitly verify that the model is
consistent with precision electroweak data without fine-tuning. Gauge coupling
unification can be maintained despite the inherently strong dynamics involved
in electroweak symmetry breaking. Supersymmetrizing the Standard Model
therefore does not imply a light Higgs mass, contrary to the lore in the
literature. The Higgs sector of the minimal Fat Higgs model has a mass spectrum
that is distinctly different from the Minimal Supersymmetric Standard Model.Comment: 13 pages, 5 figures, REVTe
Link between shear modulus and enthalpy changes of Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 high entropy bulk metallic glass
Mechanical and thermal properties of materials are intricately linked. Particularly, this fully applies to metallic glasses. In this work, we study shear modulus behavior and heat effects occurring upon heating up of Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 high entropy bulk metallic glass up to the full crystallization. In the framework of the Interstitialcy theory, we show that shear modulus relaxation data can be applied to quantitatively predict exo- and endothermal effects related to structural relaxation, glass transition and crystallization of this high entropy metallic glass. This fact suggests that the underlying physical mechanism responsible for this link can be conditioned by the relaxation of the system of structural defects, which by their properties are similar to dumbbell interstitials in metals.Peer ReviewedPostprint (author's final draft
Comparative study on composition of insect in close and open nursery of Federal College of Forestry Jos, Plateau State, Nigeria
Nursery being an area where young plants are raised before sowing or transplanting in gardens or field contains rich insect assemblages whose composition and abundance is under researched even in research institutes. Thus, the comparative study on the composition of insect in close and open nursery of Federal College of Forestry Jos, Plateau State, Nigeria was carried out in May 2015 in relation to the abundance and diversity of insect using pitfall trap and hand-picking sampling techniques. A total of 2,052 individuals distributed into 13 orders, 39 families, 50 genera and 55 species were collected. 1,557 (75.9%) individuals were collected from the open nursery (with: 13 orders, 39 families, 41 genera and 46 species) while, 495 (24.1%) individuals were found in the close nursery (with: 11 orders, 27 families, 38 genera and 47 species). Five individuals could not be identified beyond class and order levels. The distribution of insect taxa in descending order showed that Hymenoptera (62.8%), Coleoptera (11.1%) and Orthoptera (10.1%) are the most dominant, with Hymenoptera occurring the most in both sites. There was no significant difference (P > 0.05) in the pooled abundance of insect from both sampling techniques between the two nursery types. Although, insect abundance from pitfall trap collection between the two nursery types showed a significant difference (t= -2.494, df = 8, P = 0.03729) while, no significant difference (t= 1.0263, df = 8, P= 0.3348) for hand-picked insect between the two nursery types. To this end, this study shows that the nursery of Federal College of Forestry Jos is healthy due to the abundant and diverse insect species recorded in which the phytophagus individuals are the most dominant group, but are kept under check by the predaceous ones. The pitfall trap was a more efficient collection technique and should be used by insect collectors.Keywords: Close and open nursery, insect, pitfall trap, hand-pickin
Kasner and Mixmaster behavior in universes with equation of state w \ge 1
We consider cosmological models with a scalar field with equation of state
that contract towards a big crunch singularity, as in recent cyclic
and ekpyrotic scenarios. We show that chaotic mixmaster oscillations due to
anisotropy and curvature are suppressed, and the contraction is described by a
homogeneous and isotropic Friedmann equation if . We generalize the
results to theories where the scalar field couples to p-forms and show that
there exists a finite value of , depending on the p-forms, such that chaotic
oscillations are suppressed. We show that orbifold compactification also
contributes to suppressing chaotic behavior. In particular, chaos is avoided in
contracting heterotic M-theory models if at the crunch.Comment: 25 pages, 2 figures, minor changes, references adde
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