3,822 research outputs found
Duality Between Spatial and Angular Shift in Optical Reflection
We report a unified representation of the spatial and angular Goos-Hanchen
and Imbert-Fedorov shifts that occur when a light beam reflects from a plane
interface. We thus reveal the dual nature of spatial and angular shifts in
optical beam reflection. In the Goos-Hanchen case we show theoretically and
experimentally that this unification naturally arises in the context of
reflection from a lossy surface (e.g., a metal).Comment: 4 pages, 3 figure
Hoffmann-Infeld Black Hole Solutions in Lovelock Gravity
Five-dimensional black holes are studied in Lovelock gravity coupled to
Hoffmann-Infeld non-linear electrodynamics. It is shown that some of these
solutions present a double peak behavior of the temperature as a function of
the horizon radius. This feature implies that the evaporation process, though
drastic for a period, leads to an eternal black hole remnant. Moreover, the
form of the caloric curve corresponds to the existence of a plateau in the
evaporation rate, which implies that black holes of intermediate scales turn
out to be unstable. The geometrical aspects, such as the absence of conical
singularity, the structure of horizons, etc. are also discussed. In particular,
solutions that are asymptotically AdS arise for special choices of the
parameters, corresponding to charged solutions of five-dimensional Chern-Simons
gravity.Comment: 6 pages, 5 figures, Revtex4. References added and comments clarified;
version accepted for publicatio
Visualizing the Quantum Interaction Picture in Phase Space
We illustrate the correspondence between the quantum Interaction
Picture-evolution of the state of a quantum system in Hilbert space and a
combination of local and global transformations of its Wigner function in phase
space. To this aim, we consider the time-evolution of a quantized harmonic
oscillator driven by both a linear and a quadratic (in terms of bosonic
creation and annihilation operators) potentials and employ the Magnus series to
derive the exact form of the time-evolution operator. In this case, the
Interaction Picture corresponds to a local transformation of phase
space-reference frame into the one that is co-moving with the Wigner function.Comment: Submitted to New Journal of Physic
Volumetric analysis on MRI and PET images for the early diagnosis of Alzheimer’s disease
In this paper we present the development of a software for the extraction of the hippocampus and surrounding medial-temporal-lobe (MTL) regions from T1-weighted magnetic resonance (MR) and from Positron Emission Tomography (PET) images with no interactive input from the user. With this software we introduce a novel statistical index computed on the intensities in the automatically extracted MTL regions. This index is a measure of gray-matter (GM) atrophy and
allows to: distinguish between (a) patients with Alzheimer’s disease (AD), patients with amnestic mild cognitive impairment (aMCI), (b) patients with amnestic mild
cognitive impairment who will later develop AD in a time frame of 2 years (aMCIconv), and (c) a set of age-matched elderly controls. Once refined, this method could be used to infer about the clinical outcome of aMCI patients
Machine Learning the Cryptocurrency Market
Machine learning and AI-assisted trading have attracted growing interest for the past few years. Here, we use this approach to test the hypothesis that the inefficiency of the cryptocurrency market can be exploited to generate abnormal profits. We analyse daily data for cryptocurrencies for the period between Nov. 2015 and Apr. 2018. We show that simple trading strategies assisted by state-of-the-art machine learning algorithms outperform standard benchmarks. Our results show that non-trivial, but ultimately simple, algorithmic mechanisms can help anticipate the short-term evolution of the cryptocurrency market
DNA damage induced by 7,12-dimethylbenz[a]anthracene in the liver and the mammary gland of rats exposed to polycyclic aromatic hydrocarbon enzyme inducers during perinatal life
The long-lasting modulating effect induced by the prenatal or neonatal exposure to phenobarbital (PB) and aroclor on the genotoxic activity of 7,12-dimethylbenz[a]anthracene (DMBA) in female Sprague-Dawley rats was studied. The effect was measured as DNA damage evaluated in the liver and in the mammary gland of 55-day-old animals, 4 and 24 h after an i.g. injection of 80 mg/kg of DMBA. PB was given per os, i.g. or in drinking water to pregnant females and by i.g. only to neonates or in adult progeny. Aroclor was injected i.g. in prenatal and in neonatal life, and a second dose was given in adult life. Under these experimental conditions it was shown that DNA damage kinetics caused by DMBA are modulated by exposure to PB and, to a minor extent, by aroclor. The amount and persistence of DNA damage were highest when PB was administered to neonates. An average 2-fold increase in the elution constants (K) of DNA in the liver and the mammary gland was observed 4 h after DMBA treatment, as compared to uninduced animals. Repeated enzyme induction by PB seems to reduce DMBA genotoxicity, as shown by a decrease in DNA damage and persistence in the liver and mammary gland. The inducibility of the monooxygenase enzyme system in perinatal life favouring metabolic activation of inactivation of polycyclic aromatic hydrocarbons might be critical in determining individual susceptibility of adult progeny to chemical carcinogenesis by DMB
Input-Output Relations in Optical Cavities: a Simple Point of View
In this work we present a very simple approach to input-output relations in
optical cavities, limiting ourselves to one- and two-photon states of the
field.
After field quantization, we derive the non-unitary transformation between
{\em Inside} and {\em Outside} annihilation and creation operators. Then we
express the most general two-photon state generated by {\em Inside} creation
operators, through base states generated by {\em Outside} creation operators.
After renormalization of coefficients of inside two-photon state, we calculate
the outside photon-number probability distribution in a general case. Finally
we treat with some detail the single mode and symmetrical cavity case.Comment: 34 pages, 5 figures jpg, LaTe
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