4,765 research outputs found
Quantum dissipative effects in graphene-like mirrors
We study quantum dissipative effects due to the accelerated motion of a
single, imperfect, zero-width mirror. It is assumed that the microscopic
degrees of freedom on the mirror are confined to it, like in plasma or graphene
sheets. Therefore, the mirror is described by a vacuum polarization tensor
concentrated on a time-dependent surface. Under certain
assumptions about the microscopic model for the mirror, we obtain a rather
general expression for the Euclidean effective action, a functional of the
time-dependent mirror's position, in terms of two invariants that characterize
the tensor . The final result can be written in terms of the
TE and TM reflection coefficients of the mirror, with qualitatively different
contributions coming from them. We apply that general expression to derive the
imaginary part of the `in-out' effective action, which measures dissipative
effects induced by the mirror's motion, in different models, in particular for
an accelerated graphene sheet.Comment: 8 pages, 2 figures. Minor changes, version to be published in Phys.
Rev.
The Medicinal Mushroom Agaricus blazei Murrill: Review of Literature and Pharmaco-Toxicological Problems
Agaricus blazei Murrill (ABM) popularly known as ‘Cogumelo do Sol’ in Brazil, or ‘Himematsutake’ in Japan, is a mushroom native to Brazil, and widely cultivated in Japan for its medicinal uses, so it is now considered as one of the most important edible and culinary-medicinal biotechnological species. It was traditionally used to treat many common diseases like atherosclerosis, hepatitis, hyperlipidemia, diabetes, dermatitis and cancer. In vitro and in vivo ABM has shown immunomodulatory and antimutagenic properties, although the biological pathways and chemical substances involved in its pharmacological activities are still not clear. The polysaccharides phytocomplex is thought to be responsible for its immunostimulant and antitumor properties, probably through an opsonizing biochemical pathway. Clinical studies are positive confirmations, but we are still at the beginning, and there are perplexing concerns especially relative to the content of agaritine. Argantine is a well-known carcinogenic and toxic substance in animals, that must be completely and fully evaluated
Quantum dissipative effects in moving mirrors: a functional approach
We use a functional approach to study various aspects of the quantum
effective dynamics of moving, planar, dispersive mirrors, coupled to scalar or
Dirac fields, in different numbers of dimensions. We first compute the
Euclidean effective action, and use it to derive the imaginary part of the
`in-out' effective action. We also obtain, for the case of the real scalar
field in 1+1 dimensions, the Schwinger-Keldysh effective action and a
semiclassical Langevin equation that describes the motion of the mirror
including noise and dissipative effects due to its coupling to the quantum
fields.Comment: References added. Version to appear in Phys. Rev.
Comparison of different fittings of experimental DSD
Retrieval of a distribution of raindrop sizes from measured drop spectra is critically influenced by the tail of the distribution. The influence of various tail-types is studied with reference to four parameterisations fitted both to the large dropsonlyand to the entire sample of the disdrometer-measured spectra. Results of this preliminary analysis show that the Weibull distribution with a shape parameter greater than oneseems to fit the highest percentages of the measured drop spectra. © 2013 AIP Publishing LLC
Values, ideological attitudes and patriotism
We tested a series of discriminant associations, investigating how dimensions of patriotism (i.e. blind and constructive) differently relate to value orientations, and to ideological attitudes such as Right-Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO). Using an Italian student sample (N = 146) we found that blind patriotism correlated positively with tradition and negatively with univer- salism, whilst constructive patriotism correlated negatively with tradition and positively with universal- ism. Both RWA and SDO correlated negatively with universalism, whilst only RWA was associated with security and tradition and only SDO related positively to power and self-direction. Mediation analyses revealed that most of the effects of value orientations on patriotism were mediated by SDO and RWA
The Functional Derivation of Master Equations
Master equations describe the quantum dynamics of open systems interacting
with an environment. They play an increasingly important role in understanding
the emergence of semiclassical behavior and the generation of entropy, both
being related to quantum decoherence. Presently we derive the exact master
equation for a homogeneous scalar Higgs or inflaton like field coupled to an
environment field represented by an infinite set of harmonic oscillators. Our
aim is to demonstrate a derivation directly from the path integral
representation of the density matrix propagator. Applications and
generalizations of this result are discussed.Comment: 10 pages; LaTex. - Contribution to the workshop Hadron Physics VI,
March 1998, Florianopolis (Brazil); proceedings, E. Ferreira et al., eds.
(World Scientific). Replaced by slightly modified published versio
Survival rate of indirectly bonded brackets using single vs. two-component orthodontic adhesive: A 12-month split-mouth clinical trial
Objective: Compare the bonding survival rate of two distinct bonding materials: Ortho Solo + Gradia LoFlo Resin and single component GC Ortho Connect. Materials and Methods: Indirect bonding fixed appliance treatment was required for 26 consecutive patients, 8 males and 18 females, with a mean age of 22.1 +/- 4.2 years. All patients were treated with SWM (Straight-Wire Mirabella) technique (Sweden and Martina, Due Carrare, Padova, Italy). Each patient's bonding process followed a contralateral pattern. Firstly, a 37 % orthophosphoric acid etching gel was used for 20 s, subsequently the single or two components light-cured adhesives were applied through a split-mouth cross-arch procedure. The patients underwent a 12-month follow-up period and brackets failures were rebounded, but not further included in the study. Statistical analysis was performed to analyse the survival rate of the bonding materials and the influence of the variables, with a significant level of α = 0,05. Results: The GC Connect group was used on 349 teeth, while the Ortho Solo + Gradia group was used on 351 teeth, and the indirect debonding rate was respectively 17.5% and 12.8%. With respect to the total sample, statistically significant values were found for both sex and dental arch. The bracket's survival rate for incisors, canines, premolars and molars was not significant. However, a higher debonding rate was clinically appreciable in upper and lower molars. Conclusion: In a 12-months observation period, considering all maxillary and mandibular teeth the indirect survival rate for the group GC Ortho Connect and Ortho Solo + Gradia was respectively 82.5% and 87.2%. Although the difference was not significant, a pronounced tendency to debonding for the single component group was appreciable from a clinically point of view
Wavelength influence in sub-pixel temperature retrieval using the dual-band technique
The thermal model proposed by Crisp and Baloga (1990) for active lava flows considers thermal flux as a function
of the fractional area of two thermally distinct radiant surfaces. In this model, the larger surface area corresponds
to the cooler crust of the flow and the other, much smaller to fractures in the crust. These cracks temperature
is much higher than the crust one and approaches the temperature of the molten or plastic interior flow.
The dual-band method needs two distinct SWIR (short wave infrared) bands to formulate a two equations system
from the simultaneous solution of the Planck equation in each band. The system solutions consist in the crust
temperature and the fractional area of the hot component. The dual band technique originally builds on data acquired
by sensors (such as Landsat TM) with two SWIR bands only. The use of hyperspectral imaging spectrometers
allows us to test the dual-band technique using different wavelengths in the SWIR range of the spectrum.
DAIS 7915 is equipped with 40 bands into the range 1.54-2.49 nm which represent potential input in dual band
calculation. This study aims to compare results derived by inserting assorted couples of wavelengths into the
equation system. The analysis of these data provides useful information on dual-band technique accuracy
Rainfall estimation and ground clutter rejection with dual polarization weather radar
Conventional radars, used for atmospheric remote sensing, usually operate at a single polarization and frequency to estimate storm parameters such as rainfallrate and water content. Because of the high variability of the drop size distribution conventional radars do not succeed in obtaining detailed information because they just use horizontal reflectivity. The potentiality of the dual-polarized weather radar is investigated, in order to reject the ground-clutter, using differential reflectivity. In this light, a radar meteorology campaign was conducted over the city of Rome (Italy), collecting measurements by the polarimetric Doppler radar Polar 55C and by a raingauge network. The goodness of the results is tested by comparison of radar rainfall estimates with raingauges rainfall measurements
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