964 research outputs found
Exact renormalization group equation in presence of rescaling anomaly
Wilson's approach to renormalization group is reanalyzed for supersymmetric
Yang-Mills theory. Usual demonstration of exact renormalization group equation
must be modified due to the presence of the so called Konishi anomaly under the
rescaling of superfields. We carry out the explicit computation for N=1 SUSY
Yang-Mills theory with the simpler, gauge invariant regularization method,
recently proposed by Arkani-Hamed and Murayama. The result is that the
Wilsonian action S_M consists of two terms, i.e. the non anomalous term, which
obeys Polchinski's flow equation and Fujikawa-Konishi determinant contribution.
This latter is responsible for Shifman-Vainshtein relation of exact
beta-function.Comment: 19 pages, no figures; an appendix and reference added; typos
correcte
RR Lyrae variables in the globular cluster M3 (NGC5272). I. BVI CCD photometry
New BVI CCD photometry is presented for 60 RR Lyrae variables in the globular
cluster M3. Light curves have been constructed and ephemerides have been
(re)-derived for all of them. Four stars (i.e. V29, V136, V155 and V209),
although recognized as variables, had no previous period determinations. Also,
the period derived for V129 is significantly different from the one published
by Sawyer-Hogg (1973). Light curve parameters, i.e. mean magnitudes, amplitudes
and rise-times, have been derived. The discussion of these results in the
framework of the stellar evolution and pulsation theories will be presented in
a forthcoming paper.Comment: 19 pages, latex, uses mn.sty, 12 encapsulated figures, to be
published in MNRAS, text and figures also available at
http://www.bo.astro.it/bap/BAPhome.html or via anonymous ftp at
ftp://boas3.bo.astro.it/bap/files (bap98-12-textfig.ps
Globular Clusters in the Magellanic Clouds.I:BV CCD-Photometry for 11 Clusters
We present BV CCD-data for 11 intermediate-age LMC clusters; the main
conclusions are: 1. in the (V_to, V_cl,m) and (V-to, (V_to-V_cl,m)) planes the
models yield a good overall description of the data; 2. with the current
sample, it is impossible to firmly choose between "classical" and
"overshooting" models; 3. the separation in colour between the MS band and the
Red He-burning Clump is smaller than predicted by theoretical tracks; 4. the
existence of the so-called "RGB phase-transition (Renzini and Buzzoni 1986)
seems to be confirmed.Comment: 62 pages, 37 figures and tables 6 to 16 available on request,
uuencoded compressed postscript file with tables 1-5 and 17-18 included, BAP
08-1994-020-OA
Evidence of mud diapirism and coral colonies in the ionian sea (central mediterranean) from high resolution chirp sonar survey
A chirp sonar survey in the Ionian Sea investigated the Calabrian margin, the Calabrian accretionary wedge, the Taranto Trench and the Apulian foreland. Shallow tectonics structures have been related to deeper ones, recognised on CROP seismic profiles. The identified echo characters
have been compared with those described in the modern literature and have been related to different kinds of sediments, on the basis of core samples. Based on echo character and morphology we have recognised: 1) A widespread presence of mounds, up to 50 m high, occurring on the Apulian plateau as isolated mounds in the deepest zones (1600-800 m) and in groups in the shallower ones (800-600 m); they have been interpreted as coral mounds, according to a recent discovery of living
deep water coral colonies in this zone. 2) Some mud diapirs, isolated or in groups of two or three elements, widespread in the whole study area. In analogy of what has been observed on the Mediterranean Ridge, their presence suggests the activity of deep tectonic structures (thrusts and
faults) and a reduced thickness (or absence) of Messinian evaporites in this part of the Ionian Sea
Aerosol-based antimicrobial photoinactivation in the lungs: an action spectrum study
AbstractChronic lung infections are among the most diffused human infections, being often associated with multidrug-resistant bacteria. In this framework, the European project "Light4Lungs" aims at synthesizing and testing an inhalable light source to control lung infections by antimicrobial photoinactivation (aPDI), addressing endogenous photosensitizers only (porphyrins) in the representative case of S. aureus and P. aeruginosa. In the search for the best emission characteristics for the aerosolized light source, this work defines and calculates the photo-killing action spectrum for lung aPDI in the exemplary case of cystic fibrosis. This was obtained by applying a semi-theoretical modelling with Monte Carlo simulations, according to previously published methodology related to stomach infections and applied to the infected trachea, bronchi, bronchioles and alveoli. In each of these regions, the two low and high oxygen concentration cases were considered to account for the variability of in vivo conditions, together with the presence of endogenous porphyrins and other relevant absorbers/diffusers inside the illuminated biofilm/mucous layer. Furthermore, an a priori method to obtain the "best illumination wavelengths" was defined, starting from maximizing porphyrin and light absorption at any depth. The obtained action spectrum is peaked at 394 nm and mostly follows porphyrin extinction coefficient behavior. This is confirmed by the results from the best illumination wavelengths, which reinforces the robustness of our approach. These results can offer important indications for the synthesis of the aerosolized light source and definition of its most effective emission spectrum, suggesting a flexible platform to be considered in further applications
A New Version of Reimers' law of Mass Loss Based on a Physical Approach
We present a new semi-empirical relation for the mass loss of cool stellar
winds, which so far has frequently been described by "Reimers' law".
Originally, this relation was based solely on dimensional scaling arguments
without any physical interpretation. In our approach, the wind is assumed to
result from the spill-over of the extended chromosphere, possibly associated
with the action of waves, especially Alfven waves, which are used as guidance
in the derivation of the new formula. We obtain a relation akin to the original
Reimers law, but which includes two new factors. They reflect how the
chromospheric height depends on gravity and how the mechanical energy flux
depends, mainly, on effective temperature. The new relation is tested and
sensitively calibrated by modelling the blue end of the Horizontal Branch of
globular clusters. The most significant difference from mass loss rates
predicted by the Reimers relation is an increase by up to a factor of 3 for
luminous late-type (super-)giants, in good agreement with observations.Comment: 12 pages, 4 figures, accepted by ApJ Letter
A Population of Massive Globular Clusters in NGC 5128
We present velocity dispersion measurements of 14 globular clusters in NGC
5128 (Centarus A) obtained with the MIKE echelle spectrograph on the 6.5m
Magellan Clay telescope. These clusters are among the most luminous globular
clusters in NGC 5128 and have velocity dispersions comparable to the most
massive clusters known in the Local Group, ranging from 10 - 30 km/s. We
describe in detail our cross-correlation measurements, as well as simulations
to quantify the uncertainties. These 14 globular clusters are the brightest NGC
5128 globular clusters with surface photometry and structural parameters
measured from the Hubble Space Telescope. We have used these measurements to
derive masses and mass-to-light ratios for all of these clusters and establish
that the fundamental plane relations for globular clusters extend to an order
of magnitude higher mass than in the Local Group. The mean mass-to-light ratio
for the NGC 5128 clusters is ~3+/-1, higher than measurements for all but the
most massive Local Group clusters. These massive clusters begin to bridge the
mass gap between the most massive star clusters and the lowest-mass galaxies.
We find that the properties of NGC 5128 globular clusters overlap quite well
with the central properties of nucleated dwarf galaxies and ultracompact dwarf
galaxies. As six of these clusters also show evidence for extratidal light, we
hypothesize that at least some of these massive clusters are the nuclei of
tidally stripped dwarfs.Comment: ApJ Accepted, 15 pages, 9 figures, uses emulateapj.st
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