2,994 research outputs found
Path integrals and degrees of freedom in many-body systems and relativistic field theories
The identification of physical degrees of freedom is sometimes obscured in
the path integral formalism, and this makes it difficult to impose some
constraints or to do some approximations. I review a number of cases where the
difficulty is overcame by deriving the path integral from the operator form of
the partition function after such identification has been made.Comment: 15 pages, volume in honor of prof.Yu.A.Simono
Boson Dominance in nuclei
We present a new method of bosonization of fermion systems applicable when
the partition function is dominated by composite bosons. Restricting the
partition function to such states we get an euclidean bosonic action from which
we derive the Hamiltonian. Such a procedure respects all the fermion
symmetries, in particular fermion number conservation, and provides a boson
mapping of all fermion operators.Comment: 12 page
Numerical study of the scaling properties of SU(2) lattice gauge theory in Palumbo non-compact regularization
In the framework of a non-compact lattice regularization of nonabelian gauge
theories we look, in the SU(2) case, for the scaling window through the
analysis of the ratio of two masses of hadronic states. In the two-dimensional
parameter space of the theory we find the region where the ratio is constant,
and equal to the one in the Wilson regularization. In the scaling region we
calculate the lattice spacing, finding it at least 20% larger than in the
Wilson case; therefore the simulated physical volume is larger.Comment: 24 pages, 7 figure
Variable phenotype in 17q12 microdeletions: Clinical and molecular characterization of a new case
Microdeletions of 17q12 including the hepatocyte nuclear factor 1 beta (HNF1B) gene, as well as point mutations
of this gene, are associated with the Renal Cysts and Diabetes syndrome (RCAD, OMIM 137920) and genitourinary
alterations. Also, microdeletions encompassing HNF1B were identified as a cause of Mayer\u2013Rokitansky\u2013
K\ufcster\u2013Hauser Syndrome (MRKH, OMIM277000) in females and, recently,were associatedwith intellectual disability,
autistic features, cerebral anomaly and facial dysmorphisms.
In this report, we describe a boywith a deletion in 17q12 region detected by SNP array, encompassing the HNF1B
gene, that showed dysmorphic features, intellectual disability (ID), serious speech delay and autistic features. In
addition, obesity was observed. In order to study the parental origin of the rearrangement, we analyzed selected
SNPs in the deleted area in the patient and his parents, showing Mendelian incompatibilities suggesting a de
novo deletion on the chromosome of maternal origin.
Our case confirms the incomplete penetrance and variable expressivity of this deletion, its complex clinical variability,
and strengthens the evidence that ID and stereotyped behaviors may be part of the phenotypic spectrum
characterizing the affected patients. Also, it is useful to further delineate the phenotypes associated to the deletion
being the first case in which obesity has been documented. We present a genotype\u2013phenotype correlation
discussing the possible role of some genes, encompassed by the deletion, in the etiology of the observed
phenotypes
Photometry of the Oort Cloud comet C/2009 P1(Garradd): pre-perihelion observations at 5.7 and 2.5 AU
The aim of this paper is to contribute to the characterization of the general properties of the Long Period Comets (LPCs) family, and in particular to report on the dust environment of comet C/2009 P1 (Garradd).
The comet was observed at two epochs pre-perihelion, at ~6 AU and at ~2.5 AU: broad-band images have been used to investigate its coma morphology and properties and to model the dust production rate.
Comet C/2009 P1 (Garradd) is one of the most active and âdust producingâ LPCs ever observed, even at the large heliocentric distance rh~6 AU. Its coma presents a complex morphology, with subtle structures underlying the classical fan-shaped tail, and, at rh~2.5 AU, also jet-like structures and spiralling outflows. In the reference aperture of radius Ï=5°Ă104 km, the R-AfÏ is 3693±156 cm and 6368±412 cm, in August 2010 (rh~6 AU) and July 2011 (rh~2.5 AU), respectively. The application of a first order photometric model, under realistic assumptions on grain geometric albedo, power-law dust size distribution, phase darkening function and grain dust outflow velocity, yielded a measure of the dust production rate for the two epochs of observation of Qd=7.27Ă102 kg/s and Qd=1.37Ă103 kg/s, respectively, for a reference outflow dust velocity of vsmall=25 m/s for small (0.1â10 ”m) grains and vlarge=1 m/s for large (10 ”mâ1 cm) grains.
These results suggest that comet Garradd is one of the most active minor bodies observed in recent years, highly contributing to the continuous replenishment of the Interplanetary Dust Complex also in the outer Solar System, and pose important constraints on the mechanism(s) driving the cometary activity at large heliocentric distances
XMM-Newton observations of ULIRGs I: A Compton-thick AGN in IRAS19254-7245
We present the XMM-Newton observation of the merging system IRAS 19254-7245,
also known as The Superantennae, whose southern nucleus is classified as a
Seyfert 2 galaxy. The XMM-Newton data have allowed us to perform a detailed
X-ray imaging and spectral analysis of this system. We clearly detect, for the
first time in this system, a strong EW ~ 1.4 keV Fe emission line at 6.49+/-0.1
keV (rest-frame). The X-ray spectrum requires a soft thermal component (kT~0.9
keV; L(0.5-2) ~ 4E41 cgs), likely associated with the starburst, and a hard
power-law continuum above 2 keV (observed L(2-10) ~ 4E42 cgs). We confirm the
flatness of this latter component, already noted in previous ASCA data. This
flatness, together with the detection of the strong Fe-Kalpha line and other
broad band indicators, suggest the presence of a Compton-thick AGN with
intrinsic luminosity > 1E44 cgs. We show that a Compton-thick model can
perfectly reproduce the X-ray spectral properties of this object.Comment: 6 pages, 4 figures, Latex manuscript, Accepted for publication in
Astronomy and Astrophysic
Thermal issues for the optical transition radiation screen for the ELI-NP compton gamma source
A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with a laser beam in two interaction points. Electron beam spot size is measured with Optical Transition Radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the materia
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