256 research outputs found
Functional approach to the electromagnetic response function: the Longitudinal Channel
In this paper we address the (charge) longitudinal electromagnetic response
for a homogeneous system of nucleons interacting via meson exchanges in the
functional framework. This approach warrants consistency if the calculation is
carried on order-by-order in the mesonic loop expansion with RPA-dressed
mesonic propagators. At the 1-loop order and considering pion, rho and omega
exchanges we obtain a quenching of the response, in line with the experimental
results.Comment: RevTeX, 18 figures available upon request - to be published in
Physical Review
Fermion propagators in space-time
The one- and the two-particle propagators for an infinite non-interacting
Fermi system are studied as functions of space-time coordinates. Their
behaviour at the origin and in the asymptotic region is discussed, as is their
scaling in the Fermi momentum. Both propagators are shown to have a divergence
at equal times. The impact of the interaction among the fermions on their
momentum distribution, on their pair correlation function and, hence, on the
Coulomb sum rule is explored using a phenomenological model. Finally the
problem of how the confinement is reflected in the momentum distribution of the
system's constituents is briefly addressed.Comment: 26 pages, 9 figures, accepted for publication on Phys. Rev.
Revisiting the role of GSK3, a modulator of innate immunity, in idiopathic inclusion body myositis
Idiopathic or sporadic inclusion body myositis (IBM) is the leading age-related (onset > 50 years of age) autoimmune muscular pathology, resulting in significant debilitation in affected individuals. Once viewed as primarily a degenerative disorder, it is now evident that much like several other neuro-muscular degenerative disorders, IBM has a major autoinflammatory component resulting in chronic inflammation-induced muscle destruction. Thus, IBM is now considered primarily an inflammatory pathology. To date, there is no effective treatment for sporadic inclusion body myositis, and little is understood about the pathology at the molecular level, which would offer the best hopes of at least slowing down the degenerative process. Among the previously examined potential molecular players in IBM is glycogen synthase kinase (GSK)-3, whose role in promoting TAU phosphorylation and inclusion bodies in Alzheimer’s disease is well known. This review looks to re-examine the role of GSK3 in IBM, not strictly as a promoter of TAU and Abeta inclusions, but as a novel player in the innate immune system, discussing some of the recent roles discovered for this well-studied kinase in inflammatory-mediated pathology
A study on Satellite-to-Ground Propagation in Urban Environment
Non-Terrestrial Networks are going to play an important role in future 6G
wireless networks to enhance global connectivity a performance in cooperation
with terrestrial networks. In order to properly design and deploy
non-terrestrial networks, the satellite-to-ground channel must be properly
characterized, with particular focus on the urban environment. This paper uses
a Ray-Tracing simulation tool to analyze the primary propagation mechanisms and
the behaviour of the Rician K-factor as a function of satellite position in a
reference urban environment. Non-specular reflection due to surface
irregularities emerges as a primary propagation mechanism in non-line-of-sight
cases. Additionally, the Rician K-factor shows a slightly increasing trend with
elevation angle, in contrast to previous studies.Comment: 4 pages, 4 figure
Singular Structure and Enhanced Friedel Oscillations in the Two-Dimensional Electron Gas
We calculate the leading order corrections (in ) to the static
polarization , with dynamically screened interactions, for the
two-dimensional electron gas. The corresponding diagrams all exhibit singular
logarithmic behavior in their derivatives at and provide significant
enhancement to the proper polarization particularly at low densities. At a
density of , the contribution from the leading order {\em fluctuational}
diagrams exceeds both the zeroth order (Lindhard) response and the self-energy
and exchange contributions. We comment on the importance of these diagrams in
two-dimensions and make comparisons to an equivalent three-dimensional electron
gas; we also consider the impact these finding have on computed
to all orders in perturbation theory
Expression profiling of ANKRD1 in rhabdomyosarcoma cell lines
Introduction: Rhabdomyosarcoma (RMS) is the most common soft tissue
malignancy in children and adolescents. Respecting the age
of the patients and the tumor aggressiveness, investigation
of the molecular mechanisms of RMS tumorigenesis is
essential, most notably due to the possible identification of
novel therapeutic targets. To contribute to a better
understanding of the molecular pathology of RMS, we
investigated ANKRD1 (ankyrin repeat domain 1) gene,
considered a potential RMS diagnostic marker. The
changes in its expression are related to carcinogenesis and
resistance to chemotherapy in several types of tumors.EACR 2023: Innovative Cancer Science, 12-15 June 2023, Torino, Ital
Autophagic degradation of farnesylated prelamin A as a therapeutic approach to lamin-linked progeria
Farnesylated prelamin A is a processing intermediate produced in the lamin A maturation pathway. Accumulation of a truncated farnesylated prelamin A form, called progerin, is a hallmark of the severe premature ageing syndrome, Hutchinson-Gilford progeria. Progerin elicits toxic effects in cells, leading to chromatin damage and cellular senescence and ultimately causes skin and endothelial defects, bone resorption, lipodystrophy and accelerated ageing. Knowledge of the mechanism underlying prelamin A turnover is critical for the development of clinically effective protein inhibitors that can avoid accumulation to toxic levels without impairing lamin A/C expression, which is essential for normal biological functions. Little is known about specific molecules that may target farnesylated prelamin A to elicit protein degradation. Here, we report the discovery of rapamycin as a novel inhibitor of progerin, which dramatically and selectively decreases protein levels through a mechanism involving autophagic degradation. Rapamycin treatment of progeria cells lowers progerin, as well as wild-type prelamin A levels, and rescues the chromatin phenotype of cultured fibroblasts, including histone methylation status and BAF and LAP2α distribution patterns. Importantly, rapamycin treatment does not affect lamin C protein levels, but increases the relative expression of the prelamin A endoprotease ZMPSTE24. Thus, rapamycin, an antibiotic belonging to the class of macrolides, previously found to increase longevity in mouse models, can serve as a therapeutic tool, to eliminate progerin, avoid farnesylated prelamin A accumulation, and restore chromatin dynamics in progeroid laminopathies
Quasielastic Electron Scattering from Nuclei: Random-Phase vs. Ring Approximations
We investigate the extent to which the nuclear transverse response to
electron scattering in the quasielastic region, evaluated in the random-phase
approximation can be described by ring approximation calculations. Different
effective interactions based on a standard model of the type g'+V_pi+V_rho are
employed. For each momentum transfer, we have obtained the value of g'_0
permitting the ring response to match the position of the peak and/or the
non-energy weighted sum rule provided by the random-phase approach has been
obtained. It is found that, in general, it is not possible to reproduce both
magnitudes simultaneously for a given g'_0 value.Comment: 7 pages, 4 Postscript figures, to appear in Physical Review
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