1,166 research outputs found
Osteoporosis and rheumatic diseases.
Numerous rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus, systemic sclerosis, dermatomyositis/polymyositis and vasculitis are characterized by osteoporosis and fragility fractures. Inflammatory cytokines, glucocorticoid treatment, immobilization and reduced physical activity due to painful joints and muscle weakness are considered the main risk factors that cause low body mass density values in these diseases. Emerging evidence highlights the role of inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, IL-7 and IL-17, in the regulation of the bone homeostasis. In fact, chronic inflammation is often characterized by an imbalance between bone formation and bone resorption with a net prevalence of osteoclastogenesis, which is an important determinant of bone loss in rheumatic diseases
KWISP: an ultra-sensitive force sensor for the Dark Energy sector
An ultra-sensitive opto-mechanical force sensor has been built and tested in
the optics laboratory at INFN Trieste. Its application to experiments in the
Dark Energy sector, such as those for Chameleon-type WISPs, is particularly
attractive, as it enables a search for their direct coupling to matter. We
present here the main characteristics and the absolute force calibration of the
KWISP (Kinetic WISP detection) sensor. It is based on a thin Si3N4
micro-membrane placed inside a Fabry-Perot optical cavity. By monitoring the
cavity characteristic frequencies it is possible to detect the tiny membrane
displacements caused by an applied force. Far from the mechanical resonant
frequency of the membrane, the measured force sensitivity is 5.0e-14
N/sqrt(Hz), corresponding to a displacement sensitivity of 2.5e-15 m/sqrt(Hz),
while near resonance the sensitivity is 1.5e-14 N/sqrt(Hz), reaching the
estimated thermal limit, or, in terms of displacement, 7.5e-16 N/sqrt(Hz).
These displacement sensitivities are comparable to those that can be achieved
by large interferometric gravitational wave detectors.Comment: 9 pages, 8 figures in colo
Digital holographic interferometry for particle detector diagnostic
In high precision scattering experiments particle tracks must often be reconstructed from a series of hits in successive detector planes. The relative distance between these planes is a critical parameter that must be monitored during operation. To address this problem we have developed a digital holographic interferometer dubbed Holographic Alignment Monitor (HAM) to be used in the MUonE project at CERN. MUonE aims at a precision measurement of the scattering angle between particles after an elastic muon-electron scattering. The HAM is designed to monitor the relative distance between position-sensitive sensor planes inside a MUonE tracking station with a resolution better than the required 10 m. The system uses a 532 nm fiber-coupled laser source both to illuminate a portion of the detector plane (object), and to provide the reference beam. A CMOS image sensor acquires the raw data, and the reconstructed holographic image of the silicon sensor being observed is computed using an algorithm containing a Fourier transform. The relative distance between silicon planes is monitored by superposing successive raw images of the same object on an initial reference one and observing the interference fringes appearing on the reconstructed holographic image. Preliminary tests have yielded a distance resolution of less than 1 m
Detecting solar chameleons through radiation pressure
Light scalar fields can drive the accelerated expansion of the universe.
Hence, they are obvious dark energy candidates. To make such models compatible
with tests of General Relativity in the solar system and "fifth force" searches
on Earth, one needs to screen them. One possibility is the so-called
"chameleon" mechanism, which renders an effective mass depending on the local
matter density. If chameleon particles exist, they can be produced in the sun
and detected on Earth exploiting the equivalent of a radiation pressure. Since
their effective mass scales with the local matter density, chameleons can be
reflected by a dense medium if their effective mass becomes greater than their
total energy. Thus, under appropriate conditions, a flux of solar chameleons
may be sensed by detecting the total instantaneous momentum transferred to a
suitable opto-mechanical force/pressure sensor. We calculate the solar
chameleon spectrum and the reach in the chameleon parameter space of an
experiment using the preliminary results from a force/pressure sensor,
currently under development at INFN Trieste, to be mounted in the focal plane
of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that
such an experiment signifies a pioneering effort probing uncharted chameleon
parameter space.Comment: revised versio
Magnetic Permeability of Constrained Fermionic Vacuum
We obtain using Schwinger's proper time approach the Casimir-Euler-Heisenberg
effective action of fermion fluctuations for the case of an applied magnetic
field. We implement here the compactification of one space dimension into a
circle through anti-periodic boundary condition. Aside of higher order
non-linear field effects we identify a novel contribution to the vacuum
permeability. These contributions are exceedingly small for normal
electromagnetism due to the smallness of the electron Compton wavelength
compared to the size of the compactified dimension, if we take the latter as
the typical size of laboratory cavities, but their presence is thought
provoking, also considering the context of strong interactions.Comment: 8 pages, LaTex, 1 postscript figure, Phys. Let. B in press, slight
text revisions, references adde
Introduction to the Special Issue on the 2009 IEEE International Solid-State Circuits Conference
The papers in this special issue are divided into the following areas: High-Performance Digital; Low-Power Digital; Memory; and Technology Directions. The IEEE International Solid-State Circuits Conference (ISSCC) was held in San Francisco, CA, February 8-12, 2009
Bone Involvement in Systemic Lupus Erythematosus
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a wide variability of clinical manifestations due to the potential involvement of several tissues and internal organs, with a relapsing and remitting course. Dysregulation of innate and adaptive immune systems, due to genetic, hormonal and environmental factors, may be responsible for a broad spectrum of clinical manifestations, affecting quality of life, morbidity and mortality. Bone involvement represents one of the most common cause of morbidity and disability in SLE. Particularly, an increased incidence of osteoporosis, avascular necrosis of bone and osteomyelitis has been observed in SLE patients compared to the general population. Moreover, due to the improvement in diagnosis and therapy, the survival of SLE patient has improved, increasing long-term morbidities, including osteoporosis and related fractures. This review aims to highlight bone manifestations in SLE patients, deepening underlying etiopathogenetic mechanisms, diagnostic tools and available treatment
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