921 research outputs found
A non-geodesic motion in the R^-1 theory of gravity tuned with observations
In the general picture of high order theories of gravity, recently, the R^-1
theory has been analyzed in two different frameworks. In this letter a third
context is added, considering an explicit coupling between the R^-1 function of
the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion
of test particles which, in principle, could be connected with Dark Matter and
Pioneer anomaly problems.Comment: Accepted for Modern Physics Letters
An application of multi-level DC-link converter for optimised permutation control of PV sources under partial shading
The paper describes application of a multi-level DC-link converter in overcoming the problem of partially shaded series-connected PV sources. The converter control engages a permutation algorithm which enables each PV source of the string to produce the maximum power. The main features of the system are: (i) a continual operation of all PV sources, shaded and non-shaded, at their maximum power points, (ii) delivery of all extracted power from PV sources to the load and (ii) generation of multi-level output voltage waveform with a low total harmonic distortion
Behavior of Some Earth Dams on Liquefiable Soil
The 1977 March 4 Vrancea earthquake emphasized several zones with liquefiable materials on Romanian territory. Some earth dams of such zones, placed to over 200 km from the earthquake epicenter were damaged. Important hydropower works are at present in different design or construction stages in such area, comprising long earth dams. The Seismic analysis procedure applied to their design was based on the finite element method. Some characteristic cross - sections of the earth dams in different versions have been studied. The analysed sections had different shapes (with and without stabilizing benches downstream) and included different zoning of the materials (sand fine sand and free draining materials). The analyses pointed out the importance of the drainage blanket at the base of the dam for the increase of the liquefaction strength capacity of the soil - structure system. Some improvement works in certain zones of the foundation soil resulted as being necessary
Interferometer Response to Scalar Gravitational Waves
It was recently suggested that the magnetic component of Gravitational Waves
(GWs) is relevant in the evaluation of frequency response functions of
gravitational interferometers. In this paper we extend the analysis to the
magnetic component of the scalar mode of GWs which arise from scalar-tensor
gravity theory. In the low-frequency approximation, the response function of
ground-based interferometers is calculated. The angular dependence of the
electric and magnetic contributions to the response function is discussed.
Finally, for an arbitrary frequency range, the proper distance between two test
masses is calculated and its usefulness in the high-frequency limit for
space-based interferometers is briefly considered.Comment: Accepted for publication by Int. Journ. Mod. Phys. D. Final versio
The burden of cardiovascular disease associated with PM2.5 exposure in the Portuguese population
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A precise response function for the magnetic component of Gravitational Waves in Scalar-Tensor Gravity
The important issue of the magnetic component of gravitational waves (GWs)
has been considered in various papers in the literature. From such analyses, it
resulted that such a magnetic component becomes particularly important in the
high frequency portion of the frequency range of ground based interferometers
for GWs which arises from standard General Theory of Relativity (GTR).
Recently, such a magnetic component has been extended to GWs arising from
Scalar-Tensor Gravity (STG) too. After a review of some important issues on GWs
in STG, in this paper we re-analyse the magnetic component in the framework of
STG from a different point of view, by correcting an error in a previous paper
and by releasing a more precise response function. In this way, we also show
that if one neglects the magnetic contribution considering only the
low-frequency approximation of the electric contribution, an important part of
the signal could be, in principle, lost. The determination of a more precise
response function for the magnetic contribution is important also in the
framework of the possibility to distinguish other gravitational theories from
GTR. At the end of the paper an expansion of the main results is also shown in
order to recall the presence of the magnetic component in GRT too.Comment: Accepted for publication in Physical Review D, to be published during
2011. 36 pages, in this second version typos have been corrected and
references have been update
Three new Alpha1-Antitrypsin deficiency variants help to define a C-Terminal region regulating conformational change and polymerization
Alpha1-antitrypsin (AAT) deficiency is a hereditary disorder associated with reduced AAT plasma levels, predisposing adults to pulmonary emphysema. The most common genetic AAT variants found in patients are the mildly deficient S and the severely deficient Z alleles, but several other pathogenic rare alleles have been reported. While the plasma AAT deficiency is a common trait of the disease, only a few AAT variants, including the prototypic Z AAT and some rare variants, form cytotoxic polymers in the endoplasmic reticulum of hepatocytes and predispose to liver disease. Here we report the identification of three new rare AAT variants associated to reduced plasma levels and characterize their molecular behaviour in cellular models. The variants, called Mpisa (Lys259Ile), Etaurisano (Lys368Glu) and Yorzinuovi (Pro391His), showed reduced secretion compared to control M AAT, and accumulated to different extents in the cells as ordered polymeric structures resembling those formed by the Z variant. Structural analysis of the mutations showed that they may facilitate polymerization both by loosening ‘latch’ interactions constraining the AAT reactive loop and through effects on core packing. In conclusion, the new AAT deficiency variants, besides increasing the risk of lung disease, may predispose to liver disease, particularly if associated with the common Z variant. The new mutations cluster structurally, thus defining a region of the AAT molecule critical for regulating its conformational state
Extension of the frequency-range of interferometers for the ''magnetic'' components of gravitational waves?
Recently, with an enlighting treatment, Baskaran and Grishchuk have shown the
presence and importance of the so-called ``magnetic'' components of
gravitational waves (GWs), which have to be taken into account in the context
of the total response functions of interferometers for GWs propagating from
arbitrary directions. In this paper the analysis of the response functions for
the magnetic components is generalized in its full frequency dependence, while
in the work of Baskaran and Grishchuk the response functions were computed only
in the approximation of wavelength much larger than the linear dimensions of
the interferometer. It is also shown that the response functions to the
magnetic components grow at high frequencies, differently from the values of
the response functions to the well known ordinary components that decrease at
high frequencies. Thus the magnetic components could in principle become the
dominant part of the signal at high frequencies. This is important for a
potential detection of the signal at high frequencies and confirms that the
magnetic contributions must be taken into account in the data analysis. More,
the fact that the response functions of the magnetic components grow at high
frequencies shows that, in principle, the frequency-range of Earth-based
interferometers could extend to frequencies over 10000 Hz.Comment: Accepted for the International Journal of Modern Physics
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