17,736 research outputs found
Time Evolution of Non-Lethal Infectious Diseases: A Semi-Continuous Approach
A model describing the dynamics related to the spreading of non-lethal
infectious diseases in a fixed-size population is proposed. The model consists
of a non-linear delay-differential equation describing the time evolution of
the increment in the number of infectious individuals and depends upon a
limited number of parameters. Predictions are in good qualitative agreement
with data on influenza.Comment: 21 page
Posterior moments and quantiles for the normal location model with Laplace prior
We derive explicit expressions for arbitrary moments and quantiles of the posterior distribution of the location parameter eta in the normal location model with Laplace prior, and use the results to approximate the posterior distribution of sums of independent copies of eta
Reduction of gait abnormalities in type 2 diabetic patients due to physical activity: a quantitative evaluation based on statistical gait analysis
The aim of this study is the objective assessment of gait abnormalities in diabetic patients and the quantification of the benefits of physical activity in improving the gait quality. Patients were equipped with foot-switches and knee goniometers and were asked to walk at their natural pace for 2.5 minutes. A statistical gait analysis was performed extracting from hundreds of strides the ‘atypical' cycles, i.e. the cycles which do not show the usual sequence of gait phases (heel contact, flat foot contact, push off, swing), the duration of the heel contact phase and the knee kinematics in the sagittal plane. A sample population of 27 non-neuropathic type 2 diabetic patients was examined before and after attending a light-intensity physical activity program that lasted four months. A fuzzy classifier was used to assign a score to the gait abnormalities of each patient in baseline conditions and after the program completion. More than 50% of the subjects reduced significantly their gait abnormalities and, on the average, the most frequent improvements were the reduction of atypical cycles and heel contact duration. Furthermore we found that, in basal conditions, the left side is more affected by gait abnormalities than the right one (P < 0.003
Atmospheric monitoring in the mm and sub-mm bands for cosmological observations: CASPER2
Cosmological observations from ground at millimetre and sub-millimetre
wavelengths are affected by atmospheric absorption and consequent emission. The
low and high frequency (sky noise) fluctuations of atmospheric performance
imply careful observational strategies and/or instrument technical solutions.
Measurements of atmospheric emission spectra are necessary for accurate
calibration procedures as well as for site testing statistics. CASPER2, an
instrument to explore the 90-450 GHz (3-15 1/cm) spectral region, was developed
and verified its operation in the Alps. A Martin-Puplett Interferometer (MPI)
operates comparing sky radiation, coming from a field of view (fov) of 28
arcminutes (FWHM) collected by a 62-cm in diameter Pressman-Camichel telescope,
with a reference source. The two output ports of the interferometer are
detected by two bolometers cooled down to 300 mK inside a wet cryostat. Three
different and complementary interferometric techniques can be performed with
CASPER2: Amplitude Modulation (AM), Fast-Scan (FS) and Phase Modulation (PM).
An altazimuthal mount allows the sky pointing, possibly co-alligned to the
optical axis of the 2.6-m in diameter telescope of MITO (Millimetre and
Infrared Testagrigia Observatory, Italy). Optimal timescale to average acquired
spectra is inferred by Allan variance analysis at 5 fiducial frequencies. We
present the motivation for and design of the atmospheric spectrometer CASPER2.
The adopted procedure to calibrate the instrument and preliminary performance
of the instrument are described. Instrument capabilities were checked during
the summer observational campaign at MITO in July 2010 by measuring atmospheric
emission spectra with the three different procedures.Comment: 11 pages, 9 figures, 2 tables, Accepted for publication in MNRA
New VLT observations of the Fermi pulsar PSR J1048-5832
PSR J1048-5832 is a Vela-like (P=123.6 ms; tau~20.3 kyr) gamma-ray pulsar
detected by Fermi, at a distance of ~2.7 kpc and with a rotational energy loss
rate dot{E}_{SD} ~2 x 10^{36} erg/s. The PSR J1048-5832 field has been observed
with the VLT in the V and R bands. We used these data to determine the colour
of the object detected closest to the Chandra position (Star D) and confirm
that it is not associated with the pulsar. For the estimated extinction along
the line of sight, inferred from a re-analysis of the Chandra and XMM-Newton
spectra, the fluxes of Star D (V~26.7; R~25.8) imply a -0.13 < (V-R)_0 < 0.6.
This means that the PSR J1048-5832 spectrum would be unusually red compared to
the Vela pulsar.Moreover, the ratio between the unabsorbed optical and X-ray
flux of PSR J1048-5832 would be much higher than for other young pulsars. Thus,
we conclude that Star D is not the PSR J1048-5832 counterpart. We compared the
derived R and V-band upper limits (R>26.4; V>27.6) with the extrapolation of
the X and gamma-ray spectra and constrained the pulsar spectrum at
low-energies. In particular, the VLT upper limits suggest that the pulsar
spectrum could be consistent with a single power-law, stretching from the
gamma-rays to the optical.Comment: 5 pages, 2 figures, accepted for publication on Monthly Notices of
the Royal Astronomical Society Main Journa
In silico prediction of mutant HIV-1 proteases cleaving a target sequence
HIV-1 protease represents an appealing system for directed enzyme re-design,
since it has various different endogenous targets, a relatively simple
structure and it is well studied. Recently Chaudhury and Gray (Structure (2009)
17: 1636 -- 1648) published a computational algorithm to discern the
specificity determining residues of HIV-1 protease. In this paper we present
two computational tools aimed at re-designing HIV-1 protease, derived from the
algorithm of Chaudhuri and Gray. First, we present an energy-only based
methodology to discriminate cleavable and non cleavable peptides for HIV-1
proteases, both wild type and mutant. Secondly, we show an algorithm we
developed to predict mutant HIV-1 proteases capable of cleaving a new target
substrate peptide, different from the natural targets of HIV-1 protease. The
obtained in silico mutant enzymes were analyzed in terms of cleavability and
specificity towards the target peptide using the energy-only methodology. We
found two mutant proteases as best candidates for specificity and cleavability
towards the target sequence
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