1,903 research outputs found
The interplay between voluntary vaccination and reduction of risky behavior: a general behavior-implicit SIR model for vaccine preventable infections
The onset in the last 15 years of behavioral epidemiology has opened many new avenues for epidemiological modelers. In this manuscript we first review two classes of behavioral epidemiology models for vaccine preventable diseases, namely behaviour-implicit SIR models with prevalence-dependent vaccination (at birth and among older individuals), and prevalence-dependent contact rate.
Subsequently, we briefly propose a general framework of behavior–dependent nonlinear and linear Forces of Infection (FoI) valid for a vast family of infectious diseases, and including delays and ‘epidemic memory’ effects.
Finally and mainly, we develop a new general behavioral SIR model. This model combines the two aforementioned types of behavioral phenomena, previously considered only separately, into a single unified model for behavioral responses. The resulting model allows to develop a general phenomenological theory of the effects of behavioral responses within SIR models for endemic infections. In particular, the model allows to complete the picture about the complicate interplay between different behavioral responses acting on different epidemiological parameters in triggering sustained oscillations of vaccine coverage, risky behavior, and infection prevalence
The Interval Kicking Program (IKP) as a Reprogramming Technique for the Soccer Player in an Anterior Cruciate Ligament (ACL) Rehabilitation: A Technical Report
Introduction. We can state as technical-athletic gestural movements that we might call clinical (pivoting, cutting maneuvers, sidestep cuts, changes of direction) associated with ACL injuries. Objective. This technical report was conducted to research methods of reprogramming basic technical skills in the soccer player after anterior cruciate ligament reconstructive surgery. Technical report results. The Interval Kicking Program (IKP) is a model proposed as a neuromotor remodelling of basic gestures and techniques after an ACL injury in soccer player. The teaching progression is ordered regarding the diversified techniques of passing and receiving the ball. The volume, intensity, and progression steps are governed by 1) clinical status (i.e., type of injury, conservative/surgical treatment type, type of sport), 2) performance status, and 3) objective evaluative analysis of periodic follow-ups. The steps provid-ed by the IKP can be 15 and end with the introduction of the player into technical drills with the presence of opponents the first sessions include about 30 minutes of sport-specific, low-intensity exercises, while in the last ones, the volume remains constant, but the intensity and technical complexity of the movements increase. Conclusions. In this technical report, we have highlighted how IKP can be a teaching model for reprogramming basic technical skills in the soccer player after injury. It remains fair to point out how aberrant technical movement partners, side-to-side asymmetries, and postur-al dysfunction are predictive of the risk of compliance and second injury. Further studies and insights are needed to customize the reprogramming of the soccer player’s gestural movements during return to play. © 2023, EDRA S.p.A. All rights reserved
UGC 3995: A Close Pair of Spiral Galaxies
UGC 3995 is a close pair of spiral galaxies whose eastern component hosts a
Seyfert 2 nucleus. We present a detailed analysis of this system using long
slit spectroscopy and narrow (\ha + \nii) as well as broad band (B, R) imaging
and an archive WFPC2 image. The component galaxies reveal surprisingly small
signs of interaction considering their spatial proximity and almost identical
recession velocities, as the bright filament is probably an optical illusion
due to the superposition of the bar of the Seyfert galaxy and of the spiral
arms of the companion. The broad band morphology, a B--R color map, and a
continuum-subtracted \ha + \nii image demonstrate that the western component
UGC 3995B is in front of the Seyfert-hosting component UGC 3995A, partly
obscuring its western side. The small radial velocity difference leaves the
relative motion of the two galaxies largely unconstrained. The observed lack of
major tidal deformations, along with some morphological peculiarities, suggests
that the galaxies are proximate in space but may have recently approached each
other on the plane of the sky. The geometry of the system and the radial
velocity curve at P. A. = 106 suggest that the encounter may be retrograde or,
alternatively, prograde before perigalacticon. The partial overlap of the two
galaxies allows us to estimate the optical thickness of the disk of component
B. We derive an extinction = 0.18 visual magnitudes in the infra-arms parts of
the foreground galaxy disk, and >= 1-1.5 visual magnitudes in correspondence of
the spiral arms.Comment: Accepted for publication in the Astronomical Journal (June 1999
issue
Redshift-Distance Survey of Early-type Galaxies. I. Sample Selection, Properties and Completeness
This is the first in a series of papers describing the recently completed
all-sky redshift-distance survey of nearby early-type galaxies (ENEAR) carried
out for peculiar velocity analysis. The sample is divided into two parts and
consists of 1607 elliptical and lenticular galaxies with cz < 7000 km/s and
with blue magnitudes brighter than m_B=14.5 (ENEARm), and of galaxies in
clusters (ENEARc). Galaxy distances based on the Dn-sigma and Fundamental Plane
(FP) relations are now available for 1359 and 1107 ENEARm galaxies,
respectively, with roughly 80% based on new data gathered by our group. The
Dn-sigma and FP template distance relations are derived by combining 569 and
431 galaxies in 28 clusters, respectively, of which about 60% are based on our
new measurements. The ENEARm redshift-distance survey extends the earlier work
of the 7S and the recent Tully-Fisher surveys sampling a comparable volume. In
subsequent papers of this series we intend to use the ENEAR sample by itself or
in combination with the SFI Tully-Fisher survey to analyze the properties of
the local peculiar velocity field and to test how sensitive the results are to
different sampling and to the distance indicators. We also anticipate that the
homogeneous database assembled will be used for a variety of other applications
and serve as a benchmark for similar studies at high-redshift.Comment: 43 pages, 15 figures, submitted to the Astronomical Journa
Structure of the Galaxies in the NGC 80 Group
BV-bands photometric data obtained at the 6-m telescope of the Special
Astrophysical Observatory are used to analyze the structure of 13 large disk
galaxies in the NGC 80 group. Nine of the 13 galaxies under consideration are
classified by us as lenticular galaxies. The stellar populations in the
galaxies are very different, from old ones with ages of T>10 Gyrs (IC 1541) to
relatively young, with the ages of T<2-3 Gyr (IC 1548, NGC 85). In one case,
current star formation is known (UCM 0018+2216). In most of the galaxies, more
precisely in all of them more luminous than M(B) -18, two-tiered
(`antitruncated') stellar disks are detected, whose radial surface brightness
profiles can be fitted by two exponential segments with different scalelengths
-- shorter near the center and longer at the periphery. All dwarf S0 galaxies
with single-scalelength exponential disks are close companions to giant
galaxies. Except for this fact, no dependence of the properties of S0 galaxies
on distance from the center of the group is found. Morphological traces of
minor merger are found in the lenticular galaxy NGC 85. Basing on the last two
points, we conclude that the most probable mechanisms for the transformation of
spirals into lenticular galaxies in groups are gravitational ones, namely,
minor mergers and tidal interactions.Comment: 24 pages, 9 figures, slightly improved version of the paper published
in the December, 2009, issue of the Astronomy Report
Redshift-distance Survey of Early-type Galaxies: The D_n-sigma Relation
In this paper R-band photometric and velocity dispersion measurements for a
sample of 452 elliptical and S0 galaxies in 28 clusters are used to construct a
template D_n-sigma relation. This template relation is constructed by combining
the data from the 28 clusters, under the assumption that galaxies in different
clusters have similar properties. The photometric and spectroscopic data used
consist of new as well as published measurements, converted to a common system,
as presented in a accompanying paper. The resulting direct relation, corrected
for incompleteness bias, is log{D_n} =1.203 log{sigma} + 1.406; the zero-point
has been defined by requiring distant clusters to be at rest relative to the
CMB. This zero-point is consistent with the value obtained by using the
distance to Virgo as determined by the Cepheid period-luminosity relation. This
new D_n-sigma relation leads to a peculiar velocity of -72 (\pm 189) km/s for
the Coma cluster. The scatter in the distance relation corresponds to a
distance error of about 20%, comparable to the values obtained for the
Fundamental Plane relation. Correlations between the scatter and residuals of
the D_n-sigma relation with other parameters that characterize the cluster
and/or the galaxy stellar population are also analyzed. The direct and inverse
relations presented here have been used in recent studies of the peculiar
velocity field mapped by the ENEAR all-sky sample.Comment: 46 pages, 20 figures, and 7 tables. To appear in AJ, vol. 123, no. 5,
May 200
Gravitational stability and dynamical overheating of stellar disks of galaxies
We use the marginal stability condition for galactic disks and the stellar
velocity dispersion data published by different authors to place upper limits
on the disk local surface density at two radial scalelengths .
Extrapolating these estimates, we constrain the total mass of the disks and
compare these estimates to those based on the photometry and color of stellar
populations. The comparison reveals that the stellar disks of most of spiral
galaxies in our sample cannot be substantially overheated and are therefore
unlikely to have experienced a significant merging event in their history. The
same conclusion applies to some, but not all of the S0 galaxies we consider.
However, a substantial part of the early type galaxies do show the stellar
velocity dispersion well in excess of the gravitational stability threshold
suggesting a major merger event in the past. We find dynamically overheated
disks among both seemingly isolated galaxies and those forming pairs. The ratio
of the marginal stability disk mass estimate to the total galaxy mass within
four radial scalelengths remains within a range of 0.4---0.8. We see no
evidence for a noticeable running of this ratio with either the morphological
type or color index.Comment: 25 pages, 5 figures, accepted to Astronomy Letter
Ascent and Descent Guidance of Multistage Rockets via Pseudospectral Methods
This paper illustrates the trajectory modeling of multistage rockets for both ascent anddescent phases. The computation of solutions is performed by coupling a multiphase optimal-control problem formulation with a transcription performed via Radau pseudospectral meth-ods. Four examples inspired by both historical rockets like the Saturn V, and modern reusablelaunch systems like the Falcon 9 demonstrate the feasibility of the proposed modeling approachfor the rapid prototyping of valid reference solutions
Secondary infall model and dark matter scaling relations in intermediate redshift early - type galaxies
Scaling relations among dark matter (DM) and stellar quantities are a
valuable tool to constrain formation scenarios and the evolution of galactic
structures. However, most of the DM properties are actually not directly
measured, but derived through model dependent mass mapping procedures. It is
therefore crucial to adopt theoretically and observationally well founded
models. We use here an updated version of the secondary infall model (SIM) to
predict the halo density profile, taking into account the effects of angular
momentum, dissipative friction and baryons collapse. The resulting family of
halo profiles depends on one parameter only, the virial mass, and nicely fits
the projected mass and aperture velocity dispersion of a sample of intermediate
redshift lens galaxies. We derive DM related quantities (namely the column
density and the Newtonian acceleration) and investigate their correlations with
stellar mass, luminosity, effective radius and virial mass.Comment: 15 pages, 3 figures, 2 tables, accepted for publication on MNRA
Determination of the Jet Energy Scale at the Collider Detector at Fermilab
A precise determination of the energy scale of jets at the Collider Detector
at Fermilab at the Tevatron collider is described. Jets are used in
many analyses to estimate the energies of partons resulting from the underlying
physics process. Several correction factors are developed to estimate the
original parton energy from the observed jet energy in the calorimeter. The jet
energy response is compared between data and Monte Carlo simulation for various
physics processes, and systematic uncertainties on the jet energy scale are
determined. For jets with transverse momenta above 50 GeV the jet energy scale
is determined with a 3% systematic uncertainty
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