815 research outputs found
Modeling the Behavior of Novice Young Drivers Using Data from In- Vehicle Data Recorders
Novice young drivers suffer from increased crash risk that translates into over-representation in road injuries. A better understanding of the driving behavior of novice young drivers and of their determinants is needed to tackle this problem. To this extent, this study analyzes the behavior of novice young drivers within a Graduated Driver Licensing (GDL) program. Data on driving behavior of novice drivers and their parents is collected using in-vehicle data recorders, which calculate compound risk indices as measures of the risk taking behavior of the various drivers. Data is used to estimate a negative binomial model to identify the major factors that affect the driving behavior of the young drivers. Estimation results suggest that the risk taking behavior of young drivers is influenced by that of their parents and decreases with higher levels of supervised driving and stricter monitoring by the parents
Obtaining research biopsies during pediatric colonoscopy: Safety and adverse events
AIM: To investigate the safety profile of acquiring additional intestinal biopsies for research purposes in children undergoing a medically indicated colonoscopy. METHODS: A retrospective review of 122 pediatric patients who underwent colonoscopy over a 9 mo time period was completed. 38/122 participants consented to a research study in which 4 additional biopsies were obtained, in addition to routine biopsies. The outcomes after colonoscopy were measured in the research participants, and compared to 84 control participants who did not consent for the study. Groups were compared with regard to number of biopsies obtained, underlying diagnosis, and both serious and minor adverse outcomes. Data was collected including: age, gender, race, indication, diagnosis, number of biopsies obtained per case and post procedure adverse events. Medical records were reviewed and a questionnaire was completed by each of the ten gastroenterologists who performed procedures during the study. Physicians were asked about individual patient outcomes to ensure that all adverse events, such as perforation, excessive bleeding, infection, and minor gastrointestinal outcomes, were captured and included. RESULTS: The research group had more biopsies obtained (mean = 13.58 +/- 4.21) compared to controls (mean = 9.33 +/- 4.40),
Volatility of Linear and Nonlinear Time Series
Previous studies indicate that nonlinear properties of Gaussian time series
with long-range correlations, , can be detected and quantified by studying
the correlations in the magnitude series , i.e., the ``volatility''.
However, the origin for this empirical observation still remains unclear, and
the exact relation between the correlations in and the correlations in
is still unknown. Here we find analytical relations between the scaling
exponent of linear series and its magnitude series . Moreover, we
find that nonlinear time series exhibit stronger (or the same) correlations in
the magnitude time series compared to linear time series with the same
two-point correlations. Based on these results we propose a simple model that
generates multifractal time series by explicitly inserting long range
correlations in the magnitude series; the nonlinear multifractal time series is
generated by multiplying a long-range correlated time series (that represents
the magnitude series) with uncorrelated time series [that represents the sign
series ]. Our results of magnitude series correlations may help to
identify linear and nonlinear processes in experimental records.Comment: 7 pages, 5 figure
Mass growth and mergers: direct observations of the luminosity function of LRG satellite galaxies out to z=0.7 from SDSS and BOSS images
We present a statistical study of the luminosity functions of galaxies
surrounding luminous red galaxies (LRGs) at average redshifts =0.34 and
=0.65. The luminosity functions are derived by extracting source photometry
around more than 40,000 LRGs and subtracting foreground and background
contamination using randomly selected control fields. We show that at both
studied redshifts the average luminosity functions of the LRGs and their
satellite galaxies are poorly fitted by a Schechter function due to a
luminosity gap between the centrals and their most luminous satellites. We
utilize a two-component fit of a Schechter function plus a log-normal
distribution to demonstrate that LRGs are typically brighter than their most
luminous satellite by roughly 1.3 magnitudes. This luminosity gap implies that
interactions within LRG environments are typically restricted to minor mergers
with mass ratios of 1:4 or lower. The luminosity functions further imply that
roughly 35% of the mass in the environment is locked in the LRG itself,
supporting the idea that mass growth through major mergers within the
environment is unlikely. Lastly, we show that the luminosity gap may be at
least partially explained by the selection of LRGs as the gap can be reproduced
by sparsely sampling a Schechter function. In that case LRGs may represent only
a small fraction of central galaxies in similar mass halos.Comment: ApJ accepted versio
Light-Heavy Symmetry: Geometric Mass Hierarchy for Three Families
The Universal Seesaw pattern coupled with a LightHeavy
symmetry principle leads to the Diophantine equation , where and distinct. Its unique non-trivial
solution gives rise to the geometric mass hierarchy ,
, for fermion families. This is realized in
a model where the hybrid (yet UpDown symmetric) quark mass
relations play a
crucial role in expressing the CKM mixings in terms of simple mass ratios,
notably .Comment: 12 pages, no figures, Revtex fil
Rhizomatic affective spaces and the therapeutic potential of music in prison: a qualitative meta-synthesis
Research literature supports that music programmes in prisons can have a therapeutic effect in prisoners’ lives that could promote personal development and assist the process towards desistance. The authors use a meta-synthetic approach to examine 12 qualitative articles published worldwide to explore the therapeutic potential of such programmes. The findings suggest that music programmes in prison are perceived by participating prisoners as a liberating process which encourages participation and allows for non-coercive personal development. The therapeutic potential of music programmes is located in the combination of the benefits emanating from the effect and practice of music and the creation of mental, spatial and temporal zones of free expression and those that derive from the egalitarian and non-authoritative approach employed by the facilitators. These findings are discussed along with aspects involved in the provision of offender treatment as well as factors that affect treatment response and engagement
Probing Wolf-Rayet Winds: Chandra/HETG X-Ray Spectra of WR 6
With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines
whose profiles show that the X-rays originate from a uniformly expanding
spherical wind of high X-ray-continuum optical depth. The presence of strong
helium-like forbidden lines places the source of X-ray emission at tens to
hundreds of stellar radii from the photosphere. Variability was present in
X-rays and simultaneous optical photometry, but neither were correlated with
the known period of the system or with each other. An enhanced abundance of
sodium revealed nuclear processed material, a quantity related to the
evolutionary state of the star. The characterization of the extent and nature
of the hot plasma in WR 6 will help to pave the way to a more fundamental
theoretical understanding of the winds and evolution of massive stars.Comment: Accepted by the Astrophysical Journa
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