1,088 research outputs found
Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud
The distance to the Large Magellanic Cloud (LMC) represents a key local rung
of the extragalactic distance ladder. Yet, the galaxy's distance modulus has
long been an issue of contention, in particular in view of claims that most
newly determined distance moduli cluster tightly - and with a small spread -
around the "canonical" distance modulus, (m-M)_0 = 18.50 mag. We compiled 233
separate LMC distance determinations published between 1990 and 2013. Our
analysis of the individual distance moduli, as well as of their two-year means
and standard deviations resulting from this largest data set of LMC distance
moduli available to date, focuses specifically on Cepheid and RR Lyrae
variable-star tracer populations, as well as on distance estimates based on
features in the observational Hertzsprung-Russell diagram. We conclude that
strong publication bias is unlikely to have been the main driver of the
majority of published LMC distance moduli. However, for a given distance
tracer, the body of publications leading to the tightly clustered distances is
based on highly non-independent tracer samples and analysis methods, hence
leading to significant correlations among the LMC distances reported in
subsequent articles. Based on a careful, weighted combination, in a statistical
sense, of the main stellar population tracers, we recommend that a slightly
adjusted canonical distance modulus of (m-M)_0 = 18.49 +- 0.09 mag be used for
all practical purposes that require a general distance scale without the need
for accuracies of better than a few percent.Comment: 35 pages (AASTeX preprint format), 5 postscript figures; AJ, in
press. For full database of LMC distance moduli, see
http://astro-expat.info/Data/pubbias.htm
HvZ Website: The Re-Engineering
As part of our Software Design and Development class, we were given a customer and tasked with providing them a product that they specifically request. Our customer was the Humans vs Zombies (HvZ) student group here on campus. They are a group that periodically plays a campus-wide game of tag using their own online resources, and they requested that we provide them a new, updated website. Their problem was that they needed to both update their site and acquire a more maintable version. The current site that they own now is three years old with code that is difficult to decipher
Gravitational conundrum? Dynamical mass segregation versus disruption of binary stars in dense stellar systems
Upon their formation, dynamically cool (collapsing) star clusters will,
within only a few million years, achieve stellar mass segregation for stars
down to a few solar masses, simply because of gravitational two-body
encounters. Since binary systems are, on average, more massive than single
stars, one would expect them to also rapidly mass segregate dynamically.
Contrary to these expectations and based on high-resolution Hubble Space
Telescope observations, we show that the compact, 15-30 Myr-old Large
Magellanic Cloud cluster NGC 1818 exhibits tantalizing hints at the >= 2 sigma
level of significance (> 3 sigma if we assume a power-law secondary-to-primary
mass-ratio distribution) of an increasing fraction of F-star binary systems
(with combined masses of 1.3-1.6 Msun) with increasing distance from the
cluster center, specifically between the inner 10 to 20" (approximately
equivalent to the cluster's core and half-mass radii) and the outer 60 to 80".
If confirmed, this will offer support of the theoretically predicted but thus
far unobserved dynamical disruption processes of the significant population of
'soft' binary systems---with relatively low binding energies compared to the
kinetic energy of their stellar members---in star clusters, which we have
access to here by virtue of the cluster's unique combination of youth and high
stellar density.Comment: Accepted for publication in The Astrophysical Journal; 19 pages in
AASTeX format; 3 figure
Self-reported adverse reactions in 4337 healthcare workers immunizations against novel H1N1 influenza
Purpose: The use of the 2009 H1N1 vaccine has generated much debate concerning safety issues among the general population and physicians. Therefore, we investigated the safety of an inactivated monovalent H1N1 pandemic influenza vaccine Methods: We focused on the H1N1 pandemic influenza vaccine Pandemrix(R) and applied a self reporting questionnaire in a population of healthcare workers (HCWs) and medical students at a major university hospital. Results: In total, 4337 individuals were vaccinated, consisting of 3808 HCWs and 529 medical students. The vaccination rate of the employees was higher than 40%.The majority of individuals were vaccinated in November 2009. In total, 291 of the 4337 vaccinations were reported to lead to one or more adverse reactions (6.7%). Local reactions were reported in 3.8%, myalgia and arthralgia in 3.7%, fatigue in 3.7%, headache in 3.1%. Conclusions: Our data together with available data from several national and international institutions points to a safe pandemic influenza vaccine
The eye contact effect: mechanisms and development
The ‘eye contact effect’ is the phenomenon that perceived eye contact with another human face modulates certain aspects of the concurrent and/or immediately following cognitive processing. In addition, functional imaging studies in adults have revealed that eye contact can modulate activity in structures in the social brain network, and developmental studies show evidence for preferential orienting towards, and processing of, faces with direct gaze from early in life. We review different theories of the eye contact effect and advance a ‘fast-track modulator’ model. Specifically, we hypothesize that perceived eye contact is initially detected by a subcortical route, which then modulates the activation of the social brain as it processes the accompanying detailed sensory information
Transformative Sport Service Research: Linking Sport Services With Well-Being
The performance of sport organizations has been traditionally examined from the perspective of attaining strategic and operational goals (e.g., profitability, sporting performance). However, contemporary examples point to a need to expand sport organizations’ goals through consideration of their contributions to well-being outcomes. The current special issue addresses this need by advancing the theoretical and empirical understanding of transformative sport service research (TSSR), which seeks to understand how personal and collective well-being can be improved through a range of services offered in the sport industry. This introduction article clarifies the scope of TSSR scholarship and then provides a synthesis of findings and implications from the eight articles included in the special issue. The overview concludes with a call for collective efforts to establish a focused body of knowledge that leads sport organizations to integrate the goal of optimizing consumer and employee well-being into the core of their operations
A Polyphasic Approach Reveals Novel Genotypes and Updates the Genetic Structure of the Banana Fusarium Wilt Pathogen
Fusarium oxysporum f. sp. cubense (Foc) is a soil-borne fungus that causes Fusarium wilt, a destructive plant disease that has resulted in devastating economic losses to banana production worldwide. The fungus has a complex evolutionary history and taxonomic repute and consists of three pathogenic races and at least 24 vegetative compatibility groups (VCGs). Surveys conducted in Asia, Africa, the Sultanate of Oman and Mauritius encountered isolates of F. oxysporum pathogenic to banana that were not compatible to any of the known Foc VCGs. Genetic relatedness between the undescribed and known Foc VCGs were determined using a multi-gene phylogeny and diversity array technology (DArT) sequencing. The presence of putative effector genes, the secreted in xylem (SIX) genes, were also determined. Fourteen novel Foc VCGs and 17 single-member VCGs were identified. The multi-gene tree was congruent with the DArT-seq phylogeny and divided the novel VCGs into three clades. Clustering analysis of the DArT-seq data supported the separation of Foc isolates into eight distinct clusters, with the suite of SIX genes mostly conserved within these clusters. Results from this study indicates that Foc is more diverse than hitherto assumed
Recommended from our members
Fatigue Endurance Investigation of Post-processed Surfaces of LPBF Ti-6Al-4V under Flexural Stress
Numerous research works can be found focusing on fatigue properties of AM components,
however most of this literature is focused on uniaxial testing. Because the very few actual
components under uniaxial loading conditions found in any application, it is also important to
investigate fatigue performance under loads that produce combined stresses, such as bending. This
project investigates the fatigue endurance of LPBF Ti-6Al-4V specimens subjected to four
different surface finishing prost-processes (milled, ground, polished and abrasive media). The test
consisted of a force-controlled cyclic load applied on the specimen in a 4-point bending setup until
fracture. The study incorporated mechanical and optical techniques to measure and quantify the
characteristic surface roughness of the post-processes. Additionally, failure mechanisms are
discussed on fractographs. The data analyses suggested that internal defects commonly present in
additively manufactured parts had a more significant impact on the fatigue life than surface
roughness of post-processed parts.Mechanical Engineerin
- …