777 research outputs found
Racial/Ethnic Disparities in Infectious Disease Hospitalizations in Arizona
Infectious disease (ID) hospitalizations in Arizona, a diverse population with nearly complete race/ethnicity data, were analyzed using the State Inpatient Database for 2005-2008. ID hospitalizations rates were calculated and compared by ID group, race/ethnicity, age, and sex. During 2005-2008, there were 383,597 ID hospitalizations reported in Arizona, resulting in an age-adjusted rate of 1498.1 per 100,000 persons. A range of racial/ethnic disparities in ID hospitalization rates were noted. Persons of Native American and black race/ethnicity had overall ID hospitalization rates higher than the rate for persons of white race/ethnicity; persons of Asian or Pacific Islander race/ethnicity had a lower rate. The lower respiratory tract infection (LRTI) hospitalization rate was the highest rate of all ID groups, followed by cellulitis and septicemia. Persons of black and Native American race had higher LRTI hospitalization rates than persons of white race. Racial/ethnic disparities persist for ID hospitalizations in Arizona. Persons of Native American and black race/ethnicity experience high age-adjusted rates of ID hospitalization. Prevention efforts should focus on high risk race/ethnicity groups and disease groups
Islamophobia and Twitter: A Typology of Online Hate Against Muslims on Social Media
The Woolwich attack in May 2013 has led to a spate of hate crimes committed against Muslim communities in the United Kingdom. These incidents include Muslim women being targeted for wearing the headscarf and mosques being vandalized. While street level Islamophobia remains an important area of investigation, an equally disturbing picture is emerging with the rise in online anti-Muslim abuse. This article argues that online Islamophobia must be given the same level of attention as street level Islamophobia. It examines 500 tweets from 100 different Twitter users to examine how Muslims are being viewed and targeted by perpetrators of online abuse via the Twitter search engine, and offers a typology of offender characteristics
Brownian Carnot engine
The Carnot cycle imposes a fundamental upper limit to the efficiency of a
macroscopic motor operating between two thermal baths. However, this bound
needs to be reinterpreted at microscopic scales, where molecular bio-motors and
some artificial micro-engines operate. As described by stochastic
thermodynamics, energy transfers in microscopic systems are random and thermal
fluctuations induce transient decreases of entropy, allowing for possible
violations of the Carnot limit. Despite its potential relevance for the
development of a thermodynamics of small systems, an experimental study of
microscopic Carnot engines is still lacking. Here we report on an experimental
realization of a Carnot engine with a single optically trapped Brownian
particle as working substance. We present an exhaustive study of the energetics
of the engine and analyze the fluctuations of the finite-time efficiency,
showing that the Carnot bound can be surpassed for a small number of
non-equilibrium cycles. As its macroscopic counterpart, the energetics of our
Carnot device exhibits basic properties that one would expect to observe in any
microscopic energy transducer operating with baths at different temperatures.
Our results characterize the sources of irreversibility in the engine and the
statistical properties of the efficiency -an insight that could inspire novel
strategies in the design of efficient nano-motors.Comment: 7 pages, 7 figure
Astrometry with the Keck-Interferometer: the ASTRA project and its science
The sensitivity and astrometry upgrade ASTRA of the Keck Interferometer is
introduced. After a brief overview of the underlying interferometric
principles, the technology and concepts of the upgrade are presented. The
interferometric dual-field technology of ASTRA will provide the KI with the
means to observe two objects simultaneously, and measure the distance between
them with a precision eventually better than 100 uas. This astrometric
functionality of ASTRA will add a unique observing tool to fields of
astrophysical research as diverse as exo-planetary kinematics, binary
astrometry, and the investigation of stars accelerated by the massive black
hole in the center of the Milky Way as discussed in this contribution.Comment: 22 pages, 10 figures (low resolution), contribution to the
summerschool "Astrometry and Imaging with the Very Large Telescope
Interferometer", 2 - 13 June, 2008, Keszthely, Hungary, corrected authorlis
Application of Stable Carbon Isotopes in a Subtropical North Atlantic MesocosmStudy: A New Approach to Assess CO2 Effects on the Marine Carbon Cycle
Stable isotope ratio analysis offers a unique opportunity to obtain information on ecosystem processes. The increase in atmospheric CO2 as a consequence of fossil fuel combustion and land-use change is altering the stable carbon isotope composition (δ13C) of the atmosphere and ocean. This work investigates the application of using δ13C measurements of seawater samples to explore the biogeochemical responses of marine ecosystems to anthropogenic CO2 perturbations. The combination of isotopic and non-isotopic measurements from a subtropical North-Atlantic mesocosm experiment provided a holistic view of the biogeochemical mechanisms that affect carbon dynamics under a gradient of pCO2 ranging from ~350 up to ~1,000 μatm during a phytoplankton succession. A clear CO2 response was detected in the isotopic datasets with 13C shifts of up to ~5%0, but increased CO2 levels only had a subtle effect on the concentrations of the dissolved and particulate organic carbon pools. Distinctive δ13C signatures of the particulate organic carbon pools in the water column and sediment traps were detectable for the different CO2 treatments after a nutrient stimulated phytoplankton bloom. These signatures were strongly correlated (p 0.05). Fractionation of carbon isotopes in phytoplankton was positively affected (9.6 < ε < 16.5%0) by high CO2 levels either because of the higher CO2 availability or because of a shift in phytoplankton community composition. Nevertheless, phytoplankton bloom intensity and development was independent of CO2 concentrations, and higher CO2 levels had no significant effect on inorganic nutrient uptake. Results from this mesocosm experiment showed that variations in the carbon isotopic signature of the carbon pools depend on both physical (air-sea exchange) and biological (community composition) drivers opening the door to new approaches for investigations of carbon cycling in marine ecosystems
First Light LBT AO Images of HR 8799 bcde at 1.65 and 3.3 Microns: New Discrepancies between Young Planets and Old Brown Dwarfs
As the only directly imaged multiple planet system, HR 8799 provides a unique
opportunity to study the physical properties of several planets in parallel. In
this paper, we image all four of the HR 8799 planets at H-band and 3.3 microns
with the new LBT adaptive optics system, PISCES, and LBTI/LMIRCam. Our images
offer an unprecedented view of the system, allowing us to obtain H and 3.3$
micron photometry of the innermost planet (for the first time) and put strong
upper-limits on the presence of a hypothetical fifth companion. We find that
all four planets are unexpectedly bright at 3.3 microns compared to the
equilibrium chemistry models used for field brown dwarfs, which predict that
planets should be faint at 3.3 microns due to CH4 opacity. We attempt to model
the planets with thick-cloudy, non-equilibrium chemistry atmospheres, but find
that removing CH4 to fit the 3.3 micron photometry increases the predicted L'
(3.8 microns) flux enough that it is inconsistent with observations. In an
effort to fit the SED of the HR 8799 planets, we construct mixtures of cloudy
atmospheres, which are intended to represent planets covered by clouds of
varying opacity. In this scenario, regions with low opacity look hot and
bright, while regions with high opacity look faint, similar to the patchy cloud
structures on Jupiter and L/T transition brown-dwarfs. Our mixed cloud models
reproduce all of the available data, but self-consistent models are still
necessary to demonstrate their viability.Comment: Accepted to Ap
Classical and Quantum Systems: Alternative Hamiltonian Descriptions
In complete analogy with the classical situation (which is briefly reviewed)
it is possible to define bi-Hamiltonian descriptions for Quantum systems. We
also analyze compatible Hermitian structures in full analogy with compatible
Poisson structures.Comment: To appear on Theor. Math. Phy
Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics
The Large Binocular Telescope (LBT) is a unique telescope featuring two
co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive
Optics (AO) system uses two innovative key components, namely an adaptive
secondary mirror with 672 actuators and a high-order pyramid wave-front sensor.
During the on-sky commissioning such a system reached performances never
achieved before on large ground-based optical telescopes. Images with 40mas
resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6
micron). Such images showed a contrast as high as 10e-4. Based on these
results, we compare the performances offered by a Natural Guide Star (NGS)
system upgraded with the state-of-the-art technology and those delivered by
existing Laser Guide Star (LGS) systems. The comparison, in terms of sky
coverage and performances, suggests rethinking the current role ascribed to NGS
and LGS in the next generation of AO systems for the 8-10 meter class
telescopes and Extremely Large Telescopes (ELTs).Comment: 10 pages, 9 figures, Preented at SSPIE Optics + Photonics 2011, San
Diego 20-25 August 201
Nonlocal field theory driven by a deformed product. Generalization of Kalb-Ramond duality
A modification of the standard product used in local field theory by means of
an associative deformed product is proposed. We present a class of deformed
products, one for every spin S=0,1/2,1, that induces a nonlocal theory,
displaying different form for different fields. This type of deformed product
is naturally supersymmetric and it has an intriguing duality.Comment: 23 pages, Late
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