891 research outputs found
Violations of local realism by two entangled quNits
Results obtained in two recent papers, \cite{Kaszlikowski} and \cite{Durt},
seem to indicate that the nonlocal character of the correlations between the
outcomes of measurements performed on entangled systems separated in space is
not robust in the presence of noise. This is surprising, since entanglement
itself is robust. Here we revisit this problem and argue that the class of
gedanken-experiments considered in \cite{Kaszlikowski} and \cite{Durt} is too
restrictive. By considering a more general class, involving sequences of
measurements, we prove that the nonlocal correlations are in fact robust.Comment: Reference added, 3 pages, accepted for publication in J. Phys. A:
Math. and Genera
The Occurrence Rate of Earth Analog Planets Orbiting Sunlike Stars
Kepler is a space telescope that searches Sun-like stars for planets. Its
major goal is to determine {\eta}_Earth, the fraction of Sunlike stars that
have planets like Earth. When a planet 'transits' or moves in front of a star,
Kepler can measure the concomitant dimming of the starlight. From analysis of
the first four months of those measurements for over 150,000 stars, Kepler's
science team has determined sizes, surface temperatures, orbit sizes and
periods for over a thousand new planet candidates. In this paper, we
characterize the period probability distribution function of the super-Earth
and Neptune planet candidates with periods up to 132 days, and find three
distinct period regimes. For candidates with periods below 3 days the density
increases sharply with increasing period; for periods between 3 and 30 days the
density rises more gradually with increasing period, and for periods longer
than 30 days, the density drops gradually with increasing period. We estimate
that 1% to 3% of stars like the Sun are expected to have Earth analog planets,
based on the Kepler data release of Feb 2011. This estimate of is based on
extrapolation from a fiducial subsample of the Kepler planet candidates that we
chose to be nominally 'complete' (i.e., no missed detections) to the realm of
the Earth-like planets, by means of simple power law models. The accuracy of
the extrapolation will improve as more data from the Kepler mission is folded
in. Accurate knowledge of {\eta}_Earth is essential for the planning of future
missions that will image and take spectra of Earthlike planets. Our result that
Earths are relatively scarce means that a substantial effort will be needed to
identify suitable target stars prior to these future missions.Comment: Accepted for publication in the Astrophysical Journal. 19 pages, 8
figures. Minor text revisions, as requested by the scientific editor.
Included an additional figure. No changes in the scientific result
How Will Astronomy Archives Survive The Data Tsunami?
The field of astronomy is starting to generate more data than can be managed,
served and processed by current techniques. This paper has outlined practices
for developing next-generation tools and techniques for surviving this data
tsunami, including rigorous evaluation of new technologies, partnerships
between astronomers and computer scientists, and training of scientists in
high-end software engineering engineering skills.Comment: 8 pages, 3 figures; ACM Queue. Vol 9, Number 10, October 2011
(http://queue.acm.org/detail.cfm?id=2047483
Essential health information available for India in the public domain on the internet
<p>Abstract</p> <p>Background</p> <p>Health information and statistics are important for planning, monitoring and improvement of the health of populations. However, the availability of health information in developing countries is often inadequate. This paper reviews the essential health information available readily in the public domain on the internet for India in order to broadly assess its adequacy and inform further development.</p> <p>Methods</p> <p>The essential sources of health-related information for India were reviewed. An extensive search of relevant websites and the PubMed literature database was conducted to identify the sources. For each essential source the periodicity of the data collection, the information it generates, the geographical level at which information is reported, and its availability in the public domain on the internet were assessed.</p> <p>Results</p> <p>The available information related to non-communicable diseases and injuries was poor. This is a significant gap as India is undergoing an epidemiological transition with these diseases/conditions accounting for a major proportion of disease burden. Information on infrastructure and human resources was primarily available for the public health sector, with almost none for the private sector which provides a large proportion of the health services in India. Majority of the information was available at the state level with almost negligible at the district level, which is a limitation for the practical implementation of health programmes at the district level under the proposed decentralisation of health services in India.</p> <p>Conclusion</p> <p>This broad review of the essential health information readily available in the public domain on the internet for India highlights that the significant gaps related to non-communicable diseases and injuries, private health sector and district level information need to be addressed to further develop an effective health information system in India.</p
Linear Collider Capabilities for Supersymmetry in Dark Matter Allowed Regions of the mSUGRA Model
Recent comparisons of minimal supergravity (mSUGRA) model predictions with
WMAP measurements of the neutralino relic density point to preferred regions of
model parameter space. We investigate the reach of linear colliders (LC) with
and 1 TeV for SUSY in the framework of the mSUGRA model. We find
that LCs can cover the entire stau co-annihilation region provided \tan\beta
\alt 30. In the hyperbolic branch/focus point (HB/FP) region of parameter
space, specialized cuts are suggested to increase the reach in this important
``dark matter allowed'' area. In the case of the HB/FP region, the reach of a
LC extends well past the reach of the CERN LHC. We examine a case study in the
HB/FP region, and show that the MSSM parameters and can be
sufficiently well-measured to demonstrate that one would indeed be in the HB/FP
region, where the lightest chargino and neutralino have a substantial higgsino
component.Comment: 29 pages, 15 EPS figures; updated version slightly modified to
conform with published versio
Influence of family and friend smoking on intentions to smoke and smoking-related attitudes and refusal self-efficacy among 9-10 year old children from deprived neighbourhoods: a cross-sectional study.
BACKGROUND: Smoking often starts in early adolescence and addiction can occur rapidly. For effective smoking prevention there is a need to identify at risk groups of preadolescent children and whether gender-specific intervention components are necessary. This study aimed to examine associations between mother, father, sibling and friend smoking and cognitive vulnerability to smoking among preadolescent children living in deprived neighbourhoods. METHODS: Cross-sectional data was collected from 9-10 year old children (n =1143; 50.7% girls; 85.6% White British) from 43 primary schools in Merseyside, England. Children completed a questionnaire that assessed their smoking-related behaviour, intentions, attitudes, and refusal self-efficacy, as well as parent, sibling and friend smoking. Data for boys and girls were analysed separately using multilevel linear and logistic regression models, adjusting for individual cognitions and school and deprivation level. RESULTS: Compared to girls, boys had lower non-smoking intentions (P = 0.02), refusal self-efficacy (P = 0.04) and were less likely to agree that smoking is 'definitely' bad for health (P < 0.01). Friend smoking was negatively associated with non-smoking intentions in girls (P < 0.01) and boys (P < 0.01), and with refusal self-efficacy in girls (P < 0.01). Sibling smoking was negatively associated with non-smoking intentions in girls (P < 0.01) but a positive association was found in boys (P = 0.02). Boys who had a smoking friend were less likely to 'definitely' believe that the smoke from other people's cigarettes is harmful (OR 0.57, 95% CI: 0.35 to 0.91, P = 0.02). Further, boys with a smoking friend (OR 0.38, 95% CI: 0.21 to 0.69, P < 0.01) or a smoking sibling (OR 0.45, 95% CI: 0.21 to 0.98) were less likely to 'definitely' believe that smoking is bad for health. CONCLUSION: This study indicates that sibling and friend smoking may represent important influences on 9-10 year old children's cognitive vulnerability toward smoking. Whilst some differential findings by gender were observed, these may not be sufficient to warrant separate prevention interventions. However, further research is needed
Measuring the Higgs Sector
If we find a light Higgs boson at the LHC, there should be many observable
channels which we can exploit to measure the relevant parameters in the Higgs
sector. We use the SFitter framework to map these measurements on the parameter
space of a general weak-scale effective theory with a light Higgs state of mass
120 GeV. Our analysis benefits from the parameter determination tools and the
error treatment used in new--physics searches, to study individual parameters
and their error bars as well as parameter correlations.Comment: 45 pages, Journal version with comments from refere
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Digital switchover in Europe
This article discusses the political, economic, technological and human aspects of the digital switchover in Europe and explores various policies for managing the process. The article first examines the advantages and drawbacks of digital switchover, and identifies a number of challenges and policy dilemmas of making switchover an achievable objective. It goes on to look at digital television adoption across Europe and assesses the effectiveness of free-to-air digital television to accelerate take-up. Finally, the article examines EU initiatives as well as national plans in digital switchover and proposes various measures for encouraging the take-up of digital services and therefore bringing forward the likely idea of analogue switch-off
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