435 research outputs found
Target Selection for the SDSS-IV APOGEE-2 Survey
APOGEE-2 is a high-resolution, near-infrared spectroscopic survey observing
roughly 300,000 stars across the entire sky. It is the successor to APOGEE and
is part of the Sloan Digital Sky Survey IV (SDSS-IV). APOGEE-2 is expanding
upon APOGEE's goals of addressing critical questions of stellar astrophysics,
stellar populations, and Galactic chemodynamical evolution using (1) an
enhanced set of target types and (2) a second spectrograph at Las Campanas
Observatory in Chile. APOGEE-2 is targeting red giant branch (RGB) and red
clump (RC) stars, RR Lyrae, low-mass dwarf stars, young stellar objects, and
numerous other Milky Way and Local Group sources across the entire sky from
both hemispheres. In this paper, we describe the APOGEE-2 observational design,
target selection catalogs and algorithms, and the targeting-related
documentation included in the SDSS data releases.Comment: 19 pages, 6 figures. Accepted to A
Dietary iodine exposure and brain structures and cognition in older people. Exploratory analysis in the Lothian Birth Cohort 1936
Background:
Iodine deficiency is one of the three key micronutrient deficiencies highlighted as major public health issues by the World Health Organisation. Iodine deficiency is known to cause brain structural alterations likely to affect cognition. However, it is not known whether or how different (lifelong) levels of exposure to dietary iodine influences brain health and cognitive functions.
Methods:
From 1091 participants initially enrolled in The Lothian Birth Cohort Study 1936, we obtained whole diet data from 882. Three years later, from 866 participants (mean age 72 yrs, SD ±0.8), we obtained cognitive information and ventricular, hippocampal and normal and abnormal tissue volumes from brain structural magnetic resonance imaging scans (n=700). We studied the brain structure and cognitive abilities of iodine-rich food avoiders/low consumers versus those with a high intake in iodine-rich foods (namely dairy and fish).
Results:
We identified individuals (n=189) with contrasting diets, i) belonging to the lowest quintiles for dairy and fish consumption, ii) milk avoiders, iii) belonging to the middle quintiles for dairy and fish consumption, and iv) belonging to the middle quintiles for dairy and fish consumption. Iodine intake was secured mostly though the diet (n=10 supplement users) and was sufficient for most (75.1%, median 193 μg/day). In individuals from these groups, brain lateral ventricular volume was positively associated with fat, energy and protein intake. The associations between iodine intake and brain ventricular volume and between consumption of fish products (including fish cakes and fish-containing pasties) and white matter hyperintensities (p=0.03) the latest being compounded by sodium, proteins and saturated fats, disappeared after type 1 error correction.
Conclusion:
In this large Scottish older cohort, the proportion of individuals reporting extreme (low vs. high)/medium iodine consumption is small. In these individuals, low iodine-rich food intake was associated with increased brain volume shrinkage, raising an important hypothesis worth being explored for designing appropriate guidelines
Performance of the First ANTARES Detector Line
In this paper we report on the data recorded with the first Antares detector
line. The line was deployed on the 14th of February 2006 and was connected to
the readout two weeks later. Environmental data for one and a half years of
running are shown. Measurements of atmospheric muons from data taken from
selected runs during the first six months of operation are presented.
Performance figures in terms of time residuals and angular resolution are
given. Finally the angular distribution of atmospheric muons is presented and
from this the depth profile of the muon intensity is derived.Comment: 14 pages, 9 figure
Murchison Widefield Array limits on radio emission from Antares neutrino events
We present a search, using the Murchison Widefield Array (MWA), for electromagnetic (EM) counterparts to two candidate high-energy neutrino events detected by the ANTARES neutrino telescope in 2013 November and 2014 March. These events were selected by ANTARES because they are consistent, within 0°.4, with the locations of galaxies within 20 Mpc of Earth. Using MWA archival data at frequencies between 118 and 182 MHz, taken ~20 days prior to, at the same time as, and up to a year after the neutrino triggers, we look for transient or strongly variable radio sources that are consistent with the neutrino positions. No such counterparts are detected, and we set a 5s upper limit for low-frequency radio emission of ~1037 erg s-1 for progenitors at 20 Mpc. If the neutrino sources are instead not in nearby galaxies, but originate in binary neutron star coalescences, our limits place the progenitors at z 0.2. While it is possible, due to the high background from atmospheric neutrinos, that neither event is astrophysical, the MWA observations are nevertheless among the first to follow up neutrino candidates in the radio, and illustrate the promise of wide-field instruments like MWA for detecting EM counterparts to such events
Search for magnetic monopoles with ten years of the ANTARES neutrino telescope
This work presents a new search for magnetic monopoles using data taken with the ANTARES neutrino telescope over a period of 10 years (January 2008 to December 2017). Compared to previous ANTARES searches, this analysis uses a run-by-run simulation strategy, with a larger exposure as well as a new simulation of magnetic monopoles taking into account the Kasama, Yang and Goldhaber model for their interaction cross-section with matter. No signal compatible with the passage of relativistic magnetic monopoles is observed, and upper limits on the flux of magnetic monopoles with β=v/c≥0.55, are presented. For ultra-relativistic magnetic monopoles the flux limit is ∼7×10−18 cm−2s−1sr−1
A search for neutrino emission from the Fermi bubbles with the ANTARES telescope
Analysis of the Fermi-LAT data has revealed two extended structures above and below the Galactic Centre emitting gamma rays with a hard spectrum, the so-called Fermi bubbles. Hadronic models attempting to explain the origin of the Fermi bubbles predict the emission of high-energy neutrinos and gamma rays with similar fluxes. The ANTARES detector, a neutrino telescope located in the Mediterranean Sea, has a good visibility to the Fermi bubble regions. Using data collected from 2008 to 2011 no statistically significant excess of events is observed and therefore upper limits on the neutrino flux in TeV range from the Fermi bubbles are derived for various assumed energy cutoffs of the source
ANTARES search for point-sources of neutrinos using astrophysical catalogs: a likelihood stacking analysis
A search for astrophysical point-like neutrino sources using the data
collected by the ANTARES detector between January 29, 2007 and December 31,
2017 is presented. A likelihood stacking method is used to assess the
significance of an excess of muon neutrinos inducing track-like events in
correlation with the location of a list of possible sources. Different sets of
objects are tested in the analysis: a) a sub-sample of the \textit{Fermi} 3LAC
catalog of blazars, b) a jet-obscured AGN population, c) a sample of soft
gamma-ray selected radio galaxies, d) a star-forming galaxy catalog , and e) a
public sample of 56 very-high-energy track events from the IceCube experiment.
None of the tested sources shows a significant association with the sample of
neutrinos detected by ANTARES. The smallest p-value is obtained for the radio
galaxies catalog with an equal weights hypothesis, with a pre-trial p-value
equivalent to a excess, equivalent to
post-trial.
In addition, the results of a dedicated analysis for the blazar MG3
J225517+2409 are also reported: this source is found to be the most significant
within the \textit{Fermi} 3LAC sample, with 5 ANTARES events located at less
than one degree from the source. This blazar showed evidence of flaring
activity in \textit{Fermi} data, in space-time coincidence with a high-energy
track detected by IceCube. An \emph{a posteriori} significance of for the combination of ANTARES and IceCube data is reported
"The contribution of chronic diseases to the prevalence of dependence among older people in Latin America, China and India: a 10/66 Dementia Research Group population-based survey"
<p>Abstract</p> <p>Background</p> <p>The number of older people is set to increase dramatically worldwide. Demographic changes are likely to result in the rise of age-related chronic diseases which largely contribute to years lived with a disability and future dependence. However dependence is much less studied although intrinsically linked to disability. We investigated the prevalence and correlates of dependence among older people from middle income countries.</p> <p>Methods</p> <p>A one-phase cross-sectional survey was carried out at 11 sites in seven countries (urban sites in Cuba, Venezuela, and Dominican Republic, urban and rural sites in Peru, Mexico, China and India). All those aged 65 years and over living in geographically defined catchment areas were eligible. In all, 15,022 interviews were completed with an informant interview for each participant. The full 10/66 Dementia Research Group survey protocol was applied, including ascertainment of depression, dementia, physical impairments and self-reported diagnoses. Dependence was interviewer-rated based on a key informant's responses to a set of open-ended questions on the participant's needs for care. We estimated the prevalence of dependence and the independent contribution of underlying health conditions. Site-specific prevalence ratios were meta-analysed, and population attributable prevalence fractions (PAPF) calculated.</p> <p>Results</p> <p>The prevalence of dependence increased with age at all sites, with a tendency for the prevalence to be lower in men than in women. Age-standardised prevalence was lower in all sites than in the USA. Other than in rural China, dementia made the largest independent contribution to dependence, with a median PAPF of 34% (range 23%-59%). Other substantial contributors were limb impairment (9%, 1%-46%), stroke (8%, 2%-17%), and depression (8%, 1%-27%).</p> <p>Conclusion</p> <p>The demographic and health transitions will lead to large and rapid increases in the numbers of dependent older people particularly in middle income countries (MIC). The prevention and control of chronic neurological and neuropsychiatric diseases and the development of long-term care policies and plans should be urgent priorities.</p
The positioning system of the ANTARES Neutrino Telescope
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described
Time calibration of the ANTARES neutrino telescope
The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of similar to 1 ns. The methods developed to attain this level of precision are described
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