1,063 research outputs found
Recommended from our members
The quest for a donor: probability based methods offer help
When a patient in need of a stem cell transplant has no compatible donor within his or her closest family, and no matched unrelated donor can be found, a remaining option is to search within the patient’s extended family. This situation often arises when the patient is of an ethnic minority, originating from a country that lacks a well-developed stem cell donor program, and has HLA haplotypes that are rare in his or her country of residence. Searching within the extended family may be time-consuming and expensive, and tools to calculate the probability of a match within groups of untested relatives would facilitate the search. We present a general approach to calculating the probability of a match in a given relative, or group of relatives, based on the pedigree, and on knowledge of the genotypes of some of the individuals. The method extends previous approaches by allowing the pedigrees to be consanguineous and arbitrarily complex, with deviations from Hardy-Weinberg equilibrium. We show how this extension has a considerable effect on results, in particular for rare haplotypes. The methods are exemplified using freeware programs to solve a case of practical importance
Sun-like Stars Shed Light on Solar Climate Forcing
Recently published, precise stellar photometry of 72 Sun-like stars obtained
at the Fairborn Observatory between 1993 and 2017 is used to set limits on the
solar forcing of Earth's atmosphere of 4.5 W m since 1750. This
compares with the +2.2 1.1 W m IPCC estimate for anthropogenic
forcing. Three critical assumptions are made. In decreasing order of importance
they are: (a) most of the brightness variations occur within the average
time-series length of 17 years; (b) the Sun seen from the ecliptic
behaves as an ensemble of middle-aged solar-like stars; and (c) narrow-band
photometry in the Str\"omgren and bands are linearly proportional to
the total solar irradiance. Assumption (a) can best be relaxed and tested by
obtaining more photometric data of Sun-like stars, especially those already
observed. Eight stars with near-solar parameters have been observed from 1999,
and two since 1993. Our work reveals the importance of continuing and expanding
ground-based photometry, to complement expensive solar irradiance measurements
from space.Comment: 6 pages, 6 figures, accepted to The Astrophysical Journal Letter
Deciphering Solar Magnetic Activity: The (Solar) Hale Cycle Terminator of 2021
McIntosh and colleagues identified an event in the solar timeline that
appeared to play a role in how Sunspot Cycle 23 (SC23) transitioned into
Sunspot Cycle 24 (SC24). The timeframe for this transition was rapid, taking
place in as short as time as a solar rotation. M2014 inferred that the
transition observed was a critical episode for the Sun's global-scale magnetic
field that was being manifest in the spatially and temporally overlapping and
magnetic systems belonging to the Sun's 22-year (Hale) magnetic cycle. These
events have been dubbed as Hale Cycle terminations, or `terminators' for short.
Further exploration revealed a relationship between terminator separation (as a
measure of overlap in the Hale Cycles) and the upcoming sunspot cycle
amplitude. McIntosh and colleagues extrapolated upon this relationship to
identify the termination of the SC24 carrying Hale Cycle band in Mid-2020 and
inferred that this would result in a very large Sunspot Cycle 25 (SC25). This
paper presents observational analysis of the end of SC24 and the initial months
of SC25 growth following a terminator that occurred in mid-December 2021
(approximately 12/13/2021). We use the December 2021 terminator to finalize the
forecast of SC25 amplitude 184 (17 with 95\% confidence, and 63 with
68\% confidence). Finally, we use other terminator-related superposed epoch
analyses to project the timing of SC25 maxima in late 2023 to mid 2024.Comment: 16 pages, 10 figures - Submitted to Frontier
Impact of Rubin Observatory LSST Template Acquisition Strategies on Early Science from the Transients and Variable Stars Science Collaboration: Non-time-critical Science Cases
Vera C. Rubin Observatory Legacy Survey of Space and Time, LSST, will revolutionize modern astronomy by producing an extremely deep (coadded depth ~27 mag) depth-limited survey of the entire southern sky (LSST Science Collaboration et al. 2009). The 8.4 m large-aperture, wide-field telescope, which is based in Cerro Pachón, will image the entire Southern sky every three nights in multiple bands (SDSS-u, g, r, i, z, y) and produce a fire-hose of data, 20 Tb each night, concluding in a 60 petabyte data set as the legacy of the 10 yr survey.
Extracting meaningful light curves from variable objects requires difference imaging to both identify variability and calibrate light curve data products. Templates, co-added groups of visits that act as an image of the "static" sky, are a key component of Difference Imaging Analysis (DIA) and as such are of paramount importance for all science that involves variable objects. As the "non-time-critical" science cases discussed here are mostly periodic, they generally do not depend upon the survey alert stream; however, templates are still crucial for performing science and calibrations during the first year. We provide recommendations for observing strategies for template acquisition starting from commissioning and through Year 1 of the survey
Photospheric and chromospheric magnetic activity of seismic solar analogs. Observational inputs on the solar/stellar connection from Kepler and Hermes
We identify a set of 18 solar analogs among the seismic sample of solar-like
stars observed by the Kepler satellite rotating between 10 and 40 days. This
set is constructed using the asteroseismic stellar properties derived using
either the global oscillation properties or the individual acoustic
frequencies. We measure the magnetic activity properties of these stars using
observations collected by the photometric Kepler satellite and by the
ground-based, high-resolution Hermes spectrograph mounted on the Mercator
telescope. The photospheric (Sph) and chromospheric (S index) magnetic activity
levels of these seismic solar analogs are estimated and compared in relation to
the solar activity. We show that the activity of the Sun is comparable to the
activity of the seismic solar analogs, within the maximum-to-minimum temporal
variations of the 11-year solar activity cycle 23. In agreement with previous
studies, the youngest stars and fastest rotators in our sample are actually the
most active. The activity of stars older than the Sun seems to not evolve much
with age. Furthermore, the comparison of the photospheric, Sph, with the
well-established chromospheric, S index, indicates that the Sph index can be
used to provide a suitable magnetic activity proxy which can be easily
estimated for a large number of stars from space photometric observations.Comment: Accepted for publication in A&
The spherical probe electric field and wave experiment
The experiment is designed to measure the electric field and density fluctuations with sampling rates up to 40,000 samples/sec. The description includes Langmuir sweeps that can be made to determine the electron density and temperature, the study of nonlinear processes that result in acceleration of plasma, and the analysis of large scale phenomena where all four spacecraft are needed
Hunger among Inuit children in Canada
Background and objectives. Inuit populations may be at increased risk for experiencing poor nutrition or hunger due to limited access and availability to food. The prevalence and correlates of parental perceptions of hunger among a nationally representative sample of Inuit children in Canada have not yet been reported. Design. Data are from the 2006 Aboriginal Children's Survey (ACS). Sociodemographic information, dietary behaviours and hunger status were parent-reported via a household interview for Inuit children aged 2–5 years (n=1,234). Prevalence of hunger was calculated among Inuit children by sociodemographic factors and by dietary behaviours. In addition, a multivariate logistic regression model was conducted to determine factors associated with parental perception of ever experiencing hunger. Results. The prevalence of Inuit children in Canada aged 2–5 years ever experiencing hunger was 24.4%. Children who were reported to have experienced hunger consumed milk and milk products (p<0.001); fish, eggs and meat (p<0.05); fruits (p<0.001); and vegetables (p<0.001) significantly less often than never-hungry children. Fast food and processed foods, soft drinks and juice, and salty snacks, sweets and desserts were consumed as often as never-hungry children (all p>0.05). The majority (81%) of Inuit parents/guardians of ever-hungry children sought help from family or friends. Factors associated with an increased likelihood of experiencing hunger include sociodemographic characteristics (such as income and household size), living in an Inuit region and living in a community with cultural activities. Conclusion. About 1 in 4 Inuit children were reported by their parents to have experienced hunger, and hunger was associated with region, sociodemographic and community factors. Future research could further examine the impact of ever experiencing hunger on the health status of Inuit children and their families in Canada
Magnetic variability in the young solar analog KIC 10644253: Observations from the Kepler satellite and the HERMES spectrograph
The continuous photometric observations collected by the Kepler satellite
over 4 years provide a whelm of data with an unequalled quantity and quality
for the study of stellar evolution of more than 200000 stars. Moreover, the
length of the dataset provide a unique source of information to detect magnetic
activity and associated temporal variability in the acoustic oscillations. In
this regards, the Kepler mission was awaited with great expectation. The search
for the signature of magnetic activity variability in solar-like pulsations
still remained unfruitful more than 2 years after the end of the nominal
mission. Here, however, we report the discovery of temporal variability in the
low-degree acoustic frequencies of the young (1 Gyr-old) solar analog KIC
10644253 with a modulation of about 1.5 years with significant temporal
variations along the duration of the Kepler observations. The variations are in
agreement with the derived photometric activity. The frequency shifts extracted
for KIC 10644253 are shown to result from the same physical mechanisms involved
in the inner sub-surface layers as in the Sun. In parallel, a detailed
spectroscopic analysis of KIC 10644253 is performed based on complementary
ground-based, high-resolution observations collected by the HERMES instrument
mounted on the MERCATOR telescope. Its lithium abundance and chromospheric
activity S-index confirm that KIC 10644253 is a young and more active star than
the Sun.Comment: Accepted for publication in A&A, 12 pages, 8 figure
Psychometric Properties of the General Organizational Index (GOI): A Measure of Individualization and Quality Improvement to Complement Program Fidelity
To assess the implementation of effective practices, mental health programs need standardized measures. The General Organizational Index (GOI), although widely used for this purpose, has received minimal psychometric research. For this study, we assessed psychometric properties of the GOI scale administered four times over 18 months during the implementation of a new program in 11 sites. The GOI scale demonstrated high levels of interrater reliability (.97), agreement between assessors on item ratings (86% overall), internal consistency (.77–.80 at three time points), sensitivity to change, and feasibility. We conclude that the GOI scale has acceptable psychometric properties, and its use may enhance implementation and research on evidence-based mental health practices.publishedVersio
- …