2,301 research outputs found
Quantile regression for mixed models with an application to examine blood pressure trends in China
Cardiometabolic diseases have substantially increased in China in the past 20
years and blood pressure is a primary modifiable risk factor. Using data from
the China Health and Nutrition Survey, we examine blood pressure trends in
China from 1991 to 2009, with a concentration on age cohorts and urbanicity.
Very large values of blood pressure are of interest, so we model the
conditional quantile functions of systolic and diastolic blood pressure. This
allows the covariate effects in the middle of the distribution to vary from
those in the upper tail, the focal point of our analysis. We join the
distributions of systolic and diastolic blood pressure using a copula, which
permits the relationships between the covariates and the two responses to share
information and enables probabilistic statements about systolic and diastolic
blood pressure jointly. Our copula maintains the marginal distributions of the
group quantile effects while accounting for within-subject dependence, enabling
inference at the population and subject levels. Our population-level regression
effects change across quantile level, year and blood pressure type, providing a
rich environment for inference. To our knowledge, this is the first quantile
function model to explicitly model within-subject autocorrelation and is the
first quantile function approach that simultaneously models multivariate
conditional response. We find that the association between high blood pressure
and living in an urban area has evolved from positive to negative, with the
strongest changes occurring in the upper tail. The increase in urbanization
over the last twenty years coupled with the transition from the positive
association between urbanization and blood pressure in earlier years to a more
uniform association with urbanization suggests increasing blood pressure over
time throughout China, even in less urbanized areas. Our methods are available
in the R package BSquare.Comment: Published at http://dx.doi.org/10.1214/15-AOAS841 in the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Sequence stratigraphy, chemostratigraphy and facies analysis of Cambrian Series 2 â Series 3 boundary strata in northwestern Scotland
Globally, the Series 2 â Series 3 boundary of the Cambrian System coincides with a major carbon isotope excursion, sea-level changes and trilobite extinctions. Here we examine the sedimentology, sequence stratigraphy and carbon isotope record of this interval in the Cambrian strata (Durness Group) of NW Scotland. Carbonate carbon isotope data from the lower part of the Durness Group (Ghrudaidh Formation) show that the shallow-marine, Laurentian margin carbonates record two linked sea-level and carbon isotopic events. Whilst the carbon isotope excursions are not as pronounced as those expressed elsewhere, correlation with global records (Sauk I â Sauk II boundary and Olenellus biostratigraphic constraint) identifies them as representing the local expression of the ROECE and DICE. The upper part of the ROECE is recorded in the basal Ghrudaidh Formation whilst the DICE is seen around 30m above the base of this unit. Both carbon isotope excursions co-occur with surfaces interpreted to record regressiveâtransgressive events that produced amalgamated sequence boundaries and ravinement/flooding surfaces overlain by conglomerates of reworked intraclasts. The ROECE has been linked with redlichiid and olenellid trilobite extinctions, but in NW Scotland, Olenellus is found after the negative peak of the carbon isotope excursion but before sequence boundary formation
EarthPT: a foundation model for Earth Observation
We introduce EarthPT -- an Earth Observation (EO) pretrained transformer.
EarthPT is a 700 million parameter decoding transformer foundation model
trained in an autoregressive self-supervised manner and developed specifically
with EO use-cases in mind. We demonstrate that EarthPT is an effective
forecaster that can accurately predict future pixel-level surface reflectances
across the 400-2300 nm range well into the future. For example, forecasts of
the evolution of the Normalised Difference Vegetation Index (NDVI) have a
typical error of approximately 0.05 (over a natural range of -1 -> 1) at the
pixel level over a five month test set horizon, out-performing simple
phase-folded models based on historical averaging. We also demonstrate that
embeddings learnt by EarthPT hold semantically meaningful information and could
be exploited for downstream tasks such as highly granular, dynamic land use
classification. Excitingly, we note that the abundance of EO data provides us
with -- in theory -- quadrillions of training tokens. Therefore, if we assume
that EarthPT follows neural scaling laws akin to those derived for Large
Language Models (LLMs), there is currently no data-imposed limit to scaling
EarthPT and other similar `Large Observation Models.'Comment: 7 pages, 4 figures, submitted to NeurIPS CCAI worksho
Perturbative Strong Interaction Corrections to the Heavy Quark Semileptonic Decay Rate
We calculate the part of the order correction to the
semileptonic heavy quark decay rate proportional to the number of light quark
flavors, and use our result to set the scale for evaluating the strong coupling
in the order term according to the scheme of Brodsky, Lepage and
Mackenzie. Expressing the decay rate in terms of the heavy quark pole mass
, we find the scale for the strong coupling to be . If the decay rate is expressed in terms of the heavy
quark mass then the scale is . We use these
results along with the existing calculations for hadronic decay to
calculate the BLM scale for the nonleptonic decay width and the semileptonic
branching ratio. The implications for the value of extracted from
the inclusive semileptonic meson decay rate are discussed.Comment: 7 pages in Latex plus 1 uuencoded figure, uses epsf, UTPT-94-24,
CMU-HEP 94-29, CALT-68-1950 (previous results unchanged; we add a short
discussion of nonleptonic decays
Familial colloid cyst of the third ventricle
A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Colloid cysts of the third ventricle are rare benign lesions. They can present as incidental finding on imaging or
with symptoms of obstructive hydrocephalus. To date, 18 familial cases of colloid cyst have been reported. Due
to the extreme rarity of these cysts, it has been suggested that there is a genetic component involved. This report
presents a familial colloid cyst in non-twin brothers who both presented in their early twenties. In addition, both
of them had congenital inguinal hernia. This may represent a potential association between familial colloid cysts
and congenital inguinal hernia that could provide us with insight into the genetic mechanism involved
Longitudinal touchscreen use across early development is associated with faster exogenous and reduced endogenous attention control
Childhood screen time is associated with both attentional difficulties (for television viewing) and benefits (in action video gamers), but few studies have investigated todayâs pervasive touchscreen devices (e.g. smartphones and tablets), which combine salient features, interactive content, and accessibility from toddlerhood (a peak period of cognitive development). We tested exogenous and endogenous attention, following forty children who were stable high (HU) or low (LU) touchscreen users from toddlerhood to pre-school. HUs were slower to disengage attention, relative to their faster baseline orienting ability. In an infant anti-saccade task, HUs displayed more of a corrective strategy of orienting faster to distractors before anticipating the target. Results suggest that long-term high exposure to touchscreen devices is associated with faster exogenous attention and concomitant decreases in endogenous attention control. Future work is required to demonstrate causality, dissociate variants of use, and investigate how attention behaviours found in screen-based contexts translate to real-world settings
Lack of correlation between MYCN expression and the Warburg effect in neuroblastoma cell lines
<p>Abstract</p> <p>Background</p> <p>Many cancers preferentially meet their energy requirements through the glycolytic pathway rather than via the more efficient oxidative phosphorylation pathway. It is thought that this is an important adaptation in cancer malignancy. We investigated whether use of glycolysis for energy production even in the presence of oxygen (known as the Warburg effect) varied between neuroblastoma cell lines with or without <it>MYCN </it>amplification (a key indicator of poor disease outcome in neuroblastoma).</p> <p>Methods</p> <p>We examined ATP and lactate production, oxygen consumption and mitochondrial energisation status for three neuroblastoma cell lines with varying degrees of <it>MYCN </it>amplification and MYCN expression.</p> <p>Results</p> <p>We found no correlation between MYCN expression and the Warburg effect in the cell lines investigated.</p> <p>Conclusion</p> <p>Our results suggest preferential use of glycolysis for energy production and MYCN expression may be independent markers of neuroblastoma malignancy <it>in vitro </it>if not <it>in vivo</it>.</p
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What Will it Take to Make Solar Panels Cool?
With the predicted results of climate change looming, humanity must do all it can to limit greenhouse gas emissions. Maintaining a habitable environment along with the high quality of living associated with developed nations requires investment in renewable energy. Because national governments often fail to make responsible decisions for their country\u27s future, this burden falls to institutions like UMass Amherst. Although costly investments like solar panels substantially improve the sustainability of campus, some innovative improvements of existing solar energy infrastructure can go a long way. For example, when solar panels heat up they lose photovoltaic efficiency. We propose that UMass institute cooling systems on current and future solar panel structures. This may sound extravagant, but in this paper we outline a plan for a simple and affordable cooling system that can be constructed from supplies bought at a local hardware store.
The University spent approximately 40,000 worth of electricity each year, with a 38 year return on investment. We expect a cooling system for each canopy to cost around 500 investment will generate an additional 150,000. By comparison, $500 is peanuts. Read on to see how a little ingenuity can go a long way to save money and the environment
Hadron Spectra for Semileptonic Heavy Quark Decay
We calculate the leading perturbative and power corrections to the hadronic
invariant mass and energy spectra in semileptonic heavy hadron decays. We apply
our results to the system. Moments of the invariant mass spectrum, which
vanish in the parton model, probe gluon bremsstrahlung and nonperturbative
effects. Combining our results with recent data on meson branching ratios,
we obtain a lower bound and an upper bound
GeV. The Brodsky-Lepage-Mackenzie scale setting
procedure suggests that higher order perturbative corrections are small for
bottom decay, and even tractable for charm decay.Comment: 24 pages, uses REVTeX, 5 EPS figures embedded with epsf.sty, slightly
modified version to appear in Phys. Rev.
Parental influences on child physical activity and screen viewing time: a population based study
Background: Parents can influence their childrenâs physical activity participation and screen time.This study examined the relative significance of perceived parental barriers and self-efficacy in relation to childrenâs physical activity participation and screen time viewing. The associations between these factors and the behaviours were analysed. Methods: Cross-sectional population survey in New South Wales, Australia of parents of pre-school (N = 764), younger (Kindergarten, Grades 2 and 4; N = 1557) and older children (Grades 6, 8 and 10; N = 1665). Parents reported barriers and self-efficacy to influence their childâs physical activity and screen time behaviours in a range of circumstances. Differences were examined by childâs sex and age group, household income, maternal education and location of residence. The duration of physical activity and screen viewing was measured by parental report for pre-school and younger children and self-report for older children. Associations between parental factors and childrenâs organised, non-organised and total activity and screen time were analysed. Results: Cost, lack of opportunities for participation and transport problems were the barriers most often reported, particularly by low income parents and those in rural areas. The number of barriers was inversely related to childrenâs time spent in organised activity, but not their non-organised activity. Higher parental self-efficacy was positively associated with organised physical activity in the younger and older childrenâs groups and the non-organised activity of older children. School-age children (younger and older groups) were less likely to meet physical activity guidelines when parents reported âĽ4 barriers (OR 3.76, 95% CI 1.25-11.34 and OR 3.72, 95% CI 1.71-8.11 respectively). Low parental self-efficacy was also associated with the likelihood of children exceeding screen time guidelines for each age group (pre-school OR 0.62, 95% CI 0.43-0.87; young children OR 0.56, 95% CI 0.39-0.80; and older children OR 0.57, 95% CI 0.43-0.74). Conclusion: Parental barriers are associated with the time that children spend in both active and sedentary pursuits. These findings highlight family, economic and environmental factors that should be addressed in programs to promote child physical activity and tackle sedentary behaviour
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