6,029 research outputs found
High-temperature scaling limit for directed polymers on a hierarchical lattice with bond disorder
Diamond "lattices" are sequences of recursively-defined graphs that provide a
network of directed pathways between two fixed root nodes, and . The
construction recipe for diamond graphs depends on a branching number and a segmenting number , for which a larger value
of the ratio intuitively corresponds to more opportunities for
intersections between two randomly chosen paths. By attaching i.i.d. random
variables to the bonds of the graphs, I construct a random Gibbs measure on the
set of directed paths by assigning each path an "energy" given by summing the
random variables along the path. For the case , I propose a scaling regime
in which the temperature grows along with the number of hierarchical layers of
the graphs, and the partition function (the normalization factor of the Gibbs
measure) appears to converge in law. I prove that all of the positive integer
moments of the partition function converge in this limiting regime. The
motivation of this work is to prove a functional limit theorem that is
analogous to a previous result obtained in the case.Comment: 28 pages, 1 figur
More Data and Appropriate Statistical Methods Needed to Fully Measure the Displacement Effects of Development Assistance for Health
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Comparability of Self Rated Health: Cross Sectional Multi-Country Survey Using Anchoring Vignettes
Objective: To examine differences in expectations for health using anchoring vignettes, which describe fixed levels of health on dimensions such as mobility. Design: Cross sectional survey of adults living in the community. Setting: China, Myanmar, Sri Lanka, Pakistan, Turkey, and United Arab Emirates. Participants: 3012 men and women aged 18 years and older (self ratings); subsample of 406 (vignette ratings). Main outcome measures: Self rated mobility levels and ratings of hypothetical vignettes using the same questions and response categories. Results: Consistent rankings of vignettes are evidence that vignettes are understood in similar ways in different settings, and internal consistency of orderings on two mobility questions indicates good comprehension. Variation in vignette ratings across age groups suggests that expectations for mobility decline with age. Comparison of responses to two different mobility questions supports the assumption that individual ratings of hypothetical vignettes relate to expectations for health in similar ways as self assessments. Conclusions: Anchoring vignettes could provide a powerful tool for understanding and adjusting for the influence of different health expectations on self ratings of health. Incorporating anchoring vignettes in surveys can improve the comparability of self reported measures
Cluster-mining: An approach for determining core structures of metallic nanoparticles from atomic pair distribution function data
We present a novel approach for finding and evaluating structural models of
small metallic nanoparticles. Rather than fitting a single model with many
degrees of freedom, the approach algorithmically builds libraries of
nanoparticle clusters from multiple structural motifs, and individually fits
them to experimental PDFs. Each cluster-fit is highly constrained. The
approach, called cluster-mining, returns all candidate structure models that
are consistent with the data as measured by a goodness of fit. It is highly
automated, easy to use, and yields models that are more physically realistic
and result in better agreement to the data than models based on cubic
close-packed crystallographic cores, often reported in the literature for
metallic nanoparticles
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Influence of Clastic Dikes on Vertical Migration of Contaminants in the Vadose Zone at Hanford
This research project addresses the effect of clastic dikes on contaminant transport in the vadose zone. Clastic dikes are vertically oriented subsurface heterogeneities common at the Hanford Site, including within the subsurface sediments below the tank farms in the 200 West Area. Previous studies have suggested that clastic dikes may provide a fast path for transport of leaking fluid from the tanks through the vadose zone. This research is testing the hypothesis that clastic dikes at the Hanford Site provide preferential pathways that enhance the vertical movement of moisture and contaminants through the vadose zone. Current flow and transport models of the vadose zone at the 200 Areas are based on relatively simple hydrogeologic models that assume horizontally layered sediments with no preferential vertical flow paths. To address those scientific needs, our research includes field and modeling studies of the spatial distribution of clastic dikes, the hydrologic properties within dikes, and the potential effect of clastic injection dikes on fluid flow through the vadose zone. The data and models of the clastic dike networks produced for this project should be directly applicable to fate and transport studies conducted at the 200 West Hanford tank farms
Correction: The Reversal of Fortunes: Trends in County Mortality and Cross-County Mortality Disparities in the United States
Burden of Neurological Disorders Across the US From 1990-2017
IMPORTANCE Accurate and up-to-date estimates on incidence, prevalence, mortality, and
disability-adjusted life-years (burden) of neurological disorders are the backbone of
evidence-based health care planning and resource allocation for these disorders. It appears
that no such estimates have been reported at the state level for the US.
OBJECTIVE To present burden estimates of major neurological disorders in the US states by
age and sex from 1990 to 2017.
DESIGN, SETTING, AND PARTICIPANTS This is a systematic analysis of the Global Burden of
Disease (GBD) 2017 study. Data on incidence, prevalence, mortality, and disability-adjusted
life-years (DALYs) of major neurological disorders were derived from the GBD 2017 study of
the 48 contiguous US states, Alaska, and Hawaii. Fourteen major neurological disorders were
analyzed: stroke, Alzheimer disease and other dementias, Parkinson disease, epilepsy,
multiple sclerosis, motor neuron disease, migraine, tension-type headache, traumatic brain
injury, spinal cord injuries, brain and other nervous system cancers, meningitis, encephalitis,
and tetanus.
EXPOSURES Any of the 14 listed neurological diseases.
MAIN OUTCOME AND MEASURE Absolute numbers in detail by age and sex and
age-standardized rates (with 95% uncertainty intervals) were calculated.
RESULTS The 3 most burdensome neurological disorders in the US in terms of absolute
number of DALYs were stroke (3.58 [95% uncertainty interval [UI], 3.25-3.92] million DALYs),
Alzheimer disease and other dementias (2.55 [95% UI, 2.43-2.68] million DALYs), and
migraine (2.40 [95% UI, 1.53-3.44] million DALYs). The burden of almost all neurological
disorders (in terms of absolute number of incident, prevalent, and fatal cases, as well as
DALYs) increased from 1990 to 2017, largely because of the aging of the population.
Exceptions for this trend included traumatic brain injury incidence (−29.1% [95% UI, −32.4%
to −25.8%]); spinal cord injury prevalence (−38.5% [95% UI, −43.1% to −34.0%]); meningitis
prevalence (−44.8% [95% UI, −47.3% to −42.3%]), deaths (−64.4% [95% UI, −67.7% to
−50.3%]), and DALYs (−66.9% [95% UI, −70.1% to −55.9%]); and encephalitis DALYs
(−25.8% [95% UI, −30.7% to −5.8%]). The different metrics of age-standardized rates varied
between the US states from a 1.2-fold difference for tension-type headache to 7.5-fold for
tetanus; southeastern states and Arkansas had a relatively higher burden for stroke, while
northern states had a relatively higher burden of multiple sclerosis and eastern states had
higher rates of Parkinson disease, idiopathic epilepsy, migraine and tension-type headache,
and meningitis, encephalitis, and tetanus.
CONCLUSIONS AND RELEVANCE There is a large and increasing burden of noncommunicable
neurological disorders in the US, with up to a 5-fold variation in the burden of and trends in
particular neurological disorders across the US states. The information reported in this article
can be used by health care professionals and policy makers at the national and state levels to
advance their health care planning and resource allocation to prevent and reduce the burden
of neurological disorders
Measuring universal health coverage based on an index of effective coverage of health services in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
Summary
Background Achieving universal health coverage (UHC) involves all people receiving the health services they need, of
high quality, without experiencing financial hardship. Making progress towards UHC is a policy priority for both
countries and global institutions, as highlighted by the agenda of the UN Sustainable Development Goals (SDGs) and
WHO’s Thirteenth General Programme of Work (GPW13). Measuring effective coverage at the health-system level is
important for understanding whether health services are aligned with countries’ health profiles and are of sufficient
quality to produce health gains for populations of all ages.
Methods Based on the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we assessed UHC
effective coverage for 204 countries and territories from 1990 to 2019. Drawing from a measurement framework
developed through WHO’s GPW13 consultation, we mapped 23 effective coverage indicators to a matrix representing
health service types (eg, promotion, prevention, and treatment) and five population-age groups spanning from
reproductive and newborn to older adults (≥65 years). Effective coverage indicators were based on intervention
coverage or outcome-based measures such as mortality-to-incidence ratios to approximate access to quality care;
outcome-based measures were transformed to values on a scale of 0–100 based on the 2·5th and 97·5th percentile of
location-year values. We constructed the UHC effective coverage index by weighting each effective coverage indicator
relative to its associated potential health gains, as measured by disability-adjusted life-years for each location-year and
population-age group. For three tests of validity (content, known-groups, and convergent), UHC effective coverage
index performance was generally better than that of other UHC service coverage indices from WHO (ie, the current
metric for SDG indicator 3.8.1 on UHC service coverage), the World Bank, and GBD 2017. We quantified frontiers of
UHC effective coverage performance on the basis of pooled health spending per capita, representing UHC effective
coverage index levels achieved in 2019 relative to country-level government health spending, prepaid private
expenditures, and development assistance for health. To assess current trajectories towards the GPW13 UHC billion
target—1 billion more people benefiting from UHC by 2023—we estimated additional population equivalents with
UHC effective coverage from 2018 to 2023.
Findings Globally, performance on the UHC effective coverage index improved from 45·8 (95% uncertainty interval
44·2–47·5) in 1990 to 60·3 (58·7–61·9) in 2019, yet country-level UHC effective coverage in 2019 still spanned from
95 or higher in Japan and Iceland to lower than 25 in Somalia and the Central African Republic. Since 2010,
sub-Saharan Africa showed accelerated gains on the UHC effective coverage index (at an average increase of
2·6% [1·9–3·3] per year up to 2019); by contrast, most other GBD super-regions had slowed rates of progress in
2010–2019 relative to 1990–2010. Many countries showed lagging performance on effective coverage indicators for
non-communicable diseases relative to those for communicable diseases and maternal and child health, despite noncommunicable diseases accounting for a greater proportion of potential health gains in 2019, suggesting that many
health systems are not keeping pace with the rising non-communicable disease burden and associated population
health needs. In 2019, the UHC effective coverage index was associated with pooled health spending per capita
(r=0·79), although countries across the development spectrum had much lower UHC effective coverage than is
potentially achievable relative to their health spending. Under maximum efficiency of translating health spending
into UHC effective coverage performance, countries would need to reach adjusted for purchasing power parity) in order to achieve 80 on the UHC effective coverage index. From
2018 to 2023, an estimated 388·9 million (358·6–421·3) more population equivalents would have UHC effective
coverage, falling well short of the GPW13 target of 1 billion more people benefiting from UHC during this time.
Current projections point to an estimated 3·1 billion (3·0–3·2) population equivalents still lacking UHC effective
coverage in 2023, with nearly a third (968·1 million [903·5–1040·3]) residing in south Asia.
Interpretation The present study demonstrates the utility of measuring effective coverage and its role in supporting
improved health outcomes for all people—the ultimate goal of UHC and its achievement. Global ambitions to accelerate progress on UHC service coverage are increasingly unlikely unless concerted action on non-communicable
diseases occurs and countries can better translate health spending into improved performance. Focusing on effective
coverage and accounting for the world’s evolving health needs lays the groundwork for better understanding how
close—or how far—all populations are in benefiting from UH
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