480 research outputs found
Public Health Care Delivery in Five U.S. Municipalities: Lessons and Implications
Increasing pressures on private and public hospitals have necessitated a reassessment of urban health care delivery. Patients left unserved by stressed private hospitals have placed a greater burden on public institutions, which themselves are often old, underfunded, and in danger of closure. As policy analysts consider remedies, primary care in community-based settings has reemerged as an important component of planning. We present results of a comparative analysis of five public health care delivery systems (Boston, Dallas, Denver, Milwaukee, and Seattle), reflecting their economic, political, and cultural dynamics. Although significant differences in the relative centralization of care and reliance on community-based clinics are evident, the five cities discussed have incorporated an increased emphasis on preventive and primary care. The diversity among the systems is highlighted: adaptability is apparently a vital component in designing a public health care system appropriate to the needs of particular communities. Implications for Chicago and other cities are discussed
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Parallel, out-of-core methods for N-body simulation
Hierarchical treecodes have, to a large extent, converted the compute-bound N-body problem into a memory-bound problem. The large ratio of DRAM to disk pricing suggests use of out-of-core techniques to overcome memory capacity limitations. The authors describe a parallel, out-of-core treecode library, targeted at machines with independent secondary storage associated with each processor. Borrowing the space-filling curve techniques from the in-core library, and manually paging, resulting in excellent spatial and temporal locality and very good performance
Imprints of dark energy on cosmic structure formation: II) Non-Universality of the halo mass function
The universality of the halo mass function is investigated in the context of
dark energy cosmologies. This widely used approximation assumes that the mass
function can be expressed as a function of the matter density omega_m and the
rms linear density fluctuation sigma only, with no explicit dependence on the
properties of dark energy or redshift. In order to test this hypothesis we run
a series of 15 high-resolution N-body simulations for different cosmological
models. These consists of three LCDM cosmologies best fitting WMAP-1, 3 and 5
years data, and three toy-models characterized by a Ratra-Peebles quintessence
potential with different slopes and amounts of dark energy density. These toy
models have very different evolutionary histories at the background and linear
level, but share the same sigma8 value. For each of these models we measure the
mass function from catalogues of halos identified in the simulations using the
Friend-of-Friend (FoF) algorithm. We find redshift dependent deviations from a
universal behaviour, well above numerical uncertainties and of non-stochastic
origin, which are correlated with the linear growth factor of the investigated
cosmologies. Using the spherical collapse as guidance, we show that such
deviations are caused by the cosmology dependence of the non-linear collapse
and virialization process. For practical applications, we provide a fitting
formula of the mass function accurate to 5 percents over the all range of
investigated cosmologies. We also derive an empirical relation between the FoF
linking parameter and the virial overdensity which can account for most of the
deviations from an exact universal behavior. Overall these results suggest that
the halo mass function contains unique cosmological information since it
carries a fossil record of the past cosmic evolution.Comment: 21 pages, 19 figures, 5 tables, published in MNRAS. Paper I:
arXiv:0903.549
N-body simulations of gravitational dynamics
We describe the astrophysical and numerical basis of N-body simulations, both
of collisional stellar systems (dense star clusters and galactic centres) and
collisionless stellar dynamics (galaxies and large-scale structure). We explain
and discuss the state-of-the-art algorithms used for these quite different
regimes, attempt to give a fair critique, and point out possible directions of
future improvement and development. We briefly touch upon the history of N-body
simulations and their most important results.Comment: invited review (28 pages), to appear in European Physics Journal Plu
Standards recommendations for the Earth BioGenome Project
A global international initiative, such as the Earth BioGenome Project (EBP), requires both agreement and coordination on standards to ensure that the collective effort generates rapid progress toward its goals. To this end, the EBP initiated five technical standards committees comprising volunteer members from the global genomics scientific community: Sample Collection and Processing, Sequencing and Assembly, Annotation, Analysis, and IT and Informatics. The current versions of the resulting standards documents are available on the EBP website, with the recognition that opportunities, technologies, and challenges may improve or change in the future, requiring flexibility for the EBP to meet its goals. Here, we describe some highlights from the proposed standards, and areas where additional challenges will need to be met
“Medically unexplained” symptoms and symptom disorders in primary care: prognosis-based recognition and classification
Background: Many patients consult their GP because they experience bodily symptoms. In a substantial proportion of
cases, the clinical picture does not meet the existing diagnostic criteria for diseases or disorders. This may be because
symptoms are recent and evolving or because symptoms are persistent but, either by their character or the negative
results of clinical investigation cannot be attributed to disease: so-called “medically unexplained symptoms” (MUS).
MUS are inconsistently recognised, diagnosed and managed in primary care. The specialist classification systems
for MUS pose several problems in a primary care setting. The systems generally require great certainty about
presence or absence of physical disease, they tend to be mind-body dualistic, and they view symptoms from a
narrow specialty determined perspective. We need a new classification of MUS in primary care; a classification
that better supports clinical decision-making, creates clearer communication and provides scientific underpinning
of research to ensure effective interventions.
Discussion: We propose a classification of symptoms that places greater emphasis on prognostic factors.
Prognosis-based classification aims to categorise the patient’s risk of ongoing symptoms, complications, increased
healthcare use or disability because of the symptoms. Current evidence suggests several factors which may be
used: symptom characteristics such as: number, multi-system pattern, frequency, severity. Other factors are:
concurrent mental disorders, psychological features and demographic data. We discuss how these characteristics may
be used to classify symptoms into three groups: self-limiting symptoms, recurrent and persistent symptoms, and
symptom disorders. The middle group is especially relevant in primary care; as these patients generally have reduced
quality of life but often go unrecognised and are at risk of iatrogenic harm. The presented characteristics do not
contain immediately obvious cut-points, and the assessment of prognosis depends on a combination of several factors.
Conclusion: Three criteria (multiple symptoms, multiple systems, multiple times) may support the classification into
good, intermediate and poor prognosis when dealing with symptoms in primary care. The proposed new classification
specifically targets the patient population in primary care and may provide a rational framework for decision-making in
clinical practice and for epidemiologic and clinical research of symptoms
The Neuronal Correlates of Digits Backward Are Revealed by Voxel-Based Morphometry and Resting-State Functional Connectivity Analyses
Digits backward (DB) is a widely used neuropsychological measure that is believed to be a simple and effective index of the capacity of the verbal working memory. However, its neural correlates remain elusive. The aim of this study is to investigate the neural correlates of DB in 299 healthy young adults by combining voxel-based morphometry (VBM) and resting-state functional connectivity (rsFC) analyses. The VBM analysis showed positive correlations between the DB scores and the gray matter volumes in the right anterior superior temporal gyrus (STG), the right posterior STG, the left inferior frontal gyrus and the left Rolandic operculum, which are four critical areas in the auditory phonological loop of the verbal working memory. Voxel-based correlation analysis was then performed between the positive rsFCs of these four clusters and the DB scores. We found that the DB scores were positively correlated with the rsFCs within the salience network (SN), that is, between the right anterior STG, the dorsal anterior cingulate cortex and the right fronto-insular cortex. We also found that the DB scores were negatively correlated with the rsFC within an anti-correlation network of the SN, between the right posterior STG and the left posterior insula. Our findings suggest that DB performance is related to the structural and functional organizations of the brain areas that are involved in the auditory phonological loop and the SN
High rates of breast conservation for large ductal and lobular invasive carcinomas combining multimodality strategies
The literature reports low rates of breast conservation after neoadjuvant chemotherapy for operable breast cancers not amenable to initial breast-conserving surgery. This study aims to compare the outcome of lobular vs ductal carcinomas after neoadjuvant chemotherapy. Between 1989 and 1999, 750 patients with clinical stage II/IIIA ductal (672) or lobular (78) invasive breast carcinomas were treated at the Institut Curie with primary anthracycline-based polychemotherapy followed by either breast conservation (surgery and/or radiotherapy) or mastectomy. Median follow-up was 10 years. Clinical response to primary chemotherapy was significantly worse for lobular than for ductal carcinomas (47 vs 60%; P=0.04), but only histological grade remained predictive in multivariate analysis. Breast conservation was high for both ductal and lobular carcinomas (65 and 54%; P=0.07), due, in part, to the use of radiotherapy, either exclusive or preoperative, for respectively 26 and 40% of patients. The lobular type had no adverse effect, neither on locoregional control nor on overall survival, even in the group of patients treated with breast conservation
Genome of Rhodnius prolixus, an insect vector of Chagas disease, reveals unique adaptations to hematophagy and parasite infection
Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome ( approximately 702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods
Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET
Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate
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