We present a highly-parallel multi-frequency hybrid radiation hydrodynamics algorithm that combines a spatially-adaptive long characteristics method for the radiation field from point sources with a ...moment method that handles the diffuse radiation field produced by a volume-filling fluid. Our Hybrid Adaptive Ray-Moment Method (HARM2) operates on patch-based adaptive grids, is compatible with asynchronous time stepping, and works with any moment method. In comparison to previous long characteristics methods, we have greatly improved the parallel performance of the adaptive long-characteristics method by developing a new completely asynchronous and non-blocking communication algorithm. As a result of this improvement, our implementation achieves near-perfect scaling up to O(103) processors on distributed memory machines. We present a series of tests to demonstrate the accuracy and performance of the method.
A 'frontal variant of Alzheimer's disease' has been described in patients with predominant behavioural or dysexecutive deficits caused by Alzheimer's disease pathology. The description of this rare ...Alzheimer's disease phenotype has been limited to case reports and small series, and many clinical, neuroimaging and neuropathological characteristics are not well understood. In this retrospective study, we included 55 patients with Alzheimer's disease with a behavioural-predominant presentation (behavioural Alzheimer's disease) and a neuropathological diagnosis of high-likelihood Alzheimer's disease (n = 17) and/or biomarker evidence of Alzheimer's disease pathology (n = 44). In addition, we included 29 patients with autopsy/biomarker-defined Alzheimer's disease with a dysexecutive-predominant syndrome (dysexecutive Alzheimer's disease). We performed structured chart reviews to ascertain clinical features. First symptoms were more often cognitive (behavioural Alzheimer's disease: 53%; dysexecutive Alzheimer's disease: 83%) than behavioural (behavioural Alzheimer's disease: 25%; dysexecutive Alzheimer's disease: 3%). Apathy was the most common behavioural feature, while hyperorality and perseverative/compulsive behaviours were less prevalent. Fifty-two per cent of patients with behavioural Alzheimer's disease met diagnostic criteria for possible behavioural-variant frontotemporal dementia. Overlap between behavioural and dysexecutive Alzheimer's disease was modest (9/75 patients). Sixty per cent of patients with behavioural Alzheimer's disease and 40% of those with the dysexecutive syndrome carried at least one APOE ε4 allele. We also compared neuropsychological test performance and brain atrophy (applying voxel-based morphometry) with matched autopsy/biomarker-defined typical (amnestic-predominant) Alzheimer's disease (typical Alzheimer's disease, n = 58), autopsy-confirmed/Alzheimer's disease biomarker-negative behavioural variant frontotemporal dementia (n = 59), and controls (n = 61). Patients with behavioural Alzheimer's disease showed worse memory scores than behavioural variant frontotemporal dementia and did not differ from typical Alzheimer's disease, while executive function composite scores were lower compared to behavioural variant frontotemporal dementia and typical Alzheimer's disease. Voxel-wise contrasts between behavioural and dysexecutive Alzheimer's disease patients and controls revealed marked atrophy in bilateral temporoparietal regions and only limited atrophy in the frontal cortex. In direct comparison with behavioural and those with dysexecutive Alzheimer's disease, patients with behavioural variant frontotemporal dementia showed more frontal atrophy and less posterior involvement, whereas patients with typical Alzheimer's disease were slightly more affected posteriorly and showed less frontal atrophy (P < 0.001 uncorrected). Among 24 autopsied behavioural Alzheimer's disease/dysexecutive Alzheimer's disease patients, only two had primary co-morbid FTD-spectrum pathology (progressive supranuclear palsy). In conclusion, behavioural Alzheimer's disease presentations are characterized by a milder and more restricted behavioural profile than in behavioural variant frontotemporal dementia, co-occurrence of memory dysfunction and high APOE ε4 prevalence. Dysexecutive Alzheimer's disease presented as a primarily cognitive phenotype with minimal behavioural abnormalities and intermediate APOE ε4 prevalence. Both behavioural Alzheimer's disease and dysexecutive Alzheimer's disease presentations are distinguished by temporoparietal-predominant atrophy. Based on the relative sparing of frontal grey matter, we propose to redefine these clinical syndromes as 'the behavioural/dysexecutive variant of Alzheimer's disease' rather than frontal variant Alzheimer's disease. Further work is needed to determine whether behavioural and dysexecutive-predominant presentations of Alzheimer's disease represent distinct phenotypes or a single continuum.
The Determinants of Peak Bone Mass Gordon, Catherine M., MD, MSc; Zemel, Babette S., PhD; Wren, Tishya A.L., PhD ...
The Journal of pediatrics,
01/2017, Letnik:
180
Journal Article
Context.
The infrared dark cloud (IRDC) SDC335.579-0.292 (hereafter, SDC335) is a massive (~5000
M
⊙
) star-forming cloud which has been found to be globally collapsing towards one of the most ...massive star forming cores in the Galaxy, which is located at its centre. SDC335 is known to host three high-mass protostellar objects at early stages of their evolution and archival ALMA Cycle 0 data (at ~5′′ resolution) indicate the presence of at least one molecular outflow in the region detected in HNC. Observations of molecular outflows from massive protostellar objects allow us to estimate the accretion rates of the protostars as well as to assess the disruptive impact that stars have on their natal clouds during their formation.
Aims.
The aim of this work is to identify and analyse the properties of the protostellar-driven molecular outflows within SDC335 and use these outflows to help refine the properties of the young massive protostars in this cloud.
Methods.
We imaged the molecular outflows in SDC335 using new data from the Australia Telescope Compact Array of SiO and Class I CH
3
OH maser emission (at a resolution of ~3′′) alongside observations of four CO transitions made with the Atacama Pathfinder EXperiment and archival Atacama Large Millimeter/submillimeter Array (ALMA) CO,
13
CO (~1′′), and HNC data. We introduced a generalised argument to constrain outflow inclination angles based on observed outflow properties. We then used the properties of each outflow to infer the accretion rates on the protostellar sources driving them. These accretion properties allowed us to deduce the evolutionary characteristics of the sources. Shock-tracing SiO emission and CH
3
OH Class I maser emission allowed us to locate regions of interaction between the outflows and material infalling to the central region via the filamentary arms of SDC335.
Results.
We identify three molecular outflows in SDC335 – one associated with each of the known compact H
II
regions in the IRDC. These outflows have velocity ranges of ~10 km s
−1
and temperatures of ~60 K. The two most massive sources (separated by ~9000 AU) have outflows with axes which are, in projection, perpendicular. A well-collimated jet-like structure with a velocity gradient of ~155 km s
−1
pc
−1
is detected in the lobes of one of the outflows. The outflow properties show that the SDC335 protostars are in the early stages (Class 0) of their evolution, with the potential to form stars in excess of 50
M
⊙
. The measured total accretion rate, inferred from the outflows, onto the protostars is 1.4(±0.1) × 10
−3
M
⊙
yr
−1
, which is comparable to the total mass infall rate toward the cloud centre on parsec scales of 2.5(±1.0) × 10
−3
M
⊙
yr
−1
, suggesting a near-continuous flow of material from cloud to core scales. Finally, we identify multiple regions where the outflows interact with the infalling material in the cloud’s six filamentary arms, creating shocked regions and pumping Class I methanol maser emission. These regions provide useful case studies for future investigations of the disruptive effect of young massive stars on their natal clouds.
Abstract
Recent observations indicate that the cross-sectional area (CSA) of vertebral bodies is on average 10% smaller in healthy newborn girls than in newborn boys, a striking difference that ...increases during infancy and puberty and is greatest by the time of sexual and skeletal maturity. The smaller CSA of female vertebrae is associated with greater spinal flexibility and could represent the human adaptation to fetal load in bipedal posture. Unfortunately, it also imparts a mechanical disadvantage that increases stress within the vertebrae for all physical activities. This review summarizes the potential endocrine, genetic, and environmental determinants of vertebral cross-sectional growth and current knowledge of the association between the small female vertebrae and greater risk for a broad array of spinal conditions across the lifespan.
The smaller female vertebra is associated with greater spinal flexibility and lesser vertebral strength, probably contributing to a broad array of spinal conditions across the lifespan.
The aetiology and pathogenesis of non-genetic forms of frontotemporal dementia (FTD) is unknown and even with the genetic forms of FTD, pathogenesis remains elusive. Given the association between ...systemic inflammation and other neurodegenerative processes, links between autoimmunity and FTD need to be explored.
To describe the prevalence of systemic autoimmune disease in semantic variant primary progressive aphasia (svPPA), a clinical cohort, and in progranulin (PGRN) mutation carriers compared with neurologically healthy normal controls (NC) and Alzheimer's disease (AD) as dementia controls.
Case control.
Academic medical centres.
129 svPPA, 39 PGRN, 186 NC and 158 AD patients underwent chart review for autoimmune conditions. A large subset of svPPA, PGRN and NC cohorts underwent serum analysis for tumour necrosis factor α (TNF-α) levels.
χ(2) Comparison of autoimmune prevalence and follow-up logistic regression.
There was a significantly increased risk of autoimmune disorders clustered around inflammatory arthritides, cutaneous disorders and gastrointestinal conditions in the svPPA and PGRN cohorts. Elevated TNF-α levels were observed in svPPA and PGRN compared with NC.
svPPA and PGRN are associated with increased prevalence of specific and related autoimmune diseases compared with NC and AD. These findings suggest a unique pattern of systemic inflammation in svPPA and PGRN and open new research avenues for understanding and treating disorders associated with underlying transactive response DNA-binding protein 43 aggregation.
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