208 research outputs found
Observer Dependent Horizon Temperatures: a Coordinate-Free Formulation of Hawking Radiation as Tunneling
We reformulate the Hamilton-Jacobi tunneling method for calculating Hawking
radiation in static, spherically-symmetric spacetimes by explicitly
incorporating a preferred family of frames. These frames correspond to a family
of observers tied to a locally static timelike Killing vector of the spacetime.
This formulation separates the role of the coordinates from the choice of
vacuum and thus provides a coordinate-independent formulation of the tunneling
method. In addition, it clarifies the nature of certain constants and their
relation to these preferred observers in the calculation of horizon
temperatures. We first use this formalism to obtain the expected temperature
for a static observer at finite radius in the Schwarzschild spacetime. We then
apply this formalism to the Schwarzschild-de Sitter spacetime, where there is
no static observer with 4-velocity equal to the static timelike Killing vector.
It is shown that a preferred static observer, one whose trajectory is geodesic,
measures the lowest temperature from each horizon. Furthermore, this observer
measures horizon temperatures corresponding to the well-known Bousso-Hawking
normalization.Comment: 11 pages, 1 2-part figure, references added, appendix added,
discussion streamline
The Manyano movement within the Methodist Church of Southern Africa : an expression of freedom of worship (1844-1944)
Peer reviewedThe arrival of the Methodist/Wesleyan mission and missionaries
in Africa heralded a religious stringency that did not
afford the indigenous people religious freedom. In response, a
number of movements were formed from within the church by
indigenous people. Many of these emerged as Manyano
movements. The various forms that these movements took
were intended to address a range of Christian understandings of
what may be termed a rite of passage with regard to age,
gender, race and non-affiliation. The history of these churches
in Africa, and South Africa in particular, has revealed the
schism that later led to the formation of the African
Independent Churches. These movements introduced a new
trend in these traditionally European churches involving the
expression of religious freedom and worship from within rather
than imposed from without.Research Institute for Theology and Religio
The influence of Calvinism on South Africa's education system prior to 1994
Peer reviewedIn South Africa, Calvinism has exercised a profound influence on theology and this
influence extended to education. Indeed, Calvinism played a major role in shaping a local
education system which was adopted as a result of a specific political ideology. In this
article, we intend to show how Calvinism was used to justify the superiority of one group
of people over another through the education system. This article will look at the ideals
of Calvin in South Africa in the context of formal education during the apartheid era, and
offer a critique of formal education before 1994. It will be argued that, in his theology,
Calvin himself emphasised healthy values such as accountability, communication,
obedience, orderliness, lack of oppression, responsibility and the rule of law. However,
these values were either ignored in the local version of Calvinist education, or applied
from a racist perspective.Research Institute for Theology and Religio
Racial differences in influenza vaccination among older americans 1996–2000: longitudinal analysis of the Health and Retirement Study (HRS) and the Asset and Health Dynamics Among the Oldest Old (AHEAD) survey
BACKGROUND: Influenza is a common and serious public health problem among the elderly. The influenza vaccine is safe and effective. METHODS: The purpose of the study was to determine whether frequencies of receipt vary by race, age group, gender, and time (progress from 1995/1996 to 2000), and whether any racial differences remain in age groups covered by Medicare. Subjects were selected from the Health and Retirement Study (HRS) (12,652 Americans 50–61 years of age (1992–2000)) and the Asset and Health Dynamics Among the Oldest Old (AHEAD) survey (8,124 community-dwelling seniors aged 70+ years (1993–2000)). Using multivariate logistic regression, adjusting for potential confounders, we estimated the relationship between race, age group, gender, time and the main outcome measure, receipt of influenza vaccination in the last 2 years. RESULTS: There has been a clear increase in the unadjusted rates of receipt of influenza vaccination for all groups from 1995/1996 to 2000. However, the proportions immunized are 10–20% higher among White than among Black elderly, with no obvious narrowing of the racial gap from 1995/1996 to 2000. There is an increase in rates from age 50 to age 65. After age 70, the rate appears to plateau. In multivariate analyses, the racial difference remains after adjusting for a series of socioeconomic, health, and health care related variables. (HRS: OR = 0.63 (0.55–0.72), AHEAD: OR = 0.55 (0.44–0.66)) CONCLUSIONS: There is much work left if the Healthy People 2010 goal of 90% of the elderly immunized against influenza annually is to be achieved. Close coordination between public health programs and clinical prevention efforts in primary care is necessary, but to be truly effective, these services must be culturally appropriate
Genome-Wide Association Studies of Cognitive and Motor Progression in Parkinson's Disease.
BACKGROUND: There are currently no treatments that stop or slow the progression of Parkinson's disease (PD). Case-control genome-wide association studies have identified variants associated with disease risk, but not progression. The objective of the current study was to identify genetic variants associated with PD progression. METHODS: We analyzed 3 large longitudinal cohorts: Tracking Parkinson's, Oxford Discovery, and the Parkinson's Progression Markers Initiative. We included clinical data for 3364 patients with 12,144 observations (mean follow-up 4.2 years). We used a new method in PD, following a similar approach in Huntington's disease, in which we combined multiple assessments using a principal components analysis to derive scores for composite, motor, and cognitive progression. These scores were analyzed in linear regression in genome-wide association studies. We also performed a targeted analysis of the 90 PD risk loci from the latest case-control meta-analysis. RESULTS: There was no overlap between variants associated with PD risk, from case-control studies, and PD age at onset versus PD progression. The APOE ε4 tagging variant, rs429358, was significantly associated with composite and cognitive progression in PD. Conditional analysis revealed several independent signals in the APOE locus for cognitive progression. No single variants were associated with motor progression. However, in gene-based analysis, ATP8B2, a phospholipid transporter related to vesicle formation, was nominally associated with motor progression (P = 5.3 × 10-6 ). CONCLUSIONS: We provide early evidence that this new method in PD improves measurement of symptom progression. We show that the APOE ε4 allele drives progressive cognitive impairment in PD. Replication of this method and results in independent cohorts are needed. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.Funding sources: Parkinson’s U
Alternatives to project-specific consent for access to personal information for health research: Insights from a public dialogue
<p>Abstract</p> <p>Background</p> <p>The role of consent for research use of health information is contentious. Most discussion has focused on when project-specific consent may be waived but, recently, a broader range of consent options has been entertained, including broad opt-in for multiple studies with restrictions and notification with opt-out. We sought to elicit public values in this matter and to work toward an agreement about a common approach to consent for use of personal information for health research through deliberative public dialogues.</p> <p>Methods</p> <p>We conducted seven day-long public dialogues, involving 98 participants across Canada. Immediately before and after each dialogue, participants completed a fixed-response questionnaire rating individuals' support for 3 approaches to consent in the abstract and their consent choices for 5 health research scenarios using personal information. They also rated how confident different safeguards made them feel that their information was being used responsibly.</p> <p>Results</p> <p>Broad opt-in consent for use of personal information garnered the greatest support in the abstract. When presented with specific research scenarios, no one approach to consent predominated. When profit was introduced into the scenarios, consent choices shifted toward greater control over use. Despite lively and constructive dialogues, and considerable shifting in opinion at the individual level, at the end of the day, there was no substantive aggregate movement in opinion. Personal controls were among the most commonly cited approaches to improving people's confidence in the responsible use of their information for research.</p> <p>Conclusion</p> <p>Because no one approach to consent satisfied even a simple majority of dialogue participants and the importance placed on personal controls, a mechanism should be developed for documenting consent choice for different types of research, including ways for individuals to check who has accessed their medical record for purposes other than clinical care. This could be done, for example, through a web-based patient portal to their electronic health record. Researchers and policy makers should continue to engage the public to promote greater public understanding of the research process and to look for feasible alternatives to existing approaches to project-specific consent for observational research.</p
Mendelian adult-onset leukodystrophy genes in Alzheimer´s disease. Critical influence of CSF1R and NOTCH3
Mendelian adult-onset leukodystrophies are a spectrum of rare inherited progressive neurodegenerative disorders affecting the white matter of the central nervous system. Among these, Cerebral Autosomal Dominant and Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL and CARASIL), Cerebroretinal vasculopathy (CRV), Metachromatic leukodystrophy (MLD), Hereditary diffuse Leukoencephalopathy with spheroids (HDLS), Vanishing white matter disease (VWM) present with rapidly progressive dementia as dominant feature and are caused by mutations in NOTCH3, HTRA1, TREX1, ARSA, CSF1R, EIF2B1, EIF2B2, EIF2B3, EIF2B4, EIF2B5, respectively. Given the rare incidence of these disorders and the lack of unequivocally diagnostic features, leukodystrophies are frequently misdiagnosed with common sporadic dementing diseases such as Alzheimer’s disease (AD), raising the question of whether these overlapping phenotypes may be explained by shared genetic risk factors. To investigate this intriguing hypothesis, we have combined gene expression analysis 1) in 6 different AD mouse strains (APPPS1, HOTASTPM, HETASTPM, TPM, TAS10 and TAU), at 5 different developmental stages (Embryo [E15], 2 months, 4 months, 8 months and 18 months), 2) in APPPS1 primary cortical neurons under stress conditions (oxygen-glucose deprivation) and single-variant and single-gene (c-alpha and SKAT tests) based genetic screening in a cohort composed of 332 Caucasian late-onset AD patients and 676 Caucasian elderly controls. Csf1r was significantly overexpressed (Log2FC>1, adj. p-val<0.05) in the cortex and hippocampus of aged HOTASTPM mice with extensive Aβ core dense plaque pathology. We identified 3 likely pathogenic mutations in CSF1R TK domain (p.L868R, p.Q691H and p.H703Y) in our discovery and validation cohort, composed of 465 AD and MCI Caucasian patients from the UK. Moreover, NOTCH3 was a significant hit in the c-alpha test (adj p-val = 0.01). Adult onset Mendelian leukodystrophy genes are not common factors implicated in AD. Nevertheless, our study suggests a potential pathogenic link between NOTCH3, CSF1R and sporadic LOAD, that warrants further investigation
ABCA7 p.G215S as potential protective factor for Alzheimer’s disease
Genome-wide association studies (GWASs) have been effective approaches to dissect common genetic variability underlying complex diseases in a systematic and unbiased way. Recently, GWASs have led to the discovery of over 20 susceptibility loci for Alzheimer’s disease (AD).
Despite the evidence showing the contribution of these loci to AD pathogenesis, their genetic architecture has not been extensively investigated, leaving the possibility that low frequency and rare coding variants may also occur and contribute to the risk of disease. We have used exome and genome sequencing data to analyse the single independent and joint effect of rare and low frequency protein coding variants in 9 AD GWAS loci with the strongest effect sizes after APOE (BIN1, CLU, CR1, PICALM, MS4A6A, ABCA7, EPHA1, CD33, CD2AP) in a cohort of 332 sporadic AD cases and 676 elderly controls of British and North American ancestry. We identified coding variability in ABCA7 as contributing to AD risk. This locus harbors a low frequency coding variant (p.G215S, rs72973581, MAF=4.3%) conferring a modest but statistically significant protection against AD (p-value= 6x10-4, OR=0.57, 95% CI 0.41-0.80). Notably, our results are not driven by an enrichment of loss of function variants in ABCA7, recently reported as main pathogenic factor underlying AD risk at this locus. In summary, our study confirms the role of ABCA7 in AD and provide new insights that should address functional studies
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