1,220 research outputs found
Islamic Parochial Education in the United States: A Study of Two Atlanta-Area Schools
Through a comparative study of two Atlanta full-time Muslim parochial schools, this study examines Muslim approaches to Islamic education by analyzing school leaders\u27 secular and religious goals, their main obstacles and concerns, and what they believe the best practices are. The study explores leaders’ visions of socialization and community development by juxtaposing findings from two schools. In order to answer the aforementioned questions, this study 1) assesses national trends in K-12 Islamic parochial schools across the United States through related research, 2) engages Muslim leaders from both institutions through semi-formal interviews, and 3) supplements findings through an extended period of participant observation
A phase-shift-periodic parallel boundary condition for low-magnetic-shear scenarios
We formulate a generalized periodic boundary condition as a limit of the
standard twist-and-shift parallel boundary condition that is suitable for
simulations of plasmas with low magnetic shear. This is done by applying a
phase shift in the binormal direction when crossing the parallel boundary.
While this phase shift can be set to zero without loss of generality in the
local flux-tube limit when employing the twist-and-shift boundary condition, we
show that this is not the most general case when employing periodic parallel
boundaries, and may not even be the most desirable. A non-zero phase shift can
be used to avoid the convective cells that plague simulations of the
three-dimensional Hasegawa-Wakatani system, and is shown to have measurable
effects in periodic low-magnetic-shear gyrokinetic simulations. We propose a
numerical program where a sampling of periodic simulations at random
pseudo-irrational flux surfaces are used to determine physical observables in a
statistical sense. This approach can serve as an alternative to applying the
twist-and-shift boundary condition to low-magnetic-shear scenarios which, while
more straightforward, can be computationally demanding.Comment: 4 figures, 1 tabl
Sleep Extension in Short Sleepers: An Evaluation of Feasibility and Effectiveness for Weight Management and Cardiometabolic Disease Prevention
Sleep duration has become increasingly recognized as an important influencer of health. Epidemiologic and observational studies have shown associations between short sleep duration and increased risk for chronic cardiometabolic disorders, including obesity, type 2 diabetes, and cardiovascular disease. These associations have led to investigations into the potential causal pathways through which short sleep may increase risk for these disorders. Clinical intervention studies have demonstrated that restricting sleep in normal sleepers has adverse health effects, including insulin resistance, and increased blood pressure. The totality of evidence points to negative health effects of short sleep and the recognition of sleep as a lifestyle behavior that may be targeted for disease prevention. It is well established that consistent, adequate sleep is associated with the lowest risk of obesity and cardiometabolic disorders. Yet, it is unclear whether increasing sleep in short sleepers can improve health. In today's society, it is common for individuals to deprive themselves of sleep during the work week, with the intent to sleep longer during the weekend, or have “catch-up sleep.” Studies that have examined the health effects of extended sleep, post-sleep restriction, revealed some improvements in health outcomes. However, it is uncertain whether the improvements observed with catch-up sleep are sufficient to reverse the negative health effects of constant sleep restriction. Few intervention studies have been undertaken to determine whether extending sleep, long-term, in short sleepers is feasible and whether it can reduce the disease risk burden associated with short sleep duration. The purpose of this review is to highlight these studies and evaluate information related to the impact of sleep extension on risk factors for chronic cardiometabolic disorders. We discuss limitations of current research, including variability in participant characteristics and the extent to which sleep behaviors are modified and monitored. Although the evidence-base for benefits of sleep extension is still in the early stages, studies to date indicate that prolonging sleep, in short sleepers, may improve cardiometabolic risk. Finally, our review calls attention to areas that require further study and for larger scale studies of behavior modification to establish the health effects of sleep extension in short sleepers
Basement-cover relations and internal structure of the Cape Smith klippe: A 1.9 Ga greenstone belt in northern Quebec, Canada
The Cape Smith Belt is a 380x60 km tectonic klippe composed of greenschistto amphibolite-grade mafic and komatiitic lava flows and fine-grained quartzose sediment, intruded by minor syn- to post-tectonic granitoids. Previously studied transects in areas of relatively high structural level show that the belt is constructed of seven or more north-dipping thrust sheets which verge toward the Superior Province (Archean) foreland in the south and away from an Archean basement massif (Kovik Antiform) external to the Trans-Hudson Orogen (Early Proterozoic) in the north. A field project (mapping and structural-stratigraphic-metamorphic studies) directed by MRS was begun in 1985 aimed at the structurally deeper levels of the belt and underlying basement, which are superby exposed in oblique cross-section (12 km minimum structural relief) at the west-plunging eastern end of the belt. Mapping now complete of the eastern end of the belt confirms that all of the metavolcanic and most of the metasedimentary rocks are allochthonous with respect to the Archean basement, and that the thrusts must have been rooted north of Kovik Antiform. The main findings follow
Localization, epidemic transitions, and unpredictability of multistrain epidemics with an underlying genotype network
Mathematical disease modelling has long operated under the assumption that
any one infectious disease is caused by one transmissible pathogen spreading
among a population. This paradigm has been useful in simplifying the biological
reality of epidemics and has allowed the modelling community to focus on the
complexity of other factors such as population structure and interventions.
However, there is an increasing amount of evidence that the strain diversity of
pathogens, and their interplay with the host immune system, can play a large
role in shaping the dynamics of epidemics. Here, we introduce a disease model
with an underlying genotype network to account for two important mechanisms.
One, the disease can mutate along network pathways as it spreads in a host
population. Two, the genotype network allows us to define a genetic distance
across strains and therefore to model the transcendence of immunity often
observed in real world pathogens. We study the emergence of epidemics in this
model, through its epidemic phase transitions, and highlight the role of the
genotype network in driving cyclicity of diseases, large scale fluctuations,
sequential epidemic transitions, as well as localization around specific
strains of the associated pathogen. More generally, our model illustrates the
richness of behaviours that are possible even in well-mixed host populations
once we consider strain diversity and go beyond the "one disease equals one
pathogen" paradigm
Preliminary geophysical interpretation of the McKeand River area, southern Baffin Island, Nunavut: insights from gravity, magnetic and geological data
The recently completed McKeand River and Amittok Lake aeromagnetic surveys on southern Baffin Island, Nunavut pro-
vide a new high-resolution magnetic dataset over an area with no previous coverage. Complemented by regional gravity
data, newly acquired rock-property information and geological-mapping products, the aeromagnetic dataset yields qualita-
tive and quantitative information on the structure and geology of the underlying bedrock. This paper presents a preliminary
interpretation of these datasets that delineates three gravimetric and five magnetic domains. The gravity data outline a broad
negative anomaly associated with a plutonic-intrusive suite, as well as several isolated gravity highs associated with
metasedimentary strata. Magnetic domains are defined on the basis of anomaly amplitude, wavelength and texture, and are
correlated to the mapped geology and magnetic properties. Associations between potential-field anomalies, physical prop-
erties and mineral occurrences help define the regional distribution of economically significant horizons
Contextualising the Permian Sumdo eclogite belt, Lhasa block, Tibet
Abstract HKT-ISTP 2013
A
Record of modern-style plate tectonics in the Palaeoproterozoic Trans-Hudson orogen
The Trans-Hudson orogen of North America is a circa 1,800 million year old, middle Palaeoproterozoic continental collisional belt. The orogen may represent an ancient analogue to the Himalayan orogen, which began forming 50 million years ago and remains active today. Both mountain belts exhibit similar length scales of deformation and timescales of magmatism and metamorphism. A notable divergence in this correlation has been the absence of high-pressure, low-temperature metamorphic rocks in the Trans-Hudson compared with the Himalaya. It has been debated whether this absence reflects a secular tectonic change, with the requisite cool thermal gradients precluded by warmer ambient mantle temperatures during the Palaeoproterozoic, or a lack of preservation. Here we identify eclogite rocks within the Trans-Hudson orogen. These rocks, which typically form at high pressures and cool temperatures during subduction, fill the gap in the comparative geologic record between the Trans-Hudson and Himalayan orogens. Through the application of phase equilibria modelling and in situ U–Pb monazite dating we show that the pressure–temperature conditions and relative timing of eclogite-facies metamorphism are comparable in both orogenies. The results imply that modern-day plate tectonic processes featuring deep continental subduction occurred at least 1,830 million years ago. This study highlights that the global metamorphic rock record (particularly in older terrains) is skewed by overprinting and erosion
Fluctuation dynamo in a weakly collisional plasma
The turbulent amplification of cosmic magnetic fields depends upon the
material properties of the host plasma. In many hot, dilute astrophysical
systems, such as the intracluster medium (ICM) of galaxy clusters, the rarity
of particle--particle collisions allows departures from local thermodynamic
equilibrium. These departures exert anisotropic viscous stresses on the plasma
motions that inhibit their ability to stretch magnetic-field lines. We present
a numerical study of the fluctuation dynamo in a weakly collisional plasma
using magnetohydrodynamic (MHD) equations endowed with a field-parallel viscous
(Braginskii) stress. When the stress is limited to values consistent with a
pressure anisotropy regulated by firehose and mirror instabilities, the
Braginskii-MHD dynamo largely resembles its MHD counterpart. If instead the
parallel viscous stress is left unabated -- a situation relevant to recent
kinetic simulations of the fluctuation dynamo and to the early stages of the
dynamo in a magnetized ICM -- the dynamo changes its character, amplifying the
magnetic field while exhibiting many characteristics of the saturated state of
the large-Prandtl-number () MHD dynamo. We construct an
analytic model for the Braginskii-MHD dynamo in this regime, which successfully
matches magnetic-energy spectra. A prediction of this model, confirmed by our
simulations, is that a Braginskii-MHD plasma without pressure-anisotropy
limiters will not support a dynamo if the ratio of perpendicular and parallel
viscosities is too small. This ratio reflects the relative allowed rates of
field-line stretching and mixing, the latter of which promotes resistive
dissipation of the magnetic field. In all cases that do exhibit a dynamo, the
generated magnetic field is organized into folds that persist into the
saturated state and bias the chaotic flow to acquire a scale-dependent spectral
anisotropy.Comment: 62 pages, 25 figures, 1 table, accepted for publication to Journal of
Plasma Physic
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