896 research outputs found
Web crippling design of cold-formed duplex stainless steel lipped channel-sections with web openings under end-one-flange loading condition
Cold-formed stainless steel sections are becoming more widely used in the residential and commercial sectors due to their high corrosion resistance and high strength-to-weight ratio. However, their susceptibility to web crippling at points of concentrated loading is well-known to be an important design issue. In addition, web openings are also become popular, as they improve ease of installation of services. This paper presents the results of an investigation into the effect of web crippling on cold-formed duplex stainless steel lipped channel-sections, having such openings, under the end-one-flange (EOF) loading condition. 728 non-linear elasto-plastic finite element analyses are undertaken, with web openings located either centred above the bearing plate or offset to bearing plate. The effect of the size of the web opening, length of bearing plate and location of the web opening is considered. Strength reduction factor equations are proposed, that can be used to take into account such openings in design
Characterisation of the inshore fish assemblages of the Pilbara and Kimberley coasts
All of the objectives of this project have been met by documenting the following: the overall catch of the key commercial, recreational and charter boat fish species; the species composition and relative abundance of the inshore demersal finfish resource from the shoreline outward to a depth of 30 m along the inner continental shelf in north-western Australia; and the nursery areas of the major commercial and recreational fish species in the Pilbara and Kimberley regions
Stochastic String Motion Above and Below the World Sheet Horizon
We study the stochastic motion of a relativistic trailing string in black
hole AdS_5. The classical string solution develops a world-sheet horizon and we
determine the associated Hawking radiation spectrum. The emitted radiation
causes fluctuations on the string both above and below the world-sheet horizon.
In contrast to standard black hole physics, the fluctuations below the horizon
are causally connected with the boundary of AdS. We derive a bulk stochastic
equation of motion for the dual string and use the AdS/CFT correspondence to
determine the evolution a fast heavy quark in the strongly coupled
plasma. We find that the kinetic mass of the quark decreases by while the correlation time of world sheet
fluctuations increases by .Comment: 27 pages, 5 figures; v2 final version, small changes, references
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Gallavotti-Cohen theorem, Chaotic Hypothesis and the zero-noise limit
The Fluctuation Relation for a stationary state, kept at constant energy by a
deterministic thermostat - the Gallavotti-Cohen Theorem -- relies on the
ergodic properties of the system considered. We show that when perturbed by an
energy-conserving random noise, the relation follows trivially for any system
at finite noise amplitude. The time needed to achieve stationarity may stay
finite as the noise tends to zero, or it may diverge. In the former case the
Gallavotti-Cohen result is recovered, while in the latter case, the crossover
time may be computed from the action of `instanton' orbits that bridge
attractors and repellors. We suggest that the `Chaotic Hypothesis' of
Gallavotti can thus be reformulated as a matter of stochastic stability of the
measure in trajectory space. In this form this hypothesis may be directly
tested
PREDICTING THE SUMMER TEMPERATURE OF SMALL STREAMS IN SOUTHWESTERN WISCONSIN 1
One of the biggest challenges in managing cold water streams in the Midwest is understanding how stream temperature is controlled by the complex interactions among meteorologic processes, channel geometry, and ground water inflow. Inflow of cold ground water, shade provided by riparian vegetation, and channel width are the most important factors controlling summer stream temperatures. A simple screening model was used to quantitatively evaluate the importance of these factors and guide management decisions. The model uses an analytical solution to the heat transport equation to predict steady-state temperature throughout a stream reach. The model matches field data from four streams in southwestern Wisconsin quite well (typically within 1°C) and helps explain the observed warming and cooling trends along each stream reach. The distribution of ground water inflow throughout a stream reach has an important influence on stream temperature, and springs are especially effective at providing thermal refuge for fish. Although simple, this model provides insight into the importance of ground water and the impact different management strategies, such as planting trees to increase shade, may have on summer stream temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74032/1/j.1752-1688.2005.tb03714.x.pd
Interpreting Quantum Particles as Conceptual Entities
We elaborate an interpretation of quantum physics founded on the hypothesis
that quantum particles are conceptual entities playing the role of
communication vehicles between material entities composed of ordinary matter
which function as memory structures for these quantum particles. We show in
which way this new interpretation gives rise to a natural explanation for the
quantum effects of interference and entanglement by analyzing how interference
and entanglement emerge for the case of human concepts. We put forward a scheme
to derive a metric based on similarity as a predecessor for the structure of
'space, time, momentum, energy' and 'quantum particles interacting with
ordinary matter' underlying standard quantum physics, within the new
interpretation, and making use of aspects of traditional quantum axiomatics.
More specifically, we analyze how the effect of non-locality arises as a
consequence of the confrontation of such an emerging metric type of structure
and the remaining presence of the basic conceptual structure on the fundamental
level, with the potential of being revealed in specific situations.Comment: 19 pages, 1 figur
Maternal Pre-pregnancy Body Mass Index and Gestational Weight Gain in Relation to Autism Spectrum Disorder and other Developmental Disorders in Offspring
Most prior studies examining maternal pre-pregnancy body mass index (BMI) in relation to offspring autism spectrum disorders (ASD) have reported an association, though findings are not uniform and few have also examined gestational weight gain (GWG). Therefore, we examined both in the Study to Explore Early Development, a multi-site case–control study of children born in 2003–2006. Children identified from clinics, schools, and birth certificates were enrolled at ages 2–5 year and using standardized developmental evaluations, classified as: ASD, other developmental delays (DD), or population-based controls. Maternal height, weight, and GWG were self-reported during the telephone interview. Three primary weight risk factors were examined: (a) Pre-pregnancy BMI, classified as underweight to obese, (b) GWG continuous and categorized as quintiles, and (c) Institute of Medicine clinical weight-gain recommendations. Odds ratios adjusted (AOR) for sociodemographic and prenatal factors were calculated among term singletons, comparing the ASD (n = 540) or DD (n = 720) groups to the control group (n = 776). The AOR of ASD and maternal obesity was 1.37 (95%CI 0.98–1.92). Associations with higher GWG were stronger (Quintile5 vs. Quintile3 AOR = 1.58, 95%CI 1.08–2.31), and particularly so among overweight/obese women (AOR = 1.90, 95%CI 0.98–3.68). DD was associated with maternal overweight and obesity (obesity AOR = 1.48, 95%CI 1.08–2.02), but not with total GWG or clinical recommendations. High maternal BMI and GWG are risk factors for other pregnancy and child outcomes, and our results suggest they may also represent modifiable risk factors for neurodevelopmental outcomes. Autism Res 2019, 12: 316–327 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: In a large, national study, we found that children with autism were more likely than unaffected children to have mothers with higher weight gain during pregnancy; risk of autism may be even stronger if mothers were also overweight before pregnancy. Children with other developmental delays were more likely to have mothers who were overweight or obese before pregnancy, but not who gained more weight during pregnancy. Overweight and weight gain may represent factors that could be modified
Atomic X-ray Spectroscopy of Accreting Black Holes
Current astrophysical research suggests that the most persistently luminous
objects in the Universe are powered by the flow of matter through accretion
disks onto black holes. Accretion disk systems are observed to emit copious
radiation across the electromagnetic spectrum, each energy band providing
access to rather distinct regimes of physical conditions and geometric scale.
X-ray emission probes the innermost regions of the accretion disk, where
relativistic effects prevail. While this has been known for decades, it also
has been acknowledged that inferring physical conditions in the relativistic
regime from the behavior of the X-ray continuum is problematic and not
satisfactorily constraining. With the discovery in the 1990s of iron X-ray
lines bearing signatures of relativistic distortion came the hope that such
emission would more firmly constrain models of disk accretion near black holes,
as well as provide observational criteria by which to test general relativity
in the strong field limit. Here we provide an introduction to this phenomenon.
While the presentation is intended to be primarily tutorial in nature, we aim
also to acquaint the reader with trends in current research. To achieve these
ends, we present the basic applications of general relativity that pertain to
X-ray spectroscopic observations of black hole accretion disk systems, focusing
on the Schwarzschild and Kerr solutions to the Einstein field equations. To
this we add treatments of the fundamental concepts associated with the
theoretical and modeling aspects of accretion disks, as well as relevant topics
from observational and theoretical X-ray spectroscopy.Comment: 63 pages, 21 figures, Einstein Centennial Review Article, Canadian
Journal of Physics, in pres
The Broader Autism Phenotype in Mothers is Associated with Increased Discordance Between Maternal-Reported and Clinician-Observed Instruments that Measure Child Autism Spectrum Disorder
Autism spectrum disorder (ASD) diagnosis relies on parent-reported and clinician-observed instruments. Sometimes, results between these instruments disagree. The broader autism phenotype (BAP) in parent-reporters may be associated with discordance. Study to Explore Early Development data (N = 712) were used to address whether mothers with BAP and children with ASD or non-ASD developmental disabilities were more likely than mothers without BAP to ‘over-’ or ‘under-report’ child ASD on ASD screeners or interviews compared with clinician observation or overall impression. Maternal BAP was associated with a child meeting thresholds on a maternal-reported screener or maternal interview when clinician ASD instruments or impressions did not (risk ratios: 1.30 to 2.85). Evidence suggests acknowledging and accounting for reporting discordances may be important when diagnosing ASD
Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector
The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
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