356 research outputs found
Burrow identification of some estuarine organisms
The available literature lacks adequate descriptions for the identification of the burrows of common South African estuarine benthic organisms. The burrows of three crab, two prawn, two bivalve and a polychaete species commonly encountered in southem Gape estuaries are described. Details on tidal levels, sediment types and associated macrophytes are included to assist in burrow identification
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A video life-world approach to consultation practice: The relevance of a socio-phenomenological approach
This article discusses the [development and] use of a video life-world schema to explore alternative orientations to the shared health consultation. It is anticipated that this schema can be used by practitioners and consumers alike to understand the dynamics of videoed health consultations, the role of the participants within it and the potential to consciously alter the outcome by altering behaviour during the process of interaction. The study examines health consultation participation and develops an interpretative method of analysis that includes image elicitation (via videos), phenomenology (to identify the components of the analytic framework), narrative (to depict the stories of interactions) and a reflexive mode (to develop shared meaning through a conceptual framework for analysis). The analytic framework is derived from a life-world conception of human mutual shared interaction which is presented here as a novel approach to understanding patient-centred care. The video materials used in this study were derived from consultations in a Walk-in Centre (WiC) in East London. The conceptual framework produced through the process of video analysis is comprised of different combinations of movement, knowledge and emotional conversations that are used to classify objective or engaged WiC health care interactions. The videoed interactions organise along an active or passive, facilitative or directive typical situation continuum illustrating different kinds of textual approaches to practice that are in tension or harmony. The schema demonstrates how practitioners and consumers interact to produce these outcomes and indicates the potential for both consumers and practitioners to be educated to develop practice dynamics that support patient-centred care and impact on health outcomes
The TAOS Project: Upper Bounds on the Population of Small KBOs and Tests of Models of Formation and Evolution of the Outer Solar System
We have analyzed the first 3.75 years of data from TAOS, the Taiwanese
American Occultation Survey. TAOS monitors bright stars to search for
occultations by Kuiper Belt Objects (KBOs). This dataset comprises 5e5
star-hours of multi-telescope photometric data taken at 4 or 5 Hz. No events
consistent with KBO occultations were found in this dataset. We compute the
number of events expected for the Kuiper Belt formation and evolution models of
Pan & Sari (2005), Kenyon & Bromley (2004), Benavidez & Campo Bagatin (2009),
and Fraser (2009). A comparison with the upper limits we derive from our data
constrains the parameter space of these models. This is the first detailed
comparison of models of the KBO size distribution with data from an occultation
survey. Our results suggest that the KBO population is comprised of objects
with low internal strength and that planetary migration played a role in the
shaping of the size distribution.Comment: 18 pages, 16 figures, Aj submitte
Kolmogorov-Sinai entropy in field line diffusion by anisotropic magnetic turbulence
The Kolmogorov-Sinai (KS) entropy in turbulent diffusion of magnetic field
lines is analyzed on the basis of a numerical simulation model and theoretical
investigations. In the parameter range of strongly anisotropic magnetic
turbulence the KS entropy is shown to deviate considerably from the earlier
predicted scaling relations [Rev. Mod. Phys. {\bf 64}, 961 (1992)]. In
particular, a slowing down logarithmic behavior versus the so-called Kubo
number (, where is the ratio of the rms magnetic fluctuation field to the magnetic field
strength, and and are the correlation lengths in respective
dimensions) is found instead of a power-law dependence. These discrepancies are
explained from general principles of Hamiltonian dynamics. We discuss the
implication of Hamiltonian properties in governing the paradigmatic
"percolation" transport, characterized by , associating it with the
concept of pseudochaos (random non-chaotic dynamics with zero Lyapunov
exponents). Applications of this study pertain to both fusion and astrophysical
plasma and by mathematical analogy to problems outside the plasma physics.
This research article is dedicated to the memory of Professor George M.
ZaslavskyComment: 15 pages, 2 figures. Accepted for publication on Plasma Physics and
Controlled Fusio
First Results From The Taiwanese-American Occultation Survey (TAOS)
Results from the first two years of data from the Taiwanese-American
Occultation Survey (TAOS) are presented. Stars have been monitored
photometrically at 4 Hz or 5 Hz to search for occultations by small (~3 km)
Kuiper Belt Objects (KBOs). No statistically significant events were found,
allowing us to present an upper bound to the size distribution of KBOs with
diameters 0.5 km < D < 28 km.Comment: 5 pages, 5 figure, accepted in Ap
A Search for sub-km KBOs with the Method of Serendipitous Stellar Occultations
The results of a search for sub-km Kuiper Belt Objects (KBOs) with the method
of serendipitous stellar occultations are reported. Photometric time series
were obtained on the 1.8m telescope at the Dominion Astrophysical Observatory
(DAO) in Victoria, BC, and were analyzed for the presence of occultation
events. Observations were performed at 40 Hz and included a total of 5.0
star-hours for target stars in the ecliptic open cluster M35 (beta=0.9deg), and
2.1 star-hours for control stars in the off-ecliptic open cluster M34
(beta=25.7deg). To evaluate the recovery fraction of the analysis method, and
thereby determine the limiting detectable size, artificial occultation events
were added to simulated time series (1/f scintillation-like power-spectra), and
to the real data. No viable candidate occultation events were detected. This
limits the cumulative surface density of KBOs to 3.5e10 deg^{-2} (95%
confidence) for KBOs brighter than m_R=35.3 (larger than ~860m in diameter,
assuming a geometric albedo of 0.04 and a distance of 40 AU). An evaluation of
TNO occultations reported in the literature suggests that they are unlikely to
be genuine, and an overall 95%-confidence upper limit on the surface density of
2.8e9 deg^{-2} is obtained for KBOs brighter than m_R=35 (larger than ~1 km in
diameter, assuming a geometric albedo of 0.04 and a distance of 40 AU) when all
existing surveys are combined.Comment: Accepted for publication in A
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Longitudinal trajectories of amyloid deposition, cortical thickness, and tau in Down syndrome: A deep-phenotyping case report.
Introduction:Comorbid Alzheimer disease pathologies are frequently found in people with Down syndrome (DS). We report a deep phenotyping study undertaken over 7 years in a participant with DS who was nondemented at baseline but developed dementia after 5 years. Methods:Throughout the course of the study, the participant was seen 4 times (2010, 2013, 2015, and 2017). Multimodal neuroimaging, including three serial scans of [11C]-PiB-PET, four structural magnetic resonance imagings, as well as a [18F]-AV1451 scan, was interpreted alongside detailed neuropsychological assessments over the study period. Results:Amyloid beta accumulation preceded the onset of dementia and cognitive decline, which in turn corresponded to the predominant deposition of tau in temporoparietal cortices. Discussion:Until now, data on the longitudinal trajectories of amyloid accumulation, tau pathology, and brain atrophy over multiple time points remain scarce in DS. This case report highlights the potential for deep phenotyping imaging to elucidate the substrates of cognitive decline in DS, although further longitudinal studies are necessary to clarify the relative contributions of both amyloid and tau
Multi-task learning with a natural metric for quantitative structure activity relationship learning
The goal of Quantitative Structure Activity Relationship (QSAR) Learning is to learn a function that, given the structure of a small molecule (a potential drug), outputs the predicted activity of the compound. We employed multi-task learning (MTL) to exploit commonalities in drug targets and assays. We used datasets containing curated records about the activity of speci c compounds on drug targets provided by ChEMBL. Totally, 1091 assays have been analysed. As a baseline, a single task learning approach that trains random forest to predict drug activity for each drug target individually was considered. We then carried out feature-based and instance-based MTL to predict drug activities. We introduced a natural metric of evolutionary distance between drug targets as a measure of tasks relatedness. Instance-based MTL signi cantly outperformed both, feature-based MTL and the base learner, on 741 drug targets out of 1091. Feature-based MTL won on 179 occasions and the base learner performed best on 171 drug targets. We conclude that MTL QSAR is improved by incorporating the evolutionary distance between targets. These results indicate that QSAR learning can be performed effectively, even if little data is available for speci c drug targets, by leveraging what is known about similar drug targets
The effects of insulin resistance on individual tissues: an application of a mathematical model of metabolism in humans
Whilst the human body expends energy constantly, the human diet consists of a mix of carbohydrates and fats delivered in a discontinuous manner. To deal with this sporadic supply of energy, there are transport, storage and utilisation mechanisms, for both carbohydrates and fats, around all tissues of the body. Insulin-resistant states such as type 2 diabetes and obesity are characterised by reduced efficiency of these mechanisms. Exactly how these insulin-resistant states develop, for example whether there is an order in which tissues become insulin resistant, is an active area of research with the hope of gaining a better overall understanding of insulin resistance.
In this paper we use a previously derived system of 12 first-or der coupled differential equations that describe the transport between, and storage in, different tissues of the human body. We briefly revisit the derivation of the model before parametrising the model to account for insulin resistance. We then solve the model numerically, separately simulating each individual tissue as insulin resistant, and discuss and compare these results, drawing three main conclusions. The implications of these results are in accordance with biological intuition. First, insulin resistance in a tissue creates a knock-on effect on the other tissues in the body, whereby they attempt to compensate for the reduced efficiency of the insulin resistant tissue. Secondly, insulin resistance causes a fatty liver; and the insulin resistance of tissues other than the liver can cause fat to accumulate in the liver. Finally, although insulin resistance in individual tissues can cause slightly reduced skeletal-muscle metabolic flexibility, it is when the whole body is insulin resistant that the biggest effect on skeletal muscle flexibility is see
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