257,237 research outputs found
Does the inclusion of moderate amounts of red meat in the diet of exercising older women impact on faecal markers of bowel health, including faecal lactoferrin?
Background: High intakes of red meat may be associated with increased risk of colorectal cancer (CRC), however, to determine CRC risk, it is important to assess faecal changes related to protein and carbohydrate metabolism.Objective: To determine the influence of three weekly meals rich in red meat as opposed to a carbohydrate control diet on faecal markers which are involved in the aetiology of CRC.Design: Twenty post-menopausal women (aged 60-75) undertook, 3 times a week for 12 weeks, a 30 minute exercise session followed immediately by a cooked meal that was high in lean red meat, low in carbohydrate (n= 10) or low in lean red meat, high in carbohydrate (n=10). Dietary fibre intake and macronutrients were kept constant. At the beginning and end of the study, three-day faecal samples were collected and by-products of protein fermentation and carbohydrate metabolism, undigested fibre residues, and faecal output and colonic bacterial microbiota changes measured.Outcomes: No significant differences were observed in subjects on either diet when comparing faecal output, faecal pH, other faecal markers, nor faecal lactoferrin. There was a trend observed in changes in the population of colonic microbiota using FISH analysis. Bacteroides spp. and Prevotella spp. appeared to decrease in women consuming a high red meat diet compared with an increase in women consuming a high carbohydrate diet.Conclusions: In this pilot study the trend in colonic microbiota change is interesting and suggests that dietary influence of colonic microbiota, especially changes in Bacteroidetes, may be indicative of risk of gut damage and disease compared to other faecal markers.<br /
Liquid Booster Module (LBM) plume flowfield model
A complete definition of the LBM plume is important for many Shuttle design criteria. The exhaust plume shape has a significant effect on the vehicle base pressure. The LBM definition is also important to the Shuttle base heating, aerodynamics and the influence of the exhaust plume on the launch stand and environment. For these reasons a knowledge of the LBM plume characteristics is necessary. A definition of the sea level LBM plume as well as at several points along the Shuttle trajectory to LBM, burnout is presented
Planning Graph Heuristics for Belief Space Search
Some recent works in conditional planning have proposed reachability
heuristics to improve planner scalability, but many lack a formal description
of the properties of their distance estimates. To place previous work in
context and extend work on heuristics for conditional planning, we provide a
formal basis for distance estimates between belief states. We give a definition
for the distance between belief states that relies on aggregating underlying
state distance measures. We give several techniques to aggregate state
distances and their associated properties. Many existing heuristics exhibit a
subset of the properties, but in order to provide a standardized comparison we
present several generalizations of planning graph heuristics that are used in a
single planner. We compliment our belief state distance estimate framework by
also investigating efficient planning graph data structures that incorporate
BDDs to compute the most effective heuristics.
We developed two planners to serve as test-beds for our investigation. The
first, CAltAlt, is a conformant regression planner that uses A* search. The
second, POND, is a conditional progression planner that uses AO* search. We
show the relative effectiveness of our heuristic techniques within these
planners. We also compare the performance of these planners with several state
of the art approaches in conditional planning
Validation of the face-name pairs task in major depression: impaired recall but not recognition
Major depression can be associated with neurocognitive deficits which are believed in part to be related to medial temporal lobe pathology. The purpose of this study was to investigate this impairment using a hippocampal-dependent neuropsychological task. The face-name pairs task was used to assess associative memory functioning in 19 patients with major depression. When compared to age-sex-and-education matched controls, patients with depression showed impaired learning, delayed cued-recall, and delayed free-recall. However, they also showed preserved recognition of the verbal and nonverbal components of this task. Results indicate that the face-name pairs task is sensitive to neurocognitive deficits in major depression.Thisresearchwasfundedbya4-yearHealthResearch Board grant
Ion clustering in aqueous salt solutions near the liquid/vapor interface
Molecular dynamics simulations of aqueous NaCl, KCl, NaI, and KI solutions
are used to study the effects of salts on the properties of the liquid/vapor
interface. The simulations use the models which include both charge transfer
and polarization effects. Pairing and the formation of larger ion clusters
occurs both in the bulk and surface region, with a decreased tendency to form
larger clusters near the interface. An analysis of the roughness of the surface
reveals that the chloride salts, which have less tendency to be near the
surface, have a roughness that is less than pure water, while the iodide salts,
which have a greater surface affinity, have a larger roughness. This suggests
that ions away from the surface and ions near the surface affect the interface
in opposite ways.Comment: 10 pages, 5 figure
Discrete Logarithms in Generalized Jacobians
D\'ech\`ene has proposed generalized Jacobians as a source of groups for
public-key cryptosystems based on the hardness of the Discrete Logarithm
Problem (DLP). Her specific proposal gives rise to a group isomorphic to the
semidirect product of an elliptic curve and a multiplicative group of a finite
field. We explain why her proposal has no advantages over simply taking the
direct product of groups. We then argue that generalized Jacobians offer poorer
security and efficiency than standard Jacobians
Evidence of a saturated gravity-wave spectrum throughout the atmosphere
The view adapted here is that the dominant mesoscale motions are due to internal gravity waves and show that previous and new vertical wave number spectra of horizontal winds are consistent with the notion of a saturation limit on wave amplitudes. It is also proposed that, at any height, only those vertical wave numbers m less than m sub asterisk are at saturation amplitudes, where m sub asterisk is the vertical wave number of the dominant energy-containing scale. Wave numbers m less than m sub asterisk are unsaturated, but experience growth with height due to the decrease of atmospheric density. The result is a saturated spectrum of gravity waves with both m sub asterisk decreasing and wave energy increasing with height. This saturation theory is consistent with a variety of atmospheric spectral observations and provides a basis for the notion of a universal spectrum of atmospheric gravity waves
The Secondary Star in Cataclysmic Variables and Low Mass X-ray Binaries
We critically re-examine the available data on the spectral types, masses and
radii of the secondary stars in cataclysmic variables (CVs) and low-mass X-ray
binaries (LMXBs), using the new catalogue of Ritter & Kolb (1998) as a starting
point. We find there are 55 reliable spectral type determinations and only 14
reliable mass determinations of CV secondary stars (10 and 5, respectively, in
the case of LMXBs). We derive new spectral type-period, mass-radius,
mass-period and radius-period relations, and compare them with theoretical
predictions. We find that CV secondary stars with orbital periods shorter than
7-8 hours are, as a group, indistinguishable from main sequence stars in
detached binaries. We find it is not valid, however, to estimate the mass from
the spectral type of the secondary star in CVs or LMXBs. We find that LMXB
secondary stars show some evidence for evolution, with secondary stars which
are slightly too large for their mass. We show how the masses and radii of the
secondary stars in CVs can be used to test the validity of the disrupted
magnetic braking model of CV evolution, but we find that the currently
available data are not sufficiently accurate or numerous to allow such an
analysis. As well as considering secondary star masses, we also discuss the
masses of the white dwarfs in CVs, and find mean values of M_1 = 0.69+/-0.13
M_sun below the period gap, and M_1 = 0.80+/-0.22 M_sun above the period gap.Comment: 18 pages, 5 figure
A search for quasar protoclusters at z greater than 4
In the CDM and many other hierarchical scenarios for the origins of large scale structure, the existence of luminous quasars at very high redshifts (z greater than 3 or 4) is difficult to understand, unless such objects form at the very highest peaks of the density field. One then might expect a strong clustering of quasars at large redshifts. This is a generic prediction for practically any reasonable primordial density fluctuation spectrum. For CDM, Efstathiou & Rees (1988) predicted that quasars at z greater than 4 should be clustered as strongly as the bright galaxies at z approx. than 0. Cole & Kaiser (1989) suggest that z greater than 4 quasars might represent greater than or approximately = 4(sigma) peaks of the density field and thus, should be clustered more strongly than galaxies at z approximately = 0. We are performing the following experiment: a search for quasars, AGN, or other discrete objects, e.g., starforming galaxies, near known, z greater than 4 quasars. In other words, use the early quasars as markers of possible protoclusters. This is a fairly basic test of our understanding of the formation of galaxies, large-scale structure, and the origin of the first quasars themselves
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