9,732 research outputs found
Performance, emissions, and physical characteristics of a rotating combustion aircraft engine, supplement A
Testing was conducted using the basic RC2-75 engine, to which several modifications were incorporated which were designed to reduce the hydrocarbon emissions and reduce the specific fuel consumption. The modifications included close-in surface gap spark plugs, increased compression ratio rotors, and provisions for utilizing either side or peripheral intake ports, or a combination of the two if required. The proposed EPA emissions requirements were met using the normal peripheral porting. The specific fuel economy demonstrated for the modified RC2-75 was 283 g/kW-hr at 75% power and 101 brake mean effective pressure (BMEP) and 272.5 g/kW-hr at 75% power and 111 BMEP. The latter would result from rating the engine for takeoff at 285 hp and 5500 rpm, instead of 6000 rpm
Genome-Wide Association with Diabetes-Related Traits in the Framingham Heart Study
BACKGROUND: Susceptibility to type 2 diabetes may be conferred by genetic variants having modest effects on risk. Genome-wide fixed marker arrays offer a novel approach to detect these variants. METHODS: We used the Affymetrix 100K SNP array in 1,087 Framingham Offspring Study family members to examine genetic associations with three diabetes-related quantitative glucose traits (fasting plasma glucose (FPG), hemoglobin A1c, 28-yr time-averaged FPG (tFPG)), three insulin traits (fasting insulin, HOMA-insulin resistance, and 0â120 min insulin sensitivity index); and with risk for diabetes. We used additive generalized estimating equations (GEE) and family-based association test (FBAT) models to test associations of SNP genotypes with sex-age-age2-adjusted residual trait values, and Cox survival models to test incident diabetes. RESULTS: We found 415 SNPs associated (at p 1%) 100K SNPs in LD (r2 > 0.05) with ABCC8 A1369S (rs757110), KCNJ11 E23K (rs5219), or SNPs in CAPN10 or HNFa. PPARG P12A (rs1801282) was not significantly associated with diabetes or related traits. CONCLUSION: Framingham 100K SNP data is a resource for association tests of known and novel genes with diabetes and related traits posted at. Framingham 100K data replicate the TCF7L2 association with diabetes.National Heart, Lung, and Blood Institute's Framingham Heart Study (N01-HC-25195); National Institutes of Health National Center for Research Resources Shared Instrumentation grant (1S10RR163736-01A1); National Center for Research Resources General Clinical Research Center (M01-RR-01066); American Diabetes Association Career Developement Award; GlaxoSmithKline; Merck; Lilly; National Institutes of Health Research Career Award (K23 DK659678-03
Scaling and Universality in the Counterion-Condensation Transition at Charged Cylinders
We address the critical and universal aspects of counterion-condensation
transition at a single charged cylinder in both two and three spatial
dimensions using numerical and analytical methods. By introducing a novel
Monte-Carlo sampling method in logarithmic radial scale, we are able to
numerically simulate the critical limit of infinite system size (corresponding
to infinite-dilution limit) within tractable equilibration times. The critical
exponents are determined for the inverse moments of the counterionic density
profile (which play the role of the order parameters and represent the inverse
localization length of counterions) both within mean-field theory and within
Monte-Carlo simulations. In three dimensions (3D), correlation effects
(neglected within mean-field theory) lead to an excessive accumulation of
counterions near the charged cylinder below the critical temperature
(condensation phase), while surprisingly, the critical region exhibits
universal critical exponents in accord with the mean-field theory. In two
dimensions (2D), we demonstrate, using both numerical and analytical
approaches, that the mean-field theory becomes exact at all temperatures
(Manning parameters), when number of counterions tends to infinity. For finite
particle number, however, the 2D problem displays a series of peculiar singular
points (with diverging heat capacity), which reflect successive de-localization
events of individual counterions from the central cylinder. In both 2D and 3D,
the heat capacity shows a universal jump at the critical point, and the energy
develops a pronounced peak. The asymptotic behavior of the energy peak location
is used to locate the critical temperature, which is also found to be universal
and in accordance with the mean-field prediction.Comment: 31 pages, 16 figure
The Search for Intergalactic Hydrogen Clouds in Voids
I present the results of a search for intergalactic hydrogen clouds in voids.
Clouds are detected by their HI LyA absorption lines in the HST spectra of
low-redshift AGN. The parameter with which the environments of clouds are
characterized is the tidal field, which places a lower limit on the cloud
mass-density which is dynamically stable against disruption. Galaxy redshift
catalogs are used to sum the tidal fields along the lines of sight, sorting
clouds according to tidal field upper, or lower limits. The analytical
methodology employed is designed to detect gas clouds whose expansion following
reionization is restrained by dark matter perturbations. End-products are the
cloud equivalent width distribution functions (EWDF) of catalogs formed by
sorting clouds according to various tidal field upper, or lower limits.
Cumulative EWDFs are steep in voids (S ~ -1.5 \pm 0.2), but flatter in high
tidal field zones (S ~ -0.5 \pm 0.1). Most probable cloud Doppler parameters
are ~30 km/s in voids and ~60 km/s in proximity to galaxies. In voids, the
cumulative line density at low EW (~ 15 mA) is ~ 500 per unit redshift. The
void filling factor is found to be 0.87 <= f_v <= 0.94. The void EWDF is
remarkably uniform over this volume, with a possible tendency for more massive
clouds to be in void centers. The size and nature of the void cloud population
suggested by this study is completely unanticipated by the results of published
3-D simulations, which predict that most clouds are in filamentary structures
around galaxy concentrations, and that very few observable absorbers would lie
in voids. Strategies for modeling this population are briefly discussed.Comment: 21 pages, 19 figures, apjemulate style, to appear in ApJ vol. 57
Dietary supplement use and nosebleeds in hereditary haemorrhagic telangiectasia - an observational study.
Understanding potential provocations of haemorrhage is important in a range of clinical settings, and particularly for people with abnormal vasculature. Patients with hereditary haemorrhagic telangiectasia (HHT) can report haemorrhage from nasal telangiectasia in real time, and suggested dietary factors may precipitate nosebleeds. To examine further, nosebleed severity, dietary supplement use, and blood indices were evaluated in an unselected group of 50 HHT patients recruited from a specialist UK service. Using the validated Epistaxis Severity Score, nosebleed severity ranged from 0 to 9.1 out of 10 (median 3.9). Using a Food Frequency Questionnaire, 24/50 (48%) participants reported use of dietary supplements in the previous year. A third (18/50; 36%) had used self prescribed, non-iron containing dietary supplements, ingesting between 1 and 3 different supplements each day. Eight (16%) used fish oils. Despite having more severe epistaxis (p = 0.012), the 12 iron supplement users had higher serum iron concentrations, and were able to maintain their red blood cell indices. In contrast, there was no evident benefit for the participants using non iron supplements. Furthermore, platelet counts and serum fibrinogen tended to be lower in fish oil/supplement users, and one fish oil user demonstrated reduced in vitro platelet aggregation. In conclusion, in this small study, a third of HHT patients used non-iron dietary supplements, and one in six ingested fish oils, unaware of their known anti-platelet activity. The scale of use, and potential of these "natural health supplements" to exacerbate nosebleeds has not been appreciated previously in HHT
On Hilberg's Law and Its Links with Guiraud's Law
Hilberg (1990) supposed that finite-order excess entropy of a random human
text is proportional to the square root of the text length. Assuming that
Hilberg's hypothesis is true, we derive Guiraud's law, which states that the
number of word types in a text is greater than proportional to the square root
of the text length. Our derivation is based on some mathematical conjecture in
coding theory and on several experiments suggesting that words can be defined
approximately as the nonterminals of the shortest context-free grammar for the
text. Such operational definition of words can be applied even to texts
deprived of spaces, which do not allow for Mandelbrot's ``intermittent
silence'' explanation of Zipf's and Guiraud's laws. In contrast to
Mandelbrot's, our model assumes some probabilistic long-memory effects in human
narration and might be capable of explaining Menzerath's law.Comment: To appear in Journal of Quantitative Linguistic
On the importance of hydrodynamic interactions in polyelectrolyte electrophoresis
The effect of hydrodynamic interactions on the free-solution electrophoresis
of polyelectrolytes is investigated with coarse-grained molecular dynamics
simulations. By comparing the results to simulations with switched-off
hydrodynamic interactions, we demonstrate their importance in modelling the
experimentally observed behaviour. In order to quantify the hydrodynamic
interactions between the polyelectrolyte and the solution, we present a novel
way to estimate its effective charge. We obtain an effective friction that is
different from the hydrodynamic friction obtained from diffusion measurements.
This effective friction is used to explain the constant electrophoretic
mobility for longer chains. To further emphasize the importance of hydrodynamic
interactions, we apply the model to end-labeled free-solution electrophoresis.Comment: 15 pages, 7 figures; accepted for publication in J. Phys.: Condens.
Matte
Broadcasting graphic war violence: the moral face of Channel 4
Drawing on empirical data from Channel 4 (C4) regarding the broadcasting of violent war imagery, and positioned within Goffmanâs notion of the interaction ritual (1959, 1967), this article investigates how C4 negotiate potentially competing commercial, regulatory and moral requirements through processes of discretionary decision-making. Throughout, the article considers the extent to which these negotiations are presented through a series of âimaginingsâ â of C4 and its audience â which serve to simultaneously guide and legitimate the decisions made. This manifestation of imaginings moves us beyond more blanket explanations of âbrandingâ and instead allows us to see the final programmes as the end product of a series of complex negotiations and interactions between C4 and those multiple external parties significant to the workings of their organization. The insights gleaned from this case study are important beyond the workings of C4 because they help elucidate how all institutions and organizations may view, organize and justify their practices (to both themselves and others) within the perceived constraints in which they operate
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