25,375 research outputs found
Building Complex and Site Categorization Using Similarity to a Prototypical Site
This project presents an assessment tool for classifying building complexes using sitebased relationships as calculated from ArcGIS 9.2 using model builder and Python scripting. Anthropogenic features extracted from imagery often form the foundation of spatial databases. These data are in turn used to inform situational awareness for relief, law enforcement, and military agencies among many others. Buildings and the complexes they form are critical features within the landscape. The categorization of complexes requires an understanding of the relationships of the buildings within the site. In this study, building complexes in California were assessed for similarity to a prototypical California high school defined with a training set of known high schools and compared to a set of uncategorized sites. Eighty-eight percent of the high schools were correctly classified as being highly similar to the control data set
Numerical simulation of an ultrasonic vibratory cavitation device
Cavitation erosion prediction is one of the most important tasks in the ship propeller design. While predominantly qualitative methods are used such as paint tests or high speed video image analyses, there have been efforts to quantify such risks especially in the field of computational fluid dynamics (CFD).As an experimental quantitative method to assess erosion risk, the acoustic emission (AE) technique has been employed, for example, by Lloyds Register for more than a decade now to complement their borescopic cavitation observation at the ship scale. Boorsma and Fitzsimmons (2009) reported (see Fig. 1,) its correlation with borescope observed cavitation events appeared very positive and the location of cavitation impingement on the rudder (shown in the left image of Fig. 1) coincided with the estimated location by multiple synchronous measurements of AE at different locations. If it is possible to decipher how the AE connected with the pressure waves emitted from any given cavitation event, predicting the pressure waves we may be able to predict AE and eventually where and what intensity of cavitation events occur on any given propeller or ship structures. The transfer function can be useful for establishing quantitative correlations between CFD, full-scale trial data and with model test data.As the first step in being able to model this process and gain greater understanding in links between acoustic signal and type/location of cavitation, an open source Computational Fluid Dynamics programme openFOAM (version. 3.0.1) has been used to simulate ultrasonic cavitation on a sonotrode and hence to predict cavitation phenomena and pressure impact loads on a test specimen under the ultrasonic horn. The aim of the work is to evaluate the physical realism required and the limitations of current cavitation models
Sociodemographic Correlates of Sexlessness Among American Adults and Associations with Self-Reported Happiness Levels: Evidence from the U.S. General Social Survey
Although sexual activity is commonly believed to be a key component of emotional well-being, little is known about the factors associated with the absence of sexual activity or its associations with self-reported happiness. Using the U.S. General Social Survey–National Death Index 2008 dataset, a series of nationally representative surveys (1988–2002), this study analyzed the sociodemographic and lifestyle factors associated with past-year sexlessness and self-reported happiness among American adults (n = 17,744). After adjustment for marital status, there were no significant time trends evident in the proportion of American adults reporting past-year sexlessness. Among participants (age = 18–89 years), 15.2% of males and 26.7% of females reported past-year sexlessness while 8.7% of males and 17.5% of females reported no sex for 5 years or more. For both genders, past-year sexlessness was most strongly associated with older age and being currently non-married in the multivariable models. Among males, the multivariable analysis also showed that sexlessness was associated with providing less than 20% of the house-hold income (OR 2.27). In female participants, sexlessness was associated with very low income, poor health, lower financial satisfaction, absence of children, and having conservative sexual attitudes (OR 1.46–3.60). For both genders, Black race was associated with a much lower likelihood of sexlessness among currently non-married adults. The purported detrimental impact of sexlessness on self-reported happiness levels was not evident in this large, nationally representative study after adjusting for sociodemographic factors. Sexless Americans reported very similar happiness levels as their sexually active counterparts
Entanglement of a two-mode squeezed state in a Gaussian environment
Some non-classical properties such as squeezing, sub-Poissonian photon
statistics or oscillations in photon-number distributions may survive longer in
a phase-sensitive environment than in a phase-insensitive environment. We
examine if entanglement, which is an inter-mode non-classical feature, can also
survive longer in a phase-sensitive environment. Differently from the
single-mode case, we find that making the environment phase-sensitive does not
aid in prolonging entanglement.Comment: 5 pages, 1 figure, section IV has been modifie
Heat capacity study of BaFeAs: effects of annealing
Heat-capacity, X-ray diffraction, and resistivity measurements on a
high-quality BaFeAs sample show an evolution of the
magneto-structural transition with successive annealing periods. After a 30-day
anneal the resistivity in the (ab) plane decreases by more than an order of
magnitude, to 12 cm, with a residual resistance ratio 36; the
heat-capacity anomaly at the transition sharpens, to an overall width of less
than K, and shifts from 135.4 to 140.2 K. The heat-capacity anomaly in both the
as-grown sample and after the 30-day anneal shows a hysteresis of 0.15 K,
and is unchanged in a magnetic field H = 14 T. The X-ray and
heat-capacity data combined suggest that there is a first order jump in the
structural order parameter. The entropy of the transition is reported
The Phase Diagram of Compact QED Coupled to a Four-Fermi Interaction
Compact lattice Quantum Electrodynamics (QED) with four species of fermions
is simulated with massless quarks by using the QED scheme of adding a
four-fermi interaction to the action. Simulations directly in the chiral limit
of massless quarks are done with high statistics on , and lattices,
and the phase diagram, parameterized by the gauge and the four-fermi couplings,
is mapped out. The line of monopole condensation transitions is separate from
the line of chiral symmetry restoration. The simulation results indicate that
the monopole condensation transition is first order while the chiral transition
is second order. The challenges in determining the Universality class of the
chiral transition are discussed. If the scaling region for the chiral
transition is sufficiently wide, the simulations predict critical
indices far from mean field values. We discuss a speculative scenario in which
anti-screening provided by double-helix strands of monopole and anti-monopole
loops are the agent that balances the screening of fermion anti-fermion pairs
to produce an ultra-violet fixed point in the electric coupling.Comment: 29 pages, 8 figures and 2 table
Storm Surges in the Region of Western Alaska
Within the period of the historical record there have been several occurrences of extensive damage from storm-surge-related coastal flooding in the region of Nome, Alaska. The most recent of these events, although by no means the most destructive, occurred in association with the storm of 5–6 October 1992. Despite the small population of Nome (approximately 4000 people), total damage costs exceeded $6 million.
The research into the nature and causes of such flooding events has focused on this October 1992 case. The authors have, however, also examined a weaker, shorter-duration event that occurred on 20 August 1993 and, for contrast, a case in September 1993 where a sustained offshore wind transported water out of Norton Sound. Tide gauge data from Nome were used to quantitatively assess the associated changes in water level, and meteorological analyses were utilized to examine the associated synoptic-scale circulations and their evolution.
In addition, numerical modeling experiments were conducted using an extratropical storm surge model. (A version of this model is operational for the east coast of the United States.) Hindcasts of phase and amplitude for the October 1992 and September 1993 events agreed well with observations. Simulations of the shorter-duration August 1993 event were in poorer agreement with observations and indicate several possibilities for future improvement of the performance of the surge model: enhancement of the horizontal and temporal resolution of the model domain; more accurate input sea level pressure and wind data; and improvements to the surge model itself (e.g., inclusion of sea ice). Overall, however, results indicate that recent operational implementation of the model should be of significant benefit to coastal forecasters
Attenuation of bile acid-mediated FXR and PXR activation in patients with Crohn’s disease
Bile acids are endogenous ligands of nuclear receptors pregnane X (PXR) and farnesoid X (FXR). PXR and FXR regulate pathways that are impaired in inflammatory bowel disease (IBD). Decreases in PXR and FXR activity are documented in IBD; however reasons for this are unknown. We aimed to assess the effect of Crohn’s disease (CD) on the plasma bile acid composition in vivo and the resultant impact on PXR and FXR activation. A cross-sectional study evaluated the plasma concentrations of 12 bile acids in addition to 4β-hydroxycholesterol (4βOHC), an in vivo probe of the PXR target-gene cytochrome 3A4 (CYP3A4) and the FXR target-gene, fibroblast growth factor (FGF) 19 in individuals with (n = 74) and without (n = 71) CD. An in vitro model was used to assess the impact of CD-specific changes in the plasma bile acid composition on PXR and FXR activation. Decreases in glycochenodeoxycholic acid, taurocholic acid and lithocholic acid were seen in CD with increases in glycodeoxycholic acid and glycocholic acid relative to the total plasma bile acid profile. In vitro, increasing concentrations of bile acids applied in the same ratio as seen in the study cohorts resulted in decreased activation of both PXR and FXR in the CD model. In vivo, plasma 4βOHC (CD = 18.68 ng/ml ± 13.02 ng/ml, non-CD = 46.38 ng/ml ± 40.70 ng/ml, p ≤ 0.0001) and FGF19 (CD = 0.276 pg/L ± 0.189 pg/L, non-CD = 0.485 pg/L ± 0.42 pg/L, p = 0.0002) concentrations were lower in CD versus controls. Ultimately, CD-specific changes in the plasma bile acid composition lead to reduced activation of FXR and PXR target genes in vitro and in vivo
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