654 research outputs found
Self Calibration of Tomographic Weak Lensing for the Physics of Baryons to Constrain Dark Energy
Numerical studies indicate that uncertainties in the treatment of baryonic
physics can affect predictions for shear power spectra at a level that is
significant for forthcoming surveys such as DES, SNAP, and LSST.
Correspondingly, we show that baryonic effects can significantly bias dark
energy parameter measurements. Eliminating such biases by neglecting
information in multipoles beyond several hundred leads to weaker parameter
constraints by a factor of approximately 2 to 3 compared with using information
out to multipoles of several thousand. Fortunately, the same numerical studies
that explore the influence of baryons indicate that they primarily affect power
spectra by altering halo structure through the relation between halo mass and
mean effective halo concentration. We explore the ability of future weak
lensing surveys to constrain both the internal structures of halos and the
properties of the dark energy simultaneously as a first step toward self
calibrating for the physics of baryons. This greatly reduces parameter biases
and no parameter constraint is degraded by more than 40% in the case of LSST or
30% in the cases of SNAP or DES. Modest prior knowledge of the halo
concentration relation greatly improves even these forecasts. Additionally, we
find that these surveys can constrain effective halo concentrations near
m~10^14 Msun/h and z~0.2 to better than 10% with shear power spectra alone.
These results suggest that inferring dark energy parameters with measurements
of shear power spectra can be made robust to baryonic effects and may
simultaneously be competitive with other methods to inform models of galaxy
formation. (Abridged)Comment: 18 pages, 11 figures. Minor changes reflecting referee's comments.
Results and conclusions unchanged. Accepted for publication in Physical
Review
Test and Analysis Correlation of a Large-Scale, Orthogrid-Stiffened Metallic Cylinder without Weld Lands
The NASA Engineering Safety Center (NESC) Shell Buckling Knockdown Factor Project (SBKF) was established in 2007 by the NESC with the primary objective to develop analysis-based buckling design factors and guidelines for metallic and composite launch-vehicle structures.1 A secondary objective of the project is to advance technologies that have the potential to increase the structural efficiency of launch-vehicles. The SBKF Project has determined that weld-land stiffness discontinuities can significantly reduce the buckling load of a cylinder. In addition, the welding process can introduce localized geometric imperfections that can further exacerbate the inherent buckling imperfection sensitivity of the cylinder. Therefore, single-piece barrel fabrication technologies can improve structural efficiency by eliminating these weld-land issues. As part of this effort, SBKF partnered with the Advanced Materials and Processing Branch (AMPB) at NASA Langley Research Center (LaRC), the Mechanical and Fabrication Branch at NASA Marshall Space Flight Center (MSFC), and ATI Forged Products to design and fabricate an 8-ft-diameter orthogrid-stiffened seamless metallic cylinder. The cylinder was subjected to seven subcritical load sequences (load levels that are not intended to induce test article buckling or material failure) and one load sequence to failure. The purpose of this test effort was to demonstrate the potential benefits of building cylindrical structures with no weld lands using the flow-formed manufacturing process. This seamless barrel is the ninth 8-ft-diameter metallic barrel and the first single-piece metallic structure to be tested under this program
Genetic Structure of Yonahlossee Salamander Populations.
Plethodon yonahlossee is the largest eastern Plethodontid salamander. It has been classified as a species of greatest conservation need by the Tennessee Wildlife Resources Agency (TWRA). Found only in mountainous areas along the borders of Tennessee, North Carolina, and Virginia, populations of the yonahlossee are considered to be rare and local throughout their range. Genetic differentiation among populations of any species is usually attributable to long-standing, extrinsic barriers to gene flow. Because of their disjunct population structure and some observed morphological variation, genetic differentiation among yonahlossee populations is expected. A genetic structure study of yonahlossee was conducted to identify any genetically differentiated populations as conservation units. One mitochondrial DNA marker as well one nuclear DNA marker were amplified using polymerase chain reaction. After analysis, both markers show genetic differentiation suggesting geographic isolation. This information can be used by management agencies for the protection and conservation of the species
Wet and dry flexural high cycle fatigue behaviour of fully bioresorbable glass fibre composites: in-situ polymerisation versus laminate stacking
Fully bioresorbable phosphate based glass fibre reinforced polycaprolactone (PCL/PGF) composites are potentially excellent candidates to address current issues experienced with use of metal implants for hard tissue repair, such as stress shielding effects. It is therefore essential to investigate these materials under representative loading cases and to understand their fatigue behaviour (wet and dry) in order to predict their lifetime in service and their likely mechanisms of failure. This paper investigated the dry and wet flexural fatigue behaviour of PCL/PGF composites with 35% and 50% fibre volume fraction (Vf). Significantly longer flexural fatigue life (p < 0.0001) and superior fatigue damage resistance were observed for In-situ Polymerised (ISP) composites as compared to the Laminate Stacking (LS) composites in both dry and wet conditions, indicating that the ISP promoted considerably stronger interfacial bonding than the LS. Immersion in fluid (wet) during the flexural fatigue tests resulted in significant reduction (p < 0.0001) in the composites fatigue life, earlier onset of fatigue damage and faster damage propagation. Regardless of testing conditions, increasing fibre content led to shorter fatigue life for the PCL/PGF composites. Meanwhile, immersion in degradation media caused softening of both LS and ISP composites during the fatigue tests, which led to a more ductile failure mode. Among all the composites that were investigated, ISP35 (35% Vf) composites maintained at least 50% of their initial stiffness at the end of fatigue tests in both conditions, which is comparable to the flexural properties of human cortical bones. Consequently, ISP composites with 35% Vf maintained at least 50% of its flexural properties after the fatigue failure, which the mechanical retentions were well matched with the properties of human cortical bones
INTRODUCTION
Now is an opportune moment to rethink the legacy of sentimentalism so dominant in eighteenth-century Western European literature and culture. Contemporary interest in the “truth of emotions” and the affective basis of “lived experience,” whereby the individual’s somatic and subjective responses to stimuli are held to gainsay objectively verifiable data and recorded events, impels us to turn once more to the period in which arguments about mind-body relations, the hierarchy of passions, the function of reason as a regulator of human affairs and the irreducible force of feeling first entered the realm of debate. It was in the eighteenth century that the term “sentiment” became the broad-spreading umbrella under which clustered the cognates “feelings,” the “heart,” “sensibility,” “emotions,” the “affecting,” “tears,” “faints,” “being moved,” all words that carry within them a suggestion of some irresistible force acting on the rational individual. Henry Mackenzie’s “man of feeling” centres on one protagonist the age’s preoccupation with the idea that sentiments define not just us as people, but our moral compass and whole mode of being in the world. Sentimentality thus emerged as the motive force not only behind the plots of novels, the period’s defining mode of literary production, but the sum of our understanding of what it meant to be alive in the world. It is therefore timely for this special issue of Studia Philologia to re-examine the eighteenth-century’s formulations of sentimentality as we question once again the function of emotions in human subjectivity
Predicting prostate cancer treatment choices: The role of numeracy, time discounting, and risk attitudes
Prostate cancer is the most common cancer among males in the United States and there is lack of consensus as to whether active surveillance (AS) or radical prostatectomy (RP) is the best course of treatment. In this study we examined the role of three overlooked determinants of decision making about prostate cancer treatment in a hypothetical experiment—numeracy, time discounting, and risk taking in 279 men over age 50 without a prior prostate cancer diagnosis. Results showed that AS was the most frequently chosen option. Furthermore, numeracy and time discounting significantly predicted participants’ preference for AS, whereas a propensity to take risks was associated with a preference for RP. Such insights into the factors that affects cancer treatment preferences may improve tailored decision aids and help physicians be better poised to engage in shared decision-making to improve both patient-reported and clinical outcomes
Buckling Response of a Large-Scale, Seamless, Orthogrid-Stiffened Metallic Cylinder
Results from the buckling test of a compression-loaded 8-ft-diameter seamless (i.e., without manufacturing joints), orthogrid-stiffened metallic cylinder are presented. This test was used to assess the buckling response and imperfection sensitivity characteristics of a seamless cylinder. In addition, the test article and test served as a technology demonstration to show the application of the flow forming manufacturing process to build more efficient buckling-critical structures by eliminating the welded joints that are traditionally used in the manufacturing of large metallic barrels. Pretest predictions of the cylinder buckling response were obtained using a finite-element model that included measured geometric imperfections. The buckling load predicted using this model was 697,000 lb, and the test article buckled at 743,000 lb (6% higher). After the test, the model was revised to account for measured variations in skin and stiffener geometry, nonuniform loading, and material properties. The revised model predicted a buckling load of 754,000 lb, which is within 1.5% of the tested buckling load. In addition, it was determined that the load carrying capability of the seamless cylinder is approximately 28% greater than a corresponding cylinder with welded joints
Factor analysis and discriminant validity:a brief review of some practical issues
Growth in availability and ability of modern statistical software has resulted in greater numbers of research techniques being applied across the marketing discipline. However, with such advances come concerns that techniques may be misinterpreted by researchers. This issue is critical since misinterpretation could cause erroneous findings. This paper investigates some assumptions regarding: 1) the assessment of discriminant validity; and 2) what confirmatory factor analysis accomplishes. Examples that address these points are presented, and some procedural remedies are suggested based upon the literature. This paper is, therefore, primarily concerned with the development of measurement theory and practice. If advances in theory development are not based upon sound methodological practice, we as researchers could be basing our work upon shaky foundations
What does "good" look like? A three-country examination of marketing practice
Grounded in configuration theory, this study investigates the notion of co-alignment of business orientation, marketing assets and marketing capabilities, and their relationships to performance. Using these criteria, profiles of high performing businesses were derived and assessed against a three country sample of Brazil, China and the UK. Findings are consistent, statistically significant and invariant across the sample. They show that businesses with ideal profiles significantly outperform competitors in terms of market-based performance, customer satisfaction, and financial performance. Furthermore, profiles of top performing organizations are similar across countries with respect to their orientations, assets, and capabilities. Only customer-based assets, network capabilities, and customer and shareholder orientations were different. Implications and future research directions are subsequently addressed
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