22 research outputs found
Observational Consequences of Evolution of Primordial Fluctuations in Scalar-Tensor Cosmology
Evolution of primordial fluctuations in a Brans-Dicke type scalar-tensor
gravity theory is comprehensively investigated. The harmonic attractor model,
in which the scalar field has its harmonic effective potential in the Einstein
conformal frame and the theory relaxes toward Einstein gravity with time, is
considered. The evolution of adiabatic initial perturbations in flat SCDM
models is examined from the radiation-dominated epoch up to the present. We
discuss how the scalar-tensor gravity affects the evolution of metric and
matter perturbations, mainly focusing on the observational consequences, i.e.,
the matter power spectrum and the power spectrum of cosmic microwave background
temperature. We find that the early time deviation is characterized only by the
large static gravitational constant while the late time behavior is
qualitatively different from that in Einstein gravity because the time
variation of the gravitational constant and its fluctuation have non-negligible
effects. The attracting scalar-tensor gravity affects only small scale modes
due to its attracting nature, the degree of which is far beyond the
post-Newtonian deviation at the present epoch.Comment: 18 page
Uncovering the Genetic Architecture of Seed Weight and Size in Intermediate Wheatgrass through Linkage and Association Mapping
Intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & D.R. Dewey subsp. intermedium] is being developed as a new perennial grain crop that has a large allohexaploid genome similar to that of wheat (Triticum aestivum L.). Breeding for increased seed weight is one of the primary goals for improving grain yield of IWG. As a new crop, however, the genetic architecture of seed weight and size has not been characterized, and selective breeding of IWG may be more intricate than wheat because of its self-incompatible mating system and perennial growth habit. Here, seed weight, seed area size, seed width, and seed length were evaluated across multiple years, in a heterogeneous breeding population comprised of 1126 genets and two clonally replicated biparental populations comprised of 172 and 265 genets. Among 10,171 DNA markers discovered using genotyping-by-sequencing (GBS) in the breeding population, 4731 markers were present in a consensus genetic map previously constructed using seven full-sib populations. Thirty-three quantitative trait loci (QTL) associated with seed weight and size were identified using association mapping (AM), of which 23 were verified using linkage mapping in the biparental populations. About 37.6% of seed weight variation in the breeding population was explained by 15 QTL, 12 of which also contributed to either seed length or seed width. When performing either phenotypic selection or genomic selection for seed weight, we observed the frequency of favorable QTL alleles were increased to \u3e46%. Thus, by combining AM and genomic selection, we can effectively select the favorable QTL alleles for seed weight and size in IWG breeding populations
Constitutive Modeling of Magnesium Alloy Sheets
Magnesium alloy sheets have unique mechanical properties: high in-plane anisotropy/asymmetry of yield stress and hardening response, which have not been thoroughly studied. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of h.c.p metals and thus by deformation twinning. In this paper, the phenomenological continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were developed for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys. Also, characterization procedures of material parameters for the constitutive equations were presented and finally the correlation of simulation with measurements was performed to validate the proposed theory.110Nsciescopu
Equivalent drawbead model in finite element simulations
In 3D simulations of the deep drawing process the drawbead geometries are seldom included. Therefore equivalent drawbeads are used. In order to investigate the drawbead behaviour a 2D plane strain finite element model was used. For verification of this model experiments were performed. The analyses showed that not only the restraining force should be applied but also the strain changes. The effects of the restraining force and the strain change were implemented in an equivalent drawbead. The effect of using the equivalent drawbead is demonstrated with a few example
Toxicological assessments of Gulf War veterans
Concerns about unexplained illnesses among veterans of the 1991 Gulf War appeared soon after that conflict ended. Many environmental causes have been suggested, including possible exposure to depleted uranium munitions, vaccines and other drugs used to protect troops, deliberate or accidental exposure to chemical warfare agents and pesticides and smoke from oil-well fires. To help resolve these issues, US and UK governments have sought independent expert scientific advice from prestigious, independent scientific and public health experts, including the US National Academies of Science and the UK Royal Society and Medical Research Council. Their authoritative and independent scientific and medical reviews shed light on a wide range of Gulf War environmental hazards. However, they have added little to our understanding of Gulf War veterans' illnesses, because identified health effects have been previously well characterized, primarily in the occupational health literature. This effort has not identified any new health effects or unique syndromes associated with the evaluated environmental hazards. Nor do their findings provide an explanation for significant amounts of illnesses among veterans of the 1991 Gulf War. Nevertheless, these independent and highly credible scientific reviews have proven to be an effective means for evaluating potential health effects from deployment-related environmental hazards