Nanoindentation-induced dislocation emission at 5–7
nm displacements in ultra-thin films (12–33
nm) and nanocubes (40–60
nm) is used to examine deformation and plasticity models. Using the Tabor ...estimate, this displacement corresponds to a plastic strain of 3–5%. Load–displacement curves produced using nanoindentation show evidence of discretized, Burgers vector–length displacement steps, or excursions, which can be associated with individual dislocation emission events. Using these displacement steps and the residual plasticity present on unloading, theoretical hardening models are developed. Linear and parabolic hardening approaches are compared for ultra-thin films of nickel, cobalt, and Permalloy (Ni
80Fe
20), and also for silicon nanocubes. It is determined that the linear hardening model can predict the early trends of the experimental data while parabolic hardening may be more appropriate at later stages.
Apolipoprotein(a) apo(a) exhibits a genetic size polymorphism explaining about 40% of the variability in lipoprotein(a) Lp(a) concentration in Tyroleans. Lp(a) concentrations and apo(a) phenotypes ...were determined in 7 ethnic groups (Tyrolean, Icelandic, Hungarian, Malay, Chinese, Indian, Black Sudanese) and the effects of the apo(a) size polymorphism on Lp(a) levels were estimated in each group. Average Lp(a) concentrations were highly significantly different among these populations, with the Chinese (7.0 mg/dl) having the lowest and the Sudanese (46 mg/dl) the highest levels. Apo(a) phenotype and derived apo(a) allele frequencies were also significantly different among the populations. Apo(a) isoform effects on Lp(a) levels were not significantly different among populations. Lp(a) levels were however roughly twice as high in the same phenotypes in the Indians, and several times as high in the Sudanese, compared with Caucasians. The size variation of apo(a) explains from 0.77 (Malays) to only 0.19 (Sudanese) of the total variability in Lp(a) levels. Together these data show (I) that there is considerable heterogeneity of the Lp(a) polymorphism among populations, (II) that differences in apo(a) allele frequencies alone do not explain the differences in Lp(a) levels among populations and (III) that in some populations, e.g. Sudanese Blacks, Lp(a) levels are mainly determined by factors that are different from the apo(a) size polymorphism.
Application of uniform methods for measuring the apolipoprotein (apo) E polymorphism and plasma cholesterol levels in nine populations (Tyrolean, Sudanese, Indian, Chinese, Japanese, Hungarian, ...Icelandic, Finnish, and Malay) revealed significant heterogeneity among them in apo E type frequencies and mean cholesterol levels. The major apo E types in all populations were E3/2 (frequency range from 7.0% in Indians to 16.9% in Malays), E3/3 (frequency range from 39.8% in Sudanese to 72.1% in Japanese), and E3/4 (frequency range from 11.3% in Japanese to 35.9% in Sudanese). Mean cholesterol levels ranged from 144.2 mg/dl in the Sudanese to 228.5 mg/dl in the Icelandics. Two-way analysis of variance of the effect of population and apo E type on cholesterol levels showed no significantly interaction effect, indicating that the effects of apo E type on cholesterol levels do not differ significantly among the populations. The overall average excess for the epsilon 2 allele was -14.12 mg/dl (range -31.63 to -8.82 mg/dl); for the epsilon 3 allele, 0.04 mg/dl (range -1.87 to 1.58 mg/dl; and for the epsilon 4 allele, 8.14 mg/dl (range -1.71 to 13.31 mg/dl). Despite the apparent heterogeneity in these values, especially for the epsilon 4 allele, comparison of the average excesses by a method of repeated sampling with random permutations revealed no significant difference in effects among populations. These data indicate that a given apo E allele acts in a relatively uniform manner in different populations despite differences in genetic background and environmental factors.
A xenon gas purity monitor for EXO Dobi, A.; Hall, C.; Herrin, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
659, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of ...oxygen well below 1ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.
Polar sea ice is a critical component of Earth’s climate system. As a material, it is a multiscale composite of pure ice with temperature-dependent millimeter-scale brine inclusions, and ...centimeter-scale polycrystalline microstructure which is largely determined by how the ice was formed. The surface layer of the polar oceans can be viewed as a granular composite of ice floes in a sea water host, with floe sizes ranging from centimeters to tens of kilometers. A principal challenge in modeling sea ice and its role in climate is how to use information on smaller-scale structures to find the effective or homogenized properties on larger scales relevant to process studies and coarse-grained climate models. That is, how do you predict macroscopic behavior from microscopic laws, like in statistical mechanics and solid state physics? Also of great interest in climate science is the inverse problem of recovering parameters controlling small-scale processes from large-scale observations. Motivated by sea ice remote sensing, the analytic continuation method for obtaining rigorous bounds on the homogenized coefficients of two-phase composites was applied to the complex permittivity of sea ice, which is a Stieltjes function of the ratio of the permittivities of ice and brine. Integral representations for the effective parameters distill the complexities of the composite microgeometry into the spectral properties of a self-adjoint operator like the Hamiltonian in quantum physics. These techniques have been extended to polycrystalline materials, advection diffusion processes, and ocean waves in the sea ice cover. Here we discuss this powerful approach in homogenization, highlighting the spectral representations and resolvent structure of the fields that are shared by the two-component theory and its extensions. Spectral analysis of sea ice structures leads to a random matrix theory picture of percolation processes in composites, establishing parallels to Anderson localization and semiconductor physics and providing new insights into the physics of sea ice.
Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing ...this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.
The COVID-19 pandemic has triggered national recommendations encouraging people to work from home (WFH), but the possible impact of WFH on physical behaviors is unknown. This study aimed to determine ...the extent to which the 24-h allocation of time to different physical behaviors changes between days working at the office (WAO) and days WFH in office workers during the pandemic.
Data were collected on 27 office workers with full-time employment at a Swedish municipal division during the COVID-19 outbreak in May-July 2020. A thigh-worn accelerometer (Axivity) was used to assess physical behavior (sedentary, stand, move) during seven consecutive days. A diary was used to identify periods of work, leisure and sleep. 24-h compositions of sedentary, standing and moving behaviors during work and non-work time were examined using Compositional data analysis (CoDA), and differences between days WAO and days WFH were determined using repeated measures ANOVA.
Days WFH were associated with more time spent sleeping relative to awake, and the effect size was large (F = 7.4; p = 0.01; η
= 0.22). The increase (34 min) in sleep time during WFH occurred at the expense of a reduction in work and leisure time by 26 min and 7 min, respectively. Sedentary, standing and moving behaviors did not change markedly during days WFH compared to days WAO.
Days working from home during the COVID-19 pandemic in Sweden were associated with longer duration of sleep than days working at the office. This behavioral change may be beneficial to health.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Genetics of diabetic retinopathy Hanis, Craig L; Hallman, D
Current diabetes reports,
04/2006, Letnik:
6, Številka:
2
Journal Article
Recenzirano
Diabetes is rapidly increasing in frequency with an attendant toll of complications, including diabetic retinopathy. Although the underlying mechanisms remain elusive, genetic susceptibility is key ...to both types 1 and 2 diabetes and is increasingly recognized for its contribution to diabetic complications. In this article we review the evidence connecting genetic susceptibility to diabetic retinopathy. Elucidating the susceptibility genes and pathways should permit strategies to slow and reverse the troubling trends for the population, families, and individuals.
Thickness effects on the plasticity of gold films CORDILL, M. J; HALLMAN, D. M; MOODY, N. R ...
Metallurgical and materials transactions. A, Physical metallurgy and materials science,
09/2007, Letnik:
38, Številka:
13
Conference Proceeding, Journal Article
Recenzirano
An indentation size effect is a common occurrence during nanoindentation. Thin and thick gold films, deposited using sputter deposition and evaporation, illustrate this at depths less than 100 nm. ...The indentation size effect, however, has been observed to be independent of film thickness. It has been modeled using a combination of an indentation size effect model and a parabolic hardening model. At the near surface regime, the indentation size effect model is dominant, and at larger depths, the parabolic hardening model is dominant, taking into effect the film thickness. The described model, which is a combination of these two, fits the experimental data for the sputter-deposited films and the evaporated films. PUBLICATION ABSTRACT
PDF
