Numerical study of the effects of crack location on creep crack growth in weldment

A numerical study on the effects of crack location on creep crack growth, in a P91 weldment, was carried out using a finite element package (ABAQUS). Models of compact tension specimens were used. The obtained results showed that, the creep crack growth in the weld metal are much higher than that in the parent metal. However, the creep crack growth in cross-weld specimens is controlled by the properties of the weakest component of the weld. This highlights the importance of the heat affected zone (HAZ) as the weakest region of the weldment. Effects of the width of HAZ are presented, too

Social Spending, Poverty, and Immigration: A Systematic Analysis of Welfare State Effectiveness and Nativity in 24 Upper- and Middle-Income Democracies

Previous research has highlighted the disadvantaged position immigrants often face in the economy, particularly when it comes to labor market outcomes such as employment or earnings. Extending this literature, the present study evaluates the economic exclusion of immigrants, conceptualized not as labor market outcomes but as relative poverty. This study examines the relationship between welfare generosity and immigrant poverty across rich western democracies and compares this relationship with that of native poverty. One publicly held belief is that immigrants disproportionately benefit from welfare generosity, while the literature on welfare chauvinism suggests greater social spending may not necessarily benefit immigrants. Furthermore, the effects may vary by spending and immigrant type. This study uses the Luxembourg Income Study to consider differences in the effects of welfare generosity on the odds an immigrant or native household is poor, how this effect varies by the type of spending, and how the effect changes depending on factors such as region of origin or citizenship status. Using four waves of data circa 2004 to 2014 across 24 upper- and middle-income democracies, the results show some support for welfare chauvinism and advantages to being an intra-EU immigrant and citizen immigrant

Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma

Understanding the agglomeration of dust particles in complex plasmas requires a knowledge of the basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold coated mono-disperse spherical melamine-formaldehyde monomers in a radio-frequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining 3D structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.Comment: 6 pages, 7 figure

Exploring the impact of Covid-19 on the care and quality of life of people with dementia and their carers: A scoping review

This article reports on findings of a scoping review aimed to map the published literature concerning the impact of Covid-19 on the care and quality of life of people living with dementia and their carers. Twenty-nine articles were included in the review. Three overarching themes were identified: (1) Impact on people with dementia – unmet and increased care needs; (2) Impact on carers – increased stress and burden and (3) Impact according to demographics. Overall, findings show that Covid-19 has led to a reduction in support from health and social services and to a move towards technology-based support. Furthermore, Covid-19 has had a negative impact on the care and quality of life of people living with dementia and their carers, and that this impact was influenced by the severity of dementia

Design and behavior of ribless solar reflectors

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.Microfiche copy available in Archives and Barker.Vita.Includes bibliographical references.by Roderick A. Hyde.Ph.D

Detection of human influence on a new, validated 1500-Year temperature reconstruction

Climate records over the last millennium place the twentieth-century warming in a longer historical context. Reconstructions of millennial temperatures show a wide range of variability, raising questions about the reliability of currently available reconstruction techniques and the uniqueness of late-twentieth-century warming. A calibration method is suggested that avoids the loss of low-frequency variance. A new reconstruction using this method shows substantial variability over the last 1500 yr. This record is consistent with independent temperature change estimates from borehole geothermal records, compared over the same spatial and temporal domain. The record is also broadly consistent with other recent reconstructions that attempt to fully recover low-frequency climate variability in their central estimate. High variability in reconstructions does not hamper the detection of greenhouse gas-induced climate change, since a substantial fraction of the variance in these reconstructions from the beginning of the analysis in the late thirteenth century to the end of the records can be attributed to external forcing. Results from a detection and attribution analysis show that greenhouse warming is detectable in all analyzed high-variance reconstructions (with the possible exception of one ending in 1925), and that about a third of the warming in the first half of the twentieth century can be attributed to anthropogenic greenhouse gas emissions. The estimated magnitude of the anthropogenic signal is consistent with most of the warming in the second half of the twentieth century being anthropogenic

Charging and coagulation of dust in protoplanetary plasma environments

Combining a particle-particle, particle-cluster and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in various plasma environments relevant for proto-planetary disks have been investigated. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, leading to greater sizes and masses as compared to neutral aggregates, for the same number of monomers in the aggregate. In addition, aggregates coagulating in a Lorentzian plasma (containing a larger fraction of high-energy plasma particles) are more massive and larger than aggregates coagulating in a Maxwellian plasma, for the same plasma densities and characteristic temperature. Comparisons of the grain structure, utilizing the compactness factor, {\phi}{\sigma}, demonstrate that a Lorentzian plasma environment results in fluffier aggregates, with small {\phi}{\sigma}, which exhibit a narrow compactness factor distribution. Neutral aggregates are more compact, with larger {\phi}{\sigma}, and exhibit a larger variation in fluffiness. Measurement of the compactness factor of large populations of aggregates is shown to provide information on the disk parameters that were present during aggregation

Exploring the impact of Covid-19 on the care and quality of life of people with dementia and their carers: A scoping review

This article reports on findings of a scoping review aimed to map the published literature concerning the impact of Covid-19 on the care and quality of life of people living with dementia and their carers. Twenty-nine articles were included in the review. Three overarching themes were identified: (1) Impact on people with dementia – unmet and increased care needs; (2) Impact on carers – increased stress and burden and (3) Impact according to demographics. Overall, findings show that Covid-19 has led to a reduction in support from health and social services and to a move towards technology-based support. Furthermore, Covid-19 has had a negative impact on the care and quality of life of people living with dementia and their carers, and that this impact was influenced by the severity of dementia

Donor tricuspid annuloplasty during orthotopic heart transplantation: Long-term results of a prospective controlled study

Background: Development of tricuspid regurgitation after orthotopic heart transplantation can cause heart failure along with renal and hepatic impairment and portends a poor prognosis. If tricuspid regurgitation causes significant symptoms, tricuspid valve repair or replacement is often required. This study was designed to study the effects of prophylactic tricuspid valve annuloplasty (TVA) during orthotopic heart transplantation on long-term survival, renal function, and amount of tricuspid regurgitation. Methods: Between April 1997 and March 1998, 60 patients (aged 18 to 70 years; 22 female) randomly received either standard bicaval orthotopic heart transplantation (group STD; n = 30) or bicaval orthotopic heart transplantation with DeVega TVA (group TVA; n = 30). Tricuspid valve annuloplasty was performed on the donor heart before implantation using pledgeted 2-0 polypropylene and sized to an annulus of 29 mm. Echocardiographic measurements, laboratory values, and hemodynamics were obtained prospectively and reviewed by an independent data analyst. Results: Follow-up of patients as of December 2003 was complete. Although there was a perioperative mortality advantage in group TVA, there was no difference between groups in long-term survival. At the end of the study, however, there was a statistical difference (group STD versus group TVA, p \u3c 0.05) with regard to cardiac mortality (7 of 30 versus 3 of 30), average amount of tricuspid regurgitation (1.5 ± 1.3 versus 0.5 ± 0.4), percentage of patients with 2+ or greater tricuspid regurgitation (34% versus 0%), serum creatinine (2.9 ± 2.0 versus 1.8 ± 0.7), and difference in serum creatinine over baseline (2.0 ± 2.1 versus 0.7 ± 0.8). Conclusions: Prophylactic DeVega TVA of the donor heart is durable and decreases the incidence of cardiac-related mortality and tricuspid regurgitation after orthotopic heart transplantation. In addition, there is improved protection of renal function. Considering the ease and safety of TVA and its advantages, it should be performed as a routine adjunct to orthotopic heart transplantation

Emission lines in early-type galaxies: active nuclei or stars?

We selected 27244 nearby, red, giant early-type galaxies (RGEs) from the Sloan Digital Sky Survey (SDSS). In a large fraction (53%) of their spectra the [O III] emission line is detected, with an equivalent width (EW) distribution strongly clustered around ~0.75 A. The vast majority of those RGEs for which it is possible to derive emission line ratios (amounting to about half of the sample) show values characteristic of LINERs. The close connection between emission lines and stellar continuum points to stellar processes as the most likely source of the bulk of the ionizing photons in RGEs, rather than active nuclei. In particular, the observed EW and optical line ratios are consistent with the predictions of models in which the photoionization comes from to hot evolved stars. Shocks driven by supernovae or stellar ejecta might also contribute to the ionization budget. A minority, ~4%, of the galaxies show emission lines with an equivalent that is width a factor of ~2 greater than the sample median. Only among them are Seyfert-like spectra found. Furthermore, 40% of this subgroup have a radio counterpart, compared to ~6% of the rest of the sample. These characteristics argue in favor of an AGN origin for their emission lines. Emission lines diagnostic diagrams do not reveal a distinction between the AGN subset and the other members of the sample, and consequently they are not a useful tool for establishing the dominant source of the ionizing photons, which is better predicted by the EW of the emission lines.Comment: Accepted for publication in A&