Limitations for change detection in multiple Gabor targets

We investigate the limitations on the ability to detect when a target has changed, using Gabor targets as simple quantifiable stimuli. Using a partial report technique to equalise response variables, we show that the log of the Weber fraction for detecting a spatial frequency change is proportional to the log of the number of targets, with a set-size effect that is greater than that reported for visual search. This is not a simple perceptual limitation, because pre-cueing a single target out of four restores performance to the level found when only one target is present. It is argued that the primary limitation on performance is the division of attention across multiple targets, rather than decay within visual memory. However in a simplified change detection experiment without cueing, where only one target of the set changed, not only was the set size effect still larger, but it was greater at 2000 msec ISI than at 250 msec ISI, indicating a possible memory component. The steepness of the set size effects obtained suggests that even moderate complexity of a stimulus in terms of number of component objects can overload attentional processes, suggesting a possible low-level mechanism for change blindness

Probing the Density in the Galactic Center Region: Wind-Blown Bubbles and High-Energy Proton Constraints

Recent observations of the Galactic center in high-energy gamma-rays (above 0.1TeV) have opened up new ways to study this region, from understanding the emission source of these high-energy photons to constraining the environment in which they are formed. We present a revised theoretical density model of the inner 5pc surrounding Sgr A* based on the fact that the underlying structure of this region is dominated by the winds from the Wolf-Rayet stars orbiting Sgr A*. An ideal probe and application of this density structure is this high energy gamma-ray emission. We assume a proton-scattering model for the production of these gamma-rays and then determine first whether such a model is consistent with the observations and second whether we can use these observations to further constrain the density distribution in the Galactic center.Comment: 36 pages including 17 figures, submitted to ApJ, comments welcom

Non-destructive detection of machining-induced white layers in ferromagnetic alloys

Machining-induced white layers are an undesirable surface integrity feature which, due to their physical properties, can have a direct effect on the in-service performance of aero-engine components. Typically, destructive methods such as cross-sectional microscopy are used during inspection to identify white layers. This is costly, both in terms of parts sacrificed and time-consumed. A non-destructive evaluation method could speed-up inspection and allow all parts to be inspected before entering service as well as throughout the component life cycle. The present work covers the quantitative characterization of machining-induced white layers in super chrome molybdenum vanadium steel through destructive methods in addition to Barkhausen noise non-destructive testing of the same surfaces. White layers formed by machining with severely worn inserts were measured to be up to 50% harder than the bulk material, possess nano-scale grains and can have an associated compressive residual stress state of up to -1800 MPa. Barkhausen noise testing was used to show that surfaces with a white layer formed by SPD could be detected by measuring shifts in the peak frequency of the Barkhausen noise signal, caused by the compressive near-surface residual stress state associated with the formation of white layers of this type

COVID-19 pandemic impact on adolescent mental health: a reassessment accounting for development

Current prospective reports suggest a pandemic-related increase in adolescent mental health problems. We examine whether age-related change over 11-14 years accounts for this increase. Mothers and adolescents in a UK-based birth cohort (Wirral Child Health and Development Study; WCHADS; N = 737) reported on adolescent depression and behavioural problems pre-pandemic (December 2019-March 2020), mid-pandemic (June 2020-March 2021) and late pandemic (July 2021-March 2022). Analysis used repeated measures models for over-dispersed Poisson counts with an adolescent-specific intercept with age as a time-varying covariate. Maturational curves for girls, but not for boys, showed a significant increase in self-reported depression symptoms over ages 11-14 years. Behavioural problems decreased for both. After adjusting for age-related change, girls' depression increased by only 13% at mid-pandemic and returned to near pre-pandemic level at late pandemic (mid versus late - 12%), whereas boys' depression increased by 31% and remained elevated (mid versus late 1%). Age-adjusted behavioural problems increased for both (girls 40%, boys 41%) and worsened from mid- to late pandemic (girls 33%, boys 18%). Initial reports of a pandemic-related increase in depression in young adolescent girls could be explained by a natural maturational rise. In contrast, maturational decreases in boys' depression and both boys' and girls' behavioural problems may mask an effect of the pandemic

Trends of mechanical consequences and modeling of a fibrous membrane around femoral hip prostheses

In the present study, the effects of a fibrous membrane between cement and bone in a femoral total hip replacement were investigated. The study involved the problem of modeling this fibrous membrane in finite-element analyses, and its global consequences for the load-transfer mechanism and its resulting stress patterns. A finite-element model was developed, suitable to describe nonlinear contact conditions in combination with nonlinear material properties of the fibrous membrane. The fibrous tissue layer was described as a highly compliant material with little resistance against tension and shear. The analysis showed that the load transfer mechanism from stem to bone changes drastically when such a membrane is present. These effects are predominantly caused by tensile loosening and slip at the interface, and are enhanced by the nonlinear membrane characteristics.\ud \ud Using parametric analysis, it was shown that these effects on the load-transfer mechanism cannot be described satisfactorily with linear elastic models.\ud \ud Most importantly, the fibrous tissue interposition causes excessive stress concentrations in bone and cement, and relatively high relative displacements between these materials

Comparative Conflict Resolution Procedures in Taxation: An Analytic Comparative Study

Tax administrators in well developed countries rarely have either occasion or opportunity to compare experiences or exchange opinions regarding procedures and practices utilized in administering complicated tax laws. Moreover, there is little comparative literature on the subject. Even the tax institutes which are internationally oriented usually focus on substantive tax principles, not procedures and practices. Hopefully, therefore, administrators in highly developed countries will find useful this analytic comparison of practices and procedures through which six of their number resolve disputable income tax questions -administratively and judicially. Concern for tax administrators in well developed countries, however, was not the prime motivation for this study. The initial conception grew out of the belief that administrators in countries just now developing would find especially useful an analytic comparison of diverse functioning models which had evolved out of long experience. Since these now developing countries differ from one another on many counts, it was imperative that there be equally wide dissimilarity among the several experienced countries selected as models. Thus, the choice of Belgium, France, West Germany, Great Britain, the Netherlands, and the United States. These countries differ in their size and population, the complexity and precision of their tax statutes, the degree their legislative bodies provide additional guidance through pre-enactment materials, the assessment system used (self- versus non-self-assessment systems), the standards of construction to which their courts traditionally conform, the theoretical status assigned by each to the doctrine of precedent, and the types of persons available to handle tax disputes-both within and without the government. Consequently, it was possible to determine whether such basic differences were relevant or irrelevant when choosing, from among the alternative functioning models, the structural arrangement and practices most appropriate for each level involved in the conflict resolution process. Also, the analytic comparison contained in the first four chapters should enable any given country to determine the extent to which diverse parts of different wholes are adaptable to its situation. The third purpose of this study is a byproduct of the first two. Practitioners engaged in international tax practice may gain a useful insight into the conflict resolution process followed in each of the six countries covered.https://repository.law.umich.edu/michigan_legal_studies/1005/thumbnail.jp

Comparative Conflict Resolution Procedures in Taxation: An Analytic Comparative Study

Tax administrators in well developed countries rarely have either occasion or opportunity to compare experiences or exchange opinions regarding procedures and practices utilized in administering complicated tax laws. Moreover, there is little comparative literature on the subject. Even the tax institutes which are internationally oriented usually focus on substantive tax principles, not procedures and practices. Hopefully, therefore, administrators in highly developed countries will find useful this analytic comparison of practices and procedures through which six of their number resolve disputable income tax questions -administratively and judicially. Concern for tax administrators in well developed countries, however, was not the prime motivation for this study. The initial conception grew out of the belief that administrators in countries just now developing would find especially useful an analytic comparison of diverse functioning models which had evolved out of long experience. Since these now developing countries differ from one another on many counts, it was imperative that there be equally wide dissimilarity among the several experienced countries selected as models. Thus, the choice of Belgium, France, West Germany, Great Britain, the Netherlands, and the United States. These countries differ in their size and population, the complexity and precision of their tax statutes, the degree their legislative bodies provide additional guidance through pre-enactment materials, the assessment system used (self- versus non-self-assessment systems), the standards of construction to which their courts traditionally conform, the theoretical status assigned by each to the doctrine of precedent, and the types of persons available to handle tax disputes-both within and without the government. Consequently, it was possible to determine whether such basic differences were relevant or irrelevant when choosing, from among the alternative functioning models, the structural arrangement and practices most appropriate for each level involved in the conflict resolution process. Also, the analytic comparison contained in the first four chapters should enable any given country to determine the extent to which diverse parts of different wholes are adaptable to its situation. The third purpose of this study is a byproduct of the first two. Practitioners engaged in international tax practice may gain a useful insight into the conflict resolution process followed in each of the six countries covered.https://repository.law.umich.edu/michigan_legal_studies/1005/thumbnail.jp

Monte Carlo calculations for the ATLAS cavern background

A new application for simulating the ATLAS cavern background was developed. This was done using FLUGG, software that allows Geant4 geometry to be used within the FLUKA simulation framework. A Geant4 description of the ATLAS detector including its cavern was built from scratch for this application. In order to gain computing performance, our geometry is less detailed than that of GeoModel which is used in the full detector simulation, but good enough for the investigation of cavern background. Our geometry can also be used in a standalone Geant4 simulation. Thus it is possible to perform unbiased comparisons between Geant4 and FLUKA using the same complex geometry. We compared neutron and photon fluxes using the FLUKA-FLUGG application with the result of Geant4 simulations based on the QGSP_BERT and QGSP_BERT_HP physics lists. In all cases the same set of initial collision 4-vectors produced by the PHOJET event generator was used. The result from the QGSP_BERT_HP physics list, which uses the High Precision (HP) neutron model, is similar to the result of FLUKA-FLUGG and the differences in the fluxes between them are within 40% in most regions of the ATLAS cavern. The result from the QGSP_BERT physics list, which does not include the HP model, does not agree with either of the previous two results

Enteric helminths promote Salmonella co-infection by altering the intestinal metabolome

Intestinal helminth infections occur pre dominantly in regions where exposure to enteric bacterial pathogens is also common. Helminth infections inhibit host immunity against microbial pathogens, which has largely been attributed to the induction of regulatory or type 2 (Th2) immune responses. Here we demonstrate an additional three-way interaction in which helminth infection alters the metabolic environment of the host intestine to enhance bacterial pathogenicity. We show that an ongoing helminth infection increased colonization by Salmonella independently of T regulatory or Th2 cells. Instead, helminth infection altered the metabolic profile of the intestine, which directly enhanced bacterial expression of Salmonella pathogenicity island 1 (SPI-1) genes and increased intracellular invasion. These data reveal a novel mechanism by which a helminth-modified metabolome promotes susceptibility to bacterial co-infection