Individual Differences in Holistic Processing Predict the Own-Race Advantage in Recognition Memory

Individuals are consistently better at recognizing own-race faces compared to other-race faces (other-race effect, ORE). One popular hypothesis is that this recognition memory ORE is caused by differential own- and other-race holistic processing, the simultaneous integration of part and configural face information into a coherent whole. Holistic processing may create a more rich, detailed memory representation of own-race faces compared to other-race faces. Despite several studies showing that own-race faces are processed more holistically than other-race faces, studies have yet to link the holistic processing ORE and the recognition memory ORE. In the current study, we sought to use a more valid method of analyzing individual differences in holistic processing by using regression to statistically remove the influence of the control condition (part trials in the part-whole task) from the condition of interest (whole trials in the part-whole task). We also employed regression to separately examine the two components of the ORE: own-race advantage (regressing other-race from own-race performance) and other-race decrement (regressing own-race from other-race performance). First, we demonstrated that own-race faces were processed more holistically than other-race faces, particularly the eye region. Notably, using regression, we showed a significant association between the own-race advantage in recognition memory and the own-race advantage in holistic processing and that these associations were weaker when examining the other-race decrement. We also demonstrated that performance on own- and other-race faces across all of our tasks was highly correlated, suggesting that the differences we found between own- and other-race faces are quantitative rather than qualitative. Together, this suggests that own- and other-race faces recruit largely similar mechanisms, that own-race faces more thoroughly engage holistic processing, and that this greater engagement of holistic processing is significantly associated with the own-race advantage in recognition memory.Psycholog

The Dirichlet Markov Ensemble

We equip the polytope of $n\times n$ Markov matrices with the normalized trace of the Lebesgue measure of $\mathbb{R}^{n^2}$. This probability space provides random Markov matrices, with i.i.d. rows following the Dirichlet distribution of mean $(1/n,...,1/n)$. We show that if \bM is such a random matrix, then the empirical distribution built from the singular values of\sqrt{n} \bM tends as $n\to\infty$ to a Wigner quarter--circle distribution. Some computer simulations reveal striking asymptotic spectral properties of such random matrices, still waiting for a rigorous mathematical analysis. In particular, we believe that with probability one, the empirical distribution of the complex spectrum of \sqrt{n} \bM tends as $n\to\infty$ to the uniform distribution on the unit disc of the complex plane, and that moreover, the spectral gap of \bM is of order $1-1/\sqrt{n}$ when $n$ is large.Comment: Improved version. Accepted for publication in JMV

Immunological Response to Highly Active Antiretroviral Therapy in Children with Clinically Stable HIV-1 Infection

We studied changes in 60 immunological parameters after the administration of highly active antiretroviral therapy (HAART) in 192 clinically stable antiretroviral drug–experienced HIV-1–infected children 4 months– 17 years old. The studied immunological parameters included standard lymphocyte subsets and lymphocyte surface markers of maturation and activation. The most significant changes during the 48-week study period were seen for CD8+, CD8+ CD62L+ CD45RA+, CD8+ CD38+ HLA-DR+, and CD4+ T cell percentages (P \u3c .0001 for all parameters). These changes suggest that significant decreases in the expression of activation markers and increases in the expression of naive markers in the CD8+ T cell population may be related to better virologic control in these HIV-1–infected children, who had relatively stable immune function at the initiation of HAART. At week 44 of HAART, the major immunological parameters in these HIV-1–infected children moved from baseline values to about halfway to two-thirds of the way toward the values in healthy, uninfected children

Clinical and genetic analysis of 29 Brazilian patients with Huntington’s disease-like phenotype

Huntington’s disease (HD) is a neurodegenerative disorder characterized by chorea, behavioral disturbances and dementia, caused by a pathological expansion of the CAG trinucleotide in the HTT gene. Several patients have been recognized with the typical HD phenotype without the expected mutation. The objective of this study was to assess the occurrence of diseases such as Huntington’s disease-like 2 (HDL2), spinocerebellar ataxia (SCA) 1, SCA2, SCA3, SCA7, dentatorubral-pallidoluysian atrophy (DRPLA) and choreaacanthocytosis (ChAc) among 29 Brazilian patients with a HD-like phenotype. In the group analyzed, we found 3 patients with HDL2 and 2 patients with ChAc. The diagnosis was not reached in 79.3% of the patients. HDL2 was the main cause of the HD-like phenotype in the group analyzed, and is attributable to the African ancestry of this population. However, the etiology of the disease remains undetermined in the majority of the HD negative patients with HD-like phenotype. Key words: Huntington’s disease, Huntington’s disease-like, chorea-acanthocytosis, Huntington’s disease-like 2

Perceptions of newly admitted undergraduate medical students on experiential training on community placements and working in rural areas of Uganda

<p>Abstract</p> <p>Background</p> <p>Uganda has an acute problem of inadequate human resources partly due to health professionals' unwillingness to work in a rural environment. One strategy to address this problem is to arrange health professional training in rural environments through community placements. Makerere University College of Health Sciences changed training of medical students from the traditional curriculum to a problem-based learning (PBL) curriculum in 2003. This curriculum is based on the SPICES model (student-centered, problem-based, integrated, community-based and services oriented). During their first academic year, students undergo orientation on key areas of community-based education, after which they are sent in interdisciplinary teams for community placements. The objective was to assess first year students' perceptions on experiential training through community placements and factors that might influence their willingness to work in rural health facilities after completion of their training.</p> <p>Methods</p> <p>The survey was conducted among 107 newly admitted first year students on the medical, nursing, pharmacy and medical radiography program students, using in-depth interview and open-ended self-administered questionnaires on their first day at the college, from October 28-30, 2008. Data was collected on socio-demographic characteristics, motivation for choosing a medical career, prior exposure to rural health facilities, willingness to have part of their training in rural areas and factors that would influence the decision to work in rural areas.</p> <p>Results</p> <p>Over 75% completed their high school from urban areas. The majority had minimal exposure to rural health facilities, yet this is where most of them will eventually have to work. Over 75% of the newly admitted students were willing to have their training from a rural area. Perceived factors that might influence retention in rural areas include the local context of work environment, support from family and friends, availability of continuing professional training for career development and support of co-workers and the community.</p> <p>Conclusion</p> <p>Many first year students at Makerere University have limited exposure to health facilities in rural areas and have concerns about eventually working there.</p

Spatial distribution of early red lesions is a risk factor for development of vision-threatening diabetic retinopathy

Aims/hypothesis Diabetic retinopathy is characterised by morphological lesions related to disturbances in retinal blood flow. It has previously been shown that the early development of retinal lesions temporal to the fovea may predict the development of treatment-requiring diabetic maculopathy. The aim of this study was to map accurately the area where lesions could predict progression to vision-threatening retinopathy. Methods The predictive value of the location of the earliest red lesions representing haemorrhages and/or microaneurysms was studied by comparing their occurrence in a group of individuals later developing vision-threatening diabetic retinopathy with that in a group matched with respect to diabetes type, age, sex and age of onset of diabetes mellitus who did not develop vision-threatening diabetic retinopathy during a similar observation period. Results The probability of progression to vision-threatening diabetic retinopathy was higher in a circular area temporal to the fovea, and the occurrence of the first lesions in this area was predictive of the development of vision-threatening diabetic retinopathy. The calculated peak value showed that the risk of progression was 39.5% higher than the average. There was no significant difference in the early distribution of lesions in participants later developing diabetic maculopathy or proliferative diabetic retinopathy. Conclusions/interpretation The location of early red lesions in diabetic retinopathy is predictive of whether or not individuals will later develop vision-threatening diabetic retinopathy. This evidence should be incorporated into risk models used to recommend control intervals in screening programmes for diabetic retinopathy

Prime movers : mechanochemistry of mitotic kinesins

Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation