Invertibility in groupoid C*-algebras

Given a second-countable, Hausdorff, \'etale, amenable groupoid G with compact unit space, we show that an element a in C*(G) is invertible if and only if \lambda_x(a) is invertible for every x in the unit space of G, where \lambda_x refers to the "regular representation" of C*(G) on l_2(G_x). We also prove that, for every a in C*(G), there exists some x in G^{(0)} such that ||a|| = ||\lambda_x(a)||.Comment: 8 page

Racial inequities in tooth loss among older Brazilian adults: A decomposition analysis

OBJECTIVE: To determine the extent to which racial inequities in tooth loss and functional dentition are explained by individual socioeconomic status, smoking status and frequency/reason for the use of dental services. METHODS: Data came from the Brazilian Longitudinal Study of Ageing, a nationally representative sample of community-dwelling people aged 50 years and over. Tooth loss and functional dentition (ie 20+ natural teeth) were the outcomes. The main explanatory variable was self-classified race. Covariates included dental visits in the past 12 months, dental visits for check-ups only, smoking status, self-reported chronic conditions, depression and cognitive function. Logistic regression and Blinder-Oaxaca decomposition analysis were used to estimate the share of each factor in race-related tooth loss inequities. RESULTS: The analytical sample comprised of 7126 respondents. While the prevalence of functional dentition in White Brazilians was 37% (95% CI: 33.5;40.9), it was 29% (95% CI: 26.4;31.6) among Browns and 30% (95% CI: 25.1;35.4) among Blacks. The average number of lost teeth among Whites, Browns and Blacks were 18.7 (95% CI: 17.8;19.6), 20.4 (95% CI: 19.7;21.1) and 20.8 (95% CI: 19.5;22.0), respectively. Decomposition analysis showed that the selected covariates explained 71% of the racial inequalities in tooth loss. Dental visits in the previous year and smoking status explained nearly half of race-related gaps. Other factors, such as per capita income, education and cognitive status, also had an important contribution to the examined inequalities. The proportion of racial inequities in tooth loss that was explained by dental visits (frequency and reason) and smoking status decreased from 40% for those 50-59 years of age to 22% among participants aged 70-79 years. CONCLUSIONS: Frequency and reason for dental visits and smoking status explained nearly half of the racial inequity in tooth loss among Brazilian older adults. The Brazilian Family Health Strategy Program should target older adults from racial groups living in deprived areas

Serological profile of foot-and-mouth disease in wildlife populations of West and Central Africa with special reference to Syncerus caffer subspecies

The role which West and Central African wildlife populations might play in the transmission dynamics of FMD is not known nor have studies been performed in order to assess the distribution and prevalence of FMD in wild animal species inhabiting those specific regions of Africa. This study reports the FMD serological profile extracted from samples (n = 696) collected from wildlife of West and Central Africa between 1999 and 2003. An overall prevalence of FMDV NSP reactive sera of 31.0% (216/696) was estimated, where a significant difference in seropositivity (p = 0.000) was reported for buffalo (64.8%) as opposed to other wild animal species tested (17.8%). Different levels of exposure to the FMDV resulted for each of the buffalo subspecies sampled (p = 0.031): 68.4%, 50.0% and 0% for Nile Buffalo, West African Buffalo and African Forest Buffalo, respectively. The characterisation of the FMDV serotypes tested for buffalo found presence of antibodies against all the six FMDV serotypes tested, although high estimates for type O and SAT 3 were reported for Central Africa. Different patterns of reaction to the six FMDV serotypes tested were recorded, from sera only positive for a single serotype to multiple reactivities. The results confirmed that FMDV circulates in wild ruminants populating both West and Central Africa rangelands and in particular in buffalo, also suggesting that multiple FMDV serotypes might be involved with type O, SAT 2 and SAT 1 being dominant. Differences in serotype and spill-over risk between wildlife and livestock likely reflect regional geography, historical circulation and differing trade and livestock systems

Predictive coding and representationalism

According to the predictive coding theory of cognition (PCT), brains are predictive machines that use perception and action to minimize prediction error, i.e. the discrepancy between bottom–up, externally-generated sensory signals and top–down, internally-generated sensory predictions. Many consider PCT to have an explanatory scope that is unparalleled in contemporary cognitive science and see in it a framework that could potentially provide us with a unified account of cognition. It is also commonly assumed that PCT is a representational theory of sorts, in the sense that it postulates that our cognitive contact with the world is mediated by internal representations. However, the exact sense in which PCT is representational remains unclear; neither is it clear that it deserves such status—that is, whether it really invokes structures that are truly and nontrivially representational in nature. In the present article, I argue that the representational pretensions of PCT are completely justified. This is because the theory postulates cognitive structures—namely action-guiding, detachable, structural models that afford representational error detection—that play genuinely representational functions within the cognitive system

The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a “total ancestry” estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries - a phenomenon described and intended as the “whitening of Brazil” - is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations