17 research outputs found
Benford's law: what does it say on adversarial images?
Convolutional neural networks (CNNs) are fragile to small perturbations in
the input images. These networks are thus prone to malicious attacks that
perturb the inputs to force a misclassification. Such slightly manipulated
images aimed at deceiving the classifier are known as adversarial images. In
this work, we investigate statistical differences between natural images and
adversarial ones. More precisely, we show that employing a proper image
transformation and for a class of adversarial attacks, the distribution of the
leading digit of the pixels in adversarial images deviates from Benford's law.
The stronger the attack, the more distant the resulting distribution is from
Benford's law. Our analysis provides a detailed investigation of this new
approach that can serve as a basis for alternative adversarial example
detection methods that do not need to modify the original CNN classifier
neither work on the raw high-dimensional pixels as features to defend against
attacks
Dental Occlusion in a Split Amazon Indigenous Population: Genetics Prevails over Environment
Background: Studies examining human and nonhuman primates have supported the hypothesis that the recent increase in
the occurrence of misalignment of teeth and/or incorrect relation of dental arches, named dental malocclusion, is mainly
attributed to the availability of a more processed diet and the reduced need for powerful masticatory action. For the first
time on live human populations, genetic and tooth wear influences on occlusal variation were examined in a split
indigenous population. The Arara-Iriri people are descendants of a single couple expelled from a larger village. In the
resultant village, expansion occurred through the mating of close relatives, resulting in marked genetic cohesion with
substantial genetic differences.
Methodology/Principal Findings: Dental malocclusion, tooth wear and inbreeding coefficient were evaluated. The sample
examined was composed of 176 individuals from both villages. Prevalence Ratio and descriptive differences in the
outcomes frequency for each developmental stage of the dentition were considered. Statistical differences between the
villages were examined using the chi-square test or Fisher’s exact statistic. Tooth wear and the inbreeding coefficient (F)
between the villages was tested with Mann-Whitney statistics. All the statistics were performed using two-tailed distribution
at p#0.05. The coefficient inbreeding (F) confirmed the frequent incestuous unions among the Arara-Iriri indigenous group.
Despite the tooth wear similarities, we found a striking difference in occlusal patterns between the two Arara villages. In the
original village, dental malocclusion was present in about one third of the population; whilst in the resultant village, the
occurrence was almost doubled. Furthermore, the morphological characteristics of malocclusion were strongly different
between the groups.
Conclusions/Significance: Our findings downplay the widespread influence of tooth wear, a direct evidence of what an
individual ate in the past, on occlusal variation of living human populations. They also suggest that genetics plays the most
important role on dental malocclusion etiology
Predictors of HBeAg status and hepatitis B viraemia in HIV-infected patients with chronic hepatitis B in the HAART era in Brazil
<p>Abstract</p> <p>Background</p> <p>HBV-HIV co-infection is associated with an increased liver-related morbidity and mortality. However, little is known about the natural history of chronic hepatitis B in HIV-infected individuals under highly active antiretroviral therapy (HAART) receiving at least one of the two drugs that also affect HBV (TDF and LAM). Information about HBeAg status and HBV viremia in HIV/HBV co-infected patients is scarce. The objective of this study was to search for clinical and virological variables associated with HBeAg status and HBV viremia in patients of an HIV/HBV co-infected cohort.</p> <p>Methods</p> <p>A retrospective cross-sectional study was performed, of HBsAg-positive HIV-infected patients in treatment between 1994 and 2007 in two AIDS outpatient clinics located in the São Paulo metropolitan area, Brazil. The baseline data were age, sex, CD4 T+ cell count, ALT level, HIV and HBV viral load, HBV genotype, and duration of antiretroviral use. The variables associated to HBeAg status and HBV viremia were assessed using logistic regression.</p> <p>Results</p> <p>A total of 86 HBsAg patients were included in the study. Of these, 48 (56%) were using combination therapy that included lamivudine (LAM) and tenofovir (TDF), 31 (36%) were using LAM monotherapy, and 7 patients had no previous use of either one. Duration of use of TDF and LAM varied from 4 to 21 and 7 to 144 months, respectively. A total of 42 (48. 9%) patients were HBeAg positive and 44 (51. 1%) were HBeAg negative. The multivariate analysis revealed that the use of TDF for longer than 12 months was associated with undetectable HBV DNA viral load (serum HBV DNA level < 60 UI/ml) (<it>p </it>= 0. 047). HBeAg positivity was associated with HBV DNA > 60 UI/ml (p = 0. 001) and ALT levels above normality (<it>p </it>= 0. 038).</p> <p>Conclusion</p> <p>Prolonged use of TDF containing HAART is associated with undetectable HBV DNA viral load. HBeAg positivity is associated with HBV viremia and increased ALT levels.</p
Morcegos (Mammalia: Chiroptera) da região do Médio Rio Teles Pires, Sul da Amazônia, Brasil
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Factor IX Gene Haplotypes in Amerindians
We have determined the haplotypes of the factor IX gene for 95 Indians from 5 Brazilian Amazon tribes: Wayampf, Wayana-Apalaf, Kayapo, Arara, and Yanomami. Eight polymorphisms linked to the factor IX gene were investigated: MseI (at 5\u27, nt —698), BamHI (at 5\u27, nt —561), DdeI (intron 1), BamHI (intron 2), XmnI (intron 3), Taql (intron 4), Mspl (intron 4), and Hhal (at 3\u27, ~ 8 kb). The results of the haplotype distribution and the allele frequencies for each of the factor IX gene polymorphisms in Amerindians were similar to the results reported for Asian populations but differed from results for other ethnic groups. Only five haplotypes were identified within the entire Amerindian study population, and the haplotype distribution was significantly different among the five tribes, with one (Arara) to four (Wayampf) haplotypes being found per tribe. These findings indicate a significant heterogeneity among the Indian tribes and contrast with the homogeneous distribution of the /?-globin gene cluster haplotypes but agree with our recent findings on the distribution of a-globin gene cluster haplotypes and the allele frequencies for six VNTRs in the same Amerindian tribes. Our data represent the first study of factor IX-associated polymorphisms in Amerindian populations and emphasizes the applicability of these genetic markers for population and human evolution studies
Genetic relationships among native americans based on beta-globin gene cluster haplotype frequencies
The distribution of b-globin gene haplotypes was studied in 209 Amerindians from eight tribes of the Brazilian Amazon: Asurini from Xingú, Awá-Guajá, Parakanã, Urubú-Kaapór, Zoé, Kayapó (Xikrin from the Bacajá village), Katuena, and Tiriyó. Nine different haplotypes were found, two of which (n. 11 and 13) had not been previously identified in Brazilian indigenous populations. Haplotype 2 (+ - - - -) was the most common in all groups studied, with frequencies varying from 70% to 100%, followed by haplotype 6 (- + + - +), with frequencies between 7% and 18%. The frequency distribution of the b-globin gene haplotypes in the eighteen Brazilian Amerindian populations studied to date is characterized by a reduced number of haplotypes (average of 3.5) and low levels of heterozygosity and intrapopulational differentiation, with a single clearly predominant haplotype in most tribes (haplotype 2). The Parakanã, Urubú-Kaapór, Tiriyó and Xavante tribes constitute exceptions, presenting at least four haplotypes with relatively high frequencies. The closest genetic relationships were observed between the Brazilian and the Colombian Amerindians (Wayuu, Kamsa and Inga), and, to a lesser extent, with the Huichol of Mexico. North-American Amerindians are more differentiated and clearly separated from all other tribes, except the Xavante, from Brazil, and the Mapuche, from Argentina. A restricted pool of ancestral haplotypes may explain the low diversity observed among most present-day Brazilian and Colombian Amerindian groups, while interethnic admixture could be the most important factor to explain the high number of haplotypes and high levels of diversity observed in some South-American and most North-American tribes