The power of A/B testing under interference

In this paper, we address the fundamental statistical question: how can you assess the power of an A/B test when the units in the study are exposed to interference? This question is germane to many scientific and industrial practitioners that rely on A/B testing in environments where control over interference is limited. We begin by proving that interference has a measurable effect on its sensitivity, or power. We quantify the power of an A/B test of equality of means as a function of the number of exposed individuals under any interference mechanism. We further derive a central limit theorem for the number of exposed individuals under a simple Bernoulli switching interference mechanism. Based on these results, we develop a strategy to estimate the power of an A/B test when actors experience interference according to an observed network model. We demonstrate how to leverage this theory to estimate the power of an A/B test on units sharing any network relationship, and highlight the utility of our method on two applications - a Facebook friendship network as well as a large Twitter follower network. These results yield, for the first time, the capacity to understand how to design an A/B test to detect, with a specified confidence, a fixed measurable treatment effect when the A/B test is conducted under interference driven by networks.Comment: 14 page

Small subunit ribosomal metabarcoding reveals extraordinary trypanosomatid diversity in Brazilian bats

Background: Bats are a highly successful, globally dispersed order of mammals that occupy a wide array of ecological niches. They are also intensely parasitized and implicated in multiple viral, bacterial and parasitic zoonoses. Trypanosomes are thought to be especially abundant and diverse in bats. In this study, we used 18S ribosomal RNA metabarcoding to probe bat trypanosome diversity in unprecedented detail. Methodology/Principal Findings: Total DNA was extracted from the blood of 90 bat individuals (17 species) captured along Atlantic Forest fragments of Espírito Santo state, southeast Brazil. 18S ribosomal RNA was amplified by standard and/or nested PCR, then deep sequenced to recover and identify Operational Taxonomic Units (OTUs) for phylogenetic analysis. Blood samples from 34 bat individuals (13 species) tested positive for infection by 18S rRNA amplification. Amplicon sequences clustered to 14 OTUs, of which five were identified as Trypanosoma cruzi I, T. cruzi III/V, Trypanosoma cruzi marinkellei, Trypanosoma rangeli, and Trypanosoma dionisii, and seven were identified as novel genotypes monophyletic to basal T. cruzi clade types of the New World. Another OTU was identified as a trypanosome like those found in reptiles. Surprisingly, the remaining OTU was identified as Bodo saltans–closest non-parasitic relative of the trypanosomatid order. While three blood samples featured just one OTU (T. dionisii), all others resolved as mixed infections of up to eight OTUs. Conclusions/Significance: This study demonstrates the utility of next-generation barcoding methods to screen parasite diversity in mammalian reservoir hosts. We exposed high rates of local bat parasitism by multiple trypanosome species, some known to cause fatal human disease, others non-pathogenic, novel or yet little understood. Our results highlight bats as a long-standing nexus among host-parasite interactions of multiple niches, sustained in part by opportunistic and incidental infections of consequence to evolutionary theory as much as to public health. Author summary: Bats make up a mega-diverse, intensely parasitized order of volant mammals whose unique behavioural and physiological adaptations promote infection by a vast array of microorganisms. Trypanosomes stand out as ancient protozoan parasites of bats. As cryptic morphology, low parasitaemia and selective growth in culture have recurrently biased survey, we used 18S ribosomal RNA metabarcoding to resolve bat trypanosomatid diversity in Atlantic Forest fragments of southeast Brazil. Next to several unknown species, our deep sequence-based detection and assignment protocol recognized multiple known human-pathogenic trypanosomes, another linked to reptile hosts as well as a non-parasitic kinetoplastid in the blood of various phyllostomid bats. The striking permissivity exposed here, in a region where bat trypanosomes recently featured in a fatal case of Chagas disease, compels further research on bats’ role in the dispersal and spill-over of various microorganisms among humans and wildlife

The Dhow's last redoubt? Vestiges of wooden boatbuilding traditions in Yemen

This is an accepted version of an article that went on to be published in the Proceedings of the Seminar for Arabian Studies in 2010. The reference for the published version is: Agius, D.A., Cooper, J.P., Jansen van Rensburg, J.and Zazzaro, C., 2010 " The dhow's last redoubt? Vestiges of wooden boatbuilding traditions in Yemen". Proceedings of the Seminar for Arabian Studies 40: 71—84. Please use the published version in any citations.The final version of the article is available from Archaeopress via the link in this record.Researchers from the MARES Project visited Yemen in February 2009 in order to investigate the building and use of traditional wooden boats (‘dhows’, in English parlance) in the country. The survey covered the coastline from Aden to Salif in the Red Sea, and visited centres of traditional dhow building and use, including Ghureira, Mocha and Khokha. The project aimed to assess the state of the industry, establish a vessel typology, understand construction processes, learn about the use of these vessels, and compile a lexicon of boatbuilding and nautical terms. This article offers the preliminary findings of the survey, pending more comprehensive publication in the future. The survey found that, in all locations visited, the building of new vessels had rapidly diminished in the preceding decade, and had now all but ceased. The only ongoing activity witnessed during the survey was repairs to existing wooden craft. In formerly large boat-building centres, wooden boat-builders, mostly elderly, have ceased work, while younger men were building fishing craft using fibreglass – the material used in the great majority of vessels in Yemen today. A preliminary typology of surviving vessel was established. The doubleended cargo-carrying za<īmahs and zārūqs were recorded only as 2 abandoned hulks. Double-ended <obrīs and transom-sterned ‘large hūrīs’, with their stern-quarter ‘fins’, continued to be used in small numbers for sein fishing and transporting livestock. Again, most examples were abandoned. Various forms of small log and plank hūrī ‘canoes’ were observed, few still in use, while the log-raft ramas survives on the Red Sea coast. The terms used for these vessel types form part of a linguistic survey of dhow activity in Yemen.This research was conducted as part of the MARES Project, a three-year programme investigating the maritime past and heritage of the Red Sea and Arabian-Persian Gulf. MARES is based at the Institute of Arab and Islamic Studies at the University of Exeter (http://projects.exeter.ac.uk/mares). The programme is funded by the Golden Web Foundation, an educational charity registered in the UK (www.goldenweb.org), to which our gratitude is due. 27 Thanks are also due to the Seven Pillars of Wisdom Trust, which provided additional financial support for the fieldwork. In addition, the MARES team would like to thank the following people for their assistance: Dr Abdulla M. Bawazir, President of Yemen’s General Organisation of Antiquities and Museums (GOAM); Dr Muhammad Taha al-Asbahi, General Director of Antiquities at GOAM; Dr Raja Batawil, head of GOAM in Aden; our GOAMappointed field companion, Salah al-Mansuri; Mr. Hasan Saleh Shihab; Emily Allardyce, Fuad Mazid al-Matairi and their colleagues at the British Yemeni Language Institute; our driver and guide Muhammad al-Matairi; Edward Prados, Director of Amideast; Chris Evens; the British Council; and the British Embassy. Last but not least, the team wishes to thank the many individual informants along Yemen’s coast who gave their assistance to its research

O processo de formação profissional nos semi-internatos : a percepção do acadêmico de enfermagem da Universidade Federal do Pará, Brasil

Avaliou-se o processo de formação profissional nos semi-internatos do Curso de Graduação em Enfermagem da Universidade Federal do Pará, a partir da percepção dos discentes. Utilizou-se uma abordagem quali-quantitativa por meio de estudo de caso, com análise documental Projeto Pedagógico - PP e das ementas do semi-internato e construção de um instrumento atitudinal do Tipo Likert. Concluiu-se que as competências de atenção a saúde e comunicação, o trabalho docente, a relação docente/discente e a articulação teoria-prática têm uma percepção positiva entre os discentes. Contudo observa-se uma percepção mais crítica quanto à oferta de cenários de prática em diferentes níveis de atenção, aspecto de grande relevância para a formação profissional em saúde

TEMPO QUE OS ESTUDANTES COM AUXÍLIO MORADIA NA UFPE LEVAM PARA SE FORMAR OU SE DESVINCULAR DA INSTITUIÇÃO

A assistência à moradia têm grande importância na vida dos alunos que não possuem condições financeiras para terem acesso à Universidade.O presente estudo procura estimar o tempo até se formar ou se desvincular para os estudantes da graduação com auxílio moradia (que residem ou residiram na residência estudantil na UFPE, ou ainda que apenas recebem o referido auxílio), a partir de algumas variáveis de interesse, tais como: tempo de residência, tempo de vínculo com a instituição e obtenção da titulação universitária, destacando-se as diferenças/semelhanças, por sexo e por área de conhecimento do curso. Os dados analisados se referem aos beneficiários do auxílio no período de 2005 a 2014. Através da aplicação das técnicas da análise de sobrevivência foi possível estimar o tempo mediano para o estudante ficar com auxílio moradia até se formar e também até ser desvinculado. Como resultado, pode-se identificar que alguns discentes mudam de curso durante o período do auxílio, como também, o tempo mediano do residente até se formar difere para área de exatas como também em relação ao sexo. O mesmo não aconteceu com o modelo de sobrevivência até o aluno se desvincular, visto que nem a área de estudo e nem o sexo apresentaram diferenças significativas nas curvas de sobrevivência

Relação entre depressão materna como fator de risco para trauma na infância e transtornos de humor em jovens

Background Maternal depression may be a risk factor for childhood trauma (CT), with resultant offspring development of mood disorders (MD) in adult life. Objective To verify the relationship between maternal depression (as a risk factor for childhood trauma) and mood disorders in young adults. Methods The sample was composed of 164 young adults and their mothers. Maternal depression was identified through the Mini International Neuropsychiatric Interview (M.I.N.I.). Mood Disorders in the young adults were confirmed with the Structured Interview for the DSM-IV (SCID), whereas the CT was evaluated using the Childhood Trauma Questionnaire (CTQ). Results In the group of young adults with MD, individuals who had depressed mothers presented higher mean scores of CT in comparison to the ones who did not have mothers with Depression (p < 0.005). Childhood trauma was also associated with lower social classes (p < 0.005). In the group of young adults without MD, the only variable that was associated with CT was the young adult’s (not) current work (p < 0.005). Discussion Maternal depression was considered to be a risk factor for CT and MD in young adults. Thus, preventing and treating maternal psychiatric disorders may diminish the risk of offspring childhood trauma, and, consequently, avoid negative effects in the offspring’s adult life.Contexto Depressão materna pode ser um fator de risco para trauma na infância (TI), com consequente desenvolvimento de transtornos de humor (TH) em seus filhos na vida adulta. Objetivo Verificar a relação entre depressão materna (como fator de risco para TI) e TH em jovens. Métodos A amostra foi composta de 164 jovens adultos e suas mães. A depressão materna foi identificada por meio do Mini International Neuropsychiatric Interview (M.I.N.I.). Transtornos de humor nos jovens foram confirmados pela entrevista estruturada para o DSM-IV (SCID), enquanto o TI foi avaliado pelo Questionário de Trauma na Infância (CTQ). Resultados No grupo de jovens com TH, indivíduos que tiveram mães deprimidas apresentaram escores médios de TI mais altos em comparação aos que não tinham mães com depressão (p < 0,05). Trauma na infância também esteve associado com classes sociais desfavorecidas (p < 0,05). No grupo de jovens sem TH, a única variável associada ao TI foi o (não) trabalho do jovem (p < 0,05). Conclusões A depressão materna foi considerada fator de risco para TI e TH nos jovens. Portanto, prevenir e tratar transtornos psiquiátricos maternos pode diminuir o risco de trauma infantil no filho e, por consequência, evitar efeitos negativos na vida adulta da prole

Relationship between maternal depression as a risk factor for childhood trauma and mood disorders in young adults

Background Maternal depression may be a risk factor for childhood trauma (CT), with resultant offspring development of mood disorders (MD) in adult life. Objective To verify the relationship between maternal depression (as a risk factor for childhood trauma) and mood disorders in young adults. Methods The sample was composed of 164 young adults and their mothers. Maternal depression was identified through the Mini International Neuropsychiatric Interview (M.I.N.I.). Mood Disorders in the young adults were confirmed with the Structured Interview for the DSM-IV (SCID), whereas the CT was evaluated using the Childhood Trauma Questionnaire (CTQ). Results In the group of young adults with MD, individuals who had depressed mothers presented higher mean scores of CT in comparison to the ones who did not have mothers with Depression (p < 0.005). Childhood trauma was also associated with lower social classes (p < 0.005). In the group of young adults without MD, the only variable that was associated with CT was the young adult’s (not) current work (p < 0.005). Discussion Maternal depression was considered to be a risk factor for CT and MD in young adults. Thus, preventing and treating maternal psychiatric disorders may diminish the risk of offspring childhood trauma, and, consequently, avoid negative effects in the offspring’s adult life

EXECUÇÃO ORÇAMENTÁRIA: UM ESTUDO SOBRE A INSCRIÇÃO DE RESTOS A PAGAR NAS UNIVERSIDADES FEDERAIS DO NORDESTE

A presente pesquisa tem como objetivo verificar se houve modificação na situação dos restos a pagar nas Universidades Federais do Nordeste com o advento do decreto nº 7654 de 23 de dezembro de 2011. Para tanto, analisou-se a execução orçamentária em catorze universidades de nordeste, por meio das informações disponibilizadas no site de Tribunal de Contas da União (TCU) e do Senado Federal (SIGA Brasil). O levantamento de dados foi feito através da pesquisa documental e a análise foi realizada por meio de software estatístico Statistical Package for Social Sciences (SPSS), utilizando-se dos testes de Shapiro-Wilk e Wilcoxon, media e desvio padrão, com 5% de significância. Conclui-se que não houve diferenças estatísticas entre o antes e o depois do decreto em relação ao percentual de restos a pagar sobre o montante empenhado pelas IFES (p=0,551). Contudo, em relação às despesas de capital, foram constatadas diferenças estatisticamente significantes entre o percentual médio empenhado/autorizado antes do decreto com o depois do decreto (p=0,006),ou seja, as IFES passaram a emprenhar menos depois do decreto, sendo estas as que mais contribuíram para inscrição de restos a pagar. Já quanto às despesas correntes, não houve diferenças estatisticamente significantes entre as IFES ante e depois do decreto. Ressalta-se ainda que houve um pequeno aumento em relação aos restos a pagar nas despesas com pessoal para as IFES com menos orçamento

Comparison of two methods for in vitro multiplication of Radopholus similis and Pratylenchus brachyurus in carrot cylinders

ABSTRACTThe use of in vitro mass multiplication of nematodes under axenic conditions allows intensification of studies on taxonomy, biology, epidemiology and control of these pathogens. In the present study, two methods were compared for in vitro multiplication of two species of plant-parasitic nematodes, Radopholus similis and Pratylenchus Brachyurus in 20, 40 and 60 day-periods. Both techniques involved the use of carrot cylinders placed in jars with lids, with water–agar in the bottom of the flasks (WA+) or without (WA-). In WA- the nematodes were treated with a 1% solution of ampicillin whilst for WA+ the axenization was carried out with a solution of mercuric chloride (0.01%), and streptomycin sulfate 0.02%. The WA+ condition was the most favorable for multiplication of both species of nematodes, resulting in a population increase of about 280 times for R. similis and 226 times for P. brachyurus in relation to the founding population of 25 individuals. For WA- a population increase of only five times after 60 days for R. similis and a duplication of the population after 60 days for P. brachyurus was obtained. Overall, the largest amount of nematodes occurred at 60 days after inoculation