On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principle (Part One)

In October 1924, the Physical Review, a relatively minor journal at the time, published a remarkable two-part paper by John H. Van Vleck, working in virtual isolation at the University of Minnesota. Van Vleck combined advanced techniques of classical mechanics with Bohr's correspondence principle and Einstein's quantum theory of radiation to find quantum analogues of classical expressions for the emission, absorption, and dispersion of radiation. For modern readers Van Vleck's paper is much easier to follow than the famous paper by Kramers and Heisenberg on dispersion theory, which covers similar terrain and is widely credited to have led directly to Heisenberg's "Umdeutung" paper. This makes Van Vleck's paper extremely valuable for the reconstruction of the genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did not take the next step and develop matrix mechanics himself.Comment: 82 page

Effects of horn status on behaviour in fattening cattle in the field and during reactivity tests

International audienceDisbudding is in the short-term invasive and needs pharmacological pain treatment but it facilitates animal management. The present study investigates the longer-term consequences on behaviour to evaluate possible effects on animal welfare. Experiment 1 (E1) used 81 bulls up to the age of 12 and experiment 2 (E2) 71 heifers up to the age of 11 months. Half of the animals was disbudded at about 2 months of age. Different rearing conditions (RC) were compared, with animals housed in groups containing i) only animals with horns, ii) only disbudded animals, or iii) mixed (half with horns, and half disbudded; only in E1). Each rearing condition had two replicates. The effects of RC were studied on general activity and synchrony at 4 and 9 months (E1 and E2), and 7 and 12 months (only E1) of age. In E2 and during the last measuring period of E1, disbudding and mixing modified physical activity in the field. Behaviour during a novel object test (NOT) and a food competition test (FCT) were studied at 10 and 11 months of age, for E1 and E2, respectively. During the FCT, compared to disbudded, horned (unmixed) animals showed more agonistic interactions with contact in E1, and more agonistic behaviour without contact in E2. In the NOT, disbudded (mixed and unmixed) animals of E1 presented more fear-related reactions compared to horned animals while in E2, the opposite was found. In the NOT and FCT, mixed groups had intermediate levels for behaviours influenced by horn status. In conclusion, the behavioural traits influenced by horn status appeared to be at least partly associated with agonistic behaviour and fear, and may influence welfare status. However, depending on the experiment and the test, different negative and positive effects on welfare were found. The mixing of horned and disbudded animals in rearing groups may also modify the behavioural consequences of horn status

Socio-demographic and epidemiological characteristics associated with human immunodeficiency virus type I (HIV-1) infection in HIV-1-explosed but uninfected individuals, and in HIV-1-infected patients from a southern brasilian population Características sociodemográficas e epidemiológicas associadas com a infecção pelo vírus da imunodeficiência humana tipo 1 (HIV-1) em indivíduos expostos ao HIV-1 mas não infectados e em pacientes infectados pelo HIV-1, provenientes da população da região Sul do Brasil

The ability to control human immunodeficiency virus type 1 (HIV-1) infection and progression of the disease is regulated by host and viral factors. This cross-sectional study describes the socio-demographic and epidemiological characteristics associated with HIV-1 infection in 1,061 subjects attended in Londrina and region, south of Brazil: 136 healthy individuals (Group 1), 147 HIV-1-exposed but uninfected individuals (Group 2), 161 HIV-1-infected asymptomatic patients (Group 3), and 617 patients with AIDS (Group 4). Data were obtained by a standardized questionnaire and serological tests. The age of the individuals ranged from 15.1 to 79.5 years, 54.0% and 56.1% of the Groups 3 and 4 patients, respectively, were men. The major features of groups 2, 3, and 4 were a predominance of education level up to secondary school (55.8%, 60.2% and 62.4%, respectively), sexual route of exposure (88.4%, 87.0% and 82.0%, respectively), heterosexual behavior (91.8%, 75.2% and 83.7%, respectively), and previous sexually transmitted diseases (20.4%, 32.5%, and 38.1%, respectively). The patients with AIDS showed the highest rates of seropositivity for syphilis (25.6%), of anti-HCV (22.3%), and anti-HTLV I/II obtained by two serological screening tests (6.2% and 6.8%, respectively). The results documenting the predominant characteristics for HIV-1 infection among residents of Londrina and region, could be useful for the improvement of current HIV-1 prevention, monitoring and therapeutic programs targeted at this population.<br>Este estudo transversal descreve as principais características sociodemográficas e epidemiológicas associadas com a infecção pelo HIV-1 em 1.061 indivíduos atendidos em Londrina e região, Sul do Brasil: 136 indivíduos saudáveis (Grupo 1), 147 indivíduos expostos ao HIV-1 mas não infectados (Grupo 2), 161 pacientes infectados pelo HIV-1 assintomáticos (Grupo 3) e 617 pacientes com aids (Grupo 4). Os dados foram obtidos pela aplicação de um questionário padronizado e realização de testes sorológicos. A idade dos indivíduos variou de 15,1 a 79,5 anos; 54,0% e 56,1% dos pacientes dos Grupos 3 e 4, respectivamente, eram homens. As principais características dos indivíduos dos Grupos 2, 3 e 4 foram o predomínio do nível educacional com até oito anos de escolaridade (58,8%, 60,2% e 62,4%, respectivamente), a via sexual de transmissão (88,4%, 87,0% e 82,0%, respectivamente), o comportamento heterossexual (91,8%, 75,2% e 83,7%, respectivamente) e antecedentes de doenças sexualmente transmissíveis (20,4%, 32,5% e 38,1%, respectivamente). Os pacientes com aids apresentaram os valores mais elevados de soropositividade para sífilis (25,6%), anti-HCV (22,3%) e anti-HTLV I/II em dois testes de triagem sorológica (6,2% e 6,8%, respectivamente). Os resultados documentando as características predominantes associadas com a infecção pelo HIV-1 observada nos indivíduos de Londrina e região, poderá ser útil na melhoria dos atuais programas de prevenção, monitoramento e de tratamento da infecção pelo HIV-1 dirigidos a esta população

Eco-epidemiological aspects of Trypanosoma cruzi, Trypanosoma rangeli and their vector (Rhodnius pallescens) in Panama Generalidades do Trypanosoma cruzi, do Trypanosoma rangeli e do seu vetor (Rhodnius pallescens) no Panamá

The eco-epidemiology of T. cruzi infection was investigated in the Eastern border of the Panama Canal in Central Panama. Between 1999 and 2000, 1110 triatomines were collected: 1050 triatomines (94.6%) from palm trees, 27 (2.4%) from periurban habitats and 33 (3.0%) inside houses. All specimens were identified as R. pallescens. There was no evidence of vector domiciliation. Salivary glands from 380 R. pallescens revealed a trypanosome natural infection rate of 7.6%, while rectal ampoule content from 373 triatomines was 45%. Isoenzyme profiles on isolated trypanosomes demonstrated that 85.4% (n = 88) were T. cruzi and 14.6% (n = 15) were T. rangeli. Blood meal analysis from 829 R. pallescens demonstrated a zoophilic vector behavior, with opossums as the preferential blood source. Seroprevalence in human samples from both study sites was less than 2%. Our results demonstrate that T. cruzi survives in the area in balanced association with R. pallescens, and with several different species of mammals in their natural niches. However, the area is an imminent risk of infection for its population, consequently it is important to implement a community educational program regarding disease knowledge and control measures.<br>A epidemiologia da infecção do T. cruzi foi investigada na margem oriental do canal do Panamá, na região central da Republica do Panamá. A informação obtida durante o estudo avaliou fatores de risco da doença de Chagas nesta área. Entre 1999 e 2000, 1110 triatomíneos foram coletados: 1050 triatomíneos (94,6%) em palmeiras, 27 (2,4%) em habitats periurbanos e 33 (3,0%) no interior de casas. Todos os espécimens foram identificados como R. pallescens. Não havia nenhuma evidência de domiciliação do vetor. O exame de glândulas salivares de 380 R. pallescens revelaram taxa de infecção natural por Trypanosoma de 7,6%, mas o conteúdo da ampola rectal de 373 triatomíneos mostrou 45% de positividade. Os perfis de isoenzimas em Trypanosomas isolados demonstraram que 85,4% (n = 88) eram T. cruzi e 14,6% (n = 15) eram T. rangeli. A análise da refeição de sangue de 829 R. pallescens demonstrou comportamento zoofílico do vetor, sendo os gambás a fonte preferencial de sangue. Soroprevalência nos seres humanos de ambos locais de estudo foi menos que 2%. Nossos resultados demonstram que T. cruzi sobrevive na área em associação equilibrada com R. pallescens e com diversas espécies diferentes de mamíferos em seus nichos naturais. Entretanto, a área é um risco eminente de infecção para sua população, pelo que é importante executar um programa educacional na comunidade a respeito das medidas, do conhecimento e do controle da doença