Entropy and Poincar\'e recurrence from a geometrical viewpoint

We study Poincar\'e recurrence from a purely geometrical viewpoint. We prove that the metric entropy is given by the exponential growth rate of return times to dynamical balls. This is the geometrical counterpart of Ornstein-Weiss theorem. Moreover, we show that minimal return times to dynamical balls grow linearly with respect to its length. Finally, some interesting relations between recurrence, dimension, entropy and Lyapunov exponents of ergodic measures are given.Comment: 11 pages, revised versio

Tuberculosis Prevalence in Children at High-Risk from Ameixoeira, Lisbon

Introdução. As taxas de prevalência de tuberculose infecção e doença têm declinado em Portugal. No entanto, a pandemia da infecção pelo vírus de imunodeficiência humana, a toxicodependência e más condições de salubridade podem reverter esta tendência. O rastreio de crianças assintomáticas em contacto com adultos em risco de contrair a doença é crucial pois os casos de tuberculose infantil são devidos a um risco elevado e recente de transmissão na comunidade. Objectivos. Determinar a prevalência de tuberculose infecção/doença numa amostra de crianças em contacto com adultos de risco; determinar a prevalência de factores de risco e sua efectividade como preditores de infecção/doença nesta amostra; administrar quimioprofilaxia/terapêutica aos casos detectados e investigar as possíveis fontes de contágio. População e Métodos. Estudou-se uma amostra de conveniência de crianças que frequentavam uma instituição recreativa para crianças e jovens na Ameixoeira – Lumiar (Lisboa) no período de Abril-Maio de 2005. Aplicou-se um questionário sobre factores de risco para tuberculose e fez-se prova tuberculínica pelo método de Mantoux. A leitura foi efectuada após 72 horas. Os casos positivos (induração > 15 mm de diâmetro) foram submetidos a avaliação clínica e radiológica e quimioprofilaxia/terapêutica. Os seus coabitantes foram investigados. Os dados foram analisados pelo programa StatCal-Epiinfo 3.2.2. Resultados. Estudaram-se 100 crianças (54 famílias) das quais 44% tinham pelo menos um factor de risco. Em duas crianças o teste de tuberculina foi positivo sendo o diagnóstico final de tuberculose infecção. O rastreio dos seus coabitantes foi negativo. Aprevalência de infecção na amostra estudada foi de 2:100. O questionário aplicado teve um valor preditivo positivo de 2,2% e negativo de 98% para detectar infecção por tuberculose. Conclusões. A prevalência de infecção na amostra de crianças estudada foi elevada. O questionário aplicado teve pouca acuidade para predizer a presença de infecção/doença nesta amostra

Predicting Renal Scar after Pyelonephritis in Children Younger than Two Years of Age

Objectivos. Identificar factores laboratoriais e imagiológicos associados ao desenvolvimento de cicatriz renal sequelar após pielonefrite em doentes com menos de dois anos de idade e avaliar o papel da ecografia no estudo não invasivo de pielonefrite. Local. Hospital pediátrico universitário de nível III. População. Crianças com idade inferior a dois anos hospitalizadas com o diagnóstico de primeira pielonefrite. Métodos. Avaliação prospectiva do risco de cicatriz renal, através de parâmetros laboratoriais e imagiológicos. Estudo de efectividade da ecografia renal e vesical para identificar pielonefrite aguda e refluxo vesico-ureteral (RVU). Admite-se como método padrão para detecção de pielonefrite aguda e cicatriz renal a cintigrafia renal com DMSA e para detecção de RVU, a cisto-uretografia permiccional (CUM). Resultados. Estudaram-se 134 crianças, com mediana de idades de 3 meses (p25-p75: 1-9 meses) sendo 60% do sexo masculino. Acintigrafia em ambulatório evidenciou a presença de cicatriz renal em 42% das crianças. Valores de proteína C reactiva superiores a 5 mg/dl estiveram associados a alterações da cintigrafia em ambulatório [RR 2,7 (IC95% 1,1-7), VP+ 64,3%, VP– 76,5%]. A presença de RVU grau ≥ II esteve associada a cicatriz renal na cintigrafia em ambulatório [RR 2,6 (IC95% 1,7-4,2), VP+ 100%, VP–51,7%]. Vinte por cento das crianças tinha RVU verificado pela CUM, tendo a ecografia excluído de forma significativa a sua presença, em relação à CUM [LR+ 9,9 (1,4-69,3), VP– 94,4%]. Conclusões. No grupo estudado, o valor de proteína C reactiva e a presença de RVU grau ≥ II foram os principais factores preditivos de cicatriz renal. O papel da ecografia parece ser relevante no estudo de pielonefrite, sobretudo para excluir RVU

Dynamics Study of the HO(v‘=0) + O2(v‘ ‘) Branching Atmospheric Reaction. 1. Formation of Hydroperoxyl Radical

We report a theoretical study of the title four-atom atmospheric reaction for a range of translational energies 0.1 ≤ Etr/kcal mol-1 ≤ 40 and the range 13 ≤ v‘ ‘ ≤ 27 of vibrational quantum numbers of the oxygen molecule. All calculations have employed the quasiclassical trajectory method, and a realistic potential energy surface obtained by using the double many-body expansion (DMBE) method for ground-state HO3

From the lab to the river: Determination of ecological hosts of Anodonta anatina

1. Coextinction is the simplest form of secondary extinction and freshwater mussels (Bivalvia, Unionida) may be particularly prone to this phenomenon as their life cycle includes an obligatory parasitic larval stage on fish hosts. 2. The main aims of this study were to determine the possible ecological fish hosts of Anodonta anatina (Linnaeus, 1758) in several rivers of the Douro basin in north ern Portugal and to assess possible spatial and temporal differences in glochidial (larval) loads. In order to achieve this, electrofishing was conducted from December to April, the fish fauna was characterized, and levels of infestation with A. anatina glochidia were determined. 3. Native cyprinid species, mainly Luciobarbus bocagei (Iberian barbel) and Squalius carolitertii (northern Iberian chub), together with the non-native Lepomis gibbosus (pumpkinseed sunfish) and Alburnus alburnus (common bleak), were found to have the highest glochidial loads. Clear differences in infestation between rivers and throughout time were detected, with an infestation period from January to March, and with the Tâmega River having the highest prevalence. 4. Anodonta anatina is able to infest a variety of fish species, and this together with earlier studies showed that the metamorphosis into juveniles occurs mainly in native cyprinid species, although non-native species like common bleak can also be considered suitable hosts. However, the larvae infesting other non-native spe cies, such as the pumpkinseed sunfish, do not metamorphose and can be consid ered ‘dead ends’. 5. Overall, the results reported here are important for the conservation of A. anatina (and other unionoid species) because several Iberian rivers (and worldwide) have been subjected to the extirpation of native fish species and the introduction of non-native fish species. Therefore, careful assessments of fish communities should be conducted to assess possible negative interactions with freshwater musselsFundação para a Ciência e a Tecnologia, Grant/Award Number: PTDC/AGRFOR/1627/201

Invasive crayfishes as a threat to freshwater bivalves: interspecific differences and conservation implications

Freshwater bivalves have suffered major global declines, being the introduction of invasive alien species (IAS) an important, but not well studied, mechanism of threat. This study assessed the predator-prey relationship between two non-native crayfish species (Procambarus clarkii and Pacifastacus leniusculus) and three native (Anodonta anatina, Potomida littoralis and Unio delphinus) and one non-native (Corbicula fluminea) freshwater bivalve species through experiments in laboratory and validation under natural conditions (Sabor River basin, Portugal). All native bivalve species were preyed both in laboratory and in the field; however, both crayfish species were unable to prey C. fluminea. Predation was dependent on crayfish and bivalve species but was not affected neither by crayfish nor bivalve sizes. In the laboratory, the most preyed species by both crayfishes was A. anatina. On average, this species was preyed at least 12% more than other species, when crayfishes had a choice. Similar results were found in the field. We also found signs of competition between both crayfishes, being P. clarkii more dominant and aggressive as this species, on average, manipulated the bivalves 63.6% more times and 24:33 min longer than P. leniusculus, and initiated 55.8% more agnostic bouts. Our results support the idea that P. clarkii and P. leniusculus can affect native freshwater bivalves, but clear interspecific differences were detected. Both crayfishes may have direct and indirect impacts on bivalve populations by increasing mortality or by reducing their fitness. In addition, since both crayfishes do not prey C. fluminea, they offer this IAS another advantage over native bivalves. Given the widespread distribution of both P. clarkii and P. leniusculus and the threatened status of many freshwater bivalves, the dynamics and impacts of this relationship should be taken in account in the implementation of management measures devoted to the conservation of native freshwater bivalves.This work was supported by Portuguese FCT - Foundation for Science and Technology, Project FRESHCO: Multiple implications of invasive species on Freshwater Mussel co-extinction processes (contract PTDC/AGR-FOR/1627/2014-04/SAICT/2015) and Project 3599-Promoting Scientific and Technological Development Production and the Constitution of Thematic Networks (3599-PPCDT), FEDER - European Community Funds. FCT also support M.L.L. with a doctoral grant (SFRH/BD/115728/2016). We thank the three anonymous referees for constructive suggestions

Admission for Imported Malaria in Children, in Two Hospitals of Lisbon Urban Area

Introdução: Apesar de em Portugal não haver malária endógena,a crescente mobilidade das populações e os laços históricos com África possibilitam a importação de casos para o nosso país. O presente estudo pretende contribuir para melhorar o conhecimento epidemiológico e clínico da malária importada na região de Lisboa. Métodos: Realizou-se um estudo descritivo das crianças com malária, internadas em dois hospitais da Grande Lisboa, durante um período de seis anos (1999-2004). Resultados: Foram identificados 134 casos, sendo a mediana das idades de sete anos. A maioria (93,3%) era de origem africana e referia estadia em região endémica (90%). O Plasmodium falciparum foi o agente etiológico mais frequente (73%). A febre foi a manifestação clínica mais frequente, seguida de manifestações gastrointestinais e cefaleias. Ocorreram complicações em 42% dos doentes, sendo a trombocitopenia (19,4%) e a anemia grave (9%) as mais frequentes. A halofantrina e o quinino foram os anti-maláricos mais usados. Conclusões: A malária importada é uma patologia relativamente comum na Grande Lisboa e, dada a inespecificidade do quadro clínico, todas as crianças febris ou doentes com estadia recente num país endémico devem ser rastreadas para esta entidade

Fish hosts of the freshwater mussel Unio foucauldianus Pallary, 1936

The life cycle of Unio foucauldianus Pallary, 1936, a critically endangered freshwater mussel species (Bivalvia: Unionida), includes a parasitic phase using fish as hosts. Therefore, to develop more efficient conservation strategies it is essential to know which are the suitable fish hosts of U. foucauldianus. In this study, two approaches were used to assess the fish hosts of U. foucauldianus: the determination of infestation rates of fishes under natural conditions through monthly sampling (from January to June) in the Laabid River (Oum Rbia basin) and the N'Fis River (Tensift basin), and artificial infestation in laboratory trials using fish species from both rivers. The natural infestation of fish was detected from February to June, with a peak in May. Fully metamorphosed juveniles were only detected in native fish species, i.e. Luciobarbus ksibi (Boulenger, 1905), Carasobarbus fritschii (Gunther, 1874), Luciobarbus zayanensis Doadrio, Casal-lopez & Yahyaoui, 2016, Labeobarbus maroccanus (Gunther, 1874), and Luciobarbus magniatlantis (Pellegrin, 1919). The two non-native fish species used do not function as effective hosts. Given the increasing human pressure on native fish species in the Mediterranean biodiversity hotspot, including the increased number of non-native fish introductions, urgent conservation measures are discussed for this and other freshwater mussel species.The authors would like to express their thanks to the High Commission for Water and Forests (HCEFLCD) for granting permission to use electrofishing in the Moroccan basins. This study was conducted within the scope of the project ‘Biodiversity and conservation of the critically endangered freshwater mussels in Morocco: ecogeographic, genetic and physiological information’, funded by the Mohamed Bin Zayed Species Conservation Fund (ref. 15256799), and the project ‘Breeding the most endangered bivalve on Earth: argaritifera marocana’, funded by the IUCN SOS (Save our Species) fund (ref. 2015B‐015)