Resource partitioning among African savanna herbivores in North Cameroon: the importance of diet composition, food quality and body mass

The relationship between herbivore diet quality, and diet composition (the range of food plants consumed) and body mass on resource partitioning of herbivores remains the subject of an ongoing scientific debate. In this study we investigated the importance of diet composition and diet quality on resource partitioning among eight species of savanna herbivore in north Cameroon, with different body mass. Dung samples of four to seven wild herbivore and one domesticated species were collected in the field during the dry and wet period. Diet composition was based on microhistological examination of herbivore droppings, epidermis fragments were identified to genus or family level. In addition, the quality of the faecal droppings was determined in terms of phosphorus, nitrogen and fibre concentrations. The results showed that there was no significant correlation between body mass and (differences in) diet composition for wet and dry season. When all species are considered, only significant relationships are found by the Spearman rank correlation analyses during the wet season between body mass and phosphorus and nitrogen, but this relationship did not exist during the dry season. When the analyses focuses on ruminants only (thus leaving out hippo), none of the relationships between body mass and diet quality was significant in either season. During the dry season the proportion of graminoids ranged between 10% (small unidentified herbivore species) to 90% (hippopotamus), during the wet season this proportion ranged from 60% (zebu) to 90% (hippopotamus). All species but zebu had more graminoids in their dung during wet season compared with dry season. However all species but hartebeest had more graminoids old stems in their dung during the dry season, compared with the wet season. The niche breadth for food categories consumed by kob (0.300), hippo (0.090), hartebeest (0.350), roan (0.510) and zebu (0.300) was much greater in the dry season than in the wet season for kob (0.120), hippo (0.020), hartebeest (0.190), roan (0.090) and zebu (0.200). When looking at grass taxa consumed, the niche breadth of kob (0.220), hartebeest (0.140), and roan (0.250) was also greater in the dry season when compared with the wet season for kob (0.050), hartebeest (0.120) and roan (0.120). The opposite was found for zebu and hippo. Comparison of the species’ diet compositions with randomized data showed that dietary overlap between different herbivore species was much higher than what would be expected on the basis of chance, demonstrating surprisingly limited niche separation between species. This offers potential for competition, but it is more likely that the high niche overlap indicates absence of competition, due to low herbivore densities and abundant food resources, permitting species to share non-limiting resources. With increasing herbivore densities and subsequent increasing scarcity of resources, the relationship between diet quality and body mass in combination with increased niche separation is expected to become more visibl

Automatic detection of service initiation signals used in bars

Loth S, Huth K, de Ruiter J. Automatic detection of service initiation signals used in bars. Frontiers in Psychology. 2013;4: 557.Recognizing the intention of others is important in all social interactions, especially in the service domain. Enabling a bartending robot to serve customers is particularly challenging as the system has to recognize the social signals produced by customers and respond appropriately. Detecting whether a customer would like to order is essential for the service encounter to succeed. This detection is particularly challenging in a noisy environment with multiple customers. Thus, a bartending robot has to be able to distinguish between customers intending to order, chatting with friends or just passing by. In order to study which signals customers use to initiate a service interaction in a bar, we recorded real-life customer-staff interactions in several German bars. These recordings were used to generate initial hypotheses about the signals customers produce when bidding for the attention of bar staff. Two experiments using snapshots and short video sequences then tested the validity of these hypothesized candidate signals. The results revealed that bar staff responded to a set of two non-verbal signals: first, customers position themselves directly at the bar counter and, secondly, they look at a member of staff. Both signals were necessary and, when occurring together, sufficient. The participants also showed a strong agreement about when these cues occurred in the videos. Finally, a signal detection analysis revealed that ignoring a potential order is deemed worse than erroneously inviting customers to order. We conclude that (a) these two easily recognizable actions are sufficient for recognizing the intention of customers to initiate a service interaction, but other actions such as gestures and speech were not necessary, and (b) the use of reaction time experiments using natural materials is feasible and provides ecologically valid results

Band structure related wave function symmetry of amphoteric Si dopants in GaAs

Autocompensated Si-doped GaAs is studied with cross-sectional scanning tunneling spectroscopy (X-STS). The local electronic contrasts of substitutional Si(Ga) donors and Si(As) acceptors under the (110) cleavage plane are imaged with high resolution. Si(Ga) donor atoms exhibit radially symmetric contrasts. Si(As) acceptors have anisotropic features. The anisotropic acceptor contrasts are traced back to a tunnel process at the valence band edge. They reflect the probability density distribution of the localized acceptor hole state.Comment: 10 pages, 3 figure

Editorial: Understanding Social Signals: How Do We Recognize the Intentions of Others?

Loth S, de Ruiter J. Editorial: Understanding Social Signals: How Do We Recognize the Intentions of Others? Frontiers in Psychology. 2016;7: 281

On the Connection of Anisotropic Conductivity to Tip Induced Space Charge Layers in Scanning Tunneling Spectroscopy of p-doped GaAs

The electronic properties of shallow acceptors in p-doped GaAs{110} are investigated with scanning tunneling microscopy at low temperature. Shallow acceptors are known to exhibit distinct triangular contrasts in STM images for certain bias voltages. Spatially resolved I(V)-spectroscopy is performed to identify their energetic origin and behavior. A crucial parameter - the STM tip's work function - is determined experimentally. The voltage dependent potential configuration and band bending situation is derived. Ways to validate the calculations with the experiment are discussed. Differential conductivity maps reveal that the triangular contrasts are only observed with a depletion layer present under the STM tip. The tunnel process leading to the anisotropic contrasts calls for electrons to tunnel through vacuum gap and a finite region in the semiconductor.Comment: 11 pages, 8 figure

Saving biodiversity by fighting desertification in West and Central Africa

Environment and Developmen

Germination strategy of the East African savanna tree Acacia tortilis

Germination of Acacia tortilis seeds strongly depends on micro-site conditions. In Lake Manyara National Park, Tanzania, Acacia tortilis occurs abundantly in recently abandoned arable fields and in elephant-mediated gaps in acacia woodland, but does not regenerate in grass swards or beneath canopies. We examined the germination of Acacia tortilis using field and laboratory experiments. Seeds placed on top of the soil rarely germinated, while seeds covered with elephant dung or buried under the soil surface had a germination success between 23¿43%. On bare soil 39% of both the dung-covered and buried seeds germinated, in perennial grass swards 24¿43%, and under tree canopies 10¿24% respectively. In laboratory experiments, seed water absorption correlated positively with temperature up to 41 °C, while subsequent germination was optimal at lower (21¿23 °C) temperatures. Seeds that had absorbed water lost their viability when kept above 35.5 °C. The absence of light did not significantly influence germination success. Acacia tortilis does not actively disperse its seeds, but regeneration outside tree canopies was substantial. The regeneration potential thus strongly depends on the physiognomy of the vegetatio

Efeito da dose resposta de Paracoccidioides brasiliensis no modelo experimental de artrite

A paracoccidioidomicose (PCM) é causada pelo fungo dimórfico Paracoccidioides brasiliensis (Pb) e corresponde à micose sistêmica de maior prevalência na América Latina. O objetivo do presente trabalho foi avaliar a dose resposta de leveduras do fungo para padronização do modelo experimental de artrite séptica. Os experimentos foram realizados com grupos de 14 ratos que receberam doses de 103, 104 ou 105 células de P. brasiliensis (Pb18). Os fungos foram injetados em 50 µL de solução salina em tampão fosfatado (PBS) diretamente na articulação do joelho dos animais. Os seguintes parâmetros foram analisados neste trabalho: a formação de edema nos joelhos infundidos com as células das leveduras e alterações radiológicas, anatopalógicas além de titulação de anticorpos por Elisa. Após 15 dias de infecção, os sinais de inflamação foram evidentes. Aos 45 dias, algumas características de dano e necrose foram observadas na cartilagem articular. A disseminação sistêmica do fungo foi observada em 11% dos animais inoculados, concluiu-se que o modelo experimental é capaz de mimetizar a PCM articular em humanos e que a dose de 105 leveduras representa a dose padrão para o desenvolvimento do modelo.Paracoccidioidomycosis (PCM) is caused by the dimorphic fungus Paracoccidioides brasiliensis (Pb) and corresponds to prevalent systemic mycosis in Latin America. The aim of the present work was to evaluate the dose response effect of the fungal yeast phase for the standardization of an experimental model of septic arthritis. The experiments were performed with groups of 14 rats that received doses of 103, 104 or 105 P. brasiliensis (Pb18) cells. The fungi were injected in 50 µL of phosphate-buffered saline (PBS) directly into the knee joints of the animals. The following parameters were analyzed in this work: the formation of swelling in knees infused with yeast cells and the radiological and anatomopathological alterations, besides antibody titer by ELISA. After 15 days of infection, signs of inflammation were evident. At 45 days, some features of damage and necrosis were observed in the articular cartilage. The systemic dissemination of the fungus was observed in 11% of the inoculated animals, and it was concluded that the experimental model is able to mimic articular PCM in humans and that the dose of 105 yeast cells can be used as standard in this model

Análise do humor, qualidade de vida e fadiga de crianças e adolescentes hospitalizados para realização de transplante de células-tronco hematopoéticas/Analysis of humor, quality of life and fatigue of children and adolescents hospitalized for hematopoetic stem cell transplantation

Introdução: O transplante de células-tronco hematopoéticas (TCTH) é um tratamento que exige um longo período de hospitalização e pode impactar negativamente o desenvolvimento neuropsicomotor e o desempenho ocupacional. Objetivo: O estudo teve o objetivo analisar a fadiga, o humor e a qualidade de vida de crianças e adolescentes hospitalizados para o TCTH. Métodos: Pesquisa descritiva, quantitativa, longitudinal, realizada no Serviço de Transplante de Medula Óssea de um hospital universitário, a partir de um questionário sociodemográfico, a Escala de Faces de Humor, o questionário “Qualidade de Vida Pediátrica” e “Qualidade de Vida Pediátrica - Escala Multidimensional do Cansaço”, aplicado em três momentos diferentes. Resultados: Na amostra de 12 participantes, 7 eram do sexo masculino, a média de idade de 8,8 anos e o diagnóstico predominante foi Anemia de Fanconi. O período médio de internação foi de 37,2 dias. Houve declínio significativo do humor e da qualidade de vida no período pós-TCTH imediato, no qual também se observou aumento da intensidade da fadiga. A análise estatística mostrou significância na correlação entre as variáveis humor e sexo, sendo que o sexo masculino apresentou humor mais feliz no momento da internação. As variáveis fadiga e idade também demonstraram significância, sendo que os participantes de maior idade relataram maior fadiga. Conclusão: Destaca-se a importância de observar as fases do TCTH em que se encontra o paciente, para propor intervenções e ações terapêuticas ocupacionais condizentes com a necessidade, disponibilidade e disposição do paciente, tendo em vista seu bem-estar e qualidade de vida.Palavras chaves: Criança hospitalizada. Humor. Qualidade de vida. Fadiga. Transplante de Células-Tronco Hematopoéticas AbstractIntroduction: Hematopoietic stem cell transplantation (HSCT) is a treatment that requires a long period of hospitalization and can negatively impact neuropsychomotor development and occupational performance. Objective: The study aimed to analyze the fatigue, mood and quality of life of children and adolescents hospitalized for HSCT. Methods: Descriptive, quantitative, longitudinal research, carried out at the Bone Marrow Transplant Service of a university hospital, using a sociodemographic questionnaire, the Faces of Humor Scale, the “Pediatric Quality of Life” and “Pediatric Quality of Life” questionnaire - Multidimensional Scale of Tiredness”, applied in three different moments. Results: In the sample of 12 participants, 7 were male, with a mean age of 8.8 years and the predominant diagnosis was Fanconi Anemia. The average hospital stay was 37.2 days. There was a significant decline in mood and quality of life in the immediate post-HSCT period, in which there was also an increase in the intensity of fatigue. The statistical analysis showed significance in the correlation between the variables of mood and sex, with the male gender having a happier mood at the time of hospitalization. The variables fatigue and age also showed significance, with older participants reporting greater fatigue. Conclusion: The importance of observing the stages of the HSCT in which the patient is is highlighted, in order to propose therapeutic interventions and actions consistent with the patient's availability and disposition, in view of his well-being and quality of life.Keywords: Hospitalized child. Humor. Quality of life. Fatigue. Hematopoietic stem cell transplantation. ResumenIntroducción: El trasplante de células madre hematopoyéticas (TCMH) es un tratamiento que requiere un largo período de hospitalización y puede impactar negativamente el desarrollo neuropsicomotor y el desempeño ocupacional. Objetivo: El estudio tuvo como objetivo analizar la fatiga, el estado de ánimo y la calidad de vida de niños y adolescentes hospitalizados por TCMH. Métodos: Investigación descriptiva, cuantitativa, longitudinal, realizada en el Servicio de Trasplante de Médula Ósea de un hospital universitario, utilizando un cuestionario sociodemográfico, la Escala Caras de Humor, el cuestionario “Calidad de Vida Pediátrica” y “Calidad de Vida Pediátrica” - Multidimensional Escala de cansancio ”, aplicada en tres momentos diferentes. Resultados: En la muestra de 12 participantes, 7 eran varones, con una edad media de 8,8 años y el diagnóstico predominante fue Anemia de Fanconi. La estancia hospitalaria media fue de 37,2 días. Hubo una disminución significativa en el estado de ánimo y la calidad de vida en el período inmediatamente posterior al TCMH, en el que también hubo un aumento en la intensidad de la fatiga. El análisis estadístico mostró significancia en la correlación entre las variables estado de ánimo y sexo, teniendo el género masculino un estado de ánimo más feliz al momento de la hospitalización. Las variables fatiga y edad también demostraron importancia, y los participantes mayores informaron una mayor fatiga. Conclusión: Se destaca la importancia de observar las etapas del TCMH en las que se encuentra el paciente, para proponer intervenciones y acciones terapéuticas acordes con la disponibilidad y disposición del paciente, en vista de su bienestar y calidad de vida.Palabrasclave: Niño hospitalizado. Humor. Calidad de vida. Fatiga. Trasplante de células madre hematopoyéticas

Economic factors influencing zoonotic disease dynamics: demand for poultry meat and seasonal transmission of avian influenza in Vietnam

While climate is often presented as a key factor influencing the seasonality of diseases, the importance of anthropogenic factors is less commonly evaluated. Using a combination of methods-wavelet analysis, economic analysis, statistical and disease transmission modelling-we aimed to explore the influence of climatic and economic factors on the seasonality of H5N1 Highly Pathogenic Avian Influenza in the domestic poultry population of Vietnam. We found that while climatic variables are associated with seasonal variation in the incidence of avian influenza outbreaks in the North of the country, this is not the case in the Centre and the South. In contrast, temporal patterns of H5N1 incidence are similar across these 3 regions: periods of high H5N1 incidence coincide with Lunar New Year festival, occurring in January-February, in the 3 climatic regions for 5 out of the 8 study years. Yet, daily poultry meat consumption drastically increases during Lunar New Year festival throughout the country. To meet this rise in demand, poultry production and trade are expected to peak around the festival period, promoting viral spread, which we demonstrated using a stochastic disease transmission model. This study illustrates the way in which economic factors may influence the dynamics of livestock pathogens