1,139 research outputs found
Two new Morganella species from the Brazilian Amazon rainforest
Two new Morganella species, M. albostipitata and M. rimosa were found during studies of gasteroid fungi in the Brazilian Amazon rainforest, Adolpho Ducke Forest Reserve, Amazonas State, Brazil. The new taxa are described, and illustrated with photographs and line drawings, and taxonomical comments are made
Characterization of the THz quasi-optical channel for the measurement of the power radiated by photoconductive antennas
In this paper a rigorous electromagnetic characterization of the setup for measuring the THz power radiated by pulsed photoconductive antenna is discussed. Such characterization is expressed in terms of efficiencies which quantify how much power is lost in the coupling between the various components involved in the measurement setup. The conducted analysis highlights how such efficiencies affect the energy spectrum of the measured pulsed signal. Measurement results with two different detectors will be shown during the conference and will be compared against the power estimation obtained by a recently developed equivalent circuit model for photoconductive antennas. The proposed electromagnetic modeling allows us to effectively improve the design of THz time domain systems
Effect of Biodiversity Changes in Disease Risk: Exploring Disease Emergence in a Plant-Virus System
The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species
Satisfaction with Life Scale among adolescents and young adults in Portugal: extending evidence of construct validity
The paper presents three empirical studies designed to extend the test of the
construct validity of the Satisfaction With Life Scale (SWLS) among Portuguese students.
In the first study, the responses of 461 elementary and secondary education students were
submitted to a principal component analysis. A solution of one single factor was chosen, accounting for 55.7 % of the total variance, with Cronbach alpha coefficient and inter-item correlation above .70 and .20, respectively. The second study used a sample of 317
undergraduate students and registered a similar factor solution for SWLS (/pq = 0.99), which accounted for 65.6 % of the total variance (Cronbach alpha .89 and inter-item correlation above .20). A test–retest analysis registered coefficients of .70 (T2) and .77 (T3) and no significant statistically differences between T2, T3 and T1. The third study used a sample of 107 foster care youths from elementary and secondary education. Confirmatory factor analysis results indicate adequate fit indexes for the one-factor solution (v2/df = 2.70, GFI = .96, CFI = .96), which showed convergent validity, reliability and homogeneity. In conclusion, there is psychometric evidence for the one-factor structure of the SWLS in Portugal.FCTCOMPET
Noncommutative cosmological models coupled to a perfect fluid and a cosmological constant
In this work we carry out a noncommutative analysis of several
Friedmann-Robert-Walker models, coupled to different types of perfect fluids
and in the presence of a cosmological constant. The classical field equations
are modified, by the introduction of a shift operator, in order to introduce
noncommutativity in these models. We notice that the noncommutative versions of
these models show several relevant differences with respect to the
correspondent commutative ones.Comment: 27 pages. 7 figures. JHEP style.arXiv admin note: substantial text
overlap with arXiv:1104.481
Qualidade de alface crespa cultivada em sistema orgânico, convencional e hidropônico.
O objetivo deste trabalho foi avaliar a qualidade da alface do grupo crespa, cv. Vera, em sistemas de cultivo orgânico, convencional e hidropônico em Rio Branco-AC. O experimento foi conduzido em julho de 2009. As amostras dos sistemas, convencional e hidropônico (3 marcas comerciais), foram escolhidas aleatoriamente nos supermercados do município de Rio Branco, no mesmo dia de coleta da alface produzida em sistema orgânico. A alface orgânica, produzida na área experimental do Setor de Agricultura Ecológica da Universidade Federal do Acre (UFAC), em Rio Branco, foi cultivada em estufa, sob plantio direto utilizando folhas de bambu como cobertura do solo, e adubada com composto orgânico (17 t ha-1 em base seca). O delineamento utilizado foi o inteiramente casualizado, com cinco tratamentos e quatro repetições compostas por três plantas. As amostras foram lavadas, cortadas e processadas com folha e caule, para obter o suco. Logo após foram determinados os teores de sólidos solúveis e a concentração de nitrato e ácido ascórbico. As três marcas de alface hidropônica apresentaram maior teor de nitrato e menor concentração de sólidos solúveis e ácidos ascórbico, enquanto a alface orgânica apresentou qualidade superior, com baixa concentração de nitrato e maior teor de ácido ascórbico
Antimicrobial activity of Agave sisalana
This study was carried out to evaluate the antimicrobial activity of extracts of the leaves and leaf waste discarded in the process of obtaining the hard fibers of Agave sisalana. The antimicrobial activity was determined by the paper disk diffusion method using Gram-positive and Gram-negative bacteria (nonresistant and resistant to antibiotics) and a fungus. The hydroalcoholic extract obtained from leaves and from sisal waste showed significant inhibition of Candida albicans, on the other hand, it was inactive against three strains of Staphylococcus aureus, two strains of Escherichia coli, a strain ofMicrococcus luteus, Bacillus cereus, Pseudomonas aeruginosa and Salmonella choleraesuis. The methanol extract of leaves showed weaker reduction in the inhibitory action of C. albicans when compared with the above extracts, and it was also inert against the other microorganisms tested
Consensus Paper: Radiological Biomarkers of Cerebellar Diseases
Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine
Scleroderma minutisporum, a new earthball from the Amazon rainforest
A new species of earthball, Scleroderma minutisporum was found in the Brazilian Amazon. The specimen, collected in Adolpho Ducke Forest Reserve, Amazonas State, Brazil is named because of the small size of its basidiospores. A description, photographs, and taxonomical comments are provided, and the holotype is compared with related taxa
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