Reversible Transport of Interacting Brownian Ratchets

The transport of interacting Brownian particles in a periodic asymmetric (ratchet) substrate is studied numerically. In a zero-temperature regime, the system behaves as a reversible step motor, undergoing multiple sign reversals of the particle current as any of the following parameters are varied: the pinning potential parameters, the particle occupation number, and the excitation amplitude. The reversals are induced by successive changes in the symmetry of the effective ratchet potential produced by the substrate and the fraction of particles which are effectively pinned. At high temperatures and low frequencies, thermal noise assists delocalization of the pinned particles, rendering the system to recover net motion along the gentler direction of the substrate potential. The joint effect of high temperature and high frequency, on the other hand, induces an additional current inversion, this time favoring motion along the direction where the ratchet potential is steeper. The dependence of these properties on the ratchet parameters and particle density is analyzed in detail.Comment: 8 pages, 10 figure

Nanostructured Polypyrrole Powder: A Structural and Morphological Characterization

Polypyrrole (PPY) powder was chemically synthesized using ferric chloride (FeCl3) and characterized by X-ray diffraction (XRD), Le Bail Method, Fourier Transform Infrared Spectrometry (FTIR), and Scanning Electron Microscopy (SEM). XRD pattern showed a broad scattering of a semicrystalline structure composed of main broad peaks centered at 2θ = 11.4°, 22.1°, and 43.3°. Crystallinity percentage was estimated by the ratio between the sums of the peak areas to the area of amorphous broad halo due to the amorphous phase and showed that PPY has around 20 (1)%. FTIR analysis allowed assigning characteristic absorption bands in the structure of PPY. SEM showed micrometric particles of varying sizes with morphologies similar to cauliflower. Crystal data (monoclinic, space group P 21/c, a=7.1499 (2) Å, b=13.9470 (2) Å, c=17.3316 (2) Å, α=90 Å, β=61.5640 (2) Å and γ=90 Å) were obtained using the FullProf package program under the conditions of the method proposed by Le Bail. Molecular relaxation was performed using the density functional theory (DFT) and suggests that tetramer polymer chains are arranged along the “c” direction. Average crystallite size was found in the range of 20 (1) Å. A value of 9.33 × 10−9 S/cm was found for PPY conductivity

Confiabilidade da informação sobre antecedente de varicela em crianças pré-escolares

OBJECTIVE: To verify how reliable is the information provided by parents about the history of varicella in their children. METHODS: 204 parents of previously healthy children attending two municipal day-care centers of São Paulo city were interviewed between August 2003 and September 2005. A standardized form was filled out with information regarding age, sex, history of varicella and other diseases, drug use and antecedent of immunization, After medical history, physical examination and checking of immunization records, 5 ml of blood were collected for ELISA (in house) varicella test. Exclusion criteria were: age less than 1 year or more than 60 months, previous immunization against chickenpox, presence of co-morbidities or recent use of immunosuppressive drugs. Data were filed in a data bank using the Excel 2003 Microsoft Office Program and stored in a PC computer. The exact Fisher test was employed to calculate sensibility, specificity, positive and negative predictive values of history of varicella informed by children's parents. RESULTS: The age of the children varied from 12 to 54 months (median, 26 months; 49 (24%) children had positive history of varicella, 155 (76%) a negative or doubtful history. The predictive positive and negative values of the information were 90% and 93%, respectively (p = 0.0001). CONCLUSIONS: The degree of reliability of information about history of varicella informed by parents of children attending day care centers was high and useful to establish recommendations on varicella blocking immunization in day-care centers.OBJETIVOS: Verificar o grau de confiabilidade da informação fornecida pelos pais de crianças atendidas em creches sobre o antecedente de varicela. MÉTODOS: Os pais de 204 crianças previamente saudáveis matriculadas em duas creches da cidade de São Paulo foram entrevistados entre Agosto de 2003 e Setembro de 2005 para preenchimento de um questionário padronizado com informações sobre idade, sexo, antecedente de varicela e outras doenças, uso de medicamentos e história vacina. Após anamnese, exame físico e verificação da carteira de vacinação, foram colhidos 5 ml de sangue para realização do teste ELISA (in house) para varicela. Os critérios de exclusão foram: idade < 1 ano ou acima de 60 meses, vacinação prévia contra varicela, presença de comorbidades e uso recente de imunossupressores. Os dados foram registrados num banco de dados do programa Excel 2003 Microsoft Office e armazenados em microcomputador. Utilizou-se o teste exato de Fisher para calcular a sensibilidade, especificidade e valores preditivo positivo e negativo das informações fornecidas pelos pais sobre o antecedente de varicela das crianças. RESULTADOS: A idade das crianças variou entre 12 e 54 meses (mediana, 26 meses); 49 crianças (24%) tinham antecedente positivo para varicela e 155 (76%) negativo ou duvidoso. Os valores preditivo positivo e negativo da informação foram de 90% e 93%, respectivamente (p = 0.0001). CONCLUSÕES: O grau de confiabilidade das informações sobre varicela informadas pelos pais de crianças atendidas em creches foi elevado e útil para estabelecer recomendações para vacinação de bloqueio de surtos de varicela em creches

Construção e Validação de Escala de Qualidade de Ensino e Serviços: Um Estudo com Alunos de Cursos de Graduação em Administração de Empresas.

La creciente expansión de la enseñanza superior brasileña observada en los últimos años, principalmente en lo que se refiere a la participación de la iniciativa privada, ha exigido mayor atención a la calidad de los servicios ofrecidos por las Instituciones de Enseñanza Superior (IES). El objetivo de este trabajo es la construcción y validación de una escala para la evaluación de las percepciones de discentes sobre la calidad del curso de graduación en Administración de Empresas, el mayor del país en número de alumnos, mediante una muestra de conveniencia de 479 alumnos de esos cursos en cinco IES en la ciudad de São Paulo. Los datos fueron analizados según el Modelado de Ecuaciones Estructurales, y el constructo de segundo orden (QUALI – calidad) por el modelo de mensuración PLS-PM. Los resultados obtenidos indicaron la validación de la escala, ya que ella cuantifica lo que se propone, y los testes estadísticos o indicadores de la cualidad del modelo muestran que la escala es confiable y puede ser usada para valorar otras IES.The growing expansion of Brazilian higher education observed in recent years, particularly with regard to the participation of the private sector, has demanded more attention to the quality of services offered by Higher Education Institutions (IES). The aim of this work is the construction and validation of a scale for the evaluation of students’ perceptions about the quality of the undergraduate degree in business administration, which is the country’s largest number of students, using a convenience sample of 479 students in Business Administration in five IES in São Paulo city. The data were analyzed according to Structural Equation Modeling, with a second-order construct (QUALI - quality) according to the measurement model PLS-PM. The results obtained showed the validation of the scale, since it measures what it purports to measure, and statistical tests or quality indicators of the model show that the scale is reliable and can be used to measure other IES.A crescente expansão do ensino superior brasileiro observada nos últimos anos, principalmente no que se refere à participação da iniciativa privada, tem exigido maior atenção à qualidade dos serviços oferecidos pelas Instituições de Ensino Superior (IES). O objetivo deste trabalho é a construção e validação de uma escala para a avaliação das percepções de discentes sobre a qualidade do curso de graduação em Administração de Empresas, o maior do país em número de alunos, por meio de uma amostra de conveniência de 479 alunos desse curso em cinco IES na cidade de São Paulo. Os dados foram analisados segundo a Modelagem de Equações Estruturais, e o constructo de segunda ordem (QUALI – qualidade) pelo modelo de mensuração PLS-PM. Os resultados obtidos indicaram a validação da escala, já que ela mensura o que se propõe, e os testes estatísticos ou indicadores da qualidade do modelo mostram que a escala é confiável e pode ser usada para mensurar ou tras IES

Seroprevalence of bovine leptospirosis in reproductive-age female bovines in the state of São Paulo, Brazil

O presente estudo teve como objetivo determinar a soroprevalência da leptospirose bovina em fêmeas em idade reprodutiva do Estado de São Paulo, estratificado em sete regiões produtoras. Foram utilizados o delineamento estatístico, as amostras sorológicas e as informações contidas nos questionários empregados no Programa Nacional de Controle e Erradicação da Brucelose e Tuberculose (PNCETB), instituído pelo Ministério da Agricultura, Pecuária e Abastecimento, considerando-se a utilização de fêmeas bovinas com idade '> OU =' a 24 meses (excluindo-se machos), diferentes tipos de produção, práticas de manejo, finalidades de reprodução, tamanho dos rebanhos e sistema de comercialização. Realizou-se a Soroaglutinação Microscópica (SAM) em 8.216 amostras sorológicas de animais provenientes de 1.021 propriedades. De acordo com os resultados obtidos, a infecção por Leptospira spp. ocorre em todo o Estado de São Paulo, com soroprevalência de 49,4% (IC 95% = 44,4%-54,4%) nas fêmeas bovinas em idade reprodutiva e em 718 (71,3%; IC 95% = 68,5%-74%) das propriedades analisadas. O sorovar Hardjo (46%) e sua associação com o sorovar Wolffi (21%) foram prevalentes entre o total de animais sororeagentes, seguidos pelos sorovares Shermani (8,9%), Autumnalis (4,4%) e Grippotyphosa (3,9%). Leptospira spp. está distribuída por todo estado e independe do tipo de exploração, manejo e das práticas de reprodução adotadas nos rebanhosThe objective of the present study was to determine the seroprevalence of bovine leptopirosis in São Paulo State, stratified in seven cattle production regions. It was based on the statistic delineation, serological samples and responses to the survey employed in the National Program for Control and Eradication of Brucelosis and Tuberculosis established by Ministry of Agriculture (2001). From the herds selected, serological analysis was only conducted on the cows '> OU =' 24 months old (excluding the males). The study took into consideration the herd size, the type of productive exploration, the reproductive handling, bovine practices and the commercialization system. The microscopic agglutination test (MAT) was applied on 8,216 serum samples from 1,021 different farms. The results showed that leptospirose infection occurs all over the seven regions of São Paulo State with 49.4% (CI 95% = 44.4-54.4%) animal seroprevalence and in 718 (71.3%; CI 95% = 68.5-74.0%) of the herds analyzed. Hardjo (46%) was the prevalent serovar for all the animals examined, followed by the Hardjo/Wolffi association (21%), Shermani (8.9%), Autumnalis (4.4%) and Grippotyphosa (3.9%). Leptospira spp. is present in all regions of the State of São Paulo and its occurrence is independent of the handling conditions and reproductive practices adopted in the herd

Performance of straightbred and crossbred Tabapuã cattle on brachiaria pasture in Bahia state

Comparou-se o desempenho de bovinos de diferentes grupos genéticos quanto a algumas características produtivas da desmama até o abate. Os dados são referentes a 827 bovinos machos oriundos do cruzamento de vacas Tabapuã com touros Tabapuã (TAB), Red Angus (REDTAB), Santa Gertrudis (STATAB), e das fêmeas TabapuãxRed Angus com touros Santa Gertrudis (STAREDTAB) (nascidos entre 1999 e 2001 e criados em pastagens de braquiária, no Estado da Bahia). Foram analisados o peso à desmama ajustado aos 205 dias (PD205), o peso ao abate (PA), o ganho médio diário da desmama ao abate (GMD) e a idade ao abate (IA). O grupo contemporâneo (GC), o grupo genético (GG) e a interação entre GC e GG influenciaram as características avaliadas (P0,05); entretanto, apresentaram médias inferiores às do grupo REDTAB e TAB. Em condição de ambiente mais favorável, o REDTAB pode ser mais precoce, obtendo maior GMD e PA com menor IA, sendo superior ao Tabapuã e aos cruzados da segunda geração (F2). Os cruzados F2 não demonstraram vantagem em relação ao cruzado F1 e à raça pura.The aim of this study was to compare the different genetic groups performances from weaning to slaughter. The d ata are referred to 827 male calves of Tabapuã c ows crossed with Red Angus (REDTAB) and Santa Gertrudis sires and from Tabapuã x Red Angus cows crossed with Santa Gertrudis sires , born from 1999 to 2001 and raised in Brachiaria pastures, in Bahia state , Brazil. The w eaning weight was adjusted to 205 day s (WW205), slaughter weight (SW ), average daily gain from weaning to slaughter (ADG) and age slaughter (AG), were analyzed. The contemporary group (CG), genetic group (GG) and the interaction between CG and GG influenced the parameters (P0.05), however, ha d lower averages than REDTAB and TAB. In more favorable environment al conditions, REDTAB s hould get higher ADG and SW and lower AG , being superior than Tabapuã and to the second generation's crossbr ed (F2). The crossbr ed F2 show ed no advantage over F1crossbr ed and straightbred

Effect of drying temperature on the yield and phytochemical quality of the essential oil of pepper rosemary (Lippia origanoides Kunth) and of clove basil (Ocimum gratissimum L.) / Efeito da temperatura de secagem no rendimento e na qualidade fitoquímica do óleo essencial de alecrim-pimenta (Lippia origanoides Kunth) e de alfavaca (Ocimum gratissimum L.)

Among medicinal species, Lippia origanoides Kunth and Ocimum gratissimum L. stand out for its recognized therapeutic value associated with the medicinal properties of their essential oils. Drying is a critical point in post-harvest processing of medicinal plants for the conservation of bioactive compounds. This work aimed to evaluate the effect of drying temperature on the essential oil’s yield and phytochemical quality extracted from leaves of O. gratissimum and L. origanoides. The medicinal species were grown in an organic system and their leaves were harvest and immediately dried at 40, 50 and 60 °C. The essential oils were extracted from the leaves by hydrodistillation in Clevenger apparatus. There was detected a difference (P &lt;0.01) in the essential oil yield of O. gratissimum with the increase in the drying temperature, being 1.35% (40 °C), 0.83% (50 °C) and 0.45% (60 °C) ). In L. origanoides there was detected a difference (P &lt;0.01) in the essential oil yield only between 40 °C (3.4%) and 60 °C (2.84%). The increase of drying temperature reduced the levels of the major constituents of O. gratissimum (eugenol, germacrene D and caryophyllene oxide), but did not change the levels of the major constituents of L. origanoides (thymol, trans-caryophyllene and para-cymene). Considering that the increase of the drying temperature promote a reduction in the essential oil yield of both medicinal species and also in the major constituents concentration in O. gratisssimum, it is essential to select the correct drying temperature to guarantee the best yield and the phytochemical quality of the essential oil to ensure therapeutic efficacy. Here, we conclude that the best drying temperature to the essential oil’s yield and phytochemical quality is 40 °C for O. gratissimum and 40 or 50 °C for L. origanoides

Effect of drying temperature on yield and phytochemical quality of essential oil extracted from Mikania laevigata (Guaco) leaves / Efeito da temperatura de secagem sobre o rendimento e qualidade fitoquímica de óleo essencial extraído de folhas de Mikania laevigata (Guaco)

Mikania laevigata Sch. Bip. ex Baker, Asteraceae, commonly known as the guaco, is medicinal species native to Brazil. Among the critical points of post-harvest processing of medicinal species, the drying temperature must be considered, because its can interfere in the yield and phytochemical quality of plant material, and, consequently, in the therapeutic action. The effect of the drying temperature was evaluated on the yield and phytochemical quality of the essential oil extracted from M. laevigata leaves. The cultivation was carried out in an organic system and using the select genotype (Cenargen) for this region. The leaves were harvested and immediately submitted to drying process at 40, 50 and 60 °C. The essential oils were extracted by hydrodistillation in Clevenger apparatus and the chemical constituents was evaluated using gas chromatography coupled to the mass spectrophotometer (CG-MS). There was a reduction in the essential oil yield (p &lt;0.05) with increasing drying temperature. However, at 60 ºC there was a higher concentration of coumarin to which the bronchodilator and expectorant action is attributed. Therefore, we recommended dry the M. laevigata leaves at 60 ºC to obtain the highest coumarin content and guarantee the bronchodilator and expectorant therapeutic effect