2,037 research outputs found
Universality in short-range Ising spin glasses
The role of the distribution of coupling constants on the critical exponents
of the short-range Ising spin-glass model is investigated via real space
renormalization group. A saddle-point spin glass critical point characterized
by a fixed-point distribution is found in an appropriated parameter space. The
critical exponents and are directly estimated from the data of
the local Edwards-Anderson order parameters for the model defined on a diamond
hierarchical lattice of fractal dimension . Four distinct initial
distributions of coupling constants (Gaussian, bimodal, uniform and
exponential) are considered; the results clearly indicate a universal behavior.Comment: 11 pages, 4 figures, to published in Physica A 199
Short Range Ising Spin Glasses: a critical exponent study
The critical properties of short-range Ising spin-glass models, defined on a
diamond hierarchical lattice of graph fractal dimension , 3, and 4,
and scaling factor 2 are studied via a method based on the Migdal-Kadanoff
renormalization-group scheme. The order parameter critical exponent is
directly estimated from the data of the local Edwards- Anderson (EA) order
parameter, obtained through an exact recursion procedure. The scaling of the EA
order parameter, leading to estimates of the exponent of the correlation
length is also performed. Four distinct initial distributions of the quenched
coupling constants (Gaussian, bimodal, uniform and exponential) are considered.
Deviations from a universal behaviour are observed and analysed in the
framework of the renormalized flow in a two dimensional appropriate parameter
space.Comment: 9 pages, 01 figure (ps
Forced convection to laminar flow of liquid egg yolk in circular and annular ducts
The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses.(CNPq) National Council for Scientific and Technological Development(FAPESP) São Paulo Research Foundatio
Evidências neuroquímicas e comportamentais do efeito ansiogênico da deltametrina em ratos
Pyrethroid insecticides are extensively used for pest control around the house, flea prevention for pets, and plant sprays for the home and in agriculture. Deltamethrin (DTM) is a Type II pyrethroid insecticide used to control a variety of insects in agriculture and domestic environments. The present study investigated the possible anxiogenic effects of DTM (1, 3, and 10 mg/kg) in rats using behavioral and neurochemical methods. We assessed general locomotor activity and behavior in the elevated plus maze and open field test. Striatal and hippocampal neurotransmitter and metabolite levels were also measured. DTM (i) reduced locomotion and rearing frequency, (ii) slightly increased the duration of immobility, (iii) reduced the time engaged in social interaction, (iv) reduced the percentage of entries into and time spent on the open arms of the elevated plus maze, (v) reduced the number of center crossings in the elevated plus maze, (vi) Striatal and hippocampal neurotransmitter and metabolite levels were also measured. DTM (i) reduced locomotion and rearing frequency, (ii) slightly increased the duration of immobility, (iii) reduced the time engaged in social interaction, (iv) reduced the percentage of entries into and time spent on the open arms of the elevated plus maze, (v) reduced the number of center crossings in the elevated plus maze, (vi) increased striatal serotonin neurotransmitter and its metabolite, and (vii) did not alter motor coordination on the rotarod, grooming duration in the open field test, rectal temperature, or hippocampal neurotransmitter levels. These data suggest that DTM at the present doses and under these experimental conditions presented a similar profile to that of anxiogenic drugs, unrelated with the increased serotonin neurotransmission.Inseticidas piretróides são amplamente utilizados para controle de pragas, como na prevenção de pulgas em animais de estimação e sprays de plantas para a casa e na agricultura. Deltametrina (DTM) é um inseticida piretróide tipo II usado para controlar uma variedade de insetos na agricultura e ambientes domésticos. O presente estudo investigou os possíveis efeitos ansiogênicos de DTM (1, 3 e 10 mg/kg) em ratos, utilizando métodos comportamentais e neuroquímicos. Foi avaliada a atividade locomotora geral e comportamento no labirinto em cruz elevado e teste de campo aberto. Os níveis de neurotransmissores e metabólitos no estriado e hipocampo também foram mensurados. DTM (i) reduziu a locomoção e a frequência de levantar, (ii) aumentou da duração da imobilidade, (iii) reduziu o tempo de interação social, (iv) reduziu a percentagem de entradas e tempo gasto nos braços abertos do elevado labirinto em cruz, (v) reduziu o número de cruzamentos no centro do labirinto em cruz elevado, (vi) aumentou neurotransmissor serotonina e de seu metabólito estriatal, e (vii) não alterou a coordenação motora no rotarod, duração do grooming no teste de campo aberto, temperatura retal, ou níveis de neurotransmissores do hipocampo. Estes dados sugerem que DTM nas presentes doses e sob estas condições experimentais apresentaram um perfil semelhante ao de drogas ansiogénicas, não relacionados ao aumento da serotonina estriatal
Concentrações foliares do porta-enxerto limoeiro 'cravo' em função da adubação N, P, K, Ca e S
A determinação das concentrações foliares representa o estado nutricional das plantas, identifica deficiências e/ou excessos e avalia a necessidade de ajustar as adubações. Este trabalho objetivou determinar a melhor combinação de doses NPKCa e S que proporcione a concentração foliar responsável pela maior quantidade de matéria seca total das plantas de porta-enxerto limoeiro `Cravo', em um experimento fatorial fracionário (¹/25) 5(4), com 25 tratamentos, repartidos em cinco blocos de cinco tratamentos. As mudas do limoeiro `Cravo' (Citrus limonia Osb.) foram transplantadas para recipientes (3,8 dm³) com substrato comercial, em viveiro telado, quando atingiram 10 cm. Os tratamentos consistiram de combinações das seguintes doses (g por planta): N = 0,31; 0,62; 1,25; 2,5 e 5; K = 0,4; 0,62; 1,25; 2,5 e 5; P = 0,35; 1,0; 2,0; 3,0 e 4,0; e Ca = 3,5; 5,0; 6,0; 7,0 e 8,0. O P e o Ca foram misturados ao substrato de uma vez antes do transplantio e o N e o K após o transplantio, divididos em 20 aplicações semanais. As fontes utilizadas para os tratamentos foram superfosfato triplo, gesso, NH4NO3 e KCl. As concentrações foliares aos cinco meses de idade situaram-se na faixa alta, para os nutrientes N, P, K e S, e baixa para Ca e Mg. As doses que proporcionaram a maior produção de matéria seca e melhores concentrações foliares foram N = 3,5; P = 2,7; K = 2,0; e Ca = 6,5 g por planta.Analysis of leaf nutrient contents can demonstrate plant nutritional status, identify symptoms of deficiency and toxicity, and evaluate the need to adjust fertilization programs. This research determined N:P:K:Ca:S rates for optimal nutrition of Rangpur lime - RL (Citrus limonia Osb.) rootstock, in an experiment arranged in a fractional factorial design of the (¹/25) 5(4) type, with 25 treatments distributed within five blocks. Seedlings of RL were transplanted into 3.8-dm³ containers filled with commercial growing media, when plant height = 10 cm, in a nursery. Treatments consisted of the following nutrient rates (g per plant): N = 0.31, 0.62, 1.25, 2.5 and 5; K = 0.4, 0.62, 1.25, 2.5 and 5; P = 0.35, 1.0, 2.0, 3.0 and 4.0; and Ca = 3.5, 5.0, 6.0, 7.0 and 8.0. Phosphorus and Ca were applied to the compost before transplant of seedlings, while N and K were applied later and total amounts were split into 20 weekly applications via fertigation. Nutrient sources were triple super phosphate, gypsum, NH4NO3 and KCl. Leaf nutrient concentrations of five-mo-old plants were high or in excess for N, P, K and S. Calcium and Mg concentrations were low. Greater dry mass of plants were observed at nutrient rates of N = 3.5, P = 2.7, K = 2.0, and Ca = 6.5 g per plant
FLUTUAÇÃO POPULACIONAL DE Whitius piger (PSEUDOSCORPIONIDA) EM GRANJA AVÍCOLA EM PELOTAS, RS, BRASIL
To evaluate the populational flotation of Whitius piger two monitoring methods
were used, a tube type trap and a sandwich type trap. The experiment took place in the period
of April 2002 to March of 2003, in an aviary from the Conjunto Agrotécnico Visconde da Graça
(CAVG), located at Pelotas, Rio Grande do Sul, Brazil. During that period 1539 samples of
Whitius piger were captured, being the period of larger occurrence in the month of March (312),
when the monthly medium temperature was 22,2ºC and the smallest occurrence during the
month of June (11), with a monthly medium temperature of 14,5ºC. It has been found that the
Whitius piger was present iduring all the 12 months of collection, displaying a larger capture
during the months of higher temperatures and a smaller capture in the months of lower
temperatures.Para avaliar a flutuação populacional de Whitius piger foram utilizados dois métodos
de monitoramento, armadilha do tipo tubo e do tipo sanduíche. O experimento realizou-se
no período de abril de 2002 a março de 2003, em aviário do Conjunto Agrotécnico Visconde da
Graça (CAVG), localizado em Pelotas, Rio Grande do Sul, Brasil. Nesse período foram
capturados 1539 exemplares de Whitius piger, sendo o período de maior ocorrência no mês de
março (312), quando a temperatura média mensal foi de 22,2ºC e a menor ocorrência foi no
mês de junho (11) com temperatura média mensal de 14,5ºC. O pseudoescorpionideo esteve
presente nos 12 meses de coleta, apresentando maior captura nos meses de maior temperatura
e menor captura nos meses de menor temperatura
Redshift-distance Survey of Early-type Galaxies: The D_n-sigma Relation
In this paper R-band photometric and velocity dispersion measurements for a
sample of 452 elliptical and S0 galaxies in 28 clusters are used to construct a
template D_n-sigma relation. This template relation is constructed by combining
the data from the 28 clusters, under the assumption that galaxies in different
clusters have similar properties. The photometric and spectroscopic data used
consist of new as well as published measurements, converted to a common system,
as presented in a accompanying paper. The resulting direct relation, corrected
for incompleteness bias, is log{D_n} =1.203 log{sigma} + 1.406; the zero-point
has been defined by requiring distant clusters to be at rest relative to the
CMB. This zero-point is consistent with the value obtained by using the
distance to Virgo as determined by the Cepheid period-luminosity relation. This
new D_n-sigma relation leads to a peculiar velocity of -72 (\pm 189) km/s for
the Coma cluster. The scatter in the distance relation corresponds to a
distance error of about 20%, comparable to the values obtained for the
Fundamental Plane relation. Correlations between the scatter and residuals of
the D_n-sigma relation with other parameters that characterize the cluster
and/or the galaxy stellar population are also analyzed. The direct and inverse
relations presented here have been used in recent studies of the peculiar
velocity field mapped by the ENEAR all-sky sample.Comment: 46 pages, 20 figures, and 7 tables. To appear in AJ, vol. 123, no. 5,
May 200
No change in neurodevelopment at 11 years after extremely preterm birth
Objective: To determine whether improvements in school age outcomes had occurred between two cohorts of births at 22–25 weeks of gestation to women residents in England in 1995 and 2006.
Design: Longitudinal national cohort studies.
Setting: School-based or home-based assessments at 11 years of age.
Participants: EPICure2 cohort of births at 22–26 weeks of gestation in England during 2006: a sample of 200 of 1031 survivors were evaluated; outcomes for 112 children born at 22–25 weeks of gestation were compared with those of 176 born in England during 1995 from the EPICure cohort. Classroom controls for each group acted as a reference population.
Main outcome measures: Standardised measures of cognition and academic attainment were combined with parent report of other impairments to estimate overall neurodevelopmental status.
Results: At 11 years in EPICure2, 18% had severe and 20% moderate impairments. Comparing births at 22–25 weeks in EPICure2 (n=112), 26% had severe and 21% moderate impairment compared with 18% and 32%, respectively, in EPICure. After adjustment, the OR of moderate or severe neurodevelopmental impairment in 2006 compared with 1995 was 0.76 (95% CI 0.45 to 1.31, p=0.32). IQ scores were similar in 1995 (mean 82.7, SD 18.4) and 2006 (81.4, SD 19.2), adjusted difference in mean z-scores 0.2 SD (95% CI −0.2 to 0.6), as were attainment test scores. The use of multiple imputation did not alter these findings.
Conclusion: Improvements in care and survival between 1995 and 2006 are not paralleled by improved cognitive or educational outcomes or a reduced rate of neurodevelopmental impairment
The advantages of semiochemical-based attract and kill techniques in insect pest management.
Introduction: Semiochemicals (chemicals impacting insect behavior) have been employed in species-specific, ecologically friendly insect pest control strategies through a wide variety of mechanisms, many of which do not require the application of conventional insecticides. These include mating disruption?application of sex pheromones in such a way that male insects are unable to locate a female mate, reducing the size of the pest population in the treated area over time?mass trapping, and repellency. However, semiochemical attractants can also be used in combination with small amounts of chemical toxicants, a strategy called attract and kill (A&K)
The advantages of semiochemical-based attract and kill techniques in insect pest management: agricultural case studies.
Introduction: While the advantages of semiochemical-based pest control technologies over traditional insecticides are well-documented (reduced hazards to non-targets and the environment, lower risk of resistance, etc.), many strategies employing these behavior-manipulating compounds to protect agricultural crops are relegated to small niche markets,due to their limited applicability. Since most semiochemicals are species-specific, they can usually target only one pest at a time. However, this is not always the case, as we will demonstrate through this discussion of four of ISCA Technologies? attract and kill (A&K) formulations
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