bluuebunny/crossref_metadata_2025 huggingface dataset:
Fosfatos com diferentes relações flúor: fósforo na alimentação de frangos de corte
Authors: Casartelli Elenice Maria , Junqueira Otto Mack , Araújo Lúcio Francelino , Araújo Cristiane Soares da Silva , Savietto Davi , Trindade Neto Messias Alves da
Published: May 2008

Um experimento foi conduzido com o objetivo de verificar os efeitos de diferentes relações flúor:fosforo na alimentação sobre o desempenho de frangos de corte. Foram utilizados 1.000 pintos de corte de 1 dia distribuídos em um delineamento inteiramente casualizado, com quatro tratamentos e cinco repetições de 50 aves por boxe. Os tratamentos consistiram de quatro fontes de fósforo com relações flúor:fósforo de 1:40, 1:60, 1:80 e 1:100. O experimento foi dividido em três fases experimentais: 1 a 21, 22 a 42 e 43 a 49 dias de idade. Em cada fase, avaliou-se o consumo de ração, o ganho de peso e a conversão alimentar. Ao final do experimento, foram abatidas duas aves de cada repetição para coleta da tíbia e de músculos do peito para análise das concentrações de flúor, cálcio, fósforo e magnésio desses tecidos. As relações flúor:fósforo avaliadas não afetaram o desempenho dos frangos de corte. A deposição óssea de flúor é proporcional à sua concentração na dieta, no entanto, a elevação dos níveis de flúor da dieta não influencia sua deposição nos músculos.
Pérolas diamantadas obtidas por metalurgia do pó: nacionalização da tecnologia
Authors: De Oliveira L.J. , Filgueira M.
Published: May 2008

Os Fios Diamantados são ferramentas de corte aplicadas ao desmonte de rochas ornamentais, bem como a cortes de blocos de concreto, e podem ser utilizadas em substituição a serras em geral. Estas ferramentas são compostas de um fio alma (aço inoxidável), sobre o qual são dispostos segmentos anulares diamantados (pérolas diamantadas) igualmente espaçadas. Em geral, as pérolas de fios diamantados são processadas através das técnicas da Metalurgia do Pó, onde se produz compósitos tendo como partícula abrasiva o diamante, e normalmente um ligante metálico para aderir os diamantes. As pérolas diamantadas do presente trabalho foram produzidas via Metalurgia do Pó convencional, utilizando como matriz metálica ligante uma liga de Fe-20%pCu, com adição de 1% em peso de SiC. Foram feitas análises de retração/inchaço e microestrutural após a sinterização, testes de dureza Brinell, e foram medidas as resistências ao desgaste das pérolas aqui produzidas em confronto com as pérolas comerciais importadas. Os resultados mostram que conseguiu-se processar pérolas de mesmo desempenho das pérolas comerciais importadas.
Análise da influência dos diferentes tempos de polimerização por luz incandescente sobre a resistência ao desgaste abrasivo de resinas compostas
Authors: Cruz C.E.D. , Santana L.R.S. , Bianchi E.C. , De Aguiar P.R. , Silva Junior C.E. , Catai R.E. , De Freitas C.A. , Salgado M.H. , Freitas M.F.A. , Ulhoa M.P.M.
Published: May 2008

No mercado atual a qualidade é necessária na fabricação dos produtos. No mercado odontológico, as resinas compostas são cada vez mais utilizadas para substituir materiais tradicionais, como amalgama, nas restaurações estéticas e funcionais, apresentando boa estética e funcionalidade. A composição química destes materiais é variável e os resultados das reações químicas do processo de polimerização são bastante desconhecidos. O objetivo deste trabalho era medir a resistência do desgaste abrasivo de seis resinas compostas vendidas no mercado brasileiro polimerizadas com tempos de 10, 20 e 40 segundos. O método do disco retificado modificado para aplicações em odontologia foi usado para tornar esta proposta viável. Neste banco de ensaios um disco dinâmico, revestido por porcelana, desgasta um disco estático revestido do tipo de resina que se pretende avaliar, que foi polimerizada durante um tempo pré-estabelecido. Com a determinação do desgaste de material, num determinado tempo, determinava-se a agressividade (capacidade de um material para desgastar outro material) do disco dinâmico sobre o disco estático. Utilizando-se para isso um programa computacional (LabView). Posteriormente era feita a regressão linear dos valores obtidos e determinado o coeficiente angular, utilizado no cálculo de agressividade. Valores elevados de agressividade indicam uma maior agressão do disco dinâmico contra o disco estático. Os resultados mostraram um comportamento variável para cada material que foi polimerizado nos diferentes tempos de polimerização utilizado, mostrando que o método para fazer estudos de desgaste é prático e rápido para testar materiais novos antes da sua utilização.
Desenvolvimento de compostos bentonita/polímeros para aplicação em fluidos de perfuração: Parte 2
Authors: Amorim L.V. , Barbosa M.I.R. , Ferreira H.C.
Published: May 2008

Os depósitos de bentonita da Paraíba constituem um dos mais importantes do país. Essas argilas são empregadas, dentre outras aplicações, como viscosificante em fluidos de perfuração. Contudo, atualmente, alguns tipos de argila encontradas nesses depósitos não apresentam os parâmetros exigidos pela PETROBRAS e a aditivação polimérica surge como alternativa para adequar essas propriedades. Sendo assim, este trabalho objetiva o desenvolvimento de compostos bentonita/polímeros para uso em fluidos de perfuração à base de água. Para tanto, foram estudadas uma amostra de argila bentonítica sódica industrializada da Paraíba, Brasil, duas amostras de carboximetilcelulose (CMC) e uma amostra de poliacrilamida (PAM). O dimensionamento do composto polimérico (misturas de dois e três polímeros) foi elaborado por meio do planejamento experimental, sendo estudadas dez diferentes composições. Os compostos poliméricos, em três diferentes concentrações, foram misturados à argila seca. Em seguida, foram preparados os fluidos de perfuração e determinadas as viscosidades aparente e plástica, o limite de escoamento e o volume de filtrado de acordo com as normas da PETROBRAS. Os resultados das análises mostraram que a aditivação da bentonita com o composto polimérico permite obter uma mistura com melhores propriedades reológicas e de filtração. Finalmente, esse procedimento permite o uso de argilas bentoníticas de qualidade inferior em fluidos de perfuração de poços de petróleo.
Compósito de "metal duro - nitreto cúbico de boro"
Authors: Bobrovnitchii G.S. , Filgueira M. , Gomes U.U. , Tardim R.C.
Published: May 2008

Os materiais compósitos à base de metal duro (matriz) e nitreto cúbico de boro (cBN) ainda são raramente utilizados em aplicações de tecnologias industriais. Apesar de possuir propriedades físicas similares as do diamante, o cBN possui a característica inconveniente de reagir com o material da matriz durante seu processo de obtenção, feita através da sinterização. Uma maneira de eliminar este efeito negativo é aplicar altas pressões (até 9,0 GPa) durante o processo de sinterização. Em experimentos realizados, misturas de pó de metal duro (WC15%Co) e cBN (16% do volume) foram submetidas a altas pressões, entre 6,0 e 7,0 GPa, e a altas temperaturas, entre 1200 e 1400º C, durante 40 s. Depois de realizada a sinterização, a amostra que apresentou melhores resultados possuía densidade de 14,81 g/cm3, dureza Knoop média de 20,8 GPa, limite de compressão médio de 5,2 GPa, e desgaste na razão de 0,21 g a cada 5 min.
Atividade eletromiográfica no agachamento nas posições de 40º, 60º e 90º de flexão do joelho
Authors: Sousa Catarina de Oliveira , Ferreira José Jamacy de Almeida , Medeiros Ana Catarina L. Veras , Carvalho Antônia Hermínia de , Pereira Rosana Cavalcante , Guedes Dimitri Taurino , Alencar Jerônimo F. de
Published: May 2008

O objetivo deste estudo foi comparar a atividade eletromiográfica (EMG) dos músculos reto femoral, bíceps femoral, tibial anterior e sóleo no agachamento, associando a posição de tronco ereto com 2 ângulos de flexão do joelho (40° e 60°) e a posição de tronco fletido a 45° com 3 ângulos de flexão do joelho (40°, 60° e 90°). Todas as combinações foram realizadas com e sem acréscimo de carga (10kg). A amostra foi composta por 12 indivíduos saudáveis com idade de 21,1 ± 2,5 anos e massa corporal de 62,8 ± 7,4kg. O EMG dos músculos citados foi registrado, isometricamente, em 10 posições de agachamento. Para a análise estatística foi aplicada ANOVA Two-Way de Friedman e o teste Post-Hoc de Newman-Keuls. Os resultados mostraram co-ativação entre os músculos reto femoral e bíceps femoral nas posições de tronco fletido e joelho em flexão de 40º e, entre os músculos reto femoral e sóleo, nas demais posições (p < 0,05). Houve co-ativação entre o tibial anterior e bíceps femoral com o joelho a 40º, com o tronco ereto e fletido e, entre o tibial anterior e sóleo, nas demais posições (p < 0,05). Quanto à ativação muscular isolada, a maior flexão do joelho no agachamento foi um fator determinante para maior ativação dos músculos, exceto para o sóleo. A posição do tronco e a carga adicional de 10kg influenciaram a ativação muscular do reto femoral, a 60° de flexão de joelho, na qual o tronco ereto proporcionou maior ativação. E para o bíceps femoral, a 40° de flexão de joelho, na qual o tronco flexionado proporcionou maior ativação. A co-ativação entre o reto femoral e o bíceps femoral na posição de tronco fletido, e entre o reto femoral e o sóleo nas demais posições, apontam para novas possibilidades de exercícios na reabilitação.
MANAGING PLANT POPULATION SPREAD: PREDICTION AND ANALYSIS USING A SIMPLE MODEL
Authors: Bullock James M. , Pywell Richard F. , Coulson-Phillips Sarah J.
Published: May 2008

Models can be used to direct the management of population spread for the control of invasives or to encourage species of conservation value. Analytical models are attractive because of their theoretical basis and limited data requirements, but there is concern that their simplicity may limit their practical utility. We address the applied use of simple models in a study of a declining annual herb,Rhinanthus minor.We parameterized a population‐spread model using field data on demography and dispersal for four management systems: grazed only (GR), hay‐cut once (H1), hay‐cut twice (H2), and hay‐cut with autumn grazing (HG). Within a replicated experiment we measured spread rates of introducedR. minorpopulations over eight years. The modeled and measured spread rates were very similar in terms of both patterns of management effects and absolute values, so that in both cases HG > H2, H1 > GR. The treatments affected both dispersal and demography (establishment and survival) and so we used decomposition approaches to analyze the major causes of differences in population spread. Increased dispersal under hay‐cutting was more important than demographic changes and accounted for ∼70% of the differences in spread rate between the hay‐cut and grazed‐only treatments. Furthermore, management effects on the tail of the dispersal curve were by far the most critical in governing spread. This study suggests that simple models can be used to inform practical conservation management, and we demonstrate straightforward uses of our model to predict the impacts of different management strategies. While simple models can give accurate projections, we emphasize that they must be parameterized with high‐quality data gathered at the appropriate spatial scale.
POTENTIAL SITE PRODUCTIVITY INFLUENCES THE RATE OF FOREST STRUCTURAL DEVELOPMENT
Authors: Larson Andrew J. , Lutz James A. , Gersonde Rolf F. , Franklin Jerry F. , Hietpas Forest F.
Published: May 2008

Development and maintenance of structurally complex forests in landscapes formerly managed for timber production is an increasingly common management objective. It has been postulated that the rate of forest structural development increases with site productivity. We tested this hypothesis for Douglas‐fir (Pseudotsuga menziesii(Mirb.) Franco) forests using a network of permanent study plots established following complete timber harvest of the original old‐growth forests. Forest structural development was assessed by comparing empirical measures of live tree structure to published values for Douglas‐fir forests spanning a range of ages and structural conditions. The rate of forest structural development—resilience—exhibited a positive relationship with site index, a measure of potential site productivity. Density of shade‐intolerant conifers declined in all study stands from an initial range of 336–4068 trees/ha to a range of 168–642 trees/ha at the most recent measurement. Angiosperm tree species declined from an initial range of 40–371 trees/ha to zero in seven of the nine plots in which they were present. Trends in shade‐tolerant tree density were complex: density ranged from 0 to 575 trees/ha at the first measurement and was still highly variable (25–389 trees/ha) at the most recent measurement. Multivariate analysis identified the abundance of hardwood tree species as the strongest compositional trend apparent over the study period. However, structural variables showed a strong positive association with increasing shade‐tolerant basal area and little or no association with abundance of hardwood species. Thus, while tree species succession and forest structural development occur contemporaneously, they are not equivalent processes, and their respective rates are not necessarily linearly related. The results of this study support the idea that silvicultural treatments to accelerate forest structural development should be concentrated on lower productivity sites when the management objective is reserve‐wide coverage of structurally complex forests. Alternatively, high‐productivity sites should be prioritized for restoration treatments when the management objective is to develop structurally complex forests on a portion of the landscape.
BIRDS DEFEND OIL PALMS FROM HERBIVOROUS INSECTS
Authors: Koh Lian Pin
Published: May 2008

Top‐down forces are expected to be important in regulating herbivore populations in most agricultural systems where primary productivity is high and species diversity is low. Under such conditions, trophic cascades are predicted to occur when predator populations are reduced or removed. Studies on how predator removal indirectly affects herbivory rates in agricultural systems are lacking. Through a bird‐exclosure experiment, I test the hypothesis that insectivorous birds indirectly defend oil palms (Elaeis guineensis) from herbivorous insects. Results show that bird exclusion significantly increased herbivory damage to oil palms, and that the size of this exclusion effect increased with bird density, although the latter result was not statistically significant. These findings suggest that insectivorous birds deliver a natural pest control service for oil palm agriculture, which is important not only for the direct benefits it delivers for human welfare, but also in strengthening the economic justifications for conserving the remaining natural habitats and biodiversity in agricultural landscapes.
Heusler films and multilayers: X-ray resonant magnetic scattering and polarized neutron reflectivity studies on the relation between structure and magnetism
Authors: Bergmann Andre , Grabis Johannes , Vadala Miriana , Nefedov Alexei , Westerholt Kurt , Zabel Hartmut
Published: May 2008

We have studied the structural properties and the magnetization density profiles in multilayers of the Heusler phase CoMnGe with three different spacer layers: V, Au, and AlO, using hard X-ray scattering, soft X-ray resonant magnetic scattering, and polarized neutron reflectivity. We have found that the spacer layer has a significant effect on the magnetization profile of the CoMnGe layer. In all cases the interlayers at the top and the bottom of the Heusler layer exhibit a reduced magnetic moment, the thickness of which depends on the spacer layer and increases from 0.5 nm for V, to 0.6 nm for Au and 1 nm for AlO.
A subnanoscale study of the nucleation, growth, and coarsening kinetics of Cu-rich precipitates in a multicomponent Fe – Cu based steel
Authors: Prakash Kolli R. , Wojes Ryan M. , Zaucha Stephanie , Seidman David N.
Published: May 2008

The nucleation, growth, and coarsening kinetics of Cu-rich precipitates in a multicomponent Fe – Cu based steel, containing 1.17 at.% Cu, aged at 500 °C for up to 1024 h are investigated. The temporal evolution of the precipitate, heterophase interface, matrix compositions and precipitate morphology are presented. Coarsening temporal exponents are determined for mean radius, number density, and supersaturations, and are compared to the Lifshitz – Slyzov – Wagner model for coarsening, modified for multicomponent alloys by Umantsev and Olson. The experimental results indicate that the alloy does not strictly follow Umantsev – Olson model behavior. Additionally, we compare the results to an investigation of a similar multicomponent steel containing 1.82 at.% Cu and to results in the literature. Furthermore, we present a Thermo-Calc determined phase diagram.
Formation of nickel nanoparticles in nickel – ceramic anodes during operation of solid-oxide fuel cells
Authors: Du Kui , Ernst Frank , Garrels Michael , Payer Joe
Published: May 2008

The microstructure of solid-oxide fuel cell anodes, consisting of nickel particles embedded in either doped zirconia or ceria, was characterized in three different stages: (i) as sintered, (ii) after reduction, and (iii) after fuel cell operation for 500 h in an atmosphere of moist hydrogen. After 500 h of operation, we found that both types of anodes, those based on zirconia and those based on ceria, contained nanoparticles of elemental nickel. We propose that these nanoparticles form from nickel hydroxide, synthesized during fuel cell operation and precipitating elemental nickel where the partial pressure of water is low at the periphery of triple-phase boundaries or on cooling down from the operating temperature to room temperature.
Characterisation of complex hydrides synthesised or modified by ball milling
Authors: Llamas-Jansa Isabel , Rongeat Carine , Doppiu Stefania , Gutfleisch Oliver , Schultz Ludwig
Published: May 2008

Ball milling is an effective method for the synthesis and modification of light complex hydrides by changing the milling conditions. Using specially designed vials, in-situ variations of the hydrogen pressure and vial temperature taking place during the milling of LiAlH4, with and without dopants, and of LiBH4 + MgCl2 were monitored. This provided information about the efficiency of the reactions before removing the powder from the vial. The thermodynamic properties of the milled hydrides were analysed by differential scanning calorimetry and intelligent gravimetric analysis. Additional structural characterisation was carried out by X-ray diffraction and Raman spectroscopy. The results showed that the decomposition of LiAlH4 during milling is strongly affected by the use of TiCl3 as dopant. The partial formation of Mg(BH4)2 from LiBH4 + MgCl2 was demonstrated by Raman spectroscopy.
Homogeneity of mechanically alloyed nano-crystalline Fe – Cu-powders
Authors: Wille Catharina , Al-Kassab Taláat , Schmidt Malte , Choi Pyuck-Pa , Kwon Young-Soon
Published: May 2008

In this contribution Atom Probe Tomography has been applied systematically to characterise the homogeneity of mechanically alloyed Fe – Cu powders for two different compositions (Fe-10 at.% Cu, and Cu-2.5 at.% Fe). Fe – Cu is among the most attractive systems for technical application since it exhibits the Invar effect. Additionally it serves as a binary model system and hence is representative for those immiscible systems characterised by a large positive heat of mixing. Results on the extension of the solubility limits up to 10 at.% and on the homogeneity of the alloy – depending on composition and milling time – are presented, discussed and compared to earlier works. Chemical homogeneity of the sample as measured by the atom probe was never fully reached on the nano-scale, even for the longest milling time and for those samples which appear to be homogeneous via X-ray analysis. Furthermore, impurities such as oxygen, stemming from the preparation procedure, were frequently detected and analysed for the different samples. In addition, structural characterisation was performed using transmission electron microscopy and diffraction measurements to confirm the transition of Fe from bcc to fcc. Thus, nano-scale information on the local concentration, segregation effects and the distribution of impurities for the different nominal compositions and processing parameters could be gained.
Hydrogen absorption in 3.1 nanometre sized palladium samples: does structure matter?
Authors: Suleiman Mohammed , Fritsch Detlev , Borchers Christine , Guerdane Mohamed , Pundt Astrid
Published: May 2008

In this work the hydrogen absorption behaviour of two types of Pd-clusters, different in structure but similar in size (3.1 nm), will be presented. First, icosahedral Pd clusters stabilised in surfactants; second, cubic Pd clusters stabilised in a Teflon-AF matrix. The phase transition in these samples was monitored by in-situ X-ray diffraction. It will be shown that the hydrogen uptake ability depends strongly on the lattice structure, which is affected by the type of stabiliser. Teflon AF stabilised clusters (cubic clusters) show the phase transition which is common for bulk Pd, whereas the surfactant stabilised clusters (icosahedral clusters) show only weak lattice dilatation upon hydrogen absorption. Pressure – lattice parameter isotherms show that the cubic clusters absorb large amounts of hydrogen in comparison to the icosahedral clusters. The measured lattice expansion is 0.130 Å at 105 Pa and 300 K, which is about 320 % the amount measured for icosahedral clusters (0.04 Å). This suggests that surface sites are available for hydrogen in the Pd – Teflon-AF samples which are not accessible for Pd – surfactant-clusters, and that the icosahedral lattice absorbs less hydrogen for similar external pressures.
Perovskite-type hydrides – synthesis, structures and properties
Authors: Ikeda Kazutaka , Sato Toyoto , Orimo Shin-ichi
Published: May 2008

The present study gives an overview of the fundamental material properties of perovskite-type hydrides. Formation ability of the perovskite-type hydrides has been reasonably explained on the basis of the geometric restrictions on the composed ions using the Goldschmidt tolerance factor. Characteristic crystal structures and charge density maps of the perovskite-type hydrides without/with transition metals, such as NaMgH3/CaNiH3, were also examined in detail to clarify the relationship between the structures (atomic and electronic) and the hydriding properties.
On the small scale character of the stress and hydrogen concentration fields at the tip of an axial crack in steel pipeline: effect of hydrogen-induced softening on void growth
Authors: Dadfarnia Mohsen , Sofronis Petros , Somerday Brian P. , Robertson Ian M.
Published: May 2008

Gaseous hydrogen transport at pressures of 15 MPa is envisaged as a means of hydrogen delivery from central production facilities to refueling stations for the planned hydrogen economy. The study of the hydrogen embrittlement of medium or mild strength steels, which are under consideration for pipeline materials, has not as of yet led to methods to design safe and reliable pipelines. The most important failure modes in hydrogen containment components are due to subcritical cracking. However, current design guidelines for pipelines only tacitly address subcritical cracking by applying arbitrary, conservative safety factors on the applied stress. In the present work, we investigate the interaction of hydrogen transport with material elastoplasticity in the neighborhood of an axial crack in a steel pipeline. For all practical purposes, we find that the stress, deformation, and hydrogen fields exhibit a small scale character which allows for the use of the standard modified boundary layer approach to the study of the fracture behavior of steel pipelines. The approach is based on constraint fracture mechanics methodology whereby a two-parameter characterization – the stress intensity factor and the T-stress – is used to describe the interaction of the stress and deformation fields with the diffusing hydrogen under conditions of hydrogen uptake from the crack faces and outgassing through the outer boundaries, as in the pipeline. Employing the Rice and Tracey model of void growth, we find that hydrogen-induced softening can accelerate void growth in a small region confined at the crack tip by as much as 70 % relative to the case of a hydrogen-free material. We close by suggesting that one can ascertain the hydrogen effects on fracture at an axial pipeline crack with the use of a laboratory fracture mechanics specimen tested in hydrogen gas and subjected to the same intensity factor, and hydrostatic constraint, T-stress, as the real-life pipeline.
The need of data harmonization to derive robust empirical relationships between soil conditions and vegetation
Authors: Bartholomeus Ruud P. , Witte Jan‐Philip M. , van Bodegom Peter M. , Aerts Rien
Published: May 2008

Question:

Is it possible to improve the general applicability and significance of empirical relationships between abiotic conditions and vegetation by harmonization of temporal data?

Location:

The Netherlands.

Methods:

Three datasets of vegetation, recorded after periods with different meteorological conditions, were used to analyze relationships between soil moisture regime (expressed by the mean spring groundwater level –MSLt calculated for different periods) and vegetation (expressed by the mean indicator value for moisture regime Fm). For each relevé, measured groundwater levels were interpolated and extrapolated to daily values for the period 1970–2000 by means of an impulse‐response model. Sigmoid regression lines between MSLt and Fm were determined for each of the three datasets and for the combined dataset.

Results:

A measurement period of three years resulted in significantly different relationships between Fm and MSLt for the three datasets (F‐test, p < 0.05). The three regression lines only coincided for the mean spring groundwater level computed over the period 1970–2000 (MSLclimate) and thus provided a general applicable relationship. Precipitation surplus prior to vegetation recordings strongly affected the relationships.

Conclusions:

Harmonization of time series data (1) eliminates biased measurements, (2) results in generally applicable relationships between abiotic and vegetation characteristics and (3) increases the goodness of fit of these relationships. The presented harmonization procedure can be used to optimize many relationships between soil and vegetation characteristics.
A laboratory study of particle ploughing and pore-pressure feedback: a velocity-weakening mechanism for soft glacier beds
Authors: Thomason Jason F. , Iverson Neal R.
Published: May 2008

If basal-water discharge and pressure are sufficiently high, a soft-bedded glacier will slip over its bed by ploughing, the process in which particles that span the ice–bed interface are dragged across the bed surface. Results of laboratory experiments indicate that resistance to ploughing can decrease with increasing ploughing velocity (velocity weakening). During ploughing at various velocities (15–400 m a−1), till was compacted in front of idealized particles, causing pore pressures there that were orders of magnitude higher than the ambient value. This excess pore pressure locally weakened the till in shear, thereby decreasing ploughing resistance by a factor of 3.0–6.6 with a six-fold increase in ploughing velocity. Characteristic timescales of pore-pressure diffusion and compaction down-glacier from ploughing particles depend on till diffusivity, ploughing velocity and sizes of ploughing particles. These timescales accurately predict the ranges of these variables over which excess pore pressure and velocity weakening occurred. Existing ploughing models do not account for velocity weakening. A new ploughing model with no adjustable parameters predicts ploughing resistance to no worse than 38% but requires that excess pore pressures be measured. Velocity weakening by this mechanism may affect fast glacier flow, sediment transport by bed deformation and basal seismicity.
Temporal and spatial variability of surface mass balance at Dome Fuji, East Antarctica, by the stake method from 1995 to 2006
Authors: Kameda Takao , Motoyama Hideaki , Fujita Shuji , Takahashi Shuhei
Published: May 2008

The surface mass balance (SMB) at Dome Fuji, East Antarctica, was estimated using 36 bamboo stakes (grid of 6 × 6, placed at 20 m intervals) from 1995 to 2006. The heights of the stake tops from the snow surface were measured at 0.5 cm resolution twice monthly in 1995, 1996, 1997 and 2003, and once a year for the rest of the study period. To account for snow settling, the average snow density at the stake base during the measurements was used for converting the stake-height data to SMB. The annual SMB from 1995 to 2006 at Dome Fuji was 27.3 ± 1.5 kg m−2 a−1. This result agrees well with the annual SMB from AD 1260 to 1993 (26.4 kg m−2 a−1) estimated from volcanic signals in the Dome Fuji ice core. Over the period 1995–2006, there were 37 (8.6% of the measurements) negative or zero annual SMB results. Variation in the multi-year averages of annual SMB decreased with the square root of the number of observation years, and 10 years of observations of a single stake allowed the estimation of annual SMB at ±10% accuracy. The frequency distributions of annual and monthly SMB were examined. The findings clarify the complex behavior of the annual and monthly SMB at Dome Fuji, which will be common phenomena in areas of low snow accumulation of the interior of the Antarctic ice sheet.
Spatial mapping of multi-year superimposed ice on the glacier Kongsvegen, Svalbard
Authors: Brandt Ola , Kohler Jack , Lüthje Mikael
Published: May 2008

Ground-penetrating radar (GPR) and satellite ERS-2 synthetic aperture radar (SAR) are used to map the thickness and extent of the superimposed ice (SI) zone on the surge-type glacier Kongsvegen, Svalbard. GPR imagery shows sub-horizontal SI layers lying unconformably above a discrete boundary. Below this boundary, the ice has a GPR signature similar to that of ice further down-glacier in the ablation zone. This boundary is posited to represent the closing of crevasses that were created during the last surge of Kongsvegen in ∼1948. Open crevasses would have interrupted the formation of sheet layers of SI due to efficient vertical drainage of the snowpack. Aerial photographs suggest that the crevasses closed sometime in the period 1956–66. A classified SAR image from 2003 is used to delineate the extent of the SI zone. The SI extent in the SAR image agrees well with the SI zone mapped by GPR. Using the SI spatial depth distribution, we estimate the mean annual accumulation of superimposed ice to be 0.16 ± 0.06 m w.e. a−1 (locally up to 0.43 m a−1 w.e.). This corresponds to ∼15–33% of the local winter balance and ∼5–10% of the total winter balance measured since 1987.
Flow-switching and water piracy between Rutford Ice Stream and Carlson Inlet, West Antarctica
Authors: Vaughan David G. , Corr Hugh F.J. , Smith Andy M. , Pritchard Hamish D. , Shepherd Andrew
Published: May 2008

Rutford Ice Stream and Carlson Inlet are neighbouring glaciers in West Antarctica. Rutford Ice Stream flows at speeds greater than 350 m a−1, whereas Carlson Inlet, which has some similar dimensions and supports a similar driving stress, flows 10–50 times slower. We discuss a range of observations concerning Carlson Inlet, and conclude that there is good indirect evidence that it is a relict ice stream, which ceased streaming more than 240 years BP, but sufficiently recently that its surface morphology, basal water content and basal morphology still retain characteristics produced by streaming. An analysis of expected subglacial drainage pathways indicates that Carlson Inlet is not streaming because it is currently starved of subglacial water, which is currently directed beneath Rutford Ice Stream. This current state of water piracy by Rutford Ice Stream is, however, sensitive to minor thickness changes on the ice streams; a ∼120 m (<4%) thickening of Rutford Ice Stream would divert almost all the subglacial water in the system towards Carlson Inlet and could reactivate its flow. The result highlights the importance of subglacial drainage in controlling ice-stream evolution and the requirement for ice-sheet models to couple ice flow with subglacial drainage.
Secular changes in stature and body mass index for Chinese youth in sixteen major cities, 1950s–2005
Authors: Ji Cheng‐Ye , Chen Tian‐Jiao
Published: May 2008

Evidence shows a secular trend in physical growth in China in recent years. We analyze the secular trend of stature and body mass index (BMI) for the period 1950s–2005 to provide biological evidence for policy‐makers to identify measures for improving Chinese children's health. Data come from the historical records in 1950s and the successive cycles of the Chinese National Survey on Student's Constitution and Health. Subjects were 7‐ to 18‐year‐old youth from 16 cities. Sex–age differences in mean stature and BMI values between the surveys were analyzed, and the increments per decade were compared. An overall positive secular trend was found in 1950s–2005. Mean stature of the 18‐year olds increased from 166.6 to 173.4 cm for males and from 155.8 to 161.2 cm for females, yielding rates of 1.3 and 1.1 cm/decade; the overall increments of BMI values were 2.6 for males and 1.8 for females, yielding rates of 0.8 and 0.6/decade, respectively. The most significant changes occurred during puberty. The overall positive secular trend is closely associated with the socioeconomic progress and the improvement of livelihood. Strong evidence suggests that in China this trend will be continued for many years. Further studies are needed to explore how to ensure healthy changes for poorer rural youth. Effective preventive strategies and measures should be taken to prevent the progressive increase in the prevalence of childhood obesity accompanying this trend. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Interstitial deletion of 1p22.2p31.1 and medium‐chain acyl‐CoA dehydrogenase deficiency in a patient with global developmental delay
Authors: Maegawa Gustavo H.B. , Poplawski Nicola K. , Andresen Brage Storstein , Olpin Simon E. , Nie Gloria , Clarke Joe T.R. , Teshima Ikuko
Published: May 2008

We report on a 6‐year‐old girl who presented at 6 months of age with seizures, delayed psychomotor development and mild facial dysmorphism. A small muscular ventricular septal defect was documented on echocardiogram and brain MRI showed a frontal brain anomaly. Urine organic acid analysis revealed dicarboxylic aciduria, and plasma acylcarnitine analysis showed marked elevation of octanoyl (C8) and decanoyl (C10) carnitines with C8:C10 ratio of 9:1. These results were indicative of medium chain acyl‐CoA dehydrogenase deficiency. ACADM gene sequencing showed an apparent homozygous c.166G > C (Ala31Pro) missense mutation in exon 3; however, only the mother was found to be a carrier of this novel missense mutation. This finding along with non‐regressive developmental delay prompted further karyotype and genomic investigations. An interstitial deletion of chromosome 1 was detected by repeat G‐banding: 46,XX,del(1)(p22.2p31.1). Parental karyotypes were normal. The deletion was characterized by array CGH analysis using a 1 Mb BAC/PAC array platform. Clones deleted extended from RP11‐88B10 (1p31.1) to RP5‐1007M22 (1p22.2), a 15.5 Mb deletion which includes the ACADM locus. Clinical review of 6/7 cases of interstitial deletions with breakpoints of 1p22 and 1p31/32, including the patient in this report, indicate a variable phenotype. Thus, although G‐band breakpoints are similar, common breakpoints for these alterations are unlikely. This is the first report of a patient with fatty acid oxidation defect caused by a mutation in combination with an interstitial chromosomal deletion. © 2008 Wiley‐Liss, Inc.
A novel mutation in IRF6 resulting in VWS–PPS spectrum disorder with renal aplasia
Authors: de Medeiros Filipe , Hansen Lars , Mawlad Evete , Eiberg Hans , Asklund Camilla , Tommerup Niels , Jakobsen Linda P.
Published: May 2008

Popliteal pterygium syndrome (PPS) and Van der Woude syndrome (VWS) are caused by mutations in the gene interferon regulatory factor 6 (IRF6). Skeletal, genital malformations and involvement of the skin occur in PPS and orofacial clefting and lip pits occur in both. We report on a patient with unilateral cleft lip and palate, ankyloblepharon, paramedian lip pits, unilateral renal aplasia, and a coronal hypospadias. By sequencing IRF6, we detected a novel missense mutation (Arg339Ile). The other family members were unaffected and had no IRF6 mutations, including the patient's brother who was also born with hypospadias. The patient and his brother were both conceived by in vitro fertilization (IVF). It is discussed whether the renal malformation in the patient is related to the IVF procedure or to the IRF6 mutation. © 2008 Wiley‐Liss, Inc.
Further case of microdeletion of 8q24 with phenotype overlapping Langer–Giedion without TRPS1 deletion
Authors: McBrien Jacqueline , Crolla John Anthony , Huang Shuwen , Kelleher Jerry , Gleeson John , Lynch Sally Ann
Published: May 2008

Langer–Giedion syndrome results from a microdeletion at 8q24.1 encompassing the EXT1 and the adjacent TRPS1 gene. We report on a boy with an oligo array‐cgh characterized small microdeletion involving EXT1 alone but with some features of Langer–Giedion syndrome suggesting a functional disturbance of TRPS1. This boy, in addition to a mild Langer–Giedion like phenotype, also had some unusual features including prominent toe pads and fat pads on the soles of his feet similar to those described in Pierpont syndrome. © 2008 Wiley‐Liss, Inc.
Antimicrobial polyester
Authors: Ren Xuehong , Kocer Hasan B. , Kou Lei , Worley S. D. , Broughton R. M. , Tzou Y. M. , Huang T. S.
Published: May 2008

Two N‐halamine siloxane precursors, 5,5‐dimethyl‐3‐(3′‐triethoxysilylpropyl)hydantoin and 3‐(3′‐triethoxysilylpropyl)‐7,7,9,9‐tetramethyl‐1,3,8‐triazaspiro[4.5]decane‐2,4‐dione, have been synthesized and coated onto polyester fiber surfaces. The coated polyester was rendered biocidal after exposure to household bleach solution by converting the heterocyclic precursors to N‐halamine moieties. The thermal properties of these coated polyester samples were determined with differential scanning calorimetry. The chlorinated polyester swatches were challenged with Staphylococcus aureus (ATCC 6538) and Escherichia coli O157 : H7 (ATCC 43895) with contact times ranging from 1 to 30 min. The biocidal testing showed that the chlorinated samples inactivated S. aureus and E. coli O157 : H7 within 5 and 30 min of contact, respectively. Standard washing tests indicated that the chlorinated coated fibers were very resistant to loss of the coating through hydrolyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Initial results using GPS navigation with the Foerster magnetometer system at the World Heritage site of Cyrene, Libya
Authors: Gaffney Chris , Gaffney Vince , Cuttler Richard , Yorston Ron
Published: May 2008

This Short Report summarizes some initial results using real time GPS to navigate and collect magnetometer data using Foerster sensors and a magnetic cart. The Foerster system is primarily aimed at the detection of buried ordnance and, by comparison to some other magnetometer sensors, the reported sensitivity is relatively low. However, the sensors require no alignment in the field, nor does the system require a regular contiguous grid to be established across the survey area. The latter means that data grids of different sizes and orientation can be measured and stitched together as part of data restoration prior to processing. The accurate positioning of the data means that ‘staggering’, which is often seen in time‐based collection strategies, is not apparent in the data; overall less processing is required to produce a final image than is required for other fluxgate instruments. Data from a survey at Cyrene are reproduced to illustrate the strengths of the system. Copyright © 2008 John Wiley & Sons, Ltd.
Single‐cell microinjection technology in cell biology
Authors: Zhang Yan , Yu Long‐Chuan
Published: May 2008

Single‐cell microinjection has been successfully used to deliver exogenous proteins, cDNA constructs, peptides, drugs and particles into transfection‐challenged cells. With precisely controlled delivery dosage and timing, microinjection has been used in many studies of primary cultured cells, transgenic animal production, in vitro fertilization and RNA inference. This review discusses the advantages and limits of microinjection as a mechanical delivery method and its applications to attached and suspended cells. BioEssays 30:606–610, 2008. © 2008 Wiley Periodicals, Inc.
Heterochromatin tells CENP‐A where to go
Authors: Durand‐Dubief Mickaël , Ekwall Karl
Published: May 2008

The centromere is the region of the chromosome where the kinetochore forms. Kinetochores are the attachment sites for spindle microtubules that separate duplicated chromosomes in mitosis and meiosis. Kinetochore formation depends on a special chromatin structure containing the histone H3 variant CENP‐A. The epigenetic mechanisms that maintain CENP‐A chromatin throughout the cell cycle have been studied extensively but little is known about the mechanism that targets CENP‐A to naked centromeric DNA templates. In a recent report published in Science,1 such de novo centromere assembly of CENP‐A is shown to be dependent on heterochromatin and the RNA interference pathway. BioEssays 30:526–529, 2008. © 2008 Wiley Periodicals, Inc.
Using a meiosis detection toolkit to investigate ancient asexual “scandals” and the evolution of sex
Authors: Schurko Andrew M. , Logsdon John M.
Published: May 2008

Sexual reproduction is the dominant reproductive mode in eukaryotes but, in many taxa, it has never been observed. Molecular methods that detect evidence of sex are largely based on the genetic consequences of sexual reproduction. Here we describe a powerful new approach to directly search genomes for genes that function in meiosis. We describe a “meiosis detection toolkit”, a set of meiotic genes that represent the best markers for the presence of meiosis. These genes are widely present in eukaryotes, function only in meiosis and can be isolated by degenerate PCR. The presence of most, or all, of these genes in a genome would suggest they have been maintained for meiosis and, implicitly, sexual reproduction. In contrast, their absence would be consistent with the loss of meiosis and asexuality. This approach will help to understand both meiotic gene evolution and the capacity for meiosis and sex in putative obligate asexuals. BioEssays 30:579–589, 2008. © 2008 Wiley Periodicals, Inc.
Identification of Bacterial Carotenoid Cleavage Dioxygenase Homologues That Cleave the Interphenyl α,β Double Bond of Stilbene Derivatives via a Monooxygenase Reaction
Authors: Marasco Erinn K. , Schmidt‐Dannert Claudia
Published: May 2008

Carotenoid cleavage oxygenases (CCOs), which are also referred to as carotenoid cleavage dioxygenases (CCDs) are a new class of nonheme iron‐type enzymes that oxidatively cleave double bonds in the conjugated carbon chain of carotenoids. The oxidative cleavage mechanism of these enzymes is not clear, and both monooxygenase and dioxygenase mechanisms have been proposed for different carotenoid cleavage enzymes. CCOs have been described from plants, animals, fungi, and cyanobacteria, but little is known about their distribution and activities in bacteria other than cyanobacteria. We surveyed bacterial genome sequences for CCO homologues and report the characterization of CCO homologues that were identified in Novosphingobium aromaticivorans DSM 12444 (NOV1 and NOV2) and in Bradyrhizobium sp. (BRA‐J and BRA‐S). In vitro and in vivo assays with carotenoid and stilbene compounds were used to investigate the cleavage activities of the recombinant enzymes. The NOV enzymes cleaved the interphenyl α‐β double bond of stilbenes that had an oxygen functional group at the 4′ carbon atom (e.g., resveratrol, piceatannol, and rhaponticin) to the corresponding aldehyde products. Carotenoids and apocarotenoids were not substrates for these enzymes. The two homologous enzymes from Bradyrhizobium sp. did not possess carotenoid or stilbene cleavage oxygenase activities, but showed activity with farnesol. To investigate whether the oxidative cleavage of stilbenes proceeds via a monooxygenase or dioxygenase reaction, oxygen‐labeling studies were conducted with NOV2. Our labeling studies show that the double‐bond cleavage of stilbenes occurs via a monooxygenase reaction mechanism.
A bootstrap‐based strategy for spectral interval selection in PLS regression
Authors: Brás Lígia P. , Lopes Marta , Ferreira Ana P. , Menezes José C.
Published: May 2008

Bootstrap‐based methods have been applied for spectral variable selection in near (NIR) and mid‐infrared (MIR) spectroscopy applications. In this paper, an extension of those methods for the selection of spectral intervals instead of single spectral variables is proposed. This approach, interval partial least square (PLS)‐Bootstrap (iPLS‐Bootstrap), was compared against the PLS‐Bootstrap method and the use of the whole spectral region for model development. These methods were tested on a NIR spectral dataset obtained from at‐line monitoring of an industrial fermentation process, by correlating the spectra with the concentration of the active pharmaceutical ingredient (API). The performance of the models was evaluated based on the predictive ability for both cross‐validation and external validation. For the dataset used, iPLS‐Bootstrap enabled to improve the model predictive ability, with a greater impact on external validation. The decrease observed in RMSEP relative to the full‐spectrum and PLS‐Bootstrap model was, respectively, 14 and 6%. Copyright © 2008 John Wiley & Sons, Ltd.
Corticotropin‐releasing factor binding protein within the ventral tegmental area is expressed in a subset of dopaminergic neurons
Authors: Wang Hui‐Ling , Morales Marisela
Published: May 2008

Corticotropin‐releasing factor (CRF) and related peptides play a role in mediating neuronal effects of stress. These peptides mediate stress responses by their interactions with the CRF receptors and the CRF‐binding protein (CRF‐BP). Because the CRF‐BP is implicated in neurotransmission within the ventral tegmental area (VTA), we investigated whether the CRF‐BP is expressed in VTA neurons. By in situ hybridization, we detected cellular expression of CRF‐BP mRNA in the VTA; no such expression was seen in neighboring substantia nigra pars compacta (SNC) or substantia nigra pars reticulata. By double in situ hybridization, we determined that VTA neurons with CRF‐BP mRNA coexpressed transcripts encoding either tyrosine hydroxylase [TH; a marker for dopamine (DA) neurons] or glutamic acid decarboxylase [GAD; synthesizing enzyme of γ‐aminobutyric acid (GABA)]. Neurons with CRF‐BP mRNA represented 25% of the total population of TH‐expressing neurons and 28% of the total population of GAD‐expressing neurons, indicating that discrete subpopulations of dopaminergic and GABAergic neurons are present in the VTA. Within the total population of neurons containing CRF‐BP mRNA, 70% coexpressed TH mRNA and only 27% coexpressed GAD mRNA. As far as we are aware, we provide the first anatomical evidence that a molecule, CRF‐BP, is encoded by DAergic neurons of the VTA but not by those of the SNC. We propose, based on the observation that the majority of VTA neurons expressing CRF‐BP mRNA are DAergic, that in the VTA interactions of CRF‐BP with CRF, or with CRF‐related peptides, are likely to be mediated predominantly by DAergic neurons. J. Comp. Neurol. 509:302–318, 2008. Published 2008 Wiley‐Liss, Inc.