970 research outputs found
Analytical investigation of magnetic field distributions around superconducting strips on ferromagnetic substrates
The complex-field approach is developed to derive analytical expressions of
the magnetic field distributions around superconducting strips on ferromagnetic
substrates (SC/FM strips). We consider the ferromagnetic substrates as ideal
soft magnets with an infinite magnetic permeability, neglecting the
ferromagnetic hysteresis. On the basis of the critical state model for a
superconducting strip, the ac susceptibility of a SC/FM
strip exposed to a perpendicular ac magnetic field is theoretically
investigated, and the results are compared with those for superconducting
strips on nonmagnetic substrates (SC/NM strips). The real part for
(where is the amplitude of the ac magnetic field,
is the critical current density, and is the thickness of the
superconducting strip) of a SC/FM strip is 3/4 of that of a SC/NM strip. The
imaginary part (or ac loss ) for of a SC/FM
strip is larger than that of a SC/NM strip, even when the ferromagnetic
hysteresis is neglected, and this enhancement of (or ) is due to
the edge effect of the ferromagnetic substrate.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
Protein processing characterized by a gel-free proteomics approach
We describe a method for the specific isolation of representative N-terminal peptides of proteins and their proteolytic fragments. Their isolation is based on a gel-free, peptidecentric proteomics approach using the principle of diagonal chromatography. We will indicate that the introduction of an altered chemical property to internal peptides holding a free α-N-terminus results in altered column retention of these peptides, thereby enabling the isolation and further characterization by mass spectrometry of N-terminal peptides. Besides pointing to changes in protein expression levels when performing such proteome surveys in a differential modus, protease specificity and substrate repertoires can be allocated since both are specified by neo-N-termini generated after a protease cleavage event. As such, our gel-free proteomics technology is widely applicable and amenable for a variety of proteome-driven protease degradomics research
Deformation of NaCoF3 perovskite and post-perovskite up to 30 GPa and 1013 K: implications for plastic deformation and transformation mechanism
Texture, plastic deformation, and phase transformation mechanisms in perovskite and post-perovskite are of general interest for our understanding of the Earth's mantle. Here, the perovskite analogue NaCoF3 is deformed in a resistive-heated diamond anvil cell (DAC) up to 30 GPa and 1013 K. The in situ state of the sample, including crystal structure, stress, and texture, is monitored using X-ray diffraction. A phase transformation from a perovskite to a post-perovskite structure is observed between 20.1 and 26.1 GPa. Normalized stress drops by a factor of 3 during transformation as a result of transient weakening during the transformation. The perovskite phase initially develops a texture with a maximum at 100 and a strong 010 minimum in the inverse pole figure of the compression direction. Additionally, a secondary weaker 001 maximum is observed later during compression. Texture simulations indicate that the initial deformation of perovskite requires slip along (100) planes with significant contributions of {110} twins. Following the phase transition to post-perovskite, we observe a 010 maximum, which later evolves with compression. The transformation follows orientation relationships previously suggested where the c axis is preserved between phases and hh0 vectors in reciprocal space of post-perovskite are parallel to [010] in perovskite, which indicates a martensitic-like transition mechanism. A comparison between past experiments on bridgmanite and current results indicates that NaCoF3 is a good analogue to understand the development of microstructures within the Earth's mantle
Low-Rank Decompositions of Three-Nucleon Forces via Randomized Projections
Ab initio calculations for nuclei and nuclear matter are limited by the
computational requirements of processing large data objects. In this work, we
develop low-rank singular value decompositions for chiral three-nucleon
interactions, which dominate these limitations. In order to handle the large
dimensions in representing three-body operators, we use randomized
decomposition techniques. We study in detail the sensitivity of different
three-nucleon topologies to low-rank matrix factorizations. The developed
low-rank three-nucleon interactions are benchmarked in Faddeev calculations of
the triton and ab initio calculations of medium-mass nuclei. Exploiting
low-rank properties of nuclear interactions will be particularly important for
the extension of ab initio studies to heavier and deformed systems, where
storage requirements will exceed the computational capacities of the most
advanced high-performance-computing facilities.Comment: 7 pages, 4 figure
Anti-self-dual Maxwell solutions on hyperk\"ahler manifold and N=2 supersymmetric Ashtekar gravity
Anti-self-dual (ASD) Maxwell solutions on 4-dimensional hyperk\"ahler
manifolds are constructed. The N=2 supersymmetric half-flat equations are
derived in the context of the Ashtekar formulation of N=2 supergravity. These
equations show that the ASD Maxwell solutions have a direct connection with the
solutions of the reduced N=2 supersymmetric ASD Yang-Mills equations with a
special choice of gauge group. Two examples of the Maxwell solutions are
presented.Comment: 9 page
Seleção de tamanho de partÃculas por bovinos Nelore Mocho e sua relação com o desempenho animal em confinamento.
Em estudos com animais de produção em confinamento são verificadas diferenças individuais em relação ao consumo alimentar, tanto em quantidade como qualidade, entretanto, pouco se sabe da influencia da seleção no desempenho. Assim, objetivou-se avaliar se a seletividade por tamanho de partÃcula no cocho tem relação com o desempenho de bovinos Nelore Mocho. O experimento foi realizado na área de confinamento de junho a novembro de 2012. Foram utilizados 18 animais, com idade e peso médio iniciais de 21 meses e 335 kg, respectivamente, provenientes do rebanho da marca OB. Os animais foram abatidos com idade e o peso médio de 23 meses e 535 kg, e espessura de gordura mÃnima de 5 mm. Foi mantido um registro diário do ofertado e das sobras recolhidas, por animal. Avaliou-se o tamanho médio de partÃculas restantes no cocho pelo método Penn State a cada quatro horas diárias. Fez-se uso de análises de Cluster para agrupar os animais conforme seletividade por partÃculas consumidas. As médias foram ajustadas pelo método dos mÃnimos quadrados e comparadas por meio do teste de Tukey a 5% de probabilidade. Apesar do comportamento seletivo diferenciado, em relação ao tamanho de partÃculas, não houve diferença estatisticamente significativa entre os grupos de seleção alimentar (p>0,05) para as caracterÃsticas de desempenho dos animais. Conclui-se que a seletividade por tamanho de partÃculas no cocho não implicam em alterações no desempenho de bovinos de corte em confinamento. Abstract: Studies with feedlot livestock have identified quantitative and qualitative differences as it relates to individual food intake. The objective of this study was to evaluate if the food selection based on particle size in the trough was associated with the performance of Polled Nelore cattle. The experiment was conducted in the confinement, from June to November 2012. Eighteen OB brand animals were studied, with respective baseline age and average weight of 21 months and 335 kg. The animals were slaughtered at an average age and weight of 23 months and 535 kg, and minimal subcutaneous thickness of 5 mm. A registry of the daily intake was kept. The Penn State method and leftover scores were used to analyze the average size of the particles at four hour a day of feeding. Cluster analysis was used to group animals according to particle size selectivity for food intake. Least square method was used to adjust averages and Tukey?s test was used for comparison at 5% probability level. Despite the different selective behavior related to particle sizes, there were no statistically significant differences (p>0.05) among all animal performance characteristics. It was concluded particle size selectivity not affect performance variables of confined beef cattle
Evidence that histidine protonation of receptor-bound anthrax protective antigen is a trigger for pore formation
The protective antigen (PA) component of the anthrax toxin forms pores within the low pH environment of host endosomes, through mechanisms that are poorly understood. It has been proposed that pore formation is dependent on histidine protonation. In previous work, we biosynthetically incorporated 2-fluorohistidine (2-FHis), an isosteric analog of histidine with a significantly reduced pKa (~1), into PA, and showed that the pH-dependent conversion from the soluble prepore to a pore was unchanged. However, we also observed that 2-FHisPA was non-functional in the ability to mediate cytotoxicity of CHO-K1 cells by LFN-DTA, and was defective in translocation through planar lipid bilayers. Here, we show that the defect in cytotoxicity is due to both a defect in translocation and, when bound to the host cellular receptor, an inability to undergo low pH-induced pore formation. Combining X-ray crystallography with hydrogen-deuterium (H-D) exchange mass spectrometry, our studies lead to a model in which hydrogen bonds to the histidine ring are strengthened by receptor binding. The combination of both fluorination and receptor binding is sufficient to block low pH-induced pore formation
Seleção de tamanho de partÃculas por bovinos Nelore em confinamento e sua relação com caracterÃsticas de carcaça.
Pesquisas apresentam a existência de variação individual em relação ao comportamento alimentar de bovinos confinados, mesmo estando na mesma baia de confinamento. Objetivou-se avaliar se a seletividade por tamanho de partÃcula no cocho tem relação com as caracterÃsticas de carcaça de bovinos Nelore Mocho. O experimento foi realizado na área de confinamento de junho a novembro de 2012. Foram utilizados 18 animais, com idade e peso médio iniciais de 21 meses e 335 kg, respectivamente, provenientes do rebanho da marca OB. Os animais foram abatidos com idade e o peso médio de 23 meses e 535 kg, e espessura de gordura mÃnima de 5 mm. Foi mantido um registro diário do ofertado e das sobras recolhidas, por animal. Avaliou-se o tamanho médio de partÃculas restantes no cocho pelo método Penn State a cada quatro horas diárias. Fez-se uso de análises de Cluster para agrupar os animais conforme seletividade por partÃculas consumidas. As médias foram ajustadas pelo método dos mÃnimos quadrados e comparadas por meio do teste de Tukey a 5% de probabilidade. Apesar do comportamento seletivo diferenciado, em relação ao tamanho de partÃculas, não houve diferença estatÃstica significativa entre os grupos de seleção alimentar (p>0,05) para as caracterÃsticas de carcaça dos animais. Conclui-se que a seletividade por tamanho de partÃculas no cocho não implicam em alterações nas caracterÃsticas de carcaça de bovinos de corte em confinamento. Abstract: Studies with feedlot livestock have identified quantitative and qualitative differences as it relates to individual food intake. The objective of this study was to evaluate if the food selection based on particle size in the trough was associated carcass characteristics of Nelore Mocho cattle. The experiment was conducted in the confinement, from June to November 2012. Eighteen OB brand animals were studied, with respective baseline age and average weight of 21 months and 335 kg. The animals were slaughtered at an average age and weight of 23 months and 515 kg, and minimal subcutaneous thickness of 5 mm. A registry of the daily intake was kept. The Penn State method and leftover scores were used to analyze the average size of the particles at four hour a day of feeding. Cluster analysis was used to group animals according to particle size selectivity for food intake. Least square method was used to adjust averages and Tukey?s test was used for comparison at 5% probability level. Despite the different selective behavior related to particle sizes, there were no statistically significant differences (p>0.05) among carcass characteristics. It was concluded particle size selectivity not affect carcass characteristics of confined beef cattle
Anestesia local y Sedación para Intubación con Fibrobroncoscopio de paciente con VÃa Aérea DifÃcil
Presentamos el caso clÃnico de un varón de 60 años con vÃa aérea difÃcil que debÃa realizarse una tiroidectomÃa total por el diagnóstico de bocio multinodular tóxico y que, un mes antes, habÃa tenido un intento fallido de intubación con fibrobroncoscopio
Isomeric excitation energy for In from mass spectrometry reveals constant trend next to doubly magic Sn
The excitation energy of the 1/2 isomer in In at is
measured to be 671(37) keV and the mass uncertainty of the 9/2 ground state
is significantly reduced using the ISOLTRAP mass spectrometer at ISOLDE/CERN.
The measurements exploit a major improvement in the resolution of the
multi-reflection time-of-flight mass spectrometer. The results reveal an
intriguing constancy of the isomer excitation energies in
neutron-deficient indium that persists down to the shell closure, even
when all neutrons are removed from the valence shell. This trend is used to
test large-scale shell model, \textit{ab initio}, and density functional theory
calculations. The models have difficulties describing both the isomer
excitation energies and ground-state electromagnetic moments along the indium
chain.Comment: 13 pages, 4 figure
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