5,567 research outputs found
Detecting Repetitions and Periodicities in Proteins by Tiling the Structural Space
The notion of energy landscapes provides conceptual tools for understanding
the complexities of protein folding and function. Energy Landscape Theory
indicates that it is much easier to find sequences that satisfy the "Principle
of Minimal Frustration" when the folded structure is symmetric (Wolynes, P. G.
Symmetry and the Energy Landscapes of Biomolecules. Proc. Natl. Acad. Sci.
U.S.A. 1996, 93, 14249-14255). Similarly, repeats and structural mosaics may be
fundamentally related to landscapes with multiple embedded funnels. Here we
present analytical tools to detect and compare structural repetitions in
protein molecules. By an exhaustive analysis of the distribution of structural
repeats using a robust metric we define those portions of a protein molecule
that best describe the overall structure as a tessellation of basic units. The
patterns produced by such tessellations provide intuitive representations of
the repeating regions and their association towards higher order arrangements.
We find that some protein architectures can be described as nearly periodic,
while in others clear separations between repetitions exist. Since the method
is independent of amino acid sequence information we can identify structural
units that can be encoded by a variety of distinct amino acid sequences
COLA. III. Radio Detection of Active Galactic Nucleus in Compact Moderate Luminosity Infrared Galaxies
We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_(IR) = 10^(11.01) L_☉) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^(21) W Hz^(–1)) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity
Neutron-Diffraction Study of γ-Fe at High Pressure
Face-centered-cubic iron (γ-Fe) coherently precipitated in a single crystal of Cu has been studied by neutron diffraction at high pressures up to 0.9 GPa and in the temperature range from about 5 to 110 K. It undergoes antiferromagnetic ordering at 67±2 K at ambient pressure. The ordering temperature TN monotonically decreases with increasing pressure following a relation TN(K)=67-12.8p - 11.1p2 - 6.17p3, where p is in units of GPa. The change of TN in γ-Fe is discussed in terms of the volume change caused by pressurization or by alloying
Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements
We investigate the effect of varying the ion temperature gradient (ITG) and
toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer
core of MAST by means of local gyrokinetic simulations. We show that nonlinear
simulations reproduce the experimental ion heat flux and that the
experimentally measured values of the ITG and the flow shear lie close to the
turbulence threshold. We demonstrate that the system is subcritical in the
presence of flow shear, i.e., the system is formally stable to small
perturbations, but transitions to a turbulent state given a large enough
initial perturbation. We propose that the transition to subcritical turbulence
occurs via an intermediate state dominated by low number of coherent long-lived
structures, close to threshold, which increase in number as the system is taken
away from the threshold into the more strongly turbulent regime, until they
fill the domain and a more conventional turbulence emerges. We show that the
properties of turbulence are effectively functions of the distance to
threshold, as quantified by the ion heat flux. We make quantitative comparisons
of correlation lengths, times, and amplitudes between our simulations and
experimental measurements using the MAST BES diagnostic. We find reasonable
agreement of the correlation properties, most notably of the correlation time,
for which significant discrepancies were found in previous numerical studies of
MAST turbulence.Comment: 67 pages, 37 figures. Submitted to PPC
Atividade diurna de adultos de Diabrótica speciosa na cultura do milho e de cerotoma arcuatus na cultura da soja.
Neste documento são apresentadas importantes informações sobre o ritmo de atividade diurna de adultos de D. speciosa, na cultura do milho, e de C. arcuatus na cultura da soja. Assim, as informações contidas neste trabalho são de grande valia, pois podem auxiliar na definição de táticas para o manejo dessas pragas.bitstream/item/38187/1/DOC200464.pd
Life table analysis of Diaphorina citri (Hemiptera: Psyllidae) infesting sweet orange (Citrus sinensis) in São Paulo
An ecological life table for eggs and nymphs of Diaphorina citri Kuwayama (Hemiptera:
Psyllidae) was constructed with data obtained from orange orchards (Citrus sinensis Osbeck) in 2 regions of the State of São Paulo, over 4 generations in the period from XI-2006
to V-2007, comprising spring, summer, and fall seasons. Young growing shoots with D. citri
eggs present were identifed, and live individuals were counted until adult emergence. No
predatory arthropods were observed in association with D. citri eggs and nymphs during
the study. The mean parasitism of fourth- and ffth-instar nymphs by Tamarixia radiata
Waterston (Hymenoptera: Eulophidae) was 2.3%. The durations of the egg–adult period
were similar among the 4 generations, ranging from 18.0 to 24.7 d (at mean temperatures
ranging from 21.6 to 26.0 °C) and followed the temperature requirement models obtained
in the laboratory for D. citri. However, survival from the egg to the adult stage for the same
period varied considerably from 1.7 to 21.4%; the highest mortalities were observed in the
egg and small nymphal (frst- to thirdinstar) stages, which were considered to be key phases
for population growth of the pest.Uma tabela de vida ecológica foi construída para ovos e ninfas de Diaphorina citri Kuwayama (Hemiptera: Psyllidae) com dados obtidos em pomares de laranja (Citrus sinensis Osbeck) em 2 regiões do estado de São Paulo, com 4 gerações, no período de novembro de 2006
a maio de 2007, compreendendo as estações de primavera, verão e outono. Ramos jovens
em crescimento com a presença de ovos de D. citri foram identificados e os indivíduos vivos
foram contados até a emergência dos adultos. Nenhum predador foi observado associado a
ovos e ninfas de D. citri durante o estudo. A taxa média de parasitismo de ninfas de quarto
e quinto ínstares por Tamarixia radiata Waterson (Hymenoptera: Eulophidae) foi de 2.3%.
A duração do período de ovo a adulto foi semelhante entre as quatro gerações, variando de
18.0 a 24.7 dias (com temperaturas médias de 21.6 a 26.0 °C) e seguiram os modelos de
exigencias térmicas obtidas em laboratório para D. citri. Todavia, a sobrevivencia de ovo
até o estágio adulto variou consideravelmente para o mesmo período, de 1.7 a 21.4%, sendo
que as maiores mortalidades foram observadas nos estágios de ovos e ninfas pequenas (de
primeiro a terceiro ínstares), as quais foram consideradas fases chaves para o crescimento
populacional desta praga.info:eu-repo/semantics/publishedVersio
Adolescent Reactions to Maternal Responsiveness and Internalizing Symptomatology: A Daily Diary Investigation
A daily diary methodology was employed to gather teens’ perceptions of maternal responsiveness to daily stressful events and teens’ reactions to maternal responsiveness in a diverse sample (792 entries from 104 teens; 81% African American, mean age 13.7 years). Additionally, parents and teens completed baseline reports of internalizing symptoms. Diary findings were congruent with prior studies employing self-report measures of global maternal responses to emotion (e.g., higher probability of Accepting reactions to supportive responses, higher probabilities of Attack, Avoid-Withdraw reactions to non-supportive responses). Elevated baseline internalizing symptoms were related to perception of elevated Punish and Magnify responses during the week, and more Avoidant (Avoid-Withdraw and Avoid-Protect) reactions to responsiveness. Results are discussed in the context of reciprocal emotion socialization processes
Murine models susceptibility to distinct Trypanosoma cruzi i genotypes infection
Chagas disease is a complex zoonosis that affects around 8 million people worldwide. This pathology is caused by Trypanosoma cruzi, a kinetoplastid parasite that shows tremendous genetic diversity evinced in six distinct Discrete Typing Units (TcI-TcVI) including a recent genotype named as TcBat and associated with anthropogenic bats. TcI presents a broad geographical distribution and has been associated with chronic cardiomyopathy. Recent phylogenetic studies suggest the existence of two genotypes (Domestic (TcIDom) and sylvatic TcI) within TcI. The understanding of the course of the infection in different mouse models by these two genotypes is not yet known. Therefore, we infected 126 animals (ICR-CD1, National Institute of Health (NIH) and Balb/c) with two TcIDom strains and one sylvatic strain for a follow-up period of 60 days. We quantified the parasitaemia, immune response and histopathology observing that the maximum day of parasitaemia was achieved at day 21 post-infection. Domestic strains showed higher parasitaemia than the sylvatic strain in the three mouse models; however in the survival curves Balb/c mice were less susceptible to infection compared with NIH and ICR-CD1. Our results suggest that the genetic background plays a fundamental role in the natural history of the infection and the sympatric TcI genotypes have relevant implications in disease pathogenesis. © 2016 Cambridge University Press
Perpendicular momentum injection by lower hybrid wave in a tokamak
The injection of lower hybrid waves for current drive into a tokamak affects
the profile of intrinsic rotation. In this article, the momentum deposition by
the lower hybrid wave on the electrons is studied. Due to the increase in the
poloidal momentum of the wave as it propagates into the tokamak, the parallel
momentum of the wave increases considerably. The change of the perpendicular
momentum of the wave is such that the toroidal angular momentum of the wave is
conserved. If the perpendicular momentum transfer via electron Landau damping
is ignored, the transfer of the toroidal angular momentum to the plasma will be
larger than the injected toroidal angular momentum. A proper quasilinear
treatment proves that both perpendicular and parallel momentum are transferred
to the electrons. The toroidal angular momentum of the electrons is then
transferred to the ions via different mechanisms for the parallel and
perpendicular momentum. The perpendicular momentum is transferred to ions
through an outward radial electron pinch, while the parallel momentum is
transferred through collisions.Comment: 22 pages, 4 figure
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