1,496 research outputs found
Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach
We use a Green's function method to study the temperature-dependent average
moment and magnetic phase-transition temperature of the striped
antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of
FeAs-based superconductors. We consider the nearest and the next-nearest
couplings in the FeAs layer, and the nearest coupling for inter-layer spin
interaction. The dependence of the transition temperature TN and the
zero-temperature average spin on the interaction constants is investigated. We
obtain an analytical expression for TN and determine our temperature-dependent
average spin from zero temperature to TN in terms of unified self-consistent
equations. For LaFeAsO, we obtain a reasonable estimation of the coupling
interactions with the experimental transition temperature TN = 138 K. Our
results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling
is essential for the existence of a non-zero TN, and the many-body AFM
fluctuations reduce substantially the low-temperature magnetic moment per Fe
towards the experimental value. Our Green's function approach can be used for
other FeAs-based parent compounds and these results should be useful to
understand the physical properties of FeAs-based superconductors.Comment: 12 page
Shape complexity and fractality of fracture surfaces of swelled isotactic polypropylene with supercritical carbon dioxide
We have investigated the fractal characteristics and shape complexity of the
fracture surfaces of swelled isotactic polypropylene Y1600 in supercritical
carbon dioxide fluid through the consideration of the statistics of the islands
in binary SEM images. The distributions of area , perimeter , and shape
complexity follow power laws , , and , with the scaling ranges spanning
over two decades. The perimeter and shape complexity scale respectively as
and in two scaling regions delimited by . The fractal dimension and shape complexity increase when the temperature
decreases. In addition, the relationships among different power-law scaling
exponents , , , , and have been derived analytically,
assuming that , , and follow power-law distributions.Comment: RevTex, 6 pages including 7 eps figure
Developments of a 2D Position Sensitive Neutron Detector
Chinese Spallation Neutron Source (CSNS), one project of the 12th
five-year-plan scheme of China, is under construction in Guangdong province.
Three neutron spectrometers will be installed at the first phase of the
project, where two-dimensional position sensitive thermal neutron detectors are
required. Before the construction of the neutron detector, a prototype of
two-dimensional 200 mmx200 mm Multi-wire Proportional Chamber (MWPC) with the
flowing gas of Ar/CO2 (90/10) has been constructed and tested with the 55Fe
X-Ray using part of the electronics in 2009, which showed a good performance.
Following the test in 2009, the neutron detector has been constructed with the
complete electronics and filled with the 6atm.3He + 2.5atm.C3H8 gas mixture in
2010. The neutron detector has been primarily tested with an Am/Be source. In
this paper, some new developments of the neutron detector including the design
of the high pressure chamber, the optimization of the gas purifying system and
the gas filling process will be reported. The results and discussion are also
presented in this paper.Comment: 5 page
Complete mitochondrial genomes of Taenia multiceps, T. hydatigena and T. pisiformis: additional molecular markers for a tapeworm genus of human and animal health significance
<p>Abstract</p> <p>Background</p> <p>Mitochondrial genomes provide a rich source of molecular variation of proven and widespread utility in molecular ecology, population genetics and evolutionary biology. The tapeworm genus <it>Taenia </it>includes a diversity of tapeworm parasites of significant human and veterinary importance. Here we add complete sequences of the mt genomes of <it>T. multiceps</it>, <it>T. hydatigena </it>and <it>T. pisiformis</it>, to a data set of 4 published mtDNAs in the same genus. Seven complete mt genomes of <it>Taenia </it>species are used to compare and contrast variation within and between genomes in the genus, to estimate a phylogeny for the genus, and to develop novel molecular markers as part of an extended mitochondrial toolkit.</p> <p>Results</p> <p>The complete circular mtDNAs of <it>T. multiceps</it>, <it>T. hydatigena </it>and <it>T. pisiformis </it>were 13,693, 13,492 and 13,387 bp in size respectively, comprising the usual complement of flatworm genes. Start and stop codons of protein coding genes included those found commonly amongst other platyhelminth mt genomes, but the much rarer initiation codon GTT was inferred for the gene <it>atp</it>6 in <it>T. pisiformis</it>. Phylogenetic analysis of mtDNAs offered novel estimates of the interrelationships of <it>Taenia</it>. Sliding window analyses showed <it>nad</it>6, <it>nad</it>5, <it>atp</it>6, <it>nad</it>3 and <it>nad</it>2 are amongst the most variable of genes per unit length, with the highest peaks in nucleotide diversity found in <it>nad</it>5. New primer pairs capable of amplifying fragments of variable DNA in <it>nad</it>1, <it>rrn</it>S and <it>nad</it>5 genes were designed <it>in silico </it>and tested as possible alternatives to existing mitochondrial markers for <it>Taenia</it>.</p> <p>Conclusions</p> <p>With the availability of complete mtDNAs of 7 <it>Taenia </it>species, we have shown that analysis of amino acids provides a robust estimate of phylogeny for the genus that differs markedly from morphological estimates or those using partial genes; with implications for understanding the evolutionary radiation of important <it>Taenia</it>. Full alignment of the nucleotides of <it>Taenia </it>mtDNAs and sliding window analysis suggests numerous alternative gene regions are likely to capture greater nucleotide variation than those currently pursued as molecular markers. New PCR primers developed from a comparative mitogenomic analysis of <it>Taenia </it>species, extend the use of mitochondrial markers for molecular ecology, population genetics and diagnostics.</p
Strength of Coronal Mass Ejection-Driven Shocks Near the Sun, and Its Importance in Predicting Solar Energetic Particle Events
Coronal shocks are important structures, but there are no direct observations
of them in solar and space physics. The strength of shocks plays a key role in
shock-related phenomena, such as radio bursts and solar energetic particle
(SEP) generation. This paper presents an improved method of calculating Alfven
speed and shock strength near the Sun. This method is based on using as many
observations as possible, rather than one-dimensional global models. Two
events, a relatively slow CME on 2001 September 15 and a very fast CME on 2000
June 15, are selected to illustrate the calculation process. The calculation
results suggest that the slow CME drove a strong shock, with Mach number of
3.43 - 4.18, while the fast CME drove a relatively weak shock, with Mach number
of 1.90 - 3.21. This is consistent with the radio observations, which find a
stronger and longer decameter-hectometric (DH) type II radio burst during the
first event, and a short DH type II radio burst during the second event. In
particular, the alculation results explain the observational fact that the slow
CME produced a major solar energetic particle (SEP) event, while the fast CME
did not. Through a comparison of the two events, the importance of shock
strength in predicting SEP events is addressed
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Miles to go (mtgo) encodes FNDC3 proteins that interact with the chaperonin subunit CCT3 and are required for NMJ branching and growth in Drosophila.
Analysis of mutants that affect formation and function of the Drosophila larval neuromuscular junction (NMJ) has provided valuable insight into genes required for neuronal branching and synaptic growth. We report that NMJ development in Drosophila requires both the Drosophila ortholog of FNDC3 genes; CG42389 (herein referred to as miles to go; mtgo), and CCT3, which encodes a chaperonin complex subunit. Loss of mtgo function causes late pupal lethality with most animals unable to escape the pupal case, while rare escapers exhibit an ataxic gait and reduced lifespan. NMJs in mtgo mutant larvae have dramatically reduced branching and growth and fewer synaptic boutons compared with control animals. Mutant larvae show normal locomotion but display an abnormal self-righting response and chemosensory deficits that suggest additional functions of mtgo within the nervous system. The pharate lethality in mtgo mutants can be rescued by both low-level pan- and neuronal-, but not muscle-specific expression of a mtgo transgene, supporting a neuronal-intrinsic requirement for mtgo in NMJ development. Mtgo encodes three similar proteins whose domain structure is most closely related to the vertebrate intracellular cytosolic membrane-anchored fibronectin type-III domain-containing protein 3 (FNDC3) protein family. Mtgo physically and genetically interacts with Drosophila CCT3, which encodes a subunit of the TRiC/CCT chaperonin complex required for maturation of actin, tubulin and other substrates. Drosophila larvae heterozygous for a mutation in CCT3 that reduces binding between CCT3 and MTGO also show abnormal NMJ development similar to that observed in mtgo null mutants. Hence, the intracellular FNDC3-ortholog MTGO and CCT3 can form a macromolecular complex, and are both required for NMJ development in Drosophila
In vivo and in vitro studies of Th17 response to specific immunotherapy in house dust mite-induced allergic rhinitis patients
10.1371/journal.pone.0091950PLoS ONE93-POLN
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Temporal and spectral multiplexing for EUV multibeam ptychography with a high harmonic light source
We demonstrate temporally multiplexed multibeam ptychography implemented for the first time in the EUV, by using a high harmonic based light source. This allows for simultaneous imaging of different sample areas, or of the same area at different times or incidence angles. Furthermore, we show that this technique is compatible with wavelength multiplexing for multibeam spectroscopic imaging, taking full advantage of the temporal and spectral characteristics of high harmonic light sources. This technique enables increased data throughput using a simple experimental implementation and with high photon efficiency.
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ZIP: a novel transcription repressor, represses EGFR oncogene and suppresses breast carcinogenesis
Negative effect of cyclin D1 overexpression on recurrence-free survival in stage II-IIIA lung adenocarcinoma and its expression modulation by vorinostat in vitro
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