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In this paper, we investigate some applications of commutator subgroups to homotopy groups and geometric groups. In particular, we show that the intersection subgroups of some canonical subgroups in certain link groups modulo their symmetric commutator subgroups are isomorphic to the (higher) homotopy groups. This gives a connection between links and homotopy groups. Similar results hold for braid and surface groups. [ABSTRACT FROM AUTHOR]

In this paper broadband characteristics of sleeve antenna are analyzed using the Method of Moments. The sleeve antenna's property of three frequency bands is investigated. The first and third operating bands come from the driven dipole, while the second operating band is due to the height of the sleeve and the distance between the driven dipole and the sleeve. Some numerical results are presented and discussed. [ABSTRACT FROM AUTHOR]

We report on low-temperature transport measurements on four-terminal cross junction devices fabricated from high-quality graphene grown by chemical vapor deposition. At high magnetic fields, the bend resistance reveals pronounced peak structures at the quantum Hall plateau transition, which can be attributed to the edge state transport through the junctions. We further demonstrate that the bend resistance is drastically affected by the presence of local impurity states in the junction regions, and exhibits an unusual asymmetric behavior with respect to the magnetic field direction. The observations can be understood in a model taking into account the combination of the edge transport and an asymmetric scatterer. Our results demonstrate that a graphene cross junction may serve as a sensitive probe of local impurity states in graphene at the nanoscale. [ABSTRACT FROM AUTHOR]

To study the biological function of activity of bcl complex (ABC1) proteins in Lepidium apetalum Willd., genes encoding ABC1 family proteins were identified from the seed transcriptome. The sequence most closely related to germination at a low temperature was selected and gene expressions in response to low temperature stress further studied. The results show that 21 ABC1 genes were expressed in seeds germinating at the low temperature: 4 genes were upregulated, 6 were downregulated, and 11 were not significantly different from controls. The results of fluorescence quantification of the low temperature stress on the seedlings of 7-d-old L. apetalum showed that seven genes were up-regulated, six genes were down-regulated, and eight genes had no significant difference. Real-time quantitative PCR results show that under the low temperature stress, the expression of the LaAbc1-3 gene increased, but its expression decreased after some time. The expression of this gene increased again after removing the low temperature stress. The expression of LaAbc1-21 gene in L. apetalum seedlings showed a trend of decreasing first and then increasing. The LaAbc1-3 gene was insensitive to salt stress. Expression of the LaAbc1-21 gene was significantly up-regulated during the salt stress. Under osmotic stress, the expression of the LaAbc1-3 gene was down-regulated, and the expression was negatively correlated with polyethylene glycol (PEG-6000) concentration. Under the PEG-6000 treatment, the expression of the LaAbc1-21 gene was significantly up-regulated, and the expression was positively correlated with concentration. These results provide a basis for further analysis of the role of the ABC1 genes in the stress resistance of L. apetalum. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate the role of myofiber characteristics and the thickness of 2 major muscle membranes, perimysium and endomysium, in determining the breast meat tenderness of chickens. Birds from 2 breeds (White Leghorn and a line of broiler) were chosen. Chicks were sexed and wing-banded at hatch and were grown in separate cages in a single house. Sixty broilers and 60 White Leghorns were harvested at 6 wk of age, respectively, whereas another 60 White Leghorns were slaughtered at 18 wk of age. An equal number of males and females was maintained for each group. Body weight, breast muscle weight, pH, drip loss, cooking loss, WarnerBratzler shear force value (SFV), total energy of shear force, fiber diameter, sarcomere length, myofiber density, and the thickness of endomysium and perimysium of the breast were determined for each bird. At 6 wk of age, histological examination indicated that the size of myofiber and thickness of endomysium and perimysium of broilers were larger than that those of White Leghorns (P < 0.01), whereas the SFV, drip loss, and cooking loss of broilers were smaller (P < 0.01). A comparison between the White Leghorns at 18 wk and the broilers at 6 wk, which were at similar BW but different ages, showed that the breast muscle weight of broilers was larger (P < 0.01) than that of White Leghorns. For breast muscle, the endomysium of broilers at 6 wk was thicker than that of White Leghorns at 18 wk (P < 0.01), whereas the perirnysium was thinner (P < 0.01). The SFV, drip loss, and the cooking loss of broilers were smaller than those of White Leghorns at similar BW (P < 0.01). Meat tenderness was negatively correlated with myofiber density (-0.27) and the thickness of endomysium (-0.29) and positively correlated with the thickness of perimysium (0.20). It is suggested that muscle membrane should be considered in evaluating meat tenderness of the chicken. [ABSTRACT FROM AUTHOR]

Abstract. Objective and design:   Oridonin is an ent-kaurene diterpenoid extracted from Isodon Serra, and we have previously demonstrated its immunosuppressive effect. Our goal was to study how Oridonin impacts CD4+/CD25+ regulatory T cells (Tregs) and Th1/Th2 balance, as well as its effect on the anti-inflammatory target HO-1. Material:  Splenic lymphocytes were prepared from male 6–8-week-old SD rats. Treatment:  Cells were cultured in four groups as Oridonin-L (Oridonin 12.5 μmol/l), Oridonin-H (Oridonin 25 μmol/l), Cobalt protoporphyrin (Copp 50 μmol/l) and control (DMSO) with stimulation of ConA (5 μg/ml) for 48 h or with no stimulation for 12 h. Method:  We set up a model of Th1 polarization in vitro using ConA stimulation; ratios of CD4+/CD25+ Tregs (confirmed by the expression of Foxp3) were measured by flow cytometry, and levels of IL-2, IFN-γ, TGF-β and IL-10 were measured by ELISA. In addition, HO-1 expression was measured without stimulation with ConA by RT-PCR and Western blotting, and HO-1 level in vitro was then measured by enzyme activity assay. pt-test) was taken as the level of statistical significance. Result:   Oridonin promoted differentiation towards CD4+/CD25+ Tregs, inhibited IL-2 and IFN-γ but induced TGF-β and IL-10, thus rectifed the Th1 polarization. Moreover, Oridonin induced the expression of HO-1 mRNA and protein, and HO-1 activity in vitro was enhanced accordingly. Conclusion:  The results suggest that Oridonin has a distinct effect on promoting CD4+/CD25+ Treg differentiation and modulating Th1/Th2 balance, and this effect may be achieved via inducing the anti-inflammatory target HO-1. [ABSTRACT FROM AUTHOR]

The peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α) was investigated as a candidate gene for growth and fatness traits in chicken because of its prominent role in muscle fiber specialization and adipogenesis. A single nucleotide polymorphism (SNP) from C to A at position 646 of the open reading frame of chicken PGC-1α gene causing an Asp216Asn amino acid substitution was identified. The frequencies of alleles and genotypes were significantly different among 6 chicken breeds (P < 0.01). The White Plymouth Rock had the highest frequency (0.67) of allele G, whereas the White Leghorn had the lowest (0.18). The associations of the SNP with the growth and fatness traits were evaluated in 332 F2 birds from an experimental cross of White Plymouth Rock × Silkies. No association was found between the SNP and growth-related traits. However, abdominal fat weight at 12 wk of age for birds with genotype GG was 34.26 and 28.71% higher than those with genotypes AA and AG, respectively (P < 0.01), indicating that the Asp216Asn polymorphism of the PGC-1a gene could be used as a novel potential molecular marker for selection against abdominal fatness without interfering in regular breeding for growth rate of chickens. [ABSTRACT FROM AUTHOR]

Confinement and edge structures are known to play significant roles in the electronic and transport properties of two-dimensional materials. Here, we report on low-temperature magnetotransport measurements of lithographically patterned graphene cavity nanodevices. It is found that the evolution of the low-field magnetoconductance characteristics with varying carrier density exhibits different behaviors in graphene cavity and bulk graphene devices. In the graphene cavity devices, we observed that intravalley scattering becomes dominant as the Fermi level gets close to the Dirac point. We associate this enhanced intravalley scattering to the effect of charge inhomogeneities and edge disorder in the confined graphene nanostructures. We also observed that the dephasing rate of carriers in the cavity devices follows a parabolic temperature dependence, indicating that the direct Coulomb interaction scattering mechanism governs the dephasing at low temperatures. Our results demonstrate the importance of confinement in carrier transport in graphene nanostructure devices. [ABSTRACT FROM AUTHOR]

The article discusses the discovery of pitted terrain on the surface of the asteroid Vesta in images captured by the Dawn spacecraft. It is suggested that the pitted geology of Vesta was formed through a degassing process similar to the one implicated in the formation of pitted surfaces in craters on the planet Mars, which would indicate the possible presence of volatile substances on the asteroid. Other topics include the delivery of volatiles by impacts of exogenic carbonaceous chondrites, the observation of hydrogen on Vesta, and the absence of pitted features on the surface of the Moon.

Vesta's surface is characterized by abundant impact craters, some with preserved ejecta blankets, large troughs extending around the equatorial region, enigmatic dark material, and widespread mass wasting, but as yet an absence of volcanic features. Abundant steep slopes indicate that impact-generated surface regolith is underlain by bedrock. Dawn observations confirm the large impact basin (Rheasilvia) at Vesta's south pole and reveal evidence for an earlier, underlying large basin (Veneneia). Vesta's geology displays morphological features characteristic of the Moon and terrestrial planets as well as those of other asteroids, underscoring Vesta's unique rote as a transitional solar system body. [ABSTRACT FROM AUTHOR]

Morphotropic phase boundaries (MPBs) in ferroelectrics are highly desired phase transition regions, where crystal structure becomes extremely susceptible to external stimuli leading to very large electromechanical responses with applications in high-performance piezoelectric actuators and sensors. Since the recent discovery of a strain-driven MPB in chemically simple oxides, especially in thin films of BiFeO3 (BFO), much of the research emphasis has been on the physical structural MPBs which spatially separate intimately mixed phases in corrugated nanoscale regions. Very large electromechanical responses and other coupled novel functionalities, i.e. magnetism and electronic conductivity have been observed at such physical structural MPBs. In this report, we investigate and identify a region in the thickness-dependent phase diagram of the morphotropic BFO thin films at which a superior piezoelectric performance is achieved. In this region, an electrically recoverable strain approximately 40% higher than the previously reported values for the morphotropic BFO is observed. This enhanced electromechanical coupling has been attributed to the degeneracy of the mixed-phase states and concurrent increased mechanical softening. [ABSTRACT FROM AUTHOR]

We systematically analyze the X-ray variability of active galactic nuclei (AGNs) in the 7 Ms Chandra Deep Field-South survey. On the longest timescale (≈17 years), we find only a weak (if any) dependence of X-ray variability amplitudes on energy bands or obscuration. We use four different power spectral density (PSD) models to fit the anticorrelation between normalized excess variance () and luminosity, and obtain a best-fit power-law index for the low-frequency part of the AGN PSD. We also divide the whole light curves into four epochs in order to inspect the dependence of on these timescales, finding an overall increasing trend. The analysis of these shorter light curves also infers a β of ∼1.3 that is consistent with the above-derived β, which is larger than the frequently assumed value of . We then investigate the evolution of . No definitive conclusion is reached because of limited source statistics, but if present, the observed trend goes in the direction of decreasing AGN variability at fixed luminosity toward high redshifts. We also search for transient events and find six notable candidate events with our considered criteria. Two of them may be a new type of fast transient events, one of which is reported here for the first time. We therefore estimate a rate of fast outbursts and a tidal disruption event (TDE) rate assuming the other four long outbursts to be TDEs. [ABSTRACT FROM AUTHOR]