6,013 research outputs found
Fast and rewritable colloidal assembly via field synchronized particle swapping
We report a technique to realize reconfigurable colloidal crystals by using
the controlled motion of particle defects above an externally modulated
magnetic substrate. The transport of particles is induced by applying a uniform
rotating magnetic field to a ferrite garnet film characterized by a periodic
lattice of magnetic bubbles. For filling factor larger than one colloid per
bubble domain, the particle current arises from propagating defects where
particles synchronously exchange their position when passing from one occupied
domain to the next. The amplitude of an applied alternating magnetic field can
be used to displace the excess particles via a swapping mechanism, or to
mobilize the entire colloidal system at a predefined speed
Phase diagram and optical conductivity of La1.8-xEu0.2SrxCuO4
La1.8-xEu0.2SrxCuO4 (LESCO) is the member of the 214 family which exhibits
the largest intervals among the structural, charge ordering (CO), magnetic, and
superconducting transition temperatures. By using new dc transport measurements
and data in the literature we construct the phase diagram of LESCO between x =
0.8 and 0.20. This phase diagram has been further probed in ac, by measuring
the optical conductivity {\sigma}1({\omega}) of three single crystals with x =
0.11, 0.125, and 0.16 between 10 and 300 K in order to associate the
extra-Drude peaks often observed in the 214 family with a given phase. The
far-infrared peak we detect in underdoped LESCO is the hardest among them,
survives up to room temperature and is associated with charge localization
rather than with ordering. At the CO transition for the commensurate doping x =
0.125 instead the extra-Drude peak hardens and a pseudogap opens in
{\sigma}1({\omega}), approximately as wide as the maximum superconducting gap
of LSCO.Comment: 6 pages, 6 figure
Strong enhancement of d-wave superconducting state in the three-band Hubbard model coupled to an apical oxygen phonon
We study the hole binding energy and pairing correlations in the three-band
Hubbard model coupled to an apical oxygen phonon, by exact diagonalization and
constrained-path Monte Carlo simulations. In the physically relevant
charge-transfer regime, we find that the hole binding energy is strongly
enhanced by the electron-phonon interaction, which is due to a novel
potential-energy-driven pairing mechanism involving reduction of both
electronic potential energy and phonon related energy. The enhancement of hole
binding energy, in combination with a phonon-induced increase of quasiparticle
weight, leads to a dramatic enhancement of the long-range part of d-wave
pairing correlations. Our results indicate that the apical oxygen phonon plays
a significant role in the superconductivity of high- cuprates.Comment: 5 pages, 5 figure
Secondary Baryon Asymmetry in pi(+-)p Collisions
The process of secondary baryon production in pi(+-)p collisions at high
energies in the central and forward fragmentation regions is considered in the
framework of the Quark-Gluon String Model. The contribution of the
string-junction mechanism to the baryon production is analysed. The results of
numerical calculations are in reasonable agreement with the experimental data
on the Lambda/bar(Lambda) and p/bar(p)$ asymmetries.Comment: Contribution to the Proceedings of QCD@Work 2007, International
Workshop on Quantum Chromodynamics, Theory and Experiment, Martina
Franca-Valle d'Itria, Italy, June 16-20, 2007 (6 pages and 4 figures
Photonic Torque Microscopy of the Nonconservative Force Field for Optically Trapped Silicon Nanowires
We
measure, by photonic torque microscopy, the nonconservative rotational
motion arising from the transverse components of the radiation pressure
on optically trapped, ultrathin silicon nanowires. Unlike spherical
particles, we find that nonconservative effects have a significant
influence on the nanowire dynamics in the trap. We show that the extreme
shape of the trapped nanowires yields a transverse component of the
radiation pressure that results in an orbital rotation of the nanowire
about the trap axis. We study the resulting motion as a function of
optical power and nanowire length, discussing its size-scaling behavior.
These shape-dependent nonconservative effects have implications for
optical force calibration and optomechanics with levitated nonspherical
particles
Composição bromatológica e digestibilidade aparente da parte aérea seca da mandioca na alimentação de tilápia-do-nilo.
O objetivo deste trabalho foi avaliar o efeito da secagem da parte aérea da mandioca, ao sol e à sombra, sobre a composição bromatológica e o coeficiente de digestibilidade aparente (CDA) de nutrientes, energia e aminoácidos para tilápia-do-nilo (Oreochromis niloticus). Não houve diferença entre os métodos de secagem para a composição bromatológica. O CDA da proteína bruta apresentou maior digestibilidade para a parte aérea seca à sombra. A secagem da parte aérea da mandioca à sombra permite maior conservação do conteúdo proteico e melhor digestibilidade aparente da fração proteica e aminoacídica para a tilápia-do-nilo
Central obesity in Yemeni children: A population based cross-sectional study
AIM: To establish percentile curves and to explore prevalence and correlates of central obesity among Yemeni children in a population based cross-sectional study. METHODS: A representative sample of 3114 Yemeni children (1564 boys, 1550 girls) aged 6-19 years participating in the HYpertension and Diabetes in Yemen study was studied. Data collection was conducted at home by survey teams composed of two investigators of both genders. Study questionnaire included questions about demographics, lifestyle, and medical history. Anthropometric measurements included body weight, height, waist circumference (WC) and hip circumferences. Waist to hip ratio (WHR) and waist-to-height ratio (WHtR) were then calculated. Age and gender specific smoothed percentiles of WC, WHR, and WHtR were obtained using lambda-mu-sigma parameters (LMS method). The independent predictors of central obesity defined as (1) WC percentile ≥ 90(th); (2) WHtR ≥ 0.5; or (3) WC percentile ≥ 90(th) and WHtR ≥ 0.5, were identified at multivariate logistic regression analysis adjusted for age, gender, urban/rural location, years of school education, sedentary/active life-style. RESULTS: Percentile curves for WC, WHR and WHtR are presented. Average WC increased with age for both genders. Boys had a higher WC than girls until early adolescence and thereafter girls had higher values than boys. WHR decreased both in boys and girls until early adolescence. Thereafter while in boys it plateaued in girls it continued to decrease. Mean WHtR decreased until early adolescence with no gender related differences and thereafter increased more in girls than in boys towards adult age. Prevalence of central obesity largely varied according to the definition used which was 10.9% for WC ≥ 90(th) percentile, 18.3% for WHtR ≥ 0.5, and 8.6% when fulfilling both criteria. At adjusted logistic regression WC ≥ 90(th) percentiles and WHtR ≥ 0.5 were less prevalent in rural than in urban areas (OR = 0.52, 95%CI: 0.41-0.67 and 0.66, 0.54-0.79 respectively), being more prevalent in children with sedentary lifestyle rather than an active one (1.52, 95%CI: 1.17-1.98 and 1.42, 95%CI: 1.14-1.75, respectively). CONCLUSION: Yemeni children central obesity indices percentile curves are presented. Central obesity prevalence varied according to the definition used and was more prevalent in urban sedentary subjects
Cosmological Models and Latest Observational Data
In this note, we consider the observational constraints on some cosmological
models by using the 307 Union type Ia supernovae (SNIa), the 32 calibrated
Gamma-Ray Bursts (GRBs) at , the updated shift parameter from WMAP
5-year data (WMAP5), and the distance parameter of the measurement of the
baryon acoustic oscillation (BAO) peak in the distribution of SDSS luminous red
galaxies with the updated scalar spectral index from WMAP5. The tighter
constraints obtained here update the ones obtained previously in the
literature.Comment: 10 pages, 5 figures, 1 table, revtex4; v2: discussions added,
accepted by Eur. Phys. J. C; v3: published versio
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