19,958 research outputs found
The lowest-lying baryon masses in covariant SU(3)-flavor chiral perturbation theory
We present an analysis of the baryon-octet and -decuplet masses using
covariant SU(3)-flavor chiral perturbation theory up to next-to-leading order.
Besides the description of the physical masses we address the problem of the
lattice QCD extrapolation. Using the PACS-CS collaboration data we show that a
good description of the lattice points can be achieved at next-to-leading order
with the covariant loop amplitudes and phenomenologically determined values for
the meson-baryon couplings. Moreover, the extrapolation to the physical point
up to this order is found to be better than the linear one given at
leading-order by the Gell-Mann-Okubo approach. The importance that a reliable
combination of lattice QCD and chiral perturbation theory may have for hadron
phenomenology is emphasized with the prediction of the pion-baryon and
strange-baryon sigma terms.Comment: Typos in formulas correcte
Progressive managerial bonuses in a spatial Bertrand duopoly
The relationship of managerial bonuses and profit maximization is interesting both from an economic and a managerial viewpoint. Our contribution to this literature is showing that progressive managerial bonuses can increase profits in a spatial Bertrand competition, and furthermore they can help collusion
Spin precession and inverted Hanle effect in a semiconductor near a finite-roughness ferromagnetic interface
Although the creation of spin polarization in various non-magnetic media via
electrical spin injection from a ferromagnetic tunnel contact has been
demonstrated, much of the basic behavior is heavily debated. It is reported
here for semiconductor/Al2O3/ferromagnet tunnel structures based on Si or GaAs
that local magnetostatic fields arising from interface roughness dramatically
alter and even dominate the accumulation and dynamics of spins in the
semiconductor. Spin precession in the inhomogeneous magnetic fields is shown to
reduce the spin accumulation up to tenfold, and causes it to be inhomogeneous
and non-collinear with the injector magnetization. The inverted Hanle effect
serves as experimental signature. This interaction needs to be taken into
account in the analysis of experimental data, particularly in extracting the
spin lifetime and its variation with different parameters (temperature, doping
concentration). It produces a broadening of the standard Hanle curve and
thereby an apparent reduction of the spin lifetime. For heavily doped n-type Si
at room temperature it is shown that the spin lifetime is larger than
previously determined, and a new lower bound of 0.29 ns is obtained. The
results are expected to be general and occur for spins near a magnetic
interface not only in semiconductors but also in metals, organic and
carbon-based materials including graphene, and in various spintronic device
structures.Comment: Final version, with text restructured and appendices added (25 pages,
9 figures). To appear in Phys. Rev.
Reweighting towards the chiral limit
We propose to perform fully dynamical simulations at small quark masses by
reweighting in the quark mass. This approach avoids some of the technical
difficulties associated with direct simulations at very small quark masses. We
calculate the weight factors stochastically, using determinant breakup and low
mode projection to reduce the statistical fluctuations. We find that the weight
factors fluctuate only moderately on nHYP smeared dynamical Wilson-clover
ensembles, and we could successfully reweight 16^4, (1.85fm)^4 volume
configurations from m_q = 20MeV to m_q = 5MeV quark masses, reaching the
epsilon-regime. We illustrate the strength of the method by calculating the low
energy constant F from the epsilon-regime pseudo-scalar correlator.Comment: 17 pages, 8 figure
Radiation hardness of small-pitch 3D pixel sensors up to HL-LHC fluences
A new generation of 3D silicon pixel detectors with a small pixel size of
5050 and 25100 m is being developed for the HL-LHC
tracker upgrades. The radiation hardness of such detectors was studied in beam
tests after irradiation to HL-LHC fluences up to
n/cm. At this fluence, an operation voltage of only 100 V
is needed to achieve 97% hit efficiency, with a power dissipation of 13
mW/cm at -25C, considerably lower than for previous 3D sensor
generations and planar sensors.Comment: 5 pages, 2 figures, Proceedings of TIPP 2017, Beijing (International
Conference on The Technology and Instrumentation in Particle Physics 2017
Structural and Magnetic Properties of Trigonal Iron
First principles calculations of the electronic structure of trigonal iron
were performed using density function theory. The results are used to predict
lattice spacings, magnetic moments and elastic properties; these are in good
agreement with experiment for both the bcc and fcc structures. We find however,
that in extracting these quantities great care must be taken in interpreting
numerical fits to the calculated total energies. In addition, the results for
bulk iron give insight into the properties of thin iron films. Thin films grown
on substrates with mismatched lattice constants often have non-cubic symmetry.
If they are thicker than a few monolayers their electronic structure is similar
to a bulk material with an appropriately distorted geometry, as in our trigonal
calculations. We recast our bulk results in terms of an iron film grown on the
(111) surface of an fcc substrate, and find the predicted strain energies and
moments accurately reflect the trends for iron growth on a variety of
substrates.Comment: 11 pages, RevTeX,4 tar'd,compressed, uuencoded Postscript figure
The Nearby Field Galaxy Survey: a spectrophotometric and photometric study of nearby galaxies
We report on our observing program to obtain integrated spectrophotometry,
intermediate and high resolution major axis spectra, and U,B,R surface photo-
metry of a representative sample of ~200 galaxies in the nearby field. The main
goal of this program is to provide a comparison sample for high redshift
studies and to study the variation in star formation rates (SFR), star forma-
tion history (SFH), excitation, metallicity, and internal kinematics over a
large range in galaxy luminosity and morphological type. In particular, we
extend the work of Kennicutt (1992) to lower luminosity systems.
We present the main results of our analysis sofar. In these proceedings, we
condense the presented two atlases of (1) images and radial surface brightness
profiles and color profiles, and (2) of images and integrated spectra into
several example images, profiles and spectra, showing the general trends
observed. For the original atlasses we refer to the electronic version,
available at http://www.astro.rug.nl/~nfgs/ .Comment: 9 pages, LateX, 6 figures, to appear in the forthcoming issue of
Astrophysics and Space Science: "The Evolution of Galaxies on Cosmological
Timescales
Analisis Rantai Pasokan Hasil Tangkapan Ikan Di Kota Manado Dan Kota Bitung
Indonesia merupakan negara maritim yang kaya akan potensi hasil lautnya. Namun demikian tingkat pemanfaatan sumberdaya perikanan tersebut masih belum optimal, baik untuk pemenuhan konsumsi ikan dalam negeri maupun pemenuhan permintaan ekspor. Pada provinsi Sulawesi Utara, terlebih khusus Kota Manado dan Kota Bitung yang merupakan daerah pesisir, mempunyai banyak kelompok nelayan tangkap yang mempunyai beragam rantai pasokan hasil tangkapan ikan.. Tujuan penelitian ini adalah untuk mengetahui bagaimana rantai pasokan hasil tangkapan ikan di Kota Manado dan Kota Bitung serta melihat apakah terdapat perbedaan antara rantai pasokan hasil tangkapan ikan di Kota Manado dan Kota Bitung. Metode penelitian ini menggunakan penelitian deskriptif kualitatif dengan data primer dari wawancara dan observasi lapangan. Hasil penelitian menunjukan adanya perbedaan antara rantai pasokan hasil tangkapan ikan di Kota Manado dan Kota Bitung. Kelompok nelayan tangkap di Kota Manado lebih pada penjualan ikan langsung di pasar, pelelangan ataupun menjual tangkapan ikan di tempat kelompok nelayan. Sedangkan pada kelompok nelayan di Kota Bitung, peran pengumpul ikan sangat mempengaruhi rantai pasokan hasil tangkapan ikan
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