1,699 research outputs found
A New Approach for Simulating Galaxy Cluster Properties
We describe a subgrid model for including galaxies into hydrodynamical
cosmological simulations of galaxy cluster evolution. Each galaxy construct- or
galcon- is modeled as a physically extended object within which star formation,
galactic winds, and ram pressure stripping of gas are modeled analytically.
Galcons are initialized at high redshift (z~3) after galaxy dark matter halos
have formed but before the cluster has virialized. Each galcon moves
self-consistently within the evolving cluster potential and injects mass,
metals, and energy into intracluster (IC) gas through a well-resolved spherical
interface layer. We have implemented galcons into the Enzo adaptive mesh
refinement code and carried out a simulation of cluster formation in a
LambdaCDM universe. With our approach, we are able to economically follow the
impact of a large number of galaxies on IC gas. We compare the results of the
galcon simulation with a second, more standard simulation where star formation
and feedback are treated using a popular heuristic prescription. One advantage
of the galcon approach is explicit control over the star formation history of
cluster galaxies. Using a galactic SFR derived from the cosmic star formation
density, we find the galcon simulation produces a lower stellar fraction, a
larger gas core radius, a more isothermal temperature profile, and a flatter
metallicity gradient than the standard simulation, in better agreement with
observations.Comment: 4 pages, 2 figures, submitted for publication in ApJ
Muon-spin-relaxation and magnetic-susceptibility studies of effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13
Effects of the magnetic impurity Ni on the Cu-spin dynamics and
superconductivity have been studied in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x =
0.13 changing y finely up to 0.10. Compared with the case of the nonmagnetic
impurity Zn, it has been found from the muon-spin-relaxation measurements that
a large amount of Ni is required to stabilize a magnetic order of Cu spins.
However, the evolution toward the stabilization of the magnetic order with
increasing impurity concentration is qualitatively similar to each other. The
area of the non-superconducting and slowly fluctuating or static region of Cu
spins around Ni has been found to be smaller than that around Zn, suggesting
that the pinning of rather long-ranged dynamical spin correlation such as the
so-called dynamical stripe by Ni is weaker than that by Zn. This may be the
reason why Zn destroys the superconductivity in the hole-doped high-T_c_
cuprates more markedly than Ni.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev.
ADAP Pesticide Applicator Training: Instructor's Manual
A survey course which covers the pests and diseases of crop plants with specific reference to Pacific Island conditions. The fields of Entomology, Plant Pathology, and Weed Science are each presented within the context of an integrated pest management system. Each topic includes objectives, vocabulary, lecture outlines, and review questions. Regionally important pests and disease cycles are thoroughly illustratedFunded through the U.S. Department of Agriculture Cooperative State Research, Education, and Extension Service. Grant 194-38826-0l79
Scalability of spin FPGA: A Reconfigurable Architecture based on spin MOSFET
Scalability of Field Programmable Gate Array (FPGA) using spin MOSFET (spin
FPGA) with magnetocurrent (MC) ratio in the range of 100% to 1000% is discussed
for the first time. Area and speed of million-gate spin FPGA are numerically
benchmarked with CMOS FPGA for 22nm, 32nm and 45nm technologies including 20%
transistor size variation. We show that area is reduced and speed is increased
in spin FPGA owing to the nonvolatile memory function of spin MOSFET.Comment: 3 pages, 7 figure
Absence of the impurity-induced magnetic order in the electron-doped high-T_c_ cuprates Pr_0.86_LaCe_0.14_Cu_1-y_(Zn, Ni)_y_O_4_
Zero-field muon-spin-relaxation measurements have been carried out in order
to investigate the Zn- and Ni-substitution effects on the Cu-spin dynamics in
the electron-doped Pr_0.86_LaCe_0.14_Cu_1-y_(Zn, Ni)_y_O_4+\alpa-\delta_ with y
= 0, 0.01, 0.02, 0.05 and different values of the reduced oxygen content
\delta(\delta \le 0.09). For the samples with y = 0 and very small \delta
values of \delta < 0.01, a muon-spin precession due to the formation of a
long-range antiferromagnetic order has been observed at low temperatures below
\~ 5 K. For the moderately oxygen-reduced samples of 0.01 \le \delta \le 0.09,
on the contrary, no muon-spin precession has been observed and the temperature
dependence of the spectra is similar to one another regardless of the y value.
That is, no impurity-induced slowing down of the Cu-spin fluctuations has been
detected, which is very different from the results of the hole-doped high-T_c_
cuprates. The reason is discussed.Comment: 13 pages, 2 figures, Proceedings of ISS2004 (to be published in
Physica C
The effect of beam inclination on the performance of a passive vibration isolator using buckled beams
Passive vibration isolators are desired to have both high static stiffness to support large static load and low local stiffness to reduce the displacement transmissibility at frequencies greater than resonance. Utilization of a vertical buckled beam as a spring component is one way to realize such a stiffness characteristic since it exhibits a smaller ratio of local stiffness to static stiffness than that of a linear spring. This paper investigates the behaviour of a vibration isolator using inclined beams as well as vertical ones and examines the effect of beam inclination for the purpose of improving the isolation performance. The experimental system investigated has anisolated mass which is supported by a combination of two types of beams: buckled beams and constraining beams. The buckled beams can be inclined from the vertical by attachment devices, and the constraining beams are employed to prevent off-axis motion of the isolated mass. The results demonstrate that the inclination of the buckled beams reduces the resonance frequency and improves the displacement transmissibility at frequencies greater than resonance
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