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A high gradient superconducting quadrupole for a low charge state ion linac
A superconducting quadrupole magnet has been designed for use as the focusing element in a low charge state linac proposed at Argonne. The expected field gradient is 350 T/m at an operating current of 53 A, and the bore diameter is 3 cm. The use of rare earth material holmium for pole tips provides about 10% more gradient then iron pole tips. The design and the status of construction of a prototype singlet magnet is described
Perturbation Theory for Spin Ladders Using Angular-Momentum Coupled Bases
We compute bulk properties of Heisenberg spin-1/2 ladders using
Rayleigh-Schr\"odinger perturbation theory in the rung and plaquette bases. We
formulate a method to extract high-order perturbative coefficients in the bulk
limit from solutions for relatively small finite clusters. For example, a
perturbative calculation for an isotropic ladder yields an
eleventh-order estimate of the ground-state energy per site that is within
0.02% of the density-matrix-renormalization-group (DMRG) value. Moreover, the
method also enables a reliable estimate of the radius of convergence of the
perturbative expansion. We find that for the rung basis the radius of
convergence is , with defining the ratio between
the coupling along the chain relative to the coupling across the chain. In
contrast, for the plaquette basis we estimate a radius of convergence of
. Thus, we conclude that the plaquette basis offers the
only currently available perturbative approach which can provide a reliable
treatment of the physically interesting case of isotropic spin
ladders. We illustrate our methods by computing perturbative coefficients for
the ground-state energy per site, the gap, and the one-magnon dispersion
relation.Comment: 22 pages. 9 figure
Synthesis effects on the magnetic and superconducting properties of RuSr2GdCu2O8
A systematic study on the synthesis of the Ru-1212 compound by preparing a
series of samples that were annealed at increasing temperatures and then
quenched has been performed. It results that the optimal temperature for the
annealing lies around 1060-1065 C; a further temperature increase worsens the
phase formation. Structural order is very important and the subsequent grinding
and annealing improves it. Even if from the structural point of view the
samples appear substantially similar, the physical characterization highlight
great differences both in the electrical and magnetic properties related to
intrinsic properties of the phase as well as to the connection between the
grains as inferred from the resistive and the Curie Weiss behaviour at high
temperature as well as in the visibility of ZFC anf FC magnetic signals.Comment: 17 pages, 12 figures. Proc. Int. Workshop " Ruthenate and
rutheno-cuprate materials: theory and experiments", Vietri, October 2001. To
be published on LNP Series, Springer Verlag, Berlin, C. Noce, A. Vecchione,
M. Cuoco, A. Romano Eds, 200
Investigation of the ferromagnetic transition in the correlated 4d perovskites SrRuRhO
The solid-solution SrRuRhO () is a
variable-electron-configuration system forming in the nearly-cubic-perovskite
basis, ranging from the ferromagnetic 4 to the enhanced paramagnetic
4. Polycrystalline single-phase samples were obtained over the whole
composition range by a high-pressure-heating technique, followed by
measurements of magnetic susceptibility, magnetization, specific heat,
thermopower, and electrical resistivity. The ferromagnetic order in long range
is gradually suppressed by the Rh substitution and vanishes at .
The electronic term of specific-heat shows unusual behavior near the critical
Rh concentration; the feature does not match even qualitatively with what was
reported for the related perovskites (Sr,Ca)RuO. Furthermore, another
anomaly in the specific heat was observed at .Comment: Accepted for publication in PR
The New Marine Recreational Fishery Statistics Survey method for estimating Charter Boat Fishing effort
Tomato: a crop species amenable to improvement by cellular and molecular methods
Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures.
In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.
Review Section : Nature/Nurture Revisited I
Biologically oriented approaches to the study of human conflict have thus far been limited largely to the study of aggression. A sample of the literature on this topic is reviewed, drawing upon four major approaches: comparative psychology, ethology (including some popularized accounts), evolutionary-based theories, and several areas of human physiology. More sophisticated relationships between so-called "innate" and "acquired" determinants of behavior are discussed, along with the proper relevance of animal behavior studies for human behavior. Unless contained in a comprehensive theory which includes social and psychological variables, biolog ically oriented theories (although often valid within their domain) offer at best severely limited and at worst highly misleading explanations of complex social conflicts. The review concludes with a list of several positive contributions of these biological approaches and suggests that social scientists must become more knowledgeable about them.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68270/2/10.1177_002200277401800206.pd
Determinação dos elementos-traço (Zn, Co e Ni) em sedimentos da Plataforma Continental AmazĂŽnica sob influĂȘncia da descarga do rio Amazonas
Determination of trace elements (Zn, Co and Ni) in sediments at the Amazon Continental Shelf on influence of the Amazon River discharge This research was developed at Amazon Continental Shelf (ACS) between the Orange Cape (AmapĂĄ State) and the Maguari Cape (ParĂĄ State), to determine the levels of zinc, cobalt and nickel in the superficial sediments identifying its inputs and outputs. The rate of these metallic elements in the sediments decreases following Zn> Ni> Co. The concentrations of total metals in the surface sediments range from Zn = 52.8-159.5; Ni = 21.7-47.4 and Co = 14.3-48.8 (mg.kg-1). The levels of trace elements observed in the sediments at ACS are of natural occurrence. Pollution sources of metallic elements were not observed
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