972 research outputs found
A REGIONAL COMPARISON OF U.S. COTTON BASIS PATTERNS
The basis, defined as the cash price minus the futures price, is important when making marketing decisions. The cotton basis is calculated using the July futures price for six major cotton marketing regions in the U.S. for August 1993 to November 1997. Graphs of the average basis for the four complete crop years show that the basis generally followed the expected seasonal pattern. The basis tended to be weakest at harvest and to strengthen later in the crop year. However, a visual inspection showed regional differences in the seasonal pattern. Regional differences in the yearly variability in the basis were also observed. Thus, the usefulness of the average historical basis in predicting the future basis appears to differ depending on the region.Demand and Price Analysis,
Saturated configuration interaction calculations for five-valent Ta and Db
Accurate atomic structure calculations of complicated atoms with 4 or more
valence electrons begin to push the memory and time limits of supercomputers.
This paper presents a robust method of decreasing the size of \textit{ab
initio} configuration interaction and many-body perturbation theory
calculations without undermining the accuracy of the resulting atomic spectra.
Our method makes it possible to saturate the CI matrix in atoms with many
valence electrons. We test our method on the five-valence-electron atom
tantalum and verify the convergence of the calculated energies. We then apply
the method to calculate spectra and isotope shifts of tantalum's superheavy
analogue dubnium. Isotope-shift calculations can be used to predict the spectra
of superheavy isotopes which may be produced in astrophysical phenomena
Optical spectroscopy of complex open 4-shell ions Sn-Sn
We analyze the complex level structure of ions with many-valence-electron
open [Kr] 4 sub-shells (=7-4) with ab initio
calculations based on configuration-interaction many-body perturbation theory
(CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra
of Sn-Sn ions were obtained using an electron beam ion trap.
Semi-empirical spectral fits carried out with the orthogonal parameters
technique and Cowan code calculations lead to 90 identifications of
magnetic-dipole transitions and the determination of 79 energy
ground-configuration levels, questioning some earlier EUV-line assignments. Our
results, the most complete data set available to date for these ground
configurations, confirm the ab initio predictive power of CI+MBPT calculations
for the these complex electronic systems.Comment: 18 pages, 5 figure
Pressure induced structural and dynamical changes in liquid Si. An ab-initio study
The static and dynamic properties of liquid Si at high-pressure have been
studied using the orbital free ab-initio molecular dynamics method. Four
thermodynamic states at pressures 4, 8, 14 and 23 GPa are considered. The
calculated static structure shows qualitative agreement with the available
experimental data. We analize the remarkable structural changes occurring
between 8 and 14 GPa along with its effect on several dynamic properties.Comment: 10 pages, 11 figures. Accepted for publication in Journal of Physics:
Condensed Matte
Claimed Co-ethnics and Kin-State Citizenship in Southeastern Europe
The paper introduces the often neglected concept of 'claimed co-ethnics' in the analysis of citizenship policies. It argues that this is an interstitial category that further complicates the triadic nexus between national minorities, nationalising states and kin-states. The 'claimed co-ethnics' are defined as people who are recognised by the citizenship (or ethnizenship) conferring state as belonging to its main ethnic group, although they themselves do not embrace that definition. In addition to bringing the issue of claimed co-ethnics into focus, the paper elucidates how citizenship policies can affect groups that challenge the exact fit between ethnicity and nation, showing how national governments through particular citizenship policies and categorisation practices engage in the construction of these groups. The paper shows that the triadic nexus framework, which has had a strong influence on citizenship and minorities scholarship, needs to be revised to include unidirectional relations between the elements of the triadic nexus. The paper is based on the comparison between the cases of ethnic Vlachs (in the context of Albania and Greece) and Bunjevci (in the context of Serbia and Croatia).European Commission - Seventh Framework Programme (FP7
Metastable liquid-liquid phase transition in a single-component system with only one crystal phase and no density anomaly
We investigate the phase behavior of a single-component system in 3
dimensions with spherically-symmetric, pairwise-additive, soft-core
interactions with an attractive well at a long distance, a repulsive soft-core
shoulder at an intermediate distance, and a hard-core repulsion at a short
distance, similar to potentials used to describe liquid systems such as
colloids, protein solutions, or liquid metals. We showed [Nature {\bf 409}, 692
(2001)] that, even with no evidences of the density anomaly, the phase diagram
has two first-order fluid-fluid phase transitions, one ending in a
gas--low-density liquid (LDL) critical point, and the other in a
gas--high-density liquid (HDL) critical point, with a LDL-HDL phase transition
at low temperatures. Here we use integral equation calculations to explore the
3-parameter space of the soft-core potential and we perform molecular dynamics
simulations in the interesting region of parameters. For the equilibrium phase
diagram we analyze the structure of the crystal phase and find that, within the
considered range of densities, the structure is independent of the density.
Then, we analyze in detail the fluid metastable phases and, by explicit
thermodynamic calculation in the supercooled phase, we show the absence of the
density anomaly. We suggest that this absence is related to the presence of
only one stable crystal structure.Comment: 15 pages, 21 figure
Environmental changes and violent conflict
This letter reviews the scientific literature on whether and how environmental changes affect the risk of violent conflict. The available evidence from qualitative case studies indicates that environmental stress can contribute to violent conflict in some specific cases. Results from quantitative large-N studies, however, strongly suggest that we should be careful in drawing general conclusions. Those large-N studies that we regard as the most sophisticated ones obtain results that are not robust to alternative model specifications and, thus, have been debated. This suggests that environmental changes may, under specific circumstances, increase the risk of violent conflict, but not necessarily in a systematic way and unconditionally. Hence there is, to date, no scientific consensus on the impact of environmental changes on violent conflict. This letter also highlights the most important challenges for further research on the subject. One of the key issues is that the effects of environmental changes on violent conflict are likely to be contingent on a set of economic and political conditions that determine adaptation capacity. In the authors' view, the most important indirect effects are likely to lead from environmental changes via economic performance and migration to violent conflict. © 2012 IOP Publishing Ltd
Precision Determination of the Neutron Spin Structure Function g1n
We report on a precision measurement of the neutron spin structure function
using deep inelastic scattering of polarized electrons by polarized
^3He. For the kinematic range 0.014<x<0.7 and 1 (GeV/c)^2< Q^2< 17 (GeV/c)^2,
we obtain at an average . We find relatively large negative
values for at low . The results call into question the usual Regge
theory method for extrapolating to x=0 to find the full neutron integral
, needed for testing quark-parton model and QCD sum rules.Comment: 5 pages, 3 figures To be published in Phys. Rev. Let
Search for R-parity Violating Supersymmetry in Dimuon and Four-Jets Channel
We present results of a search for R-parity-violating decay of the neutralino
chi_1^0, taken to be the Lightest Supersymmetric Particle. It is assumed that
this decay proceeds through one of the lepton-number violating couplings
lambda-prime_2jk (j=1,2; k=1,2,3). This search is based on 77.5 pb-1 of data,
collected by the D0 experiment at the Fermilab Tevatron in ppbar collisions at
a center of mass energy of 1.8 TeV in 1992-1995.Comment: 10 pages, 3 figure
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