3,386 research outputs found
Isospin Splitting in the Baryon Octet and Decuplet
Baryon mass splittings are analyzed in terms of a simple model with general
pairwise interactions. At present, the masses are poorly known from
experiments. Improvement of these data would provide an opportunity to make a
significant test of our understanding of electromagnetic and quark-mass
contributions to hadronic masses. The problem of determining resonance masses
from scattering and production data is discussed.Comment: 9 pages, LATEX inc. 2 LATEX "pictures", CMU-HEP91-24-R9
A rapid assessment of the invasive status of Eucalyptus species in two South African provinces
Gum trees, or eucalypts (Eucalyptus species), have been targeted for invasive alien plant clearing programmes in many parts of South Africa. This has caused some dissatisfaction where the species concerned also have useful characteristics, and stakeholders contend that some of these useful species are not invasive. A rapid assessment of the invasive status of Eucalyptus species at 82 sites in South Africa (54 in the Western Cape and 28 in Mpumalanga) indicated that only Red River gum (E. camaldulensis) and flooded gum (E. grandis) are clearly invasive. Surveys were not undertaken in parts of the Western Cape known to be invaded by spider gum (E. lehmannii); the invasive status of this species is well known and is not contested. Red River gum has transformed long stretches of rivers and its importance as a major weed has been underestimated in previous reviews of alien plant invasions in South Africa. Most other species were naturalized. We recommend that projects aimed at clearing eucalypts should focus on riparian areas and nature reserves (where all eucalypts have deleterious effects), but that clearing projects outside these areas should only target species known to be invasive until such time as the invasive status of the other eucalypts (notably sugar gum, E. cladocalyx, and karri, E. diversicolor) can be ascertained with a greater degree of confidence
Reduction Procedures in Classical and Quantum Mechanics
We present, in a pedagogical style, many instances of reduction procedures
appearing in a variety of physical situations, both classical and quantum. We
concentrate on the essential aspects of any reduction procedure, both in the
algebraic and geometrical setting, elucidating the analogies and the
differences between the classical and the quantum situations.Comment: AMS-LaTeX, 35 pages. Expanded version of the Invited review talk
delivered by G. Marmo at XXIst International Workshop On Differential
Geometric Methods In Theoretical Mechanics, Madrid (Spain), 2006. To appear
in Int. J. Geom. Methods in Modern Physic
Measured Sensitivity of the First Mark II Phased Array Feed on an ASKAP Antenna
This paper presents the measured sensitivity of CSIRO's first Mk. II phased
array feed (PAF) on an ASKAP antenna. The Mk. II achieves a minimum
system-temperature-over-efficiency of 78 K at 1.23 GHz
and is 95 K or better from 835 MHz to 1.8 GHz. This PAF was designed for the
Australian SKA Pathfinder telescope to demonstrate fast astronomical surveys
with a wide field of view for the Square Kilometre Array (SKA).Comment: 5 pages, 2 figures, accepted for publication in Electromagnetics in
Advanced applications (ICEAA), 2015 International Conference o
REDD+ on the rocks? Conflict over forest and politics of justice in Vietnam
In Vietnam, villagers involved in a REDD+ (reduced emissions from deforestation and forest degradation) pilot protect areas with rocks which have barely a tree on them. The apparent paradox indicates how actual practices differ from general ideas about REDD+ due to ongoing conflict over forest, and how contestations over the meaning of justice are a core element in negotiations over REDD+. We explore these politics of justice by examining how the actors involved in the REDD+ pilot negotiate the particular subjects, dimensions, and authority of justice considered relevant, and show how politics of justice are implicit to practical decisions in project implementation. Contestations over the meaning of justice are an important element in the practices and processes constituting REDD+ at global, national and local levels, challenging uniform definitions of forest justice and how forests ought to be managed
Strange Decays of Nonstrange Baryons
The strong decays of excited nonstrange baryons into the final states Lambda
K, Sigma K, and for the first time into Lambda(1405) K, Lambda(1520) K,
Sigma(1385) K, Lambda K*, and Sigma K*, are examined in a relativized quark
pair creation model. The wave functions and parameters of the model are fixed
by previous calculations of N pi and N pi pi, etc., decays. Our results show
that it should be possible to discover several new negative parity excited
baryons and confirm the discovery of several others by analyzing these final
states in kaon production experiments. We also establish clear predictions for
the relative strengths of certain states to decay to Lambda(1405) K and
Lambda(1520) K, which can be tested to determine if a three-quark model of the
Lambda(1405) K is valid. Our results compare favorably with the results of
partial wave analyses of the limited existing data for the Lambda K and Sigma K
channels. We do not find large Sigma K decay amplitudes for a substantial group
of predicted and weakly established negative-parity states, in contrast to the
only previous work to consider decays of these states into the strange final
states Lambda K and Sigma K.Comment: 25 pages, 8 figures, RevTe
Lattice and q-difference Darboux-Zakharov-Manakov systems via -dressing method
A general scheme is proposed for introduction of lattice and q-difference
variables to integrable hierarchies in frame of -dressing
method . Using this scheme, lattice and q-difference Darboux-Zakharov-Manakov
systems of equations are derived. Darboux, B\"acklund and Combescure
transformations and exact solutions for these systems are studied.Comment: 8 pages, LaTeX, to be published in J Phys A, Letters
Gauge-invariant description of several (2+1)-dimensional integrable nonlinear evolution equations
We obtain new gauge-invariant forms of two-dimensional integrable systems of
nonlinear equations: the Sawada-Kotera and Kaup-Kuperschmidt system, the
generalized system of dispersive long waves, and the Nizhnik-Veselov-Novikov
system. We show how these forms imply both new and well-known two-dimensional
integrable nonlinear equations: the Sawada-Kotera equation, Kaup-Kuperschmidt
equation, dispersive long-wave system, Nizhnik-Veselov-Novikov equation, and
modified Nizhnik-Veselov-Novikov equation. We consider Miura-type
transformations between nonlinear equations in different gauges.Comment: Talk given at the Workshop "Nonlinear Physics: Theory and Experiment.
V", Gallipoli (Lecce, Italy), 12-21 June, 200
- …