3,173 research outputs found
General Gauge and Anomaly Mediated Supersymmetry Breaking in Grand Unified Theories with Vector-Like Particles
In Grand Unified Theories (GUTs) from orbifold and various string
constructions the generic vector-like particles do not need to form complete
SU(5) or SO(10) representations. To realize them concretely, we present
orbifold SU(5) models, orbifold SO(10) models where the gauge symmetry can be
broken down to flipped SU(5) X U(1)_X or Pati-Salam SU(4)_C X SU(2)_L X SU(2)_R
gauge symmetries, and F-theory SU(5) models. Interestingly, these vector-like
particles can be at the TeV-scale so that the lightest CP-even Higgs boson mass
can be lifted, or play the messenger fields in the Gauge Mediated Supersymmetry
Breaking (GMSB). Considering GMSB, ultraviolet insensitive Anomaly Mediated
Supersymmetry Breaking (AMSB), and the deflected AMSB, we study the general
gaugino mass relations and their indices, which are valid from the GUT scale to
the electroweak scale at one loop, in the SU(5) models, the flipped SU(5) X
U(1)_X models, and the Pati-Salam SU(4)_C X SU(2)_L X SU(2)_R models. In the
deflected AMSB, we also define the new indices for the gaugino mass relations,
and calculate them as well. Using these gaugino mass relations and their
indices, we may probe the messenger fields at intermediate scale in the GMSB
and deflected AMSB, determine the supersymmetry breaking mediation mechanisms,
and distinguish the four-dimensional GUTs, orbifold GUTs, and F-theory GUTs.Comment: RevTex4, 45 pages, 15 tables, version to appear in JHE
DBI analysis of generalised permutation branes
We investigate D-branes on the product GxG of two group manifolds described
as Wess-Zumino-Novikov-Witten models. When the levels of the two groups
coincide, it is well known that there exist permutation D-branes which are
twisted by the automorphism exchanging the two factors. When the levels are
different, the D-brane charge group demands that there should be
generalisations of these permutation D-branes, and a geometric construction for
them was proposed in hep-th/0509153. We give further evidence for this proposal
by showing that the generalised permutation D-branes satisfy the
Dirac-Born-Infeld equations of motion for arbitrary compact, simply connected
and simple Lie groups G.Comment: 19 pages, computation in section 3.5.1 corrected, conclusions
unchange
Quadrupole deformation of deuterons and final state interaction in scattering on tensor polarized deuterons at CEBAF energies
The strength of final state interaction (FSI) between struck proton and
spectator neutron in scattering depends on the alignment of
the deuteron. We study the resulting FSI effects in the tensor analyzing power
in detail and find substantial FSI effects starting at still low missing
momentum p_m \gsim 0.9 fm^{-1}. At larger p_m \gsim 1.5 fm^{-1}, FSI
completely dominates both missing momentum distribution and tensor analyzing
power. We find that to a large extent FSI masks the sensitivity of the tensor
analyzing power to models of the deuteron wave function. For the transversely
polarized deuterons the FSI induced forward-backward asymmetry of the missing
momentum distribution is shown to have a node at precisely the same value of
as the PWIA missing momentum distribution. The position of this node is
not affected by FSI and can be a tool to distinguish experimentally between
different models for the deuteron wave function.Comment: 24 pages, figures available from the authors on reques
CWRML: representing crop wild relative conservation and use data in XML
Background
Crop wild relatives are wild species that are closely related to crops. They are valuable as potential gene donors for crop improvement and may help to ensure food security for the future. However, they are becoming increasingly threatened in the wild and are inadequately conserved, both in situ and ex situ. Information about the conservation status and utilisation potential of crop wild relatives is diverse and dispersed, and no single agreed standard exists for representing such information; yet, this information is vital to ensure these species are effectively conserved and utilised. The European Community-funded project, European Crop Wild Relative Diversity Assessment and Conservation Forum, determined the minimum information requirements for the conservation and utilisation of crop wild relatives and created the Crop Wild Relative Information System, incorporating an eXtensible Markup Language (XML) schema to aid data sharing and exchange.
Results
Crop Wild Relative Markup Language (CWRML) was developed to represent the data necessary for crop wild relative conservation and ensure that they can be effectively utilised for crop improvement. The schema partitions data into taxon-, site-, and population-specific elements, to allow for integration with other more general conservation biology schemata which may emerge as accepted standards in the future. These elements are composed of sub-elements, which are structured in order to facilitate the use of the schema in a variety of crop wild relative conservation and use contexts. Pre-existing standards for data representation in conservation biology were reviewed and incorporated into the schema as restrictions on element data contents, where appropriate.
Conclusion
CWRML provides a flexible data communication format for representing in situ and ex situ conservation status of individual taxa as well as their utilisation potential. The development of the schema highlights a number of instances where additional standards-development may be valuable, particularly with regard to the representation of population-specific data and utilisation potential. As crop wild relatives are intrinsically no different to other wild plant species there is potential for the inclusion of CWRML data elements in the emerging standards for representation of biodiversity data
On the effects of the final state interaction in the electro-disintegration of the deuteron at intermediate and high energies
The role of the final state interactions (FSI) in the inclusive quasi-elastic
disintegration of the deuteron is investigated treating the two-nucleon final
state within the exact continuum solutions of the non-relativistic Schroedinger
equation, as well as within the Glauber multiple scattering approach. It is
shown that for values of the Bjorken scaling variable both
approaches provide similar results, unless the case , where
they appreciably disagree. It is demonstrated that present experimental data,
which are mostly limited to a region of four-momentum transfer () where the Center-of-Mass energy of the final state is below the
pion threshold production, can be satisfactorily reproduced by the approach
based on the exact solution of the Schroedinger equation and not by the Glauber
approach. It is also pointed out that the latter, unlike the former, does not
satisfy the inelastic Coulomb sum rule, the violation being of the order of
about 20%.Comment: 16 LaTeX pages, 10 eps-figures, 1 tabl
How do psychiatrists address delusions in first meetings in acute care? A qualitative study
Licensed under the Creative Commons Attribution Licens
Bloch oscillations of magnetic solitons in anisotropic spin-1/2 chains
We study the quantum dynamics of soliton-like domain walls in anisotropic
spin-1/2 chains in the presence of magnetic fields. In the absence of fields,
domain walls form a Bloch band of delocalized quantum states while a static
field applied along the easy axis localizes them into Wannier wave packets and
causes them to execute Bloch oscillations, i.e. the domain walls oscillate
along the chain with a finite Bloch frequency and amplitude. In the presence of
the field, the Bloch band, with a continuum of extended states, breaks up into
the Wannier-Zeeman ladder -- a discrete set of equally spaced energy levels. We
calculate the dynamical structure factor in the one-soliton sector at finite
frequency, wave vector, and temperature, and find sharp peaks at frequencies
which are integer multiples of the Bloch frequency. We further calculate the
uniform magnetic susceptibility and find that it too exhibits peaks at the
Bloch frequency. We identify several candidate materials where these Bloch
oscillations should be observable, for example, via neutron scattering
measurements. For the particular compound CoCl_2.2H_2O we estimate the Bloch
amplitude to be on the order of a few lattice constants, and the Bloch
frequency on the order of 100 GHz for magnetic fields in the Tesla range and at
temperatures of about 18 Kelvin.Comment: 31 single-spaced REVTeX pages, including 7 figures embedded with eps
How does reviewing the evidence change veterinary surgeons' beliefs regarding the treatment of ovine footrot? A quantitative and qualitative study
Footrot is a widespread, infectious cause of lameness in sheep, with major economic and welfare costs. The aims of this research were: (i) to quantify how veterinary surgeons’ beliefs regarding the efficacy of two treatments for footrot changed following a review of the evidence (ii) to obtain a consensus opinion following group discussions (iii) to capture complementary qualitative data to place their beliefs within a broader clinical context. Grounded in a Bayesian statistical framework, probabilistic elicitation (roulette method) was used to quantify the beliefs of eleven veterinary surgeons during two one-day workshops. There was considerable heterogeneity in veterinary surgeons’ beliefs before they listened to a review of the evidence. After hearing the evidence, seven participants quantifiably changed their beliefs. In particular, two participants who initially believed that foot trimming with topical oxytetracycline was the better treatment, changed to entirely favour systemic and topical oxytetracycline instead. The results suggest that a substantial amount of the variation in beliefs related to differences in veterinary surgeons’ knowledge of the evidence. Although considerable differences in opinion still remained after the evidence review, with several participants having non-overlapping 95% credible intervals, both groups did achieve a consensus opinion. Two key findings from the qualitative data were: (i) veterinary surgeons believed that farmers are unlikely to actively seek advice on lameness, suggesting a proactive veterinary approach is required (ii) more attention could be given to improving the way in which veterinary advice is delivered to farmers. In summary this study has: (i) demonstrated a practical method for probabilistically quantifying how veterinary surgeons’ beliefs change (ii) revealed that the evidence that currently exists is capable of changing veterinary opinion (iii) suggested that improved transfer of research knowledge into veterinary practice is needed (iv) identified some potential obstacles to the implementation of veterinary advice by farmers
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