251 research outputs found
Couplings between generalized gauge fields
We analyze the BRST field-antifield construction for generalized gauge fields
consisting of massless mixed representations of the Lorentz Group and we
calculate all the strictly gauge invariant interactions between them. All these
interactions are higher derivative terms constructed out from the derivatives
of the curl of field strength.Comment: 13 pages, Latex, requires multibox.st
Dual theories for mixed symmetry fields. Spin-two case: (1,1) versus (2,1) Young symmetry type fields
We show that the parent Lagrangian method gives a natural generalization of
the dual theories concept for non p-form fields. Using this generalization we
construct here a three-parameter family of Lagrangians that are dual to the
Fierz-Pauli description of a free massive spin-two system. The dual field is a
three-index tensor T, which dinamically belongs to the (2,1) representation of
the Lorentz group. As expected, the massless limit of our Lagrangian, which is
parameter independent, has two propagating degrees of freedom per space point.Comment: 10 pages, no figure
Institutional Change, Transactions Costs and Fisheries Reform: Two Illustrations from New Zealand
Presentation in Seafish, Edinburgh on October 11, 201
Next Generation Life Support Project Status
Next Generation Life Support (NGLS) is one of several technology development projects sponsored by NASA s Game Changing Development Program. The NGLS Project is developing life support technologies (including water recovery and space suit life support technologies) needed for humans to live and work productively in space. NGLS has three project tasks: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, and Alternative Water Processor (AWP). The RCA swing bed and VOR tasks are directed at key technology needs for the Portable Life Support System (PLSS) for an Advanced Extravehicular Mobility Unit, with focus on test article development and integrated testing in an Advanced PLSS in cooperation with the Advanced Extra Vehicular Activity (EVA) Project. An RCA swing-bed provides integrated carbon dioxide removal and humidity control that can be regenerated in real time during an EVA. The VOR technology will significantly increase the number of pressure settings available to the space suit. Current space suit pressure regulators are limited to only two settings whereas the adjustability of the advanced regulator will be nearly continuous. The AWP effort, based on natural biological processes and membrane-based secondary treatment, will result in the development of a system capable of recycling wastewater from sources expected in future exploration missions, including hygiene and laundry water. This paper will provide a status of technology development activities and future plans
Topological Field Theories and Duality
Topologically non trivial effects appearing in the discussion of duality
transformations in higher genus manifolds are discussed in a simple example,
and their relation with the properties of Topological Field Theories is
established.Comment: 7 pages, Late
Burgers velocity fields and dynamical transport processes
We explore a connection of the forced Burgers equation with the
Schr\"{o}dinger (diffusive) interpolating dynamics in the presence of
deterministic external forces. This entails an exploration of the consistency
conditions that allow to interpret dispersion of passive contaminants in the
Burgers flow as a Markovian diffusion process. In general, the usage of a
continuity equation , where
stands for the Burgers field and is the
density of transported matter, is at variance with the explicit diffusion
scenario. Under these circumstances, we give a complete characterisation of the
diffusive matter transport that is governed by Burgers velocity fields. The
result extends both to the approximate description of the transport driven by
an incompressible fluid and to motions in an infinitely compressible medium.Comment: Latex fil
A high-resolution infrared spectroscopic investigation of the halogen atom-HCN entrance channel complexes solvated in superfluid helium droplets
Rotationally resolved infrared spectra are reported for the X-HCN (X = Cl,
Br, I) binary complexes solvated in helium nanodroplets. These results are
directly compared with that obtained previously for the corresponding X-HF
complexes [J. M. Merritt, J. K\"upper, and R. E. Miller, PCCP, 7, 67 (2005)].
For bromine and iodine atoms complexed with HCN, two linear structures are
observed and assigned to the and ground
electronic states of the nitrogen and hydrogen bound geometries, respectively.
Experiments for HCN + chlorine atoms give rise to only a single band which is
attributed to the nitrogen bound isomer. That the hydrogen bound isomer is not
stabilized is rationalized in terms of a lowering of the isomerization barrier
by spin-orbit coupling. Theoretical calculations with and without spin-orbit
coupling have also been performed and are compared with our experimental
results. The possibility of stabilizing high-energy structures containing
multiple radicals is discussed, motivated by preliminary spectroscopic evidence
for the di-radical Br-HCCCN-Br complex. Spectra for the corresponding molecular
halogen HCN-X complexes are also presented.Comment: 20 pages, 15 figures, 6 tables, RevTe
Anisotropic Inflation in a 5D Standing Wave Braneworld and Dimensional Reduction
We investigate a cosmological solution within the framework of a 5D standing
wave braneworld model generated by gravity coupled to a massless scalar
phantom-like field. By obtaining a full exact solution of the model we found a
novel dynamical mechanism in which the anisotropic nature of the primordial
metric gives rise to i) inflation along certain spatial dimensions, and ii)
deflation and a shrinking reduction of the number of spatial dimensions along
other directions. This dynamical mechanism can be relevant for dimensional
reduction in string and other higher dimensional theories in the attempt of
getting a 4D isotropic expanding space-time.Comment: 8 pages in Late
Does a SLAP lesion affect shoulder muscle recruitment as measured by EMG activity during a rugby tackle?
Background: The study objective was to assess the influence of a SLAP lesion on onset of EMG activity in shoulder muscles during a front on rugby football tackle within professional rugby players.
Methods: Mixed cross-sectional study evaluating between and within group differences in EMG onset times. Testing was carried out within the physiotherapy department of a university sports medicine clinic. The test group consisted of 7 players with clinically diagnosed SLAP lesions, later verified on arthroscopy. The reference group consisted of 15 uninjured and full time professional rugby players from within the same playing squad. Controlled tackles were performed against a tackle dummy. Onset of EMG activity was assessed from surface EMG of Pectorialis Major, Biceps Brachii, Latissimus Dorsi, Serratus Anterior and Infraspinatus muscles relative to time of impact. Analysis of differences in activation timing between muscles and limbs (injured versus non-injured side and non injured side versus matched reference group).
Results: Serratus Anterior was activated prior to all other muscles in all (P = 0.001-0.03) subjects. In the SLAP
injured shoulder Biceps was activated later than in the non-injured side. Onset times of all muscles of the noninjured shoulder in the injured player were consistently earlier compared with the reference group. Whereas, within
the injured shoulder, all muscle activation timings were later than in the reference group.
Conclusions: This study shows that in shoulders with a SLAP lesion there is a trend towards delay in activation time of Biceps and other muscles with the exception of an associated earlier onset of activation of Serratus anterior, possibly due to a coping strategy to protect glenohumeral stability and thoraco-scapular stability. This
trend was not statistically significant in all cases
Speech of the Hon. Henry Clay of Kentucky on taking up his compromise resolutions on the subject of Slavery delivered in senate feb. 5 th. & 6 th. 1850 (as reported by the national Intelligencer)
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