494 research outputs found
Spin 3/2 Beyond the Rarita-Schwinger Framework
We employ the two independent Casimir operators of the Poincare group, the
squared four--momentum, P^2, and the squared Pauli-Lubanski vector, W^2, in the
construction of a covariant mass-m, and spin-3/2 projector in the
four-vector-spinor, \psi_{\mu}. This projector provides the basis for the
construction of an interacting Lagrangian that describes a causally propagating
spin-3/2} particle coupled to the electromagnetic field by a gyromagnetic ratio
of g_{3/2}=2.Comment: 20 page
Electrodynamic Limit in a Model for Charged Solitons
We consider a model of topological solitons where charged particles have
finite mass and the electric charge is quantised already at the classical
level. In the electrodynamic limit, which physically corresponds to
electrodynamics of solitons of zero size, the Lagrangian of this model has two
degrees of freedom only and reduces to the Lagrangian of the Maxwell field in
dual representation. We derive the equations of motion and discuss their
relations with Maxwell's equations. It is shown that Coulomb and Lorentz forces
are a consequence of topology. Further, we relate the U(1) gauge invariance of
electrodynamics to the geometry of the soliton field, give a general relation
for the derivation of the soliton field from the field strength tensor in
electrodynamics and use this relation to express homogeneous electric fields in
terms of the soliton field.Comment: 13 pages, 4 figures, Introduction and Section II (Model Lagrangian)
rewritten, new chapters concerning electrodynamic limit and discussion of
causality inserte
Selfdual Spin 2 Theory in a 2+1 Dimensional Constant Curvature Space-Time
The Lagrangian constraint analysis of the selfdual massive spin 2 theory in a
2+1 dimensional flat space-time and its extension to a curved one, are
performed. Demanding consistence of degrees of freedom in the model with
gravitational interaction, gives rise to physical restrictions on non minimal
coupling terms and background. Finally, a constant curvature scenario is
explored, showing the existence of forbidden mass values. Causality in these
spaces is discussed. Aspects related with the construction of the reduced
action and the one-particle exchange amplitude, are noted.Comment: 20 pages, references added, little modifications performe
Consistency of cruise data of the CARINA database in the Atlantic sector of the Southern Ocean
13 pages, 9 figures, 1 table.-- M. Hoppema ... et al.Initially a North Atlantic project, the CARINA carbon synthesis was extended to include the Southern Ocean. Carbon and relevant hydrographic and geochemical ancillary data from cruises all across the Arctic Mediterranean Seas, Atlantic and Southern Ocean were released to the public and merged into a new database as part of the CARINA synthesis effort. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean, including 11 from the Atlantic sector. The variables from all Southern Ocean cruises, including dissolved inorganic carbon (TCO2), total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency in one collective effort. Seawater pH and chlorofluorocarbons (CFCs) are also part of the database, but the pH quality control (QC) is described in another Earth System Science Data publication, while the complexity of the Southern Ocean physics and biogeochemistry prevented a proper QC analysis of the CFCs. The area-specific procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data (i.e. secondary QC), are briefly described here for the Atlantic sector of the Southern Ocean. Data from an existing, quality controlled database (GLODAP) were used as a reference for our computations – however, the reference data were included into the analysis without applying the recommended GLODAP adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises. The suggested corrections by the inversion analysis were allowed to vary within a fixed envelope, thus accounting for natural variability. The percentage of cruises adjusted ranged from 31% (for nitrate) to 54% (for phosphate) depending on the variable.This work has been done and funded as
part of the EU project CARBOOCEAN (no. 511176; GOCE).
Additional support from the International Ocean Carbon Coordination
Project IOCCP (Maria Hood) and the hospitality of
the Hanse Institute for Advanced Study (HWK Delmenhorst,
Germany) was gratefully accepted. R. M. Key was supported
by NOAA grants NA08OAR4320752 and NA08OAR4310820;
X. Lin by NOAA grant NA08OAR4310820; A. Velo, F. F. Perez
and A. F. R´ıos by grants: PGIDIT05OXIC40203PM Xunta de
Galicia and CTM200627116E/MAR MEC; M. A´ lvarez by grant
RYC-2006-001836; R. G. J. Bellerby by IPY project Bipolar
Atlantic Thermohaline Circulation (BIAC, IPY Cluster #23)
and Southern Ocean Biogeochemistry: Education and research
(project no. 180328) from the Norwegian Research Council.Peer reviewe
A quantitative assessment of the role of the parasite Amoebophrya in the termination of Alexandrium fundyense blooms within a small coastal embayment
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 8 (2013): e81150, doi:10.1371/journal.pone.0081150.Parasitic dinoflagellates of the genus Amoebophrya infect free-living dinoflagellates, some of which can cause harmful algal blooms (HABs). High prevalence of Amoebophrya spp. has been linked to the decline of some HABs in marine systems. The objective of this study was to evaluate the impact of Amoebophrya spp. on the dynamics of dinoflagellate blooms in Salt Pond (MA, USA), particularly the harmful species Alexandrium fundyense. The abundance of Amoebophrya life stages was estimated 3–7 days per week through the full duration of an annual A. fundyense bloom using fluorescence in situ hybridization coupled with tyramide signal amplification (FISH- TSA). More than 20 potential hosts were recorded including Dinophysis spp., Protoperidinium spp. and Gonyaulax spp., but the only dinoflagellate cells infected by Amoebophrya spp. during the sampling period were A. fundyense. Maximum A. fundyense concentration co-occurred with an increase of infected hosts, followed by a massive release of Amoebophrya dinospores in the water column. On average, Amoebophrya spp. infected and killed ~30% of the A. fundyense population per day in the end phase of the bloom. The decline of the host A. fundyense population coincided with a dramatic life-cycle transition from vegetative division to sexual fusion. This transition occurred after maximum infected host concentrations and before peak infection percentages were observed, suggesting that most A. fundyense escaped parasite infection through sexual fusion. The results of this work highlight the importance of high frequency sampling of both parasite and host populations to accurately assess the impact of parasites on natural plankton assemblages.L. Velo-Sua´rez was supported by a Marie Curie International Outgoing Fellowship (IOF; grant agreement: MOHAB PIOF-GA-252260). This work was
supported in part by NSF grants OCE-0430724 and OCE-0911031 and National Institute of Environmental Health Sciences grants 1P50-ES01274201 and
1P01ES021923-01 to D.M. Anderson and D.J. McGillicuddy through the Woods Hole Center for Oceans and Human Health, National Park Service Cooperative
Agreement H238015504 to D.M. Anderson
Extremadura y Aragón investigan la polinización del ciruelo japonés
El centro de Investigación Agraria Finca ‘La Orden- Valdesequera’ y el Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA) desarrollan conjuntamente proyectos de investigación sobre problemas de polinización que causan bajas producciones en el ciruelo japonés.Proyecto de investigación CICYT AGL2006–13529–CO2–00 financiado por el Ministerio de Ciencia e Innovación–FEDE
Quality control procedures and methods of the CARINA database
Data on the carbon and carbon relevant hydrographic and hydrochemical parameters from previously not publicly available cruises in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new data base: CARINA (CARbon IN the Atlantic). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. All CARINA data were subject to primary QC; a process in which data are studied in order to identify outliers and obvious errors. Additionally, secondary QC was performed for several of the measured parameters in the CARINA data base. Secondary QC is a process in which the data are objectively studied in order to quantify systematic differences in the reported values. This process involved crossover analysis, and as a second step the offsets derived from the crossover analysis were used to calculate corrections of the parameters measured on individual cruises using least square models. Significant biases found in the data have been corrected in the data products, i.e. three merged data files containing measured, calculated and interpolated data for each of the three regions (i.e. Arctic Mediterranean Seas, Atlantic, and Southern Ocean). Here we report on the technical details of the quality control and on tools that have been developed and used during the project, including procedures for crossover analysis and least square models. Furthermore, an interactive website for uploading of results, plots, comments etc. was developed and was of critical importance for the success of the project, this is also described here
"Square Root" of the Proca Equation: Spin-3/2 Field Equation
New equations describing particles with spin 3/2 are derived. The non-local
equation with the unique mass can be considered as "square root" of the Proca
equation in the same sense as the Dirac equation is related to the
Klein-Gordon-Fock equation. The local equation describes spin 3/2 particles
with three mass states. The equations considered involve fields with spin-3/2
and spin-1/2, i.e. multi-spin 1/2, 3/2. The projection operators extracting
states with definite energy, spin, and spin projections are obtained. All
independent solutions of the local equation are expressed through projection
matrices. The first order relativistic wave equation in the 20-dimensional
matrix form, the relativistically invariant bilinear form and the corresponding
Lagrangian are given. Two parameters characterizing non-minimal electromagnetic
interactions of fermions are introduced, and the quantum-mechanical Hamiltonian
is found. It is proved that there is only causal propagation of waves in the
approach considered.Comment: 17 pages, corrections in Eqs. (50), (51
Scattering and small data completeness for the critical nonlinear Schroediger equation
We prove Asymptotic Completeness of one dimensional NLS with long range
nonlinearities. We also prove existence and expansion of asymptotic solutions
with large data at infinity
On the consistency of Constraints in Matter Field Theories
We consider how the principles of causality and equivalence restrict the
background in which matter field theories are defined; those constraints
develop in restrictions for these matter field theories: the simplest matter
field theory aside, all other less simple matter field theories are too complex
therefore resulting to be inconsistent in general instances.Comment: 10 page
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