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Search Results: 1 - 10 of 153188 matches for " Héctor "
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No Degeneracy of the Ground State for the Impact Parameter Model  [PDF]
Héctor C. Merino, Juan Héctor Arredondo
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.210165
Abstract: A time dependent Hamiltonian associated to the impact parameter model for the scattering of a light particle and two heavy ones is considered. Existence and non degeneracy of the ground state is shown.
Physical Interpretation of the Dirac Neutrino with Electromagnetic Mass  [PDF]
Héctor Torres-Silva
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.57046

The usual choice of an orthogonal set of four plane-wave solutions of the free-particle Dirac equation does not lend itself readily to direct and complete physical interpretation in the case of Dirac neutrino particle. A different choice of solutions can be made which yields a direct physical interpretation at all energies. Besides the separation of positive and negative energy states there is a further separation of states for which the spin is respectively parallel or antiparallel to the direction of the momentum vector. This can be obtained from the Maxwell’s equation without charges and current in the configuration. Scenery of our study is at high temperature T where coexist electron-positron pair and neutrino-antineutrino pair, (i.e., T≥1 MeV). Taking into consideration the possibility of negative mass, we can describe the observed behavior of antimatter in response to electromagnetic fields by assuming that the anti Dirac neutrino has a negative mass, so a new causal symmetry can be obtained.

Chiral Maxwell’s Equations as Two Spinor System: Dirac and Majorana Neutrino  [PDF]
Héctor Torres-Silva
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.56042

This work clarifies the relation between Maxwell, Dirac and Majorana neutrino equations presenting an original way to derive the Dirac and neutrino equation from the chiral electrodynamics leading, perhaps, to novel conception in the mass generation by electromagnetic fields. In the present article, it is shown that Maxwell equations can be written in the same form as the two components Dirac and neutrino equations, that is the vector representation of electromagnetic theory can be factorized into a pair of two-component spinor field equations. We propose a simple approach with the electric field E parallel to the magnetic field H. Our analysis is based on the chiral or Weyl form of the Maxwell equations in a chiral vacuum. This theory is a new quantum mechanics (QM) interpretation for Dirac and neutrino equation. The below research proves that the QM of particles represents the electrodynamics of the curvilinear closed chiral waves. Electromagnetic properties of neutrinos are discussed.

Negative Refraction in Chiral Plasma Media  [PDF]
Héctor Torres-Silva
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.54028

Negative refraction is currently achieved by driving the magnetic permeability and electrical permittivity simultaneously negative. It is studied an alternative route to negative refraction without manipulating these parameters ( εand μ) on a chiral magnetized plasma. By adding chirality to the plasma, we obtain windows where the refraction is negative. The size of these windows depends on parameters such as: chirality degree, external magnetic field and the angle of incidence of the electromagnetic wave. The present study demonstrates that the condition for negative phase-velocity propagation can be satisfied by non dissipative Faraday chiral medium such as a very dilute magnetized space plasma.

Carbon and Hydrogen Isotopes as Tracers of Methane Dynamic in Wetlands  [PDF]
Romina Sanci, Héctor O. Panarello
International Journal of Geosciences (IJG) , 2015, DOI: 10.4236/ijg.2015.67058
Abstract: This work presents a review of the main processes leading to the production and sinking of methane in wetlands and how they affect the stable isotope composition of carbon and hydrogen. Isotope fractionation factors associated to diffusion, ebullition, bacterial oxidation, etc., have been gathered from relevant literature in an intent of providing researchers in this thematic with practical procedures and tools for the interpretation of experimental data. Also it is presented guidelines of the most reliable field and laboratory methods used at present for the correct sampling and analyzing methane in different stages of occurrence, as well the most common tools used in their interpretation. Each statement is fully referenced to a long updated list of publications.
Chemical Basis for the Phytotoxicity of Indoles in Relation to the Allelopathy of Cereals  [PDF]
Héctor R. Bravo, Sylvia Copaja
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.911101
Abstract: Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cereals plants with allelopathic properties. Phytotoxic selectivity was evaluated from antialgal activity against the microalga Chlorella vulgaris, seed germination seeds and biomass weight of seedling of barley, rye, wheat, oat and maize species and the weed Lolium rigidum. Lipophilia character of the compounds was determined by RP-HPLC method. Both, the electronic character of the substituents, evaluated from σp parameter, and the lipophilia character of the molecules measured from logPHPLC parameter, are involved in the phytotoxic activity. The three bio indicators has shown that the compounds with the higher electron-acceptor groups showed the higher level of phytotoxicity and the molecules with electron-donor groups showed the lowest activity, although, in some cases, this behavior is modified by the lipophilic properties of the molecules. These results are rationalized in terms of polarization of N-H bond of heterocyclic ring. Compounds with the higher logPHPLC values showed the higher phytotoxic activity. Further evidence on the role of lipophilicity was obtained from linear regression between the average inhibitions percentages of biomass and logPHPLC values. The activity increased linearly by increasing the lipophilic character of the compounds. Therefore, quantitative effects in the phytotoxic activity of the electronic properties of the substituents in the aromatic ring and lipophilic character of the indoles can be inferred from σp and logPHPLC parameters, respectively. The results strongly suggest that the potential decomposition products of the natural indole alkaloids from cereals or other natural sources may be in connection with the allelopathic phenomenon of plants when are released into the soil.
Estudio metalúrgico de causas de falla del puente pescadero
Delgado Héctor,Hernández Héctor
Ingeniería e Investigación , 1998,
Abstract: Se trata de un puente en arco de una sola luz de 120 m, el cual colapsó después de 10 a os de servicio. Con base en elementos estructurales extraídos del puente de falla, se realizó un estudio fractográfico, mecáni co y químico, con el fin de establecer las posibles causas de fallas del puente desde el punto de vista metalúrgico. En nudos de unión de pendolón-arco se observan fracturas por fatiga en uniones soldadas en varios sitios, lo cual es evidenciado por una apariencia de fractura suave de crecimiento estable de grietas combinada con una zona de apariencia fibrosa de fractura súbita final de colapso del puente. Dado que el colapso del puente es precedido por la generación de grietas en uniones soldadas, se considera importante examinar la combinación de las propiedades de resistencia y tenacidad con el fin de estudiar tanto la capacidad de soporte de carga como de la tolerancia de defectos de las uniones soldadas.
Effets d'hétérosis sur les poids a la naissance et au sevrage dans le croisement charolais × aberdeen angus
Héctor Molinuevo
Genetics Selection Evolution , 1970, DOI: 10.1186/1297-9686-2-1-75
Descripción de la larva de último instar y de la pupa de Cryptophlebia cortesi Clarke (Lepidoptera: Tortricidae)
Vargas, Héctor A.;
Neotropical Entomology , 2006, DOI: 10.1590/S1519-566X2006000300007
Abstract: a description of the last instar larva and pupa of cryptophlebia cortesi clarke, based on specimens collected on yaro, acacia macracantha bonpl & humb ex willd. (fabaceae), in the chaca valley, primera región, chile, is presented.
Megalorhipida leucodactyla (Fabricius) (Lepidoptera: Pterophoridae): first distribution record from Chile and new host plant record
Vargas, Héctor A.;
Neotropical Entomology , 2007, DOI: 10.1590/S1519-566X2007000300019
Abstract: the presence of megalorhipida leucodactyla (fabricius) (lepidoptera: pterophoridae) in chile is reported for the first time from the azapa valley, northern chile. in this locality, some immature stages of m. leucodactyla were found to be associated with tessaria absinthioides (hook. & arn.) dc., asteraceae, a new host plant record at the species, genus and family level for m. leucodactyla.
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