Unification of SU(2)xU(1) Using a Generalized Covariant Derivative and U(3)

A generalization of the Yang-Mills covariant derivative, that uses both vector and scalar fields and transforms as a 4-vector contracted with Dirac matrices, is used to simplify and unify the Glashow-Weinberg-Salam model. Since SU(3) assigns the wrong hypercharge to the Higgs boson, it is necessary to use a special representation of U(3) to obtain all the correct quantum numbers. A surplus gauge scalar boson emerges in the process, but it uncouples from all other particles.Comment: 12 pages, no figures. To be published in Int. J. Mod. Phys.

Precision Assessment of the HPLC Phytoplankton Pigment Dataset Analyzed by NASA to Quantify Global Variability in Support of Ocean Color Remote Sensing

The ability to generate chlorophyll a (Chl a) assessments from ocean color orbital sensors, such as VIIRS and MODIS, that satisfy the requirements to be climate-quality data record (CDR) quality is contingent in part on the quality of the in situ ground or sea truth observations that serve as datasets for vicarious calibration and algorithm validation activities. NASA has a mandate to collect, analyze, and distribute in situ data of the highest possible quality with documented uncertainties and in keeping with established performance metrics. Using a dataset of over 18,000 HPLC phytoplankton pigment samples representing water collected in all major ocean basins analyzed a central laboratory (Field Support Group (FSG) of the Ocean Ecology Laboratory (OEL) at NASA Goddard Space Flight Center (GSFC)), we performed an assessment of the global precision among sample replicates of Chl a as well as major accessory pigments. We investigated the impacts of filtration volume, water basin, collection technique, pigment concentration, and different filtration volumes for replicate filters on replicate filter precision, as well as investigating any pigment-specific differences. Our results quantify sample variability with the goal of understanding any systemic biases or biogeographic influences

Pseudogap and the specific heat of high TcT_c superconductors

The specific heat of a two dimensional repulsive Hubbard model with local interaction is investigated. We use the two-pole approximation which exhibits explicitly important correlations that are sources of the pseudogap anomaly. The interplay between the specific heat and the pseudogap is the main focus of the present work. Our self consistent numerical results show that above the occupation $n_T\approx 0.85$, the specific heat starts to decrease due to the presence of a pseudogap in the density of states. We have also observed a two peak structure in the specific heat. Such structure is robust with respect to the Coulomb interaction $U$ but it is significantly affected by the occupation $n_T$. A detailed study of the two peak structure is carried out in terms of the renormalized quasi-particle bands. The role of the second nearest neighbor hopping on the specific heat behavior and on the pseudogap, is extensively discussed.Comment: 6 pages, 6 figures, accepted for publication in Solid State Communication

Paraxiphidorus michelluci n.g., n.sp. from Argentina (Nematoda : Longidoridae)

#Paraxiphidorus miichelluci n.g., n.sp. est décrit sur trois spécimens provenant de sol non cultivé d'Argentine. Ce nouveau genre est caractérisé par : région labiale en relief; amphides en étrier à ouverture large; odontostyle à base fourchue; odontophore à ailettes faiblement développées; guide du stylet en position postérieure; suppléments ventromédians dépassant le niveau des spicules; queue convexe-conoïde. Il ressemble à #Xiphidorus Monteiro, 1976 et #Paralongidorus$ Siddiqi, Hooper & Khan, 1963 mais diffère du premier par la structure de l'amphide et du second par celle du stylet, la position du guide du stylet, ainsi que par le nombre et la disposition des suppléments ventro-médians (Résumé d'auteur

Biases in the In Situ Measurement of Particulate Organic Carbon and Its Effect on the Calibration and Validation of Ocean Color Sensors

Particulate organic carbon (POC) plays an oversize role, relative to its standing stock in the global carbon (C) cycle. Accurate measurement of POC is central to understanding the ocean C flux and its sensitivity to climate forcing. POC is a standard NASA ocean color data product, which lacks a consensus, quality-assured measurement protocol for satellite validation. Thus, algorithms based on field measurements lacking verified uncertainties have limited applicability towards climate data records. Different sampling and filtration protocols, and blank corrections, introduce biases in the magnitude of POC measured from the field. A significant filter blank attributable to dissolved organic C (DOC) adsorption that, until recently has been seldom corrected for, likely has introduced biases in POC global datasets

Some Factors Associated With the Effectiveness of the Agricultural Production Component in Areas of Integrated Rural Development in Colombia as Perceived by Farmers (Crop Technology).

This study was conducted in two Integrated Rural Development Districts in Colombia; South Tolima and Fusagasuga. Its specific objectives were: (1) To determine the extent to which: (a) the factors included in the agricultural production component of the DRI program (research, extension, credit, marketing), in addition to farmland and climate were limiting crop productivity; (b) the DRI program was effectively transferring crop technology; (c) farmers adopted recommended crop technology; (2) To determine: (a) some of the reasons that limited adoption of agricultural technology; (b) changes in crop production; (c) some relevant characteristics of the DRI credit and marketing programs; (d) farmers\u27 satisfaction related to the DRI technical assistance, credit, and marketing programs; (e) the extent of association between the dependent variables, adoption of technology and crop production, and the independent variables effectiveness in transferring technology, difficulty in obtaining credit, difficulty in marketing crop production, as well as between crop production and adoption of technology. Sixty cooperating farmers were selected at random from each district for a total sample of 120 respondents. Data were collected through an interview schedule, and statistically analyzed. The major conclusions were as follows: (1) Some progress in agricultural production were evident in both districts as supported by some improvements in crop production. Nevertheless, agricultural development has been taking place slowly and it is not yet at the desired level. (2) Appropriate conditions of research, extension, credit, marketing, farmland, and climate were not present in the most appropriate mix in order to maximize productivity and accelerate development. These factors affected productivity and development to a different extent in each district. Inappropriate marketing conditions were perceived by the farmers as the principal constraint to crop productivity, while credit was perceived as the least limiting factor. (3) In order to further accelerate agricultural development, greater emphasis is needed on generating appropriate crop technologies, adapted to local farming conditions, on proper and effective technology transfer to the farmers. Stable and effective local organizations are necessary for these conditions to exist, particularly to support marketing activities. Risk and uncertainty to the farmer must be reduced as much as possible so that change can be facilitated

Electric and magnetic fields effects on the excitonic properties of elliptic core-multishell quantum wires

The effect of eccentricity distortions of core-multishell quantum wires on their electron, hole and exciton states is theoretically investigated. Within the effective mass approximation, the Schrodinger equation is numerically solved for electrons and holes in systems with single and double radial heterostructures, and the exciton binding energy is calculated by means of a variational approach. We show that the energy spectrum of a core-multishell heterostructure with eccentricity distortions, as well as its magnetic field dependence, are very sensitive to the direction of an externally applied electric field, an effect that can be used to identify the eccentricity of the system. For a double heterostructure, the eccentricities of the inner and outer shells play an important role on the excitonic binding energy, specially in the presence of external magnetic fields, and lead to drastic modifications in the oscillator strength.Comment: 17 pages, 10 figure

Mammals of Colombia deposited at the Zoologische Staatssammlung Muenchen, Germany

The Zoologische Staatssammlung Muenchen (ZSM), Germany, possesses an historical value because is the depositary of important specimens that were used in the description of different species, especially from South America. Unfortunately, there is not available information about the mammals of Colombia housed at this collection. For this, 33 specimens from Colombia belonging to six orders, 14 genus, and 17 species were reviewed. Cranial and external measurements are given, as well as information of collectors and localities. Of these specimens, 23 were captured in Northern Colombia and imported to Germany to a pet store between 1954 and 1966. Due the difficulties to access to information of mammals from Colombia in European museums and collections, the information summarized here may be useful for people interested in these species.La colección Zoologische Staatssammlung Muenchen (ZSM) en Alemania, posee un carácter histórico ya que alberga importantes ejemplares, especialmente de Suramérica, que fueron empleados para la descripción de diferentes especies. Desafortunadamente no existe información sobre los mamíferos de Colombia depositados en dicha colección. Por esto, un total de 33 especímenes procedentes de Colombia pertenecientes a seis órdenes, 14 géneros y 17 especies depositados en ZSM fueron revisados. Medidas craneales y externas son suministradas al igual que la información de los colectores y localidades. De dichos especímenes, 23 fueron capturados en el norte de Colombia e importados a Alemania hacia una tienda de mascotas entre 1954 y 1966. Teniendo en cuenta la dificultad de acceso a información sobre mamíferos de Colombia depositados en colecciones y museos europeos, la información resumida aquí puede ser útil para personas interesadas en estas especies