793 research outputs found

    Nucleon and Delta axial-vector couplings in 1/Nc - Baryon Chiral Perturbation Theory

    Get PDF
    In this contribution, baryon axial-vector couplings are studied in the framework of the combined 1/Nc and chiral expansions. This framework is implemented on the basis of the emergent spin-flavor symmetry in baryons at large Nc and HBChPT, and linking both expansions (\xi-expansion), where 1/Nc is taken to be a quantity O(p). The study is carried out including one-loop contributions, which corresponds to O(\xi^3) for baryon masses and O(\xi^2) for the axial couplings. An analysis of the Lattice QCD results for the axial couplings of both N and \Delta is presented.Comment: Presented by A. Calle Cordon at the The 7th International Workshop on Chiral Dynamics, August 6 -10, 2012, Jefferson Lab, Newport News, Virginia, US

    Trypanosoma brucei gambiense in domestic livestock of Kogo and Mbini foci (Equatorial Guinea).

    No full text
    OBJECTIVE: To evaluate Trypanosoma brucei gambiense infection in peri-domestic livestock from Kogo and Mbini foci (Equatorial Guinea) in order to investigate its possible implication in the sleeping sickness transmission cycle in these hypoendemic foci. METHODS: Samples from 698 domestic animals (goats, sheep and pigs) from trypanosomiasis-endemic localities of Kogo and Mbini foci were tested for animal trypanosomes and T. b. gambiense (group I) by species-specific polymerase chain reaction. RESULTS: Trypanosoma brucei s.l., the predominant trypanosome species, was detected in 182 (52.6%) samples from Mbini and in 127 (36.1%) samples from Kogo. T. b. gambiense was only identified in seven (2%) of the Mbini samples and one co-infection (with T. vivax) was observed. CONCLUSION: The occurrence of T. b. gambiense in peri-domestic livestock in Mbini and its absence in Kogo could explain the epidemiological differences between the two foci and could have significant implications for sleeping sickness control in Equatorial Guinea

    Assessment of visual function and the neuroretina in subjects diagnosed with congenital anomaly of color vision

    Get PDF
    This cross-sectional and observational study includes 50 eyes of subjects with color blindness and 50 eyes of control subjects. Visual function (visual acuity, contrast sensitivity, and color vision) and neuroretinal structure were assessed in all subjects using optical coherence tomography (OCT). Significant thinning of the retinal nerve fiber layer, ganglion cell layer, and retina were observed in the color blindness group. Significant thinning was also recorded in layers that involve photoreceptor nuclei (between the outer limiting layer and the Bruch membrane and between the outer plexiform layer and the outer limiting membrane). OCT evaluation based on retinal segmentation is a rapid (5–10 minutes) non-invasive technique and seems to be a good biomarker of color blindness

    On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle

    Get PDF
    Exhaust emissions from diesel engine powered vehicles are considerably high during cold start and warm‐up, because of the poor catalyst performance due to the insufficient catalyst temperature. The controlled heat injection allowed by electrically heated catalysts can effectively reduce the catalyst light‐off time with relatively moderate fuel penalty. This paper compares the exhaust temperature and emissions of a case study diesel vehicle in cold and warm start conditions, and proposes two electrically heated catalyst control strategies, which are evaluated in terms of emission reduction and energy consumption with different target temperature settings. In addition, a new performance indicator, that is, the specific emission reduction, is used to evaluate the after‐treatment system and associated thermal management. For the worldwide harmonized light vehicle test cycle, the results without electrically heated catalyst show that from both cold and warm start conditions a large amount of operating points of the engine is located in the region of partial catalyst light off. Moreover, emissions, especially in terms of carbon monoxide and hydrocarbon, significantly decrease with the electrically heated catalyst implementation, for example, by at least 50% from cold start; however, they still tend to be rather substantial when the fuel is re‐injected after the engine cutoff phases. The exhaust temperature is lower than the target values in the sections of the driving cycle in which the electrically heated catalyst power is saturated according to the maximum level allowed by the device. The carbon dioxide penalty brought by the electrically heated catalyst ranges from 3.93% to 6.65% and from 6.49% to 9.35% for warm and cold start conditions, respectively

    Principle of Maximum Entropy Applied to Rayleigh-B\'enard Convection

    Full text link
    A statistical-mechanical investigation is performed on Rayleigh-B\'enard convection of a dilute classical gas starting from the Boltzmann equation. We first present a microscopic derivation of basic hydrodynamic equations and an expression of entropy appropriate for the convection. This includes an alternative justification for the Oberbeck-Boussinesq approximation. We then calculate entropy change through the convective transition choosing mechanical quantities as independent variables. Above the critical Rayleigh number, the system is found to evolve from the heat-conducting uniform state towards the convective roll state with monotonic increase of entropy on the average. Thus, the principle of maximum entropy proposed for nonequilibrium steady states in a preceding paper is indeed obeyed in this prototype example. The principle also provides a natural explanation for the enhancement of the Nusselt number in convection.Comment: 13 pages, 4 figures; typos corrected; Eq. (66a) corrected to remove a double counting for k=0k_{\perp}=0; Figs. 1-4 replace

    Reversible Dimerization/Polymerization of a Janus Diradical Producing Labile CC Bonds and Giant Chromism

    Get PDF
    En esta comunicación se presenta el estudio espectroscópico y téorico de la dimerización/oligomerización reversible de un birradical derivado de naftoditiofeno el cual en su forma monomérica presenta una intenso color azul mientras que al agregar se muestra incoloro, siendo éstas formas intercambiables gracias a la aplicación de estímulos débiles como presión o temperatura.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
    corecore