A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.Comment: To appear in Phys. Rev. D. Version with small modifications. 14 pages, 6 figures and 3 table

Octet baryon electromagnetic form factors in nuclear medium

We study the octet baryon electromagnetic form factors in nuclear matter using the covariant spectator quark model extended to the nuclear matter regime. The parameters of the model in vacuum are fixed by the study of the octet baryon electromagnetic form factors. In nuclear matter the changes in hadron properties are calculated by including the relevant hadron masses and the modification of the pion-baryon coupling constants calculated in the quark-meson coupling model. In nuclear matter the magnetic form factors of the octet baryons are enhanced in the low $Q^2$ region, while the electric form factors show a more rapid variation with $Q^2$. The results are compared with the modification of the bound proton electromagnetic form factors observed at Jefferson Lab. In addition, the corresponding changes for the bound neutron are predicted.Comment: Version accepted for publication in J.Phys. G. Few changes. 40 pages, 14 figures and 8 table

Impact of bullying on occupational commitment in young nursing professionals: the mediating role of emotional labour and emotional exhaustion

Background: Nurses are often exposed to workplace bullying, which leads to their burnout and leaving the profession. However, the processes by which workplace bullying leads to such outcomes are not clear. Aims: This study investigates how work-related and personal-related bullying affect nurses’ occupational commitment by integrating emotional labour and emotional exhaustion. Method: This study employs a cross-sectional design. The model was tested using structural equation modelling wif a sample of 245 Chinese nurses. Results: Work-related bullying is positively related to both surface acting and deep acting, and a negative relationship exists between deep acting and emotional exhaustion. Personal-related bullying is not related to either surface acting or deep acting, but is positively related to emotional exhaustion. Emotional exhaustion is negatively related to affective occupational commitment. Conclusions: This study implies that bullying behaviours should be distinguished wif work-related bullying and personal-related bullying, and emotional regulation strategies are meaningful in managing the negative impact of work-related bullying. Implication for nursing management: Policymakers and managers need to distinguish two types of bullying behaviour and manage them accordingly wif different strategies. For nursing schools it is important to prepare nursing students wif not only professional skills but also social competence and emotional management skills.info:eu-repo/semantics/acceptedVersio

Octet baryon electromagnetic form factors in a relativistic quark model

We study the octet baryon electromagnetic properties by applying the covariant spectator quark model, and provide covariant parametrization that can be used to study baryon electromagnetic reactions. While we use the lattice QCD data in the large pion mass regime (small pion cloud effects) to determine the parameters of the model in the valence quark sector, we use the nucleon physical and octet baryon magnetic moment data to parameterize the pion cloud contributions. The valence quark contributions for the octet baryon electromagnetic form factors are estimated by extrapolating the lattice parametrization in the large pion mass regime to the physical regime. As for the pion cloud contributions, we parameterize them in a covariant, phenomenological manner, combined with SU(3) symmetry. We also discuss the impact of the pion cloud effects on the octet baryon electromagnetic form factors and their radii.Comment: Published in PRD. Text modified according to the PRD journal style and format. 28 pages, 15 figures, 8 table

Wear resistant multilayer nanocomposite WC1−x/C coating on Ti–6Al–4V titanium alloy

A significant improvement of tribological properties on Ti–6Al–4V has been achieved by developed in this study multilayer treatment method for the titanium alloys. This treatment consists of an intermediate 2 μm thick TiCxNy layer which has been deposited by the reactive arc evaporation onto a diffusion hardened material with interstitial O or N atoms by glow discharge plasma in the atmosphere of Ar+O2 or Ar+N2. Subsequently, an external 0.3 μm thin nanocomposite carbon-based WC1−x/C coating has been deposited by a reactive magnetron sputtering of graphite and tungsten targets. The morphology, microstructure, chemical and phase compositions of the substrate material after treatment and coating deposition have been investigated with use of AFM, SEM, EDX, XRD, 3D profilometry and followed by tribological investigation of wear and friction analysis. An increase of hardness in the diffusion treated near-surface zone of the Ti–6Al–4V substrate has been achieved. In addition, a good adhesion between the intermediate gradient TiCxNy coating and the Ti–6Al–4V substrate as well as with the external nanocomposite coating has been obtained. Significant increase in wear resistance of up to 94% when compared to uncoated Ti–6Al–4V was reported. The proposed multilayer system deposited on the Ti–6Al–4V substrate is a promising method to significantly increase wear resistance of titanium alloys

Brazil: Oil and uncertainty

Oil spill disasters in the ocean often devastate marine and coastal ecosystems, profoundly affecting fisheries resources and fishing communities. Urgent and early-warning actions are needed to avoid a tragedy in biomes and communities when such accidents occur. In late-July 2019, Brazilian fishers alerted the first oil slick reaching the coast of Paraíba, weeks before the recognition of the biggest-ever oil spill disaster ever recorded in Brazil, extending across the entire North-eastern coast of the country. Their early voices were not properly heeded but those signals escalated into a gigantic spread of petroleum slicks. Almost 1,000 different localities were affected, including beaches, mangroves, rivers and “protected” areas. All the nine states of the region, encompassing a 2,300-km long shoreline, switched on a red light

Different Methods for the Two-Nucleon T-Matrix in the Operator Form

We compare three methods to calculate the nucleon-nucleon t-matrix based on the three-dimensional formulation of J. Golak et al., Phys. Rev. C 81, 034006, (2010). In the first place we solve a system of complex linear inhomogeneous equations directly for the t-matrix. Our second method is based on iterations and a variant of the Lanczos algorithm. In the third case we obtain the t-matrix in two steps, solving a system of real linear equations for the k-matrix expansion coefficients and then solving an on-shell equation, which connects the scalar coefficients of the k- and t-matrices. A very good agreement among the three methods is demonstrated for selected nucleon-nucleon scattering observables using a chiral next-to-next-to-leading-order neutron-proton potential. We also apply our three-dimensional framework to the demanding problem of proton-proton scattering, using a corresponding version of the nucleon-nucleon potential and supplementing it with the (screened) Coulomb force, taken also in the three-dimensional form. We show converged results for two different screening functions and find a very good agreement with other methods dealing with proton-proton scattering.Comment: 18 pages, 10 figures (54 eps files

Herbivory affects ovarian development in the zoophytophagous predator Brontocoris tabidus (Hetereoptera, Pentatomidae).

The effect of prey-based and combination prey and plant-based diets [Tenebrio molitor pupae alone; T. molitor pupae and Eucalyptus cloeziana plants; T. molitor pupae and Eucalyptus urophylla plants; and T. molitor pupae and Psidium guajava (guava) plants] on the morphometry of the ovary of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae) was analyzed in the field. Females fed on T. molitor pupae without plants presented with smaller ovarioles. The number of oocytes per ovary was higher for B. tabidus females fed on a combination diet of E. urophylla and T. molitor pupae when compared to females fed only on prey. In addition to diet, the number of oocytes in the ovariole was shown to vary with the age of B. tabidus. The 21-day-old B. tabidus females were found to have a higher number of oocytes per ovariole than the 15-day-old females in all diet conditions. The 15-day-old females exhibited more developed oocytes when fed on diets containing both prey and eucalypts plants and less developed oocytes when fed with a combination diet containing guava plants or T. molitor pupae alone. The 21-one-day-old B. tabidus females which were fed with a diet without plants had smaller oocytes than those fed with plants. Herbivory improves the morphology of the ovary of B. tabidus, affecting the size of the reproductive structures and the oogenesis of this natural enemy in the field.Publicado on-line em 28 ago. 2009

Progresso genético com a seleção de clones de Conilon no estado de Rondônia.

A espécie Coffea canephora Pierre ex Froehner possui ampla distribuição geográfica, com ocorrência em diversos continentes expandido-se por uma faixa tropical que engloba as regiões mais quentes do planeta. Aproximadamente 30% da produção nacional de café é proveniente do cultivo dessa espécie, sendo que o Estado de Rondônia se caracteriza como o segundo maior produtor de café Conilon. Este trabalho teve como objetivo estimar os parâmetros genéticos da seleção de clones de C. canephora coletados em diferentes condições ambientais do Estado de Rondônia, visando caracterizar a variabilidade genética da produção de café beneficiado e estimar o progresso genético com a seleção. A análise de variância da produtividade de café beneficiado (kg.planta-1) mostrou que a fonte de variação ?clones? foi significativa em todas as safras avaliadas, de acordo com o teste F a 1% de probabilidade. O progresso genético da produção de café beneficiado acumulada nas três safras (sacas.ha-1) com o plantio dos clones selecionados foi de 62%, com um média estimada de 217 sacas.ha-1 acumuladas nas três safras. Medidas de acurácia do experimento foram semelhantes às observadas por outros autores e indicam a possibilidade de obtenção de progresso genético com a seleção de clones no presente trabalho

Two-Nucleon Scattering without partial waves using a momentum space Argonne V18 interaction

We test the operator form of the Fourier transform of the Argonne V18 potential by computing selected scattering observables and all Wolfenstein parameters for a variety of energies. These are compared to the GW-DAC database and to partial wave calculations. We represent the interaction and transition operators as expansions in a spin-momentum basis. In this representation the Lippmann-Schwinger equation becomes a six channel integral equation in two variables. Our calculations use different numbers of spin-momentum basis elements to represent the on- and off-shell transition operators. This is because different numbers of independent spin-momentum basis elements are required to expand the on- and off-shell transition operators. The choice of on and off-shell spin-momentum basis elements is made so that the coefficients of the on-shell spin-momentum basis vectors are simply related to the corresponding off-shell coefficients.Comment: 14 pages, 8 Figures, typos correcte