Effective lagrangian for a mass dimension one fermionic field in curved spacetime

In this work we use momentum-space techniques to evaluate the propagator $G(x,x^{\prime})$ for a spin $1/2$ mass dimension one spinor field on a curved Friedmann-Robertson-Walker spacetime. As a consequence, we built the one-loop correction to the effective lagrangian in the coincidence limit. Going further we compute the effective lagrangian in the finite temperature regime. We arrive at interesting cosmological consequences, as time-dependent cosmological `constant', fully explaining the functional form of previous cosmological models.Comment: 9 pages, 0 figure

On the bilinear covariants associated to mass dimension one spinors

In this paper we approach the issue of Clifford algebra basis deformation, allowing for bilinear covariants associated to Elko spinors which satisfy the Fierz-Pauli-Kofink identities. We present a complete analysis of covariance, taking into account the involved dual structure associated to Elko. Moreover, the possible generalizations to the recently presented new dual structure are performed.Comment: 9 pages, 0 figure

On the Spinor Representation

A systematic study of the spinor representation by means of the fermionic physical space is accomplished and implemented. The spinor representation space is shown to be constrained by the Fierz-Pauli-Kofink identities among the spinor bilinear covariants. A robust geometric and topological structure can be manifested from the spinor space, wherein, for instance, the first and second homotopy groups play prominent roles on the underlying physical properties, associated to the fermionic fields.Comment: 16 page

Alpha and beta phylogenetic diversities jointly reveal ant community assembly mechanisms along a tropical elevational gradient

Despite the long-standing interest in the organization of ant communities across elevational gradients, few studies have incorporated the evolutionary information to understand the historical processes that underlay such patterns. Through the evaluation of phylogenetic α and β-diversity, we analyzed the structure of leaf-litter ant communities along the Cofre de Perote mountain in Mexico and evaluated whether deterministic- (i.e., habitat filtering, interspecific competition) or stochastic-driven processes (i.e., dispersal limitation) were driving the observed patterns. Lowland and some highland sites showed phylogenetic clustering, whereas intermediate elevations and the highest site presented phylogenetic overdispersion. We infer that strong environmental constraints found at the bottom and the top elevations are favoring closely-related species to prevail at those elevations. Conversely, less stressful climatic conditions at intermediate elevations suggest interspecific interactions are more important in these environments. Total phylogenetic dissimilarity was driven by the turnover component, indicating that the turnover of ant species along the mountain is actually shifts of lineages adapted to particular locations resembling their ancestral niche. The greater phylogenetic dissimilarity between communities was related to greater temperature differences probably due to narrow thermal tolerances inherent to several ant lineages that evolved in more stable conditions. Our results suggest that the interplay between environmental filtering, interspecific competition and habitat specialization plays an important role in the assembly of leaf-litter ant communities along elevational gradients

Mass dimension one fermions and their gravitational interaction

We investigate in detail the interaction between the spin-${1/2}$ fields endowed with mass dimension one and the graviton. We obtain an interaction vertex that combines the characteristics of scalar-graviton and Dirac's fermion-graviton vertices, due to the scalar-dynamic attribute and the fermionic structure of this field. It is shown that the vertex obtained obeys the Ward-Takahashi identity, ensuring the gauge invariance for this interaction. In the contribution of the mass dimension one fermion to the graviton propagator at one-loop, we found the conditions for the cancellation of the tadpole term by a cosmological counter-term. We calculate the scattering process for arbitrary momentum. For low energies, the result reveals that only the scalar sector present in the vertex contributes to the gravitational potential. Finally, we evaluate the non relativistic limit of the gravitational interaction and obtain an attractive Newtonian potential, as required for a dark matter candidate.Comment: 8 pages, 3 figure

Manejo alimentar de ovelhas e cabras no periparto.

Revisão discute os principais tópicos inerentes ao manejo alimentar de ovelhas e cabras no periparto, como ferramenta importante dentro do manejo geral de pequenos ruminantes. Estratégias de alimentação de matrizes no periparto devem ser elaboradas como forma de equilibrar o aporte de nutrientes necessários ao atendimento das demandas nutricionais desses animais. Para isso devem-se elaborar programas nutricionais conforme a fase da gestação e de lactação, número de fetos, ordem de parto, tendo em vista o fornecimento e a disponibilidade de alimentos de adequado valor nutritivo, incrementando a ingestão de nutrientes. Além disso, o acompanhamento do escore de condição corporal dos animais nessa fase torna-se uma ferramenta importante para o adequado manejo nutricional garantindo o adequado desempenho dos animais

\u3cem\u3eTithonia diversifolia\u3c/em\u3e for Ruminant Nutrition

India and Brazil lead the world ranking of livestock enteric methane emissions (FAO 2006). According to FAO (2006), Brazil (9.6 Tg of CH4/year) is the highest emitter of methane from cattle, followed by India (8.6 Tg of CH4/year) and the USA (5.1 Tg of CH4/year). In livestock, methane (CH4) formed from enteric fermentation of carbohydrates is primarily responsible for the emissions in the sector. Regarding livestock methane emission, Delgado et al. (2012) evaluated 20 tree and shrub species using in vitro technique and demonstrated a reducing effect on the amount of methane when Tithonia diversifolia was compared with, for example, Cynodon nlemfuensis grass. Tithonia diversifolia belongs to the division - Sphermatophyta; class - Eudicotiledoneae; sub-class - Metaclamídeas; Order - Campanulate; Family - Asteraceae; Genre - Tithonia, and Species - Tithonia diversifolia (Hemsl.), Gray (Souza 2008). Tithonia diversifolia can be very useful in animal nutrition (Fig. 1) by increasing the protein content of animal diet at low cost (Murgueitio et al. 2010) as well as in the recovery of degraded soils for it grows in areas with low levels of fertility and has high ability to absorb phosphorus, even if it is unavailable to other forage species (Kwabiah et al. 2003). The objective of this study was to assess the nutritional qualities, including quantification of enteric methane generated during in vitro ruminal fermentation, of Tithonia diversifolia as an alternative forage for ruminant nutrition in the tropics