Rare t-quark decays t→clj+lk−t \to c l_j^{+} l_k^{-}, t→cνj~νkt \to c \tilde{\nu_j} \nu_k in the minimal four color symmetry model

The rare t-quark decays $t \to c l_j^{+} l_k^{-}$, $t \to c \tilde{\nu_j} \nu_k$ via the scalar leptoquark doublets are investigated in the minimal four color symmetry model with the Higgs mechanism of the quark-lepton mass splitting. The partial widths of these decays are calculated and the total width of the charged lepton mode $\Gamma(t \to c {l^{+}}' l^{-})= \sum_{j,k} \Gamma(t \to c l_{j}^{+} l_{k}^{-})$ and the total width of the neutrino mode $\Gamma(t \to c \tilde{\nu}' \nu)= \sum_{j,k} \Gamma(t \to c \tilde{\nu_{j}} \nu_{k})$ are found. The corresponding branching ratios are shown to be $Br(t \to c {l^{+}}' l^{-}) \approx (3.5 - 0.4) 10^{-5},$ $Br(t \to c {\tilde{\nu}}' \nu) \approx (7.1 - 0.8) 10^{-5}$ for the scalar leptoquark masses $m_{S}= 180 - 250 GeV$ and for the appropriate values $(\sin{\beta} \approx 0.2)$ of the mixing angle of the model. The search for such decays at LHC may be of interest.Comment: 18 pages, 2 figures, 1 table, to be published in Modern Physics Letters A; corrected typo

Modelling supplementation strategies for beef steer rearing and fattening systems in southern chile

A mathematical model was developed to analyze beef production systems in Southern Chile. The study considered the identification of the main components of systems under different beef steer management strategies, using pasture with or without supplementation and back grounding cattle on pasture followed by a winter period of confined feeding with pasture silage and concentrates. Validation of model outputs using 200 kg LW Hereford steers against real experimental data showed no significant differences (P ≥ 0.01) between simulated and observed final weights. In order to analyze the interaction between the stocking rate (SR) and supplementation, three SR of 2, 2.5 and 3 steers ha -1 with and without pasture silage supplementation at the rate of 5 kg DMd -1 steer -1 for the length of the entire period were simulated. Means were compared by the least significant difference (LSD, P ≤ 0.05). Significant differences were found in terms of final weights, which decreased with increasing SR regardless of the supplementation level, although silage supplementation tended to reduce differences between SR. A second set of simulation runs was carried out to simulate on-farm finishing of the steers through a final phase of confined feeding based on a ration of silage and concentrates. Final weights differed between SR and systems and results showed that the optimum corresponded to 2.5 steers ha -1 , since at this SR the largest income corresponded to the smallest mean cost. It is concluded that a stocking rate of 2.5 steers ha -1 is feasible if winter supplementation is available, independently of a finishing period in feedlot

Representative decision making: constituency constraints on collective action

This chapter focuses on the role of group and national identity in various types of collective actions. It features the decision to take action and asks about factors that influence that decision. Thus, our perspective is from the standpoint of the decision-maker who usually represents a collectivity (group, organization, nation). The interest is less about those decision-makers’ own identities and attachments than about various drivers and constraints on their decisions to act