Gamma-ray burst beaming: a universal configuration with a standard energy reservoir?

We consider a gamma-ray burst (GRB) model based on an anisotropic fireball with an axisymmetric power-law distribution of the energy per solid angle with index -k, and allow for the observer's viewing direction being at an arbitrary angle with respect to the jet axis. This model can reproduce the key features expected from the conventional on-axis uniform jet models, with the novelty that the achromatic break time in the broadband afterglow lightcurves corresponds to the epoch when the relativistic beaming angle is equal to the viewing angle rather than to the jet half opening angle. If all the GRB fireballs have such a similar energy distribution form with 1.5 < k < (or \sim) 2, GRBs may be modeled by a quasi-universal beaming configuration, and an approximately standard energy reservoir. The conclusion also holds for some other forms of angular energy distributions, such as the Gaussian function.Comment: Slightly expanded version accepted for publication in Ap

3D stabilization-free virtual element method for linear elastic analysis

We present a first-order stabilization-free virtual element method (VEM) for three-dimensional linear elastic problems in this paper. VEM has been increasingly used in various fields of engineering, but the need of stabilization yields a method that cannot be used without care, e.g. in nonlinear engineering applications. In this work, by increasing the order of the strain model, a new virtual element formulation is constructed for three-dimensional problems that does not require any stabilization term. The core concept involves adapting the virtual element space to enable the computation of a higher-order L2 projection operator, guaranteeing an accurate representation of the element energy in terms of strain and stress. This work describes the calculation process of the original H1 projection operator and the higher-order L2 projection operator for three-dimensional problems. Eigenvalue analysis allows to derive an approximate relation between the polynomial order and the number of element vertices. Some benchmark problems illustrate the capability of the stabilization-free VEM for three-dimensional linear elastic problems

Gamma-ray burst early optical afterglows: implications for the initial Lorentz factor and the central engine

Early optical afterglows have been observed from GRB 990123, GRB 021004, and GRB 021211, which reveal rich emission features attributed to reverse shocks. It is expected that Swift will discover many more early afterglows. Here we investigate in a unified manner both the forward and the reverse external shock emission components, and introduce a straightforward recipe for directly constraining the initial Lorentz factor of the fireball using early optical afterglow data. The scheme is largely independent of the shock microphysics. We identify two types of combinations of the reverse and forward shock emission, and explore their parameter regimes. We also discuss a possible diagnostic for magnetized ejecta. There is evidence that the central engine of GRB 990123 is strongly magnetized.Comment: emulateapj style, 6 pages, 1 figure. Expanded version accepted for publication in ApJ Part

Probing the birth of fast rotating magnetars through high-energy neutrinos

We investigate the high-energy neutrino emission expected from newly born magnetars surrounded by their stellar ejecta. Protons might be accelerated up to 0.1-100 EeV energies possibly by, e.g., the wave dissipation in the winds, leading to hadronic interactions in the stellar ejecta. The resulting PeV-EeV neutrinos can be detected by IceCube/KM3Net with a typical peak time scale of a few days after the birth of magnetars, making the characteristic soft-hard-soft behavior. Detections would be important as a clue to the formation mechanism of magnetars, although there are ambiguities coming from uncertainties of several parameters such as velocity of the ejecta. Non-detections would also lead to useful constraints on the scenario.Comment: 5 pages, 3 figures, accepted for publication in PR

Global Shifts in Agro-Industrial Capital and the Case of Soybean Crushing: Implications for Managers and Policy Makers

Tremendous shifts are occurring in the location of agro-industrial capital around the globe. To focus discussion on this topic a session was convened at the annual meeting of the International Food and Agribusiness Management Association in Montreux, Switzerland in June of 2004. The session brought together researchers and industry leaders to better understand these dramatic shifts and the implications they hold for the agri-food system. The following article emerges from that session. The first part of the article provides the context for the discussion by looking at global shifts in soybean processing investment. The second part entails reaction by three industry panelists.Soybeans, Processing, Investment, Global strategy, Agribusiness, Agricultural and Food Policy,

Effect of Soybean Seed Treatments on Seed Emergence and Yield

The purpose of this study was to evaluate soybean seed treatments on disease pressure. There have been experimental plots for seed treatment evaluation at the McNay Research Farm for the last two years. The McNay farm was selected for seed treatment experimental plots because it exhibited a high level of Phytophthora damping off in the spring of 1999. The objective of this study is to determine the effect of different seed treatments on seedling diseases under high disease pressure as expressed by stand establishment, plant vigor, and harvest yield

Effect of Seed Soybean Treatments on Seed Emergence and Yield

The purpose of this study was to evaluate soybean seed treatments on disease pressure. There have been experimental plots for seed treatment evaluation at the McNay Research Farm for the last three years. The McNay farm was selected for seed treatment experimental plots because it exhibited a high level of phytophthora damping off the spring of 1999. The objective of this study is to determine the effect of different seed treatments on seedling diseases under high disease pressure as expressed by stand establishment, plant vigor, and harvest yield