Effect of pig weaning age and commingling after the nursery phase on humoral and behavioral indicators of well-being and on growth performance

Two hundred and sixteen pigs were weaned at 14 or 21 d of age to determine the effect of weaning age and commingling after the nursery phase on growth and behavior of pigs in a wean-tofinish facility. Pigs were divided into older and younger age groups and allotted 12 pigs/pen with nine replications of each group. At the end of the nursery phase (d 34 after weaning), one-half of the pigs in each group were removed and commingled for the grower/finisher phase and the other half remained in their original pens. Beginning at weaning (d 0), pigs were monitored via camera surveillance following weaning, commingling, and on d 65 after weaning. While in the nursery phase, older pigs had greater gain and feed intake than younger pigs, however, younger pigs were more efficient throughout the nursery phase than older pigs. Toward the end of the grower/finisher period, younger pigs had greater gain, feed intake, and gain:feed than older pigs and reached a common weight 4 d sooner. Younger pigs spent more time standing or moving during the nursery phase than older pigs. Immediately following commingling, the younger, unmixed pigs spent more time feeding. However on d 65 after weaning, the older, commingled pigs and younger, unmixed pigs spent more time feeding than older, unmixed pigs and younger, commingled pigs. In conclusion, younger pigs grew slower than older pigs during the nursery phase; however, younger pigs gained more during the finishing period. Additionally, weaning age and commingling influenced feeding behavior during the grower/finisher period

Using GIS to Create Hazard Maps and Assess Evacuation Routes around “The Gate to Hell”; Masaya Volcano, Nicaragua

Volcán Masaya in Nicaragua is made of a series of calderas and craters that lies 7 km from the city of Masaya with a population of over 100,000. Masaya is part of the Central American Volcanic Arc (CAVA) which contains hundreds of volcanoes. While many of the volcanoes of the arc produce small, quiescent eruptions, some are capable of large explosive events. The recent cycle of volcanism at Masaya began 7000 years ago. Initial eruptions were primarily lava, small ash flows, ashfalls, and degassing events which eventually gave way to climactic Vulcanian eruptions. The hazards presented from this system affect not only larger cities, but many underdeveloped communities surrounding Volcán Masaya. These communities require a simple map and action plan to use during an evacuation. While government-issued routes are in place, there are no known secondary options. The communities surrounding Masaya lack the education they need for having such a fierce geologic feature right in their backyard to base their own opinions on when and if to evacuate the area on their own accord. We visited the study area to gather data for the creation of an evacuation route and hazard map to help prepare the surrounding communities. By consolidating our research and field data, the maps we created give the communities surrounding Masaya more insight as to the behavior of the eruptions. This research gives the local population options for evacuation and more knowledge about their environment

Shrinking cities, shrinking households, or both?

Household size decline accounts for a substantial portion of population loss in shrinking cities, yet little research has focused on it. Much of the literature presents a simple growth/decline binary that is largely determined via population figures. In this paper, we highlight the importance and assess the impact of household size changes on population decline, and determine what types of household size declines are more acute in shrinking cities than other locales. We find that elderly households and households with school‐aged children are under‐represented in shrinking cities, while households with pre‐school‐aged children are over‐represented. More tellingly, we find the biggest source of household‐related loss in shrinking cities to be the growth of single‐person households now living in houses that were once home to entire families. These findings puncture the binary on which much of the shrinking cities discourse is based. The population dynamics of most cities are subtler than either practitioners or critical scholars assert. We argue that plans and development strategies for shrinking cities should reflect a range of demographic changes, including outmigration and internal household restructuring

Performance of the Christchurch, New Zealand Cathedral during the M7.1 2010 Canterbury earthquake

The Catholic Cathedral is classified as a category 1 listed heritage building constructed largely of unreinforced stone masonry, and was significantly damaged in the recent Canterbury earthquakes of 2010 and 2011. In the 2010 event the building presented slight to moderta damage, meanwhile in the 2011 one experienced ground shaking in excess of its capacity leading to block failures and partial collapse of parts of the building, which left the building standing but still posing a significant hazard. In this paper we discuss the approach to develop the earthquake analysis of the building by 3D numerical simulations, and the results are compared/calibrated with the observed damage of the 2010 earthquake. Very accurate records were obtained during both earthquakes due to a record station located least than 80 m of distance from the building and used in the simulations. Moreover it is included in the model the soil structure interaction because it was observed that the ground and foundation played an important role on the seismic behavior of the structure. A very good agreement was found between the real observed damage and the nonlinear dynamic simulations described trough inelastic deformation (cracking) and building´s performance.University of AucklandPolytechnical University of Guadalajar

Modelling of two damaged unreinforced masonry buildings following the Canterbury earthquakes

The reported study focusedon modellingthe seismic response of two URM buildings that were damaged in the Canterbury earthquake sequence. Static and dynamic nonlinear analyses were undertakenusing the equivalent frame approach. Actual time-history records attained during the earthquakes where used to undertake dynamic analyses and facilitatedirect comparison to the observed building damage. The results showedthat use of the equivalent frame methodenabledpredictionof the seismic responseof the two case study buildings with ahigh level of accuracy

A new cohomological formula for helicity in R2k+1\R^{2k+1} reveals the effect of a diffeomorphism on helicity

The helicity of a vector field is a measure of the average linking of pairs of integral curves of the field. Computed by a six-dimensional integral, it is widely useful in the physics of fluids. For a divergence-free field tangent to the boundary of a domain in 3-space, helicity is known to be invariant under volume-preserving diffeomorphisms of the domain that are homotopic to the identity. We give a new construction of helicity for closed $(k+1)$-forms on a domain in $(2k+1)$-space that vanish when pulled back to the boundary of the domain. Our construction expresses helicity in terms of a cohomology class represented by the form when pulled back to the compactified configuration space of pairs of points in the domain. We show that our definition is equivalent to the standard one. We use our construction to give a new formula for computing helicity by a four-dimensional integral. We provide a Biot-Savart operator that computes a primitive for such forms; utilizing it, we obtain another formula for helicity. As a main result, we find a general formula for how much the value of helicity changes when the form is pushed forward by a diffeomorphism of the domain; it relies upon understanding the effect of the diffeomorphism on the homology of the domain and the de Rham cohomology class represented by the form. Our formula allows us to classify the helicity-preserving diffeomorphisms on a given domain, finding new helicity-preserving diffeomorphisms on the two-holed solid torus, and proving that there are no new helicity-preserving diffeomorphisms on the standard solid torus. We conclude by defining helicities for forms on submanifolds of Euclidean space. In addition, we provide a detailed exposition of some standard `folk' theorems about the cohomology of the boundary of domains in $\R^{2k+1}$.Comment: 51 pages, 5 figures. For v2, references updated, typos corrected, and a new appendix explaining how the Hodge Decomposition Theorem for forms on manifolds with boundary affects our theorems added. For v3, corrected an error in the caption to Figure 3 and updated reference

An extension to the Navier-Stokes equations to incorporate gas molecular collisions with boundaries

We investigate a model for micro-gas-flows consisting of the Navier-Stokes equations extended to include a description of molecular collisions with solid boundaries, together with first and second order velocity slip boundary conditions. By considering molecular collisions affected by boundaries in gas flows we capture some of the near-wall affects that the conventional Navier-Stokes equations with a linear stress/strain-rate relationship are unable to describe. Our model is expressed through a geometry-dependent mean-free-path yielding a new viscosity expression, which makes the stress/strain-rate constitutive relationship non-linear. Test cases consisting of Couette and Poiseuille flows are solved using these extended Navier-Stokes equations, and we compare the resulting velocity profiles with conventional Navier-Stokes solutions and those from the BGK kinetic model. The Poiseuille mass flow-rate results are compared with results from the BGK-model and experimental data, for various degrees of rarefaction. We assess the range of applicability of our model and show that it can extend the applicability of conventional fluid dynamic techniques into the early continuum-transition regime. We also discuss the limitations of our model due to its various physical assumptions, and we outline ideas for further development