Farm, Ranch and Home Quarterly Institute of Agriculture and Natural Resources, University of Nebraska- Lincoln

In this issue: From the Vice Chancellor ............................... 2 Good Management Controls Feedlot Flies................. 3 Tractor Day-Something for Everyone...................... 5 How Not to Hit Your Children ........................... 7 Cottonwoods for Nebraska.......................... 9 Agricultural job Openings Forecast ........................ 11 Range judging-An Outdoor Classroom ................... 12 To Expand or Not to Expand? ............................ 14 Dry Bean Disease Plagues Farmers ........................ 16 Pest Center Serves Growers, Gardeners .................... 19 joint Venture Beef Fabrication ............................ 21 Rural Services: Worth the Cost? .......................... 2

Exact-size Sampling for Motzkin Trees in Linear Time via Boltzmann Samplers and Holonomic Specification

International audienceBoltzmann samplers are a kind of random samplers; in 2004, Duchon, Flajolet, Louchard and Schaeffer showed that given a combinatorial class and a combinatorial specification for that class, one can automatically build a Boltzmann sampler. In this paper, we introduce a Boltzmann sampler for Motzkin trees built from a holonomic specification, that is, a specification that uses the pointing operator. This sampler is inspired by Rémy's algorithm on binary trees. We show that our algorithm gives an exact size sampler with a linear time and space complexity in average

Restauration du manuscrit Mexicain 374 de la Bibliothèque nationale de France : découverte d’une glose

À la faveur du prêt du manuscrit Mexicain 374 conservé à la Bibliothèque nationale de France (BnF) à une exposition temporaire, le document a fait l’objet d’une restauration complète. Le retrait de la toile sur laquelle le document était collé a permis de redécouvrir au verso de celui-ci une glose sans doute de l’auteur de l’inventaire des collections confisquées de Lorenzo Boturini. Le nettoyage du manuscrit a également permis de raviver ses couleurs faisant apparaître l’usage de rehauts dorés passés jusque-là inaperçus.When the manuscript Mexicain 374, housed in the Bibliothèque nationale de France (BnF), was loaned to a temporary exhibition, the manuscript underwent a complete restoration. The removal of the canvas on which the document was glued made it possible to rediscover on the back of the document a gloss, probably by the author of the inventory of Lorenzo Boturini’s confiscated collections. The cleaning of the document also allowed the original colors of the manuscript to be revived, for which the scribes adopted a golden color.Cuando el manuscrito Mexicain 374 de la Biblioteca nacional de Francia (BnF) fue prestado para una exposición temporal, dicho manuscrito fue sometido a una restauración completa. La retirada del lienzo sobre el que estaba pegado el documento permitió descubrir una glosa en su reverso, probablemente del autor del inventario de las colecciones confiscadas de Lorenzo Boturini. La limpieza del documento también permitió recuperar los colores originales del manuscrito y la utilización de realces dorados que hasta ahora habían pasado desapercibidos

Adaptative Tracking of Non Rigid Objects Based on Color Histograms and Automatic Parameter Selection

International audienceOne of the main difficulties in visual tracking is to take into account appearance changes (not only of the target but also of or due to the scene, illumination for example). The use of a Bayesian framework is very flexible and has proven to be very efficient in visual tracking. Moreover, color or greylevel histograms allow to track an objet with a low computational cost. The recently proposed color-based trackers integrated in a probabilistic framework are efficient for a given application (face tracking for example) but can not be generalized easily, due to the initialization and the adjustment of the different tracker parameters that are dependent on the input sequence. This paper presents a method based on color integrated in a particle filter that allows to cope with some of the usual problems of visual tracking (occlusions, target appearance changes, changes in resolution or in illumination) and to adapt easily to different applications (tracking of structures in aerial imagery as well as football players). The novelty of the tracker is its ability to automatically regulate all the parameters needed for tracking, which makes it flexible and easily usable for different applications

Contrasting predation services of predator and omnivore diversity mediated by invasive ants in a tropical agroecosystem

Invasive natural enemies are known to either strengthen or weaken the suppression of herbivorous arthropods. However, the impact of invasive species on the predation service provided by natural enemy diversity remains largely unexplored. Here, we tease apart the roles of invasive ants as providers of a predation service and a potential disservice, i.e. reducing the diversity of natural enemies. In mango orchards on Reunion Island, we evaluated the predation service in 20 open fields by simultaneously monitoring the predation on bait eggs and arthropod communities in two strata: the ground surface and the mango tree canopy. Our results show that the predation on bait eggs was limited to the ground surface. This stratum is dominated by three invasive omnivorous ants: Pheidole megacephala and Solenopsis geminata strongly increased the predation rate of bait eggs, whereas Brachymyrmex cordemoyi was responsible for only a small decrease in predation rate. Predation rate was positively related to predator species richness, and was negatively related to omnivore species richness. The negative relationship between the predation rate and omnivore species richness is caused by the most dominant invasive ant, P. megacephala, which reduces omnivore richness and seems to strongly prey on eggs. This study demonstrates, for the first time, the distinct influence of the diversity of two trophic groups on the predation service and how these effects can be mediated by invasive ant species. (Résumé d'auteur