Strong mixed-integer formulations for the floor layout problem

The floor layout problem (FLP) tasks a designer with positioning a collection of rectangular boxes on a fixed floor in such a way that minimizes total communication costs between the components. While several mixed integer programming (MIP) formulations for this problem have been developed, it remains extremely challenging from a computational perspective. This work takes a systematic approach to constructing MIP formulations and valid inequalities for the FLP that unifies and recovers all known formulations for it. In addition, the approach yields new formulations that can provide a significant computational advantage and can solve previously unsolved instances. While the construction approach focuses on the FLP, it also exemplifies generic formulation techniques that should prove useful for broader classes of problems.United States. National Science Foundation. Graduate Research Fellowship Program (Grant 1122374)United States. National Science Foundation. Graduate Research Fellowship Program (Grant CMMI-1351619

Beating the SDP bound for the floor layout problem: A simple combinatorial idea

For many mixed-integer programming (MIP) problems, high-quality dual bounds can be obtained either through advanced formulation techniques coupled with a state-of-the-art MIP solver, or through semi-definite programming (SDP) relaxation hierarchies. In this paper, we introduce an alternative bounding approach that exploits the ‘combinatorial implosion’ effect by solving portions of the original problem and aggregating this information to obtain a global dual bound. We apply this technique to the one-dimensional and two-dimensional floor layout problems and compare it with the bounds generated by both state-of-the-art MIP solvers and by SDP relaxations. Specifically, we prove that the bounds obtained through the proposed technique are at least as good as those obtained through SDP relaxations, and present computational results that these bounds can be significantly stronger and easier to compute than these alternative strategies, particularly for very difficult problem instances.United States. National Science Foundation. Graduate Research Fellowship Program (Grant 1122374)United States. National Science Foundation. Graduate Research Fellowship Program (Grant CMMI-1351619

Epigenetics and developmental programming of welfare and production traits in farm animals

The concept that postnatal health and development can be influenced by events that occur in utero originated from epidemiological studies in humans supported by numerous mechanistic (including epigenetic) studies in a variety of model species. Referred to as the ‘developmental origins of health and disease’ or ‘DOHaD’ hypothesis, the primary focus of large-animal studies until quite recently had been biomedical. Attention has since turned towards traits of commercial importance in farm animals. Herein we review the evidence that prenatal risk factors, including suboptimal parental nutrition, gestational stress, exposure to environmental chemicals and advanced breeding technologies, can determine traits such as postnatal growth, feed efficiency, milk yield, carcass composition, animal welfare and reproductive potential. We consider the role of epigenetic and cytoplasmic mechanisms of inheritance, and discuss implications for livestock production and future research endeavours. We conclude that although the concept is proven for several traits, issues relating to effect size, and hence commercial importance, remain. Studies have also invariably been conducted under controlled experimental conditions, frequently assessing single risk factors, thereby limiting their translational value for livestock production. We propose concerted international research efforts that consider multiple, concurrent stressors to better represent effects of contemporary animal production systems

Indagine sulle problematiche sanitarie di Haliotis tuberculata in allevamento con focus particolare sulle infestazioni da policheti perforanti

Recentemente l\u2019allevamento del mollusco gasteropode Haliotis tuberculata, abalone europeo, \ue8 stato intrapreso in Irlanda ed in Francia. In generale, le acque fredde proteggono questo mollusco dall\u2019insorgenza di malattie batteriche e parassitarie, ma la colonizzazione della conchiglia da parte di policheti perforanti rappresenta un importante problema in grado di causare una riduzione del valore commerciale e degli indici di crescita. Nel corso di questo studio, condotto in Bretagna su animali allevati con differenti tecniche, si \ue8 dimostrato che l\u2019et\ue0 ed il sistema d\u2019allevamento sono importanti fattori che influenzano l\u2019intensit\ue0 della infestazione. I policheti raccolti dagli abaloni appartenevano a due diverse famiglie: Spionidae, come gi\ue0 descritto in precedenti studi (Clavier, 1992) e Sabellidae, qui riportata per la prima volta nell\u2019abalone europeo. Gli studi morfologici hanno indicato che i policheti Spionidae appartenevano a diverse specie dei generi Polydora/Boccardia. Sebbene non sia stato possibile condurre mediante osservazione morfologica l\u2019identificazione tassonomica dei Sabellidae a livello di genere e specie, almeno due distinte specie erano presenti. La prevalenza e l\u2019intensit\ue0 dei Sabellidi era molto bassa, ma un solo esemplare era in grado di causare lesioni della conchiglia molto gravi. I risultati di questo studio hanno mostrato come la prevalenza sia positivamente correlata all\u2019et\ue0 dell\u2019ospite e come il sistema d\u2019allevamento possa influenzare fortemente l\u2019intensit\ue0 d\u2019infestazione dei policheti perforanti: molto bassa negli allevamenti a terra, dove l\u2019acqua viene filtrata e le procedure igieniche vengono applicate routinariamente alle vasche e pi\uf9 elevata in maricoltura, in particolare se condotta in policoltura ed in aree a basso ricambio idrico, con crescita rallentata e performance produttive ridotte

The ormer (Haliotis tuberculata): a new and promising paleoclimatic tool.

International audienc

Mixed-family estimation of genetic parameters of growth, morphologic, immune and behavioral traits in the european abalone Haliotis tuberculata

un poster présentéInternational audienc