On the Consequences of the "No Free Lunch" Theorem for Optimization on the Choice of an Appropriate MDO Architecture

Multidisciplinary design optimization (MDO) based on high- delity models is challenging due to the high computational cost of evaluating the objective and constraints. To choose the best MDO architecture, a trial-and-error approach is not possible due to the high cost of the overall optimization and complexity of the implementation. We propose to address this issue by developing a generic methodology that applies to any (potentially expensive) physical problem and generates a scalable approximation that can be quickly computed, for which the input and output dimensions may be set independently. This facilitates evaluation of MDO architectures for the original MDO problem by capturing its structure and behavior. The methodology is applied to two academic MDO test cases: the Supersonic Business Jet problem and the propane combustion problem. Well-known architectures (MDF, IDF and BLISS) are benchmarked on various instances to demonstrate the dependency between the performance of the architecture and the problem dimensions

How to catch a Smurf? - Ageing and beyond... In vivo assessment of intestinal permeability in multiple model organisms

The Smurf Assay (SA) was initially developed in the model organism Drosophila melanogaster where a dramatic increase of intestinal permeability has been shown to occur during ageing. We have since validated the protocol in multiple other model organisms and have utilised the assay to further our understanding of ageing. The SA has now also been used by other labs to assess intestinal barrier permeability. The SA in itself is simple, however numerous small details can have considerable impact on its experimental validity and subsequent interpretation. Here, we provide detailed update on the SA technique and explain how to catch a Smurf while avoiding the most common experimental fallacie

The slope current along the western European margin: A numerical investigation

A three-dimensional hydrodynamic model is used to investigate the poleward flow along the western European slopes. The area of the model domain goes from northwest Africa to Ireland. During a first stage, the currents are driven by climatological density fields. In a second stage the model is also forced by climatological winds, although special attention is paid to spring, when the winds are favourable to the development of an equatorward jet along the Iberian coast. Results show that the climatological density field is able to produce the poleward current along the European continental slope. Winds can modify the flow pattern, mainly in the southern areas off Iberia, specially during the upwelling season. The poleward current obtained is continuous between the Portuguese and French coasts, following the contour depths, with a core of maximum velocity located from 300-1 500 m, depending both on space and time. This core corresponds to the shelfward divergence of isopycnals. Maximum speeds range from 10-20 cm/s. A poleward intensification of the current is also obtained.Un modelo tridimensional hidrodinámico se ha usado para investigar el flujo en dirección hacia el polo a lo largo del talud occidental europeo. El área de dominio del modelo va desde el noroeste de áfrica hasta Irlanda. En un primer estadio, las corrientes son dirigidas por los campos climatológicos de densidad. En un segundo estadio el modelo se fuerza con vientos climatológicos, donde se presta una especial atención a la primavera, cuando los vientos son favorables al desarrollo de un jet en dirección al ecuador a lo largo de la costa ibérica. Los resultados muestran cómo el campo de densidad climatológica es capaz de producir una corriente en dirección al polo a lo largo del talud del continente europeo. Los vientos pueden modificar este esquema de flujo, principalmente en las áreas al sur de la península Ibérica, sobre todo durante la estación de upwelling. La corriente hacia el polo obtenida es continua entre las costas portuguesa y francesa, siguiendo las líneas de profundidad, con una velocidad máxima en el núcleo situada entre 300 m y 1 500 m, dependiendo tanto del espacio como del tiempo. Este núcleo corresponde a la divergencia de las isopicnas hacia la plataforma continental. Las velocidades máximas varían entre 10 y 20 cm/s. También se obtiene una intensificación hacia el polo de la corriente.Instituto Español de Oceanografí

Age-related degeneration leads to gliosis but not regeneration in the zebrafish retina

Ageing is a significant risk factor for degeneration of the retina. Harnessing the regenerative potential of Müller glia cells (MG) in the retina offers great promise for the treatment of blinding conditions, such as age-related macular degeneration. Yet, the impact of ageing on their regenerative capacity has not yet been considered. Here we show that MG retain their ability regenerate after acute damage in the aged zebrafish retina. Despite this, we observe chronic age-related neurodegeneration in the retina, which is insufficient to stimulate MG proliferation and regeneration. Instead of regeneration, ageing leads to a gliotic response and loss of vision, recapitulating hallmarks of human retinal degeneration with age. Therefore we identify key differences in the MG regenerative response to acute versus chronic damage, a key consideration for stimulating endogenous regenerative mechanisms to treat human retinal disease

Productive aspects of pigs fed forage cactus silage associated with feed restriction

This study aimed to evaluate the use of silage of forage cactus (Opuntia ficus-indica Mill) in diets for finishing pigs. Two experiments were conducted: the first for digestibility and the second for performance. In the performance trial, the quantitative levels of feed restriction (0%, 10%, 20%, and 30%) were evaluated, which were associated with the supply of forage cactus silage. Forage cactus silage presented 2463.59 and 2456 kcal/kg of digestible and metabolizable energy, respectively. The feed restriction levels associated with the supply of forage cactus silage influenced feed intake, weight gain and final weight negatively, but did not affect feed conversion. Carcass absolute weight was influenced negatively. However, the yield of carcass and cuts and the amount of meat in the carcass were not influenced. With the increase in feed restriction, there was a decrease in duodenal mucosa thickness, intestinal glands, liver glycogen storage and the occurrence of inflammation in the submucosa and intestinal mucosa. Forage cactus silage is not accepted well by animals. The restriction up to 30% of balanced feed did not affect feed conversion, yield of carcass and cuts and economic viability. However, levels over 10% affected intestinal health.Keywords: Alternative feed, feed preservation, intestinal health, Opuntia ficus-indica Mill, pig nutritio

Supplementation of diets for piglets with L-Arginine and powdered whole milk

The objective of this study was to evaluate the supplementation of L-Arginine in diets with and without dairy products for piglets weaned at 21 days old. Thirty-two animals with initial mean weight of 5.16 ± 1.92 kg and from the same commercial lineage were allocated in a randomized block design to four diets. The experimental diets consisted of a corn and soybean meal-based diet (NDD), the same diet supplemented with 0.6% L-Arginine (NDDA), the diet supplemented with powdered whole milk (DD), and the diet supplemented with powdered whole milk and 0.6% of L-Arginine (DDA). At 43 days old, 16 animals were slaughtered. The productive performance, incidence of diarrhoea, serum parameters, relative organ weight, morphometry and intestinal health were evaluated. Supplementation with 0.6% of L-Arginine increased (P <0.05) the daily and final weight gain of the piglets at 32 days old and reduced the incidence of diarrhoea. DDA promoted a higher villi to crypt ratio (P <0.05). There was a lower rate of mitosis and apoptosis in the jejunum of animals fed DD and DDA. The non-dairy diet supplemented with 0.6% arginine (NDDA) increased serum immunoglobulin A (IgA) and Immunoglobulin G (IgG) concentrations compared with NDD (P <0.05). Thus, supplementation with 0.6% L-Arginine increased immunological activity, improved intestinal integrity, and reduced the incidence of diarrhoea

Coping with suboptimal water temperature: modifications in blood parameters, body composition, and postingestive-driven diet selection in Nile tilapia fed two vegetable oil blends

The world tilapia production faces seasonal variations. However, very few nutritional studies have addressed suboptimal temperature. We evaluated the effect of two temperatures (20 or 30 °C) and two vegetable oil blends (one rich in corn oil (COR) and one rich linseed oil (LIN)) on tilapia growth, body composition, and blood parameters using a 2 × 2 factorial design with the following treatments: COR-20; LIN-20; COR-30; LIN-30 (Trial 1). In addition, we also evaluated the effect of postingestive signals of dietary oils when the organoleptic properties of diets were isolated (Trial 2). In the Trial 1, 256 fish (15.36 ± 0.14 g) were placed in 16 aquariums and submitted during 30 days to the 2 × 2 factorial designs: COR-20; LIN-20; COR-30; LIN-30. The temperatures were established in two independent water recirculation systems. In the Trial 2, 96 fish (34.02 ± 0.79 g) were placed in 12 aquariums and subjected to the same experimental design of Trial 1, but to evaluate fish feeding behavior. They were allowed to select the encapsulated diets provided in different feeding halls to evaluate if diet preferences are influenced by postingestive signals. As the Trial 1 results show, diets had no significant effects on growth, dietary protein use, and body centesimal composition, but 30 °C induced the best performance and protein deposition (P < 0.05). LIN-20 showed lower very-low-density lipoprotein and cortisol, but higher high-density lipoprotein (HDL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and triglycerides (TG) than COR-20 (P < 0.05). COR-30 presented higher HDL, AST, ALT, TG, and cortisol than LIN-30. The fish fed COR showed lower C20:5n-3 (EPA) and higher n-6 than fish fed LIN (P < 0.05). The fish fed LIN had high n-3 highly unsaturated fatty acid. ∑ polyunsaturated fatty acid was higher at 30 °C. Finally, the tilapia in Trial 2 showed clear diet intake regulation and preference for LIN (P < 0.05), regardless of temperature. In short, lipid sources had no influence on tilapia performance; however, temperature affects carcass lipid deposition as well as fatty acids profile. Notably, the preference for linseed oil can suggest nutritional metabolic issues, contributing to animal behavior knowledge

Computational fluids dynamics (CFD) in the spatial distribution of air velocity in prototype designed for animal experimentation in controlled environments

ArticleMaintaining a comfortable and productive thermal environment is one of the major challenges of poultry farming in tropical and hot climates. The thermal environment encompasses a number of factors that interact with each other and reflect the actual thermal sensation of the animals. These factors characterize the microclimate inside the facilities and influence the behaviour, performance and well-being of the birds. Thus, the objective of this study is to propose and validate a computational model of fluid dynamics to evaluate the spatial distribution of air velocity and the performance of a system designed to control air velocity variation for use in experiments with birds in controlled environment. The performance of the experimental ventilation prototype was evaluated based on air velocity distribution profiles in cages. Each prototype consisted of two fans coupled to a PVC pipe 25 cm in diameter, one at each end of the pipe, with airflow directed along the entire feeder installed in front of the cages. The contour conditions considered for the simulation of airflow inside the cage were air temperature of 35 °C at the entrance and exit of the cage; air velocity equal to 2.3 m s -1 at the entrance of the cage; pressure of 0 Pa. The model proposed in this study was representative when compared to the experimental measurements, and it can be used in the study of air flow behaviour and distribution for the improvement of the prototype design for later studies