In this paper, incremental computation of schedules for complex discrete event systems in an uncertain environment is studied. Uncertainties are assumed to occur due to uncontrollable events. A ...particular class of flexible manufacturing systems (FMSs) with partial precedence constraints is proposed where some operations are performed with total precedence constraints and others with full routing flexibility (namely
partial routing FMSs
). Interruptions may occur due to unavailability of resources and interruption of operations. Such interruptions may deviate the trajectory from the planed schedule. For the modeling of the partial routing FMS, a systematic multi-level formalism based on the hierarchical structuration of the operations is introduced. Then, the risk of deviation is integrated and a new cost function is defined accordingly. Finally, a modified beam search algorithm referred to as
generation double filtered beam search algorithm
that accelerates the convergence of the method is proposed. The new algorithm is based on a new filtering mechanism that uses the cost function to selectively explore the state space of Petri net model in order to find a control sequence from an initial state to a reference one with a trade-off between performance and robustness. Examples are used to illustrate the efficiency of the proposed scheduling approach.
•Effects of yeast hydrolysate addition in plant-based diets were examined in pikeperch.•Replacing 60% of fish meal with soybean meal did not impair pikeperch growth.•Yeast hydrolysate addition in ...high soybean meal diets enhanced feed utilisation and survival.•Yeast hydrolysate prevented the deleterious effects of soybean meal on liver function and immunity.•These results are important for aquafeed manufacturers and pikeperch farmers.
Plant proteins have been increasingly used as sustainable substitutes for fish meal (FM) in aquafeeds; however, their high inclusion level compromises fish performance. The objective of this study was to examine whether yeast hydrolysate (YH) supplementation can improve the utilisation of high soybean meal (SM) diet and ameliorate its potential deteriorating impacts in pikeperch (Sander lucioperca). A basal diet was formulated using 44% FM, and four additional diets were produced by replacing 30 or 60% of FM with SM with or without the addition of 2% YH (FM, SM30, SM60, SM30 + YH, and SM60 + YH diets). Each diet was fed to three groups of fish (35.3 ± 0.10 g, 150 fish per group) to visual satiety four times daily for 70 days. Fish growth was not impacted by FM replacement level or YH application. However, SM60 group exhibited markedly higher feed conversion ratio and lower survival rate than those fed the FM- and YH-supplemented diets (P < 0.05). The highest and the lowest protein efficiency ratio values were obtained for the SM30 + YH and SM60 groups, respectively. Whole-body lipid content decreased in SM60 and SM60 + YH groups, and muscle lipid decreased in all the replacement groups. Serum triglyceride and glucose concentrations tended to decrease as FM replacement level increased. The highest alanine aminotransferase, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activities were detected in the SM60 group, and YH addition significantly decreased the AST and LDH activities. Serum lysozyme activity decreased in SM30, SM60 and SM60 + YH groups. Serum myeloperoxidase and antiprotease activities decreased in SM60 group, and YH supplementation improved their activities. No effects of diets were observed on serum antioxidant parameters such as catalase activity and malondialdehyde concentration, and gut morphological indices. Number of goblet cells in midgut decreased by increasing the SM inclusion level and a slight improvement was observed by YH application. These findings suggest that YH supplementation has the potential to support the replacement of up to 60% FM with defatted SM in pikeperch feed without deteriorating growth, feed utilisation, and survival rate. Further, YH incorporation mitigated the damaging impacts of high SM diet on liver function and non-specific immune response.
This paper is about scheduling problems for a class of flexible manufacturing systems (FMS) that have some operations with total precedence constraints and other operations with full routing ...flexibility (namely
hybrid FMS
). The objective is to find a control sequence from an initial state to a reference one in minimal time. For that, a systematic multi-level formalism is introduced to model the hybrid FMS based on the hierarchical structuration of the operations. Transition-timed Petri nets (T-TPN) that behave under earliest firing policy are used for that purpose. Then a new cost function is introduced to estimate the residual time to the reference. This estimation is proved to be a lower bound of the true duration. A modified Beam Search algorithm is proposed that uses the cost function to selectively explore the Petri net (PN) state space. Computational experiments illustrate the efficiency of the approach in comparison with other existing methods.
Ballan wrasse (Labrus bergylta) aquaculture has emerged as a strategic development for the sustainable control of sea-lice (Lepeophtheirus salmonis) in the European Atlantic salmon (Salmo salar) ...industry. Farmed ballan wrasse juveniles were exposed to a standard acute stressor (1min air exposure) and the patterns of change in blood haematocrit, plasma cortisol, glucose and lactate were described over a 24h period using newly validated analytical methods in that species. Plasma cortisol concentrations were relatively high and rose from a resting basal level of 60.8±5.5ng·ml−1 to a peak concentration of 284.3±26.7ng·ml−1 (3.7-fold increase) 30min post stress exposure. Cortisol was found to be the most sensitive indicator of stress followed by plasma glucose showing 83.9% increase from a resting basal level of 2.2±0.1mmol·l−1 30min post-stressor. The use of handheld metres for monitoring glucose and lactate levels was successfully validated against the reference spectrophotometric methods for on-site assessment. Validation of the methods and identification of the most sensitive stress indicators are expected to assist in the identification of adverse conditions and best rearing practices for this emerging new aquaculture species.
•Blood haematocrit, plasma cortisol, glucose and lactate were measured in farmed ballan wrasse exposed to an acute stressor.•Basal plasma cortisol levels were high and cortisol response to air exposure relatively low compared to other fish species.•Handheld meters for monitoring glucose and lactate levels were successfully validated.•The methods and indicators validated are expected to assist in identifying best rearing practices for this emerging species.
Commercial production of ballan wrasse (Labrus bergylta) as a cleaner fish for the removal of sea lice (Lepeophtheirus salmonis) from farmed salmonids (Salmo salar) has increased due to its proven ...efficiency. One bottleneck in commercial hatchery production is working with the benthic adhesive eggs, which makes disinfection and incubation of eggs challenging; therefore, this study aimed to find a chemical or enzymatic treatment and process to remove the adhesive gum layer. Naturally spawned eggs were collected from artificial spawning substrates up to 24h post spawning from wild caught broodstock kept in captivity at the Marine Harvest, Machrihanish facility. Four treatments were tested: tannic acid (0.2, 0.1, and 0.05%), sodium sulfite (2, 1, and 0.5%), l-cysteine (2, and 1%), and enzyme alcalase® (4.0, 3.0, 2.0, 1.0, and 0.5%) in vitro. Eggs were exposed for 25min while being continually agitated, and the proportion of “degummed” eggs was counted at the end of each time period. Enzyme alcalase® was the only treatment that proved successful in degumming eggs, with the time to complete degumming (≥96%) inversely related to enzyme concentration. Complete degumming occurred between 15 and 30min for all enzyme alcalase® dose rates. Mean hatch rates for eggs treated with enzyme alcalase ® were not compromised by the treatment and in the highest dose tested were actually found to be higher in treated eggs (78.9±2.4%) than controls (71.3±3.3%). The use of enzyme alcalase® has proven effective in degumming ballan wrasse eggs without affecting hatch rates. However, translation of this method to in situ degumming and thus removal of eggs from spawning substrate on farm remains to be standardised.
Increasing efficiency for commercial production of ballan wrasse.
•Egg adhesiveness poses issues for commercial production of ballan wrasse.•Chemical screening emphasised success of enzyme alcalase for degumming eggs.•In vitro trials reveal degumming rate inversely related to enzyme concentration.•Enzyme treatment shows no negative impacts on hatch rates.•In situ degumming and commercial upscaling still to be standardised
This study confirmed that observations of blue‐green colouration in plasma fractions of the ballan wrasse Labrus bergylta were caused by the linear tetra‐pyrrole biliverdin and that the molecule was ...of the physiologically relevant IXα isomer. Accumulation appears driven by chromogenic association with an unknown protein moiety which precludes enzymatic reduction and would suggest active management. It was demonstrated that the pigment did not fluctuate relative to ontogeny, or indeed binary gender in the species of interest, but mobilisation and depletion in the subset of individuals undergoing sex change at the time of study supports a potential association with gender inversion processes. It is of note that although biliverdin does have some effect on external colouration, the evidence is indicative that crypsis is a supplementary function thus other factors must be considered.
In wild ballan wrasse Labrus bergylta, mass–length relationships were not different between genders, and positive allometry was found in the mixed‐gender population. Male‐biased sexual size ...dimorphism was significant and the most effective morphometric method for sexing L. bergylta outside of the species spawning window used body mass (MB in g), total body length (LT in mm) and Fulton's condition factor (K) as discriminant variables to predict gender with 91% accuracy. The discriminant score (SD) of a specimen can be calculated as SD = 0·01 MB − 0·016 LT − 3·835 K + 6·252 to predict its gender as female or male if SD is < 1·459 or SD is > 1·504, respectively. There was a potential trend towards earlier sexual inversion compared to previous studies at comparable latitudes. Sex change is a phenotypically plastic trait under social control in haremic fishes and should be monitored in increasingly exploited L. bergylta.
For several adult cancer types, there is evidence that treatment in high volume hospitals, high case volume providers, or in specialised hospitals leads to a better outcome. The aim of this study is ...to give an overview of the existing evidence regarding the volume effect in paediatric oncology related to the quality of care or survival.
An extensive search was carried out for studies on the effect of provider case volume on the quality of care or survival in childhood cancer. Information about study characteristics, comparisons, results, and quality assessment were abstracted.
In total, 14 studies were included in this systematic review. Studies with a low risk of bias provide evidence that treatment of children with brain tumours, acute lymphoblastic leukaemia, osteosarcoma, Ewing's sarcoma, or children receiving treatment with allogenic bone marrow transplantation in higher volume hospitals, specialised hospitals, or by high case volume providers, is related with a better outcome.
This systematic review provides support for the statement that higher volume hospitals, higher case volume providers, and specialised hospitals are related to the better outcome in paediatric oncology. No studies reported a negative effect of a higher volume.
Sea lice continue to be one of the largest issues for the salmon farming industry and the use of ballan wrasse (Labrus bergylta) as a biological control is considered to be one of the most ...sustainable solutions in development. Broodstock management has proved challenging in the initial phases due to the significant lack of understanding of basic reproductive physiology and behaviour in the species. The aim of the study was to monitor captive breeding populations throughout a spawning season to examine timing and duration of spawning, quantify egg production, and look at seasonal changes in egg quality parameters as well as investigate the parental contribution to spawning events. A clear spawning rhythm was shown with 3–5 spawning periods inclusive of spawning windows lasting 1–9days followed by interspawning intervals of 8–12days. Fertilization rate remained consistently high (>87.5%) over the spawning season and did not differ significantly between spawning populations. Hatch rate was variable (0–97.5%), but peaked in the middle of the spawning season. Mean oocyte diameter and gum layer thickness decreased slightly over the spawning season with no significant differences between spawning populations. Fatty acid (FA) profile of eggs remained consistent throughout the season and with the exception of high levels of ARA (3.8±0.5% of total FA) the FA profile was similar to that observed in other marine fish species. Parental contribution analysis showed 3 out of 6 spawning events to be single paired mating while the remaining 3 had contributions from multiple parents. Furthermore, the proposed multiple batch spawning nature of this species was confirmed with proof of a single female contributing to two separate spawning events. Overall this work represents the first comprehensive dataset of spawning activity of captive ballan wrasse, and as such and will be helpful in formulating sustainable broodstock management plans for the species.
First dataset of spawning activity in captive ballan wrasse.
•We follow four captive ballan wrasse spawning harems throughout an entire spawning season.•We benchmark and examine changes in egg quality parameters over the spawning season.•Confirmation of multiple batch spawning through genotyping analysis of parental contribution to spawning events.•First dataset to benchmark spawning activity, reproductive characteristics and egg quality for captive ballan wrasse.
Production of sterile triploid Atlantic salmon (Salmo salar) would appear to be the best strategy to address the growing concerns on environmental impacts of escapees. However, the industry relies on ...a year round supply of smolts to ensure continual production and to date the production of out-of-season (S0+) triploid smolts has not been reported. The present study demonstrates that S0+ triploid smolts can be produced using an accelerated “square-wave” photoperiod (LL–LD 9.5:14.5–LL) under ambient water temperature. Such a regime advanced the timing of smoltification by 3months (S0+) relative to their siblings under an ambient photoperiod (S1+) as observed through body silvering, fin darkening, decrease in condition and significantly increased gill Na+, K+-ATPase activity. Importantly, triploid S0+ fish smolted 4weeks earlier than their diploid siblings. In S1+ populations, no difference in smolt time was observed although triploid fish also achieved a higher weight. Furthermore, deformity prevalence was very low during the fresh (≤5%) and seawater (≤2.5%) stages within both ploidies mainly represented by spinal deformity and operculum shortening. Family effects for growth and condition were clear, however, no significant family/ploidy interactions were observed although this was based on only two full-sib crosses. These results are promising but there is still a long way to go before triploid can become a commercial reality. Further studies are required to optimize and refine husbandry protocols, define breeding strategies especially regarding family selection and overall better understand triploid salmon physiology.
PDF
