Multiskilling is a workforce flexibility strategy where companies educate workers to perform a set of task types effectively. When the multiskilling plans are structured using k-chaining policies, it ...is possible to obtain the maximum flexibility to match the uncertain workforce demand. This work evaluates the potential benefits of multiskilled workers using a k-chaining policy with k≥2, considering the learning/forgetting phenomena to model a heterogeneous workforce. We propose a deterministic mixed-integer programming model to compute the level of required multiskilling. The mathematical formulation determines how many workers should be single-skilled and multiskilled, which task types they should be trained in, the allocation of working hours, and the expected productivity of each worker on each week of the planning horizon. We test our methodology on a case study using real, processed, and simulated data from a Chilean retail store. We perform three experiments, comparing them: zero multiskilling, k-chaining with k≥2 and homogeneous workforce, and k-chaining with k≥2 and heterogeneous workforce. We consider nine variability levels in the workforce demand for each experiment. The results show that modeling the workforce as homogeneous leads to underestimating the multiskilling level required to minimize understaffing. Incorporating heterogeneous workforce modeling through the learning-forgetting phenomena suggests more multiskilling to compensate for the lower workers’ productivity. We consider this solution is closer to the actual operation of the store. We also perform a sensitivity analysis on the learning rate parameter to evaluate the stability of the report solutions for each variability level.
•Literature review on multiskilled and heterogeneous personnel scheduling problems.•MIP model for computing multiskilling requirements and multiskilled workers' productivity.•Real study case of a multi-department retail store.•A sensitivity analysis on workers' learning rates and staff demands.•A k-chaining policy with k ≥ 2 provides greater benefits under high demand uncertainty.
This report describes the case of a female kidney transplant patient with systemic lupus erythematosus, primary biliary cholangitis, and postsurgical hypothyroidism due to Grave's disease who had a ...healthy newborn after in vitro fertilization (IVF). Cases of successful pregnancy involving women who underwent IVF after kidney transplantation have been reported. Normal and stable renal function, adequate immunosuppressant therapy, and well-managed blood pressure are requirements to be eligible for IVF and pregnancy. Primary biliary cholangitis without cirrhosis does not seem to worsen during pregnancy and IVF must be individualized in patients with systemic lupus erythematosus. There are no similar case reports involving kidney transplant patients or individuals with autoimmune disorders, so the decision to perform IVF had to be individualized in order to avoid complications for the mother and fetus.
We investigate the performance of two hybrid forecasting models to predict the next-day base load electricity prices on the APX power exchange for Great Britain. Hybrid models have often been ...advocated as a synthetic method for forecasting, but it is an open question how well they perform at the day-ahead stage. A conventional hybrid approach combines a fundamental model, formulated with supply stack modeling, with an econometric model using data on price drivers. We extend this model to one based upon logistic smooth transition regression, which represents a regime-switching for periods of structural change. Empirical results for out-of-sample forecasting using both hybrid approaches are discussed and compared to non-hybrid time series forecasting methods.
Mitochondrial Ca2+ dynamics in cells and suspensions Wacquier, Benjamin; Romero Campos, Hugo E.; González‐Vélez, Virginia ...
The FEBS journal,
December 2017, 20171201, Letnik:
284, Številka:
23
Journal Article
Recenzirano
Odprti dostop
Mitochondria play a significant role in shaping cytosolic Ca2+ signals. Thus, transfer of Ca2+ across the mitochondrial membrane is much studied, not only in intact cells but also in artificial ...systems such as mitochondrial suspensions or permeabilised cells. Observed rates of Ca2+ changes vary by at least one order of magnitude. In this work, we investigate the relationship between the Ca2+ dynamics observed in various experimental conditions using a computational model calibrated on experimental data. Results confirm that mitochondrial Ca2+ exchange fluxes through the mitochondrial Ca2+ uniporter (MCU) and the Na+/Ca2+ exchanger obey the same basic kinetics in cells and in suspensions, and emphasise the important role played by the high Ca2+ levels reached in mitochondria‐associated endoplasmic reticulum membranes in intact cells. Tissue specificity can be ascribed to the different modes of regulation of the MCU by Ca2+, probably related to the specific levels of expression of the Ca2+ sensing regulator subunit of this channel. The model emphasises the importance of mitochondrial density and buffering in controlling the rate of Ca2+ exchanges with mitochondria, as verified experimentally. Finally, we show that heterogeneity between individual mitochondria can explain the large range of amplitudes and rates of rise in mitochondrial Ca2+ concentration that have been observed experimentally.
Fluxes of Ca2+ across the mitochondrial membranes are important for signalling and bioenergetics. Ca2+ exchanges between mitochondria and the extra‐mitochondrial medium can be studied not only in intact cells, but also in suspensions or in permeabilised cells, leading to very different profiles of Ca2+ changes. However, they all obey the same kinetics whatever the experimental conditions and the cell type.
•Comprehensive review examines retail personnel scheduling.•An optimization model finds optimal shift structures for retail stockers.•A real case study evaluates the costs and benefits of night/day ...stocking.•Night stocking benefits highlighted, offering valuable retail guidance.•Combining day, night, and semi-night shift structures provides a cost-effective solution.
This research examines the economic viability of night shelf stocking in the retail industry. By analyzing real data on the costs and benefits of both night and day stocking, we propose a novel integer linear optimization model to determine the optimal structure of shelf stocker shifts for individual stores. The model is tested on a standard Chilean supermarket, with a sensitivity analysis performed on key parameters including product demands, shelf capacity, and cost factors. The results reveal that a daytime shelf stocking system is impractical and costly for high-demand outlets. We recommend combining day and night stockings, as night stocking proves to be more efficient, reducing stockouts and salary costs. Additionally, an analysis incorporating semi-night shifts as an alternative to traditional shift patterns demonstrates that combining day, night, and semi-night shift structures is the most cost-effective solution, minimizing labor and stocking expenses without compromising service quality. This study highlights the economic advantages of night shelf stocking and provides valuable insights for retailers seeking to optimize their operations.
Paralytic shellfish poisoning (PSP) episodes cause important economic impacts due to closure of shellfish production areas in order to protect human health. These closures, if are frequent and ...persistent, can seriously affect shellfish producers and the seafood industry, among others. In this study, we have developed an alternative processing method for bivalves with PSP content above the legal limit, which allows reducing toxicity to acceptable levels. A modification of the PSP detoxifying procedure stablished by Decision 96/77/EC of the European Union in Acanthocardia tuberculata, was developed and implemented for PSP elimination in other bivalves species. The procedure was applied to 6 batches of mussels, 2 batches of clams and 2 batches of scallops, achieving detoxification rates of around 85%. A viable industrial protocol which allows the transformation of a product at risk into a safe product was developed. Although a significant reduction was obtained, in a sample circa 9000 μg STX diHCl equiv/kg, the final toxin level in these highly toxic mussels did not fall below the European limit. The processing protocol described may be applied efficiently to mussels, clams and scallops and it may be a major solution to counteract the closure of shellfish harvesting areas, especially if persistent.
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•An industrial protocol aimed at reducing PSP toxin levels was developed and optimized in mussels, clams and scallops.•The procedure was applied to some batches of PSP-contaminated molluscs obtaining ±85% detoxification and a safe product.•However, one sample with an exceptionally high toxicity, 9000 μg STX diHCl equiv/kg, did not fall below the European limit.•An economically feasible bivalve canning processing was implemented, guaranteeing the manufacture of a safe product.
•60 different fungal taxa isolated from roots of Celtica gigantea, a wasteland grass.•Celtica fungal endophytes were tested in tritordeum for potential use in agriculture.•Several fungal strains ...improved the growth of leaves and/or roots of tritordeum.•A Diaporthe strain consistently promoted leaf and root growth.•Plant inoculation with fungi grown in beet pulp media was useful for screening.
Celtica gigantea(= Stipa gigantea) is a large perennial grass which grows in nutrient-poor sandy soils in semiarid zones of the western Iberian Peninsula. The purpose of this work was to find out if culturable fungal symbionts isolated from roots of this wild grass could have growth promoting activity in tritordeum, a hybrid cereal for human consumption. A survey of fungi from the root endosphere of C. gigantea produced an isolate collection consisting of 60 different taxa, mostly ascomycetes. Fungal strains were inoculated into tritordeum plants in order to evaluate their effect in leaf and root biomass, nutrient content, and total antioxidant capacity. Two consecutive screening processes were made to test endophyte effects in plants. In the first screening, 66 strains were inoculated into seedlings by dipping roots in a liquid suspension of inoculum. In the second screening, 13 strains selected from the first screening were inoculated by sowing seeds in a substrate containing inoculum. The inoculation method used in the second screening involved less labor and plant manipulation and improved the quantity and quality of the inoculum, making it more appropriate for big scale experimental inoculation procedures. Several fungal strains promoted leaf or root growth. In particular, a strain belonging to the genus Diaporthe caused an increase in leaf and root biomass in both screening processes, suggesting that this endophyte might have a good potential for field application in tritordeum.
Concern for the environment and the diminishing availability of resources is undoubtedly a relevant issue, both personally and organizationally. That is why knowing the factors that affect the ...occurrence of green behavior is relevant, particularly in SMEs, due to their importance in the economy of all countries, and specifically by the women who work in them, since their participation is gaining more and more preponderance in the Mexican labor force. It is because of the above that the objective of the research was to analyze the effect of environmental knowledge and perceived behavioral control on the employee green behavior of female employees of small and medium enterprises (SMEs) in Ensenada, Baja California. The study is characterized by having a quantitative approach, a non-experimental, exploratory design and a transverse temporal dimension. 240 questionnaires were applied to female employees of SMEs in Ensenada, Baja California. The data collected was analyzed using structural equation modeling based on the partial least squares technique. The results empirically reflect the following: environmental knowledge has a positive and statistically significant effect on perceived behavioral control and employee green behavior. Also, it was found that the perceived behavioral control variable had a positive and statistically significant effect on the employee green behavior of female employees of SMEs in Ensenada, Baja California. Lastly, it was found that environmental knowledge predicts perceived behavioral control which in turn predicts employee green behavior. In this sense, such findings allow us to consider environmental knowledge and perceived behavioral control as predictive variables of employee green behavior.
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