120 research outputs found

    No Place for Pointless Jobs: How Social Responsibility Impacts Job Performance

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    We address the question of how organizations’ practices of social responsibility impact their employees’ job performance. Independent studies have shown that job performance is influenced by how employees perceive the organization they work for and how they perceive the work they perform for the organization. Moreover, studies on the relationship between social responsibility and job performance have shown that employees’ perceptions of their organization mediate the relationship. What is thus far neglected, however, is whether and how their perceptions of work itself mediate the relationship as well. We derive a sequential mediation model according to which social responsibility improves job performance by contributing to a supportive and trustworthy work context (employees’ perceptions of the organization they work for), in turn promoting work meaningfulness and engagement (employees’ perceptions of work itself). We collect survey data and test the sequential mediation model against a series of alternative models, each of which challenges a specific assumption of the proposed model. Our model provides the best tradeoff between the accuracy and the parsimony with which it describes the data collected, and is, therefore, expected to generalize best to other data.info:eu-repo/semantics/publishedVersio

    Impact of inoculum size on mead aroma compounds formation by wine strains of S. cerevisiae

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    Mead is a traditional drink, containing 8-18% (v/v) of ethanol, which results from the alcoholic fermentation of diluted honey performed by yeasts. It has been reported that mead fermentation is a time-consuming process, and an important objective of mead makers is to reduce the fermentation time without decreasing the quality of the end product. A significant time can be saved in the fermentation process by increasing the pitching rate, i.e., the amount of suspended yeast cells added to a batch fermenter. However, an increase in the inoculum size could also have deleterious side effects on the flavour profile of the final beverage. Therefore, the aim of this study was to investigate the impact of the inoculum size of two commercial winemaking strains of Saccharomyces cerevisiae (Lalvin QA23 and Lalvin ICV D47) on the mead volatile aromatic compound production. Honey must was prepared according to the recipe developed by our team, supplemented with potassium tartrate, pH adjusted to 3.7 with malic acid and the nitrogen concentration adjusted to 267 mg/L with diammonium phosphate. The appropriate amounts of inoculum were pitched into the honey-must to obtain five different pitching rates. Mead produced was analysed for major volatile compounds by GC-FID and for minor volatile compounds by GC-MS. A total of twenty-seven fermentative aroma compounds including alcohols, esters, volatile phenols, volatile fatty acids and carbonyl compounds were identified and quantified in meads. It was observed quantitative differences in aroma profiles, confirming the contribution of both yeast strain and inoculum size on the sensory characteristics of meads. Of the twenty-seven volatile compounds quantified, fourteen could contribute to mead aroma and flavour because their concentrations rose above their respective thresholds. In general, the formation of these compounds was particularly pronounced at low pitching rates. The esters ethyl hexanoate, ethyl octanoate and isoamyl acetate were the most powerful odorants detected in all meads. In addition to this quantitative analysis of the impact of strain selection and inoculum size on mead aroma, a complementary sensorial evaluation of the meads would yield further useful information for mead producers

    Effect of Saccharomyces cerevisiae cells immobilisation on mead production

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    Mead is a traditional alcoholic beverage obtained by the fermentation of diluted honey performed by yeasts. In this work the potential of application of immobilised yeast cells on single-layer Ca-alginate or double-layer alginateechitosan for mead production was assessed for the first time. The meads produced either with entrapped or free cells were evaluated in terms of quality and aroma profile. The immobilisation procedure had no adverse effect on cell viability, since minor differences were found in fermentation kinetics among the strains and immobilisation systems. The double-layer alginate-chitosan had no advantage compared with the single-layer Ca-alginate, as the number of free cells in the medium, resulting from cell leakage, was similar. Although meads obtained with entrapped yeast cells presented less ethanol and glycerol and more acetic acid, it exhibited larger amounts of volatile compounds. Immobilised cells produced meads with more compounds with fruity characteristics, such as ethyl octanoate and ethyl hexanoate; however the concentrations of undesirable compounds in such meads were also higher. The effect of immobilisation on the aroma profile was important, but the strain contribution was also of major importance. Thus, the sensory analysis of final product gives an important insight on the overall quality.The research presented in this paper was partially funded by the Fundacdo para a Ciencia e Tecnologia, (FCT) and by PTDC projects (contracts PTDC/AGR-ALI/68284/2006). A.P.P. is a recipient of a Ph.D. grant from the FCT (SFRH/BD/45820/2008)

    Effect of nitrogen supplementation on yeast fermentation performance and mead quality

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    Mead is a traditional drink, containing X-1 X% (v/v) of ethanol, which results from the alcoholic fermentation of diluted honey performed by yeasts. However, when it is produced in a homemade way mead producers find several problems, namely, the lack of uniformity in the final products low or premature fermentations arrest, and the production of "off-flavours" by the yeasts. These problems could be due to several factors, including lack of essential nutrients such as a deficiency in available nitrogen. Additionally , it has been reported that mead fermentation is a time-consuming process, often taking several months to complete. depending on the type of honey, yeast strain anti honey-must composition. Since mead production is a time-consuming process. to make its production viable it is necessary to reduce the fermentation time while producing an end product of quality. Thus. the aim of this study was to evaluate I he effect of nitrogen addition 10 honey-must on two active dry wine yeasts (ADWY) fermentation performance, as well as on the mead composition and volatile aroma compounds production

    Initial Solution Heuristic for Portfolio Optimization of Electricity Markets Participation

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    Meta-heuristic search methods are used to find near optimal global solutions for difficult optimization problems. These meta-heuristic processes usually require some kind of knowledge to overcome the local optimum locations. One way to achieve diversification is to start the search procedure from a solution already obtained through another method. Since this solution is already validated the algorithm will converge easily to a greater global solution. In this work, several well-known meta-heuristics are used to solve the problem of electricity markets participation portfolio optimization. Their search performance is compared to the performance of a proposed hybrid method (ad-hoc heuristic to generate the initial solution, which is combined with the search method). The addressed problem is the portfolio optimization for energy markets participation, where there are different markets where it is possible to negotiate. In this way the result will be the optimal allocation of electricity in the different markets in order to obtain the maximum return quantified through the objective function.This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 641794 (project DREAM-GO) and from FEDER Funds through COMPETE program and from National Funds through FCT under the project UID/EEA/00760/2013.info:eu-repo/semantics/publishedVersio

    Reduction of volatile acidity of wines by selected yeast strains

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    Herein we isolate and characterize wine yeasts with ability to reduce volatile acidity of wines using a refermentation process, which consists in mixing the acidic wine with freshly crushed grapes or musts or, alternatively, in the incubation with the residual marc. From a set of 135 yeast isolates, four strains revealed ability to use glucose and acetic acid simultaneously. Three of them were identified as Saccharomyces cerevisiae and one as Lachancea thermotolerans. Among nine commercial S. cerevisiae strains, strains S26, S29 and S30 display similar glucose and acetic acid initial simultaneous consumption pattern and were assessed in refermentation assays. In a medium containing an acidic wine with high glucose/low ethanol concentrations, under low oxygen availability, strain S29 is the most efficient one, whereas L. thermotolerans 44C is able to decrease significantly acetic acid similar to the control strain Zygosaccharomyces bailii ISA 1307, but only under aerobic conditions. Conversely, for low glucose/high ethanol concentrations, under aerobic conditions, S26 is the most efficient acid degrading strain, while under limited-aerobic conditions, all the S. cerevisiae strains studied display acetic acid degradation efficiencies identical to Z. bailii. Moreover, S26 strain also reveals capacity to decrease volatile acidity of wines. Together, the S. cerevisiae strains characterized herein appear promising for the oenological removal of volatile acidity of acidic wines.Fundação para a Ciência e a Tecnologia (FCT) - Programa POCI 2010 (FEDER/FCT, POCI/AGR/56102/2004, PTDC/AGRALI/71460/2006

    PI3K-δ and PI3K-γ Inhibition by IPI-145 Abrogates Immune Responses and Suppresses Activity in Autoimmune and Inflammatory Disease Models

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    SummaryPhosphoinositide-3 kinase (PI3K)-δ and PI3K-γ are preferentially expressed in immune cells, and inhibitors targeting these isoforms are hypothesized to have anti-inflammatory activity by affecting the adaptive and innate immune response. We report on a potent oral PI3K-δ and PI3K-γ inhibitor (IPI-145) and characterize this compound in biochemical, cellular, and in vivo assays. These studies demonstrate that IPI-145 exerts profound effects on adaptive and innate immunity by inhibiting B and T cell proliferation, blocking neutrophil migration, and inhibiting basophil activation. We explored the therapeutic value of combined PI3K-δ and PI3K-γ blockade, and IPI-145 showed potent activity in collagen-induced arthritis, ovalbumin-induced asthma, and systemic lupus erythematosus rodent models. These findings support the hypothesis that inhibition of immune function can be achieved through PI3K-δ and PI3K-γ blockade, potentially leading to significant therapeutic effects in multiple inflammatory, autoimmune, and hematologic diseases

    Initial Solution Heuristic for Portfolio Optimization of Electricity Markets Participation

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    Meta-heuristic search methods are used to find near optimal global solutions for difficult optimization problems. These meta-heuristic processes usually require some kind of knowledge to overcome the local optimum locations. One way to achieve diversification is to start the search procedure from a solution already obtained through another method. Since this solution is already validated the algorithm will converge easily to a greater global solution. In this work, several well-known meta-heuristics are used to solve the problem of electricity markets participation portfolio optimization. Their search performance is compared to the performance of a proposed hybrid method (ad-hoc heuristic to generate the initial solution, which is combined with the search method). The addressed problem is the portfolio optimization for energy markets participation, where there are different markets where it is possible to negotiate. In this way the result will be the optimal allocation of electricity in the different markets in order to obtain the maximum return quantified through the objective function.This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 641794 (project DREAM-GO) and from FEDER Funds through COMPETE program and from National Funds through FCT under the project UID/EEA/00760/2013.info:eu-repo/semantics/publishedVersio
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