The shift team formation problem in multi-shift manufacturing operations

This paper addresses the problem of assigning operators to teams that work in single-, two-, or three-day shift systems. The problem was motivated by, and illustrated with a case situation encountered in Dutch manufacturing industry. The problem addressed forms an extension of cell formation problems which are currently in the phase of addressing labor-related issues in cell design. A generalized goal problem formulation is presented to address multiple, conflicting objectives covering cross-training of workers, ensuring adequate levels of labor flexibility and minimizing labor-related costs. The proposed solution procedure consists of two phases. In the first phase, shift systems, in which applicable machines and the sizes of each shift team are identified. The next phase deals with assignment of operators to various teams and identification of specific cross-training needs for various workers. This phase involves the use of interactive goal programming. The methodology is illustrated by details from the case situation as well as a numerical example.

Beyond the Fe-P-redox connection: preferential regeneration of phosphorus from organic matter as a key control on Baltic Sea nutrient cycles

Patterns of regeneration and burial of phosphorus (P) in the Baltic Sea are strongly dependent on redox conditions. Redox varies spatially along water depth gradients and temporally in response to the seasonal cycle and multidecadal hydrographic variability. Alongside the well-documented link between iron oxyhydroxide dissolution and release of P from Baltic Sea sediments, we show that preferential remineralization of P with respect to carbon (C) and nitrogen (N) during degradation of organic matter plays a key role in determining the surplus of bioavailable P in the water column. Preferential remineralization of P takes place both in the water column and upper sediments and its rate is shown to be redox-dependent, increasing as reducing conditions become more severe at greater water-depth in the deep basins. Existing Redfield-based biogeochemical models of the Baltic may therefore underestimate the imbalance between N and P availability for primary production, and hence the vulnerability of the Baltic to sustained eutrophication via the fixation of atmospheric N. However, burial of organic P is also shown to increase during multidecadal intervals of expanded hypoxia, due to higher net burial rates of organic matter around the margins of the deep basins. Such intervals may be characterized by basin-scale acceleration of all fluxes within the P cycle, including productivity, regeneration and burial, sustained by the relative accessibility of the water column P pool beneath a shallow halocline

Динаміка мітотичної активності клітин меристеми хвої модрини західної (Larix occidentalis Nutt.)

У результаті дослідження динаміки мітотичної активності клітин меристеми хвої модрини західної (Larix occidentalis Nutt.) визначено, що максимальна кількість клітин, які діляться, припадає на ранкові години доби (6 – 9 години). Графік динаміки має двовершинний характер з піками о 7-ій та о 9-ій годинах ранку.В результате исследований динамики митотической активности клеток меристемы хвои лиственницы западной (Larix occidentalis) установлено, что максимальное количество делящихся клеток обнаруживается в утренние часы суток (6 – 9 часов). График динамики имеет двухвершинный тип с пиками в 7 и 9 часов утра.Results of researches for dynamics of mitotic activity of merystem cells of Western larch (Larix occidentalis Nutt.) needles show, that maximal amount of divided cells was found out at 6 – 9 o'clock in the morning. The graph of dynamics has bimodal type with the peaks at 7 and at 9 o'clock in the morning

Evaluating the Impact of Career Development Services in Canada: The Perceptions of Managers and Program Administrators

Abstract Academics and policy makers have clearly identified the urgent need to strengthen the evidence base attesting to the efficacy of career development services. However, it is unclear whether those providing career development services also recognize the importance of evaluation and are able to engage in evaluation in an effective manner. This article presents research that examines the value agency managers and program administrators place on evaluation and the perceived barriers they experience in conducting evaluations. This article also proposes solutions to the barriers to evaluation described by agency managers and program administrators. Academics and policy makers have identified the urgent need to strengthen the evidence base attesting to the efficacy of career development services. However, it is unclear as to whether those providing front-line career development services understand the importance of evaluation and are able to effectively engage in the evaluation process. The purpose of the research described in this article was to examine the importance managers and program administrators place on evaluating the efficacy of their services. The purpose of this research was to also examine whether managers and program administrators experience any barriers impeding their evaluation efforts. This article will examine the results and implications of this research. As well, it will provide remedies to the barriers described by agency managers and program administrators

Recovery from multi‐millennial natural coastal hypoxia in the Stockholm Archipelago, Baltic Sea, terminated by modern human activity

Enhanced nutrient input and warming have led to the development of low oxygen (hypoxia) in coastal waters globally. For many coastal areas, insight into redox conditions prior to human impact is lacking. Here, we reconstructed bottom water redox conditions and sea surface temperatures (SSTs) for the coastal Stockholm Archipelago over the past 3000 yr. Elevated sedimentary concentrations of molybdenum indicate (seasonal) hypoxia between 1000b.c.e.and 1500c.e. Biomarker-based (TEX86) SST reconstructions indicate that the recovery from hypoxia after 1500c.e.coincided with a period of significant cooling (similar to 2 degrees C), while human activity in the study area, deduced from trends in sedimentary lead and existing paleobotanical and archeological records, had significantly increased. A strong increase in sedimentary lead and zinc, related to more intense human activity in the 18(th)and 19(th)century, and the onset of modern warming precede the return of hypoxia in the Stockholm Archipelago. We conclude that climatic cooling played an important role in the recovery from natural hypoxia after 1500c.e., but that eutrophication and warming, related to modern human activity, led to the return of hypoxia in the 20(th)century. Our findings imply that ongoing global warming may exacerbate hypoxia in the coastal zone of the Baltic Sea

Efficacy of natural antimicrobials in toothpaste formulations against oral biofilms in vitro

AbstractObjectivesTo evaluate the antimicrobial efficacies of two toothpaste formulations containing natural antimicrobials (herbal extracts and chitosan) against oral biofilms of different composition and maturational status.MethodsBacteria from a buffer suspension or fresh saliva were adhered for 2h to a salivary conditioning film and subsequently grown for 16h. Dual-species biofilms were prepared from Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, whilst multi-species biofilms were grown from freshly collected human saliva. Biofilms were exposed to 25wt% toothpaste supernatants. A chlorhexidine-containing mouthrinse and a buffer were used as positive- and negative-controls, respectively. Antibacterial efficacy was concluded from acute killing, bacterial removal, prevention of bacterial re-deposition and continued killing during re-deposition.ResultsThe herbal- and chitosan-based supernatants showed immediate killing of oral biofilm bacteria, comparable with chlorhexidine. Moreover, exposure of a biofilm to these supernatants or chlorhexidine, yielded ongoing killing of biofilm bacteria after exposure during re-deposition of bacteria to a matured 16h biofilm, but not to a much thinner initial biofilm formed by 2h adhesion only. This suggests that thicker, more matured biofilms can absorb and release oral antimicrobials.ConclusionsSupernatants based on herbal- and chitosan-based toothpastes have comparable immediate and ongoing antibacterial efficacies as chlorhexidine. Natural antimicrobials and chlorhexidine absorb in oral biofilms which contributes to their substantive action

Anthropogenic and climatic impacts on a coastal environment in the Baltic Sea over the last 1000 years

Coastal environments have experienced large ecological changes as a result of human activities over the last 100-200 years. To understand the severity and potential consequences of such changes, paleoenvironmental records provide important contextual information. The Baltic Sea coastal zone is naturally a vulnerable system and subject to significant human-induced impacts. To put the recent environmental degradation in the Baltic coastal zone into a long-term perspective, and to assess the natural and anthropogenic drivers of environmental change, we present sedimentary records covering the last 1000 years obtained from a coastal inlet (Gasfjarden) and a nearby lake (Lake Storsjon) in Sweden. We investigate the links between a pollen-based land cover reconstruction from Lake Storsjon and paleoenvironmental variables from Gasfjarden itself, including diatom assemblages, organic carbon (C) and nitrogen (N) contents, stable C and N isotopic ratios, and biogenic silica contents. The Lake Storsjon record shows that regional land use was characterized by small-scale agricultural activity between 900 and 1400 CE, which slightly intensified between 1400 and 1800 CE. Substantial expansion of cropland was observed between 1800 and 1950 CE, before afforestation between 1950 and 2010 CE. From the Gasfjarden record, prior to 1800 CE, relatively minor changes in the diatom and geochemical proxies were found. The onset of cultural eutrophication in Gasfjarden can be traced to the 1800s and intensified land use is identified as the main driver. Anthropogenic activities in the 20th century have caused unprecedented ecosystem changes in the coastal inlet, as reflected in the diatom composition and geochemical proxies. (c) 2018 Elsevier Ltd. All rights reserved.Peer reviewe