Sharing Supermodular Costs

We study cooperative games with supermodular costs. We show that supermodular costs arise in a variety of situations; in particular, we show that the problem of minimizing a linear function over a supermodular polyhedron—a problem that often arises in combinatorial optimization—has supermodular optimal costs. In addition, we examine the computational complexity of the least core and least core value of supermodular cost cooperative games. We show that the problem of computing the least core value of these games is strongly NP-hard and, in fact, is inapproximable within a factor strictly less than 17/16 unless P = NP. For a particular class of supermodular cost cooperative games that arises from a scheduling problem, we show that the Shapley value—which, in this case, is computable in polynomial time—is in the least core, while computing the least core value is NP-hard.National Science Foundation (U.S.) (DMI-0426686

The relationship between baseball participation and health: A systematic scoping review

Objective: To investigate the relationship between baseball participation and health (musculoskeletal, general, and psychological health) and to identify research gaps in the existing literature. Design: Systematic scoping review. Literature Search: Medical databases and gray literature were systematically searched from inception to November 2018. Study Selection Criteria: All studies that investigated constructs related to the health of current or former baseball players were included. Data Synthesis: Data were extracted for thematic summaries. Results: Ten thousand five hundred seventy-four titles/abstracts were screened, and 678 studies were included. Ninety percent of articles included only baseball players playing in the United States, 34% of articles investigated professional baseball players, and 11% studied college baseball players. Five hundred eighty-three (86%) studies investigated musculoskeletal health, 77 (11%) general health, and 18 (3%) psychological health. Injury incidence (injuries per 1000 athlete exposures) ranged from 0.7 to 3.6 in professional, 4.7 to 5.8 in college, and 0.8 to 4.0 in high school baseball. Among baseball players, 31% to 50% reported regular tobacco use. There was limited research investigating psychological health in current or former baseball players at all competition levels. Conclusion: Almost 90% of all articles investigated musculoskeletal health, with few articles studying general or psychological health. Baseball players have high tobacco, alcohol, and drug use compared to the general population, which may have negative health outcomes. Little is understood about the long-term musculoskeletal, general, and psychological health of baseball players.</p

Links between the presence of snowpacks and groundwater recharge – Simulation results for the territory of Slovenia

The implementation process of the EU water legislation (EU WFD, EU GWD) has put pressure on hydrogeologists to create, analyse and disseminate groundwater recharge maps in high temporal and spatial resolution for sustainable water management. The distributed water balance model mGROWA is currently applied in several European countries in order to create such maps. Applying mGROWA to country-specific prevailing climatic and hydrogeological conditions requires adaptations of the methodology with regard to the model setup and implementation. In contrast to many lowland regions in Western and Southern Europe, groundwater recharge in many Slovenian aquifers is limited during winter months due to water retention in snowpacks. Against this background the mGROWA model has been enhanced in a Slovenian-German research cooperation by procedures for the simulation of relevant processes associated with formation and melting of snowpacks. In combination with the multi-layer soil water balance module which was already implemented in mGROWA, this new feature enables a realistic simulation of inner-annual variations of groundwater recharge patterns in European alpine and highland areas in daily time-steps on a 100 m grid.In this contribution we briefly introduce the mGROWA methodology and the newly implemented snowpack module. Subsequently, model results for the reference period 1971-2014 are shown. This includes on one hand the evaluation of the simulated snowpack presence by using observations at about 400 sites and an assessment of the evolution of days with snowpack during winter. On the other hand, simulated groundwater recharge rates are evaluated with observed stream flow hydrographs and base-flow derived from these. In this context, also the impact of simulating temporal snowpack presence on groundwater recharge patterns is presented and discussed with a few examples. Finally, the consequences of addressing snowpacks in groundwater recharge assessments will be discussed with regard to the implications for management strategies for sustainable use of groundwater resources in Alpine regions

Diversification of fuel costs accounting for load variation

A practical mathematical programming model for the strategic fuel diversification problem is presented. The model is designed to consider the tradeoffs between the expected costs of investments in capacity, operating and maintenance costs, average fuel costs, and the variability of fuel costs. In addition, the model is designed to take the load curve into account at a high degree of resolution, while keeping the computational burden at a practical level. The model is illustrated with a case study for Indiana's power generation system. The model reveals that an effective means of reducing the volatility of the system-level fuel costs is through the reduction of dependence on coal-fired generation with an attendant shift towards nuclear generation. Model results indicate that about a 25% reduction in the standard deviation of the generation costs can be achieved with about a 20–25% increase in average fuel costs. Scenarios that incorporate costs for carbon dioxide emissions or a moratorium on nuclear capacity additions are also presented

Potential transfer of aquatic organisms via ballast water with a particular focus on harmful and non-indigenous species: A survey from Adriatic ports

Ballast water discharges may cause negative impacts to aquatic ecosystems, human health and economic activities by the introduction of potentially harmful species. Fifty untreated ballast water tanks, ten in each port, were sampled in four Adriatic Italian ports and one Slovenian port. Salinity, temperature and fluorescence were measured on board. Faecal indicator bacteria (FIB), phyto- and zooplankton were qualitatively and quantitatively determined to identify the species assemblage arriving in ballast water. FIB exceeded the convention standard limits in 12% of the sampled tanks. Vibrio cholerae was not detected. The number of viable organisms in the size groups (minimum dimension) <50 and ≥10 μm and ≥50 μm resulted above the abundances required from the Ballast Water Management Convention in 55 and 86% of the samples, respectively. This is not surprising as unmanaged ballast waters were sampled. Some potentially toxic and non-indigenous species were observed in both phyto- and zooplankton assemblages