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Decisions in the natural world are rarely made in isolation. Each action that an organism selects will affect the future situations in which it finds itself, and those situations will in turn affect the future actions that are available. Achieving real-world goals often requires successfully navigating a sequence of many actions. An efficient and flexible way to achieve such goals is to construct an internal model of the environment, and use it to plan behavior multiple steps into the future. This process is known as multi-step planning, and its neural mechanisms are only beginning to be understood. Here, we review recent advances in our understanding of these mechanisms, many of which take advantage of multi-step decision tasks for humans and animals.

Cigarette use is a preventable cause of mortality and diseases. The World Health Organization states that Europe and especially Greece has the highest occurrence of smoking among adults. The prevalence of smoking among women in Greece was estimated to be over 30% in 2012. Smoking is a risk factor for many diseases. Studies have demonstrated the association between smoking and laryngeal pathologies as well as changes in voice characteristics. The purpose of this study was to estimate the effect of early smoking habit on young adult female voices and if they perceive any vocal changes using two assessment methods. The Voice Handicap Index and the acoustic analyses of voice measurements were used, with both serving as mini-assessment protocols. Two hundred and ten young females (110 smokers and 100 nonsmokers) attending the Technological Educational Institute of Epirus in the School of Health and Welfare were included. Statistically significant increases for physical and total scores of the Voice Handicap Index were found in the smokers group (P

Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine–basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine–basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid–medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (μ-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship σ bulk = C σ melt ϕ m with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06 . Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential influence of volatiles and melt films on electrical conductivity of partially molten rocks is discussed.

Melt percolation in mantle rocks is currently poorly constrained, especially at low melt fractions. At mid-ocean ridges, for example, geochemical and geophysical observations produce divergent estimates of how much melt is present in the mantle and how quickly it moves. Accurate estimates of permeability and grain-scale melt distribution in mantle rock are necessary to reconcile these observations. We present three-dimensional (3-D), 700 nm-resolution images of olivine–basalt aggregates, containing nominal melt fractions ( ϕ n ) between 0.02 and 0.20. Samples were prepared from a powdered mixture of San Carlos olivine and high-alumina basalt and hot-pressed in a solid-medium piston–cylinder apparatus at 1350 °C and 1.5 GPa. Images were obtained using synchrotron X-ray microtomography (SXμT) from the Advance Photon Source at Argonne National Laboratory. Stokes flow simulations, conducted using the digital melt volume as the numerical domain, determine that the permeabilities of experimental charges range from 2 × 10 − 16 to 5 × 10 − 13 m 2 for ϕ n = 0.02 to 0.20, respectively. The simulation results are well represented by the power-law relation between permeability (k) and melt fraction (ϕ), k = ϕ n d 2 / C , where n = 2.6 ± 0.2 , and assuming a grain size of 35 μm in the experiments, C = 58 − 22 + 36 . These results place important new constraints on rates of melt migration and melt extraction within partially molten regions of the mantle.

The popularity of the co-dependency concept has grown rapidly in the alcoholism treatment field. At the same time, empirical findings gained through scientific research have raised questions concerning the validity of the concept. This paper discusses some of the problems that are created by the disease model of co-dependency and highlights some alternatives views that may be more appropriate. It is argued that the field's understanding of the alcoholic/spouse relationship and its ability to help the spouse are limited unless other conceptualizations are seriously considered.