Mapping the multicausality of Alzheimer's disease through group model building.

Alzheimer's disease (AD) is a complex, multicausal disorder involving several spatiotemporal scales and scientific domains. While many studies focus on specific parts of this system, the complexity of AD is rarely studied as a whole. In this work, we apply systems thinking to map out known causal mechanisms and risk factors ranging from intracellular to psychosocial scales in sporadic AD. We report on the first systemic causal loop diagram (CLD) for AD, which is the result of an interdisciplinary group model building (GMB) process. The GMB was based on the input of experts from multiple domains and all proposed mechanisms were supported by scientific literature. The CLD elucidates interaction and feedback mechanisms that contribute to cognitive decline from midlife onward as described by the experts. As an immediate outcome, we observed several non-trivial reinforcing feedback loops involving factors at multiple spatial scales, which are rarely considered within the same theoretical framework. We also observed high centrality for modifiable risk factors such as social relationships and physical activity, which suggests they may be promising leverage points for interventions. This illustrates how a CLD from an interdisciplinary GMB process may lead to novel insights into complex disorders. Furthermore, the CLD is the first step in the development of a computational model for simulating the effects of risk factors on AD

Impacts of Deep Oil Spills on Fish and Fisheries

The Gulf of Mexico (GoM) total fishery production varies around one million metric tons per year. Fishery production is based on a diverse set of invertebrate and finfish species, including estuarine, continental shelf, and open-ocean species. The GoM has been subjected to two large oil spills in the Southern (Ixtoc 1, 1979–1980) and in the Northern GoM (Deepwater Horizon 2010) that caused serious concern about impacts on the abundance and seafood safety of fishery resources. Scientific evidence does not indicate a collapse or a clear impact on long-term fishery productivity related to either the Ixtoc 1 or DWH oil spills. Fishery landings in the Northern GoM returned quickly to pre-spill levels, and short-term declines could be attributed to the extensive fishery closure in the US exclusive economic zone. In the Southern GoM, fishery production post-Ixtoc 1 decreased dramatically over time attributed primarily to overharvesting of the main target species. Although no oil spill impact on the fishery resources was apparent at the population level, there is considerable evidence of impacts at the organismal and sub-individual levels, and there is concern how these effects could impact fishery resources in the long term. The responses of fish and shellfish populations are analyzed in relation to reproductive strategies, distribution of nursery grounds and critical habitats, exploitation status, oil spill distribution, and overall pollution levels. Fish and shellfish populations show a high capacity to withstand/recover from natural and anthropogenic impacts by taking advantage of favorable environmental conditions and by evolving life history strategies robust to seasonal and interannual variability. Stock resiliency is affected by several factors but mainly overharvesting that may reduce reproductive potential and compromise fishery resource resiliency in the eventual case of another large-scale oil spill disaster

Hyper-dendritic nanoporous zinc foam anodes

The low cost, significant reduction potential and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work, we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1–96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrast to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~88% at full depth-of-discharge (DOD) at various rates indicating a superb rate capability. The rechargeability of Zn0/Zn2+ showed significant capacity retention over 100 cycles at a 40% DOD to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge–discharge cycling and presented superior performance compared with bulk zinc electrodes