Connectivity Explains Local Ant Community Structure in A Neotropical Forest Canopy: A Large‐Scale Experimental Approach

Understanding how habitat structure and resource availability affect local species distributions is a key goal of community ecology. Where habitats occur as a mosaic, variation in connectivity among patches influences both local species richness and composition, and connectivity is a key conservation concern in fragmented landscapes. Similarly, availability of limiting resources frequently determines species coexistence or exclusion. For primarily cursorial arthropods like ants, gaps between neighboring trees are a significant barrier to movement through the forest canopy. Competition for limited resources such as nest sites also promotes antagonistic interactions. Lianas (woody vines) connect normally isolated neighboring tree crowns and often have hollow stems inhabited by ants. We used two large‐scale liana‐removal experiments to determine how connectivity and nest site availability provided by lianas affect arboreal ant species richness, species composition, and β‐diversity in a lowland tropical forest in Panama. Removing lianas from a tree crown reduced ant species richness up to 35%, and disproportionately affected species that require large foraging areas. Adding artificial connectivity to trees mitigated the effects of liana removal. Ant colonization of artificial nests was higher (73% occupied) in trees without lianas vs. trees with lianas (28% occupied). However, artificial nests typically were colonized by existing polydomous, resident ant species. As a result, nest addition did not affect ant community structure. Collectively, these results indicate that lianas are important to the maintenance of arboreal ant diversity specifically by providing connectivity among neighboring tree crowns. Anticipated increases in liana abundance in this forest could increase the local (tree‐level) species richness of arboreal ants, with a compositional bias toward elevating the density of broad‐ranging specialist predators

Household demand persistence for child micronutrient supplementation.

Addressing early-life micronutrient deficiencies can improve short- and long-term outcomes. In most contexts, private supply chains will be key to effective and efficient preventative supplementation. With established vendors, we conducted a 60-week market trial for a food-based micronutrient supplement in rural Burkina Faso with randomized price and non-price treatments. Repeat purchases - critical for effective supplementation - are extremely price sensitive. Loyalty cards boost demand more than price discounts, particularly in non-poor households where the father is the cardholder. A small minority of households achieved sufficient supplementation for their children through purely retail distribution, suggesting the need for more creative public-private delivery platforms informed by insights into household demand persistence and heterogeneity

Integrating Economic Analysis with a Randomized Controlled Trial: Willingness-to-Pay for a New Maternal Nutrient Supplement

Maternal nutrition during pregnancy can have significant implications for a child’s prenatal growth and development, and undernutrition experienced during the prenatal period increases the risk of early childhood morbidity and mortality and can permanently impair a child’s physical growth and cognitive development. We use new data from Ghana generated using contingent valuation and experimental auction techniques to estimate willingness-to-pay (WTP) for LNS, a new nutrient supplement aimed at preventing maternal undernutrition during pregnancy. We also explore the relative importance of individual and household characteristics as well as information about the long-term benefits of preventing undernutrition on WTP. We find that WTP is positive for a large majority of individuals in our samples, and the level of WTP varies significantly with individual and household characteristics including gender, household food insecurity, and household expenditures. These findings suggest important policy implications for the development of delivery options and pricing mechanisms for LNS.Economic Development, Nutrition, Willingness-to-Pay, Food Consumption/Nutrition/Food Safety, Health Economics and Policy, International Development,

Dephasing of Electrons on Helium by Collisions with Gas Atoms

The damping of quantum effects in the transport properties of electrons deposited on a surface of liquid helium is studied. It is found that due to vertical motion of the helium vapour atoms the interference of paths of duration $t$ is damped by a factor $\exp - (t/\tau_v)^3$. An expression is derived for the weak-localization lineshape in the case that damping occurs by a combination of processes with this type of cubic exponential damping and processes with a simple exponential damping factor.Comment: 7 pages, 2 figures, Revte

Another possible way to determine the Neutrino Mass Hierarchy

We show that by combining high precision measurements of the atmospheric delta m^2 in both the electron and muon neutrino (or anti-neutrino) disappearance channels one can determine the neutrino mass hierarchy. The required precision is a very challenging fraction of one per cent for both measurements. At even higher precision, sensitivity to the cosine of the CP violating phase is also possible. This method for determining the mass hierarchy of the neutrino sector does not depend on matter effects.Comment: 12 pages, 3 postscript figures, late

Empirically Measuring Transfer Distance for System Design and Operation

Classical machine learning approaches are sensitive to non-stationarity. Transfer learning can address non-stationarity by sharing knowledge from one system to another, however, in areas like machine prognostics and defense, data is fundamentally limited. Therefore, transfer learning algorithms have little, if any, examples from which to learn. Herein, we suggest that these constraints on algorithmic learning can be addressed by systems engineering. We formally define transfer distance in general terms and demonstrate its use in empirically quantifying the transferability of models. We consider the use of transfer distance in the design of machine rebuild procedures to allow for transferable prognostic models. We also consider the use of transfer distance in predicting operational performance in computer vision. Practitioners can use the presented methodology to design and operate systems with consideration for the learning theoretic challenges faced by component learning systems

Fundamental approach for optoelectronic and microfluidic integration for miniaturizing spectroscopic devices

We have described an approach for miniaturizing spectroscopic devices by using the advantages presented by elastomeric based microfluidics and semiconductor detectors/emitters. Elastomers allow for both absorption and fluorescent spectroscopy in the visible range to be conducted on small volumes of solution and allow for easy integration with existing detectors such as CMOS imagers, CCD imagers, and silicon photodiodes. Results of some basic experiments are presented to demonstrate the effectiveness of the system. In addition, several ideas for emission sources are also discussed with their relevance yet to be determined