Ungaliophis, U. continentalis, U. panamensis

Number of Pages: 4Integrative BiologyGeological Science

The electrical response matrix of a regular 2n-gon

Consider a unit-resistive plate in the shape of a regular polygon with 2n sides, in which even-numbered sides are wired to electrodes and odd-numbered sides are insulated. The response matrix, or Dirichlet-to-Neumann map, allows one to compute the currents flowing through the electrodes when they are held at specified voltages. We show that the entries of the response matrix of the regular 2n-gon are given by the differences of cotangents of evenly spaced angles, and we describe some connections with the limiting distributions of certain random spanning forests.Comment: 10 pages, 4 figures; v2 adds more background informatio

Bitter taste stimuli induce differential neural codes in mouse brain.

A growing literature suggests taste stimuli commonly classified as "bitter" induce heterogeneous neural and perceptual responses. Here, the central processing of bitter stimuli was studied in mice with genetically controlled bitter taste profiles. Using these mice removed genetic heterogeneity as a factor influencing gustatory neural codes for bitter stimuli. Electrophysiological activity (spikes) was recorded from single neurons in the nucleus tractus solitarius during oral delivery of taste solutions (26 total), including concentration series of the bitter tastants quinine, denatonium benzoate, cycloheximide, and sucrose octaacetate (SOA), presented to the whole mouth for 5 s. Seventy-nine neurons were sampled; in many cases multiple cells (2 to 5) were recorded from a mouse. Results showed bitter stimuli induced variable gustatory activity. For example, although some neurons responded robustly to quinine and cycloheximide, others displayed concentration-dependent activity (p<0.05) to quinine but not cycloheximide. Differential activity to bitter stimuli was observed across multiple neurons recorded from one animal in several mice. Across all cells, quinine and denatonium induced correlated spatial responses that differed (p<0.05) from those to cycloheximide and SOA. Modeling spatiotemporal neural ensemble activity revealed responses to quinine/denatonium and cycloheximide/SOA diverged during only an early, at least 1 s wide period of the taste response. Our findings highlight how temporal features of sensory processing contribute differences among bitter taste codes and build on data suggesting heterogeneity among "bitter" stimuli, data that challenge a strict monoguesia model for the bitter quality

INVESTIGATION OF AN AFFORDABLE MULTIGRAIN THRESHER FOR SMALLHOLDER FARMERS IN SUB-SAHARAN AFRICA

As the global population rises, food security is among the most important grand challenges of our time. While agriculture has significantly developed in parts of the world, other parts are severely underdeveloped, inhibiting agriculture productivity, which is a necessary component of the solution to the food security challenge. Sub-Saharan Africa (SSA), in particular, has seen little growth in productivity, something that has been correlated to its low agricultural mechanization. One barrier to mechanization in SSA, where the average farm size is less than 2 Ha, is the cost of farm equipment. This leaves many farmers with just basic tools to perform farm operations. Threshing is a critical part of processing grains, which are staple crops in most countries. Traditional methods of threshing are time and energy consuming and can result in significant grain losses. Threshers that are available are imported, expensive, or too large for most farms

Physical, chemical, and sensory characteristics of dehydrated shiitake mushrooms

Shiitake mushrooms grown in Claiborne County, Tennessee were cryogenically frozen, held at -31°C until processing and then dehydrated in a Armfield forced-air, tray drier. The mushrooms were initially dried at 50°C for 3 hr and then finished at 40, 50, or 60°C for 6, 5 or 4 hr, respectively. The shiitake mushrooms were then evaluated for free glutamate (MSG), water soluble carbohydrates (WSC) and ninhydrin reactive materials (NRM), proximate composition, color, and flavor strength. The flavor strength was evaluated by a sensory panel of 8 members from Asian countries selected on the basis of their familiarity with shiitake flavor and sensory methodology. MSG and NRM were not significantly affected by dehydration conditions but increased under lower temperatures and longer times for dehydration and decreased slightly at higher temperatures and shorter times of dehydration. MSG increased from 3.11 mg/g in partially dehydrated shiitake to 3.12 mg/g in shiitake dried at 40°C for 6 hr, and decreased to 2.40 mg/g in the shiitake dried at 60°C for 4 hr. NRM increased from 29.2 mg/g to 32.8 mg/g and decreased to 25.1 mg/g under the same conditions. WSC was significantly affected by dehydration conditions. The WSC decreased from 3.63 mg/g in the partially dried shiitake to 2.47 mg/g in the shiitake dried at 60°C. The mushrooms dried at 50 and 40°C were significantly lower than the other treatments at 1.56 mg/g and 1.11 mg/g, respectively. The shiitake mushrooms are mostly water, 88.2%, and the solid content is 76% carbohydrates of which 9% is dietary fiber. The dehydration temperature and time did not affect the proximate composition of the mushroom caps and stems. However, the mushroom caps contained more moisture, protein and ash while the stems contained more dietary fiber. The mushrooms decreased in lightness from a Hunter L value of 66.2 in the partially dehydrated caps to 42.4-43.7 in the completely dried caps. Mushrooms that had second phase drying temperatures of 40 and 50°C had significantly stronger flavor than either freeze-dried mushrooms or mushrooms with a second phase drying temperature of 60°C. Mushrooms finished at 40 and 50°C were equal in flavor strength to two commercial shiitake samples and had a significantly stronger flavor than one commercial sample. Dehydrated stems were found to be similar in flavor to the dried caps

THE ADOPTION AND DIFFUSION OF LEVEL FIELDS AND BASINS

Strategic investments in agriculture often are lumpy and irreversible, with significant impacts on operating and fixed costs. Leveling cotton fields to zero slope in central Arizona is a strategic decision made by relatively younger farmers who are farming fine-textured soils in irrigation districts with higher expected water costs. The diffusion of the technology across the region between 1968-89 appears to be both a function of institutional changes (e.g., the Groundwater Management Act of 1980, the Central Arizona Project) and the long-run expected price changes induced by these new policies.Crop Production/Industries,