Low energy ohmmeter can be used to test sensitive circuits, other meters

Hazardous circuit ohmmeter is of sufficiently low energy output that it may be used to test extremely sensitive circuits safely, reliably, and accurately. A polyurethane-foam-lined aluminum case provided protection for the unit assembly

Network Structure, Efficiency, and Performance in WikiProjects

The internet has enabled collaborations at a scale never before possible, but the best practices for organizing such large collaborations are still not clear. Wikipedia is a visible and successful example of such a collaboration which might offer insight into what makes large-scale, decentralized collaborations successful. We analyze the relationship between the structural properties of WikiProject coeditor networks and the performance and efficiency of those projects. We confirm the existence of an overall performance-efficiency trade-off, while observing that some projects are higher than others in both performance and efficiency, suggesting the existence factors correlating positively with both. Namely, we find an association between low-degree coeditor networks and both high performance and high efficiency. We also confirm results seen in previous numerical and small-scale lab studies: higher performance with less skewed node distributions, and higher performance with shorter path lengths. We use agent-based models to explore possible mechanisms for degree-dependent performance and efficiency. We present a novel local-majority learning strategy designed to satisfy properties of real-world collaborations. The local-majority strategy as well as a localized conformity-based strategy both show degree-dependent performance and efficiency, but in opposite directions, suggesting that these factors depend on both network structure and learning strategy. Our results suggest possible benefits to decentralized collaborations made of smaller, more tightly-knit teams, and that these benefits may be modulated by the particular learning strategies in use.Comment: 11 pages, 5 figures, to appear in ICWSM 201

Unconventional Fermi surface instabilities in the Kagome Hubbard Model

We investigate the competing Fermi surface instabilities in the Kagome tight-binding model. Specifically, we consider onsite and short-range Hubbard interactions in the vicinity of van Hove filling of the dispersive Kagome bands where the Fermiology promotes the joint effect of enlarged density of states and nesting. The sublattice interference mechanism [Kiesel and Thomale, Phys. Rev. B Rapid Comm., in press.] allows us to explain the intricate interplay between ferromagnetic fluctuations and other ordering tendencies. On the basis of functional renormalization group used to obtain an adequate low-energy theory description, we discover finite angular momentum spin and charge density wave order, a two-fold degenerate d-wave Pomeranchuk instability, and f-wave superconductivity away from van Hove filling. Together, this makes the Kagome Hubbard model the prototypical scenario for several unconventional Fermi surface instabilities.Comment: 4+e pages, 5 figure

Variation within and among species in a pine arboretum

The primary objective of this study was to obtain estimates of variation patterns in specific taxonomic and growth characteristics, within and among species of pines. Twenty-three species growing in an arboretum on the Eastern Highland Rim near Tullahoma, Tennessee were examined. The species were established in plantations of approximately one acre each, and varied in age from 5 to 17 years. Estimates of variation were desired to assess the dependability of the taxonomic characters and to indicate the amount of improvement attainable in future intra- and interspecific breeding programs. A secondary objective of the study was to determine the species with the best potential for planting in Tennessee. The taxonomic features of needle length, number of needles per fascicle, number and position of resin canals, and percent composition of cortical monoterpenes were analyzed for 23 species. Growth characters investigated included survival, stem height and volume growth. Additionally, wood specific gravity and extractive content were determined for the 17 species having mean diameters in excess of 3 inches. Results of the taxonomic analysis verified the identity of the species and generally confirmed the accepted taxonomic grouping of pines. External morphological features displayed the most variation among species and were thus the most dependable as taxonomic characters. However, internal needle morphology and cortical monoterpenes provide additional characters when external morphological features are not sufficiently distinct, and can be most useful to those seeking to identify juvenile material. Species native to the Southeastern United States excelled in stem height and volume growth. On this basis loblolly, eastern white, and Virginia pine are recommended for timber production in Tennessee. Pond pine grew faster and produced more volume than any species except loblolly, and is highly recommended for further testing