Introducing Two New Weed Control Tools: A Smart Spray Wand and a Wildland Weed Treatment Time Model

Millions are spent managing invasive weeds on public lands each year. Wildland invasive weed treatment bids are based primarily on acreage or hours but can be influenced by variables that increase treatment time and cost. Often neither the agency contracting the treatment nor the contractor has a clear idea of the amount of time that will be involved based on these variables. This makes it difficult to develop an accurate budget or bid for invasive weed control projects. It also limits managers in seeking funding and justifying treatment costs. A model has been developed that can predict herbicide application time due to four variables, weed canopy cover, slope, land cover, and weed visibility. Other variables were explored. The “smart” spray wand (SSW) is a new precision tool used to develop this model. The SSW is a spray wand with an integrated GPS and a flow meter for use with any type of spray system. The wand records the GPS location, herbicide flow,application time, and associated data of each treatment spray point. This information provided necessary data for the treatment time model. Weed control total treatment time (TTot) was hypothesized to include both treatment time (Tt) and rest time (Rt). The development and benefits of a wildland weed treatment time model are discussed. An accurate treatment time model could 1) establish an accurate standard for contractors and land managers, 2) assist in planning and managing limited treatment resources, and 3) justify funding requests and expenditures. The primary influence of the model is due to weed canopy cover (p=2=0.5607), with smaller impacts by other variables. If canopy cover, slope, land cover, and weed visibility can be obtained for a weed control project, the model can be used

The Social Psychology of Identity and Intergroup Conflict: From Theory to Practice

Cataloged from PDF version of article.This paper reviews the seminal theories of social psychology which have guided scholarship on inter-group conflicts and describes how these theories have been used by conflict resolution practitioners to design Track Two diplomacy initiatives among citizens in conflict zones. The authors hope that such a review will provide scholars of conflict resolution and international politics with a better understanding of how complex social theories are adapted for use in the applied world, and how gaps between theory and practice can be identified and addressed. The paper begins with an overview of three of the main theoretical contributions of social psychology to the problem of inter-group conflict: social identity theory, stereotyping and prejudice, and contact theory. We then review how these theories have been applied by conflict resolution specialists in international and ethnic conflicts as they have sought to moderate intergroup hostilities in conflict zones. The paper concludes with an analysis of the gaps between theory and practice, namely: theory of change gap, transfer strategies gap, and unit of analysis gap. Finally, based on the reviewed social psychology research, the article makes policy recommendations about how these gaps between theory and practice can be narrowed. © 2011 International Studies Association

VLBA Imaging of NGC 4261: Symmetric Parsec-scale Jets and the Inner Accretion Region

We observed the nuclear region of NGC 4261 (3C270) with the VLBA at two frequencies (1.6 and 8.4 GHz) simultaneously. We find that the position angle of the parsec-scale radio axis agrees, within the errors, with the position angle of the VLA-scale jet. Our observations also reveal basically symmetric radio structures at both 1.6 and 8.4 GHz. Analysis of these images shows that most of the central 10 pc of this source is not significantly affected by free-free absorption, even though HST images show that the nucleus contains a nearly edge-on disk of gas and dust on larger scales. Our highest angular resolution image shows a very narrow gap in emission, which we interpret as an absorption feature, just east of the radio core. This suggests that there may be a small, dense inner accretion disk whose width is less than 0.1 pc. If the inclination of this inner disk is close to that of the larger-scale HST disk it becomes optically thin to 8.4 GHz radiation at a deprojected radius of about 0.8 pc. The brightness of the pc-scale jets falls off very rapidly on both sides of the core, suggesting that the jets are rapidly expanding during the the first several pc of their travel. It appears that there is a small dense inner disk centered on the radio core (the base of the jets; less than 1 pc), a low density bubble filling most of the the inner several pc of the nucleus (within which the radio jets expand rapidly; ~10 pc), and a surrounding cool, higher density region (of which the HST absorption disk is part; tens to hundreds of pc) within which the transverse expansion of the radio jets, as implied by the rate of decrease in jet brightness, is nearly halted.Comment: Accepted by the Astrophysical Journa

The Radio Jets and Accretion Disk in NGC 4261

The structure of AGN accretion disks on sub-parsec scales can be probed through free-free absorption of synchrotron emission from the base of symmetric radio jets. We present new VLBA observations of the nearby FR-I radio galaxy NGC 4261 at 22 and 43 GHz, and combine these with previous VLBA observations at 1.6 and 8.4 GHz to map absorption caused by an inner accretion disk. Assuming the disk is geometrically and optically thin and composed of a uniform 10^4 K plasma, the average electron density in the inner 0.1 pc is 10^3 - 10^8 cm^-3. Equating thermal gas pressure and magnetic field strength gives a disk magnetic field of 10^-4 - 10^-2 Gauss at 0.1 pc. The jet opening angle is between 0.3 and 20 degrees during the first 0.2 pc of the jet, and must be less than 5 degrees during the first 0.8 pc. We include an appendix containing expressions for a simple, optically thin, gas pressure dominated accretion disk model which may be applicable to other galaxies in addition to NGC 4261.Comment: 15 pages plus 6 postscript figures, accepted by Ap

Preliminary Canopy Removal Experiments in Algal Dominated Communities Low on the Shore and in the Shallow Subtidal on the Isle of Man

The algal dominated communities immediately above and below the low-water spring level on a moderately exposed Manx shore were investigated by canopy removal experiments. Fucus serratus, Laminaria digitata and L. hyperborea were removed. Competition was shown to be important in determining the zonation of L. digitata and the distribution along the wave exposure gradient of other species such as Alaria esculenta, Desmarestia aculeata and D. viridis, and L. saccharina. Many species of algal epiphytes were early colonizers of canopy removal areas suggesting that competition from canopy algae usually restricts them to an epiphytic habit. The results indicate that interactions between macrophytes are much more important than grazing in structuring these communities

Some seasonal chemical changes in the open ocean

Several studies have been made of the seasonal changes in th, chemical composition of sea water, especially of the so-called nutrient substances. But most of these have been in localities relatively near shore and in the temperate zones where climatic fluctuations are relatively great. During the years 1937 and 1938 an opportunity arose to study such changes in the open ocean in connection with an investigation of the variations of the Gulf Stream (Iselin, 1940)