Establishment of the Alfalfa Weevil Parasite \u3ci\u3eMicroctonus Aethiopoides (Hymenoptera: Braconidae)\u3c/i\u3e in Michigan

Microctonus aethiopoides, a braconid parasite of adult alfalfa weevil, Hypera postica, is now established in southeastern Minnesota. Releases were made near Caledonia in Houston County, in 1978 and 1979, and near Rosemount in Dakota County, in 1979 and 1980. M. aethiopoides was recovered in Houston County in 1979, a new state record, and since has expanded its range more than 40 km from the release site. Establishment in Dakota County was unexpected because of low host densities, but parasites were recovered there in 1983. Other workers have recovered M. aethiopoides in Olmstead County

Natural Enemies of Alfalfa Weevil, \u3ci\u3eHypera Postica\u3c/i\u3e (Coleoptera: Curculionidae), in Minnesota

Alfalfa weevil, Hypera postica, is present throughout Minnesota. How- ever, economically damaging populations seldom occur, due to a combination of natural enemies and adverse climatic conditions. Five natural enemies of alfalfa weevil were found in Minnesota. Microctonus aethiopoides (Hymenoptera: Braconidae), a parasitoid of adults, was recovered from 43 of 65 counties surveyed during 1984 and 1985. Tetrastichus incertus (Hymenoptera: Eulophidae) and Bathyplectes curculionis (Hymenoptera: Ichneumonidae), para­sitoids of larvae, were each recovered from 13 of 15 counties surveyed during 1991-1993. Bathyplectes anurus, another parasitoid of larvae, was recovered from one county In 1991, four counties in 1992, and six counties in 1993. Zoophthora phytonomi (Entomophthora: Entomophthoraceae), a pathogen of larvae, was recovered from 14 of 15 counties surveyed in 1991-1993. Winters with low minimum temperatures and little snow cover were detrimental to the weevil. Usually, southeastern Minnesota has milder winters and higher alfalfa weevil populations than other areas of the State. However, even here, because of natural enemies, weevil populations seldom reach economically damaging levels

Producers' Use of Crop Borders for Management of Potato Virus Y (PVY) in Seed Potatoes

Potato virus Y (PVY) is a very serious problem throughout most major seed potato producing states. Seed potato producers in Minnesota and North Dakota were surveyed in early 2005 to assess their perception of the profitability and risks associated with using crop borders to manage PVY in seed lots. Five of the 23 producers responding (a 25% response rate) said they had used crop borders in 2004. These 23 producers entered 152 seed lots into state seed certification programs. On average, producers had less than 0.1 seed lots rejected for PVY based on summer inspection. The average number of seed lots rejected in winter trials was 1.7. Of the 152 seed lots, these producers said they had entered into state seed certification programs, they reported detailed information on 108 lots. Generations 1 and 2 were the most likely generations to be protected by a crop border. Of these 108 seed lots, 104 passed summer inspection for PVY. Seventy-four percent of the 89 lots sent in for the winter test were reported to have passed. The use of crop borders was significant in explaining whether a seed lot had passed the winter test or not. Thirty-one (97%) of the 32 seed lots that were planted within a crop border passed the winter test while 31 (54%) of the 57 seed lots that were not planted with a crop border passed the winter test. No relationship was found between the choice of border crop and passing the winter test. Producers also were asked to state their agreement or disagreement with several statements regarding their knowledge and opinions on use of crop borders.Crop Production/Industries,

ECONOMIC ANALYSIS OF USING A BORDER TREATMENT FOR REDUCING ORGANOPHOSPHATE USE IN SEED POTATO PRODUCTION

Recent research shows initial colonization of potato fields by winged green peach aphid is concentrated at field edges. This suggests that insecticides applied only to field margins during initial colonization would largely eliminate a colonizing aphid population, conserve natural enemies in the field center, and reduce insecticide use. To better understand the costs and benefits of reducing organophosphate use, the six participating growers were interviewed to ascertain their reason for participating and their satisfaction with the border only treatment method as well as their estimated net economic benefits. Five of the farms ranked cost reduction as the most important reason for participating. The sixth farm ranked reducing virus spread as the most important reason with cost reduction as their second most important reason. The average cost savings over all 28 participating fields of using the border treatment is estimated to be $23.85 per acre for the entire field-a 93% savings. Almost all the farmers found the border treatment method to be successful at aphid control. None of the farmers observed any impact on the physical yield of seed potato. All the fields were certified during the summer except for one of Farmer F's fields that was lost because of off type. In conclusion, the border treatment method seems likely to be adopted by many farmers since the potential cost saving is large and farmers dislike Monitor. However, some farmers may resist the method due to scouting requirements and costs. Also, farmers with fields that do not meet the uniformity requirements of the border treatment will not be successful in their use of the border method.Crop Production/Industries,

Multi-source self-calibration: Unveiling the microJy population of compact radio sources

Context. Very Long Baseline Interferometry (VLBI) data are extremely sensitive to the phase stability of the VLBI array. This is especially important when we reach {\mu}Jy r.m.s. sensitivities. Calibration using standard phase referencing techniques is often used to improve the phase stability of VLBI data but the results are often not optimal. This is evident in blank fields that do not have in-beam calibrators. Aims. We present a calibration algorithm termed Multi-Source Self-Calibration (MSSC) which can be used after standard phase referencing on wide-field VLBI observations. This is tested on a 1.6 GHz wide-field VLBI data set of the Hubble Deep Field-North and the Hubble Flanking Fields. Methods. MSSC uses multiple target sources detected in the field via standard phase referencing techniques and modifies the visibili- ties so that each data set approximates to a point source. These are combined to increase the signal to noise and permit self-calibration. In principle, this should allow residual phase changes caused by the troposphere and ionosphere to be corrected. By means of faceting, the technique can also be used for direction dependent calibration. Results. Phase corrections, derived using MSSC, were applied to a wide-field VLBI data set of the HDF-N comprising of 699 phase centres. MSSC was found to perform considerably better than standard phase referencing and single source self-calibration. All detected sources exhibited dramatic improvements in dynamic range. Using MSSC, one source reached the detection threshold taking the total detected sources to twenty. 60% of these sources can now be imaged with uniform weighting compared to just 45% with standard phase referencing. The Parseltongue code which implements MSSC has been released and made publicly available to the astronomical community (https://github.com/jradcliffe5/multi_self_cal).Comment: 7 pages, 4 figures, accepted to A&

The swimming pool nuclear reactor

http://hdl.handle.net/10945/14703http://www.archive.org/details/swimmingpoolnucl00radcU.S. Air Force (U.S.A.F.) author

El parentesco: textos fundamentales

En el conjunto de trabajos compilados se encuentran todos los problemas empíricos y teóricos capitales de los estudios del parentesco: su relación con la organización social (Tylor, Durkheim, Rivers); el análisis de las terminologías (Kroeber, Lounsbury); la relación de las mismas con las formas sociales (Kroeber, Rivers); la teoría extensionista (Evans-Pritchard); la del linaje (Goody) y la de la alianza (Lévi-Strauss, Needham), son los más importantes. Asimismo, están representadas la mayoría de las regiones del planeta: Oceanía (Durkheim, Needham), Asia (Dumont, Radcliffe-Brown), África (EvansPritchard, Goody) y las Américas (Kroeber, Eggan, Radcliffe-Brown, LéviStrauss, Lounsbury)

Nowhere to Hide: Radio-faint AGN in the GOODS-N field. I. Initial catalogue and radio properties

(Abridged) Conventional radio surveys of deep fields ordinarily have arc-second scale resolutions often insufficient to reliably separate radio emission in distant galaxies originating from star-formation and AGN-related activity. Very long baseline interferometry (VLBI) can offer a solution by identifying only the most compact radio emitting regions in galaxies at cosmological distances where the high brightness temperatures (in excess of $10^5$ K) can only be reliably attributed to AGN activity. We present the first in a series of papers exploring the faint compact radio population using a new wide-field VLBI survey of the GOODS-N field. The unparalleled sensitivity of the European VLBI Network (EVN) will probe a luminosity range rarely seen in deep wide-field VLBI observations, thus providing insights into the role of AGN to radio luminosities of the order $10^{22}~\mathrm{W\,Hz^{-1}}$ across cosmic time. The newest VLBI techniques are used to completely cover an entire 7'.5 radius area to milliarcsecond resolutions, while bright radio sources ($S > 0.1$ mJy) are targeted up to 25 arcmin from the pointing centre. Multi-source self-calibration, and a primary beam model for the EVN array are used to correct for residual phase errors and primary beam attenuation respectively. This paper presents the largest catalogue of VLBI detected sources in GOODS-N comprising of 31 compact radio sources across a redshift range of 0.11-3.44, almost three times more than previous VLBI surveys in this field. We provide a machine-readable catalogue and introduce the radio properties of the detected sources using complementary data from the e-MERLIN Galaxy Evolution survey (eMERGE).Comment: 15 pages, 8 figures, accepted in A&A. Machine-readable table available upon reques

Two-photon excitation and relaxation of the 3d-4d resonance in atomic Kr

Two-photon excitation of a single-photon forbidden Auger resonance has been observed and investigated using the intense extreme ultraviolet radiation from the free electron laser in Hamburg. At the wavelength 26.9 nm (46 eV) two photons promoted a 3d core electron to the outer 4d shell. The subsequent Auger decay, as well as several nonlinear above threshold ionization processes, were studied by electron spectroscopy. The experimental data are in excellent agreement with theoretical predictions and analysis of the underlying multiphoton processes