Circular 89

A yield trial in which 43 named varieties and numbered selections of potatoes were compared was conducted during the 1991 growing season at the University of Alaska Fairbanks, Agricultural and Forestry Experiment Station’s Palmer Research Center, Matanuska Research Farm, located six miles west of Palmer, Alaska. Varieties with a history of commercial production in the Matanuska Valley (Alaska 114, Bake-King, Green Mountain, and Superior) are included and serve as a comparative base for newly developed varieties, numbered selections or older varieties that have not been tested at this location. Varieties that compare favorably with the above listed standards may warrant consideration by commercial growers. Nonirrigated trials have been conducted annually since 1982, whereas irrigated trials were initiated in 1985 (AFES Circulars 49, 54, 58, 65, 71, 77, and 84). These circulars are available at the AFES Offices in Fairbanks and Palmer. Included in this report are the results of abbreviated versions of the AFES potato yield trial conducted by cooperating individuals and agencies at other locations in Alaska including Delta Junction, Fairbanks, Homer, Kenai- Soldotna, and Kodiak.[Part 1: Potato Variety Performance] -- Introduction -- Matanuska Farm Yield Trials -- Trials at Other Locations in Alaska -- [Part 2: Commercial Potato Crop Data Summary] -- Introduction -- Potato Varieties and Yields -- Acreage per grower -- Irrigation -- Seed and Planting -- Fertilizer -- Other Cultural Practices -- Chemical Contro

Carn Goedog medieval house and settlement, Pembrokeshire

This report describes the investigation in 2011 and 2015 of two groups of relict houses on an upland common on the north flank of the Preseli hills in North Pembrokeshire. Their locations, along with medieval records, provide strong indications that these were seasonal settlements. Excavation of one subrectangular building (House C) produced finds that included medieval pottery and a spindle whorl with Romanesque decoration. A radiocarbon date of cal. AD 1030–1200 at 95.4% confidence from charcoal in the hearth of this building provides the earliest firm date identified as yet for hafodydd (‘seasonal settlements’) in Wale

Occurrence of the orange wheat blossom midge [Diptera :Cecidomyiidae] in Quebec and its incidence on wheat grain microflora

À l'été 1995, on a prélevé des échantillons de blé (Triticum aestivum) dans des champs de diverses régions agricoles du Québec. La présence de larves de la cécidomyie orangée du blé (Sitodiplosis mosellana) fut quantifiée et une évaluation qualitative et quantitative de la microflore des grains fut réalisée. Les pertes moyennes de rendement causées par les larves de la cécidomyie du blé furent estimée à 6,3%. Le pourcentage des épis infestés fut significativement corrélé avec la contamination bactérienne et fongique des grains (r = 0,79). La présence spécifique du Fusarium graminearum dans les grains de blé fut aussi significativement corrélée avec le nombre de larves par épi (r= 0,67) ou par épillet (r= 0,67). Il appert que la cécidomyie du blé pourrait jouer un rôle dans la dissémination du F. graminearum.Samples of wheat spikes (Triticum aestivum) were collected in the summer of 1995 from different crop districts in Quebec and the occurrence of orange wheat blossom midge (Sitodiplosis mosellana) and seed microflora were determined. Estimated yield loss caused by wheat midge larvae averaged 6.3%. The percentage of infested spikes was significantly correlated with total seed contamination by fungi and bacteria (r = 0.79). The specific occurrence of Fusarium graminearum in grains was also significantly correlated with number of larvae per spike (r = 0.67) or per spikelet (r = 0.67). Consequently, the wheat midge might play a role in dissemination of F. graminearum

Chopped Arms & Big Macs: ERP Correlates of Viewing and Imagining Aversive and Food Photos

OBJECTIVES
We investigated the Event-Related Potential (ERP) correlates of perceived and imagined food photos and their relation to the perception and imagery of unpleasant emotional photos. Our aim was to determine whether similar or different patterns of neural activity were associated with viewing and imagining food photos versus emotional photos. 

METHODS 
Nine volunteers with prescreened normal mood and anxiety levels wore a 32 channel Cap with embedded electrodes (10/20 international system) connected to a high-density low-noise Neuroscan EEG system. Participants were tested during two different blocks: a hunger block (containing 25 neutral and food photos) and an emotional block (containing 3 sets of 20 neutral, unpleasant and pleasant photos). The photos were selected from the International Affective Picture System (Lang, Bradley, & Cuthbert, 1999). In both blocks, each trial began with a blank screen followed by presentation of a centered fixation point, displayed for 1 second. A photo was displayed for 3 seconds followed by a 1-second blank mask. For the next 3 seconds, participants were asked to form a mental image of the photo they had just viewed and then rate its vividness (i.e., the self-reported imagery intensity, D’Angiulli & Reeves, 2002) on a 5-point rating scale (1 = no image, 5 = very vivid). 

RESULTS
Grand averages of ERPs recorded during perception of unpleasant and food photos revealed an early negative deflection (150-250 milliseconds post-stimulus) in the anterior areas (Centro-Frontal electrodes) followed by a late positive waveform (850-950 milliseconds post-stimulus) in the posterior areas (Parietal and Occipital electrodes). A similar pattern was observed for the ERPs recorded during the imagery of unpleasant photos, except that it was observed across the entire scalp and at significantly lower amplitudes. For food imagery, we found a negative deflection (450-550 milliseconds post-stimuli) followed by a late positive waveform for all anterior and posterior areas. Importantly, unpleasant imagery was rated as less vivid than food imagery. 

CONCLUSION 
These results suggest that unpleasant and food photos involve similar top-down EEG activation patterns during perception, but not during imagery. Indeed, the vividness data strongly suggest that the negative deflection may indicate suppression of unpleasant imagery. Our findings may have important application for desensitization and conditioning in the treatment of eating disorders.
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Extensive dissolution of live pteropods in the Southern Ocean

The carbonate chemistry of the surface ocean is rapidly changing with ocean acidification, a result of human activities. In the upper layers of the Southern Ocean, aragonite—a metastable form of calcium carbonate with rapid dissolution kinetics—may become undersaturated by 2050 (ref. 2). Aragonite undersaturation is likely to affect aragonite-shelled organisms, which can dominate surface water communities in polar regions. Here we present analyses of specimens of the pteropod Limacina helicina antarctica that were extracted live from the Southern Ocean early in 2008. We sampled from the top 200m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO2. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94– 1.12 produces equivalent levels of dissolution. As deep-water upwelling and CO2 absorption by surface waters is likely to increase as a result of human activities2,4, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand

Effect of sieving on ex-situ soil respiration of soils from three land use types

This study aims to investigate the effect of sieving on ex situ soil respiration (CO2 flux) measurements from different land use types. We collected soils (0–10 cm) from arable, grassland and woodland sites, allocated them to either sieved (4-mm mesh, freshly sieved) or intact core treatments and incubated them in gas-tight jars for 40 days at 10 °C. Headspace gas was collected on days 1, 3, 17, 24, 31 and 38 and CO2 analysed. Our results showed that sieving (4 mm) did not significantly influence soil respiration measurements, probably because micro aggregates (< 0.25 mm) remain intact after sieving. However, soils collected from grassland soil released more CO2 compared with those collected from woodland and arable soils, irrespective of sieving treatments. The higher CO2 from grassland soil compared with woodland and arable soils was attributed to the differences in the water holding capacity and the quantity and stoichiometry of the organic matter between the three soils. We conclude that soils sieved prior to ex situ respiration experiments provide realistic respiration measurements. This finding lends support to soil scientists planning a sampling strategy that better represents the inhomogeneity of field conditions by pooling, homogenising and sieving samples, without fear of obtaining unrepresentative CO2 flux measurements caused by the disruption of soil architecture

The Point of Origin of the Radio Radiation from the Unresolved Cores of Radio-Loud Quasars

Locating the exact point of origin of the core radiation in active galactic nuclei (AGN) would represent important progress in our understanding of physical processes in the central engine of these objects. However, due to our inability to resolve the region containing both the central compact object and the jet base, this has so far been difficult. Here, using an analysis in which the lack of resolution does not play a significant role, we demonstrate that it may be impossible even in most radio loud sources for more than a small percentage of the core radiation at radio wavelengths to come from the jet base. We find for 3C279 that $\sim85$ percent of the core flux at 15 GHz must come from a separate, reasonably stable, region that is not part of the jet base, and that then likely radiates at least quasi-isotropically and is centered on the black hole. The long-term stability of this component also suggests that it may originate in a region that extends over many Schwarzschild radii.Comment: 7 pages with 3 figures, accepted for publication in Astrophysics and Space Scienc

Characterization and calibration of the James Webb space telescope mirror actuators fine stage motion

The James Webb Space Telescope’s (Webb’s) deployable primary and secondary mirrors are actively controlled to achieve and maintain precise optical alignment on-orbit. Each of the 18 primary mirror segment assemblies (PMSAs) and the secondary mirror assembly (SMA) are controlled in six degrees of freedom by using six linear actuators in a hexapod arrangement. In addition, each PMSA contains a seventh actuator that adjusts radius of curvature (RoC). The actuators are of a novel stepper motor-based cryogenic two-stage design that is capable of sub-10 nm motion accuracy over a 20 mm range. The nm-level motion of the 132 actuators were carefully tested and characterized before integration into the mirror assemblies. Using these test results as an initial condition, knowledge of each actuator’s length (and therefore mirror position) has relied on software bookkeeping and configuration control to keep an accurate motor step count from which actuator position can be calculated. These operations have been carefully performed through years of Webb test operations using both ground support actuator control software as well as the flight Mirror Control Software (MCS). While the actuator’s coarse stage length is cross-checked using a linear variable differential transformer (LVDT), no on-board cross-check exists for the nm-level length changes of the actuators’ fine stage. To ensure that the software bookkeeping of motor step count is still accurate after years of testing and to test that the actuator position knowledge was properly handed off from the ground software to the flight MCS, a series of optical tests were devised and performed through the Center of Curvature (CoC) ambient optical test campaigns at the Goddard Space Flight Center (GSFC) and during the thermal-vacuum tests of the entire optical payload that were conducted in Chamber A at Johnson Space Center (JSC). In each test, the actuator Fine Step Count (FSC) value is compared to an external measurement provided by an optical metrology tool with the goal of either confirming the MCS database value, or providing a recommendation for an updated calibration if the measured FSC differs significantly from the MCS-based expectation. During ambient testing of the PMSA hexapods, the nm-level actuator length changes were measured with a custom laser deflectometer by measuring tilts of the PMSA. The PMSA RoC fine stage characterization was performed at JSC using multi-wave interferometric measurements with the CoC Optical Assembly (COCOA). Finally, the SMA hexapod fine stage characterization test was performed at JSC using the NIRCam instrument in the “pass-and-a-half” test configuration using a test source from the Aft-Optics System Source Plate Assembly (ASPA). In this paper, each of these three tests, subsequent data analyses, and uncertainty estimations will be presented. Additionally, a summary of the ensemble state of Webb’s actuator fine stages is provided, along with a comparison to a Wavefront Sensing and Control (WFSC)-based requirement for FSC errors as they relate to the optical alignment convergence of the telescope on-orbit