Potential routes of exposure as a foundation for a risk assessment scheme: a Conceptual Model

Background: The global interest in improving the regulatory risk assessment of pesticides in honeybees and other pollinator insects has led to new test requirements and a conceptual model has been published in the US. It is of interest for modellers and risk assessors to have a more detailed conceptual model that describes the movement of deleterious substances from the point of initial exposure to the point of impact on the protection goals, such as colony health, or honey production. Results: The flow of pesticide residues from application to distribution in the hive is described in an integrated conceptual model. The significance of this model for assessing the relative contribution of various potential routes of exposure, guiding test requirements and describing the quantitative distribution of residues among the castes and task groups of honeybees in the colony was described using data from studies with chlorpyrifos and several neonicotinoids. Conclusion: The quantitative pollinator conceptual model (QPCM) describes the flow pathways and potential exposure routes for honeybees and other bee pollinators in sufficient detail to support quantitative exposure modelling and risk assessment and shows the importance of measuring the distribution of pesticide residues in the areas that lead to exposure and in the hive

Monitoring in-hive residues of neonicotinoids in relation to bee health status

A field study was done to search for residues of neonicotinoids in twelve honeybee hives in four apiaries in the corn and soybean growing area of southern Ontario, in Canada, and to determine if any bee loss or symptoms of stress were associated with such residues. Dead bees in front of the hive, and live forager bees at the hive entrance and inside the hive were collected. Pollen, honey and nectar were also sampled. Acetamiprid, clothianidin and thiamethoxam and the metabolite TZNG were included in the analysis, and extensive diagnostic tests were done to monitor mites and diseases. Clothianidin, thiamethoxam and TZNG were found in dead bees collected in front of the hives and forager bees from the hive entrance but not in bees from inside the hive. The concentrations found in bees and hive products were below the NOELs for bees, and were not associated with any evidence of stress or bee loss. Mite levels were low, but viruses were frequently found. The pattern of distribution of residues was parallel to what has been reported for other chemicals including chlorpyrifos. Implications of this pattern for the role of the eusocial behaviour of bees in allowing a bee colony to forage on plants bearing natural or xenobiotic toxins are discussed.Keywords: honeybee, colony loss, virus, neonicotinoid, resistanc

The virtual haptic back: A simulation for training in palpatory diagnosis

<p>Abstract</p> <p>Background</p> <p>Models and simulations are finding increased roles in medical education. The Virtual Haptic Back (VHB) is a virtual reality simulation of the mechanical properties of the human back designed as an aid to teaching clinical palpatory diagnosis.</p> <p>Methods</p> <p>Eighty-nine first year medical students of the Ohio University College of Osteopathic Medicine carried out six, 15-minute practice sessions with the VHB, plus tests before and after the sessions in order to monitor progress in identifying regions of simulated abnormal tissue compliance. Students palpated with two digits, fingers or thumbs, by placing them in gimbaled thimbles at the ends of PHANToM 3.0^®haptic interface arms. The interface simulated the contours and compliance of the back surface by the action of electric motors. The motors limited the compression of the virtual tissues induced by the palpating fingers, by generating counterforces. Users could see the position of their fingers with respect to the back on a video monitor just behind the plane of the haptic back. The abnormal region varied randomly among 12 locations between trials. During the practice sessions student users received immediate feedback following each trial, indicating either a correct choice or the actual location of the abnormality if an incorrect choice had been made. This allowed the user to feel the actual abnormality before going on to the next trial. Changes in accuracy, speed and Weber fraction across practice sessions were analyzed using a repeated measures analysis of variance.</p> <p>Results</p> <p>Students improved in accuracy and speed of diagnosis with practice. The smallest difference in simulated tissue compliance users were able to detect improved from 28% (SD = 9.5%) to 14% (SD = 4.4%) during the practice sessions while average detection time decreased from 39 (SD = 19.8) to 17 (SD = 11.7) seconds. When asked in anonymous evaluation questionnaires if they judged the VHB practice to be helpful to them in the clinical palpation and manual medicine laboratory, 41% said yes, 51% said maybe, and 8% said no.</p> <p>Conclusion</p> <p>The VHB has potential value as a teaching aid for students in the initial phases of learning palpatory diagnosis.</p

The Underestimation Of Egocentric Distance: Evidence From Frontal Matching Tasks

There is controversy over the existence, nature, and cause of error in egocentric distance judgments. One proposal is that the systematic biases often found in explicit judgments of egocentric distance along the ground may be related to recently observed biases in the perceived declination of gaze (Durgin & Li, Attention, Perception, & Psychophysics, in press), To measure perceived egocentric distance nonverbally, observers in a field were asked to position themselves so that their distance from one of two experimenters was equal to the frontal distance between the experimenters. Observers placed themselves too far away, consistent with egocentric distance underestimation. A similar experiment was conducted with vertical frontal extents. Both experiments were replicated in panoramic virtual reality. Perceived egocentric distance was quantitatively consistent with angular bias in perceived gaze declination (1.5 gain). Finally, an exocentric distance-matching task was contrasted with a variant of the egocentric matching task. The egocentric matching data approximate a constant compression of perceived egocentric distance with a power function exponent of nearly 1; exocentric matches had an exponent of about 0.67. The divergent pattern between egocentric and exocentric matches suggests that they depend on different visual cues

1971

Shop Talk by Frank Santos (page 1) You\u27ve Come a Long Way, Lawn-Mower Pusher by Alan B. Albin (2) In The Eyes of the Laymen by Eugene P. Elcik (2) The Importance of Water Management by Fred V. Grau (A-1) Automatic Irrigation Systems Integrated with Pumping Systems by Michael O. Mattwell (A-5) Installation of a Complete Water Source and Automatic System by Richard C. Blake (A-19) How the Soil Conservation Service Can Help in Golf Course Management by Christopher G. Mousitakis (A-22) Our Shrinking Environment by Haim B. Gunner (A-24) Pesticides\u27 Dilemma - Emotion vs. Science by Allen H. Morgan (A-28) Effects of Turf Grasses and Trees in Neutralizing Waste Water by William E. Sopper (A-34) Unsolved and New Problems Developing in Golf Course Management by Alexander M. Radko (A-44) Coming of the Conglomerate Director of Golf Courses by Edmund B. Ault (A-48) Aquatic Weed Control by John E. Gallagher (A-52) What Project Apollo Has Done for Golf and Golf Course Architecture by Mal Purdy (A-54) Maintenance of Grass Tennis Courts by Wayne Zoppo (A-59) Diseases of Ornametnals Growing in Turf Areas by R.E. Partyka (A-62) Control of Turf Insects by John C. Schread (A-65) Lime for Turf by Henry W. Indyk (A-68) How to Stop Guessing When You Buy Seed by Dale Kern (A-71) Broad Aspects of Turf Grass Culture Other Than Golf Courses by Geoffrey S. Cornish (A-79) Establishing and Maintaining Turf int he national Capitol Parks by Alton E. Rabbitt (A-81) Preventive Maintenance on Small One Cylinder Air Cooled Engine by F. W. Hazle (A-85) Top Fairway Mower Performance by James R. Maloney (A-95) Grinding Reel Type Mowers by Ray Christopherson (A-99

Upper crustal evolution across the Juan de Fuca ridge flanks

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q09006, doi:10.1029/2008GC002085.Recent P wave velocity compilations of the oceanic crust indicate that the velocity of the uppermost layer 2A doubles or reaches ∼4.3 km/s found in mature crust in <10 Ma after crustal formation. This velocity change is commonly attributed to precipitation of low-temperature alteration minerals within the extrusive rocks associated with ridge-flank hydrothermal circulation. Sediment blanketing, acting as a thermal insulator, has been proposed to further accelerate layer 2A evolution by enhancing mineral precipitation. We carried out 1-D traveltime modeling on common midpoint supergathers from our 2002 Juan de Fuca ridge multichannel seismic data to determine upper crustal structure at ∼3 km intervals along 300 km long transects crossing the Endeavor, Northern Symmetric, and Cleft ridge segments. Our results show a regional correlation between upper crustal velocity and crustal age. The measured velocity increase with crustal age is not uniform across the investigated ridge flanks. For the ridge flanks blanketed with a sealing sedimentary cover, the velocity increase is double that observed on the sparsely and discontinuously sedimented flanks (∼60% increase versus ∼28%) over the same crustal age range of 5–9 Ma. Extrapolation of velocity-age gradients indicates that layer 2A velocity reaches 4.3 km/s by ∼8 Ma on the sediment blanketed flanks compared to ∼16 Ma on the flanks with thin and discontinuous sediment cover. The computed thickness gradients show that layer 2A does not thin and disappear in the Juan de Fuca region with increasing crustal age or sediment blanketing but persists as a relatively low seismic velocity layer capping the deeper oceanic crust. However, layer 2A on the fully sedimented ridge-flank sections is on average thinner than on the sparsely and discontinuously sedimented flanks (330 ± 80 versus 430 ± 80 m). The change in thickness occurs over a 10–20 km distance coincident with the onset of sediment burial. Our results also suggest that propagator wakes can have atypical layer 2A thickness and velocity. Impact of propagator wakes is evident in the chemical signature of the fluids sampled by ODP drill holes along the east Endeavor transect, providing further indication that these crustal discontinuities may be sites of localized fluid flow and alteration.This research was supported by National Science Foundation grants OCE-00-02488, OCE-00-02551, and OCE-00- 02600

An Integrated-Photonics Optical-Frequency Synthesizer

Integrated-photonics microchips now enable a range of advanced functionalities for high-coherence applications such as data transmission, highly optimized physical sensors, and harnessing quantum states, but with cost, efficiency, and portability much beyond tabletop experiments. Through high-volume semiconductor processing built around advanced materials there exists an opportunity for integrated devices to impact applications cutting across disciplines of basic science and technology. Here we show how to synthesize the absolute frequency of a lightwave signal, using integrated photonics to implement lasers, system interconnects, and nonlinear frequency comb generation. The laser frequency output of our synthesizer is programmed by a microwave clock across 4 THz near 1550 nm with 1 Hz resolution and traceability to the SI second. This is accomplished with a heterogeneously integrated III/V-Si tunable laser, which is guided by dual dissipative-Kerr-soliton frequency combs fabricated on silicon chips. Through out-of-loop measurements of the phase-coherent, microwave-to-optical link, we verify that the fractional-frequency instability of the integrated photonics synthesizer matches the $7.0*10^{-13}$ reference-clock instability for a 1 second acquisition, and constrain any synthesis error to $7.7*10^{-15}$ while stepping the synthesizer across the telecommunication C band. Any application of an optical frequency source would be enabled by the precision optical synthesis presented here. Building on the ubiquitous capability in the microwave domain, our results demonstrate a first path to synthesis with integrated photonics, leveraging low-cost, low-power, and compact features that will be critical for its widespread use.Comment: 10 pages, 6 figure

Upper crustal structure and axial topography at intermediate spreading ridges : seismic constraints from the southern Juan de Fuca Ridge

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): B12104, doi:10.1029/2005JB003630.We use multichannel seismic reflection data to image the upper crustal structure of 0-620 ka crust along the southern Juan de Fuca Ridge (JdFR). The study area comprises two segments spreading at intermediate rate with an axial high morphology with narrow (Cleft) and wide (Vance) axial summit grabens (ASG). Along most of the axis of both segments we image the top of an axial magma chamber (AMC). The AMC along Cleft deepens from south to north, from 2.0 km beneath the RIDGE Cleft Observatory and hydrothermal vents near the southern end of the segment, to 2.3 km at the northern end near the site of the 1980’s eruptive event. Along the Vance segment, the AMC also deepens from south to north, from 2.4 km to 2.7 km. Seismic layer 2A, interpreted as the basaltic extrusive layer, is 250-300 m thick at the ridge axis along the Cleft segment, and 300-350 m thick along the axis of the Vance segment. However off-axis layer 2A is similar in both segments (500-600 m), indicating ~90% and ~60% off-axis thickening at the Cleft and Vance segments, respectively. Half of the thickening occurs sharply at the walls of the ASG, with the remaining thickening occurring within 3-4 km of the ASG. Along the full length of both segments, layer 2A is thinner within the ASG, compared to the ridge flanks. Previous studies argued that the ASG is a cyclic feature formed by alternating periods of magmatism and tectonic extension. Our observations agree with the evolving nature of the ASG. However, we suggest that its evolution is related to large changes in axial morphology produced by small fluctuations in magma supply. Thus the ASG, rather than being formed by excess volcanism, is a rifted flexural axial high. The changes in axial morphology affect the distribution of lava flows along the ridge flanks, as indicated by the pattern of layer 2A thickness. The fluctuations in magma supply may occur at all spreading rates, but its effects on crustal structure and axial morphology are most pronounced along intermediate spreading rate ridges.This study was supported by the National Science Foundation grants OCE-0002551 to Woods Hole Oceanographic Institution, OCE-0002488 to Lamont-Doherty Earth Observatory, and OCE-0002600 to Scripps Institution of Oceanography