1,591 research outputs found

    Re International Association of Machinists, Lodge 717, and Orenda Ltd

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    Employee Grievance alleging failure by the company to provide weekly indemnity for non-occupational sickness. The facts: On June 19, 1968, Mr. Garden, the grievor, went to Orenda\u27s plant doctor for an examination. He was referred to his family doctor. That same day, and again on June 24th, he consulted Dr. W.K. Taylor who had been his doctor for some years. On June 25th, Dr. Taylor signed an Attending Physician\u27s Statement for submission to the company in support of a claim by the grievor for weekly indemnity for non-occupational sickness. The statement noted under the heading diagnosis the following: neurodermatitis both hands, duodenal ulcer symptoms . It is also noted on the statement that the patient has been totally disabled (unable to work) from June 19, 1968, and that he should be able to return to work on July 2, 1968. Under the heading how long will the patient be partially disabled? the answer given is for the same period

    Clouds, photolysis and regional tropospheric ozone budgets.

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    We use a three-dimensional chemical transport model to examine the shortwave radiative effects of clouds on the tropospheric ozone budget. In addition to looking at changes in global concentrations as previous studies have done, we examine changes in ozone chemical production and loss caused by clouds and how these vary in different parts of the troposphere. On a global scale, we find that clouds have a modest effect on ozone chemistry, but on a regional scale their role is much more significant, with the size of the response dependent on the region. The largest averaged changes in chemical budgets (±10–14%) are found in the marine troposphere, where cloud optical depths are high. We demonstrate that cloud effects are small on average in the middle troposphere because this is a transition region between reduction and enhancement in photolysis rates. We show that increases in boundary layer ozone due to clouds are driven by large-scale changes in downward ozone transport from higher in the troposphere rather than by decreases in in-situ ozone chemical loss rates. Increases in upper tropospheric ozone are caused by higher production rates due to backscattering of radiation and consequent increases in photolysis rates, mainly J(NO2). The global radiative effect of clouds on isoprene, through decreases of OH in the lower troposphere, is stronger than on ozone. Tropospheric isoprene lifetime increases by 7% when taking clouds into account. We compare the importance of clouds in contributing to uncertainties in the global ozone budget with the role of other radiatively-important factors. The budget is most sensitive to the overhead ozone column, while surface albedo and clouds have smaller effects. However, uncertainty in representing the spatial distribution of clouds may lead to a large sensitivity of the ozone budget components on regional scales

    Interannual variability of tropospheric composition:the influence of changes in emissions, meteorology and clouds

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    We have run a chemistry transport model (CTM) to systematically examine the drivers of interannual variability of tropospheric composition during 1996-2000. This period was characterised by anomalous meteorological conditions associated with the strong El Nino of 1997-1998 and intense wildfires, which produced a large amount of pollution. On a global scale, changing meteorology (winds, temperatures, humidity and clouds) is found to be the most important factor driving interannual variability of NO2 and ozone on the timescales considered. Changes in stratosphere-troposphere exchange, which are largely driven by meteorological variability, are found to play a particularly important role in driving ozone changes. The strong influence of emissions on NO2 and ozone interannual variability is largely confined to areas where intense biomass burning events occur. For CO, interannual variability is almost solely driven by emission changes, while for OH meteorology dominates, with the radiative influence of clouds being a very strong contributor. Through a simple attribution analysis for 1996-2000 we conclude that changing cloudiness drives 25% of the interannual variability of OH over Europe by affecting shortwave radiation. Over Indonesia this figure is as high as 71%. Changes in cloudiness contribute a small but non-negligible amount (up to 6%) to the interannual variability of ozone over Europe and Indonesia. This suggests that future assessments of trends in tropospheric oxidizing capacity should account for interannual variability in cloudiness, a factor neglected in many previous studies

    VOLCANIC HAZARD ASSESSMENT AT SANTORINI VOLCANO: A REVIEW AND A SYNTHESIS IN THE LIGHT OF THE 2011-2012 SANTORINI UNREST

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    Το 2011 και το πρώτο εξάμηνο του 2012 η Σαντορίνη γνώρισε την πρώτη σεισμο-ηφαιστειακή κρίση από το 1950, όπως αυτή ανιχνεύθηκε από τα μόνιμα εγκατεστημένα δίκτυα παρακολούθησης και ένα μεγάλο αριθμό παροδικών μετρήσεων. Η διέγερση αυτή χαρακτηρίστηκε από μικρού μεγέθους, αλλά έντονη σεισμική δραστηριότητα, σημαντική ανύψωση και διόγκωση του νησιού, αλλαγές της θερμοκρασίας του νερού και των γεωχημικών αερίων. Ενώ η διέγερση έληξε την άνοιξη του 2012, το παγκόσμιο ενδιαφέρον οδήγησε στην εκπόνηση αρκετών μελετών, σε μια προσπάθεια να αξιολογηθούν τα πιθανά σενάρια για την εξέλιξη της διέγερσης. Στο πλαίσιο αυτό, συνοψίζουμε τα σημαντικότερα ευρήματα σχετικά με την επικινδυνότητα του ευρύτερου ηφαιστειακού συγκροτήματος της Σαντορίνης, καθώς και τις πληροφορίες που πρέπει να ληφθούν υπόψη για τη διαχείριση μιας πιθανής μελλοντικής ηφαιστειακής κρίσης.In 2011 and the first half of 2012 Santorini experienced its first seismo-volcanic unrest since 1950, as detected by the permanently installed monitoring networks and a large number of campaign measurements. The unrest was characterized by small magnitude but intense seismic activity, significant uplift and inflation deformation rates, and changes of water temperature as well as of fluid and soil gases. While the unrest ended in the spring of 2012, the world-wide interest led to the performance of several studies, in an attempt to assess the possible scenarios for the unrest evolution. Within this framework, we summarize the most important findings regarding the volcanic hazard assessment of the broader Santorini volcanic complex, as well as the constraints that need to be taken into account for a possible future volcanic crisis management

    Ozone loss derived from balloon-borne tracer measurements in the 1999/2000 Arctic winter

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    Balloon-borne measurements of CFC11 (from the DIRAC in situ gas chromatograph and the DESCARTES grab sampler), ClO and O3 were made during the 1999/2000 Arctic winter as part of the SOLVE-THESEO 2000 campaign, based in Kiruna (Sweden). Here we present the CFC11 data from nine flights and compare them first with data from other instruments which flew during the campaign and then with the vertical distributions calculated by the SLIMCAT 3D CTM. We calculate ozone loss inside the Arctic vortex between late January and early March using the relation between CFC11 and O3 measured on the flights. The peak ozone loss (~1200ppbv) occurs in the 440-470K region in early March in reasonable agreement with other published empirical estimates. There is also a good agreement between ozone losses derived from three balloon tracer data sets used here. The magnitude and vertical distribution of the loss derived from the measurements is in good agreement with the loss calculated from SLIMCAT over Kiruna for the same days

    Do sophisticated evolutionary algorithms perform better than simple ones?

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    Evolutionary algorithms (EAs) come in all shapes and sizes. Theoretical investigations focus on simple, bare-bones EAs while applications often use more sophisticated EAs that perform well on the problem at hand. What is often unclear is whether a large degree of algorithm sophistication is necessary, and if so, how much performance is gained by adding complexity to an EA. We address this question by comparing the performance of a wide range of theory-driven EAs, from bare-bones algorithms like the (1+1) EA, a (2+1) GA and simple population-based algorithms to more sophisticated ones like the (1+(λ,λ)) GA and algorithms using fast (heavy-tailed) mutation operators, against sophisticated and highly effective EAs from specific applications. This includes a famous and highly cited Genetic Algorithm for the Multidimensional Knapsack Problem and the Parameterless Population Pyramid for Ising Spin Glasses and MaxSat. While for the Multidimensional Knapsack Problem the sophisticated algorithm performs best, surprisingly, for large Ising and MaxSat instances the simplest algorithm performs best. We also derive conclusions about the usefulness of populations, crossover and fast mutation operators. Empirical results are supported by statistical tests and contrasted against theoretical work in an attempt to link theoretical and empirical results on EAs

    Investigation of Arctic ozone depletion sampled over midlatitudes during the Egrett campaign of spring/summer 2000

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    International audienceA unique halocarbon dataset has been obtained using the Australian high altitude research aircraft, the Grob G520T Egrett, during May-June 2000 with GC instrument (DIRAC), which has been previously deployed on balloon platforms. The halocarbon data generally shows a good anticorrelation with ozone data obtained simultaneously from commercial sensors. On 5 June 2000, at 380K, the Egrett entered a high latitude tongue of air over the U.K. CFC-11 and O3 data obtained on the flight show evidence of this feature. The dataset has been used, in conjunction with a 3D chemical transport model, to infer ozone depletion encountered in the midlatitude lower stratosphere during the flight. We calculate that ozone is depleted by 20% relative to its winter value in the higher latitude airmass. A suite of ozone loss tracers in the model have been used to track ozone depletion according to location relative to the vortex and chemical cycle responsible. The model, initialised on 9 December, indicates that 50% of the total chemical ozone destruction encountered in June in the middle latitudes occurred in the 90-70°N equivalent latitude band and that 70% was due to halogen chemistry

    Evolution of breeding plumages in birds: A multiple-step pathway to seasonal dichromatism in New World warblers (Aves: Parulidae)

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    Ecology and Evolution published by John Wiley & Sons Ltd Many species of birds show distinctive seasonal breeding and nonbreeding plumages. A number of hypotheses have been proposed for the evolution of this seasonal dichromatism, specifically related to the idea that birds may experience variable levels of sexual selection relative to natural selection throughout the year. However, these hypotheses have not addressed the selective forces that have shaped molt, the underlying mechanism of plumage change. Here, we examined relationships between life-history variation, the evolution of a seasonal molt, and seasonal plumage dichromatism in the New World warblers (Aves: Parulidae), a family with a remarkable diversity of plumage, molt, and life-history strategies. We used phylogenetic comparative methods and path analysis to understand how and why distinctive breeding and nonbreeding plumages evolve in this family. We found that color change alone poorly explains the evolution of patterns of biannual molt evolution in warblers. Instead, molt evolution is better explained by a combination of other life-history factors, especially migration distance and foraging stratum. We found that the evolution of biannual molt and seasonal dichromatism is decoupled, with a biannual molt appearing earlier on the tree, more dispersed across taxa and body regions, and correlating with separate life-history factors than seasonal dichromatism. This result helps explain the apparent paradox of birds that molt biannually but show breeding plumages that are identical to the nonbreeding plumage. We find support for a two-step process for the evolution of distinctive breeding and nonbreeding plumages: That prealternate molt evolves primarily under selection for feather renewal, with seasonal color change sometimes following later. These results reveal how life-history strategies and a birds\u27 environment act upon multiple and separate feather functions to drive the evolution of feather replacement patterns and bird coloration
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