33 research outputs found

    Combined potential and spin impurity scattering in cuprates

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    We present a theory of combined nonmagnetic and magnetic impurity scattering in anisotropic superconductors accounting for the momentum-dependent impurity potential. Applying the model to the d-wave superconducting state, we obtain a quantitative agreement with the initial suppression of the critical temperature due to Zn and Ni substitutions as well as electron irradiation defects in the cuprates. We suggest, that the unequal pair-breaking effect of Zn and Ni may be related to a different nature of the magnetic moments induced by these impurities.Comment: 5 pages, 3 tables, RevTex, to be published in Phys. Rev.

    Investigation of the influence of high humidity and exposure duration on the measurement results of radon concentration by means of PicoRad system in the CLOR calibration chamber

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    PicoRad system based on activated charcoal collectors and liquid scintillation counter is one of the most popular passive methods of radon measurements which may be used both indoors and in other environments such as caves, tunnels, mines etc. It is well known that charcoal is also a very good adsorber of water vapor and it can reduce adsorption efficiency for radon. In PicoRad collectors, the charcoal is mixed with a dessicant to lower this effect. A series of expositions of PicoRad detectors was performed in a Central Laboratory for Radiological Protection (CLOR) radon calibration/climatic chamber to study the effect of high relative humidity on the airborne radon concentration measurements and the dependence of the results on the duration of exposure. The results obtained from the PicoRad system were referred to the mean concentrations delivered by an AlphaGUARD monitor, Genitron (GmbH), Germany. The main conclusions are the following: 1) the PicoRad system results are not affected by high relative humidity, including extreme values of 90-96%, for the duration of exposure up to ca. 24 h; 2) in the relative humidity range of 75-96% the correction coefficient linearly depends on the duration of exposure reaching a value of ca. 16 for 96 h exposure; 3) the PicoRad system delivers results corresponding better to the mean value of radon concentration in the last 6 h interval of exposure than that in the whole exposure duration. This finding is particularly important for the calibration of PicoRad collectors in the conditions of decreasing radon concentration due to radon decay

    stawarz.p65

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    Abstract PicoRad system based on activated charcoal collectors and liquid scintillation counter is one of the most popular passive methods of radon measurements which may be used both indoors and in other environments such as caves, tunnels, mines etc. It is well known that charcoal is also a very good adsorber of water vapor and it can reduce adsorption efficiency for radon. In PicoRad collectors, the charcoal is mixed with a dessicant to lower this effect. A series of expositions of PicoRad detectors was performed in a Central Laboratory for Radiological Protection (CLOR) radon calibration/climatic chamber to study the effect of high relative humidity on the airborne radon concentration measurements and the dependence of the results on the duration of exposure. The results obtained from the PicoRad system were referred to the mean concentrations delivered by an AlphaGUARD monitor, Genitron (GmbH), Germany. The main conclusions are the following: 1) the PicoRad system results are not affected by high relative humidity, including extreme values of 90−96%, for the duration of exposure up to ca. 24 h; 2) in the relative humidity range of 75−96% the correction coefficient linearly depends on the duration of exposure reaching a value of ca. 16 for 96 h exposure; 3) the PicoRad system delivers results corresponding better to the mean value of radon concentration in the last 6 h interval of exposure than that in the whole exposure duration. This finding is particularly important for the calibration of PicoRad collectors in the conditions of decreasing radon concentration due to radon decay

    Intercomparison of radon CR-39 detector systems conducted in CLOR's calibration chamber

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    Six radon laboratories, which perform indoor radon measurements to jointly investigate temporal variations of radon concentration in houses in a couple of regions in Poland, participated in the intercomparison exercise. There are involved three commercially available Hungarian RadoSys systems and four own laboratory methods. All of them are based on the etched-track CR-39 detectors. The intercomparison was conducted in a calibration laboratory of the Central Laboratory for Radiological Protection (CLOR), Warsaw, Poland, accredited by the Polish Center for Accreditation (previously AP 101, at present AP 057). Comparison measurements were performed during three expositions in the CLOR’s radon calibration chamber under controlled normal climatic conditions and steady radon concentration. The results were referred to the value of the radon concentration determined by AlphaGUARD monitor traceable to the primary 222Rn standard in Physikalisch-Technische Bundesanstalt (PTB), Braunchweig, Germany. The mean performance ratio defined as a ratio of the reference to participant’s result range from 0.88 to 1.31

    The European Modern Pollen Database (EMPD) project

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    Modern pollen samples provide an invaluable research tool for helping to interpret the quaternary fossil pollen record, allowing investigation of the relationship between pollen as the proxy and the environmental parameters such as vegetation, land-use, and climate that the pollen proxy represents. The European Modern Pollen Database (EMPD) is a new initiative within the European Pollen Database (EPD) to establish a publicly accessible repository of modern (surface sample) pollen data. This new database will complement the EPD, which at present holds only fossil sedimentary pollen data. The EMPD is freely available online to the scientific community and currently has information on almost 5,000 pollen samples from throughout the Euro-Siberian and Mediterranean regions, contributed by over 40 individuals and research groups. Here we describe how the EMPD was constructed, the various tables and their fields, problems and errors, quality controls, and continuing efforts to improve the available data

    Possibility of inclusion of the Sobibór Forests into Importand Birds Areas and Special Protection Areas networks

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    One of the greatest challenges of nature conservation is to identify and locate networks of protected areas, which will preserve the biodiversity. The paper aims to show the ornithological value of the Sobibór Forests (E Poland) and to emphasize the fact that the network of Important Bird Areas (IBA) and Special Protection Areas within Natura 2000 (SPA) may require additions. The study was conducted in the period of 2008−2016, mainly on forested areas occupying 256 km2. The Sobibór Forests are characterized by a large diversity of habitats, but are mainly covered by Scots pine Pinus sylvestris. High diversity of wetlands and marshlands make the Sobibór Forest unique within the country. Three methodologies were used to estimate population size of chosen species: sampling, census and random observations. 31 species from Annex I of the Birds Directive plus 25 species of SPEC or non−SPECE category were observed which allows to consider this area as one of the most valuable for avifauna in Poland. Six breeding species classify the Sobibór Forests as the IBA and SPA. These species include Black Stork Ciconia nigra (8−13 breeding pairs), Common Crane Grus grus (80−120 breeding pairs), Grey Great Owl Strix nebulosa (0−7 breeding pairs i.e. 50−100% of Polish breeding population), Eagle Owl Bubo bubo (6 breeding pairs), White−backed Woodpecker Dendrocopos leucotos (40−70 breeding pairs) and Grey−headed Woodpecker Picus canus (20−40 breeding pairs). Six other species show potential for qualification, but not enough data has been collected yet. The list of this specie includes: Short−toed Snake Eagle Circaetus gallicus, Common Snipe Gallinago gallinago, Stock Dove Columba oenas, European Nightjar Caprimulgus europaeus, Collared Flycatcher Ficedula albicollis and Bluethroat Luscinia svecica. The Sobibór Forests occupy a small area compared to other IBA forests. However, the number of breeding species classifies the surveyed area as 7th among other IBAs. Moreover all eligible species may be considered as a bioindicators of the natural state of the forest. This is proof of the high natural value of this area

    City festivals: creativity and control in staged urban experiences

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    In a global market, cities aim to develop a distinct profile to attract mobile consumers. One means increasingly used to attain distinction is to brand the city as experience space. In particular, the urban festival has become a popular organizational form for creating experience spaces and for marketing cities. Festivals are often strategically conceived with the purpose of promoting a ?distinctive city?, in line with uniqueness being the keystone of success in the experience economy. This paper applies an experience economy framework to analyse city festivals as potentially transformative practices, helping re-imagine urban space and reshape urban identity. Building on empirical studies of the Stockholm Culture Festival and the Nowy Kercelak Fair in Warsaw, it examines the tension between controlled image production and carnivalesque celebration and the extent to which the meanings and flow of urban space can be managed. Using Lef�bvre?s notion of the production of space and Deleuze and Guattari?s concepts of de-territorialization and re-territorialization, this paper critically assesses the possibility of reshaping urban practices through the staging of festivals, and the potential for creativity and expression extant in managed staging of experience
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