Mostrando recursos 1 - 20 de 14.207

  1. The act of documenting: documentary film in the 21st century

    Winston, Brian; Vanstone, Gail; Chi, Wang
    Documentary has never attracted such audiences, never been produced with such ease from so many corners of the globe, never embraced such variety of expression. The very distinctions between the filmed, the filmer and the spectator are being dissolved. The Act of Documenting addresses what this means for documentary's 21st century position as a genus in the “class” cinema; for its foundations as, primarily, a scientistic, eurocentric and patriarchal discourse; for its future in a world where assumptions of photographic image integrity cannot be sustained. Unpacked are distinctions between performance and performativy and between different levels of interaction, linearity and...

  2. ‘Passion Impossible’ or man with a mission: a Goffmanesque intervention

    Scheer, Anna
    This chapter examines Schlingensief’s temporal, creative intervention into the experiences of an underprivileged section of Hamburg’s urban population, whose destitute circumstances he viewed as a social ‘staging’ or production. The meeting point for this marginalized group, located across the road from a major theatre at Hamburg’s main station led Schlingensief to confront and challenge the theatre’s lack of engagement with the pressing social issues literally found on its doorstep. Schlingensief identified the theatre – to which he had been invited – as a site of social exclusion and rejected it as a venue in which to rehearse and premiere a...

  3. Ecosystem change and stability over multiple decades in the Swedish subarctic: complex processes and multiple drivers

    Callaghan, Terry V.; Jonasson, Christer; Thierfelder, Tomas; Yang, Zhenlin; Hedenås, Henrik; Johansson, Margareta; Molau, Ulf; van Bogaert, Rik; Michelsen, Anders; Olofsson, Johan; Gwynn-Jones, Dylan; Bokhorst, Stef; Phoenix, Gareth; Bjerke, Jarle W.; Tømmervik, Hans; Christensen, Torben R.; Hanna, Edward; Koller, Eva K.; Sloan, Victoria L.
    The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in...

  4. Examination of a physically based, high-resolution, distributed Arctic temperature-index melt model, on Midtre Lovénbreen, Svalbard

    Irvine-Fynn, T. D. L.; Hanna, Edward; Barrand, N. E.; Porter, P. R.; Kohler, J.; Hodson, A. J.
    Improvements in our ability to model runoff from glaciers remain an important scientific goal. This paper describes a new temperature-radiation-index glacier melt model specifically enhanced for use in High-Arctic environments, utilising high temporal and spatial resolution datasets while retaining relatively modest data requirements. The model employs several physically constrained parameters and was tuned using a lidar-derived surface elevation model of Midtre Lovénbreen, meteorological data from sites spanning ~70 of the glacier's area-altitude distribution and periodic ablation surveys during the 2005 melt season. The model explained 80 of the variance in observed ablation across the glacier, an improvement of ~40 on...

  5. Synoptic climatology of cold air drainage in the Derwent Valley, Peak District, UK

    Bigg, Grant R.; Wise, Stephen M.; Hanna, Edward; Mansell, Damien; Bryant, Robert G.; Howard, Alick
    Cold air drainage is a characteristic of hilly or mountainous terrain and can have significant impact on agricultural or horticultural activities. This paper considers a range of synoptic and topographic factors that could affect the phenomenon of cold air drainage, through an exploration of its characteristics in the Peak District of central England, showing that cold air drainage events can occur at any time of the year, with summer events being even more frequent than those usually noticed in winter. The occurrence of such events is related to the local topography, and particularly the correspondence to hollows and local valleys...

  6. Incorporating topographic indices into dynamic ecosystem modelling using LPJ-GUESS

    Tang, Jing; Pilesjo, Petter; Miller, Paul A.; Persson, Andreas; Yang, Zhenlin; Hanna, Edward; Callaghan, Terry V.
    Northern high-latitude regions could feed back strongly on global warming because of large carbon pools and the fact that those regions are predicted to experience temperature increases greater than the global average. Furthermore, ecological functioning and carbon cycling are both strongly related to the prevailing hydrological conditions. In this study, we address these issues and present a newly developed model LPJ distributed hydrology (LPJ-DH) with distributed hydrology based on the dynamic global ecosystem and biogeochemistry model LPJ-GUESS. The new model is an enhanced version of LPJ-GUESS, introducing parametrizations of surface water routing and lateral water fluxes between grid cells. The...

  7. Atmospheric and oceanic influence on mass balance of northern North Atlantic region land-terminating glaciers

    Mernild, Sebastian H.; Hanna, Edward; Yde, Jacob C.; Seidenkrantz, Marit-Solveig; Wilson, Ryan; Knudsen, Niels Tvis
    In this study, observed annual mass-balance data series from 1970 to 2009 for 29 land-terminating glaciers and ice caps in the northern North Atlantic region are presented to highlight their spatio-temporal variability. The glaciers and ice caps mass-balance data are compared with various zonal latitude bands of regional near-surface air temperature time series, large-scale atmospheric and oceanic circulation indices, as well as with North Icelandic sea-surface temperature records, since variations in mass-balance conditions are related both to variations in surface weather conditions and to atmospheric and oceanic circulations. The purpose is to explore statistical and physical relations based on the...

  8. Correlation of oscillatory behaviour in Matlab using wavelets

    Pering, T. D.; Tamburello, G.; McGonigle, A .J. S.; Hanna, Edward; Aiuppa, A.
    Here we present a novel computational signal processing approach for comparing two signals of equal length and sampling rate, suitable for application across widely varying areas within the geosciences. By performing a continuous wavelet transform (CWT) followed by Spearman's rank correlation coefficient analysis, a graphical depiction of links between periodicities present in the two signals is generated via two or three dimensional images. In comparison with alternate approaches, e.g., wavelet coherence, this technique is simpler to implement and provides far clearer visual identification of the inter-series relationships. In particular, we report on a Matlab® code which executes this technique, and...

  9. Learning complex motions by sequencing simpler motion templates

    Neumann, Gerhard; Maass, W.; Peters, J.
    Abstraction of complex, longer motor tasks into simpler elemental movements enables humans and animals to exhibit motor skills which have not yet been matched by robots. Humans intuitively decompose complex motions into smaller, simpler segments. For example when describing simple movements like drawing a triangle with a pen, we can easily name the basic steps of this movement. Surprisingly, such abstractions have rarely been used in artificial motor skill learning algorithms. These algorithms typically choose a new action (such as a torque or a force) at a very fast time-scale. As a result, both policy and temporal credit assignment problem become...

  10. Hierarchical relative entropy policy search

    Daniel, Christian; Neumann, Gerhard; Peters, Jan
    Many real-world problems are inherently hierarchically structured. The use of this structure in an agent’s policy may well be the key to improved scalability and higher performance. However, such hierarchical structures cannot be exploited by current policy search algorithms. We will concentrate on a basic, but highly relevant hierarchy — the ‘mixed option’ policy. Here, a gating network first decides which of the options to execute and, subsequently, the option-policy determines the action. In this paper, we reformulate learning a hierarchical policy as a latent variable estimation problem and subsequently extend the Relative Entropy Policy Search (REPS) to the latent variable case. We show that our Hierarchical REPS can learn versatile solutions while also showing an increased performance in...

  11. Learning multiple collaborative tasks with a mixture of interaction primitives

    Ewerton, Marco; Neumann, Gerhard; Lioutikov, Rudolf; Amor, Heni Ben; Peters, Jan; Maeda, Guilherme
    Robots that interact with humans must learn to not only adapt to different human partners but also to new interactions. Such a form of learning can be achieved by demonstrations and imitation. A recently introduced method to learn interactions from demonstrations is the framework of Interaction Primitives. While this framework is limited to represent and generalize a single interaction pattern, in practice, interactions between a human and a robot can consist of many different patterns. To overcome this limitation this paper proposes a Mixture of Interaction Primitives to learn multiple interaction patterns from unlabeled demonstrations. Specifically the proposed method uses Gaussian Mixture Models of Interaction Primitives to model nonlinear correlations between the movements...

  12. Learning of non-parametric control policies with high-dimensional state features

    Van Hoof, Herke; Peters, Jan; Neumann, Gerhard
    Learning complex control policies from highdimensional sensory input is a challenge for reinforcement learning algorithms. Kernel methods that approximate values functions or transition models can address this problem. Yet, many current approaches rely on instable greedy maximization. In this paper, we develop a policy search algorithm that integrates robust policy updates and kernel embeddings. Our method can learn nonparametric control policies for infinite horizon continuous MDPs with high-dimensional sensory representations. We show that our method outperforms related approaches, and that our algorithm can learn an underpowered swing-up task task directly from highdimensional image data.

  13. De facto protection for academic freedom in the U.K.: empirical evidence in a comparative context

    Karran, Terence; Mallinson, Lucy
    This analysis, which uses similar surveys to gather comparable data from over 2000 UCU members and 5000 staff in universities of the European states, demonstrates that the low level of de jure protection for academic freedom in the UK is mirrored by an equally poor (if not worse) level of de facto protection. The reality is that, in the overwhelming majority of instances, UCU members report statistically significantly higher levels of systematic abuse of their academic freedom, across a wide array of measures, than their European counterparts. For example, 23% of UCU respondents (and 14.1% of EU respondents) reported being...

  14. Solar-driven global warming

    Hanna, Edward
    Some intriguing statistical evidence from readily available data suggests that longer-term (>11-year) solar activity cannot be overlooked as a potential cause of an appreciable part of twentieth-century global warming, and might in particular explain the latter's hiatus or even slight reversal between 1940-70. On this basis, global warming is predicted to continue as projected solar activity increases towards and beyond the millennium.

  15. How and why does antarctic sea-ice vary?

    Hanna, Edward
    This research looking at the role of Antarctic sea-ice/ocean coupling in global climate change on the interannual timescale has involved: (1) Composing a more accurate time series of Antarctic sea-ice extent back as far as the homogeneous satellite record allows. (2) Statistically comparing this record with spatially-gridded temporal data of relevant climatological variables for the high-latitude Southern Ocean, including surface pressure, temperature, wind speed, precipitation and cloud cover, and searching for any present trends or correlations. The principal results of this Ph.D. research are summarised here.

  16. Patterns and variations of snow accumulation over Greenland, 1979-98, from ECMWF analyses, and their verification

    Hanna, E.; Valdes, P.; McConnell, J.
    ECMWF monthly climate analyses were used to retrieve surface temperature, precipitation, evaporation/ sublimation, and in conjunction with a simple meteorological model, snow accumulation over Greenland for 1979-98. The modeled snow accumulation is compared with existing observational maps of Greenland accumulation and mass balance, and with widely distributed coincident and contemporaneous ice-core data, primarily from NASA's Program in Arctic Regional Climate Assessment (PARCA) program. ECMWF-derived accumulation gave more realistic values for substantial (2-3-km elevation) areas of the "intermediate" inland plateau than previous methods, although the estimates are still (2�0-30) too low over central Greenland. Overall, this ECMWF-driven model provides a reasonable...

  17. The climate of Kangerlussuaq, Southwest Greenland

    Hanna, Edward
    Recently published climate data for Kangerlussuaq, Greenland, show no signs of significant climatic change from 1976-99. In contrast to the global temperature record, there is no evidence for recent warming at this site.

  18. Observed and modeled Greenland Ice Sheet snow accumulation, 1958-2003, and links with regional climate forcing

    Hanna, E.; McConnell, J.; Das, S.; Cappelen, J.; Stephens, A.
    Annual and monthly snow accumulation for the Greenland Ice Sheet was derived from ECMWF forecasts mainly 40-yr ECMWR Re-Analysis (ERA-40) and further meteorological modeling. Modeled accumulation was validated using 58 ice core accumulation datasets across the ice sheet and was found to be 95% of the observed accumulation on average, with a mean correlation of 0.53 between modeled and observed. Many of the ice core datasets are new and are presented here for the first time. Central and northern interior parts of the ice sheet were found to be �10%-30% too dry in ERA-40, in line with earlier ECMWF analysis,...

  19. Observed and modeled Greenland Ice Sheet snow accumulation, 1958-2003, and links with regional climate forcing

    Hanna, E.; McConnell, J.; Das, S.; Cappelen, J.; Stephens, A.
    Annual and monthly snow accumulation for the Greenland Ice Sheet was derived from ECMWF forecasts mainly 40-yr ECMWR Re-Analysis (ERA-40) and further meteorological modeling. Modeled accumulation was validated using 58 ice core accumulation datasets across the ice sheet and was found to be 95% of the observed accumulation on average, with a mean correlation of 0.53 between modeled and observed. Many of the ice core datasets are new and are presented here for the first time. Central and northern interior parts of the ice sheet were found to be �10%-30% too dry in ERA-40, in line with earlier ECMWF analysis,...

  20. Icelandic coastal sea surface temperature records constructed: putting the pulse on air-sea-climate interactions in the northern North Atlantic. Part I: Comparison with HadISST1 open-ocean surface temperatures and preliminary analysis of long-term patterns and anomalies of SSTs around Iceland

    Hanna, E.; Jansson, T.; Olafsson, J.; Valdimarsson, H.
    A new comprehensive record of long-term Icelandic sea surface temperature measurements, which have been updated and filled in with reference to air temperature records, is presented. The new SST series reveal important features of the variability of climate in Iceland and the northern North Atlantic. This study documents site histories and possible resulting inconsistencies and biases, for example, changes in observing sites and instruments. A new 119-yr continuous time series for north Iceland SST is presented, which should prove particularly useful for investigating air-sea ice interactions around northern Iceland. As this is the only part of the country to be...

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