Research

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  • A theory of sharecropping: the role of price behavior and imperfect competition
    A theory of sharecropping: the role of price behavior and imperfect competition
    This paper proposes a theory of sharecropping on the basis of price behavior in agriculture and imperfectly competitive nature of rural product markets. We consider a contractual setting between one landlord and one tenant with seasonal variation of price, where the tenant receives a low price for his output while the landlord can sell his output at a higher price by incurring a cost of storage. We consider two different classes of contracts: (i) tenancy contracts and (ii) crop-buying contracts. It is shown that sharecropping is the optimal form within tenancy contracts and it also dominates crop-buying contracts provided the price variation is not too large. Then we consider interlinked contracts that have both tenancy and crop-buying elements and show that there are multiple optimal interlinked contracts. Finally, proposing an equilibrium refinement that incorporates imperfect competition in the rural product market, it is shown that the unique contract that is robust to this refinement results in sharecropping., Also available for download here: http://mpra.ub.uni-muenchen.de/14898/
    AMP-Activated Protein Kinase Regulates the Cell Surface Proteome and Integrin Membrane Traffic
    AMP-Activated Protein Kinase Regulates the Cell Surface Proteome and Integrin Membrane Traffic
    The cell surface proteome controls numerous cellular functions including cell migration and adhesion, intercellular communication and nutrient uptake. Cell surface proteins are controlled by acute changes in protein abundance at the plasma membrane through regulation of endocytosis and recycling (endomembrane traffic). Many cellular signals regulate endomembrane traffic, including metabolic signaling; however, the extent to which the cell surface proteome is controlled by acute regulation of endomembrane traffic under various conditions remains incompletely understood. AMP-activated protein kinase (AMPK) is a key metabolic sensor that is activated upon reduced cellular energy availability. AMPK activation alters the endomembrane traffic of a few specific proteins, as part of an adaptive response to increase energy intake and reduce energy expenditure. How increased AMPK activity during energy stress may globally regulate the cell surface proteome is not well understood. To study how AMPK may regulate the cell surface proteome, we used cell-impermeable biotinylation to selectively purify cell surface proteins under various conditions. Using ESI-MS/MS, we found that acute (90 min) treatment with the AMPK activator A-769662 elicits broad control of the cell surface abundance of diverse proteins. In particular, A-769662 treatment depleted from the cell surface proteins with functions in cell migration and adhesion. To complement our mass spectrometry results, we used other methods to show that A-769662 treatment results in impaired cell migration. Further, A-769662 treatment reduced the cell surface abundance of β1-integrin, a key cell migration protein, and AMPK gene silencing prevented this effect. While the control of the cell surface abundance of various proteins by A-769662 treatment was broad, it was also selective, as this treatment did not change the cell surface abundance of the transferrin receptor. Hence, the cell surface proteome is subject to acute regulation by treatment with A-769662, at least some of which is mediated by the metabolic sensor AMPK., Ross E, Ata R, Thavarajah T, Medvedev S, Bowden P, Marshall JG, et al. (2015) AMP-Activated Protein Kinase Regulates the Cell Surface Proteome and Integrin Membrane Traffic. PLoS ONE 10(5): e0128013.
    Absence of Evidence and Evidence of Absence
    Absence of Evidence and Evidence of Absence
    This paper appears in Faith and Philosophy 24 (2007): 203-228. The published version can be found online at: http://www.pdcnet.org/collection/faithphil_2007_0024_0002_0203_0228.pdf .
    Academic Librarianship: A Crisis or an Opportunity?
    Academic Librarianship: A Crisis or an Opportunity?
    “Academic Librarianship: A Crisis or an Opportunity?" was a one day symposium held at the University of Toronto on November 18, 2011. The symposium provided a forum for stakeholders to consider recent troubling events and developments in the academic library community. The hiring of postdoctoral fellows at McMaster University to replace librarians, the strike by professional librarians at University of Western Ontario in 2011 and threats to the academic freedom of librarians at McGill University have all served as bellwethers and have been rich topics for debate of late. The symposium was intended to provide an opportunity to bring more coherence to the discourse and to consider further initiatives, increased activism, and to begin a process for providing greater leadership around issues relating to academic librarians and academic librarianship. The day was organized around a series of panels. A number of key stakeholders spoke to specific themes: 1) the role of national and provincial labour organizations and local faculty associations; 2) trends and challenges in education and curriculum at library schools; 3) the role of library associations and professional accreditation; and 4) librarians on the front lines. The symposium emerged with a clear call to action: that it is time to become more pro-active in a collective manner, and to use the tremendous interest generated by this event as an opportunity to seek solutions to the challenges facing academic librarianship in Canada. There was overwhelming support for the creation of a virtual forum to continue the discourse and to bring in those who are interested and willing to become engaged but who were unable to participate in the symposium., Partnership: the Canadian Journal of Library and Information Practice and Research, vol. 6, no. 2 (2011). Also available online at: http://journal.lib.uoguelph.ca/index.php/perj/article/view/1678
    Accelerated Compressed Sensing Based CT Image Reconstruction
    Accelerated Compressed Sensing Based CT Image Reconstruction
    In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error .Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%.Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization., Hashemi, S., Beheshti, S., Gill, P. R., Paul, N. S., & Cobbold, R. S. C. (2015). Accelerated compressed sensing based CT image reconstruction. Computational and Mathematical Methods in Medicine, 2015, 1-16. doi:10.1155/2015/161797
    Accessibility to health care facilities in Montreal Island: an application of relative accessibility indicators from the perspective of senior and non-senior residents
    Accessibility to health care facilities in Montreal Island: an application of relative accessibility indicators from the perspective of senior and non-senior residents
    Background Geographical access to health care facilities is known to influence health services usage. As societies age, accessibility to health care becomes an increasingly acute public health concern. It is known that seniors tend to have lower mobility levels, and it is possible that this may negatively affect their ability to reach facilities and services. Therefore, it becomes important to examine the mobility situation of seniors vis-a-vis the spatial distribution of health care facilities, to identify areas where accessibility is low and interventions may be required. Methods Accessibility is implemented using a cumulative opportunities measure. Instead of assuming a fixed bandwidth (i.e. a distance threshold) for measuring accessibility, in this paper the bandwidth is defined using model-based estimates of average trip length. Average trip length is an all-purpose indicator of individual mobility and geographical reach. Adoption of a spatial modelling approach allows us to tailor these estimates of travel behaviour to specific locations and person profiles. Replacing a fixed bandwidth with these estimates permits us to calculate customized location- and person-based accessibility measures that allow inter-personal as well as geographical comparisons. Data The case study is Montreal Island. Geo-coded travel behaviour data, specifically average trip length, and relevant traveller's attributes are obtained from the Montreal Household Travel Survey. These data are complemented with information from the Census. Health care facilities, also geo-coded, are extracted from a comprehensive business point database. Health care facilities are selected based on Standard Industrial Classification codes 8011-21 (Medical Doctors and Dentists). Results Model-based estimates of average trip length show that travel behaviour varies widely across space. With the exception of seniors in the downtown area, older residents of Montreal Island tend to be significantly less mobile than people of other age cohorts. The combination of average trip length estimates with the spatial distribution of health care facilities indicates that despite being more mobile, suburban residents tend to have lower levels of accessibility compared to central city residents. The effect is more marked for seniors. Furthermore, the results indicate that accessibility calculated using a fixed bandwidth would produce patterns of exposure to health care facilities that would be difficult to achieve for suburban seniors given actual mobility patterns. Conclusions The analysis shows large disparities in accessibility between seniors and non-seniors, between urban and suburban seniors, and between vehicle owning and non-owning seniors. This research was concerned with potential accessibility levels. Follow up research could consider the results reported here to select case studies of actual access and usage of health care facilities, and related health outcomes., Paez, A., Mercado, R. G., Farber, S., Morency, C., & Roorda, M. (2010). Accessibility to health care facilities in montreal island: An application of relative accessibility indicators from the perspective of senior and non-senior residents. International Journal of Health Geographics, 9(1), 52-52. doi:10.1186/1476-072X-9-52
    Acoustic Intervention in a Cultural Heritage: The Chapel of the Royal Palace in Caserta, Italy
    Acoustic Intervention in a Cultural Heritage: The Chapel of the Royal Palace in Caserta, Italy
    The modern use of ancient heritage sites can be, to say the least, challenging from an acoustical perspective. In fact, modern needs may require acoustical interventions in contrast with the preservation issues of the cultural heritage. This paper deals with this topic in an UNESCO designated world heritage site, the Palatine Chapel of the Royal Palace in Caserta, Italy. Since this chapel is currently being used for meetings and music chamber concerts, the acoustical characteristics of the chapel, originally used for religious purposes, are investigated. Field measurements were undertaken to evaluate the acoustical performance of the empty chapel. The measurements were then used to calibrate and validate a computer simulation model. Different acoustical treatments are then considered and simulations are used to determine the related acoustical improvements. Finally, the benefits of different acoustical treatments which are respectful of the aesthetic and historical value of this cultural heritage are discussed., Berardi, U., Iannace, G., & Ianniello, C. (2015;2016;). Acoustic intervention in a cultural heritage: The chapel of the royal palace in caserta, italy. Buildings, 6(1), 1. doi:10.3390/buildings6010001, (This article belongs to the Special Issue Selected Papers on Building and Architectural Acoustics from ICSV22)
    Acoustics of a Music Venue/Bar—A Case Study
    Acoustics of a Music Venue/Bar—A Case Study
    A vacant unit, once used by a Portuguese Deli, was converted to a bar/music room in Toronto. The unit was divided into two spaces along its north-south axis. The western portion was designed as a music room that would provide a performance space from a solo artist to a Jazz combo to a small rock band. The eastern part was designed as a regular bar/dining area. The plan also called for a microbrewery unit at the back of the unit. The bar music can be loud, while the music room can be pianissimo to forte depending on the type of performance. The acoustical design aspects are critical for the music room. In addition, the acoustical separation between the two spaces is equally important. The music room/bar is currently in use. The design results are compared to actual field measurements. The results showed that the music venue performed satisfactorily. The acoustical separation between the music venue and the bar/restaurant was better than expected other than an installation deficiency of the south side sound lock doors. The background sound along the northern portion was NC-35 or less. However, the southern portion’s background sound exceeded NC-35 due to the hissing of the return air grille. The acoustical design and the performance results of the music venue-bar/restaurant are presented in this paper., Ramakrishnan, R., & Dumoulin, R. (2016). Acoustics of a music venue/bar—A case study. Buildings, 6(1), 11. doi:10.3390/buildings6010011, (This article belongs to the Special Issue Selected Papers on Building and Architectural Acoustics from ICSV22)
    Action Research in OHS - Shifting from Hypothesis Testing to Experiential Learning?
    Action Research in OHS - Shifting from Hypothesis Testing to Experiential Learning?
    For more details see the case study example: Neumann, W.P., Ekman, M. and Winkel, J., 2009. Integrating ergonomics into system development - The Volvo Powertrain Case. Applied Ergonomics, 40(3): 527-537. doi:10.1016/j.apergo.2008.09.010
    Active Collection of Land Cover Sample Data from Geo-Tagged Web Texts
    Active Collection of Land Cover Sample Data from Geo-Tagged Web Texts
    Sample data plays an important role in land cover (LC) map validation. Traditionally, they are collected through field survey or image interpretation, either of which is costly, labor-intensive and time-consuming. In recent years, massive geo-tagged texts are emerging on the web and they contain valuable information for LC map validation. However, this kind of special textual data has seldom been analyzed and used for supporting LC map validation. This paper examines the potential of geo-tagged web texts as a new cost-free sample data source to assist LC map validation and proposes an active data collection approach. The proposed approach uses a customized deep web crawler to search for geo-tagged web texts based on land cover-related keywords and string-based rules matching. A data transformation based on buffer analysis is then performed to convert the collected web texts into LC sample data. Using three provinces and three municipalities directly under the Central Government in China as study areas, geo-tagged web texts were collected to validate artificial surface class of China’s 30-meter global land cover datasets (GlobeLand30-2010). A total of 6283 geo-tagged web texts were collected at a speed of 0.58 texts per second. The collected texts about built-up areas were transformed into sample data. User’s accuracy of 82.2% was achieved, which is close to that derived from formal expert validation. The preliminary results show that geo-tagged web texts are valuable ancillary data for LC map validation and the proposed approach can improve the efficiency of sample data collection., Hou, D., Chen, J., Wu, H., Li, S., Chen, F., & Zhang, W. (2015). Active collection of land cover sample data from geo-tagged web texts. Remote Sensing, 7(5), 5805-5827. doi:10.3390/rs70505805