13,180 research outputs found

    A Cut Principle for Information Flow

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    We view a distributed system as a graph of active locations with unidirectional channels between them, through which they pass messages. In this context, the graph structure of a system constrains the propagation of information through it. Suppose a set of channels is a cut set between an information source and a potential sink. We prove that, if there is no disclosure from the source to the cut set, then there can be no disclosure to the sink. We introduce a new formalization of partial disclosure, called *blur operators*, and show that the same cut property is preserved for disclosure to within a blur operator. This cut-blur property also implies a compositional principle, which ensures limited disclosure for a class of systems that differ only beyond the cut.Comment: 31 page

    Even at the uttermost ends of the Earth: how seabirds telecouple the Beagle Channel with regional and global processes that affect environmental conservation and socio-ecological sustainability

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    Human-wildlife dynamics exhibit novel characteristics in the Anthropocene, given the unprecedented degree of globalization that has increased the linkages between habitats and people across space and time. This is largely caused by transnational mobility and migration, international labor, resource markets, and trade. Understanding the relationship between humans and wildlife, and their associated telecoupling processes, helps to promote better management practices and governance for reconciling socioeconomic and conservation interests. Even remote places on the globe exhibit these features. For example, in southern Patagonia’s coastal and marine ecosystems, seabirds are not only very abundant and charismatic members of the wildlife community, nowadays, their colonies are a main tourism attraction of global significance, and in the past they were used for consumptive and scientific purposes that also linked the “uttermost ends of the Earth” with distant places. Thus, in this study, we review human-seabird interactions in the iconic Beagle Channel (BC) in the Argentine portion of the Tierra del Fuego Archipelago. We adapted and employed the coupled human and natural systems (CHANS) approach and telecoupling framework to integrate disparate social and biological information and obtain a more holistic understanding of current human-seabird dynamics and trends in the BC. Although our assessment includes the temporal scale of human-seabird relationships, we centered the CHANS and telecoupling analysis on the modern seabird-tourism interaction, focused on the channel’s Argentine sector, in which tourism is most intensively developed. Our synthesis of the BC’s telecoupled CHANS allowed us to recognize the strong historical local-to-global interactions between both human and natural subsystems and the sharp increase in distance telecoupling during the 20th century. Despite this globalizing trend in seabirds connecting the BC’s local ecosystems to distant places, ironically we found few linkages between Argentina and Chile, despite both countries sharing political sovereignty over this single biogeographical unit. Recognizing and studying the telecouplings identified in this study would help multilateral efforts to incorporate the spillover systems (especially with Chile) and sending systems (i.e., transnational tourists’ countries of origin) into extant regional policies (e.g., state protected areas) and global initiatives (e.g., the United Nations’ sustainable development goals). It would also enable more informed decisions regarding specific proposals based on market-based incentives (e.g., payment for ecosystem services), certification schemes (e.g., Distintivo Onashaga) and participatory approaches (e.g., comanagement of natural resources with local communities). Integrating these scales into the management of the BC would help ensure that humans continue to enjoy meaningful relationships with this unique and charismatic wildlife and at the same time reinforce responsible tourism as a local-global strategy for sustainable development and global conservation.Fil: Raya Rey, Andrea Nélida. Universidad Nacional de Tierra del Fuego, Argentina. Instituto de Ciencias Polares, Ambiente y Recursos Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Pizarro Pinochet, Jose Cristobal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad de Concepción; ChileFil: Anderson, Christopher Brian. Universidad Nacional de Tierra del Fuego, Argentina. Instituto de Ciencias Polares, Ambiente y Recursos Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Huettmann, Falk. University Of Alaska; Estados Unido

    Comparison of precoding methods for broadband MIMO systems

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    In this paper we investigate non-linear precoding solutions for the problem of broadband multiple-input multipleoutput (MIMO) systems. Based on a broadband singular value decomposition (BSVD) we can decouple a broadband MIMO channel into independent dispersive spectrally majorised singleinput single-output (SISO) subchannels. Bit loading is proposed to optimally utilise these SISO subchannels after mitigating their individual inter-symbol-interference (ISI) using Tomlinson- Harashima precoding (THP). This method is benchmarked against recent results of both MMSE linear and THP designed for frequency-selective MIMO channels. Simulation results show that better bit-error-ratio (BER) can be achieved especially for higher throughput targets when compared to the benchmar

    COMPASS Calorimetry in view of future plans

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    The COMPASS experiment at the CERN SPS is dedicated to hadron physics with a broad research programme, including the study of the nucleon spin structure using muons as a probe and a variety of issues in meson spectroscopy using hadron beams. The two stage fixed target spectrometer with electromagnetic (em) and hadronic calorimetry in both stages provides photon detection in a wide angular range. As discussed in this paper, the COMPASS em calorimetry plays a crucial r\^{o}le for the Hadron programme started in 2008 as well as for the planned COMPASS future programme of measuring GPDs via exclusive DVCS photons. We present the photon detection coverage foreseen, and first, preliminary results characterising the present performances of both existing COMPASS electromagnetic calorimeters, based on test beam data taken at CERN T9 facility end of 2007

    Rotten Bananas, Hip Hop Heads, and the American Individual: Teaching Eddie Huang’s Memoir Fresh Off the Boat and Its Tropes of Literacy

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    This essay focuses on Fresh Off the Boat as an eminently teachable coming-of-age story, provides critical contexts and directions for teaching this ideologically suggestive text, and sets forth the interpretive argument that the structures and themes of the memoir are fundamentally shaped by the literacy narrative at its core. As such, the text enters into conversation with other literacy narratives that have become so foundational in the teaching of multiethnic literature in the U.S. Moreover, Huang’s tropes of literacy draw from enduring, mythified Americanist discourses that are suggestive of a masculine individualism that, while not unique, is recognizable, instructive, and even problematic as an illustration of a powerful discourse of self-formation. In an effort to speak not only to specialists in U.S. multiethnic literature but also to nonspecialists/generalists, this discussion offers a tripartite approach to teaching this memoir: opening the unit with a sustained, critical, and creative discussion of genre(s), including traditional and popular forms; then inviting students to hone their critical thinking skills through careful rhetorical and ideological analyses of the text’s representations of race, identity, assimilation, and resistance; and ultimately setting forth a focused, conceptual argument about Fresh Off the Boat as a “literacy narrative” while placing the text within a broader U.S. literary history and discourse about the American individual

    Calibration of Tests for Time Dilation in GRB Pulse Structures

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    Two tests for cosmological time dilation in Îł\gamma-ray bursts -- the peak alignment and auto-correlation statistics -- involve averaging information near the times of peak intensity. Both tests require width corrections, assuming cosmological origin for bursts, since narrower temporal structure from higher energy would be redshifted into the band of observation, and since intervals between pulse structures are included in the averaging procedures. We analyze long (>> 2 s) BATSE bursts and estimate total width corrections for trial time-dilation factors (TDF = [1+zdimz_{\rm dim}]/[1+zbrtz_{\rm brt}]) by time-dilating and redshifting bright bursts. Both tests reveal significant trends of increasing TDF with decreasing peak flux, but neither provides sufficient discriminatory power to distinguish between actual TDFs in the range 2--3.Comment: 5 pages in LATeX, REVTEX style, 2 embedded figures. To appear in Third Huntsville GRB Workshop Proceeding

    An Analysis of the Feasibility of Anaerobic Digestion on Small-Scale Dairies in Utah

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    With an ever increasing concern for the environment, different methods of managing organic waste on dairy farms have been explored and analyzed. Anaerobic digestion has long been a popular method of managing organic waste. Its popularity stems from the potential to decrease greenhouse gases, improve air quality and provide a source of additional revenue for the farm. Problems with implementing anaerobic digestion arise from high failure rates, high start-up costs and continuous maintenance and equipment replacement. Subsidies for the initial investment and improved technology have increased the possibility of large-scale dairy farms to adopt anaerobic digestion. Due to economies of scale large-scale dairy farms are more able to adopt anaerobic digestion, but small-scale dairies struggle to finance the investment, maintain the digester system and provide sufficient organic waste to continuously feed the microorganisms inside the digester system. The increasing impact of urbanization greatly impacts the demand for anaerobic digestion on small-scale farms to mitigate the negative effects of organic waste produced by dairy farms. Dr. Conly Hansen at Utah State University suggested we use an IBR digester model to analyze the feasibility of adopting anaerobic digestion on small-scale farms. The IBR digester system is more conducive to small-scale dairies located in regions with varying temperature (i.e., Utah), and may be the solution to mitigate the negative effects of organic farm waste. Dr. Donald McMahon also suggested we analyze the potential of implementing a digester on a dairy farm that produces artisan cheese. We predicted that this would improve the feasibility due to the need to dispose of whey from the cheese production. To determine the feasibility of implementing a digester system on a small-scale dairy farm the net present value and the internal rate of return were calculated to estimate the success of the investment. These financial measures were calculated from equipment price quotes, estimations from the literature review and from using estimated annual receipts and costs for a dairy farm, artisan cheese plant and anaerobic digester system. The feasibility also depends on the success of marketing the products produced from the digester system and the farmer’s participation in incentive programs for digester systems. The products produced vary from electricity to waste disposal services, and marketing an array of diverse products and services is important to the success of the digester system. The feasibility determined by this study was estimated using generalized assumptions from various sources and should be analyzed by individual operations to determine specific farm feasibility

    Strategic Pest Management Booklets for Farmers in Kaffrine, Senegal

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    abstract: When Kaffrine, Senegal, is faced with the threat of a locust plague, farmers tend to struggle with determining what actions and when they should take place to prevent a plague from occurring. The inability of farmers to readily identify the early threats of a locust plague is a primary issue that has been affecting communities in Kaffrine for millennia. Locust plagues affect the functionality of Senegal’s ecosystems, the welfare of its social systems, and the peoples’ economic opportunities. The project focuses on the creation of 300 pest identification booklets that provide five villages in Kaffrine the proper education to prevent locust plagues from forming. I have partnered with the Global Locust Initiative (GLI) to help make these booklets come to fruition as the booklets target the lack of early detection awareness that is at the root of locust plagues. By providing the villages with these booklets, the farmers and community members, will be more educated on how to identify and act on the early threats of a plague. Additional outcomes of creating these booklets are as follows: improved well-being of the farming community, increased millet yields, and enhanced global food system sustainability. As locusts are a migratory pest, it is recommended that more stakeholders are provided the proper educational material to help them identify the early threats of a locust plague to prevent negative externalities from being imposed on the surrounding ecology, individuals, and agriculture
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