1,371 research outputs found
Scenarios for the future Lithuanian State forest sector
Three alternative scenarios to the much debated present organisation of the Lithuanian State forest sector are examined: (i) the integrated, where all functions are delegated to one central administrative authority – the Danish prototype, (ii) the commercialised, where State forests are managed by a commercial State company – the Irish prototype, and (iii) the minimalistic, where only negligible forest areas of special importance remain in State ownership – the Swedish prototype. The scenarios are assessed according to six imperatives: (i) sort out the ambiguity of the present structure, (ii) increase the profitability, (iii) reduce the level of public spending, (iv) accommodate changes in ownership structure, (v) rely on a holistic approach, and (vi) comply with the national forest policy. If adopted, any of the scenarios would most likely improve the various elements of State forestry, although in substantially different ways. Politicians will take the final decision that may be supported by the findings of this study
Equilibria with Arbitrary Market Structure.
Fifty years ago Arrow introduced contingent commodities and Debreu observed that this reinterpretation of a commodity was enough to apply the existing general equilibrium theory to uncertainty and time. This interpretation of general equilibrium theory is the Arrow-Debreu model. The complete market predicted by this theory is clearly unrealistic, and Radner (1972) formulated and proved existence of equilibrium in a multi-period model with incomplete markets. Hart (1975) showed that the lower bound on consumption sets assumed by Radner was an essential limitation, but needed for the result. The problem raised by Hart examples was eventually solved by Duffie and Shafer (1985,86). In these papers are shown generic existence of equilibria in economics with incomplete markets. In this paper the Radner result is extended in other directions. Radner assumed a specific structure of markets, independence of preferences, indifference of preferences, and total and transitive preferences. All of these assumptions are dropped here.
Experimental realization of the Yang-Baxter Equation via NMR interferometry
The Yang-Baxter equation is an important tool in theoretical physics, with
many applications in different domains that span from condensed matter to
string theory. Recently, the interest on the equation has increased due to its
connection to quantum information processing. It has been shown that the
Yang-Baxter equation is closely related to quantum entanglement and quantum
computation. Therefore, owing to the broad relevance of this equation, besides
theoretical studies, it also became significant to pursue its experimental
implementation. Here, we show an experimental realization of the Yang-Baxter
equation and verify its validity through a Nuclear Magnetic Resonance (NMR)
interferometric setup. Our experiment was performed on a liquid state
Iodotrifluoroethylene sample which contains molecules with three qubits. We use
Controlled-transfer gates that allow us to build a pseudo-pure state from which
we are able to apply a quantum information protocol that implements the
Yang-Baxter equation.Comment: 10 pages and 6 figure
Dynamic Relative Compression, Dynamic Partial Sums, and Substring Concatenation
Given a static reference string and a source string , a relative
compression of with respect to is an encoding of as a sequence of
references to substrings of . Relative compression schemes are a classic
model of compression and have recently proved very successful for compressing
highly-repetitive massive data sets such as genomes and web-data. We initiate
the study of relative compression in a dynamic setting where the compressed
source string is subject to edit operations. The goal is to maintain the
compressed representation compactly, while supporting edits and allowing
efficient random access to the (uncompressed) source string. We present new
data structures that achieve optimal time for updates and queries while using
space linear in the size of the optimal relative compression, for nearly all
combinations of parameters. We also present solutions for restricted and
extended sets of updates. To achieve these results, we revisit the dynamic
partial sums problem and the substring concatenation problem. We present new
optimal or near optimal bounds for these problems. Plugging in our new results
we also immediately obtain new bounds for the string indexing for patterns with
wildcards problem and the dynamic text and static pattern matching problem
Output-Sensitive Pattern Extraction in Sequences
Genomic Analysis, Plagiarism Detection, Data Mining, Intrusion Detection, Spam Fighting and Time Series Analysis are just some examples of applications where extraction of recurring patterns in sequences of objects is one of the main computational challenges. Several notions of patterns exist, and many share the common idea of strictly specifying some parts of the pattern and to don\u27t care about the remaining parts. Since the number of patterns can be exponential in the length of the sequences, pattern extraction focuses on statistically relevant patterns, where any attempt to further refine or extend them causes a loss of significant information (where the number of occurrences changes). Output-sensitive algorithms have been proposed to enumerate and list these patterns, taking polynomial time O(n^c) per pattern for constant c > 1, which is impractical for massive sequences of very large length n.
We address the problem of extracting maximal patterns with at most k don\u27t care symbols and at least q occurrences. Our contribution is to give the first algorithm that attains a stronger notion of output-sensitivity, borrowed from the analysis of data structures: the cost is proportional to the actual number of occurrences of each pattern, which is at most n and practically much smaller than n in real applications, thus avoiding the aforementioned cost of O(n^c) per pattern
Effect of DEM data resolution on low relief region sub-watershed boundaries delineating using of SWAT model and DEM derived from CARTOSAT-1 (IRS-P5), SRTM and ASTER
Watersheds are natural integrators of hydrological, biological, and geological processes and as such require an integrated approach to data analysis and modeling, which usually starts delineating accurately a polygon vector layer of watershed boundaries as input. In that way, Garrah sub-watershed in Shahjahanpur district of U.P., India, had been isolated with the objective of evaluate the accuracy of sub-watershed boundaries derived from three different sources: One was delineated by 2.6 m resolution CARTOSAT-1 DEM (IRS-P5) and other two were derived from a 30 m ASTER DEM and a 90 m SRTM DEM, using the Soil and Water Assessment Tool (SWAT) model. In this analysis we found that the accuracy of CARTOSAT-1 DEM is so best for accurate delineation of a sub-watershed in the management of the watershed, and the coarse spatial resolution SRTM DEM (90 m) performed much better and significantly than the high spatial resolution ASTER DEM (30 m) it’s cause of the errors in the ASTER DEM, map algebra was used to define where the “Fill” tool had filled the sinks finding that the errors in the stream network occurred where some especially large fills had occurred. Not only the visual interpretation of the produces figures indicate the SRTM DEM delineated sub-watershed as relatively more accurate from ASTER DEM delineated sub-watershed boundaries, also statistics for the SRTM DEM elevation turned in significantly higher than that of the ASTER DEM. Overall SRTM DEMs offer more precise elevations while, ASTER DEMs offer more details. Therefore, the accuracy of the sub-watershed delineation depends on the first place on the accuracy of the DEM
World cities and global commodity chains: an introduction
The purpose of this special anniversary issue is to assess the possible cross-fertilization between two prominent analytical frameworks: the World City Network framework, in which researchers have studied the emergence of a globalized urban system for the provision of a host of advanced corporate services: and the Global Commodity Chain framework, in which researchers have scrutinized the inter connected functions, operations and transactions through which specific commodities are produced, distributed and consumed in a globalized economy. These two approaches have developed in parallel but have rarely been brought together. This introductory essay identifies the common roots and recent history of these two frameworks, and outlines how the six articles contribute to their theoretical and empirical cross-fertilization
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