3,772,629 research outputs found

    Pattern scaling using ClimGen: monthly-resolution future climate scenarios including changes in the variability of precipitation

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    Development, testing and example applications of the pattern-scaling approach for generating future climate change projections are reported here, with a focus on a particular software application called “ClimGen”. A number of innovations have been implemented, including using exponential and logistic functions of global-mean temperature to represent changes in local precipitation and cloud cover, and interpolation from climate model grids to a finer grid while taking into account land-sea contrasts in the climate change patterns. Of particular significance is a new approach for incorporating changes in the inter-annual variability of monthly precipitation simulated by climate models. This is achieved by diagnosing simulated changes in the shape of the gamma distribution of monthly precipitation totals, applying the pattern-scaling approach to estimate changes in the shape parameter under a future scenario, and then perturbing sequences of observed precipitation anomalies so that their distribution changes according to the projected change in the shape parameter. The approach cannot represent changes to the structure of climate timeseries (e.g. changed autocorrelation or teleconnection patterns) were they to occur, but is shown here to be more successful at representing changes in low precipitation extremes than previous pattern-scaling methods

    Pattern discovery for semi-structured web pages using bar-tree representation

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    Many websites with an underlying database containing structured data provide the richest and most dense source of information relevant for topical data integration. The real data integration requires sustainable and reliable pattern discovery to enable accurate content retrieval and to recognize pattern changes from time to time; yet, extracting the structured data from web documents is still lacking from its accuracy. This paper proposes the bar-tree representation to describe the whole pattern of web pages in an efficient way based on the reverse algorithm. While previous algorithms always trace the pattern and extract the region of interest from \textit{top root}, the reverse algorithm recognizes the pattern from the region of interest to both top and bottom roots simultaneously. The attributes are then extracted and labeled reversely from the region of interest of targeted contents. Since using conventional representations for the algorithm should require more computational power, the bar-tree method is developed to represent the generated patterns using bar graphs characterized by the depths and widths from the document roots. We show that this representation is suitable for extracting the data from the semi-structured web sources, and for detecting the template changes of targeted pages. The experimental results show perfect recognition rate for template changes in several web targets.Comment: 9 page

    Editor\u27s Introduction (Review Symposium on \u3ci\u3eConverging Divergences: Worldwide Changes in Employment Systems\u3c/i\u3e)

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    [Excerpt] During the past two decades there have been significant changes in employment systems across industrialized countries. Converging Divergences: Worldwide Changes in Employment Systems, by Harry C. Katz and Owen Darbishire, examines changes since 1980 in employment practices in seven industrialized countries—the United States, the United Kingdom, Australia, Germany, Japan, Sweden, and Italy—with a focus on the automotive and telecommunications industries. Katz and Darbishire find that variations in employment patterns within these countries have been increasing over the past two decades. The increase in variation is not simply a result of a decline in union strength in some sectors of the economy; variation has increased within both union and nonunion sectors. Despite this within-country divergence, Katz and Darbishire find that employment systems across countries are converging toward four common patterns of work practices: a low-wage employment pattern; the human resource management (HRM) employment pattern; a Japanese-oriented employment pattern; and a joint team-based employment pattern. Significant differences in national employment-related institutions have resulted in some variation across countries in how these work patterns are implemented. Still, Katz and Darbishire find that there are many commonalities in the employment systems of the seven countries and in the processes through which these commonalities have developed

    Non-radial oscillations in M-giant semi-regular variables: Stellar models and Kepler observations

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    The success of asteroseismology relies heavily on our ability to identify the frequency patterns of stellar oscillation modes. For stars like the Sun this is relatively easy because the mode frequencies follow a regular pattern described by a well-founded asymptotic relation. When a solar like star evolves off the main sequence and onto the red giant branch its structure changes dramatically resulting in changes in the frequency pattern of the modes. We follow the evolution of the adiabatic frequency pattern from the main sequence to near the tip of the red giant branch for a series of models. We find a significant departure from the asymptotic relation for the non-radial modes near the red giant branch tip, resulting in a triplet frequency pattern. To support our investigation we analyze almost four years of Kepler data of the most luminous stars in the field (late K and early M type) and find that their frequency spectra indeed show a triplet pattern dominated by dipole modes even for the most luminous stars in our sample. Our identification explains previous results from ground-based observations reporting fine structure in the Petersen diagram and sub ridges in the period-luminosity diagram. Finally, we find `new ridges' of non-radial modes with frequencies below the fundamental mode in our model calculations, and we speculate they are related to f modes.Comment: 8 page, 5 figures, accepted by ApJL (ApJ, 788, L10

    The Stability Balloon for Two-dimensional Vortex Ripple Patterns

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    Patterns of vortex ripples form when a sand bed is subjected to an oscillatory fluid flow. Here we describe experiments on the response of regular vortex ripple patterns to sudden changes of the driving amplitude a or frequency f. A sufficient decrease of f leads to a "freezing" of the pattern, while a sufficient increase of f leads to a supercritical secondary "pearling" instability. Sufficient changes in the amplitude a lead to subcritical secondary "doubling" and "bulging" instabilities. Our findings are summarized in a "stability balloon" for vortex ripple pattern formation.Comment: 4 pages, 5 figure

    Intra-Day Variability and the Interstellar Medium Towards 0917+624

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    The intra-day variable source 0917+624 displays annual changes in its timescale of variability. This is explained in terms of a scintillation model in which changes in the variability timescale are due to changes in the relative velocity of the scintillation pattern as the Earth orbits the sun. (see also astro-ph/0102050)Comment: 4 pages, 1 figure. Accepted for A&A Letter

    A New Look at the Easy-Hard-Easy Pattern of Combinatorial Search Difficulty

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    The easy-hard-easy pattern in the difficulty of combinatorial search problems as constraints are added has been explained as due to a competition between the decrease in number of solutions and increased pruning. We test the generality of this explanation by examining one of its predictions: if the number of solutions is held fixed by the choice of problems, then increased pruning should lead to a monotonic decrease in search cost. Instead, we find the easy-hard-easy pattern in median search cost even when the number of solutions is held constant, for some search methods. This generalizes previous observations of this pattern and shows that the existing theory does not explain the full range of the peak in search cost. In these cases the pattern appears to be due to changes in the size of the minimal unsolvable subproblems, rather than changing numbers of solutions.Comment: See http://www.jair.org/ for any accompanying file

    Pattern of changes in the amino acid levels in silk gland of silkworm, Bombyx mori L.treated with Indole-3-acetic acid ( IAA)

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    The administration of IAA on the total proteins, protease activity, free amino acids, alanine amino transferase (ALAT) activity and aspartate amino transferase (AAT) activity were studied. The increase of total protein content in silk gland may be either due to increased efflux or decreased proteolysis activity which might lead to accumulation of protein content. The decrease in protease activity level in silk gland may be due to lower rate of histolysis. The decrease in the free amino acid content indicates the faster mobilization of free amino acids into oxidative metabolism in the presence of IAA. The ALAT and AAT activity levels were elevated after treatment indicating the active involvement in the protein synthesis
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