3,772,629 research outputs found
Pattern scaling using ClimGen: monthly-resolution future climate scenarios including changes in the variability of precipitation
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
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)
[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
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
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
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
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)
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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