2,553 research outputs found
How to avoid potential pitfalls in recurrence plot based data analysis
Recurrence plots and recurrence quantification analysis have become popular
in the last two decades. Recurrence based methods have on the one hand a deep
foundation in the theory of dynamical systems and are on the other hand
powerful tools for the investigation of a variety of problems. The increasing
interest encompasses the growing risk of misuse and uncritical application of
these methods. Therefore, we point out potential problems and pitfalls related
to different aspects of the application of recurrence plots and recurrence
quantification analysis
POOL File Catalog, Collection and Metadata Components
The POOL project is the common persistency framework for the LHC experiments
to store petabytes of experiment data and metadata in a distributed and grid
enabled way. POOL is a hybrid event store consisting of a data streaming layer
and a relational layer. This paper describes the design of file catalog,
collection and metadata components which are not part of the data streaming
layer of POOL and outlines how POOL aims to provide transparent and efficient
data access for a wide range of environments and use cases - ranging from a
large production site down to a single disconnected laptops. The file catalog
is the central POOL component translating logical data references to physical
data files in a grid environment. POOL collections with their associated
metadata provide an abstract way of accessing experiment data via their logical
grouping into sets of related data objects.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, 1 eps figure, PSN MOKT00
Expanding direction of the period doubling operator
We prove that the period doubling operator has an expanding direction at the
fixed point. We use the induced operator, a ``Perron-Frobenius type operator'',
to study the linearization of the period doubling operator at its fixed point.
We then use a sequence of linear operators with finite ranks to study this
induced operator. The proof is constructive. One can calculate the expanding
direction and the rate of expansion of the period doubling operator at the
fixed point
How Hard is Counting Triangles in the Streaming Model
The problem of (approximately) counting the number of triangles in a graph is
one of the basic problems in graph theory. In this paper we study the problem
in the streaming model. We study the amount of memory required by a randomized
algorithm to solve this problem. In case the algorithm is allowed one pass over
the stream, we present a best possible lower bound of for graphs
with edges on vertices. If a constant number of passes is allowed,
we show a lower bound of , the number of triangles. We match,
in some sense, this lower bound with a 2-pass -memory algorithm
that solves the problem of distinguishing graphs with no triangles from graphs
with at least triangles. We present a new graph parameter -- the
triangle density, and conjecture that the space complexity of the triangles
problem is . We match this by a second algorithm that solves
the distinguishing problem using -memory
Diffuse postoperative peritonitis -value of diagnostic parameters and impact of early indication for relaparotomy
<p>Abstract</p> <p>Objective</p> <p>Current criteria for performing relaparotomy for suspected peritonitis are non explicit and based on non-quantitative, subjective arguments or hospital practice. The aim of this study was to determine the value of routinely used clinical and diagnostic parameters in early detection of postoperative, diffuse peritonitis (PP). Furthermore, the prognosis and outcome after early indication for relaparotomy in patients with PP compared to community-aquired peritonitis (CAP) was evaluated.</p> <p>Methods</p> <p>Between 1999 and 2008, a total of 251 patients with diffuse secondary peritonitis either postoperative (PP) or community acquired (CAP) were analyzed retrospectively. PP (n = 114) and CAP (n = 137) were compared regarding physical examination, MPI-Score, APACHE II-Score, evidence of organ failure, laboratory parameters, diagnostic instruments and clinical course. The treatment regimen comprised surgical source control (with/without programmed lavage), abdominal closure and relaparotomy on demand, broad spectrum antibiotic therapy and intensive care support.</p> <p>Results</p> <p>The APACHE II-Score (20 CAP vs. 22 PP, p = 0.012), MPI-Score (27 CAP vs. 30 PP, p = 0.001) and the number of lavages differed significantly. Positive phyiscal testing and signs of sepsis [abdominal pain (81.6% PP vs. CAP 97.1%, p = 0.03), rebound tenderness (21.9% vs. 35.8%, p = 0.02), fever (35.1% vs. 51.8%, p = 0.03)] occurred significantly less often in the PP patients than in the CAP group. Conventional radiography (66.2%) and ultrasonography (44.3%) had a lower diagnostic sensitivity than did abdominal CT-scan (97.2%). Mortality was higher in the PP group but did not differ significantly between the two groups (47.4% PP vs. 35.8% CAP, p = 0.06).</p> <p>Conclusion</p> <p>The value of physical tests and laboratory parameters in diagnosing abdominal sepsis is limited. CT-scanning revealed the highest diagnostic accuracy. A treatment regimen of early relaprotomy appears to be the most reasonable strategy for as early discovery of postoperative peritonitis as possible.</p
Ergodic properties of quasi-Markovian generalized Langevin equations with configuration dependent noise and non-conservative force
We discuss the ergodic properties of quasi-Markovian stochastic differential
equations, providing general conditions that ensure existence and uniqueness of
a smooth invariant distribution and exponential convergence of the evolution
operator in suitably weighted spaces, which implies the validity
of central limit theorem for the respective solution processes. The main new
result is an ergodicity condition for the generalized Langevin equation with
configuration-dependent noise and (non-)conservative force
Existence of the Bogoliubov S(g) operator for the quantum field theory
We prove the existence of the Bogoliubov S(g) operator for the
quantum field theory for coupling functions of compact support in space and
time. The construction is nonperturbative and relies on a theorem of
Kisy\'nski. It implies almost automatically the properties of unitarity and
causality for disjoint supports in the time variable.Comment: LaTeX, 24 pages, minor modifications, typos correcte
The Kolmogorov-Sinai Entropy for Dilute Gases in Equilibrium
We use the kinetic theory of gases to compute the Kolmogorov-Sinai entropy
per particle for a dilute gas in equilibrium. For an equilibrium system, the KS
entropy, h_KS is the sum of all of the positive Lyapunov exponents
characterizing the chaotic behavior of the gas. We compute h_KS/N, where N is
the number of particles in the gas. This quantity has a density expansion of
the form h_KS/N = a\nu[-\ln{\tilde{n}} + b + O(\tilde{n})], where \nu is the
single-particle collision frequency and \tilde{n} is the reduced number density
of the gas. The theoretical values for the coefficients a and b are compared
with the results of computer simulations, with excellent agreement for a, and
less than satisfactory agreement for b. Possible reasons for this difference in
b are discussed.Comment: 15 pages, 2 figures, submitted to Phys. Rev.
Mitochondrial Dynamics and Respiration Within Cells with Increased Open Pore Cytoskeletal Meshes
The cytoskeletal architecture directly affects the morphology, motility, and tensional homeostasis of the cell. In addition, the cytoskeleton is important for mitosis, intracellular traffic, organelle motility, and even cellular respiration. The organelle responsible for a majority of the energy conversion for the cell, the mitochondrion, has a dependence on the cytoskeleton for mobility and function. In previous studies, we established that cytoskeletal inhibitors altered the movement of the mitochondria, their morphology, and their respiration in human dermal fibroblasts. Here, we use this protocol to investigate applicability of power law diffusion to describe mitochondrial locomotion, assessment of rates of fission and fusion in healthy and diseased cells, and differences in mitochondria locomotion in more open networks either in response to cytoskeletal destabilizers or by cell line. We found that mitochondria within fibrosarcoma cells and within fibroblast cells treated with an actin-destabilizing toxin resulted in increased net travel, increased average velocity, and increased diffusion of mitochondria when compared to control fibroblasts. Although the mitochondria within the fibrosarcoma travel further than mitochondria within their healthy counterparts, fibroblasts, the dependence on mitochondria for respiration is much lower with higher rates ofhydrogen peroxide production and was confirmed using the OROBOROS O2K. We also found that rates of fission and fusion of the mitochondria equilibrate despite significant alteration of the cytoskeleton. Rates ranged from 15% to 25%, where the highest rates were observed within the fibrosarcoma cell line. This result is interesting because the fibrosarcoma cell line does not have increased respiration metrics including when compared to fibroblast. Mitochondria travel further, faster, and have an increase in percent mitochondria splitting or joining while not dependent on the mitochondria for a majority of its energy production. This study illustrates the complex interaction between mitochondrial movement and respiration through the disruption of the cytoskeleton
Hierarchy of piecewise non-linear maps with non-ergodicity behavior
We study the dynamics of hierarchy of piecewise maps generated by
one-parameter families of trigonometric chaotic maps and one-parameter families
of elliptic chaotic maps of and types, in detail.
We calculate the Lyapunov exponent and Kolmogorov-Sinai entropy of the these
maps with respect to control parameter. Non-ergodicity of these piecewise maps
is proven analytically and investigated numerically . The invariant measure of
these maps which are not equal to one or zero, appears to be characteristic of
non-ergodicity behavior. A quantity of interest is the Kolmogorov-Sinai
entropy, where for these maps are smaller than the sum of positive Lyapunov
exponents and it confirms the non-ergodicity of the maps.Comment: 18 pages, 8 figure
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