1,929 research outputs found
Connecting Terminals and 2-Disjoint Connected Subgraphs
Given a graph and a set of terminal vertices we say that a
superset of is -connecting if induces a connected graph, and
is minimal if no strict subset of is -connecting. In this paper we prove
that there are at most minimal -connecting sets when and that
these can be enumerated within a polynomial factor of this bound. This
generalizes the algorithm for enumerating all induced paths between a pair of
vertices, corresponding to the case . We apply our enumeration algorithm
to solve the {\sc 2-Disjoint Connected Subgraphs} problem in time
, improving on the recent algorithm of Cygan et
al. 2012 LATIN paper.Comment: 13 pages, 1 figur
PULMONARY FUNCTION IN RHEUMATOID ARTHRITIS TREATED WITH LOW-DOSE METHOTREXATE: A LONGITUDINAL STUDY
Lung volumes and gas exchange were investigated prospectively in 96 patients with rheumatoid arthritis selected without regard to pulmonary disorders and treated with i.m. methotrexate (MTX) injections [mean weekly dose 13.0 mg (5th-95th percentile (5-95 PC) 7.6-20.8)]. Individual changes over time during MTX treatment [mean duration 2.9 yr (5-95 PC 0.4-5.3)] were assessed by regression analyses in each individual. Forced vital capacity (FVQ remained stable in the majority of patients [mean annual change +0.8% (5-95 PC −8.1 to +14.0) of calculated normal value]. In addition, transfer factor using the indicator gas CO (TLCO) was unaltered in most patients [mean annual change − 2.1% (5-95 PC −16.2 to +11.8) of predicted value]. However, there were significant decreases in the forced expiratory volume in 1 s (FEV1) before and after inhalation of 0.2 mg salbutamol [mean annual change - 0.8% (5-;95 PC −8.4 to +3.2) and −1.3% (5-95 PC −7.8 to +3.9) of the FVC measured, respectively]. In addition, there were significant increases in alveolar-arterial Po2, gradients (P(A-a), O2) at rest and after exercise [mean annual change +1.7 mmHg (5-;95 PC −5.2 to +12.2) and +1.8 mmHg (5-95 PC −3.5 to 9.0), respectively]. Nevertheless, the amounts were small in view of the reliability of the methods applied and reflect, at least in part, the normal process of ageing. The annual change in FEV1 /FVC was negatively correlated with FEV1 /FVC at baseline (Rs = − 0.46, P < 0.001). The annual change in TL, co was also negatively correlated with TL, co at baseline (Rs = − 0.31, P = 0.028). No other risk factors for deterioration of lung volumes or gas exchange were found, including mean weekly MTX dose, age, gender, smoking, presence of rheumatoid factor and pulmonary function at baseline. We conclude that MTX has no major effect on pulmonary function in the majority of patients and that there is no evidence that patients with pre-existing pulmonary disease are at increased risk for further deterioration of lung functio
Tilings, tiling spaces and topology
To understand an aperiodic tiling (or a quasicrystal modeled on an aperiodic
tiling), we construct a space of similar tilings, on which the group of
translations acts naturally. This space is then an (abstract) dynamical system.
Dynamical properties of the space (such as mixing, or the spectrum of the
translation operator) are closely related to bulk properties of the individual
tilings (such as the diffraction pattern). The topology of the space of
tilings, particularly the Cech cohomology, gives information on how the
original tiling can be deformed. Tiling spaces can be constructed as inverse
limits of branched manifolds.Comment: 8 pages, including 2 figures, talk given at ICQ
Multinet : enabler for next generation enterprise wireless services
Wireless communications are currently experiencing a fast migration toward the beyond third-generation (B3G)/fourth generation (4G) era. This represents a generational change in wireless systems: new capabilities related to mobility and new services support is required and new concepts as individual-centric, user-centric or ambient-aware communications are included. One of the main restrictions associated to wireless technology is mobility management, this feature was not considered in the design phase; for this reason, a complete solution is not already found, although different solutions are proposed and are being proposed. In MULTINET project, features as mobility and multihoming are applied to wireless network to provide the necessary network and application functionality enhancements for seamless data communication mobility considering end-user scenario and preferences. The aim of this paper is to show the benefits of these functionalities from the Service Providers and final User point of view
Recurrence in 2D Inviscid Channel Flow
I will prove a recurrence theorem which says that any () solution
to the 2D inviscid channel flow returns repeatedly to an arbitrarily small
neighborhood. Periodic boundary condition is imposed along the
stream-wise direction. The result is an extension of an early result of the
author [Li, 09] on 2D Euler equation under periodic boundary conditions along
both directions
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Scenarios as the basis for assessment of mitigation and adaptation
The possibilities and need for adaptation and mitigation depends on uncertain future developments with respect to socio-economic factors and the climate system. Scenarios are used to explore the impacts of different strategies under uncertainty. In this chapter, some scenarios are presented that are used in the ADAM project for this purpose. One scenario explores developments with no mitigation, and thus with high temperature increase and high reliance on adaptation (leading to 4oC increase by 2100 compared to pre-industrial levels). A second scenario explores an ambitious mitigation strategy (leading to 2oC increase by 2100 compared to pre-industrial levels). In the latter scenario, stringent mitigation strategies effectively reduces the risks of climate change, but based on uncertainties in the climate system a temperature increase of 3oC or more cannot be excluded. The analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but even then adaptation will be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which adaptation is more cost-effective than mitigation, but mitigation can help reduce damages and the cost of adaptation. For agriculture, finally, only the scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts
EMG to force processing III: estimation of model parameters for the human triceps surae muscle and assessment of the accuracy by means of a torque plate
Abstract-The parameters of the active state and the seriestlastic component of the Hill muscle model were estimated for the human calf muscles by means of a 'torque plate-on seven normal subjects. Together with the results of the calferSometer experiments (Part II) this yields the complete set of parameters for the EMG to force processor based on the Hill model (Part I). The accuracy of the processor was assessed by means of a set of severe test contractions in which the subjects tilted on one foot at various velocities (slow to as fast as possible). The mechanical work j M$ dr and the integrated torque 5 M dr were calculated for these contractions. M being the torque calculated by the EMG processor and Cp the measured angular velocity. These values of the work and the integrated torque were compared to those obtained with the measured torque M, instead of M. The relative error, for positive work, negative work, and integrated torque was + 6.2"" + 14'; (means + s.d.). Data on the peak values of M -M, are also given. INlRODUCTlON In Part I of this series (Hof and Van den Berg. 1981a) we introduced EMG to force processing by means of an electrical analogue of the Hill muscle model for the human calf muscles. The parameters were given in In this paper we will study the estimation of these parameters by means of a very stiff torque recording device designed for this purpose. which we called a torque plate. For thisestimation we will use fast tilting contractions and very brief isometric contractions. This study completes the estimation of the parameters of the analogue and makes it possible to study its accuracy. The accuracy of the processor was determined by test contractions on the basis of tilting contractions; the subject stood on one leg on the torque plate and went up and down on the ball of one foot. In this type of contraction the calf muscle torque is large and it varies quickly, as well as the angle and angular velocity of the ankle. Because of this we considered it a severe test for the EMG processing method. The accuracy will be given in terms of muscle work W = j M#dt and integrated torque IT = j Mdt. by comparing measured values with processed values
Limit-(quasi)periodic point sets as quasicrystals with p-adic internal spaces
Model sets (or cut and project sets) provide a familiar and commonly used
method of constructing and studying nonperiodic point sets. Here we extend this
method to situations where the internal spaces are no longer Euclidean, but
instead spaces with p-adic topologies or even with mixed Euclidean/p-adic
topologies.
We show that a number of well known tilings precisely fit this form,
including the chair tiling and the Robinson square tilings. Thus the scope of
the cut and project formalism is considerably larger than is usually supposed.
Applying the powerful consequences of model sets we derive the diffractive
nature of these tilings.Comment: 11 pages, 2 figures; dedicated to Peter Kramer on the occasion of his
65th birthda
The rise of fully turbulent flow
Over a century of research into the origin of turbulence in wallbounded shear
flows has resulted in a puzzling picture in which turbulence appears in a
variety of different states competing with laminar background flow. At slightly
higher speeds the situation changes distinctly and the entire flow is
turbulent. Neither the origin of the different states encountered during
transition, nor their front dynamics, let alone the transformation to full
turbulence could be explained to date. Combining experiments, theory and
computer simulations here we uncover the bifurcation scenario organising the
route to fully turbulent pipe flow and explain the front dynamics of the
different states encountered in the process. Key to resolving this problem is
the interpretation of the flow as a bistable system with nonlinear propagation
(advection) of turbulent fronts. These findings bridge the gap between our
understanding of the onset of turbulence and fully turbulent flows.Comment: 31 pages, 9 figure
How model sets can be determined by their two-point and three-point correlations
We show that real model sets with real internal spaces are determined, up to
translation and changes of density zero by their two- and three-point
correlations. We also show that there exist pairs of real (even one
dimensional) aperiodic model sets with internal spaces that are products of
real spaces and finite cyclic groups whose two- and three-point correlations
are identical but which are not related by either translation or inversion of
their windows. All these examples are pure point diffractive.
Placed in the context of ergodic uniformly discrete point processes, the
result is that real point processes of model sets based on real internal
windows are determined by their second and third moments.Comment: 19 page
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