39,625 research outputs found
On rational boundary conditions for higher-order long-wave models
Higher-order corrections to classical long-wave theories enable simple and efficient modelling of the onset of wave dispersion and size effects produced by underlying micro-structure. Since such models feature higher spatial derivatives,
one needs to formulate additional boundary conditions when confined to bounded domains. There is a certain controversy associated with these
boundary conditions, because it does not seem possible to justify their choice by purely physical considerations. In this paper an asymptotic model for onedimensional chain of particles is chosen as an exemplary higher-order theory. We demonstrate how the presence of higher-order derivative terms results in
the existence of non-physical “extraneous” boundary layer-type solutions and argue that the additional boundary conditions should generally be formulated to eliminate the contribution of these boundary layers into the averaged solution. Several new methods of deriving additional boundary conditions are presented for essential boundary. The results are illustrated by numerical examples featuring comparisons with an exact solution for the finite chain
On Finding Maximum Cardinality Subset of Vectors with a Constraint on Normalized Squared Length of Vectors Sum
In this paper, we consider the problem of finding a maximum cardinality
subset of vectors, given a constraint on the normalized squared length of
vectors sum. This problem is closely related to Problem 1 from (Eremeev,
Kel'manov, Pyatkin, 2016). The main difference consists in swapping the
constraint with the optimization criterion.
We prove that the problem is NP-hard even in terms of finding a feasible
solution. An exact algorithm for solving this problem is proposed. The
algorithm has a pseudo-polynomial time complexity in the special case of the
problem, where the dimension of the space is bounded from above by a constant
and the input data are integer. A computational experiment is carried out,
where the proposed algorithm is compared to COINBONMIN solver, applied to a
mixed integer quadratic programming formulation of the problem. The results of
the experiment indicate superiority of the proposed algorithm when the
dimension of Euclidean space is low, while the COINBONMIN has an advantage for
larger dimensions.Comment: To appear in Proceedings of the 6th International Conference on
Analysis of Images, Social Networks, and Texts (AIST'2017
Effectiveness of delayed-release dimethyl fumarate on patient-reported outcomes and clinical measures in patients with relapsing-remitting multiple sclerosis in a real-world clinical setting: PROTEC.
Ensaio clĂnico PROTEC, Protocolo nÂş 109MS408Abstract
BACKGROUND:
Patient-reported outcomes (PRO) and clinical outcomes give a broad assessment of relapsing-remitting multiple sclerosis (RRMS) disease.
OBJECTIVE:
The aim is to evaluate the effectiveness of delayed-release dimethyl fumarate (DMF) on disease activity and PROs in patients with RRMS in the clinic.
METHODS:
PROTEC, a phase 4, open-label, 12-month observational study, assessed annualized relapse rate (ARR), proportion of patients relapsed, and changes in PROs. Newly diagnosed and early MS (≤3.5 EDSS and ≤1 relapse in the prior year) patient subgroups were evaluated.
RESULTS:
Unadjusted ARR at 12 months post-DMF versus 12 months before DMF initiation was 75% lower (0.161 vs. 0.643, p < 0.0001) overall (n = 1105) and 84%, 77%, and 71% lower in newly diagnosed, ≤3.5 EDSS, and ≤1 relapse subgroups, respectively. Overall, 88% of patients were relapse-free 12 months after DMF initiation (84%, newly diagnosed; 88%, ≤3.5 EDSS; 88%, ≤1 relapse). PRO measures for fatigue, treatment satisfaction, daily living, and work improved significantly over 12 months of DMF versus baseline.
CONCLUSION:
At 12 months after versus 12 months before DMF initiation, ARR was significantly lower, the majority of patients were relapse-free, and multiple PRO measures showed improvement (overall and for subgroups), suggesting that DMF is effective based on clinical outcomes and from a patient perspective.Clinical trial: A Study Evaluating the Effectiveness of Tecfidera (Dimethyl Fumarate) on Multiple Sclerosis (MS) Disease Activity and Patient-Reported Outcomes (PROTEC), NCT01930708,info:eu-repo/semantics/publishedVersio
An automata characterisation for multiple context-free languages
We introduce tree stack automata as a new class of automata with storage and
identify a restricted form of tree stack automata that recognises exactly the
multiple context-free languages.Comment: This is an extended version of a paper with the same title accepted
at the 20th International Conference on Developments in Language Theory (DLT
2016
Regularity of solutions to higher-order integrals of the calculus of variations
We obtain new regularity conditions for problems of calculus of variations
with higher-order derivatives. As a corollary, we get non-occurrence of the
Lavrentiev phenomenon. Our main regularity result asserts that autonomous
integral functionals with a Lagrangian having coercive partial derivatives with
respect to the higher-order derivatives admit only minimizers with essentially
bounded derivatives
Logarithmic mathematical morphology: a new framework adaptive to illumination changes
A new set of mathematical morphology (MM) operators adaptive to illumination
changes caused by variation of exposure time or light intensity is defined
thanks to the Logarithmic Image Processing (LIP) model. This model based on the
physics of acquisition is consistent with human vision. The fundamental
operators, the logarithmic-dilation and the logarithmic-erosion, are defined
with the LIP-addition of a structuring function. The combination of these two
adjunct operators gives morphological filters, namely the logarithmic-opening
and closing, useful for pattern recognition. The mathematical relation existing
between ``classical'' dilation and erosion and their logarithmic-versions is
established facilitating their implementation. Results on simulated and real
images show that logarithmic-MM is more efficient on low-contrasted information
than ``classical'' MM
Adaptive fuzzy observer based hierarchical sliding mode control for uncertain 2D overhead cranes
© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. This paper proposes a new approach to robustly control a 2D under-actuated overhead crane system, where a payload is effectively transported to a destination in real time with small sway angles, given its inherent uncertainties such as actuator nonlinearities and external disturbances. The control law is proposed to be developed by the use of the robust hierarchical sliding mode control (HSMC) structure in which a second-level sliding surface is formulated by two first-level sliding surfaces drawn on both actuated and under-actuated outputs of the crane. The unknown and uncertain parameters of the proposed control scheme are then adaptively estimated by the fuzzy observer (FO), where the adaptation mechanism is derived from the Lyapunov theory. More importantly, stability of the proposed strategy is theoretically proved. Effectiveness of the proposed adaptive FO-based HSMC approach was extensively validated by implementing the algorithm in both synthetic simulations and real-life experiments, where the results obtained by our method are highly promising
Identification of a second proliferating cell nuclear antigen in the human malarial pathogen Plasmodium falciparum.
Proliferating cell nuclear antigen seems to exist as a single form in higher eukaryotic cells and plays multiple roles in nucleic acid metabolism. We have identified a second additional proliferating cell nuclear antigen (PfPCNA2) in Plasmodium falciparum on the basis of several lines of evidence. (1) PfPCNA2, consisting of 264 amino acid residues with a predicted molecular mass of 30.2kDa, shares only 29% identity and 53% similarity with PfPCNA1 at the amino acid level. (2) Southern blot analyses revealed that the hybridisation pattern of the Pfpcna2 gene is completely different from that of the Pfpcna1 gene. (3) Chromosomal localisation studies showed that Pfpcna2 is located on chromosome 12 while Pfpcna1 is located on chromosome 13. Northern blot analyses revealed two different transcripts of Pfpcna2, one expressed in both asexual and sexual erythrocytic stages, while the other existed only in the sexual stage, implying that PfPCNA2 may play multiple roles in DNA metabolism in different stages of the parasite. Recombinant protein of PfPCNA2, overexpressed in Escherichia coli, has been purified to near homogeneity and shown to form an oligomer, probably a trimer, as revealed by a size-exclusion chromatography and a native gel electrophoresis, suggesting that PfPCNA2, like its higher eukaryotic counterparts, may serve as a sliding platform which is capable of interaction with diverse proteins and regulation of their activities
From weak coupling to spinning strings
We identify the gauge theory dual of a spinning string of minimal energy with
spins S_1, S_2 on AdS_5 and charge J on S^5. For this purpose we focus on a
certain set of local operators with two different types of covariant
derivatives acting on complex scalar fields. We analyse the corresponding
nested Bethe equations for the ground states in the limit of large spins. The
auxiliary Bethe roots form certain string configurations in the complex plane,
which enable us to derive integral equations for the leading and sub-leading
contribution to the anomalous dimension. The results can be expressed through
the observables of the sl(2) sub-sector, i.e. the cusp anomaly f(g) and the
virtual scaling function B_L(g), rendering the strong-coupling analysis
straightforward. Furthermore, we also study a particular sub-class of these
operators specialising to a scaling limit with finite values of the second spin
at weak and strong coupling.Comment: 23 pages, 3 figures, minor changes, references adde
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