835 research outputs found
In pursuit of the dynamic optimality conjecture
In 1985, Sleator and Tarjan introduced the splay tree, a self-adjusting
binary search tree algorithm. Splay trees were conjectured to perform within a
constant factor as any offline rotation-based search tree algorithm on every
sufficiently long sequence---any binary search tree algorithm that has this
property is said to be dynamically optimal. However, currently neither splay
trees nor any other tree algorithm is known to be dynamically optimal. Here we
survey the progress that has been made in the almost thirty years since the
conjecture was first formulated, and present a binary search tree algorithm
that is dynamically optimal if any binary search tree algorithm is dynamically
optimal.Comment: Preliminary version of paper to appear in the Conference on Space
Efficient Data Structures, Streams and Algorithms to be held in August 2013
in honor of Ian Munro's 66th birthda
Accelerated Particle Swarm Optimization and Support Vector Machine for Business Optimization and Applications
Business optimization is becoming increasingly important because all business
activities aim to maximize the profit and performance of products and services,
under limited resources and appropriate constraints. Recent developments in
support vector machine and metaheuristics show many advantages of these
techniques. In particular, particle swarm optimization is now widely used in
solving tough optimization problems. In this paper, we use a combination of a
recently developed Accelerated PSO and a nonlinear support vector machine to
form a framework for solving business optimization problems. We first apply the
proposed APSO-SVM to production optimization, and then use it for income
prediction and project scheduling. We also carry out some parametric studies
and discuss the advantages of the proposed metaheuristic SVM.Comment: 12 page
Simple heuristics for the assembly line worker assignment and balancing problem
We propose simple heuristics for the assembly line worker assignment and
balancing problem. This problem typically occurs in assembly lines in sheltered
work centers for the disabled. Different from the classical simple assembly
line balancing problem, the task execution times vary according to the assigned
worker. We develop a constructive heuristic framework based on task and worker
priority rules defining the order in which the tasks and workers should be
assigned to the workstations. We present a number of such rules and compare
their performance across three possible uses: as a stand-alone method, as an
initial solution generator for meta-heuristics, and as a decoder for a hybrid
genetic algorithm. Our results show that the heuristics are fast, they obtain
good results as a stand-alone method and are efficient when used as a initial
solution generator or as a solution decoder within more elaborate approaches.Comment: 18 pages, 1 figur
Aquatics reconstruction software: the design of a diagnostic tool based on computer vision algorithms
Computer vision methods can be applied to a variety of medical and surgical applications, and many techniques and algorithms are available that can be used to recover 3D shapes and information from images range and volume data. Complex practical applications, however, are rarely approachable with a single technique, and require detailed analysis on how they can be subdivided in subtasks that are computationally treatable and that, at the same time, allow for the appropriate level of user-interaction. In this paper we show an example of a complex application where, following criteria of efficiency, reliability and user friendliness, several computer vision techniques have been selected and customized to build a system able to support diagnosis and endovascular treatment of Abdominal Aortic Aneurysms. The system reconstructs the geometrical representation of four different structures related to the aorta (vessel lumen, thrombus, calcifications and skeleton) from CT angiography data. In this way it supports the three dimensional measurements required for a careful geometrical evaluation of the vessel, that is fundamental to decide if the treatment is necessary and to perform, in this case, its planning. The system has been realized within the European trial AQUATICS (IST-1999-20226 EUTIST-M WP 12), and it has been widely tested on clinical data
Coordinate-Space Hartree-Fock-Bogoliubov Description of Superfluid Fermi Systems
Properties of strongly interacting, two-component finite Fermi systems are
discussed within the recently developed coordinate-space
Hartree-Fock-Bogoliubov (HFB) code {\hfbax}. Two illustrative examples are
presented: (i) weakly bound deformed Mg isotopes, and (ii) spin-polarized
atomic condensates in a strongly deformed harmonic trap.Comment: 4 pages, 2 figures, ENAM 2008 conference proceedings (EPJA
Safety Outcomes and Near-Adult Height Gain of Growth Hormone-Treated Children with SHOX Deficiency: Data from an Observational Study and a Clinical Trial
Background/Aims: To assess auxological and safety data for growth hormone (GH)-Treated children with SHOX deficiency. Methods: Data were examined for GH-Treated SHOX-deficient children (n = 521) from the observational Genetics and Neuroendocrinology of Short Stature International Study (GeNeSIS). For patients with near-Adult height information, GeNeSIS results (n = 90) were compared with a clinical trial (n = 28) of SHOX-deficient patients. Near-Adult height was expressed as standard deviation score (SDS) for chronological age, potentially increasing the observed effect of treatment. Results: Most SHOX-deficient patients in GeNeSIS had diagnoses of Leri-Weill syndrome (n = 292) or non-syndromic short stature (n = 228). For GeNeSIS patients with near-Adult height data, mean age at GH treatment start was 11.0 years, treatment duration 4.4 years, and height SDS gain 0.83 (95% confidence interval 0.49-1.17). Respective ages, GH treatment durations and height SDS gains for GeNeSIS patients prepubertal at baseline (n = 42) were 9.2 years, 6.0 years and 1.19 (0.76-1.62), and for the clinical trial cohort they were 9.2 years, 6.0 years and 1.25 (0.92-1.58). No new GH-related safety concerns were identified. Conclusion: Patients with SHOX deficiency who had started GH treatment before puberty in routine clinical practice had a similar height gain to that of patients in the clinical trial on which approval for the indication was based, with no new safety concerns
Effect of thyroid hormone therapy on fatigability in older adults with subclinical hypothyroidism: a nested study within a randomized placebo-controlled trial
Background:
Fatigue often triggers screening for and treatment of subclinical hypothyroidism. However, data on the impact of levothyroxine on fatigue is limited and previous studies might not have captured all aspects of fatigue.
Method:
This study is nested within the randomized, placebo-controlled, multicenter TRUST trial, including community-dwelling participants aged ≥65 and older, with persistent subclinical hypothyroidism (TSH 4.60–19.99 mIU/L, normal free thyroxine levels) from Switzerland and Ireland. Interventions consisted of daily levothyroxine starting with 50 μg (25 μg if weight <50 kg or known coronary heart diseases) together with dose adjustments to achieve a normal TSH and mock titration in the placebo group. Main outcome was the change in physical and mental fatigability using the Pittsburgh Fatigability Scale over 1 year, assessed through multivariable linear regression with adjustment for country, sex, and levothyroxine starting dose.
Results:
Among 230 participants, the mean ± standard deviation (SD) TSH was 6.2 ± 1.9 mIU/L at baseline and decreased to 3.1 ± 1.3 with LT4 (n = 119) versus 5.3 ± 2.3 with placebo (n = 111, p < .001) after 1 year. After adjustment we found no between-group difference at 1 year on perceived physical (0.2; 95% CI −1.8 to 2.1; p = .88), or mental fatigability (−1.0; 95% CI −2.8 to 0.8; p = .26). In participants with higher fatigability at baseline (≥15 points for the physical score [n = 88] or ≥13 points for the mental score [n = 41]), the adjusted between-group differences at 1 year were 0.4 (95% CI −3.6 to 2.8, p = .79) and −2.2 (95% CI −8.8 to 4.5, p = .51).
Conclusions:
Levothyroxine in older adults with mild subclinical hypothyroidism provides no change in physical or mental fatigability
The 3-3-1 model with S_4 flavor symmetry
We construct a 3-3-1 model based on family symmetry S_4 responsible for the
neutrino and quark masses. The tribimaximal neutrino mixing and the diagonal
quark mixing have been obtained. The new lepton charge \mathcal{L} related to
the ordinary lepton charge L and a SU(3) charge by L=2/\sqrt{3} T_8+\mathcal{L}
and the lepton parity P_l=(-)^L known as a residual symmetry of L have been
introduced which provide insights in this kind of model. The expected vacuum
alignments resulting in potential minimization can origin from appropriate
violation terms of S_4 and \mathcal{L}. The smallness of seesaw contributions
can be explained from the existence of such terms too. If P_l is not broken by
the vacuum values of the scalar fields, there is no mixing between the exotic
and the ordinary quarks at the tree level.Comment: 20 pages, revised versio
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