Branch-and-Prune Search Strategies for Numerical Constraint Solving

When solving numerical constraints such as nonlinear equations and inequalities, solvers often exploit pruning techniques, which remove redundant value combinations from the domains of variables, at pruning steps. To find the complete solution set, most of these solvers alternate the pruning steps with branching steps, which split each problem into subproblems. This forms the so-called branch-and-prune framework, well known among the approaches for solving numerical constraints. The basic branch-and-prune search strategy that uses domain bisections in place of the branching steps is called the bisection search. In general, the bisection search works well in case (i) the solutions are isolated, but it can be improved further in case (ii) there are continuums of solutions (this often occurs when inequalities are involved). In this paper, we propose a new branch-and-prune search strategy along with several variants, which not only allow yielding better branching decisions in the latter case, but also work as well as the bisection search does in the former case. These new search algorithms enable us to employ various pruning techniques in the construction of inner and outer approximations of the solution set. Our experiments show that these algorithms speed up the solving process often by one order of magnitude or more when solving problems with continuums of solutions, while keeping the same performance as the bisection search when the solutions are isolated.Comment: 43 pages, 11 figure

Enhancing numerical constraint propagation using multiple inclusion representations

Building tight and conservative enclosures of the solution set is of crucial importance in the design of efficient complete solvers for numerical constraint satisfaction problems (NCSPs). This paper proposes a novel generic algorithm enabling the cooperative use, during constraint propagation, of multiple enclosure techniques. The new algorithm brings into the constraint propagation framework the strength of techniques coming from different areas such as interval arithmetic, affine arithmetic, and mathematical programming. It is based on the directed acyclic graph (DAG) representation of NCSPs whose flexibility and expressiveness facilitates the design of fine-grained combination strategies for general factorable systems. The paper presents several possible combination strategies for creating practical instances of the generic algorithm. The experiments reported on a particular instance using interval constraint propagation, interval arithmetic, affine arithmetic, and linear programming illustrate the flexibility and efficiency of the approac

Interval propagation and search on directed acyclic graphs for numerical constraint solving

The fundamentals of interval analysis on directed acyclic graphs (DAGs) for global optimization and constraint propagation have recently been proposed in Schichl and Neumaier (J. Global Optim. 33, 541-562, 2005). For representing numerical problems, the authors use DAGs whose nodes are subexpressions and whose directed edges are computational flows. Compared to tree-based representations [Benhamou etal. Proceedings of the International Conference on Logic Programming (ICLP'99), pp. 230-244. Las Cruces, USA (1999)], DAGs offer the essential advantage of more accurately handling the influence of subexpressions shared by several constraints on the overall system during propagation. In this paper we show how interval constraint propagation and search on DAGs can be made practical and efficient by: (1) flexibly choosing the nodes on which propagations must be performed, and (2) working with partial subgraphs of the initial DAG rather than with the entire graph. We propose a new interval constraint propagation technique which exploits the influence of subexpressions on all the constraints together rather than on individual constraints. We then show how the new propagation technique can be integrated into branch-and-prune search to solve numerical constraint satisfaction problems. This algorithm is able to outperform its obvious contenders, as shown by the experiment

Effects of selected morphological traits in cotton on natural insect infestations, lint yield, lint percent, and fiber quality

This study was conducted to evaluate the responses of natural insect infestations to selected morphological traits in near-isogenic lines of cotton, Gossypium hirsutum L. Five morphological traits (i.e., okra leaf, nectariless, frego bract, smooth leaf, and glandless) versus the normal check were compared in each of eight genetic backgrounds (i.e., 'Deltapine 16', 'Stoneville 213', 'Auburn 56', 'Delcot 277', 'Coker 310', 'Coker 201', 'TH 149', and Pee Dee 2165). Replicated experiments were conducted under irrigation and without insecticide applications at two locations in Oklahoma for 3 years. Cotton fleahoppers, Pseudatomoscelis seriatus (Reuter); eggs and larvae of the bollworm, Heliothis zea (Boddie); and bollworm-damaged squares were counted. In most cases, interactions of morphological traits X genetic backgrounds were not significant for insect response. The smooth-leaf trait reduced cotton fleahopper populations by 54% compared with normal cotton when averaged over years, locations, backgrounds, and sampling dates. Frego bract increased fleahopper numbers by 64% over the same variables compared to normal cotton. The okra-leaf, nectariless, and glandless traits occasionally influenced fleahopper infestations, but a consistent pattern was not discernible. Probably as a result of relatively mild bollworm infestations, no significant differences between morphological traits and normal cotton were detected for bollworm-damaged squares or for bollworm larvae. Smooth leaf did suppress, to some extent, bollworm oviposition; but the other morphological traits appeared to have little effect on oviposition of that insect

Vibrational dynamics of N-H, C-D, and C = O modes in formamide

By means of heterodyned two-dimensional IR photon echo experiments on liquid formamide and isotopomers the vibrational frequency dynamics of the N-H stretch mode, the C-D mode, and the C = O mode were obtained. In each case the vibrational frequency correlation function is fitted to three exponentials representing ultrafast (few femtoseconds), intermediate (hundreds of femtoseconds), and slow (many picoseconds) correlation times. In the case of N-H there is a significant underdamped contribution to the correlation decay that was not seen in previous experiments and is attributed to hydrogen-bond librational modes. This underdamped motion is not seen in the C-D or C = O correlation functions. The motions probed by the C-D bond are generally faster than those seen by N-H and C = O, indicating that the environment of C-D interchanges more rapidly, consistent with a weaker C-D center dot center dot center dot O = C bond. The correlation decays of N-H and C = O are similar, consistent with both being involved in strong H bonding.open141

Molecular Characterization of Glucose-6-Phosphate Dehydrogenase Deficiency in a University Community in Malaysia

Purpose: To determine the prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency among staff and students of a university community in Malaysia as well as to identify molecular genetics by determination of G6PD mutations.Methods: Cross-sectional and experimental studies were carried out on the staff and students of Advanced Medical and Dental Institute (AMDI) of Universiti Sains Malaysia (USM) from July 2009 to April 2010. Venous blood samples were collected from 87 individuals (45 males and 42 females), all of whom gave informed consent. Full blood count, reticulocyte count, screening test and quantitative determination of G6PD were performed. The deficient subjects were confirmed by standard PCR restriction enzyme. DNA samples from these subjects were analyzed for certain known G6PDmutations by digesting them with appropriate restriction enzymes.Results: Out of the 87 subjects (80 were Malay, 2 were Chinese, 1 was Indian and 4 were others). The total prevalence of G6PD deficiency among the subjects was 4.59 % (4/87), all of whom were Malay males. One of the deficient subjects had G6PD Viangchan, while the other three were G6PDMahidol (487 G>A).Conclusion: The finding of this study demonstrate that the most common mutation among AMDI staff and students is Mahidol (487G>A), followed by mutation Viangchan (871G>A).Keywords: Glucose-6-Phosphate Dehydrogenase, Mahidol, Viangchan, Haemolytic anaemi

Organ-Specific and Development Regulation of the Nopaline Synthase Promoter in Transgenic Tobacco Plants

Control regions of the nopaline synthase (nos) gene have been widely used to express foreign genes in plants since the promoter is active in a wide variety of plant tissues. We report here the characteristics of the nos promoter activity in transgenic tobacco (Nicotiana tabacum) plants at various developmental stages. The promoter was highly active in the lower parts of a plant and gradually decreased in the upper parts. This vertical gradient was maintained throughout plant growth until the flowering stage when the overall promoter strength decreased significantly in the vegetative organs. However, in various flower organs, the nos promoter activities increased dramatically. Higher activity was observed in calyx, corolla, and stamens although the maximum promoter activity in each organ was found at different stages of flower development. The promoter activity in pistils was low and gradually increased in the ovaries after anthesis. In developing fruits, the nos promoter activity was strongly induced during the mid-stage of embryogenesis. These results indicate that the expression of the nos promoter is developmentally regulated and organ specific in transgenic tobacco plants

Subsequent Subarachnoid Hemorrhage from Clinically Unrelated Vertebral Artery Dissection after Thrombolytic Therapy

Thrombolysis administration poses certain safety issues in ischemic stroke patients with cerebrovascular changes that are vulnerable to hemorrhage. Furthermore, the lack of related studies has resulted in an unclear understanding of thrombolysis safety in ischemic stroke patients with intracranial dissection, including those involving the vertebral artery. This study describes a case of a 59-year-old female who developed subarachnoid hemorrhage from clinically unrelated vertebral artery dissection after thrombolysis. Histories of severe headache with posterior fossa involvement in patients receiving thrombolytic therapy may indicate careful assessment for intracranial vertebral artery dissection, even if the clinical picture of the patient suggests another arterial syndrome