We attempt to reconcile the two distinct views of approximationclasses: syntactic and computational. Syntactic classes such as MAX SNP permit structural results and have natural complete problems, while computational classes such as APX allow us to work with classes of problems whose approximability is well-understood. Our results provide a syntactic characterization of computational classes, a...

Previous studies suggest that abscisic acid (ABA) stimulates the activities of antioxidant enzymes under normal and chilling temperature and enhanced chilling resistance in Stylosanthes guianensis. The objective of this study was to test whether nitric oxide (NO) is involved in the ABA-induced activities of the antioxidant enzymes in Stylosanthes guianensis due to its nature as a second messeng...

Reactive oxygen intermediates (ROI) play a critical role in the defense of plants against invading pathogens. Produced during the "oxidative burst," they are thought to activate programmed cell death (PCD) and induce antimicrobial defenses such as pathogenesis-related proteins. It was shown recently that during the interaction of plants with pathogens, the expression of ROI-detoxifying enzymes ...

External applications of strigolactones affect plant growth positively owing to the potential adapting plants tolerance system under stress conditions. In this study, effect synthetic analogue strigolactone (GR24) pre-treatment seeds salt-tolerant and salt-sensitive bread wheat (Triticum aestivum L.) varieties on parameters, antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate per...

We prove that the multiple sequence alignment problem with weighted sum-of-pairs score is APX-hard for arbitrary metric scoring functions over the binary alphabet. This holds even when the weights are restricted to zero and one.

Let P be a set of points in R, and let α > 1 be a real number. We define the distance between two points p, q ∈ P as |pq|, where |pq| denotes the standard Euclidean distance between p and q. We denote the traveling salesman problem under this distance function by Tsp(d,α). We design a 5-approximation algorithm for Tsp(2,2) and generalize this result to obtain an approximation factor of 3 + √ 6 ...