OBJECTIVE To evaluate the effect of disinfectants and distilled water on the micro-hardness of heat cure acrylic resins. METHODS The case-control study was conducted at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, and Nadirshaw Edulji Dinshaw University of Engineering and Technology, Karachi, from April to October 2011. Specimens were fabricate...

OBJECTIVES This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. MATERIAL AND METHODS A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group). For th...

We consider offline algorithms for minimizing the total flow time on O(1) machines where jobs can be preempted arbitrarily but migrations are disallowed. Our main result is a quasipolynomial time approximation scheme for minimizing the total flow time. We also consider more general settings and give some hardness results.

The Equal Sum Subsets problem, where we are given a set of positive integers and we ask for two nonempty disjoint subsets such that their elements add up to the same total, is known to be NP-hard. In this paper we give (pseudo-)polynomial algorithms and/or (strong) NP-hardness proofs for several natural variations of Equal Sum Subsets. Among others we present (1) a framework for obtaining NP-ha...

Assuming the Unique Games Conjecture (UGC), we show optimal inapproximability results for two classic scheduling problems. We obtain a hardness of 2 − ε for the problem of minimizing the total weighted completion time in concurrent open shops. We also obtain a hardness of 2 − ε for minimizing the makespan in the assembly line problem. These results follow from a new inapproximability result for...

The Borda voting rule is a positional scoring rule where, for m candidates, for every vote the first candidate receives m− 1 points, the second m− 2 points and so on. A Borda winner is a candidate with highest total score. It has been a prominent open problem to determine the computational complexity of UNWEIGHTED COALITIONAL MANIPULATION UNDER BORDA: Can one add a certain number of additional ...

The physico-chemical properties of water and sediments therein were analyzed for assessing the suitability of Siddheshwar dam (India) waters for irrigation purpose. The physical parameters include total dissolved solids and electrical conductivity. The chemical parameters studied include pH, free carbon dioxide, total hardness, calcium hardness, magnesium hardness, phenolphthalein alkalinity, t...

Background: This research aims to measure and study spatial changes, and the reason behind the increasing nitrate content in water wells in the Central District of Khodabandeh County in the Zanjan Province. Methods: The nitrate and nitrite content, electrical conductivity, dissolved oxygen, temperature, total hardness and pH were measured at 40 sampling stations in the study area. The obtained...

Background & Aims of the Study: Corrosion and scaling play undesirable effects on transmission and distribution system of drinking water. The aim of this study was to assess the corrosion and scaling potential of drinking water resources in Babol city, Iran. Materials and Methods: Totally, 54 water samples were collected from 27 wells in spring and autumn. Calcium har...