A novel class of scheduling policies for the stochastic resource-constrained project scheduling problem.

We study the resource-constrained project scheduling problem with stochastic activity durations. We introduce a new class of scheduling policies for this problem, which make a number of a-priori sequencing decisions in a pre-processing phase, while the remaining decisions are made dynamically during project execution. The pre-processing decisions entail the addition of precedence constraints to the scheduling instance, hereby resolving some potential resource conflicts. We compare the performance of this new class with existing scheduling policies for the stochastic resource-constrained project scheduling problem, and we observe that the new class is significantly better when the variability in the activity durations is medium to high.Project scheduling; Uncertainty; Stochastic activity durations; Scheduling policies;

Prevalence of Class 1, 2, and 3 Integrons and Biofilm Formation in Pseudomonas aeruginosa and Acinetobacter baumannii among ICU and nonICU Patients

Background: Infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii are of greatest concern for hospitalized patients, particularly those in intensive care units (ICUs). The aims of this study were to investigate the prevalence of integrons and biofilm formation among P. aeruginosa and A. baumannii isolates collected from ICU and non-ICU inpatients. Materials and Methods: A total of 90 P. aeruginosa and 90 A. baumannii isolates were recovered from patients admitted into diverse units of Shahid Mohammadi hospital in Bandar Abbas from January to December 2014. Bacterial identification was carried out by phenotypic methods and PCR. Antibiotic susceptibility was measured by disk diffusion assay. The presence of Class 1, 2, and 3 integrons were evaluated by multiplex-PCR. Biofilm quantification was done by microtiter method. Results: The highest number of isolates (48%) were recovered from ICU patients. 81% of P. aeruginosa isolates were sensitive to piperacillin/tazobactam and ticarcillin, while 60% were resistant to third generation of cephalosporins. In case of A. baumannii, all the isolates were sensitive to colistin, but 98% were resistant to other antibiotics (p≤0.05). Susceptibility to ceftazidime, ticarcillin, imipenem, and piperacillin/tazobactam were higher among isolates obtained from non-ICU patients. Class 1 integron was detected in 13.3% of the P. aeruginosa and 40% of the A. baumannii isolates, while Class 2 integron was harbored by 7 and 6.6% of the isolates, respectively. Furthermore, 23% of the A. baumannii and 12% of the P. aeruginosa isolates showed strong biofilm activity. Conclusion: Class 1 integron-positive isolates were resistant to three classes of antibiotics and predominantly observed in specimens collected from ICU patients showing strong biofilm

A new approach for cell formation and scheduling with assembly operations and product structure

In this paper, a new formulation model for cellular manufacturing system (CMS) design problem is proposed. The proposed model of this paper considers assembly operations and product structure so that it includes the scheduling problem with the formation of manufacturing cells, simultaneously. Since the proposed model is nonlinear, a linearization method is applied to gain optimal solution when the model is solved using direct implementation of mixed integer programming. A new genetic algorithm (GA) is also proposed to solve the resulted model for large-scale problems. We examine the performance of the proposed method using the direct implementation and the proposed GA method. The results indicate that the proposed GA approach could provide efficient assembly and product structure for real-world size problems

A simple approach to the two-dimensional guillotine cutting stock problem

Cutting stock problems are within knapsack optimization problems and are considered as a non-deterministic polynomial-time (NP)-hard problem. In this paper, two-dimensional cutting stock problems were presented in which items and stocks were rectangular and cuttings were guillotine. First, a new, practical, rapid, and heuristic method was proposed for such problems. Then, the software implementation and architecture specifications were explained in order to solve guillotine cutting stock problems. This software was implemented by C++ language in a way that, while running the program, the operation report of all the functions was recorded and, at the end, the user had access to all the information related to cutting which included order, dimension and number of cutting pieces, dimension and number of waste pieces, and waste percentage. Finally, the proposed method was evaluated using examples and methods available in the literature. The results showed that the calculation speed of the proposed method was better than that of the other methods and, in some cases, it was much faster. Moreover, it was observed that increasing the size of problems did not cause a considerable increase in calculation time. In another section of the paper, the matter of selecting the appropriate size of sheets was investigated; this subject has been less considered by far. In the solved example, it was observed that incorrect selection from among the available options increased the amount of waste by more than four times. Therefore, it can be concluded that correct selection of stocks for a set of received orders plays a significant role in reducing waste

In Vitro Microleakage of Mineral Trioxide Aggregate, Calcium-Enriched Mixture Cement and Biodentine Intra-Orifice Barriers

Introduction: This in vitro study compared the coronal microleakage of mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement and Biodentine as intra-orifice barriers. Methods and Materials: The study was conducted on 76 extracted single-canal human teeth. Their root canals were prepared using ProTaper rotary files and filled with gutta percha and AH-26 sealer using lateral condensation technique. Coronal 3 mm of the gutta percha was removed from the root canals and replaced randomly with MTA, CEM cement or Biodentine in the three experimental groups (n=22). A positive and a negative control group were also included (n=5). The entire root surfaces of all teeth were covered with two layers of nail varnish in such a way that only the access openings were not coated. In the negative control group, the access opening was also coated with nail varnish. All teeth were immersed in India ink and after clearing, the samples were evaluated under a stereomicroscope under ×10 magnification to assess the degree of dye penetration. The data were analyzed using the Kruskal-Wallis test. The level of significance was set at 0.05. Results: The negative control group showed no leakage while the positive control group showed significantly higher microleakage than the test groups (P>0.05). CEM cement had the lowest (0.175±0.068 mm) and MTA showed the highest dye penetration (0.238±0.159 mm) among the experimental groups; although these differences were not statistically significant (P=0.313). Conclusion: CEM cement exhibited the least microleakage as an intra-orifice barrier in endodontically treated teeth.Keywords: Biodentine; Calcium-Enriched Mixture; Intra-Orifice Barrier; Microleakage; Mineral Trioxide Aggregat

A Comparison of the REMBRANDT System with a New Approach in AHP

Analytic hierarchy process (AHP) has been criticized considerably for possible rank reversal phenomenon caused by the addition or deletion of an alternative. While in many cases this is a perfectly valid phenomenon, there are also many cases where ranks should be preserved. Our findings indicate that using the geometric mean reduces the variance in ratings substantially; hence, yielding lower inconsistency in ratings. An approach is therefore proposed using the geometric mean aggregation to avoid rank reversal phenomenon. A practical example is examined using the proposed approach to demonstrate its validity and racticability in rank preservation. This paper also compares the REMBRANDT system with the proposed approach to avoid rank reversal phenomenon

Multiple Batch Sizing through Batch Size Smoothing

Batch sizing in different planning period is categorized as a classical problem in production planning, that so many exact & heuristic methods have been proposed to solve this problem, each of which considering various aspects of the original problem. The solution obtained from majority – e.g. MRP – is in this format that there may be some periods of idleness or each period should produce as needed in different adjacent periods. If there are more the one final independent product to be produced in a factory, this makes the production planning experience strong variations in batch sizes for different periods, which production managers are opposed to these proposed production plans. In this paper, some of the models are proposed to solve this shortcoming of the production plan to smooth the variation of batch sizes and consequently to meet the managers ideal. Finally all of the proposed models are used in a real case problem and the best model is introduced in that case

Building a Multi-Objective Model for Multi-Product Multi-Period Production Planning with Controllable Processing Times: A Real Case Problem

Model building is a fragile and complex process especially in the context of real cases. Each real case problem has its own characteristics with new concepts and conditions. A correct model should have some essential characteristics such as: being compatible with real conditions, being of sufficient accuracy, being logically traceable and etc. This paper discusses how to build an efficient model for a real case production planning problem. This process is reinforced by providing the proofs confirming the special characteristics of the final model such as proving its NP-Completeness. Also, the extremes of both objective functions – production smoothing versus cost minimizing – are calculated analytically. Finally, the case study and its solution methods are discussed briefly

An empirical study on measuring the relative efficiency using DEA method: A case study of bank industry

Data Envelopment Analysis (DEA) has been widely used as an effective tool for measuring the relative efficiency of similar units by considering various input/output parameters. This paper examines DEA models for the estimation and improvement of organizational inputs and outputs in order to enhance management and decision making processes. We propose an empirical DEA analysis on banking sector by considering several financial and non-financial inputs and outputs. The relative efficiencies of various branches of banks are analyzed in different scenarios. The preliminary results indicate that there are some non-financial items that could significantly change the overall performance of a unit along with other financial items

Cinnamomum zeylanicum extract has antidepressant-like effects by increasing brain-derived neurotrophic factor (BDNF) and its receptor in prefrontal cortex of rats

Objective: Depression is one of the most common mood disorders. Considering the evidence on the effect of Cinnamomum on mood disorders, this study investigatedthe effect of hydroalcoholic extract of Cinnamomum (HEC) in an animal model of depression. Materials and Methods: Thirty-two male rats were selected and divided into four groups (n=8) including: control, depressed, and depressed treated with200 and 400 mg/kg HEC. Depression induction protocol was conducted in all groups except for the control group. Sucrose preference test (SPT) and forced swimming test (FST) were done to analyze the depression score. After four weeks, the animals brain cortex was removed and BDNF protein and tyrosine receptor kinase B (TrkB) gene expression levels were determined by ELISA and Real Time PCR, respectively. Results: The results of this study showed that 400 mg/kg of HEC increased the tendency to drink the sucrose solution. Furthermore, immobility time significantly increased in the depressed group compared to the control group while it was attenuated by administration of 400 mg/kg extract on the 28th day versus the depressed group. Also the extract at both doses increased swimming time compared to the depressed group. In addition, an increase in the BDNF protein and TrkB gene expression levels was observed in the prefrontal cortex of the treatment groups. Conclusion: We found that HEC ameliorated depression symptoms in rats and these effects were probably due to an increase in BDNF proteins and its receptor, TrkB, gene expressions in the prefrontal cortex