Allocating the fixed cost:an approach based on data envelopment analysis and cooperative game

Allocating the fixed cost among a set of users in a fair way is an important issue both in management and economic research. Recently, Du et al. (Eur J Oper Res 235(1): 206–214, 2014) proposed a novel approach for allocating the fixed cost based on the game cross-efficiency method by taking the game relations among users in efficiency evaluation. This paper proves that the novel approach of Du et al. (Eur J Oper Res 235(1): 206–214, 2014) is equivalent to the efficiency maximization approach of Li et al. (Omega 41(1): 55–60, 2013), and may exist multiple optimal cost allocation plans. Taking into account the game relations in the allocation process, this paper proposes a cooperative game approach, and uses the nucleolus as a solution to the proposed cooperative game. The proposed approach in this paper is illustrated with a dataset from the prior literature and a real dataset of a steel and iron enterprise in China

Cost efficiency measures in data envelopment analysis with data uncertainty

This paper extends the classical cost efficiency (CE) models to include data uncertainty. We believe that many research situations are best described by the intermediate case, where some uncertain input and output data are available. In such cases, the classical cost efficiency models cannot be used, because input and output data appear in the form of ranges. When the data are imprecise in the form of ranges, the cost efficiency measure calculated from the data should be uncertain as well. So, in the current paper, we develop a method for the estimation of upper and lower bounds for the cost efficiency measure in situations of uncertain input and output data. Also, we develop the theory of efficiency measurement so as to accommodate incomplete price information by deriving upper and lower bounds for the cost efficiency measure. The practical application of these bounds is illustrated by a numerical example.DEA Cost efficiency Uncertain data Range data Imprecise data Two-level mathematical programming Extreme point DMU

Stability of the classification of returns to scale in FDH models

This paper deals with the estimation of returns to scale (RTS) in free disposal hull (FDH) models and provides some stability intervals for preserving the RTS classification. It has been shown that the proposed stability intervals can be obtained via a polynomial-time algorithm based on the calculation of certain ratios of inputs and outputs, without solving any mathematical programming problem. The results of the study have been proved via some lemmas and theorems and have been illustrated by numerical examples and a real application.DEA FDH Returns-to-scale Polynomial-time algorithms Stability

Investigation of Physiological and Yield Characteristics of Quinoa as Affected by Different Levels of Irrigation and Plant Density

IntroductionQuinoa is a dicotyledonous plant from the Amaranthaceae family, with favorable nutritional value and a high potential for growth and production in adverse environmental conditions. Despite being three carbon, it has high water consumption efficiency and as a new crop, due to its wide adaptation to different environment conditions such as salinity and drought, as well as being premature, it is suitable for planting in arid and desert areas and has many factors. Genetic and environmental factors such as genotype, density, arrangement and planting date, soil salinity, and drought stress affect yield. Among these, drought is one of the most important non-living stresses that cause great damage to crops and horticulture in the world every year. And especially Iran, which is considered an arid and semi-arid country. The effect of moisture stress on plants varies depending on which stage of plant growth occurs and plants can work through various mechanisms such as reducing growth parameters, closing pores, reducing photosynthesis, changing regulatory mechanisms of ion transport, and increasing activity. Antioxidant enzymes cope with drought stress to some extent, although such mechanisms are energy-intensive and cause a decline in performance.Materials and MethodsIn order to investigate the optimal density of quinoa at different levels of irrigation, a factorial experiment was conducted based on completely randomized design with three replications at the research farm of the Faculty of Agriculture, Birjand University. The first factor was irrigation levels (based on 50, 75, and 100% water requirement) and the second factor was plant density at 5 levels (40, 60, 80, 100, and 120 plants m-2). Measurement traits included relative leaf water content, stomatal conductance, electrolyte leakage, number of branches, number of grains per branch, branch weight, 1000-grain weight, grain yield, water use efficiency, and grain protein.Results and DiscussionThe results showed that the yield components in response to low irrigation conditions were significantly reduced, so that the highest 1000-seed weight, number of branches, number of seeds per branch, branch weight and yield at the level of 100% water requirement were, respectively, 0.1 (g), 1368.4 (branching per square meter), 132.64 (grains per branching), 2377.8 (grams per square meter) and 3265.25 (kg ha-1) have been obtained. The maximum orifice conductivity measured at 35.66 (mol CO2 per square meter) was obtained at the beginning of flowering at 100% water requirement. Also, with decreasing irrigation level, physiological traits including relative leaf water content decreased significantly and traits such as electrolyte leakage and grain protein increased. The optimal density at the irrigation level of 100, 75, and 50% of water requirement were 113, 105, and 80 plants per square meter, respectively. The interaction of irrigation levels and density also showed that the highest yield was 100% of water requirement and density of 100 plants with 4226.52 kg ha-1. The results showed that at the irrigation levels of 100 and 75% of the water requirement, the highest yield was obtained at a density of 100 plants and with a decrease in density at these levels by 61.2 and 73.2%, respectively, was associated with a decrease in yield, but at the level of 50%. The highest yield was obtained at a density of 80 plants, which was accompanied by a decrease in yield to 40 plants with a yield of 73.5%. The results also show an increase in optimal density with increasing irrigation level, so that the most optimal density at the irrigation level of 100% of the water requirement is 113 plants per square meter and with increasing the stress to 75 and 50% of the water requirement, respectively, density Optimal yields of 105 and 80 plants per square meter have been achieved.ConclusionIn general, the results show that lack of moisture has an adverse effect on quinoa yield such as 1000-seed weight, branch weight, number of seeds per branch, and number of branches in the main inflorescence and reduces the optimal plant density

The Comparison of Salivary IgA and IgE Levels in Children with Breast- and Formula- Feeding During Infancy Period

Introduction: Oral local immune factors may play a protective role against oral diseases and defend against microbial agents. Salivary immunoglobulin A (IgA) is a major factor for the local host defence against caries and periodontal disease. The aims of this study were to determine the concentrations of salivary IgA and IgE levels in breast-fed and formula-fed children in infancy period.Methods and Materials: Totally, 80 healthy 5 years old children were included in the study. According to type of feeding in infancy period, the children divided into two groups: 50 breast-fed and 30 formula-fed. One milliliter of saliva was collected from each participant, centrifuged, and stored at -70 )C. The salivary IgA and IgE concentrations were measured, using ELISA technique.Results: In breast-fed children, the salivary IgA level (39.6 mg/l ± 17.3) was significantly higher than that in formula-fed children (26.9 mg/l ± 14) (P=0.0001). However, the salivary IgE level was significantly lower in breast-fed children, comparing with formula fed ones (5.01 IU/ml ± 19.70 vs. 11.74 IU/ml ± 39.40) (P=0.047).Discussion: These results suggest that breast feeding enhances salivary IgA level in the early period of life which may contribute in oral cavity immunity. Higher salivary IgE level observed in formula-fed subjects may have a potential role in development of allergic or inflammatory reactions

Responsiveness and minimally important differences for selected Persian-version of outcome measures used in patients with patellofemoral pain syndrome

Purpose: To investigate the responsiveness and determine the minimally important differences (MID) of Persian versions of the Kujala patellofemoral scale (KPS), lower extremity functional scale (LEFS), and functional index questionnaire (FIQ) in patients with patellofemoral pain syndrome (PFPS). Method: Outcome measures including the Persian KPS, LEFS, and FIQ were administered to 233 patients at baseline and then again 4 weeks after physiotherapy. Moreover, the 7-point global rating scale was completed by the patients at 4 weeks. Responsiveness was evaluated using the correlation analysis and the receiver operating characteristics (ROC) method. Results: Correlation analysis showed that the relationship of all outcome measures with the global rating scale falls within the fair range of relationship (Gamma = 0.26-0.40). Moreover, the results of ROC analysis showed that the all outcome measures have acceptable high responsiveness index. Furthermore, the MIDs of 9.5, 4.5, and 1.5 points were obtained for the Persian KPS, LEFS, and FIQ, respectively. Conclusions: The Persian-versions of all outcome measures are responsive for evaluating change following physiotherapy intervention. The MID values obtained in this study will help the clinicians and researchers to determine if a patient with PFPS has experienced a true change following a physiotherapy intervention. © 2014 Informa UK Ltd. All rights reserved

Assessment of ergonomics risk factors influencing incidence of musculoskeletal disorders among office workers

Background: High prevalence of musculoskeletal disorders have been reported by office workers due to the nature of their work. This study aimed to evaluate the prevalence of musculoskeletal disorders in a group of office workers and also to determine the ergonomics risk factors affecting these disorders. &nbsp; Methods: This is a cross-sectional study, performed among 174 office workers in Kerman city, Iran. Data collection tools included demographic and organization information form, the Nordic Musculoskeletal Questinnaire (NMQ), and the Rapid Office Strain Assessment (ROSA) method. The gathered data were analyzed by SPSS software version 16 using descriptive statistics, chi-square test, and logistic regression. &nbsp; Findings: The prevalence of symptoms of musculoskeletal disorders (MSDs) in the past 12 months was reported 60.4 percent. What is more, significant associations were observed between job tenure and hours a day using computer with MSDs (P-value<0.05). In this sense, with &nbsp;one unit increase in job tenure (years) and duration of computer use (hours per day), the probability of incidence of MSDs gone up 17.2 percent and 15.8 percent, respectively. Based on the statistical chi-square test, a significant relationship was reported between the incidence of MSDs and Rapid Office Strain Assessment method (P-value<0.05). &nbsp; Conclution: According to results, ROSA assessment method is an efficient tool in the classification and identification of factors affecting the incidence of MSDs among office workers. Performing corrective measures in the dangerous work stations (the second level identified by ROSA technique), reducing the duration of computer use per day, and doing regular sport activities can be noted in order to decrease the prevalence of MSDs in the study group (office workers)

Nonsingular Integral-Type Dynamic Finite-Time Synchronization for Hyper-Chaotic Systems

In this study, the synchronization problem of chaotic systems using integral-type sliding mode control for a category of hyper-chaotic systems is considered. The proposed control method can be used for an extensive range of identical/non-identical master-slave structures. Then, an integral-type dynamic sliding mode control scheme is planned to synchronize the hyper-chaotic systems. Using the Lyapunov stability theorem, the recommended control procedure guarantees that the master-slave hyper-chaotic systems are synchronized in the existence of uncertainty as quickly as possible. Next, in order to prove the new proposed controller, the master-slave synchronization goal is addressed by using a new six-dimensional hyper-chaotic system. It is exposed that the synchronization errors are completely compensated for by the new control scheme which has a better response compared to a similar controller. The analog electronic circuit of the new hyper-chaotic system using MultiSIM is provided. Finally, all simulation results are provided using MATLAB/Simulink software to confirm the success of the planned control method