Reliability and validity of self-reported burnout in college students: A cross randomized comparison of paper-and-pencil vs. online administration

Internet data collection is becoming increasingly popular in all research fields dealing with human perceptions, behaviors and opinions. Advantages of internet data collection, when compared to the traditional paper-and-pencil format, include reduced costs, automatic database creation, and the absence of researcher-related bias effects, such as availability and complete anonymity. However, the validity and reliability of internet gathered data must be established, in comparison to the usual paper-and-pencil accepted formats, before an inferential analysis can be done. In this study, we compared questionnaire data gathered from the internet with that from the traditional paper-and-pencil in a sample of college students. The questionnaires used were the Maslach Burnout Inventory - Student Survey (MBI-SS), the Oldenburg Burnout Inventory (OBI-SS) and the Copenhagen Burnout Inventory (CBI-SS). Data was gathered through a within-subject cross randomized and counterbalanced design, on both internet and paper-and-pencil formats. The results showed no interference in the application order, and a good reliability for both formats. However, concordance between answers was generally higher in the paper-and-pencil format than on the internet. The factorial structure was invariant in the three burnout inventories. Data gathered in this study supports the Internet as a convenient, user-friendly, comfortable and secure data gathering method which does not affect the accepted factorial structures existent in the paper format of the three burnout inventories used.     

Variable-order fractional derivatives and their numerical approximations

This paper addresses the different possible definitions of variable-order derivatives and their numerical approximations; both approximations based upon the definitions and approximations consisting of non-linear transfer functions (in particular combining existing approximations of constant-order fractional derivatives, such as the Crone approximation, with fuzzy logic) are considered. There are different possible configurations, implementing variable-order fractional derivatives both with and without memory of past values of the time-dependent differentiation order.     

Natural Lignocellulosic Fibers as Engineering Materials—An Overview

Recent investigations on the tensile properties of natural cellulose-based fibers revealed an increasing potential as engineering materials. This is particularly the case of very thin fibers of some species such as sisal, ramie, and curaua. However, several other commonly used fibers such as flax, jute, hemp, coir, cotton, and bamboo as well as less known bagasse, piassava, sponge gourde, and buriti display tensile properties that could qualify them as engineering materials. An overview of the strength limits attained by these fibers is presented. Based on a tensile strength vs density chart, it is shown that natural fibers stand out as a relevant class of engineering materials.     

Introducing concurrency in sequential Java via laws

Nowadays multi-core processors can be found everywhere. It is well known that one way of improving performance is by parallelization. In this paper we propose a parallelization strategy for Java using algebraic laws. We perform an experiment with two benchmarks and show that our strategy produces a gain similar to a specialized parallel version provided by the Java Grande Benchmark (JGB).     

A thermocouple vacuum gauge for low vacuum measurement

The construction of a thermocouple vacuum gauge for the range of pressures from 200 to 800 mbar is reported. The gauge differs from similar ones that cover the medium vacuum region. The main difference is that the thermocouple is not fixed to the filament, as usual, but is placed at some distance from the filament.     

Brazing of UNS S32101 and UNS S32304 lean duplex stainless steels and UNS S32750 super duplex with AWS A5.3 BNi-7 (Ni–Cr–P) filler metal

Summary

Weld metals solidified in the ferritic-austenitic solidification mode (FA mode) have dual phases of ferrite and austenite in their as-solidified condition, where ferrite exhibits different morphologies depending on the chemical composition and welding conditions. This paper describes an investigation of the effect of the solidification and transformation sequence on the formation of final ferrite morphologies. Austenite is formed through either a eutectic reaction or peritectic reaction at the dendrite boundaries after the primary formation of ferrite. During the eutectic formation of austenite, the <100>_δ direction of the primary ferrite and the <100>_γ direction of the eutectic austenite are parallel to each other and lie along the growth direction of the primary dendrites. However, any specific lattice plane relationship between the two phases is not identified. During cooling after solidification, the austenite extends into the primary ferrite via solid-state transformation, and the final morphology of the ferrite is vermicular without any coherent orientation relationship between the primary ferrite and eutectic austenite. During peritectic formation of austenite, the Kurdjumov-Sachs orientation relationship is established between the primary ferrite and peritectic austenite, and the <100>_γ direction of the peritectic austenite is not parallel to the growth direction of the primary dendrites. During cooling after solidification, the primary ferrite transforms into austenite, and the final morphology of the ferrite is lathy, since the primary ferrite and peritectic austenite have a favourable coherent orientation.     

Novel diol spiro orthocarbonates derived from glycerol as anti‐shrinkage additives for the cationic photopolymerization of epoxy monomers

Shrinkage that takes place during polymerizations induces internal stress in polymeric materials generating a series of problems like poor adhesion to substrates and delamination in coatings or microcracks and microvoids in composites. Some additives like spiro orthocarbonates can reduce or eliminate this shrinkage. This paper deals with the synthesis of novel diol spiro orthocarbonates (DIOL SOCs) and their effect as anti‐shrinkage additives in the photopolymerization of the monomer 3,4‐epoxycyclohexyl‐3′, 4′‐epoxycyclohexanecarboxylate. It was found that increasing the concentration of the DIOL SOCs resulted in higher conversion of the monomer due to the presence of hydroxyl groups. The viscoelastic properties of the polymer products were also measured. It was observed that at 5 mol% of the mixture of DIOL SOCs there was an increase in the storage modulus due to the crosslinking produced by the bifunctional SOCs. However, at higher concentrations, a decrease in the storage modulus was observed. The level of shrinkage using the DIOL SOCs at 20 mol% was reduced by 45% when compared to the case without any additive. DIOL SOCs can be easily prepared by reacting glycerol with tetraethylorthocarbonate. These additives reduced significantly the level of shrinkage of the polyether derived from the diepoxycyclohexane monomer. Copyright © 2010 Society of Chemical Industry     

Effect of the root canal final rinse protocols on the debris and smear layer removal and on the push‐out strength of an epoxy‐based sealer

The aim of the present study was to evaluate the efficacy of QMiX, SmearClear, and 17% EDTA for the debris and smear layer removal from the root canal and its effects on the push‐out bond strength of an epoxy‐based sealer by scanning electron microscopy (SEM). Forty extracted human canines (n = 10) were assigned to the following final rinse protocols: G1‐distilled water (control), G2–17% EDTA, G3‐SmearClear, and G4‐QMiX. The specimens were submitted to a SEM analysis to evaluate the presence of debris and smear layer, respectively, in the apical or cervical segments. In sequence, forty extracted human maxillary canines with the root canals instrumented were divided into four groups (n = 10) similar to the SEM analysis study. After the filling with AH Plus, the roots were transversally sectioned to obtain dentinal slices. The specimens were submitted to a push‐out bond strength test using an electromechanical testing machine. The statistical analysis for the SEM and push‐out bond strength studies were performed using the Kruskal–Wallis and Dunn tests (α = 5%). There was no difference among the G2, G3, and G4 efficacy in removing the debris and smear layer (P > 0.05). The efficacy of these groups was superior to the control group. The push‐out bond strength values of G2, G3, and G4 were superior to the control group. The ability to remove the debris and smear layer by SmearClear and QMiX was as effective as the 17% EDTA. The final rinse with these solutions promoted similar push‐out bond strength values. Microsc. Res. Tech. 76:533–537, 2013. © 2013 Wiley Periodicals, Inc.     

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