General Learning Effect Research Articles

Machine scheduling problems with a general learning effect

Recently, learning effects in scheduling problems have received growing attention. The position-based learning model seems to be a realistic assumption for the case where the actual processing of the job is mainly machine driven. In this paper, we consider the sum-of-processing-time-based learning model. We propose a learning model which considers both the machine and human learning effects, simultaneously. We first show that the position-based learning and the sum-of-processing-time-based learning models in the literature are special cases of the proposed model. Moreover, we present the solution procedures for some single-machine and some flowshop problems.

Some scheduling problems with general position-dependent and time-dependent learning effects

In scheduling problems with learning effects, most of the research is based on specific learning functions. In this paper, we develop a general model with learning effects where the actual processing time of a job is not only a function of the total normal processing times of the jobs already processed, but also a function of the job’s scheduled position. In particular, it is shown that some single machine scheduling problems and m-machine permutation flowshop problems are still polynomially solvable under the proposed model. These results are significant extensions of some of the existing results on learning effects in the literature.

Single-machine and flowshop scheduling with a general learning effect model

Learning effects in scheduling problems have received growing attention recently. Biskup [Biskup, D. (2008). A state-of-the-art review on scheduling with learning effect. European Journal of Operational Research, 188, 315–329] classified the learning effect scheduling models into two diverse approaches. The position-based learning model seems to be a realistic assumption for the case that the actual processing of the job is mainly machine driven, while the sum-of-processing-time-based learning model takes into account the experience the workers gain from producing the jobs. In this paper, we propose a learning model which considers both the machine and human learning effects simultaneously. We first show that the position-based learning and the sum-of-processing-time-based learning models in the literature are special cases of the proposed model. Moreover, we present the solution procedures for some single-machine and some flowshop problems.

Quality in Endoscopic Ultrasonography: An Assessment of Baseline Compliance and Performance Improvement Using the ASGE-ACG Quality Indicators

Introduction: A task force formed by the ASGE and ACG recently developed a list of quality indicators for the pre-procedure, intra-procedure and post-procedure phases of each endoscopic procedure. During Digestive Disease Week 2007 we reported our baseline compliance to the pre- and intra-procedure quality indicators in our endoscopic ultrasound (EUS) cases. We identified four indicators with the lowest compliance, implemented performance improvement plan and re-measured compliance one year later. Methods: We measured our baseline compliance to each of the published pre- and intra-procedure EUS quality indicators in the EUS procedures performed at Mayo Clinic Jacksonville from 1996 through August 2006. We developed a performance improvement plan targeting the four indicators with the lowest compliance and re-measured these indicators one year later. The improvement plan consisted of notification of each physician and the group of areas for improvement, implementation of a structure dictation template, and education on the ASGE quality metrics and initiative. To control for any general learning effect we looked at our compliance trends over time and performed a sub-analysis comparing our more recent pre-intervention compliance to our 1 year post-intervention compliance. Results: We achieved improvement in all four areas targeted for quality improvement; visualization of the celiac axis in esophageal cancer, visualization of the entire pancreas in suspected pancreatic disease and documentation of submucosal tumor wall layer and echogenicity. Sub-analysis comparing our more recent pre-intervention compliance to our post-intervention compliance revealed statistically significant improvement in 3 of the 4 quality indicators (table 1). Conclusion: A targeted performance improvement plan was successful in achieving improved compliance. Sub-analysis confirmed that our intervention resulted in improvement beyond that expected to occur naturally over time. It remains unknown whether differences in quality are due to procedure performance or documentation. Table 1Quality indicator achievement before and after performance improvement implementation Before performance improvement implementation After performance improvement implementation Quality indicator No. of cases requiring indicator No. (%) of cases with indicator achieved No. of cases requiring indicator No. (%) of cases with indicator achieved P-value (1) Pancreas: visualization of entire pancreas when evaluating suspected pancreatic disease 670 326 (49%) 476 388 (82%) <0.001 (2) Esophagus: visualization of celiac axis in setting of non-obstructive esophageal cancer staging 159 143 (90%) 70 70 (100%) 0.004 (3) Sub-mucosal lesion: Documentation of wall layer for sub-epithelial lesions 105 91 (87%) 49 46 (94%) 0.27 (4) Documentation of echo characteristics for sub-epithelial lesions 105 75 (71%) 49 43 (88%) 0.026 - P-values result from Fisher's exact test. Open table in a new tab - P-values result from Fisher's exact test.

Modest environmental enrichment: Effect on a radial maze validation and well being of rats

Our 8-arm radial maze test was validated to demonstrate memory deficits in rats treated with the muscarinic antagonist scopolamine hydro bromide (SHB, 0.1 mg/kg, i.p.). To improve quality of life, we enriched the environment of single housing rats. Enrichment procedures were chosen to increase the animals' well being without disturbing a lot the results of behavioural tests. It is modest, consisting of a plastic tube and corn chips. Enriched environment (EE) and Non-enriched Environment (NE) animals' performances were compared during the 8-arms radial maze validation. Enrichment procedures were chosen to increase the animals' well being without disturbing the results of behavioural tests. The impact of our enrichment conditions was then evaluated on the general behaviour of rats, weight evolution and results of a plus maze anxiety test. Results showed a deficit and a delay in learning for SHB-treated animals, and a general time-dependent learning effect, validating our test. No effect of enrichment on negative control animals was observed. For SHB-treated animals, enrichment increased performances during learning task and accentuated the deficits in test task. Exploratory behaviour of enriched animals seemed to be increased. A general amelioration of well being for EE animals was found (stable weight). We conclude that our enrichment allows increasing exploratory behaviour not modifying radial maze sensitivity using a simple modification of our protocol (limitation to 16 visits/trial). We decided to generalise this enrichment to all our studies, given its simplicity and obtained benefits.

Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine.

Minimal measurement error (reliability) during the collection of interval- and ratio-type data is critically important to sports medicine research. The main components of measurement error are systematic bias (e.g. general learning or fatigue effects on the tests) and random error due to biological or mechanical variation. Both error components should be meaningfully quantified for the sports physician to relate the described error to judgements regarding 'analytical goals' (the requirements of the measurement tool for effective practical use) rather than the statistical significance of any reliability indicators. Methods based on correlation coefficients and regression provide an indication of 'relative reliability'. Since these methods are highly influenced by the range of measured values, researchers should be cautious in: (i) concluding acceptable relative reliability even if a correlation is above 0.9; (ii) extrapolating the results of a test-retest correlation to a new sample of individuals involved in an experiment; and (iii) comparing test-retest correlations between different reliability studies. Methods used to describe 'absolute reliability' include the standard error of measurements (SEM), coefficient of variation (CV) and limits of agreement (LOA). These statistics are more appropriate for comparing reliability between different measurement tools in different studies. They can be used in multiple retest studies from ANOVA procedures, help predict the magnitude of a 'real' change in individual athletes and be employed to estimate statistical power for a repeated-measures experiment. These methods vary considerably in the way they are calculated and their use also assumes the presence (CV) or absence (SEM) of heteroscedasticity. Most methods of calculating SEM and CV represent approximately 68% of the error that is actually present in the repeated measurements for the 'average' individual in the sample. LOA represent the test-retest differences for 95% of a population. The associated Bland-Altman plot shows the measurement error schematically and helps to identify the presence of heteroscedasticity. If there is evidence of heteroscedasticity or non-normality, one should logarithmically transform the data and quote the bias and random error as ratios. This allows simple comparisons of reliability across different measurement tools. It is recommended that sports clinicians and researchers should cite and interpret a number of statistical methods for assessing reliability. We encourage the inclusion of the LOA method, especially the exploration of heteroscedasticity that is inherent in this analysis. We also stress the importance of relating the results of any reliability statistic to 'analytical goals' in sports medicine.

Process-oriented instruction in learning and thinking strategies

Process-oriented instruction is defined as instruction aimed at teaching thinking strategies and domain-specific knowledge in coherence. This new conception of instruction is derived from psychological research on the way students learn and on the interplay between self-regulation and external regulation of learning. In the research reported here the learning effects of a process-oriented instructional program for university students were empirically studied. The instructional program consisted of a diagnostic learning style instrument, a learning guide and tutorials. The results showed that the majority of students reported significant general, knowledge, insight and application learning effects. The program effects were typified more by integrating and making usable metacognitive knowledge already present, than by increasing knowledge about new subjects. Evidence for transfer effects was obtained because participants in the program scored better than non-participants on two exams of another course. The learning effects were higher than the effects of an preliminary version of the program implemented with students from an open university. These results support the importance of the process-oriented instructional model. The linking of a thorough diagnosis of personal learning styles to individually tailored instructional measures, turned out to be a powerful way to activate students to reflect on their learning and to develop their mental models of learning.

Effects of different training conditions in the acquisition of a handwriting task

The present article reports a handwriting experiment on the learning of four Arabic letters, by novice writers of Arabic script. One group of subjects, called copiers, copied the experimental graphemes from a visual presentation which remained present during the full course of task execution. The other group, called planners, was forced into a mental planning stage. In this group, stimulus presentation was ended before task execution started. The experiment was subdivided in three consecutive stages: pretest, training stage and posttest. General effects of practice were measured by the comparison of means of reaction time, movement time and writing dysfluency in a pre- and posttest, in which both training groups performed the same graphemes with identical copying conditions. In order to reveal differential practice effects as a function of training technique, the relation was analyzed between reaction time and movement time of an initial segment. A general learning effect was expressed in the decrease of movement time and writing dysfluency. This decrease, however, was significantly less in the first writing segment than in subsequent segments. In the training stage, effects of practice were measured by analyzing the trade off between simple reaction time and movement time as a function of consecutive trials. The analyses revealed a differential effect of practice on this trade off for the two training groups. The results are discussed from a theoretical, cognitive viewpoint, which defends that the learning process can be characterized by the advanced preparation of increasingly larger and more abstract chunks, during the reaction time phase of a task. Simultaneously, the amount of on-line processing of more detailed motor instructions, during real-time execution, increases as a result of practice.

Cortical lesions: flavor illness and noise-shock conditioning

We studied the effects of neocortical lesions in rats upon (a) aversive conditioning where a flavor is paired with a subsequent illness, and (b) aversive conditioning where a noise is followed by a foot shock. Lesions of the anterior cortex produced deficits in both paradigms, regardless of whether the gustatory cortex was damaged or spared. Lesion size was more important than location for taste aversion acquisition. Gustatory cortical lesions, as well as other cortical lesions, produced “intersession memory” deficits between training days in the noise-shock paradigm. Within sessions, the acquisition slopes were similar for control and lesioned rats. These data favor a general learning effect for any anterior cortical lesion rather than a specific effect of gustatory lesions on flavor-illness conditioning.