Robust Design and Professional Services: A Hospital Emergency Room Case

ABSTRACT

This article describes what we believe is a new application of robust design methods. This study challenges the paradigm that robust design does not apply to services. We used a simple robust design approach to optimize the processes of a hospital emergency room. Results show a 25% reduction in average patient length of stay (LOS) without major capital investment for an expanded facility. Confirmation runs showed excellent repeatability. The greatest challenge was helping the team accept and implement the results, thus improving quality without larger staffs, facilities, and budgets. This study suggests that robust design methods can be used to optimize processes outside the product development arena.     

An examination of the mediating role of psychological empowerment on the relations between the job, interpersonal relationships, and work outcomes.

A field investigation of 337 employees and their immediate superiors tested the mediating role of empowerment in relations between job characteristics, leader–member exchange (LMX), team–member exchange (TMX), and work outcomes. The meaning and competence dimensions of empowerment mediated the relation between job characteristics and work satisfaction. The meaning dimension also mediated the relation between job characteristics and organizational commitment. Contrary to prediction, empowerment did not mediate relations between LMX, TMX, and the outcome variables. Rather, LMX and TMX were directly related to organizational commitment. In addition, TMX was directly related to job performance. These findings suggest that work satisfaction is explained largely by job characteristics (through empowerment) but that LMX and TMX combine with job characteristics and empowerment to explain variation in organizational commitment and job performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In vitro approaches to estimate the effect of food processing on carotenoid bioavailability need thorough understanding of process induced microstructural changes

Carotenoids represent an example of micronutrients for which processing-induced food structure changes (e.g., matrix disruption) strongly influence their bioavailability. The available scientific information on this topic resulting from both in vivo and in vitro studies shows however the complexity of this problem. Although in vitro studies have been shown useful to better understand the relation between processing and carotenoid bioavailability, there is still conflicting information. To expand our current knowledge on this topic in order to allow rational design of food processing solutions resulting in products with maximal carotenoid accessibility and (bio)availability, it is suggested (i) to further evaluate and standardize in vitro models to be used as high throughput screening tools to determine the effect of extrinsic (process-related) and intrinsic (product-related) factors and (ii) to integrate food structure information as a useful approach for understanding and quantifying the bioavailability of carotenoids in foods. However, it will be necessary to validate the information obtained from these in vitro methods thoroughly against human studies (in vivo studies).     

Coloring inductive graphs on-line

In this paper we consider the problem of on-line graph coloring. In an instance of on-line graph coloring, the nodes are presented one at a time. As each node is presented, its edges to previously presented nodes are also given. Each node must be assigned a color, different from the colors of its neighbors, before the next node is given. LetA(G) be the number of colors used by algorithmA on a graphG and letx(G) be the chromatic number ofG. The performance ratio of an on-line graph coloring algorithm for a class of graphsC is max_{G C(A(G)/(G))}. We consider the class ofd-inductive graphs. A graphG isd-inductive if the nodes ofG can be numbered so that each node has at mostd edges to higher-numbered nodes. In particular, planar graphs are 5-inductive, and chordal graphs arex(G)-inductive. First Fit is the algorithm that assigns each node the lowest-numbered color possible. We show that ifG isd-inductive, then First Fit usesO(d logn) colors onG. This yields an upper bound ofo(logn) on the performance ratio of First Fit on chordal and planar graphs. First Fit does as well as any on-line algorithm ford-inductive graphs: we show that, for anyd and any on-line graph coloring algorithmA, there is ad-inductive graph that forcesA to use (d logn) colors to colorG. We also examine on-line graph coloring with lookahead. An algorithm is on-line with lookaheadl, if it must color nodei after examining only the firstl+i nodes. We show that, forl/logn, the lower bound ofd logn colors still holds.This research was supported by an IBM Graduate Fellowship.     

Progress towards ultrasound applications of new single crystal materials

In recent years, single crystal materials with better piezoelectric properties than the existing ceramics have become available. These new materials will potentially provide improved performance in ultrasonic applications such as NDT, sonar and biomedical diagnosis. In order to select the best material and optimize transducer design, comparison must be carried out. However, due to material and transducer fabrication costs, initial comparisons can be based on simulation. In this paper, a comparison is reported between transducers based on the single crystal lead magnesium niobate-lead titanate (PMN-32% PT) and the ceramic lead zirconate titanate (PZT-5H). Material performance is assessed both for single materials and piezoelectric-polymer composite configurations by defining the relevant piezoelectric parameters. Furthermore, the effect of such parameters on the performance of different ultrasonic transducers is illustrated. Practical limitations are also discussed. We conclude that the new single crystal material will be capable of outperforming the present widely used ceramic for almost all practical applications.     

Comparison of species sensitivity distributions derived from interspecies correlation models to distributions used to derive water quality criteria

Species sensitivity distributions (SSD) require a large number of measured toxicity values to define a hazard level protective of multiple species. This investigation comprehensively evaluated the accuracy of SSDs generated from toxicity values predicted from interspecies correlation estimation (ICE) models. ICE models are log-log correlations of multiple chemical toxicity values for a pair of species that allow the toxicity of multiple species to be predicted from a single measured acute toxicity value for a surrogate species. ICE SSDs were generated using four surrogate species (fathead minnow, Pimephales promelas; rainbow trout, Oncorhynchus mykiss; sheepshead minnow, Cyprinodon varigatus; and water flea, Daphnia magna). ICE-based hazard concentrations (HC5s) from the 5th percentile of the log-logistic distribution of toxicity values were compared to HC5s determined from the acute toxicity of 55 chemicals from the United States Environmental Protection Agency Ambient Water Quality Criteria (AWQC). Measured fish and invertebrate acute toxicity data and HC5s from the AWQC data sets were compared to ICE-based HC5s. Surrogate species choice was found to be an important consideration in developing predictive HC5s. These results illustrated that fish predict fish betterthan invertebrates and D. magna predicted invertebrates better than most fish. For example, a mixed model of predicted fish and invertebrates from fathead minnow and D. magna as surrogate species provided predictive relationships with an average factor of 3.0 (+/- 6.7) over 7 orders of toxic magnitude and several chemical classes (HC5(predicted)/HC5(measured)). The application of ICE models is recommended as a valid approach for generating SSDs and hazard concentrations for chemicals with limited toxicity data.     

Use of pectinmethylesterase and calcium in osmotic dehydration and osmodehydrofreezing of strawberries

Strawberry samples of two varieties (Camarosa and Elsanta) were dehydrated using different osmotic solutions (60% glucose, fructose, sucrose and raftilose) and subsequently frozen by rapid and high-pressure shift freezing (HPSF). The effect of pectinmethylesterase (PME) and calcium (Ca⁺⁺) added to the osmotic solutions on several compositional parameters and the textural/structural quality of dehydrated and osmodehydrofrozen-then-thawed samples was studied. Due to the presence of PME and Ca⁺⁺ in the osmotic solutions, weight reduction upon dehydration was slightly decreased, which was correlated to a small positive effect on the net uptake of sugars and depression of the initial freezing point. Except for the Camarosa samples treated with sucrose, PME and Ca⁺⁺ in osmotic sugar solutions positively affected the relative hardness of dehydrated fruits, which was ascribed to the effect of PME and Ca⁺⁺ on the cell wall strength of the tissue. No cell wall damage and tissue particle alterations were observed upon dehydration. The effect of osmotic dehydration (OD) using different sugar solutions without PME and Ca⁺⁺ on the texture and structure of frozen-then-thawed samples was limited and sometimes negative. The added PME and Ca⁺⁺ however positively influenced the volume and shape of the thawed samples, which could be related to slightly higher relative hardness values and, for the Elsanta strawberry fruits, also to the reduced (up to 81%) drip loss upon thawing. Upon freezing the dehydrated fruits, no cell wall disruption was observed. Tissue distortion caused by freezing and indicated by a decrease in particle size, convexity and roundness, was compensated by the use of PME and Ca⁺⁺ during OD.