bluuebunny/crossref_metadata_2025 huggingface dataset:
The growth hormone-dependent decrease in hepatic fatty acid synthase mRNA is the result of a decrease in gene transcription
Authors: Donkin S S , McNall A D , Swencki B S , Peters J L , Etherton T D
Published: December 2008

The present study was conducted to determine the chronic effects of porcine growth hormone administration on fatty acid synthase (FAS) mRNA abundance and gene transcription in growing rats. Growth hormone treatment increased growth rate approximately 27% (P<0·01). Porcine growth hormone decreased FAS mRNA levels by 55%. The reduction in FAS mRNA was due to a marked decrease in transcription of the FAS gene (decreased by 80%). In contrast, porcine growth hormone did not affect mRNA abundance or transcription rate of another insulin-regulated gene, phosphoenolpyruvate carboxykinase. In summary, our results have established that chronic treatment with growth hormone decreases FAS mRNA by decreasing the transcription rate of the gene. Furthermore, they suggest that the effects of growth hormone are specific and are not mediated by general changes in insulin-responsive gene expression in liver.
Molecular cloning of the cDNAs encoding pituitary glycoprotein hormone α- and gonadotropin IIβ-subunits of the Japanese eel, Anguilla japonica, and increase in their mRNAs during ovarian development induced by injection of chum salmon pituitary homogenate
Authors: Nagae M , Todo T , Gen K , Kato Y , Young G , Adachi S , Yamauchi K
Published: December 2008

cDNAs encoding the glycoprotein hormone α- and gonadotropin (GTH) IIβ-subunits of Japanese eel (Anguilla japonica) pituitary were cloned using the polymerase chain reaction. The nucleotide sequence of the glycoprotein hormone α-subunit cDNA was 364 base pairs (bp) long, encoding 117 amino acids, and that of the GTH IIβ-subunit cDNA was 433 bp long, encoding 140 amino acids. The deduced amino acid sequence of each mature subunit showed high homology with those of other teleosts, indicating that the structure of GTH subunits has been conserved during the evolution of teleosts. Changes in the expression of these subunit genes during ovarian development induced artificially by the injection of chum salmon pituitary homogenate were examined using Northern blot analysis. Glycoprotein hormone α-subunit mRNA increased almost linearly during ovarian development, whereas GTH IIβ-subunit mRNA was detected only at the late vitellogenic and migratory nucleus stages. These data indicate that eel GTH II is synthesized mainly at the late vitellogenic and migratory nucleus stages, and suggest that GTH II plays an important role in final oocyte maturation of Japanese eel. Changes in the expression of glycoprotein hormone α- and GTH IIβ-subunits mRNA correlate with the serum estradiol-17β (E2) and testosterone profile during ovarian development. The increase in mRNA of both subunits is probably due to positive feedback of E2 and testosterone produced by ovarian follicles in response to the GTH contained in chum salmon pituitary homogenate.
Novel and sensitive detection systems for the vitamin D receptor — in situ-reverse transcriptase-polymerase chain reaction and immunogold cytochemistry
Authors: Mee A P , Davenport L K , Hoyland J A , Davies M , Mawer E B
Published: December 2008

The receptor for the active metabolite of vitamin D, 1,25(OH)2D3, known as the vitamin D receptor (VDR), belongs to the steroid hormone nuclear receptor superfamily. We have developed novel methods for detection of VDR mRNA and protein within a human promyelomonocytic cell line, HL-60.

Using the newly developed technique of in situ-reverse transcriptase-polymerase chain reaction (IS-RT-PCR), low levels of VDR mRNA could be amplified and demonstrated unequivocally within these cells, and also within a human kidney proximal tubule cell line, CL-8. Use of a novel immunogold cytochemical technique has allowed clear and sensitive detection of VDR protein expression within the HL-60 cells.

Further development of IS-RT-PCR has allowed us to apply this technique to tissue sections. We have shown clear amplification of VDR transcripts within sections of formalin-fixed paraffin-embedded human kidney and liver.

These techniques will be useful to localise specifically the VDR within cell types that contain low levels of mRNA and protein, and will permit further investigation of the role played by 1,25(OH)2D3 in cellular regulatory mechanisms.
An alternative splice variant of the mouse TRH receptor mRNA is the major form expressed in the mouse pituitary gland
Authors: Jones K E , Brubaker J H , Chin W W
Published: December 2008

The sequences of the mouse and rat TRH receptors (TRH-Rs) show 94% similarity at the protein level. However, they differ significantly at their carboxy terminals, i.e. the mouse TRH-R ends with an asparagine at position 393 while, in the rat, residue 393 is lysine and an additional 19 amino acids are added before the first stop codon. In the mouse cDNA, the sequence encoding these additional amino acids is located 224 bp downstream in the 3′ untranslated region (3′UT). As the mouse TRH-R was cloned from thyrotrope-derived TtT97 tissue and the rat TRH-R from lactotrope-derived GH cell lines, we have investigated whether this difference at the carboxyterminus represents a species-specific or cell type-specific pattern of TRH-R expression. Total RNA was isolated from mouse pituitary and TtT97 tissue, and rat pituitary and GH3 cells. Reverse transcription PCR analysis was performed using primers that would generate DNA fragments including the stop codon in either the mouse or the rat TRH-R and, in the mouse form, the extra 224 bp of 3′UT. This would generate a product of 234 bp from the rat sequence and 441 bp from the mouse sequence. In rat pituitary and GH3 cDNA, PCR generated the expected 234 bp product but not a band representing the mouse sequence. In both mouse pituitary and TtT97 cDNA, neither the expected 441 bp nor the 234 bp fragments were amplified; instead a larger, 829 bp, product was generated. Sequence analysis revealed a 388 bp insertion at position 1663 in the 3′UT compared with the published mouse TRH-R sequence. Ribonuclease protection analysis using this 829 bp fragment as a probe showed that this sequence represented the major TRH-R mRNA species in mouse pituitary and TtT97 RNA. A genomic clone containing this region of the mouse TRH-R gene was isolated and analysis of the sequence in this region revealed that this longer form of the mouse TRH-R could be generated by alternative splicing.

In summary, we have shown that the carboxyterminal differences between the mouse and rat TRH-Rs are species-specific rather than cell typespecific, and that the major TRH-R mRNA expressed in mouse pituitary contains an additional 388 bp of 3′UT compared with the published sequence. As a region in the 3′UT of the published mTRH-R sequence has been shown to be important for stability of this mRNA, this additional 3′UT sequence could have major effects on the regulation and stability of the mouse TRH-R mRNA.
Selenoenzyme expression in thyroid and liver of second generation selenium- and iodine-deficient rats
Authors: Mitchell J H , Nicol F , Beckett G J , Arthur J R
Published: December 2008

The stimulation of thyroid hormone synthesis in iodine deficiency may increase the requirement for the selenoproteins which are involved in thyroid hormone synthesis in the thyroid gland. Selenoenzyme activity and expression were investigated in the thyroid and liver of second generation selenium-and/or iodine-deficient rats. Selenium deficiency caused substantial decreases in hepatic seleniumcontaining type I iodothyronine deiodinase (ID-I) and cytosolic glutathione peroxidase (cGSHPx) activities and mRNA abundances, but phospholipid hydroperoxide glutathione peroxidase (phGSHPx) activity was only 55% of selenium-supplemented control levels, despite the absence of change in its mRNA abundance. Selenoenzyme mRNA concentrations were maintained at control levels in thyroid glands from the selenium-deficient rat pups. Despite this, a differential effect was observed in selenoenzyme activities: ID-I activity was decreased to 61%, cGSHPx activity to 45% and phGSHPx to 29% of that in selenium-adequate controls. In iodine-deficient thyroid glands, mRNA levels were increased 2·2, 50 and 2·8 times for ID-I, cGSHPx and phGSHPx respectively. ID-I and cGSHPx enzyme activities were also increased but the activity of phGSHPx was decreased despite the high mRNA abundance. Thyroid selenoprotein mRNA levels were also increased in combined selenium and iodine deficiency but again there were differential effects on enzyme activities, with ID-I activity increased, cGSHPx unchanged and phGSHPx decreased. Thus, iodine deficiency may produce an oxidant stress on the thyroid gland, increasing the requirement for selenium to maintain selenoenzyme activity. When dietary supplies of selenium are limiting, thyroid selenoprotein mRNA levels are increased to compensate for overall lack of the micronutrient. Furthermore, there is a preferential supply of available selenium to ID-I and cGSHPx to allow maintenance of thyroid function.
Regulation of 11β-hydroxysteroid dehydrogenase type 2 activity and mRNA in human choriocarcinoma cells
Authors: Pasquarette M M , Stewart P M , Ricketts M L , Imaishi K , Mason J I
Published: December 2008

The type 2 isoform of 11 β-hydroxysteroid dehydrogenase (11β-HSD2), which catalyzes the conversion of cortisol to hormonally inactive cortisone in man, is principally expressed in the placenta and mineralocorticoid target tissues, kidney and colon. To date, few studies have addressed the regulation of this novel 11β-HSD2 isoform. We have characterized the nature and regulation of the 11β-HSD activity expressed in a human cytotrophoblastic cell line, the JEG-3 choriocarcinoma cell. The 11β-HSD activity in JEG-3 cell homogenates required NAD+ as cofactor with NADP ineffective and demonstrated a high affinity for cortisol (apparent Km 31 nm). Incubation of JEG-3 cells with forskolin and dibutyryl cyclic AMP increased 11β-HSD2 activity several-fold in a time-dependent manner, while treatment with phorbol ester had little, if any, effect on 11β-HSD2 activity. Northern blot analysis of RNA isolated from JEG-3 cells after these treatments demonstrated a marked increase in a 1·9 kb 11β-HSD2 mRNA species in cells treated with forskolin for 24 h. We conclude that 11β-HSD2 is regulated by activation of the protein kinase A pathway, but not the protein kinase C pathway in human choriocarcinoma cells, and that this regulation occurs at a pretranslational level. JEG-3 cells provide an excellent model for further studies on the regulation of 11β-HSD2 gene expression in human trophoblast tissue.
Coastal erosion studies on the Capo Colonna cliff, Italy
Authors: Blois L.
Published: December 2008

This study investigated the coastal erosion of Capo Colonna cliff in Calabria, Italy. It included an assessment of multidisciplinary studies concerning coastal processes along the Calabrian coast and presents a description of the mechanisms that triggered the landslide of the Capo Colonna cliff located in the protected marine area of Capo Rizzuto, extending for a length of approximately 4 km and having a total surface area of approximately 135 km2. The study especially focused on the effects of the phenomenon of coastal erosion of the cliff and proposes some possible interventions for the rehabilitation of this coastline.
Reducing Management’s Influence on Auditors’ Judgments: An Experimental Investigation of SOX 404 Assessments
Authors: Earley Christine E. , Hoffman Vicky B. , Joe Jennifer R.
Published: December 2008

ABSTRACT: Auditors often receive summary information or conclusions from management about account balances or internal controls. They must then gather evidence to assess whether this information is fairly stated. In such situations, management can be considered the “first mover” and the auditor the “second mover.” When auditors are the second mover, they are vulnerable to the curse of knowledge bias—the inability to ignore previously processed information (Fischhoff 1977). Specifically, because information from management could be incorrect or biased, auditors must arrive at an independent evaluation of the item in question (e.g., year-end book values, accounting estimates, or internal controls). This study examines the general issue of auditors being “second movers” by investigating how their awareness of management’s severity classifications of internal control problems influences auditors’ initial assessments of internal control over financial reporting (ICFR) under Auditing Standard No. 2. Our experimental design allows us to determine that management’s “first mover” influence on auditors’ judgments is an unintentional cognitive effect, rather than an intentional use of management’s classifications. We further examine whether cognitively restructuring the ICFR assessment task reduces management’s influence on auditors’ judgments by asking auditors to evaluate and explicitly document the likelihood and magnitude of the effect of an ICFR problem on the financial statements. We find that cognitively restructuring the task mitigates management’s “first mover” influence on auditors’ judgments.
The Importance of Distinguishing Errors from Irregularities in Restatement Research: The Case of Restatements and CEO/CFO Turnover
Authors: Hennes Karen M. , Leone Andrew J. , Miller Brian P.
Published: December 2008

ABSTRACT: Research on restatements has grown significantly in recent years. Many of these studies test hypotheses about the causes and consequences of intentional managerial misreporting but rely on restatement data (such as the GAO database) that contains both irregularities (intentional misstatements) and errors (unintentional misstatements). We argue that researchers can significantly enhance the power of tests related to restatements by distinguishing between errors and irregularities, particularly in recent periods when the relative frequency of error-related restatements is increasing. Based on prior research, the reading of numerous restatement announcements, and the guidance that boards receive from lawyers, auditors, and the SEC on how to respond to suspicions of deliberate misreporting, we propose a straightforward procedure for classifying restatements as either errors or irregularities. We show that most of the restatements we classify as irregularities are followed by fraud-related class action lawsuits as compared to only one lawsuit in the group of restatements classified as errors. As further validation of our proxy, we report that the market reaction to the restatement announcement for our irregularities sample (−14 percent) is also significantly more negative than it is for our errors sample (−2 percent). Finally, we demonstrate the importance of distinguishing errors from irregularities by showing the impact it has on inferences about the relation between restatements and CEO/CFO turnover over time.
Non-linear electrooptic effect in antiferroelectric liquid crystal
Authors: Dardas D. , Kuczyński W. , Hoffmann J. , Jeżewski W. , Nowicka K. , Małecki J.
Published: December 2008

Electrooptic phenomena caused by weak electric fields, much lower than those needed for the helix unwinding, in helical smectic liquid crystals were studied in thin planar samples. The investigations were performed in chiral liquid crystal 4-(1-methyl-heptyloxycarbonyl) phenyl 4′-(3-butanoyloxy propyl-1-oxy) biphenyl-4-carboxylate which exhibits antiferro-electric properties. We have found that electric field applied to a helical smectic liquid crystal caused two effects. First, the helix was deformed and the position of effective optic axis changed by an angle proportional to the field strength. The second effect, quadratic in field, causes the change in the shape of the indicatrix. As a consequence, the relative changes in the light intensity caused by external electric field consist of two components. The first component represents the modulation with the fundamental frequency and the second one with the doubled frequency (second harmonic of the electrooptic effect). The ab- solute values of the first- and second-order electrooptic coefficients have been determined and their temperature dependence discussed.
Mesomorphic and dielectric properties of esters useful for formulation of nematic mixtures for dual frequency addressing system
Authors: Ziobro D. , Kula P. , Dziaduszek J. , Filipowicz M. , DĄbrowski R. , Parka J. , Czub J. , Urban S. , Wu S.T.
Published: December 2008

Mesomorphic and dielectric properties of three homologous series of two and three ring fluorosubstituted esters are described. They are 4-cyano-3-fluorophenyl 4-alkyloxy-2-fluorobenzoates, 4-cyano-3-fluorophenyl 4-(4-alkylbenzoyloxy)-2-fluorobenzoates and 3-fluoro-4-cyanophenyl, or 3-fluoro-4-isothiocyanatophenyl or 3,4-difluorophenyl 4′-alkyl-2,3-difluoro-biphenyl-4-carboxylates. The compounds exhibit the nematic mesophase accompanied by the smectic A or smectic C mesophase in some cases. Most of them show strong dependence of the dielectric anisotropy Δε upon frequency, at low frequencies Δε reaches a value ∼200, while at high frequencies a small negative dielectric anisotropy appears.
Preparation and characterization of transparent Nd:YAG ceramics
Authors: Librant Z. , Jabczyński J.K. , Węglarz H. , Wajler A. , Tomaszewski H. , Łukasiewicz T. , Żendzian W. , Kwiatkowski J.
Published: December 2008

Transparent Nd:YAG ceramics were produced by solid.state reaction of high.purity (4N) nanometric oxides powders, i.e., Al2O3, Y2O3 and Nd2O3. After sintering, mean grain sizes of 2% Nd:YAG samples were about 20 μm and their transparency were a bit worse than that of 0.9% Nd:YAG single crystal. Two types of active elements: rods and slabs were fabricated and characterized in several diode pumping schemes. In end pumping configuration as a pump source 20.W fiber coupled laser diode operating in low duty cycle regime (1 ms pump duration/20 Hz) was deployed. In the best case, 3.7 W of output power for 18 W of absorbed pump power, M2 < 1.4 were demonstrated for uncoated ceramics Nd:YAG rod of ϕ 4×3mm size in preliminary experiments. For the ceramics of two times lower Nd dopant level above 30% slope efficiency was achieved. In case of Nd:YAG ceramic slab side pumped by 600.W laser diode stack above 12 W was demonstrated with slope efficiency of 3.5%.
Cigarette Smoking among Adolescents in Northwest Ohio: Correlates of Prevalence and Age at Onset
Authors: Khuder Sadik  A. , Price James  H. , Jordan Timothy , Khuder Saja  S. , Silvestri Kathi
Published: December 2008

This study examined the prevalence and correlates of smoking initiation among adolescents. We have used data from adolescents (n=5,392) ages 10-18 who participated in the 2003 Tobacco Survey, a representative sample of adolescents in Northwest Ohio. A selfreport of cigarette smoking was obtained using a questionnaire administered in classrooms. Data were analyzed using weighted chi-square and multiple logistic regressions in SAS that accounted for the survey design. The prevalence rates for adolescents that ever tried smoking were 7.4% in elementary (grades 4-5); 17.7% in middle (grades 6-8), and 41.4% in high (grades 9-12) schools, respectively. The highest prevalence rate was among Hispanics. Having a close friend that smoked and a smoker at home correlated significantly with both initiation of smoking and smoking at an earlier age. Smoking was correlated with low academic achievement among adolescents in all grades. Students who reported smoking by parents or siblings were significantly more likely to start smoking at an earlier age, compared to other students living in a non-smoking home environment. Smoking prevention program should include components focused on adolescents’ home environment and should start as early as the 4th grade.
24-O-Ethylmanoalide, a Manoalide-related Sesterterpene from the Marine sponge Luffariella cf. variabilis
Authors: Gauvin-Bialecki Anne , Aknin Maurice , Smadja Jacqueline
Published: December 2008

A new manoalide-related sesterterpene, 24-O-ethylmanoalide (3), was isolated from the Indian Ocean sponge Luffariella cf. variabilis, together with the known compounds manoalide (1), seco-manoalide, manoalide monoacetate and 24-O-methylmanoalide (2). The structure of compound 3 was elucidated by interpretation of its spectroscopic data.
Electrochemical Immunosensor Based on Polythionine/Gold Nanoparticles for the Determination of Aflatoxin B1
Authors: Owino Joseph  H.O. , Arotiba Omotayo  A. , Hendricks Nicolette , Songa Everlyne  A. , Jahed Nazeem , Waryo Tesfaye  T. , Ngece Rachel  F. , Baker Priscilla  G .L. , Iwuoha Emmanuel I.
Published: December 2008

An aflatoxin B1 (AFB1) electrochemical immunosensor was developed by the immobilisation of aflatoxin B1-bovine serum albumin (AFB1-BSA) conjugate on a polythionine (PTH)/gold nanoparticles (AuNP)-modified glassy carbon electrode (GCE). The surface of the AFB1-BSA conjugate was covered with horseradish peroxidase (HRP), in order to prevent non-specific binding of the immunosensors with ions in the test solution. The AFB1 immunosensor exhibited a quasi-reversible electrochemistry as indicated by a cyclic voltammetric (CV) peak separation (ΔEp) value of 62 mV. The experimental procedure for the detection of AFB1 involved the setting up of a competition between free AFB1 and the immobilised AFB1-BSA conjugate for the binding sites of free anti-aflatoxin B1 (anti-AFB1) antibody. The immunosensor’s differential pulse voltammetry (DPV) responses (peak currents) decreased as the concentration of free AFB1 increased within a dynamic linear range (DLR) of 0.6 - 2.4 ng/mL AFB1 and a limit of detection (LOD) of 0.07 ng/mL AFB1. This immunosensing procedure eliminates the need for enzyme-labeled secondary antibodies normally used in conventional ELISA–based immunosensors.
Na+,K+-ATPase as the Target Enzyme for Organic and Inorganic Compounds
Authors: Vasić Vesna , Momić Tatjana , Petković Marijana , Krstić Danijela
Published: December 2008

This paper gives an overview of the literature data concerning specific and non specific inhibitors of Na+,K+-ATPase receptor. The immobilization approaches developed to improve the rather low time and temperature stability of Na+,K+-ATPase, as well to preserve the enzyme properties were overviewed. The functional immobilization of Na+,K+-ATPase receptor as the target, with preservation of the full functional protein activity and access of various substances to an optimum number of binding sites under controlled conditions in the combination with high sensitive technology for the detection of enzyme activity is the basis for application of this enzyme in medical, pharmaceutical and environmental research.
Array Biosensor for Toxin Detection: Continued Advances
Authors: Taitt Chris Rowe , Shriver-Lake Lisa C. , Ngundi Miriam M. , Ligler Frances S.
Published: December 2008

The following review focuses on progress made in the last five years with the NRL Array Biosensor, a portable instrument for rapid and simultaneous detection of multiple targets. Since 2003, the Array Biosensor has been automated and miniaturized for operation at the point-of-use. The Array Biosensor has also been used to demonstrate (1) quantitative immunoassays against an expanded number of toxins and toxin indicators in food and clinical fluids, and (2) the efficacy of semi-selective molecules as alternative recognition moieties. Blind trials, with unknown samples in a variety of matrices, have demonstrated the versatility, sensitivity, and reliability of the automated system.
Contracting Under Vendor Managed Inventory Systems Using Holding Cost Subsidies
Authors: Nagarajan Mahesh , Rajagopalan S.
Published: December 2008

Vendor managed inventory systems are becoming increasingly popular. An important issue in implementing a vendor managed inventory scheme is the contracting terms that dictate the ownership of the inventory and the responsibility of inventory replenishment decisions. Thus the performance of a vendor managed system crucially depends on these terms and on how inventory‐related costs are shared in a supply chain. We consider a system where a manufacturer supplies a single product to a retailer who faces random demand in a competitive market. The retailer incurs a fixed cost per order, inventory holding cost, and a penalty cost for a stockout (unsatisfied demand is back‐ordered). Further, the manufacturer incurs a penalty cost when there is a stockout at the retailer and a fixed replenishment cost. We assume that the players are rational and act noncooperatively. We compare the performance of retailer managed inventory systems, where the retailer places orders and makes replenishment decisions, with vendor managed inventory systems, wherein the vendor or manufacturer makes inventory and replenishment decisions. Specifically, in the vendor managed inventory system, we propose and evaluate holding cost subsidy‐type contracts on inventories offered by the retailer to improve system performance. We evaluate this contract in the context of three widely used inventory systems—deterministic economic order quantity, continuous review ( Q, r) policies, and periodic review policies—and show when such contracts may improve channel performance.
Asymmetric Competition in B2B Spot Markets
Authors: Etzion Hila , Pinker Edieal J.
Published: December 2008

We model strategic behavior of two types of suppliers in B2B spot markets: a supplier that has forward contracts and uses the spot market only for inventory liquidation, and a supplier that uses the spot market as its sole selling channel. We find that when the spot market demand is small, the supplier that has forward contracts has a higher incentive to invest in expanding the spot market. When the spot market demand exceeds a threshold size, this situation is reversed, and the supplier with no contracts benefits more from making the spot market more prevalent. We show that a supplier with forward contracts benefits from the existence of the spot market more than a supplier with no contracts and that this result holds with both negative and positive correlation between spot market demand and contracted demand. We find that suppliers producing only for the spot market gain from working in industries where contracted demand and spot market demand are positively correlated, whereas suppliers that have forward contracts benefit from working in industries with a negative correlation between demands, since it allows them to better manage risk. In addition, both total industry supply and spot market supply are higher in industries where demands are negatively correlated.
Route‐Independent Analysis of Available Capacity in Flexible Manufacturing Systems
Authors: Koltai Tamás , Stecke Kathryn E.
Published: December 2008

In a job shop, because of large setup times, each operation is assigned to only one machine. There is no alternative routing. In a flexible manufacturing system, each manufacturing operation can often be performed on several machines. Therefore, with automated equipment, the capacity of a machine to perform certain operations is not independent of the capacity of other machines. Often, however, operations managers can use a route‐independent answer to production planning questions. For example, how much can be produced of a certain part type and when are important capacity questions in business negotiations, when the detailed routing and scheduling are not yet of interest or cannot be known.

This paper provides a mathematical model for the route‐independent analysis of the capacity of flexible manufacturing systems based on a concept of operation types. An example is provided both to illustrate the use of operation types and to highlight the differences between the traditional route‐dependent and the proposed route‐independent formulations of capacity constraints. Some computational results are also given. Finally, a sensitivity analysis is developed to analyze the feasibility of production plans when production requirements and machine capacities can change.
Application Development Using Fault Data
Authors: Feng Qi , Mookerjee Vijay S. , Sethi Suresh P.
Published: December 2008

We develop a general model for software development process and propose a policy to manage system coordination using system fault reports (e.g., interface inconsistencies, parameter mismatches, etc.). These reports are used to determine the timing of coordination activities that remove faults. We show that under an optimal policy, coordination should be performed only if a “threshold” fault count has been exceeded. We apply the policy to software development processes and compare the management of those projects under different development conditions. A series of numerical experiments are conducted to demonstrate how the fault threshold policy needs to be adjusted to changes in system complexity, team skill, development environment, and project schedule. Moreover, we compare the optimal fault threshold policy to an optimal release‐based policy. The release‐based policy does not take into account fault data and is easier to administer. The comparisons help to define the range of project parameters for which observing fault data can provide significant benefits for managing a software project.
System Dynamics as a Structural Theory in Operations Management
Authors: Größler Andreas , Thun Jörn‐Henrik , Milling Peter M.
Published: December 2008

The purpose of the paper is to demonstrate the usefulness of (1) system dynamics as a structural theory for operations management and (2) system dynamics models as content theories in operations management. The key findings are that, although feedback loops, accumulation processes, and delays exist and are widespread in operations management, often these phenomena are ignored completely or not considered appropriately. Hence, it is reasoned why system dynamics is well suited as an approach for many operations management studies, and it is shown how system dynamics theory can be used to explain, analyze, and understand such phenomena in operations management. The discussion is based on a literature review and on conceptual considerations, with examples of operations management studies based on system dynamics. Implications of using this theory include the necessary re‐framing of some operations management issues and the extension of empirical studies by dynamic modeling and simulation. The value of the paper lies in the conceptualization of the link between system dynamics and operations management, which is discussed on the level of theory.
Service Coproduction with Information Stickiness and Incomplete Contracts: Implications for Consulting Services Design
Authors: Xue Mei , Field Joy M.
Published: December 2008

Drawing from three theoretical bases—“information stickiness” from the knowledge management literature, “service coproduction” from the service operations management literature, and “incomplete contract theory” from the transaction cost economics literature—we discuss a theoretical framework and develop models to study the efficiency of the service coproduction process in a knowledge‐intensive consulting environment. We apply, refine, and interpret these theories to determine how work should be allocated between the consultant and the client and the corresponding pricing under different contractual relationships that occur in this industry. We find that, with a pricing schedule that relates the fee adjustment to the self‐service level and one party's ownership of the residual right to specify the workload allocation, the client underinvests her efforts in the service coproduction process, whereas the consultant overinvests his efforts, resulting in an inefficient process. In addition, to improve overall process efficiency, we show that the more productive party should own the residual right to respecify the self‐service level when the final service need emerges. Our results, as well as interview data from experienced consultants, provide insights into the causes of inefficient service delivery processes and offer direction for achieving better efficiency through contract design and pricing schedules.
Introduction to the Special Issue on Theory Development in Operations Management
Authors: Schroeder Roger G.
Published: December 2008

Rigorous development of theory in operations management has been lacking. Although many theories have been proposed, they are often not developed in a format and depth that can be falsified, refined, or supported. This special issue includes three papers that illustrate rigorous development of theory for future testing using mathematical, simulation, or managerial approaches.
The Emergence of Service Science: Toward Systematic Service Innovations to Accelerate Co‐Creation of Value
Authors: Spohrer Jim , Maglio Paul P.
Published: December 2008

The current growth of the service sector in global economies is unparalleled in human history—by scale and speed of labor migration. Even large manufacturing firms are seeing dramatic shifts in percent revenue derived from services. The need for service innovations to fuel further economic growth and to raise the quality and productivity levels of services has never been greater. Services are moving to center stage in the global arena, especially knowledge‐intensive business services aimed at business performance transformation. One challenge to systematic service innovation is the interdisciplinary nature of service, integrating technology, business, social, and client (demand) innovations. This paper describes the emergence of service science, a new interdisciplinary area of study that aims to address the challenge of becoming more systematic about innovating in service.
To Pool or Not to Pool in Call Centers
Authors: vanDijk Nico M. , van derSluis Erik
Published: December 2008

Should service capacities (such as agent groups in call centers) be pooled or not? This paper will show that there is no single answer. For the simple but generic situation of two (strictly pooled or unpooled) server groups, it will provide (1) insights and approximate formulae, (2) numerical support, and (3) general conclusions for the waiting‐time effect of pooling. For a single call type, this effect is clearly positive, as represented by a pooling factor. With multiple job types, however, the effect is determined by both a pooling and a mix factor. Due to the mix factor, this effect might even be negative. In this case, it is also numerically illustrated that an improvement of both the unpooled and the strictly pooled scenario can be achieved by simple overflow or threshold scenarios. The results are of both practical and theoretical interest: practical for awareness of this negative effect, the numerical orders, and practical scenarios in call centers, and theoretical for further research in more complex situations.
Operations in the Service Industries: Introduction to the Special Issue
Authors: Apte Uday , Maglaras Costis , Pinedo Michael
Published: December 2008

This special issue of Production and Operations Management offers a sample of ongoing research that focuses currently on the services industries. The articles selected cover a spectrum of application areas as well as methodologies.
Optimizing the Staffing and Routing of Small‐Size Hierarchical Call Centers
Authors: Chevalier Philippe , Van denSchrieck Jean‐Christophe
Published: December 2008

Multiple‐skill call centers propagate rapidly with the development of telecommunications. An abundance of literature has already been published on call centers. Here, we want to focus on centers that would typically occur in business‐to‐business environments; these are call centers that handle many types of calls but where the arrival rate for each type is low. To find an optimal configuration, the integrality of the decision variables is a much more important issue than for larger call centers. The present paper proposes an approach that uses elements of combinatorial optimization to find optimal configurations. We develop an approximation method for the evaluation of the service performance. Next, we search for the minimum‐cost configuration subject to service‐level constraints using a branch‐and‐bound algorithm. What is at stake is to find the right balance between gains resulting from the economies of scale of pooling and the higher cost or cross‐trained agents. The article shows that in most cases this method significantly decreases the staffing cost compared with configurations with only cross‐trained or dedicated operators.
New Service Development Competence and Performance: An Empirical Investigation in Retail Banking
Authors: Menor Larry J. , Roth Aleda V.
Published: December 2008

What can service firms do to improve their ability to offer new services? In this paper we argue that new service development success results from building a competence in the management of service development resources and routines. We conceptualize new service development competence as a multidimensional, second‐order latent construct that is represented by a system of four interrelated and complementary dimensions: (1) formalized new service development processes, (2) market acuity, (3) new service development strategy, and (4) information technology use and experience. We hypothesize that the growth of new service development competence is related to improved new service development performance. Using structural equations modeling, we analyze survey data from 166 retail banks and report three key empirical findings. First, we show that the four hypothesized dimensions are statistically significant in defining new service development competence. Second, contrary to conventional wisdom in new product development, we find that formalized processes play a lesser role in the success of new service development compared with the other three dimensions. Instead, market acuity—which captures the firm's ability to see the competitive environment clearly and to anticipate and respond to customers' evolving needs and wants—was the most important new service development competence indicator. Finally, we demonstrate the positive effect of new service development competence on new service development performance and show that new service development competence is also significantly related to business‐level performance. Together, our empirical results suggest that complementary benefits arise from the adoption of a more holistic approach to the management of new service development at the program level.
Assessing Markups, Service Quality, and Product Attributes in Music CDs' Internet Retailing
Authors: Rabinovich Elliot , Maltz Arnold , Sinha Rajiv K.
Published: December 2008

We investigate trade‐offs among markups, service quality, and product attributes across customer, Internet retailer, and wholesaler echelons. Research has documented the reality of retail price dispersion, but little is known about how retail markups, in particular, are related to service quality and product attributes. For example, do Internet retailers deliver superior service in return for high markups? Do product characteristics affect the relationship between service and markups for retailers? To examine these issues, we first developed a model of Internet retail profitability that separates revenues and costs related to sales from other profit sources. This framework allowed us to position our work alongside the extant literature about Internet retailing. Moreover, it led us to synthesize service quality dimensions found in Internet retailing studies. We subsequently developed a critical‐event study based on the profit model and the synthesis of service quality dimensions to delineate service aspects that retailers should emphasize to address buyers' utility. Finally, we collected data from Internet purchases across retailers to isolate markup‐service quality trade‐offs along our delineated service aspects. We find that high markups are associated with superior performance across service quality dimensions. Furthermore, this trade‐off becomes more acutely defined when products with variable popularity are transacted.
Managing Clearance Sales in the Presence of Strategic Customers
Authors: Zhang Dan , Cooper William L.
Published: December 2008

We study the effect of strategic customer behavior on pricing and rationing decisions of a firm selling a single product over two periods. The seller may limit the availability of the product (that is, ration) in the second (clearance) period. Some customers are strategic and respond to the firm's decisions by timing their purchases. When capacity is nonconstraining and the seller has pricing flexibility, we show that rationing in the clearance period cannot improve revenue. However, when prices are fixed in advance, rationing can improve revenue. In the latter case, we conduct a detailed analysis for linear and exponential demand curves and derive explicit expressions for optimal rationing levels. We find that the policy of doing the better of not restricting availability at the clearance price or not offering the product at the clearance price is typically near optimal. Our analysis also suggests that rationing—although sometimes offering considerable benefit over allowing unrestricted availability in the clearance period—may allow the seller to obtain only a small fraction of the optimal revenue when the prices are chosen optimally without rationing. We extend the analysis to cases where the capacity is constraining and obtain similar results.
Dynamic Pricing with Constant Demand Elasticity
Authors: McAfee R. Preston , teVelde Vera
Published: December 2008

The celebrated model of Gallego and van Ryzin is specialized to the case of constant elasticity of demand. A closed form is developed, which has an even simpler form than that arising with exponential demand and which possesses an excellent approximation. In this environment, monopoly is efficient, which means that all the behavior usually attributed to monopoly pricing is actually a consequence of efficient pricing and would arise even in a perfectly competitive environment. If the initial supply is not too large, consumers have no incentive to delay their purchases to get a lower price at the average inventory prevailing at any time.
Strategic Management of Distressed Inventory
Authors: Gallego Guillermo , Phillips Robert , Şahin Özge
Published: December 2008

It is well known that maximizing revenue from a fixed stock of perishable goods may require discounting prices rather than allowing unsold inventory to perish. This behavior is seen in industries ranging from fashion retail to tour packages and baked goods. A number of authors have addressed the markdown management problem in which a seller seeks to determine the optimal sequence of discounts to maximize the revenue from a fixed stock of perishable goods. However, merchants who consistently use markdown policies risk training customers to “wait for the sale.” We investigate models in which the decision to sell inventory at a discount will change the future expectations of customers and hence their buying behavior. We show that, in equilibrium, a single‐price policy is optimal if all consumers are strategic and demand is known to the seller. Relaxing any of these conditions can lead to a situation in which a two‐price markdown policy is optimal. We show using numerical simulation that if customers update their expectations of availability over time, then optimal sales limit policies can evolve in a complex fashion.
Managing Slow‐Moving Perishables in the Grocery Industry
Authors: Ketzenberg Michael , Ferguson Mark E.
Published: December 2008

We address the value of information and value of centralized control in the context of a two‐echelon, serial supply chain with one retailer and one supplier that provide a single perishable product to consumers. Our analysis is relevant for managing slow‐moving perishable products with fixed lot sizes and expiration dates of a week or less. We evaluate two supply chain structures. In the first structure, referred to as decentralized information sharing, the retailer shares its demand, inventory, and ordering policy with the supplier, yet both facilities make their own profit‐maximizing replenishment decisions. In the second structure, centralized control, incentives are aligned and the replenishment decisions are coordinated. The latter supply chain structure corresponds to the industry practices of company‐owned stores or vendor‐managed inventory.

We measure the value of information and value of centralized control as the marginal improvement in expected profits that a supply chain achieves relative to the case when no information is shared and decision making is decentralized. Key assumptions of our model include stochastic demand, lost sales, and fixed order quantities. We establish the importance of information sharing and centralized control in the supply chain and identify conditions under which benefits are realized. As opposed to previous work on the value of information, the major benefit in our setting is driven by the supplier's ability to provide the retailer with fresher product. By isolating the benefit by firm, we show that sharing information is not always Pareto‐improving for both supply chain partners in the decentralized setting.
Coordinating a Supply Chain System with Retailers Under Both Price and Inventory Competition
Authors: Zhao Xuan
Published: December 2008

We investigate a supply chain system with a common supplier selling to downstream retailers who are engaged in both price and inventory competition. We establish the existence and uniqueness of the pure‐strategy Nash equilibrium for the retailer game and study how a supplier can coordinate the system to achieve the best performance. Our main conclusions are as follows: First, a buyback contract can be used to coordinate retailers competing on both price and inventory in a sense that optimal retail prices and inventory levels arise as the Pareto‐dominant equilibrium. With symmetric retailers, the system optimum arises as the unique symmetric equilibrium. Second, the particular type of competition experienced by retailers (price versus inventory competition) affects the characteristics of the contract. Specifically, strong price competition leads to a coordination mechanism with a positive buyback rate, where the supplier subsidizes retailers for leftover inventories; however, strong inventory competition leads to a negative buyback rate, where retailers are punished for overstocking. Using a linear expected demand function, we further explore the impact of system parameters on the coordination contract and the competitive equilibrium. We also find that the performance of the supplier's optimal contract is asymptotic to the system optimal coordination contract as competition becomes fierce.
A SIMPLE APPROACH TO IMPLEMENTING AN ENVIRONMENTAL CONTROL UNIT FOR THE DISABLED
Authors: Su Mu-Chun , Tew Chee-Yuen , Sun Li-Yen , Lu Jun-Yi , Tsai Hsiang-Chih
Published: December 2008

Environmental control units play a role in enabling disabled people to carry out routine and repetitive tasks (e.g. watching TV, making a phone call, etc.) in their home environments. Unfortunately, most commercially available environmental control units are either too expensive or they require the disabled persons' home environments to be remodelled. In this paper we report the development of a low-cost environmental control unit which enables disabled people to control mostly existing consumer electronics with an infrared remote control functionality. Finally, we use a simple scenario to evaluate the performance of the proposed environmental control unit.