bluuebunny/crossref_metadata_2025 huggingface dataset:
Precedence diagramming method: Some unusual characteristics and their implications for project managers
Authors: Wiest Jerome D.
Published: October 2002

The Precedence Diagramming Method, with its activity‐on‐node network and additional precedence relationships, offers an easier and more flexible network approach to modeling large projects than conventional PERT/CPM. But the new relationships (start‐to‐start and finish‐to‐finish constraints) can change some of the basic notions of critical path methodology, including the concept of a critical path itself. Calculations of early and late job start times are affected, along with total slack. Traditional methods of shortening a project by crashing jobs on the critical path can occasionally have anomalous effects. These little‐known characteristics of PDM are discussed, along with their implications for project managers, analysts, and other users of network methodology. Suggestions are made for improving the information available in computer printouts of PDM networks and for avoiding some of the anomalous effects. While PDM improves the project planner's ability to more simply and accurately model large projects, users should be aware of and able to effectively deal with its sometimes peculiar characteristics.
Emergency ambulance location using the contiguous zone search routine
Authors: Fitzsimmons James A. , Srikar Bellur N.
Published: October 2002

This paper reports on a study to select permanent emergency ambulance sites for the city of Austin, Texas. A facility location algorithm referred to as the contiguous zone search routine (CZSR) was developed to capitalize on the availability of a large data base of interzone travel times. This algorithm was coupled to an existing emergency medical system simulation model (CALL) to permit systematic evaluations of system performance directed at improving average response time. This combination of a simulation model and heuristicsearch routine permitted a degree of model realism not available with deterministic location algorithms currently in use. The output from the system simulation provided the city with a rich description of system performance to evaluate the desirability of locations selected by the heuristic search routine and a set of joint use sites selected by the city. A final analysis confined to the set of joint use sites identified, in priority order, twelve locations for EMS vehicles to be phased in over a five year period. The paper concludes with some observations on the process of public sector planning.
Requirements planning systems in the health care environment
Authors: Steinberg Earle , Khumawala Basheer , Scamell Richard
Published: October 2002

An important problem confronting health care administration is cost containment in hospitals. Much of the current high costs can be traced directly to outdated procedures in materials management leading to waste, excessive inventory and unnecessary obsolescence of expensive short shelf life items. In this paper, we illustrate how a modern requirements planning system for surgical supplies was developed for a private hospital in Houston and used to effectively hold inventory levels to the minimum required to support a detailed schedule of surgical procedures. We also discuss some specific problems involved in the transfer of manufacturing technology to the hospital setting.
The impact of a rolling schedule in a multi‐level MRP system
Authors: Blackburn Joseph D. , Millen Robert A.
Published: October 2002

This paper presents a cost performance comparison of different lot‐sizing algorithms under multi‐level rolling schedule conditions. Most multi‐level studies have focused on fixed horizon problems, omitting an important characteristic of an operating MRP system. The results indicate that, under certain conditions, the computationally simple Silver‐Meal heuristic provides lower lot‐sizing costs than the Wagner‐Whitin algorithm. In addition, cost modifications are introduced which greatly enhance the multi‐level performance of these single‐level lot‐sizing heuristics.
Learning curves and lot sizing for independent and dependent demand
Authors: Kopcso David P. , Nemitz William C.
Published: October 2002

This paper explores the effect of learning curve cost behavior, as opposed to linear, on lot sizing. The first portion of the paper develops optimizing models for the independent demand situation. The second portion examines lot sizing for dependent demand, developing a lot sizing rule similar to Part Period Balancing.

After examining the shortcomings of previous attempts at the independent demand lot sizing problem, two models are derived. Excluding material costs (for an assembly operation, the cost of all components), the optimal lot size is seen to vary linearly with demand and inversely with the carrying cost rate.

When material costs are included a smaller optimal lot size is derived. The difference between the two, expressed as a fraction of the smaller lot size, equals the material/labor ratio of the last unit produced in the smaller lot size. For dependent demand, the incremental model developed by Freeland and Colley as an improvement on Part Period Balancing is used as a beginning concept. An analogous model, called Assembly Period Balancing, is developed for learning curve cost behavior. The decision rule for combining lots is expressed as a comparison of the material/labor ratio of the lot considered for combining with another expression involving the carrying cost rate, relative lot size and the learning curve exponent.

Finally, cost data from an electronics manufacturer are used to examine the cost penalties of failing to recognize learning curve cost behavior. It is shown that optimal lot sizes for learning curve costs can be much larger than those obtained assuming linear costs. It is also shown that much larger lots can be economically combined in the dependent demand case when costs follow a learning curve.
Achieving factory automation through Group Technology principles
Authors: Suresh Nallan C. , Meredith Jack R.
Published: October 2002

This article illustrates the use of Group Technology (GT) principles for integrating the various elements of Computer Integrated Manufacturing (CIM). Several observations are made regarding the current state of batch manufacturing in the U.S. in light of these principles. Following a brief historical background, the various elements of GT are described as they occur in the manufacturing cycle. Since the main prerequisite to GT is part family identification, the various classification and coding systems for identifying part families, and also non‐codification systems, are briefly described.

The benefits of design rationalization and variety reduction are then explained in the context of CAD, CAM, and CAPP. Next, cellular manufacturing, currently the major problem area in the U.S. regarding GT, is discussed. The discussion includes new production technologies and concepts such as economies of scope. Materials management and operation scheduling are discussed next, highlighting the GT/MRP interface. The effect of GT and other new technologies on quality is then addressed and the significant impacts here are noted. Next, the effects on related areas such as personnel and accounting are described, including worker satisfaction, incentive schemes, and cost tracking.

Last, an assessment of the current status of batch manufacturing is undertaken. Academic approaches, as well as industry crusades such as just‐in‐time (JIT) production, are reviewed and the current problems in adopting cellular layouts are addressed.
Stochastic unpaced line design: Review and further experimental results
Authors: Smunt Timothy L. , Perkins William C.
Published: October 2002

Previous design studies of unpaced assembly lines that exhibit stochastic task times indicate that an unbalanced allocation of task times results in optimal output rates. In this article, we present a comprehensive review of the previous literature on this topic and discuss the results of simulation experiments that test the bowl distribution for unbalancing unpaced lines. The simulation experiment was designed to test the bowl distribution in more realistic environments than previously tested and illustrates that a balanced line configuration is as good as or better than an unbalanced line configuration when task times are modeled with more typical values of variance.

Stochastic unpaced assembly line research employs both simulation and analytical approaches to test the allocation of buffer capacity and task times to work stations. Analytical models are utilized to investigate simple line designs with exponential or Erlang task time distributions. Simulation is used for longer lines and for normal task time distributions. From the review of the previous research using both approaches, we note five major findings: 1) unbalancing task time allocation is optimal when task time variation is large; 2) unbalanced allocation of buffer storage capacity improves line output rate when task time variation is large; 3) output rate of an unpaced line decreases as the number of sequential workstations increases; 4) output rate increases as more buffer storage capacity is available; and 5) output rate decreases as the task time variation increases.

Most of the previous research on unpaced lines investigated lines with few workstations and large task time variation. Empirical research by Dudley (6) suggests that variation of task times in practice is much less than variations employed in previous unpaced line studies. We present the results from simulation experiments that model longer unpaced lines with lower levels of task time variance of the magnitude that is likely to occur in practice.

The results of our simulation experiments verify the benefits of using the bowl distribution for task time allocation when line lengths are short and task times experience large variance. However, when line lengths are extended or task time variation is reduced, the use of the bowl distribution for unbalancing the line degrades the line's efficiency. In these situations, the optimal task time allocation is a balanced line.

Two important implications for managers follow from the results of our experiments: 1) that unpaced line output rate is relatively insensitive to moderate variations from optimal task time allocations when buffer storage is limited; and 2) that perfectly balanced line designs are optimal for most cases in practice.
Maintenance management: Keeping up with production's changing trends and technologies
Authors: Gilbert James P , Finch Byron J
Published: October 2002

Current trends in manufacturing have led to reduced levels of work‐in‐process inventory and increased levels of automation and machine complexity. These changes have two important implications for maintenance management. First, machine breakdowns not only cause a loss of output from the down machine, but also result in lost production on downstream machines. This occurs because of the elimination of buffer stock between workstations. Second, the gap between the technological expertise of the operators and the technological sophistication of their machines has widened. This gap decreases the ability of operators to make adjustments and minor repairs to their own machines.

These two factors cause an increase in maintenance costs associated with machine downtime and maintenance labor. Historically, the proportion of preventive and corrective maintenance has attempted to balance these costs. As buffer stock is reduced and more machines are coupled, the costs of downtime will increase, increasing the need for preventive maintenance and decreasing its cost compared to the cost of lost production.

Increases in the use of computer‐based planning systems have resulted in the development of computerized preventive maintenance systems that have proven to be successful in planning for maintenance labor and materials. Integrating planning methods with corrective maintenance tasks will help reduce breakdowns, make more efficient use of maintenance craft labor, and provide information for inventory control of maintenance, repair, and operating (MRO) materials.

This article examines methods of reducing machine downtime costs, maintenance labor costs, and MRO inventory costs in today's changing production environment. Techniques for reducing these costs are explored in the areas of maintenance planning, maintenance methods improvement, and MRO inventory control.
An investigation of labor assignment rules in a dual‐constrained job shop
Authors: Treleven Mark D. , Elvers Douglas A.
Published: October 2002

One of the management decisions required to operate a dual‐constrained job shop is the labor assignment rule. This study examines the effects of various labor assignment rules on the shop's performance. Eleven different labor assignment rules are simulated. A longest‐queue rule and the traditional counterparts of the first‐in‐system, first‐served, shortest operation time, job due date, critical ratio and shortest processing time dispatching rules are used to determine to which work center available workers should be transferred. Also tested are five new labor assignment rules that use an average of the priority values of all jobs in queue at a particular work center to determine whether that work center should receive the available worker.

A SIMSCRIPT simulation program that models nine work centers provided the mechanism by which these rules were tested. Five dispatching rules, the counterparts of the five “traditional counterpart” labor assignment rules mentioned earlier, provided different shop environments. Also, the level of staffing of the work centers was altered to provide additional ship environments. Staffing levels of 50% and 67% were employed.

The results show that none of the eleven labor assignment rules had a significant impact on shop performance. This is an important result because it implies that a manager can make the labor assignment decision based on other criteria such as ease or cost of application of the rules. These results were relatively insensitive to the shop environment, as represented by the dispatching rule and the staffing level.
Expert systems in production management: An assessment
Authors: Mertens Peter , Kanet John J.
Published: October 2002

Over the last several years expert systems (ES) have gained almost sensational interest. Within business administration, production management might be one of the most fruitful application areas for ES. There already exist a number of interesting pilot systems, and reports of research projects are beginning to appear in the literature.

The main goal of this study is to identify systematically those areas in production management where an ES approach might be most promising. This is important to both researchers and practitioners because it helps pinpoint where research and development resources would be best allocated.

In this article the authors provide a taxonomy for production management activities. They then combine this taxonomy with a well‐known list of eight “expert tasks” to provide what they call an “applications map” to guide the discussion.

After discussing existing research efforts and potential production management applications of expert systems, the authors employ a Likert scoring procedure to quantify their subjective ratings as to problem importance, potential for improved solution, and ease of development, for expert systems development efforts in a given production management decision situation.

One conclusion here is that the applicability of expert systems to production management appears to be broadly based. This is particularly true for what the authors have labeled as “technological” activities. An interesting finding is the apparent lack of applicability of expert systems to inventory management. The authors found no existing system or research proposals applying expert systems to inventory management. Finally, systems that combine technological with logistical knowledge seem to be a fertile (but difficult) application area for ES.
Applications of decision support and expert systems in flexible manufacturing systems
Authors: Turban Efraim , Sepehri Mehran
Published: October 2002

Flexible manufacturing systems (FMS) increase the efficiency of operations by improving cost, quality, and lead time while decision support and expert systems (DSS&ES) improve the effectiveness of manufacturing by assisting the decision maker in coordinating all the elements and increasing the overall utilization of the factory, particularly in managing a complex system of flexible manufacturing. This article surveys a number of available decision support and expert systems applications in flexible manufacturing after reviewing the features of each one and then proposes additional potential applications.

It appears that what is holding back the widespread use of FMS is not the technology, but is some management issues. Application of DSS&ES enables a manager to obtain a full flexibility of equipment in terms of machine flexibility, product flexibility, process flexibility, operation flexibility, routing flexibility, volume flexibility, expansion flexibility, and production flexibility. Many decisions are made in planning and operating FMS that can be categorized into three classes of strategic, tactical, and operational decisions. Each class can be further categorized into structured, semistructured, and unstructured decisions. The article provides examples of FMS decision in each of nine groups and show that use of DSS&ES can be productive.

Illustrative cases are categorized into (1) DSS in FMS, (2) DSS in related manufacturing operations, (3) ES in FMS, and (4) ES in related manufacturing operations. The cases described include ICAM, REACT, KEE, PADMS, IMS, FADES, GARI, TOM, ISIS, and GENPLAN.

The article finally provides hints for successful DSS and ES implementation. Subjects include getting management involved, choosing a key application, manage vendor involvement, paying attention to maintenance, assigning qualified personnel, paying attention to training, and always reviewing the results.

FMS is basically a computer‐based system and so are DSS and ES. There is an increased trend of integrating independent computer‐based systems to take advantage of the possible synergy of such integration. At present, there is only a little evidence of DSS and/or ES applications in FMS. However, there is increasing evidence of applications in related manufacturing areas. Furthermore, the planning and operations of FMS require considerable expertise; DSS and ES techniques are aimed at supporting or even replacing such expertise. Therefore, it seems that there is a considerable potential for further application of DSS and ES in FMS.
Measuring the impact of part‐time workers in service organizations
Authors: Mabert Vincent A. , Showalter Michael J.
Published: October 2002

In the last twenty years we have seen a significant increase in interest by practicing managers and academic researchers in the labor/staff scheduling decision. In particular, service firm managers have focused their attention on improving the productivity of their labor intensive operations by an increased use of part‐time personnel. These actions have been motivated by the presence of significant variations in hourly and daily work loads faced by these firms and the desire to provide flexibility to adequately match staff capacity with customer demand. The past employment practice of using full‐time staff causes significant idle capacity to exist in many firms, reducing productivity. The significant increased use of part‐time staff has allowed today's managers to correct this situation by reducing the amount of idle labor capacity, thus reducing operating cost.

Academic researchers have also investigated the labor scheduling problem during the past two decades. They have analyzed and evaluated mathematical algorithms, optimal and heuristic, to efficiently solve the staff tour scheduling problem. Some of this work has eventually found applicability in a number of service firms. However, most of these studies have focused on the scheduling of full‐time staff to meet varying daily and hourly work load shifts and little insight has been attained in understanding a number of trade‐off issues in this area.

In this paper we investigate the complex issue of the trade‐off between full‐time and part‐time staff and develop a relative “measure of flexibility” for using part‐time individuals. First, we demonstrate, as might be expected, how greater flexibility reduces idle labor capacity. Second, we define and test what is “scheduling flexibility,” as measured by work‐hours‐per‐day and work‐days‐per‐week. Third, we document the marginal reduction in labor hours scheduled attainable with increased flexibility, using actual operating data from a lockbox department in a large Chicago commercial bank. And fourth, we demonstrate the cost implications of using part‐time staff by employing operating data from the wire transfer department of a New York commercial bank, where we examine the problem using cost data as a basis for comparing the relative impact of various labor scheduling decisions and flexibility. We illustrate the common trade‐offs that must be evaluated due to various labor costs, turnover rates, full and part‐time personnel hours and differing productivity rates among various categories of personnel. Our approach illustrates the type of analysis that should be conducted by practicing managers to adequately evaluate the trade‐offs for the staffing decision when using both full and part‐time personnel.
Operations as marketing: A competitive service strategy
Authors: Roth Aleda V. , Van Der Velde Marjolijn
Published: October 2002

This paper presents a competitive service strategy paradigm which explicitly considers the strategic role of operations as a competitive weapon. This service strategy paradigm draws upon the prevailing manufacturing strategy literature in its definition of strategic operations choices and critical success factors. We show that to make a service delivery system a potential marketing tool, critical success factor criteria must be based upon the explicit service task or mission which coincides with a service operations strategy. We illustrate how critical success factors are the linchpin between operations and marketing in service organizations.

Assessing critical success factors is the first step of a process which determines the strategic role that operations can play in a service firm. Using a sample of 117 retail banks, our paper explores industry critical success factors along two dimensions, one is market‐oriented and the other is competitor‐oriented. We derive a framework, which we label the Customer/Account Base (CAB) matrix, to serve as a decision‐aiding tool to evaluate the relative competitive positioning of a service firm. Our analyses show that quadrants on the CAB matrix coincide with four stages of capability development, similar to those found in manufacturing by Hayes and Wheelwright (1984), reflecting the strategic role a service delivery system design plays in meeting the competition.

We go on to empirically link the competitive priorities of retail banks with operations strategy contents of structure, infrastructure and integration choices. Using our service strategy paradigm, we empirically show that the pattern of operations choices varies by competitive priority. As anticipated, the pattern of operations choices linked to relationship banking, one of the most difficult capabilities to achieve and one that requires a high degree of customer contact, is characterized by the most holistic and integrative operations strategy. In conclusion, our exploratory findings illustrate how the prevailing manufacturing strategy framework can be adopted in service strategy delivery system design and the moderating role that customer contact exerts in service strategy formation.
Manufacturing and marketing interdependence in the new venture firm: An empirical study
Authors: Deane Richard H. , McDougall Patricia P. , Gargeya Vidyaranya B.
Published: October 2002

This research addresses the interdependent nature of manufacturing and marketing decisions in new venture firms. Based on an empirical study of new venture firms in the communications and computer equipment manufacturing industry, the research first shows that the perception of key aspects of the environment, entry barriers, and hostility does not differ between successful and unsuccessful new venture firms. Such a finding suggests that new venture success is based on much more than an accurate perception of the environment. In contrast, differences in performances are more likely to be attributable to the manner in which the firms constitute and implement their strategies, given their perceptions of the environment.

The research also reveals no underlying difference in manufacturing and marketing breadth between successful and unsuccessful new venture firms. The research thus, does not support the proposition that successful new ventures must be limited in scope to a narrow product range, a small market segment, a narrow geographic market, and a limited number of distribution channels. A successful firm in this industry may strategically “focus” on alternative competitive advantages such as customization, delivery speed, product development and innovation. Such a concept of focus is not based on the notion of a narrow product mix for a particular market niche, but on a coherent set of tasks based on market requirements.

This research illustrates the importance of the interaction between manufacturing and marketing decisions in predicting new venture firm success. However, the study also suggests that consistency among manufacturing decisions alone may be insufficient to predict firm success. Likewise, consistency among marketing decisions alone is insufficient to predict firm success. As a result, any study that purports to predict new venture firm success based only on an analysis of manufacturing decisions is suspect. The interaction of manufacturing and marketing decisions is only moderately successful in predicting firm success, indicating that the manufacturing and marketing interface is important, but still doesn't provide a complete picture of firm synergy. A more complete model for predicting firm success should likely incorporate other strategic, interdependent relationships with manufacturing and marketing decisions (i.e., the firm's human resource management strategy, financial strategy, R and D posture, etc).
A robust forecasting technique for inventory and leadtime management
Authors: Karmarkar Uday S.
Published: October 2002

Inventory stocking problems with stochastic demand typically involve an estimate of the location of some fractile of the demand distribution, where the fractile is usually in the 0.8‐0.99 range. This fractile is termed the “service level” and is the probability that demands will be satisfied from stock on hand. An analogous procedure must be followed to set safety times or time buffers for delivery and supply lead times. The conventional approach of using the Normal model to estimate this location can sometimes be misleading since it primarily uses information about the center of the distribution to predict behavior in the tail of the distribution.

A new method based on a mixture model is proposed to estimate the location of the appropriate fractile directly. A formal Bayesian approach is derived and heuristic smoothing methods are developed. Simulation is used to evaluate the methods. The estimate obtained is biased in general but robust in the sense that it works well for a variety of distributions. The performance of this method appears to be superior to the conventional Mean ‐ MAD approach. The method is particularly well suited to application in base‐stock inventory systems and for safety time determination in supply management when leadtimes are variable.
A Multicriteria Approach to Mutual Fund Selection
Authors: Cook Wade D. , Hebner Kevin J.
Published: October 2002

In practice, when investors select a mutual fund, they take into account a number offactors. However, the most popular approach for evaluating mutual funds employs only a single criterion, thefinds’ mean, n’sk-adjusted, rate of return (Jensen’s a coefficient). In thepresent paper a multicriteria approach to mutual fund selection is presented. The multicriteria methodology allows numerousfactors to be considered, for example, the standard deviation of thefunds’ a’s, front and back-end loadfees, the level of diversification, quality of service, and so on. It also recognizes that individual investors possess heterogeneous attributes and preferences, and hence, allows investors to formulate different ratings (and consequently rankings) of the set of competing mutual funds.
Structure of Trypanosoma cruzi glycosomal glyceraldehyde‐3‐phosphate dehydrogenase complexed with chalepin, a natural product inhibitor, at 1.95 Å resolution
Authors: Pavão F. , Castilho M.S. , Pupo M.T. , Dias R.L.A. , Correa A.G. , Fernandes J.B. , da Silva M.F.G.F. , Mafezoli J. , Vieira P.C. , Oliva G.
Published: October 2002

The structure of the glycosomal glyceraldehyde‐3‐phosphate dehydrogenase (gGAPDH) from Trypanosoma cruzi complexed with chalepin, a natural product from Pilocarpus spicatus, has been determined by X‐ray crystallography to 1.95 Å resolution. The structure is in the apo form without cofactors in the subunits of the tetrameric gGAPDH in the asymmetric unit. Unequivocal density corresponding to the inhibitor was clearly identified in one monomer. The final refined model of the complex shows extensive conformational changes when compared with the native structure. The mode of binding of chalepin to gGAPDH and its implications for inhibitor design are discussed.
Pretreatment with salicylic acid primes parsley cells for enhanced ion transport following elicitation
Authors: Katz Vera , Fuchs Annette , Conrath Uwe
Published: October 2002

Pretreatment with salicylic acid (SA), an inducer of plant disease resistance, enhanced the capacity of parsley cells for the induction of a rapid K+/pH response and the subsequent coumarin (phytoalexin) secretion. In SA‐primed cells, a low elicitor dose induced these two responses to a similar extent as did a high elicitor dose in non‐primed cells. These observations suggest that the SA‐mediated augmentation of the early K+/pH response may contribute to the enhancement of subsequent coumarin secretion. As the amphotericin B‐induced K+/pH response was not enhanced in SA‐primed cells, it is concluded that signaling components that are improved by priming are located between elicitor signal perception and the plasma membrane transporters mediating the K+/pH response.
Impaired maturation of the siderophore pyoverdine chromophore in Pseudomonas fluorescens ATCC 17400 deficient for the cytochrome c biogenesis protein CcmC
Authors: Baysse Christine , Budzikiewicz Herbert , Urı́a Fernández Diana , Cornelis Pierre
Published: October 2002

Pyoverdines are the main siderophores of fluorescent pseudomonads. They comprise a quinoline chromophore, a peptide chain, and a dicarboxylic acid or a dicarboxylic acid amide side chain. Each Pseudomonas species produces a pyoverdine with a different peptide chain. A cytochrome c biogenesis ΔccmC mutant of Pseudomonas fluorescens ATCC 17400 produces multiple pyoverdine forms, showing differences at the level of the chromophore or the side chain. When grown in the presence of L‐cysteine, ΔccmC produces only ferribactin, a non‐fluorescent precursor of pyoverdine, while addition of oxidized glutathione improves pyoverdine production. We suggest that the conversion of ferribactin to pyoverdine does not take place in the ΔccmC mutant because of lack of oxidizing power in the periplasm.
Monoclonal anti‐diuron antibodies prevent inhibition of photosynthesis by diuron
Authors: Werner Deljana , Behrsing Olaf , Scharte Gudrun , Woller Jochen , Steup Martin , Micheel Burkhard
Published: October 2002

Two monoclonal anti‐diuron antibodies were generated that bind to diuron with an extremely low equilibrium dissociation constant. The antibodies prevented and restored in vitro and in vivo the diuron‐dependent inhibition of photosynthesis. In isolated thylakoids prepared from spinach leaves (Spinacia oleracea L.) the diuron‐inhibited Hill reaction was reconstituted immediately after the addition of the monoclonal antibodies. The antibodies also restored the diuron‐dependent inhibition of the photosynthetic oxygen evolution of the cell wall‐deficient mutant cw15 of the green alga Chlamydomonas reinhardtii Dangeard.
A cytochrome c encoded by the nar operon is required for the synthesis of active respiratory nitrate reductase in Thermus thermophilus
Authors: Zafra Olga , Ramı́rez Sandra , Castán Pablo , Moreno Renata , Cava Felipe , Vallés Cristina , Caro Eddy , Berenguer José
Published: October 2002

A cytochrome c (NarC) is encoded as the first gene of the operon for nitrate respiration in Thermus thermophilus. NarC is required for anaerobic growth and for the synthesis of active nitrate reductase (NR). The α and δ subunits (NarG, NarJ) of the NR were constitutively expressed in narC::kat mutants, but NarG appeared in the soluble fraction instead of associated with the membranes. Our data demonstrate for NarC an essential role in the synthesis of active enzyme and for the attachment to the membrane of the respiratory NR from T. thermophilus.
Magic‐angle spinning 31P NMR spectroscopy of condensed phosphates in parasitic protozoa: visualizing the invisible
Authors: Moreno Benjamin , Rodrigues Claudia O , Bailey Brian N , Urbina Julio A , Moreno Silvia N.J , Docampo Roberto , Oldfield Eric
Published: October 2002

We report the results of a solid‐state 31P nuclear magnetic resonance (NMR) spectroscopic investigation of the acidocalcisome organelles from Trypanosoma brucei (bloodstream form), Trypanosoma cruzi and Leishmania major (insect forms). The spectra are characterized by a broad envelope of spinning sidebands having isotropic chemical shifts at ∼0, −7 and −21 ppm. These resonances are assigned to orthophosphate, terminal (α) phosphates of polyphosphates and bridging (β) phosphates of polyphosphates, respectively. The average polyphosphate chain length is ∼3.3 phosphates. Similar results were obtained with whole L. major promastigotes. 31P NMR spectra of living L. major promastigotes recorded under conventional solution NMR conditions had spectral intensities reduced with respect to solution‐state NMR spectra of acid extracts, consistent with the invisibility of the solid‐state phosphates. These results show that all three parasites contain large stores of condensed phosphates which can be visualized by using magic‐angle spinning NMR techniques.
In diatoms, a transthylakoid proton gradient alone is not sufficient to induce a non‐photochemical fluorescence quenching
Authors: Lavaud J , Rousseau B , Etienne A.-L
Published: October 2002

Non‐photochemical fluorescence quenching (NPQ) in diatoms is associated with a xanthophyll cycle involving diadinoxanthin (DD) and its de‐epoxidized form, diatoxanthin (DT). In higher plants, an obligatory role of de‐epoxidized xanthophylls in NPQ remains controversial and the presence of a transthylakoid proton gradient (ΔpH) alone may induce NPQ. We used inhibitors to alter the amplitude of ΔpH and/or DD de‐epoxidation, and coupled NPQ. No ΔpH‐dependent quenching was detected in the absence of DT. In diatoms, both ΔpH and DT are required for NPQ. The binding of DT to protonated antenna sites could be obligatory for energy dissipation.
Identification and characterization of a cyanobacterial DnaX intein
Authors: Liu Xiang-Qin , Hu Zhuma
Published: October 2002

A new intein is identified and characterized in the DnaX protein of Synechocystis sp. PCC6803. This cyanobacterial DnaX protein is a homologue of the intein‐less 71‐kDa tau‐subunit of Escherichia coli DNA polymerase III and is related to eukaryotic DNA replication factor C (RFC). The 430‐residue DnaX intein contains several putative intein sequence motifs and undergoes protein splicing when produced in E. coli cells. Its position in the DnaX protein is close to, but different from, positions of three inteins present in a DnaX‐related RFC protein of Methanococcus jannaschii.
Cathepsin J, a novel murine cysteine protease of the papain family with a placenta‐restricted expression
Authors: Tisljar Kai , Deussing Jan , Peters Christoph
Published: October 2002

A novel mouse cysteine protease of the papain family was identified by searching the dbEST database. A 1.28 kb full‐length cDNA was obtained which contains an open reading frame of 999 nucleotides and encodes a predicted polypeptide of 333 amino acids. The deduced polypeptide exhibits features characteristic of cysteine proteases of the papain type including the highly conserved residues of the catalytic triad, and was hence named cathepsin J. Cathepsin J represents the murine homologue of a previously described rat cathepsin L‐related protein. Mature cathepsin J shows 59.3% identity to mouse cathepsin L and contains the characteristic ER(F/W)NIN motif within the propeptide indicating that this protease belongs to the subgroup of cathepsin L‐like cysteine proteases. Northern blot analysis of various tissues revealed a placenta‐restricted expression. This expression pattern may suggest a role of cathepsin J in embryo implantation and/or placental function. Ctsj was mapped to mouse chromosome 13 in the vicinity of cathepsin L suggesting that cathepsin J may have arisen by gene duplication from cathepsin L or a common ancestral gene.
Suppression of okadaic acid‐induced apoptosis by overexpression of calpastatin in human UVr‐1 cells
Authors: Chi Xiao-Jun , Hiwasa Takaki , Maki Masatoshi , Sugaya Shigeru , Nomura Jun , Kita Kazuko , Suzuki Nobuo
Published: October 2002

Proteolytic systems have various involvements in apoptotic pathways. To understand the role of calpain in apoptosis, calpastatin, a specific inhibitor of calpain, was overexpressed in human UVr‐1 fibroblasts by transfection of its cDNA. The elevated expression of calpastatin resulted in decreased survival in the presence of okadaic acid (OA) but in no apparent alteration in the sensitivity toward other drugs such as 5‐fluorouracil, mitomycin C and methotrexate. After treatment with OA, a typical apoptotic DNA ladder was observed in control vector‐transfected cells but not in calpastatin‐transfected cells. This indicates that OA‐induced apoptosis was suppressed by overexpression of calpastatin. Further immunoblot analysis showed that the OA‐induced hyperphosphorylation of c‐Jun was inhibited in calpastatin‐transfected cells. This might be involved in the resistance to OA‐induced cell death in calpastatin‐overproducing cells.
Demand chain management in manufacturing and services: web‐based integration, drivers and performance
Authors: Frohlich Markham T , Westbrook Roy
Published: October 2002

This paper investigated the relationship between Internet‐enabled supply chain integration strategies and performance in manufacturing and services. It summarizes the literature on demand and supply integration and describes four web‐based strategies. A stratified random sample was collected from UK manufacturers and services, and there was strong evidence that demand chain management (DCM) led to the highest performance in manufacturing, but few signs of DCM in services. Manufacturers and services relying on only web‐based demand or supply integration outperformed their low integration counterparts, but lagged DCM in manufacturing. The study also investigated DCM adoption drivers and found that rational efficiency and bandwagon effects drove change. The findings have some important implications for theory as well as for manufacturing and service companies interested in improving their performance.
New aspects in the treatment of heroin dependence with special reference to neurobiological aspects
Authors: Ladewig Dieter , Dürsteler-MacFarland Kenneth M. , Seifritz Erich , Hock Christoph , Stohler Rudolf
Published: October 2002

The Swiss trials on medical prescription of injectable diacetylmorphine (pharmaceutical heroin) for “severe” heroin dependence provoked very controversial commentaries. Despite methodological shortcomings, the evaluation of the Swiss heroin trials yielded some interesting findings. Study participants showed substantial improvements in health and well-being and noticeable declines in illicit drug use and criminal activities. Heroin prescription may thus be helpful for some of those who continue to regularly use illicit heroin while maintained on methadone or who refuse other available treatment options. However, research-based evidence suggests that the intravenous (IV) application of heroin under medical supervision may have untoward side effects. Recent studies have shown that heroin injections produce transient, but significant decreases in systemic and cortical oxygenation most likely secondary to respiratory depression. Among others, these effects are the subject of ongoing studies.
The meaning of ceraunia: archaeology, natural history and the interpretation of prehistoric stone artefacts in the eighteenth century
Authors: GOODRUM MATTHEW R.
Published: October 2002

Historians of archaeology have noted that prehistoric stone artefacts were first identified as such during the seventeenth century, and a great deal has been written about the formulation of the idea of a Stone Age in the nineteenth century. Much less attention has been devoted to the study of prehistoric artefacts during the eighteenth century. Yet it was during this time that researchers first began systematically to collect, classify and interpret the cultural and historical meaning of these objects as archaeological specimens rather than geological specimens. These investigations were conducted within the broader context of eighteenth-century antiquarianism and natural history. As a result, they offer an opportunity to trace the interrelationships that existed between the natural sciences and the science of prehistoric archaeology, which demonstrates that geological theories of the history of the earth, ethnographic observations of ‘savage peoples’ and natural history museums all played important roles in the interpretation of prehistoric stone implements during the eighteenth century.
A magnetohydrodynamic chaotic stirrer
Authors: YI MINGQIANG , QIAN SHIZHI , BAU HAIM H.
Published: October 2002

A magnetohydrodynamic (MHD) stirrer that exhibits chaotic advection is investigated
experimentally and theoretically. The stirrer consists of a circular cavity with an
electrode (C) deposited around its periphery. Two additional electrodes (A) and (B)
are deposited eccentrically inside the cavity on the bottom. The cavity is positioned
in a uniform magnetic field that is parallel to the cylinder's axis, and it is filled with a
weak electrolyte solution. Fluid motion is induced in the cavity by applying a potential
difference across a pair of electrodes. A closed-form, analytical solution is derived
for the MHD creeping flow field in the gap between the two eccentric cylinders. A
singular solution is obtained for the special case when the size of the inner electrode
shrinks to a point. Subsequently, passive tracers' trajectories are computed when the
electric potential differences are applied alternately across electrodes AC and BC with
period T. At small periods T, the flow is regular and periodic in most of the cavity. As
the period increases, so does the complexity of the motion. At relatively large periods,
the passive tracer experiences global chaotic advection. Such a device can serve as
an efficient stirrer. Since this device has no moving parts, it is especially suitable
for microfluidic applications. This is yet another practical example of a modulated,
two-dimensional Stokes flow that exhibits chaotic advection.
Can the Subtropical North Atlantic permanent thermocline be observed from space?
Authors: Pingree Robin , Kuo Yu-Heng , Garcia-Soto Carlos
Published: October 2002

The analysis of remotely sensed altimeter data and in situ measurements shows that ERS 2 radar can monitor the ocean permanent thermocline from space. The remotely sensed sea level anomaly data account for ∼2/3 of the temperature variance or vertical displacement of isotherms at a depth of ∼550 m in the Subtropical North Atlantic Ocean near 32·5°N. This depth corresponds closely to the region of maximum temperature gradient in the permanent thermocline where near semi-annual internal vertical displacements reach 200 to 300 m. The gradient of the altimeter sea level anomaly data correlates well with measured ocean currents to a depth of 750 m. It is shown that observations from space can account for ∼3/4 of the variance of ocean currents measured in situ in the permanent thermocline over a 2-y period. The magnification of the permanent thermocline displacement with respect to the displacement of the sea surface was determined as −×650 and gives a measure of the ratio of barotropic to baroclinic decay scale of geostrophic current with depth. The overall results are used to interpret an eight year altimeter data time series in the Subtropical North Atlantic at 32·5°N which shows a dominant wave or eddy period near 200 days, rather than semi-annual and increases in energy propagating westward in 1995 (west of 25°W). The effects of rapid North Atlantic Oscillation climate change on ocean circulation are discussed. The altimeter data for the Atlantic were Fourier analysed. It is shown how the annual and semi-annual components relate to the seasonal maximum cholorophyll-a SeaWiFS signal in tropical and equatorial regions due to the lifting of the thermocline caused by seasonally varying ocean currents forced by wind stress.
Appearance of the common paper nautilus Argonauta argo related to the increase of the sea surface temperature in the north-eastern Atlantic
Authors: Guerra A. , González A.F. , Rocha F.
Published: October 2002

The relationship between the increase of the sea surface temperature observed off the Galician coast and the appearance of a tropical poikilotherm species Argonauta argo in these coasts is discussed. This is the first record of Argonautaargo in the north-west Iberian Peninsula. A female of this species was captured alive near the surface at dusk on 22 December 2000 in the Ria de Aldán (42°15′N–08°48′W). The specimen, a mature female of 70 mm mantle length and 96 mm shell diameter, died 36 hours after introduction in the tank.
The prevalence of TT virus and GB virus C/hepatitis G virus infection in individuals with raised liver enzymes but without HBV or HCV infection in Taiwan
Authors: DAI C. Y. , YU M. L. , CHANG W. Y. , TSENG C. H. , HOU C. , LIN Z. Y. , CHEN S. C. , HSIEH M. Y. , WANG L. Y. , TSAI J. F. , CHUANG W. L.
Published: October 2002

The prevalence of TT virus (TTV) and GB virus-C/hepatitis G virus (GBV-C/HGV) infection and the association with raised liver function tests in 546 Taiwanese with negative HBsAg, anti-HCV and HCV RNA was elucidated. They were tested for serum alanine aminotransferase (ALT), GBV-C/HGV RNA, anti-envelope protein 2 antibody (anti-E2) and TTV DNA. Direct sequencing and phylogenetic analyses were performed on 58 isolates for TTV genotype determination. The prevalence of TTV DNA, GBV-C/HGV RNA, anti-E2 and over all GBV-C/HGV exposure was 24.9, 3.4, 8.2 and 11.1%, respectively. Using uni- and multi-variate analyses, male gender and TTV viremia were associated significantly with raised ALT values. Sixty-nine percent of TTV isolates were deduced to be TTV genotype 1 and they had significantly lower mean age than genotype non-1 isolates. In the population, raised ALT may be related to male gender and be attributable to TTV infection but not to GBV-C/HGV among individuals with no evidence of current HBV and HCV infection. TTV genotype 1 is the most prevalent genotype and associated with younger age.
Matroid Duality from
Topological Duality in Surfaces of
Nonnegative Euler Characteristic
Authors: SLILATY DANIEL C.
Published: October 2002

Let G be a connected graph that is 2-cell embedded in a surface S, and let G* be its
topological dual graph. We will define and discuss several matroids whose element set is
E(G), for S homeomorphic to the plane, projective plane, or torus. We will also state and
prove old and new results of the type that the dual matroid of G is the matroid of the
topological dual G*.