bluuebunny/crossref_metadata_2025 huggingface dataset:
A heuristic solution procedure for the multi‐item, single‐level, limited capacity, lot‐sizing problem
Authors: Dixon Paul S. , Silver Edward A.
Published: October 2002

The problem to be considered is that of determining lot‐sizes for a group of products which are produced at a single workcentre. It is assumed that the requirements for each product are known, period by period, out to the end of some common time horizon. (A reasonable assumption in a Material Requirements Planning context when we are dealing with components of one or more other items already scheduled.) For each product there is a fixed setup cost incurred each time production takes place. Unit production and holding costs are linear. The time required to set up the machine is assumed to be negligible. All costs and production rates can vary from product to product but not with respect to time. In each period there is a finite amount of machine time available that can vary from period to period. The objective is to determine lot‐sizes so that 1) costs are minimized, 2) no backlogging occurs and 3) capacity is not exceeded.

An exact solution to this complex problem is out of the question. Therefore, a simple heuristic has been developed which guarantees a feasible solution, if one exists. Results of a large number of test problems, including three supplied by industrial sources, are presented. The results indicate that the heuristic will usually generate a very good solution with a relatively small amount of computational effort.
Research issues for multi‐level lot sizing in MRP systems
Authors: Collier David A.
Published: October 2002

What lot size model(s) to use in a Material Requirements Planning (MRP) system is an unresolved and often debated issue. The concept of dependent demand, the complex network defined by the product structure, the dynamics of an operating MRP‐based system, and the subsequent use of the planned order release schedule by other company subsystems represent a totally new environment for making and managing lot size decisions.

The purpose of this paper is to identify and briefly examine ten research issues related to lot sizing in a dependent demand product structure. These ten issues expand the solution space for lot sizing in an MRP‐based system compared to a reorder point based system. Areas for further research are suggested.
Multiplant MRP
Authors: Bitran Gabriel R. , Marieni David M. , Matsuo Hirofumi , Noonan James W.
Published: October 2002

Many manufacturing firms have multiple manufacturing plants, located in geographically diverse parts of the world. This situation is becoming more common, as firms establish new plants in foreign countries to take advantage of low labor cost. In such cases, it is not unusual for the firm to retain production capability of certain key parts in a backup plant, with the necessary equipment and trained workforce in place. High volume production could be obtained relatively quickly from the backup plant in case of an emergency at the main supplying plant. In such multiplant settings, the transportation costs are significant. Throughout this paper, we use the term “multisourced parts” to describe parts produced in more than one location.

Material Requirements Planning (MRP) is the component of a total manufacturing control system that is designed to manage inventory and plan orders for parts and material with dependent demand (demand derived from the demand of other items). Most of the literature on MRP systems discusses MRP methodology in a single‐plant environment. Most MRP software systems in use today are single‐plant systems.

Currently, it is common for firms with multiple plants treated as cost centers to use an independent single‐plant MRP system for each and handle the transshipment problems manually. Because of lack of coordination of production schedules between supplying and demanding plants, those firms hold more inventory and experience longer lead times than necessary to compensate for uncertainties in schedules and supply policies.

The purpose of this article is to enhance single‐plant MRP systems for coping with multiplant situations in which: the plants are regarded as cost centers, there exist multisourced parts, and the transportation costs are significant. The multiplant MRP system should recognize that parts are produced in different plants, make offset calculations for in‐transit lead times, and consider transportation costs when establishing production requirements and shipping routes for multisourced parts. The objective is, beginning with the corporate‐determined master schedule for finished products, to communicate in one planning cycle time‐phased planned order release schedules and shipping/delivery schedules to each manufacturing plant producing components for the finished products.

We first present a simplified framework for the multiplant MRP system, where a transportation algorithm is incorporated into the MRP logic. Then we refine this simplified framework to handle more complex aspects of a multiplant network. These complexities include the treatment of requirements that are not shipped on time and the regeneration of new MRP schedules. We also observe that the solution to the transportation problem described above is affected by the lot‐sizing rules employed. In addition, we discuss several important issues and decisions that confront a firm when implementing a multiplant MRP system.
Shift scheduling in services when employees have limited availability: An L.P. approach
Authors: Thompson Gary M.
Published: October 2002

This paper compares two linear programming (LP) models for shift scheduling in services where homogeneously‐skilled employees are available at limited times. Although both models are based on set covering approaches, one explicitly matches employees to shifts, while the other imposes this matching implicitly. Each model is used in three forms—one with complete, another with very limited meal break placement flexibility, and a third without meal breaks—to provide initial schedules to a completion/ improvement heuristic. The term completion/improvement heuristic is used to describe a construction/ improvement heuristic operating on a starting schedule.

On 80 test problems varying widely in scheduling flexibility, employee staffing requirements, and employee availability characteristics, all six LP‐based procedures generated lower cost schedules than a comparison from‐scratch construction/improvement heuristic. This heuristic, which perpetually maintains an explicit matching of employees to shifts, consists of three phases which add, drop, and modify shifts.

In terms of schedule cost, schedule generation time, and model size, the procedures based on the implicit model performed better, as a group, than those based on the explicit model. The LP model with complete break placement flexibility and implicitly matching employees to shifts generated schedules costing 6.7% less than those developed by the from‐scratch heuristic.
Assembly line design with incompatible task assignments
Authors: Rachamadugu Ram
Published: October 2002

Assembly lines are widely used for the mass production of consumer goods and components in large volume production systems. Design of these lines warrants taking into consideration not only cycle time and precedence constraints, but also other restrictions. An important recurring restriction is that some pairs of tasks cannot be assigned to the same station due to factors such as safety, physical demands placed on workers, quality, and technological considerations. We investigate this problem and a current industry practice used for solving this problem. Our investigation of this problem yields three findings. First, we identify a new class of heuristic procedures which dynamically updates task priorities. Our investigations show that this class of heuristics yields better results. Second, extremely greedy procedures such as knapsack heuristics (Hoffmann procedure) continue to perform better than competing heuristics for industrial grade problems even when additional restrictions on task assignments are present. However, when task restrictions are severe, this is no longer true. Lastly, we present an enumerative procedure to search for optimal solutions in the presence of restrictions. Our study shows that while most simple assembly line balancing problems can be solved optimally, presence of additional restrictions such as task assignments makes them inherently more difficult. We provide insights into this aspect.
Management of technology in service firms
Authors: Haynes Ray M. , Thies Emil A.
Published: October 2002

The service sector is receiving increasing attention with respect to technology implementation and productivity issues. At the same time, industry management remains concerned that the integrated nature of real world business is not adequately covered by academicians and their theories. This paper addresses these issues in a unique manner by examining the results of an industry gathered survey in light of three proven service models.

Specifically, data collected by a major financial services provider during a customer survey associated with two automated delivery systems, automated teller machines and self‐service gas pumps, was made available. Next, three theoretical models were selected reflecting the integrated nature of the service delivery process. Functional disciplines included operations, marketing and human behavior. The actual management of technology issue was considered from the perspectives of productivity, effectiveness, efficiency and quality factors identified in these models.

The customer acceptance and utilization of automated teller machines has been substantially less than the success of self‐service gas during the 1970–1990 period. Comparing the issues of technology management during the implementation of each offers valuable insight into factors requiring consideration when designing automated service delivery systems. Management implications are identified within the framework of lessons learned from studying these two specific technology applications.

The contrast in the success of the implementation of technology in the two service sectors studied was linked to three key factors. First, the process must be well defined and measurable characteristics identified prior to changing the system. Second, the goals of the marketing and operations functions must be coordinated with respect to implementation strategy and established capabilities of the system to change. Finally, the technology implementation must consider the needs of the customer and potential tangible benefits, so that customers will utilize the new system at volume levels that justify the initial expense of the technology.
Conducting case study research in operations management
Authors: McCutcheon David M. , Meredith Jack R.
Published: October 2002

Recently, there have been numerous calls for more empirical field‐based research to be conducted in operations management (OM). Knowledge of how operations systems work can be enhanced significantly through contact with the “real‐world” conditions that OM models seek to describe. Case study research is a primary means of exploring field conditions but is an unfamiliar methodology for many in OM. Moreover, the case study method is viewed with scepticism by those who consider it to be a weak form of research, one that lacks rigor and objectivity.

Here, we offer an introduction to the case study method for OM researchers who may have little background in field based research. We provide an outline of the procedure and cite some excellent sources that cover case study design, data analysis and the philosophical rationale for the methodology. We also identify some recent examples of OM case studies that illustrate our points. We then contrast the various uses for case study research and their different design and theory requirements. An appendix provides a listing of case studies that have appeared in some OM journals in recent years, classifying the studies by their research purpose.

However, regardless of their purposes, case study research need to be conducted in a manner that assures maximum measurement reliability and theory validity. We describe some of the steps that must be taken to ensure that a study is as rigorous as possible. We also argue that, properly conducted, a case study is a truly scientific research approach. We conclude by pointing out some areas of OM research where case studies might be particularly valuable.
An evaluation of labor assignment rules when workers are not perfectly interchangeable
Authors: Bobrowski Paul M. , Park Paul Sungchil
Published: October 2002

The dual resource constrained job shop research has considered the issue of labor flexibility. However, labor flexibility has been defined as the ability of the worker to transfer from work center to work center. A more encompassing definition used in this research is that labor flexibility is worker efficiency at each work station. With workers not equally capable at every center, assignments of different workers to the same work center results in different capacity requirements for the same job. The research here examines how to assign labor to work centers when these differences exist. The traditional labor assignment rules, when to move and where to move, are tested against rules that are created to incorporate worker efficiency information. These rules are first evaluated and then subsequently tested on differing matrices representing other labor efficiencies and with alternative dispatching rules. Results of this research indicate a departure from previous results in the dual resource constrained job shop. The research shows that selection of the rule that governs where the worker should move is the most important choice.
Mixing static and dynamic flowtime estimates for due‐date assignment
Authors: Vig Michelle M. , Dooley Kevin J.
Published: October 2002

Prediction of job flowtimes is important from the perspectives of both providing internal control and customer satisfaction. More specifically, accurate and precise flowtime prediction can facilitate proper timing for the release of materials and resources, improved accuracy of delivery dates to customers, and identification of jobs that require expediting. The objective of this paper is to introduce a new approach to flowtime prediction which improves performance quality over that found in existing dynamic flowtime estimation models. This new approach, mixed flowtime estimation, incorporates both static and dynamic flowtime estimates into a single, flowtime prediction model. In this investigation, mixed and dynamic models are compared experimentally using computer simulation of a job shop under various congestion conditions and dispatching heuristics. The results of this investigation reveal that the mixed flowtime prediction models provide significant improvements in job shop due‐date estimation performance. Statistically significant performance improvements are obtained in both the average lateness and fraction tardy jobs for mixed estimates. Specifically, average lateness is reduced by 25% in the balanced shop and 40% in the bottleneck shop. This improvement enables a corresponding increase in the accuracy of job flowtime estimates, and, hence, due‐date assignment accuracy. Due‐date performance improvements are observed for each scheduling heuristic investigated.
Iterative database searches demonstrate that glycoside hydrolase families 27, 31, 36 and 66 share a common evolutionary origin with family 13
Authors: Rigden Daniel J
Published: October 2002

Classification of glycoside hydrolases (GHs) into families, along with the structure‐based grouping together of families into clans, improve our understanding of the evolution of the large natural variety of these enzymes, help rationalise experimental data and guide further studies. Here we identify triose phosphate isomerase (TIM) barrels in GH families 27, 31, 36 and 66. We further show that iterated sequence database searches provide evidence for their sharing a common evolutionary origin with GH family 13. The catalytic, nucleophilic residue common to all these families is thereby determined and candidate catalytic proton donors identified within each family.
Influence of hydrophobic mismatch and palmitoylation on the association of transmembrane α‐helical peptides with detergent‐resistant membranes
Authors: van Duyl Bianca Y , Rijkers Dirk T.S , de Kruijff Ben , Killian J.Antoinette
Published: October 2002

The aim of this study was to gain insight into the mechanism through which transmembrane proteins are targeted to liquid ordered (Lo) phase domains or rafts. This was investigated by analyzing the Triton X‐100 resistance of designed transmembrane peptides in model membranes of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine, sphingomyelin and cholesterol (1/1/1, molar ratio), which contain both Lo phase domains and fluid bilayers. By using peptides with one or two palmitate chains covalently linked to their N‐terminus or with variable hydrophobic lengths, the roles of protein palmitoylation and of mismatch between the transmembrane segment of the protein and the bilayer thickness, respectively, were investigated. The results show that neither hydrophobic matching nor palmitoylation is sufficient for partitioning of peptides into Lo phase domains. It is concluded that the Lo phase itself, due to the tight packing of the lipids, constitutes an unfavorable environment for accommodation of protein transmembrane segments.
Biosynthesis of the major scent components 3,5‐dimethoxytoluene and 1,3,5‐trimethoxybenzene by novel rose O‐methyltransferases
Authors: Scalliet Gabriel , Journot Noellie , Jullien Frédéric , Baudino Sylvie , Magnard Jean-Louis , Channelière Stéphanie , Vergne Philippe , Dumas Christian , Bendahmane Mohammed , Cock J.Mark , Hugueney Philippe
Published: October 2002

In Chinese rose species and in many modern varieties, two methylated phenolic derivatives, 3,5‐dimethoxytoluene and 1,3,5‐trimethoxybenzene, are major scent components. We show that cell‐free extracts of rose petals catalyse the synthesis of 3,5‐dimethoxytoluene and 1,3,5‐trimethoxybenzene by methylation of precursor molecules. An expressed sequence tag approach was used to identify four highly similar O‐methyltransferase sequences expressed specifically in petals and anthers. Thin layer chromatography analysis showed that the activities of these enzymes with different substrates and the proportions of reaction products produced closely mimicked those observed using cell‐free petal extracts, indicating that orcinol O‐methyltransferases are responsible for the biosynthesis of 3,5‐dimethoxytoluene and 1,3,5‐trimethoxybenzene from un‐methylated precursors in this organ.
Cell‐line specific chromatin acetylation at the Sox10–Pax3 enhancer site modulates the RET proto‐oncogene expression
Authors: Puppo Francesca , Griseri Paola , Fanelli Mirco , Schena Francesca , Romeo Giovanni , Pelicci PierGiuseppe , Ceccherini Isabella , Ravazzolo Roberto , Patrone Giovanna
Published: October 2002

The RET gene is expressed with high tissue and stage specificity during development. Understanding its transcriptional regulation might provide new clues to clarify developmental mechanisms. Here we show that the histone deacetylase inhibitor sodium butyrate (NaB) increases RET transcription in cells displaying low levels of its mRNA, while it has no effect in cells expressing at high levels. Chromatin immunoprecipitation (ChIP) experiments showed increased histone acetylation within the same region, in particular the Sox10–Pax3 enhancer site, due to NaB. Accordingly, ChIP showed different acetylation levels at the Sox10–Pax3 site associated with cell‐line specific RET transcription rates. Concluding, chromatin acetylation targeted to functional sequences in the RET regulatory region may control its transcription.
Transcriptional regulation of the human replacement histone gene H3.3B
Authors: Witt Olaf , Albig Werner , Doenecke Detlef
Published: October 2002

In contrast to the cell‐cycle‐dependent histone genes, replacement histone genes are transcribed independently of DNA replication and their expression is upregulated during differentiation. We have investigated the transcriptional regulation of the recently characterized human replacement histone gene H3.3B. Using reporter gene assays of promoter‐luciferase gene‐constructs, we show that promoter activity largely depends on an intact Oct and CRE/TRE element within the proximal 145 bp of the promoter. DNase I footprinting revealed binding of proteins to a 40‐bp region covering these two elements. Band shift experiments identified binding proteins as Oct‐1 and factors of the CREB/ATF and AP‐1 family, respectively. The unexpected transcriptional regulation of this replacement histone gene is discussed.
Singlet oxygen mediates the activation of JNK by UVA radiation in human skin fibroblasts
Authors: Klotz Lars-Oliver , Briviba Karlis , Sies Helmut
Published: October 2002

Ultraviolet A (UVA: 320–400 nm) radiation activates c‐Jun–N‐terminal kinase (JNK 2) in human skin fibroblasts. Exposure of cells to UVA (300 kJ/m2) led to a 5‐fold induction of JNK‐activity which was significantly increased in the presence of D2O, an enhancer of the lifetime of singlet oxygen. Sodium azide, a quencher of singlet oxygen, abolished the activation of JNK. A hydroxyl radical scavenger, mannitol, had no effect. Furthermore, photochemically produced singlet oxygen (Rose Bengal plus white light) was found to induce JNK activity. This was enhanced by D2O and inhibited by azide. Thus, singlet oxygen activates and mediates the UVA‐induced activation of JNK.
Gastric GATA‐6 DNA‐binding protein: proteolysis induced by cAMP
Authors: Nakagawa Reiko , Sato Ryuichiro , Futai Masamitsu , Yokosawa Hideyoshi , Maeda Masatomo
Published: October 2002

The rat gastric GATA DNA‐binding protein, GATA‐6 (GATA‐GT1), was stably expressed in CHO‐K1 cells. The GATA‐6 protein was localized in the nucleus but not in the cytoplasm. Interestingly, when cells were treated with dibutyryl cAMP, the GATA‐6 protein was specifically degraded. Such a phenomenon was not observed in the presence of 5′‐AMP or dibutyryl cGMP. The cellular level of the GATA‐6 protein was restored upon removal of dibutyryl cAMP. Degradation was also induced by cholera toxin, which increased the cellular cAMP concentration, and was inhibited by a protein kinase A inhibitor. However, activators of protein kinase C did not have any effect. The degradation was inhibited by proteasome inhibitors (PSI (benzyloxycarbonyl‐Ile‐Glu(O‐t‐Bu)‐Ala‐leucinal) and MG115 (benzyloxycarbonyl‐Leu‐Leu‐norvalinal)) but not by those of lysosomes and serine proteases. These results suggest that a kinase‐mediated protein phosphorylation is the cellular signal for degradation of the GATA‐6 protein. This finding constitutes a novel aspect of regulation by GATA DNA‐binding proteins, which are essential for developmental processes and tissue‐specific transcription.
Interaction between the CheY response regulator and the histidine‐containing phosphotransfer (HPt) domain of the ArcB sensory kinase in Escherichia coli
Authors: Yaku Hidenobu , Kato Masato , Hakoshima Toshio , Tsuzuki Masakatsu , Mizuno Takeshi
Published: October 2002

Bacteria have devised sophisticated His–Asp phosphorelay signaling systems for eliciting a variety of adaptive responses to their environment. The histidine‐containing phosphotransfer (HPt) domain, found in many signal transduction protein, functions as a mediator of the His–Asp phosphorelay. The ArcB anaerobic sensor of E. coli contains such a HPt domain, although its function is not fully understood. In this study, we provide in vivo and in vitro evidence that the HPt domain is capable of interacting with the CheY receiver, which contains a phospho‐accepting aspartate residue.
Superoxide anion inhibits drug‐induced tumor cell death
Authors: Pervaiz Shazib , Ramalingam Jeya Kumar , Hirpara Jayshreekumari L , Clément Marie-Véronique
Published: October 2002

Intracellular superoxide (O2

−) was manipulated in M14 melanoma cells by overexpression or repression of Cu/Zn SOD using a tetracycline‐inducible expression system. Scavenging intracellular O2

− increased tumor cell sensitivity to daunorubicin, etoposide, and pMC540, whereas expression of the antisense SOD mRNA significantly decreased cell sensitivity to drug treatment. Whereas Cu/Zn SOD overexpressing cells exhibited higher activation of the executioner caspase 3 upon drug exposure, caspase 3 activation was significantly lower when Cu/Zn SOD was repressed by antisense expression. These data show that intracellular O2

− regulates tumor cell response to drug‐induced cell death via a direct or indirect effect on the caspase activation pathway.
Inhibition of tau phosphorylating protein kinase cdk5 prevents β‐amyloid‐induced neuronal death
Authors: Alvarez Alejandra , Toro Rodrigo , Cáceres Alfredo , Maccioni Ricardo B
Published: October 2002

The key target of this study was the tau protein kinase II system (TPK II) involving the catalytic subunit cdk5 and the regulatory component p35. TPK II is one of the tau phosphorylating systems in neuronal cells, thus regulating its functions in the cytoskeletal dynamics and the extension of neuronal processes. This research led to demonstration that the treatment of rat hippocampal cells in culture with fibrillary β‐amyloid (Aβ) results in a significant increase of the cdk5 enzymatic activity. Interestingly, the data also showed that the neurotoxic effect of 1–20 μM Aβ on primary cultures markedly diminished with co‐incubation of hippocampal cells with the amyloid fibers plus the cdk5 inhibitor butyrolactone I. This inhibitor protected brain cells against Aβ‐induced cell death in a concentration dependent fashion. Moreover, death was also prevented by a cdk5 antisense probe, but not by an oligonucleotide with a random sequence. The cdk5 antisense also reduced neuronal expression of cdk5 compared with the random oligonucleotide. The studies indicate that cdk5 plays a major role in the molecular path leading to the neurodegenerative process triggered by the amyloid fibers in primary cultures of rat hippocampal neurons. These findings are of interest in the context of the pathogenesis of Alzheimer's disease.
Calpain and myogenesis: development of a convenient cell culture model
Authors: Dedieu Stéphane , Dourdin Nathalie , Dargelos Elise , Poussard Sylvie , Veschambre Philippe , Cottin Patrick , Brustis Jean‐Jacques
Published: October 2002

Previous studies have led us to hypothesize that m‐calpain plays a pivotal role in myoblast fusion through its involvement in cell membrane and cytoskeleton component reorganization. To support this hypothesis, a convenient and simple myoblast culture model using frozen embryonic myoblasts was developed, which resolved a number of problems inherent to cell primary culture. Biological assays on cultured myoblasts using different media to define the characteristics of the fusion process were first conducted. Proteinase was detectable before the initiation of the fusion process and was closely correlated to the phenomenon of fusion under each culture condition studied. In addition, the study of calpastatin showed that the initiation of fusion does not require a decrease in the level of this endogenous inhibitor of calpains and also confirmed that calpastatin may be implicated in the determination of the end of fusion. On the other hand, analysis of the evolution of myogenic factors revealed that myogenins, MyoD and Myf5, increase very significantly during the formation of multinucleated myotubes. Moreover, the antisense technique against myogenin is capable of preventing the process of fusion by 50%, confirming the pivotal role of this factor in the early stages of differentiation. The possible role of myogenic regulator factors on m‐calpain gene expression is discussed.
Demand chain management theory: constraints and development from global aerospace supply webs
Authors: Williams Tim , Maull Roger , Ellis Bruce
Published: October 2002

This paper develops an empirical and theoretical approach to where strategic capabilities should lie within global aerospace supply chains. Theory from transaction cost economics (TCE) and the resource‐based view (RBV) of the firm are applied to the aerospace sector and used to underpin a theory of demand chain management (DCM). A two‐stage research process was used to generate and validate data from aerospace supply chain case studies. Demand chain driver and resource‐based response categories were identified from these data and are presented. Concluding comments concern current limits of a demand chain theory and implications for practitioners.
The fluid-dynamic paradigm of the dust-acoustic soliton
Authors: McKENZIE J. F.
Published: October 2002

In most studies, the properties of dust-acoustic solitons are derived from
the first integral of the Poisson equation, in which the shape of the pseudopotential
determines both the conditions in which a soliton may exist and its amplitude. Here
this first integral is interpreted as conservation of total momentum, which, along
with the Bernoulli-like energy equations for each species, may be cast as the structure
equation for the dust (or heavy-ion) speed in the wave. In this fluid-dynamic
picture, the significance of the sonic points of each species becomes apparent. In the
wave, the heavy-ion (or dust) flow speed is supersonic (relative to its sound speed),
whereas the protons and electrons are subsonic (relative to their sound speeds),
and the dust flow is driven towards its sonic point. It is this last feature that limits
the strength (amplitude) of the wave, since the equilibrium point (the centre of
the wave) must be reached before the dust speed becomes sonic. The wave is characterized
by a compression in the heavies and a compression (rarefaction) in the
electrons and a rarefaction (compression) in the protons if the heavies have positive
(negative) charge, and the corresponding potential is a hump (dip). These features
are elucidated by an exact analytical soliton, in a special case, which provides the
fully nonlinear counterpoint to the weakly nonlinear sech2-type solitons associated
with the Korteweg–de Vries equation, and indicates the parameter regimes in which
solitons may exist.
Propagation of electromagnetically generated wake fields in inhomogeneous magnetized plasmas
Authors: SERVIN MARTIN , BRODIN GERT
Published: October 2002

Generation of wake fields by a short electromagnetic pulse in a plasma
with an inhomogeneous background magnetic field and density profile is considered,
and a wave equation is derived. Transmission and reflection coefficients are
calculated in a medium with sharp discontinuities. Particular attention is focused
on examples where the longitudinal part of the electromagnetic field is amplified for
the transmitted wave. Furthermore, it is noted that the wake field can propagate
out of the plasma and thereby provide information about the electron density profile.
A method for reconstructing the background density profile from a measured
wake field spectrum is proposed and a numerical example is given.
Predicting climate change effects on marine biodiversity: comparison of recent and fossil molluscan death assemblages
Authors: Warwick R.M. , Turk S.M.
Published: October 2002

The death assemblage of molluscs (gastropods and bivalves) from the sandy beach at Harlyn Bay, north Cornwall is shown to be fully representative of the biodiversity of the regional species pool from all habitat types. The biodiversity measures used are average taxonomic distinctness (Δ+, the average degree to which species in an assemblage are related to each other) and variation in taxonomic distinctness (Λ+, the evenness of the spread of taxa across the taxonomic spectrum). A late Pliocene fossil assemblage of molluscs from St Erth Pits, north Cornwall, UK, is also not significantly different in biodiversity, in these terms, from the present-day regional species pool. The climate in the late Pliocene was similar to the present-day Mediterranean, suggesting that predicted changes in climate, by the end of this century, will not affect molluscan biodiversity, although the species composition will undoubtedly change.
CONSTITUTIONAL REGULATION OF THE FOREIGN AFFAIRS POWER IN KENYA: A COMPARATIVE ASSESSMENT
Authors: OJWANG J. B. , FRANCESCHI LUIS G.
Published: October 2002

This article is concerned with a specialized area of constitutional theory and practice, namely the regulation of the foreign affairs powers. Foreign affairs is a wide term which expresses more than mere relations. “Affairs” include matters and things, as well as relationships and a constitutional grant of legitimate plenary powerr. This entails that foreign affairs are matters relating to foreign countries, i.e. affairs other than domestic and, specifically, matters having to do with the interests of the home country in foreign countries. In this context, foreign affairs may be identified as a function. A function is an activity specially fitted for, appropriate to or expected of some particular type of operation because of its peculiar nature, or qualifications. The foreign affairs function, thus, as Bonfield says, may be in an activity specially fitted for, appropriate to, or expected of international relations—the interests of a state in foreign states—due to the peculiar nature or attributes of such relations. In addition, “power” may be defined as the competence to decide and act that is attached to a specific function. Hence the foreign affairs power is the competenbce to decide and act in matters having to do with the interests of the home state in foreing states. It is made up principally of the following elements: treay making, diplomatic relations, recognition of states and governments, and war and peace. Appropriate regulation of the elements of the foreign affairs power is a vital element of good governance in any particular state.
Anglo-Saxon prognostics in context:
a survey and handlist of manuscripts
Authors: Liuzza Roy Michael
Published: October 2002

The various Latin and Old English texts which have come to be called ‘prognostics’
have not, in general, been well served by scholars. For some texts the only
available edition is Oswald Cockayne's Leechdoms, Wortcunning, and Starcraft of
Early England from 1864-6; most others are available only in the broad but somewhat
unsystematic series of articles published by Max Förster in Archiv für das
Studium der neueren Sprachen und Literaturen in the 1910s and 1920s. Anselm
Hughes does not include the eight prognostic texts in Cambridge, Corpus Christi
College 391 in his otherwise fairly thorough edition of much of that manuscript; Peter Baker and Michael Lapidge omit any discussion of such texts from
their excellent survey of the history of the computus in the preface to their
edition of Byrhtferth's Enchiridion. The mid-eleventh-century Christ Church
manuscript now known as London, British Library, Cotton Tiberius A. iii has
attracted the notice of many fine scholars, including liturgists, linguists and
monastic and art historians, who have been drawn to the series of texts at the
beginning of the manuscript (fols. 117-73 and 2-27), including two magnicent
full-page drawings (117v and 2v) and glossed copies of the Benedictine Rule and
the Regularis Concordia. Helmut Gneuss describes this carefully presented series of interrelated texts as ‘a compendium of the Benedictine Reform movements
in Carolingian Francia and in tenth-century England’; Robert Deshman has
argued that the very sequence of texts is ‘laden with meaning’. Despite their
appreciation of these manuscript sequences, however, few scholars have
included in their study of this material the eighteen prognostic texts which
follow the Regularis Concordia in the manuscript (27v-47), though most of these
are in the same hand and are arranged, it may be argued, with equal care.
Reconsidering Theatre-Making in South Africa: A Study of Theatre in Education in Cape Schools
Authors: Morris Gay
Published: October 2002

The task of Theatre in Education (TIE) performers is examined in relation to what I have witnessed in TIE programmes in South Africa, found in reports written by students and ideas proposed by theatre theorists. The four contextual frames, which John O'Toole maintains are at work in TIE (namely neighbourhood, venue, audience availability and the world of the play), provide a workable configuration through which to examine the effects of each of these on performance. The interaction between the performers, the performance site and the audience in TIE promises the possibility of a more flexible approach to theatre. Creative opportunities arise that should be utilized, not only in TIE, by a variety of theatre-makers in South Africa.
Preferential association of the heat-stable enterotoxin gene (stn) with environmental strains of Vibrio cholerae belonging to the O14 serogroup
Authors: SARKAR B. , BHATTACHARYA T. , RAMAMURTHY T. , SHIMADA T. , TAKEDA Y. , BALAKRISH NAIR G.
Published: October 2002

Toxigenic Vibrio cholerae O1 and O139 serogroups have the capacity of causing epidemic and pandemic cholera but are infrequently found in the environment. The other serogroups are abundant in aquatic environments but do not possess the virulence genes necessary for causing the disease. Of the 559 environmental strains of V. cholerae, collected during different periods from environmental samples in Calcutta, 9 (1.6%) harboured the heat-stable enterotoxin gene (stn). Six of the 9 strains belonged to the O14 serogroup. Thus, V. cholerae strains carrying the stn gene revealed preferential association with the O14 serogroup. Three of the six strains harboured the tcpA gene of the E1 Tor type, which is an unusual feature among environmental V. cholerae strains. A strain that possessed the E1 Tor type tcpA also had the CTX prophage. Pulsed field gel electrophoresis (PFGE) revealed that the stn gene positive O14 strains of V. cholerae were not clonal.
Interstitial Po2 Determination by Phosphorescence Quenching Microscopy
Authors: SMITH LANE M. , GOLUB ALEKSANDER S. , PITTMAN ROLAND N.
Published: October 2002

Objective: This study introduces the technique of microinjection of phosphor probe into skeletal muscle tissue to determine oxygen tension (Po2) in the interstitium by phosphorescence quenching microscopy.

Method: The spinotrapezius muscle of Wistar‐Kyoto rats weighing 240–280 g was surgically isolated and underwent the microinjection procedure. We measured the spatial distribution of phosphor probe 10, 30, and 80 minutes after injection; the tissue Po2 at sites adjacent to arteriolar and venular microvessels; and the decline in tissue Po2 during a 3‐minute period of 8‐Hz contraction.

Results: The phosphorescence signal from the probe was undetectable outside a 2.5‐mm radius from the site of injection at the 10‐minute time point, increased to measurable values after 30 minutes, and was double the 30‐minute intensity value after 80 minutes. When used to measure periarteriolar Po2, the tissue microinjection technique demonstrated a nonlinear fall in tissue Po2 with distance away from secondary arterioles (30–40 µm diameter). Conversely, perivenular tissue Po2 increased in a nonlinear manner with distance away from secondary venules (60–70 µm diameter). The tissue Po2 at distances of 16 µm and greater from both types of secondary microvessels was significantly different from values taken directly over the centerline of these microvessels. During muscle contraction, the Po2 fell from a mean precontraction value of 28.3 ± 4.9 mmHg to 8.2 ± 0.9 mmHg at the end of the contraction period.

Conclusions: These observations indicate that the microinjection technique yields values for tissue Po2 that are in good agreement with previously published results using oxygen microelectrodes.
The Abscisic Acid-Responsive Kinase PKABA1 Interacts with a Seed-Specific Abscisic Acid Response Element-Binding Factor, TaABF, and Phosphorylates TaABF Peptide Sequences
Authors: Johnson Russell R. , Wagner Ryan L. , Verhey Steven D. , Walker-Simmons Mary K.
Published: October 2002

The abscisic acid (ABA)-induced protein kinase PKABA1 is present in dormant seeds and is a component of the signal transduction pathway leading to ABA-suppressed gene expression in cereal grains. We have identified a member of the ABA response element-binding factor (ABF) family of basic leucine zipper transcription factors from wheat (Triticum aestivum) that is specifically bound by PKABA1. This protein (TaABF) has highest sequence similarity to the Arabidopsis ABA response protein ABI5. In two-hybrid assays TaABF bound only to PKABA1, but not to a mutant version of PKABA1 lacking the nucleotide binding domain, suggesting that binding of TaABF requires prior binding of ATP as would be expected for binding of a protein substrate by a protein kinase. TaABF mRNA accumulated together with PKABA1 mRNA during wheat grain maturation and dormancy acquisition and TaABFtranscripts increased transiently during imbibition of dormant grains. In contrast to PKABA1 mRNA, TaABF mRNA is seed specific and did not accumulate in vegetative tissues in response to stress or ABA application. PKABA1 produced in transformed cell lines was able to phosphorylate synthetic peptides representing three specific regions of TaABF. These data suggest that TaABF may serve as a physiological substrate for PKABA1 in the ABA signal transduction pathway during grain maturation, dormancy expression, and ABA-suppressed gene expression.
Short Integuments1/suspensor1/carpel Factory, a Dicer Homolog, Is a Maternal Effect Gene Required for Embryo Development in Arabidopsis
Authors: Golden Teresa A. , Schauer Stephen E. , Lang Jean D. , Pien Stéphane , Mushegian Arcady R. , Grossniklaus Ueli , Meinke David W. , Ray Animesh
Published: October 2002

The importance of maternal cells in controlling early embryogenesis is well understood in animal development, yet in plants the precise role of maternal cells in embryogenesis is unclear. We demonstrated previously that maternal activity of theSIN1 (SHORT INTEGUMENTS1) gene of Arabidopsis is essential for embryo pattern formation and viability, and that its postembryonic activity is required for several processes in reproductive development, including flowering time control and ovule morphogenesis. Here, we report the cloning of SIN1, and demonstrate its identity to the CAF (CARPEL FACTORY) gene important for normal flower morphogenesis and to the SUS1 (SUSPENSOR1) gene essential for embryogenesis.SIN1/SUS1/CAF has sequence similarity to the Drosophila melanogaster geneDicer, which encodes a multidomain ribonuclease specific for double-stranded RNA, first identified by its role in RNA silencing. The Dicer protein is essential for temporal control of development in animals, through the processing of small RNA hairpins that in turn inhibit the translation of target mRNAs. Structural modeling of the wild-type and sin1 mutant proteins indicates that the RNA helicase domain of SIN1/SUS1/CAF is important for function. The mRNA was detected in floral meristems, ovules, and early embryos, consistent with the mutant phenotypes. A 3.3-kb region 5′ of theSIN1/SUS1/CAF gene shows asymmetric parent-of-origin activity in the embryo: It confers transcriptional activation of a reporter gene in early embryos only when transmitted through the maternal gamete. These results suggest that maternal SIN1/SUS1/CAF functions early in Arabidopsis development, presumably through posttranscriptional regulation of specific mRNA molecules.
The KNAT2 Homeodomain Protein Interacts with Ethylene and Cytokinin Signaling
Authors: Hamant Olivier , Nogué Fabien , Belles-Boix Enric , Jublot Delphine , Grandjean Olivier , Traas Jan , Pautot Véronique
Published: October 2002

Using a transgenic line that overexpresses a fusion of the KNAT2 (KNOTTED-like Arabidopsis) homeodomain protein and the hormone-binding domain of the glucocorticoid receptor (GR), we have investigated the possible relations between KNAT2 and various hormones. Upon activation of the KNAT2-GR fusion, we observed a delayed senescence of the leaves and a higher rate of shoot initiation, two processes that are also induced by cytokinins and inhibited by ethylene. Furthermore, the activation of the KNAT2-GR fusion induced lobing of the leaves. This feature was partially suppressed by treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, or by the constitutive ethylene response ctr1mutation. Conversely, some phenotypic traits of the ctr1mutant were suppressed by the activation of the KNAT2-GR fusion. These data suggest that KNAT2 acts synergistically with cytokinins and antagonistically with ethylene. In the shoot apical meristem, the KNAT2 gene is expressed in the L3 layer and the rib zone. 1-Aminocyclopropane-1-carboxylic acid treatment restricted the KNAT2 expression domain in the shoot apical meristem and reduced the number of cells in the L3. The latter effect was suppressed by the activation of the KNAT2-GR construct. Conversely, the KNAT2 gene expression domain was enlarged in the ethylene-resistant etr1-1 mutant or in response to cytokinin treatment. These data suggest that ethylene and cytokinins act antagonistically in the meristem via KNAT2 to regulate the meristem activity.
Molecular Characterization of the Cotton GhTUB1 Gene That Is Preferentially Expressed in Fiber
Authors: Li Xue-Bao , Cai Lin , Cheng Ning-Hui , Liu Jian-Wei
Published: October 2002

Each fiber of cotton (Gossypium hirsutum) is a single epidermal cell that rapidly elongates to 2.5 to 3.0 cm from the ovule surface within about 16 d after anthesis. A large number of genes are required for fiber differentiation and development, but so far, little is known about how these genes control and regulate the process of fiber development. To investigate gene expression patterns in fiber, a cDNA, GhTUB1, encoding β-tubulin was isolated from a cotton fiber cDNA library. The analyses of RNA northern-blot hybridization and reverse transcriptase-polymerase chain reaction demonstrated that GhTUB1 transcripts preferentially accumulated at high levels in fiber, at low levels in ovules at the early stage of cotton boll development, and at very low levels in other tissues of cotton. The correspondingGhTUB1 gene including the promoter region was isolated by screening a cotton genomic DNA library. To demonstrate the specificity of the GhTUB1 promoter, the 5′-flanking region including the promoter and 5′-untranslated region was fused with the β-glucuronidase reporter gene. The expression of the reporter chimera was examined in a large number of transgenic cotton plants. Histochemical assays demonstrated thatGhTUB1::β-glucuronidasefusion genes were expressed preferentially at high levels in fiber and primary root tip of 1- to 3-d-old seedlings and at low levels in other tissues such as ovule, pollen, seedling cotyledon, and root basal portion. The results suggested that the GhTUB1 gene may play a distinct and required role in fiber development. In addition, the GhTUB1 promoter may have great potential for cotton improvement by genetic engineering.