bluuebunny/crossref_metadata_2025 huggingface dataset:
An application of linear programming in the defence environment
Authors: Walmsley N. S. , Hearn P.
Published: December 2003

Operational analysis (OA) techniques are used extensively by the Ministry of Defence (MoD) to inform their decision‐making process. One particular type of OA study frequently undertaken is a balance‐of‐investment (BoI) study. This paper focuses on a recent BoI study whose aim was to identify the optimum (i.e. most cost effective) mix of vehicles that should be procured to fill a large number of identified requirements/roles. There will be a description of the methodology employed, highlighting the formulation and application of mixed integer linear programming (MILP) techniques, alongside a brief discussion of the implication of the results and other issues associated with the complexity of the problem.
Foresight and governance: a problem‐oriented methodology (GOVSIGHT)
Authors: Valadares Tavares L.
Published: December 2003

A problem‐oriented methodology for technology foresight is proposed in this paper stemming from the Portuguese project ‘Engenharia e Tecnologia 2000’ and oriented to support governmental policy making. This methodology includes several models from operational research to classify knowledge and to assess its impact on societal development, contributing to a better relationship between science and society, and to implement a new paradigm of development based on knowledge society.
Improving public information about large hydroelectric dams: Case studies in France and West Africa
Authors: Faure Armelle
Published: December 2003

It is becoming more common for public authorities in charge of dam construction and management to inform the population living in the area soon to be submerged by a proposed dam. However, populations living further downstream along a river to be dammed, have often been left to find out by chance, despite the fact that the changes to the river flow regime will have an important impact on their lives, sometimes serious negative impacts. This article makes a comparison between two dams, one at Bort‐les‐Orgues across the upper Dordogne River in southern France, the other the Bagré Dam over the Nakambé (or White Volta) River in south‐eastern Burkina Faso. The article discusses dam construction and operation from the point of view of the concerned populations living in the reservoir and downstream areas.

In 2000, a study was carried out in the Dordogne Valley to ascertain downstream impacts of dam operations and information needs of the population. Suggestions from local river users related mostly to improving public information about predicted and actual flow rates and actual flow in real time along the 300 km course of the Dordogne between the dams and the estuary. Such information should be disseminated as widely as possible through available media, including the Internet, and also displayed visibly in key locations along the length of the river.
Energy for sustainable development: Review of national and international energy policies
Authors: Gururaja J.
Published: December 2003

This article presents an assessment of the effectiveness of national and international energy policies directed toward the objectives of sustainable development contained in Agenda 21. Following a brief overview of energy and transport sector trends over the past ten years, the article discusses whether and to what extent energy policies for sustainable development have impacted on poverty reduction, energy security, equitable access to energy, and transition to a more efficient and environmentally sound energy system.

The impact of policies is assessed considering that such a transition involves appropriate combinations of energy efficient technologies and usage patterns, wider use of renewable energy, and gradual induction of advanced energy technologies. The article then examines the extent to which such policies have been based on integrated assessments of the needs and priorities in economic growth, social development and environmental protection and identifies some of the main constraints and barriers hampering the implementation of energy for sustainable development. The article also examines whether decision‐making processes ensure multi‐stakeholder participation in policy development and support a fair sharing of commitments, responsibilities and benefits among the participating stakeholders in policy implementation. Selected case studies of policies that have made a tangible difference in promoting energy for sustainable development are outlined.

Finally the article discusses the challenges facing energy for sustainable development and discusses various options to accelerate the implementation of its goals.
Informal coal mining in Eastern India: Evidence from the Raniganj Coalbelt
Authors: Lahiri‐Dutt Kuntala
Published: December 2003

Unauthorized mines are not uncommon in mineral‐rich regions of poorer countries, and India is no exception. Whether they constitute merely a law and order problem including safety issues, or there are important social and economic questions involved has yet to be thrashed out. The mining industry, at regional, national and international levels, is ambivalent towards such mining, tending to draw attention away from their informal nature to the size factor.

This article looks into the problem of such informal mining in the light of empirical surveys in eastern Indian collieries. These are called peoples’ mines and they serve a significant purpose in local economies. The article's thesis is that peasant communities are trying to claim back a portion of the local resources lost to them through appropriation by mining companies thus re‐asserting their traditional rights to local mineral resources. In conclusion, the need for a new moral economy for mining regions is stressed: an economy in which local communities will play a powerful role.
Towards a smallholder hydrology for equitable and sustainable water management
Authors: Vincent Linden F
Published: December 2003

Situations of water scarcity challenge sustainability and threaten small users’ access to water. In response to this problem, there has been a search for a method of hydrological analysis that can better represent the needs of small water users. While this search is rooted in the debate favouring a more participatory and inclusive allocation of the resource, it also requires a new focus on smallholder hydrology that can confront the gaps and biases found in current hydrological practices in many countries. This article looks at past hydrological practices and also at results of recent studies, highlighting the perspective of smallholder irrigators in surface water planning in Zimbabwe, and groundwater planning in India. These case studies show that wider social forces, not always best science, drive hydrological practices. However, new frameworks focusing on the water user can emerge for more equitable and sustainable water management.
Refuting the paradigm of water services privatisation
Authors: Hukka Jarmo J , Katko Tapio S
Published: December 2003

The aim of this article is to question the fundamental assumptions behind privatisation and public–private partnerships. The article shows that instead of radically increasing private sector involvement, public sector reforms should be seriously considered. Public–private partnerships should be implemented so that the strengths of all the stakeholders may be fully utilised.
The need for flexibility in freshwater treaty regimes
Authors: McCaffrey Stephen C
Published: December 2003

Shrinking freshwater supplies pose particular threats in international drainage basins, which serve some 40% of the global population and account for around 60% of the world’s river flows. The use and management of these basins are increasingly governed by treaties between the riparian states. While the rules of international law, properly understood, are sufficiently flexible to permit adaptation to changing conditions such as development, population growth and climate change, treaties are essentially rigid instruments that are modifiable only under certain limited conditions. Countries should take this fact into account in designing the regimes to govern their shared freshwater resources, including joint management institutions.
Sharing waters: Post‐Rio international water management
Authors: Giordano Meredith A , Wolf Aaron T
Published: December 2003

Transcending human‐defined political and administrative boundaries, the world’s transboundary freshwater resources pose particularly challenging management problems. Water resource users at all scales frequently find themselves in direct competition for this economic and life‐sustaining resource, in turn creating tensions, and indeed conflict, over water supply, allocation, and quality. At the international scale, where the potential for conflict is of particular concern, significant efforts are underway to promote greater cooperation in the world’s international river basins, with notable achievements in the past decade following the Dublin and Rio conferences. Over the past ten years, the international community has adopted conventions, declarations, and legal statements concerning the management of international waters, while basin communities have established numerous new basin institutions. Despite these developments, significant vulnerabilities remain. Many international basins still lack any type of joint management structure, and certain fundamental management components are noticeably absent from those that do. An understanding of these weaknesses, however, offers an opportunity for both the international and basin communities to better respond to the specific institution‐building needs of basin communities and thereby foster broader cooperation over the world’s international water resources.
Psychosocial Adjustment Over a Two–Year Period in Children Referred for Learning Problems: Risk, Resilience, and Adaptation
Authors: Sorensen Lisa G. , Forbes Peter W. , Bernstein Jane H. , Weiler Michael D. , Mitchell William M. , Waber Deborah P.
Published: December 2003

Children with learning difficulties have an increased prevalence of psychosocial adjustment problems. We hypothesized that within the context of a risk and resilience model contextual variables influence adjustment, over and above any effects of academic performance. The Behavior Assessment System for Children (BASC) was used to evaluate the relationship between psychosocial adjustment, changes in academic skills, and contextual factors longitudinally over a two–year period in 100 children (ages 7 to 11) referred for learning problems. Although there was little improvement in academic skills, contextual factors contributed to observed psychosocial outcome. Different factors were salient for parents, teachers, and children. Context–derived vulnerability and protective factors can be important determinants of adjustment in children with learning problems, even though the academic difficulties can remain chronic.
Spelling of Inflected Verb Morphology in Children with Spelling Deficits
Authors: Hauerwas Laura Boynton , Walker Joanne
Published: December 2003

Children with spelling deficits demonstrate significant difficulty using inflectional morphology in their writing. This study investigated whether phonological deficits account for these pronounced difficulties or if they are more accurately explained by limitations in morphological or orthographic awareness. Twenty–six 11—13–year–old children with spelling deficits, 31 younger spelling–level–matched children, and 31 age–matched children were asked to spell a series of verbs with past tense and progressive markers in dictated sentences and in list form. Performance on spelling tasks was compared to performance on phonological, morphological, and orthographic awareness tasks. Results suggest that children with spelling deficits have significant difficulty including inflections as well as spelling inflections and base words. Difficulty was most pronounced in a sentence context. Ability to spell inflectional forms was related to variation in morphological awareness in children with spelling deficits and to variation in orthographic awareness in spelling–level–matched children.
Graphic Organizers Applied to Higher–Level Secondary Mathematics
Authors: Ives Bob , Hoy Cheri
Published: December 2003

A review of popular approaches to teaching mathematics that emphasize nonverbal skills, such as using manipulatives or problem–solving schema, shows that they are often not immediately applicable to some important areas of secondary algebra. However, graphic organizers in various forms have been widely suggested and researched as an intervention approach to improve reading comprehension. In this article, suggestions for modifying graphic organizers to make them more applicable to teaching higher–level mathematics concepts and procedures are proposed. Using an appropriately modified graphic organizer to teach higher–level mathematics skills may help students with relatively weak verbal skills and strong nonverbal reasoning skills to be more successful in mathematics. This subgroup of students with learning disabilities has been consistently identified in several schemes for subtyping mathematical disorders developed from empirical evidence. Excerpts of two sample scripted lessons based on this approach, one for the solving of systems of linear equations in three variables and one for the concept of negative integer exponents, are included.
Promoting Success in High School World History: Peer Tutoring Versus Guided Notes
Authors: Mastropieri Margo A. , Scruggs Thomas E. , Spencer Vicky , Fontana Judith
Published: December 2003

The purpose of this investigation was to compare qualitative and quantitative outcomes associated with peer tutoring versus teacher–directed guided notes in world history for secondary–level students with mild disabilities. Sixteen students with mild disabilities (15 of whom had learning disabilities) participated in a nine–week quarter of one of the two instructional conditions. The same special education teachers taught students during world history classes. Measures included pre– and posttests of reading fluency, comprehension strategies, and content tests, including end–of–chapter tests, cumulative–delayed–recall tests, and a delayed–recall end–of–year final exam covering the entire academic year. In addition, qualitative procedures were employed, including interviews of teachers and students regarding their instructional preferences. Findings indicated that students who participated in peer tutoring significantly outperformed those who participated in the guided–notes condition on content–area tests. No significant differences were obtained on oral–reading–fluency measures, but students in the tutoring condition performed significantly better at using a reading comprehension summarization strategy independently, and at remembering the strategy steps. Results of student interviews suggested that students responded positively overall to tutoring and guided notes, and provided specific relevant insights on each procedure. Students in the tutoring condition indicated that the time spent tutoring felt like one of the shortest academic quarters for them. Findings are discussed with respect to both benefits and challenges associated with implementing peer tutoring in high school special education content–area classes.
General and Specific Issues for Researchers’ Consideration in Applying the Risk and Resilience Framework to the Social Domain of Learning Disabilities
Authors: Wong Bernice Y. L.
Published: December 2003

In this article, I discuss several general and specific issues that pertain to the risk and resilience framework. I propose that these issues deserve consideration by researchers using or interested in using the risk and resilience framework to guide their research in the social domain of learning disabilities. General issues discussed include: (1) integrating current research findings with those from prior longitudinal research by Emmy Werner and her associates, and from research in the 1980s and 1990s on problems in social perception and communication in children with learning disabilities; (2) measurement problems; and (3) the need for more differentiation in research regarding gender and the severity of learning disabilities. The specific issues discussed include: the need to continue to search for potential risk and protective factors; the need to research mediating processes or mechanisms that render a factor a risk or a protection; and the nature of intervention research.
Resilience and Multiple Risks: A Response to Bernice Wong
Authors: Wiener Judith
Published: December 2003

This article is an endorsement of Wong's proposal that risk and resilience models provide a framework for research and practice with regard to the social and emotional functioning of children with learning disabilities. Future research should include an examination of the impact of family functioning and parenting, and peer victimization. We need to be cognizant of findings in developmental psychopathology that single risk factors seldom have a massive impact on development; children who are at risk typically experience chronic multiple risks. Consequently, we cannot explain the social and emotional functioning of children with learning disabilities without understanding the reciprocal interaction between children and their environments.
Resilience Model among Individuals with Learning Disabilities: Proximal and Distal Influences
Authors: Margalit Malka
Published: December 2003

Development may be conceptualized as a process of repeated resilient reintegration, and resilience research is expected to identify the complex transactions and processes among internal and external (risk and protective) factors involved in that process. Through presenting a critical review of related research, Wong's article demonstrates the ability of youngsters with learning disabilities (LD) to challenge their difficulties. Wong's perspective helps clarify current conceptual inconsistencies and provides constructive directions for future inquiries in LD resilience research. The present commentary emphasizes two mediating factors within the third wave of resilience research: the critical role of emotions as inner sources of energy and the importance of reciprocity in relations with both adults and peers.
Response to Wong's Article
Authors: Cosden Merith
Published: December 2003

This commentary supports Wong's thesis regarding the potential of the risk and resilience framework for the field of learning disabilities (LD), while suggesting several specific areas in which longitudinal study with a risk and resilience framework would be particularly beneficial. It is recommended that focus be placed on identification of risk and protective factors for developmental outcomes in children already identified with LD. Application of this approach to analyzing friendship strategies is described, particularly as it might redirect study to the development of shared interests among children with and without LD. Using longitudinal research to identify positive, naturally occurring family practices, and translating these practices into interventions for families in which they do not naturally occur, is also discussed.
Studying Social Development and Learning Disabilities is Not for the Faint–Hearted: Comments on the Risk/Resilience Framework
Authors: Donahue Mavis L. , Pearl Ruth
Published: December 2003

Studying social dimensions of learning disabilities is not for the faint–hearted, in light of the multiple and interactive characteristics of these students and their social/cultural environments. Given the allure of the risk/resilience lens to make sense of these complexities, it would be easy to embrace these concepts too hastily. Four questions seem particularly important: What do we mean by risk and resilience factors? How do we characterize learning disabilities as risk factors?“At risk” for what? How should this framework guide intervention efforts? Rigorous thinking about these issues may enhance the promise of risk/resilience models for future research on social development.
The Applicability of the Risk and Resilience Model to Social Problems of Students with Learning Disabilities: Response to Bernice Wong
Authors: Bryan Tanis
Published: December 2003

The purpose of this article is to respond to Bernice Wong's questions regarding the efficacy of the risk and resilience model for studying social problems in students with learning disabilities. Two factors render this framework particularly inviting to special education researchers. First, it is inherently optimistic because it assumes that once we identify factors that contribute to resilience, we can train less–resistant individuals to be more resilient. As such, it moves us away from deficit models to empowering models. Second, the model forces us to look beyond the characteristics of the individual to consider external factors that have a significant influence on development and behavior. At the same time, however, we still need to advance our knowledge regarding the basic dimensions of social problems among students with learning disabilities. Hence, this article argues for multiple approaches to advancing knowledge about students with learning disabilities.
Effects of Manipulative Instruction on Solving Area and Perimeter Problems by Students with Learning Disabilities
Authors: Cass Mike , Cates Dennis , Smith Michelle , Jackson Cynthia
Published: December 2003

A multiple baseline design was employed to test the effect of manipulative instruction on the perimeter and area problem–solving performance of middle and high school students who had been diagnosed with LD in the area of mathematics. Modeling, prompting/guided practice, and independent practice in conjunction with manipulative training were employed to teach both perimeter and area problem–solving skills. Analysis of data revealed that the students rapidly acquired the problem–solving–skills, maintained these skills over a two–month period, and transferred these skills to a paper and pencil problem–solving format. This research extends previous findings by revealing that use of concrete manipulatives promotes the long–term maintenance of skills.
Teaching Algebra to Students with Learning Difficulties: An Investigation of an Explicit Instruction Model
Authors: Witzel Bradley S. , Mercer Cecil D. , Miller M. David
Published: December 2003

Thirty–four matched pairs of sixth– and seventh–grade students were selected from 358 participants in a comparison of an explicit concrete–to–representational–to–abstract (CRA) sequence of instruction with traditional instruction for teaching algebraic transformation equations. Each pair of students had been previously labeled with a specific learning disability or as at risk for difficulties in algebra. Students were matched according to achievement score, age, pretest score, and class performance. The same math teacher taught both members of each matched pair, but in different classes. All students were taught in inclusive settings under the instruction of a middle school mathematics teacher. Results indicated that students who learned how to solve algebra transformation equations through CRA outperformed peers receiving traditional instruction on both postinstruction and follow–up tests. Additionally, error pattern analysis indicated that students who used the CRA sequence of instruction performed fewer procedural errors when solving for variables.
Persons with Learning Disabilities in the Workplace: What We Know So Far in the Americans with Disabilities Act Era
Authors: Gerber Paul J. , Price Lynda A.
Published: December 2003

Since the Americans with Disabilities Act (ADA) was passed in 1990 and implemented in 1992, there has been little research to discover the realities of the workplace for adults with learning disabilities. There is a body of knowledge, albeit sparse in scope, that provides guidance for learning disabilities professionals, employers, and individuals with learning disabilities. Empirical studies are synthesized from the past 12 years to convey the perspectives of employees with learning disabilities and their employers. Issues that require further research are outlined.
Institutional Investors and Information Asymmetry: An Event Study of Self‐Tender Offers
Authors: O'Neill Michele , Swisher Judith
Published: December 2003

Our research compares the asymmetric information costs of firms with low levels of institutional ownership to those with high levels. We use self‐tender offers as an information event. Our results show that higher institutional ownership, particularly a higher number of institutional investors, is associated with a lower degree of informed trading. These results persist even after we control for differences in trading activity among our sample firms.
The Impact of Trust‐Preferred Issuance on Bank Default Risk and Cash Flow: Evidence from the Debt and Equity Securities Markets
Authors: Harvey Keith D. , Collins M. Cary , Wansley James W.
Published: December 2003

Trust‐preferred stock is a debt‐equity hybrid that offers the tax deductibility of dividends but is treated as equity capital by bank regulators and rating agencies. The purpose of this paper is to examine whether holders of bank debt securities benefit from trust‐preferred issuance in the form of lower default premia and whether bank shareholders benefit from the tax deductibility of trust‐preferred dividends. Using daily returns surrounding the Federal Reserve's announcement that trust‐preferred securities would be included as a component of commercial banks' Tier I equity capital, we find evidence to support both hypotheses.
Evidence on the Mean‐Reverting Tendencies of Closed‐End Fund Discounts
Authors: Gasbarro Dominic , Johnson Richard D. , Zumwalt J. Kenton
Published: December 2003

Closed‐end fund (CEF) discounts vary widely over time due to changes in share price, net asset value (NAV), or both. Prior studies suggest discounts are mean‐reverting. We examine the mean‐reversion issue by employing cointegration procedures. Specifically, we identify bond and equity CEFs that exhibit stationary time‐series properties and find statistically significant error correction terms that quantify the speed of mean reversion. The results indicate that mean reversion is caused by changes in both share price and NAVs. However, CEFs can only provide excess returns when the discount narrows due to share price increases.
Trade Imbalances and Inventory Effects in Long‐term S&P 500 Index Options
Authors: Bharadwaj Anu , Wiggins James B.
Published: December 2003

This article investigates how trade imbalances affect prices in the S&P 500 Long‐term Equity Anticipation Securities (LEAPS) market. From 1994 to 1996, put volume was 30 times higher than call volume, and public purchases of puts vastly outnumbered sales. We find that LEAPS put quotes are revised following trade imbalances by more than can be explained by information effects, suggesting that put prices are subject to price pressure or inventory effects. The results suggest market frictions are important in the pricing of options, at least in settings in which arbitrage is particularly costly and public demand leans toward one type of order.
Creating Fama and French Factors with Style
Authors: Faff Robert W.
Published: December 2003

This paper utilizes Frank Russell style portfolios to create useful proxies for the Fama and French (1992) factors. The proxy‐mimicking portfolios are shown to represent a pervasive source of exposure across U.S. industry portfolios and to generally possess similar properties to those utilized in the finance literature. Further, a set of multivariate asset‐pricing tests of the three‐factor Fama and French asset‐pricing (FF) model based on the proxy factors fails to reject the model. However, these tests do not reveal strong evidence of significantly positive risk premiums, particularly in the case of the size and book‐to‐market factors.
Jean‐Charles Langlois's Panorama of Algiers (1833) and the Prospective Colonial Landscape
Authors: Zarobell John
Published: December 2003

This article considers one of the first representations of colonial Algeria, Jean‐Charles Langlois's Panorama of Algiers of 1833. It examines studies and sketches made by Langlois in Algiers, resulting from his participation in the conquest in 1830 and a later visit in 1832 in preparation for the now‐destroyed panorama. Consideration of the responses of contemporary French writers illuminates their distinctions between paintings and panoramas. In arguing that the specific perceptual mechanism of the panorama assisted fantasies of domination that helped to shape France's colonial mission, this article argues that the relationship between viewer and spectacle posited by the Panorama of Algiers serves as a prototype for the representation of colonial landscape in nineteenth‐century France.
Doubles and Desire: Anatomies of masculinity in the later nineteenth century
Authors: Callen Anthea
Published: December 2003

This article explores duality and splitting in representations of the male body, stressing as a crucial factor the issue of social class. Focusing on the ‘golden age’ of doubles in the 1880s and 1890s, my study crosses the boundaries between France and Britain, art and medicine, visual images and literature, to analyse François Sallé's monumental painting of male homosociality, The Anatomy Class at the Ecole des Beaux‐Arts (1888); I suggest parallels with the male doubling identified in R.L. Stevenson's novella The Strange Case of Dr Jekyll and Mr Hyde (1886). Addressing representations of medical professionals, I position my material within nineteenth‐century clinical discourse (Foucault), and propose readings that develop the medical gaze as an alternative visual economy to that of the modern Parisian flâneur. Linking anatomy and dissection to the performance of striptease, I argue that Sallé's painting represents a scene in which unsuppressed homoerotic pleasure allows the visibility of homosexual desire, and permeability of sexual categories.
The Political Art of Jacques‐Louis David and his Modern‐Day American Successors
Authors: Carrier David
Published: December 2003

Until relatively recently, Jacques‐Louis David was a famous, relatively well‐understood painter. Thanks to Thomas Crow, and a number of recent historians, his art now has come to seem much more complex. According to these writers, David's pre‐Revolutionary paintings make subtle comments on French politics of the Revolutionary period. I demonstrate that this way of thinking cannot be understood without acknowledging the intense desire of recent American critics that there be art which is aesthetically significant and politically critical. Crow's account of David, so I argue, projects back into the 1780s important concerns of American art writers in the 1980s.
Doubles and Desire: anatomies of masculinity in the later nineteenth century
Authors: Callen Anthea
Published: December 2003

This article explores duality and splitting in representations of the male body, stressing as a crucial factor the issue of social class. Focusing on the ‘golden age’ of doubles in the 1880s and 1890s, my study crosses the boundaries between France and Britain, art and medicine, visual images and literature, to analyse François Sallé's monumental painting of male homosociality, The Anatomy Class at the Ecole des Beaux‐Arts (1888); I suggest parallels with the male doubling identified in R.L. Stevenson's novella The Strange Case of Dr Jekyll and Mr Hyde (1886). Addressing representations of medical professionals, I position my material within nineteenth‐century clinical discourse (Foucault), and propose readings that develop the medical gaze as an alternative visual economy to that of the modern Parisian flâneur. Linking anatomy and dissection to the performance of striptease, I argue that Sallé's painting represents a scene in which unsuppressed homoerotic pleasure allows the visibility of homosexual desire, and permeability of sexual categories.
Oxidative and premature skin ageing
Authors: Biesalski H. K. , Berneburg M. , Grune T. , Kerscher M. , Krutmann J. , Raab W. , Reimann J. , Reuther T. , Robert L. , Schwarz T.
Published: December 2003

Abstract: To elucidate the scientific state of the art with respect to the role of nutrition in skin ageing, nine experts from different disciplines discussed the role of micronutrients on ‘oxidative and premature skin ageing’. In this 25th Hohenheim Consensus Meeting, 13 questions were discussed and, based on published valid data, answered by mutual agreement. The consensus answers achieved during the meeting are justified by a scientific background text. The importance ofin vitroandin vivomodels regarding oxidative and premature skin ageing was critically evaluated. There was a special focus on prevention and intervention of skin ageing with nutrition. Finally, the paper summarizes the scientific background from different areas related to oxidative and premature skin ageing.
Systematics, phylogeny and biogeography of Anterastes (Orthoptera, Tettigoniidae, Tettigoniinae): evolution within a refugium
Authors: Çıplak Battal
Published: December 2003

Çıplak, B. (2004). Systematics, phylogeny and biogeography of Anterastes (Orthoptera, Tettigoniidae, Tettigoniinae): evolution within a refugium. —Zoologica Scripta, 33, 19–44.

The genus Anterastes, distributed in southeastern Europe and the western part of Anatolia, is revised based on previous materials and numerous specimens collected from new localities. A key to all species is presented. Two new species, A. antitauricus sp. n. and A. ucari sp. n. are described. Anterastes akdaghensis Ramme is placed in synonymy with A. babadaghi Uvarov. Cladistic analysis confirmed the monophyly of Anterastes. The relationships among the species of Anterastes are: A. uludaghensis + ((A. serbicus + A. burri + A. antitauricus sp. n.) + (A. anatolicus + A. tolunayi + (A. niger + (A. babadaghi + A. turcicus + A. ucari sp. n.)))). The biogeography of the genus shows a correlation with its phylogeny. It is assumed that the genus arose from an ancestral stock in northwestern Anatolia in the Pliocene and the later range of this ancestral population expanded and contracted under the effects of the ice ages (glacial and interglacial periods, respectively). It is postulated that speciation within the genus, suggested by phylogenetic analysis, might have occurred when the range of ancestral populations expanded during glacial periods and contracted in subsequent warm periods. The present species may be the product of relict populations remaining in refugia at higher altitudes with alpine or subalpine vegetation in southern Anatolia.
Hippopotamyrus ansorgii species complex in the Upper Zambezi River System with a description of a new species, H. szaboi (Mormyridae)
Authors: Kramer Bernd , Van Der Bank Herman , Wink Michael
Published: December 2003

Kramer, B., Van der Bank, & H., Wink, M. (2004) Hippopotamyrus ansorgii species complex in the Upper Zambezi River System with a description of a new species, H. szaboi (Mormyridae). — Zoologica Scripta, 33, 1–18.

Specimens referable to Hippopotamyrus ansorgii sampled from the Upper Zambezi River System within Caprivi (Namibia) represent a complex of three species, two of which coexist in the Upper Zambezi River, and a third that inhabits a nearby river, the Kwando, with which the Zambezi has been connected during periods of flooding. All three are indistinguishable in terms of their general appearance, but differ consistently in electric organ discharges (EOD), morphology, and molecular genetic characters. All phenotypes display a monopolar, head‐positive EOD pulse with specific post‐ or prepotentials. For H. ansorgii from the Zambezi River (HaZ), pulse duration is less than 0.5 ms (down to 0.205 ms; N= 34); for the syntopic H. szaboi sp. n., it is greater than 0.6 ms (up to 1.8 ms at 10% peak amplitude; N= 19). The parapatric phenotype of H. ansorgii from the Kwando River (HaK) has pulses shorter than 0.215 ms (down to 0.105 ms; N = 36). All three members of the species complex may be distinguished from each other by 7−9 anatomical characters, analysed by manova. Based on 22 enzymes and proteins studied, the moderate to high Wright's fixation index and the significant (P < 0.05) allele differentiation between EOD phenotypes provide additional evidence for incipient speciation. Pairwise analyses of the three different phenotypes showed the two parapatric species of H. ansorgii grouped together, and distinguishable from individuals of H. szaboi. Analyses of the mitochondrial cytochrome b gene revealed that all specimens which were attributed to H. szaboi form a well‐supported monophyletic basal clade (bootstrap support 73% or 82%). The genetic distances (uncorrected p distances) between H. szaboi and the two species of H. ansorgii are between 0.6% and 1.7%. Within the derived H. ansorgii clade some phylogeographical differentiation can be seen for fishes from the Zambezi and Kwando Rivers, but the respective groups are not consistent or supported by significant bootstrap values. The question of which of the two parapatric morphological and EOD phenotypes of H. ansorgii recognized in the present paper represents H. ansorgii (Boulenger, 1905) cannot be resolved at present because of the paucity and unclear origin of the historical type material.
Anatomy and relationships of the Early Cambrian wormMyoscolex
Authors: Dzik Jerzy
Published: December 2003

Dzik, J. (2004). Anatomy and relationships of the Early Cambrian wormMyoscolex. —Zoologica Scripta, 33, 57–69.

Numerous fossil specimens ofMyoscolex atelesGlaessner, 1979 from the late Early Cambrian Emu Bay shale of Kangaroo Island, South Australia with phosphatized organic matter‐rich tissues show its muscular body wall penetrated by rows of rod‐like structures — possible chaetae. The body wall was composed of an external layer with transverse (circular) fibres. This layer was thickest in lateral parts of the body and very thin dorsally. In the ventro‐lateral quarter of the body circumference, a belt of longitudinal fibres extended along the body. Longitudinal fibres also occurred in the dorsal region of the body. Along the venter extended a narrow longitudinal belt of probably oblique cords, crossing themselves perpendicularly. In having a virtually smooth, laterally flattened body,Myoscolexclosely resembles the slightly geologically youngerPikaiafrom the Burgess shale of British Columbia, generally believed to be one of the oldest chordates. Being the oldest probable annelid, at least superficially similar to the opheliid polychaetes,Myoscolexmay appear not too distant from the ancestor of the phylum. The lateral body flattening ofMyoscolexwas apparently an adaptation to swimming by undulation of the body in transverse plane, similar to today's errant polychaetes but without using chaetae or appendages in propulsion.
Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa
Authors: Stewart Barbara A. , Gouws Gavin , Daniels Savel R. , Matthee Conrad A.
Published: December 2003

Stewart, B. A., Gouws, G., Daniels, S. R. & Matthee, C. A. (2004). Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa. —Zoologica Scripta, 33, 45–55.

Presently, three Pseudodromia sponge crab species are recognized, all of which are endemic to the continental shelf off the coast of South Africa. Two of these differ only in the morphology of their rostral teeth, making them difficult to distinguish, and can thus be considered as cryptic species. In addition they have very similar distribution ranges, thus raising doubts as to their specific status. Discriminant function analysis of morphometric data, differentiation at 10 allozyme loci, and sequence data derived from the 12S rRNA mitochondrial gene were used to test whether specimens identified as P. latens and P. rotunda are morphological forms of a single, widespread species, or represent two, distinct, reproductively isolated species, and to establish whether these two taxa are sister species, and thus form a monophyletic entity. The presence of fixed allele differences at three, and strong genetic heterogeneity at five other allozyme loci, indicating no gene flow occurring between sympatric populations, as well as the relatively high degree of 12S rRNA and allozyme genetic differentiation observed, supported the recognition of P. latens and P. rotunda as separate species. The 12S rRNA topology suggested that the genus Pseudodromia, as presently constituted, is paraphyletic, thus inferring that the morphological characters used to define this taxon might not be useful for phylogenetic inferences. It was concluded that in view of the uncertainties raised regarding the designation and composition of certain genera within the family Dromiidae, further rigorous analyses of morphological and genetic data are needed to further our understanding of the taxonomy of the sponge crabs.
Olfactory ensheathing cells (OECs) and the treatment of CNS injury: advantages and possible caveats
Authors: Barnett Susan C. , Riddell John S.
Published: December 2003

One of the main research strategies to improve treatment for spinal cord injury involves the use of cell transplantation. This review looks at the advantages and possible caveats of using glial cells from the olfactory system in transplant‐mediated repair. These glial cells, termed olfactory ensheathing cells (OECs), ensheath the axons of the olfactory receptor neurons. The primary olfactory system is an unusual tissue in that it can support neurogenesis throughout life. In addition, newly generated olfactory receptor neurons are able to grow into the CNS environment of the olfactory bulb tissue and reform synapses. It is thought that this unique regenerative property depends in part on the presence of OECs. OECs share some of the properties of both astrocytes and Schwann cells but appear to have advantages over these and other glial cells for CNS repair. In particular, OECs are less likely to induce hypertrophy of CNS astrocytes. As well as remyelinating demyelinated axons, OEC grafts appear to promote the restoration of functions lost following a spinal cord lesion. However, much of the evidence for this is based on behavioural tests, and the mechanisms that underlie their potential benefits in transplant‐mediated repair remain to be clarified.
Strategies for identifying genes that play a role in spinal cord regeneration
Authors: Wintzer M. , Mladinic M. , Lazarevic D. , Casseler C. , Cattaneo A. , Nicholls J.
Published: December 2003

A search for genes that promote or block CNS regeneration requires numerous approaches; for example, tests can be made on individual candidate molecules. Here, however, we describe methods for comprehensive identification of genes up‐ and down‐regulated in neurons that can and cannot regenerate after injury. One problem concerns identification of low‐abundance genes out of the 30 000 or so genes expressed by neurons. Another difficulty is knowing whether a single gene or multiple genes are necessary. When microchips and subtractive differential display are used to identify genes turned on or off, the numbers are still too great to test which molecules are actually important for regeneration. Candidates are genes coding for trophic, inhibitory, receptor and extracellular matrix molecules, as well as unknown genes. A preparation useful for narrowing the search is the neonatal opossum. The spinal cord and optic nerve can regenerate after injury at 9 days but cannot at 12 days after birth. This narrow window allows genes responsible for the turning off of regeneration to be identified. As a next step, sites at which they are expressed (forebrain, midbrain, spinal cord, neurons or glia, intracellular or extracellular) must be determined. An essential step is to characterize proteins, their levels of expression, and their importance for regeneration. Comprehensive searches for molecular mechanisms represent a lengthy series of experiments that could help in devising strategies for repairing injured spinal cord.
A role for cAMP in regeneration of the adult mammalian CNS
Authors: Spencer Tim , Filbin Marie T.
Published: December 2003

Injury to the adult mammalian central nervous system (CNS) often results in permanent loss of sensory and motor function. This is due to the failure of injured axons to regenerate. The inhibitory nature of the CNS can be attributed to several factors, including formation of the glial scar, the presence of several molecules, associated with myelin, which inhibit axonal regrowth, and the intrinsic growth state of these neurons. Encouraging regeneration in the adult mammalian CNS therefore will require targeting one or all of these factors following injury. Here we illustrate recent work from our laboratory that identifies some of the signalling components involved in modulation of the intrinsic growth state of adult neurons. When activated, these signalling pathways can induce axonal regeneration in the presence of the myelin‐associated inhibitors both in vitro and in vivo.
Identifying genes for neuron survival and axon outgrowth in Hirudo medicinalis
Authors: Blackshaw S. E. , Babington E. J. , Emes R. D. , Malek J. , Wang W.‐Z.
Published: December 2003

We have studied the molecular basis of nervous system repair in invertebrate (Hirudo medicinalis) nerve cells. Unlike in mammals, neurons in invertebrates survive injury and regrow processes to restore the connections that they held before the damage occurred. To identify genes whose expression is regulated after injury, we have used subtractive probes, constructed from regenerating and non‐regenerating ganglia from the leech Hirudo medicinalis, to screen cDNA libraries made from whole leech CNS or from identified microdissected neurons. We have identified genes of known or predicted function as well as novel genes. Known genes up‐regulated within hours of injury and that are widely expressed in invertebrate and mammalian cells include thioredoxin and tubulin. Other known genes, e.g. Cysteine Rich Intestinal Protein (CRIP), have previously been identified in mammalian cells though not in regenerating adult neurons. Two regulated genes identified, myohemerythrin and the novel protein ReN3 are exclusively expressed in invertebrates. Thus our approach has enabled us to identify genes, present in a neuron of known function, that are up‐ and down‐regulated within hours of axotomy, and that may underpin the intrinsic ability of invertebrate neurons to survive damage and initiate regrowth programmes.
Chondroitin sulphate proteoglycans: preventing plasticity or protecting the CNS?
Authors: Rhodes K. E. , Fawcett J. W.
Published: December 2003

It is well established that axonal regeneration in the adult CNS is largely unsuccessful. Numerous axon‐inhibitory molecules are now known to be present in the injured CNS, and various strategies for overcoming these obstacles and enhancing CNS regeneration have been experimentally developed. Recently, the use of chondroitinase‐ABC to treat models of CNS injury in vivo has proven to be highly beneficial towards regenerating axons, by degrading the axon‐inhibitory chondroitin sulphate glycosaminsoglycan chains found on many proteoglycans in the astroglial scar. This enzyme has now been shown to restore synaptic plasticity in the visual cortex of adult rats by disrupting perineuronal nets, which contain high levels of chondroitin sulphate proteoglycans (CS‐PGs) and are expressed postnatally around groups of certain neurons in the normal CNS. The findings suggest exciting prospects for enhancing growth and plasticity in the adult CNS; however, some protective roles of CS‐PGs in the CNS have also been demonstrated. Clearly many questions concerning the mechanisms regulating expression of extracellular matrix molecules in CNS pathology remain to be answered.