bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cranial Osteology Of The Middle Triassic Ichthyosaur Contectopalatus From Germany
Authors: Maisch Michael W. , Matzke Andreas T.
Published: November 2003

A new partial skull of the Middle Triassic ichthyosaur Contectopalatus atavus allows many new osteological observations and makes the referral of several additional specimens, including lower jaw material, possible. This aids very much in the understanding of the anatomy of this highly derived mixosaurid species. The lectotype of Ichthyosaurus atavus is shown to be diagnostic and the recent proposal of a neotype is unnecessary. Contectopalatus shows thecodont dentition in all parts of the jaws. The teeth are labyrinthodont at their bases. Some specimens, which are interpreted as very late ontogenetic stages of C. atavus, indicate that Contectopalatus grew very large, reaching four to five times the size of other mixosaurids. Mixosaurid taxonomy is reviewed. Three valid genera can be included in a monophyletic Mixosauridae: Mixosaurus (including M. cornalianus and M. kuhnschnyderi), PhalarodonContectopalatus (monotypic). The mixosaurids are the sister group to the remaining ichthyosaurs, apart from the Lower Triassic forms. The status of the Omphalosauridae remains unresolved, but they are not closely related to the mixosaurids, because the durophagous dentition was acquired convergently in the two groups.
Three‐Dimensional Phosphatic Preservation Of Giant Acritarchs From The Terminal Proterozoic Doushantuo Formation In Guizhou And Hubei Provinces, South China
Authors: Chuanming Zhou , Brasier M. D. , Yaosong Xue
Published: November 2003

During the last two decades, a diverse assemblage of multicellular algae, spherical microfossils, bacteria and cyanobacteria (the Weng'an Biota) has been reported from the Terminal Proterozoic Doushantuo phosphorite in south China, which provides an important window for evolutionary studies of multicellular life just before the Ediacaran animal radiation. In this paper we report on three‐dimensionally preserved acritarchs from the Doushantuo phosphorites at Weng'an in Guizhou Province and, for the first time, from Baokang in Hubei Province. Our assemblage contains species of the genus Meghystrichosphaeridium Zhang, Yin, Xiao and Knoll, 1998 non Chen and Liu, 1986 including M. chadianensis (Chen and Liu) Zhang, Yin, Xiao and Knoll, emend. 1998, and M. reticulatum Xiao and Knoll, 1999; the genus Echinosphaeridium Knoll, 1992 including the species E. maximum (Yin) Knoll, 1992; the new genus Bacatisphaera including the new species B. baokangensis and the new genus Castaneasphaera including the new species C. speciosa. The latter shows a marked resemblance to similarly preserved phosphatized Palaeozoic acritarchs called ‘mazuelloids’, consistent with a phytoplanktonic mode of life for the global Doushantuo/Pertatataka microflora (DPM).
The braincase and palate of the tetrapodomorph sarcopterygian mandageria fairfaxi: morphological variability near the fish–tetrapod transition
Authors: Johanson Zerina , Ahlberg Per , Ritchie Alex
Published: November 2003

The braincase of the Late Devonian tristichopterid sarcopterygian Mandageria fairfaxi, from Canowindra, NSW, Australia, differs radically from the conservative pattern present in other ‘osteolepiforms’ (stem–group tetrapodomorph fishes) and non–dipnoan sarcopterygian fishes in general. The basioccipital region is short, displaced anteriorly, and either unossified or loosely articulated to the exoccipital, leaving most or all of the notochordal tunnel open ventrally. The exoccipital complex, which is developed into a large saddle that would have rested on top of the notochord, carries large, triangular articular facets on its posterior face and appears to have formed part of a functional neck joint, a synovial articulation between the skull and vertebral column that allows the former to rotate against the latter. Such a joint is characteristic of post–Devonian tetrapods, but unknown in other sarcopterygians. We infer that the ventrally open notochordal tunnel allowed gentle flexion of the cranial notochord during (predominantly vertical) rotational movement at the occiput; this is a mechanically unique solution to the problem of creating a mobile neck. Other unusual features of Mandageria include a posteriorly located lateral commissure, and structures on the entopterygoid and lateral commissure that may have been associated with an elaborate spiracular tract.
‘Trees, forests and communities’: some historiographical approaches to environmental history on Africa
Authors: Brown Karen
Published: November 2003

Focusing on the contested issue of trees and forests, this paper looks at various ways in which historians have explored environmental change and human agency in Africa. It looks in particular at the colonial period and positions the case of the Cape Colony (South Africa) in a broader historiographical context. Colonial silviculture involved both the appropriation of the natural forests and the creation of exotic plantations. These policies generated a mixture of reactions from African communities and had varying effects on the environment. Colonial science and the projects it gave rise to have since been critiqued, contributing to the promotion of community‐based forestry schemes that try to incorporate indigenous knowledge and ideas about land use.
The political ecology ofPrunus africanain Cameroon
Authors: Page Ben
Published: November 2003

This paper provides an analysis of some current trends in political ecology and then illustrates the intermingling of politics and ecology using a case study of the exploitation and conservation ofPrunus africanain Cameroon. It argues that political ecology is still a lively field, but that some recent attempts to chart a way forward for this perspective risk shifting it away from its liminal position in relation to natural and social science by being disinclined to engage with ecological processes. The case study draws attention to the strengths and shortcomings in existing attempts to weave political and economic analysis into environmental debates over the sustainable management of this tree species, which has been incorporated into phytomedical markets in Europe. The fortunes of the tree reflect its botany and ecology as well as the trajectories of the local economy, intercontinental markets for alternative health products, the policies and practices of the Cameroonian state and the politics of international aid.
Representing environments in flux: case studies from East Africa
Authors: Gillson Lindsey , Sheridan Michael , Brockington Dan
Published: November 2003

The dominant view in the ecology and anthropology of the 1950s saw populations harmoniously interacting in self‐regulating systems; climax forests and stable societies were the ruling hypotheses. Now, however, ecology and social sciences are investigating nature and culture in flux. The flux paradigms of nature and culture describe a human–ecological relationship that is non‐equilibrial, historically contingent and constantly negotiated at both material and ideological levels by unequal actors. In this paper, we examine the effect of changing ecological and cultural paradigms on interpretations of environmental change in three areas of East Africa: the North Pare Mountains, Tanzania, the Mkomazi Game Reserve, Tanzania and the Tsavo National Park, Kenya. We explore how discursive and materialist approaches can complement one another, by expanding the domains of ecological inquiry and demanding that analysts cross‐check their data for unquestioned assumptions regarding stability, variability and spatial and temporal scales. Rather than testing a ruling hypothesis, we suggest that ecologists and social scientists work with multiple hypotheses, with the aim of understanding the interplay between ecological, environmental and social influences.
Fashioning furniture: restructuring the furniture commodity chain
Authors: Leslie Deborah , Reimer Suzanne
Published: November 2003

The paper explores intersections between the fashion and furniture industries as manifest across magazine, retail and manufacturing spaces. We argue that the temporality and spatiality of furniture have begun to shift. As a result, furniture retailers and manufacturers in Canada and the UK have been required to restructure their methods of operating.
Long‐term Outcome of Nonsurgical Candidates with Medically Refractory Localization‐related Epilepsy
Authors: Selwa Linda M. , Schmidt Shelley L. , Malow Beth A. , Beydoun Ahmad
Published: November 2003

Summary:  Purpose: Epilepsy surgery can result in complete seizure remission rates of upto 80% in patients with mesial temporal sclerosis and unilateral seizures. The seizure‐free rate after surgery for patients with extratemporal nonlesional epilepsy has ranged between 30% and 40%. Some patients with medically refractory localization‐related epilepsy cannot be offered surgical resection because of inadequate localization of the epileptogenic zone, documentation of bilateral ictal onsets, or functionally important areas of cortex that prohibit resection. The short‐term rate of complete remission with medications in temporal lobe epilepsy is poor. Less is known about remission rates in patients who are not surgical candidates. In this study, we evaluated the outcome of medical treatment in patients with medically refractory partial epilepsy who were evaluated for possible epilepsy surgery but deemed to be inadequate surgical candidates.

Methods: A retrospective chart review and telephone survey with a self‐rating questionnaire were completed for all patients who underwent epilepsy surgery evaluation but were not ultimately offered surgical treatment at the University of Michigan from 1990 through 1998. We assessed changes in seizure frequency and type, imaging characteristics, ictal recordings, interim medication history, and subjective changes in quality of life.

Results: Thirty‐four subjects were available for follow‐up study, at an average of >4 years after surgical evaluation. A significant reduction in seizure frequency was noted at the time of follow‐up compared with that at the time of surgical evaluation. Of patients, 21% achieved seizure remission and remained seizure free for an average of 2.5 years. Four of the seven seizure‐free patients attributed their remission to new antiepileptic drugs (AEDs). On a global self‐rating item, 15 of 34, or 44%, felt more or much more satisfied with their lives, and 41% felt their quality of life was stable.

Conclusions: A surprisingly large number of patients we surveyed, with refractory partial epilepsy not eligible for surgical management, reported reduced seizure frequency at follow‐up, and 21% were seizure free. Our findings suggest that the long‐term prognosis in patients with refractory partial epilepsy who are not surgical candidates may be more positive than might be generally expected.
Correlation Between Language Organization and Diffusion Tensor Abnormalities in Refractory Partial Epilepsy
Authors: Briellmann Regula S. , Mitchell L. Anne , Waites Anthony B. , Abbott David F. , Pell Gaby S. , Saling Michael M. , Jackson Graeme D.
Published: November 2003

Summary:  Purpose: Atypical language organization is more frequently found in patients with refractory partial epilepsy than in healthy controls; however, the reasons for this are not well known. Here we assess the relation between language laterality index (LI) and white‐matter tract changes.

Methods: Nine patients with refractory partial epilepsy were assessed with a 3‐T GE scanner. Functional magnetic resonance imaging (fMRI) of language and diffusion tensor imaging (DTI) were acquired. For the fMRI, a noun–verb generation task was performed, all images were motion corrected, and activated pixels in classic language areas were counted. The DTI images were acquired in six standard directions with an initial non–diffusion‐weighted scan. The “average anisotropy” was determined in a region of interest in the frontal lobe, temporal lobe, and parietal lobe white matter. An asymmetry index (AI) was calculated for language and DTI. Atypical language lateralization was diagnosed if the lateralization index (LI)‐language was smaller than 0.4.

Results: Two of the nine patients had atypical language localization (LI‐language, −0.6, and 0.3); both had left temporal DTI asymmetry (LI‐DTI, –0.3 and –0.2). The remaining seven patients had typical language localization, and no marked DTI abnormalities. Asymmetry in temporal lobe DTI correlated with LI‐language (r= 0.8; p = 0.006).

Conclusions: Atypical language lateralization in patients with partial epilepsy may be associated with white‐matter tract abnormalities.
Unidirectional Cross‐tolerance from Levetiracetam to Carbamazepine in Amygdala‐kindled Seizures
Authors: Zhang Zhang‐Jin , Xing Guo‐Qiang , Russell Shani , Obeng Kris , Post Robert M.
Published: November 2003

Summary:  Purpose: Tolerance is a potential problem in long‐term anticonvulsant therapy of epilepsy, bipolar disorder, and neuropathic pain. The present study was designed to determine whether cross‐tolerance occurs between levetiracetam (LEV) and carbamazepine (CBZ) in amygdala‐kindled rats.

Methods: Male Sprague–Dawley rats were implanted with an electrode into the left amygdala. While kindling stimulation was started, animals received repeated treatment (i.p.) with saline (n = 7) or LEV (150 mg/kg, n = 8). Saline‐injected rats were subsequently challenged with a single dose of 150 mg/kg LEV when full kindling developed (stage ≥4). Both groups of rats were then administered long‐term CBZ (5 mg/kg) until rats developed complete tolerance. All CBZ‐tolerant rats were subsequently reexposed to LEV (150 mg/kg) for an additional 10 consecutive days.

Results: Repeated LEV treatment significantly suppressed the increase in seizure stage, seizure duration, and afterdischarge duration induced by amygdala stimulation, markedly increasing the number of stimulations to achieve a kindling major motor seizure. The LEV challenge produced a more robust suppression of seizure stage in saline‐injected rats compared with LEV‐treated animals. CBZ treatment markedly suppressed fully kindled seizures in rats initially injected with saline, and then anticonvulsant tolerance rapidly developed after 3–4 days of repeated treatment. In contrast, rats that had initially received repeated LEV treatment did not show a response to treatment with CBZ (5 mg/kg). When CBZ‐tolerant rats were subsequently exposed to LEV (150 mg/kg), noticeable anticonvulsant effects were observed; but these were gradually lost with increasing numbers of LEV exposures.

Conclusions: Whereas LEV shows potent antiepileptogenic and anticonvulsant effects in amygdala‐kindled rats, its repeated treatment induces anticonvulsant tolerance and unidirectional cross‐tolerance to CBZ. In contrast, anticonvulsant tolerance to CBZ does not transfer to LEV. The mechanistic implications of the present results for clinical therapeutics remain to be evaluated.
Symbols, not data: rare trees and vegetation history in Mali
Authors: Duvall Chris S
Published: December 2003

Historical analysis of botanical literature concerning the treesGilletiodendron glandulosumandGuibourtia copalliferain Mali's Manding Plateau reveals that the dominant representation of these plants has helped to perpetuate colonial‐era theories of vegetation history, African land management, and natural resource politics in West Africa. The French botanist Aubréville described these plants as proof of the theory of vegetation history that blamed poor land management by rural Africans for a steady and continuing destruction of vegetation from its presumed original forest climax. Although Aubréville's representation of these trees was justified within the 1930s scientific context he worked, subsequent researchers uncritically maintained his conclusions even though the changed scientific context in which they worked did not justify such representation. Subsequent ecological research also failed to substantiate Aubréville's representation of these trees, yet several influential modern botanical works have uncritically accepted colonial‐era botanical literature founded on his ideas. Thus, modern botanical works have perpetuated a simplistic and inaccurate narrative of resource use under an appearance of objectivity. As a result, policy recommendations based on the modern botanical sources remain almost identical to colonial‐era policies. Based on the similarity of colonial‐era and modern portrayals of these trees, this paper argues that a regional discursive formation recently described by other authors may be expanded to include southern Mali, which carries negative implications for decentralization reform in Mali.
Changing women's roles, changing environmental knowledges: evidence from Upper Egypt
Authors: Briggs John , Sharp Joanne , Hamed Nabila , Yacoub Hoda
Published: December 2003

The aim of this paper is to investigate the ways in which changing gender roles in a Bedouin community in Upper Egypt, brought about by settlement over the last 20 years on the shores of Lake Nasser, have impacted on the accumulation and development of indigenous environmental knowledges by Bedouin women. The research was carried out among four groups of Ababda Bedouin in the Eastern Desert of Egypt and involved in‐depth monthly conversations carried out over a period of 12 months. The main conclusions of the study are that the women of the study area have had to develop new knowledges which, in some cases, are now different from those held by men because of the different economic circumstances in which many find themselves; that these knowledges are fluid, dynamic and ever‐changing with their own internal dynamism; and that socially constructed notions of gender are vital in the development process, notions that are sensitive to both men's and women's interests and their interrelationships.
A new species of Ameripodius (Aves: Galliformes: Quercymegapodiidae) from the Lower Miocene of France
Authors: Mourer‐Chauviré Cécile
Published: November 2003

The Quercymegapodiidae, primitive galliforms resembling recent megapodes, have been described from the Upper Eocene of Quercy, France. They have also been identified in the Upper Oligocene–Lower Miocene of Brazil, where they are represented by the genus Ameripodius Alvarenga. A new species of this genus, Ameripodius alexis sp. nov., from the Lower Miocene of France, is described here. The occurrence of the same genus on both sides of the Atlantic Ocean emphasizes the similarities between South American and European avifaunas during the early Tertiary. New discoveries indicate that a similar avifauna was also present in North America, and that a characteristic association of taxa can be defined for the group that includes South America, North America and Eurasia. However, so far as is known, the same avifauna does not occur in contemporaneous African avifaunas.
New palaeothentid marsupial from the Middle Miocene of Bolivia
Authors: Goin Francisco J. , Sánchez–Villagra Marcelo R. , Kay Richard F. , Anaya–Daza Federico , Takai Masanaru
Published: November 2003

The new species Acdestis maddeni is described based on the most complete skull of a palaeothentid marsupial known so far. The skull preserves most of the upper dentition and of the ear region, the latter an anatomical region previously unknown in this extinct family. A right maxillary fragment including C–M2 also belongs to the new species. The specimens come from the middle Miocene localities of Rosario and Quebrada Honda in southernmost Bolivia. The generic allocation of the new species is somewhat problematic, given that most of the taxonomy of fossil palaeothentids is based on lower dentitions. Compared to that of caenolestids, the skull of A. maddeni is much larger, with a shorter and broader snout, a proportionally narrower interorbital constriction, and a less globular, more triangular–shaped braincase in dorsal view.
Coping with Complex Leadership Roles: The Problematic Redefinition of Government‐owned Enterprises
Authors: Christensen Tom , LÆGreid Per
Published: November 2003

Inspired by New Public Management, many countries have changed their central public apparatus from an integrated to a more segregated structural model. A central element in this process is structural devolution and the establishment of new or reorganized state‐owned companies with increased business autonomy and new formal control systems. This paper focuses on how this development, as exemplified by the case of Norway, is affecting the role of central executive political and administrative leaders. The study, based on elite interviews, shows that corporatization has made the role of central leaders more complex and ambiguous and undermined traditional political control. We interpret this development from a transformative perspective, underlining how structural devolution is filtered through the dynamic context of environmental pressure and internal structural and cultural factors; in addition, experiences from New Zealand are used to contrast the Norwegian case.
Management by Measurement? Public Management Practices Amidst Ambiguity
Authors: Noordegraaf Mirko , Abma Tineke
Published: November 2003

In the public sphere, a management by measurement (MBM) movement can be traced. Practitioners attempt to strengthen the transparency and effectiveness of administrative systems by introducing rational measurement cycles. When issues are managed, ambitions must be stated, options must be assessed, optimal options must be chosen and performance must be monitored and evaluated. This cycle rests upon assumptions that are often untenable. When issues are ambiguous, interpretative spaces exist; when interpretative spaces exist, strict measurement cycles do not work because required conditions and assumptions cannot be met. This article explores the nature of interpretative spaces by identifying three types of public management practice. In this typology of public management, practices differ in terms of the extent to which issues can be classified, as well as the extent to which standards are contested. Management by measurement fits canonical practices where issues are known and standards are shared, it is argued, but is less appropriate for evaluating non‐canonical practices and practices‐in‐transition where such a classification of issues is weak and consensus on standard is absent. MBM focuses on data; the other practices require dialogue in order to manage ambiguity and interpretative spaces.
What Can We Learn from the Current Crisis in Argentina?
Authors: Kehoe Timothy J.
Published: November 2003

Currently, Argentina is experiencing what the government describes as a ‘great depression.’ Using the ‘Great Depressions’ methodology developed by Cole and Ohanian (1999) and Kehoe and Prescott (2002), we find that the primary determinants of both the boom in Argentina in the 1990s and the subsequent depression were changes in productivity, rather than changes in factor inputs. The timing of events links the boom to the currency‐board‐like Convertibility Plan and the crisis to its collapse. To gain credibility, the Argentine government took measures to make abandoning the plan more costly. Because the government was unable to enforce fiscal discipline, however, these increased costs failed to make the plan more credible and instead made the crisis far worse when it failed.
Relationships between spatial environmental heterogeneity and plant species diversity on a limestone pavement
Authors: Lundholm Jeremy T. , Larson Douglas W.
Published: November 2003

No empirical studies have examined the relationship between diversity and spatial heterogeneity across unimodal species richness gradients. We determined the relationships between diversity and environmental factors for 144 0.18 m2plots in a limestone pavement alvar in southern Ontario, Canada, including within‐plot spatial heterogeneity in soil depth, microtopography and microsite composition. Species richness was unimodally related to mean soil depth and relative elevation. Microsite heterogeneity and soil depth heterogeneity were positively correlated with species richness, and the richness peaks of the unimodal gradients correspond to the maximally spatially heterogeneous plots. The best predictive models of species richness and evenness, however, showed that other factors, such as ramet density and flooding, are the major determinants of diversity in this system. The findings that soil depth heterogeneity had effects on diversity when the effects of mean soil depth were factored out, and that unimodal richness peaks were associated with high spatial heterogeneity in environmental factors represent significant contributions to our understanding of how spatial heterogeneity might contribute to diversity maintenance in plant communities.
Microscale distribution patterns in high Arctic soil microarthropod communities: the influence of plant species within the vegetation mosaic
Authors: Coulson S. J. , Hodkinson I. D. , Webb N. R.
Published: November 2003

We tested the hypothesis that within a relatively homogeneous vegetation type the spatial configuration of different plant species may be a determining factor in the composition of the soil animal communities. Six vascular plant species (Luzula confusa,Dryas octopetala, Cassiope tetragona, Salix polaris, Silene acaulisandSaxifraga opposigifolia), growing within high ArcticSaxifraga‐lichen heath vegetation, showed different distributional patterns.Luzula confusaandS. polariswere ubiquitous throughout whileD. octopetalaandC. tetragonahad the most scattered distributions. Soil microarthropod density varied significantly among plant species from 18 000 (S. polaris) to 42 000 m−2(S. acaulis). Few significant numerical interrelationships were found between the population densities of the different Collembola or cryptostigmatic mite species or between microarthropod densities and variation in the physical properties of the soil associated with each plant species. However, despite the high similarity of species present, Discriminant Analysis idengified distinct microarthropod assemblages associated with each plant species. Over 70% of microarthropod samples taken from soil beneathS. polarisorL. confusawere correctly classified. Rank order of animal species abundance, however, varied among plant species. The collembolanFolsomia quadrioculataranked first in five of the six plant species but the miteCamisia anomiawas numerically dominant underS. polaris. The second most abundant species was much more variable. Despite these variations, the shape of the species rank abundance curve for microarthropods was remarkably similar for all plant species, with rank one and two species comprising ca 55 and 27% of the fauna respectively. These conclusions were reinforced by χ2analysis which idengified significantly distinct faunal communities between each plant species. Those microarthropod species contributing most to these between‐plant differences, as measured by higher or lower than expected populations, were idengified and were shown to be not always the most abundant species. Thus, on a local scale plants of different species were shown to act as useful proxy indicators of soil conditions that affect the soil microarthropod community. This should be taken into account when designing sampling programmes for soil invertebrates.
Are simple plumage traits sufficient for species discrimination by harrier males?
Authors: García Jesús T.
Published: November 2003

I investigated whether plumage features are sufficient for species recognition in two sibling sympatric raptor species: the Montagu's harrier Circus pygargus and the hen harrier C. cyaneus. These species are similar in body size and differ slightly in plumage. During prelaying and laying periods, I placed artificial models close to nests of both species, simulating a conspecific male harrier (male of the same species), a heterospecific male harrier (male of the other species) or a wood pigeon Columba palumbus (acting as a control of the same size and colour). All of them represented birds perched in a neutral posture, so that they could only be recognised by their plumage differences. The use of plumage traits during this period would be particularly relevant in discriminating between their own and other species, offering the opportunity to avoid unnecessary fights, and therefore maximising the benefits of defence. I measured male responsiveness by recording aggressive behaviour towards each model (aggressive rate and time spent close to the female). Male presence time was significantly longer during conspecific decoy presentation than during heterospecific decoy presentation. Furthermore, males of both species were more aggressive towards the conspecific decoy than towards the heterospecific one, and no attacks towards the control were recorded. These results provide evidence that these birds are able to recognise plumage features of their own and the sibling species.
Diurnal exposure as a risk sensitive behaviour in tawny owls Strix aluco?
Authors: Sunde Peter , Bølstad Mikkel S. , Desfor Kasi B.
Published: November 2003

Tawny owls Strix aluco generally roost in cryptic locations during the day. To test the hypothesis that this cryptic behaviour is an effort to avoid mobbers or avian predators, we measured diurnal behaviour and cause‐specific mortality of radio‐tagged birds. Non‐breeding adults (assumed to be well fed individuals, optimising their own survival) roosted in less exposed locations than adults with young and newly independent juveniles. Parents roosted in the most exposed sites when their young were immature and vulnerable to depredation, probably to guard offspring. Newly independent juveniles apparently selected roosting sites in exposed places to get access to food, as this behaviour was associated with lower perching heights and higher prey abundance beneath their roosting sites. They also perched in more exposed sites, closer to the ground, in summers with low prey abundance compared to summers with high prey abundance. After previous encounters with goshawks Accipiter gentilis, dependent juveniles roosted in less exposed places compared to other young. The increased risk of being mobbed was highly significant with increasing roosting exposure. Once an owl was mobbed, the intensity of the mobbing correlated positively with the mass of the mobbers, but mobbing birds never killed any owls. In contrast, diurnal raptors caused 73% of natural owl deaths (n=15) and the depredation rate by raptors was 3.8 times higher in population classes that generally roosted in more exposed locations than did non‐breeding adults. We therefore suggest that depredation by diurnal raptors is the main factor shaping the diurnal behaviour of tawny owls.
Assessing migration patterns of sharp‐shinned hawks Accipiter striatus using stable‐isotope and band encounter analysis
Authors: Smith Ruth B. , Meehan Timothy D. , Wolf Blair O.
Published: November 2003

Intraspecific migration patterns in birds have both spatial and temporal components. Two commonly reported spatial patterns are leap‐frog and chain migration. Temporal migration patterns refer to the timing of migration of populations from different breeding latitudes. We investigated the spatial and temporal migration patterns of hatching‐year (HY) sharp‐shinned hawks Accipiter striatus of interior North America using stable‐hydrogen isotope and band encounter analyses. Feather samples were collected from hawks migrating through New Mexico, USA and measured for their stable‐hydrogen isotope ratios (δD) to distinguish individuals originating from relatively high and low natal latitudes. We then examined the relationship between feather δD values and passage dates through New Mexico, USA. We also gathered band encounter data from the Bird Banding Lab of the United States Geological Survey to determine the wintering latitudes of HY sharp‐shinned hawks relative to their passage date through migration banding sites in interior North America. Combining these data, we found that during fall migration HY sharp‐shinned hawks used a chain migration pattern, that is, hawks originating from lower latitudes wintered further south than those from higher latitudes. In addition, birds originating from lower latitudes passed through interior North America earlier than those from higher latitudes. We also found that hawks from higher latitudes were significantly larger than those from lower latitudes, and that females from higher latitudes had significantly higher estimated fat levels than females from lower latitudes.
Phylogenetic relationships of Neotropical honeycreepers and the evolution of feeding morphology
Authors: J. Burns Kevin , J. Hackett Shannon , K. Klein Nedra
Published: November 2003

Phylogenetic relationships among Neotropical honeycreepers were studied by using cytochromebsequence data. Although honeycreepers were once placed in their own family (Coerebidae), these species did not form a monophyletic group in any of the phylogenies in this study. Thus, our results indicate that nectar‐feeding evolved independently multiple times among these birds. The Neotropical honeycreepers are best considered disparate members of a larger radiation of tanagers and finches, in which bill size and shape, and associated feeding behaviors have changed frequently to fill a variety of niches. Our phylogenies also provide specific taxonomic recommendations on the placement of each honeycreeper genus. The use of the taxon Coerebidae is no longer warranted given the well‐supported relationships between different honeycreeper species and a variety of tanagers and finches.
Do Foreigners Cushion Native Jobs? The Case of European Regions in the 1990s
Authors: Tani Massimiliano
Published: November 2003

Abstract.  This paper investigates whether foreigners cushion native labour during the phases of the economic cycle. The theoretical model, based on the work of Blanchard and Katz (Brookings Papers on Economic Activity 0(1): 1–75, 1992), assumes that foreigners supply labour with a higher wage elasticity than natives. The empirical analysis, based on an unbalanced panel of 161 European regions during 1988–97, shows that following a labour demand shock the variability of native employment growth is lower the higher the proportion of foreign citizens in the local labour force. These results suggest that foreigners absorb some of the effects of the shock, shielding natives from its full impact. The analysis also reveals that the main channel mediating this ‘cushioning’ effect is the inter‐regional migration of foreign workers, followed (as a far distant second) by their higher/lower unemployment rates.
Attitudes, Expectations and Sharing
Authors: Brown Sarah , Sessions John G.
Published: November 2003

Forward Links to Citing Articles
 
 
Apology. Labour 19:4 801.

 Online publication date: 16‐Dec‐2005.

Abstract.  We explore the relationship between performance‐related pay and the attitudes and expectations of a representative sample of British workers. Our results suggest that employees who participate in productivity‐linked bonus schemes, discretionary bonus schemes, share ownership or profit sharing are more optimistic about future employment and pay and are generally more satisfied with their work environment. However, employees participating specifically in profit‐sharing schemes are less likely to work as hard as they can, ceteris paribus. This is an intriguing finding, insinuating as it does that group‐sharing schemes are unable to rout the temptation to free ride and thereby ensure a first best cooperative equilibrium.
Alterations in high‐density lipoprotein metabolism and reverse cholesterol transport in insulin resistance and type 2 diabetes mellitus: role of lipolytic enzymes, lecithin:cholesterol acyltransferase and lipid transfer proteins
Authors: Borggreve S. E. , De Vries R. , Dullaart R. P. F.
Published: November 2003

Insulin resistance and type 2 diabetes mellitus are generally accompanied by low HDL cholesterol and high plasma triglycerides, which are major cardiovascular risk factors. This review describes abnormalities in HDL metabolism and reverse cholesterol transport, i.e. the transport of cholesterol from peripheral cells back to the liver for metabolism and biliary excretion, in insulin resistance and type 2 diabetes mellitus.

Several enzymes including lipoprotein lipase (LPL), hepatic lipase (HL) and lecithin: cholesterol acyltransferase (LCAT), as well as cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), participate in HDL metabolism and remodelling. Lipoprotein lipase hydrolyses lipoprotein triglycerides, thus providing lipids for HDL formation. Hepatic lipase reduces HDL particle size by hydrolysing its triglycerides and phospholipids. A decreased postheparin plasma LPL/HL ratio is a determinant of low HDL2 cholesterol in insulin resistance. The esterification of free cholesterol by LCAT increases HDL particle size. Plasma cholesterol esterification is unaltered or increased in type 2 diabetes mellitus, probably depending on the extent of triglyceride elevation. Subsequent CETP action results in transfer of cholesteryl esters from HDL towards triglyceride‐rich lipoproteins, and is involved in decreasing HDL size. An increased plasma cholesteryl ester transfer is frequently observed in insulin‐resistant conditions, and is considered to be a determinant of low HDL cholesterol. Phospholipid transfer protein generates small pre β‐HDL particles that are initial acceptors of cell‐derived cholesterol. Its activity in plasma is elevated in insulin resistance and type 2 diabetes mellitus in association with high plasma triglycerides and obesity. In insulin resistance, the ability of plasma to promote cellular cholesterol efflux may be maintained consequent to increases in PLTP activity and pre β‐HDL. However, cellular cholesterol efflux to diabetic plasma is probably impaired. Besides, cellular abnormalities that are in part related to impaired actions of ATP binding cassette transporter 1 and scavenger receptor class B type I are likely to result in diminished cellular cholesterol efflux in the diabetic state. Whether hepatic metabolism of HDL‐derived cholesterol and subsequent hepatobiliary transport is altered in insulin resistance and type 2 diabetes mellitus is unknown.

Specific CETP inhibitors have been developed that exert major HDL cholesterol‐raising effects in humans and retard atherosclerosis in animals. As an increased CETP‐mediated cholesteryl ester transfer represents a plausible metabolic intermediate between high triglycerides and low HDL cholesterol, studies are warranted to evaluate the effects of these agents in insulin resistance‐ and diabetes‐associated dyslipidaemia.
Aortic distensibility is reduced in subjects with type 2 diabetes and cardiac autonomic neuropathy
Authors: Tentolouris N. , Liatis S. , Moyssakis I. , Tsapogas P. , Psallas M. , Diakoumopoulou E. , Voteas V. , Katsilambros N.
Published: November 2003

Background  Reduced aortic distensibility predicts cardiovascular mortality in patients with type 2 diabetes and impaired glucose tolerance. Cardiac autonomic neuropathy is common in subjects with diabetes. However, the relationship between the elastic properties of the aorta and autonomic neuropathy has not been studied to date in subjects with type 2 diabetes.

Materials and methods  In this cross‐sectional study, a total of 87 subjects with type 2 diabetes (27 with and 60 without cardiac autonomic neuropathy) as well as 60 healthy individuals, matched for age and sex with the diabetic subjects, were examined. Cardiac autonomic neuropathy was diagnosed on the basis of the battery of the classic cardiovascular autonomic function tests. Aortic distensibility was assessed by high‐resolution ultrasonography.

Results  Diabetic patients had reduced aortic distensibility in comparison with the control subjects: 1·81 ± 0·58 vs. 2·53 ± 0·34 10−6 cm2 dyn−1, respectively (P < 0·0001). In addition, diabetic individuals with cardiac autonomic neuropathy had reduced aortic distensibility as compared with patients without this complication: 1·60 ± 0·72 vs. 1·90 ± 0·48 10−6 cm2 dyn−1, respectively (P = 0·02). Multivariate linear regression analysis in the diabetic group, after controlling for a number of confounding factors such as age, systolic and diastolic blood pressure, duration of diabetes and presence as well as severity of cardiac autonomic neuropathy, demonstrated a significant and independent association between duration of diabetes [B = −0·02, SE(B) = 0·01, P = 0·01] and presence of cardiac autonomic neuropathy [B = −0·29, SE(B) = 0·14, P = 0·03] with aortic distensibility.

Conclusion  Type 2 diabetes is associated with a significant reduction in the elastic properties of the aorta. In addition, known duration of diabetes and presence of cardiac autonomic neuropathy are the main predictors of aortic distensibility in subjects with type 2 diabetes.
Maternal Genotype Influences Stress Reactivity of Vasopressin‐Deficient Brattleboro Rats
Authors: Zelena D. , Mergl Z. , Makara G. B.
Published: November 2003

The role of vasopressin, cosecreted with corticotropin‐releasing hormone (CRH), in stress is debated, because both normal as well as reduced adrenocorticotropin hormone (ACTH) rise to an acute challenge has been reported in Brattleboro rats genetically lacking vasopressin (di/di). Because di/di pups could be born either from di/+ (heterozygous) or from di/di mothers, and maternal influence is known to modify adult responsiveness, we investigated whether the influence of maternal genotype could explain the variability. Adult rats from mothers with different genotypes were stressed with 60 min restraint and trunk blood was collected for measuring hormone content by radioimmunoassay at the end of stress. All offspring of di/+ mothers had similar ACTH responses to restraint, while the di/di rats born to, and raised by di/di mothers showed reduced ACTH reactivity to restraint. The di/di rats showed elevated water turnover and required a daily cage cleaning every day, which meant frequent handling. To offset the role of handling, all rats had daily cage cleaning in the next series, but the results were the same as in the first series. To investigate whether lactation, the behaviour of the mother or some other factor during the pregnancy is responsible for the differences, pups from di/+ dams were raised by di/di foster mothers and vice versa. We found that the genotype of parental mother is more important than that of the foster mother. The corticosterone and prolactin elevation normally seen after acute stress was unchanged by family history, maternal or personal genotype. Furthermore, in studies with mutant animals, the rearing conditions should be controlled by the experimenter. In experiments with Brattleboro rats, the use of homozygous and heterozygous rats from the same litters of di/+ dams and di/di males is recommended. Our results suggest that vasopressin is not indispensable for ACTH release, and that the di/di genotype of the parental mother can decrease the stress reactivity of the di/di Brattleboro rats.
Adenosine A2A Receptor Gene Disruption Provokes Marked Changes in Melanocortin Content and Pro‐Opiomelanocortin Gene Expression
Authors: Jégou S. , Yacoubi M. El , Mounien L. , Ledent C. , Parmentier M. , Costentin J. , Vaugeois J. ‐M. , Vaudry H.
Published: November 2003

A2A receptor knockout (A2AR−/−) mice are more anxious and aggressive, and exhibit reduced exploratory activity than their wild‐type littermates (A2AR+/+). Because α‐melanocyte‐stimulating hormone (α‐MSH) influences anxiety, aggressiveness and motor activity, we investigated the effect of A2AR gene disruption on α‐MSH content in discrete brain regions and pro‐opiomelanocortin (POMC) expression in the hypothalamus and pituitary. No modification in α‐MSH content was observed in the hypothalamus and medulla oblongata where POMC‐expressing perikarya are located. In the arcuate nucleus of the hypothalamus, POMC mRNA levels were not affected by A2AR disruption. Conversely, in A2AR−/− mice, a significant increase in α‐MSH content was observed in the amygdala and cerebral cortex, two regions that are innervated by POMC terminals. In the pars intermedia of the pituitary, A2AR disruption provoked a significant reduction of POMC mRNA expression associated with a decrease in α‐MSH content. By contrast, in the anterior lobe of the pituitary, a substantial increase in POMC mRNA and adrenocorticotropin hormone concentrations was observed, and plasma corticosterone concentration was significantly higher in A2AR−/− mice, revealing hyperactivity of their pituitary‐adrenocortical axis. Together, these results suggest that adenosine, acting through A2A receptors, may modulate the release of α‐MSH in the cerebral cortex and amygdala. The data also indicate that A2A receptors are involved in the control of POMC gene expression and biosynthesis of POMC‐derived peptides in pituitary melanotrophs and corticotrophs.
Involvement of Ca2+‐calmodulin in Cd2+ toxicity during the early phases of radish (Raphanus sativus L.) seed germination
Authors: RIVETTA A. , NEGRINI N. , COCUCCI M.
Published: November 2003

The toxicity of Cd2+in vivo during the early phases of radish (Raphanus sativus L.) seed germination and the in vitro Cd2+ effect on radish calmodulin (CaM) were studied. Cd2+ was taken up in the embryo axes of radish seeds; the increase in fresh weight of embryo axes after 24 h of incubation was inhibited significantly in the presence of 10 mmol m−3 Cd2+ in the external medium, when the Cd2+ content in the embryo axes was c. 1.1 μmol g−1 FW. The reabsorption of K+, which characterizes germination, was inhibited by Cd2+, suggesting that Cd2+ affected metabolic reactivation. The slight effect of Cd2+ on the transmembrane electric potential of the cortical cells of the embryo axes excluded a generalized toxicity of Cd2+ at the plasma membrane level. After 24 h of incubation, Cd2+ induced no increase in total acid‐soluble thiols and Cd2+‐binding peptides able to reduce Cd2+ toxicity. Ca2+ added to the incubation medium partially reversed the Cd2+‐induced inhibition of the increase in fresh weight of embryo axes and concomitantly reduced Cd2+ uptake. Equilibrium dialysis experiments indicated that Cd2+ bound to CaM and competed with Ca2+ in this binding. Cd2+ inhibited the activation of Ca2+‐CaM‐dependent calf‐brain phosphodiesterase, inhibiting the Ca2+‐CaM active complex. Cd2+ reduced the binding of CaM to the Ca2+‐CaM binding enzymes present in the soluble fraction of the embryo axes of radish seeds. The possibility that Cd2+ toxicity in radish seed germination is mediated by the action of Cd2+ on Ca2+‐CaM is discussed in relation to the in vivo and in vitro effects of Cd2+.
Simple scaling of photosynthesis from leaves to canopies without the errors of big‐leaf models
Authors: DE PURY D. G. G. , FARQUHAR G. D.
Published: November 2003

In big‐leaf models of canopy photosynthesis, the Rubisco activity per unit ground area is taken as the sum of activities per unit leaf area within the canopy, and electron transport capacity is similarly summed. Such models overestimate rates of photosynthesis and require empirical curvature factors in the response to irradiance. We show that, with any distribution of leaf nitrogen within the canopy (including optimal), the required curvature factors are not constant but vary with canopy leaf area index and leaf nitrogen content. We further show that the underlying reason is the difference between the time‐averaged and instantaneous distributions of absorbed irradiance, caused by penetration of sunflecks and the range of leaf angles in canopies.

These errors are avoided in models that treat the canopy in terms of a number of layers – the multi‐layer models. We present an alternative to the multi‐layer model: by separately integrating the sunlit and shaded leaf fractions of the canopy, a single layered sun/shade model is obtained, which is as accurate and simpler. The model is a scaled version of a leaf model as distinct from an integrative approach.