bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutual passivation of group IV donors and nitrogen in diluted GaNxAs1−x alloys
Authors: Yu K. M. , Walukiewicz W. , Wu J. , Shan W. , Beeman J. W. , Scarpulla M. A. , Dubon O. D. , Ridgway M. C. , Mars D. E. , Chamberlin D. R.
Published: October 2003

We demonstrate the mutual passivation phenomenon of Ge donors and isovalent N in highly mismatched alloy GaNxAs1−x doped with Ge. Layers of this alloy were formed by the sequential implantation of Ge and N ions followed by pulsed laser melting and rapid thermal annealing. The mutual passivation effect results in the electrical deactivation of GeGa donors (Ge on Ga sites) and suppression of the NAs (N on As sites) induced band gap narrowing through the formation of GeGa–NAs nearest neighbor pairs. These results in combination with the analogous effect observed in Si-doped GaNxAs1−x provide clear evidence of the general nature of the mutual passivation phenomenon in highly mismatched semiconductor alloys.
Thermal conductivity of individual silicon nanowires
Authors: Li Deyu , Wu Yiying , Kim Philip , Shi Li , Yang Peidong , Majumdar Arun
Published: October 2003

The thermal conductivities of individual single crystalline intrinsic Si nanowires with diameters of 22, 37, 56, and 115 nm were measured using a microfabricated suspended device over a temperature range of 20–320 K. Although the nanowires had well-defined crystalline order, the thermal conductivity observed was more than two orders of magnitude lower than the bulk value. The strong diameter dependence of thermal conductivity in nanowires was ascribed to the increased phonon-boundary scattering and possible phonon spectrum modification.
Detection of oxygen vacancy defect states in capacitors with ultrathin Ta2O5 films by zero-bias thermally stimulated current spectroscopy
Authors: Lau W. S. , Leong L. L. , Han Taejoon , Sandler Nathan P.
Published: October 2003

Defect state D (0.8 eV) was experimentally detected in Ta2O5 capacitors with ultrathin (physical thickness <10 nm) Ta2O5 films using zero-bias thermally stimulated current spectroscopy and correlated with leakage current. Defect state D can be more efficiently suppressed by using N2O rapid thermal annealing (RTA) instead of using O2 RTA for postdeposition annealing and by using TiN instead of Al for top electrode. We believe that defect D is probably the first ionization level of the oxygen vacancy deep double donor. Other important defects are Si/O-vacancy complex single donors and C/O-vacancy complex single donors.
Quantitative assessment of Al-to-N bonding in dilute Al0.33Ga0.67As1−yNy
Authors: Wagner J. , Geppert T. , Köhler K. , Ganser P. , Maier M.
Published: October 2003

A quantitative assessment of the group III–nitrogen bonding in low N-content Al0.33Ga0.67As1−yNy with y⩽0.04 has been performed, using vibrational mode Raman spectroscopy for the quantitative analysis of local bond formation in combination with energy dispersive x-ray analysis and secondary ion mass spectrometry for chemical analysis. Clear evidence is obtained for the preferential bonding of nitrogen to Al with one nitrogen atom being coordinated to, at the average, 3.4 Al neighbors. This strong preference for Al-to-N bond formation can be understood in terms of the much larger cohesive energy of the Al–N bond compared to the Ga–N chemical bond. In spite of this phase-separation-like formation of local Al–N complexes, the fundamental band gap and the E1/E1+Δ1 band gaps show a continuous low-energy and high-energy shift, respectively, upon the addition of nitrogen as already known from dilute GaAsN.
Self-assembled SiGe quantum rings grown on Si(001) by molecular beam epitaxy
Authors: Cui J. , He Q. , Jiang X. M. , Fan Y. L. , Yang X. J. , Xue F. , Jiang Z. M.
Published: October 2003

SiGe quantum rings (QRs) were grown by partially capping on Ge quantum dots (QDs) on Si(001). Atomic force microscopy images show the shape transformation from QDs to QRs. Initial capping, with a Si layer thickness less than 2 nm, will result in the decrease of height of QDs and increase of base diameter of QDs. Capped with a Si layer, QDs will change into QRs. The mechanism of transformation from QDs to QRs is discussed. The strain will redistribute after capping, thus the strain energy relief, together with high Ge surface diffusion and Ge surface segregation at a relative high temperature of 680 °C, play the dominant role.
Extrafloral nectaries in an Australian rainforest: structure and distribution
Authors: Blüthgen Nico , Reifenrath Kerstin
Published: October 2003

Extrafloral nectaries (EFNs) are of ecological, evolutionary and taxonomic importance in many plants, but are often overlooked in botanical descriptions and have rarely been studied in humid Australian forests. We examined EFNs in a tropical rainforest in northern Queensland, Australia. A total of 29 plant species was found bearing EFNs within the 1-ha study plot at the Australian Canopy Crane Project and an additional 10 EFN species were found in rainforests and other habitats outside, but nearby, the plot. The records include 12 genera in which EFNs have not been previously reported (Ardisia, Bambusa, Castanospermum, Dysoxylum, Melicope, Flagellaria, Glochidion, Ichnocarpus, Merremia, Rockinghamia, Syzygium, Wrightia), including one new family (Flagellariaceae). In the study plot, 13 tree species (17% of tree species with dbh >10 cm), 10 climbing plant species (21%) and six shrubs had EFNs, a similar proportion compared with tropical forests on other continents. Morphology of most EFNs was studied by using scanning electron and light microscopy. Extrafloral nectaries were assigned to five different structural types (sensu Zimmermann 1932): flattened, elevated, pit, scale-like and formless nectaries. EFNs from all species were regularly visited by ants, allowing detection of many otherwise inconspicuous nectaries.
Identification of intracellular calcium oxalate crystals in Chamelaucium uncinatum (Myrtaceae)
Authors: Macnish Andrew J. , Irving Donald E. , Joyce Daryl C. , Vithanage Vasanthe , Wearing Alan H. , Webb Richard I. , Frost Ray L.
Published: October 2003

Intracellular inclusions in the pedicel and calyx-tube tissues of Chamelaucium uncinatum Schauer (Myrtaceae) flowers are irregular in shape. They were shown, by polarised light and scanning electron microscopy, to be birefringent 8.9–29.5 μm druse (i.e. aggregate) crystals. Energy-dispersive X-ray spectroscopy showed that these crystals were predominantly composed of calcium. Histochemical and acid-solubility tests indicated that the crystals were calcium oxalate. Raman microprobe spectroscopy was used to confirm this chemical identity. The calcium oxalate crystals were located in xylem-vessel lumens and also in parenchyma cells adjacent to vascular tissues. Thus, the crystals may function to regulate soluble calcium concentrations in C. uncinatum tissues near sites where calcium is unloaded from the xylem.
Impacts of ecosystem fragmentation on plant populations: generalising the idiosyncratic
Authors: Hobbs Richard J. , Yates Colin J.
Published: October 2003

Fragmentation of natural vegetation is one of the most pervasive changes in terrestrial ecosystems across the Earth. Developing a general understanding of how fragmentation affects plant and animal populations is essential to meet the pressing need for guidelines for the management of fragmented systems. Nevertheless, this general understanding has to take account of differences in ecosystem types and different biogeographic, evolutionary and ecological backgrounds against which fragmentation impacts are played out in different parts of the world. Here, we examine fragmentation impacts on plant populations by considering the processes underlying fragmentation. We suggest that it is critical to focus on the key processes that are important in particular situations, rather than assuming that the same factors are likely to be important everywhere. In other words, there are inevitable limits to generalisation because of the idiosyncratic nature of the geography, history and biota of different regions. Studies on the effects of fragmentation on plant populations have focused on a limited subset of plant types and have concentrated heavily on reproductive output rather than actual regeneration success. These studies have indicated a clear impact of fragmentation on fecundity, but there is no clear signal in terms of the actual importance of this in relation to population viability. Other factors including local habitat conditions, disturbance and competition from weeds may be just as important as the classical biogeographical impacts of fragmentation. Generalisations based on a clear assessment of key life-history processes may be valuable tools in developing management responses to ecosystem fragmentation, but this requires considerably more emphasis on factors affecting successful recruitment as well as factors affecting fecundity.
Meiotic chromosome behaviour and Boronia (Rutaceae) genome reorganisation
Authors: Shan F. , Yan G. , Plummer J. A.
Published: October 2003

Meiotic observation of nine genotypes of seven Boronia Sm. species revealed that B. megastigma Bartling (2n = 14), B. molloyae J.R.Drumm. (2n = 16), B. purdieana Diels (2n = 18), B. pinnata Sm. (2n = 22) and B. chartacea P.H.Weston (2n = 32) behaved as diploids during meiosis. B. coerulescens F.Muell. (2n = 72) was a tetraploid. These species had normal homologous chromosome pairing and segregation during meiosis and high pollen viability of 82–99%. Base chromosome numbers for B. megastigma, B. molloyae, B. purdieana, B. pinnata, B. chartacea and B. coerulescens were 7, 8, 9, 11, 16 and 18, respectively. Irregularities were found in meiosis of B. heterophylla F.Muell., which had low pollen viability of 43–46%. Results indicated that chromosome number in B. heterophylla might be the result of dysploid reduction or aneuploid reduction with 'Red' a monosomic, whereas 'Cameo' and 'Moonglow' were double monosomics. Boronia genome appeared volatile and genome repatterning in Boronia is still occurring.
Does chemical defence decline more in developing leaves that become strong and tough at maturity?
Authors: Read Jennifer , Gras Emma , Sanson Gordon D. , Clissold Fiona , Brunt Charlotte
Published: October 2003

Leaves that are expanding cannot be very tough or strong because of the constraints of cell expansion, and therefore are particularly vulnerable to being eaten. We predicted that expanding leaves would be better defended chemically than mature leaves, and that this difference would be most pronounced in species whose leaves are tougher and stronger at maturity, i.e. that chemical defence declines as the leaf increases its mechanical defences. We tested this hypothesis by comparing leaf mechanical properties and total phenolics in three species with relatively tough and strong mature leaves (Doryphora sassafras Endl., Acmena smithii (Poir.) Merr. & Perry and Nothofagus moorei (F.Muell.) Krasser) and two species with soft mature leaves (Eucryphia moorei F.Muell. and Toona ciliata M.Roem.).A significantly higher concentration of total phenolics per leaf dry weight was recorded in expanding leaves than in mature leaves in D. sassafras, N. moorei and A. smithii, but not in the two soft-leaved species. However, the decline in total phenolics in mature leaves of D. sassafras, N. moorei and A. smithii was entirely explained by dilution caused by increased concentration of cell wall. The absence of any difference in 'protoplasmic' concentrations of phenolics is consistent with the view of polyphenols as 'immobile' defences. High protoplasmic concentrations of polyphenols in expanding leaves may be less likely in species whose leaves become toughened and strengthened at maturity if they cannot quickly reclaim the chemical defence as its defence value declines. Instead, these species may be predicted to exhibit higher levels of mobile defences in expanding leaves. Despite the higher concentrations of phenolics in expanding leaves of D. sassafras and N. moorei they were eaten more by a generalist herbivore, Epiphyas postvittana, than were mature leaves, consistent with the higher nitrogen concentration in leaves that required less force and energy to chew.
Developmental morphology of ovules and seeds of Austrobaileyales
Authors: Yamada Toshihiro , Imaichi Ryoko , Prakash Nallamilli , Kato Masahiro
Published: October 2003

Development of ovules of Illicium anisatum (Illiciaceae), Trimenia moorei (Trimeniaceae), and Austrobaileya scandens (Austrobaileyaceae) (Austrobaileyales) was observed. In Austrobaileya scandens and Trimenia moorei the outer integument is hood-shaped, while it is cup-shaped in Illicium anisatum. On the basis of a phylogeny, the ovule with the hood-shaped outer integument is suggested to be primitive in Austrobaileyales. Seed development of Austrobaileyales was also examined. In Austrobaileya scandens the seed is mesotestal, ruminated, not pachychalazal, and has a micropyle–hilum complex. In Trimenia moorei the seed is exotestal, perispermous, not pachychalazal, and has a micropyle–hilum complex and a circular cap. The seed of Illicium anisatum is exotestal, not pachychalazal, and has a circular cap. Taking the character states of other basal angiosperms into account, primitive seeds of angiosperms are inferred to have such characters as the unilayered exotestal mechanical tissue, circular cap, micropyle–hilum complex and non-pachychalazy. The inferred primitive seed is very simple, suggesting that a great diversity of seeds is established through elaboration of organs/tissues of seeds, and not through reduction as hypothesised previously.
Structures of feeling and socio‐cultural formations: the significance of literature and experience to Raymond Williams's sociology of culture
Authors: Filmer Paul
Published: October 2003

Williams elaborates the concept of structures of feeling in different ways at important points in his writings. This gives it a particular methodological significance in relating the extraordinariness of imaginative literature to the ordinariness of cultural process. It is employed particularly to show the significance of literature for the articulation of alternatives to dominant world views, and thus to the politics of social change. Williams's different formulations of the concept are discussed in terms of their ways of relating reflexive experience to institutional structures and in relation to the genetic structuralism of Goldmann and Bourdieu's concepts of habitus and cultural field. Three types of criticisms are considered, which have in common the contention that the concept is unclear. Operationalized in analysing literature and its symbols, it can contribute towards clarification of the complexity of the processes of reflexive communication of experience which are at the root of social order and change.
Of Jewels and Horses: The Career and Patronage of an Iranian Merchant under Shah Jahan
Authors: Lambourn Elizabeth
Published: October 2003

“Seeing that cAli Akbar is a merchant and knowledgeable about jewels and horses it i s probable that he will be able to administer ports in a fitting manner.”

Events of 1056/1646, Lahawrī's Pādshāh Nāmah

Though Cambay is Now a Provincial Backwater, for Over Five Centuries—between the late tenth and the mid-sixteenth centuries A.D.—it was the main port of western India, home to a cosmopolitan population of merchants and traders from all over India and the Islamic world, and a major center of architectural and artistic patronage. Cambay is probably best known among Islamic art historians for its monumental fourteenth-century Friday mosque, the adjacent Kazaruni tomb complex (d.734/1333), and the large body of thirteenth- and fourteenth-century Islamic inscriptions and tombstones that survives there. However, the port conceals many Islamic remains that have not been published.
Imperialism & International Governance: The Case of US Policy towards Africa
Authors: Biel Robert
Published: October 2003

This article argues that capitalism requires a structure of international governance, and that this can fruitfully be interpreted by integrating elements of the imperialism perspective with international relations theory. A key issue is the study of the interface between country-level governance and that of the international system itself. Capitalism needs to adapt from a relatively simple state-centric model of international governance to one which encompasses and tries to exploit an environment peopled by regimes, non-governmental organisations, 'international civil society', and rapidly developing international law. But it seems that that this tendency is incompatible with an underlying imperative of deploying pure force in the selfish interests of the dominant powers, particularly the United States.
Regulating Capital in Accumulation: Negotiating the Imperial 'Frontier'
Authors: Bracking Sarah
Published: October 2003

There are three major propositions that underpin this article. First that the poorest countries are still incorporated into the global economy in adverse terms, or in a way once described by the dependency and neo-marxist schools as 'dependent'. Second, that this is not because of neutral, market driven features of globalisation or comparative advantage, but by deliberate and political intervention by people and institutions of the richer countries, moderated by the behaviour of (African and other) political elites. I shall model this interaction institutionally and propose that this serves as a 'Keynesian global multiplier' for investors, but provides very limited gains to host countries. Third, that African states have developed their own means of creating markets and state-sponsored means of accumulation, primarily by processes of local content rules, indigenisation and empowerment. These are inevitably subject to contextual questions of legitimacy. The article concludes that the current conceptualisation of government as essentially outside the market prevents us from understanding these emerging institutional structures and economic multipliers; it also disables consideration of the types of redistributive policy that are so essential for socio-economic recovery.
Reflections on Somaliland & Africa's Territorial Order
Authors: Spears Ian S.
Published: October 2003

This article examines the arguments for and against reforming the African state system in order to create more viable and peaceful states. It argues that while such a process has the potential to be enormously disruptive, selective recognition of some 'states-within-states', such as Somaliland, does offer promising approaches to more effective governance and more viable and coherent states.
Regulating Illicit Trade in Natural Resources: The Role of Regional Actors in West Africa
Authors: Aning Emmanuel
                      Kwesi
Published: October 2003

This article explores the multiple efforts that have been initiated by regional actors in West Africa, mainly ECOWAS, 1 to regulate the illicit trade in natural resources in the context of armed conflicts. It then examines the behaviour of 'spoilers' who are able to circumvent the sanctions regime and governments' domestic regulation. The paper argues that the characteristics and multiple dynamics of the armed conflicts in West Africa have created specific opportunities for economic activities in a thriving parallel economy through the 'illicit' trade in natural resources.
Personality characteristics ascribed to young women who drink alcohol
Authors: JONES SANDRA C. , ROSSITER JOHN R.
Published: October 2003

This study employs an implicit personality rating methodology from marketing research (the “shopping list” method) to investigate young adults' perceptions of young women who drink alcoholic beverages. Whereas there were some differences in perceptions of young women drinkers across the alcohol brands, the greatest differential in the personality ratings was caused by the mere presence or absence of alcohol. Young women who drink alcohol were described as being more “interesting” and “self‐assured” than young women who do not drink. These positive traits were reliably ascribed to young women drinkers by both young adult men and young adult women and more strongly by those who themselves drink. Although it is possible that young women drinkers really are differentially interesting and self‐assured, a more likely contributor to these perceptions is advertising aimed at the female drinker.
‘It was a nice day … a beautiful day’: an analysis of relapse into substance misuse among Indigenous drinkers
Authors: ALATI ROSA , LIAMPUTTONG PRANEE , PETERSON CHRIS
Published: October 2003

This paper presents results from a study investigating relapse prevention options for indigenous clients of alcohol and drug intervention services. The study has 63 ‘stories’ collected through a survey of nine substance misuse services. An adapted version of the Marlatt Relapse Prevention Model was developed to interview clients who had quit drinking but later relapsed into heavy use. The study identified situations influencing the decision to quit, obstacles and dilemmas arising during periods of abstinence, and major triggers associated with relapse into substance misuse. The paper analyses these major triggers and discusses the crucial issues of motivation to quit and maintenance of abstinence. The community environments where indigenous drinkers use alcohol strongly influence successful or unsuccessful attempts to quit. Relapse prevention should be part of a range of public health strategies for tackling substance misuse problems with Indigenous drinkers, and should be included at the minimal intervention level.
Cars after Financialisation: A Case Study in Financial Under-Performance, Constraints and Consequences
Authors: Froud Julie , Haslam Colin , Johal Sukhdev , Williams Karel
Published: October 2003

This paper presents data on the financial results achieved in the 1990s by 12 major car assemblers from the USA, Europe and Japan. While some assemblers have defensible records of share price appreciation, their return on capital employed is generally mediocre and well below the level that US and UK stock markets require. This under-performance reflects ubiquitous product market constraints and, specifically, spreading direct competition, which leaves many assemblers precariously dependent on the few segments where indirect competition prevails and where profits are divided between two or three incumbents. Financial under-performance persists into the 2000s because a variety of conditions, including family control and national differences in the valuation of car companies, inhibit a global restructuring that would raise profitability. Insofar as financial under-performance by assemblers has major consequences, the end result is to increase the messy and unresolved character of present day capitalism.
Does Europe Mean Americanization? The Case of Competition
Authors: Djelic Marie-Laure
Published: October 2003

This paper traces the process whereby competition has come to be valued in our economies. Taking a step back in history, we show how it all started not with competition but with cooperation in fact, in the last decades of the 19th century. Comparing Germany and the USA, we then show how national paths diverged after that. While cooperation remained the accepted and dominant rule in Europe, a particular understanding of competition, what we call oligopolistic competition, came to triumph in the United States. After World War II, this particular understanding was diffused to other parts of the world and particularly to Western Europe. When it comes to competition, we thus show that the basic and formal rules of the game that structure Europe today owe a lot, historically, to American models. However, we ponder in the conclusion on the limits to that process of “soft convergence”.
Distribution of the persistent organic pollutants, polycyclic aromatic hydrocarbons, between water, sediments and biota
Authors: Kirso U. , Paalme L. , Voll M. , Irha N. , Urbas E.
Published: October 2003

Polycyclic aromatic compounds continue to be regarded as a major environmental threat, especially in the aquatic environment. To gather further information on the distribution and levels of these persistent organic compound in natural waters, the current analytical study was carried out. Material collected from multiple sites within the coastal and open sea areas of several surface water bodies had different levels of polycyclic aromatic compounds.

Concentrations of dissolved, particle- and biota-associated compounds (i.e., benzo (a)pyrene, benzo(e)pyrene, pyrene, chrysene and so on) were measured by multiple analytical techniques. The sediment and biota samples were extracted using Soxhlet extraction followed by analysis using reverse-phased liquid chromatography with ultraviolet and fluorescence detection and high resolution luminescence spectroscopy. This group of pollutants was significantly enriched in particulate matter, sediments and biota material at all sites relative to water concentrations. On the basis of data obtained, the enrichment factors of 10 to 105 for different carcinogenic and noncarcinogenic compounds in the particulate material and biota are reported. Higher concentrations of the more hydrophobic compounds were found in sediments. Thus, the bottom biota may be exposed to higher levels of hydrophobic pollutants than organisms residing in the upper sediment-water interface.
Water toxicity assessment using medicinal leeches
Authors: Petrauskienë Laima
Published: October 2003

The medicinal leech (Hirudo medicinalis) is sensitive to various environmental changes. However, investigations on these leeches are restricted because of their scarcity in natural waters. Artificial of leeches makes possible the use of these animals in laboratory research. The aim of the present study to investigate changes of feeding behaviour and excretion rate following feeding in medicinal leeches exposed to different samples of water from Lake Drukshiai which provides the cooling waters for the Ignalina Power Plant (NPP). The following behavioural and physiological responses of medicinal leech exposed to of the Ignalina Nuclear Power Plant sampled in May and July 1997 were recorded: 1) feeding behaviour, that prolongation of the attachment process or a completely suppressed attachment reflex; 2) the size of blood meal; excretion rate after feeding. The most harmful changes of indices under study were caused by water from rain sewage: the highest percent of individuals with prolonged attachment process or completely attachment reflex; the smallest size of blood meal; the slowest excretion rate after feeding. Less severe were recorded after exposure to water from a waste water treatment plant. Water from Station 1, the remote monitoring station from Ignalina Nuclear Power Plant, showed the lowest effect on the medicinal in the majority of trials. The medicinal leech, due to its sensitivity, simplicity of measured indices and ease of maintenance can be used as a test-organism in studies of toxicity of polluted water.
Dissolved Oxygen, Chlorophyll a and Nutrients: Seasonal Cycles in Waters of the Gulf of Aquaba, Red Sea
Authors: Badran Mohammad Ismail
Published: October 2003

Seawater samples were collected weekly over fourteen months at 25 m intervals between the surface and 200 m from the offshore waters of the Gulf of Aqaba, Red Sea. Water temperature and dissolved oxygen concentration and percent saturation were measured in situ. Within two hours of sampling, samples were analysed for chlorophyll a, ammonia, nitrate, nitrite, phosphate and silicate. The temperature field depicted a well defined seasonal pattern of winter mixing from December to April and summer stratification from May to November. All other analysed parameters were intimately related to this pattern. Dissolved oxygen showed a maximum and homogeneous distribution in winter and a minimum in summer. Chlorophyll a showed a seasonal pattern close to that of dissolved oxygen, but with a distinct summer peak between 50 and 75 m. Ammonia was absent from the entire water column during summer and relatively abundant and homogeneously distributed in winter. Nitrite had a seasonal pattern similar to that of chlorophyll a and exhibited a summer subsurface maximum just below that of chlorophyll a. Nitrate, phosphate and silicate had similar seasonal patterns characterised by high concentrations in deeper water during summer overlaid by vanishingly low concentrations of nitrate and phosphate and relatively low in the case of silicate. In winter the three nutrients exhibited relatively high concentrations homogeneously distributed in the entire water column. These findings are analysed and discussed with reference to previous records from the Gulf of Aqaba and other oligotrophic water bodies.
Integrating mesocosm experiments with field and laboratory studies to generate Weight-of-Evidence risk assessments for ecosystem health
Authors: Cash Kevin J. , Culp Joseph M. , Dubé Monique G. , Lowell Richard B. , Glozier Nancy E. , Brua Robert B.
Published: October 2003

Assessing ecosystem health of large rivers is often complicated because these ecosystems receive multiple, interacting effluent discharges. Confounding factors, such as complicated mixing hydraulics and historical loading effects, can result in equivocal field data that lend weak inference to ecological risk assessments. Within Environment Canada's National Water Research Institute (NWRI) one approach to this problem develops a strategy that defines important mechanisms of pollutant effects through the combined use of laboratory and field measurements, riverside mesocosm experiments, and the incorporation of indicators at several trophic levels. We integrate these different types of information through weight-of-evidence postulates that provide logical guidelines for establishing causation in ecological risk assessment. Using this approach, retrospective risk assessments on a number of Canadian rivers indicates that the major effect of present effluent discharges from pulp mills has been one of nutrient enrichment and stimulation of food web productivity. The combination of field experiments with this weight-of-evidence approach yielded the scientific justification for a conceptual model that describes community shifts across a nutrient-contaminant gradient. The purpose of this is paper is to illustrate the utility of riverside mesocosms in assessing ecological impacts of point-source discharges. We conclude that the use of stream mesocosms with the weight-of-evidence approach is highly useful for establishing a mechanistic understanding of community responses to stressors at a regional scale. In addition, this approach will be useful when greater understanding of a particular class of anthropogenic stressors (e.g., specific types of effluent) is required to improve regulatory guidelines.
Environmental status of Yemen's Gulf of Aden coast determined from rapid field assessment and satellite imagery
Authors: Wilson G. , Price A. R. G. , Huntington T. , Wilson S. C.
Published: October 2003

Ninety-one sites covering 1400 km of the Gulf of Aden coast of Yemen were examined by rapid field assessment, yielding ordinal data on the extent of habitats, abundance of species groups and magnitude of human uses/environmental impacts. Satellite imagery was used to determine sea surface chlorophyll concentrations. Mangroves and seagrasses were largely absent, due to the high-energy conditions and unstable substrata. Coral development was also limited, principally because of cold upwelling sea temperatures. Macroalgal prevalence and abundance were greater on account of high nutrient levels. Nesting sites of three turtle species (Green, Hawksbill, and Loggerhead) were all impacted at low levels. Coastal construction was small-scale and located near larger towns (Al Mukalla, Foua and Shehir), while water- and land-based pollution and fishing were widespread but minimal. Fish abundance showed significant positive correlation with chlorophyll concentration. These and other associations observed probably involve causal links, although habitat effects and other factors may also be important. Classification of sites by cluster analysis using biological data and use/impact data separately revealed considerable environmental heterogeneity. The lack of clear geographical patterns contrasts with results from the Red Sea, where latitudinal related groupings using comparable biological data are evident.
Assessing Marine Ecosystem Health: The long-term effects of fishing on functional biodiversity in North Sea benthos
Authors: Bremner J. , Frid C. L. J. , Rogers S. I.
Published: October 2003

Assessments based on the taxonomic composition and relative abundance of taxa provide valuable information about the effects of anthropogenic activities on benthic systems. However, international agreements also require active conservation of ecosystem functioning as well as biological assemblages. We must therefore learn more about how ecosystems function and why changes occur within them in order to fully understand the implications of human activities.

Biological traits analysis allows systems to be described in terms of the characteristics of member taxa, describing functional diversity whilst retaining information on taxa distributions. This study used biological traits analysis to investigate the long-term effects of fishing on benthic infaunal communities.

Infaunal abundance was recorded over three decades at two stations, one within and one outside a fishing ground in the central western North Sea. Each taxon present was categorised for the degree to which it exhibited certain biological traits. The distribution of these traits within a sample produced a picture of functional diversity. Multivariate analyses were used to compare trait composition at the stations over time, thus depicting how community functioning responded to physical disturbance.

The assemblages at the two stations were functionally distinct at the onset of the study; with differences in size, feeding type and reproductive method. The functional structure changed over time at the station within the fishing ground as the level of exploitation varied. Large animals, predators, scavengers and those eating invertebrates or carrion dominated years of light effort in the fishing ground but were less represented when effort increased. No such changes occurred at the station outside the fishing ground.

Fishing seems to have some effect on benthic functional biodiversity and this effect is most obvious when moving from low to moderate levels. The differences between stations at the start of the timeseries may reflect variations in the physical environment or may result from effects of fishing that predate the timeseries.
Imperilled rivers of Australia: Challenges for assessment and conservation
Authors: Barmuta Leon A.
Published: October 2003

In Australia, riverine biodiversity (as judged by species diversity) is threatened by an array of anthropogenic effects common in industrialised countries (e.g. in-stream barriers, mining and sewage effluents, increased nutrient inputs, introduced species) as well as more diffuse, widespread phenomena characteristic of most of the arid and semi-arid areas of the world (e.g. salinisation and alteration of flows). Although much has been learned from specific case studies in the more populated areas, the nationally systematic efforts at quantifying these threats rely mostly on measures of river “condition” or “health” because measuring species diversity across areas as large as Australia is too expensive. However, these measures are incomplete representations of biodiversity, and some of the auditing processes compound other human values into their summaries of river condition or health. Furthermore, public perceptions of what rivers in Australia can deliver in terms of “ecosystem services” may not be feasible in many areas owing to the way that the Australian landscape has evolved. To avoid making the mistake of assuming that “good river health” automatically means “all biodiversity is conserved,” three advances are needed: appropriate conceptual frameworks of how a given river system functions, more research that clarifies the links between processes and biodiversity, and an understanding of the historical biogeography of the river biota so that we can provide a clear context for the first two items. Substantial progress has been made in developing and adapting conceptual models of river systems, research into processes is being initiated even in some remote, sparsely populated catchments, and much has been learned about the history and distribution of the flora and fauna. Key challenges remain in consolidating reliable empirical relationships between biodiversity and the surrogate variables used to measure it, estimating the rates of biodiversity change likely to accrue from climate change over the next millennium, and identifying biodiversity “hot spots” particularly for less than charismatic species.
Can conservation assessment criteria developed for terrestrial systems be applied to riverine systems?
Authors: Dunn Helen
Published: October 2003

Australia's aquatic ecosystems are of outstanding diversity and interest on a world scale. As one of the world's driest continents, its water resources are under growing pressure, yet there are no systematic conservation efforts. Any moves towards aquatic biodiversity conservation must be pursued within appropriate scientific, policy, and management contexts. A key starting point is the articulation of aquatic conservation values.

Concepts and criteria for biodiversity conservation are well established in the conservation of terrestrial ecosystems in Australia. They are often framed within legislation or derived through policy and practice. If freshwater biodiversity is to be conserved, then conservation criteria and methods of assessment need be integrated with possible mechanisms for protection. So it is useful to examine whether the criteria and thresholds applied to terrestrial systems are valid and appropriate for freshwater ecosystems.

Two key questions are discussed: are commonly applied conservation criteria appropriate and adequate for aquatic ecosystems? and, is it feasible to apply criteria used in terrestrial systems to aquatic systems? The discussion is informed by evidence from two perspectives: a survey of views of river scientists and managers, and analysis of field studies of river conservation assessments in Australia.

The data suggest that while the basic concepts that define biodiversity value can be applied to aquatic systems, difficulties are apparent in applying and interpreting the thresholds and decision rules used for terrestrial systems. In addition, the survey of scientists and managers in Australia showed that landscape scale values and riverine functions should be incorporated in the assessment and protection of riverine systems.

The analysis concludes that conservation of freshwater biodiversity in Australia needs to be founded upon national legislation and policies for biodiversity conservation alongside conservation of terrestrial systems. However, different approaches to defining and assessing biodiversity value of freshwater ecosystems will need to be explored and specified.
Characterization of environmental gradients using physico-chemical measurements and diatom densities in Nairobi River, Kenya
Authors: Ndiritu G. G. , Gichuki N. N. , Kaur P. , Triest L.
Published: October 2003

Degradation of water resources due to anthropogenic activities is a major problem all over the world. Monitoring changes in water quality is expensive but essential for management of water resources. Diatom assemblages can serve as useful indicators of changes in water quality. In order to determine changes in stream water quality in an urban environment, densities of epilithic diatom communities on both natural and artificial substrates were sampled in Nairobi River, Kenya in September 2000. Sampling of water and diatoms was carried out in almost equidistant sites along a 60 km stretch of the Nairobi River. Environmental (water physico-chemical and nutrients) data was explored by Principal Correspondence Analysis (PCA) and sites split into three groups of upper-, mid- and lower stream. Most abundant diatom taxa on both substrates were selected and their relationship with environmental variables determined.

On artificial substrates, Gomphonema parvulum, Nitzschia palea and Nitzschia umbonata were the most abundant and were significantly related with total dissolved solids, nitrate, conductivity and turbidity. Temperature, altitude and pH interacted significantly with dominant diatom species on natural substrates, which included Gomphonema parvulum, Nitzschia palea and Navicula subminuscula. Non-parametric analyses showed that diatom densities in natural and artificial substrates were significantly different and were affected by different environmental variables. Our results indicate that abundant diatom species can be used to describe major types of aquatic environmental gradients and can serve as good indicators of ecological conditions in tropical streams and rivers. This study also showed that diatoms from artificial and natural substrates can be used to provide complementary information.
Length at maturity and gillnet selectivity of Lake Tana's Barbus species (Ethiopia): Implications for management and conservation
Authors: de Graaf M. , Machiels M. , Wudneh T. , Sibbing F. A.
Published: October 2003

Lake Tana's 15 large Barbus species form the only known intact endemic cyprinid species flock left in the world. The barbs contribute around one third of the total annual catch of the motorised commercial gillnet fishery which was introduced in 1986. A dramatic reduction of the adult Barbus stocks and the even lower proportion of recruits at the end of the 1990s, show the necessity for the development, implementation and control of fisheries legislation in Lake Tana. The reproductive biology of the Barbus species, essential for fishery management, is poorly known. This paper presents results on size at maturity, size at harvest and gillnet selectivity curves, which can be used to provide a scientific base for management proposals. Size at maturity varied widely among the Barbus species, ranging from 18.8 cm in Barbus brevicephalus to 44.3 cm in Barbus crassibarbis. Males matured at smaller size and reached smaller maximum length than females. Estimated selectivity curves fitted closely or were slightly larger than the observed length-frequency distribution of the commercial catch. The vast majority (85%) of barbs landed by the commercial gillnet fishery were mature. Fishing pressure on juvenile, immature fish is unlikely to be the cause of the observed decrease in Barbus stocks. Size control regulations like mesh size restrictions, intended to protect the immature part of fish populations are expected to have little positive effects on the Barbus stocks and are therefore not recommended. The drastic reduction in barbs during the 1990s is most like due to recruitment overfishing, that is, poorly regulated high fishing effort by the commercial gillnet fishery on the spawning aggregations of adult barbs during their annual breeding migration in river mouths and surrounding floodplains. Only effort control regulations limiting the gillnet fishery in the spawning season and/or areas will prevent a total collapse of the Barbus stocks as has happened to other cyprinids in African lakes. Such measures have to be implemented urgently to guarantee the conservation of Lake Tana's unique biodiversity as a sustainable source of cheap protein and as a natural laboratory to study the evolutionary processes underlying speciation in freshwater fish.
Spatial distribution of phytoplankton and picocyanobacteria in Lake Tanganyika in March and April 1998
Authors: Vuorio Kristiina , Nuottajärvi Marja , Salonen Kalevi , Sarvala Jouko
Published: October 2003

The spatial distribution of phytoplankton and picocyanobacteria was studied in Lake Tanganyika in relation to environmental factors. Sampling was conducted within three weeks during the wet season of 1998 when the water column stratification was most stable. The secchi depth varied between 11 and 16 m, except off the river Malagarasi (3 m). The depth of the euphotic zone was 33 to 56 m. Altogether, 218 phytoplankton taxa were identified. Their total biomass varied between 13 and 88 mg m−3 fresh weight. Picocyanobacteria were present at very high densities (104 to 6 × 10 5 cells ml−1). The influence of the river Malagarasi appeared to spread along the water surface because of the lower density of the river water. The phytoplankton species number and biomass were particularly high near the river mouth. Excluding that area, there were no statistically significant differences in the species composition among study sites. Nevertheless, differences in water column mixing, indicated by variable temperature gradients, seemed to affect the horizontal distribution of at least some phytoplankton species.
Using Social Marketing to Promote a Healthy Diet and Physical Activity: The Need for Training Public Health Professionals
Authors: Cassady Diana , Culp Jennifer , Watnik Mitchell
Published: October 2003

The current public health workforce may not be prepared for the challenge of implementing social marketing programs, as there is only limited training on social marketing offered by schools of public health. Therefore, training programs for working public health professionals may be warranted. An inventory of current social marketing resources revealed a variety of conferences, journals, and World Wide Web sites that either include or are devoted to social marketing. However, a survey of public health professionals who have direct responsibility for social marketing programs indicates that they use these resources in only a limited fashion. Recommendations include marketing current training resources to increase their use by working professionals, expanding the number and location of training conferences, and exploring opportunities for distance education.
Promoting Health & Preventing Disease: How Will We Meet the Challenge of Behavior Change?
Authors: Syme S. Leonard
Published: October 2003

Approximately half of all causes of mortality in the United States are linked to behavioral factors such as smoking, diet, alcohol use, sedentary lifestyle and accidents (McGinnis & Foege, 1993). One very promising strategy for promoting health and preventing disease, therefore, is to help people change behaviors that increase disease risk—but helping people do this has proven to be a very difficult and challenging problem. One would think that if we informed people of their risks they would rush home and, in the interests of good health, change behaviors that caused the risk. Some people do, but most do not (Smedley & Syme, 2000).
Heparan sulfate regulates amyloid precursor protein processing by BACE1, the Alzheimer's β-secretase
Authors: Scholefield Zoe , Yates Edwin A. , Wayne Gareth , Amour Augustin , McDowell William , Turnbull Jeremy E.
Published: October 2003

Cleavage of amyloid precursor protein (APP) by the Alzheimer's β-secretase (BACE1) is a key step in generating amyloid β-peptide, the main component of amyloid plaques. Here we report evidence that heparan sulfate (HS) interacts with β-site APP-cleaving enzyme (BACE) 1 and regulates its cleavage of APP. We show that HS and heparin interact directly with BACE1 and inhibit in vitro processing of peptide and APP substrates. Inhibitory activity is dependent on saccharide size and specific structural characteristics, and the mechanism of action involves blocking access of substrate to the active site. In cellular assays, HS specifically inhibits BACE1 cleavage of APP but not alternative cleavage by α-secretase. Endogenous HS immunoprecipitates with BACE1 and colocalizes with BACE1 in the Golgi complex and at the cell surface, two of its putative sites of action. Furthermore, inhibition of cellular HS synthesis results in enhanced BACE1 activity. Our findings identify HS as a natural regulator of BACE1 and suggest a novel mechanism for control of APP processing.