Home  About us  Contact
 

Research Areas (research + area)

Distribution by Scientific Domains
Life Sciences28%
Chemistry16%
Medical Sciences15%
Engineering7%
Polymers and Materials Science6%
Humanities and Social Sciences6%
Physics and Astronomy5%
Business, Economics, Finance and Accounting4%
Education3%
Information Science and Computing2%
3 Other Domains8%
Distribution within Life Sciences
Ecology & Organismal Biology25%
Cell & Molecular Biology7%
14 Other Subdomains68%

Kinds of Research Areas

  • important research area
  • priority research area
    		•
  • sengwa wildlife research area
  • wildlife research area
    		•

    Selected Abstracts

    The Emergence and Institutionalisation of the European Higher Education and Research Area

    EUROPEAN JOURNAL OF EDUCATION, Issue 4 2008
    ERIC BEERKENS
    Since the European unification project started in the 1950s, rules, regulations and policies have been formulated by the European Union (and its predecessors) to facilitate the flow of products and people; those who benefited from the increasing transnational exchange urged European actors to remove remaining obstacles and further facilitate European trade and mobility. In the field of higher education and research, this transnational activity has led to the emergence of European rules, a strengthening of European institutions and the development of a European higher education and research community. In other words, it has led to the institutionalisation of the European higher education and research area (EHERA). The argument put forward in this article is that these three dimensions and the increase in transnational activity shape a dynamic process of which further integration of the EHERA is likely to be a result. [source]

    Doctoral and Postdoctoral Education in Science and Engineering: Europe in the international competition

    EUROPEAN JOURNAL OF EDUCATION, Issue 4 2005
    PHILIPPE MOGUÉROU
    In this article, we discuss the recent evolutions of science and engineering doctoral and postdoctoral education in Europe. Indeed, Ph.Ds are crucial to the conduct of research and innovation in the national innovation systems, as they provide a large amount of input into creating the competitive advantage, notably through basic research. First, we show that Asia, and notably China, is producing more Ph.Ds than the United States and Europe. In many EU countries, the number of Ph.Ds has levelled off or even declined recently in many natural sciences and engineering fields. Second, we discuss the European situation in the international competition for talents. We study the European brain drain question, mainly at the doctoral and postdoctoral level. We find that there is an asymmetry in the flows of Ph.D students and postdoctorates between Europe and the United States, at the advantage of this latter country. These two points , production of Ph.Ds, international flows of doctorates and postdoctorates , lead us to be concerned about the future growth and innovation in Europe. In conclusion, we outline some European policy responses in the perspective of building the European Research Area and the European Higher Education Area. [source]

    The European Science Foundation Promotes Excellence in Materials Science Research

    ADVANCED MATERIALS, Issue 10-11 2009
    Antonella di Trapani
    The European Science Foundation (ESF) with its 34,year history in funding scientific networking activities that span across European borders has been the instigator of several programs within the field of materials science. The main results of these programs have made a real impact in the field, and are contributing to a new class of researchers that will be the leaders of the European Research Area. [source]

    Evaluation of the effectiveness of an early peripheral burning strategy in controlling wild fires in north-western Zimbabwe

    AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
    Isaac Mapaure
    Abstract A review of the occurrence of wild fires in Sengwa Wildlife Research Area (SWRA), Zimbabwe, is presented for the period 1965,1993. The effectiveness and desirability of early burning of peripheral areas introduced in 1979 are evaluated. More than 75% of wild fires occurred between July and October, 48.6% of which originated from communal lands. Early burning of peripheral areas led to significant reductions in extent of areas burnt, from annual mean areas of 115 km2 (1965,1978) to 11 km2 (1979,1993) because of effective control of fires, which originated from communal lands. Some areas did not burn at all after 1979, and the overall probability of burning dropped from 0.484 to 0.187. Whilst it may be desirable to keep fires out of SWRA in the short term, fuel build-ups increase the fire hazard resulting in negative consequences on biodiversity in the long term. Consideration should be given to combine peripheral burning with low-intensity prescribed burning of selected blocks to keep a semblance of natural fire regimes to ensure the maintenance of biodiversity while simultaneously reducing the fire-hazard. An integrated fire management plan should be put in place for SWRA. Résumé Ici est passée en revue l'occurrence de feux sauvages dans l'Aire de recherche sur la faune sauvage de Sengwa (SWRA), au Zimbabwe, pour la période 1965,1993. L'efficacité et l'opportunité des feux précoces des zones périphériques, introduits en 1979, sont aussi évaluées. Plus de 75% des feux sauvages avaient lieu entre juillet et octobre, dont 48,6% trouvaient leur origine dans des terres communales. Le brûlage précoce des zones périphériques a conduit à des réductions significatives des superficies brûlées, qui sont passées d'une moyenne annuelle de 115 km2 (1965,1978) à 11 km2 (1979,1993) grâce au contrôle efficace des feux qui commençaient dans les terres communales. Certaines zones n'avaient pas brûlé du tout depuis 1979, et la probabilité globale de brûler a chuté de 0,484 à 0,187. S'il est, à court terme, souhaitable de préserver la SWRA contre les feux, l'accumulation de matières combustibles augmente les risques de feux qui pourraient avoir, à long terme, des conséquences négatives sur la biodiversité. Il faudrait envisager de combiner les feux en périphérie avec des feux programmés, de faible intensité, de certains blocs sélectionnés, pour conserver un semblant de régime naturel de feux et ainsi garantir le maintien de la biodiversité tout en réduisant les risques de feux. Il faudrait instaurer un plan de gestion des feux pour la SWRA. [source]

    Changes in miombo woodland cover in and around Sengwa Wildlife Research Area, Zimbabwe, in relation to elephants and fire

    AFRICAN JOURNAL OF ECOLOGY, Issue 3 2002
    Isaac N. Mapaure
    Abstract One of the consequences of impacts of elephants and fire on woodlands is a change in woody cover, which often results in major challenges for wildlife managers. Changes in miombo woodland cover in and around Sengwa Wildlife Research Area (SWRA) between 1958 and 1996 were quantified by analyzing aerial photographs. Woody cover in SWRA decreazed from 95.2% in 1958 to 68.2% in 1996, with a lowest mean of 62.9% in 1983. The annual absolute rate of woody cover change in SWRA increazed from ,1.1% per annum between 1958 and 1964 to a recovery of 1.6% per annum between 1993 and 1996, while the annual relative rate increazed from ,1.1% per annum between 1958 and 1964 to 3.3% per annum between 1993 and 1996. There was a strong negative correlation between elephant densities and woody cover in SWRA, suggesting that loss of woody cover was mainly due to elephants. Woodland recovery after 1983 was due to reductions in elephant populations through legal and illegal off-take and reductions in fire frequency. Surrounding areas experienced less woody cover losses than SWRA, mainly due to tree removal by locals whose densities increazed after the eradication of tsetse fly in the 1970s. Résumé Une des conséquences de l'impact des éléphants et des feux sur les forêts s'exprime par un changement du couvert ligneux qui pose souvent de fameux défis pour les gestionnaires de la faune. Les changements du couvert forestier à Miombo, qui sont survenus à l'intérieur et aux alentours de l'Aire de Recherche sur la Faune de Sengwa (SWRA) entre 1956 et 1996, ont été quantifiés grâce à l'analyse de photos aériennes. Le couvert forestier de la SWRA a diminué de 95.2% en 1958 à 68.2% en 1996, la moyenne la plus basse étant observée en 1983, avec 62.9%. Le taux annuel absolu de changement du couvert forestier dans la SWRA est passé de , 1.1% par an entre 1958 et 1964 à une restauration de 1.6% par an entre 1993 et 1996, tandis que le taux annuel relatif augmentait de , 1.1% par an entre 1958 et 1964 à 3.3% par an entre 1993 et 1996. Il existait une forte corrélation négative entre la densité des éléphants et le couvert forestier de la SWRA, ce qui laisse supposer que la perte de couvert forestier était due principalement aux éléphants. La restauration de la forêt après 1983 était due à des réductions des populations d'éléphants suite à des prélèvements, légaux ou non, et à une baisse de la fréquence des feux. Les zones adjacentes ont subi de moins fortes pertes du couvert forestier que la SWRA, et celles-ci étaient principalement dues à des coupes faites par les locaux dont la densité a augmenté suite à l'éradication de la mouche tsé-tsé dans les années 1970. [source]

    Cyclic voles, prey switching in red fox, and roe deer dynamics , a test of the alternative prey hypothesis

    OIKOS, Issue 2 2003
    Petter Kjellander
    Medium-sized predators sometimes switch to alternative prey species as their main prey declines. Our objective of this study was to test the alternative prey hypothesis for a medium sized predator (red fox, Vulpes vulpes), a small cyclically fluctuating main prey (microtine voles) and larger alternative prey (roe deer fawns, Capreolus capreolus). We used long-term time series (28 years) on voles, red fox and roe deer from the Grimsö Wildlife Research Area (59°40,N, 15°25,E) in south-central Sweden to investigate interspecific relationships in the annual fluctuations in numbers of the studied species. Annual variation in number of roe deer fawns in autumn was significantly and positively related to vole density and significantly and negatively related to the number of fox litters in the previous year. In years of high vole density, predation on roe deer fawns was small, but in years of low vole density predation was more severe. The time lag between number of fox litters and predation on fawns was due to the time lag in functional response of red fox in relation to voles. This study demonstrates for the first time that the alternative prey hypothesis is applicable to the system red fox, voles and roe deer fawns. [source]

    Diet of free-ranging domestic dogs (Canis familiaris) in rural Zimbabwe: implications for wild scavengers on the periphery of wildlife reserves

    ANIMAL CONSERVATION, Issue 1 2002
    J. R. A. Butler
    Numbers of free-ranging dogs (Canis familiaris) have reached unprecedented levels in Zimbabwean communal lands (agropastoralist rural areas). This study examined the potential competitive interactions between dogs and wild scavengers on the boundary of Gokwe Communal Land (GCL) and the Sengwa Wildlife Research Area (SWRA) in 1995,96. Dietary studies showed that dogs were primarily scavengers of human waste and animal carcasses. Twelve experimental carcasses indicated that dogs were the most successful species in the vertebrate scavenger guild, consuming 60% of available biomass and finding 66.7% of carcasses. Dogs monopolized the supply of domestic animal carrion within GCL, but also consumed wild carrion up to 1 km within the SWRA, and were seen 3 km inside the reserve. Their principal competitors for carcasses were vultures, and to a lesser degree lions (Panthera leo), leopards (P. pardus) and spotted hyaenas (Crocuta crocuta). Dogs outcompete vultures on wildlife reserve boundaries owing to their high densities, nocturnal and diurnal activity, physical dominance and greater tolerance of human disturbance. With a population growth rate of 6.5% per annum the influence of dogs will intensify on the peripheries of reserves, exacerbating their existing threat to wild scavengers. This scenario is probably occurring in many other African countries. [source]

    Multimethodological approach to investigate chamber tombs in the Sabine Necropolis at Colle del Forno (CNR, Rome, Italy)

    ARCHAEOLOGICAL PROSPECTION, Issue 2 2009
    Salvatore Piro
    Abstract Non-destructive geophysical prospecting methods are increasingly used for the investigation of archaeological sites, especially where a detailed physical and geometrical reconstruction of structures is required prior to any excavation work. Often, due to the limited size and depth of an archaeological structure, it may be rather difficult to single out its position and extent because of the generally low signal-to noise (S/N) ratio. This can be overcome by improving data acquisition and processing techniques and integrating different geophysical methods. In this work the results of a multimethodological surveys, used with the aim of detecting sharp discontinuities (boundary of cavities and fractures in the host medium) at the Archaeological Test Site of Sabine Necropolis at Research Area of National Research Council of Rome (Montelibretti, Italy) are shown. For the survey a combination of passive and active methods (magnetic, ground-penetrating radar (GPR), and dipole,dipole geoelectric (DDG)), topographical and three-dimensional laser scanner surveys and archaeological excavations were used to study the state of conservation of underground tombs. With all geophysical methods a high-resolution data acquisition was adopted with the aim of reconstructing a global vision of the study area. Signal processing and amplitude time-slice representation techniques were used for the analysis of GPR data. The bi-dimensional cross-correlation technique was applied to enhance the S/N ratio of the magnetic data. An example of the integration (both qualitative and quantitative) of these results is presented for a portion of the investigated area in the Sabine Necropolis at Colle del Forno (Rome, Italy). Archaeological excavations were then conducted systematically after completing the geophysical surveys and interpretations (from 2000 to 2006), which confirmed the location and shape of the individual chamber tombs with associated corridors. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Times, Measures and the Man: the Future of British Higher Education Treated Historically and Comparatively

    HIGHER EDUCATION QUARTERLY, Issue 2 2006
    Guy Neave
    This article is a tribute to the life work of Maurice Kogan. Very little of higher education's landscape in the United Kingdom has remained unchanged over the past four decades and this article sets out to analyze the way the perception of the role of universities in society has changed in the intervening period. This it does through three perspectives: continuity and change, continuity in change and continuity in the midst of change. Each yields very different visions of the university. Against this ,inside' view, the second part of the article examines current British higher education policy from an ,outsider' standpoint and very particularly the current strategies towards the European Higher Education and Research Areas. It concludes by arguing that Britain's higher education policy vis a vis Europe re-states a dilemma which these Islands have had to tackle for the best part of the past 250 Years. This dilemma is whether to lay priority on higher education as a global instrument or to endorse a more limited, less ambitious agenda of ,European' integration. [source]

    The introduced English wasp Vespula vulgaris (L.) (Hymenoptera: Vespidae) newly recorded invading native forests in Tasmania

    AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 3 2000
    Robert W Matthews
    Abstract The social wasp Vespula vulgaris (L.), an introduced species that has caused extreme ecological damage in New Zealand, is reported from southern Tasmanian forests for the first time. In mainland Australia, this wasp has been present in the Melbourne area since 1958 and our retrospective analysis places it in Hobart since 1995. In the present paper, we document V. vulgaris in natural areas in southern Tasmania, well away from human habitation. Malaise trap samples collected since 1997 from nine sites at the Warra Long-term Ecological Research area in southern Tasmania revealed the widespread presence of both V. vulgaris and V. germanica (F.), another introduced species of concern. Analysis of microsatellite DNA markers showed no evidence of hybridisation between the two species. The potential impact of this newest social insect threat to Australian native biota is discussed. [source]

    The Orbitrap: a new mass spectrometer

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2005
    Qizhi Hu
    Abstract Research areas such as proteomics and metabolomics are driving the demand for mass spectrometers that have high performance but modest power requirements, size, and cost. This paper describes such an instrument, the Orbitrap, based on a new type of mass analyzer invented by Makarov. The Orbitrap operates by radially trapping ions about a central spindle electrode. An outer barrel-like electrode is coaxial with the inner spindlelike electrode and mass/charge values are measured from the frequency of harmonic ion oscillations, along the axis of the electric field, undergone by the orbitally trapped ions. This axial frequency is independent of the energy and spatial spread of the ions. Ion frequencies are measured non-destructively by acquisition of time-domain image current transients, with subsequent fast Fourier transforms (FFTs) being used to obtain the mass spectra. In addition to describing the Orbitrap mass analyzer, this paper also describes a complete Orbitrap-based mass spectrometer, equipped with an electrospray ionization source (ESI). Ions are transferred from the ESI source through three stages of differential pumping using RF guide quadrupoles. The third quadrupole, pressurized to less than 10,3 Torr with collision gas, acts as an ion accumulator; ion/neutral collisions slow the ions and cause them to pool in an axial potential well at the end of the quadrupole. Ion bunches are injected from this pool into the Orbitrap analyzer for mass analysis. The ion injection process is described in a simplified way, including a description of electrodynamic squeezing, field compensation for the effects of the ion injection slit, and criteria for orbital stability. Features of the Orbitrap at its present stage of development include high mass resolution (up to 150 000), large space charge capacity, high mass accuracy (2,5 ppm), a mass/charge range of at least 6000, and dynamic range greater than 10.3 Applications based on electrospray ionization are described, including characterization of transition-metal complexes, oligosaccharides, peptides, and proteins. Use is also made of the high-resolution capabilities of the Orbitrap to confirm the presence of metaclusters of serine octamers in ESI mass spectra and to perform H/D exchange experiments on these ions in the storage quadrupole. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Neuroendocrine regulation of puberty in fish: Insights from the grey mullet (Mugil cephalus) model

    MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2008
    Josephine N. Nocillado
    Abstract We investigated the molecular regulation of pubertal development in the grey mullet, Mugil cephalus, a relatively late-maturing teleost fish. We have isolated and characterized the cDNAs of key reproductive genes along the brain,pituitary,gonadal (BPG) axis as well as the promoters of genes that modulate the axis at multiple levels. Together with relevant findings from other model species, we propose a conceptual model of the neuroendocrine regulation of puberty in the female grey mullet. Research areas that warrant further investigation are identified in the model. Mol. Reprod. Dev. 75: 355,361, 2008. © 2007 Wiley-Liss, Inc. [source]

    Output-only structural identification in time domain: Numerical and experimental studies

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2008
    M. J. Perry
    Abstract By identifying changes in stiffness parameters, structural damage can be detected and monitored. Although considerable progress has been made in this research area, many challenges remain in achieving robust structural identification based on incomplete and noisy measurement signals. The identification task is made even more difficult if measurement of input force is to be eliminated. To this end, an output-only structural identification strategy is proposed to identify unknown stiffness and damping parameters. A non-classical approach based on genetic algorithms (GAs) is adopted. The proposed strategy makes use of the recently developed GA-based method of search space reduction, which has shown to be able to accurately and reliably identify structural parameters from measured input and output signals. By modifying the numerical integration scheme, input can be computed as the parameter identification task is in progress, thereby eliminating the need to measure forces. Numerical and experimental results demonstrate the power of the strategy in accurate and efficient identification of structural parameters and damage using only incomplete acceleration measurements. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Pike predation on hatchery-reared Atlantic salmon smolts in a northern Baltic river

    ECOLOGY OF FRESHWATER FISH, Issue 1 2008
    J. Kekäläinen
    Abstract,,, The effect of pike Esox lucius predation on the mortality of newly stocked Atlantic salmon Salmo salar smolts was investigated in the Pyhäjoki River, Finland. The number of smolts eaten by pike was assessed by estimating the size of the pike population (mark,recapture experiment) and studying the stomach contents of pike. Before recapturing the pike, approximately 39,700 smolts were stocked upstream of the 2.5-km-long (89-ha) research area. The estimated size of the >40-cm pike population was 1507 (95% CL 1012,4731) individuals (17 pike and 29.8 kg·ha,1). Pike were estimated to eat 29% of the released smolts during 1 week. The diet of the pike in the research area consisted almost entirely of smolts, whereas in the reference area with no stocked smolts, the meal sizes were significantly smaller and the importance of smolts as prey was substantially lower. Pike <40 cm had not eaten any smolts, probably indicating a size refuge for the smolts, or alternatively fear of intraspecific interactions or cannibalism of pike. [source]

    Liquid chromatography on chip

    ELECTROPHORESIS, Issue 15 2010
    Karine Faure
    Abstract LC is one of the most powerful separation techniques as illustrated by its leading role in analytical sciences through both academic and industrial communities. Its implementation in microsystems appears to be crucial in the development of ,-Total Analysis System. If electrophoretic techniques have been widely used in miniaturized devices, LC has faced multiple challenges in the downsizing process. During the past 5 years, significant breakthroughs have been achieved in this research area, in both conception and use of LC on chip. This review emphasizes the development of novel stationary phases and their implementation in microchannels. Recent instrumental advances are also presented, highlighting the various driving forces (pressure, electrical field) that have been selected and their respective ranges of applications. [source]

    Entry Mode Choice of SMEs in Central and Eastern Europe

    ENTREPRENEURSHIP THEORY AND PRACTICE, Issue 1 2002
    George Nakos
    Scholars (e.g., Burgel & Murray, 2000; Jones, 1999; Zacharakis, 1997) have suggested that small and medium-sized enterprise (SME) international entry mode selection is an important new research area. In this study we attempt to determine if a model of large firm entry mode selection can be applied to SME entry mode choice. Using Dunning's eclectic framework, we examined SME entry into Central and Eastern Europe (CEE). We found that Dunning's eclectic framework did a good job of predicting SME entry mode selection in CEE markets. Managerial implications and suggestions for future research are discussed. [source]

    Depressive symptoms among mothers of children with epilepsy: A review of prevalence, associated factors, and impact on children

    EPILEPSIA, Issue 11 2009
    Mark A. Ferro
    Summary The impact of epilepsy is not limited to the child experiencing seizures, but affects all members of the family. As primary caregivers, mothers are particularly at risk for experiencing increased depressive symptoms and risk for clinical depression. The objective of this systematic review was to critically assess available evidence regarding the prevalence, associated factors, and impact of maternal depressive symptoms on child outcomes in epilepsy. Using a modified version of the Quality Index, studies were rigorously evaluated in terms of reporting, external validity, and internal validity. Limitations in the study designs and analytic techniques of previous research are discussed, and study methods to overcome these barriers are presented in order to advance this research area. Up to 50% of mothers of children with epilepsy are at risk for clinical depression. Correlates of maternal depressive symptoms include a number of modifiable risk factors such as role ambiguity, worry, and satisfaction with relationships. In addition, studies suggest that depressive symptoms in mothers have a negative impact on child outcomes in epilepsy including behavior problems and health-related quality of life. The overall mean score on the Quality Index was 9.7, indicating a midrange quality score, suggesting a need for more methodologically robust studies. [source]

    The Emergence and Institutionalisation of the European Higher Education and Research Area

    EUROPEAN JOURNAL OF EDUCATION, Issue 4 2008
    ERIC BEERKENS
    Since the European unification project started in the 1950s, rules, regulations and policies have been formulated by the European Union (and its predecessors) to facilitate the flow of products and people; those who benefited from the increasing transnational exchange urged European actors to remove remaining obstacles and further facilitate European trade and mobility. In the field of higher education and research, this transnational activity has led to the emergence of European rules, a strengthening of European institutions and the development of a European higher education and research community. In other words, it has led to the institutionalisation of the European higher education and research area (EHERA). The argument put forward in this article is that these three dimensions and the increase in transnational activity shape a dynamic process of which further integration of the EHERA is likely to be a result. [source]

    Variation in leaf functional trait values within and across individuals and species: an example from a Costa Rican dry forest

    FUNCTIONAL ECOLOGY, Issue 1 2010
    Catherine M. Hulshof
    Summary 1.,Patterns of species co-existence and species diversity in plant communities remain an important research area despite over a century of intensive scrutiny. To provide mechanistic insight into the rules governing plant species co-existence and diversity, plant community ecologists are increasingly quantifying functional trait values for the species found in a wide range of communities. 2.,Despite the promise of a quantitative functional trait approach to plant community ecology, we suggest that, along with examining trait variation across species, an assessment of trait variation within species should also be a key component of a trait-based approach to community ecology. Variability within and between individuals and populations is likely widespread due to plastic responses to highly localized abiotic and biotic interactions. 3.,In this study, we quantify leaf trait variation within and across ten co-existing tree species in a dry tropical forest in Costa Rica to ask: (i) whether the majority of trait variation is located between species, within species, within individuals or within the leaves themselves; (ii) whether trait values collected using standardized methods correlate with those collected using unstandardized methods; and (iii) to what extent can we differentiate plant species on the basis of their traits? 4.,We find that the majority of variation in traits was often explained by between species differences; however, between leaflet trait variation was very high for compound-leaved species. We also show that many species are difficult to reliably differentiate on the basis of functional traits even when sampling many individuals. 5.,We suggest an ideal sample size of at least 10, and ideally 20, individuals be used when calculating mean trait values for individual species for entire communities, though even at large sample sizes, it remains unclear if community level trait values will allow comparisons on a larger geographic scale or if species traits are generally similar across scales. It will thus be critical to account for intraspecific variation by comparing species mean trait values across space in multiple microclimatic environments within local communities and along environmental gradients. Further, quantifying trait variability due to plasticity and inheritance will provide a better understanding of the underlying patterns and drivers of trait variation as well as the application of functional traits in outlining mechanisms of species co-existence. [source]

    Ginkgo biloba extracts and cancer: a research area in its infancy

    FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2003
    Francis V. DeFeudis
    Abstract Recent studies conducted with various molecular, cellular and whole animal models have revealed that leaf extracts of Ginkgo biloba may have anticancer (chemopreventive) properties that are related to their antioxidant, anti-angiogenic and gene-regulatory actions. The antioxidant and associated anti-lipoperoxidative effects of Ginkgo extracts appear to involve both their flavonoid and terpenoid constituents. The anti-angiogenic activity of the extracts may involve their antioxidant activity and their ability to inhibit both inducible and endothelial forms of nitric oxide synthase. With regard to gene expression, a Ginkgo extract and one of its terpenoid constituents, ginkgolide B, inhibited the proliferation of a highly aggressive human breast cancer cell line and xenografts of this cell line in nude mice. cDNA microarray analyses have shown that exposure of human breast cancer cells to a Ginkgo extract altered the expression of genes that are involved in the regulation of cell proliferation, cell differentiation or apoptosis, and that exposure of human bladder cancer cells to a Ginkgo extract produced an adaptive transcriptional response that augments antioxidant status and inhibits DNA damage. In humans, Ginkgo extracts inhibit the formation of radiation-induced (chromosome-damaging) clastogenic factors and ultraviolet light-induced oxidative stress , effects that may also be associated with anticancer activity. Flavonoid and terpenoid constituents of Ginkgo extracts may act in a complementary manner to inhibit several carcinogenesis-related processes, and therefore the total extracts may be required for producing optimal effects. [source]

    Predicting the past distribution of species climatic niches

    GLOBAL ECOLOGY, Issue 5 2009
    David Nogués-Bravo
    ABSTRACT Predicting past distributions of species climatic niches, hindcasting, by using climate envelope models (CEMs) is emerging as an exciting research area. CEMs are used to examine veiled evolutionary questions about extinctions, locations of past refugia and migration pathways, or to propose hypotheses concerning the past population structure of species in phylogeographical studies. CEMs are sensitive to theoretical assumptions, to model classes and to projections in non-analogous climates, among other issues. Studies hindcasting the climatic niches of species often make reference to these limitations. However, to obtain strong scientific inferences, we must not only be aware of these potential limitations but we must also overcome them. Here, I review the literature on hindcasting CEMs. I discuss the theoretical assumptions behind niche modelling, i.e. the stability of climatic niches through time and the equilibrium of species with climate. I also summarize a set of ,recommended practices' to improve hindcasting. The studies reviewed: (1) rarely test the theoretical assumptions behind niche modelling such as the stability of species climatic niches through time and the equilibrium of species with climate; (2) they only use one model class (72% of the studies) and one palaeoclimatic reconstruction (62.5%) to calibrate their models; (3) they do not check for the occurrence of non-analogous climates (97%); and (4) they do not use independent data to validate the models (72%). Ignoring the theoretical assumptions behind niche modelling and using inadequate methods for hindcasting CEMs may well entail a cascade of errors and naïve ecological and evolutionary inferences. We should also push integrative research lines linking macroecology, physiology, population biology, palaeontology, evolutionary biology and CEMs for a better understanding of niche dynamics across space and time. [source]

    Nanostructured Biomaterials for Regeneration,

    ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008
    Guobao Wei
    Abstract Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/dysfunctional tissues or organs. Biomaterials (scaffolds) serve as temporary 3D substrates to guide neo tissue formation and organization. It is often beneficial for a scaffolding material to mimic the characteristics of extracellular matrix (ECM) at the nanometer scale and to induce certain natural developmental or/and wound healing processes for tissue regeneration applications. This article reviews the fabrication and modification technologies for nanofibrous, nanocomposite, and nanostructured drug-delivering scaffolds. ECM-mimicking nanostructured biomaterials have been shown to actively regulate cellular responses including attachment, proliferation, differentiation, and matrix deposition. Nanoscaled drug delivery systems can be successfully incorporated into a porous 3D scaffold to enhance the tissue regeneration capacity. In conclusion, nanostructured biomateials are a very exciting and rapidly expanding research area, and are providing new enabling technologies for regenerative medicine. [source]

    Streamwater quality as affected by wild fires in natural and manmade vegetation in Malaysian Borneo

    HYDROLOGICAL PROCESSES, Issue 5 2004
    Anders Malmer
    Abstract In 1998 a wild fire struck a paired catchment research area under long-term monitoring of hydrological and nutrient budgets. Streamwater quality as concentrations of dissolved and suspended particulate matter was monitored during 1·5,2·5 years after the fire in streams from seven different catchments. As the catchments, due to earlier experimental treatments, had different vegetations, varying effects related to different fire intensities were observed. The highest, mean stormflow, suspended sediment concentrations resulted from intensive fire in secondary vegetation that had experienced severe soil disturbance in previous treatments (crawler tractor timber extraction 10 years earlier). Stormflow concentrations were typically still about 400 mg l,1 in 1999 (10,21 months after the fire), which was about the maximum recorded concentration in streams during initial soil disturbance in 1988. Forest fire in natural forest resulted in less than half as high stormflow concentrations. For dissolved elements in streamwater there was a positive relation between fuel load (and fire intensity) and concentration and longevity of effects. Stream baseflow dissolved nutrient concentrations were high in the months following the fire. Mean baseflow K concentrations were 8,15 mg l,1 in streams draining catchments with intensive fire in secondary vegetation with large amounts of fuel. After controlled fire for forest plantation establishment in 1988 corresponding concentrations were 3,5 mg l,1, and after forest fire in natural forest in this study about 2 mg l,1. This study shows differences in response from controlled fire for land management, forest fire in natural forests and wild fires in manmade vegetations. These differences relate to resistance and resilience to fire for the involved ecosystems. There is reason to believe that wild fires and repeated wild fires during or after droughts, in successions caused by human influence, may lead to larger losses of ecosystem nutrient capital from sites compared with forest fires in natural forests. As fire in the humid tropics becomes more common, in an increasingly spatially fragmented landscape, it will be important to be aware of these differences. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Layer-by-Layer Hydrogen-Bonded Polymer Films: From Fundamentals to Applications

    ADVANCED MATERIALS, Issue 30 2009
    Eugenia Kharlampieva
    Abstract Recent years have seen increasing interest in the construction of nanoscopically layered materials involving aqueous-based sequential assembly of polymers on solid substrates. In the booming research area of layer-by-layer (LbL) assembly of oppositely charged polymers, self-assembly driven by hydrogen bond formation emerges as a powerful technique. Hydrogen-bonded (HB) LbL materials open new opportunities for LbL films, which are more difficult to produce than their electrostatically assembled counterparts. Specifically, the new properties associated with HB assembly include: 1) the ease of producing films responsive to environmental pH at mild pH values, 2) numerous possibilities for converting HB films into single- or two-component ultrathin hydrogel materials, and 3) the inclusion of polymers with low glass transition temperatures (e.g., poly(ethylene oxide)) within ultrathin films. These properties can lead to new applications for HB LbL films, such as pH- and/or temperature-responsive drug delivery systems, materials with tunable mechanical properties, release films dissolvable under physiological conditions, and proton-exchange membranes for fuel cells. In this report, we discuss the recent developments in the synthesis of LbL materials based on HB assembly, the study of their structure,property relationships, and the prospective applications of HB LbL constructs in biotechnology and biomedicine. [source]

    Role of the Toll/interleukin-1 receptor signaling pathway in host resistance and pathogenesis during infection with protozoan parasites

    IMMUNOLOGICAL REVIEWS, Issue 1 2004
    Ricardo T. Gazzinelli
    Summary:, Different studies have illustrated the activation of the innate immune system during infection with protozoan parasites. Experiments performed in vivo also support the notion that innate immunity has a crucial role in resistance as well as pathogenesis observed during protozoan infections such as malaria, leishmaniasis, toxoplasmosis, and trypanosomiasis. While major advances have been made in the assignment of bacterial molecules as Toll-like receptors (TLRs) agonists as well as defining the role of the Toll/interleukin-1 receptor (TIR) signaling pathway in host resistance to bacterial infection, this research area is now emerging in the field of protozoan parasites. In this review, we discuss the recent studies describing parasite molecules as TLR agonists and those studies indicating the essential role of the TIR-domain bearing molecule named myeloid differentiation factor 88 in host resistance to infection with protozoan parasites. Together, these studies support the hypothesis that the TIR signaling pathway is involved in the initial recognition of protozoan parasites by the immune system of the vertebrate host, early resistance to infection, development of acquired immunity, as well as pathology observed during acute infection with this class of pathogens. [source]

    On the design of bandwidth efficient signalling for indoor wireless optical channels

    INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2005
    Steve HranilovicArticle first published online: 15 MAR 200
    Abstract It is well known that indoor wireless optical channels are limited not only in transmitted optical power, but also in signalling bandwidth. This bandwidth constraint arises due to multipath dispersion in indoor settings as well as due to response time limitations of optoelectronic components. This paper presents an overview of theoretical and practical issues in the design of signalling for bandwidth constrained intensity modulated, direct detection wireless optical channels. A brief overview of the salient qualities of the wireless optical channel are presented to highlight the amplitude constraints which arise. A survey of modulation design is then presented which includes the review of a general technique to represent optical intensity modulation in a signal space and to construct optical intensity lattice codes. Results on the channel capacity of indoor wireless optical channels are surveyed and particular emphasis is placed on recently derived asymptotically exact bounds. The use of multiple emitters and receivers in wireless optical channels is also presented and particular emphasis is placed on techniques which exploit spatial dimensions to improve spectral performance. The paper concludes with some remarks regarding the status of the research area and suggestions for future work. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A review on microwave baking of foods

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2001
    Gülüm Sumnu
    Summary Microwaves interact with polar molecules and charged particles of food to generate heat. There are differences between the heating mechanisms of microwave and conventional heating. The use of microwave heating has the advantage of saving energy and time, improving both nutritional quality and acceptability of some foods by consumers. Microwave ovens are successfully used both in homes and in the food service industry. However, there are still problems in perfecting microwave baking, therefore it is a popular research area. The main problems found to occur in microwave-baked food products are low volume, tough or firm texture, lack of browning and flavour development. Recent studies aim to improve the quality of microwave-baked products. This article reviews the basic principles of microwave baking, problems commonly occurring in microwave-baked products and finally studies published concerning microwave-baked products. [source]

    Fusion of digital television, broadband Internet and mobile communications,Part I: Enabling technologies

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2007
    F. L. C. Ong
    Abstract The introduction of digital video broadcasting (DVB) satellite systems has become an important tool for future mobile communication and is currently a focus in several research areas such as the integration of DVB satellite systems with different wireless technologies. This tutorial consists of two parts, Enabling technologies and Future service scenarios, which aims to provide an introduction to the current state-of-the-art of DVB standards over satellite and its fusion with mobile and Internet technologies. This paper, Enabling technologies, focuses on providing an overview of the different technologies and issues that facilitates better understanding of the current and future operational scenarios, whereas the second paper, Future service scenarios will emphasize future research directions in this research area. In the first part, the paper will initially be focused on the introduction of different DVB satellite systems, i.e. DVB- via satellite (DVB-S), DVB return channel by satellite (DVB-RCS) and second-generation DVB system for broadband satellite services (DVB-S2). This is then followed by a description of the different Internet Protocol (IP) technologies used to support macro- and micro-mobility and the migration strategies from IP version 4 (IPv4) to IP version 6 (IPv6). Finally, the different security mechanisms for the DVB system and end-to-end satellite network are addressed. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Transition Metal-Catalysed, Direct and Site-Selective N1-, C2- or C3-Arylation of the Indole Nucleus: 20 Years of Improvements

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009
    Lionel Joucla
    Abstract The direct and site-selective transition metal-catalysed N1-, C2- or C3-arylations of indoles have been the subject of almost continuous improvements since their discovery in early 1980s. This research area is mainly motivated by the biological relevance of this class of compounds in order to propose catalytic alternative syntheses to the well known methodologies involving the formation of the indole ring like the Fischer, Larock, Cacchi, Lautens etc. reactions. Since the late 1990s it has experienced new impulses related to the intensive development of catalytic CH activation. Today, through the intensive studies of Buchwald and Hartwig, the N1-arylation of indoles has reached sufficient maturity for both academic and industrial applications. On the other hand, the selective C2- or C3-arylation of indoles, initiated by Ohta in the middle 1980s, has become a hot research area these last years following the reports of Sames. Surprisingly, only few reports concern the use of heterogeneous catalysts; however, the application of these emerging methodologies seems to be related to the discovery of industrially attractive systems. [source]

    A review of current developments in process and quality control for injection molding

    ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2005
    Zhongbao Chen
    Abstract Injection molding is one of the most versatile and important manufacturing processes capable of mass-producing complicated plastic parts in net shape with excellent dimensional tolerance. Injection molding process and quality control has been an active research area for many years, as part quality and yield requirements become more stringent. This paper reviews the state-of-the-art research and development in injection molding control. It organizes prior studies into four categories, namely, process setup, machine control, process control, and quality control, and presents the distinction and connection of these different levels of control. This paper further reviews and compares the typical variables, models, and control methods that have been proposed and employed for those control tasks. Strictly speaking, real online quality control without human intervention has yet to be realized, primarily due to the lack of transducers for online, real time quality response measurement, and a robust model that correlates the control variables with quantitative quality measurements. Based on the research progress to date, this paper suggests that the different levels of control tasks have to be integrated into a multilevel quality control system, and that the quality sensor and the process and quality model are the two most important areas for further advancement in injection molding control. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24: 165,182, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20046 [source]