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Specific Topics (specific + topics)
Selected AbstractsDrought and salinity: A comparison of their effects on mineral nutrition of plantsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2005Yuncai Hu Abstract The increasing frequency of dry periods in many regions of the world and the problems associated with salinity in irrigated areas frequently result in the consecutive occurrence of drought and salinity on cultivated land. Currently, 50% of all irrigation schemes are affected by salinity. Nutrient disturbances under both drought and salinity reduce plant growth by affecting the availability, transport, and partitioning of nutrients. However, drought and salinity can differentially affect the mineral nutrition of plants. Salinity may cause nutrient deficiencies or imbalances, due to the competition of Na+ and Cl, with nutrients such as K+, Ca2+, and NO. Drought, on the other hand, can affect nutrient uptake and impair acropetal translocation of some nutrients. Despite contradictory reports on the effects of nutrient supply on plant growth under saline or drought conditions, it is generally accepted that an increased nutrient supply will not improve plant growth when the nutrient is already present in sufficient amounts in the soil and when the drought or salt stress is severe. A better understanding of the role of mineral nutrients in plant resistance to drought and salinity will contribute to an improved fertilizer management in arid and semi-arid areas and in regions suffering from temporary drought. This paper reviews the current state of knowledge on plant nutrition under drought and salinity conditions. Specific topics include: (1) the effects of drought and salt stress on nutrient availability, uptake, transport, and accumulation in plants, (2) the interactions between nutrient supply and drought- or salt-stress response, and (3) means to increase nutrient availability under drought and salinity by breeding and molecular approaches. Trockenstress und Salzstress , Vergleich der Auswirkungen auf die mineralische Ernährung von Pflanzen Eine Zunahme von Trockenperioden in vielen Ländern der Welt und assoziierte Probleme der Versalzung in bewässerten Gebieten führen häufig zu gleichzeitigem Auftreten von Trockenheit und Salinität. Gegenwärtig sind weltweit ungefähr 50 % aller Bewässerungsflächen durch Salinität beeinträchtigt. Nährstoffstörungen bei Trocken- und Salzstress beeinträchtigen die Verfügbarkeit, den Transport und die Verteilung von Nährelementen in der Pflanze und reduzieren somit das Pflanzenwachstum. Trocken- und Salzstress können sich jedoch unterschiedlich auf die Nährstoffversorgung der Pflanzen auswirken. Salinität kann aufgrund der Konkurrenz zwischen Na+ bzw. Cl, und Nährelementen wie K+, Ca2+ und NO Nährstoffmängel oder -ungleichgewichte in den Pflanzen verursachen. Trockenstress kann sowohl die Nährstoffaufnahme als auch den akropetalen Transport einiger Elemente beeinträchtigen. Trotz kontroverser Schlussfolgerungen in der Literatur hinsichtlich der Wechselbeziehungen von Nährstoffangebot und Trocken- bzw. Salzstress auf das Pflanzenwachstum ist allgemein akzeptiert, dass Nährstoffzufuhr das Pflanzenwachstum nicht verbessert, wenn ausreichend Nährstoffe im Boden verfügbar sind oder bei stark ausgeprägter Trockenheit oder Salinität. Ein besseres Verständnis der Rolle von Mineralstoffen in der Toleranz von Pflanzen gegenüber Trocken- oder Salzstress dürfte gerade in ariden und semi-ariden Gebieten sowie in Regionen, die unter periodischer Trockenheit leiden, zu verbesserten Düngestrategien beitragen. In der vorliegenden Arbeit wird der gegenwärtige Kenntnisstand der mineralischen Ernährung bei Trockenheit und Salinität diskutiert. Schwerpunkte der Betrachtungen sind (1) die Auswirkungen von Trockenheit und Salzstress auf die Verfügbarkeit, die Aufnahme, den Transport und die Anreicherung von Nährelementen in der Pflanze, (2) Wechselbeziehungen zwischen dem Nährstoffangebot und Trockenheit oder Salinität sowie (3) Maßnahmen zur Verbesserung der Nährstoffverfügbarkeit bei Trockenheit und Salzstress mittels züchterischer und molekularbiologischer Ansätze. [source] Crafting Museum Experiences in Light of Research on Learning: Implications of the National Research Council's Report on Informal Science EducationCURATOR THE MUSEUM JOURNAL, Issue 2 2010Andrew Shouse The report is a synthesis of some 2,000 studies and evaluations of learning in non-school settings such as museums. Here we focus on three specific topics discussed in the full report, which we see as particularly important for museum professionals. These are: a framework for developing and studying science learning experiences; cultural diversity as an integral resource for learning; and assessment of learning. Many museums include "learning" among their goals and many researchers concern themselves with how museums and other settings can be organized to support learning. Yet this wealth of research is rarely brought into focus and offered as guidance to the museum community. [source] A metapopulation perspective for salmon and other anadromous fishFISH AND FISHERIES, Issue 4 2007Nicolas Schtickzelle Abstract Salmonids are an important component of biodiversity, culture and economy in several regions, particularly the North Pacific Rim. Given this importance, they have been intensively studied for about a century, and the pioneering scientists recognized the critical link between population structure and conservation. Spatial structure is indeed of prime importance for salmon conservation and management. At first glance, the essence of the metapopulation concept, i.e. a population of populations, widely used on other organisms like butterflies, seems to be particularly relevant to salmon, and more generally to anadromous fish. Nevertheless, the concept is rarely used, and barely tested. Here, we present a metapopulation perspective for anadromous fish, assessing in terms of processes rather than of patterns the set of necessary conditions for metapopulation dynamics to exist. Salmon, and particularly sockeye salmon in Alaska, are used as an illustrative case study. A review of life history traits indicates that the three basic conditions are likely to be fulfilled by anadromous salmon: (i) the spawning habitat is discrete and populations are spatially separated by unsuitable habitat; (ii) some asynchrony is present in the dynamics of more or less distant populations and (iii) dispersal links populations because some salmon stray from their natal population. The implications of some peculiarities of salmon life history traits, unusual in classical metapopulations, are also discussed. Deeper understanding of the population structure of anadromous fish will be advanced by future studies on specific topics: (i) criteria must be defined for the delineation of suitable habitats that are based on features of the biotope and not on the presence of fish; (ii) the collection of long-term data and the development of improved methods to determine age structure are essential for correctly estimating levels of asynchrony between populations and (iii) several key aspects of dispersal are still poorly understood and need to be examined in detail: the spatial and temporal scales of dispersal movements, the origin and destination populations instead of simple straying rates, and the relative reproductive success of immigrants and residents. [source] Periodontal diseases and health: Consensus Report of the Sixth European Workshop on PeriodontologyJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2008Denis Kinane Abstract Introduction: The remit of this group was to update the knowledge base on periodontal diseases and health. Material and Methods: The literature was systematically searched and critically reviewed in five specific topics. Results: Prevalence of periodontitis: The data suggest a trend towards a lower prevalence of periodontitis in recent years. Adverse pregnancy outcome: The findings indicate a likely association between periodontal disease and an increased risk of adverse pregnancy outcomes. There is no evidence that treating periodontal disease decreases the rate of adverse pregnancy outcomes. Prevalence and distribution of periodontal pathogens: Genetic analysis of bacteria has demonstrated an unanticipated diversity within species. Carriage rates and particular subsets of these species vary between ethnic groups. Few of these differences can be related to differences in disease prevalence. Diabetes mellitus: Evidence on the association supports the concept of increased severity but not extent of periodontitis in subjects with poorly controlled diabetes. It is inconclusive that periodontal treatment results in improved metabolic control. Cardiovascular diseases: Evidence suggests that having periodontitis contributes to the total infectious and inflammation burden and may contribute to cardiovascular events and stroke in susceptible subjects. The impact of periodontal therapy must be further investigated. [source] IAEA activities in support of production and utilization of radioisotope labelled compounds,JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5-6 2007Natesan Ramamoorthy Abstract The development of a large variety of radioisotope labelled compounds as well as the ability to design and prepare specific products forms the basis for several important applications in medicine, industry and research. As a part of the IAEA's role in fostering the peaceful uses of nuclear science and technology, the IAEA's Division of Physical and Chemical Sciences has focused attention on the important classes of compounds such as, fluorine-18 products; technetium-99m labelled complexes; products for radionuclide therapy of yttrium-90, samarium-153, lutetium-177 and rhenium-186/188; industrial radiotracers based on bromine-82 labelled compounds, tritiated water and carbon-14 labelled thiocyanate. A number of coordinated research projects (CRP) and technical cooperation projects have been implemented for this purpose. Thematic technical and consultancy meetings have been held to review the status and prepare technical documents on specific topics of interest for developing Member States (MS). These measures have contributed to several developing MS acquiring/enhancing expertise in building local facilities and capability in the production and utilization of radioisotope labelled compounds. Copyright © 2007 John Wiley & Sons, Ltd. [source] Quantifiers and Discourse ProcessingLINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 6 2009Kevin B. Paterson Quantifiers are ubiquitous in natural language and, in addition to providing information about quantity, they serve important discourse functions. We outline several theoretical accounts of the functions that quantifiers perform in a discourse and the factors governing their interpretation, focusing on two specific topics that have received substantial attention from researchers working in linguistics and psychology. The first topic concerns the interpretation of pronominal anaphora in different quantification contexts, and we review evidence showing that the focusing effects of positive and negative quantifiers license different patterns of pronominal reference. The second topic concerns the interpretation of quantifiers that function as anaphors in a discourse, and we consider recent experimental evidence in relation to two current and highly influential theories of semantic interpretation. [source] Placing Indigenous Rights to Self-Determination in an Ecological ContextRATIO JURIS, Issue 2 2002Barbara Ann Hocking In this paper the author focuses on Australian land management and in particular on the environmental management issues that could have been prompted by the High Court recognition in 1996 (in Wik Peoples v. The State of Queensland) that native title to land and pastoral leaseholdings can co-exist. Drawing on themes of self-determination and co-existence, the paper looks at more specific topics such as aboriginal title to land,what has been called land rights or native title in Australia,and some implications of that for land, sea and resource management. Central to this analysis are competing theories of Aboriginal land management and links between Aboriginal traditional knowledge and conservation of species. These are illustrated through the marine mammal, the dugong. The Australian debates lead to the Canadian debates and then to Scandinavia and the role of the Sami people in protection and management of the Arctic region. Issues of indigenous self determination inevitably provide an overall theme to these discussions. As a matter of global concern, the paper asks, but does not decide, whether indigenous peoples may manage fragile eco-systems more effectively than outsiders. It maintains that what is important in this context is a broader question. This concerns how culturally inclusive land and resource management can emerge from recognition of indigenous land and human rights and how comparative developments can provide crucial cross-jurisdictional information for future developments and opportunities in the interests of environmental conservation. [source] Koopman-von Neumann formulation of classical Yang-Mills theories: IANNALEN DER PHYSIK, Issue 3 2006P. Carta Abstract In this paper we present the Koopman-von Neumann (KvN) formulation of classical non-Abelian gauge field theories. In particular we shall explore the functional (or classical path integral) counterpart of the KvN method. In the quantum path integral quantization of Yang-Mills theories concepts like gauge-fixing and Faddeev-Popov determinant appear in a quite natural way. We will prove that these same objects are needed also in this classical path integral formulation for Yang-Mills theories. We shall also explore the classical path integral counterpart of the BFV formalism and build all the associated universal and gauge charges. These last are quite different from the analog quantum ones and we shall show the relation between the two. This paper lays the foundation of this formalism which, due to the many auxiliary fields present, is rather heavy. Applications to specific topics outlined in the paper will appear in later publications. [source] Introductory course based on a single problem: Learning nucleic acid biochemistry from AIDS researchBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 6 2004Neena Grover Abstract In departure from the standard approach of using several problems to cover specific topics in a class, I use a single problem to cover the contents of the entire semester-equivalent biochemistry classes. I have developed a problem-based service-learning (PBSL) problem on HIV/AIDS to cover nucleic acid concepts that are typically taught in the second semester of a biochemistry class. Use of research articles on a specific topic allows developing problems such as one discussed here. The implementation of this problem is similar to teaching literature-based courses but is tailored to undergraduate work. Details of designing and setting up this problem, along with the pros and cons of this approach, are discussed here. [source] Publication bias in ecology and evolution: an empirical assessment using the ,trim and fill' methodBIOLOGICAL REVIEWS, Issue 2 2002MICHAEL D. JENNIONS ABSTRACT Recent reviews of specific topics, such as the relationship between male attractiveness to females and fluctuating asymmetry or attractiveness and the expression of secondary sexual characters, suggest that publication bias might be a problem in ecology and evolution. In these cases, there is a significant negative correlation between the sample size of published studies and the magnitude or strength of the research findings (formally the ,effect size'). If all studies that are conducted are equally likely to be published, irrespective of their findings, there should not be a directional relationship between effect size and sample size; only a decrease in the variance in effect size as sample size increases due to a reduction in sampling error. One interpretation of these reports of negative correlations is that studies with small sample sizes and weaker findings (smaller effect sizes) are less likely to be published. If the biological literature is systematically biased this could undermine the attempts of reviewers to summarise actual biology relationships by inflating estimates of average effect sizes. But how common is this problem? And does it really effect the general conclusions of literature reviews? Here, we examine data sets of effect sizes extracted from 40 peer-reviewed, published meta-analyses. We estimate how many studies are missing using the newly developed ,trim and fill' method. This method uses asymmetry in plots of effect size against sample size (,funnel plots') to detect ,missing' studies. For random-effect models of meta-analysis 38% (15/40) of data sets had a significant number of ,missing' studies. After correcting for potential publication bias, 21% (8/38) of weighted mean effects were no longer significantly greater than zero, and 15% (5/34) were no longer statistically robust when we used random-effects models in a weighted meta-analysis. The mean correlation between sample size and the magnitude of standardised effect size was also significantly negative (rs=-0.20, P < 0-0001). Individual correlations were significantly negative (P < 0.10) in 35% (14/40) of cases. Publication bias may therefore effect the main conclusions of at least 15,21% of meta-analyses. We suggest that future literature reviews assess the robustness of their main conclusions by correcting for potential publication bias using the ,trim and fill' method. [source] Biomechanics/risk management (Working Group 2)CLINICAL ORAL IMPLANTS RESEARCH, Issue 2009Mariano Sanz Abstract Introduction: The remit of this workgroup was to update the existing knowledge base in biomechanical factors, navigation systems and medications that may affect the outcome of implant therapy. Material and methods: The literature was systematically searched and critically reviewed. Five manuscripts were produced in five specific topics identified as areas where innovative approaches have been developed in biomechanical factors, navigation systems and medications that may affect the outcome of implant therapy. Results: The results and conclusions of the review process are presented in the following papers, together with the group consensus statements, clinical implications and directions for future research: , To what extent do cantilevers affect survival and complications of implant supported restorations in partially dentate patients? , To what extent does the crown,implant ratio affect survival and complications of implant supported restorations? , A systematic review on the accuracy and the clinical outcome of computer-guided template based implant dentistry. , What is the impact of systemic bisphosphonates on patients undergoing oral implant therapy? , What is the impact of anticoagulants on patients undergoing oral implant therapy? [source] | ||||||||||||||||