Different Components (different + component)

Distribution by Scientific Domains
Distribution within Life Sciences

Selected Abstracts

Hg2+ Reacts with Different Components of the NADPH: Protochlorophyllide Oxidoreductase Macrodomains

PLANT BIOLOGY, Issue 3 2004
K. Solymosi
Abstract: The molecular background of Hg2+ -induced inhibition of protochlorophyllide (Pchlide) photoreduction was investigated in homogenates of dark-grown wheat leaves. Our earlier work showed that 15 min incubation with 10 -2 M Hg2+ completely inhibits the activity of NADPH: Pchlide oxidoreductase. Detailed analysis of spectra recorded at 10 K indicated the appearance of emission bands at 638 and 650 nm, which are characteristic for NADP+ -Pchlide complexes. Fluorescence emission spectra recorded with different excitation wavelengths, fluorescence lifetime measurements and the analysis of acetone extractions revealed that Hg2+ can also react directly with Pchlide, resulting in protopheophorbide formation. At 10 -3 M Hg2+, the phototransformation was complete but the blue shift of the chlorophyllide emission band speeded up remarkably. This indicates oxidation of the NADPH molecules that have a structural role in keeping together the etioplast inner membrane components. We suggest a complex model for the Hg2+ effect: depending on concentration it can react with any components of the NADPH: Pchlide oxidoreductase macrodomains. [source]

The Impact of Forecast Errors on Early Order Commitment in a Supply Chain,

Xiande Zhao
ABSTRACT Supply chain partnership involves mutual commitments among participating firms. One example is early order commitment, wherein a retailer commits to purchase a fixed-order quantity and delivery time from a supplier before the real need takes place. This paper explores the value of practicing early order commitment in the supply chain. We investigate the complex interactions between early order commitment and forecast errors by simulating a supply chain with one capacitated supplier and multiple retailers under demand uncertainty. We found that practicing early order commitment can generate significant savings in the supply chain, but the benefits are only valid within a range of order commitment periods. Different components of forecast errors have different cost implications to the supplier and the retailers. The presence of trend in the demand increases the total supply chain cost, but makes early order commitment more appealing. The more retailers sharing the same supplier, the more valuable for the supply chain to practice early order commitment. Except in cases where little capacity cushion is available, our findings are relatively consistent in the environments where cost structure, number of retailers, capacity utilization, and capacity policy are varied. [source]

Inactivation of root canal medicaments by dentine, hydroxylapatite and bovine serum albumin

I. Portenier
Abstract Aim This study examined and compared the inhibition of the antibacterial effect of saturated calcium hydroxide solution, chlorhexidine acetate and iodine potassium iodide by dentine, hydroxylapatite and bovine serum albumin. MethodologyEnterococcus faecalis strain A197A prepared to a suspension of 3 × 108 cells per ml in 0.5% peptone water was used. Fifty µL of saturated calcium hydroxide solution, 0.05% chlorhexidine acetate or 0.2/0.4% iodine potassium iodide were incubated at 37 °C with 28 mg dentine powder (DP), hydroxylapatite (HA) or bovine serum albumin (BSA) in 50 µL water for 1 h before adding 50 µL of the bacterial suspension. Samples for bacterial culturing were taken from the suspension 1 and 24 h after adding the bacteria. In further experiments, the amount of dentine was stepwise reduced from 28 mg 150 µL,1 to 2.8 mg 150 µL,1. Results Calcium hydroxide was totally inactivated by the presence of 28 mg of DP, HA or BSA. Chlorhexidine (0.05%) was strongly inhibited by BSA and slowed down by dentine. However, HA had little or no inhibitory effect on chlorhexidine. The antibacterial effect of 0.2/0.4% iodine potassium iodide on E. faecalis was totally inhibited by dentine (28 mg), but was practically unaffected by HA or BSA. A stepwise reduction of dentine from 28 mg 150 µL,1 to 2.8 mg 150 µL,1 was followed by a similar reduction of the inhibition of the antibacterial activity of chlorhexidine. Iodine potassium iodide was not inhibited at all with dentine amounts less than 28 mg. However, the effect of saturated calcium hydroxide solution was totally eliminated by dentine, in all four concentrations. Conclusion Inhibition by dentine of the antibacterial activity of calcium hydroxide, chlorhexidine and iodine potassium iodide occurs by different mechanisms. Different components of dentine may be responsible for the inhibition of these three medicaments. Calcium hydroxide was particularly sensitive to inhibition by both inorganic and organic compounds. [source]

1332: Fluorescein angiography: first step for macular degeneration diagnosis

Purpose To recall that fluorescein angiography (FA) is not only the basis of our knowledge but also mandatory to improve our understanding. Methods Macular disciform lesions have been described and drawed since about 150 years. It is only in 1977 with the advent of fluorescein that the connection with choroidal new vessels (CNV) was performed. The identification of drusen as precursors of CNV was the following stage. With time a number of precursors and clinical forms of macular degeneration were described. Results Currently, the precursors (Age-Related Maculopathy) are distinguished from the neovasdcular or atrophic complications (Age-Related Macular Degeneration). The precursors presenting an early hyperfuorescence can be either hard drusen or RPE atrophy distinguished from each other on the late phase of FA. The late hyperfluorescence of soft drusen particularly when confluent requires a careful analysis of the complete FA sequence to ensure the diagnosis. The neovascular stage presents mainly as sub epithelial occult lesions of which the other types develop that display different angiographic behaviours. Specific aspects have been described gradually based on their FA features. The atrophic stage of the disease seems to behave in a stereotyped way but sub goups are presently identified. Conclusion The fluorescein features of the different component of AMD remain the reference for all other more recent imaging technics and helps to understand and differentiate the various aspects of the disease. [source]

Characterization of New PPAR, Agonists: Analysis of Telmisartan's Structural Components

CHEMMEDCHEM, Issue 3 2009
Matthias Goebel
Abstract Telmisartan was originally designed as an AT1 antagonist but was later also characterized as a selective PPAR, modulator. This study focused on the identification of the essential structural motifs of telmisartan for PPAR, activation activity, elucidating the individual SAR of each different component (shown). In addition to a proven efficacy in lowering blood pressure, the AT1 receptor blocker telmisartan has recently been shown to exert pleiotropic effects as a partial agonist of the nuclear peroxisome proliferator-activated receptor gamma (PPAR,). Based on these findings and an excellent side-effect profile, telmisartan may serve as a lead structure for the development of new PPAR, ligands. Therefore, we analyzed the structural components of telmisartan to identify those necessary for PPAR, activation. Synthesized compounds were tested in a differentiation assay using 3T3-L1 preadipocytes and a luciferase assay with COS-7 cells transiently transfected with pGal4-hPPAR,DEF, pGal5-TK-pGL3 and pRL-CMV. The data obtained in this structure,activity relationship (SAR) study provide the basis for the development of new PPAR, ligands, which could lead to active compounds with a distinct, beneficial pharmacological profile compared with the existing full agonists. The basic 1-(biphenyl-4-ylmethyl)-1H -benzimidazole scaffold of telmisartan was identified as an essential moiety with either a carboxylic acid or tetrazole group at the C-2 position of the biphenyl. For maximum potency and activity, the alkyl chain in position 2 requires a minimum length of at least two C atoms (ethyl group), while the methyl group at position 4 of the benzimidazole core seems to contribute to partial activity. An additional benzimidazole at position 6 appears to be a further determinant of potency. Similar conclusions can be drawn for the methyl group in position 1. [source]

Generation of a virtual reality-based automotive driving training system for CAD education

Janus Liang
Abstract Designing and constructing a virtual reality-based system is useful for educating students about scenario planning, geometric modeling and computer graphics. In particular, students are exposed to the practical issues surrounding topics such as geometric modeling, rendering, collision detection, model animation and graphical design. Meanwhile, building an application system provides students exposure to the real-world side of software engineering that they are typically shielded from in the traditional computer class. This study is a description of the experiences with instructing "Computer-aided Industrial design" and "OOP," two introductory classes that focus on designing and generating the VR based system possible in the course of a semester and then "VR System," an advanced course in the next semester. This study emphasizes the continuing evolution in the training and educational needs of students of CAD-systems. This study breaks down an automobile driving training system into different components that are suitable for individual student projects and discusses the use of modern graphical design tools such as 3ds MAX for artistic design in this system. The conclusion of this study proposes a rough schedule for developing a VR based system during the course of a semester and an overview is given of a concept of a virtual reality-based design and constructing system that is being developed. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 148,166, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20178 [source]

Simulation of compression refrigeration systems

Jaime Sieres
Abstract This study presents the main features of a software for simulating vapor compression refrigeration systems that are self designed by the user. A library of 10 different components is available: compressor, expansion device, condenser, evaporator, heat exchanger, flash tank, direct intercooler flash tank, indirect intercooler flash tank, mixer, and splitter. With these components and a library of different refrigerants many different refrigeration systems may be solved. By a user-friendly interface, the user can draw the system scheme by adding different components, connecting them and entering different input data. Results are presented in the form of tables and the cycle diagram of the system is drawn on the logP,h and T,s thermodynamic charts. © 2006 Wiley Periodicals, Inc. Comput Appl Eng Educ 14: 188,197, 2006; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20075 [source]

Hardware-Based Volumetric Knit-Wear

Katja Daubert
We present a hardware-based, volumetric approach for rendering knit wear at very interactive rates. A single stitch is represented by a volumetric texture with each voxel storing the main direction of the strands of yarn inside it. We render the knit wear in layers using an approximation of the Banks model. Our hardware implementation allows specular and diffuse material properties to change from one voxel to the next. This enables us to represent yarn made up of different components or render garments with complicated color patterns. Furthermore, our approach can handle self-shadowing of the stitches, and can easily be adapted to also include view-independent scattering. The resulting shader lends itself naturally to mip-mapping, and requires no reordering of the base geometry, making it versatile and easy to use. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Hardware Applications Volumetric Textures [source]

The Scalasca performance toolset architecture

Markus Geimer
Abstract Scalasca is a performance toolset that has been specifically designed to analyze parallel application execution behavior on large-scale systems with many thousands of processors. It offers an incremental performance-analysis procedure that integrates runtime summaries with in-depth studies of concurrent behavior via event tracing, adopting a strategy of successively refined measurement configurations. Distinctive features are its ability to identify wait states in applications with very large numbers of processes and to combine these with efficiently summarized local measurements. In this article, we review the current toolset architecture, emphasizing its scalable design and the role of the different components in transforming raw measurement data into knowledge of application execution behavior. The scalability and effectiveness of Scalasca are then surveyed from experience measuring and analyzing real-world applications on a range of computer systems. Copyright © 2010 John Wiley & Sons, Ltd. [source]

The Grid Resource Broker workflow engine

M. Cafaro
Abstract Increasingly, complex scientific applications are structured in terms of workflows. These applications are usually computationally and/or data intensive and thus are well suited for execution in grid environments. Distributed, geographically spread computing and storage resources are made available to scientists belonging to virtual organizations sharing resources across multiple administrative domains through established service-level agreements. Grids provide an unprecedented opportunity for distributed workflow execution; indeed, many applications are well beyond the capabilities of a single computer, and partitioning the overall computation on different components whose execution may benefit from runs on different architectures could provide better performances. In this paper we describe the design and implementation of the Grid Resource Broker (GRB) workflow engine. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A workflow portal supporting multi-language interoperation and optimization

Lican Huang
Abstract In this paper we present a workflow portal for Grid applications, which supports different workflow languages and workflow optimization. We present an XSLT converter that converts from one workflow language to another and enables the interoperation between different workflow languages. We discuss strategies for choosing the optimal service from several semantically equivalent Web services in a Grid application. The dynamic selection of Web services involves discovering a set of semantically equivalent services by filtering the available services based on metadata, and selecting an optimal service based on real-time data and/or historical data recorded during prior executions. Finally, we describe the framework and implementation of the workflow portal which aggregates different components of the project using Java portlets. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A Quantitative Conservation Approach for the Endangered Butterfly Maculinea alcon

MICHIEL F. WallisDeVries
The quality and size of habitat patches and their isolation from other patches are the main parameters for an assessment of population persistence, but translating persistence probabilities into practical measures is still a weak link in conservation management. I provide a quantitative conservation approach for the endangered myrmecophilous butterfly Maculinea alcon in the Netherlands. All 127 colonies known on heathland since 1990 were investigated for patch quality, size, and isolation. I assessed habitat quality in three 10 × 10 m plots for most colonies. Site occupancy in 1998,1999 was only 56%. Occupancy was best explained by a logistic regression including patch area, host ant presence, host plant abundance, overall heathland area, and connectivity between sites ( R2= 0.410, p < 0.0001); it correctly classified the occupied or vacant status for 82% of the sites. Connectivity contributed only 3.6% to the total explained variation of site occupancy, indicating that habitat characteristics were more important than isolation in determining population persistence at the examined scale level (>500 m). Grazing and sod cutting had a beneficial impact, but in combination these practices proved detrimental. Hydrological measures to prevent drainage were also associated with lowered occupancy. I used the different components in the logistic regression to formulate objective management recommendations. These consisted of sod cutting, reduction of management intensity, enlargement of habitat, or combinations of these recommendations. The results highlight the importance of careful management when site quality is determined by multiple factors. The quantitative conservation approach followed here can be fruitfully extended to other endangered species, provided enough is known about their ecological requirements and how management actions affect them. Resumen:,La preservación de fragmentos individuales es extremadamente importante para especies en peligro con capacidad de dispersión limitada. La calidad y tamaño de los fragmentos de hábitat y su aislamiento de otros fragmentos son los parámetros principales para la evaluación de la persistencia de la población, pero la traducción de probabilidades de persistencia en medidas prácticas aun es un eslabón débil en la gestión de conservación. Proporciono un método cuantitativo de conservación para la mariposa mirmecófila Maculinea alcon en peligro en Holanda. Se investigó a las 127 colonias conocidas en brezales desde 1990 para calidad, tamaño y aislamiento del fragmento. Evalué la calidad del hábitat en tres parcelas de 10 × 10 m en la mayoría de las colonias. La ocupación de sitios en 1998-1999 fue sólo 56%. La ocupación fue mejor explicada por regresión logística incluyendo la superficie del fragmento, presencia de hormigas huésped, abundancia de plantas huésped, superficie total del brezal y conectividad entre sitios ( R2= 0.410, p < 0.0001); clasificó el estatus de ocupado o vacante en 82% de los sitios. La conectividad contribuyó con solo 36% de la variación total de sitio de ocupación, lo que indica que las características de hábitat fueron más importantes que el aislamiento en la determinación de la persistencia de la población en el nivel de escala examinado (>500 m). El pastoreo y el corte de pasto tuvieron un impacto benéfico pero combinadas, estas prácticas fueron perjudiciales. Obras hidrológicas para prevenir la desecación también se asociaron con una disminución en la ocupación. Utilicé los diferentes componentes de la regresión logística para formular recomendaciones objetivas de gestión. Estas incluyeron el corte de pasto, reducción en la intensidad de manejo, aumento de hábitat o combinaciones de estas recomendaciones. Los resultados resaltan la importancia de la gestión cuidadosa cuando la calidad del sitio está determinada por múltiples factores. El método cuantitativo de preservación utilizado puede ser extendido exitosamente a otras especies en peligro, siempre que sean suficientemente conocidos sus requerimientos ecológicos y la forma en que le afectan las acciones de manejo. [source]

Are CB1 receptor antagonists nootropic or cognitive impairing agents?

Stephen A. Varvel
Abstract For more than a decade, a considerable amount of research has examined the effects of rimonabant (SR 141716) and other CB1 receptor antagonists in both in vivo and in vitro models of learning and memory. In addition to its utility in determining whether the effects of drugs are mediated though a CB1 receptor mechanism of action, these antagonists are useful in providing insight into the physiological function of the endogenous cannabinoid system. Several groups have reported that CB1 receptor antagonists enhance memory duration in a variety of spatial and operant paradigms, but not in all paradigms. Conversely, disruption of CB1 receptor signaling also impairs extinction learning in which the animal actively suppresses a learned response when reinforcement has been withheld. These extinction deficits occur in aversively motivated tasks, such as in fear conditioning or escape behavior in the Morris water maze task, but not in appetitively motivated tasks. Similarly, in electrophysiological models, CB1 receptor antagonists elicit a variety of effects, including enhancement of long-term potentiation (LTP), while disrupting long-term depression (LTD) and interfering with transient forms of plasticity, including depolarization-induced suppression of inhibition (DSI) and depolarization-induced suppression of excitation (DSE). The collective results of the in vivo and in vitro studies employing CB1 receptor antagonists, demonstrate that these receptors play integral roles in different components of cognitive processing. Functionally, pharmacological blockade of CB1 receptors may strengthen memory duration, but interferes with extinction of learned behaviors that are associated with traumatic or aversive memories. Drug Dev Res 70:555,565, 2009. © 2009 Wiley-Liss, Inc. [source]

Gully-head erosion processes on a semi-arid valley floor in Kenya: a case study into temporal variation and sediment budgeting

D. J. Oostwoud Wijdenes
Abstract A three year monitoring programme of gully-head retreat was established to assess the significance of sediment production in a drainage network that expanded rapidly by gully-head erosion on the low-angled alluvio-lacustrine Njemps Flats in semi-arid Baringo District, Kenya. This paper discusses the factors controlling the large observed spatial and temporal variation in gully-head retreat rates, ranging from 0 to 15 m a,1. The selected gullies differed in planform and in runoff-contributing catchment area but soil material and land use were similar. The data were analysed at event and annual timescales. The results show that at annual timescale rainfall amount appears to be a good indicator of gully-head retreat, while at storm-event timescale rainfall distribution has to be taken into account. A model is proposed, including only rainfall (P) and the number of dry days (DD) between storms: which explains 56 per cent of the variation in retreat rate of the single-headed gully of Lam1. A detailed sediment budget has been established for Lam1 and its runoff-contributing area (RCA). By measuring sediment input from the RCA, the sediment output by channelized flow and linear retreat of the gully head for nine storms, it can be seen that erosion shifts between different components of the budget depending on the duration of the dry period (DD) between storms. Sediment input from the RCA was usually the largest component for the smaller storms. The erosion of the gully head occurred as a direct effect of runoff falling over the edge (GHwaterfall) and of the indirect destabilization of the adjacent walls by the waterfall erosion and by saturation (GHmass/storage). The latter component (GHmass/storage) was usually much larger that the former (GHwaterfall). The sediment output from the gully was strongly related to the runoff volume while the linear retreat, because of its complex behaviour, was not. Overall, the results show that the annual retreat is the optimal timescale to predict retreat patterns. More detailed knowledge about relevant processes and interactions is necessary if gully-head erosion is to be included in event-based soil erosion models. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Prediction of spatially distributed seismic demands in specific structures: Ground motion and structural response

Brendon A. Bradley
Abstract The efficacy of various ground motion intensity measures (IMs) in the prediction of spatially distributed seismic demands (engineering demand parameters, (EDPs)) within a structure is investigated. This has direct implications to building-specific seismic loss estimation, where the seismic demand on different components is dependent on the location of the component in the structure. Several common IMs are investigated in terms of their ability to predict the spatially distributed demands in a 10-storey office building, which is measured in terms of maximum interstorey drift ratios and maximum floor accelerations. It is found that the ability of an IM to efficiently predict a specific EDP depends on the similarity between the frequency range of the ground motion that controls the IM and that of the EDP. An IMs predictability has a direct effect on the median response demands for ground motions scaled to a specified probability of exceedance from a ground motion hazard curve. All of the IMs investigated were found to be insufficient with respect to at least one of magnitude, source-to-site distance, or epsilon when predicting all peak interstorey drifts and peak floor accelerations in a 10-storey reinforced concrete frame structure. Careful ground motion selection and/or seismic demand modification is therefore required to predict such a spatially distributed demands without significant bias. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Oxidative stress as a mediator of life history trade-offs: mechanisms, measurements and interpretation

Pat Monaghan
Abstract The concept of trade-offs is central to our understanding of life-history evolution. The underlying mechanisms, however, have been little studied. Oxidative stress results from a mismatch between the production of damaging reactive oxygen species (ROS) and the organism's capacity to mitigate their damaging effects. Managing oxidative stress is likely to be a major determinant of life histories, as virtually all activities generate ROS. There is a recent burgeoning of interest in how oxidative stress is related to different components of animal performance. The emphasis to date has been on immediate or short-term effects, but there is an increasing realization that oxidative stress will influence life histories over longer time scales. The concept of oxidative stress is currently used somewhat loosely by many ecologists, and the erroneous assumption often made that dietary antioxidants are necessarily the major line of defence against ROS-induced damage. We summarize current knowledge on how oxidative stress occurs and the different methods for measuring it, and highlight where ecologists can be too simplistic in their approach. We critically review the potential role of oxidative stress in mediating life-history trade-offs, and present a framework for formulating appropriate hypotheses and guiding experimental design. We indicate throughout potentially fruitful areas for further research. [source]

Four ways towards tropical herbivore megadiversity

Thomas M. Lewinsohn
Abstract Most multicellular species alive are tropical arthropods associated with plants. Hence, the host-specificity of these species, and their diversity at different scales, are keys to understanding the assembly structure of global biodiversity. We present a comprehensive scheme in which tropical herbivore megadiversity can be partitioned into the following components: (A) more host plant species per se, (B) more arthropod species per plant species, (C) higher host specificity of herbivores, or (D) higher species turnover (beta diversity) in the tropics than in the temperate zone. We scrutinize recent studies addressing each component and identify methodological differences among them. We find substantial support for the importance of component A, more tropical host species. A meta-analysis of published results reveals intermediate to high correlations between plant and herbivore diversity, accounting for up to 60% of the variation in insect species richness. Support for other factors is mixed, with studies too scarce and approaches too uneven to allow for quantitative summaries. More research on individual components is unlikely to resolve their relative contribution to overall herbivore diversity. Instead, we call for the adoption of more coherent methods that avoid pitfalls for larger-scale comparisons, for studies assessing different components together rather than singly, and for studies that investigate herbivore beta-diversity (component D) in a more comprehensive perspective. [source]

Capillary electrophoresis-mass spectrometry characterisation of secondary metabolites from the antihyperglycaemic plant Genista tenera

Emma L. Edwards
Abstract Genista tenera is endemic to the Portuguese island of Madeira, where an infusion of the aerial parts of the plant is used in folk medicine as an antidiabetic agent. Consequently the medicinal properties of the secondary metabolites of this plant have been the subject of an ongoing study. A recently reported LC-MS method using a 100,min separation allowed identification of five flavonoid components in an extract of the aerial parts of this plant. In order to obtain additional information on the range and complexity of the plant's secondary metabolite components a CE-MS method has been developed and applied for the analysis of an extract of G.,tenera. Twenty-six different components are distinguished in an analysis time of only 10,min. Results demonstrate that CE-MS/MS rapidly generates data complementary to those obtainable by LC-MS/MS and is particularly suited to the analysis of plant metabolites where concentration is not limiting. [source]

On the use of generalized linear models for interpreting climate variability

Richard E. Chandler
Abstract Many topical questions in climate research can be reduced to either of two related problems: understanding how various different components of the climate system affect each other, and quantifying changes in the system. This article aims to justify the addition of generalized linear models to the climatologist's toolkit, by demonstrating that they offer an intuitive and flexible approach to such problems. In particular, we provide some suggestions as to how ,typical' climatological data structures may be represented within the GLM framework. Recurring themes include methods for space,time data and the need to cope with large datasets. The ideas are illustrated using a dataset of monthly U.S. temperatures. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Bayesian hierarchical models in ecological studies of health,environment effects

Sylvia Richardson
Abstract We describe Bayesian hierarchical models and illustrate their use in epidemiological studies of the effects of environment on health. The framework of Bayesian hierarchical models refers to a generic model building strategy in which unobserved quantities (e.g. statistical parameters, missing or mismeasured data, random effects, etc.) are organized into a small number of discrete levels with logically distinct and scientifically interpretable functions, and probabilistic relationships between them that capture inherent features of the data. It has proved to be successful for analysing many types of complex epidemiological and biomedical data. The general applicability of Bayesian hierarchical models has been enhanced by advances in computational algorithms, notably those belonging to the family of stochastic algorithms based on Markov chain Monte Carlo techniques. In this article, we review different types of design commonly used in studies of environment and health, give details on how to incorporate the hierarchical structure into the different components of the model (baseline risk, exposure) and discuss the model specification at the different levels of the hierarchy with particular attention to the problem of aggregation (ecological) bias. Copyright © 2003 John Wiley & Sons, Ltd. [source]

The Effect of Male Incubation Feeding, Food and Temperature on the Incubation Behaviour of New Zealand Robins

ETHOLOGY, Issue 6 2010
Rebecca L. Boulton
Because of finite resources, organisms face conflict between their own self-care and reproduction. This conflict is especially apparent in avian species with female-only incubation, where females face a trade-off between time allocated to their own self-maintenance and the thermal requirements of developing embryos. We recorded incubation behaviour of the New Zealand robin (Petroica longipes), a species with female-only incubation, male incubation feeding and high nest predation rates. We examined how male incubation feeding, ambient temperature and food availability (invertebrate biomass) affected the different components of females' incubation behaviour and whether incubation behaviour explained variation in nest survival. Our results suggest that male incubation feeding rates of 2.8 per hour affect the female's incubation rhythm by reducing both on- and off-bout duration, resulting in no effect on female nest attentiveness, thus no support for the female-nutritional hypothesis. The incubation behaviours that we measured did not explain nest survival, despite high nest predation rates. Increased ambient temperature caused an increase in off-bout duration, whereas increased food availability increased on-bout duration. While males play a vital role in influencing incubation behaviour, female robins attempt to resolve the trade-off between their own foraging needs and the thermal requirements of their developing embryos via alternating their incubation rhythm in relation to both food and temperature. [source]

International conference on the healthy effect of virgin olive oil


Summary 1Ageing represents a great concern in developed countries because the number of people involved and the pathologies related with it, like atherosclerosis, morbus Parkinson, Alzheime's disease, vascular dementia, cognitive decline, diabetes and cancer. 2Epidemiological studies suggest that a Mediterranean diet (which is rich in virgin olive oil) decreases the risk of cardiovascular disease. 3The Mediterranean diet, rich in virgin olive oil, improves the major risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile. Endothelial function, inflammation and oxidative stress are also positively modulated. Some of these effects are attributed to minor components of virgin olive oil. Therefore, the definition of the Mediterranean diet should include virgin olive oil. 4Different observational studies conducted in humans have shown that the intake of monounsaturated fat may be protective against age-related cognitive decline and Alzheimer's disease. 5Microconstituents from virgin olive oil are bioavailable in humans and have shown antioxidant properties and capacity to improve endothelial function. Furthermore they are also able to modify the haemostasis, showing antithrombotic properties. 6In countries where the populations fulfilled a typical Mediterranean diet, such as Spain, Greece and Italy, where virgin olive oil is the principal source of fat, cancer incidence rates are lower than in northern European countries. 7The protective effect of virgin olive oil can be most important in the first decades of life, which suggests that the dietetic benefit of virgin olive oil intake should be initiated before puberty, and maintained through life. 8The more recent studies consistently support that the Mediterranean diet, based in virgin olive oil, is compatible with a healthier ageing and increased longevity. However, despite the significant advances of the recent years, the final proof about the specific mechanisms and contributing role of the different components of virgin olive oil to its beneficial effects requires further investigations. [source]

Neurons with distinctive firing patterns, morphology and distribution in laminae V,VII of the neonatal rat lumbar spinal cord

Péter Szûcs
Abstract It is generally accepted that neurons in the ventral spinal grey matter, a substantial proportion of which can be regarded as constituents of the spinal motor apparatus, receive and integrate synaptic inputs arising from various peripheral, spinal and supraspinal sources. Thus, a profound knowledge concerning the integrative properties of interneurons in the spinal ventral grey matter appears to be essential for a fair understanding of operational principles of spinal motor neural assemblies. Using the whole cell patch clamp configuration in a correlative physiological and morphological experimental approach, here we demonstrate that the intrinsic membrane properties of neurons vary widely in laminae V,VII of the ventral grey matter of the neonatal rat lumbar spinal cord. Based on their firing patterns in response to depolarizing current steps, we have classified the recorded neurons into four categories: ,phasic', ,repetitive', ,single' and ,slow'. Neurons with firing properties characteristic of the ,phasic', ,repetitive' and ,single' cells have previously been reported also in the superficial and deep spinal dorsal horn, but this is the first account in the literature in which ,slow' neurons have been recovered and described in the spinal cord. The physiological heterogeneity in conjunction with the morphological correlation and distribution of neurons argues that different components of motor neural assemblies in the spinal ventral grey matter possess different signal processing characteristics. [source]

Intrathecally applied flurbiprofen produces an endocannabinoid-dependent antinociception in the rat formalin test

Mehmet Ates
Abstract It is generally accepted that the phospholipase-A2 -cyclooxygenase-prostanoids-cascade mediates spinal sensitization and hyperalgesia. However, some observations are not in line with this hypothesis. The aim of the present work was to investigate whether different components of this cascade exhibit nociceptive or antinociceptive effects in the rat formalin test. Intrathecal (i.th.) injection of prostaglandin E2 (PGE2) induced a dose-dependent antinociceptive effect on the formalin-induced nociception. Furthermore, thimerosal, which inhibits the reacylation of arachidonic acid thereby enhancing arachidonic acid levels, had an antinociceptive effect rather than the expected pronociceptive effect when given i.th. While the phospholipase A2 inhibitor methyl arachidonyl fluorophosphonate (MAFP; i.th.) had a significant antinociceptive effect, its analogue palmitoyl trifluoromethyl ketone (PTFMK; i.th.) had no significant effect on the formalin-induced nociception. However, MAFP, but not PTFMK, showed a cannabinoid CB1 agonistic effect as shown by the inhibition of electrically evoked contractions of the vas deferens isolated from CB1 wild-type mice but not of that from CB1 knockout mice. The antinociceptive effect of MAFP was completely reversed by the CB1 receptor antagonist AM-251 (i.th.), thus attributing such effect to its CB1 agonistic effect. Moreover, the antinociceptive effect of the cyclooxygenase inhibitor, flurbiprofen (i.th.) was reversed by the co-administration of AM-251, but not by PGE2. Finally. the combination of phenylmethylsulfonyl fluoride (PMSF; intraperitoneal), which inhibits the degradation of anandamide through the inhibition of fatty acid amidohydrolase, with thimerosal (i.th.) produced a profound CB1 -dependent antinociception. The present results show that endocannabinoids play a major role in mediating flurbiprofen-induced antinociception at the spinal level. [source]

Discontented people: reactivity and locus of control as determinants of subjective well-being

Tatiana Klonowicz
This study examines the effects of reactivity temperament and locus of control variables on subjective well-being (SWB). SWB is operationalized as positive affect, the absence of somatic concerns, and heightened life satisfaction. The study hypotheses were that (1) reactivity and locus of control influenced SWB and that (2) affect either mediated or moderated the influence of these traits on SWB. As expected, high reactivity and external locus of control were associated with lower SWB, whereas low reactivity and internal locus of control were associated with higher SWB. However, the data indicate that reactivity and locus of control influenced different components of SWB and that locus of control predicted SWB more consistently than reactivity. Somatic health is influenced by reactivity, locus of control and negative affect, but not positive affect. Current life satisfaction is influenced by locus of control,but not reactivity,and by both positive and negative affect. Hope is related to reactivity but not to either locus of control or affect. The data corroborate the expectation that affect serves as a mediator in the trait,SWB relations, whereas the view that affect moderates the effect of stable dispositions on SWB finds scant support. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Workers, worries and welfare states: Social protection and job insecurity in 15 OECD countries

Based on data on people's attitudes toward their job as well as levels of and kinds of social protection collected in 15 OECD countries, it shows that there are distinct manifestations of job insecurity that are affected differently by distinct aspects of social protection programs. While the analysis shows that social protection measures reduce employment insecurity, it also reveals that overall levels welfare state generosity do not have any systematic effect on whether workers feel secure. The article's findings suggest the need to decompose the different components of employment insecurity as well as disaggregate national systems of social protection when examining the impact of welfare states on job insecurity. [source]

Effects of mortality salience aroused by threats against human identity on intergroup bias

Echebarria-Echabe Agustin
An experimental study on the effects of mortality salience aroused by threats against different components of the Self (personal, social and human identities) on intergroup bias is presented. It is hypothesised and found that the mortality salience per se does not inevitably led to increments of intergroup bias. This increment occurs when mortality salience is aroused by threats against personal or social identities. Copyright © 2009 John Wiley & Sons, Ltd. [source]

C-Nociceptor Activation of Hypothalamic Neurones and the Columnar Organisation of Their Projections to the Periaqueductal Grey in the Rat

B. M. Lumb
The induction of Fos protein was used to localise hypothalamic neurones activated by ramps of noxious skin heating delivered at a rate of 2.5 °C s,1 to preferentially activate C-nociceptors. This was combined with retrograde transport of cholera toxin subunit B from identified ,pressor' and ,depressor' sites in the dorsolateral/lateral or the ventrolateral columns of the periaqueductal grey. Fos-positive neurones were found throughout the rostral hypothalamus. Despite this wide distribution, those neurones double labelled retrogradely from the periaqueductal grey were focused in the lateral area of the anterior hypothalamus. More than 20% of Fos-positive neurones in this region projected to depressor sites in the ventrolateral periaqueductal grey, and 10% projected to its dorsolateral/lateral sector. These results are discussed in relation to the peripheral inputs to hypothalamic-midbrain pathways and their role in the cardiovascular responses to different components of the pain signal. [source]

Adherence factors of Lactobacillus in the human gastrointestinal tract

Mónica Perea Vélez
Abstract Despite the increasing number of scientific reports describing adhesion of Lactobacillus to components of the human intestinal mucosa, information on the surface molecules mediating this adhesion and their corresponding receptors is fragmentary. This MiniReview compiles present knowledge of the genetically and functionally characterized Lactobacillus factors responsible for mediating adhesion to different components of the human gastrointestinal tract. In addition, for the proteins among these factors, the domain structure is discussed, and where appropriate the results of in silico analyses are reported. [source]

Weedbeds and big bugs: the importance of scale in detecting the influence of nutrients and predation on macroinvertebrates in plant-dominated shallow lakes

Summary 1. The scale of investigations influences the interpretation of results. Here, we investigate the influence of fish and nutrients on biotic communities in shallow lakes, using studies at two different scales: (i) within-lake experimental manipulation and (ii) comparative, among-lake relationships. 2. At both scales, fish predation had an overriding influence on macroinvertebrates; fish reduced macroinvertebrate biomass and altered community composition. Prey selection appeared to be size based. Fish influenced zooplankton abundance and light penetration through the water column also, but there was no indication that fish caused increased resuspension of sediment. 3. There were effects of nutrients at both scales, but these effects differed with the scale of the investigation. Nutrients increased phytoplankton and periphyton at the within-lake scale, and were associated with increased periphyton at the among-lake scale. No significant effect of nutrients on macroinvertebrates was observed at the within-lake scale. However, at the among-lake scale, nutrients positively influenced the biomass and density of macroinvertebrates, and ameliorated the effect of fish on macroinvertebrates. 4. Increased prey availability at higher nutrient concentrations would be expected to cause changes in the fish community. However, at the among-lake scale, differences were not apparent in fish biomass among lakes with different nutrient conditions, suggesting that stochastic events influence the fish community in these small and relatively isolated shallow lakes. 5. The intensity of predation by fish significantly influences macroinvertebrate community structure of shallow lakes, but nutrients also play a role. The scale of investigation influences the ability to detect the influence of nutrients on the different components of shallow lake communities, particularly for longer lived organisms such as macroinvertebrates, where the response takes longer to manifest. [source]