Predictive vegetation mapping in the Mediterranean context: Considerations and methodological issues

The need to map vegetation communities over large areas for nature conservation and to predict the impact of environmental change on vegetation distributions, has stimulated the development of techniques for predictive vegetation mapping. Predictive vegetation studies start with the development of a model relating vegetation units and mapped physical data, followed by the application of that model to a geographic database and over a wide range of spatial scales. This field is particularly important for identifying sites for rare and endangered species and locations of high biodiversity such as many areas of the Mediterranean Basin. The potential of the approach is illustrated with a mapping exercise in the alti-meditterranean zone of Lefka Ori in Crete. The study established the nature of the relationship between vegetation communities and physical data including altitude, slope and geomorphology. In this way the knowledge of community distribution was improved enabling a GIS-based model capable of predicting community distribution to be constructed. The paper describes the development of the spatial model and the methodological problems of predictive mapping for monitoring Mediterranean ecosystems. The paper concludes with a discussion of the role of predictive vegetation mapping and other spatial techniques, such as fuzzy mapping and geostatistics, for improving our understanding of the dynamics of Mediterranean ecosystems and for practical management in a region that is under increasing pressure from human impact.

Process scheduling by output considerations

In multi-tasking systems when it is not possible to guarantee completion of all activities by specified times, the scheduling problem is not straightforward. Examples of this situation in real-time programming include the occurrence of alarm conditions and the buffering of output to peripherals in on-line facilities. The latter case is studied here with the hope of indicating one solution to the general problem.

A critical assessment of unbalanced surface stresses: Some complementary considerations

The wide-ranging survey of twisted growth in polymers by Lotz and Cheng cites extensive evidence consistent with the relief of surface stress being the underlying cause. This complementary note contributes to the discussion by making three main points. First, it is necessary to go further and explain the key issue of how a consistent twist is maintained when, as commonly, this habit has a lower symmetry than the crystallographic lattice. Detailed study has shown that, in polyethylene, this occurs by reorganization of the initial fold surfaces. Second, the suggested explanation by Keith and Padden that. in polyethylene, the asymmetric habit derives from molecules adding to lamellae with inclined fold surfaces is invalid being doubly inconsistent with observation. Third, twisting has now been linked to faster growth by study of row structures in polyethylene. This produces inherently rough fold surfaces in Regime II whose internal stresses drive reorganization and twisting. For slower (Regime I) growth, fold surfaces form with and maintain ordered packing so providing no basis for twisting. These new insights radically alter the context of twisted growth and provide a firm factual basis for further work. (c) 2005 Elsevier Ltd. All rights reserved.

In vitro cumulative gas production techniques: History, methodological considerations and challenges

Methodology used to measure in vitro gas production is reviewed to determine impacts of sources of variation on resultant gas production profiles (GPP). Current methods include measurement of gas production at constant pressure (e.g., use of gas tight syringes), a system that is inexpensive, but may be less sensitive than others thereby affecting its suitability in some situations. Automated systems that measure gas production at constant volume allow pressure to accumulate in the bottle, which is recorded at different times to produce a GPP, and may result in sufficiently high pressure that solubility of evolved gases in the medium is affected, thereby resulting in a recorded volume of gas that is lower than that predicted from stoichiometric calculations. Several other methods measure gas production at constant pressure and volume with either pressure transducers or sensors, and these may be manual, semi-automated or fully automated in operation. In these systems, gas is released as pressure increases, and vented gas is recorded. Agitating the medium does not consistently produce more gas with automated systems, and little or no effect of agitation was observed with manual systems. The apparatus affects GPP, but mathematical manipulation may enable effects of apparatus to be removed. The amount of substrate affects the volume of gas produced, but not rate of gas production, provided there is sufficient buffering capacity in the medium. Systems that use a very small amount of substrate are prone to experimental error in sample weighing. Effect of sample preparation on GPP has been found to be important, but further research is required to determine the optimum preparation that mimics animal chewing. Inoculum is the single largest source of variation in measuring GPP, as rumen fluid is variable and sampling schedules, diets fed to donor animals and ratios of rumen fluid/medium must be selected such that microbial activity is sufficiently high that it does not affect rate and extent of fermentation. Species of donor animal may also cause differences in GPP. End point measures can be mathematically manipulated to account for species differences, but rates of fermentation are not related. Other sources of inocula that have been used include caecal fluid (primarily for investigating hindgut fermentation in monogastrics), effluent from simulated rumen fermentation (e.g., 'Rusitec', which was as variable as rumen fluid), faeces, and frozen or freeze-dried rumen fluid (which were both less active than fresh rumen fluid). Use of mixtures of cell-free enzymes, or pure cultures of bacteria, may be a way of increasing GPP reproducibility, while reducing reliance on surgically modified animals. However, more research is required to develop these inocula. A number of media have been developed which buffer the incubation and provide relevant micro-nutrients to the microorganisms. To date, little research has been completed on relationships between the composition of the medium and measured GPP. However, comparing GPP from media either rich in N or N-free, allows assessment of contributions of N containing compounds in the sample. (c) 2005 Published by Elsevier B.V.

Cell entry by enveloped viruses: redox considerations for HIV and SARS-coronavirus

For enveloped viruses, genome entry into the target cell involves two major steps: virion binding to the cell-surface receptor and fusion of the virion and cell membranes. Virus-cell membrane fusion is mediated by the virus envelope complex, and its fusogenicity is the result of an active virus-cell interaction process that induces conformation changes within the envelope. For some viruses, such as influenza, exposure to an acidic milieu within the cell during the early steps of infection triggers the necessary structural changes. However, for other pathogens which are not exposed to such environmental stress, activation of fusogenicity can result from precise thiol/disulfide rearrangements mediated by either an endogenous redox autocatalytic isomerase or a cell-associated oxidoreductase. Study of the activation of HIV envelope fusogenicity has revealed new knowledge about how redox changes within a viral envelope trigger fusion. We discuss these findings and their implication for anti-HIV therapy. In addition, to compare and contrast the situation outlined for HIV with an enveloped virus that can fuse with the cell plasma membrane independent of the redox status of its envelope protein, we review parallel data obtained on SARS coronavirus entry.

Bahrain's Formula-1 racing circuit: energy and environmental considerations

The Bahrain International Circuit (BIC) and complex, at latitude 26.00N and longitude 51.54E, was built in 483 days and cost 150 million US$. The circuit consists of six different individual tracks with a 3.66 km outer track (involving 10 turns) and a 2.55 km inner track (having six turns). The complex has been designed to host a variety of other sporting activities. Fifty thousand spectators, including 10,500 in the main grandstand, can be accommodated simultaneously. State-of-the art on-site media and broadcast facilities are available. The noise level emitted from vehicles on the circuit during the Formula-1 event, on April 4th 2004, was acceptable and caused no physical disturbance to the fans in the VIP lounges or to scholars studying at the University of Bahrain's Shakeir Campus, which is only 1.5 km away from the circuit. The sound-intensity level (SIL) recorded on the balcony of the VIP lounge was 128 dB(A) and was 80 dB(A) inside the lounge. The calculated SIL immediately outside the lecture halls of the University of Bahrain was 70 dB(A) and 65 dB(A) within them. Thus racing at BIC can proceed without significantly disturbing the academic-learning process. The purchased electricity demand by the BIC complex peaked (at 4.5 MW) during the first Formula-1 event on April 4th 2004. The reverse-osmosis (RO) plant at the BIC provides 1000 m(3) of desalinated water per day for landscape irrigation. Renewable-energy inputs, (i.e., via solar and wind power), at the BIC could be harnessed to generate electricity for water desalination, air conditioning, lighting as well as for irrigation. If the covering of the BIC complex was covered by adhesively fixed modern photovoltaic cells, then similar to 1.2 MW of solar electricity could be generated. If two horizontal-axis, at 150 m height above the ground, three 75m bladed, wind turbines were to be installed at the BIC, then the output could reach 4 MW. Furthermore, if 10,000 Jojoba trees (a species renowned for having a low demand for water, needing only five irrigations per year in Bahrain and which remain green throughout the year) are planted near the circuit, then the local micro-climate would be improved with respect to human comfort as well as the local environment becoming cleaner.

The impact of flavonoids on memory: physiological and molecular considerations

Emerging evidence suggests that a group of dietary-derived phytochemicals known as flavonoids are able to induce improvements in memory acquisition, consolidation, storage and retrieval. These low molecular weight polyphenols are widespread in the human diet, are absorbed to only a limited degree and localise in the brain at low concentration. However, they have been found to be highly effective in reversing age-related declines in memory via their ability to interact with the cellular and molecular architecture of the brain responsible for memory. These interactions include an ability to activate signalling pathways, critical in controlling synaptic plasticity, and a potential to induce vascular effects capable of causing new nerve cell growth in the hippocampus. Their ability to activate the extracellular signal-regulated kinase (ERK1/2) and the protein kinase B (PKB/Akt) signalling pathways, leading to the activation of the cAMP response element-binding protein (CREB), a transcription factor responsible for increasing the expression of a number of neurotrophins important in de. ning memory, will be discussed. How these effects lead to improvements in memory through induction of synapse growth and connectivity, increases in dendritic spine density and the functional integration of old and new neurons will be illustrated. The overall goal of this critical review is to emphasize future areas of investigation as well as to highlight these dietary agents as promising candidates for the design of memory-enhancing drugs with relevance to normal and pathological brain ageing (161 references).

Mechanisms of probiosis and prebiosis: considerations for enhanced functional foods

The technologies of metagenomics and metabolomics are broadening our knowledge of the roles the human gut microbiota play in health and disease. For many years now, probiotics and prebiotics have been included in foods for their health benefits; however, we have only recently begun to understand their modes of action. This review highlights recent advances in deciphering the mechanisms of probiosis and prebiosis, and describes how this knowledge could be transferred to select for enhancing functional foods targeting different populations. A special focus will be given to the addition of prebiotics and probiotics in functional foods for infants and seniors.

Weight of evidence needed to substantiate a health effect for probiotics and prebiotics: regulatory considerations in Canada, EU, and US

Successful and responsible introduction of probiotic and prebiotic products into the worldwide marketplace requires labelling for health benefits that meets consumer needs, adheres to regulatory standards and does not overextend scientific evidence. Regulations differ among countries, but underlying all is an emphasis on scientific credibility of any statements of health benefits. This paper considers the value of different types of evidence offered in substantiation of efficacy and reviews different regulatory approaches to labelling for health claims. Limitations of in vitro, animal and different types of human studies used for efficacy substantiation for probiotics and prebiotics are discussed.

Inverse effectiveness, multisensory integration, and the bodily self: some statistical considerations

A recent report in Consciousness and Cognition provided evidence from a study of the rubber hand illusion (RHI) that supports the multisensory principle of inverse effectiveness (PoIE). I describe two methods of assessing the principle of inverse effectiveness ('a priori' and 'post-hoc'), and discuss how the post-hoc method is affected by the statistical artefact of,regression towards the mean'. I identify several cases where this artefact may have affected particular conclusions about the PoIE, and relate these to the historical origins of 'regression towards the mean'. Although the conclusions of the recent report may not have been grossly affected, some of the inferential statistics were almost certainly biased by the methods used. I conclude that, unless such artefacts are fully dealt with in the future, and unless the statistical methods for assessing the PoIE evolve, strong evidence in support of the PoIE will remain lacking. (C) 2009 Elsevier Inc. All rights reserved.