A novel simplified mathematical model for antennas used in medical imaging applications

In this paper a new technique is proposed to model the current across a monopole antenna and thereby the radiation fields of the antenna can be calculated. Generally, the Method of Moments (MOM) technique is used for this purpose whereby the integral equations are discretised to find the fields of an antenna. The proposed model requires only the knowledge of three parameters (Initial Current I0, Damping coefficient a and the radial parameter ?) and hence considerably reduces the computational time and space as its results do not depend on the number of functions involved. The new technique is also developed to take account of the conductivity property of the surrounding medium. Hence this technique can be used in field prediction for antennas employed in medical imaging applications. Initial results obtained from the new technique show good correlation in comparison with the MOM technique

Shedding Light on Fish Otolith Biomineralization Using a Bioenergetic Approach

Otoliths are biocalcified bodies connected to the sensory system in the inner ears of fish. Their layered, biorhythm-following formation provides individual records of the age, the individual history and the natural environment of extinct and living fish species. Such data are critical for ecosystem and fisheries monitoring. They however often lack validation and the poor understanding of biomineralization mechanisms has led to striking examples of misinterpretations and subsequent erroneous conclusions in fish ecology and fisheries management. Here we develop and validate a numerical model of otolith biomineralization. Based on a general bioenergetic theory, it disentangles the complex interplay between metabolic and temperature effects on biomineralization. This model resolves controversial issues and explains poorly understood observations of otolith formation. It represents a unique simulation tool to improve otolith interpretation and applications, and, beyond, to address the effects of both climate change and ocean acidification on other biomineralizing organisms such as corals and bivalves

Beyond the therapeutic: a Habermasian view of self-help groups’ place in the public sphere

Self-help groups in the United Kingdom continue to grow in number and address virtually every conceivable health condition, but they remain the subject of very little theoretical analysis. The literature to date has predominantly focused on their therapeutic effects on individual members. And yet they are widely presumed to fulfil a broader civic role and to encourage democratic citizenship. The article uses Habermas’ model of the public sphere as an analytical tool with which to reconsider the literature on self-help groups in order to increase our knowledge of their civic functions. In doing this it also aims to illustrate the continuing relevance of Habermas’ work to our understanding of issues in health and social care. We consider, within the context of current health policies and practices, the extent to which self-help groups with a range of different forms and functions operate according to the principles of communicative rationality that Habermas deemed key to democratic legitimacy. We conclude that self-help groups’ civic role is more complex than is usually presumed and that various factors including groups’ leadership, organisational structure and links with public agencies can affect their efficacy within the public sphere

Self-help groups challenge health care systems in the US and UK

Purpose: This research considers how self-help groups (SHGs) and self- help organizations (SHOs) contribute to consumerist trends in two different societies: United States and United Kingdom. How do the health care systems and the voluntary sectors affect the kinds of social changes that SHGs/SHOs make? Methodology/approach: A review of research on the role of SHGs/SHOs in contributing to national health social movements in the UK and US was made. Case studies of the UK and the US compare the characteristics of their health care systems and their voluntary sector. Research reviews of two community level self-help groups in each country describe the kinds of social changes they made. Findings: The research review verified that SHGs/SHOs contribute to national level health social movements for patient consumerism. The case studies showed that community level SHGs/SHOs successfully made the same social changes but on a smaller scale as the national movements, and the health care system affects the kinds of community changes made. Research limitations: A limited number of SHGs/SHOs within only two societies were studied. Additional SHGs/SHOs within a variety of societies need to be studied. Originality/value of chapter Community SHGs/SHOs are often trivialized by social scientists as just inward-oriented support groups, but this chapter shows that local groups contribute to patient consumerism and social changes but in ways that depend on the kind of health care system and societal context

Intrapopulation Variability Shaping Isotope Discrimination and Turnover: Experimental Evidence in Arctic Foxes

Tissue-specific stable isotope signatures can provide insights into the trophic ecology of consumers and their roles in food webs. Two parameters are central for making valid inferences based on stable isotopes, isotopic discrimination (difference in isotopic ratio between consumer and its diet) and turnover time (renewal process of molecules in a given tissue usually measured when half of the tissue composition has changed). We investigated simultaneously the effects of age, sex, and diet types on the variation of discrimination and half-life in nitrogen and carbon stable isotopes (δ15N and δ13C, respectively) in five tissues (blood cells, plasma, muscle, liver, nail, and hair) of a top predator, the arctic fox Vulpes lagopus. We fed 40 farmed foxes (equal numbers of adults and yearlings of both sexes) with diet capturing the range of resources used by their wild counterparts. We found that, for a single species, six tissues, and three diet types, the range of discrimination values can be almost as large as what is known at the scale of the whole mammalian or avian class. Discrimination varied depending on sex, age, tissue, and diet types, ranging from 0.3‰ to 5.3‰ (mean = 2.6‰) for δ15N and from 0.2‰ to 2.9‰ (mean = 0.9‰) for δ13C. We also found an impact of population structure on δ15N half-life in blood cells. Varying across individuals, δ15N half-life in plasma (6 to 10 days) was also shorter than for δ13C (14 to 22 days), though δ15N and δ13C half-lives are usually considered as equal. Overall, our multi-factorial experiment revealed that at least six levels of isotopic variations could co-occur in the same population. Our experimental analysis provides a framework for quantifying multiple sources of variation in isotopic discrimination and half-life that needs to be taken into account when designing and analysing ecological field studies

The great melting pot. Common sole population connectivity assessed by otolith and water fingerprints

Quantifying the scale and importance of individual dispersion between populations and life stages is a key challenge in marine ecology. The common sole (Solea solea), an important commercial flatfish in the North Sea, Atlantic Ocean and the Mediterranean Sea, has a marine pelagic larval stage, a benthic juvenile stage in coastal nurseries (lagoons, estuaries or shallow marine areas) and a benthic adult stage in deeper marine waters on the continental shelf. To date, the ecological connectivity among these life stages has been little assessed in the Mediterranean. Here, such an assessment is provided for the first time for the Gulf of Lions, NW Mediterranean, based on a dataset on otolith microchemistry and stable isotopic composition as indicators of the water masses inhabited by individual fish. Specifically, otolith Ba/Ca and Sr/Ca profiles, and delta C-13 and delta O-18 values of adults collected in four areas of the Gulf of Lions were compared with those of young-of-the-year collected in different coastal nurseries. Results showed that a high proportion of adults (>46%) were influenced by river inputs during their larval stage. Furthermore Sr/Ca ratios and the otolith length at one year of age revealed that most adults (similar to 70%) spent their juvenile stage in nurseries with high salinity, whereas the remainder used brackish environments. In total, data were consistent with the use of six nursery types, three with high salinity (marine areas and two types of highly saline lagoons) and three brackish (coastal areas near river mouths, and two types of brackish environments), all of which contributed to the replenishment of adult populations. These finding implicated panmixia in sole population in the Gulf of Lions and claimed for a habitat integrated management of fisherie

Nutrients and their duration of enrichment influence periphyton cover and biomass in rural and urban streams

© CSIRO 2008Although it is well known that land use affects nutrient dynamics and algal growth in streams, the responses to different durations of nutrient supply are poorly understood. The associations of benthic (periphyton-dominated) biomass with concentrations of dissolved nitrogen and phosphorus in rural and urban streams in New York were quantified. Biomass was significantly greater (2-fold) in the urban compared with the rural stream, which was associated with differences in dissolved nutrients. Experimental field enrichment of nutrient concentrations and duration of exposure altered benthic periphyton. Increasing nutrients by 60–99% of ambient concentrations increased periphyton percentage cover and biomass. Periphyton abundance also increased with increasing duration of exposure to nutrients (2, 4 and 8 weeks); however, short-term pulses of nutrients (2 weeks) had no significant effect in the rural stream. These results indicate that effective management of nutrient delivery, by reducing time periods of high nutrient load, will minimise impacts to benthic environmentsTravis S. Elsdon and Karin E. Limbur

An education for the people? A history of HMI and lifelong education 1944-1992

SIGLEAvailable from British Library Document Supply Centre-DSC:m01/16048 / BLDSC - British Library Document Supply CentreGBUnited Kingdo