4,913 research outputs found
Reusable chelating resins concentrate metal ions from highly dilute solutions
Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed
Architects of time: Labouring on digital futures
Drawing on critical analyses of the internet inspired by Gilles Deleuze and the Marxist autonomia movement, this paper suggests a way of understanding the impact of the internet and digital culture on identity and social forms through a consideration of the relationship between controls exercised through the internet, new subjectivities constituted through its use and new labour practices enabled by it. Following Castells, we can see that the distinction between user, consumer and producer is becoming blurred and free labour is being provided by users to corporations. The relationship between digital technologies and sense of community, through their relationship to the future, is considered for its dangers and potentials. It is proposed that the internet may be a useful tool for highlighting and enabling social connections if certain dangers can be traversed. Notably, current remedies for the lack of trust on the internet are questioned with an alternative, drawing on Zygmunt Bauman and Georg Simmel, proposed which is built on community through a vision of a ‘shared network’
Giant Magnetic Moments of Nitrogen Stabilized Mn Clusters and Their Relevance to Ferromagnetism in Mn Doped GaN
Using first principles calculations based on density functional theory, we
show that the stability and magnetic properties of small Mn clusters can be
fundamentally altered by the presence of nitrogen. Not only are their binding
energies substantially enhanced, but also the coupling between the magnetic
moments at Mn sites remains ferromagnetic irrespective of their size or shape.
In addition, these nitrogen stabilized Mn clusters carry giant magnetic moments
ranging from 4 Bohr magnetons in MnN to 22 Bohr magnetons in Mn_5N. It is
suggested that the giant magnetic moments of Mn_xN clusters may play a key role
in the ferromagnetism of Mn doped GaN which exhibit a wide range (10K - 940K)
of Curie temperatures
The Infrared Imaging Spectrograph (IRIS) for TMT: the atmospheric dispersion corrector
We present a conceptual design for the atmospheric dispersion corrector (ADC)
for TMT's Infrared Imaging Spectrograph (IRIS). The severe requirements of this
ADC are reviewed, as are limitations to observing caused by uncorrectable
atmospheric effects. The requirement of residual dispersion less than 1
milliarcsecond can be met with certain glass combinations. The design decisions
are discussed and the performance of the design ADC is described. Alternative
options and their performance tradeoffs are also presented.Comment: SPIE Astronomical Instrumentation 201
Radioaktivnost u cisternskim vodama u Hrvatskoj
The levels of radioactivity in cistern waters in the areas along the Adriatic coast have been investigated since 1962 when high total beta activity and 90Sr were detected. A rapid decline followed after the nuclear moratorium. Since 1970 a small increase due to Chinese nuclear weapon tests has been registered. Several cistern waters in the villages around Zagreb were investigated while the nuclear power station was still under construction. Very low alpha and beta radioactivity originating from fall-out was detected.Nivo radioaktivnosti u cisternskim vodama duž Jadrana ispituje se od 1962. godine. Prati se stalno ukupna beta-aktivnost i 90Sr. Nakon prestanka velikih pokusa s nuklearnim oružjem, radioaktivnost je naglo pala i ostala niska do sada. Poslije 1968. godine došlo je do malog povišenja nivoa radioaktivnosti uslijed kineskih nuklearnih eksperimenata, međutim, značajnog povišenja nije bilo. Tokom dvije godine praćena je i alfa i beta aktivnost cisternskih voda u blizini Zagreba kao nulta točka prije rada nuklearne elektrane Krško. Istraživanja se nastavljaju
Diffusion, Cell Mobility, and Bandlimited Functions
The mechanism by which leukocytes steer toward a chemical attractant is not fully resolved. Experimental data suggest that these cells detect differences in concentration of chemoattractant over their surface and walk up the gradient. The problem has been considered theoretically only in stationary media, where the distribution of attractant is determined solely by diffusion. Experimentally, bulk flow has been allowed only unintentionally. Since bulk flow is characteristic of real systems, we examine a simple two-dimensional model incorporating both diffusion and an additional drift. The latter problem leads to an integral equation which is central also in the study of weighted Hilbert spaces of bandlimited functions. We find asymptotic expressions for the required solution by a Wiener-Hopf method adapted to a finite interval. We conclude that, without drift, the concentration does not vary detectably around the cell, but that drift inceases this variation substantially. Thus over model suggests that drift may play an important role in the cell\u27s chemotactic response
Healthcare choice: Discourses, perceptions, experiences and practices
Policy discourse shaped by neoliberal ideology, with its emphasis on marketisation and competition, has highlighted the importance of choice in the context of healthcare and health systems globally. Yet, evidence about how so-called consumers perceive and experience healthcare choice is in short supply and limited to specific healthcare systems, primarily in the Global North. This special issue aims to explore how choice is perceived and utilised in the context of different systems of healthcare throughout the world, where choice, at least in policy and organisational terms, has been embedded for some time. The articles are divided into those emphasising: embodiment and the meaning of choice; social processes associated with choice; the uncertainties, risks and trust involved in making choices; and issues of access and inequality associated with enacting choice. These sociological studies reveal complexities not always captured in policy discourse and suggest that the commodification of healthcare is particularly problematic
Personal, Social, and Environmental Mediators Associated With Increased Recreational Physical Activity in Women and Girls in the Kingdom of Tonga.
BACKGROUND: The purpose of this paper was to identify personal, social, and environmental mediators of recreational physical activity (PA) in a 6-month netball-based intervention for women and girls in Tonga. METHODS: Tonga Netball's "low-engagement village program" was implemented in 10 villages and aimed to increase the recreational PA levels in women and girls through a comprehensive, structured community-level netball program addressing key barriers to participation. In a mixed-methods approach, these mediating barriers were identified through qualitative interviews based on the socioecological model. Quantitative measures for mediators and recreational PA were then developed, and data from 301 women and girls were collected. Standard mediation analyses methods were then applied. RESULTS: Program participation appeared to significantly increase PA levels. Statistically significant personal mediators were body issues, preferring competitions, and clothing. Social mediators were support from sports council, community leaders, friends, and church. Environmental mediators were travel time and access to balls, bibs, and umpires. CONCLUSION: A comprehensive community-level program addressing key participation barriers can increase recreational PA among women and girls in Tonga. Triangulating these results with mediation analyses of variables on the causal pathway can strengthen our understanding of causation and inform funding prioritization for critical program components in similar contexts
The concept of solidarity: emerging from the theoretical shadows?
The concept of solidarity has been relatively neglected by social scientists since Durkheim's pioneering work in the late 19th century. The discipline of politics has been guilty of overlooking this 'subjective' element of community life, but recent works by Stjernø and Brunkhorst reflect a growing awareness of the theoretical significance of the concept. Whereas early liberal attempts to theorise solidarity took the nation state to be the appropriate community for its realisation, the emergence of globalisation raises the possibility of human solidarity developing in the global community. Traditional forms of solidarity have been dissipated by the social changes accompanying globalisation, but they were often locked into the defence of particular interests. New forms may be emerging to rekindle the broader vision of human solidarity. Recent work by writers such as Habermas, Honneth, Rorty and Touraine focuses on widening and deepening democratic participation and/or the articulation of our ethical obligations in various ways. It is argued here that these perspectives need to be supplemented by a radical humanist approach grounded in a normative theory of human self-realisation
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