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’

Hydrocephalus in Africa: A surgical perspective

No Abstrac

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 Dirichlet problem for the Bellman equation at resonance

We generalize the Donsker-Varadhan minimax formula for the principal eigenvalue of a uniformly elliptic operator in nondivergence form to the first principal half-eigenvalue of a fully nonlinear operator which is concave (or convex) and positively homogeneous. Examples of such operators include the Hamilon-Jacobi-Bellman operator and the Pucci extremal operators. In the case that the two principal half-eigenvalues are not equal, we show that the measures which achieve the minimum in this formula provide a partial characterization of the solvability of the corresponding Dirichlet problem at resonance.Comment: Appendix added. 28 page

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

Model za predskazivanje aktivnosti 90sr u mlijeku

A model used by UNSCEAR (1) to describe the transfer of 90Sr from deposition to milk is presented. The data collected in 25 years concerning 90Sr levels in fallout and milk are given for the Zagreb area. The model shows a very good agreement with empirical data and a statistically significant relationship between 90Sr level in milk and 90Sr level in fallout (correlation index is 0.987).U radu je opisan model transfera 90Sr od radioaktivnih padavina do mlijeka koji je predložio UNSCEAR (1). Sakupljeni su podaci o aktivnosti 90Sr u radioaktivnim padavinama i mlijeku iz područja Zagreba. Model pokazuje vrlo dobro slaganje s empirijskim podacima i statistički značajnu povezanost između aktivnosti 90Sr u mlijeku i radioaktivnim padavinama (indeks korelacije je 0,987)

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

Does physical activity moderate the association between alcohol drinking and all-cause, cancer and cardiovascular diseases mortality risk? A pooled analysis of eight British population cohorts

OBJECTIVE: To examine whether physical activity (PA) moderates the association between alcohol intake and all-cause mortality, cancer mortality and cardiovascular diseases (CVDs) mortality. DESIGN: Prospective study using 8 British population-based surveys, each linked to cause-specific mortality: Health Survey for England (1994, 1998, 1999, 2003, 2004 and 2006) and Scottish Health Survey (1998 and 2003). PARTICIPANTS: 36 370 men and women aged 40 years and over were included with a corresponding 5735 deaths and a mean of 353 049 person-years of follow-up. EXPOSURES: 6 sex-specific categories of alcohol intake (UK units/week) were defined: (1) never drunk; (2) ex-drinkers; (3) occasional drinkers; (4) within guidelines (35 (women) >49 (men)). PA was categorised as inactive (≤7 MET-hour/week), active at the lower (>7.5 MET-hour/week) and upper (>15 MET-hour/week) of recommended levels. MAIN OUTCOMES AND MEASURES: Cox proportional-hazard models were used to examine associations between alcohol consumption and all-cause, cancer and CVD mortality risk after adjusting for several confounders. Stratified analyses were performed to evaluate mortality risks within each PA stratum. RESULTS: We found a direct association between alcohol consumption and cancer mortality risk starting from drinking within guidelines (HR (95% CI) hazardous drinking: 1.40 (1.11 to 1.78)). Stratified analyses showed that the association between alcohol intake and mortality risk was attenuated (all-cause) or nearly nullified (cancer) among individuals who met the PA recommendations (HR (95% CI)). CONCLUSIONS: Meeting the current PA public health recommendations offsets some of the cancer and all-cause mortality risk associated with alcohol drinking

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