2,662 research outputs found
Living apart, losing sympathy? How neighbourhood context affects attitudes to redistribution and to welfare recipients
Rising levels of income inequality have been directly linked to rising levels of spatial segregation. In this paper, we explore whether rising segregation may in turn erode support for the redistributive policies of the welfare state, further increasing levels of inequality – a form of positive feedback. The role of the neighbourhood has been neglected in attitudes research but, building on both political geography and ‘neighbourhood effects’ literatures, we theorise that neighbourhood context may shape attitudes through the transmission of attitudes directly and through the accumulation of relevant knowledge. We test this through multilevel modelling of data from England on individual attitudes to redistribution in general and to welfare benefit recipients in particular. We show that the individual factors shaping these attitudes are quite different and that the influence of neighbourhood context also varies as a result. The findings support the idea that neighbourhood context shapes attitudes, with the knowledge accumulation mechanism likely to be the more important. Rising spatial segregation would appear to erode support for redistribution but to increase support for welfare recipients – at least in a context where the dominant media discourse presents such a stigmatising image of those on welfare benefits
Adsorption characteristics of acetaldehyde on activated carbons prepared from corn-based biomass precursor
The ACs (R-1/2 and R-1/4) having two different textual and chemical properties are prepared from corn-based biomass precursor and evaluated together with a wood-based activated carbon (WAC) at room temperature using a gas chromatograph. The results obtained from the correlation studies indicate that the pore size distribution (below 8Å) and the relatively lower energetic heterogeneity of ACs on acetaldehyde adsorption are considerable factors rather than that of a specific surface area and surface chemistry. The adsorption equilibrium of ACs is well correlated with the Sips equation. The pseudo second-order equation was better in describing the ACs' adsorption kinetic of acetaldehyde. © Taylor & Francis Group, LLC
Commentary: Selecting synaptic partners: GRASPing the role of UNC- 6/netrin
Forming synaptic connections of the appropriate strength between specific neurons is crucial for constructing neural circuits to control behavior. A recent paper in Neural Development describes the use of a synapse-specific label in Caenorhabditis elegans to implicate local UNC-6/netrin signaling in this developmental process. Thus, as well as their well known roles in cell migration and axon guidance, UNC-6/netrin signals distinguish an appropriate synaptic partner from other potential targets
The Kondo effect in ferromagnetic atomic contacts
Iron, cobalt and nickel are archetypal ferromagnetic metals. In bulk,
electronic conduction in these materials takes place mainly through the and
electrons, whereas the magnetic moments are mostly in the narrow
-electron bands, where they tend to align. This general picture may change
at the nanoscale because electrons at the surfaces of materials experience
interactions that differ from those in the bulk. Here we show direct evidence
for such changes: electronic transport in atomic-scale contacts of pure
ferromagnets (iron, cobalt and nickel), despite their strong bulk
ferromagnetism, unexpectedly reveal Kondo physics, that is, the screening of
local magnetic moments by the conduction electrons below a characteristic
temperature. The Kondo effect creates a sharp resonance at the Fermi energy,
affecting the electrical properties of the system;this appears as a Fano-Kondo
resonance in the conductance characteristics as observed in other artificial
nanostructures. The study of hundreds of contacts shows material-dependent
lognormal distributions of the resonance width that arise naturally from Kondo
theory. These resonances broaden and disappear with increasing temperature,
also as in standard Kondo systems. Our observations, supported by calculations,
imply that coordination changes can significantly modify magnetism at the
nanoscale. Therefore, in addition to standard micromagnetic physics, strong
electronic correlations along with atomic-scale geometry need to be considered
when investigating the magnetic properties of magnetic nanostructures.Comment: 7 pages, 5 figure
External sources of clean technology: evidence from the clean development mechanism
New technology is fundamental to sustainable development. However, inventors from industrialized countries often refuse technology transfer because they worry about reverse-engineering. When can clean technology transfer succeed? We develop a formal model of the political economy of North–South technology transfer. According to the model, technology transfer is possible if (1) the technology in focus has limited global commercial potential or (2) the host developing country does not have the capacity to absorb new technologies for commercial use. If both conditions fail, inventors from industrialized countries worry about the adverse competitiveness effects of reverse-engineering, so technology transfer fails. Data analysis of technology transfer in 4,894 projects implemented under the Kyoto Protocol’s Clean Development Mechanism during the 2004–2010 period provides evidence in support of the model
Nonequilibrium Singlet-Triplet Kondo Effect in Carbon Nanotubes
The Kondo-effect is a many-body phenomenon arising due to conduction
electrons scattering off a localized spin. Coherent spin-flip scattering off
such a quantum impurity correlates the conduction electrons and at low
temperature this leads to a zero-bias conductance anomaly. This has become a
common signature in bias-spectroscopy of single-electron transistors, observed
in GaAs quantum dots as well as in various single-molecule transistors. While
the zero-bias Kondo effect is well established it remains uncertain to what
extent Kondo correlations persist in non-equilibrium situations where inelastic
processes induce decoherence. Here we report on a pronounced conductance peak
observed at finite bias-voltage in a carbon nanotube quantum dot in the spin
singlet ground state. We explain this finite-bias conductance anomaly by a
nonequilibrium Kondo-effect involving excitations into a spin triplet state.
Excellent agreement between calculated and measured nonlinear conductance is
obtained, thus strongly supporting the correlated nature of this nonequilibrium
resonance.Comment: 21 pages, 5 figure
Early and efficient detection of Mycobacterium tuberculosis in sputum by microscopic observation of broth cultures.
Early, efficient and inexpensive methods for the detection of pulmonary tuberculosis are urgently needed for effective patient management as well as to interrupt transmission. These methods to detect M. tuberculosis in a timely and affordable way are not yet widely available in resource-limited settings. In a developing-country setting, we prospectively evaluated two methods for culturing and detecting M. tuberculosis in sputum. Sputum samples were cultured in liquid assay (micro broth culture) in microplate wells and growth was detected by microscopic observation, or in Löwenstein-Jensen (LJ) solid media where growth was detected by visual inspection for colonies. Sputum samples were collected from 321 tuberculosis (TB) suspects attending Bugando Medical Centre, in Mwanza, Tanzania, and were cultured in parallel. Pulmonary tuberculosis cases were diagnosed using the American Thoracic Society diagnostic standards. There were a total of 200 (62.3%) pulmonary tuberculosis cases. Liquid assay with microscopic detection detected a significantly higher proportion of cases than LJ solid culture: 89.0% (95% confidence interval [CI], 84.7% to 93.3%) versus 77.0% (95% CI, 71.2% to 82.8%) (p = 0.0007). The median turn around time to diagnose tuberculosis was significantly shorter for micro broth culture than for the LJ solid culture, 9 days (interquartile range [IQR] 7-13), versus 21 days (IQR 14-28) (p<0.0001). The cost for micro broth culture (labor inclusive) in our study was US 11.35 per sample for the LJ solid culture. The liquid assay (micro broth culture) is an early, feasible, and inexpensive method for detection of pulmonary tuberculosis in resource limited settings
Spectroscopic analysis of finite size effects around a Kondo quantum dot
We consider a simple setup in which a small quantum dot is strongly connected
to a finite size box. This box can be either a metallic box or a finite size
quantum wire.The formation of the Kondo screening cloud in the box strongly
depends on the ratio between the Kondo temperature and the box level spacing.
By weakly connecting two metallic reservoirs to the quantum dot, a detailed
spectroscopic analysis can be performed. Since the transport channels and the
screening channels are almost decoupled, such a setup allows an easier access
to the measure of finite-size effects associated with the finite extension of
the Kondo cloud.Comment: contribution to Les Houches proceeding, ``Quantum magnetism'' 200
Spin qubits with electrically gated polyoxometalate molecules
Spin qubits offer one of the most promising routes to the implementation of
quantum computers. Very recent results in semiconductor quantum dots show that
electrically-controlled gating schemes are particularly well-suited for the
realization of a universal set of quantum logical gates. Scalability to a
larger number of qubits, however, remains an issue for such semiconductor
quantum dots. In contrast, a chemical bottom-up approach allows one to produce
identical units in which localized spins represent the qubits. Molecular
magnetism has produced a wide range of systems with tailored properties, but
molecules permitting electrical gating have been lacking. Here we propose to
use the polyoxometalate [PMo12O40(VO)2]q-, where two localized spins-1/2 can be
coupled through the electrons of the central core. Via electrical manipulation
of the molecular redox potential, the charge of the core can be changed. With
this setup, two-qubit gates and qubit readout can be implemented.Comment: 9 pages, 6 figures, to appear in Nature Nanotechnolog
Organic Geochemical Studies. I. Molecular Criteria for Hydrocarbon Genesis
In recent years the search for life-forms at the earliest periods of geological time has been continued not only at the morphological level but also at the molecular level. This has been possible as a result of the increase in the biochemical knowledge and with the advent of analytical techniques that are capable of describing the intimate molecular architecture of individual molecules in acute detail. The fundamental premises upon which this organic geochemical approach rest are the following: that certain molecules, possessing a characteristic structural skeleton, show a reasonable stability to degradation over long periods of geological time; that their structural specificity can be understood in terms of known biosynthetic sequences; and that their formation by any non-biological means is of negligible probability. In this manuscript it is proposed to critically re-examine these premises and to establish criteria whereby one can differentiate molecules derived from biological systems from those that have their origin in non-biological processes. The importance of establishing such criteria lies in the significance these criteria have in determining whether life exists, or has existed, on other planets. Within the very near future it may be possible to provide an initial answer to this question when the first lunar samples are returned to the earth for analysis
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