316,870 research outputs found
The UK geography of the E-Society: a national classification
It is simplistic to think of the impacts of new information and communication technologies (ICTs) in terms of a single, or even small number of, 'digital divides'. As developments in what has been termed the ?e-society? reach wider and more generalisedaudiences, so it becomes appropriate to think of digital media as having wider-ranging but differentiated impacts upon consumer transactions, information gathering and citizen participation. This paper describes the development of a detailed, nationwide household classification based on levels of awareness of different ICTs; levels of use of ICTs; andtheir perceived impacts upon human capital formation and the quality of life. It discusses how geodemographic classification makes it possible to provide context for detailed case studies, and hence identify how policy might best improve both the quality and degree ofsociety?s access to ICTs. The primary focus of the paper is methodological, but it alsoillustrates how the classification may be used to investigate a range of regional and subregional policy issues. This paper illustrates the potential contribution of bespoke classifications to evidence-based policy, and the likely benefits of combining the most appropriate methods, techniques, datasets and practices that are used in the public and private sectors. It is simplistic to think of the impacts of new information and communication technologies (ICTs) in terms of a single, or even small number of, 'digital divides'. As developments in what has been termed the ?e-society? reach wider and more generalisedaudiences, so it becomes appropriate to think of digital media as having wider-rangingbut differentiated impacts upon consumer transactions, information gathering and citizen participation. This paper describes the development of a detailed, nationwide household classification based on levels of awareness of different ICTs; levels of use of ICTs; and their perceived impacts upon human capital formation and the quality of life. It discusses how geodemographic classification makes it possible to provide context for detailed case studies, and hence identify how policy might best improve both the quality and degree of society?s access to ICTs. The primary focus of the paper is methodological, but it also illustrates how the classification may be used to investigate a range of regional and subregional policy issues. This paper illustrates the potential contribution of bespoke classifications to evidence-based policy, and the likely benefits of combining the most appropriate methods, techniques, datasets and practices that are used in the public and private sectors
Multi-line detection of O_2 toward ρ Ophiuchi A
Context. Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O_2, and water, H_(2)O. These high abundances imply high cooling rates, leading to relatively short timescales for the evolution of gravitationally unstable dense cores, forming stars and planets. Contrary to expectations, the dedicated space missions SWAS and Odin typically found only very small amounts of water vapour and essentially no O_2 in the dense star-forming interstellar medium.
Aims. Only toward ρOph A did Odin detect a very weak line of O_2 at 119 GHz in a beam of size 10 arcmin. The line emission of related molecules changes on angular scales of the order of some tens of arcseconds, requiring a larger telescope aperture such as that of the Herschel Space Observatory to resolve the O2 emission and pinpoint its origin.
Methods. We use the Heterodyne Instrument for the Far Infrared (HIFI) aboard Herschel to obtain high resolution O_2 spectra toward selected positions in the ρOph A core. These data are analysed using standard techniques for O_2 excitation and compared to recent PDR-like chemical cloud models.
Results. The N_J = 3_(3) − 1_(2) line at 487.2 GHz is clearly detected toward all three observed positions in the ρOph A core. In addition, an oversampled map of the 5_(4)−3_(4) transition at 773.8 GHz reveals the detection of the line in only half of the observed area. On the basis of their ratios, the temperature of the O_2 emitting gas appears to vary quite substantially, with warm gas (≳ 50K) being adjacent to a much colder region, of temperatures lower than 30 K.
Conclusions. The exploited models predict that the O_2 column densities are sensitive to the prevailing dust temperatures, but rather insensitive to the temperatures of the gas. In agreement with these models, the observationally determined O_2 column densities do not seem to depend strongly on the derived gas temperatures, but fall into the range N(O_2) = 3 to ≳ 6 × 10^(15) cm^(-2). Beam-averaged O2 abundances are about 5 × 10^(-8) relative to H_2. Combining the HIFI data with earlier Odin observations yields a source size at 119 GHz in the range of 4 to 5 arcmin, encompassing the entire ρOph A core. We speculate that one of the reasons for the generally very low detection rate of O2 is the short period of time during which O_2 molecules are reasonably abundant in molecular clouds
Tracing the Pathway from Drift-Wave Turbulence with Broken Symmetry to the Generation of Sheared Axial Mean Flow
This study traces the emergence of sheared axial flow from collisional drift
wave turbulence with broken symmetry in a linear plasma device---CSDX. As the
density profile steepens, the axial Reynolds stress develops and drives a
radially sheared axial flow that is parallel to the magnetic field. Results
show that the non-diffusive piece of the Reynolds stress is driven by the
density gradient and results from the spectral asymmetry of the turbulence and
thus is dynamical in origin. Taken together, these findings constitute the
first simultaneous demonstration of the causal link between the density
gradient, turbulence and stress with broken spectral symmetry, and the mean
axial flow
Steady-State Two Atom Entanglement in a Pumped Cavity
In this paper we explore the possibility of a steady-state entanglement of
two two-level atoms inside a pumped cavity by taking into account cavity
leakage and the spontaneous emission of photons by the atoms. We describe the
system in the dressed state picture in which the coherence is built into the
dressed states while transitions between the dressed states are incoherent. Our
model assumes the vacuum Rabi splitting of the dressed states to be much larger
than any of the decay parameters of the system which allows atom-field
coherence to build up before any decay process takes over. We show that, under
our model, a pumping field cannot entangle two closed two-level atoms inside
the cavity in the steady-state, but a steady-state entanglement can be achieved
with two open two-level atoms.Comment: 19 pages, 5 figure
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