2,912 research outputs found

    Interplay between the ionic and electronic density profiles in liquid metal surfaces

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    First principles molecular dynamics simulations have been performed for the liquid-vapor interfaces of liquid Li, Mg, Al and Si. We analize the oscillatory ionic and valence electronic density profiles obtained, their wavelengths and the mechanisms behind their relative phase-shift.Comment: Accepted for publication in Journal of Chemical Physic

    Conducting and reporting trials for older people

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    Randomised controlled trials provide the most rigorous test of efficacy and effectiveness for interventions used in healthcare. They underpin much of clinical practice, yet older people are often excluded from studies, resulting in uncertainty about risks and benefits of new treatments. Encouraging inclusion of older people in randomised controlled trials and reporting of trial results in a rigorous manner is a key function of clinical geriatrics journals such as Age and Ageing. This article provides practical advice on how to report randomised controlled trials that are targeted at older people. Some of these issues are generic, but there are specific requirements which apply to most studies of older people. Recording and reporting basic characteristics of recruits in terms of physical function, cognition, comorbidity and/or frailty is vital to allow proper interpretation of the external validity of the trial. Adverse effects should include consideration of common geriatric problems including falls. Authors should follow the CONSORT reporting guidelines (CONsolidated Standards Of Reporting Trials) to enhance the transparency and quality of their manuscript

    Surface structure in simple liquid metals. An orbital free first principles study

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    Molecular dynamics simulations of the liquid-vapour interfaces in simple sp-bonded liquid metals have been performed using first principles methods. Results are presented for liquid Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl, and Si at thermodynamic conditions near their respective triple points, for samples of 2000 particles in a slab geometry. The longitudinal ionic density profiles exhibit a pronounced stratification extending several atomic diameters into the bulk, which is a feature already experimentally observed in liquid K, Ga, In, Sn and Hg. The wavelength of the ionic oscillations shows a good scaling with the radii of the associated Wigner-Seitz spheres. The structural rearrangements at the interface are analyzed in terms of the transverse pair correlation function, the coordination number and the bond-angle distribution between nearest neighbors. The valence electronic density profile also shows (weaker) oscillations whose phase, with respect to those of the ionic profile, changes from opposite phase in the alkalis to almost in-phase for Si.Comment: 16 pages, 18 figures, 5 tables. Submitted to Phys. Rev.

    An Algorithmic Framework for Labeling Network Maps

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    Drawing network maps automatically comprises two challenging steps, namely laying out the map and placing non-overlapping labels. In this paper we tackle the problem of labeling an already existing network map considering the application of metro maps. We present a flexible and versatile labeling model. Despite its simplicity, we prove that it is NP-complete to label a single line of the network. For a restricted variant of that model, we then introduce an efficient algorithm that optimally labels a single line with respect to a given weighting function. Based on that algorithm, we present a general and sophisticated workflow for multiple metro lines, which is experimentally evaluated on real-world metro maps.Comment: Full version of COCOON 2015 pape

    The school-to-work transition, skill preferences and matching

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    This empirical paper investigates skill formation in the youth labour market. Using event-history data collected from the administrative records of Lancashire Careers Service, we model skill preferences formed at school by young people and skill destination, ie the occupation of the first job/training scheme after leaving compulsory schooling. We also model the duration of the individuals first unemployment spell. Competing risks models with flexible piece-wise linear baseline hazards and unobserved heterogeneity are estimated. There is evidence of occupational segregation by gender, unrealistic occupational preferences and excess supply of skills. Outcomes are mainly determined by examination performance, ethnicity and whether disadvantaged.

    Octilinear Force-Directed Layout with Mental Map Preservation for Schematic Diagrams

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    We present an algorithm for automatically laying out metro map style schematics using a force-directed approach, where we use a localized version of the standard spring embedder forces combined with an octilinear magnetic force. The two types of forces used during layout are naturally conflicting, and the existing method of simply combining these to generate a resultant force does not give satisfactory results. Hence we vary the forces, emphasizing the standard forces in the beginning to produce a well distributed graph, with the octilinear forces becoming prevalent at the end of the layout, to ensure that the key requirement of line angles at intervals of 45? is obtained. Our method is considerably faster than the more commonly used search-based approaches, and we believe the results are superior to the previous force-directed approach. We have further developed this technique to address the issues of dynamic schematic layout. We use a Delaunay triangulation to construct a schematic “frame”, which is used to retain relative node positions and permits full control of the level of mental map preservation. This technique is the first to combine mental map preservation techniques with the additional layout criteria of schematic diagrams. To conclude, we present the results of a study to investigate the relationship between the level of mental map preservation and the user response time and accuracy

    The stellar mass function of star-forming galaxies and the mass-dependent SFR function since z = 2.23 from HiZELS

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    We explore a large uniformly selected sample of Hα selected star-forming galaxies (SFGs) at z = 0.40, 0.84, 1.47, 2.23 to unveil the evolution of the star formation rate (SFR) function and the stellar mass function. We find strong evolution in the SFR function, with the typical SFR of SFGs declining exponentially in the last 11 Gyr as SFR*(T[Gyr]) = 104.23/T + 0.37 M⊙ yr−1, but with no evolution in the faint-end slope, α ≈ −1.6. The stellar mass function of SFGs, however, reveals little evolution: α ≈ −1.4, M* ∌ 1011.2 ± 0.2 M⊙ and just a slight increase of ∌2.3× in Ί* from z = 2.23 to z = 0.4. The stellar mass density within SFGs has been roughly constant since z = 2.23 at ∌107.65 ± 0.08 M⊙ Mpc−3, comprising ≈100 per cent of the stellar mass density in all galaxies at z = 2.23, and declining to ≈20 per cent by z = 0.40, driven by the rise of the passive population. We find that SFGs with ∌1010.0 ± 0.2 M⊙ contribute most to the SFR density (ρSFR) per d log10M, and that there is no significant evolution in the fractional contribution from SFGs of different masses to ρSFR or ρSFR(d log10M)−1 since z = 2.23. Instead, we show that the decline of SFR* and of ρSFR is primarily driven by an exponential decline in SFRs at all masses. Our results have important implications not only on how SFGs need to be quenched across cosmic time, but also on the driver(s) of the exponential decline in SFR* from ∌66 M⊙ yr−1 to 5 M⊙ yr−1 since z ∌ 2.23

    5-year follow-up of cytotoxic chemotherapy as an adjuvant to surgery in carcinoma of the bronchus.

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    This report gives the 5-year findings of a double-blind study of long-term cytotoxic chemotherapy as an adjuvant to surgery in patients receiving busulphan or cyclophosphamide for carcinoma of the bronchus compared with a group receiving a placebo. Of 243 patients initially allocated busulphan, 234 cyclophosphamide and 249 placebo, 28%, 27% and 34% respectively were alive at 5 years. There were significant associations between mortality from bronchial carcinoma and histological involvement of the resected intrathoracic nodes and the histology of the tumour. Haematological toxicity, especially thrombocytopenia, was frequent and severe in the busulphan series, and low platelet counts continued long after chemotherapy was stopped
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