4,384 research outputs found

    Ultrafast dynamics of neutral superexcited Oxygen: A direct measurement of the competition between autoionization and predissociation

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    Using ultrafast extreme ultraviolet pulses, we performed a direct measurement of the relaxation dynamics of neutral superexcited states corresponding to the nl\sigma_g(c^4\Sigma_u^-) Rydberg series of O_2. An XUV attosecond pulse train was used to create a temporally localized Rydberg wavepacket and the ensuing electronic and nuclear dynamics were probed using a time-delayed femtosecond near-infrared pulse. We investigated the competing predissociation and autoionization mechanisms for superexcited molecules and found that autoionization is dominant for the low n Rydberg states. We measured an autoionization lifetime of 92+/-6 fs and 180+/-10 fs for (5s,4d)\sigma_g and (6s,5d)\sigma_g Rydberg state groups respectively. We determine that the disputed neutral dissociation lifetime for the \nu=0 vibrational level of the Rydberg series is 1100+/-100fs.Comment: 5 pages, 4 figure

    Emergency nurse practitioners and doctors consulting with patients in an emergency department : a comparison of communication skills and satisfaction

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    Background: Emergency nurse practitioners (ENPs) play an increasingly important role in UK emergency departments (EDs), but there is limited evidence about how this affects patient care and outcome. A study was undertaken to compare the content of, and satisfaction with, consultations made with patients presenting with problems of low acuity to an ED. Methods: Patients presenting with "primary care" problems were allocated to senior house officers (SHOs, n = 10), specialist registrars/staff grades (n = 7), sessionally-employed general practitioners (GPs, n = 12) or ENPs (n = 6) randomly rostered to work in a consulting room that had a wall-mounted video camera. At the end of each consultation the doctor/ENP and the patient were asked to complete the Physician/Patient Satisfaction Questionnaire. A stratified sample of videotaped consultations (n = 296) was analysed in depth using the Roter Interaction Analysis System. The main outcome measures were length of consultation; numbers of utterances of doctor/ENP and patient talk related to building a relationship, data gathering, activating/partnering, and patient education/counselling; doctor/ENP and patient consultation satisfaction scores. Results: ENPs and GPs focused more on patient education and counselling about the medical condition or therapeutic regimen than did ED doctors. There were no significant differences in consultation length. ENPs had higher levels of overall self-satisfaction with their consultations than ED doctors. Patient satisfaction with how actively they participated in the consultation was significantly associated with the amount of talk relating to building a relationship and activating and partnering, and patient satisfaction with information giving in the consultation was significantly associated with the amount of talk relating to building a relationship. Conclusion: These findings suggest differences between ENP and ED doctor consultations which are associated with some aspects of patient satisfaction. In contrast to previous reports, consultation length was not greater for ENPs than for doctors. There is a need for further research to test the generalisability of these findings and their impact on clinical outcome

    Subgap Two-Photon States in Polycyclic Aromatic Hydrocarbons: Evidence for Strong Electron Correlations

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    Strong electron correlation effects in the photophysics of quasi-one-dimensional π\pi-conjugated organic systems such as polyenes, polyacetylenes, polydiacetylenes, etc., have been extensively studied. Far less is known on correlation effects in two-dimensional π\pi-conjugated systems. Here we present theoretical and experimental evidence for moderate repulsive electron-electron interactions in a number of finite polycyclic aromatic hydrocarbon molecules with D6hD_{6h} symmetry. We show that the excited state orderings in these molecules are reversed relative to that expected within one-electron and mean-field theories. Our results reflect similarities as well as differences in the role and magnitude of electron correlation effects in these two-dimensional molecules compared to those in polyenes.Comment: 11 pages, 5 figures, 2 table

    More security or less insecurity

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    We depart from the conventional quest for ‘Completely Secure Systems’ and ask ‘How can we be more Secure’. We draw heavily from the evolution of the Theory of Justice and the arguments against the institutional approach to Justice. Central to our argument is the identification of redressable insecurity, or weak links. Our contention is that secure systems engineering is not really about building perfectly secure systems but about redressing manifest insecurities.Final Accepted Versio

    Secure Role-Based Workflow Models

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    Re-imaging everyday routines and educational aspirations under COVID-19 lockdown: Narratives of urban middle-class children in Punjab, India

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    Based on in-depth interviews with 24 middle-class Indian child participants, this is the first exploratory qualitative study, in India, to demonstrate the ways in which children as reflexive social actors re-negotiated everyday schedules, drew on classed resources at their disposal and made sense of the impact of the pandemic on their educational pathways and future aspirations. These narratives offer a unique lens on the politics of middle-classness and its constitutive relation to constructions of normative childhoods in contemporary India. Study findings contribute to the sociology of Indian childhood and more generally help enrich our understanding of southern childhoods and the reproduction of inequalities in contemporary India

    Optimizing adipogenic transdifferentiation of bovine mesenchymal stem cells: a prominent role of ascorbic acid in FABP4 induction

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    Adipocyte differentiation of bovine adipose-derived stem cells (ASC) was induced by foetal bovine serum (FBS), biotin, pantothenic acid, insulin, rosiglitazone, dexamethasone and 3-isobutyl-1-methylxanthine, followed by incubation in different media to test the influence of ascorbic acid (AsA), bovine serum lipids (BSL), FBS, glucose and acetic acid on transdifferentiation into functional adipocytes. Moreover, different culture plate coatings (collagen-A, gelatin-A or poly-L-lysine) were tested. The differentiated ASC were subjected to Nile red staining, DAPI staining, immunocytochemistry and quantitative reverse transcription PCR (for NT5E, THY1, ENG, PDGFRα, FABP4, PPARγ, LPL, FAS, GLUT4). Nile red quantification showed a significant increase in the development of lipid droplets in treatments with AsA and BSL without FBS. The presence of BSL induced a prominent increase in FABP4 mRNA abundance and in FABP4 immunofluorescence signals in coincubation with AsA. The abundance of NT5E, ENG and THY1 mRNA decreased or tended to decrease in the absence of FBS, and ENG was additionally suppressed by AsA. DAPI fluorescence was higher in cells cultured in poly-L-lysine or gelatin-A coated wells. In additional experiments, the multi-lineage differentiation potential to osteoblasts was verified in medium containing ß-glycerophosphate, dexamethasone and 1,25-dihydroxyvitamin D3 using alizarin red staining. In conclusion, bovine ASC are capable of multi-lineage differentiation. Poly-L-lysine or gelatin-A coating, the absence of FBS, and the presence of BSL and AsA favour optimal transdifferentiation into adipocytes. AsA supports transdifferentiation via a unique role in FABP4 induction, but this is not linearly related to the primarily BSL-driven lipid accumulation

    High sensitivity and multifunctional micro-Hall sensors fabricated using InAlSb/InAsSb/InAlSb heterostructures

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    Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm(2) V-1 s(-1) and 2.5 x 10(11) cm(-2), respectively. The maximum current-related sensitivity was 2 750 V A(-1) T-1, which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 mu m x 1 mu m Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk
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