Influence of gas pressure on high-order harmonic generation of Ar and Ne

We study the effect of gas pressure on the generation of high-order harmonics where harmonics due to individual atoms are calculated using the recently developed quantitative rescattering theory, and the propagation of the laser and harmonics in the medium is calculated by solving the Maxwell's wave equation. We illustrate that the simulated spectra are very sensitive to the laser focusing conditions at high laser intensity and high pressure since the fundamental laser field is severely reshaped during the propagation. By comparing the simulated results with several experiments we show that the pressure dependence can be qualitatively explained. The lack of quantitative agreement is tentatively attributed to the failure of the complete knowledge of the experimental conditions.Comment: 7 figure

Perspectives of vaccinators on the factors affecting uptake of meningococcal ACWY vaccine amongst school leavers in London.

OBJECTIVES: Uptake of meningococcal ACWY (Men ACWY) vaccine amongst school leavers is suboptimal in London (9.9% compared to 17.4% nationally in 2015/16). This study explores service delivery barriers and elicits insights from general practice staff on their interaction with this cohort. The purpose was to inform the National Health Service England (London) public health commissioning team's strategy to improve Men ACWY vaccination uptake in London. STUDY DESIGN: Qualitative semi-structured interviews study. METHODS: Purposive sampling of practice nurses from three general practices from each of the three London clinical commissioning group areas (Barnet, Camden and Newham) with the largest numbers of 18-20 year old registered patients. Participants were recruited through their practice managers. A thematic analysis approach was used. RESULTS: A total of ten interviews were conducted between June and August 2017. Five themes were identified: (1) Nurses unsupported by practice systems; (2) difficulty getting school leavers into the practice; (3) confused messaging; (4) reliance on parental responsibility for health; and (5) perception of complacency amongst adolescents. CONCLUSION: Little is known about the service factors that impede uptake of adolescent vaccinations. This exploratory study suggests that existing programmatic mechanisms for delivering the Men ACWY catch-up programme were not adequate. The number of adolescent vaccinations offered has increased in the UK in the last five years and is likely to continue. Although the findings need to be further extrapolated in quantitative research, general practice staff need more systematic guidance on their role and how they can support vaccine decision-making in later adolescence

Creating connections - the development of a mobile-health monitoring system for heart failure:Qualitative findings from a usability cohort study

Objective There is significant interest in the role of digital health technology in enabling optimal monitoring of heart failure patients. To harness this potential, it is vital to account for users’ capacity and preferences in the development of technological solutions. We adopted an iterative approach focussed on learning from users’ interactions with a mobile-health monitoring system.Methods We used a participatory mixed methods research approach to develop and evaluate a mobile-health monitoring system. Fifty-eight heart failure patients were recruited from three health care settings in the UK and provided with Internet-enabled tablet computers that were wirelessly linked to sensor devices for blood pressure, heart rate and weight monitoring. One to two home visits were conducted with a subgroup of 29 participants to evaluate the usability of the system over a median follow-up period of six months. The thematic analysis of observational data and 45 interviews was informed by the domestication of technology theory.Results Our findings indicate that digital health technologies need to create and extend connections with health professionals, be incorporated into users’ daily routines, and be personalised according to users’ technological competencies and interest in assuming a proactive or more passive role in monitoring their condition.Conclusions Users' patterns of engagement with health technology changes over time and varies according to their need and capacity to use the technology. Incorporating diverse user experiences in the development and maintenance of mobile-health systems is likely to increase the extent of successful uptake and impacts on outcomes for patients and providers.%U http://dhj.sagepub.com/content/spdhj/2/2055207616671461.full.pd

Medium propagation effects in high harmonic generation of Ar and N2_{2}

We report theoretical calculations of high harmonic generation (HHG) by intense infrared lasers in atomic and molecular targets taking into account the macroscopic propagation of both fundamental and harmonic fields. On the examples of Ar and N$_2$, we demonstrate that these {\it ab initio} calculations are capable of accurately reproducing available experimental results with isotropic and aligned target media. We further present detailed analysis of HHG intensity and phase, under various experimental conditions, in particular, as the wavelength of the driving laser changes. Most importantly, our results strongly support the factorization of HHG at the macroscopic level into a product of a returning electron wave packet and the photorecombination transition dipole, under typical experimental conditions. This implies that the single-atom/molecule structure information can be retrieved from experimentally measured HHG spectra

Directional Velocity Measurements

Author Institution: Sandia National LaboratoriesAuthor Institution: Atomic Weapons Establishment (UK)Slides presented at the 4th Annual Photonic Doppler Velocimetry (PDV) Workshop held at the University of Texas, Austin, Texas, November 5-6, 2009

First measurement of kaonic helium-3 X-rays

The first observation of the kaonic 3He 3d - 2p transition was made using slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2 (stat)+-4 (syst) eV.Comment: Accepted for publication in Phys. Lett.

Group 2 ITI Consensus Report: Technological developments in implant prosthetics

Objectives Group‐2 reviewed the scientific evidence in the field of «Technology». Focused research questions were: (1) additive versus subtractive manufacturing of implant restorations; (2) survival, complications, and esthetics comparing prefabricated versus customized abutments; and (3) survival of posterior implant‐supported multi‐unit fixed dental prostheses.Materials and MethodsLiterature was systematically screened, and 67 publications could be critically reviewed following PRISMA guidelines, resulting in three systematic reviews. Consensus statements were presented to the plenary where after modification, those were accepted.ResultsAdditively fabricated implant restorations of zirconia and polymers were investigated for marginal/internal adaptation and mechanical properties without clear results in favor of one technology or material. Titanium base abutments for screw‐retained implant single crowns compared to customized abutments did not show significant differences concerning 1‐year survival. PFM, veneered and monolithic zirconia implant‐supported multi‐unit posterior fixed dental prostheses demonstrated similar high 3‐year survival rates, whereas veneered restorations exhibited the highest annual ceramic fracture and chipping rates.ConclusionsFor interim tooth‐colored implant single crowns both additive and subtractive manufacturing are viable techniques. The clinical performance of additively produced restorations remains to be investigated. Implant single crowns on titanium base abutments show similar clinical performance compared to other type of abutments; however, long‐term clinical data from RCTs are needed. The abutment selection should be considered already during the planning phase. Digital planning facilitates 3D visualization of the prosthetic design including abutment selection. In the posterior area, monolithic zirconia is recommended as the material of choice for multi‐unit implant restorations to reduce technical complications

On the Dynamical Overstability of Radiative Blast Waves: The Atomic Physics of Shock Stability

Atomic physics calculations of radiative cooling are used to calculate criteria for the overstability of radiating shocks. Our calculations explain the measurement of shock overstability by Grun et al. and explain why the overstability was not observed in other experiments. The methodology described here can be especially useful in astrophysical situations where the relevant properties leading to an overstability can be measured spectroscopically, but the effective adiabatic index is harder to determine.Comment: 11 pages including 3 figures, accepted for publication in Physical Review Letter

Stable isotope analysis provides new information on winter habitat use of declining avian migrants that is relevant to their conservation

Winter habitat use and the magnitude of migratory connectivity are important parameters when assessing drivers of the marked declines in avian migrants. Such information is unavailable for most species. We use a stable isotope approach to assess these factors for three declining African-Eurasian migrants whose winter ecology is poorly known: wood warbler Phylloscopus sibilatrix, house martin Delichon urbicum and common swift Apus apus. Spatially segregated breeding wood warbler populations (sampled across a 800 km transect), house martins and common swifts (sampled across a 3,500 km transect) exhibited statistically identical intra-specific carbon and nitrogen isotope ratios in winter grown feathers. Such patterns are compatible with a high degree of migratory connectivity, but could arise if species use isotopically similar resources at different locations. Wood warbler carbon isotope ratios are more depleted than typical for African-Eurasian migrants and are compatible with use of moist lowland forest. The very limited variance in these ratios indicates specialisation on isotopically restricted resources, which may drive the similarity in wood warbler populations' stable isotope ratios and increase susceptibility to environmental change within its wintering grounds. House martins were previously considered to primarily use moist montane forest during the winter, but this seems unlikely given the enriched nature of their carbon isotope ratios. House martins use a narrower isotopic range of resources than the common swift, indicative of increased specialisation or a relatively limited wintering range; both factors could increase house martins' vulnerability to environmental change. The marked variance in isotope ratios within each common swift population contributes to the lack of population specific signatures and indicates that the species is less vulnerable to environmental change in sub-Saharan Africa than our other focal species. Our findings demonstrate how stable isotope research can contribute to understanding avian migrants' winter ecology and conservation status

X-ray two-photon absorption with high fluence XFEL pulses

We report on nonlinear interaction of solid Fe with intense femtosecond hard x-ray free-electron laser (XFEL) pulses. The experiment was performed at the CXI end- station of the Linac Coherent Light Source (LCLS) by means of high- resolution x-ray emission spectroscopy. The focused x-ray beam provided extreme fluence of ~10⁵ photons/Ų. Two-photon absorption leading to K-shell hollow atom formation and to single K-shell ionization of solid Fe was investigated