237 research outputs found
Lasing at the band edges of plasmonic lattices
We report room temperature lasing in two-dimensional diffractive lattices of
silver and gold plasmon particle arrays embedded in a dye-doped polymer that
acts both as waveguide and gain medium. As compared to conventional dielectric
distributed feedback lasers, a central question is how the underlying band
structure from which lasing emerges is modified by both the much stronger
scattering and the disadvantageous loss of metal. We use spectrally resolved
back-focal plane imaging to measure the wavelength- and angle dependence of
emission below and above threshold, thereby mapping the band structure. We find
that for silver particles, the band structure is strongly modified compared to
dielectric reference DFB lasers, since the strong scattering gives large stop
gaps. In contrast, gold particles scatter weakly and absorb strongly, so that
thresholds are higher, but the band structure is not strongly modified. The
experimental findings are supported by finite element and fourier modal method
calculations of the single particle scattering strength and lattice extinction.Comment: 10 pages, 8 figure
Electron Cloud Mitigation by Fast Bunch Compression in the CERN PS
A fast transverse instability has been observed with nominal LHC beams in the CERN Proton Synchrotron (PS) in 2006. The instability develops within less than 1 ms, starting when the bunch length decreases below a threshold of 11.5 ns during the RF procedure to shorten the bunches immediately prior to extraction. An alternative longitudinal beam manipulation, double bunch rotation, has been proposed to compress the bunches from 14 ns to the 4 ns required at extraction within 0.9 ms, saving some 4.5 ms with respect to the present compression scheme. The resultant bunch length is found to be equivalent for both schemes. In addition, electron cloud and vacuum measurements confirm that the development of an electron cloud and the onset of an associated fast pressure rise are delayed with the new compression scheme. Beam dynamics simulations and measurements of the double bunch rotation are presented as well as evidence for its beneficial effect from the electron cloud standpoint
Proposal for a Cavity Phase Observation System in the PS Machine
In multi-cavity synchrotrons it is essential to be able to measure the phase difference between RF cavities. Errors in relative phase can have a particularly deleterious effect on the beam during RF gymnastics. Currently, two methods are available to measure the relative phase in the CERN Proton Synchrotron (PS), but neither attains the desired resolution nor covers the full arsenal of cavities. This note describes a system that will measure the relative phase between cavities with high resolution. The system makes use of the digital hardware deployed in the LEIR beam control and of the corresponding DSP and FPGA signal processing. The focus is on beams controlled by the Multi Harmonic Source (MHS) clock. The system described here is also a step towards the deployment of a new generation of digital beam control systems for the PS Complex machines, within the framework of the LHC injector consolidation and following the successful commissioning of the LEIR digital beam control system. Some expected benefits are briefly summarised at the end of this documen
Rapportage Voorkomen Terugval Utrecht:Tweede meting van vijfjarig onderzoek naar recidive dakloosheid in Utrecht, meting 2020
Rapportage Voorkomen Terugval Utrecht:Tweede meting van vijfjarig onderzoek naar recidive dakloosheid in Utrecht, meting 2020
Survival Differences in Pediatric Pulmonary Arterial Hypertension Clues to a Better Understanding of Outcome and Optimal Treatment Strategies
ObjectivesIn order to describe survival and treatment strategies in pediatric pulmonary arterial hypertension (PAH) in the current era of PAH-targeted drugs and to identify predictors of outcome, we studied uniformly defined contemporary patient cohorts at 3 major referral centers for pediatric PAH (New York [NY], Denver, and the Netherlands [NL]).BackgroundIn pediatric PAH, discrepancies exist in reported survival rates between North American and European patient cohorts, and robust data for long-term treatment effects are lacking.MethodsAccording to uniform inclusion criteria, 275 recently diagnosed consecutive pediatric PAH patients who visited the 3 referral centers between 2000 and 2010 were included.ResultsUnadjusted survival rates differed between the center cohorts (1-, 3-, and 5-year transplantation-free survival rates: 100%, 96%, and 90% for NY; 95%, 87%, and 78% for Denver; and 84%, 71%, and 62% for NL, respectively; p < 0.001). Based on World Health Organization (WHO) functional class and hemodynamic parameters, disease severity at diagnosis differed between the center cohorts. Adjustment for diagnosis, WHO functional class, indexed pulmonary vascular resistance, and pulmonary-to-systemic arterial pressure ratio resolved the observed survival differences. Treatment with PAH-targeted dual and triple therapy during the study period was associated with better survival than treatment with PAH-targeted monotherapy.ConclusionsSurvival rates of pediatric PAH patients differed between 3 major referral centers. This could be explained by differences between the center cohorts in patients’ diagnoses and measures of disease severity, which were identified as important predictors of outcome. In this study, treatment with PAH-targeted combination therapy during the study period was independently associated with improved survival
Perturbation of microbiota in one-day old broiler chickens with antibiotic for 24 hours negatively affects intestinal immune development
CERN SPS Impedance in 2007
Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In parallel, after the extensive and successful campaign of identification, classification and cure of the possible sources of (mainly longitudinal) impedance between 1998 and 2001, a new campaign (essentially for the transverse impedance this time) has started few years ago, in view of the operation of the SPS with higher intensity for the LHC luminosity upgrade. The present paper summarizes the results obtained from the measurements performed over the last few years and compares them to our predictions. In particular, it reveals that the longitudinal impedance is reasonably well understood and the main contributors have already been identified. However, the situation is quite different in the transverse plane: albeit the relative evolution of the transverse impedance over the last few years can be well explained by the introduction of the nine MKE kickers necessary for beam extraction towards the LHC, significant contributors to the SPS transverse impedance have not been identified yet
Re-integratie in BOLD Cities: Wat zijn de kansen, risico’s en (on)mogelijkheden in het gebruik van big data om de effectiviteit en kwaliteit van gemeentelijke re-integratie te verbeteren? [Eindrapportage]
Hervorming Sociale Regelgevin
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