76 resultados para 1995_12201025 Optics-21


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Some 8000 images obtained with the Solar Eclipse Coronal Imaging System (SECIS) fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analysed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white-light and Fe xiv green-line (5303 ) channels over 205 seconds (frame rate 39 s(-1)), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than those that we obtained during the 11 August 1999 total eclipse (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyse the emission at 29 518 locations, of which 10 714 had emission at reasonably high levels, searching for periodic fluctuations with periods in the range 0.1 -aEuro parts per thousand 17 seconds (frequencies 0.06 -aEuro parts per thousand 10 Hz). While a number of possible periodicities were apparent in the wavelet analysis, none of the spatially and time-limited periodicities in the local brightness curves was found to be physically important. This implies that the pervasive Alfv,n wave-like phenomena (Tomczyk et al.: Science 317, 1192, 2007) using polarimetric observations with the Coronal Multi-Channel Polarimeter (CoMP) instrument do not give rise to significant oscillatory intensity fluctuations.

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Background
Restorative justice is “a process whereby parties with a stake in a specific offence resolve collectively how to deal with the aftermath of the offence and its implications for the future” (Marshall 2003). Despite the increasing use of restorative justice programmes as an alternative to court proceedings, no systematic review has been undertaken of the available evidence on the effectiveness of these programmes with young offenders. Recidivism in young offenders is a particularly worrying problem, as recent surveys have indicated
the frequency of re-offences for young offenders has ranged from 40.2% in 2000 to 37.8% in 2007 (Ministry of Justice 2009)

Objectives
To evaluate the effects of restorative justice conferencing programmes for reducing recidivism in young offenders.

Search methods
We searched the following databases up to May 2012: CENTRAL, 2012 Issue 5, MEDLINE (1978 to current), Bibliography of Nordic Criminology (1999 to current), Index to Theses (1716 to current), PsycINFO (1887 to current), Social Sciences Citation Index (1970 to current), Sociological Abstracts (1952 to current), Social Care Online (1985 to current), Restorative Justice Online (1975 to current), Scopus (1823 to current), Science Direct (1823 to current), LILACS (1982 to current), ERIC (1966 to current), Restorative Justice Online (4May 2012),WorldCat (9May 2012), ClinicalTrials.gov (19May 2012) and ICTRP (19May 2012). ASSIA,National Criminal Justice Reference Service and Social Services Abstracts were searched up to May 2011. Relevant bibliographies, conference programmes and journals were also searched.

Selection criteria
Randomised controlled trials (RCTs) or quasi-RCTs of restorative justice conferencing versus management as usual, in young offenders.

Data collection and analysis
Two authors independently assessed the risk of bias of included trials and extracted the data. Where necessary, original investigators were contacted to obtain missing information.

Main results
Four trials including a total of 1447 young offenders were included in the review. Results failed to find a significant effect for restorative justice conferencing over normal court procedures for any of the main analyses, including number re-arrested (odds ratio (OR) 1.00, 95% confidence interval (CI) 0.59 to 1.71; P = 0.99), monthly rate of reoffending (standardised mean difference (SMD) -0.06, 95% CI -0.28 to 0.16; P = 0.61), young person’s remorse following conference (OR 1.73, 95% CI 0.97 to 3.10; P = 0.06), young person’s recognition of wrongdoing following conference (OR 1.97, 95% CI 0.81 to 4.80; P = 0.14), young person’s self-perception following conference (OR 0.95, 95% CI 0.55 to 1.63; P = 0.85), young person’s satisfaction following conference (OR 0.42, 95% CI 0.04 to 4.07; P = 0.45) and victim’s satisfaction following conference (OR 4.05, 95%CI 0.56 to 29.04; P = 0.16). A small number of sensitivity analyses did indicate significant effects, although all are to be interpreted with caution.

Authors’ conclusions
There is currently a lack of high quality evidence regarding the effectiveness of restorative justice conferencing for young offenders. Caution is urged in interpreting the results of this review considering the small number of included studies, subsequent low power and high risk of bias. The effects may potentially be more evident for victims than offenders. The need for further research in this area is highlighted.

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Evidence of high gain pumped by recombination has been observed in the 5g-4f transition at 11.1 nn in sodiumlike copper ions with use of a 20-J 2-ps Nd:glass laser system. The time- and space-integrated gain coefficient was 8.8 +/- 1.4 cm(-1), indicating a single-transit amplification of similar to 60 times. This experiment has shown that 2 ps is the optimum pulse duration to drive the sodiumlike copper recombination x-ray lasing at 11.1 nm. (C) 1996 Optical Society of America

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A novel regime is proposed where, by employing linearly polarized laser pulses at intensities 10(21) W cm(-2) (2 orders of magnitude lower than discussed in previous work [T. Esirkepov et al., Phys. Rev. Lett. 92, 175003 (2004)]), ions are dominantly accelerated from ultrathin foils by the radiation pressure and have monoenergetic spectra. In this regime, ions accelerated from the hole-boring process quickly catch up with the ions accelerated by target normal sheath acceleration, and they then join in a single bunch, undergoing a hybrid light-sail-target normal sheath acceleration. Under an appropriate coupling condition between foil thickness, laser intensity, and pulse duration, laser radiation pressure can be dominant in this hybrid acceleration. Two-dimensional particle-in-cell simulations show that 1.26 GeV quasimonoenergetic C6+ beams are obtained by linearly polarized laser pulses at intensities of 10(21) W cm(-2).

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The R-matrix incorporating time (RMT) method is a method developed recently for solving the time-dependent Schrödinger equation for multielectron atomic systems exposed to intense short-pulse laser light. We have employed the RMT method to investigate the time delay in the photoemission of an electron liberated from a 2p orbital in a neon atom with respect to one released from a 2s orbital following absorption of an attosecond xuv pulse. Time delays due to xuv pulses in the range 76-105 eV are presented. For an xuv pulse at the experimentally relevant energy of 105.2 eV, we calculate the time delay to be 10.2±1.3 attoseconds (as), somewhat larger than estimated by other theoretical calculations, but still a factor of 2 smaller than experiment. We repeated the calculation for a photon energy of 89.8 eV with a larger basis set capable of modeling correlated-electron dynamics within the neon atom and the residual Ne ion. A time delay of 14.5±1.5 as was observed, compared to a 16.7±1.5 as result using a single-configuration representation of the residual Ne+ ion. 

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A compact differential 4-way power combiner with 2.3 dB loss and high common-mode rejection characteristic for use in mm-wave PAs is presented. A complete circuit comprised of a power splitter, two-stage cascode PA array, and a power combiner was implemented in SiGe technology. Measured small-signal gain of at least 17 dB was obtained from 74.5 GHz to 80.5 GHz with a peak 21 dB at 79 GHz. The prototype delivered 13.2 dBm P1dB and 14.3 dBm Psat when operated from a single 3.3 V supply at 75 GHz.