Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1  GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100 MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5  GeV while reducing the relative energy spread to <5% FWHM.

The authors conclude that in their 10-year experience, DBS has proven to be safe for the treatment of medically refractory movement disorders.

Abstract.A new generation of laser wakefield accelerators, supported by the extreme accelerating fields generated in the interaction of PW-Class lasers and underdense targets, promises the production of high quality electron beams in short distances for multiple applications. Achieving this goal will rely heavily on numerical modeling for further understanding of the underlying physics and identification of optimal regimes, but large scale modeling of these scenarios is computationally heavy and requires efficient use of state-of-the-art Petascale supercomputing systems. We discuss the main difficulties involved in running these simulations and the new developments implemented in the OSIRIS framework to address these issues, ranging from multi-dimensional dynamic load balancing and hybrid distributed / shared memory parallelism to the vectorization of the PIC algorithm. We present the results of the OASCR Joule Metric program on the issue of large scale modeling of LWFA, demonstrating speedups of over 1 order of magnitude on the same hardware. Finally, scalability to over ∼ 10 6 cores, and sustained performance over ∼ 2 PFlops is demonstrated, opening the way for large scale modeling of laser wakefield accelerator scenarios.

We present X-ray photoelectron spectroscopy, van der Pauw Hall mobilities, low-temperature far-infrared magneto transmission (FIR-MT), and atomic force microscopy (AFM) results from graphene films produced by radiative heating in an ultrahigh vacuum (UHV) chamber or produced by radio frequency (RF) furnace annealing in a high vacuum chemical vapor deposition system on Si- and C-face 4H SiC substrates at 1200-1600 degrees C. Although the vacuum level and heating methods are different, graphene films produced by the two methods are chemically similar with the RF furnace annealing typically producing thicker graphene films than UHV. We observe, however, that the formation of graphene on the two faces is different with the thicker graphene films on the C-face RF samples having higher mobility. The FIR-MT showed a 0(-1) --> 1(0) Landau level transition with a square root B dependence and a line width consistent with a Dirac fermion with a mobility >250,000 cm(2) x V(-1) x s(-1) at 4.2 K in a C-face RF sample having a Hall-effect carrier mobility of 425 cm(2) x V(-1) x s(-1) at 300 K. AFM shows that graphene grows continuously over the varying morphology of both Si and C-face substrates.

T ardive dyskinesia (TD), a hyperkinetic movement disorder causally related to dopamine receptorblocking drug (DRBD) exposure, is a well-recognized iatrogenic disorder in adults 1 and less commonly seen in children and infants. 2,3 Although the literature on TD mainly focuses on patients treated with DRBDs used as antipsychotics, DRBDs are also used to treat a wide array of medical, chiefly gastrointestinal, conditions. 4-6 Although most of the drugs that cause TD are DRBDs that antagonize dopamine D 2 receptors, other classes of drugs have the potential to cause TD, including antidepressants and calcium channel blockers. The reported lifetime prevalence of TD in patients treated with traditional DRBDs has varied greatly, with an average of about 25% of exposed adults. 1,7 Risk factors associated with the development of TD include advanced age, female gender, and, more important, total cumulative drug exposure. [8][9][10][11] We sought to determine which drugs most commonly cause TD in patients referred to our clinic. MATERIALS AND METHODSAfter approval by the institutional review board, a retrospective chart review of 583 charts was performed on patients evaluated for TD in the Parkinson's Disease and Movement Disorders Clinic at Baylor College of Medicine between 1981 and January 2006. We included all patients who met clinical criteria for TD 12 : (1) exhibited a hyperkinetic movement disorder, (2) had a documented exposure to 1 or more DRBDs for at least 3 months before the onset of symptoms, and (3) the hyperkinetic movement disorder persisted for at least 1 month after stopping the offending DRBD. 12 A total of 434 charts were used specifically for this study; 149 charts were excluded because of incorrect diagnostic coding, accidental destruction of charts, and loss to follow-up. We excluded patients with drug-induced parkinsonism. 13 All data related to demographics (age/gender), treatment indication (psychiatric/gastrointestinal/ other), phenomenology (stereotypy/dystonia/chorea/ tic/tremor), and offending agent were captured on case report forms and transferred to a database. RESULTSWe report data on 434 TD patients for whom we have detailed clinical information. Patients, of whom 334 were women (77.0%), had a mean age of 63.8 ± 14.8 years at their initial evaluation. Since its inception, 23 653 movement disorder patients have been evaluated at Baylor College of Medicine, 11 802 of whom were women (50.0%). There was no statistical difference in the proportion of women presenting with a psychiatric treatment indication when compared with those with a gastrointestinal disorder. The majority presented with oro-faciallingual stereotypy (n = 198, 45.6%), dystonia (n = 165, 38.0%), or other stereotypies (n = 159, 36.6%).