Measured Emittance Dependence on the Injection Method in Laser Plasma Accelerators.

Single-shot, charge-dependent emittance measurements of electron beams generated by a laser plasma accelerator (LPA) reveal that shock-induced density down-ramp injection produces beams with normalized emittances a factor of 2 smaller than beams produced via ionization injection. Such a comparison is made possible by the tunable LPA setup, which allows electron beams with nearly identical central energy and peak spectral charge density to be produced using the two distinct injection mechanisms. Parametric measurements of this type are essential for the development of LPA-based applications which ultimately require high charge density and low emittance.

Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV.

Laser-plasma accelerators of only a centimetre's length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.

Review of risk factors in four cases of cryptococcosis after heart transplantation.

Cryptococcosis is a rare infection with high mortality in patients who have undergone heart transplantation (HT). In this study, we report four cases of the disease selected from our 328 HT cases (1.22%) between 1987 and 2007. The purpose of this study was to review risk factors for cryptococcosis after HT. Three of the four patients were men. The mean time from HT to diagnosis was 8.5 months (range, 3-17 months). Cryptococcosis was subcutaneous in one patient, systemic in one, and meningeal in two. One patient died. The Antifungal regimens included intravenous amphotericin B (amBisone) and oral fluconazole (Diflucan). Patients with diabetes mellitus or renal insufficiency, are hepatitis B carriers, have undergone repeat HT, or are receivings steroid therapy are susceptible to cryptococcosis. The recommend anticryptococcal therapy is amphotericin B, followed by oral fluconazole for at least 6 months. Early diagnosis with aggressive diagnostic techniques and a combination of therapies must be considered to reduce the risk of death in HT recipients with cryptococcosis.

Heart transplantation using bicaval anastomosis to concomitantly relieve superior vena caval obstruction in a pediatric patient with heart failure.

We describe a case of complex congenital heart disease treated using balloon septostomy, pulmonary artery banding. Blalock-Taussig shunt, and cardiac resynchronization therapy; however, heart failure developed. A bicaval anastomosis was used to relieve superior vena cava (SVC) obstruction despite possible anastomotic stenosis. The postoperative course was uneventful and the patient recovered rapidly. Thus, we recommend bicaval anastomosis using a longer donor SVC concomitantly performed during heart transplantation to relieve both heart failure and SVC obstruction in pediatric patients.

Characterization and control of plasma density distribution for the development of solid-target x-ray lasers.

By using deflectometry of a longitudinal probe pulse and reflective interferometry of a transverse probe pulse to resolve the spatiotemporal distribution of the preformed plasma, we characterize and control the plasma density distribution near the target surface for the development of solid-target x-ray lasers. We show that the use of prepulses in an ignitor-heater scheme can increase the scale length of the preformed plasma and how the effect varies with target materials. Many important issues crucial to x-ray lasing such as electron density distribution, electron temperature, and the optimal timing between pumping pulses can be resolved with these methods.

Control of laser-beam propagation and absorption in a nanoplasma gas by programming of a transient complex refractive index with a prepulse.

By utilizing the intensity- and duration-dependent heating and expansion rate of nanoplasma to generate a transient transverse gradient of the refractive index, prepulse controlled laser-beam propagation is demonstrated. The dynamical response of the macroscopic optical refractive index is traced back to the microscopic polarizability of nanoplasmas experimentally, in accordance with hydrodynamic nanoplasma models. In particular, the delay between the prepulse and the main pulse for maximum Rayleigh scattering is found to be longer than that for maximum x-ray emission, supporting the more refined one-dimensional self-consistent hydrodynamic nanoplasma model.