Results of an RF Pulsed Heating Experiment at SLAC

Results are reported from an experiment on RF pulsed heating of copper at SLAC. Damage in the form of cracks may be induced on the surface after the application of many pulses of RF. The experiment consists of two circularly cylindrical cavities operated in the TE011 mode at a resonant frequency of 11.424 GHz. Each cavity received 8.5 MW, 1.2 microsecond pulses at 60 Hz corresponding to a calculated temperature rise of 120 K on the copper surface. After 5.5 x 10^7 pulses, the experiment was stopped and the copper surfaces were examined. Damage is present on the area of the surface where the maximum heating occurred.Comment: 3 pages, 7 figures, Presented at LINAC 2000 conference, Paper ID THA1

Photonic Crystal Laser Accelerator Structures

Photonic crystals have great potential for use as laser-driven accelerator structures. A photonic crystal is a dielectric structure arranged in a periodic geometry. Like a crystalline solid with its electronic band structure, the modes of a photonic crystal lie in a set of allowed photonic bands. Similarly, it is possible for a photonic crystal to exhibit one or more photonic band gaps, with frequencies in the gap unable to propagate in the crystal. Thus photonic crystals can confine an optical mode in an all-dielectric structure, eliminating the need for metals and their characteristic losses at optical frequencies. We discuss several geometries of photonic crystal accelerator structures. Photonic crystal fibers (PCFs) are optical fibers which can confine a speed-of-light optical mode in vacuum. Planar structures, both two- and three-dimensional, can also confine such a mode, and have the additional advantage that they can be manufactured using common microfabrication techniques such as those used for integrated circuits. This allows for a variety of possible materials, so that dielectrics with desirable optical and radiation-hardness properties can be chosen. We discuss examples of simulated photonic crystal structures to demonstrate the scaling laws and trade-offs involved, and touch on potential fabrication processes.Comment: 3 pages, 3 figures; Submitted to Particale Accelerator Conference (PAC 2003), May 12-16, 2003, Portland, Oregon (IEEE

Ein in Deklinations- und Inklinationsrichtung kompensiertes Rubidium-Magnetometer

Es wird ein Variometer beschrieben, mit dem sich Änderungen des erdmagnetisehen Feldes in der Totalintensität F, der Deklination D und der Inklination I mit einer Empfindlichkeit und Langzeitkonstanz von 0,1 [gamma] digital und analog aufzeichnen lassen. Das Gerät enthält ein Rubidium-Magnetometer, das in Verbindung mit Zusatzfeldern und Regelkreisen Vektormessungen liefert

Full aircraft ditching simulation by advanced fluid-structure interaction computational methods: a comparative analysis

International audienceMost of air traffic operates over water, airports are mostly located around water, and near-airport operations (such takeoff, final approach, and landing) take place above water. Fortunately emergency landings on water, comprising ditching and crash on water, do not occur frequently. However, as passenger safety under dynamic loads is of key importance in modern aerospace vehicle design, ditching analysis is an important part of the aircraft design. The landing of an airplane on water is an emergency situation that an aircraft faces only once. Loss of the aircraft is acceptable, provided the crew and passengers can safely escape and be rescued. For a water contact to qualify as a ditching, it is necessary that the touchdown follows a prudent approach and acceptable procedures. The design must provide structural integrity to protect all occupants, ensure that no excessive decelerations will be experienced by the occupants, and provide sufficient time for safe egress from a damaged aircraft (FAR 25.801 on Ditching)

DIELECTRIC BRAGG ACCELERATOR

Abstract It is demonstrated that a planar Bragg reflection waveguide consisting of a series of dielectric layers may form an acceleration structure. It is shown that an interaction impedance per wavelength of over 100Ω is feasible with existing materials, Silica (ε = 2.1) and Zirconia (ε = 4), and if materials of high dielectric coefficient become available in the future, they may facilitate an interaction impedance per wavelength closer to 500Ω

Sequence dependent antitumour efficacy of the vascular disrupting agent ZD6126 in combination with paclitaxel

The clinical success of small-molecule vascular disrupting agents (VDAs) depends on their combination with conventional therapies. Scheduling and sequencing remain key issues in the design of VDA–chemotherapy combination treatments. This study examined the antitumour activity of ZD6126, a microtubule destabilising VDA, in combination with paclitaxel (PTX), a microtubule-stabilising cytotoxic drug, and the influence of schedule and sequence on the efficacy of the combination. Nude mice bearing MDA-MB-435 xenografts received weekly cycles of ZD6126 (200 mg kg−1 i.p.) administered at different times before or after PTX (10, 20, and 40 mg kg−1 i.v.). ZD6126 given 2 or 24 h after PTX showed no significant benefit, a result that was attributed to a protective effect of PTX against ZD6126-induced vascular damage and tumour necrosis, a hallmark of VDA activity. Paclitaxel counteracting activity was reduced by distancing drug administrations, and ZD6126 given 72 h after PTX potentiated the VDA's antitumour activity. Schedules with ZD6126 given before PTX improved therapeutic activity, which was paralleled by a VDA-induced increase in cell proliferation in the viable tumour tissue. Paclitaxel given 72 h after ZD6126 yielded the best response (50% tumours regressing). A single treatment with ZD6126 followed by weekly administration of PTX was sufficient to achieve a similar response (57% remissions). These findings show that schedule, sequence and timing are crucial in determining the antitumour efficacy of PTX in combination with ZD6126. Induction of tumour necrosis and increased proliferation in the remaining viable tumour tissue could be exploited as readouts to optimise schedules and maximise therapeutic efficacy

Vascular disrupting agent for neovascular age related macular degeneration: a pilot study of the safety and efficacy of intravenous combretastatin A-4 phosphate

BACKGROUND: This study was designed to assess the safety, tolerability, and efficacy of intravenous infusion of CA4P in patients with neovascular age-related macular degeneration (AMD). METHODS: Prospective, interventional, dose-escalation clinical trial. Eight patients with neovascular AMD refractory to at least 2 sessions of photodynamic therapy received CA4P at a dose of 27 or 36 mg/m2 as weekly intravenous infusion for 4 consecutive weeks. Safety was monitored by vital signs, ocular and physical examinations, electrocardiogram, routine laboratory tests, and collection of adverse events. Efficacy was assessed using retinal fluorescein angiography, optical coherence tomography, and best corrected visual acuity (BCVA). RESULTS: The most common adverse events were elevated blood pressure (46.7%), QTc prolongation (23.3%), elevated temperature (13.3%), and headache (10%), followed by nausea and eye injection (6.7%). There were no adverse events that were considered severe in intensity and none resulted in discontinuation of treatment. There was reduction of the excess foveal thickness by 24.15% at end of treatment period and by 43.75% at end of the two-month follow-up (p = 0.674 and 0.161, respectively). BCVA remained stable throughout the treatment and follow-up periods. CONCLUSIONS: The safety profile of intravenous CA4P was consistent with that reported in oncology trials of CA4P and with the class effects of vascular disruptive agents; however, the frequency of adverse events was different. There are evidences to suggest potential efficacy of CA4P in neovascular AMD. However, the level of systemic safety and efficacy indicates that systemic CA4P may not be suitable as an alternative monotherapy to current standard-of-care therapy