X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accel...

Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as f...

Cooperative diversity methods have recently been advocated for ad hoc sensor networks, and for other mobile wireless applications as well, as a means of providing diversity against link fading, and thereby offering lower power operation, or better system coverage. Sendonaris et al [1] proposed the concept of cooperative diversity, also known as distributed space-time transmission, and subsequen...

In this paper, I study the production of consonant clusters by Greek children and examine the consequences of the acquisition data for phonological theory, with particular emphasis on the word initial position. Using a non-word repetition test, I tested the order of acquisition of word initial and word medial sT, TT and TR clusters in 59 children. The results provide evidence against any analys...

Fine time-resolved analysis of matter - i.e. spectroscopy and photon scattering in the linear response regime requires a fs-scale pulsed, high repetition rate, fully coherent X-ray source. A seeded Free-Electron Laser (FEL) driven by Super-Conducting Linac, generating $10^{8}$-$10^{10}$ photons at 2-5 keV with abou 0.5 MHz can address this need. The seeding scheme proposed is Echo-Enabled Harmo...

In modern broadband wireless access systems such as mobile worldwide interoperability for microwave access (WiMAX) and others, repetition coding is recommended for the lowest modulation level, in addition to the mandatory concatenated Reed-Solomon and convolutional code data coding, to protect vital control information from deep fades. This paper considers repetition coding as a time-diversity ...

We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope effic...

In this paper a new cooperative transmission scheme is proposed that enjoys some important advantages over similar protocols First it achieves cooperative diversity without relying on orthogonal subspaces e g di erent spreading codes or frequency bands allowing full rate transmission Second its performance degrades gracefully as the path loss between cooperating partners increases never falling...