There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.

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A roadmap for graphene

QUANTUM gravitational effects are usually ignored in calculations of the formation and evolution of black holes. The justification for this is that the radius of curvature of space-time outside the event horizon is very large compared to the Planck length (Għ/c3)1/2 ≈ 10−33 cm, the length scale on which quantum fluctuations of the metric are expected to be of order unity. This means that the energy density of particles created by the gravitational field is small compared to the space-time curvature. Even though quantum effects may be small locally, they may still, however, add up to produce a significant effect over the lifetime of the Universe ≈ 1017 s which is very long compared to the Planck time ≈ 10−43 s. The purpose of this letter is to show that this indeed may be the case: it seems that any black hole will create and emit particles such as neutrinos or photons at just the rate that one would expect if the black hole was a body with a temperature of (κ/2π) (ħ/2k) ≈ 10−6 (M/M)K where κ is the surface gravity of the black hole1. As a black hole emits this thermal radiation one would expect it to lose mass. This in turn would increase the surface gravity and so increase the rate of emission. The black hole would therefore have a finite life of the order of 1071 (M/M)−3 s. For a black hole of solar mass this is much longer than the age of the Universe. There might, however, be much smaller black holes which were formed by fluctuations in the early Universe2. Any such black hole of mass less than 1015 g would have evaporated by now. Near the end of its life the rate of emission would be very high and about 1030 erg would be released in the last 0.1 s. This is a fairly small explosion by astronomical standards but it is equivalent to about 1 million 1 Mton hydrogen bombs. It is often said that nothing can escape from a black hole. But in 1974, Stephen Hawking realized that, owing to quantum effects, black holes should emit particles with a thermal distribution of energies — as if the black hole had a temperature inversely proportional to its mass. In addition to putting black-hole thermodynamics on a firmer footing, this discovery led Hawking to postulate 'black hole explosions', as primordial black holes end their lives in an accelerating release of energy.

Black Hole Explosions

Terahertz spectroscopy systems use far-infrared radiation to extract molecular spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules.

Materials for terahertz science and technology

The post-compression of high-energy Petawatt (PW) scale laser pulses offers the promise of maximizing the peak intensity deliverable by a given laser system for the amplified energy produced within the pulses. One recent proposal made by Mourou et al. relied upon the flat-top property of modern high-energy laser systems to suggest a solution utilizing self-phase modulation within a thin plastic film material to generate the bandwidth necessary to recompress to a shorter pulse duration through compensation with negative dispersion mirrors. The so-called thin film compressor (TFC) promised to offer an efficient and affordable method to boost the peak pulse achievable with existing facilities. Recent measurements including experiments done at the CETAL PW laser based at the National Institute for Lasers, Plasma, and Radiation Physics (INFLPR) in Magurele, Romania demonstrate the feasibility of the TFC configuration on a small-scale and encourage continued pursuit at increasing laser levels. The applications of such high energy, ultrashort pulses are already being considered in regard to particle acceleration and X-ray generation.

X-Rays Driven by Single-Cycle, Petawatt Lasers: A Path to Exawatt Pulses

Summary form only given. We present what is, to our best knowledge, the first Yb:KY(WO/sub 4/)/sub 2/ (Yb:KYW) regenerative amplifier. The 10-at.% Yb/sup 3+/-doped KY(WO/sub 4/)/sub 2/ crystal is 4-mm long and cut at Brewster angle for the E//b signal beam. The injection pulses originated from a directly diode-pumped Yb:glass saturable-absorber mode-locked oscillator. The mode-locked pulses stretched by a grating stretcher before being injected.

Directly diode-pumped Yb:KGW kHz regenerative amplifier

Particle-in-cell simulations reveal that strong attosecond electromagnetic pulses and dense attosecond electron bunches emerge synchronously from laser-plasma interaction in the relativistic lambda 3 regime. This provides a basis for relativistic attosecond optoelectronics

Attosecond Optoelectronics in the Relativistic &#955; 3 Regime

Summary form only given. We present, for the first time, chirped pulse amplification (CPA) in a directly diode pumped Yb:glass laser. The injected pulses were obtained from a mode-locked Ti:sapphire laser (coherent) tuned to 1040 nm with a pulse width of 200 fs. The pulses were then stretched in a fibre.

Directly diode-pumped Yb:glass regenerative chirped pulse amplifier

Summary form only given. An interaction of ultra-high intensity short laser pulses with underdense plasma is of considerable interest from the standpoint of basic physics and potential application for advanced inertial confinement fusion, X-ray lasers and particle accelerators. The ultra-high electromagnetic fields in the laser focus produce an extremely high pondermotive force that expels free electrons from the laser axis and relativistically modify the electron mass, plasma frequency and the plasma refractive index so that the plasma acts as a positive lens. If the laser pulse duration is long enough, the charge separation produces strong electrostatic field /spl sim/1 GV/cm that can accelerate ions to MeV energies. All these effects lead to a relativistic self-focusing and self-guiding of the laser beam that can further increase the laser intensity and maintain it over distances much longer than a Rayleigh range.

Gerard Mourou

Papers

X-Rays Driven by Single-Cycle, Petawatt Lasers: A Path to Exawatt Pulses

Directly diode-pumped Yb:KGW kHz regenerative amplifier

Attosecond Optoelectronics in the Relativistic λ 3 Regime

Directly diode-pumped Yb:glass regenerative chirped pulse amplifier

Electron cavitation and generation of MeV ions produced by relativistically self-guided laser pulse in He gas jet

Gerard Mourou

Papers

X-Rays Driven by Single-Cycle, Petawatt Lasers: A Path to Exawatt Pulses

Directly diode-pumped Yb:KGW kHz regenerative amplifier

Attosecond Optoelectronics in the Relativistic &#955; 3 Regime

Directly diode-pumped Yb:glass regenerative chirped pulse amplifier

Electron cavitation and generation of MeV ions produced by relativistically self-guided laser pulse in He gas jet

Attosecond Optoelectronics in the Relativistic λ 3 Regime