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.

/pdf/a-roadmap-for-graphene-1nstzmbk5x.pdf

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

Theoretical investigation of second harmonic generation (SHG) of super intense femtosecond radiation demonstrated that temporal Intensity Contrast Ratio (ICR) of output radiation of petawatt level laser complexes can be significantly increased. The cubic polarization effects in the process give possibility of additional pulse compression. We present experimental results of SHG of radiation with average intensity 2TW/cm 2 in 0.6mm KDP crystal. Theoretical model of linear regime of plane wave instability in mediums with quadratic and cubic nonlinearity is developed and thoroughly discussed. Analysis of small-scale self-focusing suppression methodic is presented. The influence of surface dust to spatial noises generation in SHG process is pointed out.

Temporal intensity contrast ratio enhancement of petawatt level laser pulses based on second harmonic generation

In order to effectively exploit the extreme speed and sensitivity potential of both the electro-optic and superconducting technologies, proper generation, coupling, and propagation of signals with bandwidths in excess of 100 Gigahertz is required. In this report we present results of an experimental investigation, supported by theoretical predictions, on a transmission structure which satisfies the ultra wide bandwidth requirements. The experiments, which incorporated a new variation of an electro optical sampling technique [1], investigated the generation of picosecond electrical pulses, an impedance matching tapered coupling configuration, and the propagation of the pulses down the transmission line. The technique allows the measurement of the waveforms at any point along the transmission line while minimizing dispersional effects associated with the sampling. This resulted in an accurate determination of pulse degradation, i.e., step response, per unit length of transmission line. The investigation supports the conclusion that transmission lines and connectors capable of supporting bandwidths in excess of 100 Gigahertz, while allowing relatively dispersionless propagation over distances exceeding a centimeter, are realizable.

Transmission Line Designs With a Measured Step Response of 3 ps Per Centimeter

Second-order autocorrelation of ultrashort laser pulses by using two-photon-induced photocurrent in semiconductors offers several advantages compared with baditionally employed combination o f a second harmonic (SH) c y t a l and B photomultiplier tube. A low-priced commercially available photodiode [I] sllows to overcome principal drawback of SH-based amcomelation: limited phaos matching bandwidth and wavelength.dependent sensitivity o f the light detector leading to B spectral filtering effect, pulse brmdening due to crystal bulk dispersion, low conversion efficiency which decrease9 with increase o f SH bandwidth, high cost and manufacturing problems associated with thin SH crystals. A siaificant advantage o f incorporating a semiconductor photodiode into autocorrel&tioa measurements i E that the desired two-photon reoponre and ihe transformation of light into electric current are combined into a single nolid-stste device. I t has been shown recently that for the vast majority of practically realisable pulses the complete phase and amplitude information could be rapidly recovered fmm the autocorrelation trace and the pulse spectrum by means of a two-stage iteratiw algorithm [Z]. In this convihurion we demonstrate that due to absence of spectrsl filtering effect and high dynamic range of quadratic response to the incident intensity in a GaAsP photodiode [I], correct retrieval of temporal profile and phase from autocorrelation and spectrum c m be achieved for ultrashort l a w pulses with bandwidths as large BS 130 nm and pulse energies as IOW BS

http://ieeexplore.ieee.org/iel5/5829/15540/00718869.pdf

Wave-Front Correction of Femtosecond TeraWatt Laser Using a Deformable Mirrors

High average power chirped pulse amplification systems

We analyze the interactions of super‐strong laser fields with an electron and with plasma electrons. An efficient conversion of incident radiation to γ‐ray emission is predicted by numerical simulations for intensities of ∼1022 W/cm2, recently achieved in experiments. At larger intensities the emission from counter‐propagating electrons is modified by the effects of Quantum ElectroDynamics (QED), as long as the electron energy is sufficiently high: e≥1 GeV. The radiation force experienced by an electron is for the first time derived from QED principles and its applicability range is extended towards QED‐strong fields.

Gerard Mourou

Papers

Temporal intensity contrast ratio enhancement of petawatt level laser pulses based on second harmonic generation

Transmission Line Designs With a Measured Step Response of 3 ps Per Centimeter

Wave-Front Correction of Femtosecond TeraWatt Laser Using a Deformable Mirrors

High average power chirped pulse amplification systems

Radiation back-reaction in relativistically strong and QED-strong pulsed laser fields