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 authors present a review of the advances that have been made to establish terahertz applications in the cultural heritage conservation sector over the last several years. This includes material spectroscopy, 2D and 3D imaging and tomographic studies, using a broad range of terahertz sources demonstrating the breadth and application of this burgeoning community.

A Survey of Terahertz Applications in Cultural Heritage Conservation Science

Terahertz imaging for non-destructive evaluation of mural paintings

1000 times expansion/compression of optical pulses for chirped pulse amplification

We report on the recent advances of an electrooptic sampling technique for the characterization of electrical transients that has now achieved an unprecedented temporal resolution of less than 1 ps. Voltage sensitivity is on the order of 50 μV. A lithium tantalate traveling wave Pockels cell is employed in conjunction with a high repetition rate subpicosecond laser system.

Subpicosecond electrical sampling

Phase transformation in condensed matter is an important area of study in solid state physics since it relates to the genesis and evolution of new microstructure. The mechanisms responsible in such critical phenomena are still not fully understood. Previous experimental information has left unmeasured such important parameters as the minimum number of nuclei and their common critical radius for a transformation to occur as well as the interphase velocity. Several probe techniques have now been developed to time-resolve phase transformations in semiconductors during laser annealing. However, most of these probes (eg. electrical conductivity,1,2 optical reflection,3,4 optical transmission,5 Raman scattering,6 and time of flight mass spectrometry7) supply no direct information about the atomic structure of the material. Probing the structure can reveal when and to what degree a system melts as it is defined by degradation in the long range order of the lattice. True structural probes based on x-ray8 and low energy electron9 diffraction and EXAFS10 with nanosecond time resolution have been developed offering fresh insight into both the bulk and surface dynamics of material structure. Also, a subpicosecond probe based on structural dependent second harmonic generation11 has been demonstrated. But at present, only the technique of picosecond electron diffraction12 can produce an unambiguous picture of the structure on the picosecond timescale. In this letter we report on the results of using this probe to directly observe the laser-induced melting of aluminum.

Gerard Mourou

Papers

A Survey of Terahertz Applications in Cultural Heritage Conservation Science

Terahertz imaging for non-destructive evaluation of mural paintings

1000 times expansion/compression of optical pulses for chirped pulse amplification

Subpicosecond electrical sampling

Time-Resolved Laser-Induced Phase Transformation in Aluminum