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

We demonstrated a Yb:glass laser directly side-pumped by two 20-W diode bars with negligible thermal effects. The experimental setup has two cw 20-W, l-cm InGaAs laser-diode bars from Thomson-CSF, France, which were combined together by using a polarizer and a halfwave plate.

Directly diode-pumped Yb:glass laser with 2.8-W cw output power

Summary form only given. It has been observed that isotopic enrichment of light ions occurs in the central portion of laser ablation plumes when such plasmas are formed with ultrafast laser pulses. It was found that the separation of lighter isotopes from heavier isotopes occurs on axis in the expanding plasma plume. The relative independence of the enrichment on axis among different elements and other similarities in the ion distributions have indicated a universality to this effect that lends credence to a possible plasma centrifuge model. In the present work, we examine the angular distribution of isotope enrichments and investigate the dependence on laser parameters and on the atomic-transport mean free path between collisions. The angular dependence is studied as a function of ion energy, ion charge state, and atomic mass.

Angular dependence of isotope enrichment in ultrafast laser ablation plumes

A first set of computational studies of transmutation of spent nuclear fuel using compact tunable 14 MeV D-T fusion driven neutron sources is presenter. Where we study the controllability, time evolution, as well as effects of spatial distribution of the neutronics in the transmutation in the subcritical operations regime of a transmutator, in which our neutron sources are small, distributed, and can be monitored. Source neutrons are generated via beam-target fusion whereas a deuteron beam is created by laser irradiation of nanometric foils, through the Coherent Acceleration of Ions by Laser (CAIL) process, onto a tritium soaked target. This can be accomplished using relatively cheap fiber lasers terminating onto small scale targets which makes possible the use of multiple tunable and distributable neutron sources. This source is then combined with a molten salt core whose liquid state allows: homogeneity by mixing, safety, in-situ processing, and monitoring. Such a source and molten salt combination allows for the introduction of rapid feedback or feedforward control of the system's operation that have not previously been considered. This encourages an investigation with the aid of AI into new spatial and operation control strategies as done here.

Fusion Driven Transmutation of Transuranics in a Molten Salt

A 100-ps-resolution electron pulse was used to study a 25-nm thick gold single crystal irradiated by a synchronized infrared optical pulse. The change in electron diffraction intensity following laser heating (the Debye-Waller effect) was measured as a function of delay time. The relaxation of a crystal lattice distortion in the surface region appears to explain an observed oscillation in time of the scattered electron intensity. This novel technique provides a sensitive structure probe for short-time dynamics and is, we believe, the fastest lattice temperature probe.

Subnanosecond Time-Resolved Electron Diffraction from Thin Crystalline Gold Films

Compact solid-state laser sources based on “Chirped Pulse Amplification” are capable of generating intensities in excess of 1018 W/cm2 and make possible the investigation of a new class of relativistic experiments in a physical regime previously inaccessible.

Gerard Mourou

Papers

Directly diode-pumped Yb:glass laser with 2.8-W cw output power

Angular dependence of isotope enrichment in ultrafast laser ablation plumes

Fusion Driven Transmutation of Transuranics in a Molten Salt

Subnanosecond Time-Resolved Electron Diffraction from Thin Crystalline Gold Films

Ultrahigh Peak Power Generation: Present and Future