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Astronomia Astrofizyka

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Metodologia nauk, Matematyka, Filozofia, Miary i wagi, Pomiary

Substancje, reakcje, energia
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Antropologia kulturowa Socjologia Psychologia Zdrowie i medycyna

Przewidywania Kosmologia Religie Ideologia Polityka

Geologia, geofizyka, geochemia, środowisko przyrodnicze

Biologia, biologia molekularna i genetyka

Technologia cyberprzestrzeni, cyberkultura, media i komunikacja

Wiadomości | Gospodarka, biznes, zarządzanie, ekonomia

Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

Kolekcje IOP - REVIEWS


Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to
improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for
the conversion of solar energy to electricity are those exploiting the particle nature of light in
conventional photovoltaic cells, and those using the collective electromagnetic nature, where light
is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial
components. Examples include arrays of semiconductor nanostructures as an intermediate band (so
called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation,
or, in antenna–rectifier cells, nanomaterials for effective optical frequency rectification. Here,
we discuss the state of the art in p–n junction, intermediate band, multiple exciton generation, and
antenna–rectifier solar cells. We provide a summary of how engineered nanomaterials have been used
in these s... 2013/01/09 - 03:22

The assessment and management of risks associated with exposures to ionising radiation are defined
by the general radiological protection system, proposed by the International Commission on
Radiological Protection (ICRP). This system is regarded by a large majority of users as a robust
system although there are a number of dissenting voices, claiming that it is not suitable for
estimating the risks resulting from internal exposures. One of the specific issues of internal
exposure involves short-range radiations such as Auger and beta particles. Auger- and beta-emitting
radionuclides can be distributed preferentially in certain tissue structures and even in certain
cellular organelles, according to their chemical nature and the vector with which they are
associated. Given the limited range of the low-energy electrons in biological matter, this
heterogeneous distribution can generate highly localised energy depositions and exacerbate
radiotoxic responses at cellular level. These pa... 2013/01/08 - 07:08

In this review, we summarize our recent efforts in exploring the non-equilibrium potential and flux
landscape for dynamical systems and networks. The driving force of non-equilibrium dynamics can be
decomposed into the gradient of the non-equilibrium potential and the divergent free probability
flux divided by the steady-state probability distribution. The potential landscape is linked to the
probability distribution of the steady state. We found that the intrinsic potential landscape in the
zero noise limit is a Lyapunov function. We have defined and quantified the entropy, energy and free
energy of the non-equilibrium systems. These can be used for formulating the first law of
non-equilibrium thermodynamics. The free energy of the non-equilibrium system is also a Lyapunov
function. Therefore, we can use both the intrinsic potential landscape and the free energy to
quantify the robustness and global stability of the system. The Lyapunov property provides the
formulation for the ... 2012/12/22 - 12:34

Photodynamic therapy (PDT) has been developed as one of the most important therapeutic options in
the treatment of cancer and other diseases. By resorting to the photosensitizer and light, which
convert oxygen into cytotoxic reactive oxygen species (ROS), PDT will induce vascular damage and
direct tumor cell killing. Another consequence of PDT is the microvascular stasis, which results in
hypoxia and further produces tumor regression. To improve the treatment with PDT, three promising
strategies are currently attracting much interest: (1) the combination of PDT and anti-angiogenesis
agents, which more effectively prevent the proliferation of endothelial cells and the formation of
new blood vessels; (2) the nanoparticle-assisted delivery of photosensitizer, which makes the
photosensitizer more localized in tumor sites and thus renders minimal damage to the normal tissues;
(3) the application of intravascular PDT, which can avoid the loss of energy during the transmission
and expos... 2012/12/22 - 12:34

A review on the electronic properties, growth and functionalization of graphene on metals is
presented. Starting from the derivation of the electronic properties of an isolated graphene layer
using the nearest neighbor tight-binding (TB) approximation for π and σ electrons, the TB model is
then extended to third-nearest neighbors and interlayer coupling. The latter is relevant to
few-layer graphene and graphite. Next, the conditions under which epitaxial graphene can be obtained
by chemical vapor deposition are reviewed with a particular emphasis on the Ni(111) surface.
Regarding functionalization, I first discuss the intercalation of monolayer Au into the
graphene/Ni(111) interface, which renders graphene quasi-free-standing. The Au intercalated
quasi-free-standing graphene is then the basis for chemical functionalization. Functionalization of
graphene is classified into covalent, ionic and substitutional functionalization. As archetypical
examples for these three possibilities ... 2012/12/21 - 03:49

The coupled mechanical and Raman/infrared (IR) analysis of the (nano)structure and texture of
synthetic and natural polymer fibres (polyamides (PA66), polyethylene terephthalate (PET),
polypropylene (PP), poly(paraphenylene benzobisoxazole) (PBO), keratin/hair, Bombyx mori , Gonometa
rufobrunea/postica Antheraea/Tussah silkworms and Nephila Madagascarensis spider silks) is applied
so as to differentiate between crystalline and amorphous macromolecules. Bonding is very similar in
the two cases but a broader distribution of conformations is observed for the amorphous
macromolecules. These conclusions are then used to discuss the modifications induced by the
application of a tensile or compressive stress, including the effects of fatigue. Detailed attention
is paid to water and the inter-chain coupling for which the importance of hydrogen bonding is
reconsidered. The significant role of the ‘amorphous’ bonds/domains in the process of
fracture/fatigue is shown. 2012/12/19 - 10:45

Electrons from the Sun, often accelerated by magnetospheric processes, produce low-density plasmas
in the upper atmospheres of planets and their satellites. The secondary electrons can produce
further ionization, dissociation and excitation, leading to enhancement of chemical reactions and
light emission. Similar processes are driven by photoelectrons produced by sunlight in upper
atmospheres during daytime. Sunlight and solar electrons drive the same processes in the atmospheres
of comets. Thus for both understanding of planetary atmospheres and in predicting emissions for
comparison with remote observations it is necessary to simulate the processes that produce upper
atmosphere plasmas. In this review, we describe relevant models and their applications and address
the importance of electron-impact excitation cross sections, towards gaining a quantitative
understanding of the phenomena in question. 2012/12/19 - 10:45

This paper reviews recent developments in research in nanostructured permanent magnets (hard
magnetic materials) with emphasis on bottom-up approaches to fabrication of hard/soft nanocomposite
bulk magnets. Theoretical and experimental findings on the effects of soft phase and interface
conditions on interphase exchange interactions are given. Synthesis techniques for hard magnetic
nanoparticles, including chemical solution methods, surfactant-assisted ball milling and other
physical deposition methods are reviewed. Processing and magnetic properties of warm compacted and
plastically deformed bulk magnets with nanocrystalline morphology are discussed. Prospects of
producing bulk anisotropic hard/soft nanocomposite magnets are presented. 2012/12/14 - 23:11

We review recent developments and applications of the classification of the Weyl tensor in higher
dimensional Lorentzian geometries. First, we discuss the general setup, i.e. main definitions and
methods for the classification, some refinements and the generalized Newman–Penrose and
Geroch–Held–Penrose formalisms. Next, we summarize general results, such as a partial extension of
the Goldberg–Sachs theorem, characterization of spacetimes with vanishing (or constant) curvature
invariants and the peeling behaviour in asymptotically flat spacetimes. Finally, we discuss certain
invariantly defined families of metrics and their relation with the Weyl tensor classification,
including Kundt and Robinson–Trautman spacetimes; the Kerr–Schild ansatz in a constant-curvature
background; purely electric and purely magnetic spacetimes; direct and (some) warped products; and
geometries with certain symmetries. To conclude, some applications to quadratic gravity are also
overviewed. 2012/12/14 - 23:11

The classical dynamics of M -dimensional extended objects arising from stationary points of the
world volume swept out in space time is discussed from various points of view. A introduction to the
Hamiltonian mechanics of bosonic compact M(em)branes is given, emphasing the diversity of the
different formulations and gauge choices. For moving hypersurfaces, a graph description—including
its nonlinear realization of Lorentz invariance—and hydrodynamic formulations (in light-cone
coordinates as well as when choosing the time coordinate of a Lorentz observer as the dependent
variable) are presented. A matrix regularization for M = 2 (existing for all topologies) is
explained in detail for the 2-sphere, as well as multilinear formulations for M > 2. The recently
found dynamical symmetry that exists for all M and related reconstruction algebras are covered, just
as some explicit solutions of the level-set equations. 2012/12/13 - 23:55

Metabolism is built on a foundation of organic chemistry, and employs structures and interactions at
many scales. Despite these sources of complexity, metabolism also displays striking and robust
regularities in the forms of modularity and hierarchy, which may be described compactly in terms of
relatively few principles of composition. These regularities render metabolic architecture
comprehensible as a system, and also suggests the order in which layers of that system came into
existence. In addition metabolism also serves as a foundational layer in other hierarchies, up to at
least the levels of cellular integration including bioenergetics and molecular replication, and
trophic ecology. The recapitulation of patterns first seen in metabolism, in these higher levels,
motivates us to interpret metabolism as a source of causation or constraint on many forms of
organization in the biosphere. Many of the forms of modularity and hierarchy exhibited by metabolism
are readily interpret... 2012/12/12 - 23:27

Neutron stars are associated with diverse physical phenomena that take place in conditions
characterized by ultrahigh densities as well as intense gravitational, magnetic and radiation
fields. Understanding the properties and interactions of matter in these regimes remains one of the
challenges in compact object astrophysics. Photons emitted from the surfaces of neutron stars
provide direct probes of their structure, composition and magnetic fields. In this review, I discuss
in detail the physics that governs the properties of emission from the surfaces of neutron stars and
their various observational manifestations. I present the constraints on neutron star radii, core
and crust composition, and magnetic field strength and topology obtained from studies of their
broadband spectra, evolution of thermal luminosity, and the profiles of pulsations that originate on
their surfaces. 2012/12/12 - 23:27

Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of
the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those
often encountered in biology and medicine. In past years, PCI has become one of the most used
imaging methods in laboratory and preclinical studies: its unique characteristics allow high
contrast 3D visualization of thick and complex samples even at high spatial resolution. Applications
have covered a wide range of pathologies and organs, and are more and more often performed in vivo .
Several techniques are now available to exploit and visualize the phase-contrast: propagation- and
analyzer-based, crystal and grating interferometry and non-interferometric methods like the coded
aperture. In this review, covering the last five years, we will give an overview of the main
theoretical and experimental developments and of the important steps performed towards the clinical
implementati... 2012/12/11 - 03:34

Since 1889 the international prototype of the kilogram has served as the definition of the unit of
mass in the International System of Units (SI). It is the last material artefact to define a base
unit of the SI, and it influences several other base units. This situation is no longer acceptable
in a time of ever increasing measurement precision. It is therefore planned to redefine the unit of
mass by fixing the numerical value of the Planck constant. At the same time three other base units,
the ampere, the kelvin and the mole, will be redefined. As a first step, the kilogram redefinition
requires a highly accurate determination of the Planck constant in the present SI system, with a
relative uncertainty of the order of 1 part in 10 8 . The most promising experiment for this
purpose, and for the future realization of the kilogram, is the watt balance. It compares mechanical
and electrical power and makes use of two macroscopic quantum effects, thus creating a ... 2012/12/05 - 16:35

Various sophisticated approximation methods exist for the description of quantum many-body systems.
It was realized early on that the theoretical description can simplify considerably in
one-dimensional systems and various exact solutions exist. The focus in this introductory paper is
on fermionic systems and the emergence of the Luttinger liquid concept. 2012/12/05 - 16:35

A look at the history of this journal reveals some significant trends in the evolution of
measurement science and shows how key papers published in the journal have influenced these
developments. 2012/12/05 - 16:35

This article presents a review of work performed over the past ten years in France, centered on the
utilization of laser-induced fluorescence (LIF) spectroscopy to diagnose the low-pressure magnetized
dc discharge of a Hall thruster (HT). The latter is a gridless electric propulsion device in a
crossed electric and magnetic field configuration, which is used onboard satellites and space probes
for various types of maneuvers. Although the design of a HT is relatively simple, the physical
mechanisms that govern thrust generation and efficiency are not yet fully understood.
Characterization of the ion and atom velocity distribution function (VDF) appears to be a powerful
way to obtain insights into the underlying physics. The VDF of xenon and krypton—the most common
propellants—is therefore locally interrogated by means of LIF on excited levels. In this review
emphasis is placed on time-averaged and time-resolved continuous-wave LIF measurements, associated
quantities and recent out... 2012/11/29 - 15:06

Neutrino-driven winds, which follow core-collapse supernova explosions, present a fascinating
nuclear-astrophysics problem that requires an understanding of advanced astrophysics simulations,
the properties of matter and neutrino interactions under extreme conditions, the structure and
reactions of exotic nuclei, and comparisons with forefront astronomical observations. The
neutrino-driven wind has attracted vast attention over the last 20 years as it was suggested as a
candidate for the astrophysics site where half of the heavy elements are produced via the r-process.
In this review, we summarize our present understanding of neutrino-driven winds from the dynamical
and nucleosynthesis perspectives. Rapid progress has been made during recent years in understanding
the wind with improved simulations and better micro physics. The current status of the fields is
that hydrodynamical simulations do not reach the extreme conditions necessary for the r-process, and
the proton or neutron... 2012/11/29 - 15:06

The detection and measurement of gas concentrations using the characteristic optical absorption of
the gas species is important for both understanding and monitoring a variety of phenomena from
industrial processes to environmental change. This study reviews the field, covering several
individual gas detection techniques including non-dispersive infrared, spectrophotometry, tunable
diode laser spectroscopy and photoacoustic spectroscopy. We present the basis for each technique,
recent developments in methods and performance limitations. The technology available to support this
field, in terms of key components such as light sources and gas cells, has advanced rapidly in
recent years and we discuss these new developments. Finally, we present a performance comparison of
different techniques, taking data reported over the preceding decade, and draw conclusions from this
benchmarking. 2012/11/28 - 16:08

Energy harvesting refers to the set of processes by which useful energy is captured from waste,
environmental, or mechanical sources and is converted into a usable form. The discipline of energy
harvesting is a broad topic that includes established methods and materials such as photovoltaics
and thermoelectrics, as well as more recent technologies that convert mechanical energy, magnetic
energy and waste heat to electricity. This article will review various state-of-the-art materials
and devices for direct energy conversion and in particular will include multistep energy conversion
approaches. The article will highlight the nano-materials science underlying energy harvesting
principles and devices, but also include more traditional bulk processes and devices as appropriate
and synergistic. Emphasis is placed on device-design innovations that lead to higher efficiency
energy harvesting or conversion technologies ranging from the cm/mm-scale down to MEMS/NEMS (micro-
and nano-elect... 2012/11/28 - 16:08

The nonlinear supersymmetric (SUSY) approach to spectral problems in quantum mechanics (QM) is
reviewed. Its building from the chains (ladders) of linear SUSY systems is outlined and different
one-dimensional and two-dimensional realizations are described. It is elaborated how the nonlinear
SUSY approach provides two new methods of SUSY separation of variables for various two-dimensional
models. In the framework of these methods, a partial and/or complete solution of some
two-dimensional models becomes possible. The full classification of ladder-reducible and irreducible
chains of SUSY algebras in one-dimensional QM is given. The emergence of hidden symmetries and
spectrum generating algebras is elucidated in the context of the nonlinear SUSY in one-dimensional
stationary and non-stationary, as well as in two-dimensional QM. 2012/11/28 - 16:08

High-power GaAs-based diode lasers produce optical energy with extremely high efficiencies, but
their spectrum is too broad for many applications (4–5 nm with 95% power content). Narrow spectra
(<1 nm) can be achieved using monolithically integrated gratings and recent advances in
semiconductor technology have largely eliminated the losses associated with this step. However, it
remains challenging to develop designs that simultaneously achieve high power, high efficiencies and
narrow spectra over a wide operation range. We review here the design choices necessary for
optimized performance, using 975 nm broad-area lasers with uniform overgrown distributed feedback
(DFB) gratings as a worked example, focusing on the role of the grating coupling strength. The steps
necessary to minimize losses in the grating region are also reviewed. In addition, we show that
special measures are needed to sustain narrow spectra in broad-area DFB lasers as they can support
multiple longitudinal, ... 2012/11/27 - 15:23

The subject of tribology encompasses the friction, wear and lubrication of mechanical components
such as bearings and gears. Tribological practices are aimed at ensuring that such components
operate with high efficiency (low friction) and achieve long lives. On spacecraft mechanisms the
route to achieving these goals brings its own unique challenges. This review describes the problems
posed by the space environment, the types of tribological component used on spacecraft and the
approaches taken to their lubrication. It is shown that in many instances lubrication needs can be
met by synthetic oils having exceedingly low volatilities, but that at temperature extremes the only
means of reducing friction and wear is by solid lubrication. As the demands placed on space
engineering increase, innovatory approaches will be needed to solve future tribological problems.
The direction that future developments might take is anticipated and discussed. 2012/11/21 - 08:29

This review considers the management of motion in photon radiation therapy. An overview is given of
magnitudes and variability of motion of various structures and organs, and how the motion affects
images by producing artifacts and blurring. Imaging of motion is described, including 4DCT and
4DPET. Techniques for monitoring motion in real time by use of surrogates are reviewed. Treatment
planning for various motion-management treatment delivery strategies is discussed, including choice
of planning image, treatment field margins and dose calculation. Imaging techniques displaying
motion in the treatment room for pre-treatment as well as real-time imaging for localization and
verification are covered, and their use for various motion-management treatment delivery techniques
is discussed. Use of motion management for different treatment sites—breast, lung and other sites—is
elaborated, and gating, breath-hold and beam tracking strategies are described. Suggestions are
given for brea... 2012/11/21 - 08:29

The conformation of protein molecules is determined by a balance of various forces, including van
der Waals attraction, electrostatic interaction, hydrogen bonding, and conformational entropy. When
protein molecules encounter an interface, they are often adsorbed on the interface. The conformation
of an adsorbed protein molecule strongly depends on the interaction between the protein and the
interface. Recent time-resolved investigations have revealed that protein conformation changes
during the adsorption process due to the protein–protein interaction increasing with increasing
interface coverage. External conditions also affect the protein conformation. This review considers
recent dynamic observations of protein adsorption at various interfaces and their implications for
the kinetics of protein unfolding at interfaces. 2012/11/20 - 02:18

Clouds in the tropics can organize the circulation on planetary scales and profoundly impact long
range seasonal forecasting and climate on the entire globe, yet contemporary operational computer
models are often deficient in representing these phenomena. On the other hand, contemporary
observations reveal remarkably complex coherent waves and vortices in the tropics interacting across
a bewildering range of scales from kilometers to ten thousand kilometers. This paper reviews the
interdisciplinary contributions over the last decade through the modus operandi of applied
mathematics to these important scientific problems. Novel physical phenomena, new multiscale
equations, novel PDEs, and numerical algorithms are presented here with the goal of attracting
mathematicians and physicists to this exciting research area. 2012/11/17 - 06:29

One of the most fundamental questions we can ask about a given gauge theory is its phase diagram. In
the Standard Model, we observe three fundamentally different types of behavior: QCD is in a confined
phase at zero temperature, while the electroweak sector of the Standard Model combines Coulomb and
Higgs phases. Our current understanding of the phase structure of gauge theories owes much to the
modern theory of phase transitions and critical phenomena, but has developed into a subject of
extensive study. After reviewing some fundamental concepts of phase transitions and
finite-temperature gauge theories, we discuss some recent work that broadly extends our knowledge of
the mechanisms that determine the phase structure of gauge theories. A new class of models with a
rich phase structure has been discovered, generalizing our understanding of the
confinement–deconfinement transition in finite-temperature gauge theories. Models in this class have
spacetime topologies with one or mor... 2012/11/12 - 21:27

Exciton states and related optical properties of a single-walled carbon nanotube are reviewed,
primarily from a theoretical viewpoint. The energies and wavefunctions of excitons are discussed
using a screened Hartree–Fock approximation with an effective-mass or k ⋅ p approximation. The close
relationship between a long-range electron–hole exchange interaction and a depolarization effect is
clarified. I discuss optical properties including the radiative lifetime of excitons, absorption
spectra and radiation force. To describe these properties in a unified scheme, a self-consistent
method is introduced for calculating the scattering light and induced current density due to
excitons. I also briefly review experimental results on the Aharonov–Bohm effect in excitons and
quasi-dark excitons excited by light polarized perpendicular to the tube axis. 2012/11/09 - 21:11

Fast, high efficiency and low error single-photon sources are required for the implementation of a
number of quantum information processing applications. The fastest triggered single-photon sources
to date have been demonstrated using epitaxially grown semiconductor quantum dots (QDs), which can
be conveniently integrated with optical microcavities. Recent advances in QD technology, including
demonstrations of high temperature and telecommunications wavelength single-photon emission, have
made QD single-photon sources more practical. Here we discuss the applications of single-photon
sources and their various requirements, before reviewing the progress made on a QD platform in
meeting these requirements. 2012/11/09 - 21:11

The ex situ process has emerged as a popular technology for growing epitaxial YBa 2 Cu 3 O 7 (YBCO)
for the second generation of coated conductors. The process combines low cost, ease of scale-up, the
possibility of achieving high critical currents in relatively thick YBCO layers, as well as high
tolerances to substrate misalignment. All of these factors explain why the process is increasingly
becoming adapted by manufacturing companies for the production of YBCO wires. Studies of the barium
fluoride variant of the ex situ process have offered rare insights into the structure, chemistry and
pinning in ultra-thick, 5 μm, ex situ YBCO layers. The transition to thick YBCO layers is viewed as
one of the key ingredients of the commercial success of the YBCO wire technology, which makes these
studies especially relevant. This review is intended to be a comprehensive introduction into the
history, physics and chemistry of barium fluori... 2012/11/08 - 18:38

This paper highlights the results of the whole work including the synthesis of highly luminescent
quantum dots (QDs), characterizations and testing applications of them in different kinds of
sensors. Concretely, it presents: (i) the successful synthesis of colloidal CdTe and CdSe QDs, their
core/shell structures with single- and/or double-shell made by CdS, ZnS or ZnSe/ZnS; (ii)
morphology, structural and optical characterizations of the synthesized QDs; and (iii) testing
examples of QDs as the fluorescence labels for agricultural-bio-medical objects (for tracing
residual pesticide in agricultural products, residual clenbuterol in meat/milk and for detection of
H5N1 avian influenza virus in breeding farms). Overall, the results show that the synthesized QDs
have very good crystallinity, spherical shape and strongly emit at the desired wavelengths between
∼500 and 700 nm with the luminescence quantum yield (LQY) of 30–85%. These synthesized QDs were used
in fabrication of the thre... 2012/11/08 - 18:38

We investigate rogue waves in deep water in the framework of the nonlinear Schrödinger (NLS) and
Dysthe equations. Amongst the homoclinic orbits of unstable NLS Stokes waves, we seek good
candidates to model actual rogue waves. In this paper we propose two selection criteria: stability
under perturbations of initial data, and persistence under perturbations of the NLS model. We find
that requiring stability selects homoclinic orbits of maximal dimension. Persistence under (a
particular) perturbation selects a homoclinic orbit of maximal dimension all of whose spatial modes
are coalesced. These results suggest that more realistic sea states, described by JONSWAP power
spectra, may be analyzed in terms of proximity to NLS homoclinic data. In fact, using the NLS
spectral theory, we find that rogue wave events in random oceanic sea states are well predicted by
proximity to homoclinic data of the NLS equation. 2012/11/02 - 17:22

A survey is given of the major developments in three-dimensional velocity field measurements using
the tomographic particle image velocimetry (PIV) technique. The appearance of tomo-PIV dates back
seven years from the present review (Elsinga et al 2005a 6th Int. Symp. PIV (Pasadena, CA) ) and
this approach has rapidly spread as a versatile, robust and accurate technique to investigate
three-dimensional flows (Arroyo and Hinsch 2008 Topics in Applied Physics vol 112 ed A Schröder and
C E Willert (Berlin: Springer) pp 127–54) and turbulence physics in particular. A considerable
number of applications have been achieved over a wide range of flow problems, which requires the
current status and capabilities of tomographic PIV to be reviewed. The fundamental aspects of the
technique are discussed beginning from hardware considerations for volume illumination, imaging
systems, their configurations and system calibration. The data processing aspects are of uppermost
i... 2012/10/29 - 14:04

Recent advances in ultra-high repetition rate (100 kHz and above) laser diagnostics for fluid
dynamic measurements are reviewed. The development of the pulse burst laser system, which enabled
several of these advances, is described. The pulse burst laser system produces high repetition rate
output by slicing the output of a low power continuous wave laser and passing the resulting burst of
pulses through a series of pulsed Nd:YAG amplifiers. Several systems have been built with output
approaching 1.0 J/pulse over bursts of up to 100 pulses generated at between 50 and 1000 kHz.
Combined with the capabilities of several types of commercially available high-speed cameras, these
systems have been used to make a wide variety of high repetition rate and 3D flow measurements.
Several examples of various high repetition rate laser diagnostics are described, including flow
visualization, filtered Rayleigh scattering, planar Doppler velocimetry, particle image velocimetry,
planar laser ind... 2012/10/29 - 14:04

The problem of how to accurately measure the flowrate of oil–gas–water mixtures in a pipeline
remains one of the key challenges in the petroleum industry. This paper discusses why three-phase
flow measurement is still important and why it remains a difficult problem to solve. The measurement
strategies and principal base technologies currently used by commercial manufacturers are described,
and research developments that could influence future flowmeter design are considered. Finally,
future issues, which will need to be addressed by manufacturers and users of three-phase flowmeters,
are discussed. 2012/10/29 - 14:04

We give an overview over the application of functional equations, namely the classical Poincaré and
renewal equations, to the study of the spectrum of Laplace operators on self-similar fractals. We
compare the techniques used to those used in the Euclidean situation. Furthermore, we use the
obtained information on the spectral zeta function to compute the Casimir energy of fractals. We
give numerical values for this energy for the Sierpiński gasket. 2012/10/29 - 14:04

The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were
discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful
nearby galaxies. Since then, enormous theoretical and observational efforts have been made to
understand the astrophysics of MBHs. We have discovered that some of the most massive black holes
known, weighing billions of solar masses, powered luminous quasars within the first billion years of
the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies
formed. Dynamical evidence also indicates that black holes with masses of millions to billions of
solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers
today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby
bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical,
questions ... 2012/10/26 - 20:02

Photonic crystals (PhCs) are periodically structured optical media offering the opportunity for
spontaneous emission (SpE) to be strongly controlled in spatial terms (directions) or in absolute
terms (rates). We discuss the application of this concept for practical light-emitting sources,
summarizing the principles and actual merits of various approaches based on two- and
three-dimensional PhCs. We take into consideration the numerous constraints on real-world
light-emitting structures and materials. The various mechanisms through which modified photonic
bands and band gaps can be used are first revisited in view of their use in light sources. We then
present an in-depth discussion of planar emitters and enhanced extraction of light thanks to grating
diffraction. Applications to conventional III–V semiconductors and to III-nitrides are reviewed.
Comparison with random surface roughening reveals some common physical limitations. Some advanced
approaches with complex structures or ... 2012/10/26 - 20:02

Chemical solution deposition (CSD) is a very competitive technique to obtain epitaxial films and
multilayers of high quality with controlled nanostructures. Based on the strong attractiveness from
the cost point of view, the production of long length coated conductors based on the CSD approach is
being extensively developed. The trifluoroacetate route (TFA) is the most widely used route to
achieve epitaxial YBa 2 Cu 3 O 7 (YBCO) layers with high critical currents, however a deep
understanding of all the individual consecutive processing steps, as well as their mutual influence
and relationship, is required to achieve superconducting materials with high performance. In this
work, we review advances in the knowledge of all the steps relevant to the preparation of YBCO thin
films based on TFA precursors as a CSD methodology: solution preparation and deposition, pyrolysis
processes, intermediate phase evolution, nucleation and growth phenomena, microstru... 2012/10/26 - 20:02

This review will focus on the use of time-of-flight (TOF) techniques to identify particles emerging
from high-energy particle interactions. The curvature of tracks of charged particles in a magnetic
field depends on its momentum and charge. The momentum is the product of the mass × velocity; thus
if the velocity is also measured, the mass can be calculated. TOF is essentially just this, the
measurement of the velocity. We will consider recent advances within this field; this was brought on
by the development of the multigap resistive plate chamber (MRPC). Since the MRPC has become the new
standard technology in the field, a good part of this review will consider the operation of this
detector. The ALICE TOF is a large array that makes use of the MRPC detector, thus this array will
be used as an example and discussed, highlighting the choices made when designing the array. The
MRPC has exceptional operation characteristics; in large part due to powerful space charge effects
that a... 2012/10/19 - 18:37