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Astronomia Astrofizyka

Sztuka dawna i współczesna, muzea i kolekcje

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

Substancje, reakcje, energia
Fizyka, chemia i inżynieria materiałowa

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


Research interest in convective heat transfer using suspensions of nano-sized solid particles has
been growing rapidly over the past decade, seeking to develop novel methods for enhancing the
thermal performance of heat transfer fluids. Due to their superior transport properties and
significant enhancement in heat transfer characteristics, nanofluids are believed to be a promising
heat transfer fluid for the future. The stability of nanofluids is also a key aspect of their
sustainability and efficiency. This review summarizes the recent research findings on stability,
thermophysical properties and convective heat transfer of nano-sized particles suspended in base
fluids. Furthermore, various mechanisms of thermal conductivity enhancement and challenges faced in
nanofluid development are also discussed. 2014/07/29 - 12:13

The framework of generalized probabilistic theories is a powerful tool for studying the foundations
of quantum physics. It provides the basis for a variety of recent findings that significantly
improve our understanding of the rich physical structure of quantum theory. This review paper tries
to present the framework and recent results to a broader readership in an accessible manner. To
achieve this, we follow a constructive approach. Starting from a few basic physically motivated
assumptions we show how a given set of observations can be manifested in an operational theory.
Furthermore, we characterize consistency conditions limiting the range of possible extensions. In
this framework classical and quantum theory appear as special cases, and the aim is to understand
what distinguishes quantum mechanics as the fundamental theory realized in nature. It turns out that
non-classical features of single systems can equivalently result from higher-dimensional classical
theories that ha... 2014/07/23 - 16:37

The symmetry energy describes how the energy of nuclear matter rises as one goes away from equal
numbers of neutrons and protons. This is very important to describe neutron rich matter in
astrophysics. This article reviews our knowledge of the symmetry energy from theoretical
calculations, nuclear structure measurements, heavy-ion collisions, and astronomical observations.
We then present a roadmap to make progress in areas of relevance to the symmetry energy that
promotes collaboration between the astrophysics and the nuclear physics communities. 2014/07/22 - 17:08

Magnetism is a very fascinating and dynamic field. Especially in the last 30 years, there have been
many major advances in a range of areas from novel fundamental phenomena to new products.
Applications such as hard disc drives and magnetic sensors are part of our daily life and new
applications, such as in non-volatile computer random access memory, are expected to surface
shortly. Thus it is an opportune time for describing the current status and current and future
challenges in the form of a roadmap article. The 2014 Magnetism Roadmap provides a view on several
selected, presently very active innovative developments. It consists of twelve sections, each
written by an expert in the field and addressing a specific subject, with a strong emphasis on
future potential. This Roadmap cannot cover the entire field. Several highly relevant areas have
been selected without attempting to provide a full review - a future update will aim to address
further. The scope covers mostly na... 2014/07/20 - 00:04

Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions, with
rather well-characterized pair interactions and minimized external influences. In complementary
approaches experiment, analytic theory and simulation have been employed to study colloidal
solidification in great detail. These studies were based on advanced optical methods, careful system
characterization and sophisticated numerical methods. Over the last decade, both the effects of the
type, strength and range of the pair-interaction between the colloidal particles and those of the
colloid-specific polydispersity have been addressed in a quantitative way. Key parameters of
crystallization have been derived and compared to those of metal systems. These systematic
investigations significantly contributed to an enhanced understanding of the crystallization
processes in general. Further, new fundamental questions have arisen and (partially) been solved
over the last decade: including, ... 2014/07/20 - 00:04

Crystalline bacterial cell surface layers (S-layers) represent the outermost cell envelope component
in a broad range of bacteria and archaea. They are monomolecular arrays composed of a single protein
or glycoprotein species and represent the simplest biological membranes developed during evolution.
They are highly porous protein mesh works with unit cell sizes in the range of 3 to 30 nm, and pore
sizes of 2 to 8 nm. S-layers are usually 5 to 20 nm thick (in archaea, up to 70 nm). S-layer
proteins are one of the most abundant biopolymers on earth. One of their key features, and the focus
of this review, is the intrinsic capability of isolated native and recombinant S-layer proteins to
form self-assembled mono- or double layers in suspension, at solid supports, the air-water
interface, planar lipid films, liposomes, nanocapsules, and nanoparticles. The reassembly is
entropy-driven and a fascinating example of matrix assembly following a multistage, non-classical
pathway in which ... 2014/07/17 - 23:08

Field emission has been known to mankind for more than a century, and extensive research in this
field for the last 40–50 years has led to development of exciting applications such as electron
sources, miniature x-ray devices, display materials, etc. In the last decade, large-area field
emitters were projected as an important material to revolutionize healthcare and medical devices,
and space research. With the advent of nanotechnology and advancements related to carbon nanotubes,
field emitters are demonstrating highly enhanced performance and novel applications. Next-generation
emitters need ultra-high emission current density, high brightness, excellent stability and
reproducible performance. Novel design considerations and application of new materials can lead to
achievement of these capabilities. This article presents an overview of recent developments in this
field and their effects on improved performance of field emitters. These advancements are
demonstrated to hold great... 2014/07/16 - 17:37

The recent advances in epitaxial SiC films' growth on Si are overviewed. The basic classical methods
currently used for SiC films' growth are discussed and their advantages and disadvantages are
explored. The basic idea and the theoretical background for a new method of the synthesis of
epitaxial SiC films on Si are given. It will be shown that the new method is significantly different
from the classical techniques of thin-film growth where the evaporation of the atoms onto the
substrate surface is exploited. The new method is based on the substitution of some atoms in the
silicon matrix by the carbon atoms to form the molecules of silicon carbide. It will be shown that
the following process of SiC nucleation happens gradually without destroying the crystalline
structure of the silicon matrix, and the orientation of a grown film is imposed by the original
crystalline structure of the silicon matrix (not only by the substrate surface as in conventional
methods of film growth). A c... 2014/07/08 - 21:07

Organic molecules and polymers with extended π -conjugation are appealing as advanced electronic
materials, and have already found practical applications in thin-film transistors, light emitting
diodes, and chemical sensors. Transition metal (TM)-catalyzed cross-coupling methodologies have
evolved over the past four decades into one of the most powerful and versatile methods for C–C bond
formation, enabling the construction of a diverse and sophisticated range of π -conjugated oligomers
and polymers. In this review, we focus our discussion on recent synthetic developments of several
important classes of π -conjugated systems using TM-catalyzed cross-coupling reactions, with a
perspective on their utility for organic electronic materials. 2014/07/08 - 21:07

The capacity of the optical communication infrastructure in backbone networks has increased
1000-fold over the last 20 years. Despite this rapid progress, internet traffic is continuing to
grow at an annual rate of 40%. This means that in 20 years, we will need petabit/s or even exabit/s
optical communication. In this paper, we present recent challenges and efforts toward achieving a
hardware paradigm shift to overcome the capacity limitation imposed by the current optical
communication infrastructure. We will overview the latest advances on the three “multi”
technologies, i.e., multi-level transmission with ultrahigh spectral efficiency, space division
multiplexing in multi-core fibers, and mode division multiplexing with multiple-input
multiple-output (MIMO). 2014/07/05 - 14:14

Progress in our understanding of the magnetic properties of R -containing icosahedral quasicrystals
( R = rare earth element) from over 20 years of experimental effort is reviewed. This includes the
much studied R -Mg-Zn and R -Mg-Cd ternary systems, as well as several magnetic quasicrystals that
have been discovered and investigated more recently including Sc-Fe-Zn, R -Ag-In, Yb-Au-Al, the
recently synthesized R -Cd binary quasicrystals, and their periodic approximants. In many ways, the
magnetic properties among these quasicrystals are very similar. However, differences are observed
that suggest new experiments and promising directions for future research. 2014/07/05 - 14:14

In this article, we review the characteristic features of icosahedral cluster solids,
metallic–covalent bonding conversion (MCBC), and the thermoelectric properties of Al-based
icosahedral quasicrystals and approximants. MCBC is clearly distinguishable from and closely related
to the well-known metal–insulator transition. This unique bonding conversion has been experimentally
verified in 1/1-AlReSi and 1/0-Al 12 Re approximants by the maximum entropy method and Rietveld
refinement for powder x-ray diffraction data, and is caused by a central atom inside the icosahedral
clusters. This helps to understand pseudogap formation in the vicinity of the Fermi energy and
establish a guiding principle for tuning the thermoelectric properties. From the electron density
distribution analysis, rigid heavy clusters weakly bonded with glue atoms are observed in the
1/1-AlReSi approximant crystal, whose physical properties are close to icosahedral Al–Pd–TM (TM: Re,
Mn) quasicrystals. Th... 2014/07/05 - 14:14

The field of graphene research has developed rapidly since its first isolation by mechanical
exfoliation in 2004. Due to the relativistic Dirac nature of its charge carriers, graphene is both a
promising material for next-generation electronic devices and a convenient low-energy testbed for
intrinsically high-energy physical phenomena. Both of these research branches require the facile
fabrication of clean graphene devices so as not to obscure its intrinsic physical properties.
Hexagonal boron nitride has emerged as a promising substrate for graphene devices as it is
insulating, atomically flat and provides a clean charge environment for the graphene. Additionally,
the interaction between graphene and boron nitride provides a path for the study of new physical
phenomena not present in bare graphene devices. This review focuses on recent advancements in the
study of graphene on hexagonal boron nitride devices from the perspective of scanning tunneling
microscopy with highlights of... 2014/07/05 - 14:14

Power-modulated ( pulsed ) plasmas have demonstrated several advantages compared to continuous wave
(CW) plasmas. Specifically, pulsed plasmas can result in a higher etching rate, better uniformity,
and less structural, electrical or radiation (e.g. vacuum ultraviolet) damage. Pulsed plasmas can
also ameliorate unwanted artefacts in etched micro-features such as notching, bowing,
micro-trenching and aspect ratio dependent etching. As such, pulsed plasmas may be indispensable in
etching of the next generation of micro-devices with a characteristic feature size in the sub-10 nm
regime. This work provides an overview of principles and applications of pulsed plasmas in both
electropositive (e.g. argon) and electronegative (e.g. chlorine) gases. The effect of pulsing the
plasma source power ( source pulsing ), the electrode bias power ( bias pulsing ), or both source
and bias power ( synchronous pulsing ), on the time evolution of species densities, electron
energy... 2014/07/01 - 15:10

Plasma medicine is a rapidly evolving multidisciplinary field at the intersection of chemistry,
biochemistry, physics, biology, medicine and bioengineering. It holds great potential in medical,
health care, dentistry, surgical, food treatment and other applications. This multidisciplinary
nature and variety of possible applications come along with an inherent and intrinsic complexity.
Advancing plasma medicine to the stage that it becomes an everyday tool in its respective fields
requires a fundamental understanding of the basic processes, which is lacking so far. However, some
major advances have already been made through detailed experiments over the last 15 years.
Complementary, computer simulations may provide insight that is difficult—if not impossible—to
obtain through experiments. In this review, we aim to provide an overview of the various simulations
that have been carried out in the context of plasma medicine so far, or that are relevant for plasma
medicine. We focus ou... 2014/06/28 - 12:34

It is indispensable to develop wide-band-gap based ultraviolet (UV) photodetectors (PDs), which are
one of the basic building blocks of solid state UV optoelectronic devices. In the last two decades,
we have witnessed the renaissance of ZnO as a wide-band-gap semiconductor and an enormous
development of ZnO-based UV PDs as a result of its superb optical and electronic properties. Since
the first demonstration, a great variety of UV PDs based on ZnO and its related materials have been
proposed and demonstrated. These PDs, with diverse device geometries, exhibit either high
performance or multiple functions, reflecting a state-of-the-art technology of UV optoelectronics.
In this review, we study the latest progress of UV PDs made on ZnO and Mg x Zn 1− x O, which is a
representative alloy of ZnO for band-gap engineering techniques. The discussion focuses on the
device performance and the behind device physics according to the architecture of UV PDs. 2014/06/24 - 13:45

Recent findings related to childhood leukaemia incidence near nuclear installations have raised
questions which can be answered neither by current knowledge on radiation risk nor by other
established risk factors. In 2012, a workshop was organised on this topic with two objectives: (a)
review of results and discussion of methodological limitations of studies near nuclear
installations; (b) identification of directions for future research into the causes and pathogenesis
of childhood leukaemia. The workshop gathered 42 participants from different disciplines, extending
widely outside of the radiation protection field. Regarding the proximity of nuclear installations,
the need for continuous surveillance of childhood leukaemia incidence was highlighted, including a
better characterisation of the local population. The creation of collaborative working groups was
recommended for consistency in methodologies and the possibility of combining data for future
analyses. Regarding the caus... 2014/06/19 - 21:24

Breath analysis is a young field of research with its roots in antiquity. Antoine Lavoisier
discovered carbon dioxide in exhaled breath during the period 1777–1783, Wilhelm (Vilém) Petters
discovered acetone in breath in 1857 and Johannes Müller reported the first quantitative
measurements of acetone in 1898. A recent review reported 1765 volatile compounds appearing in
exhaled breath, skin emanations, urine, saliva, human breast milk, blood and feces. For a large
number of compounds, real-time analysis of exhaled breath or skin emanations has been performed,
e.g., during exertion of effort on a stationary bicycle or during sleep. Volatile compounds in
exhaled breath, which record historical exposure, are called the ‘exposome’. Changes in biogenic
volatile organic compound concentrations can be used to mirror metabolic or (patho)physiological
processes in the whole body or blood concentrations of drugs (e.g. propofol) in clinical
settings—even during artificial ventilation... 2014/06/19 - 21:24

Wound healing is a complex matrix and overlapping process. In order to accelerate the healing
process and minimize bacterial infection, light-based therapy was applied to stimulate bio-reaction
to improve healing. The aim of this paper is to review the effects induced by light source (laser
and incoherent light like LED) on different biological targets. The light-based therapy techniques
were categorized according to the wavelength, energy density, type of irradiance and activity of
tissues in the healing process. Out of 80 cases, 77% were animal studies, 5% were human studies and
18% were cell studies. Around 75% of light-based therapy has an advantage on tissue interaction and
25% has no effect or inhibition on the healing process. The appropriate dose appears to be between 1
and 5 J cm −2 . At shorter wavelength, photobiostimulation would be effective with a high frequently
administrated low-energy dose. On the other hand, for longer wavelength it is the reverse, i.e.... 2014/06/19 - 21:24

Plasma etching has been enabling nano-electronic fabrication since the 1980s; during this time,
transistor size has shrunk by nearly two orders of magnitude, starting at1.0 µ m in the mid 80s to
∼0.01 µ m today. The manufacturing of these devices requires overcoming a series of challenges,
ranging from continuous innovation on device integration to extend Moore's law to breaking tradeoffs
on the perennial challenge of aspect ratio-dependent etching. In this paper, we will review four key
areas in etch manufacturing: uniformity, defects, surface precision and ‘sticky’/non-volatile etch
materials. In the uniformity section, we will discuss the challenges for microscopic uniformity,
such as localized feature dimension variations; macroscopic uniformity, such as performance at the
extreme edge of the wafer; and repeatable uniformity, meaning wafer-to-wafer, lot-to-lot and
chamber-to-chamber performance. While defect management is successful with in situ plasma cle... 2014/06/19 - 21:24

How does magnetism behave when the physical dimension is reduced to the size of nanostructures? The
multiplicity of magnetic states in these systems can be very rich, in that their properties depend
on the atomic species, the cluster size, shape and symmetry or choice of the substrate. Small
variations of the cluster parameters may change the properties dramatically. Research in this field
has gained much by the many novel experimental methods and techniques exhibiting atomic resolution.
Here we review the ab-initio approach, focusing on recent calculations on magnetic frustration and
occurrence of non-collinear magnetism in antiferromagnetic nanostructures deposited on surfaces. 2014/06/13 - 14:38

This paper provides an overview of ultrafast wavefront rotation of femtosecond laser pulses and its
various applications in highly nonlinear optics, focusing on processes that lead to the generation
of high-order harmonics and attosecond pulses. In this context, wavefront rotation can be exploited
in different ways, to obtain new light sources for time-resolved studies, called ‘attosecond
lighthouses’, to perform time-resolved measurements of nonlinear optical processes, using ‘photonic
streaking’, or to track changes in the carrier–envelope relative phase of femtosecond laser pulses.
The basic principles are explained qualitatively from different points of view, the experimental
evidence obtained so far is summarized, and the perspectives opened by these effects are discussed. 2014/06/13 - 14:38

Ultrafast electron diffraction and microscopy can provide a four-dimensional visualization of atomic
motion in space and time, but space charge effects limit the temporal resolution. In contrast to
bright pulses with many electrons, single-electron wave packets have no Coulomb repulsion at all and
can hence have ultimate characteristics in space and time. This paper discusses our current
understanding of single-electron pulse generation, microwave compression, duration and jitter, pulse
front distortions, coherence, pulse metrology and diffraction imaging of atomic and eventually
electronic motion on the atomic scale. 2014/06/13 - 14:38

The microvasculature presents a particular challenge in physiological measurement because the vessel
structure is spatially inhomogeneous and perfusion can exhibit high variability over time. This
review describes, with a clinical focus, the wide variety of methods now available for imaging of
the microvasculature and their key applications. Laser Doppler perfusion imaging and laser speckle
contrast imaging are established, commercially-available techniques for determining microvascular
perfusion, with proven clinical utility for applications such as burn-depth assessment. Nailfold
capillaroscopy is also commercially available, with significant published literature that supports
its use for detecting microangiopathy secondary to specific connective tissue diseases in patients
with Raynaud's phenomenon. Infrared thermography measures skin temperature and not perfusion
directly, and it has only gained acceptance for some surgical and peripheral microvascular
applications. Other eme... 2014/06/09 - 16:22

Multilayer Laue lens (MLL) is a new class of x-ray optics that offer great promise for achieving
nanometre-level spatial resolution by focusing hard x-rays. Fabricating an MLL via thin-film
deposition provides the means to achieve a linear Fresnel-zone plate structure with zone widths
below 1 nm, while retaining a virtually limitless aspect ratio. Despite its similarity to the
Fresnel-zone plate, MLL exhibits categorically distinctive focusing properties and their fabrication
comes with a wide array of challenges. This article provides a comprehensive review of advances in
MLLs, and includes extensive theoretical modelling on focusing performance, discussion on
fabrication challenges, their current capabilities and notable results from x-ray focusing
experiments. 2014/06/06 - 01:09

The new family of unconventional iron-based superconductors discovered in 2006 immediately relieved
their copper-based high-temperature predecessors as the most actively studied superconducting
compounds in the world. The experimental and theoretical effort made in order to unravel the
mechanism of superconductivity in these materials has been overwhelming. Although our understanding
of their microscopic properties has been improving steadily, the pairing mechanism giving rise to
superconducting transition temperatures up to 55 K remains elusive. And yet the hope is strong that
these materials, which possess a drastically different electronic structure but similarly high
transition temperatures compared to the copper-based compounds, will shed essential new light onto
the several-decade-old problem of unconventional superconductivity. In this work we review the
current understanding of the itinerant-charge-carrier dynamics in the iron-based superconductors and
parent compounds la... 2014/06/06 - 01:09

The spinorial geometry method of solving Killing spinor equations is reviewed as it applies to
six-dimensional (1,0) supergravity. In particular, it is explained how the method is used to
identify both the fractions of supersymmetry preserved by and the geometry of all supersymmetric
backgrounds. Then two applications are described to systems that exhibit superconformal symmetry.
The first is the proof that some six-dimensional black hole horizons are locally isometric to AdS 3
× Σ 3 , where Σ 3 is diffeomeorphic to S 3 . The second one is a description of all supersymmetric
solutions of six-dimensional (1,0) superconformal theories and in particular of their brane
solitons. 2014/06/03 - 16:20

The present status of the three-dimensional inverse-scattering method with supersymmetric
transformations is reviewed for the coupled-channel case. We first revisit in a pedagogical way the
single-channel case, where the supersymmetric approach is shown to provide a complete, efficient and
elegant solution to the inverse-scattering problem for the radial Schrödinger equation with
short-range interactions. A special emphasis is put on the differences between conservative and
non-conservative transformations, i.e. transformations that do or do not conserve the behaviour of
solutions of the radial Schrödinger equation at the origin. In particular, we show that for the zero
initial potential, a non-conservative transformation is always equivalent to a pair of conservative
transformations. These single-channel results are illustrated on the inversion of the neutron–proton
triplet eigenphase shifts for the S - and D -waves. We then summarize and extend our previous works
on... 2014/06/03 - 16:20

In this review we summarize our experience gained from several recent ab initio studies aimed to
investigate how the competition between short-ranged chemical and long-ranged dispersion
interactions determines the bonding mechanism of a specific set of chemically functionalized π
-conjugated organic molecules on non-magnetic and magnetic metal surfaces. A key point of this
review is to provide a detailed analysis on the issue of how to tune the strength of the organic
molecule-surface interaction, such that the nature of the molecular bonding exhibits the specific
electronic features of the physisorption or chemisorption bonding mechanisms. In particular, we
discuss in detail how the precise control of these bonding mechanisms can be used to design specific
electronic and magnetic properties of hybrid organic-metallic interfaces. Furthermore, our
first-principles simulations provide not only the basic insights needed to interpret surface-science
experiments, but are ... 2014/06/01 - 18:39

After being used for years in the chemistry community to describe molecular properties, hybrid
functionals have been increasingly and successfully employed for a wide range of solid state
problems which are not accurately accessible by standard density functional theory. In particular,
the upsurge of interest in transition metal perovskite-based compounds, motivated by their
technological relevance and functional ductility, has incentivized the use of hybrid functionals for
realistic applications, as hybrid functionals appear to be capable of capturing the complex
correlated physics of this class of oxide material, characterized by a subtle coupling between
several competing interactions (lattice, orbital, spin). Here we present a map of recent
applications of hybrid functionals to perovskites, aiming to cover an ample spectra of
cases, including the 'classical' 3d compounds (manganites, titanates, nickelates, ferrites, etc.),
less conventional examples from the the 4d (technetia... 2014/05/29 - 22:15

We review progress in the development and applications of superconducting metamaterials. The review
is organized in terms of several distinct advantages and unique properties brought to the
metamaterials field by superconductivity. These include the low-loss nature of the meta-atoms, their
compact structure, their extraordinary degree of nonlinearity and tunability, magnetic flux
quantization and the Josephson effect, quantum effects in which photons interact with quantized
energy levels in the meta-atom, as well as strong diamagnetism. 2014/05/28 - 12:57

With the development of laser technology and related scientific fields, understanding of the
structure–property relationships in nonlinear optical (NLO) crystals is becoming more and more
important. In this article, first-principles studies based on density functional theory, and their
applications to elucidate the microscopic origins of the linear and NLO properties in NLO crystals,
are reviewed. The ab initio approaches have the ability to accurately predict the optical properties
in NLO crystals, and the developed analysis tools are vital to investigating their intrinsic
mechanism. This microscopic understanding has further guided molecular engineering design for NLO
crystals with novel structures and properties. It is anticipated that first-principle material
approaches will greatly improve the search efficiency and greatly help experiments to save resources
in the exploration of new NLO crystals with good performance. 2014/05/23 - 12:59

Atomic length-scale order characteristics of binary and ternary amorphous oxides are presented
within the framework of ab initio theory. A combined numerically efficient density functional based
tight-binding molecular dynamics and density functional theory approach is applied to model the
amorphous (a) phases of SiO 2 and TiO 2 as well as the amorphous phase of atomically mixed Ti x Si
1− x O 2 hybrid-oxide alloys over the entire composition range. Short and mid-range order in the
disordered material phases are characterized by bond length and bond-angle statistics, pair
distribution function analysis, coordination number and coordination polyhedra statistics, as well
as ring statistics. The present study provides fundamental insights into the order characteristics
of the amorphous hybrid-oxide frameworks formed by versatile types of TiO n and SiO m coordination
polyhedra. In a-... 2014/05/23 - 12:59

Microrheology was proposed almost twenty years ago as a technique to obtain rheological properties
in soft matter from the microscopic motion of colloidal tracers used as probes, either freely
diffusing in the host medium, or subjected to external forces. The former case is known as passive
microrheology , and is based on generalizations of the Stokes–Einstein relation between the friction
experienced by the probe and the host-fluid viscosity. The latter is termed active microrheology ,
and extends the measurement of the friction coefficient to the nonlinear-response regime of strongly
driven probes. In this review article, we discuss theoretical models available in the literature for
both passive and active microrheology, focusing on the case of single-probe motion in model
colloidal host media. A brief overview of the theory of passive microrheology is given, starting
from the work of Mason and Weitz. Further developments include refined models of the host
suspensio... 2014/05/21 - 15:22

The Glenn Research Centre of NASA, USA (
[] , silicon carbide electronics) is in pursuit of realizing bulk
manufacturing of silicon carbide (SiC), specifically by mechanical means. Single point diamond
turning (SPDT) technology which employs diamond (the hardest naturally-occurring material realized
to date) as a cutting tool to cut a workpiece is a highly productive manufacturing process. However,
machining SiC using SPDT is a complex process and, while several experimental and analytical studies
presented to date aid in the understanding of several critical processes of machining SiC, the
current knowledge on the ductile behaviour of SiC is still sparse. This is due to a number of
simultaneously occurring physical phenomena that may take place on multiple length and time scales.
For example, nucleation of dislocation can take place at small inclusions that are of a few atoms in
size and once nucleated, the inte... 2014/05/20 - 12:26

Quantum dot mode-locked lasers have emerged as a leading source for the efficient generation of
high-quality optical pulses from a compact package, attracting considerable attention for support of
multiple high-speed applications, owing to characteristics such as low noise operation and high
pulse peak power, in addition to the ability to multiplex the output pulse train in temporal and
frequency domains in order to obtain hundreds of GHz pulse repetition rates potentially operating at
1 Tbps. This topical review provides a detailed explanation into the primary advantages of quantum
dots, identifying the key features that have made them superior to other material systems for
passive mode-locking in semiconductor lasers. Following this account, the impact of the device's
cavity geometry on the operational range of two-section, monolithic passively mode-locked lasers is
investigated both experimentally and analytically. A model is described that predicts regimes of
pulsed operation... 2014/05/15 - 08:55

I review current efforts to measure the mean density of dark matter near the Sun. This encodes
valuable dynamical information about our Galaxy and is also of great importance for ‘direct
detection’ dark matter experiments. I discuss theoretical expectations in our current cosmology; the
theory behind mass modelling of the Galaxy; and I show how combining local and global measures
probes the shape of the Milky Way dark matter halo and the possible presence of a ‘dark disc’. I
stress the strengths and weaknesses of different methodologies and highlight the continuing need for
detailed tests on mock data—particularly in the light of recently discovered evidence for
disequilibria in the Milky Way disc. I collate the latest measurements of ρ dm and show that, once
the baryonic surface density contribution Σ b is normalized across different groups, there is
remarkably good agreement. Compiling data from the literature, I estimate Σ b = 54.2 ±... 2014/05/14 - 07:09

In this paper, general aspects of the reactive ion etching (RIE) technique will be described, such
as anisotropy, loading effect, lag effect, RIE chemistries and micro-masking, followed by a brief
overview of etching dielectrics (SiO x , SiN x ) and crystalline Si. The second section of the paper
is dedicated to etching III–V compound semiconductors where, based on RIE results of GaN material, a
simple and practical thermodynamic approach is exposed, explaining the criteria for selecting the
best chemistry for etching a specific material and explaining the GaN etching results. Finally, a
comprehensive study of etching InP-based materials using various chemistries will be discussed, as
well as their various photonic applications. 2014/05/10 - 01:28

The path-integral formulation of the statistical mechanics of quantum many-body systems is
described, with the purpose of introducing practical techniques for the simulation of solids. Monte
Carlo and molecular dynamics methods for distinguishable quantum particles are presented, with
particular attention to the isothermal-isobaric ensemble. Applications of these computational
techniques to different types of solids are reviewed, including noble-gas solids (helium and heavier
elements), group-IV materials (diamond and elemental semiconductors), and molecular solids (with
emphasis on hydrogen and ice). Structural, vibrational, and thermodynamic properties of these
materials are discussed. Applications also include point defects in solids (structure and
diffusion), as well as nuclear quantum effects in solid surfaces and adsorbates. Different phenomena
are discussed, as solid-to-solid and orientational phase transitions, rates of quantum processes,
classical-to-quantum crossover, a... 2014/05/10 - 01:28

The observation of vortices in superconductors was a major breakthrough in developing the conceptual
background for superconducting applications. Each vortex carries a flux quantum, and the magnetic
field decreases radially from the center. Techniques used to make magnetic field maps, such as
magnetic decoration, give vortex lattice images in a variety of systems. However, strong type II
superconductors allow penetration of the magnetic field over large distances, of the order of the
magnetic penetration depth λ . Superconductivity survives up to magnetic fields where, for imaging
purposes, there is no magnetic contrast at all. Static and dynamic properties of vortices are
largely unknown at such high magnetic fields. Reciprocal space studies using neutron scattering have
been employed to obtain insight into the collective behavior. But the microscopic details of vortex
arrangements and their motion remain difficult to obtain. Direct real-space visualization can be
made usi... 2014/05/08 - 18:43