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Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

Kolekcje IOP - REVIEWS


Conformal sigma models and Wess–Zumino–Witten (WZW) models on coset superspaces provide important
examples of logarithmic conformal field theories. They possess many applications to problems in
string and condensed matter theory. We review recent results and developments, including the general
construction of WZW models on type-I supergroups, the classification of conformal sigma models and
their embedding into string theory. 2013/11/20 - 23:29

Logarithmic conformal field theories (LCFT) play a key role, for instance, in the description of
critical geometrical problems (percolation, self-avoiding walks, etc), or of critical points in
several classes of disordered systems (transition between plateaux in the integer and spin quantum
Hall effects). Much progress in their understanding has been obtained by studying algebraic features
of their lattice regularizations. For reasons which are not entirely understood, the non-semi-simple
associative algebras underlying these lattice models—such as the Temperley–Lieb algebra or the blob
algebra—indeed exhibit, in finite size, properties that are in full correspondence with those of
their continuum limits. This applies not only to the structure of indecomposable modules, but also
to fusion rules, and provides an ‘experimental’ way of measuring couplings, such as the ‘number b ’
quantifying the logarithmic coupling of the stress–energy tensor with its partner. Most results
ob... 2013/11/20 - 23:29

We review the status of the two-dimensional Abelian sandpile model as a strong candidate to provide
a lattice realization of logarithmic conformal invariance with a central charge c = −2. Evidence
supporting this view is collected from various aspects of the model. These include the study of some
conformally invariant boundary conditions, and the corresponding boundary condition changing fields,
the calculation of correlations of certain bulk and boundary observables (the height variables) as
well as a proper account of the necessary dissipation, which allows for a physical understanding of
some of the strange but generic features of logarithmic theories. 2013/11/20 - 23:29

We provide an overview of recent developments of quantum cascade lasers (QCLs), from the
mid-infrared (mid-IR) to the far-IR (THz) range, with a special focus on their metrological-grade
applications in a number of fields. A special emphasis on the physics of the QCLs allows underlining
peculiar effects and device features recently unveiled that pave the way to novel demanding
photonics applications. 2013/11/13 - 15:35

We provide an overview of recent developments of quantum cascade lasers (QCLs), from the
mid-infrared (mid-IR) to the far-IR (THz) range, with a special focus on their metrological-grade
applications in a number of fields. A special emphasis on the physics of the QCLs allows underlining
peculiar effects and device features recently unveiled that pave the way to novel demanding
photonics applications. 2013/11/13 - 15:35

This review presents the state of the art of the application of energy harvesting in commercial and
residential buildings. Electromagnetic (optical and radio frequency), kinetic, thermal and
airflow-based energy sources are identified as potential energy sources within buildings and the
available energy is measured in a range of buildings. Suitable energy harvesters are discussed and
the available and the potential harvested energy calculated. Calculations based on these
measurements, and the technical specifications of state-of-the-art harvesters, show that typical
harvested powers are: (1) indoor solar cell (active area of 9 cm 2 , volume of 2.88 cm 3 ): ∼300 µW
from a light intensity of 1000 lx; (2) thermoelectric harvester (volume of 1.4 cm 3 ): 6 mW from a
thermal gradient of 25 °C; (3) periodic kinetic energy harvester (volume of 0.15 cm 3 ): 2 µW from a
vibration acceleration of 0.25 m s −2 at 45 Hz; (4) electromagnetic wave ha... 2013/11/13 - 15:35

Implantable medical devices usually require a battery to operate and this can represent a severe
restriction. In most cases, the implantable medical devices must be surgically replaced because of
the dead batteries; therefore, the longevity of the whole implantable medical device is determined
by the battery lifespan. For this reason, researchers have been studying energy harvesting
techniques from the human body in order to obtain batteryless implantable medical devices. The human
body is a rich source of energy and this energy can be harvested from body heat, breathing, arm
motion, leg motion or the motion of other body parts produced during walking or any other activity.
In particular, the main human-body energy sources are kinetic energy and thermal energy. This paper
reviews the state-of-art in kinetic and thermoelectric energy harvesters for powering implantable
medical devices. Kinetic energy harvesters are based on electromagnetic, electrostatic and
piezoelectric conversi... 2013/11/13 - 15:35

We review various simple analytical theories for homopolymers within a unified framework. The common
guideline of our approach is the Flory theory, and its various avatars, with the attempt at being
reasonably self-contained. We expect this review to be useful as an introduction to the topic at the
graduate student level. 2013/11/13 - 15:35

We review the recent progress regarding the loop corrections to the correlation functions in the
inflationary universe. A naive perturbation theory predicts that the loop corrections generated
during inflation suffer from various infrared (IR) pathologies. Introducing an IR cutoff by hand is
neither satisfactory nor enough to fix the problem of a secular growth, which may ruin the
predictive power of inflation models if the inflation lasts sufficiently long. We discuss the origin
of the IR divergences and explore the regularity conditions of the loop corrections for the
adiabatic perturbation, the iso-curvature perturbation, and the tensor perturbation, in turn. These
three kinds of perturbations have qualitative differences, but in discussing the IR regularity there
is a feature common to all cases, which is the importance of the proper identification of observable
quantities. Genuinely, observable quantities should respect the gauge invariance from the view point
of a local obs... 2013/11/09 - 00:18

This paper reviews the effect of organic and inorganic coatings on magnetic nanoparticles. The
ferromagnetic-like behaviour observed in nanoparticles constituted by materials which are
non-magnetic in bulk is analysed for two cases: (a) Pd and Pt nanoparticles, formed by substances
close to the onset of ferromagnetism, and (b) Au and ZnO nanoparticles, which were found to be
surprisingly magnetic at the nanoscale when coated by organic surfactants. An overview of theories
accounting for this unexpected magnetism, induced by the nanosize influence, is presented. In
addition, the effect of coating magnetic nanoparticles with biocompatible metals, oxides or organic
molecules is also reviewed, focusing on their applications. 2013/11/09 - 00:18

The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever
evolving research field which provides new alternatives to antitumoral therapies. The development of
biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties,
which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in
the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields.
Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most
studied thermoseeds, and supply different solutions for the different scenarios in cancerous
processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal
reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting
and hyperthermia. 2013/11/09 - 00:18

Tunable optofluidic devices exhibit some unique characteristics that are not achievable in
conventional solid-state photonic devices. They provide exciting opportunities for emerging
applications in imaging, information processing, sensing, optical communication, lab-on-a-chip and
biomedical engineering. A dielectrophoresis effect is an important physical mechanism to realize
tunable optofluidic devices. Via balancing the voltage-induced dielectric force and interfacial
tension, the liquid interface can be dynamically manipulated and the optical output reconfigured or
adaptively tuned in real time. Dielectrophoretically tunable optofluidic devices offer several
attractive features, such as rapid prototyping, miniaturization, easy integration and low power
consumption. In this review paper, we first explain the underlying operation principles and then
review some recent progress in this field, covering the topics of adaptive lens, beam steering,
iris, grating, optical switch/atten... 2013/11/07 - 14:55

We review recent developments in the use of renormalization group (RG) methods in low-energy nuclear
physics. These advances include enhanced RG technology, particularly for three-nucleon forces, which
greatly extends the reach and accuracy of microscopic calculations. We discuss new results for the
nucleonic equation of state with applications to astrophysical systems such as neutron stars, new
calculations of the structure and reactions of finite nuclei, and new explorations of correlations
in nuclear systems. 2013/11/06 - 08:38

Metamaterials are rationally designed man-made structures composed of functional building blocks
that are densely packed into an effective (crystalline) material. While metamaterials are mostly
associated with negative refractive indices and invisibility cloaking in electromagnetism or optics,
the deceptively simple metamaterial concept also applies to rather different areas such as
thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and
elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts,
analogies and differences to electromagnetism, and give an overview on the current state of the art
regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes
homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed
by coordinate-transformation-based approaches analogous to transformation optics. Examples are
laminates, transient thermal... 2013/11/06 - 08:38

In this review we discuss recent research on driving self-assembly of magnetic particle suspensions
subjected to alternating magnetic fields. The variety of structures and effects that can be induced
in such systems is remarkably broad due to the large number of variables involved. The alternating
field can be uniaxial, biaxial or triaxial, the particles can be spherical or anisometric, and the
suspension can be dispersed throughout a volume or confined to a soft interface. In the simplest
case the field drives the static or quasistatic assembly of unusual particle structures, such as
sheets, networks and open-cell foams. More complex, emergent collective behaviors evolve in systems
that can follow the time-dependent field vector. In these cases energy is continuously injected into
the system and striking flow patterns and structures can arise. In fluid volumes these include the
formation of advection and vortex lattices. At air–liquid and liquid–liquid interfaces striking
dynami... 2013/11/06 - 08:38

A major problem with most of the present nuclear reactors is their safety in terms of the release of
radioactivity into the environment during accidents. In some of the future nuclear reactor designs,
i.e. Generation IV reactors, the fuel is in the form of coated spherical particles, i.e. TRISO
(acronym for triple coated isotropic) particles. The main function of these coating layers is to act
as diffusion barriers for radioactive fission products, thereby keeping these fission products
within the fuel particles, even under accident conditions. The most important coating layer is
composed of polycrystalline 3C–SiC. This paper reviews the diffusion of the important fission
products (silver, caesium, iodine and strontium) in SiC. Because radiation damage can induce and
enhance diffusion, the paper also briefly reviews damage created by energetic neutrons and ions at
elevated temperatures, i.e. the temperatures at which the modern reactors will operate, and the
annealing of the dama... 2013/10/29 - 00:54

Magnetic resonance imaging (MRI) is a noninvasive imaging technique capable of obtaining
high-resolution anatomical images of the body. Major drawbacks of MRI are the low contrast agent
sensitivity and inability to distinguish healthy tissue from diseased tissue, making early detection
challenging. To address this technological hurdle, paramagnetic contrast agents have been developed
to increase the longitudinal relaxivity, leading to an increased signal-to-noise ratio. This review
focuses on methods and principles that enabled the design and engineering of nanoparticles to
deliver contrast agents with enhanced ionic relaxivities. Different engineering strategies and
nanoparticle platforms will be compared in terms of their manufacturability, biocompatibility
properties, and their overall potential to make an impact in clinical MR imaging. 2013/10/25 - 11:20

There are an infinite number of type IIB superstrings in ten dimensions, called ( p , q ) strings,
that are labeled by two distinct string charges. They can form string junctions and string networks.
These are the key to understanding the Coulomb branch BPS spectrum of ##IMG##
[] {$\mathcal{N} =4$} super
Yang–Mills theories in four dimensions. Nongravitational theories that are analogous to type IIB
superstring theory in some respects are the (2, 0) six-dimensional theories on the Coulomb branch.
Each of them contains a finite number of half-BPS superstrings, which can be labeled by the root
vectors of the Lie algebra. When the rank is greater than one, these strings can also form string
junctions and string networks. The relationship between ##IMG##
[] {$\mathcal{N} =4$} super
Yang–Mills theorie... 2013/10/25 - 11:20

Charge transfer states around the donor–acceptor interface in an organic solar cell determine the
device performance in terms of the open circuit voltage. In the present work, we propose a
computational scheme based on constrained density functional tight binding theory (c-DFTB) to assess
the energy of the lowest charge transfer (CT) state in such systems. A comparison of the c-DFTB
scheme with Hartree–Fock based configuration interaction of singles (CIS) and with time-dependent
density functional theory (TD-DFT) using the hybrid functional B3LYP reveals that CIS and c-DFTB
reproduce the correct Coulomb asymptotics between cationic donor and anionic acceptor
configurations, whereas TD-DFT gives a qualitatively wrong excitation energy. Together with an
embedding scheme accounting for the polarizable medium, this c-DFTB scheme is applied to several
donor–acceptor combinations used in molecular solar cells. The external quantum efficiency of
photovoltaic cells based on zinc phthaloc... 2013/10/19 - 08:50

The theoretical understanding of electron transport in graphene and graphene nanoribbons is
reviewed, emphasizing the help provided by atomic pseudopotentials (self-consistent and empirical)
in determining not only the band structure but also other fundamental transport parameters such as
electron–phonon matrix elements and line-edge roughness scattering. Electron–phonon scattering in
suspended graphene sheets, impurity and remote-phonon scattering in supported and gated graphene,
electron–phonon and line-edge roughness scattering in armchair-edge nanoribbons are reviewed,
keeping in mind the potential use of graphene in devices of the future very large scale integration
technology. 2013/10/19 - 08:50

The class of materials combining high electrical or thermal conductivity, optical transparency and
flexibility is crucial for the development of many future electronic and optoelectronic devices.
Silver nanowire networks show very promising results and represent a viable alternative to the
commonly used, scarce and brittle indium tin oxide. The science and technology research of such
networks are reviewed to provide a better understanding of the physical and chemical properties of
this nanowire-based material while opening attractive new applications. 2013/10/12 - 09:21

During the last decade there has been increasing use of artificial intelligence tools in
nanotechnology research. In this paper we review some of these efforts in the context of
interpreting scanning probe microscopy, the study of biological nanosystems, the classification of
material properties at the nanoscale, theoretical approaches and simulations in nanoscience, and
generally in the design of nanodevices. Current trends and future perspectives in the development of
nanocomputing hardware that can boost artificial-intelligence-based applications are also discussed.
Convergence between artificial intelligence and nanotechnology can shape the path for many
technological developments in the field of information sciences that will rely on new computer
architectures and data representations, hybrid technologies that use biological entities and
nanotechnological devices, bioengineering, neuroscience and a large variety of related disciplines. 2013/10/12 - 09:21

Progress in developing novel gas sensors based on semiconducting metal oxides (SMOX) has been
hindered by the cumbersome fabrication technologies currently employed. They involve time intensive
synthesis procedures for gaining sensitive materials and preparation of the inks employed for
realizing sensing layers. In this paper we review the opportunities offered by the relatively young
method of flame spray pyrolysis, with which it is possible not only to synthesize a broad selection
of SMOX in pure or doped form, but also to simultaneously deposit thick and highly porous gas
sensitive films on a variety of substrates. In less than ten years the properties of nine base
materials have been evaluated for all most relevant target gases and the obtained results are
promising for future development. 2013/10/12 - 09:21

There is increasing interest in the use of nanoparticles (NPs) for biomedical applications. In
particular, nanobiophotonic approaches using fluorescence offers the potential of high sensitivity
and selectivity in applications such as cell imaging and intracellular sensing. In this review, we
focus primarily on the use of fluorescent silica NPs for these applications and, in so doing, aim to
enhance and complement the key recent review articles on these topics. We summarize the main
synthetic approaches, namely the Stöber and microemulsion processes, and, in this context, we deal
with issues in relation to both covalent and physical incorporation of different types of dyes in
the particles. The important issue of NP functionalization for conjugation to biomolecules is
discussed and strategies published in the recent literature are highlighted and evaluated. We cite
recent examples of the use of fluorescent silica NPs for cell imaging in the areas of cancer, stem
cell and infectiou... 2013/10/12 - 09:21

This article discusses the behavior of submonolayer quantum films (He and H 2 ) on graphene and
newly discovered surfaces that are derived from graphene. Among these substrates are graphane
(abbreviated GH), which has an H atom bonded to each C atom, and fluorographene (GF). The subject is
introduced by describing the related problem of monolayer films on graphite. For that case,
extensive experimental and theoretical investigations have revealed that the phase diagrams of the
Bose gases 4 He and para-H 2 are qualitatively similar, differing primarily in a higher
characteristic temperature scale for H 2 than for He. The phase behavior of these films on one side
of pristine graphene, or both sides of free-standing graphene, is expected to be similar to that on
graphite. We point out the possibility of novel phenomena in adsorption on graphene related to the
large flexibility of the graphene sheet, to the non-negligible interaction between at... 2013/10/12 - 09:21

Metallic nanoparticles (MNPs) such as iron oxide and gold nanoparticles are interesting platforms to
build theragnostic nanocarriers which combine both therapeutic and diagnostic functions within a
single nanostructure. Nevertheless, their surface must be functionalized to be suitable for in vivo
applications. Surface functionalization also provides binding sites for targeting ligands, and for
drug loading. This review focuses on the materials and surface chemistry used to build hybrid
nanocarriers that are inorganic cores functionalized with organic materials. The surface state of
the MNPs largely depends on their synthesis routes, and dictates the strategies used for
functionalization. Two main strategies can be found in the literature: the design of core–shell
nanosystems, or embedding nanoparticles in organic materials. Emerging tendencies such as the use of
clusters or alternative coating materials are also described. To present both hydrophilic and
lipophilic nanosys... 2013/10/10 - 09:13

Several classes of biological molecules that transform chemical energy into mechanical work are
known as motor proteins or molecular motors. These nanometer-sized machines operate in noisy
stochastic isothermal environments, strongly supporting fundamental cellular processes such as the
transfer of genetic information, transport, organization and functioning. In the past two decades
motor proteins have become a subject of intense research efforts, aimed at uncovering the
fundamental principles and mechanisms of molecular motor dynamics. In this review, we critically
discuss recent progress in experimental and theoretical studies on motor proteins. Our focus is on
analyzing fundamental concepts and ideas that have been utilized to explain the non-equilibrium
nature and mechanisms of molecular motors. 2013/10/09 - 04:14

A superintegrable system is, roughly speaking, a system that allows more integrals of motion than
degrees of freedom. This review is devoted to finite dimensional classical and quantum
superintegrable systems with scalar potentials and integrals of motion that are polynomials in the
momenta. We present a classification of second-order superintegrable systems in two-dimensional
Riemannian and pseudo-Riemannian spaces. It is based on the study of the quadratic algebras of the
integrals of motion and on the equivalence of different systems under coupling constant
metamorphosis. The determining equations for the existence of integrals of motion of arbitrary order
in real Euclidean space E 2 are presented and partially solved for the case of third-order
integrals. A systematic exposition is given of systems in two and higher dimensional space that
allow integrals of arbitrary order. The algebras of integrals of motions are not necessarily
quadratic but close polynomia... 2013/10/09 - 04:14

The flexoelectric effect is the response of electric polarization to a mechanical strain gradient.
It can be viewed as a higher-order effect with respect to piezoelectricity, which is the response of
polarization to strain itself. However, at the nanoscale, where large strain gradients are expected,
the flexoelectric effect becomes appreciable. Besides, in contrast to the piezoelectric effect,
flexoelectricity is allowed by symmetry in any material. Due to these qualities flexoelectricity has
attracted growing interest during the past decade. Presently, its role in the physics of dielectrics
and semiconductors is widely recognized and the effect is viewed as promising for practical
applications. On the other hand, the available theoretical and experimental results are rather
contradictory, attesting to a limited understanding in the field. This review paper presents a
critical analysis of the current knowledge on the flexoelectricity in common solids, excluding
organic materials ... 2013/10/02 - 17:25

The development of active spintronic devices, such as spin-transistors and spin-diodes, calls for
new materials that are able to efficiently inject the spin-polarized current into group-IV
semiconductors (Ge and Si). In this paper we review recent achievements of the synthesis and the
magnetic properties of Mn 5 Ge 3 /Ge and carbon-doped Mn 5 Ge 3 /Ge heterostructures. We show that
high crystalline quality and threading-dislocation free Mn 5 Ge 3 films can be epitaxially grown on
Ge(111) substrates despite the existence of a misfit as high as 3.7% between two materials. We have
investigated the effect of carbon doping in epitaxial Mn 5 Ge 3 films and show that incorporation of
carbon into interstitial sites of Mn 5 Ge 3 can allow not only enhancement of the magnetic
properties but also an increase of the thermal stability of Mn 5 Ge 3 . Finally, toward the
perspective to... 2013/10/01 - 12:43

Over the last three decades low-dimensional systems have attracted increasing interest both from the
fundamental and technological points of view due to their unique physical and chemical properties.
X-ray absorption spectroscopy (XAS) is a powerful tool for the characterization of such kinds of
systems, owing to its chemical selectivity and high sensitivity in interatomic distance
determination. Moreover, XAS does not require long-range ordering, that is usually absent in
low-dimensional systems. Finally, this technique can simultaneously provide information on
electronic and local structural properties of the nanomaterials, significantly contributing to
clarify the relation between their atomic structure and their peculiar physical properties. This
review provides a general introduction to XAS, discussing the basic theory of the technique, the
most used detection modes, the related experimental setups and some complementary relevant
characterization techniques (diffraction anom... 2013/09/27 - 14:56

Silicon is of great interest for use as the anode material in lithium-ion batteries due to its high
capacity. However, certain properties of silicon, such as a large volume expansion during the
lithiation process and the low diffusion rate of lithium in silicon, result in fast capacity
degradation in limited charge/discharge cycles, especially at high current rate. Therefore, the use
of silicon in real battery applications is limited. The idea of using porous silicon, to a large
extent, addresses the above-mentioned issues simultaneously. In this review, we discuss the merits
of using porous silicon for anodes through both theoretical and experimental study. Recent progress
in the preparation of porous silicon through the template-assisted approach and the non-template
approach have been highlighted. The battery performance in terms of capacity and cyclability of each
structure is evaluated. 2013/09/25 - 21:17

The vast and yet largely unexplored family of graphene materials has great potential for future
electronic devices with novel functionalities. The ability to engineer the electrical and optical
properties in graphene by chemically functionalizing it with a molecule or adatom is widening
considerably the potential applications targeted by graphene. Indeed, functionalized graphene has
been found to be the best known transparent conductor or a wide gap semiconductor. At the same time,
understanding the mechanisms driving the functionalization of graphene with hydrogen is proving to
be of fundamental interest for energy storage devices. Here we discuss recent advances on the
properties and applications of chemically functionalized graphene. 2013/09/17 - 18:10

There is universal agreement between the United Nations and governments from the richest to the
poorest nations that humanity faces unprecedented global challenges relating to sustainable energy,
clean water, low-emission transportation, coping with climate change and natural disasters, and
reclaiming use of land. We have invited researchers from a range of eclectic research areas to
provide a Roadmap of how superconducting technologies could address these major challenges
confronting humanity. Superconductivity has, over the century since its discovery by Kamerlingh
Onnes in 1911, promised to provide solutions to many challenges. So far, most superconducting
technologies are esoteric systems that are used in laboratories and hospitals. Large science
projects have long appreciated the ability of superconductivity to efficiently create high magnetic
fields that are otherwise very costly to achieve with ordinary materials. The most successful
applications outside of large sci... 2013/09/16 - 13:33

At present we are witnessing a rapid development of sources for terahertz (THz) pulses with very
strong electromagnetic fields. These pulses are reaching a stage where they can be used to not only
probe, but also uniquely control a variety of processes that range from fundamental dynamics in
individual atoms and molecules, through phase transitions in solids to a wealth of interactions in
biological materials. In this review, we are presenting an overview of two major directions in the
generation of such radiation. Large-scale accelerator-based sources offer unprecedented pulse
energies coupled with a wide tuning range and extreme repetition rates. Laser-based sources, on the
other hand, are laboratory-scale instruments and thus are very attractive in their availability to
the wide scientific community. The capabilities of different variants of these THz sources are
evaluated and compared with each other. In addition, powerful techniques for the temporal
characterization of THz p... 2013/09/14 - 10:21

The National Ignition Facility (NIF) has been designed, constructed and has recently begun operation
to investigate the ignition of nuclear fusion with a laser with up to 1.8 MJ of energy per pulse.
The concept for fusion ignition on the NIF, as first proposed in 1990, was based on an indirectly
driven spherical capsule of fuel in a high- Z hohlraum cavity filled with low- Z gas (Lindl et al
2004 Phys. Plasmas 11 [] 339 ). The incident laser energy is
converted to x-rays with keV energy on the hohlraums interior wall. The x-rays then impinge on the
surface of the capsule, imploding it and producing the fuel conditions needed for ignition. It was
recognized at the inception that this approach would potentially be susceptible to scattering of the
incident light by the plasma created in the gas and the ablated material in the hohlraum interior.
Prior to initial NIF operations, expectations for laser–plasm... 2013/09/14 - 10:21

In recent years polymer translocation, i.e., transport of polymeric molecules through
nanometer-sized pores and channels embedded in membranes, has witnessed strong advances. It is now
possible to observe single-molecule polymer dynamics during the motion through channels with
unprecedented spatial and temporal resolution. These striking experimental studies have stimulated
many theoretical developments. In this short theory–experiment review, we discuss recent progress in
this field with a strong focus on non-equilibrium aspects of polymer dynamics during the
translocation process. 2013/09/12 - 06:29

Innovations in relevant micro-contact areas are highlighted, these include, design, contact
resistance modeling, contact materials, performance and reliability. For each area the basic theory
and relevant innovations are explored. A brief comparison of actuation methods is provided to show
why electrostatic actuation is most commonly used by radio frequency microelectromechanical systems
designers. An examination of the important characteristics of the contact interface such as modeling
and material choice is discussed. Micro-contact resistance models based on plastic, elastic-plastic
and elastic deformations are reviewed. Much of the modeling for metal contact micro-switches centers
around contact area and surface roughness. Surface roughness and its effect on contact area is
stressed when considering micro-contact resistance modeling. Finite element models and various
approaches for describing surface roughness are compared. Different contact materials to include
gold, gold all... 2013/09/12 - 06:29

Interferometric detectors will very soon give us an unprecedented view of the gravitational-wave
sky, and in particular of the explosive and transient Universe. Now is the time to challenge our
theoretical understanding of short-duration gravitational-wave signatures from cataclysmic events,
their connection to more traditional electromagnetic and particle astrophysics, and the data
analysis techniques that will make the observations a reality. This paper summarizes the state of
the art, future science opportunities, and current challenges in understanding gravitational-wave
transients. 2013/09/06 - 15:48

Valid ideas that physical reality is vastly larger than human perception of it, and that the
perceived part may not be representative of the whole, exist on many levels and have a long history.
After a brief general inventory of those ideas and their implications, I consider the cosmological
‘multiverse’ much discussed in recent scientific literature. I review its theoretical and (broadly)
empirical motivations, and its disruptive implications for the traditional program of fundamental
physics. I discuss the inflationary axion cosmology, which provides an example where firmly rooted,
plausible ideas from microphysics lead to a well-characterized ‘mini-multiverse’ scenario, with
testable phenomenological consequences. 2013/09/05 - 03:39