305 research outputs found
Molybdenum alloying in high-performance flat-rolled steel grades
Considerable progress in developing flat-rolled
steel grades has been made by the Chinese steel industry
over the recent two decades. The increasing demand for
high-performance products to be used in infrastructural
projects as well as in production of consumer and capital
goods has been driving this development until today. The
installation of state-of-the-art steel making and rolling
facilities has provided the possibility of processing the
most advanced steel grades. The production of high-performance steel grades relies on specific alloying elements
of which molybdenum is one of the most powerful. China
is nearly self-sufficient in molybdenum supplies. This
paper highlights the potential and advantages of molybdenum alloying over the entire range of flat-rolled steel
products. Specific aspects of steel property improvement
with respect to particular applications are indicated
Relational EPR
We study the EPR-type correlations from the perspective of the relational
interpretation of quantum mechanics. We argue that these correlations do not
entail any form of 'non-locality', when viewed in the context of this
interpretation. The abandonment of strict Einstein realism implied by the
relational stance permits to reconcile quantum mechanics, completeness,
(operationally defined) separability, and locality.Comment: Revised, published versio
Ultrasound attenuation in gap-anisotropic systems
Transverse ultrasound attenuation provides a weakly-coupled probe of momentum
current correlations in electronic systems. We develop a simple theory for the
interpretation of transverse ultrasound attenuation coefficients in systems
with nodal gap anisotropy. Applying this theory we show how ultrasound can
delineate between extended-s and d-wave scenarios for the cuprate
superconductors.Comment: Uuencode file: 4 pages (Revtex), 3 figures. Some references adde
Distinguishing d-wave from highly anisotropic s-wave superconductors
Systematic impurity doping in the Cu-O plane of the hole-doped cuprate
superconductors may allow one to decide between unconvention al ("d-wave") and
anisotropic conventional ("s-wave") states as possible candidates for the order
parameter in these materials. We show that potential scattering of any strength
always increases the gap minima of such s-wave states, leading to activated
behavior in temperature with characteristic impurity concentration dependence
in observable quantities such as the penetration depth. A magnetic component to
the scattering may destroy the energy gap and give rise to conventional gapless
behavior, or lead to a nonmonotonic dependence of the gap on impurity
concentration. We discuss how experiments constrain this analysis.Comment: 5 page
Interactions, Distribution of Pinning Energies, and Transport in the Bose Glass Phase of Vortices in Superconductors
We study the ground state and low energy excitations of vortices pinned to
columnar defects in superconductors, taking into account the long--range
interaction between the fluxons. We consider the ``underfilled'' situation in
the Bose glass phase, where each flux line is attached to one of the defects,
while some pins remain unoccupied. By exploiting an analogy with disordered
semiconductors, we calculate the spatial configurations in the ground state, as
well as the distribution of pinning energies, using a zero--temperature Monte
Carlo algorithm minimizing the total energy with respect to all possible
one--vortex transfers. Intervortex repulsion leads to strong correlations
whenever the London penetration depth exceeds the fluxon spacing. A pronounced
peak appears in the static structure factor for low filling fractions . Interactions lead to a broad Coulomb gap in the distribution of
pinning energies near the chemical potential , separating
the occupied and empty pins. The vanishing of at leads to a
considerable reduction of variable--range hopping vortex transport by
correlated flux line pinning.Comment: 16 pages (twocolumn), revtex, 16 figures not appended, please contact
[email protected]
Dynamic generation of maximally entangled photon multiplets by adiabatic passage
The adiabatic passage scheme for quantum state synthesis, in which atomic
Zeeman coherences are mapped to photon states in an optical cavity, is extended
to the general case of two degenerate cavity modes with orthogonal
polarization. Analytical calculations of the dressed-state structure and Monte
Carlo wave-function simulations of the system dynamics show that, for a
suitably chosen cavity detuning, it is possible to generate states of photon
multiplets that are maximally entangled in polarization. These states display
nonclassical correlations of the type described by Greenberger, Horne, and
Zeilinger (GHZ). An experimental scheme to realize a GHZ measurement using
coincidence detection of the photons escaping from the cavity is proposed. The
correlations are found to originate in the dynamics of the adiabatic passage
and persist even if cavity decay and GHZ state synthesis compete on the same
time scale. Beyond entangled field states, it is also possible to generate
entanglement between photons and the atom by using a different atomic
transition and initial Zeeman state.Comment: 22 pages (RevTeX), including 23 postscript figures. To be published
in Physical Review
QED3 theory of underdoped high temperature superconductors
Low-energy theory of d-wave quasiparticles coupled to fluctuating vortex
loops that describes the loss of phase coherence in a two dimensional d-wave
superconductor at T=0 is derived. The theory has the form of 2+1 dimensional
quantum electrodynamics (QED3), and is proposed as an effective description of
the T=0 superconductor-insulator transition in underdoped cuprates. The
coupling constant ("charge") in this theory is proportional to the dual order
parameter of the XY model, which is assumed to be describing the quantum
fluctuations of the phase of the superconducting order parameter. The principal
result is that the destruction of phase coherence in d-wave superconductors
typically, and immediately, leads to antiferromagnetism. The transition can be
understood in terms of the spontaneous breaking of an approximate "chiral"
SU(2) symmetry, which may be discerned at low enough energies in the standard
d-wave superconductor. The mechanism of the symmetry breaking is analogous to
the dynamical mass generation in the QED3, with the "mass" here being
proportional to staggered magnetization. Other insulating phases that break
chiral symmetry include the translationally invariant "d+ip" and "d+is"
insulators, and various one dimensional charge-density and spin-density waves.
The theory offers an explanation for the rounded d-wave-like dispersion seen in
ARPES experiments on Ca2CuO2Cl2 (F. Ronning et. al., Science 282, 2067 (1998)).Comment: Revtex, 20 pages, 5 figures; this is a much extended follow-up to the
Phys. Rev. Lett. vol.88, 047006 (2002) (cond-mat/0110188); improved
presentation, many additional explanations, comments, and references added,
sec. IV rewritten. Final version, to appear in Phys. Rev.
Quantum Mechanics from Focusing and Symmetry
A foundation of quantum mechanics based on the concepts of focusing and
symmetry is proposed. Focusing is connected to c-variables - inaccessible
conceptually derived variables; several examples of such variables are given.
The focus is then on a maximal accessible parameter, a function of the common
c-variable. Symmetry is introduced via a group acting on the c-variable. From
this, the Hilbert space is constructed and state vectors and operators are
given a clear interpretation. The Born formula is proved from weak assumptions,
and from this the usual rules of quantum mechanics are derived. Several
paradoxes and other issues of quantum theory are discussed.Comment: 26 page
The amyloid precursor protein controls PIKfyve function
While the Amyloid Precursor Protein (APP) plays a central role in Alzheimer's disease, its cellular function still remains largely unclear. It was our goal to establish APP function which will provide insights into APP's implication in Alzheimer's disease. Using our recently developed proteo-liposome assay we established the interactome of APP's intracellular domain (known as AICD), thereby identifying novel APP interactors that provide mechanistic insights into APP function. By combining biochemical, cell biological and genetic approaches we validated the functional significance of one of these novel interactors. Here we show that APP binds the PIKfyve complex, an essential kinase for the synthesis of the endosomal phosphoinositide phosphatidylinositol-3,5-bisphosphate. This signalling lipid plays a crucial role in endosomal homeostasis and receptor sorting. Loss of PIKfyve function by mutation causes profound neurodegeneration in mammals. Using C. elegans genetics we demonstrate that APP functionally cooperates with PIKfyve in vivo. This regulation is required for maintaining endosomal and neuronal function. Our findings establish an unexpected role for APP in the regulation of endosomal phosphoinositide metabolism with dramatic consequences for endosomal biology and important implications for our understanding of Alzheimer's disease
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