113 research outputs found
Portfolio performance across genders and generations : the role of financial innovation
Using a unique dataset on the trading transaction records of private investors from Sweden, we explore the role of gender and age in the use of Exchange Traded Products (ETPs), considered to be innovative investment products, with respect to implications for portfolio performance. We show evidence that investors perform better when trading and investing in mutual funds, but younger investors may be relatively more skillful users of ETPs. We also find that older men and women trade more actively, although they also show a better investment performance, and we emphasize that age and gender are very different demographic determinants of investor behavior and performance.fi=vertaisarvioitu|en=peerReviewed
Intelligent Database Architecture for High-Integrity Urban Navigation
Accuracy, integrity and availability requirements are very stringent in urban navigation and autonomous driving. The GNSS sensor is the only one that provides self-localisation in a global coordinate system.
The challenge ist to model non line-of-sight (NLOS) and multipath scenarios in urban areas. To meeth the high accuracy requirements, these distortions has to be known and corrected. Ray-tracing approaches are real-time capable but require a high computational load.
The vision for this contribution is the correction of GNSS multipath for relaiable autonomous localisation of highly automated vehicles using an intelligent database structure
Von der ko-kreativen Stadtentwicklung bis zum Transfer
Welche Bedarfe, Ideen und Lösungen sehen hochqualifizierte Migrant/innen für eine nachhaltigeStadtentwicklung? Inwiefern eignet sich Urban Design Thinking als ko-kreative Methode und Impuls für städtische Transformationsprozesse? In einem Fallbeispiel in Mannheim wurden ersteAnsätze erprobt
Residual Kondo effect in quantum dot coupled to half-metallic ferromagnets
We study the Kondo effect in a quantum dot coupled to half-metallic
ferromagnetic electrodes in the regime of strong on-dot correlations. Using the
equation of motion technique for nonequilibrium Green functions in the slave
boson representation we show that the Kondo effect is not completely suppressed
for anti-parallel leads magnetization. In the parallel configuration there is
no Kondo effect but there is an effect associated with elastic cotunneling
which in turn leads to similar behavior of the local (on-dot) density of states
(LDOS) as the usual Kondo effect. Namely, the LDOS shows the temperature
dependent resonance at the Fermi energy which splits with the bias voltage and
the magnetic field. Moreover, unlike for non-magnetic or not fully polarized
ferromagnetic leads the only minority spin electrons can form such resonance in
the density of states. However, this resonance cannot be observed directly in
the transport measurements and we give some clues how to identify the effect in
such systems.Comment: 15 pages, 8 figures, accepted for publication in J. Phys.: Condens.
Mat
Supergravities without an Action: Gauging the Trombone
We present a systematic account of supergravity theories in which the global
scaling symmetry is gauged. This generalizes the standard gaugings of
non-abelian off-shell symmetries. A particular feature of these theories is an
additional positive contribution to the effective cosmological constant.
As the scaling symmetry is an on-shell symmetry, the resulting gaugings do no
longer possess an action. We develop the algebraic framework for the maximal
theories in various dimensions and construct explicit solutions to the
algebraic consistency constraints - related to `pure-spinor-like' structures
for the exceptional groups. As an example, we explicitly work out the modified
supersymmetry transformation rules and equations of motion in three dimensions.
Finally, we speculate about the role of these theories from the perspective of
very extended Kac-Moody algebras.Comment: 40 pages; v2: refs added, minor corrections, version to be published
in NP
Functional association of the stress-responsive LiaH protein and the minimal TatAyCy protein translocase in Bacillus subtilis
The bacterial twin-arginine (Tat) pathway serves in the exclusive secretion of folded proteins with bound co-factors. While Tat pathways in Gram-negative bacteria and chloroplast thylakoids consist of conserved TatA, TatB and TatC subunits, the Tat pathways of Bacillus species and many other Gram-positive bacteria stand out for their minimalist nature with the core translocase being composed of essential TatA and TatC subunits only. Here we addressed the question whether the minimal TatAyCy translocase of Bacillus subtilis recruits additional cellular components that modulate its activity. To this end, TatAyCy was purified by affinity- and size exclusion chromatography, and interacting co-purified proteins were identified by mass spectrometry. This uncovered the cell envelope stress responsive LiaH protein as an accessory subunit of the TatAyCy complex. Importantly, our functional studies show that Tat expression is tightly trailed by LiaH induction, and that LiaH itself determines the capacity and quality of TatAyCy-dependent protein translocation. In contrast, LiaH has no role in high-level protein secretion via the general secretion (Sec) pathway. Altogether, our observations show that protein translocation by the minimal Tat translocase TatAyCy is tightly intertwined with an adequate bacterial response to cell envelope stress. This is consistent with a critical need to maintain cellular homeostasis, especially when the membrane is widely opened to permit passage of large fully-folded proteins via Tat
A novel de novo TBX5 mutation in a patient with Holt-Oram syndrome leading to a dramatically reduced biological function
BACKGROUND:
The Holt-Oram syndrome (HOS) is an autosomal dominant disorder affecting 1/100.000 live births. It is defined by upper limb anomalies and congenital heart defects with variable severity. We describe a dramatic phenotype of a male, 15-month-old patient being investigated for strict diagnostic criteria of HOS. -----
METHODS AND RESULTS:
Genetic analysis revealed a so far unpublished TBX5 mutation, which occurs de novo in the patient with healthy parents. TBX5 belongs to the large family of T-box transcription factors playing major roles in morphogenesis and cell-type specification. The mutation located in the DNA-binding domain at position 920 (C→A) leads to an amino acid change at position 85 (proline → threonine). Three-dimensional analysis of the protein structure predicted a cis to trans change in the respective peptide bond, thereby probably provoking major conformational and functional alterations of the protein. The p.Pro85Thr mutation showed a dramatically reduced activation (97%) of the NPPA promoter in luciferase assays and failed to induce NPPA expression in HEK 293 cells compared to wild-type TBX5 protein. The mutation did not interfere with the nuclear localization of the protein. -----
CONCLUSION:
These results suggest that the dramatic functional alteration of the p.Pro85Thr mutation leads to the distinctive phenotype of the patient
Defining and controlling double quantum dots in single-walled carbon nanotubes
We report the experimental realization of double quantum dots in
single-walled carbon nanotubes. The device consists of a nanotube with source
and drain contact, and three additional top-gate electrodes in between. We show
that, by energizing these top-gates, it is possible to locally gate a nanotube,
to create a barrier, or to tune the chemical potential of a part of the
nanotube. At low temperatures we find (for three different devices) that in
certain ranges of top-gate voltages our device acts as a double quantum dot,
evidenced by the typical honeycomb charge stability pattern.Comment: 9 pages, 3 figure
Spin effects in single electron tunneling
An important consequence of the discovery of giant magnetoresistance in
metallic magnetic multilayers is a broad interest in spin dependent effects in
electronic transport through magnetic nanostructures. An example of such
systems are tunnel junctions -- single-barrier planar junctions or more complex
ones. In this review we present and discuss recent theoretical results on
electron and spin transport through ferromagnetic mesoscopic junctions
including two or more barriers. Such systems are also called ferromagnetic
single-electron transistors. We start from the situation when the central part
of a device has the form of a magnetic (or nonmagnetic) metallic nanoparticle.
Transport characteristics reveal then single-electron charging effects,
including the Coulomb staircase, Coulomb blockade, and Coulomb oscillations.
Single-electron ferromagnetic transistors based on semiconductor quantum dots
and large molecules (especially carbon nanotubes) are also considered. The main
emphasis is placed on the spin effects due to spin-dependent tunnelling through
the barriers, which gives rise to spin accumulation and tunnel
magnetoresistance. Spin effects also occur in the current-voltage
characteristics, (differential) conductance, shot noise, and others. Transport
characteristics in the two limiting situations of weak and strong coupling are
of particular interest. In the former case we distinguish between the
sequential tunnelling and cotunneling regimes. In the strong coupling regime we
concentrate on the Kondo phenomenon, which in the case of transport through
quantum dots or molecules leads to an enhanced conductance and to a pronounced
zero-bias Kondo peak in the differential conductance.Comment: topical review (36 figures, 65 pages), to be published in J. Phys.:
Condens. Matte
Charge Solitons in 1-D Arrays of Serially Coupled Josephson Junctions
We study a 1-D array of Josephson coupled superconducting grains with kinetic
inductance which dominates over the Josephson inductance. In this limit the
dynamics of excess Cooper pairs in the array is described in terms of charge
solitons, created by polarization of the grains. We analyze the dynamics of
these topological excitations, which are dual to the fluxons in a long
Josephson junction, using the continuum sine-Gordon model. We find that their
classical relativistic motion leads to saturation branches in the I-V
characteristic of the array. We then discuss the semi-classical quantization of
the charge soliton, and show that it is consistent with the large kinetic
inductance of the array. We study the dynamics of a quantum charge soliton in a
ring-shaped array biased by an external flux through its center. If the
dephasing length of the quantum charge soliton is larger than the circumference
of the array, quantum phenomena like persistent current and coherent current
oscillations are expected. As the characteristic width of the charge soliton is
of the order of 100 microns, it is a macroscopic quantum object. We discuss the
dephasing mechanisms which can suppress the quantum behaviour of the charge
soliton.Comment: 26 pages, LaTex, 7 Postscript figure
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