215 research outputs found
A family of generalized quantum entropies: definition and properties
We present a quantum version of the generalized -entropies,
introduced by Salicr\'u \textit{et al.} for the study of classical probability
distributions. We establish their basic properties, and show that already known
quantum entropies such as von Neumann, and quantum versions of R\'enyi,
Tsallis, and unified entropies, constitute particular classes of the present
general quantum Salicr\'u form. We exhibit that majorization plays a key role
in explaining most of their common features. We give a characterization of the
quantum -entropies under the action of quantum operations, and study
their properties for composite systems. We apply these generalized entropies to
the problem of detection of quantum entanglement, and introduce a discussion on
possible generalized conditional entropies as well.Comment: 26 pages, 1 figure. Close to published versio
Indistinguishability right from the start in standard quantum mechanics
We discuss a reconstruction of standard quantum mechanics assuming
indistinguishability right from the start, by appealing to quasi-set theory.
After recalling the fundamental aspects of the construction and introducing
some improvements in the original formulation, we extract some conclusions for
the interpretation of quantum theory
A quantum logical and geometrical approach to the study of improper mixtures
We study improper mixtures from a quantum logical and geometrical point of
view. Taking into account the fact that improper mixtures do not admit an
ignorance interpretation and must be considered as states in their own right,
we do not follow the standard approach which considers improper mixtures as
measures over the algebra of projections. Instead of it, we use the convex set
of states in order to construct a new lattice whose atoms are all physical
states: pure states and improper mixtures. This is done in order to overcome
one of the problems which appear in the standard quantum logical formalism,
namely, that for a subsystem of a larger system in an entangled state, the
conjunction of all actual properties of the subsystem does not yield its actual
state. In fact, its state is an improper mixture and cannot be represented in
the von Neumann lattice as a minimal property which determines all other
properties as is the case for pure states or classical systems. The new lattice
also contains all propositions of the von Neumann lattice. We argue that this
extension expresses in an algebraic form the fact that -alike the classical
case- quantum interactions produce non trivial correlations between the
systems. Finally, we study the maps which can be defined between the extended
lattice of a compound system and the lattices of its subsystems.Comment: submitted to the Journal of Mathematical Physic
On the lattice structure of probability spaces in quantum mechanics
Let C be the set of all possible quantum states. We study the convex subsets
of C with attention focused on the lattice theoretical structure of these
convex subsets and, as a result, find a framework capable of unifying several
aspects of quantum mechanics, including entanglement and Jaynes' Max-Ent
principle. We also encounter links with entanglement witnesses, which leads to
a new separability criteria expressed in lattice language. We also provide an
extension of a separability criteria based on convex polytopes to the infinite
dimensional case and show that it reveals interesting facets concerning the
geometrical structure of the convex subsets. It is seen that the above
mentioned framework is also capable of generalization to any statistical theory
via the so-called convex operational models' approach. In particular, we show
how to extend the geometrical structure underlying entanglement to any
statistical model, an extension which may be useful for studying correlations
in different generalizations of quantum mechanics.Comment: arXiv admin note: substantial text overlap with arXiv:1008.416
20 T dipoles and Bi-2212: the path to LHC energy upgrade
Increasing the energy of the LHC would require a ring of \sim20 T magnets
using the superconductors Nb3Sn and Bi-2212/Ag. The technology for Bi-2212/Ag
wire, cable, and coil has advanced significantly but is still far short of the
performance needed for such magnets. New technol-ogy for both wire and cable is
under development, which if successful would yield the needed performance.Comment: 5 pages, contribution to the EuCARD-AccNet-EuroLumi Workshop: The
High-Energy Large Hadron Collider, Malta, 14 -- 16 Oct 2010; CERN Yellow
Report CERN-2011-003, pp. 70-7
Akt substrate TBC1D1 regulates GLUT1 expression through the mTOR pathway in 3T3-L1 adipocytes
Multiple studies have suggested that the protein kinase Akt/PKB (protein kinase B) is required for insulin-stimulated glucose transport in skeletal muscle and adipose cells. In an attempt to understand links between Akt activation and glucose transport regulation, we applied mass spectrometry-based proteomics and bioinformatics approaches to identify potential Akt substrates containing the phospho-Akt substrate motif RXRXXpS/T. The present study describes the identification of the Rab GAP (GTPase-activating protein)-domain containing protein TBC1D1 [TBC (Tre-2/Bub2/Cdc16) domain family, member 1], which is closely related to TBC1D4 [TBC domain family, member 4, also denoted AS160 (Akt substrate of 160 kDa)], as an Akt substrate that is phosphorylated at Thr(590). RNAi (RNA interference)-mediated silencing of TBC1D1 elevated basal deoxyglucose uptake by approx. 61% in 3T3-L1 mouse embryo adipocytes, while the suppression of TBC1D4 and RapGAP220 under the same conditions had little effect on basal and insulin-stimulated deoxyglucose uptake. Silencing of TBC1D1 strongly increased expression of the GLUT1 glucose transporter but not GLUT4 in cultured adipocytes, whereas the decrease in TBC1D4 had no effect. Remarkably, loss of TBC1D1 in 3T3-L1 adipocytes activated the mTOR (mammalian target of rapamycin)-p70 S6 protein kinase pathway, and the increase in GLUT1 expression in the cells treated with TBC1D1 siRNA (small interfering RNA) was blocked by the mTOR inhibitor rapamycin. Furthermore, overexpression of the mutant TBC1D1-T590A, lacking the putative Akt/PKB phosphorylation site, inhibited insulin stimulation of p70 S6 kinase phosphorylation at Thr(389), a phosphorylation induced by mTOR. Taken together, our data suggest that TBC1D1 may be involved in controlling GLUT1 glucose transporter expression through the mTOR-p70 S6 kinase pathway
Kulturkammervorrichtung zur Erzeugung von flusslosen und zeitstabilen Gradienten
Kulturkammervorrichtung zur Erzeugung von flusslosen und zeitstabilen Gradienten (1), umfassend eine Beobachtungskammer (2), in der ein Konzentrationsgefüge dreidimensional einstellbar ist, mehrere Versorgungskanäle (4) zur Durchströmung mit einem Versorgungsfluid (10), jeweils eine Trennwand (13) zwischen den Versorgungskanälen (4) und der Beobachtungskammer (2), wobei die Trennwand (13) Poren (5) zur Diffusion von Versorgungsfluid zwischen dem jeweiligen Versorgungskanal (4) und der Beobachtungskammer (2) aufweist, wobei eine erste Anordnung von Versorgungskanälen (4O) oberhalb der Beobachtungskammer (2) und eine zweite Anordnung von Versorgungskanälen (4U) unterhalb der Beobachtungskammer (2) angeordnet sind
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Second-Generation Coil Design of the Nb3Sn low-β Quadrupole for the High Luminosity LHC
As part of the Large Hadron Collider (LHC) Luminosity upgrade program, the U.S.-LHC Accelerator Research Program collaboration and CERN are working together to design and build a 150-mm aperture Nb3Sn quadrupole for the LHC interaction regions. A first series of 1.5-m-long coils was fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new second-generation coil design. In this paper, we review the main characteristics of the first generation coils, describe the modification in coil layout and discuss their impact on parts design and magnet analysis
Material Cycles and Chemicals: Dynamic Material Flow Analysis of Contaminants in Paper Recycling
This study provides
a systematic approach for assessment of contaminants
in materials for recycling. Paper recycling is used as an illustrative
example. Three selected chemicals, bisphenol A (BPA), diethylhexyl
phthalate (DEHP) and mineral oil hydrocarbons (MOHs), are evaluated
within the paper cycle. The approach combines static material flow
analysis (MFA) with dynamic material and substance flow modeling.
The results indicate that phasing out of chemicals is the most effective
measure for reducing chemical contamination. However, this scenario
was also associated with a considerable lag phase (between approximately
one and three decades) before the presence of chemicals in paper products
could be considered insignificant. While improved decontamination
may appear to be an effective way of minimizing chemicals in products,
this may also result in lower production yields. Optimized waste material
source-segregation and collection was the least effective strategy
for reducing chemical contamination, if the overall recycling rates
should be maintained at the current level (approximately 70% for Europe).
The study provides a consistent approach for evaluating contaminant
levels in material cycles. The results clearly indicate that mass-based
recycling targets are not sufficient to ensure high quality material
recycling
The Alkamide trans-Pellitorine Targets PPARÎł via TRPV1 and TRPA1 to Reduce Lipid Accumulation in Developing 3T3-L1 Adipocytes
Adipose tissue is an important endocrine organ in the human body. However, pathological overgrowth is associated with chronic illness. Regulation of adipogenesis and maturation of adipocytes via bioactive compounds in our daily diet has been in focus of research in the past years and showed promising results for agonists of the ion channels transient receptor potential channel (TRP) V1 and A1. Here, we investigated the anti-adipogenic potential and underlying mechanisms of the alkamide trans-pellitorine present in Piper nigrum via TRPV1 and TRPA1 in 3T3-L1 cells. trans-pellitorine was found to suppress mean lipid accumulation, when applied during differentiation and maturation, but also during maturation phase solely of 3T3-L1 cells in a concentration range between 1 nM and 1 μM by up to 8.84 ± 4.97 or 7.49 ± 5.08%, respectively. Blockage of TRPV1 using the specific inhibitor trans-tert-butyl-cyclohexanol demonstrated that the anti-adipogenic activity of trans-pellitorine depends on TRPV1. In addition, blockage of the TRPA1 channel using the antagonist AP-18 showed a TRPA1-dependent signaling in the early to intermediate stages of adipogenesis. On a mechanistic level, treatment with trans-pellitorine during adipogenesis led to reduced PPARγ expression on gene and protein level via activation of TRPV1 and TRPA1, and increased expression of the microRNA mmu-let-7b, which has been associated with reduced PPARγ levels. In addition, cells treated with trans-pellitorine showed decreased expression of the gene encoding for fatty acid synthase, increased expression of microRNA-103 and a decreased short-term fatty acid uptake on the functional level. In summary, these data point to an involvement of the TRPV1 and TRPA1 cation channels in the anti-adipogenic activity of trans-pellitorine via microRNA-let7b and PPARγ. Since trans-pellitorine does not directly activate TRPV1 or TRPA1, an indirect modulation of the channel activity is assumed and warrants further investigation
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