1,039 research outputs found
Higher dimensional abelian Chern-Simons theories and their link invariants
The role played by Deligne-Beilinson cohomology in establishing the relation
between Chern-Simons theory and link invariants in dimensions higher than three
is investigated. Deligne-Beilinson cohomology classes provide a natural abelian
Chern-Simons action, non trivial only in dimensions , whose parameter
is quantized. The generalized Wilson -loops are observables of the
theory and their charges are quantized. The Chern-Simons action is then used to
compute invariants for links of -loops, first on closed
-manifolds through a novel geometric computation, then on
through an unconventional field theoretic computation.Comment: 40 page
Domino D3.1 - Architecture definition
This deliverable presents the concept of operation of Domino. It includes a description of the systems, subsystems and processes that will be taken into account in the model, as well as the general scope of the model. For each of the mechanisms suggested to be modelled in the project, the deliverable provides a set of possible operational concepts and uptake/scope to be deployed
The heavy fermion damping rate puzzle
: We examine again the problem of the damping rate of a moving heavy fermion
in a hot plasma within the resummed perturbative theory of Pisarski and
Braaten. The ansatz for its evaluation which relates it to the imaginary part
of the fermion propagator pole in the framework of a self-consistent approach
is critically analyzed. As already pointed out by various authors, the only way
to define the rate is through additional implementation of magnetic screening.
We show in detail how the ansatz works in this case and where we disagree with
other authors. We conclude that the self-consistent approach is not
satisfactory.Comment: 17 page
Observation of a warped helical spin-texture in BiSe from circular dichroism angle-resolved photoemission spectroscopy
A differential coupling of topological surface states to left- versus
right-circularly polarized light is the basis of many opto-spintronics
applications of topological insulators. Here we report direct evidence of
circular dichroism from the surface states of BiSe using a laser-based
time-of-flight angle-resolved photoemission spectroscopy. By employing a novel
sample rotational analysis, we resolve unusual modulations in the circular
dichroism photoemission pattern as a function of both energy and momentum,
which perfectly mimic the predicted but hitherto un-observed three-dimensional
warped spin-texture of the surface states. By developing a microscopic theory
of photoemission from topological surface states, we show that this correlation
is a natural consequence of spin-orbit coupling. These results suggest that our
technique may be a powerful probe of the spin-texture of spin-orbit coupled
materials in general.Comment: 16 pages, 4 figure
eIF4A inhibitors suppress cell-cycle feedback response and acquired resistance to CDK4/6 inhibition in cancer
CDK4/6 inhibitors are FDA-approved drugs for estrogen receptor-positive (ER+) breast cancer and are being evaluated to treat other tumor types, including KRAS-mutant non-small cell lung cancer (NSCLC). However, their clinical utility is often limited by drug resistance. Here, we sought to better understand the resistant mechanisms and help devise potential strategies to overcome this challenge. We show that treatment with CDK4/6 inhibitors in both ER+ breast cancer and KRAS-mutant NSCLC cells induces feedback upregulation of cyclin D1, CDK4, and cyclin E1, mediating drug resistance. We demonstrate that rocaglates, which preferentially target translation of key cell-cycle regulators, effectively suppress this feedback upregulation induced by CDK4/6 inhibition. Consequently, combination treatment of CDK4/6 inhibitor palbociclib with the eukaryotic initiation factor (eIF) 4A inhibitor, CR-1-31-B, is synergistic in suppressing the growth of these cancer cells in vitro and in vivo Furthermore, ER+ breast cancer and KRAS-mutant NSCLC cells that acquired resistance to palbociclib after chronic drug exposure are also highly sensitive to this combination treatment strategy. Our findings reveal a novel strategy using eIF4A inhibitors to suppress cell-cycle feedback response and to overcome resistance to CDK4/6 inhibition in cancer.Accepted manuscrip
The protein import apparatus of chloroplasts
Routing of cytosolically synthesized precursor proteins into chloroplasts is a specific process which involves a multitude of soluble and membrane components. In this review we wil1 focus on early events of the translocation pathway of nuclear coded plastidic precursor proteins and compare import routes for polypeptide of the outer chloroplast envelope to that of internal chloroplast compartments. A number of proteins housed in the chloroplast envelopes have been implied to be involved in the translocation process, but so far a certain function has not been assigned to any of these proteins. The only exception could be an envelope localized hsc 70 homologue which could retain the import competence of a precursor protein in transit into the organelle
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