4,160 research outputs found
The subdivision of large simplicial cones in Normaliz
Normaliz is an open-source software for the computation of lattice points in
rational polyhedra, or, in a different language, the solutions of linear
diophantine systems. The two main computational goals are (i) finding a system
of generators of the set of lattice points and (ii) counting elements
degree-wise in a generating function, the Hilbert Series. In the homogeneous
case, in which the polyhedron is a cone, the set of generators is the Hilbert
basis of the intersection of the cone and the lattice, an affine monoid.
We will present some improvements to the Normaliz algorithm by subdividing
simplicial cones with huge volumes. In the first approach the subdivision
points are found by integer programming techniques. For this purpose we
interface to the integer programming solver SCIP to our software. In the second
approach we try to find good subdivision points in an approximating overcone
that is faster to compute.Comment: To appear in the proceedings of the ICMS 2016, published by Springer
as Volume 9725 of Lecture Notes in Computer Science (LNCS
Experimental demonstration of composite stimulated Raman adiabatic passage
We experimentally demonstrate composite stimulated Raman adiabatic passage
(CSTIRAP), which combines the concepts of composite pulse sequences and
adiabatic passage. The technique is applied for population transfer in a
rare-earth doped solid. We compare the performance of CSTIRAP with conventional
single and repeated STIRAP, either in the resonant or the highly detuned
regime. In the latter case, CSTIRAP improves the peak transfer efficiency and
robustness, boosting the transfer efficiency substantially compared to repeated
STIRAP. We also propose and demonstrate a universal version of CSTIRAP, which
shows improved performance compared to the originally proposed composite
version. Our findings pave the way towards new STIRAP applications, which
require repeated excitation cycles, e.g., for momentum transfer in atom optics,
or dynamical decoupling to invert arbitrary superposition states in quantum
memories.Comment: 11 pages, 5 figure
Post-training load-related changes of auditory working memory: An EEG study
Working memory (WM) refers to the temporary retention and manipulation of information, and its capacity is highly susceptible to training. Yet, the neural mechanisms that allow for increased performance under demanding conditions are not fully understood. We expected that post-training efficiency in WM performance modulates neural processing during high load tasks. We tested this hypothesis, using electroencephalography (EEG) (N = 39), by comparing source space spectral power of healthy adults performing low and high load auditory WM tasks. Prior to the assessment, participants either underwent a modality-specific auditory WM training, or a modality-irrelevant tactile WM training, or were not trained (active control). After a modality-specific training participants showed higher behavioral performance, compared to the control. EEG data analysis revealed general effects of WM load, across all training groups, in the theta-, alpha-, and beta-frequency bands. With increased load theta-band power increased over frontal, and decreased over parietal areas. Centro-parietal alpha-band power and central beta-band power decreased with load. Interestingly, in the high load condition a tendency toward reduced beta-band power in the right medial temporal lobe was observed in the modality-specific WM training group compared to the modality-irrelevant and active control groups. Our finding that WM processing during the high load condition changed after modality-specific WM training, showing reduced beta-band activity in voice-selective regions, possibly indicates a more efficient maintenance of task-relevant stimuli. The general load effects suggest that WM performance at high load demands involves complementary mechanisms, combining a strengthening of task-relevant and a suppression of task-irrelevant processing
Equity-Efficiency Optimizing Resource Allocation: The Role of Time Preferences in a Repeated Irrigation Game
We study repeated water allocation decisions among small scale irrigation users in Tanzania. In a treatment replicating water scarcity conditions, convexities in production make that substantial efficiency gains can be obtained by deviating from equal sharing, leading to an equity–efficiency trade-off. In a repeated game setting, it becomes possible to reconcile efficiency with equity by rotating the person who receives the largest share, but such a strategy requires a longer run perspective. Correlating experimental data from an irrigation game with individual time preference data, we find that less patient irrigators are less likely to use a rotation strategy
Linear resolutions of powers and products
The goal of this paper is to present examples of families of homogeneous
ideals in the polynomial ring over a field that satisfy the following
condition: every product of ideals of the family has a linear free resolution.
As we will see, this condition is strongly correlated to good primary
decompositions of the products and good homological and arithmetical properties
of the associated multi-Rees algebras. The following families will be discussed
in detail: polymatroidal ideals, ideals generated by linear forms and Borel
fixed ideals of maximal minors. The main tools are Gr\"obner bases and Sagbi
deformation
JNK inhibition sensitises hepatocellular carcinoma cells but not normal hepatocytes to the TNF-related apoptosis-inducing ligand.
Background: cJun terminal kinase (JNK) is constitutively
activated in most hepatocellular carcinomas (HCCs), yet
its exact role in carcinogenesis remains controversial.
While tumour necrosis factor (TNF)-related apoptosisinducing
ligand (TRAIL) is known as a major mediator of
acquired immune tumour surveillance, and is currently
being tested in clinical trials as a novel cancer therapy,
the resistance of many tumours to TRAIL and concerns
about its toxicity in vivo represent obstacles to its clinical
application. In this study we investigated whether JNK
activity in HCC could contribute to the resistance to
apoptosis in these tumours.
Methods: The effect of JNK/Jun inhibition on receptormediated
apoptosis was analysed by pharmacological
inhibition or RNA interference in cancer cells and nontumour
cells isolated from human liver or transgenic mice
lacking a phosphorylation site for Jun.
Results: JNK inhibition caused cell cycle arrest,
enhanced caspase recruitment, and greatly sensitised
HCC cells but not normal hepatocytes to TRAIL. TRAILinduced
activation of JNK could be effectively interrupted
by administration of the JNK inhibitor SP600125.
Conclusions: Expression and TRAIL-dependent feedback
activation of JNK likely represent a mechanism by which
cancer cells escape TRAIL-mediated tumour surveillance.
JNK inhibition might represent a novel strategy for
specifically sensitising HCC cells to TRAIL thus opening
promising therapeutic perspectives for safe and effective
use of TRAIL in cancer treatment
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