1,294 research outputs found
Where is the length effect? A cross-linguistic study.
Many models of speech production assume that one cannot begin to articulate a word before all its segmental units are inserted into the articulatory plan. Moreover, some of these models assume that segments are serially inserted from left to right. As a consequence, latencies to name words should increase with word length. In a series of five experiments, however, we showed that the time to name a picture or retrieve a word associated with a symbol is not affected by the length of the word. Experiments 1 and 2 used French materials and participants, while Experiments 3, 4 and 5 were conducted with English materials and participants. These results are discussed in relation to current models of speech production, and previous reports of length effects are reevaluated in light of these findings. We conclude that if words are encoded serially, then articulation can start before an entire phonological word has been encoded
Marine sterols side-chain-oxygenated sterols possibly of abiotic origin from the new Caledonian sponge Stelodoryx chlorophylla
Error characterization in Quantum Information Processing: a protocol for analyzing spatial correlations and its experimental implementation
We present a protocol for error characterization and its experimental
implementation with 4 qubits in liquid state NMR. The method is designed to
retrieve information about spatial correlations and scales as , where
is the maximum number of qubits that have non-negligible interaction. We
discuss the practical aspects regarding accuracy and implementation.Comment: Added extra comments to version 2. Accepted in PR
Vascular endothelial growth factor-A and Poly(A) binding protein-interacting protein 2 expression in human head and neck carcinomas: correlation and prognostic significance
Vascular endothelial growth factor-A (VEGF-A) has been demonstrated to play an important role in tumour angiogenesis and to influence prognosis in many cancers. However its prognostic value in head and neck squamous cell carcinomas (HNSCCs) remains controversial. Therefore, we investigated the clinical relevance of VEGF-A expression in HNSCCs and analysed whether its expression was associated with PAIP2 protein levels, a VEGF-A mRNA-binding partner that strongly regulates VEGF-A expression in tissue culture. We determined the correlation of VEGF-A and PAIP2 protein levels, quantitatively evaluated in tumour tissue homogenates from 54 patients with HNSCC, to clinicopathological parameters. We showed that VEGF-A expression in HNSCC is correlated to the stage of tumour differentiation (P=0.050) and is an independent prognostic factor for progression-free survival (P=0.001) and overall survival (P=0.0004). In a pharynx carcinoma cell line, we demonstrated by RNA interference that VEGF-A expression is closely controlled by PAIP2. Moreover, in human HNSCCs, VEGF-A expression is significantly correlated to PAIP2 protein levels (P=0.0018). Nevertheless, PAIP2 expression is associated with neither clinicopathological factors nor patient's survival. Our data suggest that, in contrast to PAIP2 protein levels, which are unrelated to tumour prognosis, VEGF-A expression could serve as a prognostic marker in head and neck cancer and may be helpful for targeted therapies
Randomized benchmarking of single and multi-qubit control in liquid-state NMR quantum information processing
Being able to quantify the level of coherent control in a proposed device
implementing a quantum information processor (QIP) is an important task for
both comparing different devices and assessing a device's prospects with
regards to achieving fault-tolerant quantum control. We implement in a
liquid-state nuclear magnetic resonance QIP the randomized benchmarking
protocol presented by Knill et al (PRA 77: 012307 (2008)). We report an error
per randomized pulse of with a
single qubit QIP and show an experimentally relevant error model where the
randomized benchmarking gives a signature fidelity decay which is not possible
to interpret as a single error per gate. We explore and experimentally
investigate multi-qubit extensions of this protocol and report an average error
rate for one and two qubit gates of for a three
qubit QIP. We estimate that these error rates are still not decoherence limited
and thus can be improved with modifications to the control hardware and
software.Comment: 10 pages, 6 figures, submitted versio
Fully Explorable Horned Particles Hiding Charge
The charge-hiding effect by a horned particle, which was studied for the case
where gravity/gauge-field system is self-consistently interacting with a
charged lightlike brane (LLB) as a matter source, is now studied for the case
of a time like brane. From the demand that no surfaces of infinite coordinate
time redshift (horizons) appear in the problem we are lead now to a completly
explorable horned particle space for traveller that goes through the horned
particle (as was the case for the LLB) but now also in addition to this, the
horned region is fully visible to a static external observer. This requires
negative surface energy density for the shell sitting at the throat. We study a
gauge field subsystem which is of a special non-linear form containing a
square-root of the Maxwell term and which previously has been shown to produce
a QCD-like confining gauge field dynamics in flat space-time. The condition of
finite energy of the system or asymptotic flatness on one side of the horned
particle implies that the charged object sitting at the throat expels all the
flux it produces into the other side of the horned particle, which turns out to
be of a "tube-like" nature. An outside observer in the asymptotically flat
universe detects, therefore, apparently neutral object. The hiding of the
electric flux behind the tube-like region of a horned particle is the only
possible way that a truly charged particle can still be of finite energy, in a
theory that in flat space describes confinement. This points to the physical
relevance of such solutions, even though there is the need of negative energy
density at the throat of the horned particle, which can be of quantum
mechanical origin.Comment: The new version has been accepted for publication in Classical and
Quantum Gravity. Title changed to "Fully Explorable Horned Particles Hiding
Charge". Horned Particles terminology is used now instead of "wormholes" to
dscribe the solutions here. arXiv admin note: text overlap with
arXiv:1108.373
Tumor Growth Rate Determines the Timing of Optimal Chronomodulated Treatment Schedules
In host and cancer tissues, drug metabolism and susceptibility to drugs vary in a circadian (24 h) manner. In particular, the efficacy of a cell cycle specific (CCS) cytotoxic agent is affected by the daily modulation of cell cycle activity in the target tissues. Anti-cancer chronotherapy, in which treatments are administered at a particular time each day, aims at exploiting these biological rhythms to reduce toxicity and improve efficacy of the treatment. The circadian status, which is the timing of physiological and behavioral activity relative to daily environmental cues, largely determines the best timing of treatments. However, the influence of variations in tumor kinetics has not been considered in determining appropriate treatment schedules. We used a simple model for cell populations under chronomodulated treatment to identify which biological parameters are important for the successful design of a chronotherapy strategy. We show that the duration of the phase of the cell cycle targeted by the treatment and the cell proliferation rate are crucial in determining the best times to administer CCS drugs. Thus, optimal treatment times depend not only on the circadian status of the patient but also on the cell cycle kinetics of the tumor. Then, we developed a theoretical analysis of treatment outcome (TATO) to relate the circadian status and cell cycle kinetic parameters to the treatment outcomes. We show that the best and the worst CCS drug administration schedules are those with 24 h intervals, implying that 24 h chronomodulated treatments can be ineffective or even harmful if administered at wrong circadian times. We show that for certain tumors, administration times at intervals different from 24 h may reduce these risks without compromising overall efficacy
Second Hopf map and Yang-Coulomb system on 5d (pseudo)sphere
Using the second Hopf map, we perform the reduction of the eight-dimensional
(pseudo)spherical (Higgs)oscillator to a five-dimensional system interacting
with a Yang monopole. Then, using a standard trick, we obtain, from the latter
system, the pseudospherical and spherical generalizations of the Yang-Coulomb
system (the five dimensional analog of MICZ-Kepler system). We present the
whole set of its constants of motions, including the hidden symmetry generators
given by the analog of Runge-Lenz vector. In the same way, starting from the
eight-dimensional anisotropic inharmonic Higgs oscillator, we construct the
integrable (pseudo)spherical generalization of the Yang-Coulomb system with the
Stark term.Comment: 10 pages, PACS: 03.65.-w, 02.30.Ik, 14.80.H
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