Delocalization transition for the Google matrix

We study the localization properties of eigenvectors of the Google matrix, generated both from the World Wide Web and from the Albert-Barabasi model of networks. We establish the emergence of a delocalization phase for the PageRank vector when network parameters are changed. In the phase of localized PageRank, a delocalization takes place in the complex plane of eigenvalues of the matrix, leading to delocalized relaxation modes. We argue that the efficiency of information retrieval by Google-type search is strongly affected in the phase of delocalized PageRank.Comment: 4 pages, 5 figures. Research done at http://www.quantware.ups-tlse.fr

Quantum chaos algorithms and dissipative decoherence with quantum trajectories

Using the methods of quantum trajectories we investigate the effects of dissipative decoherence in a quantum computer algorithm simulating dynamics in various regimes of quantum chaos including dynamical localization, quantum ergodic regime and quasi-integrable motion. As an example we use the quantum sawtooth algorithm which can be implemented in a polynomial number of quantum gates. It is shown that the fidelity of quantum computation decays exponentially with time and that the decay rate is proportional to the number of qubits, number of quantum gates and per gate dissipation rate induced by external decoherence. In the limit of strong dissipation the quantum algorithm generates a quantum attractor which may have complex or simple structure. We also compare the effects of dissipative decoherence with the effects of static imperfections.Comment: 6 pages, 6 figs, research at http://www.quantware.ups-tlse.f

The Role of the Visual Association Cortex in Scaffolding Prefrontal Cortex Development: A Novel Mechanism Linking Socioeconomic Status and Executive Function

Socioeconomic status (SES) is associated with executive function (EF) and prefrontal cortex (PFC) development. However, understanding of the specific aspects of SES that influence development of EF and the PFC remains limited. We briefly review existing literature on proposed mechanisms linking SES with EF. Then, we present a novel conceptual model arguing that early cognitive stimulation shapes EF and PFC development. We propose that cognitive stimulation drives lower-level sensory and perceptual processes that may impact EF and PFC development through reciprocal connections between the ventral visual stream and PFC. We argue that caregivers guide attention and associative learning, which provides children the opportunity to regulate attention and gain semantic knowledge. This experience in turn allows for opportunities to train the PFC to resolve conflict between stimuli with overlapping features and engage in increasingly complex computations as visual processing systems develop; this may lay the groundwork for development of EF. We review existing evidence for this model and end by highlighting how this conceptual model could launch future research questions

Tubulin bond energies and microtubule biomechanics determined from nanoindentation in silico

Microtubules, the primary components of the chromosome segregation machinery, are stabilized by longitudinal and lateral non-covalent bonds between the tubulin subunits. However, the thermodynamics of these bonds and the microtubule physico-chemical properties are poorly understood. Here, we explore the biomechanics of microtubule polymers using multiscale computational modeling and nanoindentations in silico of a contiguous microtubule fragment. A close match between the simulated and experimental force-deformation spectra enabled us to correlate the microtubule biomechanics with dynamic structural transitions at the nanoscale. Our mechanical testing revealed that the compressed MT behaves as a system of rigid elements interconnected through a network of lateral and longitudinal elastic bonds. The initial regime of continuous elastic deformation of the microtubule is followed by the transition regime, during which the microtubule lattice undergoes discrete structural changes, which include first the reversible dissociation of lateral bonds followed by irreversible dissociation of the longitudinal bonds. We have determined the free energies of dissociation of the lateral (6.9+/-0.4 kcal/mol) and longitudinal (14.9+/-1.5 kcal/mol) tubulin-tubulin bonds. These values in conjunction with the large flexural rigidity of tubulin protofilaments obtained (18,000-26,000 pN*nm^2), support the idea that the disassembling microtubule is capable of generating a large mechanical force to move chromosomes during cell division. Our computational modeling offers a comprehensive quantitative platform to link molecular tubulin characteristics with the physiological behavior of microtubules. The developed in silico nanoindentation method provides a powerful tool for the exploration of biomechanical properties of other cytoskeletal and multiprotein assemblie

Effects of imperfections for Shor's factorization algorithm

We study effects of imperfections induced by residual couplings between qubits on the accuracy of Shor's algorithm using numerical simulations of realistic quantum computations with up to 30 qubits. The factoring of numbers up to N=943 show that the width of peaks, which frequencies allow to determine the factors, grow exponentially with the number of qubits. However, the algorithm remains operational up to a critical coupling strength $\epsilon_c$ which drops only polynomially with $\log_2 N$. The numerical dependence of $\epsilon_c$ on $\log_2 N$ is explained by analytical estimates that allows to obtain the scaling for functionality of Shor's algorithm on realistic quantum computers with a large number of qubits.Comment: 10 pages, 10 figures, 1 table. Added references and new data. Erratum added as appendix. 1 Figure and 1 Table added. Research is available at http://www.quantware.ups-tlse.fr

Development of the Persuasion Knowledge Scales of Sponsored Content (PKS-SC)

Despite the popularity of the Persuasion Knowledge Model, and its persistent relevance given the omnipresence of sponsored content (e.g. brand placement in TV programmes and video games, or paid product reviews in blogs), the way scholars measure persuasion knowledge varies widely. This study aims to develop valid and reliable scales for standardized measurement of consumers' persuasion knowledge of sponsored content. In three phases, we developed the Persuasion Knowledge Scales of Sponsored Content (PKS-SC) that measures nine components: (1) recognition of sponsored content, (2) understanding of selling and persuasive intent, (3) recognition of the commercial source of sponsored content, (4) understanding of persuasive tactics, (5) understanding of the economic model, (6) self-reflective awareness of the effectiveness of sponsored content, (7) skepticism toward sponsored content, (8) appropriateness of sponsored content, and (9) liking of sponsored content. All scales have good to appropriate validity and reliability. Recommendations for future research are discussed.</p

Quantum localization in rough billiards

We study the level spacing statistics p(s) and eigenfunction properties in a billiard with a rough boundary. Quantum effects lead to localization of classical diffusion in the angular momentum space and the Shnirelman peak in p(s) at small s. The ergodic regime with Wigner-Dyson statistics is identified as a function of roughness. Applications for the Q-spoiling in optical resonators are also discussed.Comment: revtex, 4 pages, 5 figure

Dissipative quantum chaos: transition from wave packet collapse to explosion

Using the quantum trajectories approach we study the quantum dynamics of a dissipative chaotic system described by the Zaslavsky map. For strong dissipation the quantum wave function in the phase space collapses onto a compact packet which follows classical chaotic dynamics and whose area is proportional to the Planck constant. At weak dissipation the exponential instability of quantum dynamics on the Ehrenfest time scale dominates and leads to wave packet explosion. The transition from collapse to explosion takes place when the dissipation time scale exceeds the Ehrenfest time. For integrable nonlinear dynamics the explosion practically disappears leaving place to collapse.Comment: 4 pages, 4 figure

Dynamical Localization: Hydrogen Atoms in Magnetic and Microwave fields

We show that dynamical localization for excited hydrogen atoms in magnetic and microwave fields takes place at quite low microwave frequency much lower than the Kepler frequency. The estimates of localization length are given for different parameter regimes, showing that the quantum delocalization border drops significantly as compared to the case of zero magnetic field. This opens up broad possibilities for laboratory investigations.Comment: revtex, 11 pages, 3 figures, to appear in Phys. Rev. A, Feb (1997

Effects of training on reticulated reactive platelets and erytrocyte fragments in patients with peripheral atherosclerosis.

Background: training is a documented effective treatment in patients affected from peripheral arterial disease (PAD). Platelet activation plays a pivotal role in atherosclerosis progression and cardiovascular events. Reticulated platelets (IPF) reflects activity of bone marrow , recently they have been associated to cardiovascular complications and atherosclerosis with unstable conditions (e.g. acute coronary syndrome). Presence of a width blood red cell distribution is considered recently as a prognostic factor for coronary artery disease, a high RDW value depends greatly on presence of red blood cells fragmentation (FRC); this parameter may depend on different conditions such as inflammation, and oxidation and is connected with different risk factors such as hypertension and diabetes. Few data can be found for patients with peripheral arterial disease on training. We aimed to evaluate the effects of aerobic training on IPF and FRC at rest and after maximal walking exercise before and after training. Methods and Results: we enrolled 12 patients with intermittent claudication. They were submitted to a 15 days aerobic training period (cycling and treadmill exercise under maximal walking capacity). IPF, MPV, PLT count and FRC were analyzed at rest, 1 hour after maximal treadmill test and after 24 hours, these evaluations were performed at the beginning and at the end of the training period. The Lab parameters were analyzed with impedentiometry, fluorimetry (oxazyne) and optical methods (Sysmex Xn-1000, Sysmex Corporation, Kobe, Japan). Walking distance was measured with treadmill (3,2 km/h, 2-10% slope), maximal test was prolonged to the maximal tolerated claudication pain. Platelets count was within normal range (216,9 \ub1 40 109/l ) and did not changed throughout the study; also MPV was unchanged (11,6\ub11,9 vs 11.45\ub10,8 fl ) before and after the training ; plateletcrit was slightly reduced (0,246\ub10,061 vs 0,282 \ub10,018 %). IPF count (figure) slightly changed during maximal stress at the beginning of training with increase after 24 hours; after training the count decreased significantly (*p<0,05) at rest and 1 hour after, while it increased significantly after 24 hours (** p<0,05 vs rest ad vs 24 h-pre) but less than before training. FRC decreased after triaining (0,381\ub10,121 vs 0,542\ub10,220 %; p<0,05), maximal test slightly increased FRC after 1 hour , no significant change after 24 hours. At the end of training, absolute walking distance increased (450\ub1180 vs 250\ub1108 m; p<0,05). Discussion: training reduces IPF in patients with peripheral arterial disease, IPF increase after acute maximal test and this phenomenon can be attenuated by training. We also observed a reduction in FRC. Presence of FRC in these patients may be caused by mechanical forces throughout a large surface of atherosclerotic plaques fragmenting red cells, ischemia reperfusion in claudication is another mechanism that can elicit formation of FRC and in addition high oxidative stress may contribute. IPF are associated with an increase platelets activity and a higher turnover; in this pathology both these condition can be found associated with oxidative stress, inflammation and endothelial dysfunction. Training improves oxidation, inflammation and endothelium function with favorable effects on platelets activation and turnover, furthermore these parameters may influence also FRC count. Conclusion: training in PAD patients reduces IPF and FRC with potential improvement in risk profile for atherosclerosis progression and reduction of cardiovascular events. References: 1. Cesari F, Marcucci R, Gori AM, et al . Reticulated platelets predict cardiovascular death in acute coronary syndrome patients. Thrombosis and Haemostasis 2013; 109: 846-853. 2. Hoffmann JJ . Reticulated platelets: analytical aspects and clinical utility. Clin Chem Lab. 2014; 52: 1107-17. 3. Bujak K, Wasilewski J, Osadnik T, et al. Prognostic role of red blood cell distribution width in coronary artery disease: a review of the pathophysiology. Disease Markers 2015, vol 1 ; 1-12