Effects of noise on hysteresis and resonance width in graphene and nanotubes resonators

We investigate the role that noise plays in the hysteretic dynamics of a suspended nanotube or a graphene sheet subject to an oscillating force. We find that not only the size but also the position of the hysteresis region in these systems can be controlled by noise. We also find that nano-resonators act as noise rectifiers: by increasing the noise in the setup, the resonance width of the characteristic peak in these systems is reduced and, as a result, the quality factor is increased.Comment: 15 pages, 6 figures. Sent to PRB (in revision

Cross-Checking Different Sources of Mobility Information

The pervasive use of new mobile devices has allowed a better characterization in space and time of human concentrations and mobility in general. Besides its theoretical interest, describing mobility is of great importance for a number of practical applications ranging from the forecast of disease spreading to the design of new spaces in urban environments. While classical data sources, such as surveys or census, have a limited level of geographical resolution (e.g., districts, municipalities, counties are typically used) or are restricted to generic workdays or weekends, the data coming from mobile devices can be precisely located both in time and space. Most previous works have used a single data source to study human mobility patterns. Here we perform instead a cross-check analysis by comparing results obtained with data collected from three different sources: Twitter, census, and cell phones. The analysis is focused on the urban areas of Barcelona and Madrid, for which data of the three types is available. We assess the correlation between the datasets on different aspects: the spatial distribution of people concentration, the temporal evolution of people density, and the mobility patterns of individuals. Our results show that the three data sources are providing comparable information. Even though the representativeness of Twitter geolocated data is lower than that of mobile phone and census data, the correlations between the population density profiles and mobility patterns detected by the three datasets are close to one in a grid with cells of 2×2 and 1×1 square kilometers. This level of correlation supports the feasibility of interchanging the three data sources at the spatio-temporal scales considered.Partial financial support has been received from the Spanish Ministry of Economy (MINECO) and FEDER (EU) under projects MODASS (FIS2011-24785) and INTENSE@COSYP (FIS2012-30634), and from the EU Commission through projects EUNOIA, LASAGNE and INSIGHT. ML acknowledges funding from the Conselleria d'Educació, Cultura i Universitats of the Government of the Balearic Islands, and JJR from the Ramón y Cajal program of MINECO.Peer Reviewe

On the possibility of electric transport mediated by long living intrinsic localized solectron modes

We consider a polaron Hamiltonian in which not only the lattice and the electron-lattice interactions, but also the electron hopping term is affected by anharmonicity. We find that the one-electron ground states of this system are localized in a wide range of the parameter space. Furthermore, low energy excited states, generated either by additional momenta in the lattice sites or by appropriate initial electron conditions, lead to states constituted by a localized electron density and an associated lattice distortion, which move together through the system, at subsonic or supersonic velocities. Thus we investigate here the localized states above the ground state which correspond to moving electrons. We show that besides the stationary localized electron states (proper polaron states) there exist moving localized solectron states which can be easily excited. The evolution of these localized states suggests their potential as new carriers for fast electric charge transport.Spanish Ministerio de Ciencia e Innovacion e Fundação para a Ciência e Tecnologia (FCT), Portugal

Mobile phone records to feed activity-based travel demand models: MATSim for studying a cordon toll policy in Barcelona

Activity-based models appeared as an answer to the limitations of the traditional trip-based and tour-based four-stage models. The fundamental assumption of activity-based models is that travel demand is originated from people performing their daily activities. This is why they include a consistent representation of time, of the persons and households, time-dependent routing, and microsimulation of travel demand and traffic. In spite of their potential to simulate traffic demand management policies, their practical application is still limited. One of the main reasons is that these models require a huge amount of very detailed input data hard to get with surveys. However, the pervasive use of mobile devices has brought a valuable new source of data. The work presented here has a twofold objective: first, to demonstrate the capability of mobile phone records to feed activity-based transport models, and, second, to assert the advantages of using activity-based models to estimate the effects of traffic demand management policies. Activity diaries for the metropolitan area of Barcelona are reconstructed from mobile phone records. This information is then employed as input for building a transport MATSim model of the city. The model calibration and validation process proves the quality of the activity diaries obtained. The possible impacts of a cordon toll policy applied to two different areas of the city and at different times of the day are then studied. Our results show the way in which the modal share is modified in each of the considered scenarios. The possibility of evaluating the effects of the policy at both aggregated and traveller level, together with the ability of the model to capture policy impacts beyond the cordon toll area confirm the advantages of activity-based models for the evaluation of traffic demand management policies.This work was developed within the framework of the INSIGHT project funded by the EC under the grant agreement no. 611307. AB is funded by the Conselleria d’Educació, Cultura i Universitats of the Government of the Balearic Islands and the European Social Fund. AB and JJR also acknowledge partial funding from the Spanish Ministry of Science, Innovation and Universities, the National Agency for Research Funding AEI and FEDER (EU) under the grant ESOTECOS (FIS2015-63628-C2-2-R) and the Maria de Maeztu program for Units of Excellence in R&D (MDM-2017-0711).Peer reviewe

Corrigendum: Influence of sociodemographic characteristics on human mobility

Human mobility has been traditionally studied using surveys that deliver snapshots of population displacement patterns. The growing accessibility to ICT information from portable digital media has recently opened the possibility of exploring human behavior at high spatio-temporal resolutions. Mobile phone records, geolocated tweets, check-ins from Foursquare or geotagged photos, have contributed to this purpose at different scales, from cities to countries, in different world areas. Many previous works lacked, however, details on the individuals' attributes such as age or gender. In this work, we analyze credit-card records from Barcelona and Madrid and by examining the geolocated credit-card transactions of individuals living in the two provinces, we find that the mobility patterns vary according to gender, age and occupation. Differences in distance traveled and travel purpose are observed between younger and older people, but, curiously, either between males and females of similar age. While mobility displays some generic features, here we show that sociodemographic characteristics play a relevant role and must be taken into account for mobility and epidemiological modelization.Partial financial support has been received from the Spanish Ministry of Economy (MINECO) and FEDER (EU) under projects MODASS (FIS2011-24785) and INTENSE@COSYP (FIS2012-30634), and from the EU Commission through projects EUNOIA, LASAGNE and INSIGHT. The work of ML has been funded under the PD/004/2013 project, from the Conselleria de Educación, Cultura y Universidades of the Government of the Balearic Islands and from the European Social Fund through the Balearic Islands ESF operational program for 2013-2017. JJR acknowledges funding from the Ramón y Cajal program of MINECO.Peer reviewe

Case report: cerebral vein thrombosis after subarachnoid analgesia for labour.

We report a case of sagittal sinus thrombosis occurring after spinal analgesia for labour to highlight the difficulty of such diagnosis in the presence of postpartum atypical headache following regional anesthesia/analgesia.Case ReportsJournal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

PREAMI: Perindopril and remodelling in elderly with acute myocardial infarction: Study rationale and design

Angiotensin-converting enzyme (ACE) inhibitors reduce mortality, the development of remodeling, left ventricular (LV) dysfunction, and ischemic events, both when administered alone as long-term treatment in patients with impaired LV function and/or heart failure (HF) and as short-term treatment, early after acute myocardial infarction (AMI) and/or HF. The few data available on the use of ACE inhibitors in the elderly after AMI are conflicting. Nothing is known about the effects of ACE inhibitors in elderly postinfarction patients with preserved LV function: these patients have a remarkable medium- to long-term mortality and HF incidence after infarction. The aim of this study is to evaluate, in patients with AMI aged ≥65 years, the effects of Perindopril on the combined outcome of death, hospitalization for HF, and heart remodeling, considered to be a ≥8% increase in LV end-diastolic volume (LVEDV). Secondary objectives include the same factors listed in the primary end points hut considered separately. In addition, safety of the drug, ventricular remodeling, and adaptation are being evaluated. A total of 1100 patients with AMI (first episode or reinfarction), aged ≥65 years, and preserved or only moderately depressed LV (LV ejection fraction ≥40%), are to he enrolled and randomly assigned to treatment (8 mg for 12 months of Perindopril or placebo, in double-blind conditions). Clinical assessment is performed at fixed times, and periodic evaluations of (1) ventricular shape, dimensions, and function by quantitative 2-D echocardiography, and (2) heart rate variability and arrhythmias by ambulatory electrocardiographic monitoring are anticipated. The results and conclusions will be available by 2002 year