Universal scaling of current fluctuations in disordered graphene

We analyze the full transport statistics of graphene with smooth disorder at low dopings. First we consider the case of 1D disorder for which the transmission probability distribution is given analytically in terms of the graphene-specific mean free path. All current cumulants are shown to scale with system parameters (doping, size, disorder strength and correlation length) in an identical fashion for large enough systems. In the case of 2D disorder, numerical evidence is given for the same kind of identical scaling of all current cumulants, so that the ratio of any two such cumulants is universal. Specific universal values are given for the Fano factor, which is smaller than the pseudodiffusive value of ballistic graphene (F=1/3) both for 1D (F=0.243) and 2D (F=0.295) disorder. On the other hand, conductivity in wide samples is shown to grow without saturation as \sqrt{L} and Log L with system length L in the 1D and 2D cases respectively.Comment: 9 pages, 7 figures. Published version, includes corrected figure for Fano facto

The use of robots in the workplace: Conclusions from a health promoting intervention using social robots

Workplace wellness programs constitute a preventive measure to help avoid healthcare costs for companies, with additional benefits for employee productivity and other organizational outcomes. Interventions using social robots may have some advantages over other conventional telemedicine applications, since they can deliver personalized feedback and counseling. This investigation focused on a health-promoting intervention within work environments, and compared the efficacy of the intervention on two distinct groups, one guided by a human agent and the other by a robot agent. Participants (n = 56) were recruited from two Portuguese organizations and led through eight sessions by the social agent, the goal being to encourage health behavior change and adoption of a healthier lifestyle. The results indicate that the group led by the robot agent revealed better post-intervention scores than the group led by the human agent, specifically with regard to productivity despite presenteeism and regard of their level of mental well-being. No effects were found concerning the work engagement level of participants in either group. By demonstrating the potential of using social robots to establish therapeutic and worth relationships with employees in their workplaces, this study provides interesting new findings that contribute to the literature on health behavior change and human–robot interaction.info:eu-repo/semantics/publishedVersio

C/O white dwarfs of very low mass: 0.33-0.5 Mo

The standard lower limit for the mass of white dwarfs (WDs) with a C/O core is roughly 0.5 Mo. In the present work we investigated the possibility to form C/O WDs with mass as low as 0.33 Mo. Both the pre-WD and the cooling evolution of such nonstandard models will be described.Comment: Submitted to the "Proceedings of the 16th European White Dwarf Workshop" (to be published JPCS). 7 pages including 13 figure

Mesoscopic Model for Free Energy Landscape Analysis of DNA sequences

A mesoscopic model which allows us to identify and quantify the strength of binding sites in DNA sequences is proposed. The model is based on the Peyrard-Bishop-Dauxois model for the DNA chain coupled to a Brownian particle which explores the sequence interacting more importantly with open base pairs of the DNA chain. We apply the model to promoter sequences of different organisms. The free energy landscape obtained for these promoters shows a complex structure that is strongly connected to their biological behavior. The analysis method used is able to quantify free energy differences of sites within genome sequences.Comment: 7 pages, 5 figures, 1 tabl

An Agent-based Architecture for AI-Enhanced Automated Testing for XR Systems, a Short Paper

This short paper presents an architectural overview of an agent-based framework called iv4XR for automated testing that is currently under development by an H2020 project with the same name. The framework's intended main use case of is testing the family of Extended Reality (XR) based systems (e.g. 3D games, VR sytems, AR systems), though the approach can indeed be adapted to target other types of interactive systems. The framework is unique in that it is an agent-based system. Agents are inherently reactive, and therefore are arguably a natural match to deal with interactive systems. Moreover, it is also a natural vessel for mounting and combining different AI capabilities, e.g. reasoning, navigation, and learning

On the curvature of vortex moduli spaces

We use algebraic topology to investigate local curvature properties of the moduli spaces of gauged vortices on a closed Riemann surface. After computing the homotopy type of the universal cover of the moduli spaces (which are symmetric powers of the surface), we prove that, for genus g>1, the holomorphic bisectional curvature of the vortex metrics cannot always be nonnegative in the multivortex case, and this property extends to all Kaehler metrics on certain symmetric powers. Our result rules out an established and natural conjecture on the geometry of the moduli spaces.Comment: 25 pages; final version, to appear in Math.

Synthesis and characterization of oxidized bacterial cellulose through electrochemical methods: its biodegradability and potential as hemostatic material

Bacterial cellulose (BC) is a biocompatible material with high purity, high crystallinity, high degree of polymerization and high-water content [1,2]. It could be applied in several fields, being the biomedical field the most relevant to this work where biodegradability is a key requirement. BC may be chemically modified through its hydroxyl groups, e.g., by oxidation, becoming reabsorbable and acquiring new features, such as hemostatic behaviour. Oxidation of BC membranes was achieved through electrolysis using tetramethylpiperidine-1-oxyl (TEMPO) radical. TEMPO is able to perform selective oxidation of the primary hydroxyl groups, meaning that only C6 is oxidized into carboxyl groups [3]. BC membranes were characterized by FT-IR, SEM, XRD and 13C-NMR. The degree of oxidation was evaluated by titration of the carboxyl groups and the hemostatic behaviour was investigated through whole blood coagulation tests. Both in vitro and in vivo biodegradability of oxidized membranes was evaluated. In vitro biodegradability was assessed in ultra-pure water after 3, 7, 14 and 63 days of incubation while in vivo biodegradability was studied in a rat model, for 3, 14 and 56 days. FT-IR spectra showed an increase on the absorption band around 1628 cm-1 attributed to the carboxylic acid vibration, as compared to non-oxidized membranes, revealing the formation of carboxylic acid groups [4]. SEM images revealed that the morphology of the membranes was not changed by the oxidation [5]. XRD patterns for all the oxidized samples were very similar to non-oxidized ones, suggesting that the crystal structure was preserved [6]. 13C-RMN results showed that the signal around 62 ppm corresponding to superficial C6 primary hydroxyl group decreased after the oxidation, while the peak around 174.6 ppm assigned to carboxylate groups appeared after oxidation, confirming the selective oxidation of C6 [7]. In vitro results showed that almost no degradation occurred on non-oxidized membranes demonstrating the relevance of the oxidation on the improvement on BC biodegradability. The hemostatic behaviour of the membranes evaluated through the whole blood clotting times assay demonstrated that, contrarily to non-oxidized membranes, the oxidized ones exhibited hemostatic activity [8]. In vivo biodegradability and biocompatibility of oxidized membranes was evaluated. Membranes were implanted subcutaneously and the inflammatory response was studied. The obtained results showed that there were no microscopic evidences of inflammation and even after 56 days of implantation, the oxidized membranes did not degrade completely. Nevertheless, oxidized membranes revealed good biocompatibility [9].info:eu-repo/semantics/publishedVersio

Time dependence of breakdown in a global fiber-bundle model with continuous damage

A time-dependent global fiber-bundle model of fracture with continuous damage is formulated in terms of a set of coupled non-linear differential equations. A first integral of this set is analytically obtained. The time evolution of the system is studied by applying a discrete probabilistic method. Several results are discussed emphasizing their differences with the standard time-dependent model. The results obtained show that with this simple model a variety of experimental observations can be qualitatively reproduced.Comment: APS style, two columns, 4 figures. To appear in Phys. Rev.

Kepler423b: a half-Jupiter mass planet transiting a very old solar-like star

We report the spectroscopic confirmation of the Kepler object of interest KOI-183.01 (Kepler-423b), a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1-17) with high-precision radial velocity measurements taken with the FIES spectrograph at the Nordic Optical Telescope. We simultaneously modelled the photometric and spectroscopic data-sets using Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that the Kepler pre-search data conditioned (PDC) light curve of KOI-183 exhibits quarter-to-quarter systematic variations of the transit depth, with a peak-to-peak amplitude of about 4.3 % and seasonal trends reoccurring every four quarters. We attributed these systematics to an incorrect assessment of the quarterly variation of the crowding metric. The host star KOI-183 is a G4 dwarf with $M_\star=0.85\pm0.04$ M_\rm{Sun}, $R_\star=0.95\pm0.04$ R_\rm{Sun}, $T_\mathrm{eff}=5560\pm80$ K, $[M/H]=-0.10\pm0.05$ dex, and with an age of $11\pm2$ Gyr. The planet KOI-183b has a mass of $M_\mathrm{p}=0.595\pm0.081$ M$_\mathrm{Jup}$ and a radius of $R_\mathrm{p}=1.192\pm0.052$ R$_\mathrm{Jup}$, yielding a planetary bulk density of $\rho_\mathrm{p}=0.459\pm0.083$ g/cm$^{3}$. The radius of KOI-183b is consistent with both theoretical models for irradiated coreless giant planets and expectations based on empirical laws. The inclination of the stellar spin axis suggests that the system is aligned along the line of sight. We detected a tentative secondary eclipse of the planet at a 2-$\sigma$ confidence level ($\Delta F_{\mathrm{ec}}=14.2\pm6.6$ ppm) and found that the orbit might have a small non-zero eccentricity of $e=0.019^{+0.028}_{-0.014}$. With a Bond albedo of $A_\mathrm{B}=0.037\pm0.019$, KOI-183b is one of the gas-giant planets with the lowest albedo known so far.Comment: 13 pages, 13 figures, 5 tables. Accepted for publication in A&A. Planet designation changed from KOI-183b to Kepler-423