Dynamical phase transitions in supercooled liquids:Interpreting measurements of dynamical activity

We study dynamical phase transitions in a model supercooled liquid. These transitions occur in ensembles of trajectories that are biased towards low (or high) dynamical activity. We compare two different measures of activity that were introduced in recent papers and we find that they are anti-correlated with each other. To interpret this result, we show that the two measures couple to motion on different length and time scales. We find that inactive states with very slow structural relaxation nevertheless have increased molecular motion on short scales. We discuss these results in terms of the potential energy landscape of the system and in terms of the liquid structure in active/inactive states.Comment: 11 pages, 7 figure

Controlling crystal self-assembly using a real-time feedback scheme

We simulate crystallisation of hard spheres with short-ranged attractive potentials as a model self-assembling system. Using measurements of correlation and response functions, we develop a method whereby the interaction parameters between the particles are automatically tuned during the assembly process, in order to obtain high-quality crystals and avoid kinetic traps. The method we use is independent of the details of the interaction potential and of the structure of the final crystal - we propose that it can be applied to a wide range of self-assembling systems

Emergence of glass-like behavior in markov state models of protein folding dynamics

The extent to which glass-like kinetics govern dynamics in protein folding has been heavily debated. Here, we address the subject with an application of space-time perturbation theory to the dynamics of protein folding Markov State Models (MSMs). Borrowing techniques from the s-ensemble method, we argue that distinct active and inactive phases exist for protein folding dynamics, and that kinetics for specific systems can fall into either dynamical regime. We do not, however, observe a true glass transition in any system studied. We go on to discuss how these inactive and active phases might relate to general protein folding properties

Synchronizing Web Documents with Style

In this paper we report on our efforts to define a set of document extensions to Cascading Style Sheets (CSS) that allow for structured timing and synchronization of elements within a Web page. Our work considers the scenario in which the temporal structure can be decoupled from the content of the Web page in a similar way that CSS does with the layout, colors and fonts. Based on the SMIL (Synchronized Multimedia Integration Language) temporal model we propose CSS document extensions and discuss the design and implementation of a proof of concept that realizes our contributions. As HTML5 seems to move away from technologies like Flash and XML (eXtensible Markup Language), we believe our approach provides a flexible declarative solution to specify rich media experiences that is more aligned with current Web practices

Space-time Phase Transitions in Driven Kinetically Constrained Lattice Models

Kinetically constrained models (KCMs) have been used to study and understand the origin of glassy dynamics. Despite having trivial thermodynamic properties, their dynamics slows down dramatically at low temperatures while displaying dynamical heterogeneity as seen in glass forming supercooled liquids. This dynamics has its origin in an ergodic-nonergodic first-order phase transition between phases of distinct dynamical "activity". This is a "space-time" transition as it corresponds to a singular change in ensembles of trajectories of the dynamics rather than ensembles of configurations. Here we extend these ideas to driven glassy systems by considering KCMs driven into non-equilibrium steady states through non-conservative forces. By classifying trajectories through their entropy production we prove that driven KCMs also display an analogous first-order space-time transition between dynamical phases of finite and vanishing entropy production. We also discuss how trajectories with rare values of entropy production can be realized as typical trajectories of a mapped system with modified forces

Robust statistics towards detection of the 21 cm signal from the Epoch of Reionization

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We explore methods for robust estimation of the 21 cm signal from the Epoch of Reionization (EoR). A Kernel Density Estimator (KDE) is introduced for measuring the spatial temperature fluctuation power spectrum from the EoR. The KDE estimates the underlying probability distribution function of fluctuations as a function of spatial scale, and contains different systematic biases and errors to the typical approach to estimating the fluctuation power spectrum. Extraction of histograms of visibilities allows moments analysis to be used to discriminate foregrounds from 21 cm signal and thermal noise. We use the information available in the histograms, along with the statistical dis-similarity of foregrounds from two independent observing fields, to robustly separate foregrounds from cosmological signal, while making no assumptions about the Gaussianity of the signal. Using two independent observing fields to robustly discriminate signal from foregrounds is crucial for the analysis presented in this paper. We apply the techniques to 13 h of Murchison Widefield Array EoR data over two observing fields. We compare the output to that obtained with a comparative power spectrum estimation method, and demonstrate the reduced foreground contamination using this approach. Using the second moment obtained directly from the KDE distribution functions yields a factor of 2-3 improvement in power for k < 0.3 h Mpc-1 compared with a matched delay space power estimator, while weighting data by additional statistics does not offer significant improvement beyond that available for thermal noise-only weights

Evaluating How Potential Pool of Partners Can Join Together in Different Types of Long Term Collaborative Networked Organizations

International audienceThe considerable benefits brought up by strategic alliances and diverse types of long term Collaborative Networked Organizations (CNOs) are nowadays widely recognized. There is an increasing demand in the industrial world for concretely implement new forms of collaborations. For example, demand often comes from pre-existent form of clusters or local productive arrangements, that want to evolve to more efficient forms of collaboration, or from small and medium enterprises that are facing a crisis, and look at collaboration with other enterprises as almost the last chance to survive. In general, variety of motivations in collaborating implies variety of missions of potential collaborations, that in turn requires the choice of an appropriate form of Collaborative Network aligned to the mission statement. This paper addresses the problem to define a methodology for analyzing potential pool of partners and for identifing the mission, the form, the governance structure and the value drivers of long term strategic alliance that would bring highest benefits to the partners. Three different forms of CNOs are considered: the Virtual organizations Breeding Environment (VBE), the Virtual Development Office (VDO) and the T-Holding

A survey for variable young stars with small telescopes: II - mapping a protoplanetary disc with stable structures at 0.15 au

The HOYS citizen science project conducts long term, multifilter, high cadence monitoring of large YSO samples with a wide variety of professional and amateur telescopes. We present the analysis of the light curve of V1490 Cyg in the Pelican Nebula. We show that colour terms in the diverse photometric data can be calibrated out to achieve a median photometric accuracy of 0.02 mag in broadband filters, allowing detailed investigations into a variety of variability amplitudes over timescales from hours to several years. Using Gaia DR2 we estimate the distance to the Pelican Nebula to be 870 +70 −55 pc. V1490 Cyg is a quasi-periodic dipper with a period of 31.447 ± 0.011 d. The obscuring dust has homogeneous properties, and grains larger than those typical in the ISM. Larger variability on short timescales is observed in U and Rc−Hα, with U-amplitudes reaching 3 mag on timescales of hours, indicating the source is accreting. The Hα equivalent width and NIR/MIR colours place V1490 Cyg between CTTS/WTTS and transition disk objects. The material responsible for the dipping is located in a warped inner disk, about 0.15 AU from the star. This mass reservoir can be filled and emptied on time scales shorter than the period at a rate of up to 10−10 M�/yr, consistent with low levels of accretion in other T Tauri stars. Most likely the warp at this separation from the star is induced by a protoplanet in the inner accretion disk. However, we cannot fully rule out the possibility of an AA Tau-like warp, or occultations by the Hill sphere around a forming planet