REDEMPTION: reduced dimension ensemble modeling and parameter estimation

Summary: Here, we present REDEMPTION (Reduced Dimension Ensemble Modeling and Parameter estimation), a toolbox for parameter estimation and ensemble modeling of ordinary differential equations (ODEs) using time-series data. For models with more reactions than measured species, a common scenario in biological modeling, the parameter estimation is formulated as a nested optimization problem based on incremental parameter estimation strategy. REDEMPTION also includes a tool for the identification of an ensemble of parameter combinations that provide satisfactory goodness-of-fit to the data. The functionalities of REDEMPTION are accessible through a MATLAB user interface (UI), as well as through programming script. For computational speed-up, REDEMPTION provides a numerical parallelization option using MATLAB Parallel Computing toolbox. Availability and implementation: REDEMPTION can be downloaded from http://www.cabsel.ethz.ch/tools/redemption. Contact: [email protected]

Classifying Pattern Formation in Materials via Machine Learning

Scanning probe experiments such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) on strongly correlated materials often reveal complex pattern formation that occurs on multiple length scales. We have shown in two disparate correlated materials that the pattern formation is driven by proximity to a disorder-driven critical point. We developed new analysis concepts and techniques that relate the observed pattern formation to critical exponents by analyzing the geometry and statistics of clusters observed in these experiments and converting that information into critical exponents. Machine learning algorithms can be helpful correlating data from scanning probe experiments to theoretical models of pattern formation. We analyze the use of machine learning algorithms for the identification of critical behavior and universality underlying scanning probe data sets taken from correlated materials. This method has complementary strengths to the cluster analysis methods. The cluster techniques have a clear physical interpretation while machine learning algorithms require less expertise from the user and are faster to implement. The complementary nature of the two techniques further facilitates our understanding of correlated materials. The training of machine learning algorithms has been done through artificial neural networks. The neural net was trained using data from theoretical simulations of percolation and Ising models. The trained net had a 3.00% average classification error during testing. This proves that machine learning algorithms can successfully distinguish whether the complex pattern formation of a specific novel material is governed by uncorrelated percolation or by an interaction model fixed point

Memory and modernity : the symbolic cityscape of Hong Kong.

This thesis proposes five conceptual headings through which to perceive the city. They are: City as History, Spectacle, A Work of Art, Corporate Image, and Home. Each heading is a complete concept on one level and the part of a greater concept on another. A number of celebrity cities (e.g. London, Paris, New York, Los Angeles, Las Vegas, etc.) are considered at each of the headings in turn. A city is the spatial embodiment of memory and modernity. Memory and modernity are multi-facaded within a totality. Each of the five conceptions reflects one facade and their juxtaposition provides meanings to each other. A good city can embrace parts of the five conceptions; whereas an ideal city must achieve an equilibrium of them all. The second part of the thesis, The Phenomenology of A City, examines the urban experience and consciousness of citizens, through the gaze of four representational figures of the modern city (the shopper, flaneur, stranger, and transgressor). Finally, the theories were applied to an exceptional modern city, Hong Kong, in which the identity and image of the city is evaluated and explored. It is worth noting that this thesis, if not the first, will be one of the few to analyse the city of Hong Kong from an aesthetic and historical dimension. The modern city is too gigantic and erratic to grasp completely. This thesis, however, approaches it from these several historical and aesthetic viewpoints. It seeks to capture the urban experience of ordinary people with a poetic lens, and through which one glimpses what is it to experience (a very problematic word in this thesis) the modern city

Communication Lower Bounds for Cryptographic Broadcast Protocols

Broadcast protocols enable a set of $n$ parties to agree on the input of a designated sender, even facing attacks by malicious parties. In the honest-majority setting, randomization and cryptography were harnessed to achieve low-communication broadcast with sub-quadratic total communication and balanced sub-linear cost per party. However, comparatively little is known in the dishonest-majority setting. Here, the most communication-efficient constructions are based on Dolev and Strong (SICOMP '83), and sub-quadratic broadcast has not been achieved. On the other hand, the only nontrivial $\omega(n)$ communication lower bounds are restricted to deterministic protocols, or against strong adaptive adversaries that can perform "after the fact" removal of messages. We provide new communication lower bounds in this space, which hold against arbitrary cryptography and setup assumptions, as well as a simple protocol showing near tightness of our first bound. 1) We demonstrate a tradeoff between resiliency and communication for protocols secure against $n-o(n)$ static corruptions. For example, $\Omega(n\cdot {\sf polylog}(n))$ messages are needed when the number of honest parties is $n/{\sf polylog}(n)$; $\Omega(n\sqrt{n})$ messages are needed for $O(\sqrt{n})$ honest parties; and $\Omega(n^2)$ messages are needed for $O(1)$ honest parties. Complementarily, we demonstrate broadcast with $O(n\cdot{\sf polylog}(n))$ total communication facing any constant fraction of static corruptions. 2) Our second bound considers $n/2 + k$ corruptions and a weakly adaptive adversary that cannot remove messages "after the fact." We show that any broadcast protocol within this setting can be attacked to force an arbitrary party to send messages to $k$ other parties. This rules out, for example, broadcast facing 51% corruptions in which all non-sender parties have sublinear communication locality.Comment: A preliminary version of this work appeared in DISC 202

Ubiquitous Design Studio. Using New Technologies to understand the Contemporary City

Over the past 5 years the [Team] team at the University of [Institution] has been experimenting with new ways of teaching the studio practice outdoor with direct learning from the interaction with the build environment and people in the urban context. Preliminary findings have been published in Authors (2018). This paper presents new findings with the case study of New York, where students have been mapping the impact of digital technologies on the use of physical space. Students have been using a series of tracking apps to gather on-site data that have been interpolated with drawing-based models elaborated in class. The first part of the paper outlines the theoretical framework that underpins these activities, including a brief discussion on key case studies (Lupton 2016). The second part describes the studio activities, highlighting the findings, with the support of a set of maps and digital visualisations. The third part discusses the findings offering a generalisation of the results of this study within the wider context of architectural education. This contribution addresses the conference’s themes by reflecting on the importance of on-site mapping, and observational and representational activities with a critical evaluation of the depiction of urban life in the renaissance through life sketching (cf. Zimmerman and Weissman 1989) and their possible connections with today’s digital technologies (Carpo 2013) in architectural education. Secondly, everyday routines of urban life are reconsidered as main elements for students to design future cities. In particular, social accounts (Gehl 2004) are included in this study, and the importance of future architects to be well-versed in a variety of disciplinary fields (technological, social, cultural and political). Finally, this paper offers a speculation into future models of learning by looking at how technology offers new venues for students to observe, analyse and understand cities and the people living in it.Peer reviewe

Phase synchronization during the processing of taxonomic and thematic relations

Semantic relations include “taxonomic” relations based on shared features and “thematic” relations based on co-occurrence in events. The “dual-hub” account proposes that the anterior temporal lobe (ATL) is functionally specialized for taxonomic relations and the inferior parietal lobule (IPL) for thematic relations. This study examined this claim by analyzing the intra- and inter-region phase synchronization of intracranial EEG data from electrodes in the ATL, IPL, and two subregions of the semantic control network: left inferior frontal gyrus (IFG) and posterior middle temporal gyrus (pMTG). Ten participants with epilepsy completed a semantic relatedness judgment task during intracranial EEG recording and had electrodes in at least one hub and at least one semantic control region. Theta band phase synchronization was partially consistent with the dual-hub account: synchronization between the ATL and IFG/pMTG increased when processing taxonomic relations, and synchronization within the IPL and between IPL and pMTG increased when processing thematic relations