Mostrando recursos 41 - 60 de 5.362

  1. Bistable metamaterial for switching and cascading elastic vibrations

    Bilal, Osama R.; Foehr, André; Daraio, Chiara
    The realization of acoustic devices analogous to electronic systems, like diodes, transistors, and logic elements, suggests the potential use of elastic vibrations (i.e., phonons) in information processing, for example, in advanced computational systems, smart actuators, and programmable materials. Previous experimental realizations of acoustic diodes and mechanical switches have used nonlinearities to break transmission symmetry. However, existing solutions require operation at different frequencies or involve signal conversion in the electronic or optical domains. Here, we show an experimental realization of a phononic transistor-like device using geometric nonlinearities to switch and amplify elastic vibrations, via magnetic coupling, operating at a single frequency....

  2. Who Will Be the Next President? A Guide to the U.S. Presidential Election System

    Belenky, Alexander
    Almost every American has either studied something about the Electoral College in school or at least heard of it. Yet to many people used to electing municipal, state, and federal officials by the democratic principle “the one who gets the most votes always wins,” the Electoral College looks quite mysterious and antiquated. The mystery concerns how such a system could have existed for so long, and why it has not been replaced by a system that is based on the above democratic principle. In contrast, people who are curious about the election system often try to grasp (a) how the Electoral College...

  3. Biotagging of Specific Cell Populations in Zebrafish Reveals Gene Regulatory Logic Encoded in the Nuclear Transcriptome

    Trinh, Le A.; Chong-Morrison, Vanessa; Gavriouchkina, Daria; Hochgreb-Hägele, Tatiana; Senanayake, Upeka; Fraser, Scott E.; Sauka-Spengler, Tatjana
    Interrogation of gene regulatory circuits in complex organisms requires precise tools for the selection of individual cell types and robust methods for biochemical profiling of target proteins. We have developed a versatile, tissue-specific binary in vivo biotinylation system in zebrafish termed biotagging that uses genetically encoded components to biotinylate target proteins, enabling in-depth genome-wide analyses of their molecular interactions. Using tissue-specific drivers and cell-compartment-specific effector lines, we demonstrate the specificity of the biotagging toolkit at the biochemical, cellular, and transcriptional levels. We use biotagging to characterize the in vivo transcriptional landscape of migratory neural crest and myocardial cells in different...

  4. Sequential Response to Multiple Developmental Network Circuits Encoded in an Intronic cis- Regulatory Module of Sea Urchin hox11/13b

    Cui, Miao; Vielmas, Erika; Davidson, Eric H.; Peter, Isabelle S.
    Gene expression in different spatial domains is often controlled by separate cis-regulatory modules (CRMs), but regulatory states determining CRM activity are not only distinct in space, they also change continuously during developmental time. Here, we systematically analyzed the regulatory sequences controlling hox11/13b expression and identified a single CRM required throughout embryonic gut development. We show that within this CRM, distinct sets of binding sites recognizing Ets, Tcf, and homeodomain transcription factors control the dynamic spatial expression of hox11/13b in each developmental phase. Several binding sites execute multiple, sometimes contradictory, regulatory functions, depending on the temporal and spatial regulatory context. In...

  5. Systematic Analysis of Quantitative Logic Model Ensembles Predicts Drug Combination Effects on Cell Signaling Networks

    Morris, Melody Kay; Clarke, David C.; Osimiri, Lindsey C.; Lauffenburger, Douglas A
    A major challenge in developing anticancer therapies is determining the efficacies of drugs and their combinations in physiologically relevant microenvironments. We describe here our application of “constrained fuzzy logic” (CFL) ensemble modeling of the intracellular signaling network for predicting inhibitor treatments that reduce the phospho-levels of key transcription factors downstream of growth factors and inflammatory cytokines representative of hepatocellular carcinoma (HCC) microenvironments. We observed that the CFL models successfully predicted the effects of several kinase inhibitor combinations. Furthermore, the ensemble predictions revealed ambiguous predictions that could be traced to a specific structural feature of these models, which we resolved with...

  6. Notas para a Elucidação do Conceito "Cultura"

    Silva, Eduardo
    Ensaio que tem em vista elucidar o conceito "cultura" por via: (1) de explicitar a relação lógica que subsiste entre a Cultura do Homem e outras formas de cultura; (2) as implicações lógico-semânticas de designações como "cultura chinesa" e "cultura dos Chineses", bem como de expressões contendo o adjetivo "cultural" (e.g., "ato cultural"); (3) os diversos sentidos que o termo homónimo "cultura" é passível de expressar; (4) a oposição entre "cultura" e "culturas": as conceções (i) neo-humanista, (ii) sociológico-antropológica" e (iii) clássica–holística de "cultura".

  7. Emerging lessons from the FIGO LOGIC initiative on maternal death and near-miss reviews

    Lewis, G
    © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.This short paper describes some early findings from an overview of the maternal death or severe morbidity "near-miss" reviews that have been undertaken to improve clinical care by the eight societies participating in the FIGO Leadership in Obstetrics and Gynecology for Impact and Change (LOGIC) Initiative in Maternal and Newborn Health aimed at strengthening the role of professional obstetric associations. While it is expected that each will publish its own report, generalizable lessons emerged and valuable solutions were implemented that will help others planning such...

  8. Why Are We Waiting?: The Logic, Urgency, and Promise of Tackling Climate Change

    Grubb, M

  9. Osiris: A Tool for Abstraction and Verification of Control Software with Lookup Tables

    Aréchiga, Nikos; Dathathri, Sumanth; Vernekar, Shashank; Kathare, Nagesh; Gao, Sicun; Shiraishi, Shinichi
    Some industrial systems are difficult to formally verify due to their large scale. In particular, the widespread use of lookup tables in embedded systems across diverse industries, such as aeronautics and automotive systems, create a critical obstacle to the scalability of formal verification. This paper presents Osiris, a tool that automatically computes abstractions of lookup tables. Osiris uses these abstractions to verify a property in first order logic. If the verification fails, Osiris uses a falsification heuristic to search for a violation of the specification. We validate our technique on a public benchmark of an adaptive cruise controller with lookup...

  10. Soft X-Ray Tomography Reveals Gradual Chromatin Compaction and Reorganization during Neurogenesis In Vivo

    Le Gros, Mark A.; Clowney, E. Josephine; Magklara, Angeliki; Markenscoff-Papadimitriou, Eirene; Colquitt, Bradley; Myllys, Markko; Lomvardas, Stavros; Larabell, Carolyn A.; Yen, Angela; Kellis, Manolis
    Summary - The realization that nuclear distribution of DNA, RNA, and proteins differs between cell types and developmental stages suggests that nuclear organization serves regulatory functions. Understanding the logic of nuclear architecture and how it contributes to differentiation and cell fate commitment remains challenging. Here, we use soft X-ray tomography (SXT) to image chromatin organization, distribution, and biophysical properties during neurogenesis in vivo. Our analyses reveal that chromatin with similar biophysical properties forms an elaborate connected network throughout the entire nucleus. Although this interconnectivity is present in every developmental stage, differentiation proceeds with concomitant increase in chromatin compaction and re-distribution...

  11. Suburban Urbanities: Suburbs and the Life of the High Street

    Vaughan, LS
    Suburban space has traditionally been understood as a formless remnant of physical city expansion, without a dynamic or logic of its own. Suburban Urbanities challenges this view by defining the suburb as a temporally evolving feature of urban growth. Anchored in the architectural research discipline of space syntax, this book offers a comprehensive understanding of urban change, touching on the history of the suburb as well as its current development challenges, with a particular focus on suburban centres. Studies of the high street as a centre for social, economic and cultural exchange provide evidence for its critical role in sustaining...

  12. Swedish Literature on the British Market 1998-2013: A Systemic Approach

    Broome, AH
    This thesis examines the role and function of contemporary Swedish fiction in English translation on the British book market in the period 1998-2013. Drawing on Bourdieu’s Field Theory, Even Zohar’s Polysystem Theory and DeLanda’s Assemblage Theory, it constructs a model capable of dynamically describing the life cycle of border-crossing books, from selection and production to marketing, sales and reception. This life cycle is driven and shaped by individual position-takings of book market actants, and by their complex interaction and continual evolution. The thesis thus develops an understanding of the book market and its actants that deliberately resists static or linear...

  13. The regulatory logic of m-xylene biodegradation by Pseudomonas putida mt-2 exposed by dynamic modelling of the principal node Ps/Pr of the TOL plasmid

    Koutinas, M; Lam, M-C; Kiparissides, A; Silva-Rocha, R; Godinho, M; Livingston, AG; Pistikopoulos, EN; De Lorenzo, V; Dos Santos, VAPM; Mantalaris, A

  14. Nanoelectromechanical systems for ultra-low-power computing and VLSI

    Feng, Philip
    Nanoscale devices with mechanical degrees of freedom offer compelling characteristics that make them very attractive for mechanical and quantum logic devices. As we are able to create nanoelectromechanical systems (NEMS) with unprecedented feature sizes, advanced complexity and functionality, and high yield and control (at wafer-scale), they become increasingly interesting for low-power logic and memory, as well as become more meaningful for VLSI. Partly this is driven by NEMS devices' unique merits such as exceptionally large on/off ratio, non-leakage, ultralow switching power, fast speed, and temperature insensitivity. In parallel, this is also an intriguing effort in the quest for the ultimately...

  15. Automatic cyclic termination proofs for recursive procedures in separation logic

    Rowe, RNS; Brotherston, J
    © 2017 ACM.We describe a formal verification framework and tool implementation, based upon cyclic proofs, for certifying the safe termination of imperative pointer programs with recursive procedures. Our assertions are symbolic heaps in separation logic with user defined inductive predicates; we employ explicit approximations of these predicates as our termination measures. This enables us to extend cyclic proof to programs with procedures by relating these measures across the preand postconditions of procedure calls. We provide an implementation of our formal proof system in the CYCLIST theorem proving framework, and evaluate its performance on a range of examples drawn from the...

  16. Asynchronous logic for high variability nano-CMOS

    Martin, Alain J.
    At the nanoscale level, parameter variations in fabricated devices cause extreme variability in delay. Delay variations are also the main issue in subthreshold operation. Consequently, asynchronous logic seems an ideal, and probably unavoidable choice, for the design of digital circuits in nano CMOS or other emerging technologies. This paper examines the robustness of one particular asynchronous logic: quasi-delay insensitive or QDI. We identify the three components of this logic that can be affected by extreme variability: staticizer, isochronic fork, and rings. We show that staticizers can be eliminated, and isochronic forks and rings can be made arbitrarily robust to timing...

  17. Consilient Discrepancy: Porosity and Atmosphere in Cinema and Architecture

    Tawa, Michael
    Cinema constitutes a way of looking at the world, at a world – its aspect, its appearance; but it also presents how that world looks, its prospect – by the prospective glance it throws back toward us. The “look” of a film – its mood, ambiance or atmosphere – eclipses formal and aesthetics registers. It is fundamentally world-forming, and therefore both cosmogonic and ethical: cosmogonic because it produces a world in the midst of, and as, the temporality that devolves through its passage; and ethical because the world it brings about is an inhabited world, a conjugation of people and place...

  18. Prioritizing inbound transportation

    Rassey, Richard Koury; Zheng, Yong
    Retailers must coordinate inbound shipments from a large number of vendors. In order to manage capacity, retailers need to have a system to prioritize inbound loads with capacitated carriers. This practice creates a constraint when the number of loads exceeds the capacity of committed carriers due to seasonality and consumer shopping behaviors. A prioritization mechanism needed to be developed to support decision making for the selection of loads when capacity is constrained. This research applied the Analytic Hierarchy Process to define prioritization logic for each inbound load and solved a Knapsack model to optimize the assignment. This decision-making model allows...

  19. Learning algorithms for logical neural networks

    Penny, WD; Stonham, TJ
    Two training methods for multilayer logical neural networks are presented and discussed. They are the probabilistic logic node (PLN) reward-penalty algorithm of I. Aleksander (1989) and the PLN back-propagation algorithm of R. Al-Alawi and T. J. Stonham (1989). They are considered within the paradigm of reward-penalty training algorithms for analog networks and are found to be capable of solving various hard learning problems in speeds which are orders of magnitude higher than error back-propagation techniques for conventional nodes.

  20. Do laboratório da escrita à escrita de laboratório: reflexões sobre genética textual, ciência e literatura

    Boto, Sandra
    Ao longo da sua História, os Estudos Literários têm vivido cíclicos momentos de aproximação ao paradigma das Ciências, fascinados pelo seu discurso de rigor e objetividade e tentando importá-lo para as suas metodologias e técnicas. isto é particularmente visível ao nível da metalinguagem de que determinadas disciplinas e correntes das Letras se munem, através da apropriação de metáforas oriundas do mundo científico. exemplo do que acabamos de enunciar é a Crítica Genética, disciplina que assume como objeto de estudo o "laboratório da escrita"de um autor, metáfora de rigor que se materializará e se oferecerá ao leitor necessariamente através de uma...

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