2,420 research outputs found

    Effect of Temperature Change on Synaptic Transmission at Crayfish Neuromuscular Junctions

    Get PDF
    Ectothermic animals in areas characterised by seasonal changes are susceptible to extreme fluctuations in temperature. To survive through varied temperatures, ectotherms have developed unique strategies. This study focuses on synaptic transmission function at cold temperatures, as it is a vital component of ectothermic animals\u27 survival. For determining how synaptic transmission is influenced by an acute change in temperature (20°C to 10°C within a minute) and chronic cold (10°C), the crayfish (Procambarus clarkii) neuromuscular junction (NMJ) was used as a model. To simulate chronic cold conditions, crayfish were acclimated to 15°C for 1 week and then to 10°C for 1 week. They were then used to examine the synaptic properties associated with the low output nerve terminals on the opener muscle in the walking legs and high output innervation on the abdominal deep extensor muscle. The excitatory postsynaptic potentials (EPSPs) of the opener NMJs increased in amplitude with acute warming (20°C) after being acclimated to cold; however, the deep extensor muscles showed varied changes in EPSP amplitude. Synaptic transmission at both NMJs was enhanced with exposure to the modulators serotonin or octopamine. The membrane resistance of the muscles decreased 33% and the resting membrane potential hyperpolarised upon warm exposure. Analysis of haemolymph indicated that octopamine increases during cold exposure. These results suggest bioamine modulation as a possible mechanism for ensuring that synaptic transmission remains functional at low temperatures

    Functional Commitments for All Functions, with Transparent Setup and from SIS

    Get PDF
    A *functional commitment* scheme enables a user to concisely commit to a function from a specified family, then later concisely and verifiably reveal values of the function at desired inputs. Useful special cases, which have seen applications across cryptography, include vector commitments and polynomial commitments. To date, functional commitments have been constructed (under falsifiable assumptions) only for functions that are essentially *linear*, with one recent exception that works for arbitrarily complex functions. However, that scheme operates in a strong and non-standard model, requiring an online, trusted authority to generate special keys for any opened function inputs. In this work, we give the first functional commitment scheme for nonlinear functions---indeed, for *all functions* of any bounded complexity---under a standard setup and a falsifiable assumption. Specifically, the setup is ``transparent,\u27\u27 requiring only public randomness (and not any trusted entity), and the assumption is the hardness of the standard Short Integer Solution (SIS) lattice problem. Our construction also has other attractive features, including: *stateless updates* via generic composability; excellent *asymptotic efficiency* for the verifier, and also for the committer in important special cases like vector and polynomial commitments, via preprocessing; and *post-quantum security*, since it is based on SIS

    Fast Vector Oblivious Linear Evaluation from Ring Learning with Errors

    Get PDF
    Oblivious linear evaluation (OLE) is a fundamental building block in multi-party computation protocols. In OLE, a sender holds a description of an affine function fα,β(z)=αz+βf_{\alpha,\beta}(z)=\alpha z+\beta, the receiver holds an input xx, and gets αx+β\alpha x+\beta (where all computations are done over some field, or more generally, a ring). Vector OLE (VOLE) is a generalization where the sender has many affine functions and the receiver learns the evaluation of all of these functions on a single point xx. The state-of-the-art semi-honest VOLE protocols generally fall into two groups. The first group relies on standard assumptions to achieve security but lacks in concrete efficiency. These constructions are mostly based on additively homomorphic encryption (AHE) and are classified as ``folklore . The second group relies on less standard assumptions, usually properties of sparse, random linear codes, but they manage to achieve concrete practical efficiency. In this work, we present a conceptually simple VOLE protocol that derives its security from a standard assumption, namely Ring Learning with Errors (RLWE), while still achieving concrete efficiency comparable to the fastest VOLE protocols from non-standard coding assumptions. Furthermore, our protocol admits a natural extension to batch OLE (BOLE), which is yet another variant of OLE that computes many OLEs in parallel

    Índices de lesões e seus fatores de riscos em praticantes de CrossFit

    Get PDF
    Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Educação Física, 2018.Objetivo : avaliar os índices de lesões e os fatores de risco associados a elas em praticantes de Crossfit. Metodologia: foi feita uma revisão de literatura nas bases de dados PubMed, Scielo, Portal de periódicos CAPES e Lilacs, procurando artigos que trataram do tema “lesão no Crossfit”. Resultados: foram encontrados 12 artigos que abordaram o tema. A média entre os artigos do percentual de indivíduos lesionados foi de 40,13%, a média do índice de lesões foi de 2,48 lesões/ 1000 horas de treino. As partes mais lesionadas foram ombro, coluna e joelho. Conclusão: Os índices de lesões no Crossfit são comparáveis com outras atividades físicas comumente praticadas, como futebol e musculação, por exemplo. É de extrema importância que treinadores conheçam as lesões e os fatores de risco para que eles possam evitá- las ao máximo

    A RELAÇÃO ENTRE INOVAÇÃO E DESEMPENHO INTERNACIONAL DE ATIVIDADES DE SERVIÇOS EM FIRMAS FRANCESAS

    Get PDF
    Assuming that internationalization can be a determining factor for companies, in the service sector, to perceive innovation as central element for development, this article aims to determine how the relationship between service innovation and international performance takes place. Based on a theoretical framework regarding the concepts of internationalization and service innovation, a model was constructed to summarize the relationship between factors that constitute these concepts, such as: international performance, service innovation, international experience, international expertise, organizational capacity, and relational capacity, the company's ability to use new information and communication technologies. A survey was designed considering the indicators of these factors, which were evaluated on a Likert scale of 5 points. The sample, taken from the Frenche database Altars and after multiple selections, was comprised of 51 companies. The method used for data processing, Partial Least Square (PLS), revealed a relationship between innovation and international performance of the enterprises studied. Partindo do pressuposto que a internacionalização pode ser um fator determinante para que as empresas, no setor de serviço, percebam a inovação como primordial para o desenvolvimento, este artigo tem como objetivo determinar como se dá a relação entre a inovação de serviços e o desempenho internacional de empresas de serviços. Com base em marco teórico desenvolvido a partir de teorias de internacionalização e inovação de serviços, foi construído um modelo sobre as relações entre estes fatores, incluindo as seguintes variáveis: desempenho internacional, inovação de serviço, experiência internacional, competência internacional, capacidade organizacional, capacidade relacional e capacidade da empresa de utilizar as novas tecnologias da informação e da comunicação. O questionário utilizado para a coleta dos dados foi construído a partir dos indicadores desses fatores e avaliado em uma escala Likert de 5 itens. A amostra, retirada de banco de dados francês Altares e após várias seleções, foi constituída por 51 empresas. O método utilizado para tratamento dos dados, o Partial Least Square (PLS), revelou uma relação entre inovação e o desempenho internacional das empresas estudadas

    Grain selective Cu oxidation and anomalous shift of graphene 2D Raman peak in the graphene-Cu system

    Get PDF
    Understanding the interaction between graphene and its supporting substrate is of paramount importance for the development of graphene based applications. In this work the interplay of the technologically relevant graphene-Cu system is investigated in detail as a function of substrate grain orientation in Cu polycrystalline foils. While (100) and (111) Cu grains show the well-known graphene-enhanced oxidation, (110) grains present a superior oxidation resistance compared to uncovered Cu and an anomalous shift of its graphene 2D Raman band which cannot be explained by the known effects of strain and doping. These results are interpreted in terms of a weak graphene-Cu coupling at the (110) grains, and show that graphene can actually be used as anticorrosion coating, contrary to previously reported. The anomalous shift is suggested to be the result of an enhanced outer Raman scattering process which surpasses the usually dominant inner process. Since Raman spectroscopy is widely used as first and main characterization tool of graphene, the existence of an anomalous shift on its 2D band not only challenges the current theory of Raman scattering in graphene, but also has profound implications from an experimental point of view

    Does Fully Homomorphic Encryption Need Compute Acceleration?

    Get PDF
    The emergence of cloud-computing has raised important privacy questions about the data that users share with remote servers. While data in transit is protected using standard techniques like Transport Layer Security (TLS), most cloud providers have unrestricted plaintext access to user data at the endpoint. Fully Homomorphic Encryption (FHE) offers one solution to this problem by allowing for arbitrarily complex computations on encrypted data without ever needing to decrypt it. Unfortunately, all known implementations of FHE require the addition of noise during encryption which grows during computation. As a result, sustaining deep computations requires a periodic noise reduction step known as bootstrapping. The cost of the bootstrapping operation is one of the primary barriers to the wide-spread adoption of FHE.In this paper, we present an in-depth architectural analysis of the bootstrapping step in FHE. First, we observe that se-cure implementations of bootstrapping exhibit a low arithmetic intensity (100MB) and as such, are heavily bound by the main memory bandwidth.Consequently, we demonstrate that existing workloads observe marginal performance gains from the design of bespoke high-throughput arithmetic units tailored to FHE. Secondly, we propose several cache-friendly algorithmic optimizations that improve the throughput in FHE bootstrapping by enabling upto3.2×higher arithmetic intensity and4.6×lower memory bandwidth. Our optimizations apply to a wide range of structurally similar computations such as private evaluation and training of machine learning models. Finally, we incorporate these optimizations into an architectural tool which, given a cache size, memory subsystem, the number of functional units and a desired security level, selects optimal cryptosystem parameters to maximize the bootstrapping throughput.Our optimized bootstrapping implementation represents a best-case scenario for compute acceleration of FHE. We show that despite these optimizations, bootstrapping (as well as other applications with similar computational structure) continue to remain bottlenecked by main memory bandwidth. We thus conclude that secure FHE implementations need to look beyond accelerated compute for further performance improvements and to that end, we propose new research directions to address the underlying memory bottleneck. In summary, our answer to the titular question is: yes, but only after addressing the memory bottleneck

    Postradiation Matrix Metalloproteinase-20 Expression and Its Impact on Dental Micromorphology and Radiation-Related Caries

    Get PDF
    Recent evidence suggests that head-and-neck radiotherapy (HNRT) increases active forms of matrix metalloproteinase-20 (MMP-20) in human tooth crowns, degrading the dentin-enamel junction (DEJ) and leading to enamel delamination, which is a pivotal step in the formation of radiation-related caries (RRC). Additional participation of enzymatic degradation of organic matrix components in caries progression was attributed to MMP-20 in dentin. Therefore, the current study tested the hypothesis that MMP-20 is overexpressed in the DEJ, dentin-pulp complex components, and carious dentin of post-HNRT patients, leading to detectable micromorphological changes to the enamel and dentin. Thirty-six teeth were studied, including 19 post-HNRT specimens and 17 nonirradiated controls. Optical light microscopy was used to investigate the micromorphological components of the DEJ, dentin-pulp complex components, and carious dentin. The samples were divided into 2 subgroups: nondemineralized ground sections (n = 20) and demineralized histological sections (n = 16). In addition, immunohistochemical analysis using the immunoperoxidase technique was conducted to semiquantitatively assess MMP-20 expression in the DEJ, dentin-pulp complex components, and carious dentin. No apparent damage to the DEJ microstructure or other dentin-pulp complex components was observed and no statistically significant differences were detected in MMP-20 expression (p > 0.05) between the irradiated and control groups. This study rejected the hypothesis that MMP-20 is overexpressed in the DEJ, dentin-pulp complex components, and carious dentin of post-HNRT patients, leading to detectable micromorphological changes. Hence, direct effects of radiation may not be regarded as an independent factor to explain aggressive clinical patterns of RRC. (C) 2017 S. Karger AG, BaselPeer reviewe

    Proto-Adamastor ocean crust (920 Ma) described in Brasiliano Orogen from coetaneous zircon and tourmaline.

    Get PDF
    Proto-Adamastor ocean bathed Rodinia and successor continental fragments from 1.0e0.9 Ga up to 0.75 Ga, and evolved into world Adamastor Ocean at 0.75e0.60 Ga. Mesoproterozoic oceanic crust is poorly preserved on continents, only indirect evidence registered in Brasiliano Orogen. We report first evidence of ophiolite originated in proto-Adamastor. We use multi-technique U-Pb-Hf zircon and d11B tourmaline isotopic and elemental compositions. The host tourmalinite is enclosed in metaserpentinite, both belonging to the Bossoroca ophiolite. Zircon is 920 Ma-old, 3 Hf(920 Ma)??12, HfTDM ? 1.0 Ga and has ?oceanic? composition (e.g., U/Yb < 0.1). Tourmaline is dravite with d11B ? ?1.8& (Tur 1), 0& (Tur 2), 8.5& (Tur 3). These characteristics are a novel contribution to Rodinia and associated world ocean, because a fragment of proto-Adamastor oceanic crust and mantle evolved at the beginning of the Brasiliano Orogen
    corecore