537 research outputs found

    Designing Secure Ethereum Smart Contracts: A Finite State Machine Based Approach

    Full text link
    The adoption of blockchain-based distributed computation platforms is growing fast. Some of these platforms, such as Ethereum, provide support for implementing smart contracts, which are envisioned to have novel applications in a broad range of areas, including finance and Internet-of-Things. However, a significant number of smart contracts deployed in practice suffer from security vulnerabilities, which enable malicious users to steal assets from a contract or to cause damage. Vulnerabilities present a serious issue since contracts may handle financial assets of considerable value, and contract bugs are non-fixable by design. To help developers create more secure smart contracts, we introduce FSolidM, a framework rooted in rigorous semantics for designing con- tracts as Finite State Machines (FSM). We present a tool for creating FSM on an easy-to-use graphical interface and for automatically generating Ethereum contracts. Further, we introduce a set of design patterns, which we implement as plugins that developers can easily add to their contracts to enhance security and functionality

    SAT-based Explicit LTL Reasoning

    Full text link
    We present here a new explicit reasoning framework for linear temporal logic (LTL), which is built on top of propositional satisfiability (SAT) solving. As a proof-of-concept of this framework, we describe a new LTL satisfiability tool, Aalta\_v2.0, which is built on top of the MiniSAT SAT solver. We test the effectiveness of this approach by demonnstrating that Aalta\_v2.0 significantly outperforms all existing LTL satisfiability solvers. Furthermore, we show that the framework can be extended from propositional LTL to assertional LTL (where we allow theory atoms), by replacing MiniSAT with the Z3 SMT solver, and demonstrating that this can yield an exponential improvement in performance

    Satisfiability Modulo Transcendental Functions via Incremental Linearization

    Full text link
    In this paper we present an abstraction-refinement approach to Satisfiability Modulo the theory of transcendental functions, such as exponentiation and trigonometric functions. The transcendental functions are represented as uninterpreted in the abstract space, which is described in terms of the combined theory of linear arithmetic on the rationals with uninterpreted functions, and are incrementally axiomatized by means of upper- and lower-bounding piecewise-linear functions. Suitable numerical techniques are used to ensure that the abstractions of the transcendental functions are sound even in presence of irrationals. Our experimental evaluation on benchmarks from verification and mathematics demonstrates the potential of our approach, showing that it compares favorably with delta-satisfiability /interval propagation and methods based on theorem proving

    A novel non-peptidic agonist of the ghrelin receptor with orexigenic activity in vivo

    Get PDF
    Loss of appetite in the medically ill and ageing populations is a major health problem and a significant symptom in cachexia syndromes, which is the loss of muscle and fat mass. Ghrelin is a gut-derived hormone which can stimulate appetite. Herein we describe a novel, simple, non-peptidic, 2-pyridone which acts as a selective agonist for the ghrelin receptor (GHS-R1a). The small 2-pyridone demonstrated clear agonistic activity in both transfected human cells and mouse hypothalamic cells with endogenous GHS-R1a receptor expression. In vivo tests with the hit compound showed significant increased food intake following peripheral administration, which highlights the potent orexigenic effect of this novel GHS-R1a receptor ligand

    Efeito alelopático do extrato bruto de Brachiaria decumbens na germinação e no vigor de sementes e de plântulas de Brachiaria brizantha.

    Get PDF
    Objetivou-se identificar os possíveis efeitos alelopáticos produzidos pelo extrato bruto de um acesso da coleção de Brachiaria spp da Embrapa Gado de Corte, denominado Brachiaria decumbens BRA001996 na germinação, no vigor de sementes e no vigor de plântulas de três cultivares de B. brizantha (cvs. Marandu, BRS Piatã e Xaraés). As sementes das cultivares foram semeadas em papel germitest, colocadas em gerbox e incubadas em câmara climática com fotoperíodo controlado. Utilizaram-se quatro repetições de 100 sementes para os testes de germinação e vigor e 25 sementes para o teste de vigor de plântulas. O extrato bruto foi obtido das folhas da gramínea, por meio de técnica laboratorial utilizada para detecção e quantificação de avaliação de saponinas esteroidais. Foram avaliadas duas testemunhas: uma somente com água destilada e outra com água destilada e acrescida de 1% de DMSO e quatro concentrações: 1,85g/mL (10%); 3,7g/mL (20%); 5,55g/mL (30%) e 9,25 mg/mL (50%), totalizando seis tratamentos. Observou-se efeito ?dose-resposta? inibitório significativo (P<0,05) em todos as variáveis avaliadas, nas sementes das três cultivares estudadas. Sabendo-se que os compostos hormonais agem estimulando ou inibindo o metabolismo celular, sugere-se que os efeitos alelopáticos observados no presente trabalho possam estar relacionados ao efeito direto das saponinas esteroidais nas células das sementes e das plântulas das B. brizantha avaliadas. Conclui-se que o extrato bruto de Brachiaria decumbens BRA001996 reduz o vigor e a germinação das sementes, bem como o vigor das plântulas de Brachiaria brizantha, cultivares Xaraés, Piatã e Marandu.bitstream/item/68749/1/DOC188.pd

    Nutritional and functional characteristics of Erophaca baetica seeds, a legume endemic to the Mediterranean region

    Get PDF
    <i>Erophaca baetica</i> is a legume endemic to the Mediterranean region. Although the fruits and seeds are large, the presence of the “locoism” which produces the alkaloid, swainsonine has prevented its use as animal feed or for human nutrition. Their protein content and chromatographic profile, amino acid composition, fatty acid composition, and polyphenol contents have been determined in order to explore the potential of the <i>E. baetica</i> seeds as a source of dietary protein with functional components. The protein content was found to be 36% (w/w), and an amino acid analysis revealed a deficiency in sulphur amino acids, tryptophane, and lysine. The low lysine content is probably due to the abundance of alkaloids metabolically derived from this amino acid. Oleic and linoleic acids are the major fatty acids in the seeds. The antioxidant activity of polyphenol extracts was higher than the activity of the polyphenols extracted from most edible legume seeds. Hence, <i>E. baetica</i> seeds represent a promising source of functional and nutritional components on the condition that the anti-nutritional alkaloids are previously removed.<br><br><i>Erophaca baetica</i> es una leguminosa endémica de la región mediterránea. Aunque los frutos y las semillas son grandes, la presencia del alcaloide swainsonina causante de locoismo, ha impedido su uso como alimento para animales o para nutrición humana. El contenido proteico y su perfil cromatográfico, la composición de aminoácidos, de ácidos grasos, y contenido de polifenoles se han determinado con el fin de explorar el potencial de las semillas de <i>E. baetica</i> como una fuente de proteínas y de componentes funcionales de la dieta. El contenido de proteínas es del 36% (w / w), y el análisis de aminoácidos reveló deficiencia en aminoácidos azufrados, triptófano y lisina. El contenido de lisina bajo es probablemente debido a la abundancia de alcaloides metabólicamente derivados de este aminoácido. Los ácidos oleicos y linoleico son los principales ácidos grasos en las semillas. La actividad antioxidante de los extractos de polifenoles fue mayor que la actividad de los polifenoles extraídos de la mayoría de las semillas de leguminosas comestibles. Por lo tanto, las semillas de <i>E. baetica</i> representan una fuente interesante de componentes funcionales y nutricionales con la condición de que los alcaloides antinutricionales sean quitados antes

    Overall Survival Time Prediction for High-grade Glioma Patients based on Large-scale Brain Functional Networks

    Get PDF
    High-grade glioma (HGG) is a lethal cancer with poor outcome. Accurate preoperative overall survival (OS) time prediction for HGG patients is crucial for treatment planning. Traditional presurgical and noninvasive OS prediction studies have used radiomics features at the local lesion area based on the magnetic resonance images (MRI). However, the highly complex lesion MRI appearance may have large individual variability, which could impede accurate individualized OS prediction. In this paper, we propose a novel concept, namely brain connectomics-based OS prediction. It is based on presurgical resting-state functional MRI (rs-fMRI) and the non-local, large-scale brain functional networks where the global and systemic prognostic features rather than the local lesion appearance are used to predict OS. We propose that the connectomics features could capture tumor-induced network-level alterations that are associated with prognosis. We construct both low-order (by means of sparse representation with regional rs-fMRI signals) and high-order functional connectivity (FC) networks (characterizing more complex multi-regional relationship by synchronized dynamics FC time courses). Then, we conduct a graph-theoretic analysis on both networks for a jointly, machine-learning-based individualized OS prediction. Based on a preliminary dataset (N = 34 with bad OS, mean OS, ~400 days; N = 34 with good OS, mean OS, ~1030 days), we achieve a promising OS prediction accuracy (86.8%) on separating the individuals with bad OS from those with good OS. However, if using only conventionally derived descriptive features (e.g., age and tumor characteristics), the accuracy is low (63.2%). Our study highlights the importance of the rs-fMRI and brain functional connectomics for treatment planning
    corecore