305 research outputs found

    Low-cost detection of lasers

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    Use of a novel fiber optical strain sensor for monitoring the vertical deflection of an aircraft flap

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    The present paper reports the use of a plastic optical fiber-based sensor for elongation measurements in an aircraft flap subjected to different types of flexural loading conditions. The sensor, bonded to the surface of the aircraft structure, relies on measuring the phase shift that occurs between two sinusoidally modulated light signals when the aircraft structure is bent. The light signals are guided through two optical fibers, one of them fixed to the top surface of the flap, and the other one to the bottom surface. The sensor offers good signal stability and repeatability and represents a cost-effective alternative to other more sophisticated health-monitoring systems currently used.Publicad

    Concise total synthesis of (+)-gliocladins B and C

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    The first total synthesis of (+)-gliocladin B is described. Our concise and enantioselective synthesis takes advantage of a new regioselective Friedel–Crafts-based strategy to provide an efficient multigram-scale access to the C3-(3â€Č-indolyl)hexahydropyrroloindole substructure, a molecular foundation present in a significant subset of epipolythiodiketopiperazine natural alkaloids. Our first-generation solution to (+)-gliocladin B involved the stereoselective formation of (+)-12-deoxybionectin A, a plausible biosynthetic precursor. Our synthesis clarified the C15 stereochemistry of (+)-gliocladin B and allowed its full structure confirmation. Further studies of a versatile dihydroxylated diketopiperazine provided a concise and efficient synthesis of (+)-gliocladin B as well as access to (+)-gliocladin C.National Institute of General Medical Sciences (U.S.) (GM089732)Amgen Inc.National Science Foundation (U.S.) (CHE-0946721

    A forensic acquisition and analysis system for IaaS

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    Cloud computing is a promising next-generation computing paradigm that offers significant economic benefits to both commercial and public entities. Furthermore, cloud computing provides accessibility, simplicity, and portability for its customers. Due to the unique combination of characteristics that cloud computing introduces (including on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service), digital investigations face various technical, legal, and organizational challenges to keep up with current developments in the field of cloud computing. There are a wide variety of issues that need to be resolved in order to perform a proper digital investigation in the cloud environment. This paper examines the challenges in cloud forensics that are identified in the current research literature, alongside exploring the existing proposals and technical solutions addressed in the respective research. The open problems that need further effort are highlighted. As a result of the analysis of literature, it is found that it would be difficult, if not impossible, to perform an investigation and discovery in the cloud environment without relying on cloud service providers (CSPs). Therefore, dependence on the CSPs is ranked as the greatest challenge when investigators need to acquire evidence in a timely yet forensically sound manner from cloud systems. Thus, a fully independent model requires no intervention or cooperation from the cloud provider is proposed. This model provides a different approach to a forensic acquisition and analysis system (FAAS) in an Infrastructure as a Service model. FAAS seeks to provide a richer and more complete set of admissible evidences than what current CSPs provide, with no requirement for CSP involvement or modification to the CSP’s underlying architecture

    Synthesis and anticancer activity of epipolythiodiketopiperazine alkaloids

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    The epipolythiodiketopiperazine (ETP) alkaloids are a highly complex class of natural products with potent anticancer activity. Herein, we report the application of a flexible and scalable synthesis, allowing the construction of dozens of ETP derivatives. The evaluation of these compounds against cancer cell lines in culture allows for the first expansive structure–activity relationship (SAR) to be defined for monomeric and dimeric ETP-containing natural products and their synthetic cognates. Many ETP derivatives demonstrate potent anticancer activity across a broad range of cancer cell lines and kill cancer cells via induction of apoptosis. Several traits that bode well for the translational potential of the ETP class of natural products include concise and efficient synthetic access, potent induction of apoptotic cell death, activity against a wide range of cancer types, and a broad tolerance for modifications at multiple sites that should facilitate small-molecule drug development, mechanistic studies, and evaluation in vivo.National Institute of General Medical Sciences (U.S.) (Grant GM089732)American Society for Engineering Education. National Defense Science and Engineering Graduate FellowshipCamille & Henry Dreyfus Foundation. Teacher-Scholar Awards Progra

    Global Law as Intercontextuality and as Interlegality

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    Since the 1990s the effects of globalization on law and legal developments has been a central topic of scholarly debate. To date, the debate is however marked by three substantial deficiencies which this chapter seeks to remedy through a reconceptualization of global law as a law of inter-contextuality expressed through inter-legality and materialized through a particular body of legal norms which can be characterized as connectivity norms. The first deficiency is a historical and empirical one. Both critics as well as advocates of ‘non-state law’ share the assumption that ‘law beyond the state’ and related legal norms have gained in centrality when compared with previous historical times. While global law, including both public and private global governance law as well as regional occurrences such as EU law, has undergone profound transformations since the structural transformations which followed the de-colonialization processes of the mid-twentieth century, we do not have more global law relatively to other types of law today than in previous historical times. The second deficiency is a methodological one. The vast majority of scholarship on global law is either of an analytical nature, drawing on insights from philosophy, or empirically observing the existence of global law and the degree of compliance with global legal norms at a given moment in time. While both approaches bring something to the table they remain static approaches incapable of explaining and evaluating the transformation of global law over time. The third deficiency is a conceptual-theoretical one. In most instances, global law is understood as a unitary law producing singular legal norms with a planetary reach, or, alternatively, a radical pluralist perspective is adopted dismissing the existence of singular global norms. Both of these approaches however misapprehend the structural characteristics, function and societal effects of global law. Instead a third positon between unitary and radical pluralist perspectives can be adopted through an understanding of global law and its related legal norms as a de-centred kind of inter-contextual law characterised by inter-legality

    Biogenetically-Inspired Total Synthesis of Epidithiodiketopiperazines and Related Alkaloids

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    Natural products chemistry has historically been the prime arena for the discovery of new chemical transformations and the fountain of insights into key biological processes. It remains a fervent incubator of progress in the fields of chemistry and biology and an exchange mediating the flow of ideas between these allied fields of science. It is with this ethos that our group has taken an interest in and pursued the synthesis of a complex family of natural products termed the dimeric epipolythiodiketopiperazine (ETP) alkaloids. We present here an Account of the highly complex target molecules to which we pegged our ambitions, our systematic and relentless efforts toward those goals, the chemistry we developed in their pursuit, and the insight we have gained for their translational potential as potent anticancer molecules.National Institute of General Medical Sciences (U.S.) (Grant GM089732)Amgen Inc
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