697 research outputs found

    Huisgen-based conjugation of water-soluble porphyrins to deprotected sugars: Towards mild strategies for the labelling of glycans

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    Fully deprotected alkynyl-functionalised mono- and oligosaccharides undergo CuAAC-based conjugation with water-soluble porphyrin azides in aqueous environments. The mild reaction conditions are fully compatible with the presence of labile glycosidic bonds. This approach provides an ideal strategy to conjugate tetrapyrroles to complex carbohydrates

    A quantum computational semantics for epistemic logical operators. Part I: epistemic structures

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    Some critical open problems of epistemic logics can be investigated in the framework of a quantum computational approach. The basic idea is to interpret sentences like “Alice knows that Bob does not understand that π is irrational” as pieces of quantum information (generally represented by density operators of convenient Hilbert spaces). Logical epistemic operators (to understand, to know. . .) are dealt with as (generally irreversible) quantum operations, which are, in a sense, similar to measurement-procedures. This approach permits us to model some characteristic epistemic processes, that concern both human and artificial intelligence. For instance, the operation of “memorizing and retrieving information” can be formally represented, in this framework, by using a quantum teleportation phenomenon

    A Model for Enveloping Space Station Logistics Requirements

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    Since the inception of the Space Station customer Logistics study, it became apparent that a modeling process was needed to provide insight into the many sensitivities and relationships which exist among the numerous variables which impact Space Station Customer Accommodations and Logistics Support Requirements with regard to their associated design requirements. such a model would provide the necessary and timely support to the Space Station designers and planners during the program\u27s early development. This paper will address the current design and operations of the Space Station in particular the Manufacturing and Technology Laboratory (MTL) which is the primary focus of the study and the model. Typical experiments planned for the MTL will be addressed as well as their on-orbit operational and logistical requirements. A detailed description of the model developed under the study along with some of its many applications for scoping Space Station Logistics Requirements will be presented

    Technology Development Missions Concept Definition Study TDMX 2066 Large Inflatable/ Rigidized Structures

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    The advent of the Space Station will require the development and advancement of many new technologies. One of which is the development of Inflatable/ Rigidized Structures. This paper addresses the concept definition, feasibility and requirements for a Large Inflatable/Rigidized Hangar for Payload Servicing on the Space Station. Inflatable/Rigidized Structure Technology has existed for .many years, but applications of this technology to Space Based Elements has only begun during the past decade. Inflatable/Rigidized Structures offer a variety of benefits and applications to the Space Station, key of which is their low weight and volume requirements for transfer to the Station. A 60X40 foot foam hangar can be packaged and shipped in a specialized container approximately 46 m3 and will provide 3200 m3 of usable working/storage space. Previous studies have produced tremendous success in the area of design, fabrication and development of such Inflatable/Rigidized Structures as: a Spacelab transfer tunnel, module airlocks, platforms, large storage hangars, interconnect tunnels, and lunar habitation modules. This paper will address the technology issues/advancements which must be meet, the requirements for accommodations on the Space Station, such as crew and equipment requirements to assemble the hangar at the Station. Pre-launch ground requirements will also be addresses, which include new advanced packaging techniques for Rigidized structures. Typical Ground and On-orbit scenarios will be provided. Finally a preliminary evolutionary plan will be presented which indicates the major experiment development phases from ground based prototypes to full scale Stat-ion deployment

    Mechanisms of growth inhibition of primary prostate epithelial cells following gamma irradiation or photodynamic therapy including senscence, necrosis, and autophagy, but not apoptosis

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    In comparison to more differentiated cells, prostate cancer stem-like cells are radioresistant, which could explain radio-recurrent prostate cancer. Improvement of radiotherapeutic efficacy may therefore require combination therapy. We have investigated the consequences of treating primary prostate epithelial cells with gamma irradiation and photodynamic therapy (PDT), both of which act through production of reactive oxygen species (ROS). Primary prostate epithelial cells were cultured from patient samples of benign prostatic hyperplasia and prostate cancer prior to treatment with PDT or gamma irradiation. Cell viability was measured using MTT and alamar blue assay, and cell recovery by colony-forming assays. Immunofluorescence of gamma-H2AX foci was used to quantify DNA damage, and autophagy and apoptosis were assessed using Western blots. Necrosis and senescence were measured by propidium iodide staining and beta-galactosidase staining, respectively. Both PDT and gamma irradiation reduced the colony-forming ability of primary prostate epithelial cells. PDT reduced the viability of all types of cells in the cultures, including stem-like cells and more differentiated cells. PDT induced necrosis and autophagy, whereas gamma irradiation induced senescence, but neither treatment induced apoptosis. PDT and gamma irradiation therefore inhibit cell growth by different mechanisms. We suggest these treatments would be suitable for use in combination as sequential treatments against prostate cancer

    A first-order epistemic quantum computational semantics with relativistic-like epistemic effects

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    Quantum computation has suggested new forms of quantum logic, called quantum computational logics. In these logics well-formed formulas are supposed to denote pieces of quantum information: possible pure states of quantum systems that can store the information in question. At the same time, the logical connectives are interpreted as quantum logical gates: unitary operators that process quantum information in a reversible way, giving rise to quantum circuits. Quantum computational logics have been mainly studied as sentential logics (whose alphabet consists of atomic sentences and of logical connectives). In this article we propose a semantic characterization for a first-order epistemic quantum computational logic, whose language can express sentences like "Alice knows that everybody knows that she is pretty". One can prove that (unlike the case of logical connectives) both quantifiers and epistemic operators cannot be generally represented as (reversible) quantum logical gates. The "act of knowing" and the use of universal (or existential) assertions seem to involve some irreversible "theoretic jumps", which are similar to quantum measurements. Since all epistemic agents are characterized by specific epistemic domains (which contain all pieces of information accessible to them), the unrealistic phenomenon of logical omniscience is here avoided: knowing a given sentence does not imply knowing all its logical consequences

    Native NIR-emitting single colour centres in CVD diamond

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    Single-photon sources are a fundamental element for developing quantum technologies, and sources based on colour centres in diamonds are among the most promising candidates. The well-known NV centres are characterized by several limitations, thus few other defects have recently been considered. In the present work, we characterize in detail native efficient single colour centres emitting in the near infra-red in both standard IIa single-crystal and electronic-grade polycrystalline commercial CVD diamond samples. In the former case, a high-temperature annealing process in vacuum is necessary to induce the formation/activation of luminescent centres with good emission properties, while in the latter case the annealing process has marginal beneficial effects on the number and performances of native centres in commercially available samples. Although displaying significant variability in several photo physical properties (emission wavelength, emission rate instabilities, saturation behaviours), these centres generally display appealing photophysical properties for applications as single photon sources: short lifetimes, high emission rates and strongly polarized light. The native centres are tentatively attributed to impurities incorporated in the diamond crystal during the CVD growth of high-quality type IIa samples, and offer promising perspectives in diamond-based photonics.Comment: 27 pages, 10 figures. Submitted to "New Journal of Phsyics", NJP-100003.R
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