558 research outputs found

    X-ray diffraction from shock-loaded polycrystals

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    X-ray diffraction was demonstrated from shock-compressed polycrystalline metal on nanosecond time scales. Laser ablation was used to induce shock waves in polycrystalline foils of Be, 25 to 125 microns thick. A second laser pulse was used to generate a plasma x-ray source by irradiation of a Ti foil. The x-ray source was collimated to produce a beam of controllable diameter, and the beam was directed at the Be sample. X-rays were diffracted from the sample, and detected using films and x-ray streak cameras. The diffraction angle was observed to change with shock pressure. The diffraction angles were consistent with the uniaxial (elastic) and isotropic (plastic) compressions expected for the loading conditions used. Polycrystalline diffraction will be used to measure the response of the crystal lattice to high shock pressures and through phase changes

    A Remote Laser System for Material Characterization at High Temperatures

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    For many years, new techniques have been developed to overcome the problems involved with the generation and detection of ultrasound in materials at high temperature [1,2]. A non-contacting technique is described using lasers to generate and detect ultrasound and which can be used to study the variation in acoustic velocity as a function of temperature. Results are presented for the change in longitudinal velocity (vâ„“) with increasing temperature in five polycrystalline materials, namely Dural, aluminum, AISI-310 stainless steel, iron and graphite

    Selective in vitro replication of herpes simplex virus type 1 (HSV-1) ICP34.5 null mutants in primary human CNS tumours--evaluation of a potentially effective clinical therapy.

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    Primary tumours of the central nervous system (CNS) are an important cause of cancer-related deaths in adults and children. CNS tumours are mostly glial cell in origin and are predominantly astrocytomas. Conventional therapy of high-grade gliomas includes maximal resection followed by radiation treatment. The addition of adjuvant chemotherapy provides little improvement in survival time and hence assessment of novel therapies is imperative. We have evaluated the potential therapeutic use of the herpes simplex virus (HSV) mutant 1716 in the treatment of primary brain tumours. The mutant is deleted in the RL1 gene and fails to produce the virulence factor ICP34.5. 1716 replication was analysed in both established human glioma cell lines and in primary cell cultures derived from human tumour biopsy material. In the majority of cultures, virus replication occurred and consequential cell death resulted. In the minority of tumour cell lines which are non-permissive for mutant replication, premature shut-off of host cell protein synthesis was induced in response to lack of expression of ICP34.5. Hence RL1-negative mutants have the distinct advantage of providing a double hit phenomenon whereby cell death could occur by either pathway. Moreover, 1716, by virtue of its ability to replicate selectively within a tumour cell, has the potential to deliver a 'suicide' gene product to the required site immediately. It is our opinion that HSV which fails to express ICP34.5 could provide an effective tumour therapy

    NASA's Understanding of Risk in Apollo and Shuttle

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    Mathematical risk analysis was used in Apollo, but it gave unacceptably pessimistic resultsand was discontinued. Shuttle was designed without using risk analysis, under the assumptionthat good engineering would make it very safe. This approach led to an unnecessarily riskydesign, which directly led to the Shuttle tragedies. Although the Challenger disaster wasdirectly due to a mistaken launch decision, it might have been avoided by a safer design. Theultimate cause of the Shuttle tragedies was the Apollo era decision to abandon risk analysis

    A newly designed virtual tour of a Radiotherapy Department for improving patient experience initial staff qualitative evaluation

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    Abstract: Introduction More informed patients are likely to be more relaxed and less anxious on their cancer journey; evidence suggests knowing practical aspects of attending for radiotherapy and what to expect are very important(1-4). Departmental open evenings providing greater information support, help reduce anxiety and distress levels(5-6). More recently, virtual methods have been used – which is our approach here; by developing a digital virtual tour by local level 3 computer science students, as part of the Innovation Project for Clatterbridge Cancer Centre Liverpool (CCCL). Initial design and evaluation with patients have been undertaken(7). Knowing that Therapeutic Radiographers (TRs) are the natural eyes and ears for capturing the patient voice, we here report the initial evaluation from TR focus groups conducted at CCCL. Method Evaluation by patients used a mixed-methods survey(7). Control (n=9) and intervention (n=14) groups were established – the latter completing the survey after watching the virtual tour. Simultaneously, TR focus groups were conducted (n=17) using open-ended questions for evaluation. Results Qualitative results from TRs covered a wide range of evaluative comments and suggestions for improvement and development. All (100%) felt the virtual tour was a positive addition to the patient’s journey. Some commented it provided a good alternative to in-person open evenings, with enough information delivered at a good pace. The radiographer avatar was in uniform and spoke with a regional accent – both aspects were commented as being usefully informative, with a style and approach considered highly personable. Highlighting available facilities (like the beverage bar) and the inside of the treatment room were particularly noted in allowing patients to know exactly what to expect and help remove fear of the unknown. Improvements were suggested, to further expand the ‘reach’ of the virtual tour – e.g. to highlight transport, phlebotomy and pharmacy services; or link to Macmillan and Chemotherapy suites; and extend into further aspects such as pre-treatment and even how radiotherapy works. Conclusion The responses from this initial evaluation with TRs, who are at the frontline of providing care for radiotherapy patients, has been highly positive – complementing patient responses which, for example, showed reductions in anxiety and improvements in confidence and knowledge in practical matters (such as queue and changing room systems), together with knowing better what to expect through to the treatment room. Its introduction can now be the foundation for providing further key information prior to treatment start, alleviating anxiety and improving the patient experience still further

    Transposon mutagenesis in Mycobacterium kansasii links a small RNA gene to colony morphology and biofilm formation and identifies 9,885 intragenic insertions that do not compromise colony outgrowth

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    Mycobacterium kansasii (Mk) is a resilient opportunistic human pathogen that causes tuberculosis-like chronic pulmonary disease and mortality stemming from comorbidities and treatment failure. The standard treatment of Mk infections requires costly, long-term, multidrug courses with adverse side effects. The emergence of drug-resistant isolates further complicates the already challenging drug therapy regimens and threatens to compromise the future control of Mk infections. Despite the increasingly recognized global burden of Mk infections, the biology of this opportunistic pathogen remains essentially unexplored. In particular, studies reporting gene function or generation of defined mutants are scarce. Moreover, no transposon (Tn) mutagenesis tool has been validated for use in Mk, a situation limiting the repertoire of genetic approaches available to accelerate the dissection of gene function and the generation of gene knockout mutants in this poorly characterized pathogen. In this study, we validated the functionality of a powerful Tn mutagenesis tool in Mk and used this tool in conjunction with a forward genetic screen to establish a previously unrecognized role of a conserved mycobacterial small RNA gene of unknown function in colony morphology features and biofilm formation. We also combined Tn mutagenesis with next-generation sequencing to identify 12,071 Tn insertions that do not compromise viability in vitro. Finally, we demonstrated the susceptibility of the Galleria mellonella larva to Mk, setting the stage for further exploration of this simple and economical infection model system to the study of this pathogen

    Synthetic biology: Building the language for a new science brick by metaphorical brick

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    Changes in the biosciences and their relations to society over the last decades provide a unique opportunity to examine whether or not such changes leave traces in the language we use to talk about them. In this article we examine metaphors used in English-speaking press coverage to conceptualize a new type of (interdisciplinary) bioscience: synthetic biology. Findings show that three central metaphors were used between 2008 and May 2010. They exploit social and cultural knowledge about books, computers and engines and are linked to knowledge of three revolutions in science and society (the printing, information and industrial revolutions). These three central metaphors are connected to each other through the concepts of reading/writing, designing and mass production and they focus on science as a revolutionary process rather than on the end results or products of science. Overall, we observed the use of a complex bricolage of mixed metaphors and chains of metaphors that root synthetic biology in historical events and achievements, while at the same time extolling its promises for the future. © 2011 Copyright Taylor and Francis Group, LLC
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