13,002 research outputs found

    X-Ray Tomography To Measure Size Of Fragments From Penetration Of High-Velocity Tungsten Rods

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    Behind-armor debris that results from tungsten rods penetrating armor steel at 2 km/s was studied by analysis of recovered fragments. Fragment recovery was by means of particle board. Individual fragments were analyzed by x-ray tomography, which provides information for fragment identification, mass, shape, and penetration down to masses of a few milligrams. The experiments were complemented by AUTODYN and EPIC calculations. Fragments were steel or tungsten generated from the channel or from the breakout through the target rear surface. Channel fragment motions were well described by Tate theory. Breakout fragments had velocities from the projectile remnant to the channel velocity, apparently depending on where in the projectile a fragment originated. The fragment size distribution was extremely broad and did not correlate well with simple uniform-fragment-size models.Mechanical Engineerin

    A research protocol for developing a Point-Of-Care Key Evidence Tool 'POCKET': a checklist for multidimensional evidence reporting on point-of-care in vitro diagnostics.

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    INTRODUCTION: Point-of-care in vitro diagnostics (POC-IVD) are increasingly becoming widespread as an acceptable means of providing rapid diagnostic results to facilitate decision-making in many clinical pathways. Evidence in utility, usability and cost-effectiveness is currently provided in a fragmented and detached manner that is fraught with methodological challenges given the disruptive nature these tests have on the clinical pathway. The Point-of-care Key Evidence Tool (POCKET) checklist aims to provide an integrated evidence-based framework that incorporates all required evidence to guide the evaluation of POC-IVD to meet the needs of policy and decisionmakers in the National Health Service (NHS). METHODS AND ANALYSIS: A multimethod approach will be applied in order to develop the POCKET. A thorough literature review has formed the basis of a robust Delphi process and validation study. Semistructured interviews are being undertaken with POC-IVD stakeholders, including industry, regulators, commissioners, clinicians and patients to understand what evidence is required to facilitate decision-making. Emergent themes will be translated into a series of statements to form a survey questionnaire that aims to reach a consensus in each stakeholder group to what needs to be included in the tool. Results will be presented to a workshop to discuss the statements brought forward and the optimal format for the tool. Once assembled, the tool will be field-tested through case studies to ensure validity and usability and inform refinement, if required. The final version will be published online with a call for comments. Limitations include unpredictable sample representation, development of compromise position rather than consensus, and absence of blinding in validation exercise. ETHICS AND DISSEMINATION: The Imperial College Joint Research Compliance Office and the Imperial College Hospitals NHS Trust R&D department have approved the protocol. The checklist tool will be disseminated through a PhD thesis, a website, peer-reviewed publication, academic conferences and formal presentations

    Innovation, Adoption, Ownership, and Productivity: Evidence from Ukraine

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    How do new and foreign firms achieve superior productivity? Do they conduct more and better R&D? Or do they distinguish themselves through computerization and organizational capital? We investigate the determinants of and returns to several types of investment, using a panel of over 40,000 Ukrainian industrial firms in 2000-2007. Foreign firms engage in more non-technological investment and IT and less in R&D than domestic private firms. Similarly, new firms invest more in non-technological capital and IT and less in R&D than initially state-owned firms. Productivity gains from R&D and non-technology investment are insignificantly different across ownership types, whereas foreign firms achieve much higher returns to IT investment than other firms. These results suggest that foreign firms outperform others via organizational capital that is better able to exploit IT investment. New firm productivity growth is a result of higher investment volume rather than investment efficiency.R&D, information technology, foreign ownership, transition, Eastern Europe, Ukraine

    Android Malware Clustering through Malicious Payload Mining

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    Clustering has been well studied for desktop malware analysis as an effective triage method. Conventional similarity-based clustering techniques, however, cannot be immediately applied to Android malware analysis due to the excessive use of third-party libraries in Android application development and the widespread use of repackaging in malware development. We design and implement an Android malware clustering system through iterative mining of malicious payload and checking whether malware samples share the same version of malicious payload. Our system utilizes a hierarchical clustering technique and an efficient bit-vector format to represent Android apps. Experimental results demonstrate that our clustering approach achieves precision of 0.90 and recall of 0.75 for Android Genome malware dataset, and average precision of 0.98 and recall of 0.96 with respect to manually verified ground-truth.Comment: Proceedings of the 20th International Symposium on Research in Attacks, Intrusions and Defenses (RAID 2017

    Association of molecules using a resonantly modulated magnetic field

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    We study the process of associating molecules from atomic gases using a magnetic field modulation that is resonant with the molecular binding energy. We show that maximal conversion is obtained by optimising the amplitude and frequency of the modulation for the particular temperature and density of the gas. For small modulation amplitudes, resonant coupling of an unbound atom pair to a molecule occurs at a modulation frequency corresponding to the sum of the molecular binding energy and the relative kinetic energy of the atom pair. An atom pair with an off-resonant energy has a probability of association which oscillates with a frequency and time-varying amplitude which are primarily dependent on its detuning. Increasing the amplitude of the modulation tends to result in less energetic atom pairs being resonantly coupled to the molecular state, and also alters the dynamics of the transfer from continuum states with off-resonant energies. This leads to maxima and minima in the total conversion from the gas as a function of the modulation amplitude. Increasing the temperature of the gas leads to an increase in the modulation frequency providing the best fit to the thermal distribution, and weakens the resonant frequency dependence of the conversion. Mean-field effects can alter the optimal modulation frequency and lead to the excitation of higher modes. Our simulations predict that resonant association can be effective for binding energies of order h×1h \times 1 MHz.Comment: 8 pages latex, figures revised, references updated and typos correcte

    Women’s perspectives on the value of a father’s initiative in shifting gendered practices within families

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    This paper explores the qualitative perspectives of women about a community embedded fathers initiative in Northern England. Projects to improve the wellbeing of men and their children are less common within the landscape of parent and child support, with mothers more often being the target recipients. Asking women about their perceptions of an initiative for fathers then offers original insights from women who are positioned as ‘related outsiders’, in that they were ‘outside’ the project but ‘inside’ the family and community. Findings suggest that women are able to see the positive impact of such a project, identifying that it offers a shared space for men and children, time for mothers without their children and can help with shifting roles and attitudes around child care and emotional labour in the home. The initiative was also seen by the women as offering men more healthy means of coping, including men moving away from traditional hegemonic practices, which in turn shifted some women’s long held gendered beliefs about men as fathers. This research then offers a relational gendered backstory to a father’s initiative, demonstrating how such initiatives can potentially ‘undo’ gender and the positive implications this could have for families

    Robust entanglement generation by reservoir engineering

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    Following a recent proposal [C. Muschik et. al., Phys. Rev. A 83, 052312 (2011)], engineered dissipative processes have been used for the generation of stable entanglement between two macroscopic atomic ensembles at room temperature [H. Krauter et. al., Phys. Rev. Lett. 107, 080503 (2011)]. This experiment included the preparation of entangled states which are continuously available during a time interval of one hour. Here, we present additional material, further-reaching data and an extension of the theory developed in [C. Muschik et. al., Phys. Rev. A 83, 052312 (2011)]. In particular, we show how the combination of the entangling dissipative mechanism with measurements can give rise to a substantial improvement of the generated entanglement in the presence of noise.Comment: Submitted to Journal of Physics B, special issue on "Quantum Memory
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