10,768 research outputs found

    Certain comments on the application of the method of averaging to the study of the rotational motions of a triaxial rigid body

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    Averaging technique applied to variational equations describing rotational motions of rigid triaxial body in elliptical orbi

    Further comments on the application of the method of averaging to the study of the rotational motions of a triaxial rigid body, part 2

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    The second and final step in the development of first-order secular solutions to rotational motions of triaxial bodies is presented

    Application of the methods of celestial mechanics to the rigid body problem Final report, 1 Jul. 1965 - 1 Jun. 1966

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    Celestial mechanics perturbation methods applied to problem of describing motion of rigid artificial earth satellite about its center of mas

    Limit Theorems For Quantum Walks Associated with Hadamard Matrices

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    We study a one-parameter family of discrete-time quantum walk models on the line and in the xy-plane associated with the Hadamard walk. Weak convergence in the long-time limit of all moments of the walker's pseudo-velocity on the line and in the xy-plane is proved. Symmetrization on the line and in the xy-plane is theoretically investigated, leading to the resolution of the Konno-Namiki-Soshi conjecture in the special case of symmetrization of the unbiased Hadamard walk on the line . A necessary condition for the existence of a phenomenon known as localization is given

    Chromosome 9p deletion in clear cell renal cell carcinoma predicts recurrence and survival following surgery

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    BACKGROUND: Wider clinical applications of 9p status in clear cell renal cell carcinoma (ccRCC) are limited owing to the lack of validation and consensus for interphase fluorescent in situ hybridisation (I-FISH) scoring technique. The aim of this study was to analytically validate the applicability of I-FISH in assessing 9p deletion in ccRCC and to clinically assess its long-term prognostic impact following surgical excision of ccRCC. METHODS: Tissue microarrays were constructed from 108 renal cell carcinoma (RCC) tumour paraffin blocks. Interphase fluorescent in situ hybridisation analysis was undertaken based on preset criteria by two independent observers to assess interobserver variability. 9p status in ccRCC tumours was determined and correlated to clinicopathological variables, recurrence-free survival and disease-specific survival. RESULTS: There were 80 ccRCCs with valid 9p scoring and a median follow-up of 95 months. Kappa statistic for interobserver variability was 0.71 (good agreement). 9p deletion was detected in 44% of ccRCCs. 9p loss was associated with higher stage, larger tumours, necrosis, microvascular and renal vein invasion, and higher SSIGN (stage, size, grade and necrosis) score. Patients with 9p-deleted ccRCC were at a higher risk of recurrence (P=0.008) and RCC-specific mortality (P=0.001). On multivariate analysis, 9p deletion was an independent predictor of recurrence (hazard ratio 4.323; P=0.021) and RCC-specific mortality (hazard ratio 4.603; P=0.007). The predictive accuracy of SSIGN score improved from 87.7% to 93.1% by integrating 9p status to the model (P=0.001). CONCLUSIONS: Loss of 9p is associated with aggressive ccRCC and worse prognosis in patients following surgery. Our findings independently confirm the findings of previous reports relying on I-FISH to detect 9p (CDKN2A) deletion

    Sustainability on engineering programmes; the need for a holistic approach

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    The teaching of sustainability on engineering curricula has increasingly become an essential feature. This has coincided with an increased focus on sustainability by professional institutions through stated policy positions and documents, though accreditation documentation has yet to be brought into line with these emerging positions. The creation of a sustainable society is a complex multi-disciplinary multi-stage project that will necessarily dominate mankind’s endeavour throughout the coming century. The pathway to a road towards sustainability will require a paradigm shift among society in general. Sustainability is a normative endeavour with uncertain outcomes requiring collaboration, teamwork and an ability to work with, respect and learn from other disciplines and professions as well as local communities and governments. This is largely new territory for the engineer. Moreover this approach can only be embraced by the engineer who sees value in and a rationale for pursuing it. Engineers must clearly see the contribution they can make; they need to see how many of the fundamental or threshold concepts in engineering can be employed as central and basic tenets of the evolving meta-discipline that is sometimes called sustainability science. This can only really be achieved if sustainability exists as a common threadline throughout programmes, in such a way that it is conceived as a necessary lens through which all engineering practice is filtered. Once this is achieved engineers will be well positioned to take the lead in moving towards developing a sustainable society rather than just designing the tools to move towards this goal as mere ‘paid hands’. This paper will examine some existing basic threshold concepts in engineering and show how these can be used to embed sustainability throughout curricula so as to provide the graduate engineer of the twenty-first century with the motivation, vision and tools to be the leaders in our shared quest to create a truly sustainable global society

    Chemical engineering in an unsustainable world: obligations and opportunities

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    Human society faces a set of unprecedented challenges emanating from the unsustainable nature of the current societal model. The creation of a new sustainable societal construct is required, essentially adopting a needs based approach over one based on ever increasing consumption. Failure to achieve this will result in the widespread destruction of our increasingly stressed environment followed quickly by inevitable collapse of society as we know it, both socially and economically. Technology alone is insufficient to meet the challenges at hand; ecological, social and economic considerations must be incorporated through a multi-faceted and multi-disciplinary approach. Because chemical engineers possess a core set of threshold concepts which are central to a sustainable society, and because engineers will ultimately help design any new society, they bear a moral and ethical responsibility to play an active and indeed central role in its development. A new engineering paradigm is required therefore, whereby sustainability becomes the context of engineering practice. To achieve this, a sustainability informed ethos must prevail throughout engineering curricula. Both professional institutions and educators bear responsibility in ensuring this happens without delay. Some key threshold concepts are presented here to demonstrate how this can be advanced through the chemical engineering curriculum

    Is attending lectures still relevant in engineering education?

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    A case study was conducted on a group of undergraduate chemical engineering students to assess the relevance of attending lectures from a student perspective and to understand why these students attend and do not attend lectures with a view to developing approaches to teaching, which are of greater interest and benefit to student learning. The students were surveyed by means of a questionnaire-type survey, which collected both quantitative and qualitative data from them. The majority of students stated that lectures are still very beneficial to their learning and are not an out-of-date mode of education. The major reasons for lecture non-attendance were time priority and curriculum overload issues with other scholarly activities and poor quality teaching. The students provided a number of suggestions to improve lectures and lecture attendance, including the incorporation of active learning in lectures, linking lectures to assessment and adding extra value to what is already in the notes

    Complementing maps, continuation and global bifurcation

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    We state, and indicate some of the consequences of, a theorem whose sole assumption is the nonvanishing of the Leray- Schauder degree of a compact vector field, and whose conclusions yield multidimensional existence, continuation and bifurcation result
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