Self-excited vibrations in turning: cutting moment analysis

This work aims at analysing the moment effects at the tool tip point and at the central axis, in the framework of a turning process. A testing device in turning, including a six-component dynamometer, is used to measure the complete torsor of the cutting actions in the case of self-excited vibrations. Many results are obtained regarding the mechanical actions torsor. A confrontation of the moment components at the tool tip and at the central axis is carried out. It clearly appears that analysing moments at the central axis avoids the disturbances induced by the transport of the moment of the mechanical actions resultant at the tool tip point. For instance, the order relation between the components of the forces is single. Furthermore, the order relation between the moments components expressed at the tool tip point is also single and the same one. But at the central axis, two different order relations regarding moments are conceivable. A modification in the rolling moment localization in the (y, z) tool plan is associated to these two order relations. Thus, the moments components at the central axis are particularly sensitive at the disturbances of machining, here the self-excited vibrations.Comment: 8 page

Cost Effectiveness of New Diagnostic Tools for Cutaneous Leishmaniasis in Afghanistan

Background and Objectives: Cutaneous leishmaniasis is responsible for chronic and disfguring skin lesions resulting in morbidity and social stigma. The gold standard to diagnose cutaneous leishmaniasis is microscopy but has a variable sensitivity and requires trained personnel. Using four scenarios, the objective of this study is to compare the cost efectiveness of microscopy with two new tools: Loopamp™ Leishmania Detection Kit (LAMP) and CL Detect™ Rapid Test (RDT). Methods: Data related to the cost and accuracy of these tools were collected at the clinic of the National Malaria and Leishmaniasis Control Program in Kabul, Afghanistan. The efectiveness estimates were measured based on the tools’ performance but also indirectly, using the disability-adjusted life years. A decision tree was designed in TreeAge Healthcare Pro 2016, combined with a Markov model representing the natural history of cutaneous leishmaniasis. In addition to a deterministic analysis, univariate sensitivity and probabilistic analyses were performed to test the robustness of the results. Results: If the tools are compared at the National Malaria and Leishmaniasis Control Program level in a period of low incidence, microscopy remains the preferred option. LAMP becomes more appropriate during cutaneous leishmaniasis seasons or outbreaks when its capacity to process several tests (e.g. up to 48) at a time can be maximised. RDT has a cost similar to microscopy when used at the reference clinic but as it is relatively easy to use, it could be implemented at the peripheral level, which would become cheaper than employing microscopy at the reference clinic. Moreover, combining RDT with microscopy or LAMP at the reference clinic for the negative suspects is economically more interesting than directly performing LAMP or microscopy respectively on all cutaneous leishmaniasis suspects at the reference clinic. Conclusions: When taking advantage of their respective strengths, LAMP and RDT can prove to be cost-efective alternatives to using microscopy alone at the reference clinic

Toward a real-time tracking of dense point-sampled geometry

4 pagesInternational audienceIn this paper, we address the problem of tracking temporal deformations between two arbitrary densely sampled point-based surfaces. We propose an intuitive and efficient resolution to the point matching problem within two frames of a sequence. The proposed method utilizes two distinct space partition trees, one for each point cloud, which both are defined on a unique discrete space. Our method takes advantage of multi-resolution concerns, voxel adjacency relations, and a specific distance function. Experimental results obtained from both simulated and real reconstructed data sets demonstrate that the proposed method can handle efficiently the tracking process even for very large point clouds. Moreover, our method is easy to implement and very fast, which provides possibilities for real-time tracking applications

From resilience to viability: a case study of indigenous communities of the North Rupununi, Guyana

'Resilience' is a term that has achieved significant prominence in scientific circles and now within popular discourse. However, its practical application is often unclear or confused because it can mean different things to different people: To resist? To adapt? To transform? In this paper, we propose a framework - System Viability - able to coherently engage with six distinct properties of all systems, from ecosystems to communities, allowing the identification of trade-offs and synergies for maximising the chances of systems persistence. We apply and evaluate the System Viability framework through participatory visual methods within three indigenous communities in the North Rupununi, Guyana. This paper highlights how the framework allows the measurement of community survival strategies in a consistent and theoretically corroborated way, with implications for national and international policy-makers aiming to promote resilience and sustainability

Indigenous identity and environmental governance in Guyana, South America

In an era of increasing access to digital technologies, Indigenous communities are progressively more able to present sophisticated and differentiated narratives in order to maximise their long-term survival. In this article, we explore how Indigenous communities use participatory video and participatory photography as tools of Indigenous media to enhance, adapt and/or reinforce their collective social memory. This social memory is key for identity formation and self-representation, and the ways in which Indigenous representations are performed promote particular interests and worldviews to the local, national and global scales. Working with the Makushi and Wapishana communities of the North Rupununi, Guyana, the current social memory ‘in use’ was surfaced through the participatory video and photography process led by the Indigenous community. Through an iterative process of analysing images (photos and video clips) and text (written material, narration and spoken word), we identified key narratives of the communities’ social memory. We show how communities provide different messages to different actors through the way they use participatory video and participatory photography, revealing how self-conscious multiple identities shape differing purposes. We suggest that our ability, as non-Indigenous stakeholders, to perceive, appreciate and act upon these more complex and nuanced narratives is critical to help address environmental governance in a rapidly changing social–ecological context

Applying the system viability framework for cross-scalar governance of nested social-ecological systems in the Guiana Shield, South America

Linking and analyzing governance of natural resources at different scales requires the development of a conceptual framework for analyzing social-ecological systems that can be easily applied by a range of stakeholders whose interests lie at different scales, but where the results of the analysis can be compared in a straightforward way. We outline the system viability framework, which allows participants to characterize a range of strategies in response to environment challenges for maintaining the long-term survival of their particular system of interest. Working in the Guiana Shield, South America, and with a range of local, regional, and international stakeholders, our aim was to use system viability to (1) investigate synergies and conflicts between distinct scales of governance, (2) identify scale-related challenges, and (3) test the framework as a conceptual tool for supporting cross-scalar analysis for environmental governance. At the international and national levels, a number of civil society organizations explored system viability indicators that would measure the successful implementation of governance mechanisms relevant to sustainable development and natural resource management. At the local level, we used participatory video and photography within two indigenous territories to enable local participants to identify indicators of viability within community governance systems. A grounded theory approach was then used to identify common themes across the different scales of analysis. Five key themes emerged: land rights, leadership, partnerships, lifestyle, and identity. We found that although most categories of interest were theoretically aligned across scales, all perceived systems of interest were struggling to face up to various cross-scalar challenges undermining different system viability responses. In conclusion, we highlight how the system viability framework can be used with a disparate variety of stakeholders as a practical, participative and “big-picture” approach for facilitating the integrated governance of nested local and regional social-ecological systems

Community owned solutions: identifying local best practices for social-ecological sustainability

Policies and actions that come from higher scale structures, such as international bodies and national governments, are not always compatible with the realities and perspectives of smaller scale units including indigenous communities. Yet, it is at this local social-ecological scale that mechanisms and solutions for dealing with unpredictability and change can be increasingly seen emerging from across the world. Although there is a large body of knowledge specifying the conditions necessary to promote local governance of natural resources, there is a parallel need to develop practical methods for operationalizing the evaluation of local social-ecological systems. In this paper, we report on a systemic, participatory, and visual approach for engaging local communities in an exploration of their own social-ecological system. Working with indigenous communities of the North Rupununi, Guyana, this involved using participatory video and photography within a system viability framework to enable local participants to analyze their own situation by defining indicators of successful strategies that were meaningful to them. Participatory multicriteria analysis was then used to arrive at a short list of best practice strategies. We present six best practices and show how they are intimately linked through the themes of indigenous knowledge, local governance and values, and partnerships and networks. We highlight how developing shared narratives of community owned solutions can help communities to plan governance and management of land and resource systems, while reinforcing sustainable practices by discussing and showcasing them within communities, and by engendering a sense of pride in local solutions

Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey

The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust properties of these quasars finding an unusual dust extinction curve for one quasar and a high far-infrared luminosity due to dust emission for another. The mean millimeter continuum flux for CFHQS quasars is substantially lower than that for SDSS quasars at the same redshift, likely due to a correlation with quasar UV luminosity. For two quasars with sufficiently high signal-to-noise optical spectra, we use the spectra to investigate the ionization state of hydrogen at z>5. For CFHQS J1509-1749 at z=6.12, we find significant evolution (beyond a simple extrapolation of lower redshift data) in the Gunn-Peterson optical depth at z>5.4. The line-of-sight to this quasar has one of the highest known optical depths at z~5.8. An analysis of the sizes of the highly-ionized near-zones in the spectra of two quasars at z=6.12 and z=6.43 suggest the IGM surrounding these quasars was substantially ionized before these quasars turned on. Together, these observations point towards an extended reionization process, but we caution that cosmic variance is still a major limitation in z>6 quasar observations.Comment: 15 pages, 9 figures, AJ, in press, minor changes to previous versio

The effect of dynamic recrystallisation on the rheology and microstructures of partially molten rocks

This work was founded by the joint project “Rheology of the continental crust in collision”, funded by the Procope scheme of PHC Egide in France and by the DAAD PPP scheme in Germany. M-GL acknowledges the support of the Juan de la Cierva programme of the Government of Spain’s Ministry for Science, Innovation and Universities. EGR acknowledges the support of the Beatriu de Pinós programme of the Government of Catalonia's Secretariat for Universities and Research of the Department of Economy and Knowledge (2016 BP 00208). This work benefited from discussions with Pi L. Jolivet and E. Burov within the ERC project RHEOLITH. We thank Elisabetta Mariani and Marcin Dabrowski for their helpful comments, together with the editorial guidance of Dave Healy and Bill Dunne.Peer reviewedPostprin

The Canada-France High-z Quasar Survey: nine new quasars and the luminosity function at redshift 6

We present discovery imaging and spectroscopy for nine new z ~ 6 quasars found in the Canada-France High-z Quasar Survey (CFHQS) bringing the total number of CFHQS quasars to 19. By combining the CFHQS with the more luminous SDSS sample we are able to derive the quasar luminosity function from a sample of 40 quasars at redshifts 5.74 < z < 6.42. Our binned luminosity function shows a slightly lower normalisation and flatter slope than found in previous work. The binned data also suggest a break in the luminosity function at M_1450 approx -25. A double power law maximum likelihood fit to the data is consistent with the binned results. The luminosity function is strongly constrained (1 sigma uncertainty < 0.1 dex) over the range -27.5 < M_1450 < -24.7. The best-fit parameters are Phi(M_1450^*) = 1.14 x 10^-8 Mpc^-3 mag^-1, break magnitude M_1450^* = -25.13 and bright end slope beta = -2.81. However the covariance between beta and M_1450^* prevents strong constraints being placed on either parameter. For a break magnitude in the range -26 < M_1450^* < -24 we find -3.8 < beta < -2.3 at 95% confidence. We calculate the z = 6 quasar intergalactic ionizing flux and show it is between 20 and 100 times lower than that necessary for reionization. Finally, we use the luminosity function to predict how many higher redshift quasars may be discovered in future near-IR imaging surveys.Comment: 15 pages, 9 figures, AJ in pres