Cutting temperatures when ball nose end milling γ-TiAl intermetallic alloys

AbstractExperimental results are presented for Ti–45Al–2Mn–2Nb+0.8vol% TiB2XD and Ti–45Al–8Nb–0.2C alloys. Three approaches were employed involving a constantan-workpiece thermocouple arrangement, implanted K-type thermocouples and IR thermography. New and worn (~300μm flank wear) coated carbide tools were used under dry conditions when down milling at 50–345m/min, with workpieces mounted horizontally and at 45°. Despite slight variation in ancillary finishing parameters there was generally good agreement between data sets for the different evaluation techniques employed and for both alloys. Higher temperatures were measured with the workpiece at 45°, with constantan-workpiece thermocouple temperatures of 375°C and 413°C for new and worn tools respectively at 345m/min

Epistemic and social scripts in computer-supported collaborative learning

Collaborative learning in computer-supported learning environments typically means that learners work on tasks together, discussing their individual perspectives via text-based media or videoconferencing, and consequently acquire knowledge. Collaborative learning, however, is often sub-optimal with respect to how learners work on the concepts that are supposed to be learned and how learners interact with each other. One possibility to improve collaborative learning environments is to conceptualize epistemic scripts, which specify how learners work on a given task, and social scripts, which structure how learners interact with each other. In this contribution, two studies will be reported that investigated the effects of epistemic and social scripts in a text-based computer-supported learning environment and in a videoconferencing learning environment in order to foster the individual acquisition of knowledge. In each study the factors ‘epistemic script’ and ‘social script’ have been independently varied in a 2×2-factorial design. 182 university students of Educational Science participated in these two studies. Results of both studies show that social scripts can be substantially beneficial with respect to the individual acquisition of knowledge, whereas epistemic scripts apparently do not to lead to the expected effects

Comparison of K+K^+ and e−e^- Quasielastic Scattering

We formulate $K^+$-nucleus quasielastic scattering in a manner which closely parallels standard treatments of $e^-$-nucleus quasielastic scattering. For $K^+$ scattering, new responses involving scalar contributions appear in addition to the Coulomb (or longitudinal) and transverse $(e,e')$ responses which are of vector character. We compute these responses using both nuclear matter and finite nucleus versions of the Relativistic Hartree Approximation to Quantum Hadrodynamics including RPA correlations. Overall agreement with measured $(e,e')$ responses and new $K^+$ quasielastic scattering data for $^{40}$Ca at |\qs|=500 MeV/c is good. Strong RPA quenching is essential for agreement with the Coulomb response. This quenching is notably less for the $K^+$ cross section even though the new scalar contributions are even more strongly quenched than the vector contributions. We show that this ``differential quenching'' alters sensitive cancellations in the expression for the $K^+$ cross section so that it is reduced much less than the individual responses. We emphasize the role of the purely relativistic distinction between vector and scalar contributions in obtaining an accurate and consistent description of the $(e,e')$ and $K^+$ data within the framework of our nuclear structure model.Comment: 26 pages, 5 uuencoded figures appended to end of this fil

A combined first and second order variational approach for image reconstruction

In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler's elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images -- a known disadvantage of the ROF model -- while being simple and efficiently numerically solvable.Comment: 34 pages, 89 figure

An oncogenic role for sphingosine kinase 2

While both human sphingosine kinases (SK1 and SK2) catalyze the generation of the pleiotropic signaling lipid sphingosine 1-phosphate, these enzymes appear to be functionally distinct. SK1 has well described roles in promoting cell survival, proliferation and neoplastic transformation. The roles of SK2, and its contribution to cancer, however, are much less clear. Some studies have suggested an antiproliferative/ pro-apoptotic function for SK2, while others indicate it has a prosurvival role and its inhibition can have anti-cancer effects. Our analysis of gene expression data revealed that SK2 is upregulated in many human cancers, but only to a small extent (up to 2.5-fold over normal tissue). Based on these findings, we examined the effect of different levels of cellular SK2 and showed that high-level overexpression reduced cell proliferation and survival, and increased cellular ceramide levels. In contrast, however, low-level SK2 overexpression promoted cell survival and proliferation, and induced neoplastic transformation in vivo. These findings coincided with decreased nuclear localization and increased plasma membrane localization of SK2, as well as increases in extracellular S1P formation. Hence, we have shown for the first time that SK2 can have a direct role in promoting oncogenesis, supporting the use of SK2-specific inhibitors as anti-cancer agents.Heidi A. Neubauer, Duyen H. Pham, Julia R. Zebol, Paul A.B. Moretti, Amanda L. Peterson, Tamara M. Leclercq, Huasheng Chan, Jason A. Powell, Melissa R. Pitman, Michael S. Samuel, Claudine S. Bonder, Darren J. Creek, Briony L. Gliddon and Stuart M. Pitso

Extracellular nanomatrix-induced self-organization of neural stem cells into miniature substantia nigra-like structures with therapeutic effects on Parkinsonian rats

Substantia nigra (SN) is a complex and critical region of the brain wherein Parkinson's disease (PD) arises from the degeneration of dopaminergic neurons. Miniature SN‐like structures (mini‐SNLSs) constructed from novel combination of nanomaterials and cell technologies exhibit promise as potentially curative cell therapies for PD. In this work, a rapid self‐organization of mini‐SNLS, with an organizational structure and neuronal identities similar to those of the SN in vivo, is achieved by differentiating neural stem cells in vitro on biocompatible silica nanozigzags (NZs) sculptured by glancing angle deposition, without traditional chemical growth factors. The differentiated neurons exhibit electrophysiological activity in vitro. Diverse physical cues and signaling pathways that are determined by the nanomatrices and lead to the self‐organization of the mini‐SNLSs are clarified and elucidated. In vivo, transplantation of the neurons from a mini‐SNLS results in an early and progressive amelioration of PD in rats. The sculptured medical device reported here enables the rapid and specific self‐organization of region‐specific and functional brain‐like structures without an undesirable prognosis. This development provides promising and significant insights into the screening of potentially curative drugs and cell therapies for PD

The language of malaria in Abui: An interdisciplinary investigation of healthcare practices in Alor, Eastern Indonesia

We report on an interdisciplinary collaboration between public health experts, linguists, and botanists which seeks to better understand indigenous perspectives on malaria among the Abui [abz] speaking communities of Alor Island, Eastern Indonesia. Malaria is endemic in Alor and is highly resistant to common conventional treatment regimens (Sutanto et al. 2009). There is a low rate of compliance with modern malaria treatments, and a correspondingly high reliance on traditional treatment methods (Krentel 2008). Our research attempts to understand traditional knowledge of malaria in Abui and its relevance to modern healthcare. We analyze a corpus of unstructured interviews concerning health-related problems in Abui in order to better understand the conceptualization of disease (Forster 1976). This includes the systematic study of metaphor (Author 2016), sequencing of symptom descriptions (Author 2016), symptom-based indigenous classification of malaria, an inventory of traditional health-protecting practices, and an inventory of medical plants. The plant terminology reveals a syncretism between terms referring to diseases and the plants which either treat or cause those diseases. For example, the term takaya denotes both the ti plant (Cordyline fruticosa) and a severe form of malaria (Plasmodium falciparum). The leaves of the ti plant takaya are tied onto valuable trees such as candlenut, areca palm, and jackfruit to create a protective spell which wards off theft of the fruits or nuts of that tree. Transgressing this protection by taking the fruits or nuts without permission will cause the transgressor to suffer the takaya disease. The existence of supernatural causes may go unnoticed when interviews are conducted in Indonesian, the national language closely associated with modernity. However, the pervasiveness of plant-disease syncretism within Abui belies the continuing significance of traditional beliefs regarding disease. The collaborative methodology described here shows great promise for improving our understanding of the conceptualization of malaria in Abui and thus increasing treatment efficacy for this disease. Moreover, this approach provides a platform for documentary linguistics which includes a high level of community engagement. The healthcare interviews yield a culturally significant corpus of spontaneous speech which also serves as an independent knowledge base to evaluate the reliability and accuracy of ethnobotanical research. Finally, we suggest several ways in which our approach can be applied to future healthcare research in other domains and with other communities. References Author. 2016. The Pragmatics Behind the Medical and Health Knowledge in Alor: An Understanding of how disease is conceptualized in the Abui language. Honors thesis. Nanyang Technological University, Singapore. Du Bois, Cora. 1944. The People of Alor: a social-psychological study of an East Indian island. Minnesota: The University of Minnesota Press Forster, George M. 1976. Disease Etiologies in Non-Western Medical Systems. American Anthropologist 78(4): 773-782. Krentel, Alison. 2008. Why do individuals comply with mass drug administration for lymphatic filariasis? A case study from Alor District, Indonesia. PhD dissertation. London School of Hygiene & Tropical Medicine. Sutanto, I. Nurhayati, S. S., Manoempil, P., Baird, J.K. 2009. Resistance to Choloroquine by Plasmodium vivax at Alor in the Lesser Sundas Archipelago in Eastern Indonesia. The American Society of Tropical Medicine and Hygiene, 81(2), 338-342. Author. 2016. The Semantics of Complex Sentences in the Discourse of Health and Diseases: A Case Study in Abui. Honors thesis. Nanyang Technological University, Singapore

Ground-state properties of tubelike flexible polymers

In this work we investigate structural properties of native states of a simple model for short flexible homopolymers, where the steric influence of monomeric side chains is effectively introduced by a thickness constraint. This geometric constraint is implemented through the concept of the global radius of curvature and affects the conformational topology of ground-state structures. A systematic analysis allows for a thickness-dependent classification of the dominant ground-state topologies. It turns out that helical structures, strands, rings, and coils are natural, intrinsic geometries of such tubelike objects