Ultrasonic tomographic imaging of defects in industrial materials

Ultrasonic tomography has been fairly widely applied for imaging of inhomogeneities in isotropic materials, particularly in the medical field, however, little success has been made in its application to industrial materials. This is largely due to the complex nature of ultrasonic wave propagation in these anisotropic materials. The three dimensional characteristics of ultrasonic wave propagation in anisotropic materials have been thoroughly studied for single crystals and also studied recently for different composites [1,2,3]. Understanding these characteristics provides the theoretical background for developing appropriate ultrasonic tomographic imaging methods for industrial materials

Mathematical modeling of the metastatic process

Mathematical modeling in cancer has been growing in popularity and impact since its inception in 1932. The first theoretical mathematical modeling in cancer research was focused on understanding tumor growth laws and has grown to include the competition between healthy and normal tissue, carcinogenesis, therapy and metastasis. It is the latter topic, metastasis, on which we will focus this short review, specifically discussing various computational and mathematical models of different portions of the metastatic process, including: the emergence of the metastatic phenotype, the timing and size distribution of metastases, the factors that influence the dormancy of micrometastases and patterns of spread from a given primary tumor.Comment: 24 pages, 6 figures, Revie

Magnetic Levitation for Soft-Tethered Capsule Colonoscopy Actuated With a Single Permanent Magnet: A Dynamic Control Approach

The present letter investigates a novel control approach for magnetically driven soft-tethered capsules for colonoscopy—a potentially painless approach for colon inspection. The focus of this work is on a class of devices composed of a magnetic capsule endoscope actuated by a single external permanent magnet. Actuation is achieved by manipulating the external magnet with a serial manipulator, which in turn produces forces and torques on the internal magnetic capsule. We propose a control strategy which, counteracting gravity, achieves levitation of the capsule. This technique, based on a nonlinear backstepping approach, is able to limit contact with the colon walls, reducing friction, avoiding contact with internal folds, and facilitating the inspection of nonplanar cavities. The approach is validated on an experimental setup, which embodies a general scenario faced in colonoscopy. The experiments show that we can attain 19.5% of contact with the colon wall, compared to the almost 100% of previously proposed approaches. Moreover, we show that the control can be used to navigate the capsule through a more realistic environment—a colon phantom—with reasonable completion time

Enabling the future of colonoscopy with intelligent and autonomous magnetic manipulation

Early diagnosis of colorectal cancer substantially improves survival. However, over half of cases are diagnosed late due to the demand for colonoscopy—the ‘gold standard’ for screening—exceeding capacity. Colonoscopy is limited by the outdated design of conventional endoscopes, which are associated with high complexity of use, cost and pain. Magnetic endoscopes are a promising alternative and overcome the drawbacks of pain and cost, but they struggle to reach the translational stage as magnetic manipulation is complex and unintuitive. In this work, we use machine vision to develop intelligent and autonomous control of a magnetic endoscope, enabling non-expert users to effectively perform magnetic colonoscopy in vivo. We combine the use of robotics, computer vision and advanced control to offer an intuitive and effective endoscopic system. Moreover, we define the characteristics required to achieve autonomy in robotic endoscopy. The paradigm described here can be adopted in a variety of applications where navigation in unstructured environments is required, such as catheters, pancreatic endoscopy, bronchoscopy and gastroscopy. This work brings alternative endoscopic technologies closer to the translational stage, increasing the availability of early-stage cancer treatments

Phenotypic and genotypic monitoring of Schistosoma mansoni in Tanzanian schoolchildren five years into a preventative chemotherapy national control programme

We conducted combined in vitro PZQ efficacy testing with population genetic analyses of S. mansoni collected from children from two schools in 2010, five years after the introduction of a National Control Programme. Children at one school had received four annual PZQ treatments and the other school had received two mass treatments in total. We compared genetic differentiation, indices of genetic diversity, and estimated adult worm burden from parasites collected in 2010 with samples collected in 2005 (before the control programme began) and in 2006 (six months after the first PZQ treatment). Using 2010 larval samples, we also compared the genetic similarity of those with high and low in vitro sensitivity to PZQ

Auditory hallucinations and migraine of possible brainstem origin

10.1007/s10194-011-0355-zJournal of Headache and Pain125573-57

Language learning and integration of adult Bhutanese refugees : an ethnographic study

This study sought a holistic and in-depth investigation of English language learning and integration experiences of a group of adult Bhutanese refugees in Australia. The Bhutanese refugees have settled since 2007 as new residents of their host country after two decades of expatriate life in the refugee camps of Nepal. The impetus for this exploratory study stemmed from my personal experience as a cultural orientation trainer to such refugees and awareness of their expectations, attitudes, and dispositions related to learning and life trajectory. This study is interdisciplinary in its approach that takes account of the complex interplay of language learning and integration. Using an ethnographic methodology as an approach to investigation, this study sought to examine three social spaces of refugees: the family and ethnic community, the host society and the migrant English classroom. The attention was focussed on the resources and constraints the refugees encountered in each of the social spaces. Moreover, various social, contextual, cultural factors, and pre-migration influences embedded in these spaces were explored for their impact on learning and integration. This study was important mainly for three reasons. Through critical examination of the role of refugees’ family and ethnic community networks, it aimed to provide insights into to what extent the resources embedded in these networks can be significant to refugees and also contribute to the existing literature of social capital (Putnam, 2000). Drawing on the investigation of how cultural issues, pre-migration experiences and perceptions of teaching impact on classroom language learning, this study sought to offer insights into how the English language should be taught to the adult students from refugee backgrounds. Moreover, this study sought to extend the scope of the existing refugee integration literature by investigating the integration as a process of ongoing negotiation between ethnocultural retention and host society participation, and how various social, cultural, contextual factors, and pre-migration experiences influenced the way integration is structured in everyday practice. This study employed an ethnographic approach as a methodological framework, involving observations, interviews, and a reflective journal study as the main tools for data collection. The field work was carried out in a regional area of the State of Tasmania. The observations were conducted in the migrant English classrooms, in a multi-ethnic Australian church and in the refugee community; and then the retrospective interviews were carried out with the Bhutanese refugees, their teachers and other service providers. The data were analyzed using ethnographic macro and micro level analysis techniques (Duff, 2002). The findings generated from observation data were supported and triangulated, where possible, by the use of data derived from interviews. This study was informed mainly by the interpretive paradigm. Given how extensive and messy the literature on migrant language learning and integration is, this study utilized a wide range of relevant theories to analyze and interpret the findings derived from the ethnographic fieldwork. One important contribution of this study is the finding that the social capital derived from refugees’ family and ethnic community networks not only enables, but it also inhibits integration. This bonding social capital can function as a coping resource for refugees against the effects of culture shock, language shock, and racism, and can facilitate access to a range of instrumental support and information necessary for successful transition to the host society. However, this study also suggests that an extreme level of embeddedness within the cultural and social frames of ethnic space has the potential to jeopardize individual mobility, host society language learning and sustainable integration. This study shows that the cultural dispositions the adult refugee students bring to the classroom provide the primary basis for the way they approach their English learning, and thus influence their agency and identity as learners. The findings also suggest that the students are likely to engage in the desired learning tasks if their perceptions of teaching quality cohere with the actual teaching they are exposed to. Teachers are therefore suggested to adopt a hybridity of teaching approaches and methods in ways that bridge the gap between their own and their students’ perceptions and expectations. The implications drawn from the empirical results additionally suggest that if the aim of the migrant English program is to facilitate the integration of refugees into their multicultural society, then the pedagogy it embodied should incorporate a hybridity of simulation scenarios (native, non-native and coethnic), enabling them to critically examine the impact of different types of identity they portray and negotiate their identities according to social constraints. This study suggests that in order to understand refugee integration more fully, it is not sufficient to account only for the pre-determined set of objective measures (such as employment and educational outcomes) without considering the way in which integration is actualized in everyday experience. For refugees in this study, what it means to be integrated into the Australian society was complex, ambivalent and context dependent. It was an ongoing process of contestation and negotiation between different values, identities and practices embedded in ethnic and mainstream Australia community. Based on my empirical study, I suggest that the everyday practices of refugee integration resembles with Bhabha’s (1990) notion of “Third Space” and incorporates the hybridity of cultural identifications and experiences

Microbial soil respiration and its dependency on carbon inputs, soil temperature and moisture

This experiment was designed to study three determinant factors in decomposition patterns of soil organic matter (SOM): temperature, water and carbon (C) inputs. The study combined field measurements with soil lab incubations and ends with a modelling framework based on the results obtained. Soil respiration was periodically measured at an oak savanna woodland and a ponderosa pine plantation. Intact soils cores were collected at both ecosystems, including soils with most labile C burnt off, soils with some labile C gone and soils with fresh inputs of labile C. Two treatments, dry-field condition and field capacity, were applied to an incubation that lasted 111 days. Short-term temperature changes were applied to the soils periodically to quantify temperature responses. This was done to prevent confounding results associated with different pools of C that would result by exposing treatments chronically to different temperature regimes. This paper discusses the role of the above-defined environmental factors on the variability of soil C dynamics. At the seasonal scale, temperature and water were, respectively, the main limiting factors controlling soil CO2 efflux for the ponderosa pine and the oak savanna ecosystems. Spatial and seasonal variations in plant activity (root respiration and exudates production) exerted a strong influence over the seasonal and spatial variation of soil metabolic activity. Mean residence times of bulk SOM were significantly lower at the Nitrogen (N)-rich deciduous savanna than at the N-limited evergreen dominated pine ecosystem. At shorter time scales (daily), SOM decomposition was controlled primarily by temperature during wet periods and by the combined effect of water and temperature during dry periods. Secondary control was provided by the presence/absence of plant derived C inputs (exudation). Further analyses of SOM decomposition suggest that factors such as changes in the decomposer community, stress-induced changes in the metabolic activity of decomposers or SOM stabilization patterns remain unresolved, but should also be considered in future SOM decomposition studies. Observations and confounding factors associated with SOM decomposition patterns and its temperature sensitivity are summarized in the modeling framework

Experimental glomerulonephritis induced by hydrocarbon exposure: A systematic review

BACKGROUND: Much epidemiological evidence suggests that hydrocarbon exposure may induce glomerulonephritis and worsen its course in many patients. The mechanisms are unknown, however, no specific microscopic pattern has been identified, and it has also been argued that hydrocarbon exposure causes tubular damage mainly. Studying experimental animals may best answer these questions, and as no systematic review of glomerulonephritis produced experimentally by hydrocarbon exposure has been performed previously, I found it relevant to search for and analyse such studies. METHODS: Animal experiments having mimicked human glomerulonephritis by hydrocarbon exposure were sought on Medline and Toxnet RESULTS: Twenty-six experiments using thirteen different hydrocarbons were identified. Several human subtypes were observed including IgA nephritis, mesangial, proliferative and extracapillary glomerulonephritis, focal and focal-segmental sclerosis, minimal change nephropathy, anti-GBM and anti-TBM nephritis, and glomerulonephritis associated with peiarteritis nodosa. Glomerular proteinuria was seen in 10/12 experiments that included urine analyses, and renal failure in 5/8 experiments that included measurements of glomerular function. All experiments resulted in various degrees of tubular damage as well. In most studies, where the animals were examined at different times during or after the exposure, the renal microscopic and functional changes were seen immediately, whereas deposits of complement and immunoglobulins appeared late in the course, if at all. CONCLUSION: These experiments are in accord with epidemiological evidence that hydrocarbon exposure may cause glomerulonephritis and worsen renal function. Probable mechanisms include an induction of autologous antibodies and a disturbance of normal immunological functions. Also, tubular damage may increase postglomerular resistance, resulting in a glomerular deposition of macromolecules. In most models a causal role of glomerular immune complex formation was unlikely, but may rather have been a secondary phenomenon. As most glomerulonephritis subgroups were seen and as some of the hydrocarbons produced more than one subgroup, the microscopic findings in a patient cannot be used as a clue to the causation of his disease. By the same reason, the lack of a specific histological pattern in patients with glomerulonephritis assumed to have been caused by hydrocarbon exposure is not contradictive

One moment, please: can the speed and quality of political contact affect democratic health

Contact between politicians and their constituents is the cornerstone of democracies globally but an area of scholarship that remains relatively underdeveloped. Political contact can help convey authority, provide legitimacy and facilitate governance. This article goes beyond the assumption that representatives need to communicate more with the public and suggests, instead, that the quality of contact matters. Focusing on four processes by which citizens can contact their representatives (face-to-face, by letter, email or social media), we employ an experimental vignette methodology to test whether the character and timeliness of politicians’ responses to citizen communication affects two indicators of democratic health: (a) the latter’s satisfaction with political contact and (b) their likelihood to re-contact representatives. Our findings provide evidence that personalised communication and to a smaller extent, speed of response, can influence citizen satisfaction and their likelihood of re-engagement. This suggests politicians can improve these indicators of democratic health by adjusting the style of political contact and communication