194 resultados para 87-582B
Resumo:
The mineral schlossmacherite (H3O,Ca)Al3(AsO4,PO4,SO4)2(OH)6 , a multi-cation-multi-anion mineral of the beudantite mineral subgroup has been characterised by Raman spectroscopy. The mineral and related minerals functions as a heavy metal collector and is often amorphous or poorly crystalline, such that XRD identification is difficult. The Raman spectra are dominated by an intense band at 864 cm-1, assigned to the symmetric stretching mode of the AsO43- anion. Raman bands at 809 and 819 cm-1 are assigned to the antisymmetric stretching mode of AsO43- . The sulphate anion is characterised by bands at 1000 cm-1 (ν1), and at 1031, 1082 and 1139 cm-1 (ν3). Two sets of bands in the OH stretching region are observed: firstly between 2800 and 3000 cm-1 with bands observed at 2850, 2868, 2918 cm-1 and secondly between 3300 and 3600 with bands observed at 3363, 3382, 3410, 3449 and 3537 cm-1. These bands enabled the calculation of hydrogen bond distances and show a wide range of H-bond distances.
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Shattuckite Cu5(SiO3)4(OH)2 is a copper hydroxy silicate and is commonly known as a ‘healing’ mineral. Three shattuckite mineral samples from three different origins were analysed by Raman spectroscopy. Some Raman bands are common in the spectra of the minerals. Raman bands at around 890, 1058 and 1102 are described as the ν3 –SiO3 antisymmetric stretching vibrations. The Raman band at 670 cm-1 is assigned to the ν4 bending modes of the -SiO3 units and the band at around 785 cm-1is due to Si-O-Si chain stretching mode. Raman (and infrared) spectroscopy proves that water is in the molecular structure of shattuckite; thus the formula is better written as Cu5(SiO3)4(OH)2•xH2O.
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Rats are superior to the most advanced robots when it comes to creating and exploiting spatial representations. A wild rat can have a foraging range of hundreds of meters, possibly kilometers, and yet the rodent can unerringly return to its home after each foraging mission, and return to profitable foraging locations at a later date (Davis, et al., 1948). The rat runs through undergrowth and pipes with few distal landmarks, along paths where the visual, textural, and olfactory appearance constantly change (Hardy and Taylor, 1980; Recht, 1988). Despite these challenges the rat builds, maintains, and exploits internal representations of large areas of the real world throughout its two to three year lifetime. While algorithms exist that allow robots to build maps, the questions of how to maintain those maps and how to handle change in appearance over time remain open. The robotic approach to map building has been dominated by algorithms that optimise the geometry of the map based on measurements of distances to features. In a robotic approach, measurements of distance to features are taken with range-measuring devices such as laser range finders or ultrasound sensors, and in some cases estimates of depth from visual information. The features are incorporated into the map based on previous readings of other features in view and estimates of self-motion. The algorithms explicitly model the uncertainty in measurements of range and the measurement of self-motion, and use probability theory to find optimal solutions for the geometric configuration of the map features (Dissanayake, et al., 2001; Thrun and Leonard, 2008). Some of the results from the application of these algorithms have been impressive, ranging from three-dimensional maps of large urban strucutures (Thrun and Montemerlo, 2006) to natural environments (Montemerlo, et al., 2003).
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While the phrase “six degrees of separation” is widely used to characterize a variety of humanderived networks, in this study we show that in patent citation network, related patents are connected with an average distance of 6, whereas an average distance for a random pair of nodes in the graph is approximately 15. We use this information to improve the recall level in prior-art retrieval in the setting of blind relevance feedback without any textual knowledge.
Resumo:
Imagine that is you holding the glass, and the separate larger picture of the glass to the left, is how much wine is inside the glass you are holding. Now, first of all, no tricks, truthfully answer the following question...
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Context-based chemistry education aims to improve student interest and motivation in chemistry by connecting canonical chemistry concepts with real-world contexts. Implementation of context-based chemistry programmes began 20 years ago in an attempt to make the learning of chemistry meaningful for students. This paper reviews such programmes through empirical studies on six international courses, ChemCom (USA), Salters (UK), Industrial Science (Israel), Chemie im Kontext (Germany), Chemistry in Practice (The Netherlands) and PLON (The Netherlands). These studies are categorised through emergent characteristics of: relevance, interest/attitudes motivation and deeper understanding. These characteristics can be found to an extent in a number of other curricular initiatives, such as science-technology-society approaches and problem-based learning or project based science, the latter of which often incorporates an inquiry-based approach to science education. These initiatives in science education are also considered with a focus on the characteristics of these approaches that are emphasised in context-based education. While such curricular studies provide a starting point for discussing context-based approaches in chemistry, to advance our understanding of how students connect canonical science concepts with the real-world context, a new theoretical framework is required. A dialectical sociocultural framework originating in the work of Vygotsky is used as a referent for analysing the complex human interactions that occur in context-based classrooms, providing teachers with recent information about the pedagogical structures and resources that afford students the agency to learn.
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Childhood sun exposure has been associated with increased risk of developing melanoma later in life. Sunscreen, children.s preferred method of sun protection, has been shown to reduce skin cancer risk. However, the effectiveness of sunscreen is largely dependent on user compliance, such as the thickness of application. To reach the sun protection factor (SPF) sunscreen must be applied at a thickness of 2mg/cm2. It has been demonstrated that adults tend to apply less than half of the recommended 2mg/cm2. This was the first study to measure the thickness at which children apply sunscreen. We recruited 87 primary school aged children (n=87, median age 8.7, 5-12 years) from seven state schools within one Brisbane education district (32% consent rate). The children were supplied with sunscreen in three dispenser types (pump, squeeze and roll-on) and were asked to use these for one week each. We measured the weight of the sunscreen before and after use, and calculated the children.s body surface area (based on height and weight) and area to which sunscreen was applied (based on children.s self-reported body coverage of application). Combined these measurements resulted in an average thickness of sunscreen application, which was our main outcome measure. We asked parents to complete a self-administered questionnaire which captured information about potential explanatory variables. Children applied sunscreen at a median thickness of 0.48mg/cm2, significantly less than the recommended 2mg/cm2 (p<0.001). When using the roll-on dispenser (median 0.22mg/cm2), children applied significantly less sunscreen thickness, compared to the pump (median 0.75mg.cm2, p<0.001), and squeeze (median 0.57mg/cm2, p<0.001) dispensers. School grade (1-7) was significantly associated with thickness of application (p=0.032), with children in the youngest grades applying the most. Other variables that were significantly associated with the outcome variable included: number of siblings (p=0.001), household annual income (p<0.001), and the number of lifetime sunburns the child had experienced (p=0.007). This work is the first to measure children.s sunscreen application thickness and demonstrates that regardless of their age or the type of dispenser that they use, children do not apply enough sunscreen to reach the advertised SPF. It is envisaged that this study will assist in the formulation of recommendations for future research, practice and policy aimed at improving childhood sun protection to reduce skin cancer incidence in the future.
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Road dust contain potentially toxic pollutants originating from a range of anthropogenic sources common to urban land uses and soil inputs from surrounding areas. The research study analysed the mineralogy and morphology of dust samples from road surfaces from different land uses and background soil samples to characterise the relative source contributions to road dust. The road dust consist primarily of soil derived minerals (60%) with quartz averaging 40-50% and remainder being clay forming minerals of albite, microcline, chlorite and muscovite originating from surrounding soils. About 2% was organic matter primarily originating from plant matter. Potentially toxic pollutants represented about 30% of the build-up. These pollutants consist of brake and tire wear, combustion emissions and fly ash from asphalt. Heavy metals such as Zn, Cu, Pb, Ni, Cr and Cd primarily originate from vehicular traffic while Fe, Al and Mn primarily originate from surrounding soils. The research study confirmed the significant contribution of vehicular traffic to dust deposited on urban road surfaces.
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This paper addresses the permeability of the field of China media research, its openness to new ideas; it argues that we need to adopt a wide angle view on research opportunities. Expansion of China’s media during the past decade has opened up possibilities for broadening of the field. The discussion first identifies boundary tensions as the field responds to transdisciplinary knowledge; in the second part the paper addresses challenges faced by Chinese researchers or visiting scholars in ‘Western’ media environments. Finally the paper addresses what a wide angle perspective might include.
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This paper reports on a unique study of a large, random sample of business start-ups that were identified prior to the actual, commercial launch of the ventures. The purpose of this paper is two-fold. First, to present frequencies on the involvement of the Swedish population in the small business sector (particularly in start-ups of firms) and to compare these with estimates from Norway and the USA, which are based on studies using a similar research design. The authors also discuss the possible reasons for the differences that emerge between countries. Second, the characteristics of nascent entrepreneurs (i.e. individuals trying to start an independent business) are analysed and compared for sub-groups within the sample and with characteristics of business founders as they appear in theoretical accounts or retrospective empirical studies of surviving all firms. In order to get a representative sample from the working age population, respondents (n = 30,427) were randomly selected and interviewed by telephone. It was found that 2.0% of the Swedish population at the time of the interview were trying to start an independent business. Sweden had a significantly lower prevalence rate of nascent entrepreneurs compared to Norway and the USA. Nascent entrepreneurs were then compared to a control group of people not trying to start a business. The results confirmed findings from previous studies of business founders pointing to the importance of role models and the impression of self-employment obtained through these, employment status, age, education and experience. Marital status, the number of children in the household, and length of employment experience were unrelated to the probability of becoming a nascent entrepreneur. The gender of the respondent was the strongest distinguishing factor. Importantly, the results suggest that while one has a reasonably good understanding of the characteristics associated with men going into business for themselves, the type of variables investigated here have very limited ability to predict nascent entrepreneur status for women.
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Is the brain evolving and adapting to new technological environments such as that of Silicon Valley? This paper examines changes that are being observed and studied relating to a possible correlation between ‘excessive’ focus on technology and the emergence of diagnosable social, physical and mental health dysfunction. The author explores the possible role of university staff and student services in the duty of care toward students. Would it not be more ethical to provide education on healthy technology use and to provide evidence based therapy for those students who fall through the web? Currently students end up being excluded from their courses. Many suffer from social anxiety and depression and lack confidence and social skills to find or hold down a job. Currently many “hibernate” in their rooms for months or years frequently in a state of despair.
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Digital Disruption: Cinema Moves On-line helps to make sense of what has happened in the short but turbulent history of on-line moving image distribution. It provides a realistic assessment of both the genuine and the not-so-promising methods that have been experimented in response to the disruptions that moving from ‘analogue dollars’ to ‘digital cents’ have provoked in the film industry. Paying close attention to how the Majors have dealt – often unsuccessfully – with the challenges it poses, it also focuses closely on the innovations and practices that have taken place beyond the mainstream, showcasing important entrepreneurial innovations such as Mubi, Jaman, Withoutabox and IMDb. Written by leading academic commentators and experts close to the fluctuating fortunes of the industry, Digital Disruption: Cinema Moves On-line is an indispensable guide to the changes currently facing film and its audiences.
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Applying ice or other forms of topical cooling is a popular method of treating sports injuries. It is commonplace for athletes to return to competitive activity, shortly or immediately after the application of a cold treatment. In this article, we examine the effect of local tissue cooling on outcomes relating to functional performance and to discuss their relevance to the sporting environment. A computerized literature search, citation tracking and hand search was performed up to April, 2011. Eligible studies were trials involving healthy human participants, describing the effects of cooling on outcomes relating to functional performance. Two reviewers independently assessed the validity of included trials and calculated effect sizes. Thirty five trials met the inclusion criteria; all had a high risk of bias. The mean sample size was 19. Meta-analyses were not undertaken due to clinical heterogeneity. The majority of studies used cooling durations >20 minutes. Strength (peak torque/force) was reported by 25 studies with approximately 75% recording a decrease in strength immediately following cooling. There was evidence from six studies that cooling adversely affected speed, power and agility-based running tasks; two studies found this was negated with a short rewarming period. There was conflicting evidence on the effect of cooling on isolated muscular endurance. A small number of studies found that cooling decreased upper limb dexterity and accuracy. The current evidence base suggests that athletes will probably be at a performance disadvantage if they return to activity immediately after cooling. This is based on cooling for longer than 20 minutes, which may exceed the durations employed in some sporting environments. In addition, some of the reported changes were clinically small and may only be relevant in elite sport. Until better evidence is available, practitioners should use short cooling applications and/or undertake a progressive warm up prior to returning to play.
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In response to developments in international trade and an increased focus on international transfer-pricing issues, Canada’s minister of finance announced in the 1997 budget that the Department of Finance would undertake a review of the transfer-pricing provisions in the Income Tax Act. On September 11, 1997, the Department of Finance released draft transfer-pricing legislation and Revenue Canada released revised draft Information Circular 87-2R. The legislation was subsequently amended and included in Bill C-28, which received first reading on December 10, 1997. The new rules are intended to update Canada’s international transfer-pricing practices. In particular, they attempt to harmonize the standards in the Income Tax Act with the arm’s-length principle established in the OECD’s transfer pricing guidelines. The new rules also set out contemporaneous documentation requirements in respect of cross-border related-party transactions, facilitate administration of the law by Revenue Canada, and provide for a penalty where transfer prices do not comply with the arm’s-length principle. The Australian tax authorities have similarly reviewed and updated their transfer-pricing practices. Since 1992, the Australian commissioner of taxation has issued three rulings and seven draft rulings directly relating to international transfer pricing. These rulings outline the selection and application of transfer pricing methodologies, documentation requirements, and penalties for non-compliance. The Australian Taxation Office supports the use of advance pricing agreements (APAs) and has expanded its audit strategy by conducting transfer-pricing risk assessment reviews. This article presents a detailed review of Australia’s transfer-pricing policy and practices, which address essentially the same concerns as those at which the new Canadian rules are directed. This review provides a framework for comparison of the approaches adopted in the two jurisdictions. The author concludes that although these approaches differ in some respects, ultimately they produce a similar result. Both regimes set a clear standard to be met by multinational enterprises in establishing transfer prices. Both provide for audits and penalties in the event of noncompliance. And both offer the alternative of an APA as a means of avoiding transfer-pricing disputes with Australian and Canadian tax authorities.