979 resultados para Geometry, Non-euclidean
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Purpose To examine choroidal thickness (ChT) and its topographical variation across the posterior pole in myopic and non-myopic children. Methods One hundred and four children aged 10-15 years of age (mean age 13.1 ± 1.4 years) had ChT measured using enhanced depth imaging optical coherence tomography (OCT). Forty one children were myopic (mean spherical equivalent -2.4 ± 1.5 D) and 63 non-myopic (mean +0.3 ± 0.3 D). Two series of 6 radial OCT line scans centred on the fovea were assessed for each child. Subfoveal ChT and ChT across a series of parafoveal zones over the central 6mm of the posterior pole were determined through manual image segmentation. Results Subfoveal ChT was significantly thinner in myopes (mean 303 ± 79 µm) compared to non-myopes (mean 359 ± 77 µm) (p<0.0001). Multiple regression analysis revealed both refractive error (r = 0.39, p<0.001) and age (r = 0.21, p = 0.02) were positively associated with subfoveal ChT. ChT also exhibited significant topographical variations, with the choroid being thicker in more central regions. The thinnest choroid was typically observed in nasal (mean 286 ± 77 µm) and inferior-nasal (306 ± 79 µm) locations, and the thickest in superior (346 ± 79 µm) and superior-temporal (341 ± 74 µm) locations. The difference in ChT between myopic and non-myopic children was significantly greater in central foveal regions compared to more peripheral regions (>3 mm diameter) (p<0.001). Conclusions Myopic children have significantly thinner choroids compared to non-myopic children of similar age, particularly in central foveal regions. The magnitude of difference in choroidal thickness associated with myopia appears greater than would be predicted by a simple passive choroidal thinning with axial elongation.
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The molecular mechanisms involved in non‑small cell lung cancer tumourigenesis are largely unknown; however, recent studies have suggested that long non-coding RNAs (lncRNAs) are likely to play a role. In this study, we used public databases to identify an mRNA-like, candidate long non-coding RNA, GHSROS (GHSR opposite strand), transcribed from the antisense strand of the ghrelin receptor gene, growth hormone secretagogue receptor (GHSR). Quantitative real-time RT-PCR revealed higher expression of GHSROS in lung cancer tissue compared to adjacent, non-tumour lung tissue. In common with many long non-coding RNAs, GHSROS is 5' capped and 3' polyadenylated (mRNA-like), lacks an extensive open reading frame and harbours a transposable element. Engineered overexpression of GHSROS stimulated cell migration in the A549 and NCI-H1299 non-small cell lung cancer cell lines, but suppressed cell migration in the Beas-2B normal lung-derived bronchoepithelial cell line. This suggests that GHSROS function may be dependent on the oncogenic context. The identification of GHSROS, which is expressed in lung cancer and stimulates cell migration in lung cancer cell lines, contributes to the growing number of non-coding RNAs that play a role in the regulation of tumourigenesis and metastatic cancer progression.
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Background The majority of patients who attend emergency departments (EDs) in Saudi Arabia have non-urgent problems, resulting in overcrowding, excessive waiting times and delayed care for more acutely ill patients. The purpose of this research was to examine the reasons for non-urgent visits to a Saudi ED and factors associated with patient perceptions of urgency. Methods We administered a survey to 350 consecutively presenting Canadian Triage and Acuity Scale (CTAS) IV or V adult patients at a large tertiary ED in Riyadh region, Saudi Arabia, during 25 days of data collection in March 2013. Results Over half of the sample usually visited the ED to access healthcare. The most common reasons for attending the ED were not having a regular healthcare provider (63%), being able to receive care on the same day (62%), and the convenience of and access to medical care 24/7 (62%). Approximately two-thirds of CTAS V patients and one-third of CTAS IV patients believed their condition was more urgent than their triage nurse rating. Conclusion Multiple factors influence non-urgent visits to the ED in the Saudi context including insufficient community awareness of the role of the ED and perceived lack of access to primary healthcare services.
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This report provides the Queensland Department of Education and Training (DET) with independent evidence based data to enable the identification of barriers and enablers to effective attraction and retention of suitably qualified people to specialist teaching and non‐teaching roles in Queensland secondary schools. The scope of this report is to consider the strategic imperatives, trends, and drivers as they apply to the recruitment and retention of specialised teachers and non‐teaching professionals. The research was specifically designed to inform DET on innovative and novel strategies to recruit and retain staff within Education Queensland in areas specifically identified as at risk of experiencing shortages in the near future. Those areas considered to be at risk of experiencing shortages included: • Teaching principals • Specialist teachers in mathematics, science, industrial technology and design, and special education • Non‐teaching professional roles, such as speech pathologists, occupational therapists, physiotherapists and registered nurses providing services in schools to students with special needs.
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Objectives The goal of this article is to examine whether or not the results of the Queensland Community Engagement Trial (QCET)-a randomized controlled trial that tested the impact of procedural justice policing on citizen attitudes toward police-were affected by different types of nonresponse bias. Method We use two methods (Cochrane and Elffers methods) to explore nonresponse bias: First, we assess the impact of the low response rate by examining the effects of nonresponse group differences between the experimental and control conditions and pooled variance under different scenarios. Second, we assess the degree to which item response rates are influenced by the control and experimental conditions. Results Our analysis of the QCET data suggests that our substantive findings are not influenced by the low response rate in the trial. The results are robust even under extreme conditions, and statistical significance of the results would only be compromised in cases where the pooled variance was much larger for the nonresponse group and the difference between experimental and control conditions was greatly diminished. We also find that there were no biases in the item response rates across the experimental and control conditions. Conclusion RCTs that involve field survey responses-like QCET-are potentially compromised by low response rates and how item response rates might be influenced by the control or experimental conditions. Our results show that the QCET results were not sensitive to the overall low response rate across the experimental and control conditions and the item response rates were not significantly different across the experimental and control groups. Overall, our analysis suggests that the results of QCET are robust and any biases in the survey responses do not significantly influence the main experimental findings.
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The news media industry has changed dramatically into a global business with ever-increasing attention being devoted to entertainment and celebrity across the last 10–20 years. There has also been a growing reliance on images produced by citizens (citizen photojournalism), by media outlets and publishers. It is widely acknowledged that in tandem these changes have shrunk publication opportunities for professional photographers undertaking editorial projects. As a result, photographers are increasingly relying on non-government organisations (NGOs) to gain access to photographing issues and events in developing countries and to expand their economic and portfolio opportunities. This increase in photographers working for and alongside NGOs has given rise to a new genre of editorial photography which I call NGO Reportage. By way of a case study, an exploration of this new genre reveals important issues for photographers working with NGOs and examines the constructed narratives of images contained within these emerging practices.
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An encryption scheme is non-malleable if giving an encryption of a message to an adversary does not increase its chances of producing an encryption of a related message (under a given public key). Fischlin introduced a stronger notion, known as complete non-malleability, which requires attackers to have negligible advantage, even if they are allowed to transform the public key under which the related message is encrypted. Ventre and Visconti later proposed a comparison-based definition of this security notion, which is more in line with the well-studied definitions proposed by Bellare et al. The authors also provide additional feasibility results by proposing two constructions of completely non-malleable schemes, one in the common reference string model using non-interactive zero-knowledge proofs, and another using interactive encryption schemes. Therefore, the only previously known completely non-malleable (and non-interactive) scheme in the standard model, is quite inefficient as it relies on generic NIZK approach. They left the existence of efficient schemes in the common reference string model as an open problem. Recently, two efficient public-key encryption schemes have been proposed by Libert and Yung, and Barbosa and Farshim, both of them are based on pairing identity-based encryption. At ACISP 2011, Sepahi et al. proposed a method to achieve completely non-malleable encryption in the public-key setting using lattices but there is no security proof for the proposed scheme. In this paper we review the mentioned scheme and provide its security proof in the standard model. Our study shows that Sepahi’s scheme will remain secure even for post-quantum world since there are currently no known quantum algorithms for solving lattice problems that perform significantly better than the best known classical (i.e., non-quantum) algorithms.
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We study the natural problem of secure n-party computation (in the computationally unbounded attack model) of circuits over an arbitrary finite non-Abelian group (G,⋅), which we call G-circuits. Besides its intrinsic interest, this problem is also motivating by a completeness result of Barrington, stating that such protocols can be applied for general secure computation of arbitrary functions. For flexibility, we are interested in protocols which only require black-box access to the group G (i.e. the only computations performed by players in the protocol are a group operation, a group inverse, or sampling a uniformly random group element). Our investigations focus on the passive adversarial model, where up to t of the n participating parties are corrupted.
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Boolean functions and their Möbius transforms are involved in logical calculation, digital communications, coding theory and modern cryptography. So far, little is known about the relations of Boolean functions and their Möbius transforms. This work is composed of three parts. In the first part, we present relations between a Boolean function and its Möbius transform so as to convert the truth table/algebraic normal form (ANF) to the ANF/truth table of a function in different conditions. In the second part, we focus on the special case when a Boolean function is identical to its Möbius transform. We call such functions coincident. In the third part, we generalize the concept of coincident functions and indicate that any Boolean function has the coincidence property even it is not coincident.
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This study aimed to examine the use of hospital emergency departments and to investigate the level of satisfaction with the emergency department service among patients from a non-English-speaking background compared to those of patients from an English-speaking background in Queensland. The findings of this study might inform health professionals and policy planners to develop educational interventions and policies to ensure equitable use of emergency services among the populations.
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The purpose of this study was to contrast the role of parental and non-parental (sibling, other family and non-family) supervisors in the supervision of learner drivers in graduated driver licensing systems. The sample consisted of 522 supervisors from the Australian states of Queensland (n = 204, 39%) and New South Wales (n = 318, 61%). The learner licence requirements in these two states are similar, although learners in Queensland are required to accrue 100 h of supervision in a log book while those in New South Wales are required to accrue 120 h. Approximately 50 per cent of the sample (n = 255) were parents of the learner driver while the remainder of the sample were either siblings (n = 72, 13.8%), other family members (n = 153, 29.3%) or non-family (n = 114, 21.8%). Parents were more likely than siblings, other family or non-family members to be the primary supervisor of the learner driver. Siblings provided fewer hours of practice when compared with other supervisor types while the median and mode suggest that parents provided the most hours of practice to learner drivers. This study demonstrates that non-parental supervisors, such as siblings, other family members and non-family, at least in jurisdictions that require 100 or 120 h of practice, are important in facilitating learner drivers to accumulate sufficient supervised driving practice.
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Obtaining attribute values of non-chosen alternatives in a revealed preference context is challenging because non-chosen alternative attributes are unobserved by choosers, chooser perceptions of attribute values may not reflect reality, existing methods for imputing these values suffer from shortcomings, and obtaining non-chosen attribute values is resource intensive. This paper presents a unique Bayesian (multiple) Imputation Multinomial Logit model that imputes unobserved travel times and distances of non-chosen travel modes based on random draws from the conditional posterior distribution of missing values. The calibrated Bayesian (multiple) Imputation Multinomial Logit model imputes non-chosen time and distance values that convincingly replicate observed choice behavior. Although network skims were used for calibration, more realistic data such as supplemental geographically referenced surveys or stated preference data may be preferred. The model is ideally suited for imputing variation in intrazonal non-chosen mode attributes and for assessing the marginal impacts of travel policies, programs, or prices within traffic analysis zones.
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The profession of law is deeply steeped in tradition and conservatism, which influences the content and pedagogy employed in law faculties across Australia. Indeed, the practice of law and the institutions of legal education are in a relationship of mutual influence; a dénouement which preserves the best aspects of the common law legal system, but also leaves the way we educate, practice and think about the role of law resistant to change. In this article, the authors lay down a challenge to legal education orthodoxy and a call to arms for legal academic progressivists: that alternative dispute resolution (ADR) should be a compulsory, stand alone subject in the law degree. The authors put forward 10 simple arguments as to why every law student should be exposed to a semester-long course of ADR instruction.
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Some initial EUVL patterning results for polycarbonate based non-chemically amplified resists are presented. Without full optimization the developer a resolution of 60 nm line spaces could be obtained. With slight overexposure (1.4 × E0) 43.5 nm lines at a half pitch of 50 nm could be printed. At 2x E0 a 28.6 nm lines at a half pitch of 50 nm could be obtained with a LER that was just above expected for mask roughness. Upon being irradiated with EUV photons, these polymers undergo chain scission with the loss of carbon dioxide and carbon monoxide. The remaining photoproducts appear to be non-volatile under standard EUV irradiation conditions, but do exhibit increased solubility in developer compared to the unirradiated polymer. The sensitivity of the polymers to EUV light is related to their oxygen content and ways to increase the sensitivity of the polymers to 10 mJ cm-2 is discussed.