66 resultados para 391
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It is well known that, although a uniform magnetic field inhibits the onset of small amplitude thermal convection in a layer of fluid heated from below, isolated convection cells may persist if the fluid motion within them is sufficiently vigorous to expel magnetic flux. Such fully nonlinear(‘‘convecton’’) solutions for magnetoconvection have been investigated by several authors. Here we explore a model amplitude equation describing this separation of a fluid layer into a vigorously convecting part and a magnetically-dominated part at rest. Our analysis elucidates the origin of the scaling laws observed numerically to form the boundaries in parameter space of the region of existence of these localised states, and importantly, for the lowest thermal forcing required to sustain them.
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The introduction of Building Information Modelling (BIM) to the design, construction and operation of buildings is changing the way that the building construction industry works. BIM involves the development of a full 3D virtual model of a building which not only contains the 3D information necessary to show the building as it will appear, but also contains significant additional data about each component in the building. BIM represents both physical and virtual objects in a building. This includes the rooms and spaces within and around the building. The additional data stored on each part of the building can support building maintenance opera- tions and, more importantly from the perspective of this paper, support the generation and running of simula- tions of the operation of the building and behaviour of people within it under both normal and emergency scenarios. The initial discussion is around the use of BIM to support the design of resilient buildings which references the various codes and standards that define current best practice. The remainder of the discussion uses various recent events as the basis for discussion on how BIM could have been used to support rapid recovery and re- building.
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This article responds to the invitation extended by Carney to engage in a dialogue on the topic of graduate legal research units. In his paper, Carney stated the approach of the Sydney course as being to teach theory rather than skills, to "pursue academic goals over skill competencies... ". The Faculty of Law at Queensland University of Technology introduced a postgraduate legal research unit in 1993 with different perspectives and purposes to the Sydney course, and given this experience, the opportunity for a discussion on aspects of such units including the theoretical versus practical approach to teaching cannot be ignored.
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This article reports on the organisation and main events of the 15th World Congress of the World Council of Comparative Education Societies (WCCES), held in Buenos Aires, Argentina, in 2013.
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Background Child sexual abuse is considered a modifiable risk factor for mental disorders across the life course. However the long-term consequences of other forms of child maltreatment have not yet been systematically examined. The aim of this study was to summarise the evidence relating to the possible relationship between child physical abuse, emotional abuse, and neglect, and subsequent mental and physical health outcomes. Methods and Findings A systematic review was conducted using the Medline, EMBASE, and PsycINFO electronic databases up to 26 June 2012. Published cohort, cross-sectional, and case-control studies that examined non-sexual child maltreatment as a risk factor for loss of health were included. All meta-analyses were based on quality-effects models. Out of 285 articles assessed for eligibility, 124 studies satisfied the pre-determined inclusion criteria for meta-analysis. Statistically significant associations were observed between physical abuse, emotional abuse, and neglect and depressive disorders (physical abuse [odds ratio (OR) = 1.54; 95% CI 1.16–2.04], emotional abuse [OR = 3.06; 95% CI 2.43–3.85], and neglect [OR = 2.11; 95% CI 1.61–2.77]); drug use (physical abuse [OR = 1.92; 95% CI 1.67–2.20], emotional abuse [OR = 1.41; 95% CI 1.11–1.79], and neglect [OR = 1.36; 95% CI 1.21–1.54]); suicide attempts (physical abuse [OR = 3.40; 95% CI 2.17–5.32], emotional abuse [OR = 3.37; 95% CI 2.44–4.67], and neglect [OR = 1.95; 95% CI 1.13–3.37]); and sexually transmitted infections and risky sexual behaviour (physical abuse [OR = 1.78; 95% CI 1.50–2.10], emotional abuse [OR = 1.75; 95% CI 1.49–2.04], and neglect [OR = 1.57; 95% CI 1.39–1.78]). Evidence for causality was assessed using Bradford Hill criteria. While suggestive evidence exists for a relationship between maltreatment and chronic diseases and lifestyle risk factors, more research is required to confirm these relationships. Conclusions This overview of the evidence suggests a causal relationship between non-sexual child maltreatment and a range of mental disorders, drug use, suicide attempts, sexually transmitted infections, and risky sexual behaviour. All forms of child maltreatment should be considered important risks to health with a sizeable impact on major contributors to the burden of disease in all parts of the world. The awareness of the serious long-term consequences of child maltreatment should encourage better identification of those at risk and the development of effective interventions to protect children from violence.
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Researchers have postulated that reduced hip-abductor muscle strength may have a role in the progression of knee osteoarthritis by increasing the external knee-adduction moment. However, the relationship between hip-abductor strength and frontal-plane biomechanics remains unclear. To experimentally reduce hip-abduction strength and observe the subsequent changes in frontal-plane biomechanics. Descriptive laboratory study. Research laboratory. Eight healthy, recreationally active men (age = 27 ± 6 years, height = 1.75 ± 0.11 m, mass = 76.1 ± 10.0 kg). All participants underwent a superior gluteal nerve block injection to reduce the force output of the hip-abductor muscle group. Maximal isometric hip-abduction strength and gait biomechanical data were collected before and after the injections. Gait biomechanical variables collected during walking consisted of knee- and hip-adduction moments and impulses and the peak angles of contralateral pelvic drop, hip adduction, and ipsilateral trunk lean. Hip-abduction strength was reduced after the injection (P = .001) and remained lower than baseline values at the completion of the postinjection gait data collection (P = .02). No alterations in hip- or knee-adduction moments (hip: P = .11; knee: P = .52) or impulses (hip: P = .16; knee: P = .41) were found after the nerve block. Similarly, no changes in angular kinematics were observed for contralateral pelvic drop (P = .53), ipsilateral trunk lean (P = .78), or hip adduction (P = .48). A short-term reduction in hip-abductor strength was not associated with alterations in the frontal-plane gait biomechanics of young, healthy men. Further research is needed to determine whether a similar relationship is true in older adults with knee osteoarthritis.
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Background The use of the internet to access information is rapidly increasing; however, the quality of health information provided on various online sites is questionable. We aimed to examine the underlying factors that guide parents' decisions to use online information to manage their child's health care, a behaviour which has not yet been explored systematically. Methods Parents (N=391) completed a questionnaire assessing the standard theory of planned behaviour (TPB) measures of attitude, subjective norm, perceived behavioural control (PBC), and intention as well as the underlying TPB belief-based items (i.e., behavioural, normative, and control beliefs) in addition to a measure of perceived risk and demographic variables. Two months later, consenting parents completed a follow-up telephone questionnaire which assessed the decisions they had made regarding their use of online information to manage their child's health care during the previous 2 months. Results We found support for the TPB constructs of attitude, subjective norm, and PBC as well as the additional construct of perceived risk in predicting parents' intentions to use online information to manage their child's health care, with further support found for intentions, but not PBC, in predicting parents' behaviour. The results of the TPB belief-based analyses also revealed important information about the critical beliefs that guide parents' decisions to engage in this child health management behaviour. Conclusions This theory-based investigation to understand parents' motivations and online information-seeking behaviour is key to developing recommendations and policies to guide more appropriate help-seeking actions among parents.
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"It could easily provide the back-drop for a James Bond movie. Deep inside a mountain near the North Pole, down a fortified tunnel, and behind airlocked doors in a vault frozen to -18 degrees Celsius, scientists are squirreling away millions of seed samples. The samples constitute the very foundation of agriculture, the biological diversity needed so the world's major food crops can adapt to the next pest or disease, or to climate change. It's little wonder that the Svalbard Global Seed Vault has captured the public's imagination more than almost any agricultural topic in recent years. Popular press reports about the ‘Doomsday Vault,’ however, typically mask the complexity of the endeavor and, if anything, underestimate its practical utility." Cary Fowler This chapter considers the use of seed banks to address concerns about intellectual property, climate change and food security. It has a number of themes. First of all, it is interested in the use of ‘Big Science’ projects to address pressing global scientific concerns and Millennium Development Goals. Second, it highlights the increasing use of banks as a means of managing both property and intellectual property across a wide range of fields of agriculture and biotechnology. Third, it considers the linkage of intellectual property, access to genetic resources and benefit sharing. There are a variety of positions in this debate. Some see requirements in respect of access to genetic resources and benefit sharing as an inconvenient burden for science and commerce. Others defend access to genetic resources and benefit sharing as meaningful and productive. Those inclined to somewhat more conspiratorial views suggest that access to genetic resources and benefit sharing are a ruse to facilitate biopiracy. This chapter has a number of components. Section I focuses upon the Consultative Group on International Agricultural Research (CGIAR) network – often raised as a model for Climate Innovation Centres. Section II considers the Svalbard Global Seed Vault – the so-called Doomsday Vault. After a consideration of the World Summit on Food Security in 2009, it is concluded in this chapter that any future international agreement on climate change needs to address intellectual property, plant genetic resources and food security.
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The NTRK1 gene (also known as TRKA) encodes a high-affinity receptor for NGF, a neurotrophin involved in nervous system development and myelination. NTRK1 has been implicated in neurological function via links between the T allele at rs6336 (NTRK1-T) and schizophrenia risk. A variant in the neurotrophin gene, BDNF, was previously associated with white matter integrity in young adults, highlighting the importantce of neurotrophins to white matter development. We hypothesized that NTRK1-T would relate to lower fractional anisotropy in healthy adults. We scanned 391 healthy adult human twins and their siblings (mean age: 23.6 ± 2.2 years; 31 NTRK1-T carriers, 360 non-carriers) using 105-gradient diffusion tensor imaging at 4 tesla. We evaluated in brain white matter how NTRK1-T and NTRK1 rs4661063 allele A (rs4661063-A, which is in moderate linkage disequilibrium with rs6336) related to voxelwise fractional anisotropy-acommondiffusion tensor imaging measure of white matter microstructure. We used mixed-model regression to control for family relatedness, age, and sex. The sample was split in half to test reproducibility of results. The false discovery rate method corrected for voxelwise multiple comparisons. NTRK1-T and rs4661063-A correlated with lower white matter fractional anisotropy, independent of age and sex (multiple-comparisons corrected: false discovery rate critical p=0.038 forNTRK1-Tand0.013 for rs4661063-A). In each half-sample, theNTRK1-T effectwasreplicated in the cingulum, corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, superior corona radiata, and uncinate fasciculus. Our results suggest that NTRK1-T is important for developing white matter microstructure.
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A computed tomography number to relative electron density (CT-RED) calibration is performed when commissioning a radiotherapy CT scanner by imaging a calibration phantom with inserts of specified RED and recording the CT number displayed. In this work, CT-RED calibrations were generated using several commercially available phantoms to observe the effect of phantom geometry on conversion to electron density and, ultimately, the dose calculation in a treatment planning system. Using an anthropomorphic phantom as a gold standard, the CT number of a material was found to depend strongly on the amount and type of scattering material surrounding the volume of interest, with the largest variation observed for the highest density material tested, cortical bone. Cortical bone gave a maximum CT number difference of 1,110 when a cylindrical insert of diameter 28 mm scanned free in air was compared to that in the form of a 30 × 30 cm2 slab. The effect of using each CT-RED calibration on planned dose to a patient was quantified using a commercially available treatment planning system. When all calibrations were compared to the anthropomorphic calibration, the largest percentage dose difference was 4.2 % which occurred when the CT-RED calibration curve was acquired with heterogeneity inserts removed from the phantom and scanned free in air. The maximum dose difference observed between two dedicated CT-RED phantoms was ±2.1 %. A phantom that is to be used for CT-RED calibrations must have sufficient water equivalent scattering material surrounding the heterogeneous objects that are to be used for calibration.
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This study examines and quantifies the effect of adding polyelectrolytes to cellulose nanofibre suspensions on the gel point of cellulose nanofibre suspensions, which is the lowest solids concentration at which the suspension forms a continuous network. The lower the gel point, the faster the drainage time to produce a sheet and the higher the porosity of the final sheet formed. Two new techniques were designed to measure the dynamic compressibility and the drainability of nanocellulose–polyelectrolyte suspensions. We developed a master curve which showed that the independent variable controlling the behaviour of nanocellulose suspensions and its composite is the structure of the flocculated suspension which is best quantified as the gel point. This was independent of the type of polyelectrolyte used. At an addition level of 2 mg/g of nanofibre, a reduction in gel point over 50 % was achieved using either a high molecular weight (13 MDa) linear cationic polyacrylamide (CPAM, 40 % charge), a dendrimer polyethylenimine of high molecular weight of 750,000 Da (HPEI) or even a low molecular weight of 2000 Da (LPEI). There was no significant difference in the minimum gel point achieved, despite the difference in polyelectrolyte morphology and molecular weight. In this paper, we show that the gel point controls the flow through the fibre suspension, even when comparing fibre suspensions with solids content above the gel point. A lower gel point makes it easier for water to drain through the fibre network,reducing the pressure required to achieve a given dewatering rate and reducing the filtering time required to form a wet laid sheet. We further show that the lower gel point partially controls the structure of the wet laid sheet after it is dried. Halving the gel point increased the air permeability of the dry sheet by 37, 46 and 25 %, when using CPAM, HPEI and LPEI, respectively. The resistance to liquid flow was reduced by 74 and 90 %, when using CPAM and LPEI. Analysing the paper formed shows that sheet forming process and final sheet properties can be engineered and controlled by adding polyelectrolytes to the nanofibre suspension.
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Percutaneous coronary interventions have increased 50% in Australia, yet vascular and cardiac complications remain ongoing outcome issues for patients. Managing complications is confounded by reduced length of patient stay, yet is an integral component of a cardiac nurses’ scope of practice. The aim of this study was to highlight in and out of hospital vascular and cardiac complications, for twelve months post patient discharge after PCI. Prospective data was collected from the hospital angioplasty database from 1089 consecutive patients who had PCI procedures from 1 January 2005 to 31 December 2006. In hospital vascular complications were reported by 391 (35%) of the 1089 patients, following PCI. Of these, 22.4% had haemorrhage only, 7.1% haematoma only. Cardiac complications in hospital were, one death (0.09%) following PCI, three deaths (0.27%) during the same admission and no incidence of myocardial infarction or bypass surgery. Patients who had PCI in 2005 (525) were telephone followed up after discharge at one and twelve months. Surprisingly, ongoing vascular outcomes were noted, with a 2.5% incidence at one month and 4% at 12 months. Cardiac complications were also identified, 51 (9.7%) patients requiring readmission for repeat angiogram, 19 (3.6%) a repeat PCI and 7 (1.3%) patients undergoing bypass surgery. This review highlights that vascular and cardiac problems are ongoing issues for PCI patients both in and out of hospital. The results suggest that cardiac nurses focus more on improving the monitoring and discharge care of patients and families for recovery after PCI.