18,591 research outputs found

    Comparison of the full potential and Euler formulations for computing transonic airfoil flows

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    A quantitative comparison between the Euler and full potential formulations with respect to speed and accuracy is presented. The robustness of the codes used is tested by a number of transonic airfoil cases. The computed results are from four transonic airfoil computer codes. The full potential codes use fully implicit iteration algorithms. The first Euler code uses a fully implicit ADI iteration scheme. The second Euler code uses an explicit Runge Kutta time stepping algorithm which is enhanced by a multigrid convergence acceleration scheme. Quantitative comparisons are made using various plots of lift coefficient versus the average mesh spacing along the airfoil. Besides yielding an asymptotic limit to the lift coefficient, these results also demonstrate the truncation error behavior of the various codes. Quantitative conclusions regarding the full potential and Euler formulations with respect to accuracy, speed, and robustness can be presented

    Insights into finding a mismatch through the structure of a mispaired DNA bound by a rhodium intercalator

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    We report the 1.1-Ă… resolution crystal structure of a bulky rhodium complex bound to two different DNA sites, mismatched and matched in the oligonucleotide 5'-(dCGGAAATTCCCG)2-3'. At the AC mismatch site, the structure reveals ligand insertion from the minor groove with ejection of both mismatched bases and elucidates how destabilized mispairs in DNA may be recognized. This unique binding mode contrasts with major groove intercalation, observed at a matched site, where doubling of the base pair rise accommodates stacking of the intercalator. Mass spectral analysis reveals different photocleavage products associated with the two binding modes in the crystal, with only products characteristic of mismatch binding in solution. This structure, illustrating two clearly distinct binding modes for a molecule with DNA, provides a rationale for the interrogation and detection of mismatches

    Forensic analysis of secure ephemeral messaging applications on Android platforms

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    Secure messaging applications have been used for the purposes of major crime, creating the need for forensic research into the area. This paper forensically analyses two secure messaging applications, Wickr and Telegram, to recover artefacts from and then to compare them to reveal the differences between the applications. The artefacts were created on Android platforms by using the secure features of the applications, such as ephemeral messaging, the channel function and encrypted conversations. The results of the experiments documented in this paper give insight into the organisation of the data structures by both Wickr and Telegram, as well as the exploration of mobile digital forensics techniques to recover artefacts removed by the ephemeral functions

    Electrical and magnetic properties of the complete solid solution series between SrRuO3 and LaRhO3: Filling t2g versus tilting

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    A complete solid solution series between the t2g^4 perovskite ferromagnet SrRuO3 and the diamagnetic t2g^6 perovskite LaRhO3 has been prepared. The evolution with composition x in (SrRuO3)(1-x)(LaRhO3)(x) of the crystal structure and electrical and magnetic properties has been studied and is reported here. As x increases, the octahedral tilt angle gradually increases, along with the pseudocubic lattice parameter and unit cell volume. Electrical resistivity measurements reveal a compositionally driven metal to insulator transition between x = 0.1 and 0.2. Ferromagnetic ordering gives over to glassy magnetism for x > 0.3 and no magnetic ordering is found above 2 K for x > 0.5. M_sat and Theta_CW decrease with increasing x and remain constant after x = 0.5. The magnetism appears poised between localized and itinerant behavior, and becomes more localized with increasing x as evidenced by the evolution of the Rhodes-Wohlfarth ratio. mu_eff per Ru is equal to the quenched spin-only S value across the entire solid solution. Comparisons with Sr(1-x)Ca(x)RuO3 reinforce the important role of structural distortions in determining magnetic ground state. It is suggested that electrical transport and magnetic properties are not strongly coupled in this system

    On being a consumer living with dementia, a socio-legal study of the contractual consequences

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    This research investigates the experiences encountered when persons living with dementia enter into contracts as consumers with businesses, and what consequences may result from such transactions for the person living with dementia and their families. In doing so, this research seeks to clarify what, if any, legal protections are afforded to persons living with dementia who are often still legally capable, but in practice experience difficulties in fully understanding complex consumer contracts with businesses. Relevant academic literature is reviewed in a scoping exercise to gain a clear picture of the concepts of capacity and financial decision-making in a contractual setting. The review demonstrates that for a person living with dementia, capacity to make financial decisions will deteriorate as the disease progresses. Whilst there is no single path to assessing financial capacity, recognising any reduction of financial capacity is seen as important in ensuring long-term financial security and independence for those living with dementia. The review also highlights a clear gap in literature relating to consumers living with dementia. A doctrinal review of relevant laws is undertaken, and includes analysis of contract law, capacity law, consumer rights, as well as human rights in the context of equality and non-discrimination laws. The thesis highlights the lack of cohesion between the various laws, resulting in some consumers living with dementia falling through the gaps and not being adequately protected when entering into contracts with businesses. In addition to the close examination of the law, new empirical data is sought through semi-structured interviews with a number of stakeholders, including persons living with dementia, their family members and carers, as well as charities that advise and work with people affected by dementia. Analysis of the results indicates multiple concerns relating to capacity, knowledge, and protective measures aimed at countering financial harm. In practice, as roles within families evolve, capacity is often ignored in favour of safety and security of the person living with dementia. Where capacity is considered, difficulties arise as to how and who should assess a person’s legal capacity to make decisions. The thesis highlights the difficulties of understanding and/or remembering the terms of the contract, which can lead to unintentional breaches of contract. Fear of stigma results in many consumers living with dementia deliberately refusing to disclose their condition, resulting in the business’s lack of knowledge of any issue. There is a sense of powerlessness in seeking to terminate consumer contracts outside of the (often onerous) terms of the contract, although pragmatic solutions were presented, such as withholding payments, pleading for understanding and questioning the risk to reputation of the business. Building on from these practical solutions, the thesis suggests a range of legal solutions, such as a review of doctrine and legislation, to improve the contractual position of consumers living with dementia

    Acute hypocalcemia and metabolic alkalosis in children on cation-exchange resin therapy

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    Background. Sodium polystyrene sulfonate (SPS) is a chelating agent used for the treatment of hyperkalemia. SPS has a wide range of exchange capacity requiring close monitoring of serum electrolytes. We observed two patients who developed acute hypocalcemia and increased metabolic alkalosis after initiating SPS therapy. We report these cases to draw attention to the potential risk of this medication in pediatric patients. Case Diagnosis/Treatment. Two children with chronic kidney disease on dialysis were started on SPS for hyperkalemia. Within a week after initiation of the medication, both patients developed hypocalcemia on routine labs without overt clinical manifestations. The hypocalcemia was rapidly corrected with oral supplementation and discontinuation of SPS. Conclusions. Severe hypocalcemia can develop after SPS therapy. The metabolic alkalosis in these patients associated with the hypocalcemia put them at increased risk for complications. Hence, careful attention must be paid to the state of calcium metabolism in all patients receiving SPS. Often calcium supplementation is required to maintain normal calcium levels

    Drone forensic analysis using open source tools

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    Carrying capabilities of drones and their easy accessibility to public have led to an increase in crimes committed using drones in recent years. For this reason, the need for forensic analysis of drones captured from the crime scenes and the devices used for these drones is also paramount. This paper presents the extraction and identification of important artefacts from the recorded flight data as well as the associated mobile devices using open source tools and some basic scripts developed to aid the analysis of two popular drone systems- the DJI Phantom 3 Professional and Parrot AR. Drone 2.0. Although different drones vary in their operations, this paper extends the extraction and analysis of the data from the drones and associated devices using some generic methods which are forensically sound adhering to the guidelines of the Association of Chief Police Officers (ACPO)
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