Development of an Electrowetting Valve in Capillary-Driven Microfluidic Biosensor for Nucleic Acid Detection

This article presents the development of microfluidic valves to be used in capillary flow microfluidic device as a platform for nucleic acid detection. The valve used the principle of electrowetting and was able to be actuated at low voltage. The valve consisted of two silver electrodes which were encountered in series within a microfluidic channel. The second electrode was modified with a hydrophobic monolayer resulting in a cessation of capillary flow. A potential of 4V resulted in a 70° reduction in water contact angle within ten seconds which allowed capillary flow to continue. The final device represented a microfluidic valve for capillary flow microfluidics realized on PMMA substrate. In addition to the valve designed for timed fluid delivery, our PMMA microfluidic chip also consists of self-priming microfluidics with sealed conjugate pads of reagent delivery and an absorbent pad for additional fluid draw. We have developed a single-step surface modification method which allows strong capillary flow within a sealed microchannel. Conjugate pads within the device held trapped complex consisting of the magnetic beads and nucleic-acid-probe-conjugated horseradish peroxidase (HRP). Magnetic beads were released when sample entered the chamber and hybridized with the complex. The complex was immobilized over a magnet in the capture zone while a luminol co-reactant stream containing H2O2 was merged with the channel. A photomultiplier tube was used to quantify the chemiluminescence signal. This new format of biosensor will not only allow for pumpless automatically reagent delivery, but also smaller and more sensitive detection, as well as commercial-scale manufacturing and low materials cost, and it would be an ideal device for fast diagnostic in resource-limited settings

Generating ogives to (i) analyse perceptual changes associated with ambiguous figures, and (ii) reaction times in an inhibition-of-return (IOR) task

The perceptual changes (PCs) associated with viewing an ambiguous figure like the Necker cube (NC) can be considered as a series of independent events in time. The time between successive PCs is then percept duration, and the frequency distribution of percepts plotted against duration is adequately modelled by a gamma distribution (Borsellino et al, 1972 Kybernetik 10 139 - 144). A logarithmic transformation on the duration scale enabled us to model the subsequent distribution with a Gaussian. The cumulative Gaussian fitted to the normalised ogive allowed simple comparison of observer performance in different conditions. We found no differences between ogives generated for the standard 'cube-up' and 'cube-down' 3-D perceptual alternatives. When observers recorded 2-D perceptual alternatives, the ogives were shallower and shifted to the right. This suggests that the neural mechanisms governing PCs between 3-D and 2-D perceptual alternatives differ from those that govern the PCs between the opposing 3-D perceptual alternatives of 'cube-up' and 'cube-down'. Further, we show that the same analysis can be applied to reaction times generated in an inhibition-of-return (IOR) task. We argue that this form of analysis is superior to other more commonly reported methods for both attentional and PC data

Effect of ketamine on cardiovascular function during procedural sedation of adults

INTRODUCTION: Ketamine is commonly used in emergency department procedural sedation. Mild to moderate transient increases in blood pressure, heart rate, and cardiac output are common due to ketamine causing an increase in sympathetic activity. There is a concern that these physiological changes could result in an increased myocardial oxygen demand that may exacerbate underlying cardiac disease. METHODS: Convenience sample of patients older than 50 years receiving ketamine for procedural sedation in the emergency department was used (n = 31). Patients were selected to receive ketamine based on provider discretion. Primary outcome was incidence of new myocardial ischemia apparent on an electrocardiogram (ECG). ECGs were obtained prior to sedation and during the sedation approximately one minute after administration of ketamine. ECGs were reviewed by a board-certified emergency medicine physician and a board-certified cardiologist. RESULTS: New onset ischemia was found in 9.7% (3/31) of ECGs. Of these, one was in a patient who had previously received ketamine without evidence of ischemia on the repeat ECG. There were no statistically significant differences between the groups. Evidence of ischemia on ECG did not impact patient disposition. CONCLUSIONS: Ketamine is a useful medication in procedural sedation; however, careful attention should be made in patient selection when ketamine is the desired agent. Consideration might be made in using the lowest possible dose of ketamine to obtain adequate sedation in order to hopefully lessen the occurrence of ECG changes suggestive of myocardial ischemia. Based on this small sample, single-site study, no evidence of statistically or clinically significant ischemia was seen with the use of ketamine for procedural sedation. Ketamine remains a safe medication option in adults undergoing procedural sedation

Breaking the icosahedra in boron carbide

Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate an approach for characterizing the atomic structure and interatomic bonding of molecules associated with extraordinary structural stability. The discovery of crystallographic planes in these boron carbide datasets substantiates that crystallinity is maintained to the point of field evaporation, and characterization of individual ionization events gives unexpected evidence of the destruction of individual icosahedra. Statistical analyses of the ions created during the field evaporation process have been used to deduce relative atomic bond strengths and show that the icosahedra in boron carbide are not as stable as anticipated. Combined with quantum mechanics simulations, this result provides insight into the structural instability and amorphization of boron carbide. The temporal, spatial, and compositional information provided by atom probe tomography makes it a unique platform for elucidating the relative stability and interactions of primary building blocks in hierarchically crystalline materials

Field-induced canting of magnetic moments in GdCo5 at finite temperature : first-principles calculations and high-field measurements

We present calculations and experimental measurements of the temperature-dependent magnetization of a single crystal of GdCo5 in magnetic fields of order 60 T. At zero temperature the calculations, based on density-functional theory in the disordered-local-moment picture, predict a field-induced transition from an antiferromagnetic to a canted alignment of Gd and Co moments at 46.1 T. At higher temperatures the calculations find this critical field to increase along with the zerofield magnetization. The experimental measurements observe this transition to occur between 44–48 T at 1.4 K. Up to temperatures of at least 100 K, the experiments continue to observe the transition; however, at variance with the calculations, no strong temperature dependence of the critical field is apparent. We assign this difference to the inaccurate description of the zero-field magnetization of the calculations at low temperatures, due to the use of classical statistical mechanics. Correcting for this effect, we recover a consistent description of the high-field magnetization of GdCo5 from theory and experiment

The Practitioner's Dilemma: How to Assess the Credibility of Downscaled Climate Projections

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101803/1/eost2013EO460005.pd

Optimal design of low density marker panels for genotype imputation

Cost-effective genotyping of livestock species can be done through a process which involves genotyping part of the population using a high density (HD) panel and the remainder with a lower density panel and then use imputation to infer the missing genotypes that are not included on the low density panel. Therefore, it is desirable to have a method of selecting markers for an assay that maximises imputation accuracy. Here we present a marker selection method that relies on the pairwise (co)variances between single nucleotide polymorphisms (SNPs) and the minor allele frequency (MAF) of SNPs. The performance of the developed method was tested in a 5 fold cross-validation process using genotypes of crossbred dairy cattle in East Africa, a population in which it is unclear whether existing low density SNP assays designed for purebred populations will maintain high imputation accuracies. Various densities of SNPs were selected using the (co)variance method and alternative SNP selection methods and then imputed up to the HD panel. The (co)variance method provided the highest imputation accuracies at all marker densities, with accuracies being up to 19% higher than the random selection of SNPs. The presented method is straightforward in its application and can ensure high accuracies in genotype imputation of crossbred dairy population in East Africa

Australasian Malignant PLeural Effusion (AMPLE)-3 trial: Study protocol for a multi-centre randomised study comparing indwelling pleural catheter (±talc pleurodesis) versus video-assisted thoracoscopic surgery for management of malignant pleural effusion

Introduction: Malignant pleural effusions (MPEs) are common. MPE causes significant breathlessness and impairs quality of life. Indwelling pleural catheters (IPC) allow ambulatory drainage and reduce hospital days and re-intervention rates when compared to standard talc slurry pleurodesis. Daily drainage accelerates pleurodesis, and talc instillation via the IPC has been proven feasible and safe. Surgical pleurodesis via video-assisted thoracoscopic surgery (VATS) is considered a one-off intervention for MPE and is often recommended to patients who are fit for surgery. The AMPLE-3 trial is the first randomised trial to compare IPC (±talc pleurodesis) and VATS pleurodesis in those who are fit for surgery. Methods and analysis: A multi-centre, open-labelled randomised trial of patients with symptomatic MPE, expected survival of ≥ 6 months and good performance status randomised 1:1 to either IPC or VATS pleurodesis. Participant randomisation will be minimised for (i) cancer type (mesothelioma vs non-mesothelioma); (ii) previous pleurodesis (vs not); and (iii) trapped lung, if known (vs not). Primary outcome is the need for further ipsilateral pleural interventions over 12 months or until death, if sooner. Secondary outcomes include days in hospital, quality of life (QoL) measures, physical activity levels, safety profile, health economics, adverse events, and survival. The trial will recruit 158 participants who will be followed up for 12 months. Ethics and dissemination: Sir Charles Gairdner and Osborne Park Health Care Group (HREC) has approved the study (reference: RGS356). Results will be published in peer-reviewed journals and presented at scientific meetings. Discussion: Both IPC and VATS are commonly used procedures for MPE. The AMPLE-3 trial will provide data to help define the merits and shortcomings of these procedures and inform future clinical care algorithms. Trial registration: Australia New Zealand Clinical Trial Registry ACTRN12618001013257. Registered on 18 June 2018. Protocol version: Version 3.00/4.02.1

Kailo: a systemic approach to addressing the social determinants of young people’s mental health and wellbeing at the local level [version 1; peer review: awaiting peer review]

The mental health and wellbeing of children and young people is deteriorating. It is increasingly recognised that mental health is a systemic issue, with a wide range of contributing and interacting factors. However, the vast majority of attention and resources are focused on the identification and treatment of mental health disorders, with relatively scant attention on the social determinants of mental health and wellbeing and investment in preventative approaches. Furthermore, there is little attention on how the social determinants manifest or may be influenced at the local level, impeding the design of contextually nuanced preventative approaches. This paper describes a major research and design initiative called Kailo that aims to support the design and implementation of local and contextually nuanced preventative strategies to improve children's and young people’s mental health and wellbeing. The Kailo Framework involves structured engagement with a wide range of local partners and stakeholders - including young people, community partners, practitioners and local system leaders - to better understand local systemic influences and support programmes of youth-centred and evidence-informed co-design, prototyping and testing. It is hypothesised that integrating different sources of knowledge, experience, insight and evidence will result in better embedded, more sustainable and more impactful strategies that address the social determinants of young people’s mental health and wellbeing at the local level