A threshold-free approach with age-dependency for estimating malaria seroprevalence

Background In malaria serology analysis, the standard approach to obtain seroprevalence, i.e the proportion of seropositive individuals in a population, is based on a threshold which is used to classify individuals as seropositive or seronegative. The choice of this threshold is often arbitrary and is based on methods that ignore the age-dependency of the antibody distribution. Methods Using cross-sectional antibody data from the Western Kenyan Highlands, this paper introduces a novel approach that has three main advantages over the current threshold-based approach: it avoids the use of thresholds; it accounts for the age dependency of malaria antibodies; and it allows us to propagate the uncertainty from the classification of individuals into seropositive and seronegative when estimating seroprevalence. The reversible catalytic model is used as an example for illustrating how to propagate this uncertainty into the parameter estimates of the model. Results This paper finds that accounting for age-dependency leads to a better fit to the data than the standard approach which uses a single threshold across all ages. Additionally, the paper also finds that the proposed threshold-free approach is more robust against the selection of different age-groups when estimating seroprevalence. Conclusion The novel threshold-free approach presented in this paper provides a statistically principled and more objective approach to estimating malaria seroprevalence. The introduced statistical framework also provides a means to compare results across studies which may use different age ranges for the estimation of seroprevalence.

Validation of Performance-Based Specifications for Surface Asphalt Mixtures in Virginia

The Virginia Department of Transportation (VDOT), like many owner agencies, is interested in ways to facilitate the increased durability of asphalt mixes in an effort to make its roadway network more sustainable, longer lasting, and more economical. The balanced mix design (BMD) method proposes to address this through the incorporation of performance criteria into mix design and acceptance. VDOT has committed to the implementation of the BMD method in an effort to improve asphalt mix performance. The purpose of this study was to continue advancing efforts toward implementation of BMD through the evaluation of 13 asphalt mixes using performance-indicating laboratory tests, validation of the initial performance tests selected for BMD use, and validation of the initial test threshold criteria. Based on the results, the asphalt pavement analyzer (APA) rut test, indirect tensile cracking test (IDT-CT), and Cantabro test were found suitable for continued use in BMD. The current threshold criteria for all three tests were found reasonable based on additional mix testing. The study recommends that APA rut test and IDT-CT results should be compared and correlated to fundamental rutting and cracking tests, respectively, as well as to performance predictions obtained from mechanistic-empirical pavement design simulations, and to field performance for full assurance that test threshold values are appropriate. It was further recommended to evaluate the Cantabro, IDT-CT, and APA rut tests to determine acceptable variability and establish precision statements.

TP6.2.15 Staging Laparoscopy and Peritoneal Cytology for Gastric and Gastro-oesophageal Junction Malignancy: an Audit from a Single Oesophagogastric Resection Centre

Aims AUGIS recommends staging laparoscopy in all gastric cancers and selected gastro-oesophageal junction (GOJ) cancers. We previously audited our practice of staging laparoscopy and peritoneal cytology and found that in a cohort of 158 consecutive patients, no tumours less than T3 with negative nodes had positive cytology, resulting in change in practice to selectively use peritoneal cytology in patients with a T-stage of 3 and above or N+ disease. Our aim was to assess the impact of this audit on current practice. Methods We retrospectively reviewed the notes of patients undergoing staging laparoscopy and oesophagogastroduodenoscopy (OGD) identified by MDT from January 2019 to December 2019. Patients who underwent resection on the same day were excluded. Results 63 patients underwent staging laparoscopy and OGD, 54 for GOJ and 9 for gastric disease. The majority were staged as T3 or T4a (81%). As a result of staging laparoscopy and OGD, 4 (6%) patients were changed from curative to palliative pathway, 2 (3%) of whom had positive cytology. No patients had positive peritoneal cytology for a T stage of 2 and below with no positive nodes, further demonstrating the safety of the recommendation. Conclusions Peritoneal cytology has a low yield in changing the clinical course of patients but can upstage up to 6% of patients. The re-audit backs up the previous guidance in the safety of using our current threshold for recommending peritoneal cytology and potentially prevents delaying treatment while waiting for cytology results.

Ge-Source Based L-Shaped Tunnel Field Effect Transistor for Low Power Switching Application

In this work, the performance of the heterojunction L-Tunnel Field Effect Transistor (LTFET) has been analyzed with different engineering techniques such as bandgap engineering, pocket engineering, work-function engineering, and gate dielectric engineering, respectively. The electrical characteristics of the device has been investigated by using Synopsys Sentaurus TCAD tool and compared with some recent other TFETs. The proposed Ge-source L-TFET device with n-type pocket shows ON-state current of 2.12*10-5 Aµm-1, OFF-state current of 1.09*10-13 Aµm-1, current ratio of ~108 and sub-threshold slope (SS) of 21 mV/decade and the threshold voltage of 0.26 V and compared to the conventional Si/Ge source L-shaped TFETs without pocket simulation result. The pocket engineering techniques suppress the leakage without degrading the ON current, threshold voltage and SS of the proposed device. The simplified fabrication steps of the proposed device have also been discussed. The proposed L-TFET is free from ambipolarity issues and can be used to develop low-power switching devices.

Design guidance for protection of geomembrane liners in landfill applications

A new method of evaluating strains and predicting required protection layers that are placed over geomembranes is developed based on the combined effects of the clay strength and stiffness and the cushioning effect of a nonwoven protection layer. Plots giving the required geotextile protection for a different maximum strains are presented for expected landfill pressures under 300 kPa for angular, 38 mm gravel placed above a geomembrane liner for both drained and undrained loading conditions of the clay. A similar plot is also given for tire derived aggregate placed above the liner for pressures under 500 kPa for undrained loading conditions. All tests were conducted at room temperature. For all cases, nonwoven geosynthetic protection layers with mass per unit areas (MUA) exceeding at least 1200 g/m2 were required to limit long term strains below current threshold levels, such as a 4% strain target as given by Rowe and Yu (2019). The MUA of the protection layer, for the particular aggregates and geomembranes tested, is dependent on the loading rate, water content relative to optimum, the silt content, and the activity of the clay below.

Impact of Membrane Resistance on Width and Amplitude of Spikes in Different Injected Currents in One Spiking Neural Model

Neurons in the brain as the elementary processing units and nervous system play a key role. If a neuron gets a proper stimulus, it produces action potentials (spikes) that are transferred along its axon. Reaching the end of the neuron, other neurons or muscle cells may be activated [1]. The effect of neural morphology along with thickness of dendrites and passive electrical parameters on the spikes width and amplitude can be investigated by analytical and numerical investigations of spiking models. The impact of mentioned proper stimulus may be degraded by passing time. In this paper, it is tried to add the effective parameter ’membrane resistance’ in well-known Hodgkin-Huxley model with four dimensions to compare several outputs due to changing resistance and various injected current. The goal of this paper has been to measure spikes changes or even how to determine current threshold when resistance is not constant (non-linear time dependant) result of different factors.

Changing The Firing Threshold for Normal Optic Nerve Axons by The Application of Infra-Red Laser Light

Normal optic nerve axons exhibit a temperature dependence, previously explained by a membrane potential hyperpolarization on warming. We now report that near infra-red (IR) laser light, delivered via a fibre optic light guide, also affects axonal membrane potential and threshold, at least partly through a photo-thermal effect. Application of light to optic nerve, at the recording site, gave rise to a local membrane potential hyperpolarization over a period of about a minute, and increased the size of the depolarizing after potential (DAP). Application near the site of electrical stimulation reversibly raised current-threshold, and the change in threshold recorded over minutes of irradiation was significantly increased by the application of the Ih blocker, ZD7288 (50 µM), indicating Ih limits the hyperpolarizing effect of light. Light application also had fast effects on nerve behaviour, increasing threshold without appreciable delay (within seconds), probably by a mechanism independent of Na+ channels and kinetically fast K+ channels, and hypothesized to be caused by reversible changes in myelin function.

Collision risk of bats with small wind turbines: Worst-case scenarios near roosts, commuting and hunting structures

Small wind turbines (SWTs) have become increasingly common within the last decade, but their impact on wildlife, especially bats, is largely unknown. We conducted an operational experiment by sequentially placing a mobile SWT with five different operational modes at six sites of high bat activity, including roosts, commuting structures, and highly frequented hunting areas. Bat flight trajectories around the SWT were documented at each site during five consecutive nights using a specifically designed high-spatial-resolution 3D camera. The recordings showed high bat activity levels close to the SWT (7,065 flight trajectories within a 10-m radius). The minimum distance to the rotor of each trajectory varied between 0 and 18 m, with a mean of 4.6 m across all sites. Linear mixed models created to account for site differences showed that, compared to a reference pole without a SWT, bats flew 0.4 m closer to the rotor (95% CI 0.3–0.6 m) if it was out of operation and 0.3 m closer (95% CI 0.1–0.4 m) if it was moving slowly. Exploratory behavior was frequently observed, with many bats deviating from their original flight trajectory to approach the rotor. Among 7,850 documented trajectories, 176 crossed the rotor, including 65 while it was in motion. The collision of one P. pygmaeus individual occurred during the experiment. These results demonstrate that, despite the generally strong ability of bats to evade moving rotor blades, bat casualties at SWTs placed at sites of high bat activity can reach or exceed the current threshold levels set for large wind turbines. As SWTs provide less energy than large turbines, their negative impact on bats should be minimized by avoidance measures such as a bat-friendly site selection or curtailment algorithms.

Impact of interface trap charges on Junctionless double and triple metal gate High-k Gate All Around Nanowire FET based Alzheimer Biosensor

In this work, junctionless double and triple metal gate high-k gate all around nanowire field-effect transistor-based APTES biosensor has been developed to study the impact of ITCs on device sensitivity. The analytical results were authenticated using ‘‘ATLAS-3D’’ device simulation tool. Effect of different interface trap charge on the output characteristics of double and triple metal gate high-k gate all around junctionless NWFET biosensor was studied. Output characteristics, like transconductance, output conductance,drain current, threshold voltage, subthreshold voltage and switching ratio, including APTES biomolecule, have been studied in both devices. 184% improvement has been investigated in shifting threshold voltage in a triple metal gate compared to a double metal gate when APTES biomolecule immobilizes on the nanogap cavity region under negative ITCs. Based on this finding, drain off-current ratio and shifting threshold voltage were considered as sensing metrics when APTES biomolecule immobilizes in the nanogap cavity under negative ITCs which is significant for Alzheimer's disease detection. We signifies a negative ITC has a positive impact on our proposed biosensor device compared to positive and neutral ITCs.

Effect of Gate Metal Work-function on Junctionless (JL) Nanowire GAA MOSFET Performance

Metal gate technology is one of the promising methods used to increase the drain current by increasing the electrostatic controllability. Different metals have different work-function that controls the device performance very closely as gate to source voltage is the basic inputs for these. In this paper the dependency of gate metal work-function on device performance (both for nMOS and pMOS) is extensively investigated. The gate metal work-function value is taken as 4.2eV to 5.1eV with one increment to see the change in potential profile. With this condition, the IOn current, IOff current, threshold voltage, transconductance also calculated for these structures. A decrease value in drain current (1e-6 to 1e-7 A) is observed for both the cases with increase in work-function of gate metal. However, the Off current is getting better (1e-7 to 1e-18 A) while moving towards higher metal work-function values. As a result of which the IOn/IOff ratio increases which leads to higher device performances.