Pooled testing efficiency increases with test frequency

Pooled testing increases efficiency by grouping individual samples and testing the combined sample, such that many individuals can be cleared with one negative test. This short paper demonstrates that pooled testing is particularly advantageous in the setting of pandemics, given repeated testing, rapid spread, and uncertain risk. Repeated testing mechanically lowers the infection probability at the time of the next test by removing positives from the population. This effect alone means that increasing frequency by x times only increases expected tests by around x. However, this calculation omits a further benefit of frequent testing: Removing infections from the population lowers intragroup transmission, which lowers infection probability and generates further efficiency. For this reason, increasing testing frequency can paradoxically reduce total testing cost. Our calculations are based on the assumption that infection rates are known, but predicting these rates is challenging in a fast-moving pandemic. However, given that frequent testing naturally suppresses the mean and variance of infection rates, we show that our results are very robust to uncertainty and misprediction. Finally, we note that efficiency further increases given natural sampling pools (e.g., workplaces, classrooms) that induce correlated risk via local transmission. We conclude that frequent pooled testing using natural groupings is a cost-effective way to provide consistent testing of a population to suppress infection risk in a pandemic.

Field evaluation of Rapid SARS-Cov2 Antigen screening test on self-collected deep throat saliva samples in Malaysia

Low cost Rapid Antigen Tests are widely used in Malaysia and the government has also mandated worksite screening as a condition for reopening. Numerous RAT kits have been approved by the Malaysian Medical Device Authority. However, it remains uncertain how these kits would perform in the field. We enrolled workers between June and September 2021 from 23 worksites. They were trained and experienced in performing RAT selftest by virtue of their worksite participation in routine screening program. These workers also had reverse transcriptase polymerase chain reaction tests in the course of mass screening or contact tracing. We also enrolled patients with PCR confirmed Covid19 from a quarantine centre. These patients were instructed on selftesting and then immediately perform RAT under supervision. Two manufacturers donated RAT for this study. A total of 340 participants were enrolled, 130 were from quarantine centre and 210 from worksites. The overall sensitivity of RAT compared to PCR was 70 percent. The specificity was 91 percent. Sensitivity decreased with increasing PCR cycle threshold values. Sensitivity is also lower among untrained subjects at each level of Ct. Logistic regression analysis confirmed false negative result is associated with Ct and participants prior training and experience. This study shows that in the real world, RAT performance were markedly lower than that reported by the manufacturers. The test sensitivity is dependent on the operator training and experience, as well as on viral load as measured by Ct. User training and repeated testing for screening purpose is necessary to mitigate the low sensitivity of RAT.

Pooling for SARS-CoV2 Surveillance: Validation and Strategy for Implementation in K-12 Schools

Repeated testing of a population is critical for limiting the spread of the SARS-CoV-2 virus and for the safe reopening of educational institutions such as kindergarten—grade 12 (K-12) schools and colleges. Many screening efforts utilize the CDC RT-PCR based assay which targets two regions of the novel Coronavirus nucleocapsid gene. The standard approach of testing each person individually, however, poses a financial burden to these institutions and is therefore a barrier to using testing for re-opening. Pooling samples from multiple individuals into a single test is an attractive alternate approach that promises significant cost savings—however the specificity and sensitivity of such approaches needs to be assessed prior to deployment. To this end, we conducted a pilot study to evaluate the feasibility of analyzing samples in pools of eight by the established RT-PCR assay. Participants (1,576) were recruited from amongst the Tufts University community undergoing regular screening. Each volunteer provided two swabs, one analyzed separately and the other in a pool of eight. Because the positivity rate was very low, we spiked approximately half of the pools with laboratory-generated swabs produced from known positive cases outside the Tufts testing program. The results of pooled tests had 100% correspondence with those of their respective individual tests. We conclude that pooling eight samples does not negatively impact the specificity or sensitivity of the RT-PCR assay and suggest that this approach can be utilized by institutions seeking to reduce surveillance costs.

Is Retrieval Practice Always Superior to Restudy?

A classic study by Roediger and Karpicke (2006a) investigated the relative benefits of restudy versus retrieval practice, or “test”, on memory retention. Repeated studying was superior to repeated testing when memory was tested immediately (all study > multiple study/single test > single study/multiple tests). Strikingly, the pattern reversed when memory was tested after a days-long delay, with best performance in a single study/multiple tests condition. As each study period was minutes-long and contained repeated reading of a to-be-remembered text passage, we were interested whether the striking benefit for repeated testing at the expense of any restudy replicates when study opportunities are brief, akin to a single mention of a fact in a lecture. Participants encountered academically relevant facts a total of three times, each time either studied (S) or self-tested (T). Final test followed immediately or after a delay (Experiment 1: two days, Experiment 2: seven days). Partially replicating prior work, immediate memory benefited from repeated study (SSS > SST > STT), but the pattern did not reverse after a delay. Instead, memory was superior for facts the were restudied in addition to self-tested (SST > STT = SSS). We further investigated whether restudy after a test (STS) provides additional benefits compared to restudy before test (SST), but found comparably high delayed recall in both conditions. The results show that under some circumstances, balancing repetition and testing can allow for more information to be learned and retained long-term.

Design improvement of an airbox for a passenger vehicle

The purpose of an airbox is to provide the engine with a clean air flow for combustion. The high velocity of the fluid flow across the airbox will create a pressure drop resulting a decline in the vehicle’s performance. This project collaborates with an Original Equipment Manufacturer (OEM) to develop a numerical simulation model for a new airbox design and to compare its pressure drop with OEM production design. Reducing the pressure drop across the airbox can increase the efficiency of a vehicle, hence, reducing CO2 emissions. This research focuses on the passenger type vehicle as it is the highest source of carbon dioxide (CO2) being emitted for road transportation and these pollutant emissions have also caused many health problems on human. ANSYS Fluent program was used to carry out Computational Fluid Dynamics (CFD) simulation for both OEM and the new design. Then, the same simulation setup was used for the new design. The inlet size of the new design is larger when compared to the OEM design. After analysing both models, it was determined that the main reason behind the pressure loss was caused by the shape of the airbox and turbulent flow inside. The new airbox design shows reduction of 96% in the pressure drop within it and in return, enhancing the performance of the passenger vehicle. This conclude that numerical simulation model is able to provide a good indicator for the designer to choose the best design and proceed with fabrication and conduct actual test, thus saving a lot of prototyping and repeated testing cost.

The effects of moxidectin nicotine-conditioned cue on nicotine-seeking behavior in mice

Current pharmacotherapies for nicotine abuse are few and relatively inefficient demonstrating the need for the development of new, effective remedies. Moxidectin is used as an anti-parasitic agent in both animals and humans, it also activates GABA receptors. The objective of the present investigation was to study the effect of moxidectin on nicotine-induced conditioned place preference (CPP) in male Swiss mice. Intraperitoneal (i.p.) route was used for nicotine (0.5mg/kg) administration for a 3-day conditioning program. The influences of moxidectin on the reinforcing characteristics of nicotine were tested in mice given i.p. treatment of moxidectin (5 and 10mg/kg) 30 minutes prior to per nicotine administration. CPP was extinguished by repeated testing, through which conditioned mice were daily given two doses of moxidectin (5 and 10mg/kg, i.p.). Subsequently, the potency of moxidectin in blocking the reinstatement of CPP provoked by priming given low-dose nicotine (0.1mg/kg, i.p.) was also evaluated. Moxidectin treatment illustrated a reserve of acquisition of nicotine-induced CPP. It was reduced priming nicotine-induced reinstatement and accelerated the extinction of CPP. Relatively nicotine enhanced the locomotor, motor activity but was not statistically significant. In conclusion, the outcomes demonstrate the potential for the development of moxidectin as a new pharmacotherapy for the treatment of nicotine addiction.

Vasomotor Dysfunction in Patients with Ischemia and Non-Obstructive Coronary Artery Disease: Current Diagnostic and Therapeutic Strategies

Many patients who present with symptoms or objective evidence of ischemia have no or non-physiologically-significant disease on invasive coronary angiography. The diagnosis of ischemic heart disease is thus often dismissed, and patients receive false reassurance or other diagnoses are pursued. We now know that a significant proportion of these patients have coronary microvascular dysfunction and/or vasospastic disease as the underlying pathophysiology of their clinical presentation. Making the correct diagnosis of such abnormalities is important not only because they impact the quality of life, with recurring symptoms and unnecessary repeated testing, but also because they increase the risk for adverse cardiovascular events. The mainstay of diagnosis remains an invasive comprehensive physiologic assessment, which further allows stratifying these patients into appropriate “endotypes”. It has been shown that tailoring treatment to the patient’s assigned endotype improves symptoms and quality of life. In addition to the conventional drugs used in chronic stable angina, multiple newer agents are being investigated. Moreover, innovative non-pharmacologic and interventional therapies are emerging to provide a bail-out in refractory cases. Many of these novel therapies fail to show consistent benefits, but others show quite promising results.

COVID-19 testing systems and their effectiveness in small, semi-isolated groups for sports events

In this study, we quantitatively assessed the effectiveness of systems for COVID-19 testing in small groups of sport teams that are semi-isolated from the general population by countermeasures against infection. Two types of group were assumed, and the dynamics of infection within each group was modeled by using a compartment model of infectious disease. One group (Group A) comprised domestic professional sports teams that play many games over a season while remaining within a relatively small region. Polymerase chain reaction (PCR) tests were routinely conducted once every 2 weeks, and the number of infected individuals that could not be removed after identification by testing or checking for symptoms was defined as the risk. The other group (Group B) comprised teams that travel across borders for mass-gathering events like the Olympic and Paralympic Games. The teams were isolated for 2 weeks at their destination; frequent testing and checking for symptoms was conducted, and any infected individuals were removed. The number of infected individuals participating in games after the isolation period was defined as the risk. In Group A, the number of infected individuals detected by routinely conducted PCR testing was lower than the number of infected individuals detected by checking for symptoms, indicating that routine testing every 2 weeks was not very effective. In Group B, daily PCR testing was the most effective, followed by daily antigen testing. Dual testing, in which individuals with a positive antigen test were given an additional PCR test, was the least effective with an effect equal to PCR testing every other day. These results indicate that repeated testing does not necessarily increase the detection of infected individuals.

Firm supervisory board during pandemic

This study investigates public trust in the firm supervisory board, an essential indicator of good corporate governance in some literature. By using 474 non-financial entities in Indonesia during the COVID-19 pandemic and considering a number of firm fundamental factors, this study documents evidence of irrational investor behavior during the pandemic. Investors seem to panic and respond negatively to financial information. However, the public still believes in the independent supervisory board's contribution to the firm. This effect is getting stronger with the presence of an increasingly dominant supervisory board. These results are still robust during repeated testing. This empirical evidence is useful to regulators in emerging markets, industry, and academia.

Measuring Anxiety-Like Behaviors in Rodent Models of Traumatic Brain Injury

Anxiety is a common complaint following acquired traumatic brain injury (TBI). However, the measurement of dysfunctional anxiety behavioral states following experimental TBI in rodents is complex. Some studies report increased anxiety after TBI, whereas others find a decreased anxiety-like state, often described as increased risk-taking behavior or impulsivity. These inconsistencies may reflect a lack of standardization of experimental injury models or of behavioral testing techniques. Here, we review the most commonly employed unconditioned tests of anxiety and discuss them in a context of experimental TBI. Special attention is given to the effects of repeated testing, and consideration of potential sensory and motor confounds in injured rodents. The use of multiple tests and alternative data analysis methods are discussed, as well as the potential for the application of common data elements (CDEs) as a means of providing a format for documentation of experimental details and procedures of each published research report. CDEs may improve the rigor, reproducibility, as well as endpoint for better relating findings with clinical TBI phenotypes and the final goal of translation. While this may not resolve all incongruities in findings across laboratories, it is seen as a way forward for standardized and universal data collection for improvement of data quality and sharing, and advance therapies for neuropsychiatric symptoms that often present for decades following TBI.