147. Defining the Optimal Serial Testing Interval and Features for Identifying Patients with Early SARS-CoV-2 Infection

Background Serial testing for SARS-CoV-2 is necessary to prevent spread from patients early in infection. Testing intervals are largely derived from viral kinetic studies performed early in the COVID-19 pandemic. Laboratory and epidemiologic data accrued over the past year present an opportunity to use empiric models to define optimal serial testing intervals and features predictive of early infection. Methods Retrospective analysis of 15,314 inpatients within the Mass General Brigham healthcare system who had two tests within a 36-hour period between May 1 2020 and May 29 2021. Early infection was defined as having a negative test followed by a positive test. Patients with prior positive tests were excluded. The primary outcome was the proportion of patients in early infection over the total number tested serially, stratified by 4-hour testing intervals from the timestamp of the first test. Multivariate modeling was used to identify features predictive of early infection. Covariates included demographics, body site, PCR assay, location, community incidence, percent positivity, and median / skew of Ct value distributions. Results Of 19,971 test pairs, 193 (0.97%) were characterized as a negative followed by a positive within 36 hours. Bivariate analysis showed a close association between negative to positive test pairs during the first surge in spring 2020 that was not present during the winter surge. Negative to positive test pairs were most common in the 12 to 16 hour time interval (51/193, 26%, Figure 1). After controlling for covariates, the Roche cobas assay was more likely to identify patients with a negative to positive test pair relative to the Cepheid Xpert, Hologic Panther Fusion and Roche Liat assays. A second specimen from the lower respiratory tract was more likely to lead to a positive relative to other body sites. Community incidence and Ct value distributions were not predictive and there were no differences between nasal and nasopharyngeal swabs. All 4-hour time intervals from 16 to 36 hours were significant for predicting a negative to positive test pair (Table 1). Figure 1. Distribution of negative to positive test pairs by 4 hour time intervals Table 1. Multivariate regression predicting a negative to positive test pair Conclusion The likelihood of detecting early infection is dependent on PCR platform and body site of sampling. A range of time intervals between 16 to 36 hours after the initial test were likely to identify positive cases. Disclosures Sanjat Kanjilal, MD, MPH, GlaskoSmithKline (Advisor or Review Panel member)

PENGEMBANGAN LEMBAR KERJA SISWA MATERI SPLDV BERBASIS KONTEKSTUAL BERBANTUAN SOFTWARE GEOGEBRA UNTUK SISWA KELAS VIII SMP

Abstrak: Penelitian ini bertujuan untuk mengembangkan LKS berbasis kontekstual berbantuan geogebra yang valid, praktis dan efektif. Penelitian ini menggunakan model pengembangan ADDIE dan telah dinyatakan valid dari aspek materi dan media pembelajaran dengan persentase berturut-turut 92,59% dan 92,80%, termasuk kategori sangat baik. Media ini telah diujicobakan kepada siswa kelas VIII SMP PGRI Banyubiru dan menghasilkan indeks kepraktisan penggunaan sebesar 75%, masuk kategori praktis. Uji pair t-test dengan taraf signifikan α = 0,05 menghasilkan signifikan mendekati nol kurang dari 0,05 dengan rata-rata posttest lebih tinggi daripada pretest. Berdasarkan ketiga hasil uji tersebut maka dapat disimpulkan bahwa media ini valid, praktis, dan efektif. Abstract: This study aims to develop a Geogebra based, contextual, practical and effective contextual-based LKS. This research uses ADDIE development model and it has been stated valid from material aspect and instructional media with percentage of 92,59% and 92,80%, including very good category. This media has been tested to students of class VIII SMP PGRI Banyubiru and produce the practicality of the use index of 75%, entered the practical category. T-test pair with significant level α = 0.05 yields significantly close to zero less than 0.05 with posttest average higher than pretest. Based on the three test results it can be concluded that the media is valid, practical, and effective.

Test Pair Selection for Test Case Prioritization in Regression Testing for WS-BPEL Programs

Many web services not only communicate through XML-based messages, but also may dynamically modify their behaviors by applying different interpretations on XML messages through updating the associated XML Schemas or XML-based interface specifications. Such artifacts are usually complex, allowing XML-based messages conforming to these specifications structurally complex. Testing should cost-effectively cover all scenarios. Test case prioritization is a dimension of regression testing that assures a program from unintended modifications by reordering the test cases within a test suite. However, many existing test case prioritization techniques for regression testing treat test cases of different complexity generically. In this paper, the authors exploit the insights on the structural similarity of XML-based artifacts between test cases in both static and dynamic dimensions, and propose a family of test case prioritization techniques that selects pairs of test case without replacement in turn. To the best of their knowledge, it is the first test case prioritization proposal that selects test case pairs for prioritization. The authors validate their techniques by a suite of benchmarks. The empirical results show that when incorporating all dimensions, some members of our technique family can be more effective than conventional coverage-based techniques.

Reliability of Shoulder Symptom Recall after 1 Year in a Retrospective Application of the Oxford Shoulder Score

Background The accuracy of retrospective recall of shoulder symptoms has not been well documented. This prospective study assesses the ability of patients to recall their preoperative shoulder function one year after a surgical intervention, using the Oxford Shoulder Score (OSS). Methods 35 patients completed an OSS before undergoing shoulder surgery. One year later, patients were asked to recall their symptoms prior to their surgery. The recalled OSS of the patients as a group was compared to their preoperative score. The recall bias of each test pair was assessed with a Bland – Altman plot. Results On recall after a mean of 12.6 months, the mean OSS from the index assessment increased from 36.25 to 38.25 points. The mean difference of 2 points for the patients as a group was not significant (p = 0.14). The statistical limits of agreement of the Bland – Altman plot were set at +/-2 SD = 14.079 points. The plotted points showed fair correlation between each individual test pair. Conclusion The recall of symptoms of a large group of patients at 1 year after the index intervention appears to have a moderate correlation with the preoperative scoring. Although statistically acceptable, this limit of agreement is much larger than the 4.5-point difference, established to be clinically relevant in prior studies. The variation seen within the scores at the individual level suggests that these data cannot be used as a retrospective tool.

Practice and Incentive Motivation in Recognition of Inverted Faces

In each of three experiments, participants received successive daily practice sessions on the task of recognizing inverted faces. In all practice sessions, an initial study series of 25 inverted faces was followed immediately by a test series of 17 pairs of inverted faces. Each test pair comprised a face from the study series and a new face. Completely new sets of faces were used in each session. Recognition of inverted faces did not improve across sessions in Exp. 1 but did improve in Exps. 2 and 3. Unlike Exp. 1, Exps. 2 and 3 employed an explicit incentive for improved performance. These results show that sufficiently motivated participants can become quite proficient at recognizing inverted faces. Implications of the results for the role of expertise at recognition in producing the inversion effect are discussed.

Which Train Might Pass the Tunnel First? Testing a Learning Context Suitable for Children

This article describes a nonverbal learning setting, using a miniature railway game, suitable for learning experiments with younger children. To test the setting a brief study on transitive responding was carried out. Children aged between 3 and 6 years were trained with pairs of different coloured trains A + B−, B + C−, C + D−, and D + E− conveying an hierarchical 5-term series A←B←C←D←E (where an arrow represents the relation: ‘A’ may pass the tunnel before ‘B’). Afterwards they were tested for transitivity with the novel test pair BD. The children learned the task quickly. On the average, they showed transitive decisions when confronted with test pair BD. However, among those children who reached the learning criterion, the 3- to 4-yr.-olds showed weaker transitivity than the 5- to 6-yr.-old children. The setting proved to be highly acceptable to the children. It can be potentially varied for operant conditioning tasks with younger children.

Collaborative Study of a Gravimetric Method for Mercury in Formulations Containing Chlorinated Pesticides

A gravimetric method for mercury was modified and collaboratively studied with formulations containing ~6% phenylmercuric urea and ~7% captan in one test pair and ~2% phenylmercuric urea and 30% lindane in another test pair. Mercury is determined by precipitation and weighing cupric propylene mercury iodide (Cu pn2HgI4), following refluxing with dilute HI-H2SO4 solution containing I2. Single determinations on 4 samples by 11 collaborators showed that the standard deviation estimation of random error was 0.063 for the captan pair and 0.034 for the lindane pair. Standard deviation estimates of systematic error were 0.061 and 0.013, respectively. In the preliminary study, the method showed close agreement with other accepted methods for 15 formulations. Lindane, captan, dieldrin, heptachlor, and zineb do not interfere; however, the method is not applicable to chloro- or nitrophenolic compounds nor to materials not decomposed by the digestion mixture. The method has been adopted as official first action.

Collaborative Study of Modified Elmore Method for Mercury in Formulations

The titrimetric method for mercury described by Elmore in 1946 was modified and collaboratively studied with formulations containing 6.7% phenylmercury urea in one test pair and 1% mercuric nitrate in another test pair. Mercury is determined in diluted solution, following reflux at 30 drops/min with fuming H2SO4-red fuming HNO3, by titration with standard thiocyanate solution, using ferric alum as indicator. The method is not applicable in presence of large quantities of chlorine-bearing materials. Single determinations on 4 samples by 14 collaborators showed that the standard deviation estimation of random error was 0.058 for phenylmercury urea and 0.004 for mercuric nitrate. Standard deviation estimates of systematic error were 0.048 and 0.009, respectively. The method has been adopted as official first action.