Viscose Rayon: An Absorbing Problem. An Investigation into the Impact Conservation Wet Cleaning Treatments have on Historic Woven Viscose Rayon Fabrics; with a Supplementary Analysis of Current Techniques for Identifying Man-Made Fibres

Viscose rayon has been in production for over a century, however, minimal literature is available on its conservation. Pre-1940s viscose rayon has poorer wet strength than later versions. The fiber’s manufacture has influence on its wet strength and progressive improvements to processing methods have improved this characteristic. The implications for conservation wet cleaning treatments on examples from different eras were investigated. Tensile strength testing was conducted on three sets of specimens from different times – c.1940s, c.1960s and c.1980/90s – each subjected to a controlled wet cleaning treatment. Results showed the two later viscose rayons lost significant strength in the wet state, up to 50%. The c.1940s fabric had a greater strength reduction of around 80% - however, degradation from a black colorant present affected the results. This highlighted the risk that degradation, even when not visible macroscopically, can become significantly exacerbated in wetted viscose rayon. Further tensile tests on specimens subjected to wet cleaning and then air dried showed a return of strength upon drying, suggesting that no apparent immediate permanent impact was had on fibers. This research has shown it can be suitable to wet clean viscose rayon, although such treatment may be less appropriate for older more degraded versions

An assessment of the remodelling of bifurcations in hazel (Corylus avellana L.) in response to bracing, drilling and splitting

This paper provides an insight into the ability of bifurcations in hazel trees to remodel themselves after bracing, drilling and splitting. The study uses evidence from field observations and testing the strength of these bifurcations using a universal testing machine alongside wood density tests. This work highlights the importance of the centrally-placed xylem at the apex of hazel forks in supplying tensile strength to the bifurcation. Additionally, it provides evidence that rod-braced bifurcations can atrophy in terms of their tensile strength, growth rate and wood density, suggesting that thigmomorphogenesis plays an important role in the development of a strong bifurcation

Nearly Optimal Sparse Group Testing

Group testing is the process of pooling arbitrary subsets from a set of $n$ items so as to identify, with a minimal number of tests, a "small" subset of $d$ defective items. In "classical" non-adaptive group testing, it is known that when $d$ is substantially smaller than $n$, $\Theta(d\log(n))$ tests are both information-theoretically necessary and sufficient to guarantee recovery with high probability. Group testing schemes in the literature meeting this bound require most items to be tested $\Omega(\log(n))$ times, and most tests to incorporate $\Omega(n/d)$ items. Motivated by physical considerations, we study group testing models in which the testing procedure is constrained to be "sparse". Specifically, we consider (separately) scenarios in which (a) items are finitely divisible and hence may participate in at most $\gamma \in o(\log(n))$ tests; or (b) tests are size-constrained to pool no more than $\rho \in o(n/d)$items per test. For both scenarios we provide information-theoretic lower bounds on the number of tests required to guarantee high probability recovery. In both scenarios we provide both randomized constructions (under both $\epsilon$-error and zero-error reconstruction guarantees) and explicit constructions of designs with computationally efficient reconstruction algorithms that require a number of tests that are optimal up to constant or small polynomial factors in some regimes of $n, d, \gamma,$ and $\rho$. The randomized design/reconstruction algorithm in the $\rho$-sized test scenario is universal -- independent of the value of $d$, as long as $\rho \in o(n/d)$. We also investigate the effect of unreliability/noise in test outcomes. For the full abstract, please see the full text PDF

Firm level hiring policy with culturally biased testing

This paper explores the implications for labor market outcomes of systematic testing of applicants in the hiring process. A matching model in which productivity is a worker's private information is used. Both wages and hiring rates are endogenous. A minority is defined as a group for whom the test is less precise in identifying individual productivity. Welfare and employment outcomes across various hiring policies are compared. Simulations suggest that tests are typically too accurate so that in a laissez faire economy minority group members fair better than the majority group members. Rules requiring equity in hiring reverse this result.

New Archaeological Investigations at the M. S. Roberts Site (41HE8) in the Caddo Creek Valley in Henderson County, Texas

In this article, we discuss new archaeological investigations at the M. S. Roberts site (41HE8), likely a 14th to early 15th century A.D. Caddo period mound center along Caddo Creek in the upper Neches River basin in Henderson County in East Texas. With the permission and cooperation of the landowners, we completed an aerial survey of the site to produce a detailed topographic map as well as assess the plan and profile of the mound and its associated borrow pit, and we also excavated a number of shovel tests around the mound to locate habitation deposits. Finally, a few auger holes were excavated to determine the internal structure of the M. S. Roberts site mound

Analysis of Disengagements in Semi-Autonomous Vehicles: Drivers’ Takeover Performance and Operational Implications

This report analyzes the reactions of human drivers placed in simulated Autonomous Technology disengagement scenarios. The study was executed in a human-in-the-loop setting, within a high-fidelity integrated car simulator capable of handling both manual and autonomous driving. A population of 40 individuals was tested, with metrics for control takeover quantification given by: i) response times (considering inputs of steering, throttle, and braking); ii) vehicle drift from the lane centerline after takeover as well as overall (integral) drift over an S-turn curve compared to a baseline obtained in manual driving; and iii) accuracy metrics to quantify human factors associated with the simulation experiment. Independent variables considered for the study were the age of the driver, the speed at the time of disengagement, and the time at which the disengagement occurred (i.e., how long automation was engaged for). The study shows that changes in the vehicle speed significantly affect all the variables investigated, pointing to the importance of setting up thresholds for maximum operational speed of vehicles driven in autonomous mode when the human driver serves as back-up. The results shows that the establishment of an operational threshold could reduce the maximum drift and lead to better control during takeover, perhaps warranting a lower speed limit than conventional vehicles. With regards to the age variable, neither the response times analysis nor the drift analysis provide support for any claim to limit the age of drivers of semi-autonomous vehicles

Accuracy of Malaria Rapid Diagnostic Tests in Community Studies and their Impact on Treatment of Malaria in an Area with Declining Malaria Burden in North-Eastern Tanzania.

Despite some problems related to accuracy and applicability of malaria rapid diagnostic tests (RDTs), they are currently the best option in areas with limited laboratory services for improving case management through parasitological diagnosis and reducing over-treatment. This study was conducted in areas with declining malaria burden to assess; 1) the accuracy of RDTs when used at different community settings, 2) the impact of using RDTs on anti-malarial dispensing by community-owned resource persons (CORPs) and 3) adherence of CORPs to treatment guidelines by providing treatment based on RDT results. Data were obtained from: 1) a longitudinal study of passive case detection of fevers using CORPs in six villages in Korogwe; and 2) cross-sectional surveys (CSS) in six villages of Korogwe and Muheza districts, north-eastern, Tanzania. Performance of RDTs was compared with microscopy as a gold standard, and factors affecting their accuracy were explored using a multivariate logistic regression model. Overall sensitivity and specificity of RDTs in the longitudinal study (of 23,793 febrile cases; 18,154 with microscopy and RDTs results) were 88.6% and 88.2%, respectively. In the CSS, the sensitivity was significantly lower (63.4%; χ2=367.7, p<0.001), while the specificity was significantly higher (94.3%; χ2=143.1, p<0.001) when compared to the longitudinal study. As determinants of sensitivity of RDTs in both studies, parasite density of<200 asexual parasites/μl was significantly associated with high risk of false negative RDTs (OR≥16.60, p<0.001), while the risk of false negative test was significantly lower among cases with fever (axillary temperature ≥37.5 °C) (OR≤0.63, p≤0.027). The risk of false positive RDT (as a determinant of specificity) was significantly higher in cases with fever compared to afebrile cases (OR≥2.40, p<0.001). Using RDTs reduced anti-malarials dispensing from 98.9% to 32.1% in cases aged ≥5 years. Although RDTs had low sensitivity and specificity, which varied widely depending on fever and parasite density, using RDTs reduced over-treatment with anti-malarials significantly. Thus, with declining malaria prevalence, RDTs will potentially identify majority of febrile cases with parasites and lead to improved management of malaria and non-malaria fevers