Novel measurement system for respiratory aerosols and droplets in indoor environments

The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier.     

Cytotoxic effects of topotecan combined with various anticancer agents in human cancer cell lines

BACKGROUND: Topotecan (TPT) is a topoisomerase I poison that exhibits antineoplastic activity. Analysis of the cytotoxic effects of combinations of TPT and other anticancer agents has been limited. PURPOSE: We assessed the cytotoxic effects produced by combinations of TPT and other antineoplastic agents in experiments involving multiple human cancer cell lines of diverse histologic origins. METHODS: The cytotoxic effects of various antimetabolites (fluorouracil, methotrexate, or cytarabine), antimicrotubule agents (vincristine or paclitaxel [Taxol]), DNA alkylating agents (melphalan, bis[chloroethyl]nitrosourea [BCNU], or 4-hydroperoxycyclophosphamide [4HC]), and a DNA-platinating agent (cisplatin), alone and in combination with TPT, were measured in clonogenic (i.e., colony-forming) assays. HCT8 ileocecal adenocarcinoma, A549 non-small-cell lung carcinoma, NCI-H82ras(H) lung cancer, T98G glioblastoma, and MCF-7 breast cancer cell lines were used in these assays. The data were analyzed by the median effect method, primarily under the assumption that drug mechanisms of action were mutually nonexclusive (i.e., completely independent of one another). For each level of cytotoxicity (ranging from 5% to 95%), a drug combination index (CI) was calculated. A CI less than 1 indicated synergy (i.e., the effect of the combination was greater than that expected from the additive effects of the component agents), a CI equal to 1 indicated additivity, and a CI greater than 1 indicated antagonism (the effect of the combination was less than that expected from the additive effects of the component agents). RESULTS: When the mechanisms of drug action were assumed to be mutually nonexclusive, virtually all CIs for combinations of TPT and either antimetabolites or antimicrotubule agents revealed cytotoxic effects that were less than additive. The CIs calculated at low-to-intermediate levels of cytotoxicity for combinations of TPT and the DNA alkylating agents melphalan, BCNU, and 4HC also showed drug effects that were less than additive; in most cases, however, nearly additive or even synergistic effects were observed with these same drug combinations at high levels of cytotoxicity (i.e., at > or = 90% inhibition of colony formation). Results obtained with combinations of TPT and cisplatin varied according to the cell line examined. With A549 cells, less than additive effects were seen at low-to-intermediate levels of cytotoxicity, and more than additive effects were seen at high levels of cytotoxicity. With NCI-H82ras(H) cells, synergy was observed over most of the cytotoxicity range. CONCLUSIONS AND IMPLICATIONS: TPT cytotoxicity appears to be enhanced more by combination with certain DNA-damaging agents than by combination with antimetabolites or antimicrotubule agents. Interactions between TPT and other drugs can vary depending on the cell type examined. Further investigation is required to determine the basis of the observed effects and to determine whether these in vitro findings are predictive of results obtained in vivo.     

Improvements to an electromagnetic near-field sensor forsimultaneous electric and magnetic field measurement

A sensor for simultaneous electric and magnetic field measurement has been described by M. Kanda (see ibid., vol.EMC-26, no.3, p.102-10, 1984). It relies upon measuring the voltage across precisely matched loads at opposite sides of a loop antenna. A modification to the theory is presented to account for unmatched loading of the loop. Measured results of wave impedance over a 10-400-MHz range demonstrate the accuracy of the modified theory as well as highlighting a novel calibration technique     

Effect of transluminal angioplasty on cerebral blood flow in the management of symptomatic vasospasm following aneurysmal subarachnoid hemorrhage

In this study the authors have examined the effects of transluminal angioplasty on cerebral blood flow (CBF) in the management of intractable vasospasm following aneurysmal subarachnoid hemorrhage (SAH). Fourteen consecutively enrolled patients underwent attempted angioplasty with or without intraarterial infusion of papaverine. Twelve patients underwent pre- and postangioplasty xenon-enhanced computerized tomography (Xe-CT) scanning to measure regional CBF in 55 to 65 regions of interest (ROIs) per patient. Angioplasty was possible in 13 (93%) of 14 patients, with angiographically demonstrated improvement in all 13. Twelve (92%) of the 13 patients were neurologically improved following angioplasty; seven (58%) of the 12 patients who improved had a complete reversal of all delayed ischemic deficits. Angioplasty significantly decreased the mean number of ROIs at risk (11.4 ROIs pre- and 0.9 ROIs postangioplasty) (p < 0.00005, t-test). All patients had a reduction in the number of ROIs at risk after angioplasty; six (50%) of 12 no longer had any ROIs remaining at risk after angioplasty. Angioplasty significantly increased the mean CBF within at-risk ROIs (13 ml/100 g/minute pre- and 44 ml/100 g/minute postangioplasty) (p < 0.00005, t-test). All patients experienced an improvement in mean CBF in at-risk ROIs after angioplasty, with the mean CBF improving to above 20 ml/100 g/minute in all cases. No differences in the degree of improvement were found in patients who received intraarterial papaverine compared with those who did not. In the majority of patients with refractory vasospasm following SAH, angioplasty effectively dilated spastic arteries, reversed delayed neurological deficits, and significantly improved CBF in areas of brain at risk of infarction.     

An overview of nondestructive evaluation methods

ondestructive evaluation is described as nondestructive testing (NDT), nondestructive inspection (NDI), and nondestructive examination (NDE). The activities associated with the evaluation include testing, inspection, and examination and primarily involve looking at (or through) and/or measuring some characteristic of an object. Frequently there is a desire to determine some characteristic of the object or to determine whether the object contains irregularities, discontinuities, or flaws. These examinations, inspections, or tests are used to determine the physical soundness of a material without impairing its usefulness. Nondestructive evaluation is a powerful tool that can help assure safety, quality, and reliability; increase productivity; decrease liability; protect the environment; and save money. In this article, nondestructive evaluation is represented by the acronym NDE.     

Ethical issues concerning expert systems' applications in education

This article traces the connection between expert systems used as consultants in medicine and their design for instructional purposes in education. It is suggested that there are important differences between these applications. Recognizing these differences leads to the view that the development of intelligent computer-assisted instructions (ICAI) should be guided by empirical research into social/psychological consequences and by ethical inquiries into the acceptability of those consequences. Three proposals are put forward: (1) that the pedagogical role of intelligent CAI be clarified, (2) that forms of intelligent CAI be developed that aim primarily at refining rather than replacing human judgements, and (3) that ICAI research and development projects contain components which address ethical and social/psychological components and which are equitably-funded, integral parts of the overall development effort.This work was supported in part by funds from the Foundation of the University of North Carolina at Charlotte and from the State of North Carolina. An earlier version of this paper was read at the Human Dimension in Artificial Intelligence Symposium held at the University of Kentucky (April 1988).     

Prevention and Mitigation Strategies to Address Recent Brittle Fractures in Steel Bridges

Brittle fracture results in unplanned loss of service, very costly repairs, concern regarding the future safety of the structure, and potential loss of life. These types of failures are most critical when there is no evidence of fatigue cracking leading up to the fracture and the fracture origin is concealed from view. Hence, the failure occurs without warning and the details are, essentially, noninspectable. In these cases, it appears desirable to take a proactive approach and introduce preventative retrofits to reduce the potential for future crack development. These efforts will help ensure that the likelihood of unexpected fractures is minimized. This paper examines the behavior of two bridge structures in which brittle fractures have developed in recent times, discusses the causes of the failures, and offers suggested design strategies for prevention and retrofit mitigation techniques. In situations where considerable uncertainty exists in the prediction of accumulated damage or in the ability to reliably inspect critical details, preemptive retrofit strategies appear to be highly desirable.     

Reduction of Radiation-Induced Hair Loss by Topical Application of Radioprotectors

ABSTRACT

Our transdermal permeation studies of radioprotectors in permeation-enhancing vehicles led us to hypothesize that radiation-induced hair loss could be reduced by topical application of radioprotectors. In the present study we used a hair regrowth assay in “plucked” mice to measure the radioprotective effectiveness of WR-1065, cysteine and TEMPOL when they were dissolved in a variety of vehicles, i.e., saline, dimethyl formamide (DMF), propylene glycol (PG), dimethyl sulfoxide (DMSO), ethanol. Protector effectiveness varied with radiation dose and vehicles. At 600 R, WR-1065 or cysteine, in any vehicle, reduced radiation-induced baldness scores; at 800 R, only WR-1065 in DMF and cysteine in saline, produced some protection. TEMPOL in ethanol produced protection at both the 600 and 800 R. Results suggest that suitably chosen topical application of protector/vehicle combinations can reduce radiation-induced hair loss.     

Off flavours in large waterbodies: physics, chemistry and biology in synchrony.

The Laurentian Great Lakes of North America are a drinking water source for millions of Canadian and US consumers. These waterbodies have undergone extensive change over the past century as a result of widespread degradation and remediation. Many of the Lakes are prone to taste and odour (T&O), and although these outbreaks have been poorly monitored, evidence suggests that they are increasing in frequency. Tracing and controlling T&O in such large systems presents a challenging task, due to their physical size and complexity. This paper presents an overview of recent investigative and management approaches to T&O in Lake Ontario and its outflow, the St. Lawrence River. We have identified three distinct patterns of T&O in these source-waters, caused by geosmin and 2-methylisoborneol and differing in their planktonic and benthic sources, and temporal and spatial dynamics. Each pattern has required a different approach by scientists and management, in partnership with the water industry. We have shown these T&O outbreaks are caused and moderated by physical, chemical and biological mechanisms over a spectrum of spatial and temporal scales. Canadian municipalities affected by these outbreaks have been key to the investigation of the links between T&O and ecosystem processes with the aim to develop more proactive water treatment and long-term management.