A simple three-cylinder radiometer and low-speed anemometer to characterize human extreme heat exposure

As populations and temperatures of urban areas swell, more people face extreme heat and are at increasing risk of adverse health outcomes. Radiation accounts for much of human heat exposure but is rarely used as heat metric due to a lack of cost-effective and accurate sensors. To this end, we fuse the concepts of a three-globe radiometer-anemometer with a cylindrical human body shape representation, which is more realistic than a spherical representation. Using cost-effective and readily available materials, we fabricated two combinations of three cylinders with varying surface properties. These simple devices measure the convection coefficient and the shortwave and longwave radiative fluxes. We tested the devices in a wind tunnel and at fourteen outdoor sites during July 2023's record-setting heat wave in Tempe, Arizona. The average difference between pedestrian-level mean radiant temperature (MRT) measured using research-grade 3-way net radiometers and the three-cylinder setup was 0.4 ± 3.0 °C ( ±  1 SD). At most, we observed a 10 °C MRT difference on a white roof site with extreme MRT values (70 °C to 80 °C), which will be addressed through discussed design changes to the system. The measured heat transfer coefficient can be used to calculate wind speed below 2 m·s-1; thus, the three cylinders combined also serve as a low-speed anemometer. The novel setup could be used in affordable biometeorological stations and deployed across urban landscapes to build human-relevant heat sensing networks.

Extracorporeal life support outcome for 128 pediatric patients with respiratory failure

PURPOSE

The aim of this study was to describe a single-center experience with pediatric extracorporeal life support (ECLS) and to determine variables predictive of outcome in pediatric patients, both before the institution of ECLS and while on support.

METHODS

From October 1985 to September 1998 the authors supported 128 children with severe acute hypoxemic respiratory failure(n = 121, Pao2/FIo2 ratio = 58+/-29) or acute hypercarbic respiratory failure (n = 7, Paco2 = 128+/-37), despite maximal conventional ventilation. Mode of access included venoarterial bypass (VA, n = 64), venovenous bypass (VV, n = 53), and VV to VA bypass (n = 11). The techniques used included lung rest, pulmonary physiotherapy, diuresis to dry weight using hemofiltration if needed, minimal anticoagulation, and optimal systemic oxygen delivery.

RESULTS

The median age was 1.4 years (range, 2 weeks to 17 years). The mean duration of ECLS was 288+/-240 hours (range, 4 to 1148 hours or 0.2 to 47.8 days). Lung compliance increased from 0.32+/-0.02 mL/cm H2O/kg to 0.59+/-0.03 mL/cm H2O/kg in survivors, but only increased from 0.34+/-0.02 mL/cm H2O/kg to 0.35+/-0.02 mL/cm H2O/kg in nonsurvivors (P<.002 comparing change between survivors and nonsurvivors). Mean body weight decreased from 9%+/-2% over dry weight to 4%+/-2% in survivors, whereas in nonsurvivors the mean body weight increased from 25%+/-5% over dry weight to 35%+/-7% (P<.001). Outcome results by diagnosis were pneumonia, 73%; acute respiratory distress syndrome, 67%; and airway support, 60%, with overall lung recovery occurring in 77%, and hospital survival in 71%. Multivariate logistic regression modelling of patients with hypoxemic respiratory failure found the only pre-ECLS variable significantly associated with outcome to be pH (P<.05). Variables during the course of ECLS significantly associated with decreased survival were the presence of creatinine greater than 3.0 (P<.01), the need for inotropes (P<.04), failure to return the patient to dry weight (P<.04), and lung compliance that did not improve significantly. (P<.01).

CONCLUSIONS

ECLS provides life support in severe respiratory failure in children, allowing time for injured lungs to recover. Pre-ECLS predictors, such as pH and variables during ECLS, such as presence of renal failure, improvement in compliance, return to dry weight, and the need for inotropes on ECLS, may be useful for predicting outcome.

Reverse-micelle model: pH, electromagnetic field and inhibitor enzyme interaction

The reverse micelle is one of many models thought to have properties more nearly resembling the biological cellular environment, than does the traditional dilute-solution biochemical reaction system. In order to evaluate the results of EMF perturbation of enzyme-catalyzed reactions, the description of the AOT reverse-micelle model, with respect to its internal pH, effect of chemical inhibitors, temperature, and electromagnetic-field perturbation has herein been extended. Acetylcholinesterase and NADPH cytochrome-P450 reductase, reacting within the AOT reverse-micelle, exhibit a temperature vs. activity profile equivalent to the same reaction in a buffered dilute-solution environment. In reverse micelles, some inhibitors of AChE (propidium, and d-tubocurarine) have much less effect upon indophenol-acetate hydrolysis than they do in a dilute solution environment. Other inhibitors act in the same manner within the structured environment of the reverse micelle as in the conventional dilute solution reaction model. These differences are explicable in terms of mechanism of action of the individual inhibitors. Perturbation by low-intensity microwave fields has a similar inhibitory effect upon dilute-solution reactions, as those in the 'low-water-activity' environment of the reverse micelle. However, the interactions between physical and chemical perturbants are differently limited by the structure of the aqueous phase of the reverse micelle. pH of the 'internal' reverse-micelle environment is a function of the availability of H-ions supplied by system components. Use of indicator dyes show that the low-molarity buffers which are compatible with reverse-micelle stability, are often insufficient to maintain a constant pH. Too, in the reverse micelle, reaction rate, for proton yielding reactions, is dramatically greater than the rate of the same reaction in dilute solution at the same acidic pH.

Rapid screening and selection of monoclonal antibodies by bivariate flow cytometric analyses

We describe a bivariate flow cytometric assay to rapidly identify hybridomas producing new monoclonal antibodies recognizing subpopulations that are unreactive with existing immunological reagents. In this screen, whole cells in microtiter wells are labeled first with a red-linked test antibody, and then with a green-linked cocktail of existing monoclonal antibody reagents. The multiply-stained fluorescent cells are analyzed flow cytometrically and bivariate distributions of red vs. green-linked antibody fluorescence are generated. Test antibodies that recognize different subpopulations than those labeled by antibodies in the cocktail are readily identified. The use of an antibody cocktail conjugated with a single fluorophore allows comparison of the reactivity of the test antibody with multiple existing antibodies in a single analysis. This screen allows rapid (approximately 100 test antibodies can be evaluated in 40 min) identification of potentially interesting new antibodies for discrimination of subpopulations in heterogeneous tissues. We describe application of this assay to identify antibodies useful to mark hemopoietic subpopulations.