Efficacy of detergent-based cleaning and wiping against SARS-CoV-2 on high-touch surfaces.

Efficacy of cleaning methods against SARS-CoV-2 suspended in either 5% soil load (SARS-soil) or simulated saliva (SARS-SS) was evaluated immediately (hydrated virus, T0) or 2 hours post-contamination (dried virus, T2). Hard water dampened wiping (DW) of surfaces, resulted in 1.77-3.91 log reduction (T0) or 0.93-2.41 log reduction (T2). Incorporating surface pre-wetting by spraying with a detergent solution (D + DW) or hard water (W + DW) just prior to dampened wiping did not unilaterally increase efficacy against infectious SARS-CoV-2, however, the effect was nuanced with respect to surface, viral matrix, and time. Cleaning efficacy on porous surfaces (seat fabric, SF) was low. W + DW on stainless steel (SS) was as effective as D + DW for all conditions except SARS-soil at T2 on SS. DW was the only method that consistently resulted in > 3-log reduction of hydrated (T0) SARS-CoV-2 on SS and ABS plastic. These results suggest that wiping with a hard water dampened wipe can reduce infectious virus on hard non-porous surfaces. Pre-wetting surfaces with surfactants did not significantly increase efficacy for the conditions tested. Surface material, presence or absence of pre-wetting, and time post-contamination affect efficacy of cleaning methods.

Body composition and skin temperature variation.

Temperature variations near four common torso skin temperature sites were measured on 17 lightly clad subjects exposed to ambient temperatures of 28, 23, and 18 degrees C. Although variations in skin temperature exceeding 7 degrees C over a distance of 5 cm were observed on individuals, the mean magnitude of these variations was 2-3 degrees C under the coolest condition and less at the warmer temperatures. There was no correlation between the temperature variation and skinfold thickness at a site or with estimations of whole body fat content. These findings imply that errors in mean skin temperature measurement could arise from probe mislocation and/or subcutaneous fat distribution and that the problem becomes more acute with increasing cold stress. However, the magnitudes of these errors cannot be easily predicted from common anthropometric measurements.

Computer acquisition and analysis of skin temperature and heat flow data from heat flux transducers.

A computer-controlled system for the collection and analysis of skin temperature and heat flow data originating from an array of heat flux transducers is described. The system is based on a program ('THERMAL') that reads, stores, prints and displays skin temperatures and heat flow data every 2 min for up to 4 h. It also simultaneously calculates important environmental physiology parameters such as mean skin and mean body temperatures as well as mean heat flow according to four different combinations of transducers such as the established 3-, 4-, 7- and 12-point (site) formulae. Core temperature, heart rate and environmental condition indices such as dry bulb, wet bulb and globe temperatures are also continuously monitored.

A thermographic study of the effect of body composition and ambient temperature on the accuracy of mean skin temperature calculations.

The problem associated with using measurements from a small number of sites to determine mean skin temperature was investigated by studying variations in distributions of skin temperatures of the bare torsos of humans exposed to ambient temperatures of 18, 23, and 28 degrees C. Following a 60 minute equilibration period the temperatures of four regions (chest, abdomen, upper back, and lower back) were measured using both thermistors and an infra-red thermographic system. Regions of the torso usually represented by a single temperature exhibited significant point-to-point temperature variations especially in chilled subjects. Also an earlier finding was confirmed: in that larger variations in skin temperature distributions occur as body fat content increases. Caution must therefore be used in applying the concept of a mean skin temperature derived from a few select sites, especially with nude subjects who are chilled or have a high body fat content.

[Respiratory functional hypoxia in ruminants under general anesthesia]. / Die respiratorisch-funktionelle Hypoxie beim Wiederkäuer unter Allgemeinanästhesie.

General anesthesia causes a marked hypoxia in ruminants. We compared this phenomenon with anaesthesia related changes in the dog. Under alfentanil/etomidat anaesthesia some variables of the pulmonary circulation (TPR, PAP, PCWP) as well as arterial and venous blood gases and saturation (HbO2, pO2, ph) in dogs, sheep and calves were measured and calculated. The calculated pulmonary shunt fraction was compared between the three species. In ruminants there was an increase of total pulmonary resistance being associated with elevated PAP and decreased PCWP. The pulmonary shunt fraction was increased significantly and markedly during the surgical tolerance period, too. These parameters were not significantly changed in the dog. Ruminants seem to take an exceptional position concerning the anaesthesia related alterations of the pulmonary ventilation/perfusion system.

Patterns of skin temperature and surface heat flow in man during and after cold water immersion.

The region of the lateral thorax, previously identified as an area of high heat transfer during cold water immersion, was investigated using heat flow discs and thermography to determine values of local heat flow and surface temperature before, during and after immersion. The effect of different positions of the arms on local heat flow from the torso was also investigated. No large site-to-site variation in local heat flow was detected for immersion in water temperatures in the range 18.7-24 degrees C. When the arms were positioned close to the torso, there was a decrease in local heat flow and an increase in local surface temperatures. Thermographic examinations revealed local regions of elevated temperature after the arms were briefly held against the body in the post-immersion stage. In this circumstance, erroneous results can follow from the assumption that an elevated surface temperature always constitutes a signal of increased regional heat flow.

Effect of cold exposure on various sites of core temperature measurements.

Rectal, esophageal, auditory canal, gastrointestinal tract, and sublingual temperature were recorded on five young Caucasian males who, in an environment of -32 degrees C and 11-km/h wind, sat during one 90-min exposure and walked on a treadmill at 2.9 km/h during another. The clothing permitted cooling of their torsos while giving adequate protection to their extremities. Control exposures involved subjects sitting in still air at 24-26 degrees C dressed only in thermal underwear. In the control environment all of the internal body temperatures measured gave comparable and consistent values; however, cold exposure affected the various sites differently. Esophageal temperatures fluctuated rapidly as a result of subjects swallowing cold saliva. Sublingual temperatures were below the lower limit of a clinical thermometer, possibly because of facial cooling. Auditory canal temperatures were low, perhaps also because of facial cooling. Rectal temperatures were high as were the gastrointestinal tract temperatures, due perhaps to local heat production in response to cold stimulation. Metabolic rate increased initially in the cold and again toward the end of the cold exposure.

The effect of alcohol on body heat loss.

The effect of the ingestion of alcohol on cooling in seminude human subjects was examined at 25 and 30 degrees C in air; in heavily clothed individuals at -23 degrees C in air; and nude subjects in a water calorimeter at 25 degrees C. It was observed that consumption of the equivalent of five bar whiskey drinks did not affect the cooling rate of subjects as measured by infrared techniques or by thermistors. Total heat loss, measured in the calorimeter, was also not affected by drinking alcohol. It is concluded that the ingestion of alcohol does not cause an increase in cooling rate in humans.

Body cooling after death.

In the analyses of cases of death in cold air environments, it is often of interest to determine the time required for the body of the individual to cool to ambient temperature. Usually such determinations have been based on Newton's law of cooling. This paper describes a case history in which this technique was experimentally tested and consequently abandoned in favour of a more complex biophysical model which more accurately described the thermo-physical events inherent in body cooling. This model is recommended for determination of the times required for various body parts to cool to ambient environmental temperatures.

Cold-induced shivering in men with thermoneutral skin temperatures.

Twenty-two male Caucasians, aged 20-47 yr, were exposed in a cold room to air temperatures of -33 degrees C while lying in sleeping bags for 2 h. Skin and rectal temperatures as well as electromyographic activity of the chin, forearm, and thigh, were recorded. Shivering occurred in all the subjects, even though skin temperatures were maintained between 31 and 33 degrees C. It is suggested that a counter-current heat exchange occurs whereby the warm blood of the common carotid artery is cooled by cool venous blood in the jugular veins. This cooled arterial blood, in irrigating the hypothalamus, causes shivering.