The effect of tree shade on ambient conditions and heat stress indicator traits of new-born South African Mutton Merino and Dormer lambs: Preliminary results

Fly infestation remains a universal problem for dairy cattle herds, affecting the animals’ health and welfare status. Pre-weaned dairy calves are significantly challenged by the direct and indirect consequences of severe fly infestation, heat-stress and their interaction, which contribute to a stressful and fatiguing environment. Among several physiological, behavioral, clinical and biochemical traits, serum cortisol (SC) and creatine kinase (CK) levels, as well as feed consumption can be used as valid indicators of potential stressful and fatiguing conditions and, therefore, can be efficiently used for stress analysis studies. Hence, the objective of the study was to assess the fly-repellency effect of deltamethrin on pre-weaned dairy calves exposed to heat stress conditions, as well as its association with SC, CK concentrations and feed consumption. Two commercial dairy cattle herds of the Holstein breed in Central Macedonia (Greece) were involved in the study during summer months and under heat stress conditions. Deltamethrin administration resulted in (i) a decreased fly population (100% Musca domestica) landing on pre-weaned dairy calves, (ii) a reduced SC (stress indicator) and CK (fatigue indicator) concentration, and (iii) an increased consumption of feedstuff in deltamethrin treated animals compared to the untreated ones.

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Disinfection by-products and extractable organic compounds in South African tap water

The Journal for Transdisciplinary Research in Southern Africa ◽

10.4102/td.v4i1.170 ◽

2008 ◽

Vol 4 (1) ◽

Author(s):

Carien Nothnagel ◽

Karsten Kotte ◽

J J Pienaar ◽

P G Van Zyl ◽

J P Beukes

Keyword(s):

Drinking Water ◽

South African ◽

Tap Water ◽

Target Range ◽

Preliminary Results ◽

The Us ◽

Microbiological Parameters ◽

Us Epa ◽

Micro Organisms ◽

By Products

An important step in urban purification of drinking water is disinfection by e.g. chlorination where potential pathogenic micro-organisms in the water supply are killed. The presence of organic material in natural water leads to the formation of organic by- products during disinfection. Over 500 of these disinfection by-products (DBPs) have been identified and many more are estimated to form during the disinfection step. Several DBPs such as trihalomethanes (THMs), which is carcinogenic, poses serious health risks to the community. There is very few quantitative data available which realizes the actual levels of these compounds present in drinking water. The levels of four THMs present in drinking water were measured. It included chloroform, bromodichloromethane, chlorodibromomethane and bromoform. Although microbiological parameters are considered to get more attention than disinfection by-products, the measurement of the levels of these compounds in South-African drinking water is essential together with establishing minimum acceptable concentration levels. The target range for total trihalomethanes (TTHMs) established by the US EPA at the end of 2003 is 0-0.08ug/mL. The aim of this paper is to create an awareness of the problem as well as presenting preliminary results obtained with the method of analysis. Preliminary results indicate that urgent attention must be given to the regulation and monitoring of DBPs in South African drinking water.

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Thermal Environment of Urban Schoolyards: Current and Future Design with Respect to Children’s Thermal Comfort

Atmosphere ◽

10.3390/atmos11111144 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1144

Author(s):

Dimitrios Antoniadis ◽

Nikolaos Katsoulas ◽

Dimitris Κ. Papanastasiou

Keyword(s):

Heat Stress ◽

Adverse Effects ◽

Thermal Comfort ◽

Vegetation Cover ◽

Thermal Environment ◽

Positive Impact ◽

High Surface ◽

Well Being ◽

Ambient Conditions ◽

Human Thermal Comfort

Urban outdoor thermal conditions, and its impacts on the health and well-being for the city inhabitants have reached increased attention among biometeorological studies during the last two decades. Children are considered more sensitive and vulnerable to hot ambient conditions compared to adults, and are affected strongly by their thermal environment. One of the urban outdoor environments that children spend almost one third of their school time is the schoolyard. The aims of the present manuscript were to review studies conducted worldwide, in order to present the biophysical characteristics of the typical design of the urban schoolyard. This was done to assess, in terms of bioclimatology, the interactions between the thermal environment and the children’s body, to discuss the adverse effects of thermal environment on children, especially the case of heat stress, and to propose measures that could be applied to improve the thermal environment of schoolyards, focusing on vegetation. Human thermal comfort monitoring tools are mainly developed for adults, thus, further research is needed to adapt them to children. The schemes that are usually followed to design urban schoolyards create conditions that favour the exposure of children to excessive heat, inducing high health risks to them. The literature survey showed that typical urban schoolyard design (i.e., dense surface materials, absence of trees) triggered high surface temperatures (that may exceed 58 °C) and increased absorption of radiative heat load (that may exceed 64 °C in terms of Mean Radiant Temperature) during a clear day with intense solar radiation. Furthermore, vegetation cover has a positive impact on schoolyard’s microclimate, by improving thermal comfort and reducing heat stress perception of children. Design options for urban schoolyards and strategies that can mitigate the adverse effects of heat stress are proposed with focus on vegetation cover that affect positively their thermal environment and improve their aesthetic and functionality.

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A Multicolor Study of AGNs and BL Lacs

International Astronomical Union Colloquium ◽

10.1017/s0252921100039695 ◽

1997 ◽

Vol 159 ◽

pp. 76-77

Author(s):

W.-H. Sun ◽

Yu-Ya Su ◽

Hsiao-Feng Tang ◽

Matthew A. Malkan ◽

Remington P. S. Stone

Keyword(s):

South African ◽

Time Lag ◽

Optical Filters ◽

Astronomical Observatory ◽

Intermediate Band ◽

Variable Field ◽

Preliminary Results ◽

Differential Photometry ◽

Wavelength Filters ◽

Bl Lacs

AbstractWe present preliminary results of two monitoring projects on AGNs and BL Lacs with four intermediate-band optical filters at Lick Observatory, South African Astronomical Observatory, and Siding Spring Observatory. We applied differential photometry between the target and non-variable field stars to derive the variability amplitudes. All the AGNs varied in all wavebands, with amplitudes from 30% to 90%. The variations in shorter wavelength filters are always larger than in longer wavelength filters. We did not observe significant continuum slope changes. Continuum variations of BL Lacs up to 0.2 mag in 20 minutes were observed. Interestingly, we found a time lag of 6–8 minutes between two seemingly correlated variations observed in the intermediate U band with the 1-m telescope and in broad V band with the 24-in. telescope at SSO.

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The Effects of Increased Ambient Temperature on Dual Task Performance

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/1071181381025001100 ◽

1981 ◽

Vol 25 (1) ◽

pp. 379-383

Author(s):

Robert P. Bateman

Keyword(s):

Heat Stress ◽

Ambient Temperature ◽

Performance Improvement ◽

Physiological State ◽

Performance Curve ◽

Ambient Conditions ◽

Dual Task Performance ◽

Significant Performance ◽

Effective Temperatures ◽

Mental Tasks

This paper reports on the effects of two levels of increased ambient temperature on the performance of a tracking task and a variety of secondary mental tasks. Significant performance decrements due to increased ambient temperature were observed for the least complex mental tasks. It must be concluded that for the intelligent, highly motivated subjects used in this experiment, simple tasks involving a minimum of mental effort are more sensitive to Effective Temperatures up to 32.2°C (90°F) for exposure times between one and two hours. It appears that complex mental tasks remain unaffected by ambient conditions that produce only minor changes in the physiological state, and may actually show small increases in performance level. The performance improvement with increasing heat stress for difficult tasks and the corresponding decrement for simple tasks supports a theory that heat stress at the levels used in this study tends to decrease arousal. Based on an inverted-U performance curve, a lower level of arousal would result in the prediction of exactly the results obtained in this study.

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