International Journal of Biometeorology

We tested the hypothesis that the date of the onset of net carbon uptake by temperate deciduous forest canopies corresponds with the time when the mean daily soil temperature equals the mean annual air temperature. The hypothesis was tested using over 30 site-years of data from 12 field sites where CO2 exchange is being measured continuously with the eddy covariance method. The sites spanned the geographic range of Europe, North America and Asia and spanned a climate space of 16°C in mean annual temperature. The tested phenology rule was robust and worked well over a 75 day range of the initiation of carbon uptake, starting as early as day 88 near Ione, California to as late as day 147 near Takayama, Japan. Overall, we observed that 64% of variance in the timing when net carbon uptake started was explained by the date when soil temperature matched the mean annual air temperature. We also observed a strong correlation between mean annual air temperature and the day that a deciduous forest starts to be a carbon sink. Consequently we are able to provide a simple phenological rule that can be implemented in regional carbon balance models and be assessed with soil and temperature outputs produced by climate and weather models.

The effect of ambient temperature on diurnal rhythm of metabolic rate and activity was studied in group housed pigs in two trials. Two climate controlled respiration chambers were used, one for each trial. Each chamber contained two groups of 8 pigs. During the experiment of 31 days the mean live weight of the animals increased from 28 to 40 kg. Feeding level was kept constant at 93 kg−0.75. d−1. Feed contained 12 kJ of metabolizable energy per g. Temperature treatment started with 20‡C for two days. After that it was lowered in stepwise fashion by 4K to 16, 12 and 8‡C. Each temperature treatment lasted two days. After that temperature it was increased in steps to 20‡C in 8 days. The whole procedure was repeated once. Metabolic rate and activity were measured continuously during the 24 hrs of every second day of the temperature treatment. Metabolic rate increased at temperatures below 16‡C. Activity was associated with ambient temperature. At low temperature, the total activity related heat production was increased, especially during day time. Variation in metabolic rate within a day was not reduced by low ambient temperature. Thermal requirement, calculated as lower critical temperature, was about 14‡C as averaged over the day, (16.1‡C during day time and 13.6‡C during night time). Extra thermal heat production below thermoneutrality was affected by time of day and activity.

There have been numerous studies of the relationship between intracerebral hemorrhage (ICH) and meteorological conditions, but their conclusions have been inconsistent. Poor discrimination of ICH subtypes (primary or secondary) may have obscured the conclusions. Although most studies have analyzed seasonal or monthly variation, daily meteorological data are more appropriate for determining whether weather conditions play a role in triggering the onset of ICH. No studies have examined the activity and location of patients at the time of onset. The aim of this study was to evaluate the relationship between the occurrence of hypertensive ICH and daily meteorological parameters, in addition to examining the effect of the location and activity of the patient at the time of onset. We analyzed 138 patients with severe hypertensive ICH in a hospital-based population. We assessed whether daily meteorological parameters for the days on which ICH occurred differed from the days without ICH onset. Days on which hypertensive ICH occurred had a significantly lower minimum temperature and a decreased minimum temperature from that of the previous day (P=0.0042 and 0.0012, respectively). There were no significant differences among subgroups of patients categorized according to their location and activity at the time of onset for any of the meteorological parameters.

Juniperus pollen is highly allergenic and is produced in large quantities across Texas, Oklahoma, and New Mexico. The pollen negatively affects human populations adjacent to the trees, and since it can be transported hundreds of kilometers by the wind, it also affects people who are far from the source. Predicting and tracking long-distance transport of pollen is difficult and complex. One parameter that has been understudied is the hygroscopic weight gain of pollen. It is believed that juniper pollen gains weight as humidity increases which could affect settling rate of pollen and thus affect pollen transport. This study was undertaken to examine how changes in relative humidity affect pollen weight, diameter, and settling rate. Juniperus ashei, Juniperus monosperma, and Juniperus pinchotii pollen were applied to greased microscope slides and placed in incubation chambers under a range of temperature and humidity levels. Pollen on slides were weighed using an analytical balance at 2- and 6-h intervals. The size of the pollen was also measured in order to calculate settling rate using Stokes’ Law. All pollen types gained weight as humidity increased. The greatest settling rate increase was exhibited by J. pinchotii which increased by 24 %.

32 West African dwarf goats were exposed in respiration chambers to temperature treatments of 20, 25, 30, 35, 35, 35, 30, 25, 20°C. Each treatment lasted three days. 16 goats were kept in individual pens (“I”); the others in two group pens of eight animals each (“G”). During each treatment, heat production and activity were recorded continuously over 48 hours. In addition, feed and water intake, rectal temperature, skin temperature and respiratory rate were measured during each treatment. Compared to 20°C, at 35°C rectal temperature increased from 39.0°C to 39.9°C, respiratory rate from 30 to 260 times. min−1 and skin temperature from 37.1°C to 39.5°C. Hay intake decreased by 40%; concentrates (30 g. kg−0.75. d−1) were always completely consumed. Heat production was higher for the “G” animals at 20°C and higher for the “I” animals at 35°C. These differences in heat production between the two groups were reflected in differences in rectal and skin temperature and in respiratory rate but only very slightly in differences in hay intake. Tissue insulation was 0.014 K. m2. W−1 at 30°C and 35°C and 0.022 K. m2. W−1 at 20°C. It is concluded that the reactions of these dwarf goats to high ambient temperatures are not different in principle from those of other domestic ruminants and that they do not exhibit a specific suitability or unsuitability for ambient temperatures as prevailing in West Africa.

The use of R-R interval and the coefficient of variation in R-R intervals (CVR-R) for the evaluation of thermal comfort was investigated. The experiments were carried out with ten male subjects but data from one were excluded from the analysis. Thermal sensation, comfort, and tolerance of environmental conditions were reported and mean skin temperature, R-R interval and CVR-R were monitored during a 3 h period in a climatic chamber with the operative temperature set at 26, 20, or 30° C. Relative humidity was maintained at ca. 50% in each case. At the operative temperature of 20° C, the mean skin temperature was significantly lower, the cold sensation was significantly more intense, and discomfort was significantly greater than at 26° C and R-R interval was increased significantly. Seven of the nine subjects were unable to tolerate this thermal environment. The R-R interval and CVR-R were increased in five and four of those seven subjects, respectively. At the operative temperature of 30° C, the mean skin temperature was significantly higher, and the sensation of warmth was significantly more intense than at 26° C. Seven of the nine subjects felt discomfort, and four of the seven reported an inability to tolerate this thermal environment. The R-R interval and CVR-R were decreased in four and three of these four subjects, respectively. At the operative temperature of 20° C CVR-R was significantly greater than that at 30° C. Together with the subjective indices, R-R interval and CVR-R are considered worthy of further evaluation as objective indications of the effect on people of the thermal environment.