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Humidity Levels (humidity + level)
Selected AbstractsDesiccation tolerance in embryonic stages of the tardigradeJOURNAL OF ZOOLOGY, Issue 1 2008R. O. Schill Abstract Desiccation tolerance commonly found among tardigrades allows them to cope with temporal variation of available water. Although the long-term survival of adults has been demonstrated in several species, desiccation tolerance of eggs and embryos is less well studied, however it is an important aspect from an ecological and evolutionary point of view. For the first time we evaluated the desiccation tolerance and subsequent hatching success of five different developmental stages of the tardigrade species Milnesium tardigradum, when rehydrated following drying at eight different humidity levels (10, 20, 31, 40, 54, 59, 72, 81%). Humidity level and developmental stage are significant factors in determining successful hatch rates. The results showed that the less developed stages were quite sensitive to desiccation. Low humidity levels during the first 3 days of development lead to a decrease in hatch rates following rehydration. Later developmental stages showed higher hatch rates than embryos dried at earlier stages. However, fast drying at low humidity levels resulted in delayed development and lower hatch rates following rehydration. In general, further developed embryos exhibit a better survival capacity compared with younger stages. [source] Effect of polyethylene oxide,polyethylene glycol content and humidity on performance of electro-active paper actuators based on cellulose/polyethylene oxide,polyethylene glycol microcompositePOLYMER ENGINEERING & SCIENCE, Issue 6 2010Suresha K. Mahadeva The effect of humidity and polyethylene oxide (PEO),polyethylene glycol (PEG) content on the actuator performance of cellulose/PEO,PEG microcomposites was studied. Upon blending 5% PEO,PEG, the maximum bending displacement of the actuator increased nearly twice compared to that of cellulose EAPap actuator. However, further increase of PEO,PEG content resulted in decreased actuator performance. This might be due to the increased intermolecular interaction by hydrogen bonding that reduces the mobility of the molecules. The actuator performance test showed that the increase in humidity level rather reduced the maximum displacement of the actuators. X-ray diffractogram and Fourier transform infrared spectrum analysis suggested a structural change of the microcomposites as well as disruption of cellulose/PEO,PEG association attributed to the actuator performance degradation at high humidity level. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers [source] Why do captive tufted capuchins (Cebus apella) urine wash?AMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2008Kimran E. Miller Abstract Urine washing (UW) has been observed in numerous species of prosimians and New World monkeys. The functional significance of UW in Cebidae, specifically, Cebus apella, has not been determined. The objective of our study was to test two major hypotheses related to the function of UW: (1) UW functions as a thermoregulatory mechanism, and (2) UW functions as a means of social communication related to (a) territoriality, (b) sexual encounters, or (c) intragroup aggression/agitation. We collected focal data on a captive group of 28 tufted capuchins (C. apella; July,October 2004 and February,July 2005). We found no significant correlation between UW rates and temperature, at a constant, moderate humidity level. Rates of UW were significantly greater outdoors (no conspecific neighbors) vs. indoors (conspecific neighbors). Qualitative evidence suggests a relationship between UW by the alpha male and sexual solicitations from females. UW rates associated with aggression received were significantly higher than UW rates associated with aggression given and UW rates associated with potential fear/stress. There was also a significant negative correlation between cortisol measures and UW frequencies. Our results suggest that UW does not function in thermoregulation or in territorial communication. Alternatively, our results suggest that UW may be associated with sexual encounters and receiving aggression. Additionally, further investigation is warranted to determine whether UW is used as an appeasement mechanism or as a stress reliever or as both. Am. J. Primatol. 70:119,126, 2008. © 2007 Wiley-Liss, Inc. [source] Effects of humidity and temperature on the fatigue behaviour of an extruded AZ61 magnesium alloyFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 4 2005Z. B. SAJURI ABSTRACT Load-controlled fatigue tests were performed at 20 and 50 °C using two relative humidity levels of 55 and 80% to characterize the influence of humidity and temperature on the fatigue behaviour of an extruded AZ61 magnesium alloy. Fatigue tests were also conducted at 150 °C. No significant variation in fatigue properties was noticed with respect to temperature over the range from 20 to 50 °C for both the humidity levels. Fatigue limits in the range 140,150 MPa were observed for relative humidity of 55%. Fatigue strength decreased significantly with increase in temperature to 150 °C. Further, a significant reduction in fatigue strength with a fatigue limit of ,110 MPa was observed with increase in relative humidity to 80% at 20 and 50 °C. The crack initiation and propagation remained transgranular under all test conditions. The fatigue fracture at low stress amplitudes and high relative humidity of 80% results from the formation of corrosion pits at the surface and their growth to a critical size for fatigue-crack initiation and propagation. The observed reduction in fatigue strength at high humidity is ascribed to the effects associated with fatigue,environment interaction. [source] Synoptic climatology of extreme fire-weather conditions across the southwest United StatesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2006Michael A. Crimmins Abstract Extreme fire-weather conditions are usually thought of as discrete events rather than part of a continuum of meteorological and climatological variability. This study uses a synoptic climatological approach (weather typing) to examine the seasonal climatology of extreme fire-weather conditions across the southwest United States (Arizona and New Mexico) during the period of 1988,2003. Three key circulation patterns representing broad southwesterly flow and large geopotential height gradients are associated with over 80% of the extreme fire-weather days identified in this study. Seasonal changes in relative humidity levels, strength of height gradient, and geopotential heights all modulate the relationship between these key circulation patterns and extreme fire-weather days. Examination of daily incident summaries for three recent wildfires (May 2000, June 2002 and June 2003) shows that wildfire activity can be strongly regulated by these critical fire-weather circulation patterns. Copyright © 2006 Royal Meteorological Society. [source] The effect of water-soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheetJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Arja-Helena Vesterinen Abstract Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Desiccation tolerance in embryonic stages of the tardigradeJOURNAL OF ZOOLOGY, Issue 1 2008R. O. Schill Abstract Desiccation tolerance commonly found among tardigrades allows them to cope with temporal variation of available water. Although the long-term survival of adults has been demonstrated in several species, desiccation tolerance of eggs and embryos is less well studied, however it is an important aspect from an ecological and evolutionary point of view. For the first time we evaluated the desiccation tolerance and subsequent hatching success of five different developmental stages of the tardigrade species Milnesium tardigradum, when rehydrated following drying at eight different humidity levels (10, 20, 31, 40, 54, 59, 72, 81%). Humidity level and developmental stage are significant factors in determining successful hatch rates. The results showed that the less developed stages were quite sensitive to desiccation. Low humidity levels during the first 3 days of development lead to a decrease in hatch rates following rehydration. Later developmental stages showed higher hatch rates than embryos dried at earlier stages. However, fast drying at low humidity levels resulted in delayed development and lower hatch rates following rehydration. In general, further developed embryos exhibit a better survival capacity compared with younger stages. [source] | |||||||||||||