Estimating transpiration from 6-year-old Eucalyptus grandis trees: development of a canopy conductance model and comparison with independent sap flux measurements

Daily patterns of stomatal conductance (g_s), xylem pressure potential (P) and canopy microclimatic variables were recorded on 11 sample days as part of a one-year study of the water use of Eucalyptus grandis Hill ex Maiden in the eastern Transvaal, South Africa. Measured g_s was found to be largely controlled by quantum flux density (Q) and ambient vapour pressure deficit (D). Canopy conductance (g_c) was determined for hourly intervals using g_s measurements and leaf areas in four different canopy levels. A simple model was constructed to allow the prediction of g_c and transpiration from Q, D and season of year. The model was used to estimate transpiration rates from 10 trees in a later study of similarly-aged E. grandis trees, in which sap flow in each tree was measured using the heat pulse velocity (HPV) technique. Five of the trees were monitored on a summer day and five on a winter day. Correspondence between HPV sap flow and modelled transpiration was good for the summertime comparisons, but measured winter-time sap flow rates were underestimated by the model, especially under conditions of high sap flow. The discrepancy is believed to result from having insufficient data from the conductance study to describe the response of g_s to relatively high D in winter. Marked variation in transpiration per unit leaf area indicates that a relatively large number of trees must be sampled for the HPV technique to be used to obtain a mean rate for an entire stand in winter.     

经颅多普勒超声对80例偏头痛病人的检测分析

经颅多普勒超声波对８０例偏头痛病人与１１０例正常对照组血流速度进行检测．结果发现病例组血流速度异常为８７．５％。根据血流速度改变,本组分为血流速度增快型与血流速度减慢型,这有助于偏头痛的临床诊断。     

Transpiration by an emergent macrophyte: source of water and implications for nutrient supply

The contribution of sediment interstitial water and the water column to the transpiration stream of Myriophyllum aquaticum (Vellozo) Verdcourt was determined to estimate the significance of mass flow in supply of sediment nutrients for plant growth. Sediment interstitial water accounted for about 2% of the water transpired over a 37 day period. Because of the small volume of water that originated in the sediment we concluded that mass flow did not significantly enhance nutrient supply to the roots of M. aquaticum. Relative growth rate (RGR) of adventitious, water roots was greater than whole plant RGR, and RGR of sediment roots was not significantly different from zero, indicating a shift in the biomass allocation after emergence of the apical meristem into the air. Water use, measured by the transpiration coefficient, averaged 260 ml H₂O mg DW^-1, which is similar to C-4 terrestrial plants. M. aquaticum has leaf characteristics commonly associated with xerophytic habitats. These characteristics may be necessary if a high transpiration rate and a mechanical requirement for high cell turgor pressure, required by a reliance upon hydrostatic pressure for support of the aerial stems, are mutually exclusive because of morphological constraints on hydraulic conductivity.     

Estimation of disruption of animal cells by turbulent capillary flow

Disruption of animal cells in turbulent capillary flows has been predicted from a model of cell-hydrodynamic interactions using cell mechanical properties determined by micromanipulation. Eddies of sizes similar to or smaller than the cells are presumed to interact with those cells, causing local surface deformations. The proposed mechanism of cell damage is that such deformations result in an increase in membrane tension and surface energy and that a cell disrupts when its bursting membrane tension and bursting surface energy are exceeded. The surface energy of the cells is estimated from the kinetic energy of appropriately sized eddies. To test the model, cells were disrupted in turbulent flows in capillaries at mean energy dissipation rates up to 2 x 10(4) m(2)/s(3). In all cases the model underestimated the cell disruption by about 15%. Such good agreement implies that the approach of the model to the complicated phenomena of cell turbulence interactions is reasonable. (c) 1993 John Wiley & Sons, Inc.     

Monitoring glutamine in animal cell cultures using a chemiluminescence fiber optic biosensor

Together with flow injection analysis (FIA), a chemiluminescence (CL) fiber optic biosensor system has been developed for determining glutamine in animal cell cultures. Glutaminase (GAH) and glutamate oxidase (GLO) were onto separate porous aminopropyl glass beads via glutaraldehyde activation and packed to form an enzyme column. These two enzymes acted in sequence on glutamine to produce hydrogen peroxide, which was then reacted with luminol in the presence of ferricyanide to produce a light signal. An anion exchanger was introduced on-line to eliminate interfering endogenous glutamate in view of its negative charge at pH above 3.22 (isoelectric pH). Among several resins tested, the acetate form was most effective, and this type of ion exchanger also effectively adsorbed uric acid, acetaminophen, and aspartic acid.There was an excellent linear relationship between the CL response and standard glutamine concentration in the range 1 to 100 muM. A complete analysis could be performed in 2 min, including sampling and washing with a good reproducibility (+/- 4.4%). Both the bi-enzymic and ion exchange columns were useful for at least 500 analyses when the biosensor system was applied for the glutamine determination in murine hybridoma cell cultures and insect cell cultures. The values obtained compared well with those of HPLC, thus validating the applicability of the CL fiber optic system. (c) 1993 John Wiley & Sons, Inc.     

PEAK SHIFTS AND POLYMORPHISM DURING PHASE THREE OF WRIGHT'S SHIFTING-BALANCE PROCESS

The third phase of Wright's shifting-balance theory involves the export of adaptive gene combinations from one subpopulation to another. Previous results have demonstrated that this can occur at very low migration rates, but it has been argued that this simply reflects the ability of migration to overcome selection and fix any (even deleterious) alleles. Here, previous analyses are extended by concentrating on the critical balance between forward and reverse migration rates that still allows phase III to proceed. It is shown that selective advantage, dominance, recombination rate, and the number of loci all affect the ability of a genotype to invade and become fixed in a new subpopulation, but it is unlikely that phase III will occur in the absence of differential migration unless the invading genotype consists of a few dominant loci with a large selection advantage, spreading into a few populations of lower fitness. Therefore, as was envisioned by Wright, differential migration from more to less fit populations will be necessary for phase III to occur under most circumstances.     

Ecology and genetics of insecticide resistance inHelicoverpa armigera: Interactions between selection and gene flow

Pyrethroid resistance inHelicoverpa armigera provides a model system in which to study evolution in natural populations. Resistance is seen to evolve as a consequence of selection pressure that varies within and between life-stages and gene flow. Although three different mechanisms are involved, present day fluctuations in phenotype frequency can be explained by variation in only one of these, metabolic resistance, that is inherited as a single, incompletely dominant gene,mfo. Selective mortality of phenotypes occurs in both larvae and adults in the presence of the pyrethroid insecticides. Although most individuals of all three genotypes are killed in young larvae, selection in this age-class contributes significantly to evolution of resistance. While there is some evidence of reduced fitness of resistant pupae during winter diapause, most of the decline in resistance frequencies each spring occurs as a result of immigration of susceptible individuals into insecticide-treated populations.     

Effects of body and head positions on bilateral difference in tympanic temperatures

We have examined the nonparallel changes in tampanic membrane temperatures (T _ty) from the two ears in response to various changes in body and head positions. Upon assuming a lateral recumbent position, the T _ty on the lower side increased while that on the upper side decreased. Pressure application over a wide area of the lateral chest only caused inconsistent and obscure asymmetric changes in T _ty. A lateral flexion of the head with the subject sitting upright and a rotation of the head to the side in a supine position induced an increase in the T _ty on the lower side compared to that on the upper side. The temperature and blood flow of the forehead often decreased on the lower side and increased on the upper side, although such responses were not always concomitant with the asymmetric changes in T _ty. A dorsal flexion of the head with the subject in a reclining position caused a slight increase in the T _ty, whereas raising the head upright induced a slight decrease in them. Two additional experiments were carried out with single photon emission computed tomography using ^99mTc-hexamethylpropyleneamine oxime as tracer, and a slight, relative decrease in counts was noted in the right hemisphere during rotation of the head to the right. These results would strongly suggest that unilateral increases and decreases in T _ty could have been caused by one-sided decreases and increases, respectively, in blood flow to the brain and/or the tympanic membrane, induced by a vasomotor reflex involving vestibular stimulation.     

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

Climate change is altering hydrological cycles globally, and in Mediterranean (med-) climate regions it is causing the drying of river flow regimes, including the loss of perennial flows. Water regime exerts a strong influence over stream assemblages, which have developed over geological timeframes with the extant flow regime. Consequently, sudden drying in formerly perennial streams is expected to have large, negative impacts on stream fauna. We compared contemporary (2016/17) macroinvertebrate assemblages of formerly perennial streams that became intermittently flowing (since the early 2000s) to assemblages recorded in the same streams by a study conducted pre-drying (1981/82) in the med-climate region of southwestern Australia (the Wungong Brook catchment, SWA), using a multiple before-after, control-impact design. Assemblage composition in the stream reaches that remained perennial changed very little between the studies. In contrast, recent intermittency had a profound effect on species composition in streams impacted by drying, including the extirpation of nearly all Gondwanan relictual insect species. New species arriving at intermittent streams tended to be widespread, resilient species including desert-adapted taxa. Intermittent streams also had distinct species assemblages, due in part to differences in their hydroperiods, allowing the establishment of distinct winter and summer assemblages in streams with longer-lived pools. The remaining perennial stream is the only refuge for ancient Gondwanan relict species and the only place in the Wungong Brook catchment where many of these species still persist. The fauna of SWA upland streams is becoming homogenised with that of the wider Western Australian landscape, as drought-tolerant, widespread species replace local endemics. Flow regime drying caused large, in situ alterations to stream assemblage composition and demonstrates the threat posed to relictual stream faunas in regions where climates are drying.     

Combining industrial ecology tools to assess potential greenhouse gas reductions of a circular economy: Method development and application to Switzerland

Industrial ecology (IE) methodologies, such as input/output or material flow analysis and life cycle assessment (LCA), are often used for the environmental evaluation of circular economy strategies. Up to now, an approach that utilizes these methods in a systematic, integrated framework for a holistic assessment of a geographic region's sustainable circular economy potential has been lacking. The approach developed in this study (IE4CE approach) combines IE methodologies to determine the environmental impact mitigation potential of circular economy strategies for a defined geographic region. The approach foresees five steps. First, input/output analysis helps identify sectors with high environmental impacts. Second, a refined analysis is conducted using material flow and LCA. In step 3, circular strategies are used for scenario design and evaluated in step 4. In step 5, the assessment results are compiled and compared across sectors. The approach was applied to a case study of Switzerland, analyzing 8 sectors and more than 30 scenarios in depth. Carbon capture and storage (CCS) from waste incineration, biogas and cement production, food waste prevention in households, hospitality and production, and the increased recycling of plastics had the highest mitigation potential. Most of the scenarios do not influence each other. One exception is the CCS scenarios: waste avoidance scenarios decrease the reduction potential of CCS. A combination of scenarios from different sectors, including their impact on the CCS scenario potential, led to an environmental impact mitigation potential of 11.9 Mt CO₂-eq for 2050, which equals 14% of Switzerland's current consumption-based impacts.