40 research outputs found
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Multi-scale sensible heat fluxes in the urban environment from large aperture scintillometry and eddy covariance
Sensible heat fluxes (QH) are determined using scintillometry and eddy covariance over a suburban area. Two large aperture scintillometers provide spatially integrated fluxes across path lengths of 2.8 km and 5.5 km over Swindon, UK. The shorter scintillometer path spans newly built residential areas and has an approximate source area of 2-4 km2, whilst the long path extends from the rural outskirts to the town centre and has a source area of around 5-10 km2. These large-scale heat fluxes are compared with local-scale eddy covariance measurements. Clear seasonal trends are revealed by the long duration of this dataset and variability in monthly QH is related to the meteorological conditions. At shorter time scales the response of QH to solar radiation often gives rise to close agreement between the measurements, but during times of rapidly changing cloud cover spatial differences in the net radiation (Q*) coincide with greater differences between heat fluxes. For clear days QH lags Q*, thus the ratio of QH to Q* increases throughout the day. In summer the observed energy partitioning is related to the vegetation fraction through use of a footprint model. The results demonstrate the value of scintillometry for integrating surface heterogeneity and offer improved understanding of the influence of anthropogenic materials on surface-atmosphere interactions
Anatomy, Physiology, and Pathophysiology of Renal Circulation
This chapter covers functional anatomy, physiology, and pathophysiology of the renal circulation. While insights about the anatomy of the renal vasculature have evolved some, the understanding of the physiology has improved substantially. Regarding glomerular filtration rate and renal blood flow, this chapter discusses the three levels of organization that can be recognized in renal physiology: first, principle driving forces of renal blood flow and glomerular filtration (based on the Starling forces); second, autoregulation, the system that stabilizes renal blood flow and glomerular filtration rate upon changes in renal perfusion pressure; and last, the neuroendocrine systems that connect systemic hemodynamics to the regulation of renal blood and glomerular filtration. Regarding pathophysiology, the basic derangements happening in renovascular hypertension, in diabetic nephropathy, in hypertensive renal injury, and in cardiorenal syndrome are described
Plant cognition : ability to perceive ‘touch’ and ‘sound’
Plants’ sessile life-style has enabled them to develop enormous sensitivity towards their dynamic, tactile and clamorous surroundings. Consequently, besides a range of different stimuli, plants can even perceive subtle stimuli, like ‘touch’ and unanticipatedly ‘sound’. Importantly, touch sensitivity in plants is not just limited to sensitive plant and carnivorous species, which respond through eye-catchy movements; instead every plant and living plant cell senses and responds to mechanostimulation, whether intrinsic or extrinsic in nature. For instance, plant roots are extremely touch-sensitive, and upon encountering a barrier in soil, they are able to effectively redirect their growth to transcend it. Similarly, tendrils in climbing plants exhibit extreme sensitivity towards touch, which enable them to sense and grab a support in close vicinity. Unlike touch sensitivity, which was recognized long ago by Robert Hooke and Darwin, plants’ sensitivity towards sound has started gaining attention only recently. The past decade has seen major advances in this area of plant biology; many breakthrough discoveries were made that revealed the, otherwise debatable, ecological significance of sound perception in plants’ life. It has come to light that plants not just sense but also distinguish relevant sound among a mixture of irrelevant sound frequencies; plants distinguish buzz produced by a true pollinator among pollen thieves in the sophisticated process of buzz pollination. Similarly, plants distinguish sound typical of a herbivore for elicitation of defence response. Interestingly, plant roots can sense sound of flowing water in order to direct their growth towards the water source. Given the similarity in the physical properties of touch and sound stimuli, many recently discovered signaling events and molecular players in touch and sound perception are noted to be common. However, in view of the contrasting responses tailored according to the stimuli, plants appear to distinguish well among the two in an ecologically meaningful manner