The leaf hydraulic conductance (K(leaf)) is a major determinant of plant water transport capacity. Here, we measured K(leaf), and its basis in the resistances of leaf components, for fully illuminated leaves of five tree species that regenerate in deep shade, and five that regenerate in gaps or clearings, in Panamanian lowland tropical rainforest. We also determined coordination with stomatal c...

The effects of acute changes in circulating blood volume on embryonic vascular hemodynamics were evaluated with the use of input impedance. We simultaneously measured dorsal aortic pressure with a servo-null system and flow velocity with a 20-MHz pulsed Doppler system in n = 90 stage 24 chick embryos. We withdrew or infused 1,3, or 5 microliters of blood via a second-order vitelline vein (n = 1...

Possible mechanical and hydraulic costs to increased cavitation resistance were examined among six co-occurring species of chaparral shrubs in southern California. We measured cavitation resistance (xylem pressure at 50% loss of hydraulic conductivity), seasonal low pressure potential (P(min)), xylem conductive efficiency (specific conductivity), mechanical strength of stems (modulus of elastic...

We examine the validity of commonly used Hagen-Poiseuille model local resistance porous media using direct numerical simulations. provide theoretical arguments that highlight possible limitations this and formulate a new constitutive is based on circularity iso-pressure surfaces. compare performance both models three different three-dimensional artificial media. show improves root-mean-squared-...

The hydraulic resistance characterization manuscript chronicles the early development of the hollow-core fiberoptic microneedle device (FMD). The study determined that for straight tubing with an inner bore of 150 μm and a length greater than 50 mm long, Poiseuille’s Law was shown to be accurate within 12% of experimental data for the pressure range of 69-517 kPa. Comparison between different n...

−This paper proposes a method that can be used for the resistance estimation of a PWM (Pulse Width Modulation)-driven solenoid. By using estimated solenoid resistance, the PWM duty ratio was compensated to be proportional to the solenoid current. The proposed method was developed for use with EHB (Electro-Hydraulic Braking) systems, which are essential features of the regenerative braking syste...

Water availability has been considered one of the crucial drivers of species distribution. However, the increasing of temperatures and more frequent water shortages could overcome the ability of long-lived species to cope with rapidly changing conditions. Growth and survival of natural populations adapted to a given site, transferred and tested in other environments as part of provenance trials...

Coordination of water movement among plant organs is important for understanding plant water use strategies. The hydraulic segmentation hypothesis (HSH) proposes that hydraulic conductance in shorter lived, 'expendable' organs such as leaves and longer lived, more 'expensive' organs such as stems may be decoupled, with resistance in leaves acting as a bottleneck or 'safety valve'. We tested the...

Hydraulic traits were studied in temperate, woody evergreens in a high-elevation heath community to test for trade-offs between the delivery of water to canopies at rates sufficient to sustain photosynthesis and protection against disruption to vascular transport caused by freeze-thaw-induced embolism. Freeze-thaw-induced loss in hydraulic conductivity was studied in relation to xylem anatomy, ...

Chaparral species of California, USA, exhibit three life history types in response to fire: non-sprouters (NS), facultative sprouters (FS), and obligate sprouters (OS). Adult non-sprouters are killed by fire; thus populations reestablish only through firestimulated seed germination and seedling recruitment. Facultative sprouters reestablish by both vegetative sprouting and seed germination. Obl...