This study investigates the role of nitrogen (N2) in transmucosal gas exchange of the middle ear (ME). We used an experimental rat model to measure gas volume variations in the ME cavity at constant pressure. We disturbed the steady-state gas composition with either air or N2 to measure resulting changes in volume at ambient pressure. Changes in gas volume over time could be characterized by th...

We calculate the stopping power for heavy-ion diclusters moving in a strongly coupled two-dimensional electron gas system by using the local field corrected dielectric function at finite temperature. We obtain a parameterized local field correction factor based on a relation between the thermal compressibility and exchange-correlation energy in two-dimension. The interpolated parameter is deriv...

Gas exchange following experimental pulmonary thromboembolization was studied with an inert gas elimination technique in 17 dogs. Pulmonary arterial, systemic arterial, and expired gas concentrations of six gases infused intravenously were measured before embolization and 5,10,15,30,60, and 120 minutes after embolization. Distributions of ventilation-perfusion (VA/Q) ratios were derived from th...

Pulmonary CO diffusion capacity ( D L C O ) , lung volume (VL), oxygen uptake (Vo ) and pulmonary blood flow (QL) were measured simultaneously in the loggerhead sea turtle Caretta caretta (Linnaeus) (8—11 kg) using a gas rebreathing technique (syringe pump ventilation). Calculated D L C O and Vo values in the loggerhead turtle are approximately twice those of non-varanid reptiles and about 25 %...

The effect of thoracentesis on pulmonary gas exchange was studied in 33 patients with unilateral pleural effusions of various causes. Arterial blood gases were measured before thoracentesis and at 20 minutes, two hours, and 24 hours after the procedure. In 13 patients alveolar arterial oxygen gradient (PA-ao2), physiological dead space:tidal volume ratio (VD/VT), physiological shunt, and "anato...

The red-colored chlorophyte Chlamydomonas nivalis is commonly found in summer snowfields. We used a modified Li-Cor gas-exchange system to investigate surface gas-exchange characteristics of snow colonized by this alga, finding rates of CO(2) uptake up to 0.3 micromol.m(-2).s(-1) in dense algal blooms. Experiments varying the irradiance resulted in light curves that resembled those of the leave...

Fluorine (F) stands out for its phytotoxic potential, because it accumulates in plants, changes enzymes activity, reduces chlorophyll content and, consequently, affects growth and yield of crop plants. An experiment was conducted to evaluate the effects of F on leaf gas exchange in coffee and sweet orange plants, compared to sensitive (gladiolus) and tolerant (ryegrass) reference species. Plant...

The lungs and heart are irrevocably linked in their oxygen and CO2 transport functions. Functional impairment of the lungs often affects heart function, and functional impairment of the heart often affects lung function. In patients with chronic congestive heart failure (CHF), exertional dyspnea is a common symptom, and ventilatory effort is increased at a given exercise workload despite normal...

In cellular, tissue-level or whole organ bioreactors, the level of dissolved oxygen is one of the most important factors requiring control. Hypoxic environments may lead to cellular apoptosis, while hyperoxic environments may lead to cellular damage or dedifferentiation, both resulting in loss of overall tissue function. This manuscript describes the creation, characterization and validation of...

Stomatal conductance (gs) and transpiration (E) are often positively correlated with the hydraulic conductance of the soil–leaf continuum (ks–l). Interaction between gs and ks–l helps regulate water potential (9) of leaves. When soil and plant 9 decreases during water stress, ks–l decreases. A well-documented cause of the decrease in ks–l is xylem cavitation. The interaction between k and 9 in ...