Mechanisms Controlling Dormancy in the Arid Zone Grass Aristida contorta. I. Physiology and Mechanisms of Dormancy

1974 ◽  
Vol 22 (4) ◽  
pp. 635 ◽  
Author(s):  
JJ Mott
Keyword(s):  
Gas Exchange ◽  
Oxygen Uptake ◽  
High Temperatures ◽  
Arid Zone ◽  
Ambient Temperatures ◽  
Oxidizing Agents

Two dormancy mechanisms are evident in young A. contorta grain. One is an after-ripening requirement of the embryo, and can be satisfied by storage at ambient temperatures; the second is associated with the hull and requires prolonged periods of high temperatures before germination can take place. The dormancy imposed by the hull is not controlled by a leachable inhibitor, but germination can be stimulated by oxidizing agents or by the removal of small sections of the hull directly over the embryo. The oxygen uptake of dormant grain is very low, but non-dormant grain, or dormant grain with the hull removed, shows a much higher uptake. The possibility remains that there is a mechanical restriction of gas exchange by the hull, the hull of non-dormant grain being more permeable than that of dormant grain.

Seed Germination in Ruzizi Grass (Brachaaria ruziziensis Germain & Evrard)

1976 ◽  
Vol 24 (4) ◽  
pp. 437 ◽  
Author(s):  
C Renard ◽  
P Capelle
Keyword(s):  
Hydrogen Peroxide ◽  
Seed Germination ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Oxidizing Agents ◽  
Brachiaria Ruziziensis

Sowing is the most common way of establishing Brachiaria ruziziensis in pastures, but seed germi- nation is poor as a result of dormancy. The mechanism of dormancy is clearly located in the hull, for removing the hull or cutting at the base of the spikelet stimulates germination. No leachable inhibitor seems to be the cause of dormancy. However, the action of oxidizing agents such as hydrogen peroxide and the measurement of oxygen uptake by full or empty spikelets suggest that a restriction of gas exchange by the hull is responsible.

scholarly journals Effects of Cold Exposure on Oxygen Consumption, Ventilation and Interclavicular Air-Sac Gases in the Little Penguin(Eudyptula Minor)

1990 ◽  
Vol 154 (1) ◽  
pp. 397-405
Author(s):  
HEGE JOHANNESEN ◽  
STEWART C. NICOL
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Tidal Volume ◽  
Cold Exposure ◽  
Strong Correlation ◽  
Respiratory Frequency ◽  
Oxygen Extraction ◽  
Ambient Temperatures ◽  
Little Penguin

Oxygen consumption (VO2), tidal volume, respiratory frequency and the composition of the gas in the interclavicular air sac were measured in the little penguin Eudyptula minor (Forster) at ambient temperatures (Ta) of 5 and 20 °C. VO2 increased from 14.60 ml O2 kg−1 at 20°C to 18.29 ml O2 kg−1 min−1 at 5 °C. However, the elevated atVO2 the low Ta was not matched by a similar rise in total inspiratory ventilation (Vi). The ventilatory requirement (Vi/VO2) thus decreased from 0.5751 mmol−11 at 20°C to 0.4401 mmol−1 at 5°C. An increased gas exchange efficiency during cold exposure was also shown by the composition of the gas in the interclavicular air sac. PO2 decreased from 11.95 kPa at 20°C to 10.24kPa at 5°C, while the corresponding increase in PCO2 was from 6.61 to 7.50 kPa. Oxygen extraction, calculated from VO2, Vi and O2 content of the inspired air, increased from 24.60% at 20°C to 31.04% at 5°C. Oxygen extraction calculated from the O2 contents of inspired air and interclavicular air—sac gas was 38.73 % at 20°C and 47.18% at 5°C. The results confirm previous findings for the little penguin which showed a decrease in the ventilatory requirement with increasing oxygen uptake. However, the improved gas exchange efficiency during cold exposure and the strong correlation found between oxygen extraction and oxygen consumption have not been demonstrated previously for this species.

Pulmonary Gas Exchange and Oxygen Uptake During Exercise in Patients with Type 1 Diabetes Mellitus

1992 ◽  
Vol 9 (3) ◽  
pp. 252-257 ◽  
Author(s):  
Th. Wanke ◽  
D. Formanek ◽  
M. Auinger ◽  
H. Zwick ◽  
K. Irsigler
Keyword(s):  
Diabetes Mellitus ◽  
Type 1 Diabetes ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Type 1 Diabetes Mellitus ◽  
Pulmonary Gas Exchange

Early Development of Thermoregulatory Competence in Chickens: Responses of Heart Rate and Oxygen Uptake to Altered Ambient Temperatures

2004 ◽  
Vol 15 (3) ◽  
pp. 166-176 ◽  
Author(s):  
H. Tazawa ◽  
Y. Chiba ◽  
A.H. Khandoker ◽  
E.M. Dzialowski ◽  
W.W. Burggren
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Early Development ◽  
Ambient Temperatures

Effect of short-term exposure to high ambient temperatures on gas exchange and heat production in boars of different breeds

1998 ◽  
Vol 66 (2) ◽  
pp. 431-440 ◽  
Author(s):  
A.-H. Tauson ◽  
A. Chwalibog ◽  
J. Ludvigsen ◽  
K. Jakobsen ◽  
G. Thorbek
Keyword(s):  
Heat Stress ◽  
Gas Exchange ◽  
Heat Production ◽  
Live Weight ◽  
Mean Value ◽  
Short Term ◽  
Ambient Temperatures ◽  
Cooling Period ◽  
Basal Period ◽  
Short Term Exposure

AbstractThe effects of short-term exposure to high ambient temperatures on gas exchange, heat production (HE), respiration rate (RR) and rectal temperature were evaluated individually with boars of approximately 100 kg live weight. The boars were of different breeds with four of Yorkshire (YS), eight of Danish Landrace (DL), out of which three were found stress susceptible by the halothane test (DLH+), eight of Duroc (DR) and eight of Hampshire (HS) breeds. After 1 h rest in the respiration chamber at 17·0°C the gas exchange measurements started with al-h basal period at 17 °C, followed by 2h of heating during which temperature increased to 35·0 °C (period I) and then further to 39·7X1 (period II). Then cooling of the chamber started, and after 1 h (period III) temperature had decreased to 21·8°C, and after the 2nd h of cooling (period IV) temperature was 18·2 °C. The gas exchange was measured for each hour from 09.00 h (basal period) until 14.00 h (period IV). RR was recorded every 15 min. Rectal temperatures were measured when the animals were removed from the chamber. The gas exchange and HE increased slowly during period I but rapidly in period II, followed by decreasing values in the cooling periods. HS and DLH+ had considerably higher gas exchange and HE than other breeds in these two periods and the values remained high during period III. In period IV all breeds had gas exchange rates and HE below those of the basal period. RR increased slightly in period I and then a sharp increase followed during period II. Maximum RR was recorded in period III with an average of 183 breaths per min for all breeds. RR increased earlier and more steeply in HS and reached the highest mean value of 236 breaths per min. Four HS boars salivated heavily during heat stress and rectal temperatures of these animals were 39·7 °C when removed from the chamber compared with close to 39·0 °C for all other breeds. It was concluded that there were considerable breed differences in response to heat stress and that DLH+ and HS were more severely stressed than boars ofYS, DL and DR.

Change in the Properties of a Lead-acid Battery Depending on the Cycling Speed and the Ambient Temperature

2021 ◽  
Vol 105 (1) ◽  
pp. 119-134
Author(s):  
Jana Zimáková ◽  
Petr Baca ◽  
Martin Langer ◽  
Tomáš Binar
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Room Temperature ◽  
Lead Acid Battery ◽  
Ambient Temperatures ◽  
Lead Acid Batteries ◽  
Temperature Dependences ◽  
Cycling Speed ◽  
Lead Acid

This work deals with lead-acid batteries, their properties and individual types that are available on the market. The temperature dependences of the battery parameters at different ambient temperatures and at different discharging and charging modes are measured. 6 batteries are tested at different charging currents, which provides information about their behavior both during discharge and at the time of charging. During the experiments, testing is not only performed at room temperature, but the batteries are also exposed to high temperatures up to 75 °C.

scholarly journals Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers

1996 ◽  
Vol 81 (5) ◽  
pp. 1901-1907 ◽  
Author(s):  
Roland Favier ◽  
Esperanza Caceres ◽  
Laurent Guillon ◽  
Brigitte Sempore ◽  
Michel Sauvain ◽  
...  
Keyword(s):  
Heart Rate ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Metabolic Responses ◽  
Physiological Data ◽  
Respiratory Gas Exchange ◽  
Gum Chewing ◽  
Arterial Blood ◽  
Before And After ◽  
Exercise Induced

Favier, Roland, Esperanza Caceres, Laurent Guillon, Brigitte Sempore, Michel Sauvain, Harry Koubi, and Hilde Spielvogel. Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers. J. Appl. Physiol. 81(5): 1901–1907, 1996.—To determine the effects of acute coca use on the hormonal and metabolic responses to exercise, 12 healthy nonhabitual coca users were submitted twice to steady-state exercise (∼75% maximal O2 uptake). On one occasion, they were asked to chew 15 g of coca leaves 1 h before exercise, whereas on the other occasion, exercise was performed after 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, norepinephrine, insulin, glucagon, and metabolites (glucose, lactate, glycerol, and free fatty acids) were determined at rest before and after coca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (heart rate, mean arterial blood pressure, oxygen uptake, and respiratory gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significantly reduced insulin concentration. During exercise, the oxygen uptake, heart rate, and respiratory gas exchange ratio were significantly increased in the coca-chewing trial compared with the control (gum-chewing) test. The exercise-induced drop in plasma glucose and insulin was prevented by prior coca chewing. These results contrast with previous data obtained in chronic coca users who display during prolonged submaximal exercise an exaggerated plasma sympathetic response, an enhanced availability and utilization of fat (R. Favier, E. Caceres, H. Koubi, B. Sempore, M. Sauvain, and H. Spielvogel. J. Appl. Physiol. 80: 650–655, 1996). We conclude that, whereas coca chewing might affect glucose homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual users could enhance tolerance to exercise.

scholarly journals Silicon Photonic Micro-Transceivers for Beyond 5G Environments

2021 ◽  
Vol 11 (22) ◽  
pp. 10955
Author(s):  
Kazuhiko Kurata ◽  
Luca Giorgi ◽  
Fabio Cavaliere ◽  
Liam O’Faolain ◽  
Sebastian A. Schulz ◽  
...  
Keyword(s):  
Quantum Dot ◽  
High Temperatures ◽  
Low Cost ◽  
Laser System ◽  
Data Rate ◽  
Ambient Temperatures ◽  
Quantum Dot Laser ◽  
Silicon Photonic ◽  
Order Of Magnitude ◽  
And Performance

Here, we report on the design and performance of a silicon photonic micro-transceiver required to operate in 5G and 6G environments at high ambient temperatures above 105 °C. The four-channel “IOCore” micro-transceiver incorporates a 1310 nm quantum dot laser system and operates at a data rate of 25 Gbps and higher. The 5 × 5 mm micro-transceiver chip benefits from a multimode coupling interface for low-cost assembly and robust connectivity at high temperatures as well as an optical redundancy scheme, which increases reliability by over an order of magnitude.

Coordination between leaf, stem, and root hydraulics and gas exchange in three arid-zone angiosperms during severe drought and recovery

2018 ◽  
Vol 41 (12) ◽  
pp. 2869-2881 ◽  
Author(s):  
Danielle Creek ◽  
Chris J. Blackman ◽  
Timothy J. Brodribb ◽  
Brendan Choat ◽  
David T. Tissue
Keyword(s):  
Gas Exchange ◽  
Arid Zone ◽  
Severe Drought

Some Aspects of Gas Exchange in Tuna

1972 ◽  
Vol 56 (3) ◽  
pp. 809-823
Author(s):  
E. D. STEVENS
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Average Rate ◽  
Oxygen Removal ◽  
Skipjack Tuna ◽  
Partial Pressure Of Oxygen ◽  
Free Swimming ◽  
Flow Rates ◽  
Theoretical Predictions

1. Some aspects of gas exchange in restrained skipjack tuna were analysed. 2. The average rate at which water flowed over the gills was 2.81/min. kg. 3. The concentration of oxygen in water entering and leaving the gills was measured and used to calculate oxygen uptake (692 mg/h.kg) and utilization (0.71). 4. The drop in hydrostatic pressure as water flowed over the gills was 1.9 cm water and agrees favourably with theoretical predictions. 5. The partial pressure of oxygen was measured in blood afferent and efferent to the gills and used to calculate effectiveness of oxygen removal from the water (90%) and the transfer factor for oxygen (0.12 ml/min.kg.mmHg). 6. The average utilization measured in free-swimming tuna was 0.56. 7. The extraordinary ability of tuna to efficiently extract oxygen from the water at high gill water flow rates is discussed.

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