Mean alveolar gases and alveolar-arterial gradients in pulmonary patients

1979 ◽  
Vol 46 (3) ◽  
pp. 534-540 ◽  
Author(s):  
U. C. Luft ◽  
J. A. Loeppky ◽  
E. M. Mostyn
Keyword(s):  
Steady State ◽  
Mass Spectrometer ◽  
Dead Space ◽  
Best Approximation ◽  
The Other ◽  
Mean Values ◽  
The Best Approximation ◽  
The Mean ◽  
End Tidal ◽  
Better Than

In view of uncertainties about the best way to estimate mean alveolar gases in patients with ventilation-perfusion inequalities, three different methods were evaluated on 54 patients. 1) O2 and CO2 were recorded by mass spectrometer on an O2 (x)-CO2 (y) diagram. The coordinates at the intersect of the expiratory record with the mixed expired R line (RE) ives the mean alveolar values (PAo2 and PAco2. 2)pa'co2 was calculated with the Bohr equation using a predicted anatomic dead space and PA'o2 was derived with the alveolar equation. 3) End-tidal (ET) P02 were averaged over 1 min at rest in steady state. Mean RET calculated from 3 was identical with RE. Mean values for PAco2, PA'CO2. and PETco2 differed by less that 1 Torr, but the variance was least with the end-tidal method. There was a highly significant correlation between delta aAPco2 using PETco2 and VD/VT, better than with either of the other methods. The end-tidal measurement appears to give the best approximation of mean alveolar gas in pulmonary patients.

The Race for Online Reputation: Implications for Platforms, Firms, and Consumers

2021 ◽  
Author(s):  
Mingwen Yang ◽  
Zhiqiang (Eric) Zheng ◽  
Vijay Mookerjee
Keyword(s):  
Adverse Event ◽  
Marketing Mix ◽  
Digital Economy ◽  
The Other ◽  
The Mean ◽  
The Absolute ◽  
The Cost ◽  
Online Reputation ◽  
Better Than

Online reputation has become a key marketing-mix variable in the digital economy. Our study helps managers decide on the effort they should use to manage online reputation. We consider an online reputation race in which it is important not just to manage the absolute reputation, but also the relative rating. That is, to stay ahead, a firm should try to have ratings that are better than those of its competitors. Our findings are particularly significant for platform owners (such as Expedia or Yelp) to strategically grow their base of participating firms: growing the middle of the market (firms with average ratings) is the best option considering the goals of the platform and the other stakeholders, namely incumbents and consumers. For firms, we find that they should increase their effort when the mean market rating increases. Another key insight for firms is that, sometimes, adversity can come disguised as an opportunity. When an adverse event strikes the industry (such as a reduction in sales margin or an increase in the cost of effort), a firm’s profit can increase if it can manage this event better than its competitors.

Physiological and biophysical limits to work in the heat for clothed men and women

1978 ◽  
Vol 44 (6) ◽  
pp. 918-925 ◽  
Author(s):  
E. Kamon ◽  
B. Avellini ◽  
J. Krajewski
Keyword(s):  
Steady State ◽  
Vapor Pressure ◽  
Physiological Responses ◽  
Men And Women ◽  
Mean Values ◽  
Air Temperatures ◽  
Significant Difference ◽  
The Mean ◽  
Evaporative Heat Transfer ◽  
The One

Heat-acclimated, lightly clothed men and women (four of each) walked on a treadmill at 25% and 43% VO2 max, respectively, (M =194 W.m-2), under seven air temperatures (Ta) ranging from 36 to 52 degrees C. Each experiment involved 1 h of fixed and a 2nd h of progressively increasing ambient vapor pressure (Pa). The relative steady state of rectal temperature (Tre), mean skin temperature (Tsk), and heart rate (HR) reached in the 1st h were forced upward during the 2nd h by the rising Pa. The critical air vapor pressure (Pcrit) was identified by the Tre point of inflection for each Ta. One man did not fully reach steady state, but inflection could be determined for his physiological responses. The mean values of all points of inflection were calculated for Tre, Tsk, and HR. Significant sex difference in HR was found only by excluding the results of the one man. Tre and Tsk showed no significant difference between men and women. The coefficient for evaporative heat transfer (he), which could be derived using the Pcrit for the low Ta range, was 14.5 +/- 2.2 W.m-1 Torr-1.

Effect of grain or silage supplementation on meat quality attributes of cryptorchid lambs grazing lucerne or annual grass-clover pastures

1995 ◽  
Vol 35 (4) ◽  
pp. 461 ◽  
Author(s):  
DL Hopkins ◽  
PJ Holst ◽  
DG Hall
Keyword(s):  
Meat Quality ◽  
Shear Force ◽  
The Other ◽  
Carcass Weight ◽  
Annual Grass ◽  
Eye Muscle ◽  
Mean Values ◽  
Significant Difference ◽  
The Mean ◽  
Ad Libitum

Objective and subjective tests for quality were performed on the meat from 40 cryptorchid second-cross lambs fed lucerne only (L; n = 8), lucerne plus an oat grain supplement ad libitum (LO; n = lo), lucerne plus wilted lucerne silage ad libitum (LS; n = 11), or an oat-lupin grain (3:1) supplement at 90% of ad libitum while grazing dry summer annual pasture (OL; n = 11). All carcasses complied with the Elite lamb specification of weight >22 kg and GR measurement 6-15 mm. There was no significant difference between groups for hot carcass weight, the mean (� s.e) values being 25.1 0.43, 25.2 � 0.36,25.2 � 0.38, and 25.3 � 0.36 kg for L, LS, LO, and OL groups, respectively. When the GR and fat depth over the eye muscle at the 12th rib were adjusted to a common carcass weight of 25.2 kg there was no significant difference between groups. There was no significant difference between groups for pH, or the colour values a*, b*, and L* of the M. longissimus thoracis et lumborum (a* is relative redness, b* relative yellowness, and L* relative lightness). The shear force values for the loin muscle were significantly (P<0.05) greater for lambs from group OL than for those from group LO. Cooking loss for the loin muscle was significantly (P<0.05) greater for OL lambs than all other groups. A comparison of the mean values for aroma and flavour showed the lambs from group OL produced meat that was considered significantly (P<0.05) less desirable for these characteristics, with other groups being similar. Meat from OL-fed lambs was considered oilier and less meaty than meat from lambs fed the other diets. There was a significant (P<0.05) difference in absolute scores between panellists, but their ranking was not affected and there was no panellist x sample interaction. Because many producers use grain supplements such as oats and lupins for finishing lambs on dry forages, further study is recommended that focuses on the interaction between supplement and the base forage.

Arterial-alveolar CO2 equilibration in exercising dogs during prolonged rebreathing

1985 ◽  
Vol 58 (5) ◽  
pp. 1654-1658 ◽  
Author(s):  
J. A. Loeppky ◽  
P. Scotto ◽  
H. Rieke ◽  
M. Meyer ◽  
J. Piiper
Keyword(s):  
Steady State ◽  
Carotid Artery ◽  
Average Rate ◽  
Blood Gas ◽  
O2 Uptake ◽  
Full Agreement ◽  
Arterial Blood ◽  
Simultaneous Measurements ◽  
The Mean ◽  
End Tidal

Arterial-alveolar equilibration of CO2 during exercise was studied by normoxic CO2 rebreathing in six dogs prepared with a chronic tracheostomy and exteriorized carotid loop and trained to run on a treadmill. In 153 simultaneous measurements of PCO2 in arterial blood (PaCO2) and end-tidal gas (PE'CO2) obtained in 46 rebreathing periods at three levels of mild-to-moderate steady-state exercise, the mean PCO2 difference (PaCO2-PE'CO2) was -1.0 +/- 1.0 (SD) Torr and was not related to O2 uptake or to the level of PaCO2 (30–68 Torr). The small negative PaCO2-PE'CO2 is attributed to the lung-to-carotid artery transit time delay which must be taken into account when both PaCO2 and PE'CO2 are continuously rising during rebreathing (average rate 0.22 Torr/s). Assuming that blood-gas equilibrium for CO2 was complete, a lung-to-carotid artery circulation time of 4.6 s accounts for the observed uncorrected PaCO2-PE'CO2 of -1.0 Torr. The results are interpreted to indicate that in rebreathing equilibrium PCO2 in arterial blood and alveolar gas are essentially identical. This conclusion is at variance with previous studies in exercising humans during rebreathing but is in full agreement with our recent findings in resting dogs.

An assessment of nasal functions in control of breathing

1988 ◽  
Vol 65 (4) ◽  
pp. 1520-1524 ◽  
Author(s):  
Y. Tanaka ◽  
T. Morikawa ◽  
Y. Honda
Keyword(s):  
Steady State ◽  
Dead Space ◽  
Airway Resistance ◽  
Breathing Pattern ◽  
Ventilatory Response ◽  
Control Of Breathing ◽  
Mouth Breathing ◽  
Occlusion Pressure ◽  
Ventilatory Responses ◽  
End Tidal

Breathing pattern and steady-state CO2 ventilatory response during mouth breathing were compared with those during nose breathing in nine healthy adults. In addition, the effect of warming and humidification of the inspired air on the ventilatory response was observed during breathing through a mouthpiece. We found the following. 1) Dead space and airway resistance were significantly greater during nose than during mouth breathing. 2) The slope of CO2 ventilatory responses did not differ appreciably during the two types of breathing, but CO2 occlusion pressure response was significantly enhanced during nose breathing. 3) Inhalation of warm and humid air through a mouthpiece significantly depressed CO2 ventilation and occlusion pressure responses. These results fit our observation that end-tidal PCO2 was significantly higher during nose than during mouth breathing. It is suggested that a loss of nasal functions, such as during nasal obstruction, may result in lowering of CO2, fostering apneic spells during sleep.

scholarly journals Some Physiological Factors Affecting the Binding of Cortisol by Human Plasma Proteins

1977 ◽  
Vol 14 (1-6) ◽  
pp. 35-38 ◽  
Author(s):  
J. D. Few ◽  
J. R. Haspineall
Keyword(s):  
Steady State ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Gel Filtration ◽  
Physiological Factors ◽  
Mean Values ◽  
Factors Affecting ◽  
Free Cortisol ◽  
The Mean

Steady-state gel filtration has been used to study the binding of cortisol to human plasma proteins in vitro. Raising the temperature from 37°C to 41°C results in the mean proportion of free (non-protein-bound) cortisol rising approximately from 7% to 11%. Addition of cortisol to plasma ≡ 275 nmol/l) also increased the proportion of free cortisol by approximately 50%. Cortisone is less strongly bound to plasma proteins than cortisol. The mean values (±S.D.) for five samples were free cortisol 8.4 ± 1.1% and free cortisone 26.0±3.8%.

The analysis of temperature fluctuations by pulse-counting techniques

1959 ◽  
Vol 6 (2) ◽  
pp. 261-271 ◽  
Author(s):  
A. A. Townsend
Keyword(s):  
Time Derivative ◽  
Temperature Fluctuations ◽  
Mean Value ◽  
Time Intervals ◽  
Mean Values ◽  
Average Value ◽  
Electrical Pulses ◽  
The Mean ◽  
The Stability ◽  
Better Than

To determine experimentally the mean value of a randomly fluctuating quantity, it may be necessary to measure the average value over a considerable interval of time. This problem arose in a recent study of the temperature fluctuations over a heated horizontal plate, and a system was used that depended on the counting of electrical pulses generated at a rate proportional to the quantity being measured. The advantage of this technique is that mean values may be measured over time intervals of almost unlimited length with little added difficulty for the experimenter. Circuits are described which measure: (a) the mean square of a fluctuating quantity and of its time-derivative, (b) the statistical distribution of the fluctuations, (c) the mean frequency of the fluctuation assuming a particular value, and (d) the mean product of two fluctuating quantities. Over the range of use, the stability and linearity of the calibrations is better than 1%, more than sufficient for work on natural convection. In its present form, the equipment responds uniformly to all frequencies below 100 c/s, but it would not be difficult to extend this range of response to higher frequencies.

scholarly journals Changes in selected physicochemical parameters of breast muscles of geese from Polish conservation flocks depending on duration of the post slaughter period

2008 ◽  
Vol 51 (3) ◽  
pp. 255-265 ◽  
Author(s):  
A. Okruszek ◽  
J. Książkiewicz ◽  
J. Wołoszyn ◽  
G. Haraf ◽  
A. Orkusz ◽  
...  
Keyword(s):  
Genetic Resources ◽  
Physicochemical Parameters ◽  
Ph Value ◽  
The Other ◽  
Mean Values ◽  
Qualitative Traits ◽  
Ph Values ◽  
Colour Parameters ◽  
The Mean

Abstract. In four Polish conservative flocks of Suwałki (Su), Kartuzy (Ka), Kielce (Ki) and Subcarpathian (Sb) geese, registered by FAO as domestic genetic resources the mean values of qualitative traits of breast muscles (pH15', pH30', pH45', pH24h; colour parameters: L*15', L*30', L*45', L24h, a*15', a*30', a*45', a*24h, b*15', b*30', b*45', b*24h and conductivity: EC45', EC3h, EC24h) were determined. The experimental flocks showed significant variations in the investigated parameters. The Kartuzy goose breast muscles were characterized by higher values of pH15' (6.74), pH30' (6.62), pH45' (6.56) and b*15' parameter (0.80) in comparison with the remaining flocks. Moreover, these muscles had the lowest pH24h (5.65) and values of L* parameter (L*15', L*30', L*45' and L*24h) and EC45' (3.23 mS/cm). The pH value and L* and a* parameters (except L*24h and a*24h) of the analysed flocks were decreasing, and conductivity increasing together with the time post slaughter, and the rate of changes depended on the birds’ origin. Greater differences between pH values, measured 15 min and 24 h after slaughter were stated in breast muscles from Ka (1.09) and Su (0.90) geese than from the other two flocks investigated (Ki – 0.74; Sb – 0.58). The highest increase in conductivity (from EC45' to EC24h) was affirmed in Ka and Ki muscles (3.84 mS/cm) and the lowest in breast muscles of Sb geese (2.72 mS/cm).

End-tidal CO2 response to low levels of inspired CO2 in awake beagle dogs

1980 ◽  
Vol 48 (6) ◽  
pp. 1077-1082 ◽  
Author(s):  
P. Reischl ◽  
D. M. Stavert ◽  
S. M. Lewis ◽  
L. C. Murdock ◽  
B. J. O'Loughlin
Keyword(s):  
Steady State ◽  
Dead Space ◽  
Resolving Power ◽  
Beagle Dogs ◽  
Co2 Response ◽  
Arterial Pco2 ◽  
Control Of Ventilation ◽  
Low Levels ◽  
End Tidal ◽  
End Tidal Co2

The steady-state end-tidal CO2 tension (PCO2) was examined during control and 1% CO2 inhalation periods in awake beagle dogs with an intact airway breathing through a low dead-space respiratory mask. A total of eight experiments were performed in four dogs, comprising 31 control observations and 23 CO2 inhalation observations. The 1% inhaled CO2 produced a significant increase in the steady-state end-tidal PCO2 comparable to the expected 1 Torr predicted from conventional CO2 control of ventilation. We conclude that 1% inhaled CO2 results in a hypercapnia. Any protocol that is to resolve the question of whether mechanisms are acting during low levels of inhaled CO2 such that ventilation increases without any change in arterial PCO2 must have sufficient resolving power to discriminate changes in gas tension in magnitude predicted from conventional (i.e., arterial PCO2) control of ventilation.

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