scholarly journals Assessment of the interaction of hyperbaric N2, CO2, and O2 on psychomotor performance in divers

2016 ◽  
Vol 121 (4) ◽  
pp. 953-964 ◽  
Author(s):  
J. J. Freiberger ◽  
B. J. Derrick ◽  
M. J. Natoli ◽  
I. Akushevich ◽  
E. A. Schinazi ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Cognitive Performance ◽  
Video Game ◽  
Ventilatory Response ◽  
Cognitive Tasks ◽  
Motor Tasks ◽  
Training Video ◽  
Factors Associated ◽  
Partial Pressures ◽  
Male Subjects

Diving narcosis results from the complex interaction of gases, activities, and environmental conditions. We hypothesized that these interactions could be separated into their component parts. Where previous studies have tested single cognitive tasks sequentially, we varied inspired partial pressures of CO2, N2, and O2 in immersed, exercising subjects while assessing multitasking performance with the Multi-Attribute Task Battery II (MATB-II) flight simulator. Cognitive performance was tested under 20 conditions of gas partial pressure and exercise in 42 male subjects meeting U.S. Navy age and fitness profiles. Inspired nitrogen (N2) and oxygen (O2) partial pressures were 0, 4.5, and 5.6 ATA and 0.21, 1.0, and 1.22 ATA, respectively, at rest and during 100-W immersed exercise with and without 0.075-ATA CO2. Linear regression modeled the association of gas partial pressure with task performance while controlling for exercise, hypercapnic ventilatory response, dive training, video game frequency, and age. Subjects served as their own controls. Impairment of memory, attention, and planning, but not motor tasks, was associated with N2 partial pressures >4.5 ATA. Sea level O2 at 0.925 ATA partially rescued motor and memory reaction time impaired by 0.075-ATA CO2; however, at hyperbaric pressures an unexpectedly strong interaction between CO2, N2, and exercise caused incapacitating narcosis with amnesia, which was augmented by O2. Perception of narcosis was not correlated with actual scores. The relative contributions of factors associated with diving narcosis will be useful to predict the effects of gas mixtures and exercise conditions on the cognitive performance of divers. The O2 effects are consistent with O2 narcosis or enhanced O2 toxicity.

The Ventilatory Response to Hypoxia Below the Carbon Dioxide Threshold

1997 ◽  
Vol 22 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Theodore Rapanos ◽  
James Duffin
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Ventilatory Response ◽  
Pressure Threshold ◽  
Partial Pressures ◽  
Progressive Hypoxia ◽  
End Tidal ◽  
Peripheral Chemoreflex ◽  
Ventilatory Response To Hypoxia ◽  
Lower Carbon

The ventilatory response to acute progressive hypoxia below the carbon dioxide threshold using rebreathing was investigated. Nine subjects rebreathed after 5 min of hyperventilation to lower carbon dioxide stores. The rebreathing bag initially contained enough carbon dioxide to equilibrate alveolar and arterial partial pressures of carbon dioxide to the lowered mixed venous partial pressure (≈ 30 mmHg), and enough oxygen to establish a chosen end-tidal partial pressure (50-70 mmHg), within one circulation time. During rebreathing, end-tidal partial pressure of carbon dioxide increased while end-tidal partial pressure of oxygen fell. Ventilation increased linearly with end-tidal carbon dioxide above a mean end-tidal partial pressure threshold of 39 ± 2.7 mmHg. Below this peripheral-chemoreflex threshold, ventilation did not increase, despite a progressive fall in end-tidal oxygen partial pressure to a mean of 37 ± 4.1 mmHg. In Conclusion, hypoxia does not stimulate ventilation when carbon dioxide is below its peripheral-chemoreflex threshold. Key words: peripheral chemoreflex, rebreathing technique, hyperventilation

scholarly journals Storage and Handling Effects on a CO2-related Internal Browning Disorder of `Braeburn' Apples

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 719-722 ◽  
Author(s):  
H. John Elgar ◽  
Douglas M. Burmeister ◽  
Christopher B. Watkins
Keyword(s):  
Partial Pressure ◽  
Controlled Atmosphere ◽  
Factors Associated ◽  
Partial Pressures ◽  
Storage Atmosphere ◽  
Internal Browning

`Braeburn' apple (Malus ×domestica Borkh.) fruit can be susceptible to the development of an internal disorder called “`Braeburn' browning disorder” (BBD). Factors associated with development of this disorder were investigated. Susceptibility to injury was greater in fruit exposed to 2 or 5 kPa CO2 than to 0 kPa CO2 during storage. Susceptibility also increased with decreasing O2 partial pressure in the range of 5 to 1 kPa in the storage atmosphere. However, fruit stored in 1 kPa O2 remained firmer than those stored at higher partial pressures, regardless of CO2 level. BBD appeared to develop during the first 2 weeks of storage, and delays in air at 0 °C prior to controlled-atmosphere (CA) storage decreased incidence and severity of the disorder. The incidence of BBD was also reduced when the time to establish CA conditions was prolonged. We recommend that `Braeburn' apples be stored under CA conditions of ≤1.0 kPa CO2 and 3.0 kPa O2. Delayed application of CA for 2 weeks after fruit enter the coldstorage may also reduce development of BBD.

Effects of Fatigue on Cognitive Performance in Long-Duration Simulated Flight Missions

2020 ◽  
Vol 10 (2) ◽  
pp. 82-93
Author(s):  
Eduardo Rosa ◽  
Ola Eiken ◽  
Mikael Grönkvist ◽  
Roger Kölegård ◽  
Nicklas Dahlström ◽  
...  
Keyword(s):  
Executive Functions ◽  
Task Performance ◽  
Cognitive Performance ◽  
Cognitive Tasks ◽  
Fatigue Index ◽  
Fighter Aircraft ◽  
Long Duration ◽  
Metacognitive Accuracy

Abstract. Fighter pilots may be exposed to extended flight missions. Consequently, there is increasing concern about fatigue. We investigated the effects of fatigue and cognitive performance in a simulated 11-hr mission in the 39 Gripen fighter aircraft. Five cognitive tasks were used to assess cognitive performance. Fatigue was measured with the Samn–Perelli Fatigue Index. Results showed that performance in the non-executive task degraded after approximately 7 hr. Fatigue ratings showed a matching trend to the performance in this task. Performance in tasks taxing executive functions did not decline. We interpreted that fatigue can be overridden by increased attentional effort for executive tasks but not for non-executive components of cognition. Participants underestimated their performance and metacognitive accuracy was not influenced by fatigue.

Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone

2014 ◽  
Vol 789 ◽  
pp. 466-470
Author(s):  
Qing Hao Shi ◽  
Bing Ying Wang ◽  
Bin Zhao
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Composite Coating ◽  
Corrosion Test ◽  
Electrochemical Impedance ◽  
Failure Process ◽  
Corrosion Property ◽  
Corrosion Mechanism ◽  
Partial Pressures ◽  
High Temperature High Pressure

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

Controlled partial melting during isobaric and isothermal processing of dipcoated Bi-2212/Ag tapes

1998 ◽  
Vol 13 (12) ◽  
pp. 3580-3586 ◽  
Author(s):  
A. L. Crossley ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Phase Diagram ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Melting ◽  
Coulometric Titration ◽  
Processing Route ◽  
Optimum Processing ◽  
Partial Pressures ◽  
Titration Technique

A detailed study has been made of the control and optimization of partial melting of dipcoated Bi2Sr2Ca1Cu2O8+δAg0.1 (Bi-2212) tapes using reduced oxygen partial pressures. A coulometric titration technique has been employed to vary the oxygen partial pressure in a region of the phase diagram corresponding to binary melting, and the amount of partial melting has been quantified. Using this information, tapes have been processed using both isothermal and isobaric techniques. An optimum processing route was determined which combined isothermal and isobaric processes. Highly aligned material at the point of optimum melting was obtained.

Effects of acetone in heparin on the multiple inert gas elimination technique

1985 ◽  
Vol 58 (4) ◽  
pp. 1143-1147 ◽  
Author(s):  
F. L. Powell ◽  
F. A. Lopez ◽  
P. D. Wagner
Keyword(s):  
Partial Pressure ◽  
Dead Space ◽  
Room Temperature ◽  
Inert Gas ◽  
Published Data ◽  
Physiological Mechanisms ◽  
Heparinized Saline ◽  
Partial Pressures ◽  
Ventilation Perfusion Ratio ◽  
Mixed Venous

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.

scholarly journals Factors associated with cognitive performance in elderly caregivers

2018 ◽  
Vol 76 (10) ◽  
pp. 685-691 ◽  
Author(s):  
Sofia Cristina Iost Pavarini ◽  
Allan Gustavo Brigola ◽  
Ana Carolina Ottaviani ◽  
Bruna Moretti Luchesi ◽  
Érica Nestor Souza ◽  
...  
Keyword(s):  
Cognitive Performance ◽  
Verbal Fluency ◽  
Family Income ◽  
Healthcare Services ◽  
Cognitive Domains ◽  
Factors Associated ◽  
Dependent Variables ◽  
Attention Memory ◽  
Elderly Caregivers ◽  
Addenbrooke’S Cognitive Examination

Abstract Objectives: To explore the socioeconomic, demographic and psychosocial factors associated with cognitive performance in elderly caregivers from Brazil. Methods: We evaluated 351 Brazilian elderly caregivers attending primary healthcare services regarding sociodemographic and care variables. Addenbrooke's Cognitive Examination-Revised (ACE-R) domains of orientation/attention, memory, verbal fluency, language and visuospatial were used as dependent variables in the Tobit model. Results: Literacy and family income were positively associated with all ACE-R domains. Age, gender, time of care (days/week) were negatively associated with some cognitive domains. Moreover, receiving emotional help and the level of hope were positively associated with specific domains. Discussion: The results may be useful for planning interventions aimed at elderly caregivers in order to prevent deficits in the different cognitive domains.

Childhood Chronic Illness and Visual Motor Perceptual Development

1969 ◽  
Vol 36 (1) ◽  
pp. 39-42 ◽  
Author(s):  
Clyde W. Shepherd
Keyword(s):  
Chronic Illness ◽  
Early Reading ◽  
Reading Difficulty ◽  
Second Grade ◽  
Motor Tasks ◽  
Perceptual Development ◽  
Factors Associated ◽  
Childhood Chronic Illness ◽  
History Of ◽  
Visual Motor

The visual motor perceptual development of 47 second grade children having a history of chronic illness was investigated. Relationships between factors associated with the chronic illness and visual perceptual development are cited and discussed. The results suggest that children having a history of chronic illness perform significantly below expected levels on visual motor tasks and experience early reading difficulty.

scholarly journals Structural, optical and electrical properties of reactively sputtered CrxNy films: Nitrogen influence on the phase formation

2017 ◽  
Vol 11 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Mirjana Novakovic ◽  
Maja Popovic ◽  
Zlatko Rakocevic ◽  
Natasa Bibic
Keyword(s):  
Partial Pressure ◽  
Phase Formation ◽  
Rutherford Backscattering Spectrometry ◽  
Deposition Process ◽  
Columnar Structure ◽  
Nitrogen Partial Pressure ◽  
Tem Analysis ◽  
Dense Microstructure ◽  
Transmission Electron ◽  
Partial Pressures

The properties of various CrxNy films grown by direct current (DC) reactive sputtering process with different values of nitrogen partial pressures (0, 2?10-4, 3.5?10-4 and 5?10-4 mbar) were studied. The structural analysis of the samples was performed by using X-ray diffraction and transmission electron microscopy (TEM), while an elemental analysis was realized by means of Rutherford backscattering spectrometry. By varying nitrogen partial pressure the pure Cr layer, mixture of Cr, Cr2N and CrN phases, or single-phase CrN was produced. TEM analysis showed that at pN2 = 2?10-4 mbar the layer has dense microstructure. On the other hand, the layer deposited at the highest nitrogen partial pressure exhibits pronounced columnar structure. The optical properties of CrxNy films were evaluated from spectroscopic ellipsometry data by the Drude or combined Drude and Tauc-Lorentz model. It was found that both refractive index and extinction coefficient are strongly dependent on the dominant phase formation (Cr, Cr2N, CrN) during the deposition process. Finally, the electrical studies indicated the metallic character of Cr2N phase and semiconducting behaviour of CrN.

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