SOME REACTIONS OF MUSCOID DIPTERA TO CHANGES IN ATMOSPHERIC PRESSURE

1946 ◽  
Vol 24d (4) ◽  
pp. 105-117 ◽  
Author(s):  
W. G. Wellington
Keyword(s):  
Atmospheric Pressure ◽  
Laboratory Experiments ◽  
Low Pressure ◽  
Pressure Waves ◽  
Pressure Changes

Laboratory experiments are described that demonstrate that the antennal aristae of muscoid Diptera are sensitive to slight fluctuations in pressure, acting as external baroreceptors. Further experiments show that the increase in activity exhibited by flies at low pressure is of a kinetic nature, lacking any directional element, while the reaction of flies to manually-produced pressure waves that vibrate the aristae is tactic in a baronegative sense. It is suggested that the erratic prethunderstorm flight of muscoid Diptera results largely from such a baronegative response to localized pressure changes. This suggestion is based on laboratory observations of the reactions of flies under simulated storm pressure patterns.

THE EFFECTS OF VARIATIONS IN ATMOSPHERIC PRESSURE UPON INSECTS

1946 ◽  
Vol 24d (2) ◽  
pp. 51-70 ◽  
Author(s):  
W. G. Wellington
Keyword(s):  
Atmospheric Pressure ◽  
Laboratory Experiments ◽  
Positive Influence ◽  
The Other ◽  
Direct Influence ◽  
Reduced Pressure ◽  
Fluctuating Pressure ◽  
Pressure Changes ◽  
Increased Pressure

This paper constitutes a review and an analysis of the available literature on the effects of pressure changes upon insects. The variations of atmospheric pressure that occur are classified briefly, but the effects of pressure changes upon insects are considered from the standpoint of the reactions of insects to extremely low pressure, extremely high pressure, and slight variations in pressure. It is concluded that extreme changes of pressure exert no direct influence upon insects. On the other hand, there is evidence that slightly reduced pressure increases the rates of the development and of the various activities of insects, while slightly increased pressure does not appear to have any positive influence on these processes. A discussion of the possible role of chordotonal organs in the observed responses of some insects to fluctuating pressure is included, and some laboratory experiments are suggested that might aid in quantitative determinations of the effects of varying atmospheric pressure upon insects.

Atmospheric pressure changes in the Arctic from 1801 to 1920

2012 ◽  
Vol 33 (7) ◽  
pp. 1730-1760 ◽  
Author(s):  
Rajmund Przybylak ◽  
Przemysław Wyszyński ◽  
Zsuzsanna Vízi ◽  
Joanna Jankowska
Keyword(s):  
Atmospheric Pressure ◽  
The Arctic ◽  
Pressure Changes

scholarly journals Comparison of bacterial microleakage of three bioactive endodontic sealers in simulated underwater diving and aviation conditions

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mehdi Dastorani ◽  
Behnam Malekpour ◽  
Mohsen AminSobhani ◽  
Mohammadsadegh Alemrajabi ◽  
Arezoo Mahdian ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Mineral Trioxide Aggregate ◽  
In Vitro Study ◽  
Chi Square ◽  
Custom Made ◽  
Single Cone ◽  
Registration Number ◽  
Chi Square Test ◽  
Pressure Changes

Abstract Background Bacterial microleakage is an important cause of apical periodontitis and endodontic treatment failure. This study aimed to assess the bacterial microleakage of nano-mineral trioxide aggregate (nano-MTA) as a sealer, Endoseal MTA, and GuttaFlow Bioseal sealers in atmospheric pressure, and simulated underwater diving and aviation conditions. Methods In this in vitro, experimental study, 180 extracted single-rooted teeth were cleaned and shaped, and were then randomly divided into three groups for single-cone obturation using Endoseal MTA, GuttaFlow Bioseal, or nano-MTA as a sealer. Each group was then randomly divided into three subgroups, and subjected to ambient atmospheric pressure, 2 atm pressure (to simulate underwater diving), and 0.5 atm pressure (to simulate aviation) using a custom-made pressure chamber. The teeth then underwent microbial leakage test using Streptococcus mutans (S. mutans), and the percentage of samples showing microleakage was recorded for up to 1 month, and analyzed using the Chi-square test. Results The three sealer groups were significantly different regarding bacterial microleakage (P < 0.05). The nano-MTA group showed significantly higher microleakage after 15 days than the other two groups (P = 0.006). The effect of pressure on bacterial microleakage was not significant in any sealer group (P > 0.05). Conclusion Within the limitations of this in vitro study, it may be concluded that single-cone obturation technique using nano-MTA as a sealer results in lower resistance to bacterial microleakage compared with the use of GuttaFlow Bioseal, and Endoseal MTA. Pressure changes in simulated underwater diving and aviation conditions had no significant effect on bacterial microleakage. Trial Registration Number This is not a human subject research.

The effect of spacecraft descent engine plumes on spore transfer to planetary surfaces: Phoenix as a test case

2011 ◽  
Vol 10 (4) ◽  
pp. 335-340 ◽  
Author(s):  
J.R. Marshall ◽  
R.L. Mancinelli
Keyword(s):  
Atmospheric Pressure ◽  
Laboratory Experiments ◽  
Particle Impact ◽  
Test Case ◽  
Surrounding Area ◽  
Planetary Protection ◽  
Engine Thrust ◽  
Exhaust Plumes ◽  
Microbial Contaminants ◽  
Different Parts

AbstractLaboratory experiments were conducted to determine the effect of descent-engine plumes on the scouring of surface (microbial) contaminants from a spacecraft. A simulated touchdown of a half-scale lander engine and deck configuration was conducted at Mars atmospheric pressure in the NASA Ames Planetary Aeolian Laboratory. Low-density particles were used for the soil simulant to emulate the lower Martian gravity. The underside of the model had small witness plates with controlled microbial surface populations and particle impact detectors. For both steady-state engine thrust (Viking) and pulsed engine thrust (Phoenix), the exhaust plumes from the engines violently excavated the soil and produced particle-laden eddies beneath the lander that sandblasted the lander underside. The result was nearly complete erosion of microbial contaminants from the spacecraft model with their subsequent deposition in the surrounding area. It is concluded that different planetary protection cleanliness levels for different parts of a spacecraft do not necessarily prevent soil contamination because these cleaning strategies evolved without consideration of the effects of the descent engine plumes.

scholarly journals Atmospheric Pressure Changes

Nature ◽  
1946 ◽  
Vol 158 (4025) ◽  
pp. 914-914
Author(s):  
C. H. B. PRIESTLEY
Keyword(s):  
Atmospheric Pressure ◽  
Pressure Changes

scholarly journals Experimental study on the effect of spray cone angle on the characteristics of horizontal jet spray flame under sub-atmospheric pressure

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2941-2952 ◽  
Author(s):  
Kai Xie ◽  
Xingqi Qiu ◽  
Yunjing Cui ◽  
Jianxin Wang
Keyword(s):  
Atmospheric Pressure ◽  
Cone Angle ◽  
Flame Temperature ◽  
Normal Pressure ◽  
Low Pressure ◽  
Dimensionless Temperature ◽  
Thermal Imager ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Matlab Programming

The burning state of a plateau environment is attracting more and more attention. In this paper, in order to have a deeper scientific understanding of diesel spray combustion and the characteristics of a flame under different spray cone angles in a plateau environment, experiments were carried out in a low pressure chamber. The flame morphology was recorded by a high speed video instrument, and the temperature change was recorded by a thermal imager and thermocouples. The MATLAB programming was used to process the video image of the flame, and the probability of its binarization was calculated. The results indicate that the flame becomes longer and wider under different pressures with the same spray angle. The variation is more pronounced at a smaller spray taper angle. The flame uplifted height characteristic is mainly negatively related to the atmospheric pressure. According to the normalized flame temperature and the dimensionless horizontal projection, the length can be divided into three regions. In the region of buoyancy flame, the dimensionless temperature varies with sub-atmospheric pressure more than with normal pressure. In addition, under different spray cone angle conditions, the law of variation in the normalized flame temperature under sub-atmospheric pressure is exactly opposite to that under normal pressure. This study is of great significance to the scientific research on flames in a low pressure environment, and the design of different fuel nozzles for application in a plateau environment.

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