oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 154 )

2018 ( 254 )

2017 ( 228 )

2016 ( 313 )

Custom range...

Search Results: 1 - 10 of 125718 matches for " Arthur T. Johnson "
All listed articles are free for downloading (OA Articles)
Page 1 /125718
Display every page Item
Effect of Induced Anxiety on Respiratory Resistance Using Virtual Reality Simulation  [PDF]
Matthew Bohensky, Arthur T. Johnson, Jafar Vossoughi
Open Journal of Respiratory Diseases (OJRD) , 2017, DOI: 10.4236/ojrd.2017.72008
Abstract: Background: The purpose of this research was to identify significant changes to respiratory resistance resulting from anxiety inducing simulations presented through the medium of virtual reality (VR) goggles. The tested hypothesis was that a virtual reality simulation would produce anxiety in the wearer, and, with it, a statistically significant change in subject respiratory resistance. It was also suggested that there may be a significant difference in the levels of respiratory resistance responses of males and females. The Oculus Rift DK2 VR goggles with video software designed for the Rift were used to induce anxiety in the wearers. Methods: Respiratory resistances in both inhalation and exhalation directions were measured with the Airflow Perturbation Device (APD), a medical instrument used noninvasively. Two groups of subjects were tested: the test group watched a simulation deemed to be anxiety inducing, and the Control group watched a simulation determined to be non-anxiety inducing. Anxiety levels and respiratory resistance were measured before and during the simulation with two anxiety measures, the State Trait Anxiety Inventory (STAI) and the Subjective Units of Distress Scale (SUDS). Results: Statistically significant increases in anxiety level and respiratory resistance were found in the Test group, but no significant differences in anxiety and respiratory resistance levels were found in the control group. Anxiety affected both breathing phases similarly. For the gender hypothesis, we found that one of the tests used to measure anxiety, (the SUDS difference) was statistically significant, while the other test and the difference in respiratory resistance were not statistically significant. Conclusion: Results from this experiment show that anxiety level can be a significant contributor to the physiological measurement of respiratory resistance, and this can have implications for pulmonary function test environments and the psychological conditions of the patients being tested.
Testing Low Doses of Caffeine on Respiratory Resistance Using the Airflow Perturbation Device  [PDF]
Mary Kate Montgomery, Allen Luk, Arthur T. Johnson, Jafar Vossoughi
Open Journal of Respiratory Diseases (OJRD) , 2017, DOI: 10.4236/ojrd.2017.72006
Abstract: Research reports on pulmonary function measurements often mention caffeine abstinence as a condition for testing subjects. Yet, the effects of caffeine on respiration are not well documented. This study was intended to investigate the physiological effects of caffeine on respiratory resistance measurements and the necessity of caffeine avoidance in such testing. Thirty-one subjects were administered caffeine in pill form for dosages in the range of 3 - 4.5 mg/kg body weight. Respiratory resistance was measured with the Airflow Perturbation Device every 15 minutes after caffeine ingestion until a full hour of elapsed time. No changes were noted in inhalation, exhalation, and average respiratory resistances during the times of measurements. The conclusion is that for low dosages of caffeine, respiratory resistance measurements are not affected by caffeine ingestion prior to testing.
Are premenstrual symptoms associated with health anxiety in nursing graduates?  [PDF]
Yinghui Xu, Russell Noyes, Arthur J. Hartz, Barcey T. Levy, Jeanette M. Daly, Susan R. Johnson
Open Journal of Psychiatry (OJPsych) , 2011, DOI: 10.4236/ojpsych.2011.13014
Abstract: Objective: This study examined retrospectively the relationship between premenstrual symptoms and health anxiety. Methods: Premenstrual symptoms of nursing school graduates were assessed in 1985 and again in 1991 using the Premenstrual Assessment Form (PAF). A total of 571 women completed the survey in 1991, along with items relating to their physical and mental health. The latter included depression, anxiety, and panic attacks. Health anxiety was also assessed using the Whiteley Index (WI). After women who were amenorrheic for any reason were excluded, a final sample of 410 women aged 25 to 52 years was obtained. Factor analyses yielded 57 items that were useful for calculating a total PAF score. A stepwise multivariate linear regression model was used to find the association of PAF scores with various participant characteristics. Results: Thirty-kone of the 410 (7.6%) women had WI scores of ≥5 and were considered to have significant health-related anxiety. The PAF score had statistically significant associations with health anxiety, as well as depression and anxiety. Conclusions: Our results suggest that the premenstrual symptoms often coexist with health anxiety as well as other psychological symptoms. Clinicians should be alert to the fact that PMS may be associated with treatable psychiatric conditions.
Decrease of resistance to air flow with nasal strips as measured with the airflow perturbation device
Lily S Wong, Arthur T Johnson
BioMedical Engineering OnLine , 2004, DOI: 10.1186/1475-925x-3-38
Abstract: This study tested forty-seven volunteers (14 men and 33 women), ranging in age from 17 to 51. Each volunteer was instructed to breathe normally into the APD using an oronasal mask with and without nasal strips. The APD measured respiratory resistance during inhalation, exhalation, and an average of the two.Results of a paired mean t-test comparing nasal strip against no nasal strip were statistically significant at the p = 0.05 level. The Breathe Right? nasal dilator strips lowered nasal resistance by an average of 0.5 cm H20/Lps from an average nasal resistance of 5.5 cm H20/Lps.Nasal strips reduce nasal resistance when measured with the APD. The effect is equal during exhalation and during inhalation.Nasal dilator strips (NDS) are used by athletes, people who snore, and asthmatics to ease the burden of breathing. The nasal strips are used as a mechanical means of reducing nasal airflow resistance [1]. By lowering nasal resistance, they reduce the work of breathing and the supply of oxygen into the body could increase [2,3].The size of the nostril limits the amount of air entering into the body. The NDS is placed along the nasal valve of the nose. The adhesiveness of the strip binds to the creases of the nasal valve to prevent the outer wall tissue of the nose from collapsing inward during nasal breathing. This mechanism thus dilates the nose and allows more air to flow into the nose [3].The primary effect of the NDS could be either to dilate the air passage of the nose or to stiffen the nasal wall. Either mechanism would reduce nasal resistance and allow higher flow of air, but they can be distinguished over a range of air flows. Stiffening the nasal wall would have its most profound effect at higher flows where the Bernoulli effect would decrease internal nasal pressures and tend to constrict nasal passage diameter. Air passage dilation would tend to decrease nasal resistance more uniformly over a range of air flows.Recent studies on the effectiveness of Breathe
Resistance Measured by Airflow Perturbation Compared with Standard Pulmonary Function Measures  [PDF]
Tania Haque, Jafar Vossoughi, Arthur T. Johnson, Wanda Bell-Farrell, Thomas Fitzgerald, Steven M. Scharf
Open Journal of Respiratory Diseases (OJRD) , 2013, DOI: 10.4236/ojrd.2013.32010
Abstract: Background: Routine lung function testing requires expensive equipment, or requires maximum expiratory effort. The airflow perturbation device (APD) is a light handheld device, allowing for serial measures of respiratory resistance noninvasively and effortlessly. Methods: In a convenience sample of 398 patients undergoing pulmonary function testing, we compared routine spirometric indices (forced expired volume in 1 second (FEV1), peak expiratory flow (PEF)), and airways resistance (Raw-272 patients), to measures of respiratory resistance measured with the APD including inspiratory (IR), expiratory (ER) and averaged (AR) resistance. Results: Measures of lung function were significantly correlated (p < 0.001). On regression analysis, between 7% - 17% of the variance (R2) for FEV1, PEF, and Raw was explained by APD measurements. Approximately 2/3 of the variance in FEV1 was explained by PEF measurements. Conclusions: APD measurements of lung function correlate with conventional measures. Future studies should be directed at exploring the use of the APD device in serial measures of lung function in patients with lung disease.
Inward Leakage in Tight-Fitting PAPRs
Frank C. Koh,Arthur T. Johnson,Timothy E. Rehak
Journal of Environmental and Public Health , 2011, DOI: 10.1155/2011/473143
Abstract: A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form.
Maximum static inspiratory and expiratory pressures with different lung volumes
Christopher G Lausted, Arthur T Johnson, William H Scott, Monique M Johnson, Karen M Coyne, Derya C Coursey
BioMedical Engineering OnLine , 2006, DOI: 10.1186/1475-925x-5-29
Abstract: Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity.In women, maximum expiratory pressure increased with volume from 39 to 61 cmH2O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH2O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH2O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH2O. Equations describing pressures for both sexes are:Pe/Pmax = 0.1426 Ln( %VC) + 0.3402 R2 = 0.95Pi/Pmax = 0.234 Ln(100 - %VC) - 0.0828 R2 = 0.96These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models.While maximum respiratory pressures at the mouth have been measured in numerous subjects, less data exists to characterize maximum pressures as they vary with lung volume. Maximum pressure is volume dependent because muscle tension is length dependent, because muscle tension produces higher pressure with a smaller radius of curvature, and because respiratory tissue is elastic. Rahn et al. [1] first produced static pressure-volume diagrams from a group of adult men, and later, Cook et al. [2] produced pressure-volume diagrams from a larger group of subjects including women and children. These diagrams were useful in modeling the energetics of respiration [3] and in monitoring the progress of respiratory muscle training [4]. Yet the total number of subjects tested remained small, particularly regarding females. The present paper provides additional static pressure-volume data obtained from adult volunteers, both women and men.Forty-eight normal subjects agreed to participate in the study. The subjects were recruited from students and staff at the University of Maryland. The study was approved by the Ins
Using to Determine Inhaled Contaminant Volumes and Blower Effectiveness in Several Types of Respirators
Arthur T. Johnson,Frank C. Koh,William H. Scott Jr.,Timothy E. Rehak
Journal of Environmental and Public Health , 2011, DOI: 10.1155/2011/402148
Abstract: This experiment was conducted to determine how much contaminant could be expected to be inhaled when overbreathing several different types of respirators. These included several tight-fitting and loose-fitting powered air-purifying respirators (PAPRs) and one air-purifying respirator (APR). CO2 was used as a tracer gas in the ambient air, and several loose-and tight-fitting respirators were tested on the head form of a breathing machine. CO2 concentration in the exhaled breath was monitored as well as CO2 concentration in the ambient air. This concentration ratio was able to give a measurement of protection factor, not for the respirator necessarily, but for the wearer. Flow rates in the filter/blower inlet and breathing machine outlet were also monitored, so blower effectiveness (defined as the blower contribution to inhaled air) could also be determined. Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR. Inhaled contaminant volumes depended on tidal volume but ranged from 2.02 L to 0 L for the same respirators, respectively. Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs. With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation. Results from this experiment point to different ways to measure respirator efficacy.
Targeted Amino-Terminal Acetylation of Recombinant Proteins in E. coli
Matthew Johnson,Arthur T. Coulton,Michael A. Geeves,Daniel P. Mulvihill
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015801
Abstract: One major limitation in the expression of eukaryotic proteins in bacteria is an inability to post-translationally modify the expressed protein. Amino-terminal acetylation is one such modification that can be essential for protein function. By co-expressing the fission yeast NatB complex with the target protein in E.coli, we report a simple and widely applicable method for the expression and purification of functional N-terminally acetylated eukaryotic proteins.
Testing limits to airflow perturbation device (APD) measurements
Erika R Lopresti, Arthur T Johnson, Frank C Koh, William H Scott, Shaya Jamshidi, Nischom K Silverman
BioMedical Engineering OnLine , 2008, DOI: 10.1186/1475-925x-7-28
Abstract: Ten subjects between the ages of 18 and 35 were tested for each station in the experiment. The first station involved testing the effects of leaks of known sizes on APD measurements. The second station tested the use of an oronasal mask used in conjunction with the APD during nose and mouth breathing. The third station tested the effects of two different resistances added in series with the APD mouthpiece. The fourth station tested the usage of a flexible ventilator tube in conjunction with the APD.All leaks reduced APD resistance measurement values. Leaks represented by two 3.2 mm diameter tubes reduced measured resistance by about 10% (4.2 cmH2O·sec/L for control and 3.9 cm H2O·sec/L for the leak). This was not statistically significant. Larger leaks given by 4.8 and 6.4 mm tubes reduced measurements significantly (3.4 and 3.0 cm cmH2O·sec/L, respectively). Mouth resistance measured with a cardboard mouthpiece gave an APD measurement of 4.2 cm H2O·sec/L and mouth resistance measured with an oronasal mask was 4.5 cm H2O·sec/L; the two were not significantly different. Nose resistance measured with the oronasal mask was 7.6 cm H2O·sec/L. Adding airflow resistances of 1.12 and 2.10 cm H2O·sec/L to the breathing circuit between the mouth and APD yielded respiratory resistance values higher than the control by 0.7 and 2.0 cm H2O·sec/L. Although breathing through a 52 cm length of flexible ventilator tubing reduced the APD measurement from 4.0 cm H2O·sec/L for the control to 3.6 cm H2O·sec/L for the tube, the difference was not statistically significant.The APD can be adapted for use in ventilated, unconscious, and uncooperative patients with use of a ventilator tube and an oronasal mask without significantly affecting measurements. Adding a resistance in series with the APD mouthpiece has an additive effect on resistance measurements, and can be used for qualitative calibration. A leak size of at least the equivalent of two 3.2 mm diameter tubes can be tolerated withou
Page 1 /125718
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.