Angela Lee - Academia.edu (original) (raw)

Papers by Angela Lee

Research paper thumbnail of Pediatric Anesthesia Management for Post-Tonsillectomy Bleed: Current Status and Future Directions

International Journal of General Medicine, 2022

After medical stabilization, several techniques are considered for anesthesia in the surgical int... more After medical stabilization, several techniques are considered for anesthesia in the surgical intervention of post-tonsillectomy bleeding in children. Hypoxia during induction of general anesthesia occurs more frequently than aspiration for this population. While classical (apneic) rapid sequence induction and intubation with cricoid pressure still has a role, controlled rapid sequence induction and intubation that incorporates mask ventilation at low pressure (<12 cm H2O) before direct laryngoscopy under a deep plane of anesthesia is a viable alternative for cases of slow venous bleeding. Supplemental oxygen delivery during laryngoscopy to permit apneic oxygenation is a future trend in management. While the routine administration of tranexamic acid during tonsillectomy has not been shown to be of benefit, it may have a role in post-tonsillectomy hemorrhage with further study.

Research paper thumbnail of Author's response to reviews Title: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their response to trunk perturbations. Authors

RE: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their re... more RE: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their response to trunk perturbations. Dear Editor, Enclosed please find our revised manuscript, which we would like you to consider for publication in BMC Musculoskeletal Disorders. This material and results have not been published or submitted for publication elsewhere. The manuscript contains information relevant to current rehabilitation strategies for low back pain. We addressed all of the points raised by the reviewers and described our changes below.

Research paper thumbnail of Understanding Instant Messaging in the Workplace

Advances in Visual Informatics, 2019

In the workplace, effective communication plays a vital role. Many work tasks require communicati... more In the workplace, effective communication plays a vital role. Many work tasks require communication which includes planning, organizing, motivating and controlling. Communication establishes relationship between superiors and their subordinates, and it determines the quality of relationship between colleagues. Currently, computer mediated communication such as Instant Messaging (IM) is used in complimentary to or as a replacement of e-mails to complete tasks. This paper discusses how IM has evolved and being adapted at work. Reviews conducted from previous studies show the impact and how people practice IM in workplaces to create a better communication and relationship in areas such as education, health care, business and others. Research shows that communication through IM applications can support or improve the quality of communication, work task and the relationship between colleagues. Based on the current trend of IM usage is the workplace, the paper proposes a qualitative method to study WhatsApp mobile application usage in the workplace. This approach will be used to observe how IM is adapted in WhatsApp group conversation in the workplace. The goal of this proposed study is to observe the use of WhatsApp at work using the existing framework, develop an IM usage model at the workplace and test and validate the IM model to make it more workplace-friendly that encourages to full implementation as a medium of communication in the workplace.

Research paper thumbnail of Methods for improving chemical vapor deposition processing

Research paper thumbnail of Plasma CVD of silicon nitride thin films on large area glass substrates at high deposition rates

Research paper thumbnail of Gas reactions to eliminate contaminates in a CVD chamber

Research paper thumbnail of Method for multilayer CVD processing in a single chamber

Research paper thumbnail of Trunk muscle response to various protocols of lumbar traction

Manual Therapy, 2009

The purpose of this study was to compare trunk muscle activity, spinal decompression force, and t... more The purpose of this study was to compare trunk muscle activity, spinal decompression force, and trunk flexibility resulting from various protocols of spinal traction. Four experiments explored the effects of (1) sinusoidal, triangular, square, and continuous distraction-force waveforms, (2) 0, 10, 20, and 30 degrees of pull angle, (3) superimposed low, medium and high frequency force oscillations, and (4) sham traction. Nineteen healthy subjects volunteered for this study. Surface EMG was recorded during traction and later used in a biomechanical model to estimate spine decompression force. Trunk flexibility was measured before and after each treatment. There were no differences in muscle activity between any of the experimental conditions except the thoracic erector spinae muscle, which had lower EMG during continuous compared to sinusoidal distraction-force waveform (p ¼ 0.02). Thoracic and lumbar erector spinae muscles were significantly less active during sham than real traction (p ¼ 0.01 and p ¼ 0.04, respectively). The estimated L4-L5 spine compression force was 25 N. Trunk flexibility decreased after each experimental session (p ¼ 0.01), and there were no differences between sessions. Our results suggest that the trunk muscle activity is minimal and point toward fluid exchange in the disc as one of the key biomechanical effects of spinal traction.

Research paper thumbnail of The effect of background muscle activity on computerized detection of sEMG onset and offset

Journal of Biomechanics, 2007

The performance of two computerized algorithms for the detection of muscle onset and offset was c... more The performance of two computerized algorithms for the detection of muscle onset and offset was compared. Standard deviation (SD) method, a commonly used algorithm, and approximated generalized likelihood ratio (AGLR) method, a more recently developed algorithm, were evaluated at different levels of background surface EMG (sEMG) activity. For this purpose, the amplitude ratio between the period of muscle inactivity and activity was varied from 0.125 to 1 in artificially assembled sEMG traces. In addition, 1230 real sEMG signals, obtained from various trunk muscles, were raised to a power of 3 to change the relative amplitude ratio. As the relative level of background activity increased, both the SD and AGLR methods produced longer latencies and detected fewer muscle responses, suggesting that a detection artifact can be introduced if the subject populations being compared have different levels of background muscle activity. Of the two methods, AGLR appears to be the least affected by background activity. However, above the ratio 0.8, results from AGLR are also unreliable particularly in detecting offsets. Average latency artifacts near this ratio were 8 ms for AGLR and 46 ms for SD.

Research paper thumbnail of Trunk antagonist co-activation is associated with impaired neuromuscular performance

Experimental Brain Research, 2008

The goal of this paper was to determine if trunk antagonist activation is associated with impaire... more The goal of this paper was to determine if trunk antagonist activation is associated with impaired neuromuscular performance. To test this theory, we used two methods to impair neuromuscular control: strenuous exertions and fatigue. Force variability (standard deviation of force signal) was assessed for graded isometric trunk exertions (10, 20, 40, 60, 80 % of max) in flexion and extension, and at the start and end of a trunk extensor fatiguing trial. Normalized EMG signals for five trunk muscle pairs (RA-rectus abdominis, EO-external oblique, IO-internal oblique, TE-thoracic erector spinae, and LE-lumbar erector spinae) were collected for each graded exertion, and at the start and end of a trunk extensor fatiguing trial. Force variability increased for more strenuous exertions in both flexion (p<.001) and extension (p<.001), and after extensor fatigue (p<.012). In the flexion direction, both antagonist muscles (TE & LE) increased activation for more strenuous exertions (p<.001). In the extension direction, all antagonist muscles except RA increased activation for more strenuous exertions (p<.05) and following fatigue (p<.01). These data demonstrate a strong relationship between force variability and antagonistic muscle activation, irrespective of where this variability comes from. Such antagonistic co-activation increases trunk stiffness with the possible objective of limiting kinematic disturbances due to greater force variability.

Research paper thumbnail of The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and on the muscular response to trunk perturbations

BMC Musculoskeletal Disorders, 2010

Background: The effects of lumbosacral orthoses (LSOs) on neuromuscular control of the trunk are ... more Background: The effects of lumbosacral orthoses (LSOs) on neuromuscular control of the trunk are not known. There is a concern that wearing LSOs for a long period may adversely alter muscle control, making individuals more susceptible to injury if they discontinue wearing the LSOs. The purpose of this study was to document neuromuscular changes in healthy subjects during a 3-week period while they regularly wore a LSO. Methods: Fourteen subjects wore LSOs 3 hrs a day for 3 weeks. Trunk muscle activity prior to and following a quick force release (trunk perturbation) was measured with EMG in 3 sessions on days 0, 7, and 21. A longitudinal, repeatedmeasures, factorial design was used. Muscle reflex response to trunk perturbations, spine compression force, as well as effective trunk stiffness and damping were dependent variables. The LSO, direction of perturbation, and testing session were the independent variables. Results: The LSO significantly (P < 0.001) increased the effective trunk stiffness by 160 Nm/rad (27%) across all directions and testing sessions. The number of antagonist muscles that responded with an onset activity was significantly reduced after 7 days of wearing the LSO, but this difference disappeared on day 21 and is likely not clinically relevant. The average number of agonist muscles switching off following the quick force release was significantly greater with the LSO, compared to without the LSO (P = 0.003). Conclusions: The LSO increased trunk stiffness and resulted in a greater number of agonist muscles shutting-off in response to a quick force release. However, these effects did not result in detrimental changes to the neuromuscular function of trunk muscles after 3 weeks of wearing a LSO 3 hours a day by healthy subjects.

Research paper thumbnail of Comparison of Trunk Proprioception Between Patients With Low Back Pain and Healthy Controls

Archives of Physical Medicine and Rehabilitation, 2010

Objective-To determine if proprioceptive impairments exist in patients with low back pain (LBP). ... more Objective-To determine if proprioceptive impairments exist in patients with low back pain (LBP). We hypothesized that patients with LBP would exhibit larger trunk proprioception errors than healthy controls. Design-Case-control study. Setting-University laboratory. Participants-24 patients with non-specific LBP and 24 age-matched healthy controls. Interventions-Not applicable. Main Outcome Measures-We measured trunk proprioception in all 3 anatomical planes using motion perception threshold, active repositioning, and passive repositioning tests.

Research paper thumbnail of Pediatric Anesthesia Management for Post-Tonsillectomy Bleed: Current Status and Future Directions

International Journal of General Medicine, 2022

After medical stabilization, several techniques are considered for anesthesia in the surgical int... more After medical stabilization, several techniques are considered for anesthesia in the surgical intervention of post-tonsillectomy bleeding in children. Hypoxia during induction of general anesthesia occurs more frequently than aspiration for this population. While classical (apneic) rapid sequence induction and intubation with cricoid pressure still has a role, controlled rapid sequence induction and intubation that incorporates mask ventilation at low pressure (<12 cm H2O) before direct laryngoscopy under a deep plane of anesthesia is a viable alternative for cases of slow venous bleeding. Supplemental oxygen delivery during laryngoscopy to permit apneic oxygenation is a future trend in management. While the routine administration of tranexamic acid during tonsillectomy has not been shown to be of benefit, it may have a role in post-tonsillectomy hemorrhage with further study.

Research paper thumbnail of Author's response to reviews Title: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their response to trunk perturbations. Authors

RE: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their re... more RE: The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and their response to trunk perturbations. Dear Editor, Enclosed please find our revised manuscript, which we would like you to consider for publication in BMC Musculoskeletal Disorders. This material and results have not been published or submitted for publication elsewhere. The manuscript contains information relevant to current rehabilitation strategies for low back pain. We addressed all of the points raised by the reviewers and described our changes below.

Research paper thumbnail of Understanding Instant Messaging in the Workplace

Advances in Visual Informatics, 2019

In the workplace, effective communication plays a vital role. Many work tasks require communicati... more In the workplace, effective communication plays a vital role. Many work tasks require communication which includes planning, organizing, motivating and controlling. Communication establishes relationship between superiors and their subordinates, and it determines the quality of relationship between colleagues. Currently, computer mediated communication such as Instant Messaging (IM) is used in complimentary to or as a replacement of e-mails to complete tasks. This paper discusses how IM has evolved and being adapted at work. Reviews conducted from previous studies show the impact and how people practice IM in workplaces to create a better communication and relationship in areas such as education, health care, business and others. Research shows that communication through IM applications can support or improve the quality of communication, work task and the relationship between colleagues. Based on the current trend of IM usage is the workplace, the paper proposes a qualitative method to study WhatsApp mobile application usage in the workplace. This approach will be used to observe how IM is adapted in WhatsApp group conversation in the workplace. The goal of this proposed study is to observe the use of WhatsApp at work using the existing framework, develop an IM usage model at the workplace and test and validate the IM model to make it more workplace-friendly that encourages to full implementation as a medium of communication in the workplace.

Research paper thumbnail of Methods for improving chemical vapor deposition processing

Research paper thumbnail of Plasma CVD of silicon nitride thin films on large area glass substrates at high deposition rates

Research paper thumbnail of Gas reactions to eliminate contaminates in a CVD chamber

Research paper thumbnail of Method for multilayer CVD processing in a single chamber

Research paper thumbnail of Trunk muscle response to various protocols of lumbar traction

Manual Therapy, 2009

The purpose of this study was to compare trunk muscle activity, spinal decompression force, and t... more The purpose of this study was to compare trunk muscle activity, spinal decompression force, and trunk flexibility resulting from various protocols of spinal traction. Four experiments explored the effects of (1) sinusoidal, triangular, square, and continuous distraction-force waveforms, (2) 0, 10, 20, and 30 degrees of pull angle, (3) superimposed low, medium and high frequency force oscillations, and (4) sham traction. Nineteen healthy subjects volunteered for this study. Surface EMG was recorded during traction and later used in a biomechanical model to estimate spine decompression force. Trunk flexibility was measured before and after each treatment. There were no differences in muscle activity between any of the experimental conditions except the thoracic erector spinae muscle, which had lower EMG during continuous compared to sinusoidal distraction-force waveform (p ¼ 0.02). Thoracic and lumbar erector spinae muscles were significantly less active during sham than real traction (p ¼ 0.01 and p ¼ 0.04, respectively). The estimated L4-L5 spine compression force was 25 N. Trunk flexibility decreased after each experimental session (p ¼ 0.01), and there were no differences between sessions. Our results suggest that the trunk muscle activity is minimal and point toward fluid exchange in the disc as one of the key biomechanical effects of spinal traction.

Research paper thumbnail of The effect of background muscle activity on computerized detection of sEMG onset and offset

Journal of Biomechanics, 2007

The performance of two computerized algorithms for the detection of muscle onset and offset was c... more The performance of two computerized algorithms for the detection of muscle onset and offset was compared. Standard deviation (SD) method, a commonly used algorithm, and approximated generalized likelihood ratio (AGLR) method, a more recently developed algorithm, were evaluated at different levels of background surface EMG (sEMG) activity. For this purpose, the amplitude ratio between the period of muscle inactivity and activity was varied from 0.125 to 1 in artificially assembled sEMG traces. In addition, 1230 real sEMG signals, obtained from various trunk muscles, were raised to a power of 3 to change the relative amplitude ratio. As the relative level of background activity increased, both the SD and AGLR methods produced longer latencies and detected fewer muscle responses, suggesting that a detection artifact can be introduced if the subject populations being compared have different levels of background muscle activity. Of the two methods, AGLR appears to be the least affected by background activity. However, above the ratio 0.8, results from AGLR are also unreliable particularly in detecting offsets. Average latency artifacts near this ratio were 8 ms for AGLR and 46 ms for SD.

Research paper thumbnail of Trunk antagonist co-activation is associated with impaired neuromuscular performance

Experimental Brain Research, 2008

The goal of this paper was to determine if trunk antagonist activation is associated with impaire... more The goal of this paper was to determine if trunk antagonist activation is associated with impaired neuromuscular performance. To test this theory, we used two methods to impair neuromuscular control: strenuous exertions and fatigue. Force variability (standard deviation of force signal) was assessed for graded isometric trunk exertions (10, 20, 40, 60, 80 % of max) in flexion and extension, and at the start and end of a trunk extensor fatiguing trial. Normalized EMG signals for five trunk muscle pairs (RA-rectus abdominis, EO-external oblique, IO-internal oblique, TE-thoracic erector spinae, and LE-lumbar erector spinae) were collected for each graded exertion, and at the start and end of a trunk extensor fatiguing trial. Force variability increased for more strenuous exertions in both flexion (p<.001) and extension (p<.001), and after extensor fatigue (p<.012). In the flexion direction, both antagonist muscles (TE & LE) increased activation for more strenuous exertions (p<.001). In the extension direction, all antagonist muscles except RA increased activation for more strenuous exertions (p<.05) and following fatigue (p<.01). These data demonstrate a strong relationship between force variability and antagonistic muscle activation, irrespective of where this variability comes from. Such antagonistic co-activation increases trunk stiffness with the possible objective of limiting kinematic disturbances due to greater force variability.

Research paper thumbnail of The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and on the muscular response to trunk perturbations

BMC Musculoskeletal Disorders, 2010

Background: The effects of lumbosacral orthoses (LSOs) on neuromuscular control of the trunk are ... more Background: The effects of lumbosacral orthoses (LSOs) on neuromuscular control of the trunk are not known. There is a concern that wearing LSOs for a long period may adversely alter muscle control, making individuals more susceptible to injury if they discontinue wearing the LSOs. The purpose of this study was to document neuromuscular changes in healthy subjects during a 3-week period while they regularly wore a LSO. Methods: Fourteen subjects wore LSOs 3 hrs a day for 3 weeks. Trunk muscle activity prior to and following a quick force release (trunk perturbation) was measured with EMG in 3 sessions on days 0, 7, and 21. A longitudinal, repeatedmeasures, factorial design was used. Muscle reflex response to trunk perturbations, spine compression force, as well as effective trunk stiffness and damping were dependent variables. The LSO, direction of perturbation, and testing session were the independent variables. Results: The LSO significantly (P < 0.001) increased the effective trunk stiffness by 160 Nm/rad (27%) across all directions and testing sessions. The number of antagonist muscles that responded with an onset activity was significantly reduced after 7 days of wearing the LSO, but this difference disappeared on day 21 and is likely not clinically relevant. The average number of agonist muscles switching off following the quick force release was significantly greater with the LSO, compared to without the LSO (P = 0.003). Conclusions: The LSO increased trunk stiffness and resulted in a greater number of agonist muscles shutting-off in response to a quick force release. However, these effects did not result in detrimental changes to the neuromuscular function of trunk muscles after 3 weeks of wearing a LSO 3 hours a day by healthy subjects.

Research paper thumbnail of Comparison of Trunk Proprioception Between Patients With Low Back Pain and Healthy Controls

Archives of Physical Medicine and Rehabilitation, 2010

Objective-To determine if proprioceptive impairments exist in patients with low back pain (LBP). ... more Objective-To determine if proprioceptive impairments exist in patients with low back pain (LBP). We hypothesized that patients with LBP would exhibit larger trunk proprioception errors than healthy controls. Design-Case-control study. Setting-University laboratory. Participants-24 patients with non-specific LBP and 24 age-matched healthy controls. Interventions-Not applicable. Main Outcome Measures-We measured trunk proprioception in all 3 anatomical planes using motion perception threshold, active repositioning, and passive repositioning tests.