13 results on '"Greene, Trevor"'
Search Results
2. Detecting and Mitigating Attacks on GPS Devices.
- Author
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Burbank, Jack, Greene, Trevor, and Kaabouch, Naima
- Subjects
- *
GLOBAL Positioning System , *GPS receivers , *LOCATION-based services , *EVIDENCE gaps , *AUTONOMOUS vehicles - Abstract
Modern systems and devices, including unmanned aerial systems (UASs), autonomous vehicles, and other unmanned and autonomous systems, commonly rely on the Global Positioning System (GPS) for positioning, navigation, and timing (PNT). Cellular mobile devices rely on GPS for PNT and location-based services. Many of these systems cannot function correctly without GPS; however, GPS signals are susceptible to a wide variety of signal-related disruptions and cyberattacks. GPS threat detection and mitigation have received significant attention recently. There are many surveys and systematic reviews in the literature related to GPS security; however, many existing reviews only briefly discuss GPS security within a larger discussion of cybersecurity. Other reviews focus on niche topics related to GPS security. There are no existing comprehensive reviews of GPS security issues in the literature. This paper fills that gap by providing a comprehensive treatment of GPS security, with an emphasis on UAS applications. This paper provides an overview of the threats to GPS and the state-of-the-art techniques for attack detection and countermeasures. Detection and mitigation approaches are categorized, and the strengths and weaknesses of existing approaches are identified. This paper also provides a comprehensive overview of the state-of-the-art on alternative positioning and navigation techniques in GPS-disrupted environments, discussing the strengths and weaknesses of existing approaches. Finally, this paper identifies gaps in existing research and future research directions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Effects of Heat Input and Intertrack Overlap on the Microstructure and Properties of Inconel 686 Weld Overlays.
- Author
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Tabaie, Seyedmohammad, Khodamoradi, Zahra, Greene, Trevor, and Benoit, Michael J.
- Subjects
GAS metal arc welding ,ELECTRIC welding ,WELDING ,PHASE transitions ,INCONEL ,ANALYTICAL chemistry ,VACUUM arcs - Abstract
The objective of this study was to investigate how weld overlays with nickel superalloys are important for the integrity, due the high temperatures and corrosive environments that can be experienced in mineral processing environments, of mining and processing equipment. The Ni-Cr-Mo superalloy Inconel 686 overlays are fabricated through automatic gas metal arc welding with variations in arc voltage and travel speed (i.e., heat input), and they have overlap between adjacent weld tracks for applications in the mining and minerals sector. The impact of variations in the process parameters and the size of the weld overlapping on the dilution, solidification morphology, microsegregation, and microhardness were investigated. Both geometric and chemical composition definitions were used to quantify the extent of the weld dilution. Subsequently, the weld geometry and dilution were correlated with the solidification microstructure and phase transformations. The maximum dilutions were measured to be 13.63% (1/2 overlap, 5.96 kJ·cm
−1 ) and 15.39% (1/3 overlap, 4.77 kJ·cm−1 ), which shows that less of an overlap increases the dilution level. Scanning electron microscopy and chemical composition analysis revealed that an increase in weld heat input and dilution level led to higher levels of microsegregation for Mo and Cr, as well as the volume fraction of Mo- and Cr-rich phases in the interdendritic/intercellular regions in the overlay layer. Analysis of the weld overlays in the current study revealed strong and unprecedented connections between the weld overlay process conditions, the resultant metallurgy (i.e., dendrite arm spacing, microsegregation, and phase formation), and the hardness of the overlay. It was concluded that the optimal weld overlays in the processing window studied in this investigation were fabricated at mid-level heat inputs (i.e., 4–5 kJ·cm−1 ) and a 1/2 track overlap. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
4. Portable neuromodulation induces neuroplasticity to re-activate motor function recovery from brain injury: a high-density MEG case study
- Author
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D’Arcy, Ryan C. N., Greene, Trevor, Greene, Debbie, Frehlick, Zack, Fickling, Shaun D., Campbell, Natasha, Etheridge, Tori, Smith, Christopher, Bollinger, Fabio, Danilov, Yuri, Livingstone, Ashley, Tannouri, Pamela, Martin, Pauline, and Lakhani, Bimal
- Published
- 2020
- Full Text
- View/download PDF
5. Brain Vital Signs Detect Cognitive Improvements During Combined Physical Therapy and Neuromodulation in Rehabilitation From Severe Traumatic Brain Injury: A Case Report.
- Author
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Fickling, Shaun D., Greene, Trevor, Greene, Debbie, Frehlick, Zack, Campbell, Natasha, Etheridge, Tori, Smith, Christopher J., Bollinger, Fabio, Danilov, Yuri, Rizzotti, Rowena, Livingstone, Ashley C., Lakhani, Bimal, and D'Arcy, Ryan C. N.
- Subjects
BRAIN injuries ,VITAL signs ,PHYSICAL therapy ,POST-traumatic stress disorder ,SYMPTOMS - Abstract
Using a longitudinal case study design, we have tracked the recovery of motor function following severe traumatic brain injury (TBI) through a multimodal neuroimaging approach. In 2006, Canadian Soldier Captain (retired) Trevor Greene (TG) was attacked with an axe to the head while on tour in Afghanistan. TG continues intensive daily rehabilitation, which recently included the integration of physical therapy (PT) with neuromodulation using translingual neurostimulation (TLNS) to facilitate neuroplasticity. Recent findings with PT + TLNS demonstrated that recovery of motor function occurred beyond conventional time limits, currently extending past 14-years post-injury. To investigate whether PT + TLNS similarly resulted in associated cognitive function improvements, we examined event-related potentials (ERPs) with the brain vital signs framework. In parallel with motor function improvements, brain vital signs detected significant increases in basic attention (as measured by P300 response amplitude) and cognitive processing (as measured by contextual N400 response amplitude). These objective cognitive improvements corresponded with TG's self-reported improvements, including a noteworthy and consistent reduction in ongoing symptoms of post-traumatic stress disorder (PTSD). The findings provide valuable insight into the potential importance of non-invasive neuromodulation in cognitive rehabilitation, in addition to initial indications for physical rehabilitation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. Long-Term Motor Recovery After Severe Traumatic Brain Injury: Beyond Established Limits.
- Author
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D'Arcy, Ryan C. N., Lindsay, D. Stephen, Xiaowei Song, Gawryluk, Jodie R., Greene, Debbie, Mayo, Chantel, Hajra, Sujoy Ghosh, Mandziuk, Lila, Mathieson, John, and Greene, Trevor
- Abstract
Objective: To report neural plasticity changes after severe traumatic brain injury. Setting: Case-control study. Participants: Canadian soldier, Captain Trevor Greene survived a severe open-traumatic brain injury during a 2006 combat tour in Afghanistan. Design: Longitudinal follow-up for more than 6 years. Main Measures: Twelve longitudinal functional magnetic imaging (fMRI) examinations were conducted to investigate lower limb activation changes in association with clinical examination. Trevor Greene's lower limb fMRI activation was compared with control fMRI activation of (1) mental imagery of similar movement and (2) matched control subject data. Results: Trevor Greene's motor recovery and corresponding fMRI activation increased significantly over time (F = 32.54, P < .001). Clinical measures of functional recovery correlated strongly with fMRI motor activation changes (r = 0.81, P = .001). By comparison, while Trevor Greene's mental imagery activated similar motor regions, there was no evidence of fMRI activation change over time. While comparable, control motor activation did not change over time and there was no significant mental imagery activation. Conclusion: Motor function recovery can occur beyond 6 years after severe traumatic brain injury, both in neural plasticity and clinical outcome. This demonstrates that continued benefits in physical function due to rehabilitative efforts can be achieved for many years following injury. The finding challenges current practices and assumptions in rehabilitation following traumatic brain injury. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
7. Use of Double Ventricular Extrastimulation to Determine the Preexcitation Index in Atrioventricular Nodal Reentrant Tachycardia.
- Author
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Waushal, Alan B., Huang, Shoei K. Steephen, Pires, Luis A., Mittleman, Robert S., Greene, Trevor O., and Schuger, Claudio D.
- Subjects
TACHYCARDIA ,ATRIOVENTRICULAR node ,HEART beat ,PATIENTS ,HEART diseases ,HEART failure - Abstract
The ability of single paced ventricular beats during tachycardia to penetrate the tachycardia circuit and reset the subsequent atrial depolarization (atrial preexcitation), enabling calculation of the "preexcitation index," can be helpful in analyzing supra-ventricular tachycardias. However, the ventricular refractory period often prevents ventricular capture of beats with the necessary prematurity to demonstrate atrial preexcitation, particularly in atrioventricular nodal reentrant tachycardia (AVNRT). We hypothesized that the use of double premature stimuli could overcome this limitation. In 25 consecutive patients with either AVNRT or atrioventricular reciprocating tachycardia (AVRT) we attempted to demonstrate atrial preexcitation with single and double ventricular extrastimuli. Whereas atrial preexcitation with a single extrastimulus could only be achieved in 3 of 11 patients with AVNRT, all but 1 patient demonstrated atrial preexcitation with the use of double ventricular extrastimuli. On the other hand, in all but 1 patient with AVRT, atrial preexcitation could be achieved with single and double extrastimuli. A formula was derived for obtaining a preexcitation index with double extrastimuli and shown to correspond closely with the preexcitation index obtained with a single extrastimulus in the 16 patients in whom atrial preexcitation could he achieved with single and double extrastimuli. Thus, this technique significantly enhances the ability to achieve atrial preexcitation and to calculate the preexcitation index in patients with AVNRT and thus may be useful in deciphering tachycardia mechanism in some patients, as well as being a useful technique in studying the electrophysiological properties of the antegrade and retrograde limbs of AVNRT. [ABSTRACT FROM AUTHOR]
- Published
- 1995
- Full Text
- View/download PDF
8. Acute Pericarditis Resulting From an Endocardial Active Fixation Screw-In Atrial Lead.
- Author
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Greene, Trevor O., Portnow, Arthur S., and Huang, Shoei K. Stephen
- Subjects
PERICARDITIS ,PERICARDIUM diseases ,HEART diseases ,ATRIAL septal defects ,HEART septum abnormalities ,CARDIAC pacemakers ,IMPLANTED cardiovascular instruments ,ARTIFICIAL implants - Abstract
We examined the occurrence of acute pericarditis after pacemaker implantation in 123 consecutive patients (61 males, 62 females, ages 17-87 years) in whom a newer atrial active fixation bipolar lead was inserted endocardially in the right atrium for dual chamber pacing. The atrial leads were positioned to obtain the best possible pacing and sensing thresholds, after an initial attempt was made for insertion into the right atrial appendage or medially into the right atrial septum. Six patients (4.9%) developed acute symptomatic pericarditis with effusion within 24 hours of implantation. Of these six patients, four had leads screwed into the lateral wall, and the other two had leads placed in the anterolateral wall. The lead implantation parameters between patients with pericarditis and those without did not show any significant difference in the atrial P wave amplitude (2.3 ± 0.4 vs 2.9 ±0.9 mV), pacing threshold (1.1 ± 0.2 vs 1.1 ± 0.4 V), or resistance (524 ± 112 vs 480 ± 94 ohms). All symptomatic patients were treated with nonsteroidal anti-inflammatory drugs with symptoms resolving in 1-2 weeks. We conclude that: (1) a significant number of patients (4.9%) developed acute symptomatic pericarditis after insertion of this type of atrial fixation lead: (2) because of the lead design, the implantation parameters could not be taken to predict the occurrence of pericarditis: and (3) caution should be taken for the insertion of this lead into the thin atrial wall. [ABSTRACT FROM AUTHOR]
- Published
- 1994
- Full Text
- View/download PDF
9. Portable neuromodulation induces neuroplasticity to re-activate motor function recovery from brain injury: a high-density MEG case study.
- Author
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D'Arcy, Ryan C. N., Greene, Trevor, Greene, Debbie, Frehlick, Zack, Fickling, Shaun D., Campbell, Natasha, Etheridge, Tori, Smith, Christopher, Bollinger, Fabio, Danilov, Yuri, Livingstone, Ashley, Tannouri, Pamela, Martin, Pauline, and Lakhani, Bimal
- Subjects
- *
MAGNETOENCEPHALOGRAPHY , *FUNCTIONAL magnetic resonance imaging , *NEUROPLASTICITY , *BRAIN injuries - Abstract
Background: In a recent high-profile case study, we used functional magnetic resonance imaging (fMRI) to monitor improvements in motor function related to neuroplasticity following rehabilitation for severe traumatic brain injury (TBI). The findings demonstrated that motor function improvements can occur years beyond current established limits. The current study extends the functional imaging investigation to characterize neuromodulation effects on neuroplasticity to further push the limits.Methods: Canadian Soldier Captain (retired) Trevor Greene (TG) survived a severe open-TBI when attacked with an axe during a 2006 combat tour in Afghanistan. TG has since continued intensive daily rehabilitation to recover motor function, experiencing an extended plateau using conventional physical therapy. To overcome this plateau, we paired translingual neurostimulation (TLNS) with the continuing rehabilitation program.Results: Combining TLNS with rehabilitation resulted in demonstrable clinical improvements along with corresponding changes in movement evoked electro-encephalography (EEG) activity. High-density magneto-encephalography (MEG) characterized cortical activation changes in corresponding beta frequency range (27 Hz). MEG activation changes corresponded with reduced interhemispheric inhibition in the post-central gyri regions together with increased right superior/middle frontal activation suggesting large scale network level changes.Conclusions: The findings provide valuable insight into the potential importance of non-invasive neuromodulation to enhance neuroplasticity mechanisms for recovery beyond the perceived limits of rehabilitation. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
10. Dobutamine digital echocardiography for detecting coronary artery disease
- Author
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Cohen, Jerald L., Greene, Trevor O., Ottenweller, John, Binenbaum, Steve Z., Wilchfort, Samuel D., and Kim, Chung S.
- Published
- 1991
- Full Text
- View/download PDF
11. Usefulness of oral quinidine-mexiletine combination therapy for sustained ventricular tachyarrhythmias as assessed by programmed electrical stimulation when quinidine monotherapy has failed
- Author
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Bonavita, Gregory J., Pires, Luis A., Wagshal, Alan B., Cuello, Carlos, Mittleman, Robert S., Greene, Trevor O., and Huang, Shoei K.Stephen
- Published
- 1994
- Full Text
- View/download PDF
12. Usefulness of oral dipyridamole digital echocardiography for detecting coronary artery disease
- Author
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Cohen, Jerald L., Greene, Trevor O., Alston, John R., Wilchfort, Samuel D., and Kim, Chung S.
- Published
- 1989
- Full Text
- View/download PDF
13. Long-Term Motor Recovery After Severe Traumatic Brain Injury: Beyond Established Limits.
- Author
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DʼArcy RC, Lindsay DS, Song X, Gawryluk JR, Greene D, Mayo C, Ghosh Hajra S, Mandziuk L, Mathieson J, and Greene T
- Subjects
- Adult, Canada, Humans, Longitudinal Studies, Magnetic Resonance Imaging, Male, Middle Aged, Military Personnel, Brain Injuries, Traumatic physiopathology, Brain Injuries, Traumatic rehabilitation, Neuronal Plasticity, Recovery of Function
- Abstract
Objective: To report neural plasticity changes after severe traumatic brain injury., Setting: Case-control study., Participants: Canadian soldier, Captain Trevor Greene survived a severe open-traumatic brain injury during a 2006 combat tour in Afghanistan., Design: Longitudinal follow-up for more than 6 years., Main Measures: Twelve longitudinal functional magnetic imaging (fMRI) examinations were conducted to investigate lower limb activation changes in association with clinical examination. Trevor Greene's lower limb fMRI activation was compared with control fMRI activation of (1) mental imagery of similar movement and (2) matched control subject data., Results: Trevor Greene's motor recovery and corresponding fMRI activation increased significantly over time (F = 32.54, P < .001). Clinical measures of functional recovery correlated strongly with fMRI motor activation changes (r = 0.81, P = .001). By comparison, while Trevor Greene's mental imagery activated similar motor regions, there was no evidence of fMRI activation change over time. While comparable, control motor activation did not change over time and there was no significant mental imagery activation., Conclusion: Motor function recovery can occur beyond 6 years after severe traumatic brain injury, both in neural plasticity and clinical outcome. This demonstrates that continued benefits in physical function due to rehabilitative efforts can be achieved for many years following injury. The finding challenges current practices and assumptions in rehabilitation following traumatic brain injury.
- Published
- 2016
- Full Text
- View/download PDF
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