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M Lowery

Publications and source records attributed to M Lowery.

12 recordsLinked to original sources
PubMed2003

Rectification and non-linear pre-processing of EMG signals for cortico-muscular analysis.

Rectification of the electromyographic (EMG) signal is a commonly used pre-processing procedure that allows detection of significant coherence between EMG and measured cortical signals. However, despite its accepted and wide-spread use, no detailed analysis has been presented to offer insight into the precise function of rectification. We begin this paper with arguments based on single motor unit action potential (AP) trains to demonstrate that rectification effectively enhances the firing rate information of the signal. Enhancement is achieved by shifting the peak of the AP spectrum toward the lower firing rate frequencies, whilst maintaining the firing rate spectra. A similar result is obtained using the analytic envelope of the signal extracted using the Hilbert transform. This argument is extended to simulated EMG signals generated using a published EMG model. Detection of firing rate frequencies is obtained using phase randomised surrogate data, where the original EMG power spectrum exceeds the averaged rectified surrogate spectra at integer multiples of firing rate frequencies. Model simulations demonstrate that this technique accurately determines grouped firing rate frequencies. Extraction of grouped firing rate frequencies prior to coherency analyses may further aid interpretation of significant cortico-muscular coherence findings.

Action Potentials↗
PubMed2002

Electromyogram median frequency, spectral compression and muscle fibre conduction velocity during sustained sub-maximal contraction of the brachioradialis muscle.

Changes in the median frequency of the power spectrum of the surface electromyogram (EMG) are commonly used to detect muscle fatigue. Previous research has indicated that changes in the median frequency are related to decreases in muscle fibre conduction velocity (MFCV) during sustained fatiguing contractions. However, in experimental studies the median frequency has been consistently observed to decrease by a relatively greater amount than MFCV. In this paper, a new estimate of EMG frequency compression, the Spectral Compression Estimate (SCE), is compared with the median frequency of the EMG power spectrum, the median frequency of the EMG amplitude spectrum and MFCV measured during sustained, isometric, fatiguing contractions of the brachioradialis muscle at 30, 50 and 80% maximum voluntary contraction (MVC). The SCE is found to provide a better estimate of the observed changes in MFCV than the median frequency of either the EMG power spectrum or EMG amplitude spectrum.

Adult↗
PubMed2001

The impact of a clinical pathway for gastric bypass surgery on resource utilization.

BACKGROUND: Clinical pathways are believed to improve patient care and reduce costs. Our hypothesis was that a gastric bypass pathway would decrease hospital resource utilization and cost of care without adversely affecting patient care. METHODS: The prepathway (Pre) group consisted of 16 gastric bypasses (6/98 to 3/99). The postpathway (Post) group includes 12 gastric bypass procedures performed after institution of the clinical pathway (4/99 to 12/99). The impact of the clinical pathway on hospital length of stay (LOS) and resource utilization was investigated. A comparison of costs was performed using cost/charge ratios. Hospital readmissions and postoperative complications were also examined. RESULTS: Despite increased obesity/medical acuity of the Post group, hospital LOS decreased by 3 days (P < 0.0001). Total hospital costs decreased by over $1600/case (>15%). Postpathway savings were greatest for room and board (34%), supplies (41%), and lab/radiology costs (50%). An increase in OR costs (22%) was observed in the Post group. This was due to an increase in anesthesia time (epidural catheter placement) and equipment costs (ultrasonic shears). Despite reductions in hospital LOS and resource utilization, the complication rate (Pre 12%, Post 16%) was similar and two patients in each group required brief readmission. CONCLUSIONS: A pathway for gastric bypass decreased hospital LOS and resource utilization. OR-related expenses account for 34-50% of total costs and must be monitored closely for surgical patients. The reduction in costs observed with this clinical pathway was not associated with an increase in postoperative complications or hospital readmission.

Adult↗
PubMed2001

Finite element modeling of electromagnetic signal propagation in a phantom arm.

Improving the control of artificial arms remains a considerable challenge. It may be possible to graft remaining peripheral nerves in an amputated limb to spare muscles in or near the residual limb and use these nerve-muscle grafts as additional myoelectric control signals. This would allow simultaneous control of multiple, degrees of freedom (DOF) and could greatly improve the control of artificial limbs. For this technique to be successful, the electromyography (EMG) signals from the nerve-muscle grafts would need to be independent of each other with minimal crosstalk. To study EMG signal propagation and quantify crosstalk, finite element (FE) models were developed in a phantom-arm model. The models were validated with experimental data collected by applying sinusoidal excitations to a phantom-arm model and recording the surface electric potential distribution. There was a very high correlation (r > 0.99) between the FEM data and the experimental data, with the error in signal magnitude generally less than 5%. Simulations were then performed using muscle dielectric properties with static, complex, and full electromagnetic solvers. The results indicate that significant displacement currents can develop (> 50% of total current) and that the fall-off of surface signal power varies with how the signal source is modeled. Index Terms-Control, electromyography (EMG), finite element (FE), modeling, prosthesis.

Arm↗
PubMed1996

Subarachnoid hemorrhage simulating myocardial infarction.

We describe a patient with a subarachnoid hemorrhage that presented with electrocardiographic evidence of transmural myocardial infarction. The patient was found to have normal coronaries and on autopsy revealed generalized myocytolysis with no evidence of transmural myocardial infarction. This case illustrates the value of acute coronary angiography in patients with altered mental status and suspected myocardial infarction.

Adult↗
PubMed1995

Cytogenetic findings in a case of congenital mesoblastic nephroma.

Congenital mesoblastic nephroma (CMN) is a benign, but locally aggressive, renal tumor of early infancy. Few metastases have been reported, but local recurrence is well documented. CMN is histologically distinct from Wilms' tumor and other childhood renal tumors, and is typically treated by surgical excision without adjuvant therapy. Cytogenetic abnormalities in these tumors have been described and are often compared with abnormalities seen in leiomyomas, fibromatoses, and infantile fibrosarcomas. In particular, trisomy 11 has been suggested as a nonrandom occurrence in CMNs. We describe a case of CMN in a 4-month-old female infant. The diagnostic histologic features included a monophasic mesenchymal appearance, prominent staghorn vascular spaces, and extensive infiltration of the adjacent kidney. Cytogenetic analysis showed a hyperdiploid chromosome number and a single structural abnormality involving a translocation between chromosomes 12 and 15. The composite karyotypic interpretation was: 46-47,XX,-X, +8, +11,t(12;15)(p12;q25), +17, +20[cp14]. The significance of karyotypic changes in this tumor is currently unknown. A genetic basis for histologic variability and progression may exist if certain cytogenetic abnormalities, such as trisomy 11 or specific translocations, confer a proliferative advantage. Additional cases are required to correlate cytogenetic findings with the biologic behaviors of CMN. We present this case as a contribution to existing literature describing these relatively rare and interesting renal tumors.

Female↗
PubMed1992

LAMP in L.A.'s skid row: a model for community-based support services.

In most states, we reneged on our promise to provide community-based program support to persons deinstitutionalized from psychiatric hospitals. Now many people are blaming those with mental illness for their failure to thrive and have begun creating new laws and methods for reinstitutionalization. This chapter describes a community-based program that is demonstrably effective. It involves the full participation of homeless people diagnosed with mental illness and attests to what can work.

Community Mental Health Services↗
PubMed1990

Interrelationship of variable coupling, multiformity and repetitive forms: implications for classification of ventricular arrhythmias.

One hundred 24-hour ambulatory electrocardiograms were prospectively examined to determine the relationship of variable coupling and multiformity of single premature ventricular complexes to repetitive forms. Premature ventricular complexes were present in 86 patients and were categorized by a three-tier decision-making tree using (1) multiformity confirmed in two channels, (2) variable coupling of greater than 80 msec of premature ventricular complexes of similar QRS morphologies, and (3) repetitive forms of greater than or equal to 2 premature ventricular complexes. Variable coupling was present in 51 patients, among whom 35 (69%) had repetitive forms; multiformity was present in 46 patients, among whom 37 (80%) had repetitive forms; repetitive forms were present in 41 patients, among whom only one patient (2%) did not demonstrate multiformity or variable coupling. Variable coupling, multiformity, or either were significantly associated with the occurrence of repetitive forms (chi square = 34, 15, 29, respectively, each p less than 0.005). There was a bimodal distribution between patients with uniform, fixed coupled premature ventricular complexes who had rare repetitive forms (1 of 26) and patients with multiformity and variable coupling of premature ventricular complexes who had significantly more repetitive forms (30 of 37; p less than 0.001). The frequency distribution of repetitive form length suggested a natural break point between five and six consecutive complexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMedDate not supplied

A campaign with street cred to target teenagers with asthma.

Failure to use asthma medication among young people has contributed to significant levels of morbidity. This report describes an attempt to address this issue through the development of a teenage-asthma initiative focusing on an inhaler rap record. The help of Byker Grove stars, the former Newcastle United player Scott Sellars and many other famous names was enlisted to facilitate the campaign. A nine-minute pop video which has been produced in collaboration with the multidisciplinary health care team forms the campaign's centerpiece. The video is supported by karaoke version of the inhaler rap, aerobic type exercises, posters, T-shirts and baseball caps. An education quiz is used to evaluate the programme.

Adolescent↗