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M Walsh

Publications and source records attributed to M Walsh.

At least 37 records · Page 2Linked to original sources
PubMed2004

Spatial and temporal structure of edge-localized modes.

This Letter provides information on the spatial and temporal structure of periodic eruptions observed in magnetically confined laboratory fusion plasmas, called edge-localized modes (ELMs), and highlights similarities with solar eruptions. Taken together, the observations presented in this Letter provide strong evidence for ELMs being associated with a filamentlike structure. These filaments are extended along a field line, are generated on a 100 micros time scale, erupt from the outboard side, and connect back into the plasma. Such structures are predicted by a theoretical model based on the "ballooning" instability, developed for both solar and tokamak applications.

Journal Article↗
PubMed2004

Kinematics of the toe touching test: an investigation using motion analysis.

We describe a technique for measuring dynamic motion at the low back along with the major lower limb joints during the toe touching maneuver. This type of motion analysis was carried out on eight normal volunteers. Flexion during the toe touching maneuver involves not only low back and hip movement but also ankle plantar flexion and a varying degree of knee movement. The low back and ankle movements were highly correlated within each subject to an extent that suggests a functional connection between the lower limb and low back movements. The significance of our work is two-fold. First, we emphasize that the toe touching test represents a combined movement of the low back, the hips, the knees, and the ankles and it is reasonable to suggest that abnormalities of these joints may affect the clinical relevance of the test as an indicator of back movement. Second, we point out that the guidelines of the American Medical Association in using the test to determine hip movement are incorrect as they do not take into account the effect of knee and ankle movements on the estimation of hip movement.

Adult↗
PubMed2004

Movements at the low back during normal walking.

We present a technique for measuring the kinematics of the functional low back during normal gait. We have used a similar technique previously to measure low back movement simultaneously with hip, knee, and ankle movement during the toe-touching manoeuvre. We noted that movements at the low back were biphasic. The greatest low back movements were found to occur in the transverse plane (mean = 23 degrees), whereas a mean of 17 degrees movement occurred in the coronal plane and only 5 degrees movement in the sagittal plane. These findings confirm, using a non-invasive technique, that there are significant ranges of movement at the low back during walking and lend some support to the theory that rotational movement at the low back is a major component of human locomotion.

Adult↗
PubMed2004

A mathematical model to predict the in vivo pulsatile drag forces acting on bifurcated stent grafts used in endovascular treatment of abdominal aortic aneurysms (AAA).

Endovascular treatment of abdominal aortic aneurysms (AAA) is a promising new alternative to the traditional surgical repair. However, the endovascular approach suffers problems such as stent graft migration, endoleaks and stent mechanism breakage. Fatigue failure is believed to be the major cause of stent graft migration and device breakage. Knowledge of the in vivo forces acting on such devices is a basic requirement for the design of a successful endovascular device. Using a Fourier series trigonometric fit of a typical pressure and flow relationship, a mathematical model, using the control volume method, was developed to predict the pulsatile drag forces acting on various bifurcated stent graft geometries. It was found that for an iliac angle of 30 degrees, a proximal diameter of 24 mm and an iliac diameter of 12 mm, the drag force varied, over the cardiac cycle, between 3.9 and 5.5 N in the axial direction. It was noted that for a specific iliac angle the drag force variation with proximal diameter approximates a quadratic fit, with an increase in proximal diameter producing an increase in drag force. The more compliant the aorta the higher the drag force. Previously published results demonstrated the axial loads (axial drag forces) required for stent graft migration for certain stents types are lower than the drag forces calculated in this study. It is believed that the results of this study can provide guidelines for the quantitative analyses of the in vivo drag forces experienced by stent grafts and could therefore be used as design criteria for such devices.

Aortic Aneurysm, Abdominal↗
PubMed2004

Anthropometrical analysis of cervical spine injuries.

UNLABELLED: To date the principal focus of the mechanism of cervical spine fracture has been directed towards head/neck circumference and vertebral geometric dimensions. However the role of other measurements, including chest circumference and neck length, in a standard cervical fracture population has not yet been studied in detail. Cervical fractures often involve flexion/extension type mechanisms of injury, with the head and cervical spine flexing/extending, using the thorax as an end point of contact. Thus, the thorax may play an important role in neck injuries. STUDY DESIGN: We prospectively studied all patients with cervical spine fractures who were admitted to the National Spinal Injuries Unit from 1 July 2000 to 1 March 2001. Anthropometrical measurement of head circumference, neck circumference, chest circumference, and neck length were analysed. Ages ranged from 18 to 55 years, and all patients with concomitant cervical pathology were excluded from the study. Mechanism of injury involved flexion/extension type injuries in all cases; those with direct axial loading were excluded. A control group of 40 patients (age 18-50 years) involved in high velocity trauma with associated long bone fractures, in whom cervical injury was suspected, but who were without any cervical fracture, or associated pathology, were similarly measured. RESULTS: Our analysis revealed a statistically significant increase in chest size in the male control group versus the male fracture group (97.89 cm versus 94.19 cm, P < 0.05, Student's t-test). There was a correspondingly significant increase in chest circumference between the female controls versus the female fracture group (92.33 cm versus 88.88 cm, P < 0.05, Student's t-test). Our results revealed no statistical difference in head circumference, neck circumference, or neck length between each of the groupings. These results indicate a proportionately larger chest may be a protective factor in cervical spine fractures.

Adolescent↗
PubMed2003

Serotonergic mediation of the antidepressant-like effects of nitric oxide synthase inhibitors.

Recent studies indicate that nitric oxide (NO) synthase inhibitors have antidepressant-like potential in various animal models. In the present study the behavioural activity of the NO synthase inhibitors, N(G)-nitro-L-arginine (L-NA) and 7-nitroindazole (7-NI), were assessed in a modified rat forced swimming test (FST). Both L-NA and 7-NI, dose dependently reduced immobility and increased swimming behaviour in the rat FST. This behavioural profile parallels the one previously shown with selective serotonin re-uptake inhibitors and serotonergic agonists. Thus, we examined the role of serotonin mediating the behavioural effects of L-NA and 7-NI in the rat FST. Depletion of endogenous serotonin using para-chlorophenylalanine (pCPA; 3 x 150 mg/kg, i.p.) completely blocked L-NA (20 mg/kg, i.p.) and 7-NI (20 mg/kg, i.p.)-induced reductions in immobility and increases in swimming behaviour during the FST. In conclusion these observations suggest that NO synthase inhibitors elicit their antidepressant-like activity in the modified swimming test through a serotonin dependent mechanism.

Animals↗
PubMed2003

Hair cell regeneration in the inner ear: a review.

Hair cell regeneration has been shown to occur in the inner ear of mammals. Specifically, it has been demonstrated in the vestibular system and not the organ of Corti. Recent evidence suggests that the degree of the regenerative response may be augmented pharmacologically. This review discusses the field of hair cell regeneration in fish, amphibians, birds and mammals, and the relationship of regeneration to functional recovery

Amphibians↗
PubMed2003

On using experimentally estimated wall shear stresses to validate numerically predicted results.

The objective of this investigation was to assess the use of experimentally estimated wall shear stresses to validate numerically predicted results. The most commonly cited haemodynamic factor implicated in the disease initiation and proliferation processes at graft/artery junctions is wall shear stress (WSS). WSS can be determined from the product of the viscosity of the fluid and the wall shear rate. Numerically, the wall shear rate is predicted using velocity values stored in the computational cell near the wall and assuming zero velocity at the wall. Experimentally, the wall shear rate is estimated by applying a curve-fit to near-wall velocity measurements and evaluating the shear rate at a specific distance from the wall. When estimating the wall shear rate from the laser Doppler anemometry (LDA) point velocity measurements, large differences between the experimentally estimated and numerically predicted WSSs were introduced. It was found that the estimated WSS distributions from the experimental results are highly dependent on the curve-fitting method used to calculate the wall shear rate. However, the velocity profiles for both the experimental and numerical investigations show extremely good comparison. It is concluded that numerical models should be validated using unprocessed LDA point velocity measurement and not estimated WSS values.

Anastomosis, Surgical↗
PubMed2003

Manipulation of nasal bone fractures under local anaesthetic.

This article describes the technique of manipulation of nasal bones under local anaesthesia. With increased demand on day ward and in patient hospital beds there is a growing need to treat fractured nasal bones under local anaesthesia at the ENT clinic. Ten patients were treated in this fashion in the out patient setting. All had X rays confirming a fracture of the nasal bones. All ten had an obvious cosmetic deformity of the nose as a result of the fracture. All ten patients underwent satisfactory reduction under local anaesthesia and without the need for intra nasal manipulation to elevate overlapping bones. Reduction of nasal bones in the clinic under local anaesthesia should become the accepted practice where there is a deformity but no overlap of the nasal bones.

Anesthetics, Local↗
PubMed2002

Measuring movement at the low back.

The clinical importance of movements of the human spine is increasingly being realized but their measurement is difficult to carry out. Traditionally, measurement of spinal motion focuses on the lumbar spine as the mobile region and movement at the lower thoracic spine is largely ignored. The aim of this study was to test the hypothesis that sagittal movement at the low back is not confined to the lumbar spine. The range of sagittal movement and the amount of skin distraction during trunk flexion was studied in 10 normal subjects. Angular movement in the sagittal plane between the vertebra prominens and S2 ranged between 40 degree and 83 degree among the subjects. Concomitant skin distraction showed that a mean of 32% (range 20-41%) of the movement between the upper thorax and sacropelvis occurred cranial to T12. We therefore suggest that the term "low back" should be applied to a series of mobile vertebrae in the lower thoracic and lumbar spines and that motion of this region in the sagittal plane should be considered as the movement of an immobile upper thoracic spine relative to the sacropelvis.

Adult↗
PubMed2002

The role of computerized tomography in the preoperative assessment of chronic suppurative otitis media.

Twenty patients awaiting mastoid surgery for chronic suppurative otitis media underwent preoperative high resolution computerized tomography (CT) of the temporal bones. The CT scans were compared with the intraoperative findings. CT was helpful in determining the anatomy of the middle ear and mastoid, and accurately predicted the extent of the disease process in the sinus tympani and facial recess. However, it was unable to distinguish between cholesteatoma, mucosal disease and fluid, and it contributed little to the surgical management of the patients. This suggests that routine preoperative CT scanning of patients before uncomplicated virgin mastoid surgery is of questionable value.

Chronic Disease↗
PubMed2002

Effect of perioperative administration of dexketoprofen on opioid requirements and inflammatory response following elective hip arthroplasty.

BACKGROUND: In this double-blind, randomized, placebo-controlled trial, the safety and analgesic efficacy of perioperative dexketoprofen were evaluated. METHODS: Thirty ASA I or II patients undergoing elective hip arthroplasty were randomized to one of two groups. One group (D) received dexketoprofen 25 mg tds for 24 h before and 48 h after surgery; the second group (P) received placebo tablets at equivalent times. Hyperbaric 0.5% bupivacaine (17.5 mg if greater than 70 kg and 15 mg if less than 70 kg) and preservative-free morphine (0.6 mg) were administered intrathecally. Postoperatively, PCA was provided (bolus morphine sulphate 1 mg; lockout 5 min; no continuous infusion). RESULTS: The two groups were similar in terms of age, gender, weight, height, ASA class, duration of operation, and level of sensory block on arrival to the recovery room. Groups were also similar in terms of blood loss, transfusion requirements, ventilatory frequency, and haemodynamic variables. According to visual analogue pain scores patients in group D experienced less pain at 15 h (P=0.02) postoperatively. Cumulative morphine consumption was also less in group D compared with group P at 6 (0.06 (0.2) vs 0.85 (1.4) mg, P=0.04) and 48 h postoperatively (10.1 (8) vs 26.2 (20) mg, P<0.01). Plasma interleukin 6 concentrations increased postoperatively to a significantly lesser extent in group D than in group P (P=0.02). Nausea and vomiting were less (P<0.01) in group D compared with group P at 18 h postoperatively. Sedation scores were less (P=0.03) in group D. CONCLUSIONS: Perioperative administration of dexketoprofen 25 mg 8 hourly markedly improves analgesia and decreases opioid requirements (and associated adverse effects) following hip arthroplasty. It appears that this regimen decreases the postoperative pro-inflammatory response.

Aged↗
PubMed2002

Mucin gene expression in the ileoanal reservoir is altered and may be relevant to the risk of inflammation and dysplasia.

BACKGROUND: Adaptive colonic phenotypic change of the ileal mucosa is a feature of the ileoanal reservoir (IAR) with time, as described by mucin glycoprotein and histological analysis. Mucin gene expression is altered in colorectal neoplasia and inflammatory bowel disease but little is known of its expression in the IAR. AIMS: To examine the changes in mucin gene expression contributing to mucosal protection of the IAR against a background of known changes occurring in inflammatory disease and colorectal neoplasia. PATIENTS: Paraffin embedded specimens from 29 "W" and 11 "J" ileoanal reservoirs were studied. Colonic and ileal control tissue was obtained from normal resection margins. METHODS: Mucin mRNA was detected by in situ hybridisation using [(35)S]dATP labelled oligonucleotide probes. Mucin core protein was detected by immunohistochemistry. RESULTS: There was no change in mRNA expression of MUC1-4 in the IAR compared with ileal controls but there was a decrease in the protein product of MUC1 and MUC3. No mRNA transcripts of MUC5AC, 5B, or 6 were detected but protein product of MUC5AC and MUC6 was detected. Both cases of MUC6 positivity and 1/5 cases of MUC5AC positivity were confined to the ulcer associated cell lineage. No dysplasia was detected. CONCLUSIONS: There is a change in the pattern of the membrane associated mucins MUC1 and MUC3, part of which is in keeping with changes described in colorectal neoplasia. A small number of cases demonstrated mucin gene changes (MUC5AC) which are seen in early neoplasia and this may provide a valuable monitor for such changes in IAR surveillance.

Child↗
PubMed2002

The experience and training of British general surgeons in trauma surgery for the abdomen, thorax and major vessels.

BACKGROUND: The report Better Carefor the Severely Injured [London: The Royal College of Surgeons of England and the British Orthopaedic Association; 2000] states that an experienced general surgeon trained in the techniques required to perform life-saving emergency surgery is vital in the management of major trauma. The experience and training of general surgeons in the UK in the management of trauma to the abdomen, thorax and major vessels has never been assessed. METHOD: Postal questionnaire sent to UK general surgical consultants and Higher Surgical Trainees (HSTs). RESULTS: A total of 854 (48%) questionnaires were completed. Of respondents, 85% believe that major trauma should be directed to hospitals that provide a dedicated trauma service. Of non-vascular specialists, 43% felt their training was adequate to manage vascular trauma and only one-third of general surgical consultants felt adequately prepared to manage acute cardiothoracic injuries. The median number of trauma laparotomies undertaken annually was 2 for blunt injury and 1 for penetrating injury. Of HSTs, 21% had not performed a splenectomy for trauma and 44% had no experience of packing for liver injuries. CONCLUSIONS: There is limited experience and training in the surgical management of torso trauma in the UK. Implementation of the recommendations from Better Care for the Severely Injured will be hampered unless steps are taken to maximise experience and improve training.

Abdominal Injuries↗