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B. W. Metcalfe,T. N. Nielsen,N. de N. Donaldson,A. J. Hunter,J. T. Taylor 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.1
Neural interfaces have great potential to treat disease and disability by modulating the electrical signals within the nervoussystem. However, whilst neural stimulation is a well-established technique, current neural interfaces are limited by poorrecording ability. Low signal amplitudes necessitate the use of highly invasive techniques that divide or penetrate thenerve, and as such are unsuitable for chronic implantation. In this paper, we present the first application of the velocityselective recording technique to the detection of respiration activity in the vagus nerve, which is involved with treatmentsfor epilepsy, depression, and rheumatoid arthritis. Further, we show this using a chronically implantable interface that doesnot divide the nerve. We also validate our recording setup using electrical stimulation and we present an analysis of therecorded signal amplitudes. The recording interface was formed from a cuff containing ten electrodes implanted around theintact right vagus nerve of a Danish Landrace pig. Nine differential amplifiers were connected to adjacent electrodes, andthe resulting signals were processed to discriminate neural activity based on conduction velocity. Despite the averagesingle channel signal-to-noise ratio of - 5.8 dB, it was possible to observe distinct action potentials travelling in bothdirections along the nerve. Further, contrary to expectation given the low signal-to-noise ratio, we have shown that it waspossible to identify afferent neural activity that encoded respiration. The significance of this is the demonstration of achronically implantable method for neural recording, a result that will transform the capabilities of future neuroprostheses.
Ahmed Elbasty,James Metcalf 대한혈관외과학회 2017 Vascular Specialist International Vol.33 No.4
Purpose: Catheter direct thrombolysis (CDT) has been shown to be an effective treatment for deep venous thrombosis. The objective of the review is to improve safety and efficacy of the CDT by using ward based protocol, better able to predict complications and treatment outcome through monitoring of haemostatic parameters and clinical observation during thrombolysis procedure. Materials and Methods: MEDLINE, EMBASE, CENTRAL and Web of Science were searched for all articles on deep venous thrombosis, thrombolysis and correlations of clinical events (bleeding, successful thrombolysis) during thrombolysis with hemostatic parameters to March 2016. The risk of bias in included studies was assessed by Cochrane Collaboration’s tool and Cochrane Risk of Bias Assessment Tool: for Non-Randomized Studies of Interventions. Results: Twenty-four studies were included in the review and we found that improving safety and efficacy of CDT by using ward based protocol depending on eight factors; strict patient selection criteria, types of fibrinolytic drugs, mode of fibrinolytic drug injection, biochemical markers monitoring (fibrinogen, D-dimer, activated partial thromboplastin time, plasminogen activator inhibitor-1), timing of intervention, usage of intermittent pneumatic calf, ward monitoring and thrombolysis imaging assessment (intravascular ultrasound). These factors may help to improve safety and efficacy by reducing total thrombolytic drug dosage and at the same time ensure successful lysis. There is a marked lack of randomized controlled trials discussing the safety and efficacy of catheter direct thrombolysis. Conclusion: CDT can be performed safely and efficiently in clinical ward, providing that careful nursing, biochemical monitoring, proper selection and mode of infusion of fibrinolytic drugs, usage of Intermittent pneumatic calf and adequate thrombolysis imaging assessment are ensured.
The EU`s New Economic Geography after the Eastern Enlargement
( Helena Marques ),( Hugh Metcalf ) 세종대학교 경제통합연구소 2003 Journal of Economic Integration Vol.18 No.4
Using a centre-two periphery new economic geography model we study the location and real wage effects of the EU`s Eastern enlargement on current and future EU member countries under pure trade integration and with migration of skilled labour. The quality of final and intermediate products differs across countries according to their effective endowments of human capital engaged in R&D. Allowing for migration prevents the relocation of firms into the integrating periphery. Moreover, the location of firms differs according to the sectors` skill and R&D intensity, low skill and low R&D firms tending to locate in the Eastern and Southern peripheries.
Extra-fine Ni Powder for Diamond Tool Binder Applications
Stephenson Thomas F.,Korotkin Maria,Metcalfe Shawn 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
A new extra-fine grade Ni powder (XF Ni) has demonstrated increased sintering activity in Co-Fe-Ni binders for diamond tool applications. XF Ni has the advantage of significantly lower cost than XF Co. Up to 30% of XF Co was substituted with XF Ni while maintaining comparable apparent hardness and transverse rupture strength to pure Co binders. Ni substantially increased the diffusion of Fe. Diamond tool producers can take advantage of the improved sintering properties of XF Ni powder to substantially lower material costs.
Carotid Endarterectomy in the Very Elderly: Short-, Medium-, and Long-Term Outcomes
Shabin Fahad,Sayali Shirsath,Matthew Metcalfe,Ahmed Elmallah 대한혈관외과학회 2023 Vascular Specialist International Vol.39 No.3
Purpose: Carotid endarterectomy (CEA) has an established effect on stroke-free survival in patients with carotid artery stenosis. Most landmark trials excluded patients ≥80 years of age due to their perceived high risk and uncertainty regarding the benefits of CEA. Despite the ongoing global increase in life expectancy, guidelines have not changed. The current study aimed to assess CEA outcomes in patients ≥80 years of age. Materials and Methods: Data from patients ≥80 years of age, who underwent CEA between April 2016 and April 2022, were collected. Demographic information, comorbidities, surgical details, operative details, outcomes, and post-CEA survival were reviewed, and long-term data up to April 2023 were collected. Results: Over the 6-year study period, 258 CEA procedures were recorded, of which 70 (27.1%) were performed in patients ≥80 years of age; the mean age was 84 years (range, 80-96 years), 47 (67.1%) were males, and 69 (98.6%) were symptomatic. Twenty-three (32.9%) patients were American Society of Anesthesiologists (ASA) grade 2, and 47 (67.1%) were grade 3. The 30-day stroke and mortality rates were 4.3% and 1.4%, respectively. At 1, 3, and 5 years, the cumulative freedom-from-stroke rates were 95.7%, 92.9%, and 91.4%, respectively, and the cumulative survival rates were 94.3%, 75.7%, and 61.4%, respectively. No risk factors affected early or late stroke or early mortality rates. Patients with ASA grade 3 had significantly lower cumulative survival than those with grade 2 (HR, 5.29; 95% CI, 1.590-17.603; P<0.01). Conclusion: CEA was safe and effective in average-risk, elderly patients. Higher risk patients (i.e., ASA 3) showed no increased 30-day risk for stroke or mortality but exhibited significantly worse long-term survival. Hence, careful consideration of the benefits before performing CEA is crucial.
Enhanced Properties of Extra-fine Nickel Steels for PM Gears
Stephenson Thomas F.,Korotkin Maria,Metcalfe Shawn 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Highly compressible Ni-Mo steels are attractive materials for PM due to high sinter density and ease of processing. Extra-fine Ni admixed PM steels have demonstrated improved mechanical properties and rolling contact fatigue resistance due to a more uniform microstructure and increased Ni diffusion during sintering. Sinter densities of single press single sinter XF Ni-Mo steels can approach at moderate compaction pressures. Leaner alloys based on extra-fine Ni powder are possible depending on the performance requirements of the PM steel part. Extra-fine Ni steels are particularly attractive for the growing market of high performance PM gears and sprockets.