An asteroseismic test of diffusion theory in white dwarfs

Metcalfe, T. S.,Nather, R. E.,Watson, T. K.,Kim, S.-L.,Park, B.-G.,Handler, G. SPRINGER VERLAG KG 2005 Astronomy and astrophysics Vol.435 No.2

First demonstration of velocity selective recording from the pig vagus using a nerve cuff shows respiration afferents

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.

Hippocampal–Prefrontal Engagement and Dynamic Causal Interactions in the Maturation of Children's Fact Retrieval

Cho, Soohyun,Metcalfe, Arron W. S.,Young, Christina B.,Ryali, Srikanth,Geary, David C.,Menon, Vinod MIT Press 2012 JOURNAL OF COGNITIVE NEUROSCIENCE Vol.24 No.9

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.

Glucocorticoid Hormones Decrease the Proliferation and Viability of Cultured Mast Cells

Min, Kyung Up,Costa, John, J.,Metcalfe, Dean D. 대한알레르기학회 1989 천식 및 알레르기 Vol.9 No.3

The local administration of glucocorticoid hormones decreases tissue mast cell numbers. To explore the direct effect of steroids on mast cells, we cultured the interleukin 3 dependent murine mast cell line, PT-18, in interleukin-3 containing WEHI-3 conditioned medium in the presence or absence of dexamethasone. Viable cell counts, and tritiated thymidine, uridine and leucine incorporation were compared in the daxamethasone treated and control mast cell populations. Both cell viability and the uiable cell count decreased in a dose dependent manner. At low concentration of dexamethasone, cell viability was maintained while cell proliferation was inhibited. Exposure of mast cells to dexamethasone (10 M for 24hrs) cause inhibition of thymidine, uridine and leucine incorporation to 9,5.2% 78.3% and 82.2% of control values respectively. This effect could not be reuersed by increasing the concentration of IL-3 in the culture medium. The effects of dexamethasone on rat basophilic leukemia cells, HL-60 cells and rat embryo dermal fibroblasts were also examined. Inhibition of thymidine incorporation was limited to the rat basophilic leukemia cells. We conclude that dexamethasone acts as a growth inhibiting and ultimately, cytotoxic agent on mast cells.

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.

A REVISED EFFECTIVE TEMPERATURE SCALE FOR THE <i>KEPLER</i> INPUT CATALOG

Pinsonneault, Marc H.,An, Deokkeun,Molenda-Ż,akowicz, Joanna,Chaplin, William J.,Metcalfe, Travis S.,Bruntt, Hans IOP Publishing 2012 The Astrophysical journal Supplement series Vol.199 No.2

Development of integrated waste management options for irradiated graphite

Alan Wareing,Liam Abrahamsen-Mills,Linda Fowler,Michael Grave,Richard Jarvis,Martin Metcalfe,Simon Norris,Anthony William Banford 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.5

The European Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste projectsought to develop best practices in the retrieval, treatment, and disposal of irradiated graphite includingother irradiated carbonaceous waste such as structural material made of graphite, nongraphitized carbonbricks, and fuel coatings. Emphasis was given on legacy irradiated graphite, as this represents a significantinventory in respective national waste management programs. This paper provides an overview ofthe characteristics of graphite irradiated during its use, primarily as a moderator material, within nuclearreactors. It describes the potential techniques applicable to the retrieval, treatment, recycling/reuse, anddisposal of these graphite wastes. Considering the lifecycle of nuclear graphite, from manufacture to finaldisposal, a number of waste management options have been developed. These options consider thetechniques and technologies required to address each stage of the lifecycle, such as segregation, treatment,recycle, and ultimate disposal in a radioactive waste repository, providing a toolbox to aid operatorsand regulators to determine the most appropriate management strategy. It is noted that nationalwaste management programs currently have, or are in the process of developing, respective approachesto irradiated graphite management. The output of the Treatment and Disposal of Irradiated Graphite andother Carbonaceous Waste project is intended to aid these considerations, rather than dictate them.

Management of mucoid degeneration of the anterior cruciate ligament: a systematic review

( Tamer Sweed ),( Mohamed Mussa ),( Ahmed El-bakoury ),( Guido Geutjens ),( Andrew Metcalfe ) 대한슬관절학회 2021 대한슬관절학회지 Vol.33 No.-

Purpose: The purpose of this study was to investigate the outcomes of management of mucoid degeneration of the anterior cruciate ligament (MDACL) by performing a systematic review of methods of treatment that have been reported. Methods: A systematic literature search in the databases MEDLINE, Embase, Google Scholar, Cochrane, ISI web of science and Scopus was performed through July 2020 by three independent reviewers. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and registered in the PROSPERO database (CRD42018087782). Quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria. Results: A total of nine studies were eligible for review. All nine studies assessed the outcome of arthroscopic debridement of MDACL. A total of 313 knees in 292 patients were included. The mean follow up ranged from 13 to 72 months. There was strong association between MDACL and chondral lesions (82%) and between MDACL and meniscal tears (69%). The rate of simultaneous meniscectomy ranged from 13 to 44%. Postoperative pain relief ranged from 53.8 to 95%. There was an improvement in postoperative range of motion and outcome scores (Lysholm and International Knee Documentation Committee scores and the Knee Injury and Osteoarthritis Outcome Score). Postoperative Lachman test was positive in 40% of patients, and 6% of patients had symptomatic instability. The mean MINORS score was 9.5 out of 16 (4-12). Conclusions: Arthroscopic debridement of the anterior cruciate ligament (ACL) results in satisfactory pain relief and improvement in knee outcome scores. Postoperative ACL laxity is common after arthroscopic ACL debridement, however, symptomatic instability is not. The need for delayed ACL reconstruction should be discussed preoperatively, especially if complete resection of the ACL is to be performed. Level of evidence: IV