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Transcranial Doppler emboli monitoring for stroke prevention after flow diverting stents
Matias Costa,Paul Schmitt,Jaleel N,Matias Baldoncini,Juan Vivanco-Suarez,Bipin Chaurasia,Colleen Douville,Loh Yince,Akshal Patel,Stephen Monteith 대한뇌혈관외과학회 2024 Journal of Cerebrovascular and Endovascular Neuros Vol.26 No.1
Objective: Flow diverting stents (FDS) are increasingly used for the treatment of intracranial aneurysms. While FDS can provide flow diversion of parent vessels, their high metal surface coverage can cause thromboembolism. Transcranial Doppler (TCD) emboli monitoring can be used to identify subclinical embolic phenomena after neurovascular procedures. Limited data exists regarding the use of TCDs for emboli monitoring in the periprocedural period after FDS placement. We evaluated the rate of positive TCDs microembolic signals and stroke after FDS deployment at our institution.Methods: We retrospectively evaluated 105 patients who underwent FDS treatment between 2012 and 2016 using the Pipeline stent (Medtronic, Minneapolis, MN, USA). Patients were pretreated with aspirin and clopidogrel. All patients were therapeutic on clopidogrel pre-operatively. TCD emboli monitoring was performed immediately after the procedure. Microembolic signals (mES) were classified as “positive” (<15 mES/hour) and “strongly positive” (>15 mES/hour). Clinical stroke rates were determined at 2-week and 6-month post-operatively.Results: A total of 132 intracranial aneurysms were treated in 105 patients. TCD emboli monitoring was “positive” in 11.4% (n=12) post-operatively and “strongly positive” in 4.8% (n=5). These positive cases were treated with heparin drips or modification of the antiplatelet regimen, and TCDs were repeated. Following medical management modifications, normalization of mES was achieved in 92% of cases. The overall stroke rates at 2-week and 6-months were 3.8% and 4.8%, respectively.Conclusions: TCD emboli monitoring may help early in the identification of thromboembolic events after flow diversion stenting. This allows for modification of medical therapy and, potentially, preventionf of escalation into post-operative strokes.
Reactive Co-Evaporation of YBCO for Coated Conductors
Matias, V.,Hanisch, J.,Sheehan, C.,Ugurlu, O.,Storer, J. The Korean Society of Superconductivity and Cryoge 2007 한국초전도저온공학회논문지 Vol.9 No.4
We describe methods for depositing high temperature superconducting films on textured metal tapes by reactive co-evaporation (RCE). We discuss how RCE can be used to deposit on moving tape in a continuous fashion in a Garching-style process. Results are presented on films deposited by RCE at Los Alamos on IBAD-MgO textured tapes. The performance achieved, attaining over 500A/cm-width in self-field at 75.5 K, is competitive with the best results obtained by other processes for coated conductors. Tape production throughput is critical for the economics of the process and high deposition rates achieved in RCE are attractive for this. We present a detailed cost analysis model for HTS deposition using an RCE Garching process. The results indicate that HTS deposition can cost $<$5/kA{\cdot}m$ in a scaled up manufacturing environment.
Matias Scherer Lunkes 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.3
Polysaccharides are commonly used as binders in metal oxide colloidal processing. However, if the macromolecular chains areable to adsorb on ceramic particles surface, the suspension deflocculating properties are also favored. This paper investigatedthe use of dextrin as a bio-dispersant on structural and morphological properties of Al2O3 materials. The interactionmechanism between dextrin and Al2O3 surface and the additive efficiency of producing less agglomerated systems werediscussed. The suspensions behavior was pH-dependent, being the pH 6 the best condition for obtaining more compact systemsin dextrin presence. The first monolayer saturation of the Al2O3 active sites occurred at 1.5 wt. % of dextrin and a secondadsorption layer started above this additive concentration. The highest percentage of densification was 96.25% for thesuspension containing 30 vol. % solids and 1 wt. % dextrin. The presence of dextrin also influenced the microstructure of thesystems, providing a better bridging between Al2O3 particles. The use of dextrin at low dosages proved to be efficient in thestabilization of aqueous alumina suspensions.
On some solutions of a functional equation related to the partial sums of the Riemann zeta function
Juan Matias Sepulcre Martinez 대한수학회 2014 대한수학회보 Vol.51 No.1
In this paper, we prove that infinite-dimensional vector spaces of $\alpha$-dense curves are generated by means of the functional equations $f(x)+f(2x)+\cdots+f(nx)=0$, with $n\geq 2$, which are related to the partial sums of the Riemann zeta function. These curves $\alpha$-densify a large class of compact sets of the plane for arbitrary small $\alpha$, extending the known result that this holds for the cases $n=2,3$. Finally, we prove the existence of a family of solutions of such functional equation which has the property of quadrature in the compact that densifies, that is, the product of the length of the curve by the $n^{th}$ power of the density approaches the Jordan content of the compact set which the curve densifies.
Ivair Matias Júnior,Priscila Medeiros,Renato Leonardo de Freita,Hilton Vicente-César,José Raniery Ferreira Junior,Hélio Rubens Machado,Rafael Menezes-Reis 대한척추신경외과학회 2019 Neurospine Vol.16 No.2
Objective: Chronic constriction injury (CCI) of the sciatic nerve is a peripheral nerve injury widely used to induce mononeuropathy. This study used machine learning methods to identify the best gait analysis parameters for evaluating peripheral nerve injuries. Methods: Twenty-eight male Wistar rats (weighing 270±10 g), were used in the present study and divided into the following 4 groups: CCI with 4 ligatures around the sciatic nerve (CCI-4L; n=7), a modified CCI model with 1 ligature (CCI-1L; n=7), a sham group (n=7), and a healthy control group (n=7). All rats underwent gait analysis 7 and 28 days postinjury. The data were evaluated using Kinovea and WeKa software (machine learning and neural networks). Results: In the machine learning analysis of the experimental groups, the pre-swing (PS) angle showed the highest ranking in all 3 analyses (sensitivity, specificity, and area under the receiver operating characteristics curve using the Naive Bayes, k-nearest neighbors, radial basis function classifiers). Initial contact (IC), step length, and stride length also performed well. Between 7 and 28 days after injury, there was an increase in the total course time, step length, stride length, stride speed, and IC, and a reduction in PS and IC-PS. Statistically significant differences were found between the control group and experimental groups for all parameters except speed. Interactions between time after injury and nerve injury type were only observed for IC, PS, and IC-PS. Conclusion: PS angle of the ankle was the best gait parameter for differentiating nonlesions from nerve injuries and different levels of injury.
Murilo Matias,Carlos Flores-Mir,Marcio Rodrigues de Almeida,Bruno da Silva Vieira,Karina Maria Salvatore de Frei,Daniela Calabrese Nunes,Marcos Cezar Ferreira,Weber Ursi 대한치과교정학회 2021 대한치과교정학회지 Vol.51 No.6
Objective: To identify optimal areas for the insertion of extra-alveolar miniscrews into the infrazygomatic crest (IZC) and mandibular buccal shelf (MBS), using cone beam computed tomography (CBCT) imaging in patients with different craniofacial patterns. Methods: CBCT reconstructions of untreated individuals were used to evaluate the IZC and MBS areas. The participants were divided into three groups, based on the craniofacial pattern, namely, brachyfacial (n = 15; mean age, 23.3 years), mesofacial (n = 15; mean age, 19.24 years), and dolichofacial (n = 15; mean age, 17.79 years). In the IZC, the evaluated areas were at 11, 13, and 15 ㎜ above the buccal cusp tips of the right and left first molars. In the MBS, the evaluated areas were at the projections of the first molars’ distal roots and second molars’ mesial and distal roots, at a 4- and 8-㎜ distance from the cementoenamel junction. Intergroup comparisons were performed with analysis of variance and the Tukey test. Results: There was no statistically significant difference in the IZC bone thickness among the groups. For MBS bone availability, some comparisons revealed no difference; meanwhile, other comparisons revealed increased MBS bone thickness in the brachyfacial (first molars distal roots) and dolichofacial (second molars mesial and distal roots) patterns. Conclusions: There was no significant difference in the IZC bone thickness among the groups. The facial skeletal pattern may affect the availability of ideal bone thickness for the insertion of extra-alveolar miniscrews in the MBS region; however, this variability is unlikely to be clinically meaningful.