3,567 research outputs found
Platform for in-situ manufacturing of underground cable
No full textThesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018Supervised by Alexander H. Slocum. Cataloged from PDF of thesis. Vitae.Includes bibliographical references (pages 83-86).As the demand for and viability of renewable energies has increased, connecting remote power generation stations to demand centers has become more important. High Voltage Direct Current (HVDC) transmission systems offer efficiency and cost effectiveness over long distances, allow for the linkage of incompatible AC grids, and can be immune to telluric currents and aggressive EMP attacks, which all make these systems particularly applicable to connecting to remote renewables. With the current state-of-the-art in HVDC, overhead lines (OHL) are several times cheaper than underground cables (UGC). However, OHLs have security risks and create substantial visual pollution, which has resulted in significant public opposition and lengthy delays in project permitting. Project developers have reluctantly agreed to replace portions of overhead line with underground cable as a concession to these stakeholders. One way to make UGCs more attractive to developers is to reduce cost by locating UGC systems along railroad right of ways. The increased mobility of heavy machines and materials on railroads and the state-of-the-art in railroad construction machinery provide both precedent and process advantages, which make the concept of augmenting railroads with underground cable systems an attractive one. The practice of installing and maintaining such systems could be less complex than traditional methods required by independent transmission corridors. The use of private railways may avoid conflicts with external stakeholders and eliminate the regulatory delays that have plagued many renewable energy transmission projects. Additionally, taking advantage of the increased accessibility of railroads by in-situ manufacturing high voltage, extruded cable in lengths far greater than what is currently able to be transported by road haulage, may reduce overall project costs by eliminating expensive and vulnerable cable splices. To accomplish this, here we present a method for continuously manufacturing and installing high voltage undergourd cable from a moving "Cable Train" using public-private railway systems. There are three primary challenges associated with such a mobile platform -- extrusion, curing, and degassing. Several promising countermeasures have been presented, which require varying levels of further development continuous extrusion, horizontal curing, and inline degassing. Herein, further discussions on standards, system topology, earthworks, practical limitations to cable production length, and cost estimation, can also be found. The technology and methods to accomplish this vision can be achieved by a pre-competitive technology consortium with member companies capable of completing and fully realizing the proof-of-concept designs proposed.by Luke A. Gray, Alexander H. Slocum and Qi Du.S.B.S.B. Massachusetts Institute of Technology, Department of Mechanical Engineerin
Response to Cardiac Resynchronization Therapy Across Chronic Kidney Disease Stages
Full text linkINTRODUCTION: Limited data is available on the effect of severe chronic kidney disease (CKD) on the response to cardiac resynchronization therapy (CRT) as these patients are often excluded from trials. We therefore aimed to assess the effect of CRT on renal function, reverse remodeling and outcome across all stages of CKD in a large patient population of CRT recipients.METHODS: 798 consecutive heart failure (HF) patients undergoing CRT implantation between October 2008 and September 2016 were retrospectively evaluated. Renal function was available at baseline and 6 months following CRT. Remodeling based on LVESV/LVEF and clinical outcome was assessed using a combined endpoint of all-cause mortality and HF hospitalization.RESULTS: Median baseline eGFR was 62.8 [43.6-77.8] ml/min/1.73m2. 33.6% of patients were in CKD stage 3, 11.0% in stage 4, and 1.1% in stage 5. LVEF and LVESV improved across all CKD stages, however patients with CKD stage 1-2 exhibited a greater degree of improvement in LVEF (median 15% vs. 10%, P<0.001) and LVESV (median -37.2% vs. -29.9%, P<0.001) compared to patients with CKD stage 3-5. Despite a greater degree of reverse remodeling in CKD stage 1-2, the most accurate cutoff of remodeling predicting good clinical outcome was lower for patients with CKD stage 3-5, respectively 5.5% vs. 9.5% (LVEF), and -6.67% vs. -12.41% (LVESV).CONCLUSIONS: CRT results in reverse remodeling across all stages of CKD, although to a lesser extent in patients with renal dysfunction (CKD stage 3-5). However, patients with CKD derive benefit on outcome at a lesser degree of remodeling.</p
„Natur muss gefühlt werden“ – Alexander von Humboldt, Vordenker einer ökologischen Weltsicht und Protagonist „transversaler Vernunft“
No full textDer Text erinnert zum 250sten Geburtsjahr an Alexander von Humboldt, ein Vordenker für eine ökologische Sicht der Welt und ein früher Protagonist „transversaler Vernunft“. Er ist als Ideengeber für die „neuen Naturtherapien“, für die Integrative Therapie und für eine ökologische Sicht in der Psychotherapie eine unverzichtbare Quelle. Einige aus dieser Perspektive wichtige Aspekte seines Denkens und Werkes werden aufgezeigt. Er ist ein Referenzautor für transversales und integratives Konzeptualisieren in unserer Zeit.The text commemorates the 250th year of birth of Alexander von Humboldt, a thought leader for an ecological view of the world and an early protagonist of „transversal reason“. He is an indispensable source of ideas for the „new nature therapies“, for integrative therapy and for an ecological viewpoint in psychotherapy. Some important aspects of his thinking and work are shown from this perspective. He is a reference author for transversal and integrative conceptualization in our time.https://www.fpi-publikation.de/polyloge/25-2019-petzold-h-g-mathias-wiedemann-u-natur-muss-gefuehlt-werden-alexander-v-humboldt/peerReviewedpublishedVersio
„Nature must be felt“ – Alexander von Humboldt, pioneer of an ecological worldview and protagonist of „transversal reason“
No full textDer Text erinnert zum 250sten Geburtsjahr an Alexander von Humboldt, ein Vordenker für eine ökologische Sicht der Welt und ein früher Protagonist „transversaler Vernunft“. Er ist als Ideengeber für die „neuen Naturtherapien“, für die Integrative Therapie und für eine ökologische Sicht in der Psychotherapie eine unverzichtbare Quelle. Einige aus dieser Perspektive wichtige Aspekte seines Denkens und Werkes werden aufgezeigt. Er ist ein Referenzautor für transversales und integratives Konzeptualisieren in unserer Zeit.The text commemorates the 250th year of birth of Alexander von Humboldt, a thought leader for an ecological view of the world and an early protagonist of „transversal reason“. He is an indispensable source of ideas for the „new nature therapies“, for integrative therapy and for an ecological viewpoint in psychotherapy. Some important aspects of his thinking and work are shown from this perspective. He is a reference author for transversal and integrative conceptualization in our time.https://www.fpi-publikation.de/gruene-texte/17-2019-petzold-h-g-mathias-wiedemann-u-natur-muss-gefuehlt-werden-alexander-v-humboldt/peerReviewedpublishedVersio
Immediate-early gene induction by repetitive mechanical but not electrical activity in adult rat cardiomyocytes.
No full textpeer reviewedMechanical factors are thought to play an important role in the induction of myocardial hypertrophy. Yet, it is not known whether active contraction induces genes that probably represent initial steps in the hypertrophic response in the adult myocardium--and if so, whether the mechanical or the electrical component of the twitch governs this response. We therefore investigated whether electrical stimulation of contraction was able to induce the immediate-early genes (IEGs) egr-1 and c-fos in adult rat cardiomyocytes. Cyclical contraction led to an increase in egr-1 and c-fos mRNA levels within 30 min. Full inhibition of contraction during electrostimulation by the Ca(2+)-desensitizer 2,3-butanedione monoxime (BDM) totally blocked this IEG-response without altering membrane potential. These data suggest that in adult myocardium, the mechanical rather than the electrical activity is responsible for the IEG-response during active twitch
Letter by Maass and Maier Regarding Article, "Cardiac Arrhythmogenic Remodeling in a Rat Model of Long-Term Intensive Exercise Training"
No full textAn annotated catalogue of selected works for clarinet by South African composers
No full textThe dissertation consists of an annotated catalogue of nineteen selected works for clarinet by South African composers. These are presented in chronological order, based on the year of composition. A short biographyof the composer is given before the work is discussed. Of the analysed works, all those for solo clarinet or for clarinet and piano have been graded. A thesis of a similar nature, written in 1989 by L.A. Hartshorne, entitled ""The Compositions for Clarinet by South African Composers"", contains details of twenty-four works written between 1928 and circa 1981. The majority of the compositions analysed in the current dissertation were written from around 1981 onwards, and to some extent, therefore, this research could be seen as complementary to the information contained in the aforementioned thesis. An addendum lists all the South African works featuring solo clarinet that the author was able to trace. These include solo works, cham ber works for up to nineteen instruments and concerto-type works with strings or orchestra
Author Correction: Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks
Full text linkChange history: In this Letter, Alexander Groisman should have been listed as an author. This error has been corrected online
Acute echocardiographic and electrocardiographic effects of triggered left ventricular pacing
Full text linkCardiac resynchronization therapy (CRT) is an essential pillar in the therapy of heart failure patients with reduced ejection fraction (HFrEF) presenting with broad left bundle branch block (LBBB) or pacemaker dependency. To achieve beneficial effects, CRT requires high bi-ventricular (BiV) pacing rates. Therefore, device-manufacturers designed pacing algorithms which maintain high BiV pacing rates by a left ventricular (LV) pacing stimulus immediately following a right ventricular sensed beat. However, data on clinical impact of these algorithms are sparse. We studied 17 patients implanted with a CRT device providing triggered left ventricular pacing (tLVp) in case of atrioventricular nodal conduction. Assessment of LV dyssynchrony was performed using echocardiographic and electrocardiographic examination while CRT-devices were set to three different settings: 1. Optimized bi-ventricular-stimulation (BiV); 2. Physiological AV nodal conduction (tLVp-off); 3. Physiological AV nodal conduction and tLVp-algorithm turned on (tLVp-on). QRS duration increased when the CRT-device was set to tLVp-off compared to BiV-Stim, while QRS duration was comparable to BiV-Stim with the tLVp-on setting. Echocardiographic analysis revealed higher dyssynchrony during tLVp-off compared to BiV-Stim. TLVp-on did not improve LV dyssynchrony compared to tLVp-off. QRS duration significantly decreased using tLVp-algorithms compared to physiological AV nodal conduction. However, echocardiographic examination could not show functional benefit from tLVp-algorithms, suggesting that these algorithms are inferior to regular biventricular pacing regarding cardiac resynchronization. Therefore, medical treatment and ablation procedures should be preferred, when biventricular pacing rates have to be increased. TLVp-algorithms can be used in addition to these treatment options
Métricas de autor Alexander Sellamén-Garzón
No full textInforme de las métricas de autor del Dr. Alexander Sellamén-Garzón de las publicaciones indexadas en Google Académico cuyo objetivo es entregar un insumo para el fortalecimiento de las capacidades y potencialidades de los autores de la Universidad Santo Tomás en el posicionamiento y visibilidad de sus publicacionesReport of the author metrics Alexander Sellamén-Garzón of the publications indexed in Google Scholar whose objective is to provide an input for the strengthening of the capacities and potentialities of the authors of the Santo Tomás University in the positioning and visibility of their publicationshttp://unidadinvestigacion.usta.edu.c
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