• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1466
  • 847
  • 259
  • 251
  • 176
  • 133
  • 87
  • 45
  • 34
  • 27
  • 25
  • 22
  • 18
  • 16
  • 11
  • Tagged with
  • 4005
  • 594
  • 345
  • 275
  • 263
  • 243
  • 223
  • 207
  • 200
  • 186
  • 184
  • 176
  • 170
  • 160
  • 157
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
611

Reversible Nerve Conduction Block Using Low Frequency Alternating Currents

Muzquiz, Maria I. 08 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis describes a novel method to reversibly and safely block nerve conduction using a low frequency alternating current (LFAC) waveform at 1 Hz applied through a bipolar extrafascicular electrode. This work follows up on observations made on excised mammalian peripheral nerves and earthworm nerve cords. An in-situ electrophysiology setup was used to assess the LFAC waveform on propagating action potentials (APs) within the cervical vagus nerve in anaesthetized Sprague-Dawley rats (n = 12). Two sets of bipolar cuff or hook electrodes were applied unilaterally to the cervical vagus nerve, which was crushed rostral to the electrodes to exclude reflex effects on the animal. Pulse stimulation was applied to the rostral electrode, while the LFAC conditioning waveform was applied to the caudal electrode. The efferent volley, if unblocked, elicits acute bradycardia and hypotension. The degree of block of the vagal stimulation induced bradycardia was used as a biomarker. Block was assessed by the ability to reduce the bradycardic drive by monitoring the heart rate (HR) and blood pressure (BP) during LFAC alone, LFAC with vagal stimulation, and vagal stimulation alone. LFAC applied via a hook electrode (n = 7) achieved 86.6 +/- 11% block at current levels 95 +/- 38 uAp (current to peak). When applied via a cuff electrode (n = 5) 85.3 +/- 4.60% block was achieved using current levels of 110+/-65 uAp. Furthermore, LFAC was explored on larger vagal afferent fibers in larger human sized nerve bundles projecting to effects mediated by a reflex. The effectiveness of LFAC was assessed in an in-situ electrophysiological setup on the left cervical vagus in anaesthetized domestic swine (n = 5). Two bipolar cuff electrodes were applied unilaterally to the cervical vagus nerve, which was crushed caudal to the electrodes to eliminate cardiac effects. A tripolar extrafascicular cuff electrode was placed most rostral on the nerve for recording of propagating APs induced by electrical stimulation and blocked via the LFAC waveform. Standard pulse stimulation was applied to the left cervical vagus to induce the Hering-Breuer reflex. If unblocked, the activation of the Hering-Breuer reflex would cause breathing to slow down and potentially cease. Block was quantified by the ability to reduce the effect of the Hering-Breuer reflex by monitoring the breathing rate during LFAC alone, LFAC and vagal stimulation, and vagal stimulation alone. LFAC achieved 87.2 +/- 8.8% (n = 5) block at current levels of 0.8 +/- 0.3 mAp. Compound nerve action potentials (CNAP) were monitored directly. They show changes in nerve activity during LFAC, which manifests itself as the slowing and amplitude reduction of components of the CNAPs. Since the waveform is balanced, all forward reactions are reversed, leading to a blocking method that is similar in nature to DC block without the potential issues of toxic byproduct production. These results suggest that LFAC can achieve a high degree of nerve block in both small and large nerve bundles, resulting in the change in behavior of a biomarker, in-vivo in the mammalian nervous system at low amplitudes of electrical stimulation that are within the water window of the electrode.
612

Different Mode of Afferents Determines the Frequency Range of High Frequency Activities in the Human Brain: Direct Electrocorticographic Comparison between Peripheral Nerve and Direct Cortical Stimulation / ヒトの大脳皮質の高周波活動の周波数帯域は求心性入力機構の相違により規定される:末梢神経刺激と直接皮質刺激による皮質脳波の比較

Kobayashi, Katsuya 24 September 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19273号 / 医博第4037号 / 新制||医||1011(附属図書館) / 32275 / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邉 大, 教授 村井 俊哉, 教授 高橋 淳 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
613

Analysis of Λ(1405) based on chiral SU(3) dynamics / カイラルSU(3)動力学に基づくΛ(1405)の解析

Miyahara, Kenta 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20914号 / 理博第4366号 / 新制||理||1626(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 國廣 悌二, 教授 川合 光, 教授 永江 知文 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
614

Hyperheavy Nuclei in Axial Relativistic Hartree-Bogoliubov Calculations

Gyawali, Abhinaya 10 August 2018 (has links)
The existence of highest proton numbers at which the nuclear landscape cease to ex- ist, the end of the periodic table of elements and the limits of the existence of the nu- clei are some of the difficult questions to answer. To explore those questions, we in- vestigated hyperheavy nuclei (Z ≥ 126) using covariant density functional theory. We demonstrate the existence of three regions of spherical hyperheavy nuclei centered around (Z ∼ 138, N ∼ 230), (Z ∼ 156, N ∼ 310) and (Z ∼ 174, N ∼ 410). Also, we explored other properties of hyperheavy nuclei such as octupole deformation, alpha decay half lives, chemical potential, etc.
615

Inherent Electric Field Measurements of Liquid Surfaces using Ionizing Surface Potential

Adel, Tehseen January 2021 (has links)
No description available.
616

Prediction of Detonation Performance of CHNO Explosives

Abrahamsson, Anders January 2022 (has links)
Produktion av nya energetiska material är dyrt. Målet med detta arbete är att utveckla en metod som uppskattar Chapman-Jouget detonationstrycket och detonationshastigheten hos nya CHNO-sprängämnen. En sådan metod möjliggör valet att bara syntetisera och testa de mest lovande kandidaterna som nya energetiska material, därmed undviks resursslösande arbete. Den här metoden använder sig av density functional theory (DFT) och den elektrostatiska potentialen till att uppskatta bildningsentalpier och kristalldensiteter. Beräkningarna gjordes på traditionella sprängämnen och de beräknade detonationstrycken och detonatioshastigheterna visade bra överensstämmelse med experimentell data. Detonationstrycken hamnade inom ±10% och detonatioshastigheterna inom ±5% av experimentell data. / Producing new energetic materials is expensive. This work aims to develop a method of estimating the Chapman-Jouget detonation pressure and the detonation velocity of potential new CHNO explosives. This would allow choosing the most promising candidates for synthesis and testing thus avoiding wasting resources. This method utilizes density functional theory (DFT) and the electrostatic potential to estimate heats of formation and crystal densities. The calculations were performed on traditionally used explosives and the calculated detonation pressures and detonation velocities showed good accordance with experimental data. The calculated detonation pressures fell within ±10% and the detonation velocities within ±5% of experimental data.
617

Preparation for Nerve Membrane Potential Readings of a Leech, Laboratory Setup and Dissection Process

Caulfield, Jason Patrick 01 June 2009 (has links) (PDF)
A well documented laboratory setup, leech preparation process, and bio-potential data recording process are needed. Repeatability and quality data recordings are essential and thus dictate the requirements of the laboratory setup and processes listed above. Advances in technology have both helped and hindered this development. While very precise equipment is required to record the low voltage bio-potentials, noisy electronic equipment and wires surrounding the work area provide high levels of interference. Proper laboratory setup and data recording processes, however, limit the unwanted interference. Quality data can only be recorded from a properly handled and prepared leech subject. Proper setup and procedures result in quality recordings which lend a clean signal for furthering the understanding of nerve functionality. The electrophysiology lab at California Polytechnic State University in San Luis Obispo is an example of a proven lab setup for high quality signal capture.
618

Разработка методики оценки экономического потенциала промышленной организации на примере АО «Группа «СВЭЛ» : магистерская диссертация / Development of a methodology for assessing the economic potential of an industrial organization on the example of JSC "SVEL Group"

Кувшинова, Т. А., Kuvshinova, T. A. January 2019 (has links)
Реальные условия функционирования предприятия определяют необходимость проведения анализа уровня экономического потенциала предприятия и его оценки. Результаты анализа уровня экономического потенциала предприятия позволяют выявить уязвимые места, требующие разработки мероприятий по их ликвидации. Использование различных составляющих, входящих в понятие экономического потенциала, позволяет оценить уровень комплексного развития объекта исследования. Проведение анализа экономического потенциала мероприятия позволяет выявить сильные и слабые стороны объекта исследования, а также пути достижения целей, направленных на увеличение степени клиентоориентированности. Цель диссертационного исследования заключается в развитии методических положений по анализу прогнозирования и управления экономическим потенциалом промышленного предприятия, способствующих принятию эффективных управленческих решений и направленных на повышение конкурентоспособности. В ходе написания магистерской диссертации была разработана и апробирована методика оценки уровня экономического потенциала предприятия, в основу которой положено деление на субпотенциалы, что позволит обосновать уровень каждого субпотенциала и оценить, какие показатели оказывают наибольшее влияние на тот или иной субпотенциал, для обеспечения оперативного принятия управленческих решений по корректировке бизнес-процессов промышленного предприятия и его экономического развития. / The real conditions of the enterprise functioning determine the necessity of analyzing the level of the economic potential of the enterprise and its assessment. The results of the analysis of the level of economic potential of the enterprise allow to identify vulnerabilities that require the development of measures to eliminate them. The use of various components included in the concept of economic potential allows us to estimate the level of integrated development of the object of study. An analysis of the economic potential of the event reveals the strengths and weaknesses of the object of study, as well as ways to achieve goals aimed at increasing the degree of customer focus. The purpose of the dissertation research is the development of methodological guidelines for analyzing the forecasting and management of the economic potential of an industrial enterprise, facilitating the adoption of effective management decisions and aimed at improving competitiveness. In the course of writing the master's thesis, a methodology for assessing the level of economic potential of an enterprise was developed and tested, based on dividing into subpotentials, which will justify the level of each subpotential and assess which indicators have the greatest impact on a particular subpotential to ensure rapid management decisions on adjusting the business processes of an industrial enterprise and its economic development.
619

Design, Construction, and Implementation of Ionization Method Surface Potential Instrument For Studies of Charged Surfactants and Inorganic Electrolytes At the Air/Water Interface

Adel, Tehseen January 2017 (has links)
No description available.
620

Evaluation of Dissolved Air Flotation for Water Purification: With Focus on Floc Characteristics and PFAS / Utvärdering av Flotationprocess för Vattenrening: Med Fokus på Flockkaraktär och PFAS

Löf, Ludwig January 2021 (has links)
I detta projekt har experiment utförts med mål att förse kommunalförbundet Norrvatten med data som kan användas som underlag för beslutsfattande angående om deras fällningslinjer i vattenreningsprocessen ska köras i flotation eller sedimentering. För detta ändamål har koncentrationen av poly- och perfluorerade alkylsubstanser (PFAS) samt karaktär av agglomererade partiklar (flockar) undersökts och jämförts mellan fällningslinjer som körs i olika konfigurationer. För flockkaraktär har skapandet och stabiliteten av flockar varit av intresse, eftersom flotation har ett mer turbulent flöde där flockarna riskerar att brista. Partikelstorlek, storleksfördelning och zeta potential identifierades som egenskaper som reflekterar flockarnas karaktär, dessa analyserades i en zetasizer. Koncentrationen av elva vanligt förekommande PFAS ämnen analyserades i projektet. Resultatet av flockkaraktär tyder på att det ej fanns någon större skillnad i skapandet av flockar samt deras stabilitet mellan de olika fällningslinjerna som undersökts. Detta eftersom zeta potentialen var identisk (-6.45 mV) för de analyserade proverna från respektive process. Analyserna och provberedningen bedömdes ha en hög mätosäkerhet, och några förbättringar som föreslås för att öka säkerheten är genomförande av komplementerande fotoanalys för att bekräfta likheter i utseende mellan flockar, samt att genomföra mer analyser så att en statistisk giltighet av analysen kan kvantifieras. För PFAS koncentrationen så var koncentrationen av PFAS lägre i utgående vatten från fällningslinje som körs i sedimentation (7.5 ng/l), jämfört med prov från linje som körs i flotation (9.2 ng/l). För fällningslinjen som kördes i flotation så skapades skum med höga koncentrationer av PFAS (3800 ng/l) jämfört med analyserade vattenprover (5.5–9.2 ng/l), detta identifierades som en potentiell källa för PFAS-avlägsning. Resultaten av PFAS baserades endast på en provtagningsserie, och förbättringar av validitet kan åstadkommas genom samling av mer analysdata för samma processer, och genom att analysera ett av proverna i två olika instrument, som båda analyserar PFAS koncentration. / In this project, attempts have been made to collect data that allows the municipal association Norrvatten in the decision-making process on the  flotation/ sedimentation step of their water treatment process. In this sense, poly- and perfluorinated alkyl substances (PFAS) concentration and the characteristics of agglomerated particles (flocs) have been investigated and compared between the two modes that the process can be operated. For the floc characteristics, the creation and stability of the flocs were investigated, and the particle size, size distribution and zeta potential was identified as important properties and thereafter analysed using the instrument zetasizer. The concentration of eleven different PFAS compounds were analysed. The results of floc characteristics show that there is no major difference in creation and breakage of flocs in the two investigated modes, since the analysed samples had the same zeta potential, -6.45 mV. The results were deemed uncertain because of varying results, and improvement suggestions include using photoanalysis to confirm similar floc appearances and to produce more data so a statistical validity can be quantified. As for the PFAS concentration, the concentration of PFAS were slightly lower in the treatment step in which sedimentation was utilized (7.5 ng/l) compared to when flotation was utilized (9.2 ng/l). The flotation mode did, however, create foam with a high PFAS concentration (3800 ng/l) compared to the liquid samples (5.5-9.2 ng/l), so a potential PFAS removal source was identified. The results were based on one sample series, so improvements of validity can be achieved by gathering more data, analysing more samples, and analysing the same sample in two different instruments measuring PFAS concentrations.

Page generated in 0.0899 seconds