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  • 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.
451

Kelvin Probe Electrode for Field Detection of Corrosion of Steel in Concrete

Emmenegger, Leonidas Philip 02 November 2015 (has links)
While the Kelvin Probe (KP) has been used in a variety of surface scanning applications, the use of the KP in reinforced concrete structures to detect corrosion has been pioneered by previous work performed at the University of South Florida. However, in that work, the scale and construction of the probes was not suited to use in the field. This is primarily attributable to the small operating disk-to-concrete gap which would make the probe unable to accommodate road conditions, such as irregularities in the grading of the road, and local pitting of the surface. Therefore, it was important to investigate whether the KP can be scaled up while still maintaining resolution and fidelity of the measurements taken. The new mobile KP prototype (MKPP) constructed in this work, has a sensing disk that is approximately 10 cm in diameter and is capable of operating up to 2 cm above the concrete surface. Testing consisted of mapping an instrumented test slab simulating a corroding concrete bridge deck, at a rate of travel of about 0.6 mph (~1 ft/s) over the slab surface. The potential map generated through use of the MKPP successfully identified the corroding spot, the location of which was verified using the traditional half-cell potential mapping method outlined in ASTM C 876-09. The MKPP mapping in these trials was approximately 10 times faster than when using the traditional method. The faster potential mapping by the MKPP, while still identifying corroding sites, should allow for more economical and less intrusive survey of the condition of bridge decks. The work set the necessary proof of concept for future demonstration of an array of such probes which would further magnify the beneficial effect.
452

Výpočet rezonančních šířek v kvadraticky integrabilních bázích / Computing resonance widths using square integrable basis

Votavová, Petra January 2016 (has links)
Four different non-orthogonal basis sets are studied and compared in order to obtain the resonance properties of a model scattering problem. In particular, two types of Gaussian basis sets, one B-spline basis set and one hybrid Gaussian - B-spline basis set. Their ability to represent the scattering continuum is investigated along with their numerical properties. Particular attention is paid to the energy range within which each basis set gives reasonably accurate values of the phase shift and the decay width. The radial Schrödinger equation is solved by the Löwdin's symmetric orthogonalization method and the decay width is extracted by the Stieltjes imaging procedure. The R-matrix method within the framework of Feshbach-Fano projection operator formalism with polynomial basis set is utilized as a numerically exact reference method.
453

Characterization of bioactive molecules using genetically engineered ion channels / 遺伝子工学によって作製したイオンチャネルを用いた生理活性分子の特性解析

Kato, Kenta 23 March 2010 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15408号 / 工博第3287号 / 新制||工||1495(附属図書館) / 27886 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 森 泰生, 教授 濵地 格, 教授 跡見 晴幸 / 学位規則第4条第1項該当
454

TRP channels as sensors of cellular redox status / 細胞内酸化還元状態センサーとしてのTRPチャネルに関する研究

Takahashi, Nobuaki 24 November 2010 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15728号 / 工博第3342号 / 新制||工||1505(附属図書館) / 28273 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 森 泰生, 教授 濵地 格, 教授 跡見 晴幸 / 学位規則第4条第1項該当
455

The effect of the New Silk Road on EU-China trade / The effect of the New Silk Road on EU-China trade

Philipps, Andreas January 2017 (has links)
The thesis tries to investigate which impact the new Silk Road announced 2013 by the Chinese president has on EU-China trade potentials. The so called OBOR initiative is an infrastructure project that aims to promote trade facilitation along the ancient Silk Road. The initiative includes more than 60 countries. The gravity model of trade will be applied to run a simulation exercise to estimate trade potentials from the EU to China and vice versa. The results suggest that China can increase its trade potential to the EU. Among the EU countries there are winners and losers. Those countries which participate in the initiative will benefit from an increased trade potential others will lose trade potential.
456

A translational approach to dyssynchrony

Kirkwood, Graeme January 2014 (has links)
Normal cardiac function is dependent on a healthy conduction system to maintain coordinated and synchronised activity. In the presence of heart failure, dyssynchronous ventricular activation due to left bundle branch block or right ventricular pacing can result in worsening symptoms and increased mortality; cardiac resynchronisation therapy in the form of biventricular pacing has therefore become an established and effective treatment. However, it also appears that right ventricular pacing can be a cause of heart failure in some individuals, even when there is no evidence of associated pre-existing cardiac disease. A better understanding of the processes leading to dyssynchrony-induced cardiomyopathy will allow better identification and treatment of patients who are at risk, and will contribute to our knowledge about heart failure in general. This PhD adopted a translational approach to cardiac dyssynchrony, by developing a novel model of atrial-synchronous ventricular pacing in adult Welsh Mountain sheep. The right ventricle was paced from the apex continuously for 3 months at a rate that was determined by the intrinsic atrial rate; this allowed the ventricular activation pattern to be altered without changing the heart rate. In parallel, a previously-developed model of rapid ventricular pacing was studied. In this model, the heart was paced continuously at a fixed rate of 210 bpm, which led to the development of symptomatic heart failure. In vivo parameters were characterised using standard clinical techniques of electrocardiography and echocardiography. Autonomic nervous system activity was investigated by examining the heart rate responses to pharmacological blockade using atropine and propranolol, and to beta-adrenergic stimulation using dobutamine. Heart rate variability was analysed in the time and frequency domains. In vitro, patch clamping studies were performed on ventricular myocytes isolated through enzymatic digestion from the interventricular septum and left ventricular free wall. Using the perforated patch current clamp technique at 37 C, action potential duration was measured and the associated triggered calcium transient was analysed using the calcium-sensitive fluorescent indicator Fura-2AM.Heart failure was associated with in vivo evidence of autonomic dysfunction, including a 38 % increase in the resting heart rate, blunting of the heart rate response to dobutamine, and almost complete loss of vagal tonic heart rate control. This pattern was not present in dyssynchrony. At a cellular level, normal sheep had heterogeneity of action potential duration, which was longer in the septum than the free wall. Heart failure disrupted this pattern, and was also associated with approximately a 40 % reduction in the magnitude of the calcium transient in both the septum and the free wall. Dyssynchrony was associated with a similar reduction in the calcium transient, but this was isolated to the free wall. RV apical pacing therefore induced a phenotype that resembled a localised cardiomyopathy, but without the associated autonomic dysfunction of the heart failure model. However, it was possible to identify a subgroup within these subjects that displayed a pattern of autonomic changes similar to those seen in heart failure, and this appeared to be associated with the most profound cellular changes. This raises the possibility that early dyssynchrony-induced cardiomyopathy may manifest as changes in the autonomic profile, which may be detectable in clinical practice.
457

The Impact of Latency Jitter on the Interpretation of P300 in the Assessment of Cognitive Function

Yu, Xiaoqian 16 June 2016 (has links)
When stimuli processing time varies in an oddball paradigm, the latency of the P300 will vary across trials. In an oddball task requiring difficult response selections, as the variation of stimuli processing time increases, so does the variation of the P300 latency, causing latency jitters in the measurement. Averaging the P300 across different trials without adjusting this latency jitter will lead to diminished P300 amplitude, resulting in inaccurate conclusions from the data. Verleger et al. (2014) reported a diminished P300 amplitude in a difficult oddball task that required subjects to make response selections among stimuli that are difficult to distinguish, but his work did not correct for any latency jitter observed within his sample. The current study replicated the easy and hard oddball tasks conducted in Verleger et al.. Raw ERPs obtained from 16 subjects indicated a successful replication of the study. An examination of the behavioral data showed that there was substantial variation in the P300 during the hard oddball tasks, and a latency jitter correction was applied in the analysis. Results indicated that there was a significant increase in the amplitude of P300 after latency jitter correction, and that this P300 amplitude did not differ significantly between easy and hard oddball tasks. These results suggest that difficult decision requirement does not reduce the amplitude of the P300, and that latency jitter should be accounted for when analyzing data from tasks involving a difficult decision requirement.
458

The Influence of Motivational Salience on Attention Selection: An ERP Investigation

De Dios, Constanza 30 June 2016 (has links)
The current study used event-related potentials (ERPs) to investigate how motivational salience in the form of expectation violation influences spatial attention. The medial frontal negativity (MFN) ERP indexes expected value, being negative to unexpected punishments and positive to unexpected rewards. The P1 and N1 ERPs index spatial attention, being larger to stimuli in attended locations. This design attached motivational value to locations by making one visual hemifield economically rewarding (greater probability of a rewarding outcome) and the other punishing (greater probability of a punishing outcome). Keypresses to a dot probe following a reward-signifying stimulus were awarded money if correct, and penalized following a punishment-signifying stimulus if incorrect. We predicted that salience would be attached to visual hemifield, thus the MFN would be most negative to punishing outcomes in the rewarding hemifield and most positive to rewarding outcomes in the punishing hemifield. We also predicted that attention would be allocated to a location where expectation was violated, thus the P1 and N1 ERPs would be larger and RTs (reaction times) faster to dot probes appearing in the same side as an outcome that violated expected value. In a sample of 36 participants, there were no significant effects on the MFN, although the means were in the predicted direction, suggesting a lack of power. Contrary to our hypothesis, keypresses were slower, P1 smaller, and N1 larger to probes opposite the location where an expectation violation occurred. This suggested that expectation violation did not direct attention to a particular location, but produced general interference.
459

Determining the shape of a liquid droplet : from microscopic theory to coarse grained models

Hughes, Adam January 2015 (has links)
This thesis investigates the wetting of simple liquids using two density functional theory (DFT) models. The first model is a discrete lattice-gas model and the second a continuum DFT model of a hard-sphere reference system with an additional attractive perturbation. The wetting properties of liquids are principally investigated by studying the binding, or interface, potential of the fluid and this thesis presents a method by which a binding potential can be fully calculated from the microscopic DFT. The binding potentials are used to investigate the behaviour of the model fluid depending on the range to which particle interactions are truncated. Long ranged particle interactions are commonly truncated to increase computational efficiency but the work in this thesis shows that in making this truncation some important aspects of the interfacial phase behaviour are changed. It is demonstrated that in some instances by reducing the interaction range of fluid particles a shift in phase behaviour from wetting to non wetting occurs. The binding potential is an input to larger scale coarse grained models and this is traditionally given as an asymptotic approximation of the binding potential. By using the full binding potential, calculated from the DFT model, as an input, excellent agreement can be found between the results from the microscopic DFT model and the larger scale models. This is first verified with the discrete lattice-gas model where the discrete nature of the model causes some non-physical behaviour in the binding potentials. The continuum DFT model is then applied which corrects this behaviour. An adaptation to this continuum model is used to study short ranged systems at high liquid densities at state points below the `Fisher-Widom' line. The form of the decay of the density profiles and binding potentials now switches from monotonic to oscillatory. This model leads to highly structured liquid droplets exhibiting a step-like structure.
460

The role of salt tectonics in the hydrocarbon potential of the post-salt deposits (Albian to Recent), offshore Gabon

Makhubele, Marvel M.H. January 2014 (has links)
Magister Scientiae - MSc / Following successful discovery and production of hydrocarbons, Gabon is one of the key hydrocarbon target countries in Africa. Located in the Lower Congo Basin, the study area is based in Etame Marin Permit (EMP), which is licensed to VAALCO Energy Inc., and has been producing hydrocarbons since 2002. The currently explored and producing reservoirs are in the pre-salt sandstones of the Aptian Gamba Formation, charged with hydrocarbons sourced from the syn-rift lacustrine shale of the pre-Aptian Melania Formation. With the aim of finding potential petroleum plays in the post-salt successions and by using 3D prestack depth migration (PSDM) seismic sections and wireline logs, a detailed study of the post-Aptian stratigraphy and salt tectonics of the EMP was undertaken. Eight distinct reflectors were identified based on gamma ray signatures, stratal terminations and isopach trends. Sediment distribution patterns and the relative sea level history of the succession were determined by applying principles of sequence stratigraphy and salt tectonics. Furthermore, two potential plays have been outlined in the post-salt carbonates of the Albian Madiela Formation as well as in sandstones of the Turonian Azile Formation. These reservoirs might have been charged with hydrocarbons from the pre-salt shale of the Melania Formation and/or potentially also enriched from the Albian and Cenomanian shales. For these post-salt hydrocarbon reservoirs to be charged by the pre-salt source rocks, windows within the extensive evaporitic sealing of the Aptian Ezanga Formation were required. 3D PSDM seismic sections attest that diapirism of the Aptian salt unit generated ample hydrocarbon migration pathways from the pre-salt source rocks to post-salt reservoirs. Five well-developed potential salt windows have been identified, two of which have good probability to have facilitated the upward migration of hydrocarbons, because these salt windows are located up dip of oil producing wells. However, even if hydrocarbons are found in the post-salt reservoirs, similarly to the Yombo Field (located offshore Congo, south of the EMP), these shallow reservoirs in the EMP are likely to produce heavy oils due to biodegradation.

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