Examination of myocardial electrophysiology using novel panoramic optical mapping techniques

Optical mapping of voltage signals has revolutionised the field and study of cardiac electrophysiology by providing the means to visualise changes in electrical activity at a high temporal and spatial resolution from the cellular to the whole heart level under both normal and disease conditions. The aim of this thesis was to develop a novel method of panoramic optical mapping using a single camera and to study myocardial electrophysiology in isolated Langendorff-perfused rabbit hearts. First, proper procedures for selection, filtering and analysis of the optical data recorded from the panoramic optical mapping system were established. This work was followed by extensive characterisation of the electrical activity across the epicardial surface of the preparation investigating time and heart dependent effects. In an initial study, features of epicardial electrophysiology were examined as the temperature of the heart was reduced below physiological values. This manoeuvre was chosen to mimic the temperatures experienced during various levels of hypothermia in vivo, a condition known to promote arrhythmias. The facility for panoramic optical mapping allowed the extent of changes in conduction timing and pattern of ventricular activation and repolarisation to be assessed. In the main experimental section, changes in epicardial electrical activity were assessed under various pacing conditions in both normal hearts and in a rabbit model of chronic MI. In these experiments, there was significant changes in the pattern of electrical activation corresponding with the changes in pacing regime. These experiments demonstrated a negative correlation between activation time and APD, which was not maintained during ventricular pacing. This suggests that activation pattern is not the sole determinant of action potential duration in intact hearts. Lastly, a realistic 3D computational model of the rabbit left ventricle was developed to simulate the passive and active mechanical properties of the heart. The aim of this model was to infer further information from the experimental optical mapping studies. In future, it would be feasible to gain insight into the electrical and mechanical performance of the heart by simulating experimental pacing conditions in the model.

Wind turbine rotor blade monitoring using digital image correlation: a comparison to aeroelastic simulations of a multi-megawatt wind turbine

Optical full-field measurement methods such as Digital Image Correlation (DIC) provide a new opportunity for measuring deformations and vibrations with high spatial and temporal resolution. However, application to full-scale wind turbines is not trivial. Elaborate preparation of the experiment is vital and sophisticated post processing of the DIC results essential. In the present study, a rotor blade of a 3.2 MW wind turbine is equipped with a random black-and-white dot pattern at four different radial positions. Two cameras are located in front of the wind turbine and the response of the rotor blade is monitored using DIC for different turbine operations. In addition, a Light Detection and Ranging (LiDAR) system is used in order to measure the wind conditions. Wind fields are created based on the LiDAR measurements and used to perform aeroelastic simulations of the wind turbine by means of advanced multibody codes. The results from the optical DIC system appear plausible when checked against common and expected results. In addition, the comparison of relative out-of-plane blade deflections shows good agreement between DIC results and aeroelastic simulations.

Endoscopic optical coherence tomography : design and application

This thesis presents an investigation on endoscopic optical coherence tomography (OCT). As a noninvasive imaging modality, OCT emerges as an increasingly important diagnostic tool for many clinical applications. Despite of many of its merits, such as high resolution and depth resolvability, a major limitation is the relatively shallow penetration depth in tissue (about 2∼3 mm). This is mainly due to tissue scattering and absorption. To overcome this limitation, people have been developing many different endoscopic OCT systems. By utilizing a minimally invasive endoscope, the OCT probing beam can be brought to the close vicinity of the tissue of interest and bypass the scattering of intervening tissues so that it can collect the reflected light signal from desired depth and provide a clear image representing the physiological structure of the region, which can not be disclosed by traditional OCT. In this thesis, three endoscope designs have been studied. While they rely on vastly different principles, they all converge to solve this long-standing problem.

A hand-held endoscope with manual scanning is first explored. When a user is holding a hand- held endoscope to examine samples, the movement of the device provides a natural scanning. We proposed and implemented an optical tracking system to estimate and record the trajectory of the device. By registering the OCT axial scan with the spatial information obtained from the tracking system, one can use this system to simply ‘paint’ a desired volume and get any arbitrary scanning pattern by manually waving the endoscope over the region of interest. The accuracy of the tracking system was measured to be about 10 microns, which is comparable to the lateral resolution of most OCT system. Targeted phantom sample and biological samples were manually scanned and the reconstructed images verified the method.

Next, we investigated a mechanical way to steer the beam in an OCT endoscope, which is termed as Paired-angle-rotation scanning (PARS). This concept was proposed by my colleague and we further developed this technology by enhancing the longevity of the device, reducing the diameter of the probe, and shrinking down the form factor of the hand-piece. Several families of probes have been designed and fabricated with various optical performances. They have been applied to different applications, including the collector channel examination for glaucoma stent implantation, and vitreous remnant detection during live animal vitrectomy.

Lastly a novel non-moving scanning method has been devised. This approach is based on the EO effect of a KTN crystal. With Ohmic contact of the electrodes, the KTN crystal can exhibit a special mode of EO effect, termed as space-charge-controlled electro-optic effect, where the carrier electron will be injected into the material via the Ohmic contact. By applying a high voltage across the material, a linear phase profile can be built under this mode, which in turn deflects the light beam passing through. We constructed a relay telescope to adapt the KTN deflector into a bench top OCT scanning system. One of major technical challenges for this system is the strong chromatic dispersion of KTN crystal within the wavelength band of OCT system. We investigated its impact on the acquired OCT images and proposed a new approach to estimate and compensate the actual dispersion. Comparing with traditional methods, the new method is more computational efficient and accurate. Some biological samples were scanned by this KTN based system. The acquired images justified the feasibility of the usage of this system into a endoscopy setting. My research above all aims to provide solutions to implement an OCT endoscope. As technology evolves from manual, to mechanical, and to electrical approaches, different solutions are presented. Since all have their own advantages and disadvantages, one has to determine the actual requirements and select the best fit for a specific application.

Study of the tracking performance of a liquid Argon detector based on a novel optical imaging concept

The Deep Underground Neutrino Experiment (DUNE) is a long-baseline accelerator experiment designed to make a significant contribution to the study of neutrino oscillations with unprecedented sensitivity. The main goal of DUNE is the determination of the neutrino mass ordering and the leptonic CP violation phase, key parameters of the three-neutrino flavor mixing that have yet to be determined. An important component of the DUNE Near Detector complex is the System for on-Axis Neutrino Detection (SAND) apparatus, which will include GRAIN (GRanular Argon for Interactions of Neutrinos), a novel liquid Argon detector aimed at imaging neutrino interactions using only scintillation light. For this purpose, an innovative optical readout system based on Coded Aperture Masks is investigated. This dissertation aims to demonstrate the feasibility of reconstructing particle tracks and the topology of CCQE (Charged Current Quasi Elastic) neutrino events in GRAIN with such a technique. To this end, the development and implementation of a reconstruction algorithm based on Maximum Likelihood Expectation Maximization was carried out to directly obtain a three-dimensional distribution proportional to the energy deposited by charged particles crossing the LAr volume. This study includes the evaluation of the design of several camera configurations and the simulation of a multi-camera optical system in GRAIN.

Neutrino interactions in the SAND LAr volume at the DUNE Near Detector site

The neutrino mass ordering and the leptonic CP violation phase are key parameters of the three-neutrino flavour mixing still to be determined. Measuring these parameters is the main goal of DUNE, a next generation Long Baseline neutrino experiment under construction in the United States. DUNE will feature a Near and a Far Detector site. An important component of the Near detector complex is the SAND apparatus, which will include GRAIN, a novel liquid Argon detector that aims at imaging neutrino interactions using scintillation light. For this purpose, an innovative optical readout system based on Coded Aperture Masks is under study. This thesis work is aimed at a first quantitative assessment of a 3D neutrino event reconstruction algorithm for GRAIN. The processing procedure is optimized and the reconstruction performance is evaluated. Promising results are obtained.

Multiphoton ac Stark effect in a bichromatically driven two-level atom

We study the interaction of a two-level atom with two lasers of different frequencies and amplitudes: a strong laser of Rabi frequency 2 Ohm(1) on resonance with the atomic transition, and a weaker laser detuned by subharmonics (2 Ohm(1)/n) of the Rabi frequency of the first. We find that under these conditions the second laser couples the dressed states created by the first in an n-photon process, resulting in doubly dressed states and in a ''multiphoton ac Stark'' effect. We calculate the eigenstates of the doubly dressed atom and their energies, and illustrate the role of this multiphoton ac Stark effect in its fluorescence, absorption, and Autler-Townes spectra. [S1050-2947(98)07607-0].

Accuracy Comparison of Implant Impression Techniques: A Systematic Review

Background: Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose: The aim of this study was to identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods: A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit.A total of 417 articles were identified; 32 were selected for review. Results: All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique, and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in nine; six studies tested vinyl polysiloxane and one study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intraoral optical devices were compared in four studies. Conclusions: The most accurate results were achieved with two configurations: (1) the optical intraoral system with powder and (2) the open technique with splinted squared transfer copings, using polyether as impression material.

Gestão estratégica: balanced scorecard para uma entidade hospitalar

Dissertação para obtenção do Grau de Mestre em Contabilidade e Finanças Orientador: Doutora Cláudia Maria Ferreira Pereira Lopes

Projecto, optimização e gestão de redes MAIS

Mestrado em Engenharia Electrotécnica e de Computadores

Análise do padrão motor em pessoas com diagnóstico de esquizofrenia: uma abordagem em tempo real

A esquizofrenia é uma perturbação mental grave caracterizada pela coexistência de sintomas positivos, negativos e de desorganização do pensamento e do comportamento. As alterações motoras são consistentemente observadas mas, ainda pouco estudadas na esquizofrenia, sendo relevantes para o seu diagnóstico. Neste quadro, o presente estudo tem como objetivo verificar se os indivíduos com esquizofrenia apresentam alterações na coordenação motora, comparativamente com o grupo sem esquizofrenia, bem como analisar se as disfunções dos sinais neurológicos subtis (SNS) motores se encontram correlacionadas com o funcionamento executivo e com os domínios psicopatológicos da perturbação. No total participaram 29 indivíduos (13 com diagnóstico de esquizofrenia e 16 sem diagnóstico) equivalentes em termos de idade, género, escolaridade e índice de massa corporal. Para avaliar o desempenho motor recorreu-se ao sistema Biostage de parametrização do movimento em tempo real, com a tarefa de lançameto ao alvo; a presença de SNS foi examinada através da Brief Motor Scale; o funcionamento executivo pela aplicação do subteste do Vocabulário e da fluência verbal e a sintomatologia clínica através da Positive and Negative Sindrome Scale. Pela análise cinemática do movimento constatou-se que os indivíduos com esquizofrenia recrutam um padrão motor menos desenvolvido e imaturo de movimento, com menor individualização das componentes (principalmente do tronco e pélvis), necessitando de mais tempo para executar a tarefa, comparativamente com os sujeitos sem a perturbação que evidenciaram um movimento mais avançado de movimento. Os indivíduos com esquizofrenia mostraram índices elevados de disfunção dos SNS (média =6,01) estabelecendo este domínio uma relação boa e negativa com o desempenho verbal (rho Spearman=-0,62) e uma relação forte e positiva com todos os domínios psicopatológicos (rho Spearman=0,74). O estudo da existência de alterações motoras como parte intrínseca da esquizofrenia revela-se pertinente uma vez que possibilita uma compreensão mais aprofundada da sua fisiopatologia e permite que se desenvolvam práticas mais efetivas na área da saúde e reabilitação.

Cutting of Frozen Wood

The objective of this master's thesis was to develop a system for measuring the cutting forces of frozen wood. In northern parts of the world cuttingof frozen wood is one of the major problem. During winter and early spring the temperature inside the wood cells will fall below Zero degrees that strongly influences on the properties of the wood. These variations of properties will effects on the blade nomenclature while cutting the frozen wood. However the end results will cause uneven cutting forces. Cutting forces, Chip formation, wearing of the blade and the quality of the machined surface are difficult task. In this project we are attempting to find the variation of cutting forces and properties of frozen wood at four different temperatures (-20 , -10, 0 and + 10 degrees). The linear planning machine was used for measuring the cuttingforces. The cutting was done parallel to the long axis of wood due to the nature of pine wood and the structure of the plane. A considerable amount of work andtime was used for collecting and processing the numerical information from the sensors of the measuring system. There were some alterations suggested to the construction of the plane and the sensor system.

Methods for Region Based Paper Surface Roughness Measurement

Paperin pinnan karheus on yksi paperin laatukriteereistä. Sitä mitataan fyysisestipaperin pintaa mittaavien laitteiden ja optisten laitteiden avulla. Mittaukset vaativat laboratorioolosuhteita, mutta nopeammille, suoraan linjalla tapahtuville mittauksilla olisi tarvetta paperiteollisuudessa. Paperin pinnan karheus voidaan ilmaista yhtenä näytteelle kohdistuvana karheusarvona. Tässä työssä näyte on jaettu merkitseviin alueisiin, ja jokaiselle alueelle on laskettu erillinen karheusarvo. Karheuden mittaukseen on käytetty useita menetelmiä. Yleisesti hyväksyttyä tilastollista menetelmää on käytetty tässä työssä etäisyysmuunnoksen lisäksi. Paperin pinnan karheudenmittauksessa on ollut tarvetta jakaa analysoitava näyte karheuden perusteella alueisiin. Aluejaon avulla voidaan rajata näytteestä selvästi karheampana esiintyvät alueet. Etäisyysmuunnos tuottaa alueita, joita on analysoitu. Näistä alueista on muodostettu yhtenäisiä alueita erilaisilla segmentointimenetelmillä. PNN -menetelmään (Pairwise Nearest Neighbor) ja naapurialueiden yhdistämiseen perustuvia algoritmeja on käytetty.Alueiden jakamiseen ja yhdistämiseen perustuvaa lähestymistapaa on myös tarkasteltu. Segmentoitujen kuvien validointi on yleensä tapahtunut ihmisen tarkastelemana. Tämän työn lähestymistapa on verrata yleisesti hyväksyttyä tilastollista menetelmää segmentoinnin tuloksiin. Korkea korrelaatio näiden tulosten välillä osoittaa onnistunutta segmentointia. Eri kokeiden tuloksia on verrattu keskenään hypoteesin testauksella. Työssä on analysoitu kahta näytesarjaa, joidenmittaukset on suoritettu OptiTopolla ja profilometrillä. Etäisyysmuunnoksen aloitusparametrit, joita muutettiin kokeiden aikana, olivat aloituspisteiden määrä ja sijainti. Samat parametrimuutokset tehtiin kaikille algoritmeille, joita käytettiin alueiden yhdistämiseen. Etäisyysmuunnoksen jälkeen korrelaatio oli voimakkaampaa profilometrillä mitatuille näytteille kuin OptiTopolla mitatuille näytteille. Segmentoiduilla OptiTopo -näytteillä korrelaatio parantui voimakkaammin kuin profilometrinäytteillä. PNN -menetelmän tuottamilla tuloksilla korrelaatio oli paras.

Polttodirektiivien soveltaminen sellutehtaiden ilmapäästömittauksissa

EU:n polttodirektiivit, LCP- ja jätteenpolttodirektiivi ovat arkipäivää suuressa osassa polttolaitoksia Suomessakin lähivuosien kuluessa. Molemmat direktiivit on otettu mukaan Suomen lain-säädäntöön asetuksina, joita on hieman muutettu vastaamaan kansallisia tarpeita. Polttolaitokset tulevat muuttamaan aikaisempia käytäntöjään päästöistä mitattavien komponenttien sekä tarkkailujaksojen että raportoinnin osalta. Mittausten tulokset raportoidaan jatkossa yksikössä mg/Nm3. Jatkuvatoimisia mittausjärjestelmiä on asennettava yhä useampaan laitokseen ja savukaasuista tarkkaillaan pitoisuuksia päästöjen sijaan. Edelleen raportoidaan esim. ympäristölupaviranomaiselle vuosipäästöjen suuruus. Vuonna 2000 voimaan tulleen ympäristönsuojelulain ja -asetuksen velvoittamina toiminnassa olevat sellutehtaat ovat hakeneet uuden lain mukaista ympäristölupaa vuoden 2004 loppuun mennessä. Ympäristöluvan tarvitsevat myös kaikki teholtaan yli 50 MW:n polttolaitokset. Suuria polttolaitoksia koskeva LCP-direktiivi astuu voimaan vuoden 2008 alussa. Siksi uusissa ympäristöluvissa tullaantodennäköisesti vaatimaan myös sellutehtailta ko. direktiivin mukaisia mittaus-järjestelmiä ja päästörajoja. Laitoksissa on jo nyt melko kattavat päästömittausjärjestelmät, sillä myös voimassaolevat ympäristöluvat ja ilmapäästöjen tarkkailuohjelmat velvoittavat päästöjen jatkuvaan seurantaan pääosin samoista savukaasukomponenteista kuin mitä direktiivissäkin edellytetään. Tässä diplomityössä keskitytään LCP- ja jätteenpolttodirektiivien mittausvaatimuksiin, raja-arvoihin sekä raportointiin sekä Metsä-Botnian sellutehtaiden mittausjärjestelmien parantamis-toimenpiteisiin. Yksityiskohtainen toimintamalli on tehty Joutsenon tehtaan laitosta ja mittaus-järjestelmää silmällä pitäen. Sitä voidaan käyttää myös muillatehtailla mallina savukaasupäästöjen mittauksien ja laitteiden päivitysten yhteydessä. Toimintamalliin siirtyminen ei velvoita Metsä-Botnian tehtaita, mutta monet tehtaat haluavat laitteistokannan uusimisen yhteydessä siirtyä direktiivien vaatimuksia vastaavaan järjestelmään.

Asiakaspalveluprosessin mittariston luominen: Case Borealis Polymers Oy

Työn tavoitteena oli luoda asiakaspalveluprosessin mittaristo päivittäisen operatiivisen toiminnan seuraamiseksi ja parantamiseksi. Tarkoituksena oli mitata tilaustoimitusketjun suorituskykyä sekä tutkia mahdollisia kehitys ja parannuskohteita. Työ tehtiin Borealis Polymers Oy:n Fenolin Liiketoimintayksikölle. Yhtiön käytössä on Balanced Scorecard KPI- mittaristo. Asiakaspalveluprosessin mittaristo luotiin BSC asiakasnäkökulman mukaisesti soveltuen yhtiön toimintaympäristöön ja tavoitteisiin. Mittariston tarkoituksena on täydentää KPI- mittareita keskittyen päivittäisen asiakaspalveluprosessin suorituskyvyn ja asiakastyytyväisyyden parantamiseen. Asiakaspalveluprosessia kuvaavia mittareita testattiin suorittamalla asiakastyytyväisyyskysely, joka käytännössä toteutettiin sähköpostitse tehtynä tyytyväisyysmittauksena. Mittauksella haluttiin selvittää asiakastyytyväisyyden taso, palvelun eritekijöiden suhteellinen tärkeys asiakkaille eli mitkä laadun tekijät ovat asiakkaille tärkeimmät sekä miten asiakas kokee Borealiksen asiakaspalvelun suhteessa kilpailijoihin. Asiakaspalvelukysely on osa yhtiön kuluen vuoden aikana tehtävää asiakastyytyväisyysselvitystä. Lisäksi työn tavoitteena oli luoda jatkuvan toiminnan seuraamiseksi tulevaisuutta varten mittarit asiakkaille tärkeimpien laadun tekijöiden seuraamiseksi.

Optisen 1.6 GHz signaalin monistin

Tässä diplomityössä suunnitellaan CERN:in (Conseil Europëen pour la Recherche Nuclëaire) Compact Muon Solenoid –nimiseen hiukkasilmaisinjärjestelmään laite, joka monistaa 1.6 Gbit/s nopeudella saapuvia optisia signaaleja useaan eri kohteeseen. Aluksi suunnitellaan ja rakennetaan testauslaite, jonka avulla tutkitaan eri komponenttien soveltuvuutta laitteistoon. Lisäksi testauslaitteella haetaan laserohjaimille ja vastaanottimille sopivia säätöarvoja. Testauslaitteesta saatujen kokemusten perusteella suunnitellaan ja rakennetaan signaalinmonistinlaitteisto, johon tuodaan useita satoja erillisiä signaaleja. Jokainen näistä signaaleista monistetaan joko kahdeksi tai neljäksi lähteväksi signaaliksi. Lopuksi testauslaitteella tutkitaan signaalinmonistinlaitteiston toimintaa ja luotettavuutta.