CPAP is the most common treatment for moderate to severe sleep apnea in adults. Despite its efficacy, patients’ safety, comfort and compliance are issues to be considered and improved in CPAP design. The issues include condensation, carbon dioxide in inhaled air, humidity and temperature of inhaled air. When a CPAP user breaths deeply, there will be some air not fully expelled and may be driven back into the heated air delivery tube (HADT). An interest has existed in what impacts this so called reverse flow may bring about to the CPAP use. The main objectives of this research are to quantify the reverse flow and its influence on carbon dioxide re-breathing, delivered humidity to the patient and condensation in the HADT. Within this thesis, two computer models of the CPAP system have been constructed on Simulink™ in the Matlab™ environment. One is about the CPAP fluid dynamic performance and carbon dioxide re-breathing and the other is on thermodynamic performance. The models can predict the dynamic behaviour of the CPAP machine. They are able to mimic the breath induced airflow fluctuation, and flow direction changes over wide real working ranges of ambient conditions, settings and coefficients. These models can be used for future analysis, development, improvement and design of the machine. The fluid dynamic and thermodynamic models were experimentally validated and they have proved to be valuable tool in the work. The main conclusions drawn from this study are: • Reverse flow increases when breaths load increases and pressure setting decreases. • Reverse flow does not definitely add exhaled air to the next inhalation unless the reverse flow is relatively too much. • Mask capacity does not influence the reverse flow. • The exhaled air re-breathed is mainly due to that stays in the mask, therefore larger mask capacity increases the exhaled air re-breath and the percentage of exhaled air in next inhalation drops when the breath load increases. • Deep breathing does not significantly change the total evaporation in chamber. • When deep breathing induced reverse flow occurs, condensation occurs or worsens in the HADT near the mask. This happens only when the humidity of the airflow from the CPAP is much lower than that of the exhaled air and the tube wall temperature is low enough for condensation to occur. • The deep breathing and reverse flow do not significantly influence the average inhaled air temperature. • The overall specific humidity in inhaled air is lower under deep breathing. • Mask capacity does not influence the thermal conditions in the HADT and the inhaled air specific humidity. Also the mask capacity does not significantly influences the inhaled air temperature.

The aim to provide preventive healthcare and high quality medical diagnostics and treatment to an increasingly ageing population caused a rapidly increasing demand for point-of-care diagnostic devices. Disposables have an advantage over re-usable units as cross-contamination is avoided, no cleaning and sterilising of equipment is required and devices can be used out of centralised laboratories. To remain cost-effective, costs for disposables should be kept low. This makes polymer materials an obvious choice. One method for the realisation of fluidic micro devices is the stacking of several layers of microstructured polymer films. Reel-to-reel manufacturing is a promising technique for high-volume manufacturing of disposable polymer bio-analytical devices. Polyethylene terephthalate (PET) and cycloolefin copolymer (COC) were selected as suitable polymer substrate materials and polydimethyl siloxane (PDMS) as membrane layer. Bonding of polymer films with the help of adhesives carries the risk of channel blocking. Despite this drawback, no other method of bonding PDMS to a structural layer could be identified. Bonding with solvents avoids channel blocking issues, but adversely affects biocompatibility. Thermal diffusion processes enable bonding of COC and PET without the use of any auxiliary material. The extensive process times requires for thermal diffusion bonding can be considerably shortened by pre-treating the material with plasma or UV exposure. Welding with the use of a laser energy absorbing dye was demonstrated to be particularly suitable for selective bonding around channels and reservoirs. None of the assessed bonding methods provide a generic solution to all bonding applications. Instead, the selection of an appropriate technique depends on the intended application and the required level of biocompatibility. Since this selection has implications on the feasibility and reliability of microfluidic structures on the device, design rules which ensure design for production have to be established and followed.

Ce document décrit les récents résultats expérimentaux sur la structure en spin du nucléon obtenus auprès de l'accélérateur d'électrons Thomas Jefferson National Accelerator Facility (Jefferson Lab) en Virginie. Après avoir discuté la finalité de l'étude la structure en spin du nucléon et donnés les définitions de base, nous expliquons la phénoménologie de la diffusion de leptons. Nous détaillons ensuite certaines règles de somme, un outil central pour l'étude du spin du nucléon à Jefferson Lab, puis exposons la situation expérimentale actuelle. Suivent une présentation et discussion des résultats correspondants puis un exemple de résultat de l'étude du nucléon et ses conséquences sur notre compréhension de l'interaction forte. Nous concluons ce document sur les perspectives expérimentales dans ce domaine de recherche, en particulier avec la prochaine augmentation en énergie de Jefferson Lab.

<p>Computer simulations can be useful aids for both developing new analytical methods and enhancing the performance of existing techniques. This thesis is based on studies in which computer simulations were key elements in the development of several new tools for use in gas chromatography and dielectrophoresis. In gas chromatography, gaseous analytes are separated by exploiting differences in their partitioning between different phases, and after their partitioning parameters have been determined the separations can be computationally predicted, and optimized, for a wide range of operating conditions. Similarly, in dielectrophoresis, particles with differing polarizability or size can be separated, and since particle trajectories within a separation device can be predicted using computations, the suitability of new designs, applications of forces and combinations of operational parameters can be assessed without necessarily making or empirically testing all of the variants.</p><p>Using two existing numerical methods combined with semi-empirical determinations of retention behavior, temperature-programmed gas chromatograms were predicted with less than one percent deviations from experimental data, and a new method for improving the capacity of a gas-trapping device was predicted and experimentally verified. In addition, two new concepts with potential capacity to enhance dielectrophoretic separations were developed and tested in simulations. The first provides a promising way to improve the trapping of bacteria in media with elevated conductivity by using super-positioned electric fields, and the second a way to increase selectivity in the separation of bio-particles by using multiple dielectrophoretic cycles. The studies also introduced a more accurate method for determining the conductivity of suspensions of bacteria, and a new computational method for determining the dielectrophoretic behavior of particles in concentrated suspensions.</p><p>The scientific studies are summarized and discussed in the main text of this thesis, and presented in detail in seven appended papers.</p>

<p>This degree project has studied how a changed preparation affected students' outcome of a laboratory exercise. Through use of cognitive load theory and sociocultural theory a guided writing of summary was designed. Students in secondary school were let to prepare for a laboratory exercise through a traditional teacher led introduction or the guided writing of summary. Data was collected as observations, worksheets, tests and evaluations. Results suggest that the guided writing of summary facilitated a construction of cognitive schema supporting students' method. This made them follow instructions and understand purpose of the laboratory exercise before and during the exercise in a better way than students preparing through a teacher led introduction. Furthermore students' perception of aim of the exercise shifted from theoretical work afterwards to theoretical work before and practical work during the exercise. This shows an improved understanding of links between theory and practice.</p> / <p>Detta examensarbete har studerat hur en förändrad förberedelse påverkade elevers utfall av en laborationsövning. Med stöd av kognitiv belastningsteori och sociokulturell teori designades ett väglett skrivande av sammanfattning. Studenter, i motsvarande grundskolans senare år, fick förbereda sig för en laboration genom en traditionell lärarledd introduktion eller det vägledda skrivandet av sammanfattning. Data samlades in i form av observationer, arbetshäften, tester och utvärderingar. Resultatet tyder på att den vägledda skriftliga sammanfattningen underlättade för en konstruktion av kognitivt schema vilket undelättade elevernas metod. Detta gjorde att de följde instruktioner och förstod mening med laborationen före och under denna på ett bättre sätt än elever som förberedde sig med en lärarledd introduktion. Vidare ändrades elevernas uppfattning om målet med laborationen från teoretiskt arbete efter övningen till teoretiskt arbete före och praktiskt arbete under laborationen. Detta visade på en ökad förståelse av kopplingar mellan teori och praktik.</p>

<p>In later years polymer replication techniques have become a frequently employed fabrication method for microfluidic and micro-optical devices. This thesis describes applications and further developments of microstructures replicated in polymer materials. </p><p>A novel method for homogenous amplified single-molecule detection utilizing a microfluidic readout format is presented. The method enables enumeration of single biomolecules by transforming specific molecular recognition events at nanometer dimensions to micrometer-sized DNA macromolecules. This transformation process is mediated by target specific padlock probe ligation, followed by rolling circle amplification (RCA) resulting in the creation of one rolling circle product (RCP) for each recognized target. Throughout this transformation the discrete nature of the molecular population is preserved. By hybridizing a fluorescence-labeled DNA detection oligonucleotide to each repeated sequence of the RCP, a confined cluster of fluorophores is generated, which makes optical detection and quantification possible. Spectral multiplexing is also possible since the spectral profile of each RCP can be analyzed separately. The microfluidic data acquisition process is characterized in detail and conditions that allow for quantification limited only by Poisson sampling statistics is established. The molecular characteristics of RCPs in solution are also investigated.</p><p>Furthermore a novel thermoplastic microfluidic platform is described. The platform allows for observation of the microchannels using high magnification optics and also offers the possibility of on-chip cell culture and the integration of mechanical actuators.</p><p>A novel fabrication process for the integration of polymer micro-optical elements on silicon is presented. The process is used for fabrication of a micro-optical system consisting of a laser and a movable microlens making beam steering possible. Such a micro-scanning system could potentially be used for miniaturized biochemical analysis.</p>

In later years polymer replication techniques have become a frequently employed fabrication method for microfluidic and micro-optical devices. This thesis describes applications and further developments of microstructures replicated in polymer materials. A novel method for homogenous amplified single-molecule detection utilizing a microfluidic readout format is presented. The method enables enumeration of single biomolecules by transforming specific molecular recognition events at nanometer dimensions to micrometer-sized DNA macromolecules. This transformation process is mediated by target specific padlock probe ligation, followed by rolling circle amplification (RCA) resulting in the creation of one rolling circle product (RCP) for each recognized target. Throughout this transformation the discrete nature of the molecular population is preserved. By hybridizing a fluorescence-labeled DNA detection oligonucleotide to each repeated sequence of the RCP, a confined cluster of fluorophores is generated, which makes optical detection and quantification possible. Spectral multiplexing is also possible since the spectral profile of each RCP can be analyzed separately. The microfluidic data acquisition process is characterized in detail and conditions that allow for quantification limited only by Poisson sampling statistics is established. The molecular characteristics of RCPs in solution are also investigated. Furthermore a novel thermoplastic microfluidic platform is described. The platform allows for observation of the microchannels using high magnification optics and also offers the possibility of on-chip cell culture and the integration of mechanical actuators. A novel fabrication process for the integration of polymer micro-optical elements on silicon is presented. The process is used for fabrication of a micro-optical system consisting of a laser and a movable microlens making beam steering possible. Such a micro-scanning system could potentially be used for miniaturized biochemical analysis.

Computer simulations can be useful aids for both developing new analytical methods and enhancing the performance of existing techniques. This thesis is based on studies in which computer simulations were key elements in the development of several new tools for use in gas chromatography and dielectrophoresis. In gas chromatography, gaseous analytes are separated by exploiting differences in their partitioning between different phases, and after their partitioning parameters have been determined the separations can be computationally predicted, and optimized, for a wide range of operating conditions. Similarly, in dielectrophoresis, particles with differing polarizability or size can be separated, and since particle trajectories within a separation device can be predicted using computations, the suitability of new designs, applications of forces and combinations of operational parameters can be assessed without necessarily making or empirically testing all of the variants. Using two existing numerical methods combined with semi-empirical determinations of retention behavior, temperature-programmed gas chromatograms were predicted with less than one percent deviations from experimental data, and a new method for improving the capacity of a gas-trapping device was predicted and experimentally verified. In addition, two new concepts with potential capacity to enhance dielectrophoretic separations were developed and tested in simulations. The first provides a promising way to improve the trapping of bacteria in media with elevated conductivity by using super-positioned electric fields, and the second a way to increase selectivity in the separation of bio-particles by using multiple dielectrophoretic cycles. The studies also introduced a more accurate method for determining the conductivity of suspensions of bacteria, and a new computational method for determining the dielectrophoretic behavior of particles in concentrated suspensions. The scientific studies are summarized and discussed in the main text of this thesis, and presented in detail in seven appended papers.

@font-face { font-family: "Times New Roman"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 4pt; text-align: justify; font-size: 9pt; font-family: "Times New Roman"; }table.MsoNormalTable { font-size: 10pt; font-family: "Times New Roman"; }div.Section1 { page: Section1;Mechanics, first experienced by engineering students in introductory physics courses, encompasses an important set of foundational concepts for success in engineering. However, although it has been well known for some time that acquiring a conceptual understanding of mechanics is one of the most difficult challenges faced by students, very few successful attempts to engender conceptual learning have been described in the literature. On the contrary, research has shown that most students participating in university levelcourses had not acquired a Newtonian understanding of mechanics at the end of their respective course. Recently I have described more than 10 years of experiences of designing and using conceptual labs in engineering education that have successfully fostered insightful learning. In the framework of the larger project I have developed labs applying variation theory in the design of task structure and using sensor-computer-technology (“probe-ware”) for collecting and displaying experimental data in real-time. In previous studies, I have shown that these labs using probe-ware can be effective in learning mechanics with normalised gains in the g≈50-60% range and with effect sizes d≈1.1, but that this technology also can be implemented in ways that lead to low achievements. One necessary condition for learning is that students are able to focus on the object of learning and discern its critical features. A way to establish this, according to the theory of variation developed by Marton and co-workers, is through the experience of difference (variation), rather than through the recognition of similarity. In a lab, an experiential human–instrument–world relationship is established. The technology used places some aspects of reality in the foreground, others in the background, and makes certain aspects visible that would otherwise be invisible. In labs, this can be used to bring critical features of the object of learning into the focal awareness of students and to afford variation. In this study, I will account for how the design of task structure according to variation theory, as well as the probe-ware technology, make the laws of force and motion visible and learnable and, especially, in the lab studied make Newton’s third law visible and learnable. I will also, as a comparison, include data from a mechanics lab that use the same probe-ware technology and deal with the same topics in mechanics, but uses a differently designed task structure. I will argue that the lower achievements on the FMCE-test in this latter case can be attributed to these differences in task structure in the lab instructions. According to my analysis, the necessary pattern of variation is not included in the design. I will also present a microanalysis of 15 hours collected from engineering students’ activities in a lab about impulse and collisions based on video recordings of student’s activities in a lab about impulse and collisions. The important object of learning in this lab is the development of an understanding of Newton’s third law. The approach analysing students interaction using video data is inspired by ethnomethodology  and conversation analysis, i.e. I will focus on students practical, contingent and embodied inquiry in the setting of the lab. I argue that my result corroborates variation theory and show this theory can be used as a ‘tool’ for designing labs as well as for analysing labs and lab instructions.  Thus my results have implications outside the domain of this study and have implications for understanding critical features for student learning in labs.

An all-optical micromanipulation technique is presented in the framework of precise cell selection within a cell culture and multiplexed transport capabilities for microfluidic single cell analysis applications. The technique was developed by combining an optical tweezer setup with a novel integrated waveguide cell propulsion method referred to as end-face waveguide propulsion (EFWP). The EFWP technique delivers optical forces to a particle generating thrust. The thesis is divided into two sections: simulation and experimental validation. In the first section a new simulation technique based on ray optics theory (ROT) and the beam propagation method (BPM) is used to predict particle velocity and trajectory along a microfluidic propagation channel. In this work, the ROT-BPM technique is used to analyse and optimize the waveguide geometry to maximize particle velocity. Analysis of the impact of common microchip manufacturing limitations on velocity is performed to determine acceptable fabrication process tolerances. The second section presents experimental results of polymer microspheres and acute myeloid leukemia (AML) cells as biological targets. The experimental results are compared with simulations performed in the first section. Correction factors are added to the simulations to reflect the experimental device parameters. Thermal e_ects due to photon absorption within the fluidic channels are also investigated and corrected for. The final analysis indicates that the ROT-BPM technique developed in this work can be used to adequately predict particle velocity and trajectory path. EFWP currently delivers the fastest particle velocities compared to other optical micromanipulation techniques currently available in microfluidic applications. While the technique is focused on addressing chemical cytometry precise particle selectivity and high throughput needs, EFWP can also be used in many other single cell applications.