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1
Yoshida, Beni. "Studying many-body physics through quantum coding theory." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77257.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 133-140).
The emerging closeness between correlated spin systems and error-correcting codes enables us to use coding theoretical techniques to study physical properties of many-body spin systems. This thesis illustrates the use of classical and quantum coding theory in classifying quantum phases arising in many-body spin systems via a systematic study of stabilizer Hamiltonians with translation symmetries. In the first part, we ask what kinds of quantum phases may arise in gapped spin systems on a D-dimensional lattice. We address this condensed matter theoretical question by giving a complete classification of quantum phases arising in stabilizer Hamiltonians at fixed points of RG transformations for D = 1; 2; 3. We found a certain dimensional duality on geometric shapes of logical operators where m-dimensional and (D m)-dimensional logical operators always form anti-commuting pairs (m is an integer). We demonstrate that quantum phases are completely classified by topological characterizations of logical operators where topological quantum phase transitions are driven by non-analytical changes of geometric shapes of logical operators. As a consequence, we argue that topological order is unstable at any nonzero temperature and self-correcting quantum memory in a strict sense may not exist where the memory time is upper bounded by some constant at a fixed temperature, regardless of the system size. Our result also implies that topological field theory is the universal theory for stabilizer Hamiltonians with continuous scale symmetries. In the second part, we ask the fundamental limit on information storage capacity of discrete spin systems. There is a well-known theoretical limit on the amount of information that can be reliably stored in a given volume of discrete spin systems. Yet, previously known systems were far below this theoretical limit. We propose a construction of classical stabilizer Hamiltonians which asymptotically saturate this limit. Our model borrows an idea from fractal geometries arising in the Sierpinski triangle, and is a rare manifestation of limit cycle behaviors with discrete scale symmetries in real-space RG transformations, which may be beyond descriptions of topological field theory.
by Beni Yoshida.
Ph.D.
2
Miller, Daniel E. (Daniel Edward). "Studying coherence in ultra-cold atomic gases." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/45398.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Physics, September 2007.Includes bibliographical references (leaves 130-141).
This thesis will discuss the study of coherence properties of ultra-cold atomic gases. The atomic systems investigated include a thermal cloud of atoms, a Bose-Einstein condensate and a fermion pair condensate. In each case, a different type of measurement is performed. However, all of the experiments share a common tool: an optical lattice which is used to probe these atomic gases. In the first case, we use an auto-correlation technique to study the interference pattern produced by a gas of atoms, slightly above the Bose -Einstein condensate transition temperature. A moving optical lattice is used to split and recombine the single particle atomic wavefunction. Analogous to a Young's double slit experiment, we observe high contrast interference which is well described by the model which we develop. When we address only a velocity subset of the thermal sample, however, the contrast is enhanced and deviates from this model. In a second experiment we measure the coherence of a diatomic molecular gas, as well as the atomic Bose-Einstein condensate from which it was created. We use Bragg spectroscopy, in which atoms exchange photons with a moving optical lattice, transferring momentum to the atoms. This process can reveal the velocity distribution of the sample as energy and momentum are conserved only for a specific velocity class. Based on this measurement, we find that the atomic coherence is transferred directly to the molecular gas. We also discuss similar preliminary measurements performed on a fermion pair condensate in the BEC-BCS crossover. In a third experiment we study a fermion pair condensate into a 3D optical lattice. Such a system shares many similarities with electrons in solid materials which exhibit superconductivity, and can offer insight into mechanism which result in this behavior. We infer coherence from the sharp interference pattern observed in the expanding gas, after release. Finally, we study the abrupt onset of dissipation observed in a fermion pair condensate, as a function of velocity, in a moving optical lattice.
(cont.) We equate this threshold with the Landau critical velocity, and take measurements throughout the BEC-BCS crossover. The critical velocity is found to be maximum near unitarity, where the loss mechanism is predicted to crossover from phonon-like excitations to pair breaking.
by Daniel E. Miller.
Sc.D.
3
Owen, John Michael. "Studying cosmological structure formation with numerical hydrodynamic simulations /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487943341530188.
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HONGSA-NGIAM, Anusak, and anusakhongsa@yahoo com. "AN INVESTIGATION OF PHYSICS INSTRUCTORS' BELIEFS AND STUDENTS' BELIEFS, GOALS AND MOTIVATION FOR STUDYING PHYSICS IN THAI RAJABHAT UNIVERSITIES." Edith Cowan University. Community Services, Education And Social Sciences: School Of Education, 2007. http://adt.ecu.edu.au/adt-public/adt-ECU2007.0011.html.
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Students' interest in physics seems to be decreasing at all levels of education in most countries including Thailand. This problem is likely to be influenced by physics teaching and learning processes. Instructors' beliefs influence teaching strategies whereas students' beliefs, goals and motivation influence learning strategies. The investigation of factors influencing teaching and learning will provide useful information for improving the teaching and learning of physics. This research aims to explore physics instructors' beliefs about teaching and learning physics, students' beliefs, goals and motivation for studying physics in Thai Rajabhat universities. A questionnaire was administered to instructors who teach introductory physics courses in Rajabhats throughout Thailand at the beginning of second semester in 2002. Questionnaires were administered to first year students who enrolled in introductory physics courses at two Rajabhat universities in the south of Thailand at the beginning and the end of that semester. Four case studies were conducted with instructors and students at the two Rajabhats during the semester.
5
Rafei, Mouna. "Synthesis of single-layer graphene and studying oxidation behaviour of copper foil." Thesis, Umeå universitet, Institutionen för fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-177004.
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The ultimate aim of the current study is to investigate the electron transfer from copper (Cu) to single layer graphene through a thin Cu oxide layer. Therefore the project is divided into two main parts. In the first part, single layer graphene is synthesized with chemical vapour deposition technique on a Cu foil and the grown graphene is characterized by means of Raman spectroscopy and scanning electron microscopy (SEM). We tune different experimental parameters to grow high quality graphene. We show that a pre-annealing of the Cu foil, in Varigon environment, modifies the Cu crystal grain size and that modifies the growth dynamic of the graphene. Optimum annealing time in correlation with growth time results in high Ǵ/G ratio and a narrow FWHM of Ǵ band in Raman spectrum. The second part of the project focuses on controlling the surface oxidation of Cu foil with respect to the oxide layer thickness. The surface and cross section of the oxidized Cu foil is examined by SEM and the presence of oxide layer is confirmed via energy dispersive X-ray spectroscopy (EDS) analysis. We show that the surface roughness of the oxide layer can be minimized by controlling the oxidation condition with a minimum oxide layer thickness of 18 μm. In addition the grain size of the oxide layer is getting larger with increasing the oxidation temperature. Furthermore, the oxygen concentration in the oxide layer is controlled through a controlled reduction process which is confirmed via EDS analysis. XPS spectroscopy is also used for elemental analysis as well as revealing the chemical state of the Cu oxide.
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Hansch, Peter. "Intensity-selective scanning: A new paradigm for studying photoionization in strong laser fields /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946103568339.
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Daldorff, Lars Kristen Selberg. "Numerical Simulation as a Tool for Studying Waves and Radiation in Space." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9517.
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Hinz, Philip Mark. "Nulling interferometry for studying other planetary systems: Techniques and observations." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280541.
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Nulling interferometry is an important technique in the quest for direct detection of extrasolar planets. It is central to NASA's plans for a Terrestrial Planet Finder (TPF) mission to detect and characterize Earth-like planets. This thesis presents the first experiments to demonstrate that the technique is a useful tool for ground-based observations as well. It demonstrates the ability of the technique to study faint, circumstellar environments otherwise not easily observed. In addition the observations and experiments allow more confident estimation of expected sensitivity to planetary systems around nearby stars. The old MMT was used for the first telescope experiments of stellar suppression via nulling. The stellar suppression achieved was sufficient to observe thermal emission from cool dust in the outflows around late-type stars. Based on the original MMT prototype, which worked at ambient temperature, I have constructed a cryogenic nulling interferometer for use with the renovated 6.5 m MMT. Features include the capability of sensing and correcting the phase between the two arms of the interferometer, achromatic tuning of the null using a unique symmetric beam-splitter, and compatibility with the deformable secondary of the MMT. The instrument has been used in a laboratory setup with an artificial source to demonstrate a high level of suppression. Commissioning of the instrument took place at the MMT in June 2000 using the fixed f/9 secondary. The instrument was aligned, phased, and used for science observations of 17 stars over five nights. The future impact of nulling with the MMT and the Large Binocular Telescope is sketched out. These telescopes will be sensitive to very faint levels of zodiacal dust, indicative of planetary companions and giving us clues as to the make up of planetary systems. Substellar companions down to near Jupiter mass will be detectable around the nearest stars for the LBT, allowing direct imaging of long-period giant planets. The detection of such companions will be complementary to the Doppler velocity searches, currently so successful in verifying the existence of planets, thus giving a balanced view of the prevalence and range of separations possible for giant planets around nearby stars.
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Vinciguerra, Serena. "Studying neutron-star and black-hole binaries with gravitational-waves." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8159/.
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The revolutionary discoveries of the last few years have opened a new era of astronomy. With the detection of gravitational-waves, we now have the opportunity of investigating new phenomena, such as mergers of black-holes. Furthermore, multi-messenger observations now allow us to combine information from different channels, providing insight into the physics involved. With this rapid evolution and growth of the field, many challenges need to be faced. In this thesis we propose three data analysis strategies to efficiently study the coalescences of compact binaries. First we propose an algorithm to reduce the computational cost of Bayesian inference on gravitational-wave signals. Second we prove that machine-learning signal classification could enhance the significance of gravitational-wave candidates in unmodelled searches for transients. Finally we develop a tool, saprEMo, to predict the number of electromagnetic events, which according to a specific emission model, should be present in a particular survey.
10
Lynch, Christene Rene. "Studying the magnetic fields of cool stars." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1357.
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Magnetic fields are prevalent in a wide variety of low mass stellar systems and play an important role in their evolution. Yet the process through which these fields are generated is not well understood. To understand how such systems can generate strong field structures characterization of these fields is required. Radio emission traces the fields directly and the properties of this emission can be modeled leading to constraints on the field geometry and magnetic parameters. The new Karl Jansky Very Large Array (VLA) provides highly sensitive radio observations. My thesis involves combining VLA observations with the development of magnetospheric emission models in order to characterize the magnetic fields in two fully convective cool star systems: (1) Young Stellar Objects (YSOs); (2) Ultracool dwarf stars.
I conducted multi epoch observations of DG Tau, a YSO with a highly active, collimated outflow. The radio emission observed from this source was found to be optically thick thermal emission with no indication of the magnetic activity observed in X-rays. I determined that the outflow is highly collimated very close to the central source, in agreement with jet launching models. Additionally, I constrained the mass loss of the ionized component of the jet and found that close to the central source the majority of mass is lost through this component. Using lower angular resolution observations, I detected shock formations in the extended jet of DG Tau and modeled their evolution with time.
Taking full advantage of the upgraded bandwidth on the VLA, I made wideband observations of two UCDs, TVLM513-46 and 2M 0746+20. Combining these observations with previously published and archival VLA observations I was able to fully characterize the spectral and temporal properties of the radio emission. I found that the emission is dominated by a mildly polarized, non-thermal quiescent component with periodic strongly polarized flare emission. The spectral energy distribution and polarization of the quiescent emission is well modeled using gyrosynchrotron emission with a mean field B~100 G, mildly relativistic power-law electrons with a density ne~105-6 cm-3, and source size of R~2R*. We were able to model the pulsed emission by coherent electron cyclotron radiation from a small number of isolated loops of high magnetic field (2-3 kG) with scale heights~1.2-2.7 stellar radii. The loops are well-separated in magnetic longitude, and are not part of a single dipolar magnetosphere. The overall magnetic configuration of both stars appears to confirm recent suggestions that radio over-luminous UCD's have `weak field' non-axisymmetric topologies, but with isolated regions of high magnetic field.
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Fortin, Pascal. "An instrument for studying the response of STACEE camera components to different lighting conditions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ64354.pdf.
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Trainor, John Roland. "Development of a crossed beam instrument for studying ion-molecule reactions." Thesis, University of Warwick, 1990. http://wrap.warwick.ac.uk/106751/.
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This thesis describes the development of a Crossed Beam instrument for the study of ion-molecule reactions. A full investigation of some gross systematic errors, in apparatus which had been previously installed, is made. Where time has prevented the further development, then conclusions have been transformed into specifications, and practical solutions described. Experimental data is presented which is interpreted as evidence that the beams intersect and that low intensity of the scattered products and the forementioned systematic errors veil these data. The reduction of data, containing such errors, to useful chemical interpretation is extremely difficult, hence the need for further modification. Data are presented in chapter 3 consistent with the quadrupole acting as a linear particle accelerator. The effect on an initially monochromated beam is of causing an unacceptable energy spread. The spherical and chromatic aberrations of both source and detector are identified as the principal systematic errors using computer simulation (SIMION) for forward convolution. The development of a pulsed neutral beam source is described in chapter 4. The performance of the beam source is critically analysed and compared to alternative sources. A generally applicable model is derived to predict the shutter opening function of pulsed sources. Such a study has not previously been made. It is anticipated that this model will be of use to the solution of non-steady flow problems i.e. calculation of time dependent flow field properties, or in the deconvolution of TOF spectra from beam sources. Performance data for the beam source and some calculated properties are given. The subject of ion-molecule reactions is introduced by development from simple ideas. The subject matter covered is not intended to be exhaustive, but covers the examples of ion-molecule reactions of personal Interest. Recent crossed beam studies are examined and suggestions of possible new experiments made.
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Hongsa-ngiam, Anusak. "An investigation of physics instructors' beliefs and students' beliefs, goals and motivation for studying physics in Thai Rajabhat universities." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2006. https://ro.ecu.edu.au/theses/35.
Full textAbstract:
Students' interest in physics seems to be decreasing at all levels of education in most countries including Thailand. This problem is likely to be influenced by physics teaching and learning processes. Instructors' beliefs influence teaching strategies whereas students' beliefs, goals and motivation influence learning strategies. The investigation of factors influencing teaching and learning will provide useful information for improving the teaching and learning of physics. This research aims to explore physics instructors' beliefs about teaching and learning physics, students' beliefs, goals and motivation for studying physics in Thai Rajabhat universities. A questionnaire was administered to instructors who teach introductory physics courses in Rajabhats throughout Thailand at the beginning of second semester in 2002. Questionnaires were administered to first year students who enrolled in introductory physics courses at two Rajabhat universities in the south of Thailand at the beginning and the end of that semester. Four case studies were conducted with instructors and students at the two Rajabhats during the semester.
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Hongsa-ngiam, Anusak. "An investigation of physics instructors' beliefs and students' beliefs, goals and motivation for studying physics in Thai Rajabhat Universities." Connect to thesis, 2006. http://portal.ecu.edu.au/adt-public/adt-ECU2007.0011.html.
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Subedi, Ramesh Raj. "Studying Short-Range Correlations with the 12C(e,e'pn) Reaction." [Kent, Ohio] : Kent State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1194961371.
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Wickey, Kurtis J. "Developing a temperature sensitive tool for studying spin dissipation." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437252889.
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Verstreken, Christophe. "Studying the direct effects of forces on embryonic stem cell behaviour." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283499.
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Cells experience different mechanical cues from their local environment, including shear flow, forces applied by neighbouring cells, and substrate stiffness. These external signals influence cell behaviour, also in embryonic stem (ES) cells, where they could potentially affect pluripotency or differentiation. The precise effects of external forces on ES cells are confounded by forces inducing secondary changes to attachment or cell-cell signalling, which themselves can also influence cell behaviour. In this study we developed a set-up to attach cells to elastic membranes using a novel functionalisation technique, and exposed them to single or cyclic stretch. We used this method to study the mechanosensitive response of ES cells. We found that stretching caused an immediate increase in the concentration of intracellular calcium, followed by a rapid decrease in some cells. On timescales of 1 - 2 h, stretching induced an increase in the expression of the immediate and early genes, but then cells became temporarily insensitive to subsequent mechanical signals. Stretching did not have a substantial impact on pluripotency and differentiation, as we showed using gene expression studies and a Rex1 reporter. To study how ES cells' susceptibility to mechanical signals depended on media condition, stretch duration and stretch type, we performed RNA sequencing and used gene ontology techniques to investigate the involvement of specific pathways. We found that forces have a broad impact on the overall transcriptome that is highly culture media-dependent. However, a core transcriptional response, including the biosynthesis of membrane components and stress pathways, was largely preserved across the different conditions. We supplemented our experimental findings with a conceptual model of force propagation in disordered environments, such as the nucleus of a cell. Using computational simulations, we studied how the large-scale behaviour of a disordered system depends on the microscopic structure. Contrary to common wisdom, we showed that disordered systems exhibit both positive and negative Poisson's ratios with equal probability. Overall, on short timescales, stretching affected ES cells' calcium concentration and transcription. On longer timescales, ES cells' response was small in magnitude but broad in scope, with limited effects on pluripotency. As such, our results suggest that mechanosensitivity in ES cells is mediated primarily by tissue-wide changes to morphology and attachment.
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Praveen, Vikram. "Event Driven GPS Data Collection System for Studying Ionospheric Scintillation." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1323894410.
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Herman, Michael Ray. "Studying Paramagnetic Impurities in Diamond with Magnetic Resonance Force Microscopy." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313593340.
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Steer, Edward. "Development and characterisation of a cold molecule source and ion trap for studying cold ion-molecule chemistry." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:13c3a622-ba78-4a53-902c-666ec461f708.
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A novel apparatus, combining buffer-gas cooling, electrostatic velocity selection and ion trapping, has been constructed and characterised. This apparatus is designed to investigate cold ion-molecule chemistry in the laboratory, at a variable translational and internal (rotational) temperature. This improves on previous experiments with translationally cold but rotationally hot molecule sources. The ability to vary the rotational temperature of cold molecules will allow for the experimental investigation of post-Langevin capture theories.
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Calvo, Villar Ernesto. "The AD detector array: a new tool for studying diffractive physics at the ALICE experiment." Master's thesis, Pontificia Universidad Católica del Perú, 2015. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6155.
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We present a new detector array proposal for the ALICE experiment at LHC.
This new subdetector is composed of four stations of scintillator pads and its main goal is to extend our current rapidity coverage. Therefore, we would have more sensitivity to tag the rapidity gaps related to the diffractive processes.
In particular, we show a study of the performance of this new subdetector and its impact in our ability to select diffractive events. Certainly, this new system will contribute to improve the ALICE capabilities in addressing several subjects on diffractive physics.Tesis
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Mattera, Andrea. "Studying neutron-induced fission at IGISOL-4 : From neutron source to yield measurements and model comparisons." Doctoral thesis, Uppsala universitet, Tillämpad kärnfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328484.
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Fission yields represent the probability of producing a certain nuclide in a fission event, and are important observables for fission research. For applications, accurate knowledge of the yields is fundamental at all stages of the fuel cycle of nuclear reactors, e.g., for reactivity calculations, or to estimate (spent) fuel inventory. Fission yields also help in the basic understanding of the fission process, for nucleosynthesis models, and for radioactive ion beam production. This thesis was developed in the framework of the AlFONS project, the objective of which was to measure neutron-induced fission yields of relevance for partitioning and transmutation of spent fuel. The work is performed at the IGISOL-4 facility in JYFL (University of Jyväskylä). The first part of this thesis work is dedicated to the development and characterisation of a suitable 9Be(p(30MeV),nx) neutron source for IGISOL-4. The neutron energy spectrum and the neutron yield from a 5mm thick converter were studied with Monte Carlo simulations. Two characterisation campaigns that validated the MCNPX code were also performed. At the maximum current available from the cyclotron at JYFL, a total neutron yield between 2 and 5×1012 neutrons/(sr s) can be obtained. This satisfies the design goal for studies of fission yields. The neutron source was used in the measurement of fission yields from high-energy neutron-induced fission of natU at IGISOL-4, discussed in the second part of this thesis. The fission products were online-separated with a dipole magnet. The isobars, with masses in the range A = 128-133, were identified using γ-spectroscopy. Data for the relative yields of tin and antimony, as well as isomeric yield ratios for five nuclides will be reported. The yields show trends not observed in the ENDF/B-VII.1 evaluation, and only in part confirmed by the GEF model. The final part of this thesis concerns a study of the performance of different nuclear model codes, that aim at describing the states of the fission fragments right after scission. Reproduction of experimental data serves to benchmark the models and it indicates, to some extent, how reliably the results can be extrapolated to regions where no data exist. A methodology to compare and test these models has been developed, which was implemented in the DEℓFIN code. DEℓFIN takes the excited fission fragments, defined by the model under test, and de-excites them in a standardised way using the nuclear model code TALYS. Eliminating any variability in the way the final observables are extracted helps focusing on each model's assumptions. DEℓFIN was tested on five models, and interesting features in the prompt neutron multiplicity were found for some of them. This study will promote a better understanding of the ideas used in the development of fission models.
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Tekiel, Antoni. "Ultra-high vacuum fabrication of nanoscale systems for studying single-electron charging by room-temperature atomic force microscopy." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119570.
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In this work we describe ultra-high vacuum fabrication of a nanoscale system that reveals Coulomb blockade at room temperature and its characterization by single-electron sensitive electrostatic force microscopy (e-EFM). The system consists of Au nanoparticles separated from an Fe(001) back electrode by a crystalline ultra-thin NaCl film. Due to the small size of the nanoparticles (3.5 nm high), the Coulomb blockade can be observed at room temperature. An atomic force microscopy (AFM) cantilever is used as a movable gate to charge individual nanoparticles via single-electron tunneling from the back electrode. At the same time the tunneling is detected by measuring frequency shift and damping of the oscillating cantilever. The e-EFM technique can overcome limitations of other characterization methods based on lithographic fabrication. So far, however, it has been successfully used only at low-temperatures. In this work, we extend the e-EFM technique to room temperature by carefully tuning the sample design and fabrication relative to the cantilever response to achieve maximum sensitivity. To grow atomically defined tunnel barriers we investigate the morphology of MgO and NaCl ultra-thin films on Fe(001) surfaces by non-contact-AFM and low energy electron diffraction (LEED). First, we demonstrate that the quality of MgO films, typically grown in ultra-high vacuum (UHV) by electron-beam evaporation, can be improved by using reactive deposition method that gives full control over the gaseous species existing in the evaporated beam. Second, we investigate the effects of temperature and oxygen presence on the growth of NaCl on Fe(001). As a result, we develop a protocol to grow NaCl films on the Fe(001)-p(1x1)O surface in a layer-by-layer mode, yielding atomically flat films with 40-60 nm wide terraces (on a 12 ML thick film) and with far fewer defects than the MgO films. Using the NaCl film as a tunnel barrier that can be easily adjusted by modifying the film thickness we characterize single-electron charging at room temperature of individual Au nanoparticles formed after thermal evaporation onto a 6 monolayer thick NaCl film. We demonstrate how a combination of e-EFM and finite element electrostatic simulation can be used for revealing electronic and morphological properties of individual Au nanoparticles. As a result, the electron addition energy, the capacitance, tunneling rates and an approximated shape of an individual nanoparticle have been determined. Numerical simulations point towards a total capacitance dominated by the mutual capacitance between the nanoparticle and the back electrode. A comparison with the experimental value, determined from measurement of the addition energy, indicates that the nanoparticles should be modeled as truncated spheres in order to reduce the mutual capacitance to the substrate. This observation has a fundamental impact on the design of nanoelectronic circuits, where the components have to meet desired requirements for capacitances that determine coupling and charging effects. The fabrication flexibility and the fact that all measurements were performed in-situ on samples prepared under ultra-clean conditions make the presented system attractive for further studies. In particular, this approach can be used to study quantum mechanically coupled quantum dots and the catalytic activity of Au nanoclusters at room temperature.Dans ce travail, nous décrivons la fabrication sous ultra haut vide (UHV) d'un système à l'échelle nanométrique qui révèle le blocage de Coulomb à température de la pièce, ainsi que sa caractérisation par microscopie à force électrostatique sensible à un électron (single-electron sensitive electrostatic force microscopy, e-EFM). Le système est constitué de nanoparticules d'or séparées d'une électrode de Fe(001) par un film cristallin ultra mince de NaCl. Dû à la petite taille des nanoparticules (3.5 nm maximum), le blocage de Coulomb est observable à température ambiante. Un cantilever de microscope à force atomique (MFA) est utilisé comme une grille électrique déplaçable pour charger individuellement les nanoparticules par le passage de charge élémentaire par effet tunnel à partir de l'électrode. Ce passage d'électron est détecté en mesurant simultanément le changement de fréquence de résonance, ainsi que l'amortissement de l'oscillation du cantilever. La technique e-EFM permet de contourner certaines limitations inhérentes aux techniques de caractérisation basées sur la fabrication par lithographie. Toutefois, cette technique a été appliquée avec succès seulement à basses températures. Dans ce travail, nous étendons la technique e-EFM à température ambiante par un ajustement minutieux du design de l'échantillon et de sa fabrication en fonction de la réponse du cantilever de sorte à maximiser la sensibilité de la mesure. Pour croître une jonction tunnel définie à l'échelle atomique, nous étudions la morphologie de couches minces de MgO et de NaCl sur une surface de Fe(001) par microscopie à force atomique non-contact et par diffraction d'électrons lents (Low Energy Electrons Diffraction, LEED). Premièrement, nous démontrons que la qualité des couches minces de MgO, typiquement crûes sous UHV par évaporation sous faisceau d'électrons (electron-beam evaporation), peut être améliorée par l'utilisation d'une méthode de déposition réactive qui donne un contrôle total sur les espèces gazeuses présentes dans le faisceau d'évaporation. Deuxièmement, nous étudions l'effet de la température et de la présence d'oxygène sur la croissance du NaCl sur une surface de Fe(001). Conséquemment, un protocole pour la croissance de films de NaCl sur une surface de Fe(001)-p(1x1)O déposés couche par couche. Ces films plats à l'échelle atomique présentent des terrasses de 40-60 nm de large et contiennent beaucoup moins de défauts cristallins que les films de MgO.En utilisant ces couches minces de NaCl comme jonction tunnel facilement ajustables par une modification de leur épaisseur, nous caractérisons le chargement d'électron à température ambiante de nanoparticules individuelles formées par évaporation thermique sur un film de 6 monocouches de NaCl. Nous montrons comment la combinaison de la technique e-EFM et de simulations électrostatiques par éléments finis peut être utilisée pour révéler les propriétés électroniques et morphologiques de nanoparticules d'or individuelles. Ainsi, l'énergie de chargement, la capacitance, la fréquence de passage par effet tunnel et la forme approximative des nanoparticules ont été déterminées. Des simulations numériques montrent que la capacitance totale est dominée par la capacitance mutuelle entre la nanoparticule et l'électrode. En comparant avec les valeurs expérimentales, déterminées par une mesure de l'énergie de chargement, on montre que les nanoparticules devraient être modélisées par des sphères tronquées pour réduire la capacitance mutuelle avec le substrat. Cette observation a un impact fondamental pour le design de circuits nanoélectroniques dans lesquels les composantes doivent avoir des capacitances définies, étant donné que celles-ci déterminent les effets de couplage et de chargement.La flexibilité de la technique de fabrication et le fait que toutes les mesures ont été effectuées in situ sur des échantillons dans des conditions ultra propres rendent le système attrayant pour de futures études.
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Cochran, Ginevra E. "New Computational and Experimental Approaches for Studying Ion Acceleration and the Intense Laser-Plasma Interaction." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534432188474908.
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Cardoch, Sebastian. "Studying Atomic Vibrations by Transmission Electron Microscopy." Thesis, Uppsala universitet, Materialteori, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305370.
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We employ the empirical potential function Airebo to computationally model free-standing Carbon-12 graphene in a classical setting. Our objective is to measure the mean square displacement (MSD) of atoms in the system for different average temperatures and Carbon-13 isotope concentrations. From results of the MSD we aim to develop a technique that employs Transmission Electron Microscopy (TEM), using high-angle annular dark filed (HAADF) detection, to obtain atomic-resolution images. From the thermally diffusive images, produced by the vibrations of atoms, we intent to resolve isotopes types in graphene. For this, we establish a relationship between the full width half maximum (FWHM) of real-space intensity images and MSD for temperature and isotope concentration changes. For the case of changes in the temperature of the system, simulation results show a linear relationship between the MSD as a function of increased temperature in the system, with a slope of 7.858×10-6 Å2/K. We also note a power dependency for the MSD in units of [Å2] with respect to the FWHM in units of [Å] given by FWHM(MSD)=0.20MSD0.53+0.67. For the case of increasing isotope concentration, no statistically significant changes to the MSD of 12C and 13C are noted for graphene systems with 2,000 atoms or more. We note that for the experimental replication of results, noticeable differences in the MSD for systems with approximately 320,000 atoms must be observable. For this, we conclude that isotopes in free-standing graphene cannot be distinguished using TEM.
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Alanazi, Nadyah L. "Studying the Fusion Evaporation Reaction (a,n) with 54Fe, 56Fe, 57Fe, and 58Fe." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1522335214406224.
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Saucedo, Morales Julio Cesar. "The morphology, environment and interstellar medium of early-type galaxies as a means for studying the evolution of galaxies outside of clusters." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289190.
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The main goal of this thesis is to study the properties of isolated early-type galaxies with the hope of learning about their formation and evolution. With this goal in mind, B and I optical, and Ks near infrared images of 4 different samples of early-type galaxies in contrasting galactic density environments have been secured with the Steward Observatory 90 inch and 61 inch telescopes. The 4 early-type galaxy samples consist of: a sample extracted from the Catalog of Isolated Galaxies of Karachentseva, a sample of isolated galaxies previously studied by Fasano and Bonoli, a sample of galaxies from the Hickson Compact Groups Catalog, and a sample of galaxies with detected ISM's. This data set is used to examine whether differences in the galactic environment are related to differences in key properties of early-type galaxies. Multi-color surface photometry analysis is performed on the 4 samples, and the results are used in several contexts. For most of the galaxies in the Karachentseva sample surface photometry is reported for the first time. Likewise, Ks data for most of the objects in this thesis have never been reported. The light profile of the galaxies are fitted with Sersic profile functions. In agreement with other investigations, it is found that the Sersic parameter, n is primarily dependent on the galaxy size, and does not seem to be strongly dependent on properties such as environment or ISM content. The (B - I) color index, ellipticity, position angle, and third and fourth-order Fourier coefficients are derived from the surface photometry. It is confirmed that the third-order coefficients signal the presence of dust, and that the coefficient of the cos(4θ) gives structural information of the galaxies. Furthermore, the subtraction of model ellipticals has revealed peculiarities in the morphology, such as disks, spiral arms, dust lanes, multiple nuclei, etc. The largest and most relevant sample in this investigation consists of 39 galaxies, and it contains ∼25% of the galaxies classified as ellipticals in the Karachentseva catalog. Only approximately one half of the galaxies classified as ellipticals in that catalog appear to be correctly classified, a result which may imply a reduction of the percentage of ellipticals in the Karachentseva catalog to ∼6% of the total population of Isolated Galaxies. A significant number of merger candidates has also been found among the isolated galaxies. It is argued that the fraction of merger candidates to isolated ellipticals can be used to constrain models for the evolution of compact groups into isolated galaxies. The results of CO(1-0) millimetric wavelength observations taken at the NRAO 12 M telescope, as well as submillimeter continuum emission from dust at the SMT are also presented.
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Mattsson, Sandra. "Microscopy techniques for studying polymer-polymer blends." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-157990.
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Semiconductors are used in many electronic applications, for example diodes, solar cells and transistors. Typically, semiconductors are inorganic materials, such as silicon and gallium arsenide, but lately more research and development has been devoted to organic semiconductors, for example semiconducting polymers. One of the reasons is that polymers can be customized, to a greater extent than inorganic semiconductors, to create a material with desired properties. Often, two polymers are blended to obtain the desired function, but two polymers do not usually result in an even blend. Instead they tend to separate from each other to varying degrees. The morphology of the blend affects the material properties, for example how efficiently it can convert electricity to light. In this project, thin films consisting of polymer blends were examined using microscopy techniques for the purpose of increasing our understanding of the morphology of such blends. One goal was to investigate whether a technique called correlative light and electron microscopy can be useful for examining the morphology of these films. In correlative light and electron microscopy, a light microscope and an electron microscope are used in the same location in order to be able to correlate the information from the two microscopes. The second goal was to learn about the morphology of the thin films using various microscopy techniques. The polymers used were Super Yellow and poly(ethylene oxide) with large molecular weight. Super Yellow is a semiconducting and light-emitting polymer while poly(ethylene oxide) is an isolating and non-emitting polymer that can crystallize. In the blend films, large, seemingly crystalline structures appeared. The structures could be up to 1 mm in the lateral direction, while the films were only approximately 170 nm thick. These structures could grow after the films had dried and their shapes were similar to those of poly(ethylene oxide) crystals. Consequently, there is reason to believe that it is the poly(ethylene oxide) that makes up the seemingly crystalline structures, but the structures also emitted more light than the rest of the film, and Raman spectroscopy showed that there was Super Yellow in the same location as the crystals. Among the microscopy techniques used, phase contrast microscopy was particularly interesting. This method visualizes differences in optical path length and was useful for studying polymer blends when the polymers have different indices of refraction. Correlating light and electron microscopy showed that there was a pronounced topographical difference between the seemingly crystalline regions and the rest of the thin film. Light microscopy has a limited resolution due to diffraction, but as long as the resolution of the light microscope is sufficient for seeing phase separation, correlative light and electron microscopy turned out to be a good method for studying the morphology of thin films of polymer blends.Halvledare är viktiga för många elektroniska ändamål eftersom de kan användas till exempelvis dioder, solceller och transistorer. Traditionellt används inorganiska halvledande material som kisel eller galliumarsenid, men på senare tid har allt mer forskning och utveckling inriktat sig mot organiska (kolbaserade) halvledare, såsom halvledande polymerer, bland annat eftersom det i högre utsträckning går att skräddarsy de organiska materialen så att de får önskvärda egenskaper. Ofta blandas två polymerer med varandra för att skapa ett material med nya egenskaper som är önskvärda, men två polymerer brukar inte blandas jämnt utan tenderar att separera från varandra i olika utsträckning. Hur blandningen ser ut (morfologin) påverkar materialets egenskaper, till exempel hur effektivt det omvandlar ström till ljus. Med syfte att öka förståelsen för hur morfologin ser ut hos en blandning av två polymerer, har detta projekt gått ut på att undersöka tunna filmer av polymer-blandningar med hjälp av mikroskopiska tekniker. Ett delmål var att ta reda på om en teknik som heter korrelativ ljus- och elektronmikroskopi är en bra metod för att undersöka morfologin hos dessa filmer. Vid korrelativ ljus- och elektronmikroskopi används både ett ljusmikroskop och ett elektronmikroskop på samma plats för att kunna korrelera informationen som de båda mikroskopen ger. Det andra delmålet var att undersöka vad de olika mikroskopi-teknikerna kan säga om morfologin hos de tunna filmerna. De polymerer som använts är Super Yellow och poly(etylenoxid) med hög molekylmassa. Super Yellow är en oordnad halvledande och ljusemitterande polymer medan poly(etylenoxid) är en isolerande och icke-emitterande polymer som kan kristallisera. I de blandade filmerna uppstod stora kristall-liknande strukturer som kunde vara upp emot 1 mm breda trots att filmerna bara var ungefär 170 nm tunna. Dessa strukturer kunde växa fram efter det att filmerna redan hade torkat och påminde i form om kristaller som kan bildas av poly(etylenoxid). Det finns alltså skäl att tro att det är poly(etylenoxid) som kristalliserats, men de kristall-liknande strukturerna visade sig emittera mer ljus än vad resten av filmen gjorde, och Raman-spektroskopi visade att det även fanns Super Yellow på samma plats som kristallerna. Bland de mikroskopitekniker som testades utmärker sig faskontrastmikroskopi, som visar skillnader i den optiska vägskillnaden (det vill säga faktisk vägskillnad multiplicerat med brytningsindex). Det visade sig vara en intressant teknik för att studera polymerblandningar när de båda polymererna har olika brytningsindex. Genom att korrelera ljus- och elektronmikroskopi visade det sig att det fanns en tydlig skillnad i struktur mellan de kristall-liknande områdena och resten av den tunna filmen. Ljusmikroskopi har begränsad upplösning på grund av ett fenomen som heter diffraktion, men så länge som ljusmikroskopets upplösning är tillräcklig för att se fasseparation visade det sig att korrelativ ljus- och elektronmikroskopi är en bra metod för att studera morfologin hos tunna filmer av polymerblandningar.
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Adkins, James Kevin. "STUDYING TRANSVERSE MOMENTUM DEPENDENT DISTRIBUTIONS IN POLARIZED PROTON COLLISIONS VIA AZIMUTHAL SINGLE SPIN ASYMMETRIES OF CHARGED PIONS IN JETS." UKnowledge, 2017. http://uknowledge.uky.edu/physastron_etds/47.
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A complete, fundamental understanding of the proton must include knowledge of the underlying spin structure. The transversity distribution, h1(x), which describes the transverse spin structure of quarks inside of a transversely polarized proton, is only accessible through channels that couple h1(x) to another chiral odd distribution, such as the Collins fragmentation function (ΔN Dπ/q↑(z,jT)). Significant Collins asymmetries of charged pions have been observed in semi-inclusive deep inelastic scattering (SIDIS) data. These SIDIS asymmetries combined with e+e- process asymmetries have allowed for the extraction of h1(x) and ΔN Dπ/q↑(z,jT). However, the current uncertainties on h1(x) are large compared to the corresponding quark momentum and helicity distributions and reflect the limited statistics and kinematic reach of the available data. In transversely polarized hadronic collisions, Collins asymmetries may be isolated and extracted by measuring the spin dependent azimuthal distributions of charged pions in jets. This thesis will report on the first statistically significant Collins asymmetries extracted from √ s = 200 GeV hadronic collisions using 14 pb-1 of transversely polarized proton collisions at 57% average polarization.
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Scozzi, Federico. "Studying excited states of the nucleon with the HADES detector at GSI." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS593.
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Le sujet de cette thèse est l’analyse de la production de di-électrons dans des réactions induites par des pions avec le détecteur HADES a une énergie dans le centre de masse proche de 1.5 GeV, dans lesquelles des résonances baryoniques dans la deuxième région de résonances (N(1440), N(1520),..) peuvent être excitées. L’objectif est d’obtenir des informations sur les transitions électromagnétiques dans une région inexplorée cinématiquement, où l’on s’attend à ce que les mésons vecteurs jouent un rôle important. Ces mesures peuvent aussi être utilisées comme référence pour les études de production de paires e⁺e⁻ dans la matière hadronique visant à explorer les modifications de la fonction spectrale du ρ. Le document commence par une présentation des résultats déjà obtenus par la collaboration HADES pour la production de di- électrons. Suit une description de l’expérience HADES et de la ligne de faisceau de pions. Les différentes étapes de l’analyse sont ensuite présentées, en insistant sur l’identification des électrons. Une étude détaillée de l’ajustement de la réponse du détecteur RICH, qui est crucial pour la discrimination entre électrons et pions est réalisée. Puis, l’extraction du signal de production de di-électrons, ainsi que les problèmes de soustraction de la contribution de noyaux de carbone pour étudier les interactions pion-nucléon. Les outils existants pour l’interprétation des données sont ensuite introduits. En plus des modèles existants pour la réaction π⁻ρ →ne⁺e⁻, les résultats de l’analyse en ondes partielles des canaux 2πN peuvent être utilisés. La distribution de la masse invariante des paires e⁺e⁻ présente un excès par rapport à la production attendue pour des baryons ponctuels, ce qui confirme le rôle important de mésons _ hors-couche dans les facteurs de forme de transition électromagnétique dans ce domaine cinématique. Les résultats de l’analyse des distributions angulaires en utilisant le formalisme de la matrice densité sont aussi comparés`a un modèle théorique basé sur les contributions de plusieurs résonances. Cette comparaison montre que les distributions angulaires apportent des informations supplémentaires sur la structure des transitions baryoniques électromagnétiques. Cette analyse est utilisée pour motiver des expériences futures pour étudier les transitions électromagnétiques mettant enjeu des baryons non-étrangesThe subject of this thesis is the analysisof dielectron (e⁺e⁻) production channels produced in pion induced reactions with the High Acceptance Di-Electron Spectrometer (HADES) at a center of mass energy close to 1.5 GeV, where baryon resonances in the second resonance region (N(1440), N(1520),...) can be excited. The objective is to bring information on electromagnetic baryon transitions in an unexplored kinematic region, where vector mesons (ρ, w) are expected to play an important role. These measurements can also be used as a reference for studies of in-medium e⁺e⁻ production, investigating the modifications of the ρ meson spectral function. The document begins with a presentation of the results already obtained by the HADES collaboration concerning dielectron production. Then the different steps of the data analysis are presented, with a focus on the electron identification. For this purpose a careful study on how to tune in simulation the response of the RICH detector, fundamental for the discrimination between pions and electrons, is performed. The extraction of the signal for dielectron production is then discussed, together with the problem of subtracting the carbon contribution from the polyethylene target to study pion-nucleon interactions. The existing tools for the interpretation of the data are then presented.In addition to existing models for the π⁻ρ →ne⁺e⁻ reaction, the results of Partial Wave analysis of then γn→ π⁻ρ reaction as well as for π⁻ρ →2 πN channels can be used.The e⁺e⁻ invariant mass distribution shows a clear enhancement with respect to a production by point like baryons, and confirms the significant role of off shell ρ mesons in electromagnetic form factors in this kinematic range. Results of the analysis of the angular distributions using the framework of the spin density matrix are also compared to a theoretical model based on several resonance contributions. This demonstrates the additional information provided by angular distributions to extract information on electromagnetic structure of baryon transitions. This analysis is used to motivate further experiments to study electomagnetic transitions involving non-strange baryons
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Berger, Andrew Joseph. "Studying Spin and Charge Coupling in Operational Spintronic Devices Using Multi-Mode Magnetotransport Scanning Probe Microscopy and Ferromagnetic Resonance." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429702400.
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Grossman, Esther Florence. "Comparing B3LYP and its dispersion-corrected form to B97-D3 for studying adsorption and vibrational spectra in nitrogen reduction." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors155628790845.
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Luong, Vu Hai Nam. "Studying optical micro-resonators coupling for future insertion in an opto-electronic oscillator." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00905958.
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The classical structure of an Opto-Electronic Oscillator (OEO) is based on a long fiber loop acting as a delay line and leading to the high spectral purity, or very low phase noise, of the oscillator. Such an OEO has been developed in SATIE/LPQM laboratory at ENS Cachan, operating at 8 GHz frequency. However, this system has some main disadvantages such as a bulky size, the difficulty to control temperature and a wide range of peaks among which it is difficult to select only one mode. In order to eliminate these disadvantages, high quality factor optical resonator can be used instead of the optical fiber loop. In this thesis, two resonator structures are produced and investigated. Microspheres are fabricated based on optical single mode fiber. Whispering gallery modes of these resonators are characterized by tapered fiber -resonator coupling. The experimental results show that the quality factor of the microsphere is up to 106 and FSR depends on the diameter of the resonator. A microsphere with a diameter of 300 µm, presents a FSR of 0.2 nm corresponding to a frequency of 25 GHz. However, for an OEO system which should work at 8 GHz, microsphere with a smaller FSR or with diameter of some millimeters should be fabricated- that is really difficult to obtain. Another add/drop racetrack resonator is designed and investigated. Optical experimental behavior of racetrack is characterized via fiber micro-lens coupling. The transmission spectrum shows resonance dips with average quality factor of 105 and a small FSR of 0.050 ± 0.003 nm (actually corresponding to 6 GHz) for a scanning wavelength range from 1534 nm to 1610 nm. The most promising features of the racetrack resonator are its high quality factor, and its free spectral range, which give it the high suitability for being used in the OEO system. Nevertheless the coupling with fiber lens leads to high losses and it is not possible to fulfill the oscillation conditions. Future work should be conducted for improving the coupling and for controlling the resonance dips position in agreement with the wavelength of the laser used in the OEO.
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Jelescu, Ileana O. "Magnetic resonance microscopy of Aplysia neurons : studying neurotransmitter-modulated transport and response to stress." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00979419.
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Recent progress in magnetic resonance imaging (MRI) has opened the way for micron-scale resolution, and thus for imaging biological cells. In this thesis work, we performed magnetic resonance microscopy (MRM) on the nervous system of Aplysia californica, a model particularly suited due to its simplicity and to its very large neuronal cell bodies, in the aim of studying cellular-scale processes with various MR contrasts. Experiments were performed on a 17.2 Tesla horizontal magnet, at resolutions down to 25 µm isotropic. Initial work consisted in conceiving and building radiofrequency microcoils adapted to the size of single neurons and ganglia. The first major part of the project consisted in using the manganese ion (Mn2+) as neural tract tracer in the buccal ganglia of Aplysia. Manganese is an MR contrast agent that enters neurons via voltage-gated calcium channels. We performed the mapping of axonal projections from motor neurons into the peripheral nerves of the buccal ganglia. We also confirmed the existence of active Mn2+ transport inside the neural network upon activation with the neurotransmitter dopamine. In the second major part of the project, we tested the potential of two diffusion MRI sequences for microscopy. On the one hand, we explored a very original mechanism for diffusion weighting, DESIRE (Diffusion Enhancement of SIgnal and REsolution), particularly suited for small samples. The two-dimensional DESIRE sequence was implemented and successfully tested on phantoms. The measured enhancement was consistent with theoretical predictions. Using this sequence to produce diffusion weighted images with an unprecedented contrast in biological tissue remains a challenge. On the other hand, a more "standard" sequence was implemented to measure the apparent diffusion coefficient (ADC) in nervous tissue with MRM. This sequence was a three-dimensional DP-FISP (Diffusion Prepared Fast Imaging with Steady-state free Precession), which met criteria for high resolution in a short acquisition time, with minimal artifacts. Using this sequence, we studied the changes in water ADC at different scales in the nervous system, triggered by cellular challenges. The challenges were hypotonic shock or exposure to ouabain. ADC measurements were performed on single isolated neuronal bodies and on ganglia tissue, before and after challenge. Both types of stress produced an ADC increase inside the cell and an ADC decrease at tissue level. The results favor the hypothesis that the increase in membrane surface area associated with cell swelling is responsible for the decrease of water ADC in tissue, typically measured in ischemia or other conditions associated with cell swelling.
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Lopes, Ariane Milani 1981. "Professores de física : práticas e subjetividades no processo de ensinar." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250891.
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Orientador: Elizabeth BarolliDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação
Made available in DSpace on 2018-08-20T23:41:57Z (GMT). No. of bitstreams: 1 Lopes_ArianeMilani_M.pdf: 1811259 bytes, checksum: 12051380b042007758229e22408b3cec (MD5) Previous issue date: 2012
Resumo: O presente trabalho de pesquisa em nível de Mestrado consiste no estudo de caso de professores egressos do curso de licenciatura em física da Unicamp, atuantes na rede pública de São Paulo. A pesquisa é do tipo qualitativa e se apoia em um referencial do campo psicanalítico - os discursos inconscientes do professor em analogia aos discursos inconscientes de Lacan. O texto trata da prática pedagógica do professor de ciências na escola contemporânea, para tanto, traz em seu escopo um resgate histórico dos modelos e teorias pedagógicas presentes no ensino de física desde o início do século XX até os dias atuais, travando um diálogo entre pensadores pós-modernos e seus críticos. Em seguida, com a intenção de compreender como os sujeitos se constituem professores nesta escola, trazemos o caso de dois professores de Física - Raul e Rodolfo - implicados com a profissão e atuantes na educação básica da rede estadual paulista. Através de observação e entrevistas problematizamos os saberes docentes que eles mobilizam e as referências subjetivas que parecem condicionar a condução de suas práticas.
Abstract: This research work in Master's level consists in the case study of teachers graduates of the licenciature course in physics from Unicamp, working in public schools of São Paulo. The research is qualitative and is supported on a referential of the psychoanalytic field - the unconscious discourse of the teacher in analogy to unconscious discourses of Lacan. The text is about the science teacher's pedagogic practice on the contemporary school, so it brings in a scope a historical rescue of the pedagogical models present in physics teaching from the early twentieth century to the present day, engage in a dialogue between thinkers postmodernists and their critics. Then, with the intent to understand how a person becomes a teacher at this school, we bring the case of two physics teachers - Raul and Rodolfo - involved with the profession and working in basic education in the public network of São Paulo. Through observation and interviews with the teachers we brought a problematization of the teacher's knowledge that they mobilize and the subjective references that seem to constrain the conduct of their practices.
Mestrado
Ensino e Práticas Culturais
Mestre em Educação
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Waelkens, Andre. "Studying magnetic turbulence with radio polarimetry." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-102069.
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Khayat, Zeena. "Understanding the mechanism of action of endosomolytic polyamidoamines by studying their physico-chemical properties." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/54271/.
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Polyamidoamines PAAs are a family of synthetic, water-soluble, linear polymers that are synthesised by hydrogen-transfer polyaddition of aliphatic amines or fo's-secondary amines to fo'sacrylamides reviewed by Ferruti et al. 2002. Over the last 15 years, PAAs been developed as drug carriers and as pH-responsive polymers for protein and gene delivery Richardson et al., 2001. The latter, called endosomolytic PAAs, can disrupt membranes at low pH, but the delivery of genes and proteins is still poorly efficient. The precise mode of action is still poorly understood, therefore the main aim of this work was to examine the physico-chemical properties of PAAs in order to better define their mechanism of membrane permeabilisation to allow design of more efficient chemical structures. First PAA ISA1 23 k g/mol and ISA23 52 - 67 k g/mol were synthesised and were characterised using H-NMR, GPC and acid-base titration. In agreement with past studies, ISA23.HC1 demonstrated a pH-dependant haemolytic activity. The solution conformation of ISA23.HC1 was then investigated using small-angle neutron scattering SANS. ISA23.HC1 possessed a Gaussian coil like-shape in solution at all pHs pH 2 to 14 and polymer concentrations examined 10 mg/ml to 50 mg/ml. However as the pH decreased the radius of gyration increased to a maximum Rg 8 nm at pH 3. Surface tension, electron paramagnetic resonance EPR and SANS were then used to investigate the interaction of ISA23.HC1 with simple micelles as model surfaces. Both pH and micelle composition played an important role in the strength of interaction seen. For SDS micelles, three different responses were observed, strong interaction at pH 4.5, weak interaction at pH 4.5 - 6.5, and no interaction at pH 7. However, ISA23.HC1 did not appear to interact with more biologically relevant lyso-PC surfactants at pHs 7.4 - 5.5. EPR experiments showed that micelle fluidity was effected when a PAA-micelle interaction occurred, and SANS reinforced this conclusion. Finally, liposomes were used as a more complex model membrane. Liposomes were prepared to mimic three phospholipids composition of plasma, endosomal and lysosomal membranes. The liposomes were stable over 2 days at pH 7.4, 5.5 and 4, but not at pH 3. SANS was used to study polymer-liposomes interaction, and the Schultz polydisperse 3 shell sphere model was used to fit the liposomal alone SANS scattering data. The radius of the plasma, endosome and lysosome liposomes was 50 nm. When liposomes were incubated in the presence of ISA23.HC1, it was difficult to interpret the scattering data. However, it was clear that at pH 4 and 5.5 scattering of model liposomes alters in the presence of PAA indicating possible interaction. Using a contrast approach the scattering data for ISA23.HC1 in the presence of model liposomes could be extracted. This was again fitted using Gaussian coil model. Generally, the polymer increased in size in the presence of liposomes, at pHs where there was an interaction. However, these are only preliminary experiments, and there is a need for further mathematical modelling. In conclusion, this project emphasise the importance of combining the different disciplines to fully understand a system that can be the first step in finding a way to cure devastating genetic diseases.
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Giatras, Nikoletta. "Studying abroad: physical activity and subjective well-being of international postgraduate students." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492576.
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Overall this mixed methods research provides a unique insight into the experience of students studying abroad in the UK. It highlights cultural differences in student's perceptions of academic life and how these relate to subjective well-being. Physical activity was seen as part of a wider 'lifestyle' where not only structured exercise was valued but also more unstructured physical activity, particularly outside in a social environment. Adaptation and associated stressors are common but ebb and flow over the course of the academic year.
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Fassbender, Rene. "Studying Cosmic Evolution with the XMM-Newton Distant Cluster Project." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-79385.
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Zhang, Jianrui [Verfasser]. "Studying Polymeric Materials with Mesoscopic Models. Focus: Multiscale Properties / Jianrui Zhang." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1223378993/34.
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Tang, Kim-chow Catherine. "Effects of different assessment procedures on tertiary students' approaches to studying /." [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1300945X.
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Myung, Sunnie. "Developing ion mobility methods for studying structure and assembly of biomolecules." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3238509.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2006."Title from dissertation home page (viewed July 16, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: B, page: 5718. Adviser: David E. Clemmer.
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Krin, Anna [Verfasser], and Melanie [Akademischer Betreuer] Schnell. "Studying chiral molecules with broadband microwave spectroscopy / Anna Krin ; Betreuer: Melanie Schnell." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1212180968/34.
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Kraatz, Matthias [Verfasser]. "Studying the Effect of Cu Microstructure on Electromigration Reliability using Statistical Simulation / Matthias Kraatz." Aachen : Shaker, 2014. http://d-nb.info/105034197X/34.
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Biffi, Veronica. "Studying the ICM velocity structure within galaxy clusters with simulations and X-ray observations." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-143375.
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Dietrich, Dennis [Verfasser], and Tobias [Akademischer Betreuer] Lachenmaier. "Studying the muon background component in the Double Chooz experiment / Dennis Dietrich ; Betreuer: Tobias Lachenmaier." Tübingen : Universitätsbibliothek Tübingen, 2013. http://d-nb.info/1162844051/34.
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Grünbein, Marie Luise [Verfasser]. "Studying protein dynamics with X-ray free-electron lasers: Opportunities & Limitations / Marie Luise Grünbein." Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1233286579/34.
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Dayan, Saeid, and Hakim Ejal. "”Man känner sig liksom klar i hjärnan” : En kvalitativ studie om sambandet mellan fysisk aktivitet och studiero." Thesis, Södertörns högskola, Lärarutbildningen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-39958.
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It is often emphasized that children and young people around the world are too inactive, that the schools only focus on theoretical learning and that children in school lack concentration or wander too much in the classroom. The connection between the aforementioned observations was something we wanted to interpret and was something that we found interesting. In order to answer our questions we approached them from a child’s point of view. The purpose of this study was to examine the correlation between physical activity and quietude for studying. This survey was conducted at two schools that participate in a project where they add more scheduled physical activity. Applying qualitative research methods such as interviews and observations, we obtained results that were then analyzed from different perspectives on learning and physiological processes, including theories about learning. The results showed that both the students and educators in the study considered that physical activity had positive effects. Furthermore, the results showed that the students perceived that physical activity leads to increased quietude for studying. Educators were also positive about the effects of physical activities had on studies, but they considered that structure and clarity were also important. From our research we can conclude that the students agree that having physical activity in school is advantageous.
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Saville, Brian K. "A Framework for Studying the Physical Degradation Characteristics of DVDs and Their Relationship to Digital Errors." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2893.
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The methods used to store data on DVD-R discs have been proven to work over the last 15 years. However, there has been a growing concern that these discs will be outlasted by the paper records they were meant to replace. The data on a DVD-R is stored as optical contrasts which have the potential to be misread and even damaged. This damage may occur either on the surface or internally to the disc, especially on the recording layer itself. The literature is saturated with studies attempting to determine the time period in which discs may fail and what the general signs of the degradation are, but almost all fail to determine the fundamental causes of DVD degradation. In particular, the exact connection between the physical state of the disc and its digital errors is undetermined. This study undertook to develop a framework to study and understand this relationship. The study also consisted of a characterization validation experiment involving several brands of DVD-Rs. The framework constructed during the course of the research included several tools. Due to the lack of an existing tool able to aggregate the gathered data, a specialized software program, called SectorDraw, was developed. In the course of this study, this software tool was validated. Additionally, it was discovered that physical defects should be evaluated and characterized by using a process of visual inspection, microscope examination, and measurements. Although not all relationships between physical defects and digital errors were explored, the study established the fact that defects can directly cause bursts of digital errors. This indicated that there was a connection between physical defects and digital errors. It was also found that physical defects developed over time after treatments of artificial aging. The developed framework was established as viable for future research to study specific relationships between physical defects and digital errors.
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Tang, Kim-chow Catherine, and 鄧劍秋. "Effects of different assessment procedures on tertiary students' approaches to studying." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31232413.
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