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PhD defense

Transcript: Partial vs. impartial Trust Personality Competence A need for the question: who performs the practice we want to change? Gender focus in practical initiatives and policy programmes 4 social dimensions When you have received the text messages to change the timing of your electricity consumption, how often have you decided to do the following in order to change the timing of your electricity consumption? Changed the timing of washing (1)  (2)  (3)  (4)  (5)  (6)  Changed the timing of dishwashing (1)  (2)  (3)  (4)  (5)  (6)  Changed the timing of tumble drying (1)  (2)  (3)  (4)  (5)  (6)  Changed the timing of charging of phone, etc (1)  (2)  (3)  (4)  (5)  (6)  "When we bought the house, it had a thatched roof. It was old and needed to be changed. We could easily have chosen another type of roof. It would have been cheaper and cost less in insurance. But, no, it had to be a thatched roof. We wanted to be faithful to the original style of the house, which is why we also kept the old plank flooring". never Background INCAP Social and gendered engagements significantly impact decisions on energy renovations and practices of flexible electricity use. Aim: to investigate the importance of gendered practices for how households react to flexible electricity use. West and Zimmerman This is your area, John Motivation of the private households Focus on collective action Reaching the environmental sceptics More power and security Relying on a few passionate participants Little experience in the area Lise Tjørring, Industrial PhD defense, November 16th 2017 Partners The positioning in the life cycle influenced people's willingness and capacity to energy renovate Targeting women or rethinking the way we develop solutions? Loosening the boundaries of fixed categories? Financial incentives vs. a focus on (gendered) practices Theoretical attention Aim: to investigate the significance of gender in private households for decisions on energy renovations. Those green tiles in the bathroom, they have to go Foucault From homogenous households to engagements between household members, home and energy advisor Conducted by co-author: • Participant observation in a variety of meetings, an energy fair and conferences • Literature study • Semi-structured interviews with project managers, citizens and builders The process of analysis I'm in the bathroom for 5 min Research focus Paper 1 addresses the social engagement between the energy advisor and the family and between the home and the human actors in the context of energy renovation. Paper 2 addresses the gendered engagement between the energy advisor and the family in the context of energy renovation. Paper 3 addresses the gendered engagement between the energy advisor and the family in the context of flexible electricity use. Paper 4 addresses the social engagement between the home and the human actors in the context of energy renovation. Austin A gap between what the energy advisors think people want and what people really want The importance of empathy Homes instead of houses Influencing vs. being influenced Data from interviews Paper 2: Conclusion How important will it be for you to move the timing of your electricity consumption when you, during the test period, receive text messages telling you the best time of the day to use electricity? (1)  Very important (2)  Important (3)  Slightly important (4)  Less important (5)  Not important (6)  Don’t know Bias Data collection As perceived by the households Aim: An investigation of the possibilities for flexible electricity consumption in private households. Partners: University of Copenhagen, the energy company SE, the Technical University of Denmark (DTU), Stanford University and the private company Develco. One year field experiment with 71 participants. Main findings Althusser We both retire this summer, then we'll get the time and money to renovate......... Merleau-Ponty Paper 1: Energy renovation models in private households in Denmark Research objective "I often answer a question twice. First in a technical manner, and then I talk about the soft values..." Phenomenological anthropology Practical engagement in the world The dwelling perspective I don't want people to drive through the village and see my ugly solar panels The role of the energy adviser Financing aspects Project evaluation methods The value of community vs. individual approaches Motivation of the private households Questionnaire 1 Questionnaire results Money Comfort Task Man Woman Both Laundry 10% 70% 20% H.M. 100% Cooking 10% 50% 40% Cleaning 10% 90% Dishes 20% 20% 60% not very often The typical energy consultation: - the energy advisor primarily talks to the man - the man takes on an active role, the woman a passive role - Taking for granted that the man knows about maintenance Men and women have different priorities for energy renovation based on their practices in the house The connection between gender and doings Practice as a

PhD defense

Transcript: 1- Introduction 2- Theories and method 3- Chaterization and application 4-Conclusion 5- The connection Drug Delivery: -What ? -Why ? * The release ability of these two materials have been compared in term of using small molecules drug. However, silica nanotubes proved to be more suitable with large molecules drug. * This nanostructured tubes have been used with anti-cancer Doxorubicin and optimized the geometry for minimum energy using Hyperchem. Resultes were comparable with previously reported data. * Steric effects plays an important role in the loading efficency. Si-Ti-Sv * The efficiency of silica-titania sieves as bioactive materials as well as their potential to be a suitable nano-carrier have been examined by using a new anti-bacterial agent, Izohidrafural * Izohidrafural, the new antibiotic agent exhibited the highest antimicrobial efficiency, superior to the common drug Nitrofurantoin against the majority of E. coli strains, with average MIC of (4.68 µg/mL), followed by silica-titania sieves loaded with Izohidrafural. * The non-loaded silica-titanium sieves exhibited the highest antimicrobial activity against the gram-positive cocci. Nitrofurantoin Preparation technique Sol-Gel Sol-Gel Adjustments: Synergistic effect The synergistic effect might occur due to the fact that the Titanium dioxide, in form of anatase, in Si-Ti-Sv, has photocatalytic properties and thus the ability of creating reactive oxygen species (ROS)... Reported mechanism.G. Timmins et. al. (2006) The biological activity of isoniazid states (in Izo.) The presence of an oxidizing enzyme, KatG, the molecule is transformed into radical species BY TiO2 such as acyl, acylperoxo and pyridyl radicals... We may presume that TiO2 plays a role in activating Izohidrafural producing thus a synergistic effect... http://www.sigmaaldrich.com/technical-documents/articles/material-matters/mesoporous-materials.html Nanostructured silica MCM-41 The chemical structure for this drug is analogue to some extent with Nitrofurantoin, Urinary Tract Infections On the other hand the ORIENTATION of the calculated dipole moment, YELLOW ARROW favors the penetration of the molecule in polar cavities as it is for MCM-41. = slightly Higher Loading http://www.chromacademy.com/lms/sco5/10-Selecting-Reversed-Phase-Columns.html fChannel=6&fCourse=64&fSco=410&fPath=sco5/10-Selecting-Reversed-Phase-Columns.html Nitrofurazone Quantum Mechanics Izohidrafural Ibuprofen: Anti-inflammatory drug BASE MATERIAL -Adding Surfactant This method will be applied with other drugs For Detecting EE % Other Characterizations: *Three types of silica nanostructured materials have been prepared as drug carriers *The preparation technique follows the principals of sol-gel method, where the prepared silica materials were MCM-41, silica nanotubes and silica-titania sieves. *The obtained nanomaterials were characterized according to different considerations *The characterization methods were: SEM, TEM, EDAX, XRD, BET and FT-IR. *Silica-titania six different samples, according to different preparation medium and calcination conditions. *Silica nanotubes and MCM-41 were compared as a carrier materials for Ibuprofen with different encapsulation efficiencies and release profiles . The reason behind that proved to be related to the pore size of those two materials. General Atomic and Molecular Electronic Structure System (GAMESS) FTIR REFERENCES [1] L. P. Singh, S. K. Agarwal, S. K. Bhattacharyya, U. Sharma, S. Ahalawat, Nanomater. nanotechnol. 1 (2011) 44-51. [2] R. Stan, C. Ott, S. Rosca, A. Badanoiu, S.Stoleriu, G. Voicu, U.P.B. Sci. Bull., Series B 3 (2008) 1454-2331 [3] F. Kamar, A. Nechifor, M. Ridha, M. B. M. Al Tameemi, G. Nechifor, REV. CHIM. 66 (2015) 921-925. [4] Fruijtier-Polloth C., Toxicology 294 (2012) 61– 79. [5] D. Dykxhoorn, J. Lieberman, Cell 2 (2006) 231-5. [6] D. Dykxhoorn, D. Chowdhury, J. Lieberman, Dordrecht: Springer (2008) 299-329. [7] M. B. M. Al tameemi, Master thesis, EMU, university publications, Doi: http://hdl.handle.net/11129/1517 [8] L. Yan, X.Chen, Nanocrystalline Materials (2013) 221-268. [9] S. Ranghar, P. Sirohi, P. Verma, V. Agarwal, Braz. Arch. Biol. Technol 57 (2014) 209-222. [10] C. S. S. Kumar, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim (2006). ISBN: 3-527-31382-6 V [11] C. S. S. Kumar, WILEY-VCH Verlag GmbH & Co. KGa (2007). [12] I. Rahman, V. Padavettan, Journal of Nanomaterials (2012) 15. [13] W. Stober, A. Fink, J. Bohn, J. Coll. Int. Sci. 26 (1968) 62. [14] G. Bogush, C. Zukoski, J. Non‐Cryst. Sol. 104 (1988) 95. [15] J. Shi, L. Guo, F. Cui, X. Cui, Microporous and Mesoporous Materials 117 (2009) 609. [16] I. Rahman, P. Vejayakumaran, C. Chee, Ceramics International 32 (2006) 691. [17] Z. Wang, J. Zhao, X. Ding, K. Yu, Materials letters 59 (2005) 4013. [18] K. Ikari, K. Suzuki, H. Imai, Langmuir 22 (2006) 802. [19] Y. Han, J. Ying, Angewandte Chemie International Edition 44 (2004) 288–292. [20] T. Tan, S. Liu, Y. Zhang, M.-Y. Han, S. Selvan,

PhD defense

Transcript: Relationship Between Laboratory and Field Tests in Service Life Assessment of Wood-based Materials Davor Kržišnik Introduction Introduction Laboratory vs. Field Tests Laboratory vs. Field Tests Service Life Assessment Service Life Assessment Functional Service Life Functional Service Life Exposure dose (DEd) ≤ Resistance dose (DRd) DRd = Dcrit × kwa × kinh Aesthetic Service Life Aesthetic Service Life The criterion of service life is subjective, depending on different criteria, such as colour stability of surfaces, cracks, dyeing due to the action of fungi and molds ... Wood-based Materials Wood-based materials Relationship Relationship Exposure position of wood and wood-based materials has a significant influence on moisture content. Hypothesis number 1 Publications Materials and Methods Materials and Methods Materials Methods Methods North North facing façade South South facing façade East East facing façade West West facing façade Decking Decking Stand Stand Results Conclusion Exposure position of wood and wood-based materials has a significant influence on moisture content. Improperly performed impregnation of wood with biocides does not significantly improve the service life of wood in contact and above ground exposure. Hypothesis number 2 Publications Materials and methods Materials and Methods Franja partisan hospital 2007 2012 Assessment of the decay Resistograph measurements and Retention of a wood preservative analysis Continuous monitoring of T and MC Results Results Assessment of the decay Monitoring Conclusion Improperly performed impregnation of wood with biocides does not significantly improve the service life of wood in contact and above ground exposure. Greying and blue staining of the wood surface is a continuous cyclical process. Hypothesis number 3 Publications Materials and methods Materials and methods Materials Laboratory test EN 152 test Artificial weathering In-service test Colour measurements Results Results Laboratory test In-service test In-service test Conclusion Greying and blue staining of the wood surface is a continuous cyclical process. Results obtained from field and laboratory tests are not easily comparable to one another. Hypothesis number 4 Publications Materials and methods Materials Methods Results 1st year 2nd year 3rd year 4th year 1st year 2nd year 3rd year 4th year 60 % RH prEN 16818 ±0.7000 - ±0.7999 ±0.8000 - ±0.8999 ±0.9000 - ±1.0000 ±0.7000 - ±0.7999 ±0.8000 - ±0.8999 ±0.9000 - ±1.0000 ±0.7000 - ±0.7999 ±0.8000 - ±0.8999 ±0.9000 - ±1.0000 Conclusion Results obtained from field and laboratory tests are not easily comparable to one another. Summary Summary H1: Exposure position of wood and wood-based materials has a significant influence on moisture content. H2: Improperly performed impregnation of wood with biocides does not significantly improve the service life of wood in contact and above ground exposure. H3: Greying and blue staining of the wood surface is a continuous cyclical process. H4: Results obtained from field and laboratory tests are not easily comparable to one another. Future work Future work Aesthetic Service Life * Colour modeling as a function of a climatic exposure Future work * Different laboratory tests * Different approach for correlation calculations Future work Functional Service Life

PhD defense

Transcript: Outlook bead radius viscosity excellent agreement of theory and experiment no additional terms needed symmetry breaking necessary for net pumping of fluid rows, arrays of cilia: larger pumping effects, nearly homogeneous flow above the ciliated surface external magnetic field t = 160 s opening angle, tilt angle, offsets, adding the microparticles, initial distribution vacuum permeability ability of support, adhere the cells, promotion of cell growth a variety of possible scaffold shapes, possibility of enlargement during experiment low Reynolds number hydrodynamics - magneto-optical tweezers - self-assembled chains composed of superparamagnetic beads - self-assembled colloidal scaffolds wave optics description Navier-Stokes equation point dipole wavelength Gašper Kokot adviser: dr. Andrej Vilfan SRA adviser: dr. Mojca Vilfan Hydrodynamic coupling marked difference between longitudinal and transverse coupling coefficients for rods (not 2 as in bulk for a sphere) - wall effects distance dependence of the coupling coefficient of the rods was found to be different for longitudinal and transverse direction - models have to take it into account brightfield optical tweezers pulling fluorescence magnetic susceptibility biomimetics superparamagnetic beads simulation: mobility matrix with the Rotne-Prager approximation incompressibility Measuring forces with magneto-optical tweezers in biological and biomimetic systems magnetic field calibration volume Self-assembled artificial cilia Aim artificial system: simplified, more control over parameters physical model with external drive Introduction 1/d dependance for both longitudinal (purple) and transverse (blue), ratio stays 2 cell growth proof of principle density magnetic filed, no colloids swimming, pumping, feeding, cleaning, body symmetry determination ... magneto-optical tweezers detailed study of flow around a cilium direct illumination photolithography ray optics description Colloidal scaffolds for cell growth clean glass external force density t = 0 s typical velocity bead separation (scaffold bearing force measurements) t = 20 s efficient biological systems typical length evolution pressure artificial cell support: self-assembled structures artificial cilia: microfluidic pumps collective effects: coordinated movement rapid magnetic field oscillation 3 velocity Stokes equation hydrodynamic coupling coefficient measurements development of a simple method of artificial cilia carpets fabrication studying other beating patterns hydrodynamic coupling under combined influence of several cilia heterostructured particles - a variety of shapes and colloids colloidal scaffolds - coatings, interaction potentials, shapes, sizes slow oscillation of magnetic field resistive force theory, Blake tensor expansion to 1/r terms, temporal and spatial average: light sensitive polymer cross-linking after exposure to UV light hydrodynamic coupling measurement: driven and passive cilium t = 120 h Experimental methods cilia: arrays, complicated beating pattern fluorescent tracer particles trajectory analysis flow maps pumping velocity calculated colloids, no magnetic field Actuated flow

PhD Defense

Transcript: Reaction Convection Diffusion Thank you for your attention Pressure in the stented arterial wall Matching conditions on the interface Biodegradable Polymer (PLA) Fully embedded stent in the arterial wall Stiffness of the arterial wall Affinity of the arterial wall Future works Evolution of the drug mass in the arterial wall for different values of κ_r for long time (Maxwell-Wiechert model) Center for Mathematics, University of Coimbra (CMUC) FCT-Grant SFRH/BD/51167/2010 Acknowledgments Velocity and pressure in the arterial wall 3-parameter solid model Tiny expandable metallic mesh tube Non-Fickian Models for Biodegradable Drug Eluting Stents Convection Weak formulation Numerical study Modeling Where Velocity in the stented arterial wall Main assumptions PDE solver freeFEM++ 3688 elements (1968 vertices) for the arterial wall and 100 elements (83 vertices) for each stent Implicit-Explicit (IMEX) backward formula in the uniform time grid Piecewise linear finite element space for concentration and pressure Velocity and pressure in the stent A DES with topcoat Reaction Conclusions and future works Numerical Experiments Coupling the model with the blood flow equations Gradual stent embedding using moving boundary problems Fully bioabsorbable stent (ABSORB, Abbott Vascular) DES without topcoat Analytical study Mathematical modeling Qualitative behavior of the total mass of the system Motivation Maxwell-Wiechert viscoelastic model Conclusions 2D coupled model to simulate drug release from a polymeric stent to the arterial wall. Biodegradable coating and viscoelasticity and affinity of the arterial wall Three particular aspects of clinical importance are included: A: The influence of the stiffness of the arterial wall on the drug accumulation in the arterial wall, B: The effect of permeability of the stent coating on the drug release from the stent, C: The effect of affinity of the arterial wall on the dug release, Atherosclerosis Stability Drug Eluting Stent Drug release from polymeric stent into the arterial wall Publications where Viscoelastic effect Ferreira, J.A., Naghipoor, J. and de Oliveira, P. (2015), Numerical and analytical study of a coupled cardiovascular drug delivery model, Journal of Computational and Applied Mathematics, 275, 433-446 Ferreira, J.A., Naghipoor, J. and de Oliveira, P. (2013), Numerical simulation of a coupled cardiovascular drug delivery model, Proceeding of 13th International Conference on Computational and Mathematical Methods in Science and Engineering, , CMMSE2013 (II), I. P. Hamilton and J. Vigo-Aguiar (editors), 642-653, Almeria, Spain Ferreira, J.A., Naghipoor, J. and de Oliveira, P. (2014), The effect of reversible binding sites on the drug release from drug eluting stent, Proceeding of 14th International Conference on Computational and Mathematical Methods in Science and Engineering, CMMSE2014(II), I. P. Hamilton and J. Vigo-Aguiar (editors), 519-530, Cadiz, Spain Ferreira, J.A., Naghipoor, J. and de Oliveira, P., A Coupled Non-Fickian Model of a Cardiovascular Drug Delivery System, CMUC Preprint 14-13, Submitted Evolution of the drug mass in the arterial wall for different values of κ_r for long time (Fung’s model) T. Khamdaenga, J. Luo , J. Vappou, P. Terdtoon and E.E. Konofagou, Arterial stiffness identification of the human carotid artery using the stress-strain relationship in vivo, Ultrasonic 52 (3) (2012) 402-411. Arterial stiffness has been shown to be an excellent indicator of cardiovascular morbidity and mortality in a large percentage of the patients with atherosclerosis Chemical reactions in the stent 1) 1 2) 1 2 Chemical reaction in the vessel wall Reversible binding in the vessel wall Reactions in the coated stent Reactions in the arterial wall + initial and boundary conditions Initial mass the mass of plasma that enters in the system until time t the mass of hydrolyzed oligomers until time t the mass of the components that are on the boundary until time t Distribution of drug in the arterial wall in the model without binding, 30 days Distribution of drug in the arterial wall in the model with binding, 30 days

PhD defense

Transcript: < 26 Accretion is like brewing coffee STARS ARE BORN IN LARGE COMPLEXES t Angular momentum cannot be lost 0 Outward transport occurs predominantly in disk plane in radial direction due to magnetic fields. Zoom-simulations are necessary to account for differences in protostellar environments Al I Supervisors: Åke Nordlund, Troels Haugbølle Luminosity problem Build the bridge between planet formation and star formation 27 ~4.567 Gyr MHD = Magnetohydrodynamics II / ANGULAR MOMENTUM TRANSPORT SUMMARY FUN puzzle M Angular momentum: distance from center of rotation x mass x rotational velocity Of course... 1 pc ~ 206 000 AU III AGE OF THE SOLAR SYSTEM 8 * Age Outflow STARS FORM IN DIFFERENT ENVIRONMENTS Sink particles Expensive! (Resolution) ... Al III IN PRACTICE 27 Origin of in Calcium-Aluminium-rich inclusions abundances of gas phase and stars AMR = Adaptive Mesh Refinement physical What's the effect of the stellar environment? ACCRETION PROCESSES IN STAR FORMATION TMA = Too many acronyms Angular momentum problem NOT! 50 AU PROCEDURE Stars form in Giant Molecular Clouds III Sketches: M. Persson 50 kyr after star formation Different environment = different disk Al ARTICLES < 0 I I TO DO: ...with the help of DISPATCH... PROCEDURE Synthetic observations Carried out in modified version of RAMSES ... differs from star to star Only ideal MHD No radiative transfer No dust No chemistry ... I I Turbulence as a result of supernova feedback Start from a snapshot of a young Giant Molecular Cloud obtained from a previous simulation PROCEDURE Everything solved? We use adaptive mesh refinement (AMR) and evolve the equations for ideal magnetohydrodynamics (MHD). Class 0 object HOPS 383 Credit: Paolo Padoan/Tim Sandstrom (NASA) II PLANET FORMATION II But important to constrain initial conditions of disk models! I / 1 AU = Distance from Sun to Earth (~150 million km) Zoom-in for 11 stars => The closer the mass falls towards the center, the faster it rotates Conservative form Image: Orion Molecular Cloud Complex III Image of HL Tau Zoom-in to constrain results Significant differences due to contamination are very unlikely CLASSICAL PICTURE Al MAIN POINTS Infall Issues and challenges: Thermal processing of dust grains (?) numerical IV I Michael Küffmeier 26 (0.2 HETEROGENEOUS ACCRETION ) 1 pc ~ 206 000 AU DISPATCH: A Numerical Simulation Framework for the Exa-scale Era. I. Fundamentals ... is heterogeneous in time (episodic events due to infall) Solution: Angular momentum transport, but how? Proposed (Gedanken) model: Thermal processing of dust grains ONE last thing... Nordlund, Ramsey, Popovas & Küffmeier 2017, submitted to MNRAS I II STAR AND DISK FORMATION Age II Idea: Sublimation time is Protostellar accretion is heterogeneous in space and in time Reynolds: "Motion of the gas" ZOOM-IN 1 pc ~ 206 000 AU 0 ~4 kAU t - ~10 kyr t 0 100 kyr Zoom-in to level 22 (2 AU) ~100 AU 0 Parental run with level 16 (min cell size 126 AU) 4 Myr 40 pc 40 pc 51 kyr 52 kyr Zoom-in to level 27 (0.06 AU) Cell size: length of box / 2 Level 50 AU Model stars with sink particles Calcium- Aluminium- rich inclusion (CAI) formed directly out of the gas phase Connelly et al. 2012 1 cm explicitly include The Sun: 99.9 % of solar system mass less than 1 % of angular momentum CAIs form close to the proto-Sun within the first 10 thousand years of the solar system Haugbølle et al. 2017 Hammer projection r=50 AU, t=100 kyr after star formation Level 4 fluid 52 kyr 51 kyr Zoom-in to level 27 (0.06 AU) M Sun 3 (40 pc) box (AMR, ideal MHD) Adaptive Mesh Refinement MagnetoHydroDynamics 27 Al Disks form early - and dust growth starts early 26 60 Al Fe and Tracking the distribution of during the early phases of star and disk evolution Küffmeier, Frostholm, Haugbølle, Bizzarro & Nordlund 2016, published in ApJ I movement Safron et al. 2015 CLASSICAL PICTURE Continuity equation Momentum equation Energy equation Induction equation Gauss law for magnetism Ideal magnetohydrodynamics (MHD) equations Parental run with 16 levels (min cell size 126 AU) 0 4 Myr 40 pc 40 pc Teyssier 2002 Fromang et al. 2006 Infall M Sun 26 Al => potential differences in (remember: CAIs form directly out of the gas phase) 0 t 0 Zoom-in with 22 levels (2 AU) 100 kyr t - ~10 kyr ~100 AU ~4 kAU accretion rate 26 Al 100 kyr t - ~10 kyr Zoom-in to level 22 (2 AU) ~100 AU ~4 kAU What's going on here? Gravity: "Spiral arms" Disk Level 3 -5 canonical value for CAIs: 5x10 27 26 Al Al / : -6 FUN CAIs <5x10 flux luminosity Supernova injection unlikely Parental run with level 16 (min cell size 126 AU) 0 4 Myr 40 pc 40 pc Level 2 Our model doesn't Parental run with 16 levels (min cell size 126 AU) 0 4 Myr 40 pc 40 pc 1 pc ~ 206 000 AU magnetic field Maxwell: "Magnetic fields" Reynolds: "Motion of the gas" Gravity: "spiral arms" Total Haugbølle and Nordlund Accretion is heterogenous Infall Disk Star Star Accretion ... ... is heterogeneous in space around each individual star CAIs with high temperature minerals

PhD Defense

Transcript: Hitziger et al. Electro-metabolic coupling investigated with jitter invariant dictionary learning, HBM 2014. Results SNR [dB] presented by Sebastian Hitziger Bruno Torrésani Alain Rakotomamonjy template vs. random Coefficient updates = sparse coding Matching pursuit (MP) Epoching (often manually): problematic if Response onsets are unknown Responses overlap Averaging: problematic if Response latencies vary Response shape changes alternate Hitziger et al. Jitter-adaptive dictionary learning - application to multi-trial neuroelectric signals, ICLR 2013. Collaborators Compared techniques Contiguous AWL from http://jonlieffmd.com Invited guest Main contributions Single long signal Multiple occurrences (overlaps) Variable latencies and durations Implementation: MP (detection) MC-Spike/AD-Spike Lasso problem maximal spiking potential Statistical independence of components Combine previous models Evaluation Stepwise activation using LARS Every step: ensure uniqueness (and non-negativity) AD-Spike/MC-Spike benefit from relearning bad template Difficult to know a priori Hierarchical approach Task-dependent stopping criterion Large noise levels (background activity) No ground truth -> Adequate modeling -> Statistical learning from data Epoching + averaging too simplistic Signal variability (amplitudes, latencies, wave shapes) Complex data (multi-channel, multi-trial, multi-modal) CBF activity around 1 Hz (respiration) Local spiking rates (LSR) match CBF activity Spikes synchronize, phase-locked to CBF rhythm Examiners Short epochs/trials Uniqueness constraint Jitter compensation Implementation: LARS General model Generic algorithm Coefficient updates High spiking activity = high CBF level MC-Spike Detection step Reviewers time to previous spike [s] Use matching pursuit Ensure minimal distance constraint Sandrine Saillet Alexandre Gramfort Christian G. Bénar Bruno Torrésani Tallon-Baudry and Bertrand (1999) Each method addresses only one type of variability Laure Blanc-Féraud Christian G. Bénar Coefficients provide clustering Spike-to-spike distances correlate with spike energies Number of waveforms No epoching Multiple responses Sparsity of components 6) Conclusion Processing full LFP recording Dynamic time warping Speech processing (Itakura, 1975; Sakoe and Chiba, 1971, 1978) Event-related potentials (Picton et al., 1988) Latency compensation Multi-component models Time-frequency representations frequency [Hz] Summation of electromagnetic fields Alternate minimization Woody (1967) Weighted average over isolated spikes Normalization + alignment of peaks Advisors No individual CBF response visible Non-linear summation of responses Overlapping effects: epoching problematic Multi-class spike learning (no dilations) Hierarchical structure, start with alternate Maximizes variance Orthogonality between components Shortcomings No explicit modeling of temporal variability Create dictionary Dictionary learning (DL): http://biomedicalengineering.yolasite.com/neurons.php Hitziger et al. Adaptive waveform learning - application to single- and multi-modal neurological data, in preparation. Adaptive waveform learning (AWL) The general model Jung et al. (2000) 3) Adaptive Waveform Learning (AWL) Using noisy spike template Rescaling of time axis Representations in Fourier or wavelet bases Meaningful representations: time-frequency Complex values: separate phase and amplitude Finite set : discretization of "variability space" Sum over p: multiple occurrences per waveform PhD Defense April 14, 2015 Fast Spiking Rates Coefficients Waveform updates 1) Neural Activity in the Brain 4) Epoched AWL Spikes well isolated Clear CBF response after each spike Modeling the Variability of Electrical Activity in the Brain LFP-CBF recording Within ANR project Multimodel Recording in 6 anesthetized rats with bicuculline injection (epilepsy model) Goal: develop/evaluate models explaining parameter couplings Realigned average for every waveform Normalization + centering Discussion E-AWL specialization Insightful representations Clear artifact separation Comparison to PCA, ICA, template matching Deformations of signal components Coefficient updates Convex problem Solve sequentially for each : generalized averaging Normalization + centering Essentially averaging Choice of right basis Multi-channel extension (preliminary results Papageorgakis, 2014) Different specializations/applications (MEG, detect sleep spindles, ...) More general deformations (e.g., dynamic time warping) Time frequency version Hemodynamic coupling more studies needed Interneuronal communication S. Hitziger, M. Clerc, S. Saillet, A. Gramfort, C. Bénar, T. Papadopoulo. Electro-metabolic coupling investigated with jitter invariant dictionary learning, International Human Brain Mapping Conference (HBM), 2014. S. Hitziger, M. Clerc, S. Saillet, A. Gramfort, C. Bénar, T. Papadopoulo. Jitter-adaptive dictionary learning - application to multi-trial neuroelectric signals, International

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