Image restoration using geometrically stabilized reverse heat equation

Blind restoration of blurred images is a classical ill-posed problem. There has been considerable interest in the use of partial differential equations to solve this problem. The blurring of an image has traditionally been modeled by Witkin [10] and Koenderink [4] by the heat equation. This has been the basis of the Gaussian scale space. However, a similar theoretical formulation has not been possible for deblurring of images due to the ill-posed nature of the reverse heat equation. Here we consider the stabilization of the reverse heat equation. We do this by damping the distortion along the edges by adding a normal component of the heat equation in the forward direction. We use a stopping criterion based on the divergence of the curvature in the resulting reverse heat flow. The resulting stabilized reverse heat flow makes it possible to solve the challenging problem of blind space varying deconvolution. The method is justified by a varied set of experimental results

Oncogenesis- kaleidoscopic and multi-level reality

Oncogenesis is an extremely complex phenomenon. The mechanisms by which cancer is induced is only partially known. Consequently, therapeutic targets may be uncertain and results are often unsatisfactory. The purpose of this paper is to develop a trans-level and multiple transdisciplinary perspective describing the kaleidoscopic reality of oncogenesis. This manner of understanding oncogenesis as a complex process characterized by a non-linear dynamic, far from equilibrium and with unpredictable evolution, transcends the classical perspective and requires a paradigm shift. This approach is also facilitated by recent studies that focus on group phenomena, with emerging behaviors in a continuous phase transition. Biological systems, and obviously the human organism, express this type of behavior with critical self-organizing valences in the context of a genome - mesotope (environment) - phenotype interaction. For example, nature has transposed in the ecosystem, among other things, the performance pattern of its mineral history represented by the dynamic energy-matter-information unit (the principle of invariance). And multi-cell biological systems in the phylogenetic tree crown have multiple directed aerobic metabolisms in accordance with specific functions. Cancers, in turn, have a hybrid (anaerobic and aerobic) and unidirectional metabolism whose only and ultimate reason is the survival of the malignant cell. Understanding the transdisciplinary reality of oncogenesis offers novel development paths for new therapeutic strategies compared to current ones which have relatively limited efficiency

Project Tech Top study of lunar, planetary and solar topography Final report

Data acquisition techniques for information on lunar, planetary, and solar topograph

Compressive Wave Computation

This paper considers large-scale simulations of wave propagation phenomena. We argue that it is possible to accurately compute a wavefield by decomposing it onto a largely incomplete set of eigenfunctions of the Helmholtz operator, chosen at random, and that this provides a natural way of parallelizing wave simulations for memory-intensive applications. This paper shows that L1-Helmholtz recovery makes sense for wave computation, and identifies a regime in which it is provably effective: the one-dimensional wave equation with coefficients of small bounded variation. Under suitable assumptions we show that the number of eigenfunctions needed to evolve a sparse wavefield defined on N points, accurately with very high probability, is bounded by C log(N) log(log(N)), where C is related to the desired accuracy and can be made to grow at a much slower rate than N when the solution is sparse. The PDE estimates that underlie this result are new to the authors' knowledge and may be of independent mathematical interest; they include an L1 estimate for the wave equation, an estimate of extension of eigenfunctions, and a bound for eigenvalue gaps in Sturm-Liouville problems. Numerical examples are presented in one spatial dimension and show that as few as 10 percents of all eigenfunctions can suffice for accurate results. Finally, we argue that the compressive viewpoint suggests a competitive parallel algorithm for an adjoint-state inversion method in reflection seismology.Comment: 45 pages, 4 figure

Study of resonant reflection in helicoidal photonic band gap structures

La présente thèse de doctorat rapporte une étude expérimentale sur la réflexion résonante de la lumière dans des structures hélicoïdales à bande photonique interdite. Plusieurs aspects optiques et électro-optiques des cristaux liquides cholestériques sont abordés en concentrant l’attention sur deux effets principaux: l’influence des conditions aux limites (mécaniques et optiques) sur les propriétés optiques des couches de cristaux liquides cholestériques et le contrôle de la bande interdite de ces dernières. On présente un élément à double-rétroaction optique basé sur une cavité de Fabry-Pérot remplie de cristal liquide cholestérique. Les propriétés spectrales et de polarisation de cet élément sont caractérisées expérimentalement et par des simulations théoriques. Un changement mineur dans la structure en haut (cavité de Fabry-Pérot) nous a permis d’obtenir une transmission non-réciproque de la lumière sans application d’un champ externe à l’élément en question. Nous avons observé une transmission non-réciproque de la lumière par un système qui ressemble beaucoup aux structures naturelles observées sur certaines carapaces d’insectes (par exemple, sur les élytres de certains coléoptères): une simple couche de matière transparente linéaire dans son état fondamental. L’effet est défini par deux facteurs principaux: la chiralité et la périodicité de la matière ainsi que les conditions asymétriques aux surfaces limites. Concernant la partie sur le contrôle de la bande interdite, nous présentons la création et l’utilisation du mélange de cristal liquide cholestérique à deux fréquences pour le ‘déroulement’ et la reconstruction dynamique de la structure hélicoïdale. Le processus de reconstruction est accéléré d’un ordre de grandeur par l’application de champs électriques modérés. L’étape suivante du contrôle de la bande interdite est l’accord en longueur d’onde de la bande interdite. Un effet électromécanique est utilisé pour générer et étudier l’auto-adaptation du pas d’hélice de la couche de cristal liquide cholestérique. L’anisotropie négative diélectrique a permis d’assurer la stabilisation de la structure hélicoïdale de la couche pendant l’application du champ électrique qui a aussi changé l’épaisseur de la couche de cristal liquide en pliant un des substrats minces de la cellule. Cette déformation de la couche a généré un d’accord (et des sauts) des longueurs d’onde de la bande interdite. Les études spectrales et morphologiques pendant les changements de la bande interdite sont présentées et discutées.The present PhD thesis reports experimental study of resonant reflection in helicodal photonic band gap structures. Several optical and electro-optical properties of cholesteric liquid crystals are investigated where attention was concentrated on two principal phenomena: the influence of mechanical and optical boundary conditions on optical properties of cholesteric liquid crystal layers and control of photonic band gap of cholesteric liquid crystals. The creation of a double-feedback optical element based on a Fabry-Perot cavity filled with a planar aligned cholesteric liquid crystal mixture is presented. The polarization and spectral properties of this element are characterized experimentally and simulated theoretically. Experimental results are obtained for the transmittance dependence upon the orientation of the linear polarization plane and the polarization state of incident probe beam. A slight change in above mentioned structure (Fabry-Perot cavity) let us obtain a non-reciprocal transmittance of light without applying any external field. We observed an optical non reciprocity in a material system that is very close to natural structures, such as insect skin: a single layer of linear transparent material in its ground state. The process is shown to be defined by two key parameters: the chiral and periodic nature of the material and its asymmetric boundary conditions. In the part of band gap control, we present the creation and the use of dual frequency cholesteric liquid crystal mixtures for the dynamic electrical unwinding and forced (accelerated) restoring of their molecular helix. The restoring process is accelerated almost by an order of magnitude for quite moderate voltages used. The next step of band gap control is the tuning of band gap (wavelength). Strong electromechanical effect was used to generate and study self-adaptation and pitch jumps in a layer of cholesteric liquid crystal. The negative dielectric anisotropy of the material allowed its stabilization by the electric field and important thickness changes, achieved thanks to the use of a very thin substrate, allowed the observation of multiple dynamic jumps at fixed deformation conditions. Spectral and morphological studies of the material during those jumps were performed and are presented

Combined Hyperthermia and Radiotherapy for the Treatment of Cancer

Radiotherapy is used to treat approximately 50% of all cancer patients, with varying success. Radiation therapy has become an integral part of modern treatment strategies for many types of cancer in recent decades, but is associated with a risk of long-term adverse effects. Of these side effects, cardiac complications are particularly relevant since they not only adversely affect quality of life but can also be potentially life-threatening. The dose of ionizing radiation that can be given to the tumor is determined by the sensitivity of the surrounding normal tissues. Strategies to improve radiotherapy therefore aim to increase the effect on the tumor or to decrease the effects on normal tissues, which must be achieved without sensitizing the normal tissues in the first approach and without protecting the tumor in the second approach. Hyperthermia is a potent sensitizer of cell killing by ionizing radiation (IR), which can be attributed to the fact that heat is a pleiotropic damaging agent, affecting multiple cell components to varying degrees by altering protein structures, thus influencing the DNA damage response. Hyperthermia induces heat shock protein 70 (Hsp70; HSPA1A) synthesis and enhances telomerase activity. HSPA1A expression is associated with radioresistance. Inactivation of HSPA1A and telomerase increases residual DNA DSBs post IR exposure, which correlates with increased cell killing, supporting the role of HSPA1A and telomerase in IR-induced DNA damage repair. Thus, hyperthermia influences several molecular parameters involved in sensitizing tumor cells to radiation and can enhance the potential of targeted radiotherapy. Therapy-inducible vectors are useful for conditional expression of therapeutic genes in gene therapy, which is based on the control of gene expression by conventional treatment modalities. The understanding of the molecular response of cells and tissues to ionizing radiation has lead to a new appreciation of the exploitable genetic alterations in tumors and the development of treatments combining pharmacological interventions with ionizing radiation that more specifically target either tumor or normal tissue, leading to improvements in efficacy

Development of the additively manufactured stainless steel 316L and AlSi10Mg alloys by in situ alloying and post-process treatment

L'abstract è presente nell'allegato / the abstract is in the attachmen

Gingival tissue attachment and blood responses to nanoporous bioactive coatings on zirconia

Zirconia implant abutments have gained popularity over the past few years as a substitute for the traditionally used titanium alloy abutments. However, research on the soft-tissue responses of zirconia and improving the zirconia surface properties towards immediate soft-tissue integration are limited. This series of in vitro studies aimed at evaluating tissue and cellular responses of commercially available zirconia versus zirconia provided with sol-gel derived TiO2 coating. Final purpose of the research project was to optimize zirconia surface properties for fabrication of implant abutments, which enhances gingival tissue attachment. Coatings were prepared from tetraisopropyl orthotitanate solution by dip-coating method. The effect of coatings and the coating process on the mechanical properties of zirconia was evaluated by biaxialflexural strength test. Human gingival epithelial and fibroblast cell responses – adhesion kinetics, adhesion strength, and proliferation– was studied in cell culture environment. Blood response, including blood clotting ability, protein adsorption and platelet adhesion and morphology was evaluated. A novel tissue culture method, developed earlier by the research group, was used to evaluate porcine gingivaltissue attachment on the coated and non-coated zirconia implants. Adhesion was evaluated using routine microscopy coupled with immunohistochemical staining. Furthermore, the strength of bond between tissue and implants was analyzed utilizing dynamic mechanical analysis. The biaxial flexural strength of zirconia specimens was unaffected by the coating process. Significant differences were observed in blood coagulation between the coated and non-coated zirconia surfaces. UV treatment of the TiO2 coated specimens enhanced blood coagulation. Blood platelets also appeared at a higher activation state on coated specimens although no differences in protein adsorption were observed. TiO2 coated zirconia were significantly more hydrophilic with higher total surface free energy than non-coated ones. Cell proliferation and adhesion was significantly higher on coated specimens. Microscopic observation of gingival tissue attachment on coated implants identified laminin-g-2 at the attachment of epithelium to implant indicating direct attachment. This observation was absent in noncoated zirconia controls. Furthermore, gingival tissue attachment to coated zirconia implants demonstrated higher dynamic modulus of elasticity and higher creep modulus. Sol-gel derived TiO2 coatings on zirconia enhance trombogenicity and facilitate direct gingival tissue attachment on zirconia surface. These findings indicate that TiO2 coating on zirconia abutments has good potential to improve implant treatment results

PREPARATION AND CHARACTERIZATION OF MESOPOROUS SBA-15 SILICA SUPPORTED GOLD CATALYSTS FOR SELECTIVE OXIDATIONS

The aim of this research is to design, prepare, and characterize gold catalysts that combine the active surface of gold nanoparticles with the confinement effects afforded by the highly ordered mesoporous SBA-15 silica. These gold catalysts show promising catalytic efficiency in facilitating the selective oxidation of benzyl alcohol, which produces benzaldehyde, a valuable product for various industrial applications. However, traditional methods for preparing these catalysts require modification of the SBA-15 surface with ligands to stabilize the gold nanoparticles inside the SBA-15 pores. High-temperature calcination (≥ 500 ℃) is then needed to remove the anchored ligands for catalyst activation. This calcination causes the deterioration of the gold nanoparticles’ size and morphology, reducing catalytic efficiency.We demonstrate a novel reversible ionic liquid (RevIL) technique for preparing gold catalysts, eliminating the need for chemical modification of the silica surface. RevILs can be switched between their molecular and ionic forms by reacting with CO2. Upon removal of CO2 via sparging with inert gas or gentle heating, RevILs revert to their molecular form and leave the gold surface. We use the RevIL technique to prepare and deposit the size-controlled gold nanoparticles inside the pores of SBA-15 silica. The gold nanoparticles’ location inside the pores is confirmed by a microscopic technique and the nanoparticles’ improved thermal stability compared to those deposited on the surface of nonporous SiO2. Owing to the bare gold surface, the porous gold catalysts prepared with the RevIL technique are highly active in the selective oxidation of benzyl alcohol without calcination. We confirm the bare gold surface by the disappearance of the RevILs’ chemical signals via Fourier-transform infrared spectroscopy analysis. The porous SBA-15 supported gold catalysts show improved catalytic activity over the nonporous SiO2 supported gold catalysts’, implying that the SBA-15 pores impact catalysis.By controlling the geometry of the gold catalysts, we alter the pore environment near the gold surface to tune the reactive molecules’ mass transport, thus influencing catalytic activity. We hypothesize that the SBA-15 pores have no impact on the translational diffusion of benzyl alcohol molecules but restrict the random rotational diffusion. To test this hypothesis, we use the NMR-based DOSY and T1 relaxation techniques to measure the translational and rotational diffusion coefficients of benzyl alcohol in three distinctive environments: bulk, pore, and non-pore. These diffusion coefficients are measured at varying temperatures and are then correlated to Arrhenius behavior to determine the activation energy associated with temperature-dependent diffusion processes. A high activation energy indicates difficult diffusion processes. We demonstrate that the trend of activation energy of translational diffusion is bulk (difficult)> non-pore > pore (easy), while for rotational diffusion, the trend is pore (difficult) > bulk > non-pore (easy). These findings indicate that the SBA-15 pores do not induce translational mass-transport limitation but hinder the free rotation of benzyl alcohol molecules near the gold surface. Given that rotational diffusion governs the adsorption behavior of reactive species, we further investigate the impact of SBA-15 pores on the adsorption process.Consequently, we hypothesize that the SBA-15 pores fundamentally alter the adsorption behavior of benzyl alcohol. To verify this hypothesis, we use three probe molecules—hexane, cyclohexanol, and toluene—to examine the effects of dilution, hydroxyl group adsorption, and phenyl ring adsorption, respectively, on the catalytic activity of the porous and nonporous gold catalysts. The results reveal that while dilution has no impact on catalytic activity, the presence of cyclohexanol’s hydroxyl group and toluene’s phenyl ring greatly reduces the porous and nonporous gold catalysts’ catalytic activities. To explain these effects, we construct a kinetic model to elucidate the catalytic dynamics and quantify the kinetic parameters, providing a quantitative assessment of how the porous catalyst structure influences the adsorption process compared to the nonporous catalyst structure. We demonstrate that the SBA-15 pores significantly enhance the adsorption rate of reactive species, as shown by a 200% higher adsorption constant of benzyl alcohol in the porous gold catalysts than the nonporous. This enhancement improves the catalytic activity of the porous SBA-15 supported gold catalysts. In addition, the SBA-15 pores promote the adsorption of hydroxyl groups while hindering the adsorption of phenyl rings, as evidenced by a 107% higher adsorption constant of cyclohexanol’s hydroxyl group and a 110% lower adsorption constant of toluene’s phenyl ring in the nonporous gold catalysts than the porous. These findings suggest unique adsorption behavior of benzyl alcohol within the SBA-15 pores, characterized by two processes: 1) the SBA-15 pores hinder the adsorption of the phenyl ring in benzyl alcohol through restricted rotational diffusion, reducing the likelihood of active site blockage; and 2) the SBA-15 pores facilitate the alignment of the hydroxyl group in benzyl alcohol with the gold surface, thus facilitating chemical reactions and, consequently, catalytic activity.Based on the findings in this dissertation, we conclude that, in the absence of translational mass transport limitations, the SBA-15 pores can modify the adsorption behavior of benzyl alcohol molecules through tuned rotational mass transport, enhancing the catalytic performance of the porous SBA-15 supported gold catalysts