Development and Applications Of Photoflash-Pvdf Technique in Thermal Diffusitivity Measurement at Low Temperatures

The photoflash technique is developed and used for measuring thermal diffusivity of various types of material, at temperature range from -77K to ambient temperature. It uses a cheap and simple camera flash and polyvinlidene difluoride (PVDF) film as signal generating source and detector, respectively. The theoretical signal was derived based on the square pulse approximation of the camera flash that replaced Dirac-6 function approximation employed in other studies. Comparative studies on these two different approximations have been performed on SiCIB4C composites. Although the camera flash temporal shape is closer to square pulse, Dirac-6 function approximation is still valid for the limited case of PVDF signal that is significantly longer than camera flash pulse duration. The square wave approximation model was further used in determining the thermal diffusivity of superconductors, semiconductors, magnetoresistances, carbon nanotubes, ceramics, composites, polymers and porous samples. The thermal diffusivity for SiC/B4C composites and Sic doped with A1 decreased with increasing temperature. This suggests that thermal diffusivity is basically influenced by phonon interaction within lattice that determines the phonon mean free path. In case of superconducting materials, thermal diffusivity measurements were carried for BSCCO, doped with Samarium (Sm) at Bi, Sr and Cu sites and sintered for 24,48 and 100hrs respectively. The results were explained in terms of electronphonon and phonon-lattice interactions in association with the sample grain size. The magneto-resistive of LCMO doped with Er at La site was also studied in this study. Thermal diffusivity measurements revealed that the transition from metallic to insulator and from insulator to semiconductor behavior in the materials, were closely matched to the results obtained from electrical resistivity measurement of other researchers. The thermal diffusivity of carbon nanotubes (CNTs) decreased when the temperature was increased from low to room temperature. Besides, there were also double slope phenomena in the way the thermal diffusivity changed with composition of CNT in the range of temperature covered in the measurement. In the case of polymers of Emeraldine Base (EB) and Emeraldine Salt (ES), the thermal diffusivity changed with temperature as in other insulating materials. Finally, the effect of porosity on thermal diffusivity was studied using Nickel Copper Zinc Ferrite samples. The thermal diffusivity decreased with increasing porosity of the sample. The results also showed that porosity has a greater effect on thermal conductivity of the material than its thermal capacity

RSU-Based Online Intrusion Detection and Mitigation for VANET

Secure vehicular communication is a critical factor for secure traffic management. Effective security in intelligent transportation systems (ITS) requires effective and timely intrusion detection systems (IDS). In this paper, we consider false data injection attacks and distributed denial-of-service (DDoS) attacks, especially the stealthy DDoS attacks, targeting the integrity and availability, respectively, in vehicular ad-hoc networks (VANET). Novel statistical intrusion detection and mitigation techniques based on centralized communications through roadside units (RSU) are proposed for the considered attacks. The performance of the proposed methods are evaluated using a traffic simulator and a real traffic dataset. Comparisons with the state-of-the-art solutions clearly demonstrate the superior performance of the proposed methods in terms of quick and accurate detection and localization of cyberattacks

Satellite remote sensing in earthquake prediction. A review

Sudden, violent movement of the earth's surface resulted of the release of energy into the atmosphere can destroy cities and claim lives. With the recent advances in space-borne data collecting methods which have made it possible monitoring the earth surface with different sensors, scientists are now able to better study the causes and signs of Earthquakes. Current researches are moving in the direction of pre-earthquake deformation detection. In order to make successful prediction all the related data must be collected from different space-borne sensors and ground-based stations. Past earthquakes should also be investigated for any phenomena that can occur before an earthquake. Surface deformation data are provided by GPS and SAR imaging, land surface temperature changes by ASTER, Landsat TM and ETM, different types of cloud studies using MODIS and Seawifs data, electromagnetic and ionosphere anomalies by ground passive stations and radon gas emissions in the faults areas by solid on the ground detectors. In this paper we tried to gather complete and helpful information of earthquake precursors which have been studied until now

An investigation about newspaper buying and effects of sales promotions on newspaper choice

Ankara : The Department of Management and The Graduate School of Business Administration of Bilkent University, 1992.Thesis (Master's) -- Bilkent University, 1992.Includes bibliographical references leaves 48-50.Haydari, NazanM.S

Latent heat flux and air temperature anomalies along an active fault zone associated with recent Iran earthquakes

Pre-earthquake physical and chemical interactions in the earth’s ground may cause anomalies in latent heat flux, air and surface temperature. Earthquakes occur when the energy accumulated in rocks releases. Sometimes, the movements of the ground cause ruptures in the earth’s surface and sometimes the two sides of an existing fault shift towards each other. In a structurally complex and inhomogeneous collision region such as the Iranian Plateau, seismicity is not the result of activity of a single fault but is due to energy discharge in fault zones hundreds of kilometers wide. Changes in latent heat flux and temperature, on and above the earth’s surface can be detected with thermal infrared (TIR) sensors such as NOAA-AVHRR, Terra/Aqua-MODIS, etc. Spatio-temporal distributions of surface latent heat flux (SLHF) and air temperature before and after two recent earthquakes in Iran have been studied. Anomalous patterns of higher SLHF formed a few days before the earthquakes of 20 Dec 2010 (6M) and 27 Jan 2011(6.5M) occurred in Kerman province and disappeared after the main events. Data analyses revealed at least 2–4 °C rises in air temperature along the nearby fault zone, as well. These changes were also in accordance with the abnormal relative humidity over the region. Significant rises in SLHF and air temperature may lead us to understand the energy exchange mechanism during the earthquakes. These anomalies prior to impending earthquakes can be attributed to the thermodynamic, degassing and ionization processes which are believed to be activated by the accumulated stress in the ground, insensible movements of the tectonic blocks, and micro-fracturing in the rocks especially along area’s active faults. Continuous monitoring of these potential precursors helps in differentiating earthquake related variations from seasonal changes and atmospheric effects

Towards Efficient and Secure Intelligent Transportation Services: AI-driven Traffic Light Controller and Privacy-Preserving Mobility Data Generation

The widespread adoption of artificial intelligence (AI) and Intelligent Transportation Systems (ITS) technologies has led to the increasing application of AI-based ITS controllers, with the Traffic Signal Controller (TSC) being a prominent example. Reinforcement learning (RL) models have shown promising results for adaptively adjusting traffic light schedules in urban environments through RL-based TSCs (RL-TSCs). The real-world deployment of RL-TSCs involves three key aspects: performance, security, and data privacy. In terms of performance, RL-TSC models need to be designed with consideration for various metrics, such as fair traffic scheduling and air quality impact. To address this, our approach takes into account a multi-objective constrained learning formulation to optimize performance. However, the use of RL-TSCs for automation, by leveraging external inputs, introduces security concerns that require active research to mitigate. We address these security challenges by introducing an innovative defense mechanism. Additionally, the training of RL-TSCs relies on real-world mobility datasets, necessitating the protection of data privacy at different levels of granularity. To minimize the constraints associated with limited real data availability or privacy concerns, we introduce two distinct directions: synthetic trajectory data generation using recent generative AI methods, and location privacy models for raw mobility datasets based on differential privacy, which safeguard individual trajectories and aggregated mobility datasets.This research provides a valuable tool for evaluating the practical deployment of RL-TSCs, particularly in real-world settings where the last mile of implementation and security is paramount. By addressing the key challenges of performance, security, and data privacy, this work aims to facilitate the successful real-world deployment of AI-powered ITS controllers

Regenerative potential of corneal endothelium from patients with fuchs endothelial corneal dystrophy

La dystrophie cornéenne endothéliale de Fuchs (FECD, pour l’abréviation du terme anglais « Fuchs endothelial corneal dystrophy ») est une maladie de l'endothélium cornéen. Sa pathogenèse est mal connue. Aucun traitement médical n’est efficace. Le seul traitement existant est chirurgical et consiste dans le remplacement de l’endothélium pathologique par un endothélium sain provenant de cornées de la Banque des yeux. Le traitement chirurgical, en revanche, comporte 10% de rejet immunologique. Des modèles expérimentaux sont donc nécessaires afin de mieux comprendre cette maladie ainsi que pour le développement de traitements alternatifs. Le but général de cette thèse est de développer un modèle expérimental de la FECD en utilisant le génie tissulaire. Ceci a été réalisé en trois étapes. 1) Tout d'abord, l'endothélium cornéen a été reconstruit par génie tissulaire en utilisant des cellules endothéliales en culture, provenant de patients atteints de FECD. Ce modèle a ensuite été caractérisé in vitro. Brièvement, les cellules endothéliales cornéennes FECD ont été isolées à partir de membranes de Descemet prélevées lors de greffes de cornée. Les cellules au deuxième ou troisième passages ont ensuite été ensemencées sur une cornée humaine préalablement décellularisée. Suivant 2 semaines de culture, les endothélia cornéens reconstruits FECD (n = 6) ont été évalués à l'aide d'histologie, de microscopie électronique à transmission et d’immunomarquages de différentes protéines. Les endothélia cornéens reconstruits FECD ont formé une monocouche de cellules polygonales bien adhérées à la membrane de Descemet. Les immunomarquages ont démontré la présence des protéines importantes pour la fonctionnalité de l’endothélium cornéen telles que Na+-K+/ATPase α1 et Na+/HCO3-, ainsi qu’une expression faible et uniforme de la protéine clusterine. 2) Deux techniques chirurgicales (DSAEK ; pour « Descemet stripping automated endothelial keratoplasty » et la kératoplastie pénétrante) ont été comparées pour la transplantation cornéenne dans le modèle animal félin. Les paramètres comparés incluaient les défis chirurgicaux et les résultats cliniques. La technique « DSAEK » a été difficile à effectuer dans le modèle félin. Une formation rapide de fibrine a été observée dans tous les cas DSAEK (n = 5). 3) Finalement, la fonctionnalité in vivo des endothélia cornéens reconstruits FECD a été évaluée (n = 7). Les évaluations in vivo comprenaient la transparence, la pachymétrie et la tomographie par cohérence optique. Les évaluations post-mortem incluaient la morphométrie des cellules endothéliales, la microscopie électronique à transmission et des immunomarquage de protéines liées à la fonctionnalité. Après la transplantation, la pachymétrie a progressivement diminué et la transparence a progressivement augmenté. Sept jours après la transplantation, 6 des 7 greffes étaient claires. La microscopie électronique à transmission a montré la présence de matériel fibrillaire sous-endothélial dans toutes les greffes d’endothelia reconstruits FECD. Les endothélia reconstruits exprimaient aussi des protéines Na+-K+/ATPase et Na+/HCO3-. En résumé, cette thèse démontre que les cellules endothéliales de la cornée à un stade avancé FECD peuvent être utilisées pour reconstruire un endothélium cornéen par génie tissulaire. La kératoplastie pénétrante a été démontrée comme étant la procédure la plus appropriée pour transplanter ces tissus reconstruits dans l’œil du modèle animal félin. La restauration de l'épaisseur cornéenne et de la transparence démontrent que les greffons reconstruits FECD sont fonctionnels in vivo. Ces nouveaux modèles FECD démontrent une réhabilitation des cellules FECD, permettant d’utiliser le génie tissulaire pour reconstruire des endothelia fonctionnels à partir de cellules dystrophiques. Les applications potentielles sont nombreuses, y compris des études physiopathologiques et pharmacologiques.Fuchs endothelial corneal dystrophy (FECD) is a primary disease of the corneal endothelium. Its pathogenesis is poorly understood. No medical treatment is effective. Surgical treatment (the only available treatment) carries 10% of immunogenic rejection. Experimental models are needed in order to better understand the disease and to investigate potential autologous treatments (to prevent immunogenic rejection). The overall goal of this thesis is to develop an experimental model for FECD using tissue engineering. This was achieved in three steps. 1) An in vitro tissue-engineered FECD model was created and characterized. Briefly, Descemet’s membranes from patients with late-stage FECD undergoing Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) were used to isolate and culture FECD endothelial cells. Second or third-passaged FECD endothelial cells were seeded on a previously decellularized human cornea. After 2 weeks in culture, TE-FECD corneas (n=6) were assessed using histology, transmission electron microscopy (TEM) and immunofluorescence labeling of various proteins. TE-FECD endothelium yielded a monolayer of polygonal cells well adhered to Descemet’s membrane. The TE-FECD corneal endothelium expressed the function-related proteins Na+-K+/ATPase α1 and Na+/HCO3-. Clusterin expression was faint and uniform. 2) In order to determine the best surgical procedure to transplant the TE-FECD corneas in the feline model, a DSAEK procedure was evaluated and compared to penetrating keratoplasty technique. DSAEK assessments included surgical challenges and clinical outcomes. DSAEK technique was challenging to perform in the feline model. Rapid fibrin formation was observed in all DSAEK cases (n=5). 3) The in vivo functionality of the TE-FECD corneas was assessed. TE-FECD corneas were grafted in the feline model (n=7) using penetrating keratoplasty procedure and observed for seven days. In vivo assessments included transparency, pachymetry, optical coherence tomography, endothelial cell morphometry, TEM and immunostaining of function-related proteins. After transplantation, pachymetry gradually decreased and transparency gradually increased. Seven days after transplantation, 6 out of 7 grafts were clear. Post-mortem TEM showed subendothelial loose fibrillar material deposition in all TE-FECD grafts. The TE grafted endothelium expressed Na+-K+/ATPase and Na+/HCO3-. This thesis demonstrates that endothelial cells from late-stage FECD corneas can be used to engineer a corneal endothelium. Compared to DSEAK, penetrating keratoplasty is a more appropriate procedure for corneal transplantation in the feline model, since the DSAEK procedure in the feline model presently yields inconsistent clinical results. Restoration of corneal thickness and transparency demonstrates that the TE-FECD grafts are functional in vivo. This novel FECD living model suggests a potential role of tissue engineering for FECD cell rehabilitation. Potential applications are numerous, including pathophysiological and pharmacological studies

Investigation of lipid profiles and lipid peroxidation in patients with type 2 diabetes.

The aim of this study was to investigat the lipid peroxidation of plasma as a marker of oxidant-induced protein damage the effects of oxygen radicals on glycated-hemoglobin and to find out the relationship between the increase level of Malondialdehyde (MDA) on HbA1C, lipid profiles and FBS (Fasting Blood Sugar) in patients with type 2 diabetes. This randomized study included 200 individuals, 100 cases had history of diabetic for at least 3 years (file in Isfehan hospital, Diabetic Center of Medical Sciences University) and 100 cases as the control group without history of diabetes. In both groups, level of MDA, FBS, lipid profiles and HbA1C were determined in fasting blood samples. Results showed that MDA level in diabetic patients was significantly (p<0.005) higher (0.9222 ± 0.3 μmol/L) than those in the control group (0.7428 ± 0.04μmol/L). The same was also true (p<0.05) for the level of HbA1C (9.387 ± 2.4 mg/dl in diabetic patients and 7.356 ± 1.0 mg/dl in the control group) and the FBS (163.31 ± 56mg/dl in patient group and 85.740 ± 10.1 in the control group). Furthermore, the concentration of, LDL significantly was higher (p<0.05) and the HDL level were significantly lower (p<0.05) in case group as compared to control group. The increased plasma lipid peroxidation and decreased plasma HDL that we observed in patients with type 2 diabetes mellitus indicated that these may predispose to the development of cardiovascular complications

Synthesis and Biological Activity Evaluations of Novel Heterobimetallic Platinum(II)–Gold(I) Complexes as Bio-imaging Agents.

Introduction: Platinum-based drugs have become a mainstay of cancer therapy, approximately half of all patients undergoing chemotherapeutic treatment receive a platinum drug. Despite the pervasiveness of platinum drugs in cancer treatment regimens, a number of attendant disadvantages such as resistance to some cancer types and side effects exist. Gold complexes are also emerging as a new class of metal complexes with outstanding cytotoxic properties and are presently being evaluated as potential antitumor agents. Methods and Results: Here, some novel heterobimetallic platinum(II)–gold(I) complexes were synthesized and their cytotoxic activities against different human cancer cell lines such as A549 (human lung cancer), SKOV3 (human ovarian cancer) and MDA-MB-231 (human breast cancer) were evaluated. Electrophoresis mobility shift assay and molecular modeling investigations have been performed to determine the specific binding mode or the binding orientation of these compounds to DNA. Molecular docking studies of them on DNA were performed by means of AutoDock 4.2. Fluorescence emission properties of them were assessed using fluorescent microscopy imaging. In comparison to cis-platin, these compounds displayed significantly higher in vitro cytotoxicity on the studied cell lines. They enter SKOV3 cells rapidly, retaining their phosphorescence and localise simultaneously in cytoplasm, especially in perinuclear regions. So they are suitable candidates for time resolved emission imaging microscopy (TREM). Electrophoresis mobility shift assay showed a little shift and little interaction with plasmid DNA, though this shift is not as much as cis-platin. They may exert their cytotoxic effect through a different mechanism. Conclusions: According to the results, careful drug design would result in producing potential antitumor agents with high efficacy. These Pt(II)-Au(I) complexes can be used in biological labelling and cellular imaging studies, due to desirable absorption and emission of them in solution under ambient conditions. Hence, they had a potential value for drug development as anticancer agents