Two journeys of the spirit: comparing Plato\u27s Republic and Ibn Tufayl\u27s Hayy Ibn Yaqzan

Both Plato’s Republic and Ibn Tufayl’s Hayy Ibn Yaqzan explain to the reader how a spiritual journey can bring about an understanding of the Divine. However, both works also show us that the spiritual journey depends on an inquiry into the nature of the human soul as it engages in the process of learning. In the first chapter of the thesis, Plato’s Republic is explored, particularly in terms of the Allegory of the Cave, which suggests how the notion the Divine goes beyond everyday life experience. In the second chapter, Hayy Ibn Yaqzan is presented as a spiritual narrative that helps us view the importance of observation, leading to the knowledge of the natural world, the beginnings of self-discovery and meditations on the Divine. My conclusion argues that these two works help the reader understand the reality of the Divine through different conceptions of the soul, which imply different but comparable views of education

Microwave sources based on high quality factor resonators; modeling, optimization and metrology

La technologie photonique-RF offre une alternative intéressante à l'approche purement électronique dans différents systèmes micro-ondes pour des applications militaires, spatiales et civiles. Un composant original, l'oscillateur optoélectronique (OEO), permet la génération de signaux RF stables et à haute pureté spectrale. Il est basé sur une liaison photonique micro-onde utilisée comme boucle de rétroaction et comportant soit une fibre longue, soit un résonateur à fort coefficient de qualité. Différentes études ont été menées au cours de cette thèse afin d'optimiser et d'améliorer la performance en termes de stabilité et de bruit de phase pour le cas de l'OEO à résonateur. La caractérisation fine et la modélisation des résonateurs est une première étape de la conception globale du système. La métrologie du résonateur optique est réalisée par une technique originale, dite de spectroscopie RF. Les résultats expérimentaux ont révélé que cette technique permet d'une part d'identifier le régime de couplage du résonateur et d'autre part de déterminer avec une grande précision tous les paramètres d'un dispositif résonant, comme les facteurs de qualité interne et externe ou les facteurs de couplage. Une deuxième étude a été orientée vers l'implémentation d'un modèle non-linéaire fiable du dispositif. Dans un tel modèle, la photodiode rapide nécessitait une description plus précise, dans le but de contrôler la conversion du bruit d'amplitude optique en bruit de phase de l'OEO. Un nouveau modèle non-linéaire d'une photodiode hyperfréquence a été développé sous un logiciel commercial: Agilent ADS. Ce nouveau modèle rend effectivement compte de cette conversion de bruit. Une puissance optique optimale à l'entrée de la photodiode a été déterminée, pour laquelle la contribution de RIN du laser au bruit de phase RF pourrait être négligeable. La performance de l'OEO est affectée par diverses perturbations entrainant un décalage en fréquence entre la fréquence du laser et la fréquence de résonance du résonateur. Il est donc important d'utiliser un système de stabilisation pour contrôler cette différence de fréquence. Des séries d'expériences et de tests ont été menées pour étudier la possibilité, d'une part, de remplacer l'électronique commerciale utilisée auparavant pour le système de verrouillage en fréquence (boucle de Pound-Drever-Hall) par une électronique faible bruit et, d'autre part, d'utiliser un laser à semi-conducteur. Un bilan de ces approches est présenté.RF photonics technology offers an attractive alternative to classical electronic approaches in several microwave systems for military, space and civil applications. One specific original architecture dubbed as optoelectronic oscillator (OEO) allows the generation of spectrally pure microwave reference frequencies, when the microwave photonic link is used as a feedback loop. Various studies have been conducted during this thesis on the OEO, especially the one that is based on fiber ring resonators, in order to optimize and improve its phase noise performance and its long-term stability. Precise characterization and modeling of the optical resonator are the first step towards overall system design. The resonator metrology is performed using an original approach, known as RF spectral characterization. The experimental results have demonstrated that this technique is helpful for the identification of the resonator's coupling regime and the accurate determination of the main resonator parameters such as the intrinsic and extrinsic quality factors or the coupling coefficients. A second study was directed toward implementing a reliable nonlinear model of the system. In such a model, the fast photodiode require an accurate description, in order to reduce the conversion of the optical amplitude noise into RF noise. A new nonlinear equivalent circuit model of a fast photodiode has been implemented in a microwave circuit simulator: Agilent ADS. This new model is able to describe the conversion of the laser relative intensity noise (RIN) into microwave phase noise at the photodiode output. An optimal optical power at the photodiode's input has been identified, at which the contribution of the laser RIN in RF phase noise is negligible. When it comes to practical applications, the desired performance of an OEO is threatened by various disturbances that may result in a frequency shift of both the laser frequency and the transmission peak of the resonator, which causes a malfunction of the OEO. Therefore it is desirable to use a stabilization system to control the difference between the laser frequency and the resonator frequency. A series of tests and experiments have been carried out to investigate the possibility, on one hand, to replace the commercial servo controller that was used up until now in the Pound-Drever-Hall loop, with a low noise homemade one and, on the other hand, to use a semiconductor laser to reduce the system size. A detailed review of these approaches is presented

Infection Control Measures in Private Dental Clinics in Lebanon

Purpose. Evaluate infection control knowledge, attitude, and practice in Lebanese private dental clinics. Materials and Methods. A survey including 46 questions related to routine safety procedures was sent to 1150 Lebanese dentists between July 1st and 2nd, 2015. The study sample was selected from the database of registered dentists based on a proportional random sampling ensuring equitable representation of the 5 geographic regions of Lebanon. A subset of 29 questions was used to generate an overall score of compliance (excellent, good, fair, and poor). Comparisons according to gender, type, region, and years of practice were performed. Results. 417 dentists returned the completed questionnaires. 96% expressed concern about infection transmission, 90.6% were vaccinated against Hepatitis B, and 61.8% asked routinely about patients medical history. Only 43% used protective eyewear. Although most dentists (65%) used autoclaves, dry heat was still used. Significant correlations were found between gender and use of personal protective equipment. Less compliance was shown by clinicians with fewer years of experience. In the overall compliance questionnaire, the mean percentage of correct answers was roughly 54% with <5% of the practitioners scoring “excellent.” Conclusions. The study found inadequacy of compliance in private Lebanese dental clinics necessitating improved educational training and sustained monitoring by regulatory bodies

Prevalence of Body Dysmorphic Disorder (BDD) among the Lebanese University students: Associated risk factors and repercussion on mental health

Background: Body Dysmorphic Disorder (BDD) is a psychological illness characterized by persistent and intrusive preoccupation with an imagined or slight defect in appearance. For individuals with BDD, these perceived defects are significant and prominent, leading to emotional distress, depression, anxiety, and impairment in daily functioning. Despite its impact, no prior studies have explored the prevalence of BDD among Lebanese university students. Objectives: This study aimed to determine the prevalence of BDD and investigate its association with mental health status (depression and anxiety), religiosity, eating disorder risk, and self-esteem among Lebanese University students.&nbsp; Methodology: A cross-sectional study was conducted in March 2020, involving students from the Lebanese University. Data were collected using the dysmorphic concern questionnaire (DCQ), Rosenberg self-esteem scale (RSE), religiosity scale, patient health questionnaire (PHQ-9), generalized anxiety disorder assessment (GAD-7), Eating Attitude test-26 scale (EAT-26). Results: A total of 6448 participants were enrolled in our study. The overall prevalence of BDD among university students was (6.4%).Our results showed that Lebanese students with BDD were more likely to have anxiety ORadj 1.3 (95% CI:1.2-1.7) p-value 0.001, depression ORadj 1.2 (95% C:1.15-1.5) p-value 0.007, and eating disorder (Bulimia &amp; Food preoccupation ORadj 1.06 (95% CI:1.03-1.2) P-value 0.0, and oral control ORadj 1.09 (95% CI:1.05-1.1)&nbsp; P-value &lt; 0.001) compared to those with no BDD. We also found that students with BDD had Lower Self-esteem ORadj 0.88 (95%CI: 0.78-0.9) P-value &lt;0.001), and less likely to be religious ORadj 0.88 (95%CI: 0.82-0.9) P-value 0.02) compared to those with no BDD. Conclusion: This pioneering study in Lebanon sheds light on the prevalence of BDD among Lebanese university students and its associated factors. BDD was found to be significantly linked to elevated levels of depression, anxiety, and eating disorders, along with lower levels of self-esteem and religiosity. These findings underscore the importance of early detection of BDD during adolescence and young adulthood, necessitating timely psychological intervention to prevent chronicity and complications. Moreover, promoting widespread awareness through various social media and public platforms is essential to address this psychological issue effectively

Tumorigenic proteins upregulated in the MYCN-amplified IMR-32 human neuroblastoma cells promote proliferation and migration.

Childhood neuroblastoma is one of the most common types of extra-cranial cancer affecting children with a clinical spectrum ranging from spontaneous regression to malignant and fatal progression. In order to improve the clinical outcomes of children with high-risk neuroblastoma, it is crucial to understand the tumorigenic mechanisms that govern its malignant behaviors. MYCN proto-oncogene, bHLH transcription factor (MYCN) amplification has been implicated in the malignant, treatment-evasive nature of aggressive, high-risk neuroblastoma. In this study, we used a SILAC approach to compare the proteomic signatures of MYCN-amplified IMR-32 and non-MYCN-amplified SK-N-SH human neuroblastoma cells. Tumorigenic proteins, including fatty-acid binding protein 5 (FABP5), L1-cell adhesion molecule (L1-CAM), baculoviral IAP repeat containing 5 [BIRC5 (survivin)] and high mobility group protein A1 (HMGA1) were found to be significantly upregulated in the IMR-32 compared to the SK-N-SH cells and mapped to highly tumorigenic pathways including, MYC, MYCN, microtubule associated protein Tau (MAPT), E2F transcription factor 1 (E2F1), sterol regulatory element binding transcription factor 1 or 2 (SREBF1/2), hypoxia-inducible factor 1α (HIF-1α), Sp1 transcription factor (SP1) and amyloid precursor protein (APP). The transcriptional knockdown (KD) of MYCN, HMGA1, FABP5 and L1-CAM significantly abrogated the proliferation of the IMR-32 cells at 48 h post transfection. The early apoptotic rates were significantly higher in the IMR-32 cells in which FABP5 and MYCN were knocked down, whereas cellular migration was significantly abrogated with FABP5 and HMGA1 KD compared to the controls. Of note, L1-CAM, HMGA1 and FABP5 KD concomitantly downregulated MYCN protein expression and MYCN KD concomitantly downregulated L1-CAM, HMGA1 and FABP5 protein expression, while survivin protein expression was significantly downregulated by MYCN, HMGA1 and FABP5 KD. In addition, combined L1-CAM and FABP5 KD led to the concomitant downregulation of HMGA1 protein expression. On the whole, our data indicate that this inter-play between MYCN and the highly tumorigenic proteins which are upregulated in the malignant IMR-32 cells may be fueling their aggressive behavior, thereby signifying the importance of combination, multi-modality targeted therapy to eradicate this deadly childhood cancer

Sources micro-ondes à base de résonateurs optiques à très fort facteur de qualité : modélisation, stabilisation et métrologie

RF photonics technology offers an attractive alternative to classical electronic approaches in several microwave systems for military, space and civil applications. One specific original architecture dubbed as optoelectronic oscillator (OEO) allows the generation of spectrally pure microwave reference frequencies, when the microwave photonic link is used as a feedback loop. Various studies have been conducted during this thesis on the OEO, especially the one that is based on fiber ring resonators, in order to optimize and improve its phase noise performance and its long-term stability. Precise characterization and modeling of the optical resonator are the first step towards overall system design. The resonator metrology is performed using an original approach, known as RF spectral characterization. The experimental results have demonstrated that this technique is helpful for the identification of the resonator's coupling regime and the accurate determination of the main resonator parameters such as the intrinsic and extrinsic quality factors or the coupling coefficients. A second study was directed toward implementing a reliable nonlinear model of the system. In such a model, the fast photodiode require an accurate description, in order to reduce the conversion of the optical amplitude noise into RF noise. A new nonlinear equivalent circuit model of a fast photodiode has been implemented in a microwave circuit simulator: Agilent ADS. This new model is able to describe the conversion of the laser relative intensity noise (RIN) into microwave phase noise at the photodiode output. An optimal optical power at the photodiode's input has been identified, at which the contribution of the laser RIN in RF phase noise is negligible. When it comes to practical applications, the desired performance of an OEO is threatened by various disturbances that may result in a frequency shift of both the laser frequency and the transmission peak of the resonator, which causes a malfunction of the OEO. Therefore it is desirable to use a stabilization system to control the difference between the laser frequency and the resonator frequency. A series of tests and experiments have been carried out to investigate the possibility, on one hand, to replace the commercial servo controller that was used up until now in the Pound-Drever-Hall loop, with a low noise homemade one and, on the other hand, to use a semiconductor laser to reduce the system size. A detailed review of these approaches is presented.La technologie photonique-RF offre une alternative intéressante à l'approche purement électronique dans différents systèmes micro-ondes pour des applications militaires, spatiales et civiles. Un composant original, l'oscillateur optoélectronique (OEO), permet la génération de signaux RF stables et à haute pureté spectrale. Il est basé sur une liaison photonique micro-onde utilisée comme boucle de rétroaction et comportant soit une fibre longue, soit un résonateur à fort coefficient de qualité. Différentes études ont été menées au cours de cette thèse afin d'optimiser et d'améliorer la performance en termes de stabilité et de bruit de phase pour le cas de l'OEO à résonateur. La caractérisation fine et la modélisation des résonateurs est une première étape de la conception globale du système. La métrologie du résonateur optique est réalisée par une technique originale, dite de spectroscopie RF. Les résultats expérimentaux ont révélé que cette technique permet d'une part d'identifier le régime de couplage du résonateur et d'autre part de déterminer avec une grande précision tous les paramètres d'un dispositif résonant, comme les facteurs de qualité interne et externe ou les facteurs de couplage. Une deuxième étude a été orientée vers l'implémentation d'un modèle non-linéaire fiable du dispositif. Dans un tel modèle, la photodiode rapide nécessitait une description plus précise, dans le but de contrôler la conversion du bruit d'amplitude optique en bruit de phase de l'OEO. Un nouveau modèle non-linéaire d'une photodiode hyperfréquence a été développé sous un logiciel commercial: Agilent ADS. Ce nouveau modèle rend effectivement compte de cette conversion de bruit. Une puissance optique optimale à l'entrée de la photodiode a été déterminée, pour laquelle la contribution de RIN du laser au bruit de phase RF pourrait être négligeable. La performance de l'OEO est affectée par diverses perturbations entrainant un décalage en fréquence entre la fréquence du laser et la fréquence de résonance du résonateur. Il est donc important d'utiliser un système de stabilisation pour contrôler cette différence de fréquence. Des séries d'expériences et de tests ont été menées pour étudier la possibilité, d'une part, de remplacer l'électronique commerciale utilisée auparavant pour le système de verrouillage en fréquence (boucle de Pound-Drever-Hall) par une électronique faible bruit et, d'autre part, d'utiliser un laser à semi-conducteur. Un bilan de ces approches est présenté

Towards optical-frequency-comb generation in continuous-wave-pumped titanium-indiffused lithium-niobate waveguide resonators

Much progress, both experimentally and theoretically, has recently been made towards optical-frequency-comb generation from continuously pumped second-order nonlinear systems. Here, we present observations towards finding an integrated solution for such a system, using a titanium-indiffused lithium-niobate waveguide resonator. These results are compared to the recently developed theory for equivalent systems. The system is seen to exhibit strong instabilities, which require further investigation in order to fully determine the suitability of this platform for stable optical-frequency-comb generation.Peer reviewe

Frequency comb generation in a continuous-wave pumped second-order nonlinear waveguide resonator

Optical frequency comb generation has been experimentally studied using an integrated system based on a lithium niobate waveguide resonator featuring a strong quadratic nonlinearity. Our theoretical model shows good agreement with the experimental results. (c) 2019 The Author(s)Peer reviewe

Oscillateur optoélectronique: Modélisation et Amélioration des Performances

National audienceLa simulation du bruit de phase des oscillateurs optoélectroniques est décrite, et plus particulièrement près de la porteuse (bruit en 1/f) qui est une limitation pour les systèmes à haute performance. Le processus principalement analysé est celui de la conversion du bruit d'amplitude du laser en bruit de phase RF. L'approche proposée démontre l'existence d'une puissance optique optimale, pour laquelle cette conversion est quasiment nulle, et par la suite permet une amélioration du bruit de phase des oscillateurs optoélectroniques basés sur des résonateurs optiques fibrés

Modélisation non-linéaire de photodiodes hyperfréquences

National audienceUn nouveau Modèle non-linéaire de photodiode, décrivant la conversion du bruit d'intensité relative du laser en bruit de phase RF, est proposé. Ce modèle comprend une cellule à retard RC non-linéaire. La validité de ce circuit équivalent est confirmée par un bon accord entre les résultats mesurés et les résultats simulés pour différentes fréquences micro-ondes