Nonlinearity and Gating in Superconducting Nanowire Single Photon Detectors

The quantum properties of electromagnetic radiation at single photon level promise to offer what are classically inaccessible. Single photon sources and detectors are therefore on demand for exploiting these properties in practical applications, including but not limited to quantum information processing and communication. In this thesis, I advance Superconducting Nanowire Single Photon Detectors (SNSPD) both in terms of models describing their operation, and their performance. I report on characterization, semi-empirical modeling, quantum-optical modeling and detector tomography. The results provide more accurate methods and formulations to characterize and mathematically describe the detectors, valuable findings from both application and device points of views. I also introduce the concept of Gated SNSPDs, show how to implement and how to characterize them. Through series of theoretical and experimental investigations, I show performance advantages of Gated SNSPDs in terms of dead time and dark count rate, important figures for many applications like quantum key distribution. The ultimate limitations of gated operation are also explored by physical modeling and simulation steps

Synthesis and Characterization of Bismuth Telluride-Based Nanostructured Thermoelectric Composite Materials

RÉSUMÉ Les matériaux et dispositifs thermoélectriques (TE) sont intéressants pour les applications en conversion d’énergie tels la récupération de chaleur, la climatisation et la réfrigération. Depuis les années 50, plusieurs efforts ont été déployés pour améliorer l’efficacité des matériaux TE pour la conversion d’énergie (amélioration de la figure de mérite ZT). Malgré ces efforts, la plupart des matériaux TE atteignent au mieux une valeur de ZT de l’ordre de 1. Pour améliorer la performance des alliages TE à base de tellurure de bismuth, nous avons développé des matériaux TE composites à partir de l’hypothèse que par addition d’interfaces dans la structure du matériau TE, il soit possible de réduire la conductibilité thermique par la diffusion des phonons sur ces interfaces. En suivant cette approche, on suppose que les propriétés de transport électronique ne seront pas grandement affectées, menant ainsi à une augmentation de ZT. Dans cette thèse, nous discuterons des procédés d’élaboration et de la caractérisation de deux types de composites TE basés sur le tellurure de bismuth. Le premier type de composite est obtenu en créant des interfaces cohérentes entre différentes phases miscibles de compositions chimiques similaires. Le second type de nanocomposite est fabriqué par l’addition de nano-particules d’une espèce différente menant à la présence d’interfaces incohérentes entre les particules et la matrice. Les étapes des procédés, la caractérisation micro- et nanostructurale ainsi que les propriétés thermoélectriques seront présentées dans cette thèse. Dans l’étude des composites avec interfaces cohérentes, nous avons produit différents mélanges d’alliages de type p de tellurure de bismuth et d’antimoine pour évaluer leurs propriétés TE et leur microstructure. Chaque composite est constitué de deux phases qui sont élaborées à partir de poudres par mécanosynthèse. Le composite est obtenu en extrudant à chaud différentes proportions des deux phases de compositions différentes. La taille de grains minimale pour les composites, évaluée par microscopie électronique à balayage, montre une réduction de 50% par rapport à la taille de grains de l’alliage (Bi0.2Sb0.8)2Te3 élaboré par la méthode conventionnelle. L’analyse par diffraction des rayons x (XRD) indique une décroissance systématique de la taille des cristallites dans e composite. Les mécanismes de diffusion des porteurs de charges ont été caractérisés à partir de mesures de l’effet Hall. Nous n’avons pas observé d’évidence de diffusion des porteurs dans ces composites. Aucune décroissance significative du facteur de puissance n’a été observée et de hautes valeurs de la figure de mérite ZT ont été obtenues, entre 0.86 et 1.04.----------ABSTRACT Thermoelectric (TE) materials and devices are attractive in solid-state energy conversion applications such as waste heat recovery, air-conditioning, and refrigeration. Since the 1950’s lots of unremitting efforts have been made to enhance the efficiency of energy conversion in TE materials (i. e. improving the figure of merit (ZT)), however, most of commercial bulk TE materials still suffer from low efficiency with ZTs around unity. To enhance the performance of bismuth telluride based TE alloys, we have developed composite TE materials, based on the idea that introducing more engineered interfaces in the bulk TE materials may lead to thermal conductivity reduction due to increased phonon scattering by these interfaces. In this approach it is expected that the electronic transport properties of the material are not effectively affected. Consequently, ZT enhancement can be achieved. In this dissertation we will discuss synthesis and characterization of two types of bismuth telluride based bulk composite TE materials. The first type is engineered to contain the presence of coherent interfaces between phases in the material resulting from different mixtures of totally miscible compounds with similar composition. The second type includes the nanocomposites with embedded foreign nano-particles in which the matrix and the particles are delimited by incoherent interfaces. The synthesis procedure, micro- and nano-structures as well as thermoelectric properties of these composites will be presented. In our study on the composites with coherent interfaces, we produced a series of different composites of p-type bismuth antimony telluride alloys and studied their microstructure and thermoelectric properties. Each composite consists of two phases that were obtained in powder form by mechanical alloying. Mixed powders in various proportions of the two different phases were consolidated by hot extrusion to obtain each bulk composite. The minimum grain size of bulk composites as revealed by scanning electron microscopy shows a 50% reduction compared to the conventional (Bi0.2Sb0.8)2Te3 . XRD analysis indicates a systematic decrease of crystallite size in the composite materials. Scattering mechanisms of charge carriers were evaluated by Hall effect measurements. There is no evidence of carriers scattering linked to the composite nature in these materials. The composites show no significant degradation of the power factor and high peak ZT values ranging from 0.86 to 1.04. It was found, contrary to expectations that the thermal conductivity of the composites slightly increases compared to the conventional alloy

A cost-utility analysis of different antiviral medicine regimens in patients with chronic hepatitis C virus genotype 1 infection

Background: Despite the introduction of new drug regimens with high effectiveness for the hepatitis C virus (HCV) patients, especially in HCV genotype 1, no cost-effectiveness study on the selection of the superior drug strategy in Iran has been conducted yet. Objectives: This study is aimed to assess the cost-effectiveness of the three drug regimens of pegylated interferon and ribavirin (PR), sofosbuvir (SOF) + PR and ledipasvir and sofosbuvir (LDV/SOF) in patients with HCV genotype 1 in Iran in the year 2014. Methods: A Markov micro-simulation model was used to evaluate the cost-effectiveness of the three drug strategies for a cohort of 10000 patients. Quality-adjusted life-years (QALYs) were extracted from published studies. Cost data was estimated through the review of medical records and obtaining experts opinion. Results: The results showed that the SOF + PR drug compared with PR had a lower cost and was more effective, but compared with the LDV/SOF, in spite of its lower cost, it was less efficient. The QALY values obtained for PR, SOF + PR and LDV/SOF, respectively, were 10.98, 12.08 and 12.28 and their costs were $41,741,$ 7,676 and $46,993. Moreover, the results obtained from acceptability curves showed that SOF + PR were the most cost-effective treatment for thresholds below$ 45,270 PPP. Conclusions: The use of SOF + PR regimen or LDV/SOF can significantly reduce the incidence of complications associated with the disease. For example, short and long-term outcomes are better than the current drug regimens for HCV genotype 1 patients in all stages of the disease

A Narrative Case History of Distance Education Before, During, and After COVID-19 in China and Iran

Educational hub refers to centres of excellence in higher education and research whose aims are to provide high-quality education for both national and international students to enhance the competitiveness of the country. These educational hubs provide an opportunity for knowledge exchanges and innovation in local regions through education and training. In response to the COVID-19 pandemic, rapid shifts were made towards online learning in education around the world. Although the lockdown is over, remote learning will likely play an increasingly prominent role in education. The adoption of scaled remote learning during the pandemic provided evidence of the importance of online learning. They offer an insight into global society, helping prepare students for an increasingly interconnected world by facilitating links between different regions. Educational hubs can be tied to distance learning and are successful in attracting international students when offering a combination of distance learning methods and innovative programs. This paper examines the phenomenon of educational hubs in higher education for international education through online learning with digital technology. New opportunities for online and distance learning within the definition of educational hubs are analyzed, and three online and blended learning models that reflect the development of educational hubs based on COVID-19 conditions of education are offered. In addition, the successful cases and experiences of distance learning hubs in China and Iran in recent years are described

Identification and Prioritization of Strategies to Tackle the Barriers of Youth Engagement in Public Sports and Health Based on ANP Method in Mashhad

Introduction: Public sport as a low-cost and fun but effective tool can be part of the daily life plan of the people that can function for the general public in terms of individual and social characteristics, and, in particular, contribute significantly to the promotion of physical, psychological and social health of the youth.Methods: In this causal-comparative study, experts in the field of public sport and health were consulted. 30 public sport and health activists including coaches and staff of the sports board as well as university professors and 10 professors of physical education and health were selected through interviews. Then, the data obtained were analyzed by Lambda method and the design of matrix tables for paired comparisons of final weights of barriers and sub-barriers, using the AHP method and the ranking of barriers and sub-barriers by ANP method at the level of p Conclusion: Among the proposed solutions for management barriers, the decision to approve the plan by the deputies was the first priority for the Ministry of Health and Treatment to create sports spaces. Among the solutions presented for social-cultural barriers, the agreement to exchange media coverage of women's sports activities and increase knowledge and awareness were first and foremost for women and men. Also, parents' justification of positive effects of exercise and health on improving mental performance for personal-familial barriers was given the priority

Experimental investigation on coal fines migration through proppant packs: Assessing variation of formation damage and filtration coefficients

Coalbed methane reservoirs generate coal fines during production that cause irreversible damage to cleat conductivity. In severe scenarios, this can result in temporary closure of recovery operations from the gas well(s). In this work, we simulate the impact of coal fines on proppant conductivity. Four sets of experiments were conducted: effect of salinity – 0 to 3.5 NaCl wt.%, pH – 2 to 11, coal rank - anthracite, high volatile bituminous, and sub-bituminous; and 0.01 wt% additives – Sodium Dodecyl Benzene Sulfonate (SDBS) and Cetrimonium bromide (CTAB) and validated with established analytical models. Moreover, medical computed tomography of three extreme cases was conducted. Results showed that coal fines uniform distribution within a proppant pack does not cause greater conductivity decline than non-uniform distribution owing to clogging and straining. Additionally, results showed that anionic surfactants successfully dispersed coal fines. These research results can be applied to coalbed methane reservoirs, especially during the early water drainage phase, to optimise the impact of coal fines on proppant conductivity

A cost utility and cost effectiveness analysis of different oral antiviral medications in patients with HBeAg-Negative chronic hepatitis B in Iran: an economic microsimulation decision model

Background: Although hepatitis B infection is the major cause of chronic liver disease in Iran, no studies have employed economic evaluations of the medications used to treat Iranian patients with chronic hepatitis B (CHB). Therefore, the cost-effectiveness of the different treatment options for this disease in Iran is unknown. Objectives: The aim of this study was to compare the cost utility and cost-effectiveness of medication strategies tailored to local conditions in patients with HB e antigen (HBeAg)-negative CHB infection in Iran. Methods: An economic evaluation of the cost utility of the following five oral medication strategies was conducted: adefovir (ADV), lamivudine (LAM), ADV + LAM, entecavir (ETV), and tenofovir (TDF). A Markov microsimulation model was used to estimate the clinical and economic outcomes over the course of the patient’s lifetime and based on a societal perspective. Medical and nonmedical direct costs and indirect costs were included in the study and life-years gained (LYG) and quality-adjusted life-years (QALY) were determined as measures of effectiveness. The results are presented in terms of the incremental cost-effectiveness ratio (ICER) per QALY or LYG. The model consisted of nine stages of the disease. The transition probabilities for the movement between the different stages were based on clinical evidence and international expert opinion. A probabilistic sensitivity analysis (PSA) was used to measure the effects of uncertainty in the model parameters. Results: The results revealed that the TDF treatment strategy was more effective and less costly than the other options. In addition, TDF had the highest QALY and LYG in the HBeAg-negative CHB patients, with 13.58 and 21.26 (discounted) in all comparisons. The PSA proved the robustness of the model results. The cost-effectiveness acceptability curves showed that TDF was the most cost-effective treatment in 59% - 78% of the simulations of HBeAg-negative patients, with WTP thresholds less than $14010 (maximum WTP per QALY). Conclusions: The use of TDF in patients with HBeAg-negative CHB seemed to be a highly cost-effective strategy. Compared with the other available medication options, TDF was the most cost-saving strategy. Thus, TDF may be the best option as a first-line medication. Patients can also be switched from other medications to TDF

Causal Layers of Social Dissatisfaction in the Islamic Republic of Iran

IntroductionSocial dissatisfaction in Iran, particularly over the past decade, has been widespread and profound, as confirmed by national surveys. A review of the last four decades reveals the emergence of social discontent and political unrest in various manifestations and at different times. In certain instances, such as in 2009, the protests have posed a threat to the survival and stability of the Islamic Republic of Iran. Indeed, an analysis of the frequency and duration of social protests demonstrates the growth and prevalence of social dissatisfaction within Iranian society.Social dissatisfaction can manifest itself through apathy and non-participation, as seen in the decline in political participation during the Islamic Council and presidential elections in in the recent decade, particularly in 2019 and 2021. A review of relevant research shows a lack of deep insight and comprehensive understanding of social dissatisfaction as a multi-faceted issue in Iran, which can be a major obstacle to insightful policymaking for successful and cost-effective management of social dissatisfaction.The present research aimed to analyze and elucidate the underlying factors that contribute to social dissatisfaction, and subsequently develop strategies for effectively managing and mitigating the issue within Iranian society. The objective can ultimately enhance the efficiency of the decision-making process and policymaking in order to effectively address social dissatisfaction and protests. Accordingly, the main research questions are: What are the causal factors underlying social dissatisfaction in the Islamic Republic of Iran? and what are the potential solutions to solve the issue?Materials and MethodsThe present research employed a mixed methods research design. The documentary analysis method was utilized to examine and analyze various perspectives and approaches, as well as to investigate the evolution of the phenomenon of social dissatisfaction in Iranian society. Moreover, the method of causal layered analysis (CLA) was used to analyze and explain the underlying causes that contribute to social dissatisfaction in Iran.This method incorporates the examination of four distinct layers: the litany, social/systemic causes, discourse/worldview, and myth/metaphor. The litany layer represents the surface level, encompassing the most evident and objective aspects of the future. The social/systemic layer involves exploring the technological, social, economic, historical, political, and environmental causes associated with the subject matter. The discourse layer encompasses efforts to comprehend linguistic, cultural, and social structures that shape and pertain to the future. Lastly, the myth/metaphor layer delves into the investigation and exploration of schemas, mental images, and underlying narratives.The researchers collected the data by administering an open semi-structured questionnaire to a total of 10 experts. The collected data was subjected to review by 5 additional experts, who were asked to confirm the identified causes and related factors with the ultimate aim of ensuring the validity and reliability of the data. Based on the degree of consensus and frequency, the identified causes were categorized into three levels: systemic, discursive, and metaphorical. Furthermore, the researchers developed scenarios of social dissatisfaction by sharing the collected data with 5 experts, who were requested to envision future dissatisfaction scenarios in the 2031 horizon across three categories: desirable, possible, and probable. Results and DiscussionAfter conducting a review of relevant literature and collecting insights from 10 experts, the present study examined and analyzed the causes and factors contributing to social dissatisfaction the Islamic Republic in three layers: systemic, discursive, and metaphorical. At the systemic level, various factors were identified and discussed, including the prevalence of poverty, increasing discrimination, widening class gap and increasing Gini coefficient, evolving societal lifestyles, widespread feelings of deprivation, unjust distribution of national resources, and unsustainable development, etc.In the discursive layer, various causes and factors were identified and analyzed, including the historical mistrust towards the political sphere, the duality of the Islamic Revolution and the Islamic Republic of Iran, the Shia culture and thought, the modern thought and worldview, the discourse of transformation, the discourse of Western development, and the alienation of political governance, etc. Moving to the metaphorical/mythical layer, factors such as the portrayal of the government as a bandit in Iranian culture, the usurpation of power by the state, the metaphor of the Alavi government, and historical transformation-seeking were recognized and discussed as influential elements in the development of social dissatisfaction.Moreover, in accordance with expert opinions, three scenarios (desirable, possible, and probable) were formulated and constructed regarding the future of social dissatisfaction in Iran. In the desirable scenario, effective reformist measures and the realization of the right to protest would lead to a reduction in social dissatisfaction, putting protests within a legally recognized framework. In the possible scenario, considering the continuation and exacerbation of underlying causes of dissatisfaction, we would witness the accumulation of social dissatisfaction and the emergence of intermittent episodes of violent social protests. Finally, according to the probable scenario, civil disobedience would arise as a result of the prevailing security-focused approach and the rising costs of engaging in protests.ConclusionSocial dissatisfaction remains a significant issue in Iran, posing considerable challenges to political stability and national security. Effective policymaking and management concerning social dissatisfaction initially requires a comprehensive and accurate understanding of this complex issue. In this line, the present study used the CLA method as an effective approach to examine different causal layers and drivers and their impact on social dissatisfaction. The results indicated that the Islamic Republic of Iran aims to move towards its desired scenario, which involves reducing dissatisfaction and implementing a persuasive and systematic approach to managing social protests. However, given the current circumstances, attaining this scenario proves to be challenging. Instead, the possible scenario entails the continued accumulation of dissatisfaction and ongoing social protests, which will pose a significant challenge to the political stability of the Islamic Republic of Iran. Protests will be characterized by increased violence, potentially leading the political system to adopt a hard approach in suppressing and managing social unrest. This, in turn, may exacerbate radicalism and further fuel social dissatisfaction. The probable scenario, characterized by intermittent and costly protests as well as civil disobedience, presents an alternative outlook for the future of social dissatisfaction. In this scenario, social dissatisfaction manifests itself through intermittent protests that occur at various intervals and in response to specific events. As social dissatisfaction continues to evolve and persist, some citizens may resort to civil disobedience and divergence from official values and norms

The COVID‑19‑diabetes mellitus molecular tetrahedron

Accumulating molecular evidence suggests that insulin resistance, rather than SARS-CoV-2- provoked beta-cell impair- ment, plays a major role in the observed rapid metabolic deterioration in diabetes, or new-onset hyperglycemia, during the COVID-19 clinical course. In order to clarify the underlying complexity of COVID-19 and diabetes mellitus interactions, we propose the imaginary diabetes-COVID-19 molecular tetrahedron with four lateral faces consisting of SARS-CoV-2 entry via ACE2 (lateral face 1), the viral hijacking and replication (lateral face 2), acute inflammatory responses (lateral face 3), and the resulting insulin resistance (lateral face 4). The entrance of SARS-CoV-2 using ACE2 receptor triggers an array of multiple molecular signaling beyond that of the angiotensin II/ACE2-Ang-(1–7) axis, such as down-regulation of PGC-1 α/ irisin, increased SREBP-1c activity, upregulation of CD36 and Sirt1 inhibition leading to insulin resistance. In another arm of the molecular cascade, the SARS-CoV-2 hijacking and replication induces a series of molecular events in the host cell metabolic machinery, including upregulation of SREBP-2, decrement in Sirt1 expression, dysregulation in PPAR-ɣ, and LPI resulting in insulin resistance. The COVID-19-diabetes molecular tetrahedron may suggest novel targets for therapeutic interventions to overcome insulin resistance that underlies the pathophysiology of worsening metabolic control in patients with diabetes mellitus or the new-onset of hyperglycemia in COVID-19. Keywords Covid-19 · Diabetes mellitus · Insulin resistance · Inflammation · ACE2 receptor · SARS-CoV-

Plan for Applying Total Quality Management in Education for Torbat Heydariyeh University of Medical Sciences

In this study, the appropriateness of existing quality standards and their use in practice in educational organizations were discussed. The study shows how the quality standard of TQM and QMTL and the possibility of their articulation to develop a holistic model can contribute to change this situation. The study alsoinvestigated whether this standard is an adequate basis for quality development in organizations. To implement a quality system in an educational organization, four main steps are necessary: context setting, model adaptation, model implementation/adoption, and quality development. Each step should be performed with a broad range of actors to raise awareness and consensus. To facilitate this process and to develop a quality system for an organization, the use of the holistic model for the description of quality approaches was recommended. Since the model is very generic, more research is necessary, especially to find specific solutions to different contexts of usage (e.g., for schools). Additionally, research has been initiated to analyze the differences and adaptation requirements for different countries and regions to include cultural aspects. Finally, a variety of tools is being developed to support this process, such as the initial choice of a quality approach or the choice of quality instruments. For the future, it can be expected that a variety of tools will be available to support this process and to integrate quality into a broad range of educational organizations