RF MEMS reference oscillators platform for wireless communications

A complete platform for RF MEMS reference oscillator is built to replace bulky quartz from mobile devices, thus reducing size and cost. The design targets LTE transceivers. A low phase noise 76.8 MHz reference oscillator is designed using material temperature compensated AlN-on-silicon resonator. The thesis proposes a system combining piezoelectric resonator with low loading CMOS cross coupled series resonance oscillator to reach state-of-the-art LTE phase noise specifications. The designed resonator is a two port fundamental width extensional mode resonator. The resonator characterized by high unloaded quality factor in vacuum is designed with low temperature coefficient of frequency (TCF) using as compensation material which enhances the TCF from - 3000 ppm to 105 ppm across temperature ranges of -40˚C to 85˚C. By using a series resonant CMOS oscillator, phase noise of -123 dBc/Hz at 1 kHz, and -162 dBc/Hz at 1MHz offset is achieved. The oscillator’s integrated RMS jitter is 106 fs (10 kHz–20 MHz), consuming 850 μA, with startup time is 250μs, achieving a Figure-of-merit (FOM) of 216 dB. Electronic frequency compensation is presented to further enhance the frequency stability of the oscillator. Initial frequency offset of 8000 ppm and temperature drift errors are combined and further addressed electronically. A simple digital compensation circuitry generates a compensation word as an input to 21 bit MASH 1 -1-1 sigma delta modulator incorporated in RF LTE fractional N-PLL for frequency compensation. Temperature is sensed using low power BJT band-gap front end circuitry with 12 bit temperature to digital converter characterized by a resolution of 0.075˚C. The smart temperature sensor consumes only 4.6 μA. 700 MHz band LTE signal proved to have the stringent phase noise and frequency resolution specifications among all LTE bands. For this band, the achieved jitter value is 1.29 ps and the output frequency stability is 0.5 ppm over temperature ranges from -40˚C to 85˚C. The system is built on 32nm CMOS technology using 1.8V IO device

Lithium niobate RF-MEMS oscillators for IoT, 5G and beyond

This dissertation focuses on the design and implementation of lithium niobate (LiNbO3) radiofrequency microelectromechanical (RF-MEMS) oscillators for internet-of-things (IoT), 5G and beyond. The dissertation focuses on solving two main problems found nowadays in most of the published works: the narrow tuning range and the low operating frequency (sub 3 GHz) acoustic oscillators currently deliver. The work introduced here enables wideband voltage-controlled MEMS oscillators (VCMOs) needed for emerging applications in IoT. Moreover, it enables multi-GHz (above 8 GHz) RF-MEMS oscillators through harnessing over mode resonances for 5G and beyond. LiNbO3 resonators characterized by high-quality factor (Q), high electromechanical coupling (kt2), and high figure-of-merit (FoMRES= Q kt2) are crucial for building the envisioned high-performance oscillators. Those oscillators can be enabled with lower power consumption, wider tuning ranges, and a higher frequency of oscillation when compared to other state-of-the-art (SoA) RF-MEMS oscillators. Tackling the tuning range issue, the first VCMO based on the heterogeneous integration of a high Q LiNbO3 RF-MEMS resonator and complementary metal-oxide semiconductor (CMOS) is demonstrated in this dissertation. A LiNbO3 resonator array with a series resonance of 171.1 MHz, a Q of 410, and a kt2 of 12.7% is adopted, while the TSMC 65 nm RF LP CMOS technology is used to implement the active circuitry with an active area of 220×70 µm2. Frequency tuning of the VCMO is achieved by programming a binary-weighted digital capacitor bank and a varactor that are both connected in series to the resonator. The measured best phase noise performances of the VCMO are -72 and -153 dBc/Hz at 1 kHz and 10 MHz offsets from 178.23 and 175.83 MHz carriers, respectively. The VCMO consumes a direct current (DC) of 60 µA from a 1.2 V supply while realizing a tuning range of 2.4 MHz (~ 1.4% tuning range). Such VCMOs can be applied to enable ultralow-power, low phase noise, and wideband RF synthesis for emerging applications in IoT. Moreover, the first VCMO based on LiNbO3 lateral overtone bulk acoustic resonator (LOBAR) is demonstrated in this dissertation. The LOBAR excites over 30 resonant modes in the range of 100 to 800 MHz with a frequency spacing of 20 MHz. The VCMO consists of a LOBAR in a closed-loop with two amplification stages and a varactor-embedded tunable LC tank. By the bias voltage applied to the varactor, the tank can be tuned to change the closed-loop gain and phase responses of the oscillator so that Barkhausen’s conditions are satisfied for the targeted resonant mode. The tank is designed to allow the proposed VCMO to lock to any of the ten overtones ranging from 300 to 500 MHz. These ten tones are characterized by average Qs of 2100, kt2 of 1.5%, FoMRES of 31.5 enabling low phase noise, and low-power oscillators crucial for IoT. Owing to the high Qs of the LiNbO3 LOBAR, the measured VCMO shows a close-in phase noise of -100 dBc/Hz at 1 kHz offset from a 300 MHz carrier and a noise floor of -153 dBc/Hz while consuming 9 mW. With further optimization, this VCMO can lead to direct RF synthesis for ultra-low-power transceivers in multi-mode IoT nodes. Tackling the multi-GHz operation problem, the first Ku-band RF-MEMS oscillator utilizing a third antisymmetric overtone (A3) in a LiNbO3 resonator is presented in the dissertation. Quarter-wave resonators are used to satisfy Barkhausen’s oscillation conditions for the 3rd overtone while suppressing the fundamental and higher-order resonances. The oscillator achieves measured phase noise of -70 and -111 dBc/Hz at 1 kHz and 100 kHz offsets from a 12.9 GHz carrier while consuming 20 mW of dc power. The oscillator achieves a FoMOSC of 200 dB at 100 kHz offset. The achieved oscillation frequency is the highest reported to date for a MEMS oscillator. In addition, this dissertation introduces the first X-band RF-MEMS oscillator built using CMOS technology. The oscillator consists of an acoustic resonator in a closed loop with cascaded RF tuned amplifiers (TAs) built on TSMC RF GP 65 nm CMOS. The TAs bandpass response, set by on-chip inductors, satisfies Barkhausen's oscillation conditions for A3 only. Two circuit variations are implemented. The first is an 8.6 GHz standalone oscillator with a source-follower buffer for direct 50 Ω-based measurements. The second is an oscillator-divider chain using an on-chip 3-stage divide-by-2 frequency divider for a ~1.1 GHz output. The standalone oscillator achieves measured phase noise of -56, -113, and -135 dBc/Hz at 1 kHz, 100 kHz, and 1 MHz offsets from an 8.6 GHz output while consuming 10.2 mW of dc power. The oscillator also attains a FoMOSC of 201.6 dB at 100 kHz offset, surpassing the SoA electromagnetic (EM) and RF-MEMS based oscillators. The oscillator-divider chain produces a phase noise of -69.4 and -147 dBc/Hz at 1 kHz and 1 MHz offsets from a 1075 MHz output while consuming 12 mW of dc power. Its phase noise performance also surpasses the SoA L-band phase-locked loops (PLLs). The demonstrated performance shows the strong potential of microwave acoustic oscillators for 5G frequency synthesis and beyond. This work will enable low-power 5G transceivers featuring high speed, high sensitivity, and high selectivity in small form factors

Determinants of Unemployment Status: Indicating College Majors that reduces the Unemployment Status in Lebanon

Unemployment status is considered one of the divisive economic issues. This paper aims to examine the factors such as age, gender, geographical area, educational level, college major and work experience that affect unemployment status in Lebanon. As well as predicting college majors that reduces unemployment in Lebanon. Using the survey method to collect data, and after refining the questionnaires, a total of 731 answers from different Lebanese areas were selected for this study. This study found that individuals with higher educational levels and higher work experience are set to have higher chances to be employed. Another finding is that males have more opportunities to get hired. With respect to the geographical area, citizens that lives in the capital Beirut, have more chances to enter the labor market. Individuals between the age of 24 and 37 have higher chances to get recruited. By studying the college majors, this study found that individuals that have business management, computer science, art, health, nursing, nutrition and psychology as a college major could guarantee a job opportunity more than individuals with other majors. The findings would help students in choosing a college major that helps them find a job opportunity after graduating

Genetic and physiological responses to heat stress in Brassica napus

Given the current rise in global temperatures, heat stress has become a major abiotic challenge affecting the growth and development of various crops and reducing their productivity. Brassica napus, the second largest source of vegetable oil worldwide, experiences a drastic reduction in seed yield and quality in response to heat. This review outlines the latest research that explores the genetic and physiological impact of heat stress on different developmental stages of B. napus with a special attention to the reproductive stages of floral progression, organogenesis, and post flowering. Several studies have shown that extreme temperature fluctuations during these crucial periods have detrimental effects on the plant and often leading to impaired growth and reduced seed production. The underlying mechanisms of heat stress adaptations and associated key regulatory genes are discussed. Furthermore, an overview and the implications of the polyploidy nature of B. napus and the regulatory role of alternative splicing in forming a priming-induced heat-stress memory are presented. New insights into the dynamics of epigenetic modifications during heat stress are discussed. Interestingly, while such studies are scarce in B. napus, opposite trends in expression of key genetic and epigenetic components have been identified in different species and in cultivars within the same species under various abiotic stresses, suggesting a complex role of these genes and their regulation in heat stress tolerance mechanisms. Additionally, omics-based studies are discussed with emphasis on the transcriptome, proteome and metabolome of B. napus, to gain a systems level understanding of how heat stress alters its yield and quality traits. The combination of omics approaches has revealed crucial interactions and regulatory networks taking part in the complex machinery of heat stress tolerance. We identify key knowledge gaps regarding the impact of heat stress on B. napus during its yield determining reproductive stages, where in-depth analysis of this subject is still needed. A deeper knowledge of heat stress response components and mechanisms in tissue specific models would serve as a stepping-stone to gaining insights into the regulation of thermotolerance that takes place in this important crop species and support future breeding of heat tolerant crops

Cellular intrinsic factors involved in the resistance of squamous cell carcinoma to photodynamic therapy

Photodynamic therapy (PDT) is widely used to treat non-melanoma skin cancer. However, some patients affected with squamous cell carcinoma (SCC) do not respond adequately to PDT with methyl-δ-aminolevulinic acid (MAL-PDT) and the tumors acquire an infiltrative phenotype and became histologically more aggressive, less differentiated, and more fibroblastic. To search for potential factors implicated in SCC resistance to PDT, we have used the SCC-13 cell line (parental) and resistant SCC-13 cells obtained by repeated MAL-PDT treatments (5th and 10th PDT-resistant generations). Xenografts assays in immunodeficient mice showed that the tumors generated by resistant cells were bigger than those induced by parental cells. Comparative genomic hybridization array (aCGH) showed that the three cell types presented amplicons in 3p12.1 CADM2, 7p11.2 EFGR, and 11q13.3 CCND1 genes. The 5th and 10th PDT-resistant cells showed an amplicon in 5q11.2 MAP3K1, which was not present in parental cells. The changes detected by aCGH on CCND1, EFGR, and MAP3K1 were confirmed in extracts of SCC-13 cells by reverse-transcriptase PCR and by western blot, and by immunohistochemistry in human biopsies from persistent tumors after MAL-PDT. Our data suggest that genomic imbalances related to CCND1, EFGR, and particularly MAP3K1 seem to be involved in the development of the resistance of SCC to PDT. © 2014 The Society for Investigative DermatologyThe work was supported by MINECO (FIS PI12/01253), and Comunidad de Madrid (S2010/BMD-2359). We recognize the valuable contributions of Javier Suela and Juan Cruz Cigudos

Papel del sistema del glutatión en la adaptación y resistencia de los tumores linfoides al estrés oxidativo

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 13-12-2019Esta tesis tiene embargado el acceso al texto completo hasta el 13-06-2021La transformación tumoral es un proceso complejo que implica varios cambios en el funcionamiento normal de la célula. Entre las habilidades que adquiere una célula en su transición a un estado maligno se encuentra la capacidad de crecimiento independiente de anclaje, íntimamente relacionada con los mecanismos que permiten evadir la muerte celular inducida por pérdida del anclaje a un sustrato rígido. El ensayo más empleado para determinar la capacidad de crecimiento independiente de anclaje es el de formación de colonias en agar blando. Mientras que los linfomas, tumores sólidos resultado de la malignización de células linfoides, forman colonias en agar blando, los linfocitos inmortales no tumorales no crecen. Los linfocitos normales requieren de anclaje a sustratos y a otras células para llevar a cabo sus funciones biológicas. Sin embargo, en este trabajo hemos observado que, in vitro, tanto las líneas celulares linfoides tumorales como las inmortales no tumorales son capaces de proliferar en ausencia de interacción directa con otras células o con el sustrato rígido. El estudio en profundidad del papel restrictivo que ejerce el cultivo en agar blando sobre las líneas inmortales, pero no sobre las líneas tumorales, reveló que es capaz de inducir estrés oxidativo en las células a través del aumento de los niveles de especies reactivas de oxígeno (ROS). Las células linfoides tumorales, a diferencia de las inmortales no tumorales, son capaces de hacer frente al estrés oxidativo inducido por el cultivo en agar gracias al incremento en los niveles de glutatión reducido (GSH), uno de los principales mecanismos de defensa antioxidante de la célula. La pérdida de la producción de GSH en células tumorales, mediante la inhibición farmacológica o mediante el silenciamiento de la expresión de la subunidad catalítica de la enzima limitante en su síntesis (GCLC), aumentó el estrés oxidativo e inhibió drásticamente el crecimiento de las células tumorales en agar blando. El silenciamiento de GCLC también inhibió el crecimiento de linfomas en un modelo de xenotrasplante subcutáneo en ratones inmunodeficientes NOD-SCID. Los tejidos linfoides tumorales de un modelo de ratón que sobre-expresa MYC en linfocitos B (lambda-MYC) muestran mayores niveles de GSH que los tejidos linfoides de ratones sanos y el tratamiento de los ratones lambda-MYC con un inhibidor farmacológico de GCLC previno la linfomagénesis en este modelo animal, lo que junto con el resto de resultados obtenidos en este trabajo sugiere la posibilidad de dirigir futuros tratamientos contra los mecanismos responsables de proporcionar resistencia al estrés oxidativo de las células tumorales.Tumor transformation is a complex process that involves several changes in cell physiology. Among the abilities that a cell acquires in its transition to a malignant state is the capacity for anchorage-independent growth, a capacity intimately related to the mechanisms that prevent cell death induced by loss of anchorage to a rigid substrate. Colony formation in soft agar hydrogels is the gold-standard assay for anchorage-independent growth. While lymphomas, solid tumors resulting from malignancy of lymphoid cells, form colonies in soft agar, immortal non-tumor lymphocytes do not grow. Lymphocytes anchor to the extracellular matrix and other cells while carrying out their biological function. However, we have observed that both tumor lymphoid and immortal non-tumor cells proliferate in the absence of direct interaction with other cells or with a rigid substrate. Research of the mechanisms involved in the restrictions imposed by soft agar on the growth of immortal lymphoid cell lines, but not on that of lymphoid tumor cell lines, revealed that of the culture in soft agar induces oxidative stress through of the increase of reactive oxygen species (ROS). Tumor lymphoid cells, unlike non-tumor immortal lymphoid cells, are able to cope with oxidative stress induced by culture in soft agar through the increase in reduced glutathione levels (GSH), one of the main antioxidant defense mechanisms of cells. The loss of GSH production in tumor cells, through pharmacological inhibition or by silencing of the catalytic subunit of the limiting enzyme of its synthesis (GCLC), markedly inhibited their growth in soft agar. Moreover, GCLC knockdown also inhibited lymphoid tumor growth in a model of subcutaneous xenograft in immunodeficient NOD-SCID mice. Lymphoid tumor tissues in the lambda-MYC mouse model, that overexpresses MYC in B-lymphocytes, show higher GSH levels than lymphoid tissues from wild-type littermates, and pharmacological inhibition of GCLC in lambda-MYC mice prevented lymphomagenesis. Together, our results strongly encourage directing lymphoid tumor treatments against mechanisms responsible for oxidative stress resistance in tumor cells

Les infections broncho-pulmonaires à germes atypiques chez l'enfant :Mythe ou réalité ?

Mycoplasma pneumoniae and Chlamydia pneumoniae are the most common atypical pathogens seen in respiratory infections in children. Currently, the management of atypical pneumonia due to these pathogens is blurry. The clinical features are hardly specific ;it appears that M. pneumoniae respiratory infect ions are associated with chest pain and the absence of wheezing, however, further confirmations are needed. Hoarseness is frequently seen with C. pneumoniae infection. Co-infections with viruses, bacteria or even between M. pneumoniae and C. pneumoniae can be frequent. Infection with either of these bacteria seems to increase the incidence of asthma. PCR appears to be the most sensitive and specific for rapid diagnosis of M. pneumoniae and C. pneumoniae infections, however, it cannot dif ferentiate asymptomatic carriage from infection. Serodiagnosis can be helpful. This requires two serum samples taken with several weeks interval. Macrolides are the classical antibiotics used for treatment of these pathogens. In vivo efficacy of antibiotic treatment of M. pneumoniae remains unclear. Resistance to macrolides in M. pneumoniae treatment has been described. In conclusion, there is still a lack in scientific literature of high level evidences and clear consensus in the management of suspicious infection due to M. pneumoniae and C. pneumoniae.SCOPUS: ar.jinfo:eu-repo/semantics/publishe