Novel Quadruple-mode, Dual-mode and Dual-band Dielectric Resonator Filters and Multiplexers

Dielectric resonators offer high-Q (low loss) characteristics which make them ideal for filters with narrow bandwidth and low insertion loss specifications. They are mainly used in satellite and wireless system applications. Such applications desire the highest performance filters with the lowest amount of size and mass, which has been the main motivation for size reduction techniques invented over the past three decades for these filters. In addition with the emergence of different communication system technologies, several bands are now required to be supported by a single front-end, calling for emergence and development of dual-band and multi-band filters. To date few work has been done in the area of dual-band dielectric resonator filters. Dielectric resonators filters are important components in many communication systems, when a group of such filters are brought together to perform multiplexing of RF channels. These multiplexer systems tend to be fairly complex and bulky in design, and there is strong desire to reduce their size and mass to the maximum extent possible. Novel quadruple-mode, dual-mode, and dual-band filters as well multiplexers are presented in this thesis. The first ever quadruple-mode dielectric resonator filter using the simple cylinder structure is reported in this work. A cylindrical dielectric resonator sized appropriately in terms of its diameter and height is shown to operate as a quadruple-mode resonator, which is achieved by having two mode pairs of the structure resonate at the same frequency. Single-cavity, quad-mode filters and higher order 4n-pole filters are realizable using this quad-mode cylindrical resonator, offering significant size reduction for dielectric resonator filter applications. The structure of the quad-mode cylinder is then simplified by cutting lengthwise along the central axis of the cylinder, to produce a half-cut cylinder suitable for operation in a dual-mode regime. Novel dual-mode, 2n-pole filters are realizable using this half-cut cylinder, by making the two resonances equal in frequency. The dual-mode half-cut filter is shown to be a strong contender for replacing existing dual-mode filters used in satellite and wireless applications, as it offers superior size and mass characteristics. By making the resonances unequal in frequency, novel dual-band filters and multiplexers are further realizable, by carrying separate frequency bands on different resonant modes of the structure. The first true orthogonal mode dual-band dielectric resonator is presented in this work, using the half-cut structure. Multiplexers are also derived from these dual-band resonators, which greatly reduce size and mass of many-channel multiplexers at the system level, as each two channels are overloaded in one physical branch. Full control of center frequencies of resonances, input and inter-resonator couplings are achievable, allowing realization of microwave filters with different bandwidth, frequency, and return loss specifications, as well as advanced filtering functions with prescribed transmission zeros. Spurious performance of the half-cut cylinder can also be improved by cutting one or more through-way slots between opposite surfaces of the resonator. Size and mass reduction achieved by using the full and half-cut resonators described in this thesis, provide various levels of size reduction in microwave systems, both device and system level

Detection and Localization of HCA2 Receptors in Urinary System of Male Rats with Immunohistochemical Method

Background and aims: HCA2 receptors have attracted much interest due to their role as the target of important hypolipidemic agent, niacin. In this study, the presence of HCA2 receptors as well as cell types that express them has been evaluated in different parts of male rats' urinary system including kidney, ureter, urinary bladder and urethra (in penis). Methods: In this experimental study, six adult male Wistar rats were used. Histological slides were made from above mentioned parts and were evaluated by immunohistochemical method. Results: In kidney, capillary epithelium showed a high reactivity while proximal epithelial cells were stained moderately. The epithelial cells of loop of Henle, distal and collective tubules as well as glomerular cells showed weak staining. In urinary bladder, transitional epithelium and capillary endothelium showed weak staining, while smooth muscle had no reactivity. In penile tissue, urethral epithelium and smooth muscle cells were weakly positive while capillary endothelial cells showed moderate reactivity. Conclusion: This study shows that HCA2 receptors are present in different parts of male rats' urinary tract. Distribution of these receptors is dependent to cell type and location in the urinary tract. The findings pave the road for future studies on possible role of these receptors in urinary system

Evaluation of Characteristics of Inpatient Falls in Rasoul Akram Hospital

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The quantitative changes trend of Iranian schools building from the early Islamic centuries until Qajar Era

Like any other piece of art indicating signs of past originalities, the Iranian architectural works are required to be recognized and introduced. From amongst the architectural subjects, schools have the most links in the most elegant formats with the past heritage, nature and environment and enjoy a certain importance. The important point concerning studying Iranian schools architecture is to recognize the trend of architecture continuance of these buildings, especially during Islamic era. From amongst the important factor in studying the continuity in schools architecture include quantitative continuity and number of schools built during each era, which shall be an effective guide in recognition of the indicated values. Based on such type of analytical vision, studying quantitative continuity of building schools and number of the same during different post-Islamic eras until Qajar Era in Iran is the main context and purpose of this study. The generality of the study represents an analysis on the number and quantitative continuance of building schools during different eras of Iran Islamic architecture, beyond which, the quantitative trend of building and important cities in terms of number of built schools in each era are identified. This study is of historical- interpretation type and collection the data and conclusion are based on comparative studies conducted on different library and field resources and refining and choosing the most correct and reliable statistics from amongst the available information. In Conclusion, the number of schools in all the post-Islamic eras in Iran, the most important cities and eras in terms of quantity of building schools are determined and relationship between political importance of cities and number of built schools in them is observed. According to the aforementioned interpretations, this study shall clarify a documented role to plan in order to take benefit from the available information in an optimized manner

Planar Resonant Blazed Gratings from a Circuit Model Standpoint

The equivalent circuit approach (ECA) is used in this work to analyze and design a previously proposed one-dimensional planar blazed grating of the resonant type. The analysis covers both the classical Littrow configuration, when the direction of the relevant diffracted order coincides with that of the incident wave (Bragg blazing), and when these directions are different (off-Bragg blazing). Once the scattering problem of the grating structure is posed as a discontinuity problem inside an equivalent generalized waveguide (corresponding to the unit cell of the original structure) and studied in terms of its equivalent circuit network, the possibility of transferring all the power of the incident plane wave into one single-diffraction order is seen as a simple impedance matching problem. An associated resonance phenomenon is also found to be implicitly associated with this matching condition. This simplifying and fruitful standpoint makes it possible to set up a systematic design procedure to find the specifications of the planar grating for either Bragg or non-Bragg blazing operation. Dielectric and strong skin-effect ohmic losses are easily implemented in the ECA and its effects in the practical design of structures are discussed.Ministerio de Ciencia, Investigación y Universidades TEC2017-84724-PJunta de Andalucía TIC-11

The Association between Neonatal Icterus or Neonatal Phototherapy and the Likelihood of Childhood Asthma among Iranian Children

Background: There might be a close link between neonatal icterus and/or neonatal phototherapy and childhood asthma. The present study aimed to assess the relationship between neonatal icterus and/or phototherapy and the likelihood of childhood asthma among Iranian population. Materials and Methods The present case-control study was performed on 102 consecutive asthmatic children hospitalized at Children’s Medical Center, Tehran, Iran. Asthma was diagnosed by a pediatric asthma and allergy specialist based on clinical manifestations and/or spirometry results for children older than 5 years. A total of 113 sex and age-matched children without asthma who were admitted to other wards during the same period of time were selected as the control group. Data were collected by a researcher-made checklist including data regarding participants’ age, gender, and gestational age, history of neonatal icterus and history and duration of phototherapy, filled by participants’ parents/guardians. Results: There was a significant difference between cases and controls with respect to preterm birth, history of phototherapy and duration of phototherapy. History of icterus was not associated with childhood asthma. In the multivariable logistic regression model, both history of phototherapy (P=0.029), and duration of phototherapy (P=0.03) were considered as determinants for occurrence of childhood asthma. Conclusion According to the results, history of neonatal icterus was not associated with childhood asthma, but history and duration of phototherapy were both determinants of childhood asthma

Efficacy of High Dose Vitamin C, Melatonin and Zinc in Iranian Patients with Acute Respiratory Syndrome due to Coronavirus Infection: A Pilot Randomized Trial

INTRODUCTION: Our aim was to investigate the efficacy of vitamin C, melatonin, and zinc in patients with severe Covid-19. METHODS:  Twenty-one adult patients were randomized 1:1 to standard care alone or standard care plus IV vitamin C (2 g, q6hr), oral melatonin (6 mg, q6hr), and oral zinc sulfate (50 mg, q6hr) for 10 days. Patients were monitored for changes in hypoxemia and inflammatory markers. RESULTS: Both treatment modalities were effective to improve PaO2/FiO2 and oxygen saturation. However, there were no significant differences between 2 groups (P > 0.05). There were reductions in CRP, ESR, and LDH levels in both study groups, although not significant. No significant difference was noted in length of ICU stay between 2 groups (P = 0.3). CONCLUSION: Our study suggests that addition of vitamin C, melatonin, and zinc to standard care is not associated with considerable improvement in patients with severe Covid-19.&nbsp