Receive Soft Antenna Selection for Noise-Limited/Interference MIMO Channels

Although the Multi-Input and Multi-Output (MIMO) communication systems provide very high data rates with low error probabilities, these advantages are obtained at the expense of having high signal processing tasks and the hardware cost, e.g. expensive Analog-to-Digital (A/D) converters. The increased hardware cost is mainly due to having multiple Radio Frequency (RF) chains (one for each antenna element). Antenna selection techniques have been proposed to lower the number of RF chains and provide a low cost MIMO system. Among them, due to a beamforming capability Soft Antenna Selection (SAS) schemes have shown a great performance improvement against the traditional antenna sub-set selection methods for the MIMO communication systems with the same number of RF chains. A SAS method is basically realized by a pre-processing module which is located in RF domain of a MIMO system. In this thesis, we investigate on the receive SAS-MIMO, i.e. a MIMO system equipped with a SAS module at the receiver side, in noise-limited/interference channels. For a noise-limited channel, we study the SAS-MIMO system for when the SAS module is implemented before Low Noise Amplifier (LNA), so-called pre-LNA, under both spatial multiplexing and diversity transmission strategies. The pre-LNA SAS module only consists of passive elements. The optimality of the pre-LNA SAS method is investigated under two di erent practical cases of either the external or internal noise dominates. For the interference channel case, the post-LNA SAS scheme is optimized based on Power Angular Spectrum (PAS) of the received interference signals. The analytical derivations for both noise-limited and interference channels are verified via the computer simulations based on a general Rician statistical MIMO channel model. The simulation results reveal a superiority of the post-LNA SAS to the post-LNA SAS at any condition. Moreover, using the simulations performed for the interference channels we show that the post-LNA SAS is upper bounded by the full-complexity MIMO. Since in both above-mentioned channels, noise-limited and interference, the channel knowledge is needed for the SAS optimization, in this thesis we also propose a two-step channel estimation method for the SAS-MIMO. This channel estimation is based on an Orthogonal Frequency-Division Multiplexing (OFDM) MIMO system. Two di erent estimators of Least-Square (LS) and Minimum-Mean-Square- Error (MMSE) are applied. Simulation results show a superiority of the MMSE method to the LS estimator for a MIMO system simulated under the 802.16 framing strategy. Moreover, a 802.11a framing based SAS-MIMO is simulated using MATLAB SIMULINK to verify the two-step estimation procedure. Furthermore, we also employ a ray-tracing channel simulation to assess di erent SAS configurations, i.e. realized by active (post-LNA) and/or passive (pre-LNA) phased array, in terms of signal coverage. In this regard, a rigorous Signal to Noise Ratio (SNR) analysis is performed for each of these SAS realizations. The results show that although the SAS method performance is generally said to be upperbounded by a full-complexity MIMO, it shows a better signal coverage than the full-complexity MIMO

ASCCC Fractal and Its Application in Antenna Miniaturization

In this chapter, ASCCC fractal is defined. The name “ASCCC” is based on the process that the fractal is built. It is made by adding and subtracting circles to the circumference of a circle. Then the necessary formulas to build up the first and higher orders of ASCCC fractal are derived. By calculating the perimeter of each order, it is shown that the ASCCC fractal has a great capability in antenna miniaturization. Based on first-order ASCCC fractal, a systematic approach is designed to miniaturize an antipodal dipole at any arbitrary frequency. Then the proposed method is applied at band LTE13 (746–787 MHz), which is controversy for mobile antenna, because it causes the size of a common antenna to become very large for a handheld mobile. It is illustrated that not only the ASCCC fractal is successful in miniaturization of dipole antenna, but also it is very good at improving the antenna’s efficiency in comparison with its counterparts like Koch dipole/monopole

Detection of Human papillomavirus 16 and 18 types in oral squamous cell carcinoma patients in Yazd, Iran: A Case-Control Study

         The aim of this study was to ascertain the prevalence of human papillomavirus (HPV) 16/18 in oral squamous cell carcinoma (OSCC) and normal oral mucosa in Iranian individuals with OSCC and their association with various risk factors. The investigation followed a hospital-based case-control design. Cases were individuals with diagnosed OSCC, age- and sex-matched with controls. Sixty-six paraffin embedded tissue samples (39 OSCC and 27normal oral mucosa) were studied. DNA was purified to amplify HPV-DNA using HPV type specific primers-mediated polymerase chain reaction (PCR) method.Mean age was 64.2 ±14 years in cases (range 25-81 years), and 63.5 ±13.5 years in controls (range 22-78 years). Forty-three percent (17/39) of OSCC but none of normal oral mucosa were positive for HPV 16/18 DNA (p = 0.001). The most frequent type in patient group was HPV-16 type. The prevalence rate was high older in age (>50 years) and gender (male) and tongue tissue but no significant association was found (p=0.7, p=0.5 and p=0.42 respectively). We found a significant association of HPV16/18 with oral squamous cell carcinoma. Also, HPV16/18 is a co-factor in oral carcinogenesis. In addition, also it is suggested that HPV is as a risk factor independent of alcohol and tobacco can be effective in creating OSCC.

Attenuation Effect of Cannabinoid Type 1 Receptor Activation on Methamphetamine-Induced Neurodegeneration and Locomotion Impairments among Male Rats

Background: A number of neuroimaging studies on human addicts have revealed that abuse of Methamphetamine (METH) can induce neurodegenerative changes in various brain regions like the cerebral cortex and cerebellum. Although the underlying mechanisms of METH-induced neurotoxicity have been studied, the cellular and molecular mechanisms of METH-induced neurotoxicity remain to be clarified. Previous studies implicated that cannabinoid type 1 receptors (CB1Rs) exert neuroprotective effects on several models of cerebral toxicity, but their role in METH-induced neurotoxicity has been rarely investigated. Moreover, the cerebellum was considered as a potential target to evaluate the effects of cannabinoids on locomotion activity as the CB1Rs are most widely distributed in the molecular layer of cerebellum. Therefore, the present study was carried out to evaluate whether neurodegeneration induced in the cerebellum tissue implicated in locomotion deficit induced by METH.Methods: In the current study, open field test was used to examine locomotor activity. Using hematoxylin and eosin (H&E) staining, morphology of the cerebellar vermis was investigated after repeated exposure to METH. Then, the effects of CB1Rs antagonist [SR17141A, 10 mg/kg, intraperitoneally (IP)] and CB1Rs agonist [WIN55, 212-2 (WIN), 3 mg/kg] against METH-induced neurodegeneration and locomotor deficit were assessed.Findings: The results of the present study demonstrated that repeated exposure to METH increased cerebellar degeneration level as compared to the saline and dimethyl sulfoxide (DMSO) groups. In addition, METH-treated rats showed hyperactivity as compared to the saline and DMSO groups. Pretreatment with WIN significantly attenuated neurodegeneration and hyperactivity induced by METH.Conclusion: The findings of this study provided evidence that CB1Rs may serve as a therapeutic strategy for attenuation of METH-induced locomotor deficits

Intestinal colonization regulates systemic anti-commensal immune sensitivity and hyperreactivity

Healthy host-microbial mutualism with our intestinal microbiota relies to a large degree on compartmentalization and careful regulation of adaptive mucosal and systemic anti-microbial immune responses. However, commensal intestinal bacteria are never exclusively or permanently restricted to the intestinal lumen and regularly reach the systemic circulation. This results in various degrees of commensal bacteremia that needs to be appropriately dealt with by the systemic immune system. While most intestinal commensal bacteria, except for pathobionts or opportunistic pathogen, have evolved to be non-pathogenic, this does not mean that they are non-immunogenic. Mucosal immune adaptation is carefully controlled and regulated to avoid an inflammatory response, but the systemic immune system usually responds differently and more vigorously to systemic bacteremia. Here we show that germ-free mice have increased systemic immune sensitivity and display anti-commensal hyperreactivity in response to the addition of a single defined T helper cell epitope to the outer membrane porin C (OmpC) of a commensal Escherichia coli strain demonstrated by increased E. coli-specific T cell-dependent IgG responses following systemic priming. This increased systemic immune sensitivity was not observed in mice colonized with a defined microbiota at birth indicating that intestinal commensal colonization also regulates systemic, and not only mucosal, anti-commensal responses. The observed increased immunogenicity of the E. coli strain with the modified OmpC protein was not due to a loss of function and associated metabolic changes as a control E. coli strain without OmpC did not display increased immunogenicity

A Unified Multi-Functional Dynamic Spectrum Access Framework: Tutorial, Theory and Multi-GHz Wideband Testbed

Dynamic spectrum access is a must-have ingredient for future sensors that are ideally cognitive. The goal of this paper is a tutorial treatment of wideband cognitive radio and radar—a convergence of (1) algorithms survey, (2) hardware platforms survey, (3) challenges for multi-function (radar/communications) multi-GHz front end, (4) compressed sensing for multi-GHz waveforms—revolutionary A/D, (5) machine learning for cognitive radio/radar, (6) quickest detection, and (7) overlay/underlay cognitive radio waveforms. One focus of this paper is to address the multi-GHz front end, which is the challenge for the next-generation cognitive sensors. The unifying theme of this paper is to spell out the convergence for cognitive radio, radar, and anti-jamming. Moore’s law drives the system functions into digital parts. From a system viewpoint, this paper gives the first comprehensive treatment for the functions and the challenges of this multi-function (wideband) system. This paper brings together the inter-disciplinary knowledge

Dynamic Range Consideration in MIMO Systems with Hybrid Antenna Selection

A Hybrid Antenna Selection (HAS), also called Soft Antenna Selection (SAS), method is basically implemented by a Linear Network (LN) located in RF domain of Multiple Input Multiple Output (MIMO) systems. In this paper, we evaluate the SAS-MIMO system, which is optimally tuned based on spatial multiplexing/diversity transmissions, in terms of receiver dynamic range issue. To this end, an SNR analysis is first performed for a reference point that is the input of Receiver Chain Block (RCB). Different systems are then compared based on a standard receiver, that is, WLAN 802.11 b. A three Dimensional (3D) ray-tracing modeling is applied to assist this evaluation. The simulation results for a case study show that although the optimum post-LNA SAS works like a full-complexity MIMO in the spatial multiplexing/diversity transmission strategies, it provides even a better SNR to the baseband, that is, it reveals a receiver dynamic range improvement

نقش اخلاق و حقوق در قبال اقاله قراردادهای پیمانکاری

Background and Aim: Cancellation is one of the causes of termination of contracts, which also includes contractual agreements focusing on the activities of the employer and the contractor. Given that the conditions, criteria and reasons due to cancellation have legal and ethical consequences, the present study examines the role of ethics and law in relation to the cancellation of contractual agreements. Materials and Methods: The present research is of theoretical type and the method used in it is descriptive-analytical. The required data has been collected through documents and books related to the subject. Ethical Considerations: In organizing the present research, while observing the originality of the texts, honesty and trustworthiness have been observed. Findings: The cancellation of a contract, which leads to its dissolution with the consent of the parties, can be done if it is in the interests of social and governance in order to protect the administrative rights and rights of citizens. In the general terms of the contract, the cancellation is not foreseen, but with regard to the protection of social interests, the employer can cancel the contract so that the contractor cannot claim compensation later, which legally puts the contractors in an unequal position and even obey the orders of employers. In addition, from ethical point of view, arguing for the public interest from employers may lead to government corruption. Conclusion: While in the Iranian legal system, the termination of an administrative contract is justified only on the basis of the principle of public interest; However, the principle of continuity of public service and the principle of respect for the acquired rights of contractors should be provided for in cases where contractors have the right to terminate, because the cancellation of contract is a two-way termination and regardless of the consent and authority of the contractor in dissolving the contract is not accepted morally and legally. The subject of the terms of termination in an administrative contract is mainly contained in Articles 46 and 48 of the General Conditions of the Contract, which are often in the employer's favor and a reason for centralizing authority and providing a ground for corruption in government agencies.   Cite this article as: Pourhosseini K, Ahmadi F, Namdar SH. The Role of Ethics and Law in the Cancellation of Contractual Agreements. Majale "Akhlāq-i zīstī" (i.e., Bioethics Journal). 2021; 11(36): e37.زمینه و هدف: اقاله یکی از اسباب انحلال قراردادها است که قراردادهای پیمانکاری با محوریت فعالیت کارفرما و پیمانکار را نیز دربر می‌گیرد. با توجه به اینکه شرایط، معیارها و اسباب انحلال به سبب اقاله، دارای پیامدهای حقوقی و اخلاقی است، پژوهش حاضر به بررسی نقش اخلاق و حقوق در قبال اقاله قراردادهای پیمانکاری می‌پردازد. مواد و روش‌ها: پژوهش حاضر از نوع نظری و روش مورد استفاده در آن، توصیفی ـ تحلیلی است. داده‌های مورد نیاز از طریق اسناد و کتب مرتبط با موضوع گردآوری شده است. ملاحظات اخلاقی: در انجام پژوهش حاضر، ضمن رعایت اصالت متون، صداقت و امانتداری رعایت شده است. یافته‌ها: اقاله قراداد که منجر به انحلال آن با رضایت و اختیار طرفین می‌شود، در صورتی می‌تواند صورت گیرد که با در نظرگرفتن مصالح اجتماعی و حاکمیتی در جهت حفظ حقوق اداری و حقوق شهروندان باشد. در شرایط عمومی پیمان، اقاله پیش‌بینی نشده است، اما با عنایت به حفظ مصالح اجتماعی، کارفرما می‌تواند قرارداد (پیمان) را اقاله نماید تا پیمانکار بعداً نتواند مطالبه غرامت نماید که این امر از نظر حقوقی، پیمانکاران را در شرایط نابرابر و حتی مطیع دستورات کارفرمایان قرار می‌دهد. از نظر اخلاقی نیز توجیه دفاع از منافع عمومی نزد کارفرمایان ممکن است به فساد دولتی منجر شود. نتیجه‌گیری: در حالی که در نظام حقوقی ایران، فسخ قرارداد اداری صرفاً بر اساس اصل منفعت عمومی توجیه می‌شود، اما بایستی اصل استمرار خدمت عمومی و اصل احترام به حقوق مکتسبه پیمانکاران در مواردی که پیمانکاران حق فسخ دارند، پیش‌بینی شود، زیرا اقاله از نوع فسخ دو طرفی است و بی‌توجهی به رضایت و اختیار پیمانکار در انحلال قرارداد از نظر اخلاقی و حقوقی پذیرفته نیست. موضوع شرایط فسخ قرارداد اداری به طور عمده در مواد 46 و 48 شرایط عمومی پیمان آمده است که غالباً به نفع کارفرما و دلیلی برای متمرکزشدن اختیارات و فراهم‌شدن بستری برای فساد در دستگاه‌های دولتی متولی قراردادها است