Radio resource management for OFDMA systems under practical considerations.

Orthogonal frequency division multiple access (OFDMA) is used on the downlink of broadband wireless access (BWA) networks such as Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE) as it is able to offer substantial advantages such as combating channel impairments and supporting higher data rates. Also, by dynamically allocating subcarriers to users, frequency domain diversity as well as multiuser diversity can be effectively exploited so that performance can be greatly improved. The main focus of this thesis is on the development of practical resource allocation schemes for the OFDMA downlink. Imperfect Channel State Information (CSI), the limited capacity of the dedicated link used for CSI feedback, and the presence of a Connection Admission Control (CAC) unit are issues that are considered in this thesis to develop practical schemes. The design of efficient resource allocation schemes heavily depends on the CSI reported from the users to the transmitter. When the CSI is imperfect, a performance degradation is realized. It is therefore necessary to account for the imperfectness of the CSI when assigning radio resources to users. The first part of this thesis considers resource allocation strategies for OFDMA systems, where the transmitter only knows the statistical knowledge of the CSI (SCSI). The approach used shows that resources can be optimally allocated to achieve a performance that is comparable to that achieved when instantaneous CSI (ICSI) is available. The results presented show that the performance difference between the SCSI and ICSI based resource allocation schemes depends on the number of active users present in the cell, the Quality of Service (QoS) constraint, and the signal-to- noise ratio (SNR) per subcarrier. In practical systems only SCSI or CSI that is correlated to a certain extent with the true channel state can be used to perform resource allocation. An approach to quantifying the performance degradation for both cases is presented for the case where only a discrete number of modulation and coding levels are available for adaptive modulation and coding (AMC). Using the CSI estimates and the channel statistics, the approach can be used to perform resource allocation for both cases. It is shown that when a CAC unit is considered, CSI that is correlated with its present state leads to significantly higher values of the system throughput even under high user mobility. Motivated by the comparison between the correlated and statistical based resource allocation schemes, a strategy is then proposed which leads to a good tradeoff between overhead consumption and fairness as well as throughput when the presence of a CAC unit is considered. In OFDMA networks, the design of efficient CAC schemes also relies on the user CSI. The presence of a CAC unit needs to be considered when designing practical resource allocation schemes for BWA networks that support multiple service classes as it can guarantee fairness amongst them. In this thesis, a novel mechanism for CAC is developed which is based on the user channel gains and the cost of each service. This scheme divides the available bandwidth in accordance with a complete partitioning structure which allocates each service class an amount of non-overlapping bandwidth resource. In summary, the research results presented in this thesis contribute to the development of practical radio resource management schemes for BWA networks

Angiogenic Factor Expression in Hepatic Cirrhosis

The pathogenesis of fibrosis in hepatic cirrhosis remains obscure. This study examines the eventual role of angiogenic factors in the fibrotic process. A series of 55 cirrhotic livers was studied for the proliferation state of fibroblasts, and the expression of vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP) and the basic and acidic fibroblast growth factor (bFGF, aFGF) in both fibroblasts and hepatic cells. The angiogenic and/or fibrogenic factors VEGF, TP, bFGF, and aFGF were clearly expressed in regenerative hepatocytes, but not in fibroblasts of diffuse hepatic fibrosis. The immunohistochemical findings suggest that angiogenic factors and factors promoting oxidative stress (i.e., TP) produced by hepatocytes may contribute to the development of fibrous bands in hepatic cirrhosis

Osteolytic bone destruction resulting from relapse of a testicular tumour 23 years after inguinal orchiectomy and adjuvant chemotherapy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Late relapse of a testicular germ cell tumour is an uncommon occurrence. We report a case of osteolytic bone metastasis appearing 23 years after the initial treatment of a metastatic testicular mixed tumour (choriocarcinoma and embryonal carcinoma). This is one of the longest periods of recurrence reported for testicular germ cell tumours.</p> <p>Case presentation</p> <p>A 52-year-old Caucasian man who underwent a right inguinal orchiectomy due to testicular tumour in 1984 presented to our outpatient clinic in a generally bad condition of health and with severe pain of his right hip joint and os ischii caused by osteolytic metastasis.</p> <p>Conclusions</p> <p>This case emphasizes the need for a life-long follow-up of patients with primary metastatic testicular cancer.</p

Acute appendicitis in preschoolers: a study of two different populations of children

<p>Abstract</p> <p>Objective</p> <p>To assess the incidence and the risk factors implicated in acute appendicitis in preschoolers in our region.</p> <p>Methods</p> <p>Over a 7-year period, 352 children underwent appendectomy for suspected acute appendicitis. Of these, data for 23 children were excluded because no inflammation of the appendix was found on subsequent histology. Of the remaining 329, 82 were ≤ 5 years old (i.e., preschool children) and 247 were 5-14 years old. These two groups of children were further divided according to their religion into Muslims and Christian Orthodox: 43 of the children aged ≤ 5 years were Muslims and 39 were Christian Orthodox. A household questionnaire was designed to collect data concerning age, gender, type of residence area, living conditions, vegetable consumption, and family history of surgery for acute appendicitis as preschool children. The removed appendices were also assessed histologically for the amount of lymphoid tissue.</p> <p>Results</p> <p>Acute appendicitis of preschoolers developed more frequently in Muslims (39.4%) than in Christians (17.7%; <it>p </it>< 0.001). The lack of inside toilet facilities at home, overcrowded living conditions, living in rural areas, and the amount of appendix lymphoid tissue were significantly more frequent among the Muslim preschool children (<it>p </it>< 0.05), while there were no statistically significant differences between Muslim and Christian children with regard to gender, the family history of acute appendicitis, or the vegetable consumption (<it>p </it>> 0.05).</p> <p>Conclusions</p> <p>In our region, the percentage of preschool-aged Muslim children with acute appendicitis was remarkably high. One possible explanation for this finding could be the higher amount of lymphoid tissue in the wall of the appendix in Muslim preschool children together with their low standard of hygiene.</p

Human Papillomavirus in Endometrial Adenocarcinomas: Infectious Agent or a Mere “Passenger”?

Aims. To investigate the possible association of human papillomavirus (HPV) with endometrial hyperplasias and neoplasia. Does HPV play any role in the initiation or prognosis of endometrial adenocarcinomas? Methods. Twenty-five endometrial adenocarcinomas of the endometrioid cell type, with and without squamous differentiation, and twenty-four endometrial hyperplasias of various forms (simple, complex, and atypical) were analyzed for the presence of type 16 and 18 HPV by the polymerase chain reaction (PCR). The results were related to histopathological features of the tumour, and the patients' age, and prognosis. Results. Six of 25 endometrial adenocarcinomas were HPV 16-positive (24%), and 5 of 25 (20%) were HPV 18-positive. Simple endometrial hyperplasias was associated somewhat more commonly with HPV 16 and 18 (2/8 and 1/8 cases, resp.) than hyperplasias progressing to endometrial adenocarcinomas, namely, atypical endometrial hyperplasia (1/8 and 0/8 cases, resp.). None of the positive cases in the series, whether hyperplastic or neoplastic, demonstrated cytological evidence of HPV infection. There was no relation between HPV-positive cases and squamous differentiation, depth of myometrial invasion, lymphatic involvement, lymphocytic response, patients' age, or prognosis. Conclusion. It appears that the presence of HPV in the endometrium, as detected by PCR, does not play any role in the initiation or prognosis of endometrial adenocarcinoma

Omental infarction in an obese 10-year-old boy

Primary omental infarction (POI) has a low incidence worldwide, with most cases occurring in adults. This condition is rarely considered in the differential diagnosis of acute abdominal pain in childhood. Herein, we present a case of omental infarction in an obese 10-year-old boy who presented with acute abdominal pain in the right lower abdomen. The ultrasound (US) examination did not reveal the appendix but showed secondary signs suggesting acute appendicitis. The child was thus operated on under the preoperative diagnosis of acute appendicitis but the intra-operative finding was omental infarct. Since the omental infarct as etiology of acute abdominal pain is uncommon, we highlight some of the possible etiologies and emphasize the importance of accurate diagnosis and appropriate treatment of omental infarction

Clear cell sarcoma of the scapula. A case report and review of the literature

BACKGROUND: Clear cell sarcoma of tendons and aponeuroses (CCSTA) appears usually in the extremities and rarely in the trunk. CASE PRESENTATION: We present an unusual case of CCSTA overlying the scapular region and with secondary osseous extension in the lower scapula. The patient underwent a wide local excision with removal of the tumor and the lower two thirds of the scapula. He had no local recurrences but he developed lung metastases after 5 months in spite of postoperative chemotherapy. He finally died ten months later. CONCLUSION: The patients with CCSTA have a variable unpredictable course. Despite treatment the overall prognosis is poor

A Case Report of Urinary Bladder Carcinosarcoma and Review of the Literature

Carcinosarcoma of the bladder is an unusual tumour characterized by a combination of malignant epithelial and soft tissue elements. Most of the reported cases have been case reports or small series. Optimal treatment is uncertain. We herein report our experience in such a case treated with transurethral resection followed by radiotherapy with adverse final outcome. Treatment of bladder carcinosarcomas should be aggressive and multimodal but optional treatment is still unknown. Radiotherapy alone is insufficient as a treatment option of these aggressive tumors

Pyruvate Dehydrogenase and Pyruvate Dehydrogenase Kinase Expression in Non Small Cell Lung Cancer and Tumor-Associated Stroma

AbstractPyruvate dehydrogenase (PDH) catalyzes the conversion of pyruvate to acetyl-coenzyme A, which enters into the Krebs cycle, providing adenosine triphosphate (ATP) to the cell. PDH activity is under the control of pyruvate dehydrogenase kinases (PDKs). Under hypoxic conditions, conversion of pyruvate to lactate occurs, a reaction catalyzed by lactate dehydrogenase 5 (LDH5). In cancer cells, however, pyruvate is transformed to lactate occurs, regardless of the presence of oxygen (aerobic glycolysis/Warburg effect). Although hypoxic intratumoral conditions account for HIFia stabilization and induction of anaerobic metabolism, recent data suggest that high pyruvate concentrations also result in HIFia stabilization independently of hypoxia. In the present immunohistochemical study, we provide evidence that the PDH/PDK pathway is repressed in 73% of non small cell lung carcinomas, which may be a key reason for HIFia stabilization and “aerobic glycolysis.” However, about half of PDHdeficient carcinomas are not able to switch on the HIF pathway, and patients harboring these tumors have an excellent postoperative outcome. A small subgroup of clinically aggressive tumors maintains a coherent PDH and HIF/LDH5 expression. In contrast to cancer cells, fibroblasts in the tumor-supporting stroma exhibit an intense PDH but reduced PDK1 expression favoring maximum PDH activity. This means that stroma may use lactic acid produced by tumor cells, preventing the creation of an intolerable intratumoral acidic environment at the same time

Upregulated hypoxia inducible factor-1α and -2α pathway in rheumatoid arthritis and osteoarthritis

The pathogenesis of rheumatoid arthritis (RA) and osteoarthritis (OA) remains obscure, although angiogenesis appears to play an important role. We recently confirmed an overexpression of two angiogenic factors, namely vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF), by the lining and stromal cells of the synovium in both conditions. Because hypoxia inducible factor (HIF)-1α and HIF-2α are essential in regulating transcription of the VEGF gene, active participation of HIF-α molecules in the pathogenesis of these arthritides is anticipated. We investigated the immunohistochemical expression of HIF-1α and HIF-2α in the synovium of 22 patients with RA, 34 patients with OA and 22 'normal' nonarthritic individuals, in relation to VEGF, VEGF/KDR (kinase insert domain protein receptor) vascular activation, PD-ECGF and bcl-2. A significant cytoplasmic and nuclear overexpression of HIF-1α and HIF-2α was noted in the synovial lining and stromal cells of both diseases relative to normal. Overexpression of HIF-αs was related to high microvessel density, high PD-ECGF expression and high VEGF/KDR receptor activation, suggesting HIF-α-dependent synovial angiogenesis in OA. By contrast, the activation of the angiogenic VEGF/KDR pathway was persistently increased in RA, as indeed was microvessel density and the expression of PD-ECGF, irrespective of the extent of HIF-α expression, indicating a cytokine-dependent angiogenesis. In all cases, the VEGF/KDR vascular activation was significantly lower in OA than in RA, suggesting a relative failure of the HIF-α pathway to effectively produce a viable vasculature for OA, which is consistent with the degenerative nature of the disease. The activation of the HIF-α pathway occurs in both RA and OA, although for unrelated reasons