A MIMO-OFDM testbed, channel measurements, and system considerations for outdoor-indoor WiMAX

The design, implementation, and test of a real-time flexible 2×2 (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter) CDIT capacity is close to (Channel State Information at the Transmitter) CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array) FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements

On the diversity and complexity of Zero Forcing receivers for MIMO Zero Padded systems

Zero padded systems with linear receivers are shown to be robust and amenable to fast implementations in single antenna scenarios. In this paper, properties of such systems are investigated when multiple antennas are present at both ends of the communication link. In particular, their diversity and complexity are evaluated for precoded transmissions. The linear receivers are shown to exploit multipath and receive diversities, even in the absence of any coding at the transmitter. Use of additional redundancy to improve performance is considered and the effect of transmission rate on diversity order is analyzed. Low complexity implementations of Zero Forcing receivers are devised to further enhance their applicability

The right sided syndrome, congenital absence of kidney and testis

Unilateral renal agenesis (URA) is a developmental defect associated with ano-malies of the genitourinary system. The associations vary from absence of testis alone to high anorectal anomalies in other patients. We present two interesting patients with URA, encountered recently. Our first case was diagnosed with URA at the age of 11 years, which was detected on sonography, when he presented with pain abdomen. The presence of an epididymal cyst masked the absence of ipsilateral testes leading to delay in the diagnosis. Our second case was diagnosed with URA during the neonatal period when he presented with anorectal agenesis. He underwent abdomino-anal pull-through operation and later clinical course was complicated by recurrent cystitis, secondary vesicoureteral reflux and hydroureteronephrosis of solitary kidney, progressing to chronic kidney disease

Cleistanthus collinus poisoning: experience at a medical intensive care unit in a tertiary care hospital in south India

Background & objectives: Ingestion of Cleistanthus collinus causes hypokalemia and cardiac arrhythmias leading to mortality in most cases. We undertook this retrospective study to evaluate the clinical presentation and predictors of outcome in critically ill patients admitted with C. collinus poisoning. Methods: The case records of 56 patients admitted to the medical intensive care unit (MICU) of a tertiary care teaching hospital in south India (2000-2014) with C. collinus poisoning were retrospectively analysed. Results: The mean age of patients was 36.7±13.3 yr; there were 30 males. Salient clinical manifestations included hypokalemia (58%), neutrophilic leucocytosis (48.2%), acute kidney injury (AKI) (42.9%), acute respiratory failure requiring mechanical ventilation (AcRFMv) (32.1%), shock (21.4%); cardiac arrhythmias and neuromuscular weakness (19.6% each); 21 patients (37.5%) had adverse outcome. Longer time-lapsed from consumption to reaching emergency room [median (interquartile range)] (hours) [49 (22-97) vs. 28 (7-56), p =0.0380 ]; higher acute physiology and chronic health evaluation II (APACHE II) score at presentation [14 (8.25-14.75) vs. 2 (0-6) P<0.001]; and presence of the following [odds ratio (95% confidence intervals)] at initial presentation: shock [37.40 (4.29-325.98), P=0.001]; AcRFMv [26.67 (5.86-121.39), P<0.001]; elevated alanine aminotransferase [5.71 (1.30-25.03), p0 =0.021]; metabolic acidosis [5.48 (1.68-17.89), P=0.005]; acute kidney injury (AKI) [5 (1.55-16.06), P=0.007]; hyponatremia [4.67 (1.25-17.44), P=0.022]; and neutrophilic leucocytosis [3.80 (1.02-14.21), P=0.047] predicted death. A significant (P<0.001) increasing trend in mortality was observed with increasing International Program on Chemical Safety Poisoning Severity Score (IPCS-CSS) grade. Interpretation & conclusions: C. collinus is a lethal poison associated with high mortality for which there is no specific antidote. Careful search and meticulous monitoring of the predictors of death and initiating appropriate corrective measures can be life saving

Derivation & validation of glycosylated haemoglobin (HbA 1c ) cut-off value as a diagnostic test for type 2 diabetes in south Indian population

Background & Objectives: Glycosylated haemoglobin (HbA 1c ) has been in use for more than a decade, as a diagnostic test for type 2 diabetes. Validity of HbA 1c needs to be established in the ethnic population in which it is intended to be used. The objective of this study was to derive and validate a HbA 1c cut-off value for the diagnosis of type 2 diabetes in the ethnic population of Rayalaseema area of south India. Methods: In this cross-sectional study, consecutive patients suspected to have type 2 diabetes underwent fasting plasma glucose (FPG) and 2 h post-load plasma glucose (2 h-PG) measurements after a 75 g glucose load and HbA 1c estimation. They were classified as having diabetes as per the American Diabetes Association criteria [(FPG ≥7 mmol/l (≥126 mg/dl) and/or 2 h-PG ≥11.1 mmol/l (≥200 mg/dl)]. In the training data set (n = 342), optimum cut-off value of HbA 1c for defining type 2 diabetes was derived by receiver-operator characteristic (ROC) curve method using oral glucose tolerance test results as gold standard. This cut-off was validated in a validation data set (n = 341). Results: On applying HbA 1c cut-off value of >6.3 per cent (45 mmol/mol) to the training data set,sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for diagnosing type 2 diabetes were calculated to be 90.6, 85.2, 80.8 and 93.0 per cent, respectively. When the same cut-off value was applied to the validation data set, sensitivity, specificity, PPV and NPV were 88.8 , 81.9, 74.0 and 92.7 per cent, respectively, although the latter were consistently smaller than the proportions for the training data set, the differences being not significant. Interpretation & conclusions: HbA 1c >6.3 per cent (45 mmol/mol) appears to be the optimal cut-off value for the diagnosis of type 2 diabetes applicable to the ethnic population of Rayalaseema area of Andhra Pradesh state in south India