Optimal Power Allocation for Channel Estimation in MIMO-OFDM System with Per-Subcarrier Transmit Antenna Selection

A novel hybrid channel estimator is proposed for multiple-input multiple-output orthogonal frequency- division multiplexing (MIMO-OFDM) system with per-subcarrier transmit antenna selection having optimal power allocation among subcarriers. In practice, antenna selection information is transmitted through a binary symmetric control channel with a crossover probability. Linear minimum mean-square error (LMMSE) technique is optimal technique for channel estimation in MIMO-OFDM system. Though LMMSE estimator performs well at low signal to noise ratio (SNR), in the presence of antenna-to-subcarrier-assignment error (ATSA), it introduces irreducible error at high SNR. We have proved that relaxed MMSE (RMMSE) estimator overcomes the performance degradation at high SNR. The proposed hybrid estimator combines the benefits of LMMSE at low SNR and RMMSE estimator at high SNR. The vector mean square error (MSE) expression is modified as scalar expression so that an optimal power allocation can be performed. The convex optimization problem is formulated and solved to allocate optimal power to subcarriers minimizing the MSE, subject to transmit sum power constraint. Further, an analytical expression for SNR threshold at which the hybrid estimator is to be switched from LMMSE to RMMSE is derived. The simulation results show that the proposed hybrid estimator gives robust performance, irrespective of ATSA error

Alternate Servers with Set up Times

The paper analyzes a queueing model consisting of a single queue serviced by two servers alternately. A change over time is required when one server is replaced by another. In a busy period, only one server is servicing and when it empties the queue, the second server takes over and thus the two servers work alternately. The actual service after the change over time of the particular server under operation

Immunology of occupational lung diseases caused by dust: an overview

The lungs are exposed to numerous injurious substances.Such injury may be the result of immunological or non-immunological mechanisms. The lung clears itself of inhaled particles by means of ciliated cells lining the airways and the macrophages.The latter play an important role in the immune process as well.Inorganic particles are ingested by macrophages and if found inert are transported for eventual expulsion.Particles such as silica are poorly handled by macrophages, they not only damage the macrophages but also impair their function. Others, such as asbestos, may stimulate fibrosis. Endogenous factors such as the presence of auto-antibodies (rheumatoid factor or anti-nuclear factor) alter the response of the host to inhaled particles.The pathological changes caused by handling inorganic dusts include intestitial fibrosis, nodular fibrosis or macule formation leading to emphysema.Occupational asthma a occurs when individuals are exposed to dusts during the course of their work. The lung responds differently to organic dust. T cells and complement are important elements in handling organic dust.The role of inhaled steroids which have no significant systemic effects in the prevention of certain occupational asthmas is worth evaluating, apart from control measures which minimise the exposure

Etiologic diagnosis of pleural effusion by punch biopsy of the parietal pleura

Needle biopsy of the pleura using Harefield pleural biopsy punch, has been performed in 100 subjects, 58 of whom were 40 years of age or over, in order to arrive at a histologic diagnosis. Ancillary investigations such as bronchoscopy and lymph node biopsy have been done where necessary and feasible. In 18 of the 58 in the older age group and in 15 of the 42 in the younger age group, the biopsy showed lesions suggestive of tuberculous infection; 13 in the older age group and two in the other showed evidence of malignancy; 23 in the older and 21 in the younger group showed nonspecific changes. Vegetative forms of Entamoeba histolytica were demonstrated in the biopsy material in one case. Biopsy, performed on one occasion only was a failure in five cases. No untoward effects were noticed as a consequence of the procedure

Urticaria - some observations

Urticaria has been known from antiquity. The disorder was known to the Arabs as essera and it has found a place in the writings of Cesius (circa 30 BC–45 AD). Although the condition was recognised as an entity, its cause was a mystery to the physicians of those times. It was initially thought to be a manifestation of idiosyncrasy and later believed to be a form of neuroses. However, now the pathophysiological basis of urticaria is well understood. The development of antihistamine group of drugs, paved the way for the management of urticaria

Evaluation of Heavy- and Medium-Duty On-Road Vehicle Emissions in California\u27s South Coast Air Basin

Emission measurements were collected from heavy-duty (HDVs) and medium-duty vehicles (MDVs) at the Peralta weigh station long-term measurement site near Anaheim, CA in 2017. Two Fuel Efficiency Automobile Test units sampled elevated and ground-level exhaust vehicles totaling 2,315 measurements. HDVs (1844 measurements) exhibited historical reductions in fuel specific oxides of nitrogen (NOx) from the 2008 measurements (55%) with increased use of exhaust gas recirculation and selective catalytic reduction systems. However, as these technologies have aged, the in-use benefits have declined. Infrared %opacity measurements of tailpipe soot decreased 14% since 2012 with increased diesel particulate filter (DPF) use, DPF longevity and fleet turnover. 63% of the HDV fleet in 2017 was chassis model year 2011+ compared to only 12% in 2012. The observed MDV fleet (471 measurements) was 1.4 years older than the HDV fleet with average NOx 14% higher. A significant reduction in MDV NOx occurred approximately 2 model years prior to similar HDV reductions (2014 versus 2016 chassis model year). MDV chassis model years 2014+ were able to meet their corresponding NOx laboratory certification standards in-use, whereas HDVs remain slightly above this threshold. Similar MDV NOx emission trends were also observed in data previously collected in Chicago, IL

Cell-mediated immunity in chyluria

Cellular immune response to mitogens phytohemaggluthin (PHA) and poke weed mitogen (PWM) was assessed in 13 patients with chyluria and 32 healthy controls. The mean stimulation Index of the patient group was significantly lower than the control group. The degree of depression was neither related to the duration of excretion of chyle nor to the microfilaraemic status

Nuclear oxidation in flavones and related compounds Part XXIV. Synthesis of myristicin and elemicin

This article does not have an abstract

Targeting Pancreatic Ductal Adenocarcinoma Acidic Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in the USA, accounting for ~40,000 deaths annually. The dismal prognosis for PDAC is largely due to its late diagnosis. Currently, the most sensitive diagnosis of PDAC requires invasive procedures, such as endoscopic ultrasonography, which has inherent risks and accuracy that is highly operator dependent. Here we took advantage of a general characteristic of solid tumors, the acidic microenvironment that is generated as a by-product of metabolism, to develop a novel approach of using pH (Low) Insertion Peptides (pHLIPs) for imaging of PDAC. We show that fluorescently labeled pHLIPs can localize and specifically detect PDAC in human xenografts as well as PDAC and PanIN lesions in genetically engineered mouse models. This novel approach may improve detection, differential diagnosis and staging of PDAC