Onboard multichannel demultiplexer/demodulator

An investigation performed for NASA LeRC by COMSAT Labs, of a digitally implemented on-board demultiplexer/demodulator able to process a mix of uplink carriers of differing bandwidths and center frequencies and programmable in orbit to accommodate variations in traffic flow is reported. The processor accepts high speed samples of the signal carried in a wideband satellite transponder channel, processes these as a composite to determine the signal spectrum, filters the result into individual channels that carry modulated carriers and demodulate these to recover their digital baseband content. The processor is implemented by using forward and inverse pipeline Fast Fourier Transformation techniques. The recovered carriers are then demodulated using a single digitally implemented demodulator that processes all of the modulated carriers. The effort has determined the feasibility of the concept with multiple TDMA carriers, identified critical path technologies, and assessed the potential of developing these technologies to a level capable of supporting a practical, cost effective on-board implementation. The result is a flexible, high speed, digitally implemented Fast Fourier Transform (FFT) bulk demultiplexer/demodulator

Working and organizing in the age of the learning algorithm

Learning algorithms, technologies that generate responses, classifications, or dynamic predictions that resemble those of a knowledge worker, raise important research questions for organizational scholars related to work and organizing. We suggest that such algorithms are distinguished by four consequential aspects: black-boxed performance, comprehensive digitization, anticipatory quantification, and hidden politics. These aspects are likely to alter work and organizing in qualitatively different ways beyond simply signaling an acceleration of long-term technology trends. Our analysis indicates that learning algorithms will transform expertise in organizations, reshape work and occupational boundaries, and offer novel forms of coordination and control. Thus, learning algorithms can be considered performative due to the extent to which their use can shape and alter work and organizational realities. Their rapid deployment requires scholarly attention to societal issues such as the extent to which the algorithm is authorized to make decisions, the need to incorporate morality in the technology, and their digital iron-cage potential

Fungal infections in renal transplant patients

Organ transplantation has always been considered to be the standard therapeutic interventions in patients with end-stage organ failure. In 2008, more than 29,000 organ transplants were performed in US. Survival rates among transplant recipients have greatly improved due to better understanding of transplant biology and more effective immunosuppressive agents. After transplant, the extent of the immune response is influenced by the amount of interleukin 2 (IL-2) being produced by the T-helper cells. Transplant immunosuppressive therapy primarily targets T cell-mediated graft rejection. Calcineurin inhibitor, which includes cyclosporine, pimecrolimus and tacrolimus, impairs calcineurin-induced up-regulation of IL-2 expression, resulting in increased susceptibility to invasive fungal diseases. This immunosuppressive state allows infectious complication, leading to a high mortality rate. Currently, overall mortality due to invasive fungal infections (IFIs) in solid organ transplant recipients ranges between 25% and 80%. The risk of IFI following renal transplant is associated with the dosage of immunosuppressive agents given, environmental factors and post-transplant duration. Most fungal infections occur in the first 6 months after transplant because of the use of numerous immunosuppressors. Candida spp. and Cryptococcus spp. are the yeasts most frequently isolated, while most frequent filamentous fungi (molds) isolated are Aspergillus spp. The symptoms of systemic fungal infections are non-specific and early detection of fungal infections and proper therapy are important in improving survival and reducing mortality. This article will provide an insight on the risk factors and clinical presentation, compare variation in treatment of IFIs in renal transplant patients, and evaluate the role of prophylactic therapy in this group of patients. We also report the course and management of two renal transplant recipients admitted to Staten Island University Hospital, both of whom developed pulmonary complications secondary to Aspergillus infection

On-board demux/demod

To make satellite channels cost competitive with optical cables, the use of small, inexpensive earth stations with reduced antenna size and high powered amplifier (HPA) power will be needed. This will necessitate the use of high e.i.r.p. and gain-to-noise temperature ratio (G/T) multibeam satellites. For a multibeam satellite, onboard switching is required in order to maintain the needed connectivity between beams. This switching function can be realized by either an receive frequency (RF) or a baseband unit. The baseband switching approach has the additional advantage of decoupling the up-link and down-link, thus enabling rate and format conversion as well as improving the link performance. A baseband switching satellite requires the demultiplexing and demodulation of the up-link carriers before they can be switched to their assigned down-link beams. Principles of operation, design and implementation issues of such an onboard demultiplexer/demodulator (bulk demodulator) that was recently built at COMSAT Labs. are discussed

Treatment of Hydrothermal-Liquefaction Wastewater with Crossflow UF for Oil and Particle Removal

This study aims to evaluate the application of ceramic ultrafiltration membranes in the crossflow mode for the separation of particles and oil in water emulsions (free oil droplets and micelles) from hydrothermal-liquefaction wastewater (HTL-WW) from the hydrothermal liquefaction of municipal sewage sludge. The experiments were carried out using one-channel TiO$_{2}$ membranes with pore sizes of 30, 10 and 5 nm. The results showed that the highest stable permeability could be achieved with a membrane-pore size of 10 nm, which experienced less fouling, especially through pore blockage, in comparison to the two other pore sizes. Instead of observing an increase in the permeability, the application of a higher feed temperature as well as backwash cycles led to a clear increase in irreversible fouling due to the presence of surfactants in the HTL-WW. Among several physical and chemical cleaning methods, alkaline cleaning at pH 12 proved to be the most efficient in removing fouling and maintaining stable performance on a long-term basis. Ceramic-membrane ultrafiltration can be considered as an adequate first-stage treatment of real HTL wastewater

IgA-dominant post-infectious glomerulonephritis presenting as a fatal pulmonary-renal syndrome

Over the last decades, post-infectious glomerulonephritis underwent major changes in its epidemiology, pathophysiology, and outcomes. We are reporting a case of IgA-dominant post-infectious glomerulonephritis (IgA-PIGN) presenting as a fatal pulmonary-renal syndrome. An 86-year-old Filipino man presented with worsening dyspnea, hemoptysis, and decreased urine output over 2 weeks. Past medical history is significant for hypertension, chronic kidney disease stage III, and pneumonia 3 weeks prior treated with intravenous cefazolin for methicillin-sensitive Staphylococcus aureus bacteremia. Physical examination was remarkable for heart rate of 109/min and respiratory rate of 25/min saturating 99% on 3 liters via nasal cannula. There were bibasilar rales in the lungs and bilateral ankle edema. A chest radiograph showed bibasilar opacifications. Blood work was significant for hemoglobin of 8.3 g/dL and creatinine of 9.2 mg/dL (baseline of 1.67). TTE showed EF 55%. Urinalysis revealed large blood and red blood cell casts. Kidney ultrasound showed bilateral echogenicity compatible with renal disease. Pulse methylprednisolone therapy and hemodialysis were initiated with patient\u27s condition precluding kidney biopsy. Serology workup for rapidly progressive glomerulonephritis was negative. On day 7, the patient required mechanical ventilation; bronchoscopy showed alveolar hemorrhage and plasmapheresis was initiated. Renal biopsy revealed IgA-PIGN with endocapillary and focal extracapillary proliferative and exudative features. IgA-PIGN occurs in diabetic elderly (mean age of 60 years), 0-16 weeks after an infection mainly by Staphylococcus. However, this nondiabetic patient had normal complement IgA-PIGN with fatal pulmonary-renal syndrome. Understanding the pathogenesis and identifying the nephrotoxic bacteria species and the aberrant IgA molecule will open new insights toward prevention and treatment

Surface Defect incorporated Diamond Machining of Silicon

This paper reports the performance enhancement benefits in diamond turning of the silicon wafer by incorporation of the Surface Defect Machining (SDM) method. The hybrid micromachining methods usually require additional hardware to leverage the added advantage of hybrid technologies such as laser heating, cryogenic cooling, electric pulse or ultrasonic elliptical vibration. The SDM method tested in this paper does not require any such additional baggage and is easy to implement in a sequential micro-machining mode. This paper made use of Raman spectroscopy data, average surface roughness data and imaging data of the cutting chips of silicon for drawing a comparison between conventional Single Point Diamond Turning (SPDT) and SDM while incorporating surface defects in the (i) circumferential and (ii) radial directions. Complimentary 3D Finite Element Analysis (FEA) was performed to analyse the cutting forces and the evolution of residual stress on the machined wafer. It was found that the surface defects generated in the circumferential direction with an interspacing of 1 mm revealed the lowest average surface roughness (Ra) of 3.2 nm as opposed to 8 nm Ra obtained through conventional SPDT using the same cutting parameters. The observation of the Raman spectroscopy performed on the cutting chips showed remnants of phase transformation during the micromachining process in all cases. FEA was used to extract quantifiable information about the residual stress as well as the sub-surface integrity and it was discovered that the grooves made in the circumferential direction gave the best machining performance. The information being reported here is expected to provide an avalanche of opportunities in the SPDT area for low-cost machining solution for a range of other nominal hard, brittle materials such as SiC, ZnSe and GaAs as well as hard steels

Effect of a pedometer-based walking challenge on increasing physical activity levels amongst hospital workers

Background: More than 50% of Qatari adults are physically inactive. The workplace is an excellent environment to implement cost-effective, efficient behavioural physical activity (PA) interventions to increase PA. This study evaluated whether a pedometer-based walking challenge would increase PA levels amongst hospital workers. Methods: A pedometer-based workplace walking intervention was implemented in April-August 2017. Amongst 800 recruited full-Time hospital workers, a cross-sectional sample of 212 workers completed the online questionnaires Quality of Life Questionnaire, International Physical Activity Questionnaire (IPAQ), and Workforce Sitting Questionnaire. A sub-sample of participants (n = 54) wore a pedometer for 3 months. They recorded their daily step count through an online web platform linked to the pedometer. Another cross-sectional sample (n = 194) in the same target population completed online questionnaires at post intervention. Results: The IPAQ assessed physical activity at post-intervention was higher compared to pre-intervention. In a sub-sample (n = 54) that provided pedometer data, workers' step count during intervention was significantly higher (9270) from pre-intervention (7890) (p = 0.048). Conclusions: Although self-reported PA was higher post-intervention, the subsample showed objectively assessed physical activity did not exceed the threshold recommended for optimal health. Therefore, encouraging participation and maintaining motivation amongst workers in a work-based PA programme is challenging. - 2019 The Author(s).The publication of this article was funded by the Qatar National Library. We would like to acknowledge, Mr. Manaf Kamil, Application Architect in assisting us to extract pedometer data for analysis. Also we would like to thank Mr. Christopher Mengelt, Director of planning and performance for his assistance in dissemination of e-surveys. Finally, we are grateful to Dr. Nathan Riding for English language editing