Performance Analysis of Physical Layer Network Coding for Two-way Relaying over Non-regenerative Communication Satellites

Two-way relaying is one of the major applications of broadband communication satellites, for which an efficient technique is Physical Layer Network Coding (PLNC). Earlier studies have considered satellites employing PLNC with onboard processing. This paper investigates the performance of PLNC over non-regenerative satellites, as a majority of the operational and planned satellites have no onboard processing. Assuming that the channel magnitudes of the two users are equal, two operating conditions are considered with uncoded-QPSK relaying. In the first condition, both users are completely synchronized in phase and transmit power, and in the second condition, phase is not synchronized. The peak power constraint imposed by the satellite amplifier is considered and the error performance bounds are derived for both the conditions. The simulation results for end-to-end Bit Error Rate (BER) and throughput are provided. These results shall enable communication system designers to decide system parameters like power and linearity, and perform tradeoff analysis between different relaying schemes.Comment: 9 pages and 13 figure

Wireless Bidirectional Relaying using Physical Layer Network Coding with Heterogeneous PSK Modulation

In bidirectional relaying using Physical Layer Network Coding (PLNC), it is generally assumed that users employ same modulation schemes in the Multiple Access phase. However, as observed by Zhang et al., it may not be desirable for the users to always use the same modulation schemes, particularly when user-relay channels are not equally strong. Such a scheme is called Heterogeneous PLNC. However, the approach in [1] uses the computationally intensive Closest Neighbour Clustering (CNC) algorithm to find the network coding maps to be applied at the relay. Also, the treatment is specific to certain cases of heterogeneous modulations. In this paper, we show that, when users employ heterogeneous but symmetric PSK modulations, the network coding maps and the mapping regions in the fade state plane can be obtained analytically. Performance results are provided in terms of Relay Error Rate (RER) and Bit Error Rate (BER).Comment: 10 pages, 10 figures and 3 table

True infliximab resistance in rheumatoid arthritis: a role for lymphotoxin α?

Background: The combination of methotrexate and the anti-tumour necrosis factor (TNF) antibody infliximab is a very effective treatment for rheumatoid arthritis (RA). However, a proportion of patients are not responsive to this treatment. Inefficacy may represent a TNF independent disease or insufficient drug at the site of action. Case report: A patient with RA resistant to repeated high dose infliximab infusions and intra-articular infliximab into an inflamed knee is described. No beneficial clinical effect was observed. Pre-injection arthroscopic biopsy of the study knee demonstrated TNF staining but also confirmed the presence of lymphotoxin (LT or TNFß) on immunohistochemistry. Subsequent treatment with etanercept (which blocks LT as well as TNF) resulted in clinical remission of disease. Conclusion: This case suggests that resistance to TNF blockade may occur when TNF is not the dominant inflammatory cytokine and suggests that LT may have a pathogenic role in RA

Implementing and Characterizing Real-time Broadband RFI Excision for the GMRT Wideband Backend

The Giant Metrewave Radio Telescope (GMRT) is being upgraded to increase the receiver sensitivity. This makes the receiver more susceptible to man-made Radio Frequency Interference (RFI). To improve the receiver performance in presence of RFI, real-time RFI excision (filtering) is incorporated in the GMRT wideband backend (GWB). The RFI filtering system is implemented on FPGA and CPU-GPU platforms to detect and remove broadband and narrowband RFI. The RFI is detected using a threshold-based technique where the threshold is computed using Median Absolute Deviation (MAD) estimator. The filtering is carried out by replacing the RFI samples by either noise samples or constant value or threshold. This paper describes the status of the real-time broadband RFI excision system in the wideband receiver chain of the upgraded GMRT (uGMRT). The test methodology for carrying out various tests to demonstrate the performance of broadband RFI excision at the system level and on radio astronomical imaging experiments are also described.Comment: 7 pages, 7 figure

Making Care Work: Sustaining Personhood and Reproducing Inequality in Home Care of Older Adults in Chicago, IL.

This dissertation explores the ways that everyday paid home care of older adults in Chicago, IL reproduces social inequality in the process of making and unmaking independent persons. Integrating theory and methods from social work and anthropology, this dissertation is based on ethnographic research conducted between 2006 and 2008 with supervisors, home care workers, older adults and family members associated with one publicly-funded and one privately-funded home care agency. The dissertation highlights the ways social policy and agency practices intersect with people’s meanings and experiences of home care. Older adults experienced home care as a liminal practice through which the invasion of bureaucratic and corporate ethics into their domestic lives was seen as threatening their independence and personhood. By participating in risky gift exchanges, workers and older adults restored expected domestic relations and positioned one another as moral subjects. Home care workers labored to sustain older adults’ social relations and independence even as the structural conditions of this labor threatened their ability to support their families. Workers sustained older adults’ independence and personhood by a process I call phenomenological empathy, that is, sensing, imagining and incorporating older adults’ lifetimes of embodied tastes into everyday care practices, all the while suppressing their own. Given the political-economic structures of both private and public home care in the United States, the capacity of workers to sustain older adults as visibly independent persons was actually facilitated by their own social marginality, even invisibility, as predominantly poor women of color or of immigrant status. Paradoxically, the invisibility of care work and home care workers makes possible the reproduction of recognizably autonomous persons, while reproducing social stratification in the process. Disrupting the reproduction of inequality that attends home care work requires public investments that improve the structural position of workers and broader public consideration of the social supports that independence and individualism actually require in practice. The study of paid care thus offers a critical perspective on how some kinds of persons come to be valued, made, reproduced and sustained over others and policies and practices through which these processes might be made more equitable.Ph.D.Social Work and AnthropologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/78817/1/ebuch_1.pd

Perception gaps between patients with ulcerative colitis and healthcare professionals: An online survey

Background: The purpose of this study was to examine the differing perspectives and perceptual gaps relating to ulcerative colitis (UC) symptoms and their management between patients and healthcare professionals (HCPs). Methods: Structured, cross-sectional, Web-based questionnaires designed to assess a variety of disease indices were completed by adult patients with UC and HCPs involved in the care of patients with UC from Canada, France, Germany, Ireland, Spain, and the United Kingdom. Results: Surveys were completed by 775 patients, 475 physicians, and 50 nurses. Patient self-reported classification of disease severity revealed generally greater severity (mild, 32%; moderate, 53%) compared with physician and nurse estimates of UC severity among their caseloads (mild, 52% and 49%; moderate, 34% and 37%, respectively). Patients reported that an average of 5.5 (standard deviation, 11.0) flares (self-defined) occurred over the past year, compared with 3.4 and 3.8 flares per year estimated by physicians and nurses. Perceived flare triggers differed between patients (stress ranked first) and HCPs (natural disease course ranked first). Fifty-five percent of patients stated that UC symptoms over the past year had affected their quality of life, while physicians and nurses estimated that 35% to 37% of patients would have a reduced quality of life over the same period. Patients ranked urgency and pain as the most bothersome symptoms, while physicians and nurses ranked urgency and stool frequency highest. About half of patients (47%) defined remission as experiencing no symptoms; by comparison, 62% to 63% of HCPs defined remission as requiring the complete absence of symptoms. HCPs (doctors/nurses in general practice and/or hospital) were regarded by patients as their main source of UC information by 72%; however, 59% reported not arranging regular visits to see their HCPs. Conclusions: This large survey identified important differences between patients' and HCPs' perceptions of the impact of UC symptoms on patients' lives. Notably, HCPs may underestimate the effect of specific UC symptoms on patients and may fail to recognize issues that are important to patients. © 2015, In House Publications. All rights reserved

Bypass of DNA interstrand crosslinks by a Rev1-DNA polymerase ζ complex

DNA polymerase ζ (Pol ζ) and Rev1 are essential for the repair of DNA interstrand crosslink (ICL) damage. We have used yeast DNA polymerases η, ζ and Rev1 to study translesion synthesis (TLS) past a nitrogen mustard-based interstrand crosslink (ICL) with an 8-atom linker between the crosslinked bases. The Rev1-Pol ζ complex was most efficient in complete bypass synthesis, by 2-3 fold, compared to Pol ζ alone or Pol η. Rev1 protein, but not its catalytic activity, was required for efficient TLS. A dCMP residue was faithfully inserted across the ICL-G by Pol η, Pol ζ, and Rev1-Pol ζ. Rev1-Pol ζ, and particularly Pol ζ alone showed a tendency to stall before the ICL, whereas Pol η stalled just after insertion across the ICL. The stalling of Pol η directly past the ICL is attributed to its autoinhibitory activity, caused by elongation of the short ICL-unhooked oligonucleotide (a six-mer in our study) by Pol η providing a barrier to further elongation of the correct primer. No stalling by Rev1-Pol ζ directly past the ICL was observed, suggesting that the proposed function of Pol ζ as an extender DNA polymerase is also required for ICL repair

Performance Analysis Techniques for Real-time Broadband RFI Filtering System of uGMRT

Electromagnetic radiation from human activities, known as man-made Radio Frequency Interference (RFI), adversely affects radio astronomy observations. In the vicinity of the Upgraded Giant Metrewave Radio Telescope (uGMRT) array, the sparking on power lines is the major cause of interference at observing frequencies less than 800 MHz. A real-time broadband RFI detection and filtering system is implemented as part of the uGMRT wideband signal processing backend to mitigate the effect of broadband RFI. Performance analysis techniques used for testing and commissioning the system for observations in the beamformer and correlator modes of the uGMRT are presented. The concept and implementation of recording simultaneous unfiltered and filtered data along with data analysis and interpretation is illustrated using an example. For the beamformer mode, spectrogram, single spectral channel, and its Fourier transform is used for performance analysis whereas, in the correlator mode, the cross-correlation function, closure phase, and visibilities from the simultaneously recorded unfiltered and filtered is carried out. These techniques are used for testing the performance of the broadband RFI filter and releasing it for uGMRT users.Comment: 14 pages, 5 figure