A Feedback-Based Pneumatic Compression System for Effective Lymphedema Management

Bioimpedance analysis (BIA) is a method of detecting lymphedema- a debilitating medical condition involving swelling of the extremities. Pneumatic compression devices are frequently used in the compression treatment of lymphedema. Although existing compression technology provides relief of symptoms, it has limitations in terms of ease-of-use, portability, and monitoring of treatment progress. Currently, there are no BIA analyzers in the market that run on a low-power microcontroller and a rechargeable battery. Moreover, no such device currently exists that integrate the BIA analysis with pneumatic compression system to offer a feedback-based solution for lymphedema treatment. This work represents the first steps towards a complete system and describes the pneumatic compression and circuit designs for a portable BIA analyzer. The study proposes a lightweight, battery operated pneumatic compression device that can apply a pressure of 50 mmHg in a four-chamber compression garment. A microcontroller-based BIA system that can provide accurate indication of swelling based on a Nyquist plot was introduced. The envisioned mechatronic system features programmable compression sequences and operates with the human-in-the-loop using bioimpedance spectroscopy as control feedback. Performance of the compression system is verified by measurement of applied pressures and the BIA circuits are validated for single frequency and multi frequency impedance analysis of a phantom test load. With further development in the future, the system has the potential to serve as a quantitative source of valuable diagnostic information for clinicians, and in the long run may enable the smart management of lymphedema with the device essentially prescribing the course of treatment in response to measured conditions. This kind of human-in-the-loop control system may be a breakthrough in treatment of chronic conditions

Black Spruce (Picea mariana) Regeneration in Post-fire Cryptogamic Mats

Post-fire black spruce (Picea mariana Mill.) regeneration has received considerable attention in management of the boreal forest of eastern Canada. Seedbed quality is a key factor for seed germination and early seedling establishment. The objective of this research was to investigate the potential role of cryptogamic seedbeds in black spruce germination and seedling establishment. To compare lichen-dominated seedbeds with thin and thick organic matter, in situ seeding experiments were conducted at three sites in Terra Nova National Park, Newfoundland burned 11 (Rocky Pond, RP), 17 (Spracklin Road, SR) and 37 (Terra Nova Road, TNR) years ago. At each site, three manipulation treatments (mat-intact, mat-mixed and mat-removed) were applied to the seedbed with four replications in plots of 30 x 30 cm where 200 black spruce seeds were broadcasted. To compare lichen vs. moss seedbed, the same experimental design was extended to moss dominated seedbeds at the SR site. A laboratory germination bioassay was conducted to test the possible chemical effects of four cryptogamic species on black spruce germination and primary growth. Seed germination was highest in mat-intact and mat-removal plots with thick OM at RP, mat-mixed plots with thin OM at SR and matmixed plots with both thin and thick OM at TNR. There was significantly higher germination and seedling establishment on moss seedbeds than lichen seedbeds. In moss seedbeds, mat-mixed plots with thick OM had the highest germination but mat-intact plots of both thin and thick OM had higher seedling establishment. Moss seedbeds had higher soil moisture and lower surface temperature than lichen seedbeds. Laboratory bioassay with lichen Cladonia cristatella Tuck. had significantly lower germination and seedling growth than control but no difference between the control and moss treatments. HPLC analysis of C. cristatella indicated the presence of a germination inhibiting allelochemical, usnic acid. Lichen mat provides physical barrier to seed germination and seedling growth in late post-fire site TNR but not in early post-fire sites. It appears that moss dominated seedbeds facilitate black spruce regeneration by increasing seedbed moisture retention and maintaining low surface temperature, while lichen seedbeds inhibit seedling regeneration by their adverse physical and chemical effects. Cryptogamic seedbed type, OM thickness, soil moisture and temperature are limiting factors in poor black spruce seedling regeneration after fire

Micro/Nano Structured Materials for Enhanced Device Performance and Antibacterial Applications

Micro/nanostructured materials have been used extensively for various applications due to their unique chemical, physical, and mechanical properties. In this thesis we report the fabrication and characterization of micro/nanostructured materials with antibacterial properties. Plastics are used in a wide range of medical components such as prosthetics, implants, catheters, and syringes. However, contaminating bacteria can attach to plastic surfaces and grow and form biofilms that lead to healthcare associated infections. The consequences on patients and their families are serious, as infections can extend hospital stays, create long-term disability, increase healthcare costs, and even result in unnecessary deaths. Two strategies for creating antibacterial surfaces are (1) anti-biofouling surfaces that make the bacterial attachment process difficult and (2) bactericidal surfaces that kill bacteria cells that come in proximity of or contact the surface. We demonstrate that a fluorine etch chemistry may be utilized to create lotus leaf-inspired, low surface energy, hierarchical micro-structure/nanofibrils in Polypropylene (PP). Our anti-biofouling PP surfaces exhibit a 99.6% reduction of E. coli cell adhesion compared to untreated PP. We also fabricated bactericidal surfaces consisting of uniform and regular nanostructured arrays. The interest in mechanical bactericidal effect has recently increased, as the bacteria cells grow drug resistance. Nanosphere lithography and combination of reactive ion etching and deep reactive ion etching were utilized to prepare these substrates. The pitch, diameter, taper, and height of the nanostructures are controlled. The bactericidal effect of these structures is investigated and significant enhancement in killing is observed. We also report fabrication of micro/nanostructured materials to improve device performance. Our simulation results show that absorption enhancement in vertical nanowire arrays on a perfectly electric conductor can be further improved through tilting. Tilted nanowire arrays, with the same amount of material, exhibit improved performance over vertical nanowire arrays over a broad range of tilt angles. The optimum tilt of 53° has an improvement of 8.6% over that of vertical nanowire arrays and 80.4% of the ideal double pass thin film. Incorporation of these structures could improve the efficiency of solar cells

The Social World of Content Abusers in Community Question Answering

Community-based question answering platforms can be rich sources of information on a variety of specialized topics, from finance to cooking. The usefulness of such platforms depends heavily on user contributions (questions and answers), but also on respecting the community rules. As a crowd-sourced service, such platforms rely on their users for monitoring and flagging content that violates community rules. Common wisdom is to eliminate the users who receive many flags. Our analysis of a year of traces from a mature Q&A site shows that the number of flags does not tell the full story: on one hand, users with many flags may still contribute positively to the community. On the other hand, users who never get flagged are found to violate community rules and get their accounts suspended. This analysis, however, also shows that abusive users are betrayed by their network properties: we find strong evidence of homophilous behavior and use this finding to detect abusive users who go under the community radar. Based on our empirical observations, we build a classifier that is able to detect abusive users with an accuracy as high as 83%.Comment: Published in the proceedings of the 24th International World Wide Web Conference (WWW 2015

Cultures in Community Question Answering

CQA services are collaborative platforms where users ask and answer questions. We investigate the influence of national culture on people's online questioning and answering behavior. For this, we analyzed a sample of 200 thousand users in Yahoo Answers from 67 countries. We measure empirically a set of cultural metrics defined in Geert Hofstede's cultural dimensions and Robert Levine's Pace of Life and show that behavioral cultural differences exist in community question answering platforms. We find that national cultures differ in Yahoo Answers along a number of dimensions such as temporal predictability of activities, contribution-related behavioral patterns, privacy concerns, and power inequality.Comment: Published in the proceedings of the 26th ACM Conference on Hypertext and Social Media (HT'15

Estimation of Optimum Number of Poles for Random Signal by Yule-Walker Method

The Yule-Walker method is an effective method to estimate the system response or spectrum for random signal. Hence most of the noise and spurious signals are random in nature, so it is very convenient to estimate their spectrum by Yule-Walker method successfully. The Yule-Walker method is an autoregressive process to estimate the poles and errors also based on the number of poles for Wide Sense Stationary (WSS) process as well. Moreover the value of zero will be correspondingly calculated based on the poles in case of all poles model. The main concern of this paper is to analyze the Yule-Walker method and estimate the poles and zero along with the error based on the number of poles for a random signal. Moreover analyze the results to find out the optimum number of poles for least possible error