Performance Analysis of Localization Techniques with Generalized Prior Distributions

Low error of indoor localization of wireless transmitters is difficult to achieve with only the received signal strength. This work includes an investigation of the probabilistic method for estimating the position of an unknown node in an indoor environment, Improved Prior Measurement Comparison (PMC+). PMC+ relies on a prior distribution for the unknown node position that emphasizes the probability of a node being in a specific room using a comparison to prior measurements made in that room. We expand the method of calculating this distribution to include arbitrary room shape and sensor placement. This method is then applied to a simulation and measurement campaign in an actual building at the University of New Hampshire, and the results of PMC+ are compared to other localization techniques. PMC+ significantly increases the likelihood of estimating the correct room of the unknown node

Floristic quality and site assessment of Inverness Mud Lake Bog in Cheboygan County, Michigan

Nature conservancy organizations need a standard by which to compare sites in order to protect those with more significance. Mud Lake Bog in Cheboygan County, Michigan is a protected natural reserve. Mud Lake Bog hosts a wide variety of naturally-occurring floral zones that delineate the sequence of wetland regions surrounding the central lake. We divided Mud Lake Bog into three regions: Cedar Swamp, Spruce Muskeg, and Sphagnum mat. In each of these areas we inventoried all the flora species we found. This inventory was collected along a transect extending through all three areas and then in the area surrounding the transect. We then performed a floristic quality assessment on the inventory to assess plant diversity and floristic condition of the entire studied site. We found that Mud Lake Bog has high floristic quality index rating inferring a status very similar to pre-European settlement.http://deepblue.lib.umich.edu/bitstream/2027.42/55001/1/3442.pdfDescription of 3442.pdf : Access restricted to on-site users at the U-M Biological Station

Xenoantigenicity of porcine decellularized valves

Abstract Background The xenoantigenicity of porcine bioprosthetic valves is implicated as an etiology leading to calcification and subsequent valve failure. Decellularization of porcine valves theoretically could erase the antigenicity of the tissue leading to more durable prosthetic valves, but the effectiveness of decellularization protocols in regard to completely removing antigens has yet to be verified. Our hypothesis was that decellularization would remove the more abundant α-gal antigens but not remove all the non α-gal antigens, which could mount a response. Methods Porcine aortic valves were decellularized with 1% sodium dodecyl sulfate for 4 days. Decellularized cusps were evaluated for α-gal epitopes by ELISA. To test for non α-gal antigens, valves were implanted into sheep. Serum was obtained from the sheep preoperatively and 1 week, 1 month, and 2 months postoperatively. This serum was utilized for anti-porcine antibody staining and for quantification of anti-pig IgM and IgG antibodies and complement. Results Decellularized porcine cusps had 2.8 ± 2.0% relative α-gal epitope as compared to fresh porcine aortic valve cusps and was not statistically significantly different (p = 0.4) from the human aortic valve cusp which had a 2.0 ± 0.4% relative concentration. Anti-pig IgM and IgG increased postoperatively from baseline levels. Preoperatively anti-pig IgM was 27.7 ± 1.7 μg/mL and it increased to 71.9 ± 12.1 μg/mL average of all time points postoperatively (p = 0.04). Preoperatively anti-pig IgG in sheep serum was 44.9 ± 1.5 μg/mL and it increased to 72.6 ± 6.0 μg/mL average of all time points postoperatively (p = 0.01). There was a statistically significant difference (p = 0.00007) in the serum C1q concentration before valve implantation (2.5 ± 0.2 IU/mL) and at averaged time points after valve implantation (5.3 ± 0.3 IU/mL). Conclusions Decellularization with 1% sodium dodecyl sulfate does not fully eliminate non α-gal antigens; however, significant reduction in α-gal presence on decellularized cusps was observed. Clinical implications of the non α-gal antigenic response are yet to be determined. As such, evaluation of any novel decellularized xenografts must include rigorous antigen testing prior to human trials

Supercritical Carbon DioxideâBased Sterilization of Decellularized Heart Valves

Summary: Sterilization of grafts is essential. Supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide techniques were compared for impact on sterility and mechanical integrity of porcine decellularized aortic valves. Ethanol-peracetic acidâ and supercritical carbon dioxideâtreated valves were found to be sterile using histology, microbe culture, and electron microscopy assays. The cusp tensile properties of supercritical carbon dioxideâtreated valves were higher compared with valves treated with other techniques. Superior sterility and integrity was found in the decellularized valves treated with supercritical carbon dioxide sterilization. This sterilization technique may hold promise for other decellularized soft tissues. Key Words: decellularized, decontamination, heart valve, tensile properties, tissue engineerin

Additional file 1: of Xenoantigenicity of porcine decellularized valves

Methods Supplement (DOCX 19 kb

Recellularization of a novel off-the-shelf valve following xenogenic implantation into the right ventricular outflow tract.

Current research on valvular heart repair has focused on tissue-engineered heart valves (TEHV) because of its potential to grow similarly to native heart valves. Decellularized xenografts are a promising solution; however, host recellularization remains challenging. In this study, decellularized porcine aortic valves were implanted into the right ventricular outflow tract (RVOT) of sheep to investigate recellularization potential. Porcine aortic valves, decellularized with sodium dodecyl sulfate (SDS), were sterilized by supercritical carbon dioxide (scCO2) and implanted into the RVOT of five juvenile polypay sheep for 5 months (n = 5). During implantation, functionality of the valves was assessed by serial echocardiography, blood tests, and right heart pulmonary artery catheterization measurements. The explanted valves were characterized through gross examination, mechanical characterization, and immunohistochemical analysis including cell viability, phenotype, proliferation, and extracellular matrix generation. Gross examination of the valve cusps demonstrated the absence of thrombosis. Bacterial and fungal stains were negative for pathogenic microbes. Immunohistochemical analysis showed the presence of myofibroblast-like cell infiltration with formation of new collagen fibrils and the existence of an endothelial layer at the surface of the explant. Analysis of cell phenotype and morphology showed no lymphoplasmacytic infiltration. Tensile mechanical testing of valve cusps revealed an increase in stiffness while strength was maintained during implantation. The increased tensile stiffness confirms the recellularization of the cusps by collagen synthesizing cells. The current study demonstrated the feasibility of the trans-species implantation of a non-fixed decellularized porcine aortic valve into the RVOT of sheep. The implantation resulted in recellularization of the valve with sufficient hemodynamic function for the 5-month study. Thus, the study supports a potential role for use of a TEHV for the treatment of valve disease in humans

Mechanical properties.

<p>(A.) Stiffness comparison of native porcine, decellularized porcine with sterilization, and recellularized porcine explant after 5 months in vivo. (B.) Ultimate tensile strength comparison of native porcine, decellularized porcine implant with sterilization, and recellularized porcine explant after 5-months in vivo.</p

Gross examination.

<p>Explanted aortic valves showing aortic cusp without evidence of thrombosis, increased thickness, or calcification. Explant taken immediately after 5-month sacrifice and cross-sectioned to show anatomical features.</p