Determining the physical limits on semi‐active control performance: a tutorial

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106822/1/stc1602.pd

A Breast Prosthesis Infection Update: Two-Year Incidence, Risk Factors and Management at Single Institution

Background: Infection following augmentation and prosthetic-based breast reconstruction can cause significant physical and psychological distress for patients. It may delay adjuvant therapies and compromise aesthetic outcomes. The aim of this study is to identify modifiable risk factors for infection and identify common bacterial isolates to achieve optimal outcomes for patients. Methods: A retrospective cohort study was performed for patients undergoing implant-based breast reconstruction over a 2-year period. In each case, we documented demographics, co-morbidities, complications and antibiotic use. We reviewed treatments, infectious species cultured where applicable and all outcomes. Results: A total of 292 patients met the inclusion criteria. Fifty-five patients (19%) developed an infection. Univariate analysis showed a significantly increased infection rate with longer operative times (P = 0.001) and use of tissue expanders (P = 0.001). Multiple logistic regression analysis confirmed drain use and elevated body mass index (BMI) as risk factors (odds ratio [OR] 2.427 and 1.061, respectively). After controlling for BMI, smoking status and radiation, we found an increased odd of infection with allograft use (OR 1.838) and a decreased odd with skin preparation using 2% chlorhexidine gluconate in 70% isopropyl (OR 0.554), though not statistically significant. Forty of 55 patients with infections had cultures, with 62.5% of isolates being Gram-positive species and 30% Gram-negative species. The median time to clinical infection was 25 days. Implant salvage with surgical interventions was achieved in 61.5% of patients. Conclusions: This study identified judicious use of drains and efficiency in the operating room as modifiable risk factors for infections following implant-based breast reconstruction. Prospective trials to analyse techniques for infection prevention are warranted. Implant salvage following infection is a possible end-point in the appropriate patient

Technical assessment of the Office of Industrial Programs' Advanced Heat Exchanger Program

The DOE's AHX Program is an integral part of the OIP's Waste Heat Recovery Program whose goals are to increase the end-use energy efficiency of industry and agricultural operations, and to expand the energy options for manufacturing processes by providing technologies which use various fuels including coal, renewables, oil, and natural gas. The OIP and PNL convened a panel of industry experts to conduct a technical assessment of OIP's AHX program. This report documents the results of the panel's assessment

EFFECT OF PEG COATING ON NANOPARTICLE DIFFUSION THROUGH TUMOUR EXTRACELLULAR MATRIX

INTRODUCTION Nanoparticle drug delivery systems have the potential to improve current cancer treatments through encapsulating cytotoxic agents and delivering them to specific sites in the body. One such class of particle, liposomes, has already found some commercial success [1]. Liposomes are vesicles composed of a lipid bi-layer surrounding an aqueous solution. Poly(ethylene) glycol (PEG) surface coating is commonly used to improve the hydrophilicity of liposomes, thereby increasing their stability in aqueous solutions. Furthermore, PEG limits the binding of blood antigens, which minimizes opsonisation and phagocytosis, extending circulation time in the blood stream. When applied to the surface of liposomes at lower molecular weights and surface densities, PEG adopts a “mushroom” conformation, in which adjacent chains of PEG do not interact laterally, therefore portions of the bi-layer remain exposed [2]. However, at higher molecular weights and surface densities, the “brush” conformation is adopted; where lateral interactions occur between neighbouring PEG strands and provide complete coverage of the lipid bi-layer [2]. This study will investigate the effect of varying PEG molecular weight and surface density on liposome transport through tumour extracellular matrix. METHODS Seven different formulations of liposomes were synthesized using a modification of the lipid extrusion method described in [1]. Molecular weight and surface density values were chosen to include both PEG conformations. The Type I collagen hydrogel was prepared with a collagen concentration of 2.5mg/mL. Confocal Microscopy was used to track the liposome transport into the gels via the bilayer incorporated Rhodamine dye. While simple collagen hydrogels may not capture all of the complexity of native tumour ECM, they allow for more carefully controlled conditions than in vivo models. Images were taken every 30 minutes until the 900 minute mark. RESULTS As shown in Figure 1, the liposomes with a lower PEG loading (DOPC, 5, 10% PEG 1000, 5, 10% PEG 2000), all accumulated at the interface of the hydrogel, and had identical diffusion coefficients. The 5% and 10% PEG 5000 however, accumulated significantly less and therefore had a much greater diffusion coefficient.DISCUSSION AND CONCLUSIONS The liposomes with low PEG surface density, and DOPC control liposomes shown in Figure 1, are all within the “mushroom” conformation of PEG [2] and therefore would all have exposed bilayer which is not shielded by the PEG strands. The formulations that penetrated deeply were notably only higher PEG surface densities (5 and 10% PEG 5000) which literature suggests would have been in the “brush” conformation [2]. This suggests that the high PEG surface densities sterically shielded the liposomes, and reduced the electrostatic interactions between the hydrogels and the liposomes, allowing increased diffusion

Short-range correlations in low-lying nuclear excited states

The electromagnetic transitions to various low-lying excited states of 16O, 48Ca and 208Pb are calculated within a model which considers the short-range correlations. In general the effects of the correlations are small and do not explain the required quenching to describe the data.Comment: 6 pages, 2 postscript figures, 1 tabl

Muon capture on nuclei with N > Z, random phase approximation, and in-medium renormalization of the axial-vector coupling constant

We use the random phase approximation to describe the muon capture rate on ${}^{44}$Ca,${}^{48}$Ca, ${}^{56}$Fe, ${}^{90}$Zr, and ${}^{208}$Pb. With ${}^{40}$Ca as a test case, we show that the Continuum Random Phase Approximation (CRPA) and the standard RPA give essentially equivalent descriptions of the muon capture process. Using the standard RPA with the free nucleon weak form factors we reproduce the experimental total capture rates on these nuclei quite well. Confirming our previous CRPA result for the $N = Z$ nuclei, we find that the calculated rates would be significantly lower than the data if the in-medium quenching of the axial-vector coupling constant were employed.Comment: submitted to Phys. Rev.

Tropical Herbivorous Phasmids, but Not Litter Snails, Alter Decomposition Rates By Modifying Litter Bacteria

Consumers can alter decomposition rates through both feces and selective feeding in many ecosystems, but these combined effects have seldom been examined in tropical ecosystems. Members of the detrital food web (litter-feeders or microbivores) should presumably have greater effects on decomposition than herbivores, members of the green food web. Using litterbag experiments within a field enclosure experiment, we determined the relative effects of common litter snails (Megalomastoma croceum) and herbivorous walking sticks (Lamponius portoricensis) on litter composition, decomposition rates, and microbes in a Puerto Rican rainforest, and whether consumer effects were altered by canopy cover presence. Although canopy presence did not alter consumers’ effects, focal organisms had unexpected influences on decomposition. Decomposition was not altered by litter snails, but herbivorous walking sticks reduced leaf decomposition by about 50% through reductions in high quality litter abundance and, consequently, lower bacterial richness and abundance. This relatively unexplored but potentially important link between tropical herbivores, detritus, and litter microbes in this forest demonstrates the need to consider autotrophic influences when examining rainforest ecosystem processes