Deliberation in Practice: Deliberative Theory, News Media, and Political Conversation

While much scholarly attention has been paid to deliberation as a set of procedures used to achieve democratic goals of individual autonomy and mutually beneficial policy outcomes, few studies have asked to what extent contemporary American society resembles a deliberative democracy. In order to assess the prospects for deliberative democracy, everyday political conversation, its influences and its consequences are examined. The dissertation establishes a “reasonable ideal” of deliberation by which a democracy may be judged. The reasonable ideal has five elements: conversation, disagreement, information, the common interest, and the accommodation of uncertainty. Results show that American democracy is deliberative in some ways but not in others. Political conversation is disproportionately the pastime of the elite, and discussion across lines of difference, an essential element of deliberation, is extremely rare. Contrary to the assumptions of deliberative theory, conversation produces an increase in the belief that citizens are motivated by self-interest. However, the discussions that occur do succeed in producing learning and reducing uncertainty about political issues. While media use serves deliberative ends by spurring some to discuss politics and providing information, it also increases the likelihood that others will view political discussion as unpleasantly argumentative. News media thus encourage deliberation for some and discourage it for others

A "synaptoplasmic cistern" mediates rapid inhibition of cochlear hair cells

Cochlear hair cells are inhibited by cholinergic efferent neurons. The acetylcholine (ACh) receptor of the hair cell is a ligand-gated cation channel through which calcium enters to activate potassium channels and hyperpolarize the cell. It has been proposed that calcium-induced calcium release (CICR) from a near-membrane postsynaptic store supplements this process. Here, we demonstrate expression of type I ryanodine receptors in outer hair cells in the apical turn of the rat cochlea. Consistent with this finding, ryanodine and other store-active compounds alter the amplitude of transient currents produced by synaptic release of ACh, as well as the response of the hair cell to exogenous ACh. Like the sarcoplasmic reticulum of muscle, the "synaptoplasmic" cistern of the hair cell efficiently couples synaptic input to CICR.Fil: Lioudyno, Maria. Johns Hopkins University School of Medicine; Estados UnidosFil: Hiel, Hakim. Johns Hopkins University School of Medicine; Estados UnidosFil: Kong, Jee-Hyun. Johns Hopkins University School of Medicine; Estados UnidosFil: Katz, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Waldman, Erik. Johns Hopkins University School of Medicine; Estados UnidosFil: Parameshwaran Iyer, Suchitra. Johns Hopkins University School of Medicine; Estados UnidosFil: Glowatzki, Elisabeth. Johns Hopkins University School of Medicine; Estados UnidosFil: Fuchs, Paul A.. Johns Hopkins University School of Medicine; Estados Unido

Genomic aberrations in normal tissue adjacent to HER2-amplified breast cancers: field cancerization or contaminating tumor cells?

Field cancerization effects as well as isolated tumor cell foci extending well beyond the invasive tumor margin have been described previously to account for local recurrence rates following breast conserving surgery despite adequate surgical margins and breast radiotherapy. To look for evidence of possible tumor cell contamination or field cancerization by genetic effects, a pilot study (Study 1: 12 sample pairs) followed by a verification study (Study 2: 20 sample pairs) were performed on DNA extracted from HER2-positive breast tumors and matching normal adjacent mammary tissue samples excised 1-3 cm beyond the invasive tumor margin. High-resolution molecular inversion probe (MIP) arrays were used to compare genomic copy number variations, including increased HER2 gene copies, between the paired samples; as well, a detailed histologic and immunohistochemical (IHC) re-evaluation of all Study 2 samples was performed blinded to the genomic results to characterize the adjacent normal tissue composition bracketing the DNA-extracted samples. Overall, 14/32 (44 %) sample pairs from both studies produced genome-wide evidence of genetic aberrations including HER2 copy number gains within the adjacent normal tissue samples. The observed single-parental origin of monoallelic HER2 amplicon haplotypes shared by informative tumor-normal pairs, as well as commonly gained loci elsewhere on 17q, suggested the presence of contaminating tumor cells in the genomically aberrant normal samples. Histologic and IHC analyses identified occult 25-200 μm tumor cell clusters overexpressing HER2 scattered in more than half, but not all, of the genomically aberrant normal samples re-evaluated, but in none of the genomically normal samples. These genomic and microscopic findings support the conclusion that tumor cell contamination rather than genetic field cancerization represents the likeliest cause of local clinical recurrence rates following breast conserving surgery, and mandate caution in assuming the genomic normalcy of histologically benign appearing peritumor breast tissue

Titanium addition influences antibacterial activity of bioactive glass coatings on metallic implants

© 2017 The Authors In an attempt to combat the possibility of bacterial infection and insufficient bone growth around metallic, surgical implants, bioactive glasses may be employed as coatings. In this work, silica-based and borate-based glass series were synthesized for this purpose and subsequently characterized in terms of antibacterial behavior, solubility and cytotoxicity. Borate-based glasses were found to exhibit significantly superior antibacterial properties and increased solubility compared to their silica-based counterparts, with BRT0 and BRT3 (borate-based glasses with 0 and 15 mol% of titanium dioxide incorporated, respectively) outperforming the remainder of the glasses, both borate and silicate based, in these respects. Atomic Absorption Spectroscopy confirmed the release of zinc ions (Zn2+), which has been linked to the antibacterial abilities of glasses SRT0, BRT0 and BRT3, with inhibition effectively achieved at concentrations lower than 0.7 ppm. In vitro cytotoxicity studies using MC3T3-E1 osteoblasts confirmed that cell proliferation was affected by all glasses in this study, with decreased proliferation attributed to a faster release of sodium ions over calcium ions in both glass series, factor known to slow cell proliferation in vitro

Impact of Type Ia Supernova Ejecta on a Helium-star Binary Companion

The impact of Type Ia supernova ejecta on a helium-star companion is investigated via high-resolution, two-dimensional hydrodynamic simulations. For a range of helium-star models and initial binary separations it is found that the mass unbound in the interaction, $\delta M_{\rm ub}$, is related to the initial binary separation, $a$, by a power law of the form $\delta M_{\rm ub} \propto a^{m}$. This power-law index is found to vary from -3.1 to -4.0, depending on the mass of the helium star. The small range of this index brackets values found previously for hydrogen-rich companions, suggesting that the dependence of the unbound mass on orbital separation is not strongly sensitive to the nature of the binary companion. The kick velocity is also related to the initial binary separation by a power law with an index in a range from -2.7 to -3.3, but the power-law index differs from those found in previous studies for hydrogen-rich companions. The space motion of the companion after the supernova is dominated by its orbital velocity in the pre-supernova binary system. The level of Ni/Fe contamination of the companion resulting from the passage of the supernova ejecta is difficult to estimate, but an upper limit on the mass of bound nickel is found to be $\sim 5\times 10^{-4}\ M_\odot$.Comment: Accepted in ApJ, 9 pages, 9 figure

Effect of TiO2 Doping on Degradation Rate, Microstructure and Strength of Borate Bioactive Glass Scaffolds

A titanium-containing borate glass series based on the system (52-X) B2O3–12CaO–6P2O5–14Na2O–16ZnO-XTiO2 with X varying from 0, 5 and 15 mol% of TiO2 incorporated, identified as BRT0, BRT1 and BRT3, respectively, were used in this study. Scaffolds (pore sizes, 165–230 μm and porosity, 53.51–69.51%) were prepared using a polymer foam replication technique. BRT3 scaffolds exhibited higher compressive strength (7.16 ± 0.22 MPa) when compared to BRT0 (6.02 ± 0.47 MPa) and BRT1 (5.65 ± 0.28 MPa) scaffolds with lower, or no, TiO2 content. The solubility of the scaffolds decreased as the TiO2 content increased up to 15 mol% when samples of each scaffold were immersed in DI water and the pH of all these extracts went up from 7.0 to 8.5 in 30 days. The cumulative ion release from the scaffolds showed significant difference with respect to TiO2 content; addition of 5 mol% TiO2 at the expense of borate (B2O3) decreased the ion release remarkably. Furthermore, it was found that for all three scaffolds, cumulative ion release increased with incubation time. The results indicate that the degradation rates and compressive strengths of borate bioactive glass scaffolds could be controlled by varying the amount of TiO2 incorporated, confirming their potential as scaffolds in TKA and rTKA

The role of poly(methyl methacrylate) in management of bone loss and infection in revision total knee arthroplasty: A review

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Poly(methyl methacrylate) (PMMA) is widely used in joint arthroplasty to secure an implant to the host bone. Complications including fracture, bone loss and infection might cause failure of total knee arthroplasty (TKA), resulting in the need for revision total knee arthroplasty (rTKA). The goals of this paper are: (1) to identify the most common complications, outside of sepsis, arising from the application of PMMA following rTKA, (2) to discuss the current applications and drawbacks of employing PMMA in managing bone loss, (3) to review the role of PMMA in addressing bone infection following complications in rTKA. Papers published between 1970 to 2018 have been considered through searching in Springer, Google Scholar, IEEE Xplore, Engineering village, PubMed and weblinks. This review considers the use of PMMA as both a bone void filler and as a spacer material in two-stage revision. To manage bone loss, PMMA is widely used to fill peripheral bone defects whose depth is less than 5 mm and covers less than 50% of the bone surface. Treatment of bone infections with PMMA is mainly for two-stage rTKA where antibiotic-loaded PMMA is inserted as a spacer. This review also shows that using antibiotic-loaded PMMA might cause complications such as toxicity to surrounding tissue, incomplete antibiotic agent release from the PMMA, roughness and bacterial colonization on the surface of PMMA. Although PMMA is the only commercial bone cement used in rTKA, there are concerns associated with using PMMA following rTKA. More research and clinical studies are needed to address these complications

Comparative Evaluation of Two Glass Polyalkenoate Cements: An in Vivo Pilot Study using a Sheep Model

Poly(methyl methacrylate) (PMMA) is used to manage bone loss in revision total knee arthroplasty (rTKA). However, the application of PMMA has been associated with complications such as volumetric shrinkage, necrosis, wear debris, and loosening. Glass polyalkenoate cements (GPCs) have potential bone cementation applications. Unlike PMMA, GPC does not undergo volumetric shrinkage, adheres chemically to bone, and does not undergo an exothermic setting reaction. In this study, two different compositions of GPCs (GPCA and GPCB), based on the patented glass system SiO2-CaO-SrO-P2O5-Ta2O5, were investigated. Working and setting times, pH, ion release, compressive strength, and cytotoxicity of each composition were assessed, and based on the results of these tests, three sets of samples from GPCA were implanted into the distal femur and proximal tibia of three sheep (alongside PMMA as control). Clinical CT scans and micro-CT images obtained at 0, 6, and 12 weeks revealed the varied radiological responses of sheep bone to GPCA. One GPCA sample (implanted in the sheep for 12 weeks) was characterized with no bone resorption. Furthermore, a continuous bone–cement interface was observed in the CT images of this sample. The other implanted GPCA showed a thin radiolucent border at six weeks, indicating some bone resorption occurred. The third sample showed extensive bone resorption at both six and 12 weeks. Possible speculative factors that might be involved in the varied response can be: excessive Zn2+ ion release, low pH, mixing variability, and difficulty in inserting the samples into different parts of the sheep bone