Indirect Network Effects and Adoption Externalities

The conventional wisdom is that indirect network effects, unlike direct network effects, do not give rise to externalities. In this paper we show that under very general conditions, indirect network effects lead to adoption externalities. In particular we show that in markets where consumption benefits arise from hardware/software systems, adoption externalities will occur when there are (i) increasing returns to scale in the production of software, (ii) free-entry in software, and (iii) consumers have a preference for software variety. The private benefit of the marginal hardware purchaser is less than the social benefit since the marginal hardware purchaser does not internalize the welfare improving response of the software industry, particularly the increase in software variety, on inframarginal purchasers when the market for hardware expands.Network Externalities, Network Effects

Engineering Controls for Bioaerosols in Non-Industrial/Non-Healthcare Settings

The list of disease pathogens that can be transmitted in the air is extensive. This list includes the common cold, SARS, measles, Hansen’s disease (leprosy), polio, influenza, Legionella (Legionnaires’ disease and Pontiac fever), and tuberculosis (TB). TB, SARS-CoV-1, avian influenza, varicella, and now SARS-CoV-2 all have received public notice due not only to their known or assumed ability to be transmitted in the air rapidly from one individual to another, but also for their virulence. Other bioaerosols that can be transmitted through the air include bacteria, fungal spores and fragments, dust mites, and pollen. This document was developed to address control of bioaerosols transmission, primarily through ventilation and other engineering controls. This monograph will focus on engineering controls in non-industrial/ non-healthcare facilities such as office buildings, schools, public assembly, theaters, and governmental buildings. It does not, however, address ventilation in residences, either single or multi-family

The use of an online support group for neuromuscular disorders: a thematic analysis of message postings

Purpose: People affected by neuromuscular disorders can experience adverse psychosocial consequences and difficulties accessing information and support. Online support groups provide new opportunities for peer support. The aim of this study was to understand how contributors used the message board function of a newly-available neuromuscular disorders online support group. Methods: Message postings (n=1,951) from the first five months of the message board of a newly-formed online support group for neuromuscular disorders hosted by a charitable organisation were analysed using inductive thematic analysis. Results: Members created a sense of community through disclosing personal information, connecting with people with similar illness experiences or interests, welcoming others, and sharing aspirations for the development of a resourceful community. Experiences, emotional reactions and support were shared in relation to: delayed diagnosis; symptom interpretation; illness management and progression; the isolating impact of rare disorders; and the influence of social and political factors on illness experiences. Conclusions: This study provided a novel insight into individuals’ experiences of accessing a newly-available online support group for rare conditions hosted by a charitable organisation. The findings highlight how the online support group provided an important peer support environment for members to connect with others, exchange information and support, and engender discussion on political and social issues unique to living with often-rare neuromuscular disorders. Online support groups may therefore provide an important and easily accessible support outlet for people with neuromuscular disorders as well as a platform for empowering members to raise awareness about the impact of living with these conditions. Further research is needed to examine member motivations for using such groups and any effects of participation in greater detail

Cancer Patient T Cells Genetically Targeted to Prostate-Specific Membrane Antigen Specifically Lyse Prostate Cancer Cells and Release Cytokines in Response to Prostate-Specific Membrane Antigen

AbstractThe expression of immunoglobulin-based artificial receptors in normal T lymphocytes provides a means to target lymphocytes to cell surface antigens independently of major histocompatibility complex restriction. Such artificial receptors have been previously shown to confer antigen-specific tumoricidal properties in murine T cells. We constructed a novel ζ chain fusion receptor specific for prostate-specific membrane antigen (PSMA) termed Pz-1. PSMA is a cell-surface glycoprotein expressed on prostate cancer cells and the neovascular endothelium of multiple carcinomas. We show that primary T cells harvested from five of five patients with different stages of prostate cancer and transduced with the Pz-1 receptor readily lyse prostate cancer cells. Having established a culture system using fibroblasts that express PSMA, we next show that T cells expressing the Pz-1 receptor release cytokines in response to cell-bound PSMA. Furthermore, we show that the cytokine release is greatly augmented by B7.1-mediated costimulation. Thus, our findings support the feasibility of adoptive cell therapy by using genetically engineered T cells in prostate cancer patients and suggest that both CD4+ and CD8+ T lymphocyte functions can be synergistically targeted against tumor cells

Turing Patterning in Stratified Domains

Reaction-diffusion processes across layered media arise in several scientific domains such as pattern-forming E. coli on agar substrates, epidermal-mesenchymal coupling in development, and symmetry-breaking in cell polarisation. We develop a modelling framework for bi-layer reaction-diffusion systems and relate it to a range of existing models. We derive conditions for diffusion-driven instability of a spatially homogeneous equilibrium analogous to the classical conditions for a Turing instability in the simplest nontrivial setting where one domain has a standard reaction-diffusion system, and the other permits only diffusion. Due to the transverse coupling between these two regions, standard techniques for computing eigenfunctions of the Laplacian cannot be applied, and so we propose an alternative method to compute the dispersion relation directly. We compare instability conditions with full numerical simulations to demonstrate impacts of the geometry and coupling parameters on patterning, and explore various experimentally-relevant asymptotic regimes. In the regime where the first domain is suitably thin, we recover a simple modulation of the standard Turing conditions, and find that often the broad impact of the diffusion-only domain is to reduce the ability of the system to form patterns. We also demonstrate complex impacts of this coupling on pattern formation. For instance, we exhibit non-monotonicity of pattern-forming instabilities with respect to geometric and coupling parameters, and highlight an instability from a nontrivial interaction between kinetics in one domain and diffusion in the other. These results are valuable for informing design choices in applications such as synthetic engineering of Turing patterns, but also for understanding the role of stratified media in modulating pattern-forming processes in developmental biology and beyond.Comment: 25 pages, 7 figure