The Life-Cycle Permanent-Income Model and Consumer Durables

This paper presents an extension of the life-cycle permanent-income model of consumption to the case of a durable good whose purchase involves lumpy trans- actions costs. Where individual behavior is concerned, the implications of the model are different in some respects from those of standard consumption theory. Specifically, rather than choose an optimal path for the service flow from durables, the optimizing consumer will choose an optimal range and try to keep his service flow inside that range. The dynamics implied by this behavior is different from that of the stock adjustment model. Properties of aggregate durables consumption are derived by explicit aggregation. In particular, it is shown that expenditures on durables display very large short-run elasticity to changes in permanent income. Empirical tests of the sort suggested by Hall (1978) generally produce results that are in line with the predictions of the theory.

Two Notions of Privacy Online

Users of social networking websites tend to disclose much personal information online yet seem to retain some form of an expectation of privacy. Is this expectation of privacy always unreasonable? How do users of online social networks define their expectations of privacy online? These questions were the impetus behind an empirical study, the findings of which are presented in this Article. The project, simultaneously conducted in Canada, at Ryerson University, and in the United States, at the University of Miami, consisted of a survey regarding personal information protection and expectations of privacy on online social networks (OSNs). Approximately 2,500 young adults between the ages of 18 and 24 were surveyed about the personal information they post online, the measures they take to protect such information, and their concerns, if any, regarding their personal information. Respondents also reacted to several hypothetical scenarios in which their privacy was breached on an OSN by measures both within and beyond their control. The theoretical assumption underlying this research project is that two prevalent and competing notions of privacy online exist: one rooted in control and the other in dignity. Of the two, the idea of privacy as control over one\u27s personal information has, to date, been predominant. Legislation, regulation, corporate policy, and technology are often analyzed and evaluated in terms of the measure of control offered to individuals over their personal information. Leading OSNs, such as Facebook and MySpace, propagate a notion of privacy as user control. However, online social networking poses a fundamental challenge to the theory of privacy as control. A high degree of control cannot preclude the possibility that online socializers would post unflattering, defamatory, or personal information about each other, and that this information would in turn be available to a large, if not unrestricted, online audience. Many online socializers post personal information seemingly without much concern over the loss of control, yet it seems that online socializers react with indignation when their personal information is accessed, used, or disclosed by individuals perceived to be outside their social network. The findings presented here indicate indeed that online socializers have developed a new and arguably legitimate notion of privacy online, that if accepted by OSNs, will offer online socializers both control and protection of their dignity and reputation. We call this notion network privacy. According to network privacy, information is considered by online socializers to be private as long as it is not disclosed outside of the network to which they initially disclosed it, if it originates with them, or as long as it does not affect their established online personae, if it originates with others. OSNs, as businesses profiting from socializing online, are best positioned to offer online socializers, often the young and vulnerable, effective protection in accordance with their notion of network privacy above and beyond regular measures of personal information control, and they should be required to do so

Correlation Functions of Coulomb Branch Operators

We consider the correlation functions of Coulomb branch operators in four-dimensional N=2 Superconformal Field Theories (SCFTs) involving exactly one anti-chiral operator. These extremal correlators are the "minimal" non-holomorphic local observables in the theory. We show that they can be expressed in terms of certain determinants of derivatives of the four-sphere partition function of an appropriate deformation of the SCFT. This relation between the extremal correlators and the deformed four-sphere partition function is non-trivial due to the presence of conformal anomalies, which lead to operator mixing on the sphere. Evaluating the deformed four-sphere partition function using supersymmetric localization, we compute the extremal correlators explicitly in many interesting examples. Additionally, the representation of the extremal correlators mentioned above leads to a system of integrable differential equations. We compare our exact results with previous perturbative computations and with the four-dimensional tt^* equations. We also use our results to study some of the asymptotic properties of the perturbative series expansions we obtain in N=2 SQCD.Comment: 47 pages, 6 figures. v2: typos corrected and references adde

Deliberating Public Policy Issues with Adolescents: Classroom Dynamics and Sociocultural Considerations

Classroom discussion and deliberation have been widely touted in the research literature as a centerpiece of high quality civic education. Empirical studies, however, of such processes are relatively few. In a public policy deliberation on immigration conducted in three Midwestern high schools during the academic year 2015–16, the authors found that analysis of a set of deliberations on the subject of immigration policy in the United States reveals the ways in which sociocultural identity aspects of the settings and participants influenced the processes and dynamics of these classroom events. Reflecting upon this analysis suggests a set of factors that reveal the degree to which classroom deliberations are shaped by factors other than rational consideration of the topic

Global Stability of a Premixed Reaction Zone (Time-Dependent Liñan’s Problem)

Global stability properties of a premixed, three-dimensional reaction zone are considered. In the nonadiabatic case (i.e., when there is a heat exchange between the reaction zone and the burned gases) there is a unique, spatially one-dimensional steady state that is shown to be unstable (respectively, asymptotically stable) if the reaction zone is cooled (respectively, heated) by the burned mixture. In the adiabatic case, there is a unique (up to spatial translations) steady state that is shown to be stable. In addition, the large-time asymptotic behavior of the solution is analyzed to obtain sufficient conditions on the initial data for stabilization. Previous partial numerical results on linear stability of one-dimensional reaction zones are thereby confirmed and extended

UK experience of liver transplantation for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is characterised by excess production of free protoporphyrin from the bone marrow, most commonly due to deficiency of the enzyme ferrochelatase. Excess protoporphyrin gives rise to the cutaneous photosensitivity characteristic of the disease, and in a minority of patients leads to end-stage liver disease necessitating liver transplantation (LT). There is limited information regarding the timing, impact and long-term outcome of LT in such patients, thus we aimed to identify the indications and outcomes of all transplants performed for EPP in the UK using data from the UK Transplant Registry. Between 1987 and 2009, five patients underwent LT for EPP liver disease. Median follow-up was 60 months, and there were two deaths at 44 and 95 months from causes unrelated to liver disease. The remaining recipients are alive at 22.4 years, 61 months and 55 months after transplant. A high rate of postoperative biliary stricturing requiring multiple biliary interventions was observed. Recurrent EPP-liver disease occurred in 4/5 (80%) of patients but graft failure has not been observed. Given the role of biliary obstruction in inducing EPP-mediated liver damage, we suggest that consideration should be given for construction of a Roux loop at the time of transplant. Thus we demonstrate that although EPP liver transplant recipients have a good long-term survival, comparable to patients undergoing LT for other indications, biliary complications and disease recurrence are almost universal, and bone marrow transplantation should be considered where possible

Mechanical stress inhibits early stages of endogenous cell migration: A pilot study in an ex vivo osteocho

Cell migration has a central role in osteochondral defect repair initiation and biomaterial-mediated regeneration. New advancements to reestablish tissue function include biomaterials and factors promoting cell recruitment, differentiation and tissue integration, but little is known about responses to mechanical stimuli. In the present pilot study, we tested the influence of extrinsic forces in combination with biomaterials releasing chemoattractant signals on cell migration. We used an ex vivo mechanically stimulated osteochondral defect explant filled with fibrin/hyaluronan hydrogel, in presence or absence of platelet-derived growth factor-BB or stromal cell-derived factor 1, to assess endogenous cell recruitment into the wound site. Periodic mechanical stress at early time point negatively influenced cell infiltration compared to unloaded samples, and the implementation of chemokines to increase cell migration was not efficient to overcome this negative effect. The gene expression at 15 days of culture indicated a marked downregulation of matrix metalloproteinase (MMP)13 and MMP3, a decrease of β1 integrin and increased mRNA levels of actin in osteochondral samples exposed to complex load. This work using an ex vivo osteochondral mechanically stimulated advanced platform demonstrated that recurrent mechanical stress at early time points impeded cell migration into the hydrogel, providing a unique opportunity to improve our understanding on management of joint injury