Algebraic and combinatorial codimension-1 transversality

The Waldhausen construction of Mayer-Vietoris splittings of chain complexes over an injective generalized free product of group rings is extended to a combinatorial construction of Seifert-van Kampen splittings of CW complexes with fundamental group an injective generalized free product.Comment: Published by Geometry and Topology Monographs at http://www.maths.warwick.ac.uk/gt/GTMon7/paper6.abs.htm

On the non-integrability of the Popowicz peakon system

We consider a coupled system of Hamiltonian partial differential equations introduced by Popowicz, which has the appearance of a two-field coupling between the Camassa-Holm and Degasperis-Procesi equations. The latter equations are both known to be integrable, and admit peaked soliton (peakon) solutions with discontinuous derivatives at the peaks. A combination of a reciprocal transformation with Painlev\'e analysis provides strong evidence that the Popowicz system is non-integrable. Nevertheless, we are able to construct exact travelling wave solutions in terms of an elliptic integral, together with a degenerate travelling wave corresponding to a single peakon. We also describe the dynamics of N-peakon solutions, which is given in terms of an Hamiltonian system on a phase space of dimension 3N.Comment: 8 pages, AIMS class file. Proceedings of AIMS conference on Dynamical Systems, Differential Equations and Applications, Arlington, Texas, 200

From "land to the tiller" to the "new landlords"? The debate over Vietnam's latest land reforms

Between Vietnam’s independence and its reunification in 1975, the country’s socialist land tenure system was underpinned by the principle of “land to the tiller”. During this period, government redistributed land to farmers that was previously owned by landlords. The government’s “egalitarian” approach to land access was central to the mass support that it needed during the Indochinese war. Even when the 1993 Land Law transitioned agricultural land from collectivized to household holdings with 20-year land use certificates, the “land to the tiller” principle remained largely sacrosanct in state policy. Planned amendments to the current Land Law (issued in 2013), however, propose a fundamental shift from “land to the tiller” to the concentration of land by larger farming concerns, including private sector investors. This is explained as being necessary for the modernization of agricultural production. The government’s policy narrative concerning this change emphasizes the need to overcome the low productivity that arises from land fragmentation, the prevalence of unskilled labor and resource shortages among smallholders. This is contrasted with the readily available resources and capacity of the private sector, together with opportunities for improved market access and high-tech production systems, if holdings were consolidated by companies. This major proposed transition in land governance has catalyzed heated debate over the potential risks and benefits. Many perceive it as a shift from a “pro-poor” to “pro-rich” policy, or from “land to the tiller” to the establishment of a “new landlord”—with all the historical connotations that this badge invokes. Indeed, the growing level of public concern over land concentration raises potential implications for state legitimacy. This paper examines key narratives on the government-supported land concentration policy, to understand how the risks, benefits and legitimacy of the policy change are understood by different stakeholders. The paper considers how the transition could change land access and governance in Vietnam, based on early experience with the approach.This research was partially supported the Australian Research Council’s Discovery Projects funding scheme (project DP180101495)

Nuclear and cytoplasmic shuttling of TRADD induces apoptosis via different mechanisms

The adapter protein tumor necrosis factor receptor (TNFR)1–associated death domain (TRADD) plays an essential role in recruiting signaling molecules to the TNFRI receptor complex at the cell membrane. Here we show that TRADD contains a nuclear export and import sequence that allow shuttling between the nucleus and the cytoplasm. In the absence of export, TRADD is found within nuclear structures that are associated with promyelocytic leukemia protein (PML) nuclear bodies. In these structures, the TRADD death domain (TRADD-DD) can activate an apoptosis pathway that is mechanistically distinct from its action at the membrane-bound TNFR1 complex. Apoptosis by nuclear TRADD-DD is promyelocytic leukemia protein dependent, involves p53, and is inhibited by Bcl-xL but not by caspase inhibitors or dominant negative FADD (FADD-DN). Conversely, apoptosis induced by TRADD in the cytoplasm is resistant to Bcl-xL, but sensitive to caspase inhibitors and FADD-DN. These data indicate that nucleocytoplasmic shuttling of TRADD leads to the activation of distinct apoptosis mechanisms that connect the death receptor apparatus to nuclear events

An interprofessional urban health elective focused on the social determinants of health

Background: More than half of the world’s population now lives in cities. Health professionals should understand how social factors and processes in urban spaces determine individual and population health. We report on lessons from an interprofessional urban health elective developed to focus on the social determinants of health (SDOH).                Methods: An interprofessional committee developed an urban health elective based in downtown Toronto. Course objectives included promoting collaboration to address SDOH, identifying barriers to care, accessing community-based resources, and learning to advocate at individual- and community-levels.Results: Seventeen students from eight disciplines participated during the 2011-2012 academic year. Sessions were co-facilitated with community partners and community members identified as experts based on their personal experience. Topics included housing, income and food security, Indigenous communities in urban spaces, and advocacy. Students collaborated on self-directed projects, which ranged from literature reviews to policy briefs for government. Students particularly valued learning about community agencies and hearing from people with lived experience.Conclusion: The specific health challenges faced in urban settings can benefit from an interprofessional approach informed by the experiences and needs of patient communities. This elective was innovative in engaging students in interprofessional learning on how health and social agencies collaborate to tackle social determinants in urban spaces.

How solar household systems contribute to resilience

This paper explores the relationship between the energy services provided by solar household devices, and the resilience of their users to climate change

Gender differences in survival among adult patients starting antiretroviral therapy in South Africa: a multicentre cohort study.

Increased mortality among men on antiretroviral therapy (ART) has been documented but remains poorly understood. We examined the magnitude of and risk factors for gender differences in mortality on ART

A Signaling Theory of Unemployment

This paper presents a signaling explanation for unemployment. The basic idea is that employment at an unskilled job may be regarded as a bad signal. Therefore, good workers who are more likely to qualify for employment at a skilled job in the future are better off being unemployed than accepting an unskilled job. We present conditions under which all equilibria satisfying the Cho-Kreps intuitive criterion involve unemployment. However, there always exist budget balancing wage subsidies and taxes that eliminate unemployment. Also, for any unemployment equilibrium, either there always exists a set of Pareto improving wage taxes and subsidies, or we give conditions under which there exists a set of Pareto improving wage taxes and subsidies.