RESOURCE OR NUISANCE? MANAGING AFRICAN ELEPHANTS AS A MULTI-USE SPECIES

Increasing human interference with natural systems causes us to re-think our perception of wildlife species and the economic choices society makes with regards to their management. Accordingly, we generalize existing 'bioeconomic' models by proposing an economically-based classification of species. The theoretical model is applied to the case of African elephant management. We demonstrate that the classification of the steady state population of a species depends on both species' density and economic factors. Our main results are threefold. First, we demonstrate the classification-dependent possibility of multiple equilibria and perverse comparative statics for multi-use species. Second, upon comparing the optimal stock of a multi-use species to the stock under an open access regime, we find that the ranking in terms of abundance is ambiguous. Finally, and consistent with existing literature on resource management in a second-best world, our case study supports the idea that trade measures have ambiguous effects on wildlife abundance under open access.Resource /Energy Economics and Policy,

Coevolutionary Investments in Human Speech and Trade

We propose a novel explanation for the emergence of language in modern humans, and the lack thereof in other hominids. A coevolutionary process, where trade facilitates speech and speech facilitates trade, driven by expectations and potentially influenced by geography, gives rise to multiple stable development trajectories. While the trade-speech equilibrium is not an inevitable outcome for modern humans, we do find that it is a relatively likely result given that our species evolved in Africa under climatic conditions supporting relatively high population densities.Institutional and Behavioral Economics,

Competitive Exclusion, Diversification, and the Origins of Agriculture

The beginnings of agriculture, or the agricultural revolution, is now recognized to be the widespread adoption of known practices – a change in behavior – as opposed to a phenomenon of discovery and innovation. In this paper, we combine elements of three theories—climate change, property rights, and competitive exclusion—to create a paleoeconomic model of agriculture and its diffusion. We focus on climate change as a necessary trigger, which combined with group property rights and competitive exclusion processes produced conditions sufficient for the diffusion of early agriculture. In contrast to other models in which farming emerges as technological progress or climate makes it a more productive option than hunting, farming emerges in our model even if farmers are poor hunters and cannot sustain themselves with agriculture alone. Moreover, the strategy of farming can invade the system even if farmers initially generate lower per capita consumption than hunters. The key is that the simple innovation of property rights over an immobile resource can help to insulate farmers from competitive ecological pressures.Farm Management, Research and Development/Tech Change/Emerging Technologies,

Unconditional Transfers and Tropical Forest Conservation: Evidence from a Randomized Control Trial in Sierra Leone

Unconditional conservation payments are increasingly used by conservation non-governmental organizations to further their environmental objectives. One key objective in many conservation projects that use such unconditional payments schemes is the protection of tropical forest ecosystems in buffer zone areas around protected parks where the scope of instating mandatory restrictions is more limited. We use a randomized controlled trial to evaluate the impact of unconditional livelihood payments to local communities on land use outside a protected area – the Gola Rainforest National Park – which is a biodiversity hotspot on the border of Sierra Leone and Liberia. High resolution RapidEye satellite imagery from before and after the intervention was used to determine land use changes in treated and control villages. We find support for the hypothesis that unconditional payments, in this setting, increase land clearance in the short run. The study constitutes one of the first attempts to use evidence from a randomized control trial to evaluate the efficacy of conservation payments and provides insights for further research.Cambridge Conservation Initiative International Initiative for Impact Evaluation (grant # TW1.1042) NWO (#45-14-001 and #451-14-001

Studying Paths of Participation in Viral Diffusion Process

Authors propose a conceptual model of participation in viral diffusion process composed of four stages: awareness, infection, engagement and action. To verify the model it has been applied and studied in the virtual social chat environment settings. The study investigates the behavioral paths of actions that reflect the stages of participation in the diffusion and presents shortcuts, that lead to the final action, i.e. the attendance in a virtual event. The results show that the participation in each stage of the process increases the probability of reaching the final action. Nevertheless, the majority of users involved in the virtual event did not go through each stage of the process but followed the shortcuts. That suggests that the viral diffusion process is not necessarily a linear sequence of human actions but rather a dynamic system.Comment: In proceedings of the 4th International Conference on Social Informatics, SocInfo 201

Violent conflict and behavior:A field experiment in Burundi

We use a series of field experiments in rural Burundi to examine the impact of exposure to conflict on social, risk, and time preferences. We find that conflict affects behavior: individuals exposed to violence display more altruistic behavior towards their neighbors, are more risk-seeking, and have higher discount rates. Large adverse shocks can thus alter savings and investments decisions, and potentially have long-run consequences—even if the shocks themselves are temporary

Molecular Electroporation and the Transduction of Oligoarginines

Certain short polycations, such as TAT and polyarginine, rapidly pass through the plasma membranes of mammalian cells by an unknown mechanism called transduction as well as by endocytosis and macropinocytosis. These cell-penetrating peptides (CPPs) promise to be medically useful when fused to biologically active peptides. I offer a simple model in which one or more CPPs and the phosphatidylserines of the inner leaflet form a kind of capacitor with a voltage in excess of 180 mV, high enough to create a molecular electropore. The model is consistent with an empirical upper limit on the cargo peptide of 40--60 amino acids and with experimental data on how the transduction of a polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of arginines in the CPP and on the CPP concentration. The model makes three testable predictions.Comment: 15 pages, 5 figure

Dissecting the illegal ivory trade: an analysis of ivory seizures data

Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions--Transactions Index--and the total weight of illegal ivory transactions--Weights Index--at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants

Diffusion of treatment in social networks and mass drug administration

Information, behaviours, and technologies spread when people interact. Understanding these interactions is critical for achieving the greatest diffusion of public interventions. Yet, little is known about the performance of starting points (seed nodes) for diffusion. We track routine mass drug administration—the large-scale distribution of deworming drugs—in Uganda. We collect friendship networks, socioeconomic factors, and treatment delivery outcomes for 16,357 individuals in 3,491 households of 17 rural villages. Each village has two community medicine distributors (CMDs), who are the seed nodes and responsible for administering treatments. Here we show that CMDs with tightly-knit (clustered) friendship connections achieve the greatest reach and speed of treatment coverage. Importantly, we demonstrate that clustering predicts diffusion through social networks when spreading relies on contact with seed nodes whilst centrality is unrelated to diffusion. Clustering should be considered when selecting seed nodes for large-scale treatment campaigns.Financially supported by the Vice Chancellor’s Fund of the University of Cambridge, the Schistosomiasis Control Initiative, the Wellcome Trust (Programme grant 083931/Z/07/Z to D.W.D), and the Netherlands Organization for Scientific Research (N.W.O. grant 452-04-333 to E.B.)

In Vivo, Multimodal Imaging of B Cell Distribution and Response to Antibody Immunotherapy in Mice

BACKGROUND: B cell depletion immunotherapy has been successfully employed to treat non-Hodgkin's lymphoma. In recent years, increasing attention has been directed towards also using B-cell depletion therapy as a treatment option in autoimmune disorders. However, it appears that the further development of these approaches will depend on a methodology to determine the relation of B-cell depletion to clinical response and how individual patients should be dosed. Thus far, patients have generally been followed by quantification of peripheral blood B cells, but it is not apparent that this measurement accurately reflects systemic B cell dynamics. METHODOLOGY/PRINCIPAL FINDINGS: Cellular imaging of the targeted population in vivo may provide significant insight towards effective therapy and a greater understanding of underlying disease mechanics. Superparamagnetic iron oxide (SPIO) nanoparticles in concert with near infrared (NIR) fluorescent dyes were used to label and track primary C57BL/6 B cells. Following antibody mediated B cell depletion (anti-CD79), NIR-only labeled cells were expeditiously cleared from the circulation and spleen. Interestingly, B cells labeled with both SPIO and NIR were not depleted in the spleen. CONCLUSIONS/SIGNIFICANCE: Whole body fluorescent tracking of B cells enabled noninvasive, longitudinal imaging of both the distribution and subsequent depletion of B lymphocytes in the spleen. Quantification of depletion revealed a greater than 40% decrease in splenic fluorescent signal-to-background ratio in antibody treated versus control mice. These data suggest that in vivo imaging can be used to follow B cell dynamics, but that the labeling method will need to be carefully chosen. SPIO labeling for tracking purposes, generally thought to be benign, appears to interfere with B cell functions and requires further examination