Optimal taxation of risky entrepreneurial capital

We study optimal taxation in a model with endogenous financial frictions, risky investment and occupational choice, where the wealth distribution affects how efficiently capital is used. The planner chooses linear taxes on wealth, capital and labor income to maximize the steady state utility of a newborn agent. Most agents in the model are poor, leading to an equity motive for taxation. We calibrate the model to the US economy and find low positive levels of optimal capital income and wealth taxes. We express optimal tax rates as a closed-form function of the size of tax bases and their elasticities with respect to tax rates, highlighting the forces behind the result. Because financial frictions are endogenous, higher capital income tax rates tighten financial frictions and reduce output. Thus, optimal capital income taxes are lower than in models with exogenous frictions

A synthesis of past, current and future research for protection and management of papyrus (Cyperus papyrus L.) wetlands in Africa

Papyrus wetlands (dominated by the giant sedge Cyperus papyrus L.) occur throughout eastern, central and southern Africa and are important for biodiversity, for water quality and quantity regulation and for the livelihoods of millions of people. To draw attention to the importance of papyrus wetlands, a special session entitled ‘‘The ecology of livelihoods in papyrus wetlands’’ was organized at the 9th INTECOL Wetlands Conference in Orlando, Florida in June 2012. Papers from the session, combined with additional contributions, were collected in a special issue of Wetlands Ecology and Management. The current paper reviews ecological and hydrological characteristics of papyrus wetlands, summarizes their ecosystem services and sustainable use, provides an overview of papyrus research to date, and looks at policy development for papyrus wetlands. Based on this review, the paper provides a synthesis of research and policy priorities for papyrus wetlands and introduces the contributions in the special issue. Main conclusions are that (1) there is a need for better estimates of the area covered by papyrus wetlands. Limited evidence suggests that the loss of papyrus wetlands is rapid in some areas; (2) there is a need for a better understanding and modelling of the regulating services of papyrus wetlands to support trade-off analysis and improve economic valuation; (3) research on papyrus wetlands should include assessment of all ecosystem services (provisioning, regulating, habitat, cultural) so that trade-offs can be determined as the basis for sustainable management strategies (‘wise use’); (4) more research on the governance, institutional and socio-economic aspects of papyrus wetlands is needed to assist African governments in dealing with the challenges of conserving wetlands in the face of growing food security needs and climate change. The papers in the special issue address a number of these issues

Urbanisation affects ecosystem functioning more than structure in tropical streams

Urbanisation poses a clear threat to tropical freshwater streams, yet fundamental knowledge gaps hinder our ability to effectively conserve stream biodiversity and preserve ecosystem functioning. Here, we studied the impact of urbanisation on structural and functional ecosystem responses in low-order streams in Singapore, a tropical city with a mosaic landscape of protected natural forests, managed buffer zones (between forest and open-country habitats), and built-up urban areas. We quantified an urbanisation gradient based on landscape, in-stream, and riparian conditions, and found an association between urbanisation and pollution-tolerant macroinvertebrates (e.g. freshwater snail and worm species) in litter bags. We also found greater macroinvertebrate abundance (mean individuals bag−1; forest: 30.3, buffer: 70.1, urban: 109.0) and richness (mean taxa bag−1; forest: 4.53, buffer: 4.75, urban: 7.50) in urban streams, but similar diversity across habitats. Higher levels of primary productivity (measured from algal accrual on ceramic tiles) and microbial decomposition (measured from litter-mass loss in mesh bags) at urban sites indicate rapid microbial activity at higher light, temperature, and nutrient levels. We found that urbanisation affected function 32% more than structure in the studied tropical streams, likely driven by greater algal growth in urban streams. These changes in ecological processes (i.e. ecosystem functioning) possibly lead to a loss of ecosystem services, which would negatively affect ecology, society, and economy. Our results point to possible management strategies (e.g. increasing vegetation density through buffer park creation) to reduce the impacts of urbanisation, restore vital ecosystem functions in tropical streams, and create habitat niches for native species

Bathymetry of lake Bogoria, Kenya

This paper presents the first bathymetric map for the approximately 17 km by 2 km alkaline Lake Bogoria situated in the eastern Rift Valley of Kenya. Longitudinal and transverse cross sections of the lake are also provided. Northern, central and southern basins of the lake had maximum depths of 5.9 m, 10.2 m and 8.4 m respectively. Average depth was 5.68 m and volume was calculated to be 164 x106 m3.Journal of East African Natural History Vol. 92 (1&2) 2003: pp. 107-11

STUDIES ON TEACHING BIODIVERSITY BY THE USE OF ONLINE INTERACTIVE IDENTIFICATION TOOLS

Modern teaching methods and learning with educational soft allow education to adapt to current and future needs of modern society. Computer-assisted learning for specific biodiversity study with on line K2N tools facilitate the work of learning capacity for observation, consolidation of knowledge and intellectual skills. Interactive educational tools are innovative educational solutions, student-centered, replace conventional identification keys of identifying the organisms and exploit the interdisciplinary character: digital skills, concepts of plant morphology, systematic botany. Through modern and accessible design makes easier the learning process of main morphological characteristics of living organisms, allowing the correct identification and recognition of the species studied. E-Learning development platform, availability of instruments in various forms is particularly important because students can access the tools outside the classroom, the study of ecosystems or visits home, strengthening the knowledge. Following the comparative study conducted at two classes of students using the teaching with K2N tools approach to one class test results showed the effectiveness of their particular teaching-learning-evaluation