Temporary carbon storage and discount rates

Several approaches have been proposed for accounting for temporary carbon sequestration in land-use change and forestry projects that are implemented to offset permanent emissions of carbon dioxide from the energy sector. In a previous paper, we evaluated the incentives provided by some of these approaches. In this paper, we investigate further what we call the “ideal” accounting system, where the forest owner would be paid for carbon sequestration as the service is provided and redeem payments when the forest is harvested and carbon is released back into the atmosphere. We demonstrate how discounting affects the net present value of the forest when carbon sequestration is taken into account under this ideal system. Not all carbon is released back into the atmosphere at harvest, however, since a large proportion may remain fixed in forest products for many years. Here, we compare the profitability of the forest under full redemption of credits at harvest, with partial redemption of credits at harvest followed by annual redemption post-harvest as the carbon decays in a durable forest product. The analysis is based on simulation of farm-forestry systems in south-eastern Australia.carbon accounting, reforestation, discounting, bioeconomics, Environmental Economics and Policy, Land Economics/Use,

Carbon-accounting methods and reforestation incentives

The emission of greenhouse gases, particularly carbon dioxide, and the consequent potential for climate change are the focus of increasing international concern. Temporary land-use change and forestry projects (LUCF) can be implemented to offset permanent emissions of carbon dioxide from the energy sector. Several approaches to accounting for carbon sequestration in LUCF projects have been proposed. In the present paper, the economic implications of adopting four of these approaches are evaluated in a normative context. The analysis is based on simulation of Australian farm–forestry systems. Results are interpreted from the standpoint of both investors and landholders. The role of baselines and transaction costs are discussed.Resource /Energy Economics and Policy,

Extending an eco-evolutionary understanding of biofilm-formation at the air-liquid interface to community biofilms

Growing bacterial populations diversify to produce a number of competing lineages. In the Pseudomonas fluorescens SBW25 model system, Wrinkly Spreader mutant lineages, capable of colonising the air-liquid interface of static microcosms by biofilm-formation, rapidly appear in diversifying populations with a fitness advantage over the ancestral wild-type strain. Similarly, a biofilm is rapidly produced by a community containing many biofilm-competent members, and selection by serial transfer of biofilm samples across microcosms results in a gradually changing community structure. Both the adaptive radiation producing Wrinkly Spreaders and the succession of biofilm communities in these static microcosms can be understood through evolutionary ecology in which ecological interactions and evolutionary processes are combined. Such eco-evolutionary dynamics are especially important for bacteria, as rapid growth, high population densities and strong selection in the context of infections can lead to fast changes in disease progression and resistance phenotypes, while similar changes in community function may also affect many microbially-mediated biotechnological and industrial processes. Evolutionary ecology provides an understanding of why bacterial biofilms are so prevalent and why they are such a successful colonisation strategy, and it can be directly linked to molecular analyses to understand the importance of pathways and responses involved in biofilm-formation

OPTIMAL MANAGEMENT OF GIANT-CLAM FARMING IN SOLOMON ISLANDS

Giant-clam farming is undertaken by coastal villagers in Solomon Islands as part of a research and development project of the International Center for Living Aquatic Resources Management (ICLARM). The production technology is simple and does not require a large capital investment. The main inputs are clam seed, labour and time. Labour is used for activities such as seeding, cleaning, thinning and harvesting. In this paper, a bioeconomic model is used to explore optimal farm management. The theoretical basis for this analysis is found in the economic theory of optimal forestry exploitation. The management variables considered are husbandry applied to cleaning and the frequency with which thinning is undertaken. The optimal cycle-length is determined for both a single clam harvest and multiple harvests. The labour requirements of various management scenarios are identified for the multiple-cycle case.bioeconomics, giant clams, subsistence mariculture, Farm Management,

A Convenient Synthetic Route to Partial-Cone p-Carboxylatocalix[4]arenes.

p-Carboxylatocalix[n]arenes have emerged as useful building blocks for the construction of a diverse range of supramolecular assemblies. A convenient route to a p-carboxylatocalix[4]arene that is locked in a partial-cone conformation is presented. The conformation gives the molecule markedly different topological directionality relative to those previously used in self- and metal-directed assembly studies

Penetrating the air-liquid interface is the key to colonization and wrinkly spreader fitness

In radiating populations of Pseudomonas fluorescens SBW25, adaptive wrinkly spreader (WS) mutants are able to gain access to the air–liquid (A–L) interface of static liquid microcosms and achieve a significant competitive fitness advantage over other non-biofilm-forming competitors. Aerotaxis and flagella-based swimming allows SBW25 cells to move into the high-O2 region located at the top of the liquid column and maintain their position by countering the effects of random cell diffusion, convection and disturbance (i.e. physical displacement). However, wild-type cells showed significantly lower levels of enrichment in this region compared to the archetypal WS, indicating that WS cells employ an additional mechanism to transfer to the A–L interface where displacement is no longer an issue and a biofilm can develop at the top of the liquid column. Preliminary experiments suggest that this might be achieved through the expression of an as yet unidentified surface active agent that is weakly associated with WS cells and alters liquid surface tension, as determined by quantitative tensiometry. The effect of physical displacement on the colonization of the high-O2 region and A–L interface was reduced through the addition of agar or polyethylene glycol to increase liquid viscosity, and under these conditions the competitive fitness of the WS was significantly reduced. These observations suggest that the ability to transfer to the A–L interface from the high-O2 region and remain there without further expenditure of energy (through, for example, the deployment of flagella) is a key evolutionary innovation of the WS, as it allows subsequent biofilm development and significant population increase, thereby affording these adaptive mutants a competitive fitness advantage over non-biofilm-forming competitors located within the liquid column

The Most Distant Stars in the Milky Way

We report on the discovery of the most distant Milky Way (MW) stars known to date: ULAS J001535.72$+$015549.6 and ULAS J074417.48$+$253233.0. These stars were selected as M giant candidates based on their infrared and optical colors and lack of proper motions. We spectroscopically confirmed them as outer halo giants using the MMT/Red Channel spectrograph. Both stars have large estimated distances, with ULAS J001535.72$+$015549.6 at $274 \pm 74$ kpc and ULAS J074417.48$+$253233.0 at 238 $\pm$ 64 kpc, making them the first MW stars discovered beyond 200 kpc. ULAS J001535.72$+$015549.6 and ULAS J074417.48$+$253233.0 are both moving away from the Galactic center at $52 \pm 10$ km s$^{-1}$ and $24 \pm 10$ km s$^{-1}$, respectively. Using their distances and kinematics, we considered possible origins such as: tidal stripping from a dwarf galaxy, ejection from the MW's disk, or membership in an undetected dwarf galaxy. These M giants, along with two inner halo giants that were also confirmed during this campaign, are the first to map largely unexplored regions of our Galaxy's outer halo.Comment: Accepted and in print by ApJL. Seven pages, 2 figure

Kinetic and sequence-structure-function analysis of known LinA variants with different hexachlorocyclohexane isomers

BACKGROUND Here we report specific activities of all seven naturally occurring LinA variants towards three different isomers, α, γ and δ, of a priority persistent pollutant, hexachlorocyclohexane (HCH). Sequence-structure-function differences contributing to the differences in their stereospecificity for α-, γ-, and δ-HCH and enantiospecificity for (+)- and (-)-α -HCH are also discussed. METHODOLOGY/PRINCIPAL FINDINGS Enzyme kinetic studies were performed with purified LinA variants. Models of LinA2(B90A) A110T, A111C, A110T/A111C and LinA1(B90A) were constructed using the FoldX computer algorithm. Turnover rates (min(-1)) showed that the LinAs exhibited differential substrate affinity amongst the four HCH isomers tested. α-HCH was found to be the most preferred substrate by all LinA's, followed by the γ and then δ isomer. CONCLUSIONS/SIGNIFICANCE The kinetic observations suggest that LinA-γ1-7 is the best variant for developing an enzyme-based bioremediation technology for HCH. The majority of the sequence variation in the various linA genes that have been isolated is not neutral, but alters the enantio- and stereoselectivity of the encoded proteins.This work was supported by the Indo-Australian Biotechnology Fund from the Department of Education Science and Technology (DEST), Australia and the Department of Biotechnology (DBT), India

Risk Factors for Long-Term Coronary Artery Calcium Progression in the Multi-Ethnic Study of Atherosclerosis.

BackgroundCoronary artery calcium (CAC) detected by noncontrast cardiac computed tomography scanning is a measure of coronary atherosclerosis burden. Increasing CAC levels have been strongly associated with increased coronary events. Prior studies of cardiovascular disease risk factors and CAC progression have been limited by short follow-up or restricted to patients with advanced disease.Methods and resultsWe examined cardiovascular disease risk factors and CAC progression in a prospective multiethnic cohort study. CAC was measured 1 to 4 times (mean 2.5 scans) over 10 years in 6810 adults without preexisting cardiovascular disease. Mean CAC progression was 23.9 Agatston units/year. An innovative application of mixed-effects models investigated associations between cardiovascular disease risk factors and CAC progression. This approach adjusted for time-varying factors, was flexible with respect to follow-up time and number of observations per participant, and allowed simultaneous control of factors associated with both baseline CAC and CAC progression. Models included age, sex, study site, scanner type, and race/ethnicity. Associations were observed between CAC progression and age (14.2 Agatston units/year per 10 years [95% CI 13.0 to 15.5]), male sex (17.8 Agatston units/year [95% CI 15.3 to 20.3]), hypertension (13.8 Agatston units/year [95% CI 11.2 to 16.5]), diabetes (31.3 Agatston units/year [95% CI 27.4 to 35.3]), and other factors.ConclusionsCAC progression analyzed over 10 years of follow-up, with a novel analytical approach, demonstrated strong relationships with risk factors for incident cardiovascular events. Longitudinal CAC progression analyzed in this framework can be used to evaluate novel cardiovascular risk factors