The horofunction boundary of the Hilbert geometry

We investigate the horofunction boundary of the Hilbert geometry defined on an arbitrary finite-dimensional bounded convex domain D. We determine its set of Busemann points, which are those points that are the limits of `almost-geodesics'. In addition, we show that any sequence of points converging to a point in the horofunction boundary also converges in the usual sense to a point in the Euclidean boundary of D. We prove that all horofunctions are Busemann points if and only if the set of extreme sets of the polar of D is closed in the Painleve-Kuratowski topology.Comment: 24 pages, 2 figures; minor changes, examples adde

ESTIMATION OF EXISTENCE VALUES SOME EMPIRICAL ISSUES

Existence values (EVs) are the values derived from the knowledge that certain species ornatural environments exist. Existence values arc pure public goods and hence lack marketvalues. As income rise and natural environment suffer greater degradation, demand forexistence values is likely to increase. This paper presents results of a contingent valuationsurvey designed to elicit existence values of a tropical rain forest and several issues relatedto estimation of existence values of a global resource.A contingent valuation survey was carried out in order to derive EVs for the Sinharaja RainForest Reserve in Sri Lanka. An open ended question format was used with a neutral trustfund as a payment vehicle. Three samples from Sri Lanka (urban and rural areas distant tothe forest and peripheral villages to the forest) and one remote sample (from UK) were usedin the study. The existence values for different types of users such as educational users.recreational users and non users were derived from the survey.When expressed as percentage of income, willingness to pay values showed cleardifferences among different user types in different samples. On average, local ruraleducational users stated the highest values while remote non-users stated the lowest values.These existence value estimates, notwithstanding the theoretical validity, clearly illustratethe empirical problems related to estimation of existence values.It could be assumed that existence values stated by non-users provide the nearestapproximation for the 'true' existence value of a resource. However, this relates with theprovision of information and the knowledge of the respondent since people derive benefitsdirectly and indirectly and they may be aware or unaware of such benefits emanating fromtropical rain forests.Implications of these findings in designing future existence value estimations and the role ofinformation in survey design are highlighted. Implications for policy at global level,specifically, how mechanisms for appropriation of such values could be developed are alsodiscussed.

Beyond Environmental Economics New Directions for Policy Making

In the 1950s and 1960s economics had its focus on economic growth ignoring the fact that some of theinputs essential to the production process were limited in supply. In other words, the sustainability of thegrowth process was not addressed properly. Since 1970, a number of world views appeared ranging froma support for a market technology driven growth process which is environmentally damaging, through aposition advocating prudent resource management to an ‘eco-preservationist’ positions which explicitlyreject economic growth. Against this background environmental economics became established as a subdiscipline (Pearce and Turner, 1990). Environmental economics (EE) was considered as an opportunity toaccommodate the environmental implications of the growth economy and society within a modified(though not radically different) set of economic models.The subject has developed immensely during the last three decades both in theoretical and empiricalgrounds. Micro level applications of EE include estimating demands for various environmental goods andservices and damage estimations (through various environmental valuation methods), designing ofeconomic instruments, project level cost benefit analyses, aiding renewable and non renewable resourceharvesting decisions. Macro level applications include green accounting (integrating environmentaladditions and depletions into system of national accounts), development of macro level indicators etc.Such applications seem to cover a wide variety of real world issues ranging from biodiversity, energy,agricultural and local pollution issues to global issues such as climate change, ozone depletion andultimately towards the long term survival of mankind. Although Environmental economics seem toaddress these issues quite comprehensively than conventional economics and pure scientific approaches,the outcomes of such applications are often subject to debate. Doubts are being raised mainly fromdifferent disciplines indicating non recognition of their concerns, particularly from ethical, ecological andphilosophical grounds.Most natural resource policy decisions in many countries have made sure that environmental economicvalues are being incorporated. There are however policy gaps, partly due to the yet unresolved theoreticalissues of the subject and partly due to the single disciplinary roots of economics. The subject of ecologicaleconomics arose partly in response to such concerns and enriched the analysis with the incorporation ofecological inter linkages to the economics (Costanza, 1991).The objective of the paper is therefore to first elaborate on the various aspects of the subject that are beingused in the various natural resource management issues. For example, EE provides explanations forresource degradation basically the economic failure arguments and proposes corrections accordingly. Thepaper elaborates on the usefulness of such arguments and the critique, the need for alternativeexplanations.The second section discusses more practical issues, how the decision making has been aided by thediscipline through standard micro level and macro level analysis with special emphasis on Sri Lanka. Italso discusses the drawbacks of the analytical tools especially in relation to the instances where themultidisciplinary integration could enhance the outcome. Some of these integrations are however, onlytheoretical conceptualizations while others have been actually tested in different contexts. The subject ofenvironmental economics has benefited immensely from various other disciplines. The third section ofthis paper is devoted to discuss on such disciplines that could be further integrated in order to widen thescope of the subject

ECOLOGICAL ECONOMICS: A BETTER FRAMEWORK FOR SUSTAINABLE DEVELOPMENT

Sustainable development has been the focus and. the target of many resource managementrelated issues. However, proper definitions and frameworks of action have seemed to begreatly unexplored. This paper aims at providing a framework for sustainable developmentbased on concepts of ecological economics. The main focus will be on the issues of intraand inter generational equity on natural resource use and maintaining non-declining levelsof critical natural capital.The conventional economic view is generally optimistic about the ability of the economicsystem to overcome natural resource depletion with the help of the technological progress.However, conventional approaches in resource economics limit themselves to only optimalrate of exploitation of a natural resource and determination of optimal pollution discharges.Although such approaches are sensitive to scale issues at the micro level, it is insensitive tothe macro level scale of the whole economy relative to the ecosystem. Although the marketprovides space for substituting abundant resources for scarce ones, it is not able toovercome entropy constraints. Such issues are not reflected in Pareto optimality sinceoptimal allocation is independent of whether or not the scale of physical throughput isecologically sustainable.Therefore is important to recognize the existence of a new constraint on the physical scaleof the economy relative to the ecosystem. This constraint has to be set according to thecriteria of sustainability and under such constraint, the market will be able to achieveprices which reflect the social value of sustainability.Unique natural environments and other critical natural capital need special considerationsin economic analysis since technology can do little to replicate their ecological, physicaland geographical characteristics. In order to determine the social cost and benefits of adecision to develop a previously undeveloped area, it is necessary to know both thepreferences of present and future generations who may be affected by that decision. Theexisting valuation frameworks and discounting in cost benefit analysis have inherent biasesagainst future generations. Recognition of such facts and identifying the means ofminimizing such biases are essential in achieving sustainable development.Ecological economic framework is essentially an extension of environment and resourceeconomics in to the explicit analysis of biophysical constraints and equity amonggenerations.

A discourse analysis of trainee teacher identity in online discussion forums

Teacher education involves an identity transformation for trainees from being a student to being a teacher. This discourse analysis examined the online discussion board communications of a cohort of trainee teachers to better understand the situated identities of the trainees and how they were presented online. Their discussion board posts were the primary method of communication during placement periods and, as such, provided insight into how the trainees situated their identities in terms of being a student or being a teacher. During the analysis, the community boundaries, language and culture were explored along with the tutor's power and role in the identity transformation process. This involved looking at the lexis used by the students, the use of pronouns to refer to themselves and others such as teachers and pupils, the types of messages allowed in the community and the effect of the tutor's messages on their communication. The research found that the trainees felt comfortable with teaching but did not feel like teachers during the course. Tutors and school teachers need to develop an awareness of the dual nature of trainees' identities and help promote the transition from student to teacher. In the beginning of the course, trainees should be familiarised with teacher vocabulary and practical concepts in addition to pedagogical theory. Towards the end of the course, trainee identity as teachers could be promoted through the use of authentic assessments that mirror real teacher tasks and requirements

Trace Spaces: an Efficient New Technique for State-Space Reduction

State-space reduction techniques, used primarily in model-checkers, all rely on the idea that some actions are independent, hence could be taken in any (respective) order while put in parallel, without changing the semantics. It is thus not necessary to consider all execution paths in the interleaving semantics of a concurrent program, but rather some equivalence classes. The purpose of this paper is to describe a new algorithm to compute such equivalence classes, and a representative per class, which is based on ideas originating in algebraic topology. We introduce a geometric semantics of concurrent languages, where programs are interpreted as directed topological spaces, and study its properties in order to devise an algorithm for computing dihomotopy classes of execution paths. In particular, our algorithm is able to compute a control-flow graph for concurrent programs, possibly containing loops, which is "as reduced as possible" in the sense that it generates traces modulo equivalence. A preliminary implementation was achieved, showing promising results towards efficient methods to analyze concurrent programs, with very promising results compared to partial-order reduction techniques

GLASS RECYCLING IN SRI LANKA: A FINANCIAL ANALYSIS

Glass recycling is the use of secondary raw materials or post consumer glass waste for the manufacturing of new or similar products. Glass Company of Sri Lanka is manufacturing glass containers and also involved in glass container recycling in Sri Lanka. The main purpose of the study is to carry out a financial analysis of glass recycling from company point of view along with an analysis on possible best practices that could enhance the recycling behaviours of individuals. The primary data was gathered from a household questionnaire survey which was conducted in Western Province of Sri Lanka. Sample of 150 households were selected from 8 GN divisions in  Colombo, Gampaha and Kaluthara districts representing two Municipal councils, three urban councils, and three Pradeshiya Sabha. Six different scenarios were proposed for the respondents in order to generate information on practices that are most preferred by them and on their willing levels of recycling under each scenario. Results revealed that the best scenario was the introduction of door to door collectors which yielded highest net present value of Rs. Mn 1,517.39 at 10% discount rate and resulted 7.98% of net profit increase from the current glass recycling process of Glass Company

Current distribution and abundance of slender lorises (Loris tardigradus and L. Iydekkerianus) in Sri Lanka

Two species of slender lorises are currently recognized in Sri Lanka. They are Sri Lanka red slenderloris (Loris tardigradusj and Grey slender loris (L. lydekkerianus i, with four currently recognizedsub-species; viz. Western red slender loris (L. t. tardigradus), Montane slender loris (L. t.nycticeboidesi, Northern grey slender loris (L. 1.nordicusi, and Highland slender loris (L. 1.grandis).The objective of this survey was to map the distribution and estimate the abundance of lorises in SriLanka. The study was initiated in 2002 and continues to date. Thus far forty-five sites across all ofthe ecological zones have been surveyed covering approximately 400 krn-. In six of these sites, loriseswere not recorded. Of the other 39 sites, 223 sightings of slender loris (L. t. tardigradus (n = 86), L.t. nycticeboides (n = 3), L. 1. nordicus (n = 122), and L. l. grandis (n = 12). Abundance estimates, 'base on sightings of animals krn', were: L. t. tardigradus (0.5-8), L. t. nycticeboides (0.03), L. I.nordicus (0.7-13). and L. 1. grandis (0.3-4) were recorded. The abundance of lorises varied indifferent habitat types with the highest abundance oflorises occurring in the dry zone monsoon forests.The least abundance of lorises was recorded in the cloud forest

EVALUATION OF URBAN AIR POLLUTION COST A CASE STUDY IN THE COLOMBO CITY

Air pollution is arguably the most important. in terms of economics cost, of thevarious types of pollution caused by transport and industrial activities and itseffects have been widely studied in other countries. However, direct studies havenot been undertaken to measure the economics cost of air pollution in Sri Lanka.Concern for air pollution in Sri Lanka is focused mainly in Colombo. AlthoughColombo air pollution level is less than many Asian countries, recent monitoringresults show that air pollution from particulate matter and Sulfur is well above theWHO recommended levelThe contingent valuation method was used to estimate the air pollution cost anddata was collected from a contingent valuation survey carried out in the Fort andPettah areas. Respondents' willingness to pay values were obtained for ahypothetical market presented. The results were consistent with the economictheory. Aggregated cost of air pollution for the country was Rs.55 million peryear. This value may help cost benefit analysis of air quality managementprogrammes and other related development policy and programs in Sri Lanka.