466 research outputs found
ADDITIONALITY AND THE ADOPTION OF FARM CONSERVATION PRACTICES
Replaced with revised version of paper 07/20/11.Conservation programs, matching estimators, additionality, average treatment effects, Environmental Economics and Policy, Land Economics/Use,
Interference filter photometry of periodic comet Ashbrook-Jackson
P/Ashbrook-Jackson has a period of 7.43 years and comes to perihelion at 2.284 AU. It is a low inclination object (12.5 deg) of moderate eccentricity (0.400). In 1963, it made the best possible apparition, coming to perihelion and opposition virtually simultaneously, but no one made physical observations of faint periodic comets in 1963. In 1978 Ashbrook-Jackson came to opposition on Sept. 28, just 40 days after perihelion. It will be just over 100 years before an equally favorable apparition recurs. P/Ashbrook-Jackson was recovered by Pereyra at Cordoba Observatory on April 28, 1977, more than a year and a quarter before perilhelion and already showing a diffuse coma with central condensation. Its helio-centric distance was then 3.7 AU. An extensive program was planned, but equipment problems and weather ultimately limited it to the two nights of data reported here
Venus/Mercury swingby with Venus capsule. Preliminary science objectives and experiments for use in advanced mission studies
Venus/Mercury swingby with Venus capsule - preliminary science objectives and experiments for use in advanced mission studie
Science aspects of a 1980 flyby of Comet Encke with a Pioneer spacecraft
Results are presented of an investigation of the feasibility of a 1980 flyby of Comet Encke using a Pioneer class spacecraft. Specific areas studied include: science objectives and rationale; science observables; effects of encounter velocity; science encounter and targeting requirements; selection and description of science instruments; definition of a candidate science payload; engineering characteristics of suggested payload; value of a separable probe; science instruments for a separable probe; science payload integration problems; and science operations profile
Science aspects of 1980 ballistic missions to comet Encke, using Mariner and Pioneer spacecraft
Science aspects of a 1980 spacecraft reconnaissance of Comet Encke are considered. The mission discussed is a ballistic flyby (more exactly, a fly-through) of P/Encke, using either a spin stabilized spacecraft, without despin of instruments, or a 3-axis stabilized spacecraft
Modelling trade offs between public and private conservation policies
To reduce global biodiversity loss, there is an urgent need to determine the
most efficient allocation of conservation resources. Recently, there has been a
growing trend for many governments to supplement public ownership and
management of reserves with incentive programs for conservation on private
land. At the same time, policies to promote conservation on private land are
rarely evaluated in terms of their ecological consequences. This raises
important questions, such as the extent to which private land conservation can
improve conservation outcomes, and how it should be mixed with more traditional
public land conservation. We address these questions, using a general framework
for modelling environmental policies and a case study examining the
conservation of endangered native grasslands to the west of Melbourne,
Australia. Specifically, we examine three policies that involve: i) spending
all resources on creating public conservation areas; ii) spending all resources
on an ongoing incentive program where private landholders are paid to manage
vegetation on their property with 5-year contracts; and iii) splitting
resources between these two approaches. The performance of each strategy is
quantified with a vegetation condition change model that predicts future
changes in grassland quality. Of the policies tested, no one policy was always
best and policy performance depended on the objectives of those enacting the
policy. This work demonstrates a general method for evaluating environmental
policies and highlights the utility of a model which combines ecological and
socioeconomic processes.Comment: 20 pages, 5 figure
Scientific possibilities of a solar electric powered rendezvous with comet Encke
The minimum scientific spacecraft instrumentation is considered that is likely to result in as complete an understanding of the composition, structure, and activity of a cometary nucleus as is possible without landing on it. The payload will also give useful results on secondary goals of a better understanding of physical processes in the inner and outer coma. Studies of composition, by means of an actual landing on the surface, details of the internal structure of the nucleus, and sample return were considered beyond the scope of this mission
Plural policing in Europe:relationships and governance in contemporary security system
References to ‘plural policing’, ‘policing beyond the police’ and the ‘extended policing family’ are now commonplace in many discussions of policing in late modern societies. There is a danger that claims about the dynamic and changing nature of plural policing themselves become a new orthodoxy and begin to lose a sense of local nuance and recognition of the importance of place-based specificity and context in understanding the particularities of policing. It is this need to unpack the complex ways in which contemporary plural policing is now configured at a local level within different national political environments that provides the underpinning rationale for this Special Issue. Focussing on aspects of relationships and governance in six jurisdictions across northern and western Europe, it provides important insights into how the policies, practices and narratives around plural policing reflect the influence of particular histories and geographies. The first three articles are focused primarily on the relationships which have emerged in the public sector through its own processes of pluralisation, in particular, through the introduction of policing auxiliaries or municipal policing in Scotland, England and The Netherlands. The fourth article considers both relationships and governance in pluralised policing in Paris, France. A detailed analysis of the governance of safety and security is taken up in the final two articles, examining the cases of Austria and Belgium. These articles clearly demonstrate that experiences of pluralised policing vary widely within Europe and call into question the assumed dominance of neo-liberal forces in this area
Venus - Preliminary science objectives and experiments for use in advanced mission studies
Mission planning and experiment design for future Mariner-type Venus space probe
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The Stardust – a successful encounter with the remarkable comet Wild 2
On January 2, 2004 the Stardust spacecraft completed a close flyby of comet Wild2 (P81). Flying at a relative speed of 6.1 km/s within 237km of the 5 km nucleus, the spacecraft took 72 close-in images, measured the flux of impacting particles and did TOF mass spectrometry
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