4,878 research outputs found
LANDSAT data and interactive computer mapping
The integration of image processing capabilities with interactive computer mapping systems is discussed. It is noted that the accomplishment of this integration will result in powerful geographic information systems which will enhance the applicatons of LANDSAT and other types of remotely sensed data in solving problems in the resource planning and management domain
On The Use and Misuse of Input-Output Based Impact Analysis in Evaluation
Estimates of economic activity generated and jobs created that are derived using input-output analysis are often presented in program evaluations and confused with the benefits resultin g from die program. Two such cases are presented as examples. We argue that for two main reasons this type of analysis con stitutes a misuse of input-output analysis. First, input-output estimates generated using the Keynesian closed versions of input-output models are biased upwards because they ignore the price and financial feedbacks that tend to reduce multipliers in macro-economic models. Second, and more important, it is inappropria te to consider induced effects resulting from a particular program in isolation, because such effects can only be properly considered in the aggr egate at th e level of overall stabilization policy. In this paper we contend that cost-benefit analysis, with its assumption of full employment, is the most appropriate tool for analyzing the benefits resulting from particular programs. Input-output analysis should be confin ed to providing estimates of die industr ial or regional breakdown of the direct impact of a program or of the employment impacts of program spending. It should not be used to generate Keynesian multipliers.input-output analysis, Keynesian multiplier, evaluation
Isolated major aortopulmonary collateral as the sole pulmonary blood supply to an entire lung segment
Congenital systemic-to-pulmonary collateral arteries or major aortopulmonary collaterals are associated with cyanotic congenital heart disease with decreased pulmonary blood flow. Though it is usually associated with congenital heart diseases, there is an increased incidence of isolated acquired aortopulmonary collaterals in premature infants with chronic lung disease. Interestingly, isolated congenital aortopulmonary collaterals can occur without any lung disease, which may cause congestive heart failure and require closure. We present a neonate with an echocardiogram that showed only left-sided heart dilation. Further workup with a CT angiogram demonstrated an anomalous systemic artery from the descending thoracic aorta supplying the left lower lobe. He eventually developed heart failure symptoms and was taken to the catheterization laboratory for closure of the collateral. However, with the collateral being the only source of blood flow to the entire left lower lobe, he required surgical unifocalization. Isolated aortopulmonary collaterals without any other congenital heart disease or lung disease are rare. Our patient is the first reported case to have an isolated aortopulmonary collateral being the sole pulmonary blood supply to an entire lung segment. Due to its rarity, there is still much to learn about the origin and development of these collaterals that possibly developed prenatally
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Microbial D/H fractionation in extraterrestrial materials: application to micrometeorites and Mars
High D/H terrestrial alteration of micrometeorites is described and suggested to be a result of microbial isotopic fractionation by methanogens. Applications to other planetary materials, including martian meteorites, are also considered
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Ar-Ar age and halogen characteristics of nakhlite MIL 03346: records of crustal processes on Mars
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Cryptoendolith communities in Antarctic dry valley region sandstones: Potential analogues of Martian life-forms
We are studying cryptoendolith-bearing Antarctic sandstones, to determine if the microbes alter the elemental composition of the rocks. If there is an effect, then it might be a tracer for the presence of micro-organisms in martian surface materials
The structure of borders in a small world
Geographic borders are not only essential for the effective functioning of
government, the distribution of administrative responsibilities and the
allocation of public resources, they also influence the interregional flow of
information, cross-border trade operations, the diffusion of innovation and
technology, and the spatial spread of infectious diseases. However, as growing
interactions and mobility across long distances, cultural, and political
borders continue to amplify the small world effect and effectively decrease the
relative importance of local interactions, it is difficult to assess the
location and structure of effective borders that may play the most significant
role in mobility-driven processes. The paradigm of spatially coherent
communities may no longer be a plausible one, and it is unclear what structures
emerge from the interplay of interactions and activities across spatial scales.
Here we analyse a multi-scale proxy network for human mobility that
incorporates travel across a few to a few thousand kilometres. We determine an
effective system of geographically continuous borders implicitly encoded in
multi-scale mobility patterns. We find that effective large scale boundaries
define spatially coherent subdivisions and only partially coincide with
administrative borders. We find that spatial coherence is partially lost if
only long range traffic is taken into account and show that prevalent models
for multi-scale mobility networks cannot account for the observed patterns.
These results will allow for new types of quantitative, comparative analyses of
multi-scale interaction networks in general and may provide insight into a
multitude of spatiotemporal phenomena generated by human activity.Comment: 9 page
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