37,444 research outputs found
Inclusive Economy Indicators: Framework & Indicator Recommendations
This report provides a summary of our research and recommendations for indicators to measure inclusive economies
Competition Among Spatially Differentiated Firms: An Empirical Model with an Application to Cement
The theoretical literature of industrial organization shows that the distances between consumers and firms have first-order implications for competitive outcomes whenever transportation costs are large. To assess these effects empirically, we develop a structural model of competition among spatially differentiated firms and introduce a GMM estimator that recovers the structural parameters with only regional-level data. We apply the model and estimator to the portland cement industry. The estimation fits, both in-sample and out-of-sample, demonstrate that the framework explains well the salient features of competition. We estimate transportation costs to be $0.30 per tonne-mile, given diesel prices at the 2000 level, and show that these costs constrain shipping distances and provide firms with localized market power. To demonstrate policy-relevance, we conduct counter-factual simulations that quantify competitive harm from a hypothetical merger. We are able to map the distribution of harm over geographic space and identify the divestiture that best mitigates harm.
Performance of Network and Service Monitoring Frameworks
The efficiency and the performance of anagement systems is becoming a hot
research topic within the networks and services management community. This
concern is due to the new challenges of large scale managed systems, where the
management plane is integrated within the functional plane and where management
activities have to carry accurate and up-to-date information. We defined a set
of primary and secondary metrics to measure the performance of a management
approach. Secondary metrics are derived from the primary ones and quantifies
mainly the efficiency, the scalability and the impact of management activities.
To validate our proposals, we have designed and developed a benchmarking
platform dedicated to the measurement of the performance of a JMX manager-agent
based management system. The second part of our work deals with the collection
of measurement data sets from our JMX benchmarking platform. We mainly studied
the effect of both load and the number of agents on the scalability, the impact
of management activities on the user perceived performance of a managed server
and the delays of JMX operations when carrying variables values. Our findings
show that most of these delays follow a Weibull statistical distribution. We
used this statistical model to study the behavior of a monitoring algorithm
proposed in the literature, under heavy tail delays distribution. In this case,
the view of the managed system on the manager side becomes noisy and out of
date
The Z-index: A geometric representation of productivity and impact which accounts for information in the entire rank-citation profile
We present a simple generalization of Hirsch's h-index, Z =
\sqrt{h^{2}+C}/\sqrt{5}, where C is the total number of citations. Z is aimed
at correcting the potentially excessive penalty made by h on a scientist's
highly cited papers, because for the majority of scientists analyzed, we find
the excess citation fraction (C-h^{2})/C to be distributed closely around the
value 0.75, meaning that 75 percent of the author's impact is neglected.
Additionally, Z is less sensitive to local changes in a scientist's citation
profile, namely perturbations which increase h while only marginally affecting
C. Using real career data for 476 physicists careers and 488 biologist careers,
we analyze both the distribution of and the rank stability of Z with
respect to the Hirsch index h and the Egghe index g. We analyze careers
distributed across a wide range of total impact, including top-cited physicists
and biologists for benchmark comparison. In practice, the Z-index requires the
same information needed to calculate h and could be effortlessly incorporated
within career profile databases, such as Google Scholar and ResearcherID.
Because Z incorporates information from the entire publication profile while
being more robust than h and g to local perturbations, we argue that Z is
better suited for ranking comparisons in academic decision-making scenarios
comprising a large number of scientists.Comment: 9 pages, 5 figure
Quality-Driven Disorder Handling for M-way Sliding Window Stream Joins
Sliding window join is one of the most important operators for stream
applications. To produce high quality join results, a stream processing system
must deal with the ubiquitous disorder within input streams which is caused by
network delay, asynchronous source clocks, etc. Disorder handling involves an
inevitable tradeoff between the latency and the quality of produced join
results. To meet different requirements of stream applications, it is desirable
to provide a user-configurable result-latency vs. result-quality tradeoff.
Existing disorder handling approaches either do not provide such
configurability, or support only user-specified latency constraints.
In this work, we advocate the idea of quality-driven disorder handling, and
propose a buffer-based disorder handling approach for sliding window joins,
which minimizes sizes of input-sorting buffers, thus the result latency, while
respecting user-specified result-quality requirements. The core of our approach
is an analytical model which directly captures the relationship between sizes
of input buffers and the produced result quality. Our approach is generic. It
supports m-way sliding window joins with arbitrary join conditions. Experiments
on real-world and synthetic datasets show that, compared to the state of the
art, our approach can reduce the result latency incurred by disorder handling
by up to 95% while providing the same level of result quality.Comment: 12 pages, 11 figures, IEEE ICDE 201
Large cities are less green
We study how urban quality evolves as a result of carbon dioxide emissions as
urban agglomerations grow. We employ a bottom-up approach combining two
unprecedented microscopic data on population and carbon dioxide emissions in
the continental US. We first aggregate settlements that are close to each other
into cities using the City Clustering Algorithm (CCA) defining cities beyond
the administrative boundaries. Then, we use data on emissions at a
fine geographic scale to determine the total emissions of each city. We find a
superlinear scaling behavior, expressed by a power-law, between
emissions and city population with average allometric exponent
across all cities in the US. This result suggests that the high productivity of
large cities is done at the expense of a proportionally larger amount of
emissions compared to small cities. Furthermore, our results are substantially
different from those obtained by the standard administrative definition of
cities, i.e. Metropolitan Statistical Area (MSA). Specifically, MSAs display
isometric scaling emissions and we argue that this discrepancy is due to the
overestimation of MSA areas. The results suggest that allometric studies based
on administrative boundaries to define cities may suffer from endogeneity bias
Is There a Path for Green Growth? Evidence from India
This paper uses historical temperature fluctuations in India to identify its effects on economic growth rates. Using a climate-adjusted form of the Solow growth model, I find that one degree Celsius increase in temperature decreases GDP per capita growth by 0.71%. This finding informs debates over the role of climate on economic development and suggests the possibility of a green path for economic growth, a policy agenda that is both sustainable and pro-growth
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