7,519 research outputs found
From urban to national heat island: The effect of anthropogenic heat output on climate change in high population industrial countries
The project presented here sought to determine whether changes in anthropogenic thermal emission can have a measurable effect on temperature at the national level, taking Japan and Great Britain as type examples. Using energy consumption as a proxy for thermal emission, strong correlations (mean r2 = 0.90 and 0.89, respectively) are found between national equivalent heat output (HO) and temperature above background levels Δt averaged over 5‐ to 8‐yr periods between 1965 and 2013, as opposed to weaker correlations for CMIP5 model temperatures above background levels Δmt (mean r2 = 0.52 and 0.10). It is clear that the fluctuations in Δt are better explained by energy consumption than by present climate models, and that energy consumption can contribute to climate change at the national level on these timescales
Dynamic communicability and epidemic spread: a case study on an empirical dynamic contact network
We analyze a recently proposed temporal centrality measure applied to an
empirical network based on person-to-person contacts in an emergency department
of a busy urban hospital. We show that temporal centrality identifies a
distinct set of top-spreaders than centrality based on the time-aggregated
binarized contact matrix, so that taken together, the accuracy of capturing
top-spreaders improves significantly. However, with respect to predicting
epidemic outcome, the temporal measure does not necessarily outperform less
complex measures. Our results also show that other temporal markers such as
duration observed and the time of first appearance in the the network can be
used in a simple predictive model to generate predictions that capture the
trend of the observed data remarkably well.Comment: 31 pages, 15 figures, 11 tables; typos corrected; references added;
Figure 3 added; some changes to the conclusion and introductio
Test for Spatio-Temporal Counts Being Poisson
The new Log-Linear Test (TL) is proposed to identify when the Poisson model fails for a collection of count random variables. TL is shown to have better rejection rate with small sample size and essentially the same power compared to a classical Fisher-Bohning’s Statistic TF for standard alternatives to Poisson
Edge Intelligence Over the Air: Two Faces of Interference in Federated Learning
Federated edge learning is envisioned as the bedrock of enabling intelligence
in next-generation wireless networks, but the limited spectral resources often
constrain its scalability. In light of this challenge, a line of recent
research suggested integrating analog over-the-air computations into federated
edge learning systems, to exploit the superposition property of electromagnetic
waves for fast aggregation of intermediate parameters and achieve (almost)
unlimited scalability. Over-the-air computations also benefit the system in
other aspects, such as low hardware cost, reduced access latency, and enhanced
privacy protection. Despite these advantages, the interference introduced by
wireless communications also influences various aspects of the model training
process, while its importance is not well recognized yet. This article provides
a comprehensive overview of the positive and negative effects of interference
on over-the-air computation-based edge learning systems. The potential open
issues and research trends are also discussed.Comment: 7 pages, 6 figures. Accepted by IEEE Communications Magazin
Catastrophic eruption of magnetic flux rope in the corona and solar wind with and without magnetic reconnection
It is generally believed that the magnetic free energy accumulated in the
corona serves as a main energy source for solar explosions such as coronal mass
ejections (CMEs). In the framework of the flux rope catastrophe model for CMEs,
the energy may be abruptly released either by an ideal magnetohydrodynamic
(MHD) catastrophe, which belongs to a global magnetic topological instability
of the system, or by a fast magnetic reconnection across preexisting or
rapidly-developing electric current sheets. Both ways of magnetic energy
release are thought to be important to CME dynamics. To disentangle their
contributions, we construct a flux rope catastrophe model in the corona and
solar wind and compare different cases in which we either prohibit or allow
magnetic reconnection to take place across rapidly-growing current sheets
during the eruption. It is demonstrated that CMEs, even fast ones, can be
produced taking the ideal MHD catastrophe as the only process of magnetic
energy release. Nevertheless, the eruptive speed can be significantly enhanced
after magnetic reconnection sets in. In addition, a smooth transition from slow
to fast eruptions is observed when increasing the strength of the background
magnetic field, simply because in a stronger field there is more free magnetic
energy at the catastrophic point available to be released during an eruption.
This suggests that fast and slow CMEs may have an identical driving mechanism.Comment: 7 pages, 4 figures, ApJ, in press (vol. 666, Sept. 2007
Theranostic Imaging of the Kinases and Proteases that Modulate Cell Death and Survival
Several signaling cascades are involved in cell death, with a significant amount of crosstalk between them. Despite the complexity of these cascades several key pro-survival and pro-death players have been identified. These include PI3-kinase, AKT and caspase-3. Here we review the approaches used to date to perform molecular imaging of these important targets. We focus in particular on approaches that include the possibility of modulating the activity of these kinases and proteases in a theranostic approach
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