Rosario Delgado

A statistical approach to bioclimatic trend detection in the airborne pollen records of Catalonia (NE Spain)

Airborne pollen records are a suitable indicator for the study of climate change. The present work focuses on the role of annual pollen indices for the detection of bioclimatic trends through the analysis of the aerobiological spectra of 11 taxa of great biogeographical relevance in Catalonia over an 18-year period (1994–2011), by means of different parametric and non-parametric statistical methods. Among others, two non-parametric rank-based statistical tests were performed for detecting monotonic trends in time series data of the selected airborne pollen types and we have observed that they have similar power in detecting trends. Except for those cases in which the pollen data can be well-modeled by a normal distribution, it is better to apply non-parametric statistical methods to aerobiological studies. Our results provide a reliable representation of the pollen trends in the region and suggest that greater pollen quantities are being liberated to the atmosphere in the last years, specially by Mediterranean taxa such as Pinus, Total Quercus and Evergreen Quercus, although the trends may differ geographically. Longer aerobiological monitoring periods are required to corroborate these results and survey the increasing levels of certain pollen types that could exert an impact in terms of public health.

State space collapse for asymptotically critical multi-class fluid networks

AbstractWe consider a class of fluid queueing networks with multiple fluid classes and feedback allowed, which are fed by N heavy tailed ON/OFF sources. We study the asymptotic behavior when N→∞ of these queueing systems in a heavy traffic regime (that is, when they are asymptotically critical). As performance processes we consider the workload WN (the amount of time needed for each server to complete processing of all the fluid in queue), and the fluid queue ZN (the quantity of each fluid class in the system). We show the convergence of

Stability analysis of cascade networks via fluid models

\sqrt{N}W^{N}

ON THE REFLECTED FRACTIONAL BROWNIAN MOTION PROCESS ON THE POSITIVE ORTHANT: ASYMPTOTICS FOR A MAXIMUM WITH APPLICATION TO QUEUEING NETWORKS

and

Local conditions for the stochastic comparison of particle systems

\sqrt{N}Z^{N}

State space collapse and stability of queueing networks

(to

Changes in the Mediterranean pine forest: pollination patterns and annual trends of airborne pollen

\hat{W}

A packet-switched network with On/Off sources and a fair bandwidth sharing policy: state space collapse and heavy-traffic

and

A Bayesian Network Profiler for Wildfire Arsonists

\hat{Z}

Heavy-traffic limit for a feed-forward fluid model with heterogeneous heavy-tailed On/Off sources

) in heavy traffic if state space collapse (SSC) holds. (SSC) is a condition that establishes a relationship between those components of