Radiative Properties of the Stueckelberg Mechanism

We examine the mechanism for generating a mass for a U(1) vector field introduced by Stueckelberg. First, it is shown that renormalization of the vector mass is identical to the renormalization of the vector field on account of gauge invariance. We then consider how the vector mass affects the effective potential in scalar quantum electrodynamics at one-loop order. The possibility of extending this mechanism to couple, in a gauge invariant way, a charged vector field to the photon is discussed.Comment: 8 pages, new Introduction, added Reference

Phytoplankton Composition in a Borrow Pit Lake in Virginia

The phytoplankton assemblages in Lake Trashmore, Virginia, a borrow pit, were dominated by centric diatoms and cyanobacteria, with seasonal pulses of cryptomonads, euglenoids, and chlorophyceans. Ninety species were identified and their abundance levels noted for a 12-month period

Observations of the Phytoplankton Standing Crop at the Shelf Margin of the Mid Atlantic Bight

A comparison of the total percentage cell abundance and cell biovolume relationships of major phytoplankton categories was made between two station sets across the shelf margin. Diatom values for abundance and biovolume were greater at oceanic stations compared to the outer shelf stations, with dinoflagellates having the reverse pattern. The composite contributions to biovolume and abundance in the standing crop from other phytoplankton categories were greater over the outer shelf than beyond the shelf margin. The major source of biovolume (biomass) from the outer shelf and these oceanic stations came from the diatoms and dinoflagellates, with an average mean of 93% of the total phytoplankton standing crop

Preparing a Presentation for Educational Programs.

4 p

Phytoplankton Composition in a Borrow Pit Lake in Virginia

The phytoplankton assemblages in Lake Trashmore, Virginia, a borrow pit, were dominated by centric diatoms and cyanobacteria, with seasonal pulses of cryptomonads, euglenoids, and chlorophyceans. Ninety species were identified and their abundance levels noted for a 12-month period

Program Building Committee's Central Planning Group.

16 p

Statistical Properties of Avalanches in Networks

We characterize the distributions of size and duration of avalanches propagating in complex networks. By an avalanche we mean the sequence of events initiated by the externally stimulated `excitation' of a network node, which may, with some probability, then stimulate subsequent firings of the nodes to which it is connected, resulting in a cascade of firings. This type of process is relevant to a wide variety of situations, including neuroscience, cascading failures on electrical power grids, and epidemology. We find that the statistics of avalanches can be characterized in terms of the largest eigenvalue and corresponding eigenvector of an appropriate adjacency matrix which encodes the structure of the network. By using mean-field analyses, previous studies of avalanches in networks have not considered the effect of network structure on the distribution of size and duration of avalanches. Our results apply to individual networks (rather than network ensembles) and provide expressions for the distributions of size and duration of avalanches starting at particular nodes in the network. These findings might find application in the analysis of branching processes in networks, such as cascading power grid failures and critical brain dynamics. In particular, our results show that some experimental signatures of critical brain dynamics (i.e., power-law distributions of size and duration of neuronal avalanches), are robust to complex underlying network topologies.Comment: 11 pages, 7 figure