Exploring the canonical behaviour of long gamma-ray bursts with an intrinsic multiwavelength afterglow correlation

In this conference proceeding we examine a correlation between the afterglow luminosity (measured at restframe 200 s; logL200s) and average afterglow decay rate (measured from restframe 200 s onwards; α>200s) found in both the optical/UV and X-ray afterglows of long duration Gamma-ray Bursts (GRBs). Examining the X-ray light curves, we find the correlation does not depend on the presence of specific light curve features. We explore how the parameters in the optical/UV and X-ray bands relate to each other and to the prompt emission phase. We also use a Monte Carlo simulation to explore whether these relationships are consistent with predictions of the standard afterglow model. We conclude that the correlations are consistent with a common underlying physical mechanism producing GRBs and their afterglows regardless of their detailed temporal behaviour. However, a basic afterglow model has difficulty explaining correlations involving α>200s. We therefore briefly discuss alternative more complex models

Effective Rheology of Bubbles Moving in a Capillary Tube

We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

Temporal and spectral signatures of the default mode network

The existence of a structured pattern of neuronal activity in the brain at rest has been consistently reported in the neuroscience literature. Multiple techniques, such as fMRI, MEG and EEG, showed that spontaneous, slow fluctuations of cerebral activity are temporally coherent within distributed functional networks resembling those evoked by sensory, motor, and cognitive paradigms. Among these networks, the Default Mode network gained large interest because of its anatomical and functional architecture. In fact, this network seems to reflect the default brain activity at rest and it has been associated with internal mentation, autobiographical memory, thinking about one's future, theory of mind, self-referential and affective decision making. What processing demands are shared in common across such a variety of tasks is presently unclear, and to disentangle such high level tasks into component processes is challenging. Here, we address some of these aspects by reviewing the current MEG studies on this network. In fact, while MEG data confirm the observed fMRI spatial topography, some new intriguing temporal and frequency properties of this network are revealed. Such findings enrich the original fMRI scenario on the DMN functional roles in terms of internal coupling and cross-network communication in the brain at rest. The Default Mode Network's internal coupling seems to be characterized by slow frequencies in the alpha and beta range and the cross-network interaction reveals that the DMN plays a central role in the communication across many different resting state networks