31 research outputs found
Communication and optimal hierarchical networks
We study a general and simple model for communication processes. In the
model, agents in a network (in particular, an organization) interchange
information packets following simple rules that take into account the limited
capability of the agents to deal with packets and the cost associated to the
existence of open communication channels. Due to the limitation in the
capability, the network collapses under certain conditions. We focus on when
the collapse occurs for hierarchical networks and also on the influence of the
flatness or steepness of the structure. We find that the need for hierarchy is
related to the existence of costly connections.Comment: 7 pages, 2 figures. NATO ARW on Econophysic
Headache in juvenile myoclonic epilepsy
The objective of this study was to assess the prevalence of and risk factors for primary headaches in juvenile myoclonic epilepsy (JME). Headache was classified in 75 patients with JME using a questionnaire, and its prevalence was correlated with the literature on the general population and clinical data. Headache was present in 47 patients. Thirty-one had migraine [20 migraine without aura (MO), 11 migraine with aura (MA)]. Fourteen patients with migraine had tension-type headache (TTH) in addition. Sixteen had only TTH. Comparison with the general population revealed a significantly higher prevalence of migraine (RR 4.4), MO (3.6), MA (7.3) and TTH (3.4) in JME. Risk factors for migraine and MO were female gender and for MA family history of migraine in first-degree relatives. Migraine and MA were associated with fairly controlled generalized tonic clonic seizures, MO with absences. Together with its strong genetic background, JME appears to be an attractive homogenous subtype of epilepsy for genetic research on migraine