7 research outputs found
Fermi acceleration in astrophysical jets
We consider the acceleration of energetic particles by Fermi processes (i.e.,
diffusive shock acceleration, second order Fermi acceleration, and gradual
shear acceleration) in relativistic astrophysical jets, with particular
attention given to recent progress in the field of viscous shear acceleration.
We analyze the associated acceleration timescales and the resulting particle
distributions, and discuss the relevance of these processes for the
acceleration of charged particles in the jets of AGNs, GRBs and microquasars,
showing that multi-component powerlaw-type particle distributions are likely to
occur.Comment: 6 pages, one figure; based on talk at "The multimessenger approach to
unidentified gamma-ray sources", Barcelona/Spain, July 2006; accepted for
publication in Astrophysics and Space Scienc
Discovery of the chelonine tribeAdeliini Viereck, 1918 (Hymenoptera: Braconidae) from the Indian subcontinent with the description of a new genus from south India
Ranjith, A.P., Achterberg, C. Van, Samartsev, K.G., Nasser, M. (2021): Discovery of the chelonine tribeAdeliini Viereck, 1918 (Hymenoptera: Braconidae) from the Indian subcontinent with the description of a new genus from south India. Zootaxa 4926 (1): 1-25, DOI: https://doi.org/10.11646/zootaxa.4926.1.
Temporal and region-specific requirements of αCaMKII in spatial and contextual learning
The α isoform of the calcium/calmodulin-dependent protein kinase II (αCaMKII) has been implicated extensively in molecular and cellular mechanisms underlying spatial and contextual learning in a wide variety of species. Germline deletion of Camk2a leads to severe deficits in spatial and contextual learning in mice. However, the temporal and region-specific requirements for αCaMKII have remained largely unexplored. Here, we generated conditional Camk2a mutants to examine the influence of spatially restricted and temporally controlled expression of αCaMKII. Forebrain-specific deletion of the Camk2a gene resulted in severe deficits in water maze and contextual fear learning, whereas mice with deletion restricted to the cerebellum learned normally. Furthermore, we found that temporally controlled deletion of the Camk2a gene in adult mice is as detrimental as germline deletion for learning and synaptic plasticity. Together, we confirm the requirement for αCaMKII in the forebrain, but not the cerebellum, in spatial and contextual learning. Moreover, we highlight the absolute requirement for intact αCaMKII expression at the time of learning