The response of the upper atmospheric temperature to changes in solar EUV radiation and geomagnetic activity

Solar radiation and magnetic effects on upper atmospheric neutral temperatures derived from satellite dra

Coarsening and Slow-Dynamics in Granular Compaction

We address the problem of the microscopic reorganization of a granular medium under a compaction process in the framework of Tetris-like models. We point out the existence of regions of spatial organization which we call domains, and study their time evolution. It turns out that after an initial transient, most of the activity of the system is concentrated on the boundaries between domains. One can then describe the compaction phenomenon as a coarsening process for the domains, and a progressive reduction of domain boundaries. We discuss the link between the coarsening process and the slow dynamics in the framework of a model of active walkers on active substrates.Comment: Revtex 4 pages, 4 figures, in press in PRL. More info http://axtnt3.phys.uniroma1.it/Tetri

Bott--Kitaev periodic table and index theory

We consider topological insulators and superconductors with discrete symmetries and clarify the relevant index theory behind the periodic table proposed by Kitaev. An effective Hamiltonian determines the analytical index, which can be computed by a topological index. We focus on the spatial dimensions one, two and three, and only consider the bulk theory. In two dimensions, the $\mathbb{Z}$-valued invariants are given by the first Chern number. Meanwhile, $\mathbb{Z}_2$-valued invariants can be computed by the odd topological index and its variations. The Bott-Kitaev periodic table is well-known in the physics literature, we organize the topological invariants in the framework of KR-theory.Comment: 37 page

Seaweed resources of Kerala Coast

Surveys conducted for the first time recently along the Karala coast have indicated the presence of seaweeds at the following locations: Mullur,Vizhinjam, Kovalam , Chilakaar,Varkala, Edava, Tankasseri, Thirumullavaram, Kovilthottam, Cherai, Azhikkal, Perumpally, Thekkodu, Pallithodu, Chellanam, Kandakadavu, Elathur, Kadalur (Nandi) Madapalli, Tharayi, Tellicherry, Pallikere and Kanutheertha

Studies on the fauna associated with the cultured seaweed Gracilaria edulis

With a view to study the fauna associated with the cultured seaweed Gracilaria edulis in coastal waters of the Palk Bay and the Gulf of Mannar and to assess the damage, if any, caused by any of the organisms, samples of all animal associated with the cultured seaweeds were collected from the seaweed culture sites. Qualitative analysis of the samples indicated that the fauna is mainly composed of crabs, amphipods, polychaetes, isopods, copepods, gastropods, bivalves, holothurians and fishes. Quantitatively, crabs were found to be more numerous than all other groups, followed by amphipods and polychaetes

Nonlinear physics of the ionosphere and LOIS/LOFAR

The ionosphere is the only large-scale plasma laboratory without walls that we have direct access to. From results obtained in systematic, repeatable experiments in this natural laboratory, where we can vary the stimulus and observe its response in a controlled, repeatable manner, we can draw conclusions on similar physical processes occurring naturally in the Earth's plasma environment as well as in parts of the plasma universe that are not easily accessible to direct probing. Of particular interest is electromagnetic turbulence excited in the ionosphere by beams of particles (photons, electrons) and its manifestation in terms of secondary radiation (electrostatic and electromagnetic waves), structure formation (solitons, cavitons, alfveons, striations), and the associated exchange of energy, linear momentum, and angular momentum. We present a new diagnostic technique, based on vector radio allowing the utilization of EM angular momentum (vorticity), to study plasma turbulence remotely.Comment: Six pages, two figures. To appear in Plasma Physics and Controlled Fusio