The neural correlates of phonological short-term memory: A repetitive transcranial magnetic stimulation study

Neuropsychological reports and activation studies by means of positron emission tomography anti functional magnetic resonance imaging have suggested that the neural correlates of phonological short-term memory are located in the left hemisphere, with Brodmann's area (BA) 40 being, responsible for short-term storage and BA 44 for articulatory rehearsal. However, a careful review of the literature on the role of left BA 40 shows that the data are equivocal. We tested We hypotheses by means of repetitive transcranial magnetic stimulation (rTMS). Participants performed four tasks: two phonological judgements, thought to require only articulatory rehearsal Without the contribution of short-term storage digit span, which involves both short-term storage and articudlatory rehearsal: and a pattern span, this last heing the control task. The sites of stimulation were left BA 40. left BA 44 anti the electrode location V-W plus a baseline without TMS. Reaction times increased and accuracy decreased in the case of the phonological judgement and digit span after stimulation of both left sites, suggesting that BA 40, in addition to BA 44. is involved in phonological judgements. Possible explanations are discussed, namely, the possibility that (i) the neural correlates of rehearsal are not limited to BA and (ii) phonological judgements invlove processes other than rehearsal. We also consider the effects of using different tasks and responses to resolve some of the descrepancies in the literature

Gamma-ray flares from black hole coronae

We present results of a study of non-thermal, time-dependent particle injection in a corona around an accreting black hole. We model the spectral energy distribution of high-energy flares in this scenario. We consider particle interactions with magnetic, photon and matter fields in the black hole magnetosphere. Transport equations are solved for all species of particles and the electromagnetic output is predicted. Photon annihilation is taken into account for the case of systems with early-type donor stars.Comment: 7 pages, 7 figures. Accepted for publication in the Proceedings of the 25th Texas Symposium on Relativistic Astrophysics, held in Heidelberg, December 06-10, 201

Mechanisms for optical binding

The phenomenon of optical binding is now experimentally very well established. With a recognition of the facility to collect and organize particles held in an optical trap, the related term 'optical matter' has also been gaining currency, highlighting possibilities for a significant interplay between optically induced inter-particle forces and other interactions such as chemical bonding and dispersion forces. Optical binding itself has a variety of interpretations. With some of these explanations being more prominent than others, and their applicability to some extent depending on the nature of the particles involved, a listing of these has to include the following: collective scattering, laser-dressed Casimir forces, virtual photon coupling, optically induced dipole resonance, and plasmon resonance coupling. It is the purpose of this paper to review and to establish the extent of fundamental linkages between these theoretical descriptions, recognizing the value that each has in relating the phenomenon of optical binding to the broader context of other, closely related physical measurements

Ermakov approach for the one-dimensional Helmholtz Hamiltonian

For the one-dimensional Helmholtz equation we write the corresponding time-dependent Helmholtz Hamiltonian in order to study it as an Ermakov problem and derive geometrical angles and phases in this contextComment: 6 pages, LaTe