Strong atom-field coupling for Bose-Einstein condensates in an optical cavity on a chip

An optical cavity enhances the interaction between atoms and light, and the rate of coherent atom-photon coupling can be made larger than all decoherence rates of the system. For single atoms, this 'strong coupling regime' of cavity quantum electrodynamics has been the subject of many experimental advances. Efforts have been made to control the coupling rate by trapping the atom and cooling it towards the motional ground state; the latter has been achieved in one dimension so far. For systems of many atoms, the three-dimensional ground state of motion is routinely achieved in atomic Bose-Einstein condensates (BECs). Although experiments combining BECs and optical cavities have been reported recently, coupling BECs to cavities that are in the strong-coupling regime for single atoms has remained an elusive goal. Here we report such an experiment, made possible by combining a fibre-based cavity with atom-chip technology. This enables single-atom cavity quantum electrodynamics experiments with a simplified set-up and realizes the situation of many atoms in a cavity, each of which is identically and strongly coupled to the cavity mode. Moreover, the BEC can be positioned deterministically anywhere within the cavity and localized entirely within a single antinode of the standing-wave cavity field; we demonstrate that this gives rise to a controlled, tunable coupling rate. We study the heating rate caused by a cavity transmission measurement as a function of the coupling rate and find no measurable heating for strongly coupled BECs. The spectrum of the coupled atoms-cavity system, which we map out over a wide range of atom numbers and cavity-atom detunings, shows vacuum Rabi splittings exceeding 20 gigahertz, as well as an unpredicted additional splitting, which we attribute to the atomic hyperfine structure. We anticipate that the system will be suitable as a light-matter quantum interface for quantum information.     

Immunohistochemical demonstration of corticotrophic cells concentrated in the rostral zone of the pars intermedia of the mouse hypophysis

Résumé La nature corticotrope des cellules constituant la partie rostrale de la pars intermedia de l'hypophyse de souris est établie par la microscopie électronique et la cytoimmunofluorescence. Cette zone réagit positivement avec les anticorps anti-ACTH et négativement avec les anticorps anti-MSH.     

Immunocytology of alpha-endorphin positive hypothalamic fibers of Carassius auratus L. and Cyprinus carpio L.]

An immunocytological study of the basal hypothalamus of Carassius auratus and Cyprinus carpio with an alpha-endorphin antiserum shows the different nerve processes belonging probably to the immunoreactive cells of the lateral part of the N.L.T. According to their pathways, two main fibre tracts have been distinguished: many fluorescent fibres converge towards the pituitary gland into which they enter, other fibres run caudally through the tuber towards the nucleus tuberis inferior (Baumgarten and Braak) where they could not be followed further.     

Self-assembly of regular hollow icosahedra in salt-free catanionic solutions

Self-assembled structures having a regular hollow icosahedral form (such as those observed for proteins of virus capsids) can occur as a result of biomineralization processes, but are extremely rare in mineral crystallites. Compact icosahedra made from a boron oxide have been reported, but equivalent structures made of synthetic organic components such as surfactants have not hitherto been observed. It is, however, well known that lipids, as well as mixtures of anionic and cationic single chain surfactants, can readily form bilayers that can adopt a variety of distinct geometric forms: they can fold into soft vesicles or random bilayers (the so-called sponge phase) or form ordered stacks of flat or undulating membranes. Here we show that in salt-free mixtures of anionic and cationic surfactants, such bilayers can self-assemble into hollow aggregates with a regular icosahedral shape. These aggregates are stabilized by the presence of pores located at the vertices of the icosahedra. The resulting structures have a size of about one micrometre and mass of about 1010 daltons, making them larger than any known icosahedral protein assembly or virus capsid. We expect the combination of wall rigidity and holes at vertices of these icosahedral aggregates to be of practical value for controlled drug or DNA release.     

Localization of substance P in the nervous system of the human fetus : preliminary results

Substance P (SP) immunoreactive structures were localized by immunofluorescence technique within the central nervous system of human fetuses (12, 15, 19 and 24 weeks old). Specificity of the anti-SP serum was established by immunocytology and radio-immunology. A wide distribution of SP positive structures (pericaryons and/or fibres) was found in brain, spinal cord and dorsal root ganglia. Mesencephalon, pons and dorsal horns of the spinal cord showed very intense fluorescence. The preliminary observations are the first report concerning SP ontogeny in the Human central nervous system. However, it was difficult to ascribe a significance to this neuropeptide during fetal life.