Gyromagnetic Ratios of Bound Particles

A new approach to calculation of the binding corrections to the magnetic moments of the constituents in a loosely bound system, based on the Bargmann-Michel-Telegdi equation, is suggested. Binding corrections are calculated in this framework, and the results confirm earlier calculations performed by other methods. Our method clearly demonstrates independence of the binding corrections on the magnitude of the spin of the constituents.Comment: 10 pages, RevTe

Dressing a black hole with non-minimally coupled scalar field hair

We investigate the possibility of dressing a four-dimensional black hole with classical scalar field hair which is non-minimally coupled to the space-time curvature. Our model includes a cosmological constant but no self-interaction potential for the scalar field. We are able to rule out black hole hair except when the cosmological constant is negative and the constant governing the coupling to the Ricci scalar curvature is positive. In this case, non-trivial hairy black hole solutions exist, at least some of which are linearly stable. However, when the coupling constant becomes too large, the black hole hair becomes unstable.Comment: 17 pages, 7 figures, uses iopart.cls. Minor changes, accepted for publication in Classical and Quantum Gravit

Bogoliubov transformations and exact isolated solutions for simple non-adiabatic Hamiltonians

We present a new method for finding isolated exact solutions of a class of non-adiabatic Hamiltonians of relevance to quantum optics and allied areas. Central to our approach is the use of Bogoliubov transformations of the bosonic fields in the models. We demonstrate the simplicity and efficiency of this method by applying it to the Rabi Hamiltonian.Comment: LaTeX, 16 pages, 1 figure. Minor additions and journal re

Non-Linear Affine Embedding of the Dirac Field from the Multiplicity-Free SL(4,R) Unirreps

The correspondence between the linear multiplicity-free unirreps of SL(4, R) studied by Ne'eman and {\~{S}}ija{\~{c}}ki and the non-linear realizations of the affine group is worked out. The results obtained clarify the inclusion of spinorial fields in a non-linear affine gauge theory of gravitation.Comment: 13 pages, plain TeX, macros include

Peculiar properties of the cluster-cluster interaction induced by the Pauli exclusion principle

Role of the Pauli principle in the formation of both the discrete spectrum and multi-channel states of the binary nuclear systems composed of clusters is studied in the Algebraic Version of the resonating-group method. Solutions of the Hill-Wheeler equations in the discrete representation of a complete basis of the Pauli-allowed states are discussed for 4He+n, 3H+3H, and 4He+4He binary systems. An exact treatment of the antisymmetrization effects are shown to result in either an effective repulsion of the clusters, or their effective attraction. It also yields a change in the intensity of the centrifugal potential. Both factors significantly affect the scattering phase behavior. Special attention is paid to the multi-channel cluster structure 6He+6He as well as to the difficulties arising in the case when the two clustering configurations, 6He+6He and 4He+8He, are taken into account simultaneously. In the latter case the Pauli principle, even in the absence of a potential energy of the cluster-cluster interaction, leads to the inelastic processes and secures an existence of both the bound state and resonance in the 12Be compound nucleus.Comment: 17 pages, 14 figures, 1 table; submitted to Phys.Rev.C Keywords: light neutron-rich nuclei, cluster model

RECEIVED 1 APRIL; ACCEPTED 9 JULY; PUBLISHED ONLINE

The nematode C. elegans is an excellent model organism for studying behavior at the neuronal level. Because of the organism's small size, it is challenging to deliver stimuli to C. elegans and monitor neuronal activity in a controlled environment. To address this problem, we developed two microfluidic chips, the 'behavior' chip and the 'olfactory' chip for imaging of neuronal and behavioral responses in C. elegans. We used the behavior chip to correlate the activity of AVA command interneurons with the worm locomotion pattern. We used the olfactory chip to record responses from ASH sensory neurons exposed to high-osmotic-strength stimulus. Observation of neuronal responses in these devices revealed previously unknown properties of AVA and ASH neurons. The use of these chips can be extended to correlate the activity of sensory neurons, interneurons and motor neurons with the worm's behavior. How neural circuits process information to generate behavior is a fundamental question in neuroscience. To address this question, one should observe an animal in a well-controlled environment, in which a specific behavior can be generated and corresponding neuronal activity monitored. Ideally such an environment should not disturb normal neuronal function and should be able to reveal the specific neuronal circuit under study. C. elegans, with its optically accessible, stereotyped and compact nervous system, has drawn great scientific attention because of its diverse repertoire of behavioral outputs and its genetic conservation with vertebrates. Initial efforts to measure activity in the C. elegans nervous system relied on electrophysiological recordings from single neurons in dissected worms 1 . The recent development of genetically encoded fluorescent calcium indicators 2 has spawned an increasing interest in optical imaging approaches that permit the tracking of calcium transients in individual neurons in vivo in intact worms 3 . Although transgenic worms that express neuron-specific indicators can now routinely be generated, the present methods for confining and stimulating the worm during imaging are not ideal. The typical experimental setup involves application of glue onto specific segments of the worm to achieve permanent immobilization on a hydrated agar pad. Fluid-filled pipettes, temperature-controlled plates and sharp electrodes have been used in the past to deliver chemical, thermal and mechanical stimuli, respectively 4,5 . Whether the organic glue is toxic to the worm and how it influences neuronal activity are difficult to determine. Moreover, the delivery of chemical stimuli to the glued worm cannot be precisely controlled or separated from mechanical stimuli associated with fluid flow. More concerns arise when the circuit controlling locomotion is under study. The glue immobilizes the worm, not allowing muscles and stretch-receptor neurons, if any, to contract and relax normally. This mechanically restricted microenvironment might affect the function of the proprioceptive sensory neurons as well as motor neurons. Most importantly, the glue setup does not permit most behaviors to be generated, visualized, quantified or correlated to neuronal activity in real time. A system with two objectives 6 has been a welcome step toward simultaneous neuronal-behavior analysis, as has been a new system for tracking thermosensory neurons (albeit at low optical resolution) in freely moving worms 7 . Recent advances in microfabrication technology permit the construction of well-controllable microenvironments with applications ranging from cell analysis to tissue engineering RESULTS The behavior chip The first microfluidic device, the behavior chi