2,274 research outputs found

    Phase separation in a boson-fermion mixture of Lithium atoms

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    We use a semiclassical three-fluid model to analyze the conditions for spatial phase separation in a mixture of fermionic Li-6 and a (stable) Bose-Einstein condensate of Li-7 atoms under cylindrical harmonic confinement, both at zero and finite temperature. We show that with the parameters of the Paris experiment [F. Schrek et al., Phys. Rev. Lett. 87 080403 (2001)] an increase of the boson-fermion scattering length by a factor five would be sufficient to enter the phase-separated regime. We give examples of configurations for the density profiles in phase separation and estimate that the transition should persist at temperatures typical of current experiments. For higher values of the boson-fermion coupling we also find a new phase separation between the fermions and the bosonic thermal cloud at finite temperature.Comment: 8 pages, 4 figures, new version of Fig. 4 and typos correcte

    Bose-Fermi Mixtures in One Dimension

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    We analyze the phase stability and the response of a mixture of bosons and spin-polarized fermions in one dimension (1D). Unlike in 3D, phase separation happens for low fermion densities. The dynamics of the mixture at low energy is independent of the spin-statistics of the components, and zero-sound-like modes exist that are essentially undamped.Comment: 5 pages; 1 figur

    The Experimental plan of the 4m Resonant Sideband Extraction Prototype for The LCGT

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    The 4m Resonant Sideband Extraction (RSE) interferometer is a planned prototype of the LCGT interferometer. The aim of the experiment is to operate a powerrecycled Broadband RSE interferometer with suspended optics and to achieve diagonalization of length signals of the central part of the interferometer directly through the optical setup. Details of the 4m RSE interferometer control method as well as the design of the experimental setup will be presented

    Phase Coherence in a Driven Double-Well System

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    We analyze the dynamics of the molecular field incoherently pumped by the photoassociation of fermionic atoms and coupled by quantum tunnelling in a double-well potential. The relative phase distribution of the molecular modes in each well and their phase coherence are shown to build up owing to quantum mechanical fluctuations starting from the vacuum state. We identify three qualitatively different steady-state phase distributions, depending on the ratio of the molecule-molecule interaction strength to interwell tunnelling, and examine the crossover from a phase-coherent regime to a phase-incoherent regime as this ratio increases.Comment: 5 pages, 2 figure

    M4 muscarinic receptor knockout mice display abnormal social behavior and decreased prepulse inhibition

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    <p>Abstract</p> <p>Background</p> <p>In the central nervous system (CNS), the muscarinic system plays key roles in learning and memory, as well as in the regulation of many sensory, motor, and autonomic processes, and is thought to be involved in the pathophysiology of several major diseases of the CNS, such as Alzheimer's disease, depression, and schizophrenia. Previous studies reveal that M<sub>4 </sub>muscarinic receptor knockout (M<sub>4</sub>R KO) mice displayed an increase in basal locomotor activity, an increase in sensitivity to the prepulse inhibition (PPI)-disrupting effect of psychotomimetics, and normal basal PPI. However, other behaviorally significant roles of M<sub>4</sub>R remain unclear.</p> <p>Results</p> <p>In this study, to further investigate precise functional roles of M<sub>4</sub>R in the CNS, M<sub>4</sub>R KO mice were subjected to a battery of behavioral tests. M<sub>4</sub>R KO mice showed no significant impairments in nociception, neuromuscular strength, or motor coordination/learning. In open field, light/dark transition, and social interaction tests, consistent with previous studies, M<sub>4</sub>R KO mice displayed enhanced locomotor activity compared to their wild-type littermates. In the open field test, M<sub>4</sub>R KO mice exhibited novelty-induced locomotor hyperactivity. In the social interaction test, contacts between pairs of M<sub>4</sub>R KO mice lasted shorter than those of wild-type mice. In the sensorimotor gating test, M<sub>4</sub>R KO mice showed a decrease in PPI, whereas in the startle response test, in contrast to a previous study, M<sub>4</sub>R KO mice demonstrated normal startle response. M<sub>4</sub>R KO mice also displayed normal performance in the Morris water maze test.</p> <p>Conclusions</p> <p>These findings indicate that M<sub>4</sub>R is involved in regulation of locomotor activity, social behavior, and sensorimotor gating in mice. Together with decreased PPI, abnormal social behavior, which was newly identified in the present study, may represent a behavioral abnormality related to psychiatric disorders including schizophrenia.</p

    Random-phase approximation study of collective excitations in the Bose-Fermi mixed condensate of alkali-metal gases

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    We perform Random Phase Approximation (RPA) study of collective excitations in the bose-fermi mixed degenerate gas of Alkali-metal atoms at T=0. The calculation is done by diagonalization in a model space composed of particle-hole type excitations from the ground state, the latter being obtained from the coupled Gross-Pitaevskii and Thomas-Fermi equations. We investigate strength distributions for different combinations of bose and fermi multipole (LL) operators with L=0,1,2,3L=0,1,2,3. Transition densities and dynamical structure factors are calculated for collective excitations. Comparison with the sum rule prediction for the collective frequency is given. Time dependent behavior of the system after an external impulse is studied.Comment: 28 pages, 13 figures, submitted to Phys. Rev.
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