12,616 research outputs found

    Solitude, Silence, and the Training of Psychotherapists: A Preliminary Study

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    The spiritual disciplines of silence and solitude have long been practiced within the contemplative Christian tradition as a means of character transformation and experiencing God. Do these disciplines affect the use of silence in psychotherapy for Christian clinicians in a graduate training program? Nineteen graduate students in clinical psychology were assigned to a wait-list control condition or a training program involving the disciplines of solitude and silence, and the groups were reversed after the ftrst cohort completed the spiritual disciplines training. One group, which was coincidentally comprised of more introverted individuals, demonstrated a striking increase in the number of silent periods and total duration of silence during simulated psychotherapy sessions during the period of training. The other group, more extraverted in nature, did not show significant changes in therapeutic silence during the training. These results cause us to pose research questions regarding the interaction of personality characteristics and spiritual disciplines in training Christian psychotherapists

    Spontaneously modulated spin textures in a dipolar spinor Bose-Einstein condensate

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    Helical spin textures in a 87^{87}Rb F=1 spinor Bose-Einstein condensate are found to decay spontaneously toward a spatially modulated structure of spin domains. This evolution is ascribed to magnetic dipolar interactions that energetically favor the short-wavelength domains over the long-wavelength spin helix. This is confirmed by eliminating the dipolar interactions by a sequence of rf pulses and observing a suppression of the formation of the short-range domains. This study confirms the significance of magnetic dipole interactions in degenerate 87^{87}Rb F=1 spinor gases

    Amplification of Fluctuations in a Spinor Bose Einstein Condensate

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    Dynamical instabilities due to spin-mixing collisions in a 87^{87}Rb F=1 spinor Bose-Einstein condensate are used as an amplifier of quantum spin fluctuations. We demonstrate the spectrum of this amplifier to be tunable, in quantitative agreement with mean-field calculations. We quantify the microscopic spin fluctuations of the initially paramagnetic condensate by applying this amplifier and measuring the resulting macroscopic magnetization. The magnitude of these fluctuations is consistent with predictions of a beyond-mean-field theory. The spinor-condensate-based spin amplifier is thus shown to be nearly quantum-limited at a gain as high as 30 dB

    Coherence-enhanced imaging of a degenerate Bose gas

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    We present coherence-enhanced imaging, an in situ technique that uses Raman superradiance to probe the spatial coherence properties of an ultracold gas. Applying this method, we obtain a spatially resolved measurement of the condensate number and more generally, of the first-order spatial correlation function in a gas of 87^{87}Rb atoms. We observe the enhanced decay of propagating spin gratings in high density regions of a Bose condensate, a decay we ascribe to collective, non-linear atom-atom scattering. Further, we directly observe spatial inhomogeneities that arise generally in the course of extended sample superradiance.Comment: 4 pages, 4 figure

    Eulerian spectral closures for isotropic turbulence using a time-ordered fluctuation-dissipation relation

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    Procedures for time-ordering the covariance function, as given in a previous paper (K. Kiyani and W.D. McComb Phys. Rev. E 70, 066303 (2004)), are extended and used to show that the response function associated at second order with the Kraichnan-Wyld perturbation series can be determined by a local (in wavenumber) energy balance. These time-ordering procedures also allow the two-time formulation to be reduced to time-independent form by means of exponential approximations and it is verified that the response equation does not have an infra-red divergence at infinite Reynolds number. Lastly, single-time Markovianised closure equations (stated in the previous paper above) are derived and shown to be compatible with the Kolmogorov distribution without the need to introduce an ad hoc constant.Comment: 12 page

    A Flattened Protostellar Envelope in Absorption around L1157

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    Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8 microns, there is a flattened structure seen in absorption against the background emission. The structure is perpendicular to the outflow and is extended to a diameter of 2 arcminutes. This structure is the first clear detection of a flattened circumstellar envelope or pseudo-disk around a Class 0 protostar. Such a flattened morphology is an expected outcome for many collapse theories that include magnetic fields or rotation. We construct an extinction model for a power-law density profile, but we do not constrain the density power-law index.Comment: ApJL accepte

    The Spitzer View of Low-Metallicity Star Formation: II. Mrk 996, a Blue Compact Dwarf Galaxy with an Extremely Dense Nucleus

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    (abridged) We present new Spitzer, UKIRT and MMT observations of the blue compact dwarf galaxy (BCD) Mrk 996, with an oxygen abundance of 12+log(O/H)=8.0. This galaxy has the peculiarity of possessing an extraordinarily dense nuclear star-forming region, with a central density of ~10^6 cm^{-3}. The nuclear region of Mrk 996 is characterized by several unusual properties: a very red color J-K = 1.8, broad and narrow emission-line components, and ionizing radiation as hard as 54.9 eV, as implied by the presence of the OIV 25.89 micron line. The nucleus is located within an exponential disk with colors consistent with a single stellar population of age >1 Gyr. The infrared morphology of Mrk 996 changes with wavelength. The IRS spectrum shows strong narrow Polycyclic Aromatic Hydrocarbon (PAH) emission, with narrow line widths and equivalent widths that are high for the metallicity of Mrk 996. Gaseous nebular fine-structure lines are also seen. A CLOUDY model requires that they originate in two distinct HII regions: a very dense HII region of radius ~580 pc with densities declining from ~10^6 at the center to a few hundreds cm^{-3} at the outer radius, where most of the optical lines arise; and a HII region with a density of ~300 cm^{-3} that is hidden in the optical but seen in the MIR. We suggest that the infrared lines arise mainly in the optically obscured HII region while they are strongly suppressed by collisional deexcitation in the optically visible one. The hard ionizing radiation needed to account for the OIV 25.89 micron line is most likely due to fast radiative shocks propagating in an interstellar medium. A hidden population of Wolf-Rayet stars of type WNE-w or a hidden AGN as sources of hard ionizing radiation are less likely possibilities.Comment: 48 pages, 13 figures, accepted for publication in the Astrophysical Journa

    High-Resolution Magnetometry with a Spinor Bose-Einstein Condensate

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    We demonstrate a precision magnetic microscope based on direct imaging of the Larmor precession of a 87^{87}Rb spinor Bose-Einstein condensate. This magnetometer attains a field sensitivity of 8.3 pT/Hz1/2^{1/2} over a measurement area of 120 μ\mum2^2, an improvement over the low-frequency field sensitivity of modern SQUID magnetometers. The corresponding atom shot-noise limited sensitivity is estimated to be 0.15 pT/Hz1/2^{1/2} for unity duty cycle measurement. The achieved phase sensitivity is close to the atom shot-noise limit suggesting possibilities of spatially resolved spin-squeezed magnetometry. This magnetometer marks a significant application of degenerate atomic gases to metrology
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