Tuning the structural and dynamical properties of a dipolar Bose-Einstein condensate: Ripples and instability islands

It is now well established that the stability of aligned dipolar Bose gases can be tuned by varying the aspect ratio of the external harmonic confinement. This paper extends this idea and demonstrates that a Gaussian barrier along the strong confinement direction can be employed to tune both the structural properties and the dynamical stability of an oblate dipolar Bose gas aligned along the strong confinement direction. In particular, our theoretical mean-field analysis predicts the existence of instability islands immersed in otherwise stable regions of the phase diagram. Dynamical studies indicate that these instability islands, which can be probed experimentally with present-day technology, are associated with the going soft of a Bogoliubov--de Gennes excitation frequency with radial breathing mode character. Furthermore, we find dynamically stable ground state densities with ripple-like oscillations along the radial direction. These structured ground states exist in the vicinity of a dynamical radial roton-like instability.Comment: 9 pages, 11 figure

Predictors of Two Kilometer Rowing Ergometer Time Trial Performance

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Generalized polarizabilities of the nucleon studied in the linear sigma model (II)

In a previous paper virtual Compton scattering off the nucleon has been investigated in the one-loop approximation of the linear sigma model in order to determine the 3 scalar generalized polarizabilities. We have now extended this work and calculated the 7 vector polarizabilities showing up in the spin-dependent amplitude of virtual Compton scattering. The results fulfill 3 model-independent constraints recently derived. Compared to the constituent quark model there exist enormous differences for some of the vector polarizabilities. At vanishing three-momentum of the virtual photon, the analytical results of the sigma model and of chiral perturbation theory can be related. The influence of the $\pi^{0}$ exchange in the $t$ channel has been discussed in some detail. Besides, the vector polarizabilities determine 2 linear combinations of the third order spin-polarizabilities appearing in real Compton scattering.Comment: 17 pages, 4 figures, latex2e (Revtex), submitted to Z. Phys.

Simultaneous and accurate measurement of the dielectric constant at many frequencies spanning a wide range

We present an innovative technique which allows the simultaneous measurement of the dielectric constant of a material at many frequencies, spanning a four orders of magnitude range chosen between 10 --2 Hz and 10 4 Hz. The sensitivity and accuracy are comparable to those obtained using standard single frequency techniques. The technique is based on three new and simple features: a) the precise real time correction of the amplication of a current amplier; b) the specic shape of the excitation signal and its frequency spectrum; and c) the precise synchronization between the generation of the excitation signal and the acquisition of the dielectric response signal. This technique is useful in the case of relatively fast dynamical measurements when the knowledge of the time evolution of the dielectric constant is needed

Structure analysis of the virtual Compton scattering amplitude at low energies

We analyze virtual Compton scattering off the nucleon at low energies in a covariant, model-independent formalism. We define a set of invariant functions which, once the irregular nucleon pole terms have been subtracted in a gauge-invariant fashion, is free of poles and kinematical zeros. The covariant treatment naturally allows one to implement the constraints due to Lorentz and gauge invariance, crossing symmetry, and the discrete symmetries. In particular, when applied to the $ep\to e'p'\gamma$ reaction, charge-conjugation symmetry in combination with nucleon crossing generates four relations among the ten originally proposed generalized polarizabilities of the nucleon.Comment: 19 pages, LaTeX2e/RevTeX, no figures, original sections IV.-VI. removed, to be discussed in a separate publication, none of the conclusions change

К разработке технологии возведения геокомпозитных охранных систем горных выработок

У статті розглянуто відмінності використання особливо тонко дисперсних в’яжучих (ОТДВ) у підземних умовах для створення елементів геокомпозитних конструкцій.In article the differences of the use especially thinly of dispersible astringent are considered in underground terms for creation elements of geocomposit constructions

Developing a practice-driven research agenda in implementation science: Perspectives from experienced implementation support practitioners

Background Attention is being placed on the “ironic gap” or “secondary” research-to-practice gap in the field of implementation science. Among several challenges posited to exacerbate this research-to-practice gap, we call attention to one challenge in particular—the relative dearth of implementation research that is tethered intimately to the lived experiences of implementation support practitioners (ISPs). The purpose of this study is to feature a qualitative approach to engaging with highly experienced ISPs to inform the development of a practice-driven research agenda in implementation science. In general, we aim to encourage ongoing empirical inquiry that foregrounds practice-driven implementation research questions. Method Our analytic sample was comprised of 17 professionals in different child and family service systems, each with long-term experience using implementation science frameworks to support change efforts. Data were collected via in-depth, semi-structured interviews. Our analysis followed a qualitative content analysis approach. Our focal conceptual category centered on the desired areas of future research highlighted by respondents, with subcategories reflecting subsets of related research question ideas. Results Interviews yielded varying responses that could help shape a practice-driven research agenda for the field of implementation science. The following subcategories regarding desired areas for future research were identified in respondents’ answers: (a) stakeholder engagement and developing trusting relationships, (b) evidence use, (c) workforce development, and (d) cost-effective implementation. Conclusions There is significant promise in bringing implementation research and implementation practice together more closely and building a practice-informed research agenda to shape implementation science. Our findings point not only to valuable practice-informed gaps in the literature that could be filled by implementation researchers, but also topics for which dissemination and translation efforts may not have yielded optimal reach. We also highlight the value in ISPs bolstering their own capacity for engaging with the implementation science literature to the fullest extent possible.Plain Language Summary In the field of implementation science, increasing attention is being placed on the “ironic gap” or “secondary” research-to-practice gap. This gap reflects a general lag or disconnect between implementation research and implementation practice, often stemming from knowledge generated by implementation research not being accessible to or applied by professionals who support implementation efforts in various service-delivery systems. Several explanations for the research-to-practice gap in implementation science have been offered in recent years; the authors highlight one notable challenge that may be exacerbating the research-to-practice gap in this field, namely that implementation research often remains disconnected from the lived experiences of implementation support practitioners. In this paper, the authors demonstrate the promise of developing a practice-drive research agenda in implementation science, with specific research question ideas offered by highly experienced implementation support practitioners. The paper concludes by expressing enthusiasm for future efforts to bring implementation research and implementation practice together more closely, empirically foreground practice-driven implementation research questions, translate and disseminate existing implementation research findings more widely, and build the capacity of implementation support practitioners to fully engage with the implementation science literature

Quantum jumps induced by the center-of-mass motion of a trapped atom

We theoretically study the occurrence of quantum jumps in the resonance fluorescence of a trapped atom. Here, the atom is laser cooled in a configuration of level such that the occurrence of a quantum jump is associated to a change of the vibrational center-of-mass motion by one phonon. The statistics of the occurrence of the dark fluorescence period is studied as a function of the physical parameters and the corresponding features in the spectrum of resonance fluorescence are identified. We discuss the information which can be extracted on the atomic motion from the observation of a quantum jump in the considered setup

Sub-doppler two-photon spectrum of asymmetric rotor molecules

The Doppler-free two-photon excitation spectrum of the qqQ branch of the 1410 vibrational band of the S1(1B2u) ← S0(1A1g) transition of benzene-d1 has been recorded using a cw single-mode dye laser coupled to an external concentric resonator. The spectrum has been analysed using a non-rigid Watson Hamiltonian. More than 200 lines with J up to 20 have been assigned and the rotational constants which best reproduce the spectrum are A1v = 0.181435, B1v = 0.169990, C1v = 0.089055 cm−1. The Ka = odd lines of the qqQ5(J) subbranch show small and quite regular perturbations of 60 ± 5 MHz which are probably due to a coupling to another vibrational state of the S1 manifold

Boson-conserving one-nucleon transfer operator in the interacting boson model

The boson-conserving one-nucleon transfer operator in the interacting boson model (IBA) is reanalyzed. Extra terms are added to the usual form used for that operator. These new terms change generalized seniority by one unit, as the ones considered up to now. The results obtained using the new form for the transfer operator are compared with those obtained with the traditional form in a simple case involving the pseudo-spin Bose-Fermi symmetry $U^{B}(6) \otimes U^F(12)$ in its $U^{BF}(5) \otimes U^F(2)$ limit. Sizeable differences are found. These results are of relevance in the study of transfer reactions to check nuclear supersymmetry and in the description of (\beta)-decay within IBA.Comment: 13 pages, 1 table, 0 figures. To be published in Phys. Rev.