9,612 research outputs found

    Attractive Bose-Einstein Condensates in three dimensions under rotation: Revisiting the problem of stability of the ground state in harmonic traps

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    We study harmonically trapped ultracold Bose gases with attractive interparticle interactions under external rotation in three spatial dimensions and determine the critical value of the attraction strength where the gas collapses as a function of the rotation frequency. To this end we examine the stationary state in the corotating frame with a many-body approach as well as within the Gross-Pitaevskii theory of systems in traps with different anisotropies. In contrast to recently reported results [N. A. Jamaludin, N. G. Parker, and A. M. Martin, Phys. Rev. A \textbf{77}, 051603(R) (2008)], we find that the collapse is not postponed in the presence of rotation. Unlike repulsive gases, the properties of the attractive system remain practically unchanged under rotation in isotropic and slightly anisotropic traps.Comment: 15 pages, 1 figure, 1 tabl

    Octopamine increases the excitability of neurons in the snail feeding system by modulation of inward sodium current but not outward potassium currents

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    Background: Although octopamine has long been known to have major roles as both transmitter and modulator in arthropods, it has only recently been shown to be functionally important in molluscs, playing a role as a neurotransmitter in the feeding network of the snail Lymnaea stagnalis. The synaptic potentials cannot explain all the effects of octopamine-containing neurons on the feeding network, and here we test the hypothesis that octopamine is also a neuromodulator. Results: The excitability of the B1 and B4 motoneurons in the buccal ganglia to depolarising current clamp pulses is significantly (P << 0.05) increased by (10 mu M) octopamine, whereas the B2 motoneuron becomes significantly less excitable. The ionic currents evoked by voltage steps were recorded using 2-electrode voltage clamp. The outward current of B1, B2 and B4 motoneurons had two components, a transient I-A current and a sustained I-K delayed-rectifier current, but neither was modulated by octopamine in any of these three buccal neurons. The fast inward current was eliminated in sodium - free saline and so is likely to be carried by sodium ions. 10 mu M octopamine enhanced this current by 33 and 45% in the B1 and B4 motoneurons respectively (P << 0.05), but a small reduction was seen in the B2 neuron. A Hodgkin-Huxley style simulation of the B1 motoneuron confirms that a 33% increase in the fast inward current by octopamine increases the excitability markedly. Conclusion: We conclude that octopamine is also a neuromodulator in snails, changing the excitability of the buccal neurons. This is supported by the close relationship from the voltage clamp data, through the quantitative simulation, to the action potential threshold, changing the properties of neurons in a rhythmic network. The increase in inward sodium current provides an explanation for the polycyclic modulation of the feeding system by the octopamine-containing interneurons, making feeding easier to initiate and making the feeding bursts more intense

    Oral Health Practices, Beliefs and Dental Service Utilization of Albanian Immigrants in Milwaukee, Wisconsin: A Pilot Study

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    There is limited information on the oral health of Albanian immigrant population residing in the U.S. This creates a hinderance to developing and implementing appropriate dental care programs for the population. This study investigated oral health practices, beliefs, dental visits and associated factors of Albanian adults living in Milwaukee, Wisconsin. Purposive and snowball sampling methods were employed. Self-administered questionnaires were used to collect data on oral health practices, beliefs, dental visits and socio-demographic information. Descriptive and multivariable logistics regression were conducted. Overall, 266 adults were recruited, 54% male, 56% have lived 10 or more years in the U.S., 95% rated their oral health as excellent/good and 87% reported having a dental visit in the last year. Age, ability to speak English, having a usual source of dental care, and reporting excellent/good oral health were associated with having a dental visit in the last year. A substantial number of Albanians adult reported a dental visit in the last year and those that did not write or read in English had lower odds of reporting a dental visit

    Opioid Analgesic Prescribing Practices of Dental Professionals in the United States

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    The prescription of opioid analgesics by dental professionals is widespread in the United States. Policy makers, government agencies, and professional organizations consider this phenomenon a growing public health concern. This study examined trends in the prescription of opioid analgesics for adults by dental professionals and associated factors in the United States. Data from the Medical Expenditure Panel Survey (1996-2013) were analyzed. Descriptive statistics were calculated separately for each year. Logistic regression analyses were conducted to estimate the overall trend during the period with and without adjusting for dental procedures and personal characteristics. Survey weights were incorporated to handle the sampling design. The prescription of opioid analgesics following dental care increased over time. After adjusting for sociodemographic factors, source of payment, and type of dental procedure, the odds ratio (OR) of prescribing opioid analgesics following a dental visit per each decade difference was 1.28 (95% confidence interval [CI], 1.19–1.38). Surgical, root canal, and implant procedures had the highest rates of opioid prescriptions and the greatest increases in rates over the study period. After adjusting for personal characteristics and type of dental procedure, the OR of receiving a prescription for opioids comparing blacks, Asians, and Hispanics to whites was 1.29 (95% CI, 1.17–1.41), 0.57 (95% CI, 0.47–0.70), and 0.84 (95% CI, 0.75–0.95), respectively. Opioid analgesic prescriptions following dental visits increased over time after adjusting for personal characteristics and type of dental procedure. The odds of receiving a prescription for opioids were higher for certain racial/ethnic minority groups. Knowledge Transfer Statement: This study highlights dental professionals prescribing practices of opioid analgesics by following dental treatments in the United States. With this knowledge, appropriate guidelines, protocols, and policies can be developed and implemented to address any inappropriate prescribing practices of opioid analgesics. In addition, this information could lead to an improvement in the prescribing practices of dental professionals and to evidence-based therapeutic decision making

    Trends and Racial/Ethnic Disparities in Antibiotic Prescribing Practices of Dentists in The United States

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    Objective The aim of this study was to examine trends and racial/ethnic disparities in antibiotic prescribing practices of dentists in the United States. Methods The US Medical Expenditure Panel Survey data for 1996‐2013 was analyzed. Information on patient sociodemographic characteristics, dental visits, receipt of dental procedures, and type of antibiotics prescribed following visits was obtained. Descriptive statistics were calculated separately for each year. Logistic regression analyses were conducted to identify associations during the period with and without adjustment for dental procedures and sociodemographic characteristics. Survey weights were incorporated to handle the sampling design. Results Nationally, the number of antibiotic prescribed at dental visits was estimated to be higher by 842,749 (0.4 percent) at year 2013 compared to the prescription level at 2003 were the population sociodemographic distribution kept at 2013 level. On average, the odds of prescribing antibiotics following dental care increased with each decade of study (OR: 1.10; 95% CI: [1.04, 1.17]) after adjusting for sociodemographic characteristics and receipt of dental procedures. Compared to Whites, Blacks had 21 percent (95% CI: 11%, 31%) higher odds of receiving a prescription for antibiotics from a dentist after adjusting for dental procedure and other sociodemographic characteristics. Conclusions The prescription of antibiotics following dental visits increased over time after adjustment for sociodemographic characteristics and dental procedure. The probability of being prescribed antibiotics by dentists was higher for Blacks compared to Whites

    Noncommutative theories and general coordinate transformations

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    We study the class of noncommutative theories in dd dimensions whose spatial coordinates (xi)i=1d(x_i)_{i=1}^d can be obtained by performing a smooth change of variables on (yi)i=1d(y_i)_{i=1}^d, the coordinates of a standard noncommutative theory, which satisfy the relation [yi,yj]=iθij[y_i, y_j] = i \theta_{ij}, with a constant θij\theta_{ij} tensor. The xix_i variables verify a commutation relation which is, in general, space-dependent. We study the main properties of this special kind of noncommutative theory and show explicitly that, in two dimensions, any theory with a space-dependent commutation relation can be mapped to another where that θij\theta_{ij} is constant.Comment: 21 pages, no figures, LaTeX. v2: section 5 added, typos corrected. Version to appear in Physical Review

    Multielectron corrections in molecular high-order harmonic generation for different formulations of the strong-field approximation

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    We make a detailed assessment of which form of the dipole operator to use in calculating high order harmonic generation within the framework of the strong field approximation, and look specifically at the role the form plays in the inclusion of multielectron effects perturbatively with regard to the contributions of the highest occupied molecular orbital. We focus on how these corrections affect the high-order harmonic spectra from aligned homonuclear and heteronuclear molecules, exemplified by N2\mathrm{N}_2 and CO, respectively, which are isoelectronic. We find that the velocity form incorrectly finds zero static dipole moment in heteronuclear molecules. In contrast, the length form of the dipole operator leads to the physically expected non-vanishing expectation value for the dipole operator in this case. Furthermore, the so called "overlap" integrals, in which the dipole matrix element is computed using wavefunctions at different centers in the molecule, are prominent in the first-order multielectron corrections for the velocity form, and should not be ignored. Finally, inclusion of the multielectron corrections has very little effect on the spectrum. This suggests that relaxation, excitation and the dynamic motion of the core are important in order to describe multielectron effects in molecular high-order high harmonic generation.Comment: Figures 2 and 4 have been simplified in order to fulfil the size requirements of arXiv; in the new version references have been adde

    Analysis of X-ray spectra emitted from laser-produced plasmas of uranium

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    In this paper, we used the multiconfiguration Dirac-Fock method to generate theoretical X-ray spectra for Co-, Ni-, Cu-, Zn-, Ga-, Ge-, As-, Se-, Br-, Kr-, and Rb-like uranium ions. Using the distribution of these ions in a laser-produced plasma, for different plasma temperatures, we generate theoretical spectra, which are compared to experimental data

    Sasakian quiver gauge theories and instantons on cones over round and squashed seven-spheres

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    We study quiver gauge theories on the round and squashed seven-spheres, and orbifolds thereof. They arise by imposing GG-equivariance on the homogeneous space G/H=SU(4)/SU(3)G/H=\mathrm{SU}(4)/\mathrm{SU}(3) endowed with its Sasaki-Einstein structure, and G/H=Sp(2)/Sp(1)G/H=\mathrm{Sp}(2)/\mathrm{Sp}(1) as a 3-Sasakian manifold. In both cases we describe the equivariance conditions and the resulting quivers. We further study the moduli spaces of instantons on the metric cones over these spaces by using the known description for Hermitian Yang-Mills instantons on Calabi-Yau cones. It is shown that the moduli space of instantons on the hyper-Kahler cone can be described as the intersection of three Hermitian Yang-Mills moduli spaces. We also study moduli spaces of translationally invariant instantons on the metric cone R8/Zk\mathbb{R}^8/\mathbb{Z}_k over S7/ZkS^7/\mathbb{Z}_k.Comment: 44 pages; v2: minor changes, reference added; Final version to appear in Nuclear Physics
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