4,732 research outputs found

    Probing Nonlocal Spatial Correlations in Quantum Gases with Ultra-long-range Rydberg Molecules

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    We present photo-excitation of ultra-long-range Rydberg molecules as a probe of spatial correlations in quantum gases. Rydberg molecules can be created with well-defined internuclear spacing, set by the radius of the outer lobe of the Rydberg electron wavefunction RnR_n. By varying the principal quantum number nn of the target Rydberg state, the molecular excitation rate can be used to map the pair-correlation function of the trapped gas g(2)(Rn)g^{(2)}(R_n). We demonstrate this with ultracold Sr gases and probe pair-separation length scales ranging from Rn=1400−3200R_n = 1400 - 3200 a0a_0, which are on the order of the thermal de Broglie wavelength for temperatures around 1 μ\muK. We observe bunching for a single-component Bose gas of 84^{84}Sr and anti-bunching due to Pauli exclusion at short distances for a polarized Fermi gas of 87^{87}Sr, revealing the effects of quantum statistics.Comment: 6 pages, 5 figure

    Driving and Patients With Dementia

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    Driving is a symbol of autonomy and independence, eagerly awaited during adolescence, cherished during adulthood and reluctantly rescinded during old age. It is nevertheless an individual’s privilege, not right, especially as driving may affect other drivers and pedestrians on the road. It is therefore not only the individual patient who is at stake but essentially the entire community. In this case scenario, we describe the situation that arose when a patient with multi-infarct dementia wanted to go for a drive and his son and grandson tried to convince him that he could no longer drive. What went wrong in the caregivers/patient interaction is presented. The futility of arguing with patients who have dementia is highlighted as well as the suspiciousness it may generate. Alternate actions that can be useful to avoid/avert the situation from escalating and having a catastrophic ending are discussed. Testing/evaluating patients with dementia for fitness to drive is also reviewed and a list of select resources is included

    Optical Properties of Radio-selected Narrow Line Seyfert 1 Galaxies

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    We present results from the analysis of the optical spectra of 47 radio-selected narrow-line Seyfert 1 galaxies (NLS1s). These objects are a subset of the First Bright Quasar Survey (FBQS) and were initially detected at 20 cm (flux density limit ~1 mJy) in the VLA FIRST Survey. We run Spearman rank correlation tests on several sets of parameters and conclude that, except for their radio properties, radio-selected NLS1 galaxies do not exhibit significant differences from traditional NLS1 galaxies. Our results are also in agreement with previous studies suggesting that NLS1 galaxies have small black hole masses that are accreting very close to the Eddington rate. We have found 16 new radio-loud NLS1 galaxies, which increases the number of known radio-loud NLS1 galaxies by a factor of ~5.Comment: 18 pages, 20 figures, Accepted for publication in Ap

    Too Many Choices Confuse Patients With Dementia

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    Choices are often difficult to make by patients with Alzheimer Dementia. They often become acutely confused when faced with too many options because they are not able to retain in their working memory enough information about the various individual choices available. In this case study, we describe how an essentially simple benign task (choosing a dress to wear) can rapidly escalate and result in a catastrophic outcome. We examine what went wrong in the patient/caregiver interaction and how that potentially catastrophic situation could have been avoided or defused

    Improving Critical Speed Calculations Using Flexible Bearing Support FRF Compliance Data.

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    LecturePg. 69-78The importance of including flexible supports in rotordynamic analyses is discussed. Various methods of including the support in rotordynamic calculations are reviewed. A method is described in which actual compliance frequency response function, FRF, data are used directly in a rotordynamic forced response computer program to accurately predict a steam turbine rotor's critical speed. The flexible support model is described as two single degree of freedom, SDOF, spring-mass-damper systems per bearing support. The methodology of acquiring the FRF data via impact hammer testing is described, and the equations are summarized that incorporate the FRF data into the flexible support model. Three flexible support models of increasing sophistication are used to analytically predict the rotor and support resonances. These results are compared to the actual steam turbine speed-amplitude plots. Modelling the support as many speed dependent SDOF systems accurately predicts the location of the rotor's first critical speed and also the split critical peaks and several support resonance speeds
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