Doppler cooling of calcium ions using a dipole-forbidden transition

Doppler cooling of calcium ions has been experimentally demonstrated using the S1/2 to D5/2 dipole-forbidden transition. Scattering forces and fluorescence levels a factor of 5 smaller than for usual Doppler cooling on the dipole allowed S1/2 to P1/2 transition have been achieved. Since the light scattered from the ions can be monitored at (violet) wavelengths that are very different from the excitation wavelengths, single ions can be detected with an essentially zero background level. This, as well as other features of the cooling scheme, can be extremely valuable for ion trap based quantum information processing.Comment: 4 pages, 4 figures, minor changes to commentary and reference

Experimental study of bubble cavities attached to a rotating shaft in a reservoir

Bubble cavities formed by air entrainment and attached to a rotating shaft in an oil reservoir were studied. The cavities appear to the unaided eye as toroidal. High speed photography, however, reveals the individuality of the bubble cavities and their near solid body rotational characteristics. The cavities are distorted by the rotation effects but remain attached and tend to merge because of edge effects in the axial direction. The flow field within the reservoir is influenced by the unusual character of the two phase fluid found there; the vorticity is readily visualized. Other examples of vapor entrapment at the inlet of an eccentric rotor are also discussed. A simplified analytical method is provided, and a numerical analysis is being investigated. Vapor (void) entrainment and generation can significantly alter leakage rates and stability of seals, bearings, and dampers. Recognition of these effects in the component design systems will result only after detailed studies of the above phenomena

Evaluation of seals for high-performance cryogenic turbomachines

An approach to computing flow and dynamic characteristics for seals or bearings is discussed. The local average velocity was strongly influenced by inlet and exit effects and fluid injection, which in turn drove zones of secondary flow. For the restricted three-dimensional model considered, the integral averaged results were in reasonable agreement with selected data. Unidirectional pressure measurements alone were insufficient to define such flow variations. However, for seal and bearing leakage correlations the principles of corresponding states were found to be useful. Also discussed are three phenomena encountered during testing of three eccentric nonrotating seal configurations for the Space Shuttle Main Engine (SSME) Program. Fluid injection, choking within a seal, and pressure profile crossover are related to postulated zones of secondary flow or separation and to direct stiffness

Curatorship applications: The role of neuropsychology

This article highlights ethical issues that may arise in the relationship between curatorship applications and neuropsychology. In South Africa (SA), curatorship applications for the elderly diagnosed with dementia require substantiation from two medical professionals, one of whom should be a practising psychiatrist deemed competent to provide this. Concurrently, there is often a request for a psychologist to conduct a neuropsychological assessment and to produce a relevant report. The process may result in ethical issues at various stages of the assessment. The balance between protecting the patient’s rights v. freedom of autonomy becomes a central issue. Psychiatrists and psychologists are cautioned to adhere to best practices throughout the assessment, maintaining a critical and reflective stance. The limitations of cognitive assessment as a predictor of functionality should be considered. Furthermore, neuropsychological training in SA differs across institutions, resulting in variable practitioner competency. ‘Competency’ itself is an ambiguous legal term that may be interpreted variably. This article outlines the definitions and requirements of the curatorship process, as well as the role and limitations of neuropsychology, with emphasis on the ethical dilemmas that may arise

Nested subcritical flows within supercritical systems

In supercritical systems the design inlet and outlet pressures are maintained above the thermaodynamic critical pressure P sub C. Designers rely on this simple rule of thumb to circumvent problems associated with a subcritical pressure regime nested within the supercritical pressure system along with the uncertainties in heat transfer, fluid mechanics, and thermophysical property variations. The simple rule of thumb is adequate in many low-power designs but is inadequate for high-performance turbomachines and linear systems, where nested two-phase regions can exist. Examples for a free-jet expansion with backpressure greater than P sub C and a rotor (bearing) with ambient pressure greater than P sub C illustrate the existence of subcritical pressure regimes nested within supercritical systems

Neurofibromatosis (von Recklinghausen's disease) - An unusual cause of parenchymal lung disease : a case report

CITATION: Hardcastle, S. W. & Hendricks, M. L. 1984. Neurofibromatosis (von Recklinghausen's disease) - An unusual cause of parenchymal lung disease : a case report. South African Medical Journal, 66:959-960.The original publication is available at http://www.samj.org.zaInterstitial pulmonary fibrosis and bullae are uncommon findings in neurofibromatosis. A case of this disease with pulmonary parenchymal involvement is presented and the association between the two is discussed.Publisher’s versio

Numerical modeling of multidimensional flow in seals and bearings used in rotating machinery

The rotordynamic behavior of turbomachinery is critically dependent on fluid dynamic rotor forces developed by various types of seals and bearings. The occurrence of self-excited vibrations often depends on the rotor speed and load. Misalignment and rotor wobbling motion associated with differential clearance were often attributed to stability problems. In general, the rotative character of the flowfield is a complex three dimensional system with secondary flow patterns that significantly alter the average fluid circumferential velocity. A multidimensional, nonorthogonal, body-fitted-grid fluid flow model is presented that describes the fluid dynamic forces and the secondary flow pattern development in seals and bearings. Several numerical experiments were carried out to demonstrate the characteristics of this complex flowfield. Analyses were performed by solving a conservation form of the three dimensional Navier-Stokes equations transformed to those for a rotating observer and using the general-purpose computer code PHOENICS with the assumptions that the rotor orbit is circular and that static eccentricity is zero. These assumptions have enabled a precise steady-state analysis to be used. Fluid injection from ports near the seal or bearing center increased fluid-film direct dynamic stiffness and, in some cases, significantly increased quadrature dynamic stiffness. Injection angle and velocity could be used for active rotordynamic control; for example, injection, when compared with no injection, increased direct dynamic stiffness, which is an important factor for hydrostatic bearings

A Fixed-Radius Point Count Method for Nonbreeding and Breeding-Season Use

We provide a detailed description of a fixed-radius point count method that carries fewer assumptions than most of the currently popular methods of estimating bird density and that can be used during both the nonbreeding and breeding seasons. The method results in three indices of bird abundance, any of which can be used to test for differences in community composition among sites, or for differences in the abundance of a given bird species among sites. These indices are (1) the mean number of detections within 25 m of the observer, (2) the frequency of detections within 25 m of the observer, and (3) the frequency of detections regardless of distance from the observer. The overall ranking of species abundances from a site is similar among the three indices, but discrepancies occur with either rare species that are highly detectable at great distances or common species that are repulsed by, or inconspicuous when near, the observer. We argue that differences in the behavior among species will preclude an accurate ranking of species by abundance through use of this or any other counting method in current use

High-Risk Corneal Graft Rejection in the Setting of Previous Corneal Herpes Simplex Virus (HSV)-1 Infection

Acknowledgments The authors thank M. Robertson and R. Fordyce for technical support during the duration of the study. The work performed in Aberdeen was supported by grant from Action Medical Research UK (SP4328; London, England, UK), NHS Grampian Endowment grant (12/49; Aberdeen, Scotland, UK), and Saving Sight in Grampian (Charity No.SC002938; Aberdeen, Scotland, UK). The work performed in Pittsburgh was supported by a Fight for Sight Post-Doctoral Award (JEK; New York, NY, USA); unrestricted grants from the Western Pennsylvania Medical Eye Bank Foundation (Pittsburgh, PA, USA), Research to Prevent Blindness (New York, NY, USA), and the Eye and Ear Foundation of Pittsburgh (RLH; Pittsburgh, PA, USA); and National Institutes of Health Grants P30EY08098 (RLH; Bethesda, MD, USA) and EY10359 (RLH).Peer reviewedPublisher PD

COMMUNICATION: Electrochemical polymerization of conducting polymers in living neural tissue

A number of biomedical devices require extended electrical communication with surrounding tissue. Significant improvements in device performance would be achieved if it were possible to maintain communication with target cells despite the reactive, insulating scar tissue that forms at the device–tissue interface. Here, we report that the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) can be polymerized directly within living neural tissue resulting in an electrically conductive network that is integrated within the tissue. Nano and microscale PEDOT filaments extend out from electrode sites, presumably forming within extracellular spaces. The cloud of PEDOT filaments penetrates out into the tissue far enough that it should be possible to bypass fibrous scar tissue and contact surrounding healthy neurons. These electrically functional, diffuse conducting polymer networks grown directly within tissue signify a new paradigm for creating soft, low impedance implantable electrodes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58177/2/jne7_2_l02.pd