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  • 1
    Electronic Resource
    Electronic Resource
    Measurements of optical refrigeration in ytterbium-doped crystals (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4815-4819 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We measured anti-Stokes fluorescence cooling (optical refrigeration) in ytterbium-doped yttrium aluminum garnet (YAG). Pumping the 2.3% Yb3+:YAG crystal with 1.8 W of 1030 nm laser light produced a temperature drop of 8.9 °C from room temperature. The high thermal conductivity and ruggedness of this crystal make it an attractive material for use in optical refrigerators. Our spectral studies show that pure crystals of this material could be efficient for optical refrigeration at temperatures above ∼100 K. Photothermal deflection measurements show that our current crystals can cool at ∼250 K. Additionally, we measured optical refrigeration in a 5% Yb3+:Y2SiO5 crystal when pumped at 1050 nm. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1406544
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  • 2
    Electronic Resource
    Electronic Resource
    The NaCl pressure standard (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5801-5808 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A revised pressure scale for NaCl is proposed as an update for the 30-year-old work of Decker. An alternative approach to the analysis is utilized in conjunction with more recent data. The zero-Kelvin compression curve is parameterized using local basis functions (splines) and constrained by accurate pressure-volume-temperature data. Thermal pressures are estimated within a quasiharmonic framework using a volume-dependent Grüneisen parameter and the Debye thermal energy. In the pressure regime extending to 5 GPa uncertainties in pressure (based on measured volumes) are estimated to be less than 1%. Uncertainty increases to 1.5% at 10 GPa and 3% at 25 GPa. The largest contribution to systematic uncertainty at the highest pressures is the lack of knowledge of the volume dependence of the Grüneisen parameter. Misfit of other calculated thermodynamic properties with respect to data is relatively small. On the basis of the current analysis, pressures determined using the older Decker calibration are low. Along the 300 K isotherm, apparent errors in the Decker scale are as large as −3% (−0.3 GPa at 10 GPa, −0.47 GPa near 18 GPa, and −0.37 GPa at 25 GPa). At higher temperatures the apparent errors are smaller. At 1100 K and 20 GPa the error is −0.2 GPa. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371596
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  • 3
    Electronic Resource
    Electronic Resource
    Arsenic for antimony exchange on GaSb, its impacts on surface morphology, and interface structure (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 329-337 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We quantify the rates and total amounts of the arsenic for antimony exchange on both the Sb-terminated and Ga (or In)-terminated GaSb (001) surfaces using in situ real time line-of-sight mass spectrometry (LOS-MS) during molecular beam epitaxy. On the Sb-terminated GaSb (001) surface, an As for Sb exchange is observed to occur at all values of incident As2 flux considered. At high substrate temperature, three-dimensional (3D) nanometer-sized clusters from as a consequence of As/Sb exchange and lattice mismatch strain between GaAs and GaSb. The 3D clusters are found to have lateral dimensions of ∼10–30 nm and heights of 1–3 nm by atomic force microscopy (AFM). By contrast, at lower substrate temperatures a two-dimensional surface morphology is maintained, and AFM reveals an array of atomically flat terraces. On the surface terminated by one monolayer (ML) of Ga or In, there exists a critical As2 flux below which the As/Sb exchange is greatly diminished. The net amounts of Sb leaving the surface during one period of InAs/GaSb type-II superlattice growth are measured in real time by LOS-MS and estimated to be in the range of 0–0.4 ML for the various conditions used. By supplying only an As2 beam to a GaSb surface covered by InAs, the Sb riding over the InAs layer is replaced by arsenic and the total amount of such Sb is measured. The amount of Sb riding on the InAs can be as large as 0.8 ML for the first 1 ML of InAs and it gradually decreases to zero as the number of InAs monolayer increases. X-ray diffraction data show that all the InAs/GaSb superlattices coherently match with the GaSb substrate in the growth plane. The average lattice constant along the growth direction reduces with decreasing Sb mole fraction shown by the increased Sb desorption signal. Using the information on As/Sb exchange and Sb riding on the InAs surface, we predict an average lattice constant along the growth direction to be consistent with the measured one to within 2×10−4. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370733
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  • 4
    Electronic Resource
    Electronic Resource
    Density gradient columns: Dynamic modeling for linear profiles (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3973-3980 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Rigorous mathematical modeling of the process dynamics associated with the construction and filling of density gradient columns is presented in this article. These models incorporate the hydrostatic driving forces for fluid flow, friction losses associated with this flow, and the unsteady-state behavior of the liquid levels in the filling vessels and in the column itself. Four different filling arrangements are considered, corresponding to the density order of the two fluids in the filling vessels and two methods for introducing the fluid of varying density into the column. Time requirements for filling of the column and the resulting calibration curve for liquid density versus height in the gradient column are both obtained as a result of this modeling procedure. Further, extremely important operating guidelines for the final achievement of a linear density gradient in the column, which is normally the desired objective in most laboratory applications, are derived and presented. Conversely, the causes leading to nonlinear gradients are elucidated and quantified. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147301
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  • 5
    Electronic Resource
    Electronic Resource
    [3H]Homoquinolinate Binds to a Subpopulation of NMDA Receptors and to a Novel Binding Site (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 71 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: NMDA receptors mediate several important functions in the CNS; however, little is known about the pharmacology, biochemistry, and function of distinct NMDA receptor subtypes in brain tissue. To facilitate the study of native NMDA receptor subpopulations, we have determined the radioligand binding properties of [3H]homoquinolinate, a potential subtype-selective ligand. Using quantitative receptor autoradiography, NMDA-specific [3H]homoquinolinate binding selectively labeled brain regions expressing NR2B mRNA (layers I–III of cerebral cortex, striatum, hippocampus, and septum). NMDA-specific [3H]homoquinolinate binding was low in brain regions that express NR2C and NR2D mRNA (cerebellar granular cell layer, NR2C; glomerular layer of olfactory bulb, NR2C/NR2D; and midline thalamic nuclei, NR2D). In forebrain, the pattern of NMDA-specific [3H]homoquinolinate binding paralleled NR2B and not NR2A distribution. In addition to NMDA-displaceable binding, there was a subpopulation of [3H]homoquinolinate binding sites in the forebrain, cerebellum, and choroid plexus that was not displaced by NMDA or l-glutamate. In contrast, we found that the derivative of homoquinolinate, 2-carboxy-3-carboxymethylquinoline, markedly inhibited the NMDA-insensitive binding of [3H]homoquinolinate without inhibiting the NMDA-sensitive population. [3H]Homoquinolinate may be useful for selectively characterizing NR2B-containing NMDA receptors in a preparation containing multiple receptor subtypes and for characterizing a novel binding site of unknown function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.71041464.x
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  • 6
    Electronic Resource
    Electronic Resource
    Achieving early surgery for undescended testes: quality improvement through a multifaceted approach to guideline implementation (2004)
    Oxford, UK : Blackwell Science Ltd
    Child 30 (2004), S. 0 
    Details
    ISSN: 1365-2214
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Background  Surgery for undescended testes is recommended before the age of 2 years. However, boys are still undergoing surgery for undescended testes at a much later age than recommended.Methods  An initial audit reviewed all orchidopexies performed at Northampton General Hospital between 1992 and 1994. This demonstrated that only 19% of boys had surgery by the age of 2 years, and the key reason for late surgery was late referral. Guidelines for referral of undescended testes were established in which referral to a surgeon was advised following the 8-month child health surveillance check if undescended testis was suspected. This would enable surgery before the age of 2 years. Audit results were disseminated and we implemented a package of measures based on evidence based change management techniques. These included written advice to general practitioners (GPs), a parent information leaflet and an amended personal child health record advising timing of referral. A reminder to the GP to refer following the 8-month check was generated using computer recall from the Child Health System records. Guideline implementation was monitored by annual audit and feedback.Results  The baseline audit for the years 1992–94 found a median age at surgery of 4 years. Implementation of the new policies in 1998 resulted in a reduction in median age at surgery to 2.0 years in the 12 months ending September 2001.Conclusions  While concern about the age at orchidopexy has been highlighted in many previous studies, this is the first to show that improvement in the age at orchidopexy can be achieved. Implementing locally agreed guidelines with written information to GPs and parents combined with computerized recall from Child Health System records achieved the target within 3 years. Similar systems could be implemented nationally at minimal cost.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2214.2003.00398.x
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  • 7
    Electronic Resource
    Electronic Resource
    The Occurrence of Highly Unsaturated Fatty Acids in the Oils of Some Common Fowls and in Animal Fats (1934)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 56 (1934), S. 2149-2151 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01325a050
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of annealing on the defect structure in a-SiC:H films (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2216-2223 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The annealing behavior of amorphous, hydrogenated silicon carbide films in the range 400–900 °C was studied by optical characterization methods, 15N hydrogen profiling, and defect profiling using a variable energy positron beam. The films were deposited in an electron cyclotron resonance chemical vapor deposition system using ditertiary butyl silane [SiH2(C4H9)2] as the monosource for silicon and carbon. As-deposited films were found to contain large concentrations of hydrogen, both bonded and unbonded. Under rapid thermal annealing in a N2 atmosphere, the bonded hydrogen effuses giving rise to additional Si–C bond formation and to film densification. After annealing at high temperatures in N2, a marked decrease in the total hydrogen content is observed. After annealing in vacuum, however, the hydrogen effusion promotes void formation in the films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363049
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  • 9
    Electronic Resource
    Electronic Resource
    Hugoniot data for iron (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 5496-5498 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A definitive set of the Los Alamos Hugoniot data for iron in a pressure regime extending to 442 GPa is given. Earlier standards data, obtained using conventional explosive systems, were thoroughly reprocessed. All original film records were reread. On the basis of more recent experiment and theory, some data were culled because the experimental designs were found to be insufficiently conservative. The analysis was also modified to take into account preheating of the explosively driven flyer plates. Minor clerical errors in transcription of measurements were corrected. An improved algorithm for the flash-gap time correction was incorporated. Higher-pressure data were obtained using a conventional 13-pin target assembly on a two-stage light gas gun. Several polynomial representations of the data are given. A linear fit to the data (Us=3.935+1.578 Up, where the shock velocity Us and the particle velocity Up are in km/s) has a root-mean-square misfit of 62 m/s. The quadratic fit (Us=3.691+1.788 Up−0.038 Up2) has a root-mean-square misfit of 39 m/s. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1319320
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  • 10
    Electronic Resource
    Electronic Resource
    Collaborative development of a sun protection factor test method: a proposed European Standard. COLIPA Task Force ‘Sun Protection Measurement’, Europe (1996)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 18 (1996), S. 0 
    Details
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Standardization of the method to determine sun protection factors (SPF) is fundamental to uniform labelling of SPF values on sun products. The COLIPA Task Force ‘Sun Protection Measurement’(SPM), including representatives of major European sun-product manufacturers and contract testing laboratories, was established in 1990 to define methods for sun products testing. The process involved in developing the COLlPA SPF Test Method started with a critical appraisal of previously existing methods, and identification of areas for improvement. Experiments were performed by the participating laboratories to establish the new recommended test protocol which was then confirmed in two multicentred ring tests. Improvements to test methodology included the number and selection of volunteers and skin types, the application of the product, the definition of W output from solar simulators, and the method for assessing erythemal response (MED) including an option to use colorimetry to define objectively the ‘erythemal threshold’ of skin and to predetermine MED prior to exposure. Four cosmetic formulations and neutral density physical filters (SPF from 4 to 20) were tested in two ring tests. Results showed that variations in SPF of the cosmetic products were, on average, directly proportional to SPF value. An excellent correlation was found between visual and colorimetric SPF assessments (r = 0.99). An acceptable range of values for low and high SPF standard products was also established. The COLIPA SPF test method is now fully defined and supported by experimental data. Its use will harmonize SPF testing throughout Europe and help in the quest for global harmonization in testing sun products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-2494.1996.tb00151.x
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