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  • 1
    Electronic Resource
    Electronic Resource
    The role of polarization current in magnetic island evolution (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 2835-2848 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The polarization current plays an important role in the evolution of magnetic islands with a width comparable to the characteristic ion orbit width. Understanding the evolution of such small magnetic islands is important for two reasons: (1) to investigate the threshold mechanisms for growth of large-scale islands (e.g., neoclassical tearing modes), and (2) to describe the drive mechanisms for small-scale magnetic turbulence and consequent transport. This article presents a two-fluid, cold ion, collisional analysis of the role of the polarization current in magnetic island evolution in slab geometry. It focuses on the role played by the conjunction of parallel electron dynamics and perpendicular transport (particle diffusion and viscosity) in determining the island rotation frequency and the distribution of the polarization current within the island. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1370062
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  • 2
    Electronic Resource
    Electronic Resource
    Resistive wall modes and nonuniform wall rotation (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 4062-4072 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The resistive wall mode (RWM) poses a threat to many plasma confinement devices. The continuous rotation of the wall relative to the plasma makes it appear perfectly conducting, because of the skin effect, but this is ineffective if the perturbation locks to the wall. This raises the question of whether a nonuniformly rotating wall is more effective. In this paper we discuss the effect of such nonuniform wall rotation, in both the toroidal and poloidal directions, on resonant and nonresonant RWMs. In the case of toroidal rotation it is shown that at large wall velocity both the resonant and nonresonant RWMs are stabilized, even though the nonresonant mode rotates with the maximum wall velocity. In the case of poloidal rotation RWMs do not lock to the wall and have a complicated behavior at intermediate velocities. However they are again stabilized by large wall velocity. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1388035
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  • 3
    Electronic Resource
    Electronic Resource
    Combined ultrasound and biochemical screening for Down's Syndrome in the first trimester: a Scottish multicentre study (2002)
    Oxford, UK : Blackwell Science Ltd
    BJOG 109 (2002), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To evaluate the use of ultrasound measurements of fetal nuchal translucency (NT) obtained in a routine antenatal clinic setting in combination with appropriate biochemical markers as a first trimester screening test for Down's Syndrome.Design Multicentre observational study.Setting Fifteen Scottish maternity units.Population Pregnant women (n= 17,229) attending routine antenatal clinics at 10–14 weeks of gestation.Methods NT measurements were attempted in all women along with the measurement of maternal serum free beta human chorionic gonadotrophin (FβhCG) and pregnancy-associated plasma protein-A (PAPP-A). All results were converted to multiples of the appropriate gestational median (MoM) and using a statistical model the risk of an affected pregnancy was derived. No results were given to participating women but all were offered routine second trimester biochemical screening. All cases of Down's Syndrome within the study group were ascertained and the detection rate for each marker was estimated.Main outcome measures Success rate of obtaining NT measurements and overall effectiveness of ultrasound and biochemical markers individually and in combination for the detection of Down's Syndrome pregnancies.Results NT measurements were obtained in 72.9% of women and blood samples in 98.4%. Forty-five cases of Down's Syndrome were ascertained (2.6/1000). NT measurements were obtained in 37 cases (median NT 1.65 MoM), blood samples in 42 cases and both NT and blood in 34 cases. In combination with the a priori maternal age risk, observed detection rates at a 5% false positive rate were 20/37 (54%) for NT, 23/42 (55%) for FβhCG and PAPP-A and 28/34 (82%) for a combination of NT, FβhCG and PAPP-A using a cutoff risk of 1:250. The effect of failing to obtain NT measurements in all cases reduces the overall detection rate to 62% (i.e. 28/45) if the entire series of affected pregnancies within the study group is considered.Conclusions NT in combination with appropriate serum markers has the potential to detect over 80% of Down's Syndrome fetuses in early pregnancy. However, NT measurement is highly operator-dependent. It requires training, external quality control and adequate time to allow accurate measurement, otherwise suboptimal performance will result.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.2002.01394.x
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  • 4
    Electronic Resource
    Electronic Resource
    Nearside–farside analysis of differential cross sections using Jacobi functions of the first and second kinds: Application to Ar+N2 rotationally inelastic scattering (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 5194-5206 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the first nearside–farside (NF) analysis of angular scattering for an inelastic molecular collision in which the partial wave series for the scattering amplitude is expanded in a basis set of reduced rotation matrix elements dmf,miJ(θ), where θ is the scattering angle, J is the total angular momentum quantum number, and mi,mf are initial and final helicity quantum numbers, respectively. The practical implementation of the NF theory is described in detail; it exploits in an essential way the properties of a function that we denote emf,miJ(θ) and call a reduced rotation matrix element of the second kind. The caustic structure of dmf,miJ(θ) and emf,miJ(θ) is taken into account via a restricted nearside–farside (resNF) decomposition of the scattering amplitude. The resNF theory is used to analyze polarization and degeneracy averaged differential cross sections for the Ar+N2(ji=2,mi=0,±1,±2)→Ar+N2(jf=2,mf=0,±1,±2) collision system, treated as an atom+rigid-rotor. The resNF analysis always provides a clear physical interpretation of the scattering (except sometimes for θ(approximate)0°,180°) for phenomena such as diffraction oscillations and potential rainbows, as well as for more complicated (unnamed) interference effects. We also report results for some approximations to the resNF theory. Mathematical properties of the emf,miJ(θ) required for the resNF analysis are derived. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1335658
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  • 5
    Electronic Resource
    Electronic Resource
    The utility of the 13C-galactose breath test as a measure of liver function (2003)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 18 (2003), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : The 13C-galactose breath test has been reported to be an accurate, non-invasive method for the assessment of liver function.Aims : To determine the optimal doses of labelled and unlabelled carrier galactose necessary to perform the 13C-galactose breath test, to assess the utility of the 13C-galactose breath test in distinguishing between normal subjects and those with liver cirrhosis and to determine whether the 13C-galactose breath test can stratify patients with cirrhosis based on their Child–Pugh score.Methods : Twenty-three control subjects and 30 patients with liver cirrhosis received fixed doses of unlabelled carrier galactose and labelled 13C-galactose. Breath samples were collected just before and at 30-min intervals up to 4 h after the ingestion of unlabelled carrier galactose and labelled 13C-galactose. Each sample was analysed for its 13CO2 content.Results : Doses of 25 g/m2 of unlabelled carrier galactose and 100 mg of 13C-galactose had the greatest sensitivity (93%; 95% confidence interval, 76–99%) and specificity (87%; 95% confidence interval, 65–97%) for distinguishing between normal subjects and cirrhotics when the test was performed 2 h after ingestion. The 13C-galactose breath test was also able to distinguish between class A and class B or C cirrhotics.Conclusion : The 13C-galactose breath test is a useful non-invasive tool for distinguishing between healthy subjects and patients with liver cirrhosis and between cirrhotics with well-compensated liver disease and those with decompensated liver disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2003.01753.x
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  • 6
    Electronic Resource
    Electronic Resource
    Development Early-pregnancy origins of low birth weight (2002)
    [s.l.] : Nature Publishing Group
    Nature 417 (2002), S. 916-916 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Low birth weight is a significant cause of morbidity and mortality among newborns, and may result from impaired placental function during the first trimester of pregnancy. Here we show that the risk of delivering a low-birth-weight baby at term after an uncomplicated pregnancy varies with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/417916a
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  • 7
    Electronic Resource
    Electronic Resource
    Simulation of START shots with the canonical profile transport model (2000)
    Springer
    Plasma physics reports 26 (2000), S. 539-549 
    Details
    ISSN: 1562-6938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The canonical profile transport model, which has been benchmarked previously for tokamaks with a conventional aspect ratio, is applied to simulations of the spherical tokamak START. A set of Ohmic shots is used to modify the model so that it is appropriate for the specific conditions of the spherical tokamak plasma. The application of the model as a tool to analyze neutral beam-heated START shots allows the estimation of the neutral beam-injection power absorbed by the plasma, P NB abs , which is experimentally uncertain. The modeling shows that both P NB abs and the energy confinement time increase with increasing the average density. Finally, the modified model is used to simulate the performance of the new megaampere spherical tokamak MAST at Culham.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.952889
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  • 8
    Electronic Resource
    Electronic Resource
    Transient transfection induces different intracellular calcium signaling in CHO K1 versus HEK 293 cells (2000)
    Springer
    Cytotechnology 33 (2000), S. 139-145 
    Details
    ISSN: 1573-0778
    Keywords: calcium phosphate ; CHO-K1 ; cytosolic calcium signaling ; HEK 293 ; laser scanning confocal microscopy ; transient transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract For the controlled production of recombinant proteinsin mammalian cells by transient transfection, it maybe desirable not only to manipulate, but also todiagnose the expression success early. Here, weapplied laser scanning confocal microscopy to monitortransfection induced intracellular Ca2+responses. We compared Chinese hamster ovary (CHO K1)versus human embryo kidney (HEK) 293 cell lines, whichdiffer largely in their transfectability. An improvedcalcium phosphate transfection method was used for itssimplicity and its demonstrated upscale potential.Cytosolic Ca2+ signaling appeared to inverselyreflect the cellular transfection fate. Virtually allCHO cells exhibited asynchronous, cytosolicCa2+ oscillations, which peaked 4 h afteraddition of the transfecting solution. Yet, most ofthe HEK cells displayed a slow and continuousCa2+ increase over the time of transfection. CHOcells, when exposed to a transfection-enhancingglycerol shock, strongly downregulated their Ca2+response, including its oscillations. When treatedwith thapsigargin, a Ca2+ store depleting drug,the number of successfully transfected CHO cells was significantly reduced. Our result points tointracellular store release as a critical componentfor the transfection fate of CHO cells, and its early detection before product visualization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008150402616
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