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  • 1
    ISSN: 1572-9559
    Keywords: SIS receiver ; twin-slot planar antenna ; NbTiN superconductor ; bandgap energy ; AlN tunnel barrier ; RF loss ; cooled optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have developed a niobium titanium nitride (NbTiN) based superconductor-insulator-superconductor (SIS) receiver to cover the 350 micron atmospheric window. This frequency band lies entirely above the energy gap of niobium (700 GHz), a commonly used SIS superconductor. The instrument uses an open structure twin-slot SIS mixer that consists of two Nb/AlN/NbTiN tunnel junctions, NbTiN thin-film microstrip tuning elements, and a NbTiN ground plane. The optical configuration is very similar to the 850 GHz waveguide receiver that was installed at the Caltech Submillimeter Observatory (CSO) in 1997. To minimize front-end loss, we employed reflecting optics and a cooled beamsplitter at 4 K. The instrument has an uncorrected receiver noise temperature of 205K DSB at 800 GHz and 410K DSB at 900 GHz. The degradation in receiver sensitivity with frequency is primarily due to an increase in the mixer conversion loss, which is attributed to the mismatch between the SIS junction and the twin-slot antenna impedance. The overall system performance has been confirmed through its use at the telescope to detect a wealth of new spectroscopic lines.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7284
    Keywords: Alcohol consumption ; Coffee consumption ; Hospital workers ; Logistic regression ; Miscarriage ; Spontaneous abortion ; Tobacco smoking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of this study was to examine the possible relationships between spontaneous abortion and caffeine, tobacco and alcohol intake in a well-controlled group of hospital workers. A retrospective cohort study design including 711 women, 20 to 41 years old, was used. All data regarding the purpose of this study were extracted from clinical histories registered at the Preventive Medicine Service. The dependent variable was spontaneous abortion and the independent variables were tobacco, coffee, and alcohol intake. Age, previous spontaneous abortion, menarcheal age and marital status were considered as potential confounders. The data were analyzed by multiple logistic regression. The following adjusted odds ratios of spontaneous abortion by caffeine consumption were calculated: 141–280 mg/day, 2.20 (1.22–3.96); 281–420 mg/day, 4.81 (2.28–10.14) and 421 or more, 15.43 (7.38–32.43);p〈0.05. The adjusted odds ratio for tobacco were 11 or more cigarettes/day, 3.35 (1.65–6.92);p〈0.05. It appears from this and other papers that tobacco and caffeine intake must be considered as clear risk factors for spontaneous abortion or miscarriage.
    Type of Medium: Electronic Resource
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