We report on extensive testing carried out on the optical fibers for the VIRUS instrument. The primary result of this work explores how 10+ years of simulated wear on a VIRUS fiber bundle affects ...both transmission and focal ratio degradation (FRD) of the optical fibers. During the accelerated lifetime tests we continuously monitored the fibers for signs of FRD. We find that transient FRD events were common during the portions of the tests when motion was at telescope slew rates, but dropped to negligible levels during rates of motion typical for science observation. Tests of fiber transmission and FRD conducted both before and after the lifetime tests reveal that while transmission values do not change over the 10+ years of simulated wear, a clear increase in FRD is seen in all 18 fibers tested. This increase in FRD is likely due to microfractures that develop over time from repeated flexure of the fiber bundle, and stands in contrast to the transient FRD events that stem from localized stress and subsequent modal diffusion of light within the fibers. There was no measurable wavelength dependence on the increase in FRD over 350 nm to 600 nm. We also report on bend radius tests conducted on individual fibers and find the 266 microns VIRUS fibers to be immune to bending-induced FRD at bend radii of R > 10cm. Below this bend radius FRD increases slightly with decreasing radius. Lastly, we give details of a degradation seen in the fiber bundle currently deployed on the Mitchell Spectrograph (formally VIRUS-P) at McDonald Observatory. The degradation is shown to be caused by a localized shear in a select number of optical fibers that leads to an explosive form of FRD. In a few fibers, the overall transmission loss through the instrument can exceed 80%.
The lifetime and oscillation frequency of the B
0 meson has been measured using
B
̄
0→
D
∗+ℓ
−
ν
̄
decays recorded on the Z
0 peak with the OPAL detector at LEP. The
D
∗+→
D
0π
+
decays were ...reconstructed using an inclusive technique and the production flavour of the B
0 mesons was determined using a combination of tags from the rest of the event. The results
τ
B
0
=1.541±0.028±0.023
ps,
Δm
d
=0.497±0.024±0.025
ps
−1
were obtained, where in each case the first error is statistical and the second is systematic.
The process e
+e
−→
γγ(
γ) is studied using data recorded with the OPAL detector at LEP. The data sample taken at a centre-of-mass energy of 189 GeV corresponds to a total integrated luminosity of ...178 pb
−1. The measured cross-section agrees well with the expectation from QED. A fit to the angular distribution is used to obtain improved limits at 95% CL on the QED cut-off parameters:
Λ
+> 304 GeV and
Λ
−> 295 GeV as well as a mass limit for an excited electron,
M
e
∗
>
306 GeV assuming equal
e
∗eγ
and eeγ couplings. Graviton exchange in the context of theories with higher dimensions is excluded for scales
G
+< 660 GeV and
G
−< 634 GeV. No evidence for resonance production is found in the invariant mass spectrum of photon pairs. Limits are obtained for the cross-section times branching ratio for a resonance decaying into two photons and produced in association with another photon.
The types and concentrations of sweeteners in common prescription liquid and chewable medications for pediatric use were determined by manufacturer survey. Oral-liquid and chewable antibiotic, ...antifungal, bronchodilator, antihistamine, anticonvulsant, and miscellaneous products were identified. The manufactures were asked by telephone the type and amount of sweeteners in their products. Two follow-up letters requested confirmation of the sweetener contents; manufacturers' approval for publication of the information was also requested by mail. Sweetener information on 160 preparations was obtained. For antibiotics such as ampicillin, amoxicillin, erythromycin ethylsuccinate, and penicillin VK, products from different manufacturers had a wide range of sucrose concentration (18%-80%). Only four antibiotic preparations were sucrose free. The bronchodilators and antihistamines contained either sucrose, sorbitol, or saccharin. The anticonvulsants contained 0%-60% sucrose. Health-care practitioners who prescribe or dispense oral liquid or chewable prescription drug products should know that products in a given category can vary in type and amount of sweetener.
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