Site location and requirements for the installation of a nuclear magnetic resonance scanning unit

The installation of a nuclear magnetic resonance unit in any diagnostic facility involves certain location and environmental requirements. Based on our experience with the FONAR QED 80 system, we have delineated the major factors which must be considered when planning for such an installation. The major requirements are location and space. Suggested layouts for the suite and the control room are included. Certain environmental specifications will vary depending on the location of the facility and the type of unit installed.     

Direct analytical solutions to non-uniform beam problems

The direct analytical solution to the vibration of non-uniform beams with and without discontinuities and with various boundary conditions is presented. Results are compared to results from the exact solution for certain cases where the exact solution has been obtained. It is shown that the direct solution converges to the exact solution, in fact, with “indefinite accuracy” just as Hamilton stated that it would.     

The assembly of lipid-linked oligosaccharides in plant and animal membranes.

Membrane preparations from growing regions of pea stems and actively-dividing mouse L-cells form lipid-linked saccharides from GDP-mannose and UDP-N-acetylglucosamine. These lipids have properties which are consistent with those of mono- and di-phosphoryl polyisoprenyl derivatives. In experiments using plant membranes, the monophosphoryl derivative labeled with GDP-(14C) mannose contains mannose only, while the diphosphoryl derivative labeled with the same nucleotide sugar is heterogeneous, containing oligosaccharides corresponding to mannosaccharides of 5, 7, and 9--12 residues. Only the diphosphoryl polyisoprenyl derivatives are labeled with UDP-(14C)glucosamine and these contain predominantly chitobiose and N-acetylglucosamine itself. Unlabeled GDP-mannose added after UDP-N-acetyl-(14C)glucosamine results in the formation of higher lipid-linked oligosaccharides which are apparently the same as those which are labeled with GDP-(14C)mannose alone. Incubation of the membranes with GDP-(14C)mannose in the presence of Mn2+, unlabeled UDP-glucose or unlabeled UDP-N-acetylglucosamine results in marked changes in the accumulation of both the polyisoprenyl monophosphoryl mannose and polyisoprenyl diphosphoryl oligosaccharides. Animal cell membranes synthesise lipid-linked oligosaccharides when incubated with UDP-N-acetylglucosamine and GDP-mannose. These oligosaccharides are similar in size to those synthesised by the plant membranes but their formation is more efficient. The potential roles of these compounds in glycoprotein biosynthesis in both plant and animal tissues is discussed.     

Measurement of mass and lifetime of hadronically produced charmed F mesons

We have observed three unique decays of F mesons into KKπ and five unique decays of D mesons into KKπ using the NA11 spectrometer together with a telescope of high-resolution silicon microstrip detectors. The mass value obtained for the F meson is (1975 ± 4) MeV, the lifetime (3.2±_1.3^3..0)×10^?13 s.     

A systematic investigation into the recovery of radioactively labeled proteins from sodium dodecyl sulfate-polyacrylamide gels

We report the results of a systematic investigation designed to optimize a method for quantifying radioactivity in proteins in sodium dodecyl sulfate-polyacrylamide gels. The method involves dissolving appropriately sized pieces of gel in hydrogen peroxide and heating to 70 degrees C overnight followed by liquid scintillation counting. H(2)O(2) had no effect on the count rates of [(14)C]bovine serum albumin (BSA) when counted in a conventional liquid scintillation system, and the count rates remained stable for several days. Temperatures below 70 degrees C resulted in incomplete extraction of radioactivity from gels containing [(14)C]BSA, but there was also a significant reduction in count rates in samples incubated at 80 degrees C. At 70 degrees C recovery was not affected by the amount of sample loaded onto the gel or by the staining procedure (Coomassie Brilliant Blue or SYPRO Ruby). Recoveries were in the range of 89-94%, and the coefficient of variation for five replicate samples was 5-10%. This method offers a reliable way of measuring the amount of radioactivity in proteins that have been separated by electrophoresis. It may be useful, for example, in quantitative metabolic labeling experiments when it is necessary to know precisely how much tracer has been incorporated into a particular protein.     

Hot dense capsule-implosion cores produced by Z-pinch dynamic Hohlraum radiation

Hot dense capsule implosions driven by Z-pinch x rays have been measured using a approximately 220 eV dynamic Hohlraum to implode 1.7-2.1 mm diameter gas-filled CH capsules. The capsules absorbed up to approximately 20 kJ of x rays. Argon tracer atom spectra were used to measure the T(e) approximately 1 keV electron temperature and the n(e) approximately 1-4 x 10(23) cm(-3) electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak emission values of T(e), n(e), and symmetry, indicating reasonable understanding of the Hohlraum and implosion physics.     

Search for pair production of scalar top quarks in R-parity violating decay modes in pp collisions at square root of s=1.8 TeV

We present the results of a search for pair production of scalar top quarks (t(1)) in an R-parity violating supersymmetry scenario in 106 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab. In this mode each t(1) decays into a tau lepton and a b quark. We search for events with two tau's, one decaying leptonically (e or mu) and one decaying hadronically, and two jets. No candidate events pass our final selection criteria. We set a 95% confidence level lower limit on the t(1) mass at 122 GeV/c(2) for Br(t(1)-->tau b)=1.     

Wet-etch optimization of free-standing terahertz frequency-selective structures

Free-standing frequency-selective surfaces consisting of approximately 10-microm-thick copper films with cross-aperture arrays are found to be tunable toward lower frequencies by means of wet chemical etching. Center frequencies were tuned from 1.57 to 1.53 THz while maintaining high transmittance. Wet etching also adjusts bandwidth, peak transmittance, and sidelobe transmittance. The advantage of the wet-etch technique is demonstrated by employment of these devices as bandpass filters for difluoromethane-based terahertz lasers. Adjustment in aperture dimensions because of etching results in suppression of a competing laser line (133.93 microm) by 15 dB while maintaining high transmittance at the operating wavelength of 192.06 microm.     

Laser-induced-fluorescence detection of SnO in low-pressure particle-synthesis flames

Ground-state SnO has been observed in a flame for the first time using laser-induced fluorescence. The (18-0) band of the E¹⁺-X¹⁺ transition is used for excitation. SnO is found to rapidly predissociate after excitation, and the tin atom emerges electronically excited, generating a fluorescence spectrum of atomic tin lines. This transition is found to be strong enough to excite in the linear regime, and the discrete nature of the fluorescence spectrum facilitates detection in environments with strong scattering and other interferences. However, quantitative analysis is hindered by a high density of SnO lines due to the many tin isotopes. Spatial SnO profiles in a hydrogen/oxygen/tetra-n-butyltin flame are obtained using this technique, and these profiles are qualitatively similar to metal monoxide profiles in other oxide-synthesis flames. PACS 42.62.Fi; 33.50.Dq; 81.20.Ka     

Measurement of prompt charm meson production cross sections in pp collisions at square root s = 1.96 TeV

We report on measurements of differential cross sections dsigma/dp(T) for prompt charm meson production in ppmacr; collisions at sqrt[s]=1.96 TeV using 5.8+/-0.3 pb(-1) of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y|K-pi(+), D(*+)-->D0pi(+), D+-->K-pi(+)pi(+), D(+)(s)-->phipi(+), and their charge conjugates. The measured cross sections are compared to theoretical calculations.