Flowmeter measures low gas-flow rates

Positive-displacement flowmeter measures low gas-flow rates by gaging the time required for a slug of mercury to pass between two reference levels in a tube of known volume

Are checks overused?

This study overturns the conclusion of a 1990 study by David Humphrey and Allen Berger, which found that check float is responsible for the popularity of checks despite their high resource cost compared to electronic payment instruments. The new study examines recent data on the costs of checks and automated clearinghouse (ACH) payments. It finds that the value of check float has decreased significantly since the 1990 study and is no longer large enough to make checks more attractive than ACH payments. The study also questions whether the idea that float could be responsible for the persistent use of checks is reasonable given standard assumptions about the behavior of economic agents. The study ends by speculating on why checks are used more than less-costly alternatives and by encouraging policymakers to wait for researchers to adequately answer that question before intervening in the market for payment instruments.Clearinghouses (Banking)

Preliminary considerations of optical telescopes for lunar surface use

Design considerations of astronomical telescopes for lunar surface observatio

The tension between gauge coupling unification, the Higgs boson mass, and a gauge-breaking origin of the supersymmetric mu-term

We investigate the possibility of generating the $\mu$-term in the MSSM by the condensation of a field that is a singlet under the SM gauge group but charged under an additional family-independent $U(1)_X$ gauge symmetry. We attempt to do so while preserving the gauge coupling unification of the MSSM. For this, we find that SM non-singlet exotics must be present in the spectrum. We also prove that the pure $U(1)_X$ anomalies can always be solved with rationally charged fields, but that a large number of SM singlets are often required. For $U(1)_X$ charges that are consistent with an embedding of the MSSM in SU(5) or SO(10), we show that the $U(1)_X$ charges of the MSSM states can always be expressed as a linear combination of abelian subgroups of $E_6$. However, the SM exotics do not appear to have a straightforward embedding into GUT multiplets. We conclude from this study that if this approach to the $\mu$-term is correct, as experiment can probe, it will necessarily complicate the standard picture of supersymmetric grand unification.Comment: 10 pages, no figure

Gas flowmeter

Mass flowmeter measures rates of flow of all common gases from purges and collected leaks at leak ports. Without dependence on gravity, it measures rates between 5 and 650 cc/min with pressures ranging from 0.001 to 10 to the minus thirteenth torr at temperatures between 70 and 500 degrees K

A study of some reactor shielding problems for spacecraft applications

Programs to calculate single-scattered neutron and gamma fluxes from reactor-powered spacecraft radiators and sample calculations from unshielded SNAP-