The purpose of this investigation is to study the validity of the “leaky box” propagationmodel and determine some of its parameters. The pathlength distributions and their energy dependencies are derived from measurements of secondary-toprimary abundance ratios. A special charged particle telescope carried on the Ulysses spacecraft has provided a complete separation of elements from hydrogen to...

The total instruction pathlength and instruction frequency counts are measured for the SPEC89 benchmark programs on the PA-RISC architecture and compared with previously published information for the MIPS and SPARC architectures. The PA-RISC architecture typically requires significantly fewer instructions than the other two architectures for the same benchmark. The differences in counts for ins...

Monte Carlo simulations are used to compute the uncertainty associated to light backscattering measurements in turbid waters using the ECO-BB (WET Labs) and Hydroscat (HOBI Labs) scattering sensors. ECO-BB measurements provide an accurate estimate of the particulate volume scattering coefficient after correction for absorption along the short instrument pathlength. For Hydroscat measurements, b...

We report the use of a novel hybrid near-infrared spectrometer for the measurement of optical scattering, pathlength and chromophore concentration in critically ill patients with brain injury. Ten mechanically ventilated patients with acute brain injury were studied. In addition to standard neurointensive care monitoring, middle cerebral artery flow velocity, brain lactate-pyruvate ratio (LPR) ...

We consider extended binary trees and study the common right and left depth of leaf j, where the leaves are labelled from left to right by 0, 1, . . . , n, and the common right and left external pathlength of binary trees of size n. Under the random tree model, i.e., the Catalan model, we characterize the common limiting distribution of the suitably scaled left depth and the difference between ...

We have used an intensity modulated optical spectrometer, which measures the phase shift across tissue experienced by intensity modulated near-infrared light, to determine the absolute optical pathlength through tissue. The instrument is portable and takes only 5 s to record pathlength at four wavelengths (690 nm, 744 nm, 807 nm and 832 nm). The absolute pathlength divided by the known spacing ...

In order to quantify near-infrared spectroscopic (NIRS) data on an inhomogeneous medium, knowledge of the contribution of the various parts of the medium to the total NIRS signal is required. This is particularly true in the monitoring of cerebral oxygenation by NIRS, where the contribution of the overlying tissues must be known. The concept of the time point spread function (TPSF), which is us...

This paper describes a robust and rapid procedure for measuring chlorophyll using a microplate reader. The procedure enables direct translation of any published equation developed on a 1-cm pathlength spectrophotometer to any format microplate with any sample volume. Chlorophylls were extracted with methanol because it is compatible with cheap polystyrene plates; however, the principles apply t...

Accurate knowledge of lightpath and parallelism of cuvettes used in spectrophotometry are indispensable parameters that must be determined when accurate transmittance measurements of liquid materials are considered. A description is given of the design and techniques developed at NBS for production of quartz cuvettes (SRM 932) having a nominal radiation pathlength of 10 mm ± 0.03 mm. For each c...