NICMOS and its arrays

NICMOS is a second generation instrument for the Hubble Space Telescope to provide imaging and spectroscopic capabilities in the near infrared region. NICMOS utilizes HgCdTe detectors in three cameras, one with grisms, to image in the 0.8–2.5 mm spectral region.     

Tsunami risk in northwestern Europe: a Holocene example

A thin, regionally extensive, laterally persistent sand layer is present within the Holocene coastal sequences of eastern Scotland, dated to 7000 yr BP. It is proposed that this deposit was caused by a tsunami wave generated by a catastrophic submarine landslide (the Second Storegga Slide) on the Norwegian continental slope. The distribution of this tsunami deposit indicates that the wave penetrated at least 2 km beyond the contemporary coastline and a minimum of 4 m above the contemporary high-water mark. Although the frequency of tsunamis may be low in this region their effects should be considered for very long-term or very sensitive strategic developments at coastal sites.     

Collective neutrino-plasma interactions

Nonlinear processes describing the interaction of neutrinos with collective plasma oscillations and the excitation of plasma turbulence by a large neutrino flux is discussed. The excitation considered is the inverse processes of neutrino emission by plasma waves first considered by Tsytovich (V.N. Tsytovich, Soviet Fiz. Dokl. 9 (1965) 1114). The process is similar to a beam plasma instability considered as inverse Landau damping in which the usual electromagnetic interactions are important. In the neutrino beam relaxation the weak interaction can play a similar role. We emphasize here the possibility of another process namely the interaction of an intense neutrino flux with a strongly turbulent plasma. The turbulence can also be assumed to be due to the shock produced at the early stages of a type II supernova (SN) explosion. The scattering of the neutrinos in the turbulent plasma is shown to be sufficient for transferring momentum and energy from the neutrino flux to the plasma causing the shock to continue moving outward and eventually creating the blow-off of the mantle of the star producing type II SN.     

A comparison of cosmic ray composition measurements at the highest energies

In recent years the Fly's Eye and Akeno groups have presented analyses of the cosmic ray mass composition at energies above 10¹⁷ eV. While the analysis of the Fly's Eye group points to a likely change in mass composition from heavy to light at energies above 10¹⁸ eV, the Akeno analysis favours an unchanging composition. However, the two groups base their conclusions on simulations using quite different hadronic models. Here we present a comparison of the experiments using the same hadronic model and find that the agreement between the experiments is much improved. Under this model, both experiments measure a composition rich in iron around 10¹⁷ eV which becomes lighter at higher energies. However, the agreement is not complete, which indicates scope for improvement of the interaction model, or perhaps the need for a re-examination of the experimental results.     

The representer method for data assimilation in single-phase Darcy flow in porous media

We apply the representer method, a data assimilation algorithm, to single-phase Darcy flow in porous media. The measurement array that yields the assimilated data can be expressed as a vector of linear functionals of pressure. The a priori discretization errors in the representer method are analyzed in terms of the convergence properties of the underlying numerical schemes used in each part of the algorithm. We formulate some proof-of-concept numerical experiments that illustrate the error analysis.     

Microprocessor systems as an aid to estuarine studies in the laboratory

Three systems are outlined which indicate the potential of microprocessor systems as control devices in the generation of specifically varying environmental mental conditions. The use of an RCA 1802 Cosmac microprocessor to generate salinity cycles, tidal cycles and temperature cycles is described.     

Simplified analysis of offshore piles under cyclic lateral loads

A simple theory for predicting the response to cyclic lateral loading of piles deeply driven in either soft clay or sand is presented and formulas given for calculating, among other things, deflection and internal bending moment along the pile. The theory assumes the soil resistance to deflection to be characterized by an initial elastic reaction up to a critical deflection level, followed by a yield reaction independent of further deflection. Soil parameters are estimated and the theory is shown to provide good correlation with existing field data.