A Color-Magnitude Diagram for a Globular Cluster In the Giant Elliptical Galaxy NGC 5128

The Hubble Space Telescope has been used to obtain WFPC2 (V,I) photometry for a large sample of stars in the outer halo of the giant elliptical NGC 5128 (d = 4 Mpc). The globular cluster N5128-C44, at the center of the Planetary Camera field, is well enough resolved to permit the construction of a color-magnitude diagram (CMD) for it which covers the brightest two magnitudes of the giant branch. The CMD is consistent with that of a normal old, moderately low-metallicity ([Fe/H] = -1.30 globular cluster, distinctly more metal-poor than most of the field halo stars at the same projected location (which average [Fe/H] ~ -0.5). This is the most distant globular cluster in which direct color-magnitude photometry has been achieved to date, and the first one belonging to a giant E galaxy.Comment: 12 pages, LaTeX, including 5 postscript figures; submitted to Astronomical Journa

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Static and forward speed tests were made in a 40 multiplied by 80 foot wind tunnel of a large-scale, ejector-powered V/STOL aircraft model. Modifications were made to the model following earlier tests primarily to improve longitudinal acceleration capability during transition from hovering to wingborne flight. A rearward deflection of the fuselage augmentor thrust vector was shown to be beneficial in this regard. Other augmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also showed negligible influence on the performance of the wing and of the fuselage augmentor

Dusty plasma cavities: probe-induced and natural

A comprehensive exploration of regional dust evacuation in complex plasma crystals is presented. Voids created in 3D crystals on the International Space Station have provided a rich foundation for experiments, but cavities in dust crystals formed in ground-based experiments have not received as much attention. Inside a modified GEC RF cell, a powered vertical probe was used to clear the central area of a dust crystal, producing a cavity with high cylindrical symmetry. Cavities generated by three mechanisms are examined. First, repulsion of micrometer-sized particles by a negatively charged probe is investigated. A model of this effect developed for a DC plasma is modified and applied to explain new experimental data in RF plasma. Second, the formation of natural cavities is surveyed; a radial ion drag proposed to occur due to a curved sheath is considered in conjunction with thermophoresis and a flattened confinement potential above the center of the electrode. Finally, cavity formation unexpectedly occurs upon increasing the probe potential above the plasma floating potential. The cavities produced by these methods appear similar, but each are shown to be facilitated by fundamentally different processes.Comment: 10 pages, 12 figure

Effects of digital altimetry on pilot workload

A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA

HST Photometry for the Halo Stars in the Leo Elliptical NGC 3377

We have used the ACS camera on HST to obtain (V,I) photometry for 57,000 red-giant stars in the halo of the Leo elliptical NGC 3377. We use this sample of stars to derive the metallicity distribution function (MDF) for its halo field stars, and comment on its chemical evolution history compared with both larger and smaller E galaxies. Our ACS/WFC field spans a radial range extending from 4 to 18 kpc projected distance from the center of NGC 3377 and thus covers a significant portion of this galaxy's halo. We find that the MDF is broad, reaching a peak at [m/H] ~ -0.6$, but containing virtually no stars more metal-poor than log [m/H] = -1.5$. It may, in addition, have relatively few stars more metal-rich than [m/H] = -0.3$, although interpretation of the high-metallicity end of the MDF is limited by photometric completeness that affects the detection of the reddest, most metal-rich stars. NGC 3377 appears to have an enrichment history intermediate between those of normal dwarf ellipticals and the much larger giants. As yet, we find no clear evidence that the halo of NGC 3377 contains a significant population of ``young'' (< 3 Gy) stars.Comment: 40 pages, 17 figure

Cold water aquifer storage

A working prototype system is described in which water is pumped from an aquifer at 70 F in the winter time, chilled to a temperature of less than 50 F, injected into a ground-water aquifer, stored for a period of several months, pumped back to the surface in the summer time. A total of 8.1 million gallons of chilled water at an average temperature of 48 F were injected. This was followed by a storage period of 100 days. The recovery cycle was completed a year later with a total of 8.1 million gallons recovered. Approximately 20 percent of the chill energy was recovered

Transport on randomly evolving trees

The time process of transport on randomly evolving trees is investigated. By introducing the notions of living and dead nodes a model of random tree evolution is constructed which describes the spreading in time of objects corresponding to nodes. By using the method of the age-dependent branching processes we derive the joint distribution function of the number of living and dead nodes, and determine the correlation between these node numbers as a function of time. Also analyzed are the stochastic properties of the end-nodes; and the correlation between the numbers of living and dead end-nodes is shown to change its character suddenly at the very beginning of the evolution process. The survival probability of random trees is investigated and expressions are derived for this probability.Comment: 16 pages, 8 figures, published in Phys. Rev. E 72, 051101 (2005

Fluctuations of the heat flux of a one-dimensional hard particle gas

Momentum-conserving one-dimensional models are known to exhibit anomalous Fourier's law, with a thermal conductivity varying as a power law of the system size. Here we measure, by numerical simulations, several cumulants of the heat flux of a one-dimensional hard particle gas. We find that the cumulants, like the conductivity, vary as power laws of the system size. Our results also indicate that cumulants higher than the second follow different power laws when one compares the ring geometry at equilibrium and the linear case in contact with two heat baths (at equal or unequal temperatures). keywords: current fluctuations, anomalous Fourier law, hard particle gasComment: 5 figure