Teleoperators for remote operations in space

The primary objective of the remote nuclear teleoperator study program was to define in detail a program plan which would provide a qualified operational space teleoperator system by about 1980. The concept and philosophy presented provides a product considered to be an advanced teleoperator when compared to today's state-of-the-art. The teleoperator concept is formulated to meet NERVA requirements

Scoping a public health impact assessment of aquaculture with particular reference to tilapia in the UK

Background. The paper explores shaping public health impact assessment tools for tilapia, a novel emergent aquaculture sector in the UK. This Research Council’s UK Rural Economy and Land Use project embraces technical, public health, and marketing perspectives scoping tools to assess possible impacts of the activity. Globally, aquaculture produced over 65 million tonnes of food in 2008 and will grow significantly requiring apposite global public health impact assessment tools.<p></p> Methods. Quantitative and qualitative methods incorporated data from a tridisciplinary literature. Holistic tools scoped tilapia farming impact assessments. Laboratory-based tilapia production generated data on impacts in UK and Thailand along with 11 UK focus groups involving 90 consumers, 30 interviews and site visits, 9 visits to UK tilapia growers and 2 in The Netherlands.<p></p> Results. The feasibility, challenges, strengths, and weaknesses of creating a tilapia Public Health Impact Assessment are analysed. Occupational and environmental health benefits and risks attached to tilapia production were identified.<p></p> Conclusions. Scoping public health impacts of tilapia production is possible at different levels and forms for producers, retailers, consumers, civil society and governmental bodies that may contribute to complex and interrelated public health assessments of aquaculture projects. Our assessment framework constitutes an innovatory perspective in the field

Gravitational Instability in Collisionless Cosmological Pancakes

The gravitational instability of cosmological pancakes composed of collisionless dark matter in an Einstein-de Sitter universe is investigated numerically to demonstrate that pancakes are unstable with respect to fragmentation and the formation of filaments. A ``pancake'' is defined here as the nonlinear outcome of the growth of a 1D, sinusoidal, plane-wave, adiabatic density perturbation. We have used high resolution, 2D, N-body simulations by the Particle-Mesh (PM) method to study the response of pancakes to perturbation by either symmetric (density) or antisymmetric (bending or rippling) modes, with corresponding wavevectors k_s and k_a transverse to the wavevector k_p of the unperturbed pancake plane-wave. We consider dark matter which is initially ``cold'' (i.e. with no random thermal velocity in the initial conditions). We also investigate the effect of a finite, random, isotropic, initial velocity dispersion (i.e. initial thermal velocity) on the fate of pancake collapse and instability. Pancakes are shown to be gravitationally unstable with respect to all perturbations of wavelength l<l_p (where l_p= 2pi/k_p). These results are in contradiction with the expectations of an approximate, thin-sheet energy argument.Comment: To appear in the Astrophysical Journal (1997), accepted for publication 10/10/96, single postscript file, 61 pages, 19 figure

Characterization of three types of silicon solar cells for SEPS Deep Space Mission. Volume 3: Current-voltage characteristics of spectrolab sculptured BSR/P+ (K7), BSR/P+ (K6.5) and BSR (K4.5) cells as a function of temperature and intensity

Three types of high performance silicon solar cells, sculptured BSR/P+(K7), BSR/P+(K6.5) and BSR(K4.5) manufactured by Spectrolab were evaluated for their low temperature and low intensity performance. Sixteen cells of each type were subjected to 11 temperatures and 9 intensities. The sculptured BSR/P+(K7) cells provided the greatest maximum power output both at 1 AU and at LTLI conditions. The average efficiencies of this cell were 14.4 percent at 1 SC/+25 deg C and 18.5 percent at 0.086 SC/-100 deg C

Using stochastic acceleration to place experimental limits on the charge of antihydrogen

Assuming hydrogen is charge neutral, CPT invariance demands that antihydrogen also be charge neutral. Quantum anomaly cancellation also demands that antihydrogen be charge neutral. Standard techniques based on measurements of macroscopic quantities of atoms cannot be used to measure the charge of antihydrogen. In this paper, we describe how the application of randomly oscillating electric fields to a sample of trapped antihydrogen atoms, a form of stochastic acceleration, can be used to place experimental limits on this charge

Need for timely paediatric HIV treatment within primary health care in rural South Africa

&lt;p&gt;Background: In areas where adult HIV prevalence has reached hyperendemic levels, many infants remain at risk of acquiring HIV infection. Timely access to care and treatment for HIV-infected infants and young children remains an important challenge. We explore the extent to which public sector roll-out has met the estimated need for paediatric treatment in a rural South African setting.&lt;/p&gt; &lt;p&gt;Methods: Local facility and population-based data were used to compare the number of HIV infected children accessing HAART before 2008, with estimates of those in need of treatment from a deterministic modeling approach. The impact of programmatic improvements on estimated numbers of children in need of treatment was assessed in sensitivity analyses.&lt;/p&gt; &lt;p&gt;Findings: In the primary health care programme of HIV treatment 346 children &#60;16 years of age initiated HAART by 2008; 245(70.8%) were aged 10 years or younger, and only 2(&#60;1%) under one year of age. Deterministic modeling predicted 2,561 HIV infected children aged 10 or younger to be alive within the area, of whom at least 521(20.3%) would have required immediate treatment. Were extended PMTCT uptake to reach 100% coverage, the annual number of infected infants could be reduced by 49.2%.&lt;/p&gt; &lt;p&gt;Conclusion: Despite progress in delivering decentralized HIV services to a rural sub-district in South Africa, substantial unmet need for treatment remains. In a local setting, very few children were initiated on treatment under 1 year of age and steps have now been taken to successfully improve early diagnosis and referral of infected infants.&lt;/p&gt

Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

K_s-band images of 20 barred galaxies show an increase in the peak amplitude of the normalized m=2 Fourier component with the R_25-normalized radius at this peak. This implies that longer bars have higher $m=2$ amplitudes. The long bars also correlate with an increased density in the central parts of the disks, as measured by the luminosity inside 0.25R_25 divided by the cube of this radius in kpc. Because denser galaxies evolve faster, these correlations suggest that bars grow in length and amplitude over a Hubble time with the fastest evolution occurring in the densest galaxies. All but three of the sample have early-type flat bars; there is no clear correlation between the correlated quantities and the Hubble type.Comment: ApJ Letters, 670, L97, preprint is 7 pages, 4 figure

Fundamental Discreteness Limitations of Cosmological N-Body Clustering Simulations

We explore some of the effects that discreteness and two-body scattering may have on N-body simulations with ``realistic'' cosmological initial conditions. We use an identical subset of particles from the initial conditions for a $128^3$ Particle-Mesh (PM) calculation as the initial conditions for a variety P$^3$M and Tree code runs. We investigate the effect of mass resolution (the mean interparticle separation) since most ``high resolution'' codes only have high resolution in gravitational force. The phase-insensitive two--point statistics, such as the power spectrum (autocorrelation) are somewhat affected by these variations, but phase-sensitive statistics show greater differences. Results converge at the mean interparticle separation scale of the lowest mass-resolution code. As more particles are added, but the force resolution is held constant, the P$^3$M and the Tree runs agree more and more strongly with each other and with the PM run which had the same initial conditions. This shows high particle density is necessary for correct time evolution, since many different results cannot all be correct. However, they do not so converge to a PM run which continued the fluctuations to small scales. Our results show that ignoring them is a major source of error on comoving scales of the missing wavelengths. This can be resolved by putting in a high particle density. Since the codes never agree well on scales below the mean comoving interparticle separation, we find little justification for quantitative predictions on this scale. Some measures vary by 50%, but others can be off by a factor of three or more. Our results suggest possible problems with the density of galaxy halos, formation of early generation objects such as QSO absorber clouds, etc.Comment: Revised version to be published in Astrophysical Journal. One figure changed; expanded discussion, more information on code parameters. Latex, 44 pages, including 19 figures. Higher resolution versions of Figures 10-15 available at: ftp://kusmos.phsx.ukans.edu/preprints/nbod

Utilising Visual Attention Cues for Vehicle Detection and Tracking

Advanced Driver-Assistance Systems (ADAS) have been attracting attention from many researchers. Vision-based sensors are the closest way to emulate human driver visual behavior while driving. In this paper, we explore possible ways to use visual attention (saliency) for object detection and tracking. We investigate: 1) How a visual attention map such as a \emph{subjectness} attention or saliency map and an \emph{objectness} attention map can facilitate region proposal generation in a 2-stage object detector; 2) How a visual attention map can be used for tracking multiple objects. We propose a neural network that can simultaneously detect objects as and generate objectness and subjectness maps to save computational power. We further exploit the visual attention map during tracking using a sequential Monte Carlo probability hypothesis density (PHD) filter. The experiments are conducted on KITTI and DETRAC datasets. The use of visual attention and hierarchical features has shown a considerable improvement of $\approx$8\% in object detection which effectively increased tracking performance by $\approx$4\% on KITTI dataset.Comment: Accepted in ICPR202

Bar-Halo Interaction and Bar Growth

I show that strong bars can grow in galactic discs, even when the latter are immersed in haloes whose mass within the disc radius is comparable to, or larger than, the mass of the disc. I argue that this is due to the response of the halo and in particular to the destabilising influence of the halo resonant stars. Via this instability mechanism the halo can stimulate, rather than restrain, the growth of the bar.Comment: 10 pages, 2 figures, accepted for ApJ Letter