Dual turbopump liquid hydrogen feed system experience

Design and development of dual turbopump liquid hydrogen feed syste

Couples as Partners and Parents over Children’s Early Years

We use data from the Fragile Families and Child Wellbeing Study to examine couple how couple relationship quality and parental engagement are linked over children’s early years. Our sample includes 1,630 couples that are co-resident over years 1 to 3 and 1,376 over years 3 to 5 (1,196 over both periods). Overall, we find that better relationship quality predicts greater parental engagement for both mothers and fathers—especially from children’s infant to toddler years; we find little evidence that parenting predicts future relationship quality. Married and cohabiting couples are generally similar in how relationship quality and parenting are linked. When couples are having their first birth, relationship quality is more strongly tied to parental engagement for fathers (but not mothers).Couple relationship quality, parenting, fragile families

The evolution of clustering and bias in the galaxy distribution

This paper reviews the measurements of galaxy correlations at high redshifts, and discusses how these may be understood in models of hierarchical gravitational collapse. The clustering of galaxies at redshift one is much weaker than at present, and this is consistent with the rate of growth of structure expected in an open universe. If $\Omega=1$, this observation would imply that bias increases at high redshift, in conflict with observed $M/L$ values for known high-$z$ clusters. At redshift 3, the population of Lyman-limit galaxies displays clustering which is of similar amplitude to that seen today. This is most naturally understood if the Lyman-limit population is a set of rare recently-formed objects. Knowing both the clustering and the abundance of these objects, it is possible to deduce empirically the fluctuation spectrum required on scales which cannot be measured today owing to gravitational nonlinearities. Of existing physical models for the fluctuation spectrum, the results are most closely matched by a low-density spatially flat universe. This conclusion is reinforced by an empirical analysis of CMB anisotropies, in which the present-day fluctuation spectrum is forced to have the observed form. Open models are strongly disfavoured, leaving $\Lambda$CDM as the most successful simple model for structure formation.Comment: Invited review at the Royal Society Meeting `Large-scale structure in the universe', London, March 1998. 20 Pages LaTe

Coarse-Grained Online Monitoring of BTI Aging by Reusing Power-Gating Infrastructure

In this paper, we present a novel coarse-grained technique for monitoring online the bias temperature instability (BTI) aging of circuits by exploiting their power gating infrastructure. The proposed technique relies on monitoring the discharge time of the virtual-power-network during standby operations, the value of which depends on the threshold voltage of the CMOS devices in a power-gated design (PGD). It does not require any distributed sensors, because the virtual-power-network is already distributed in a PGD. It consists of a hardware block for measuring the discharge time concurrently with normal standby operations and a processing block for estimating the BTI aging status of the PGD according to collected measurements. Through SPICE simulation, we demonstrate that the BTI aging estimation error of the proposed technique is less than 1% and 6.2% for PGDs with static operating frequency and dynamic voltage and frequency scaling, respectively. Its area cost is also found negligible. The power gating minimum idle time (MIT) cost induced by the energy consumed for monitoring the discharge time is evaluated on two scalar machine models using either x86 or ARM instruction sets. It is found less than 1.3× and 1.45× the original power gating MIT, respectively. We validate the proposed technique through accelerated aging experiments conducted with five actual chips that contain an ARM cortex M0 processor, manufactured with a 65 nm CMOS technology

Issues for the Next Generation of Galaxy Surveys

I argue that the weight of the available evidence favours the conclusions that galaxies are unbiased tracers of mass, the mean mass density (excluding a cosmological constant or its equivalent) is less than the critical Einstein-de Sitter value, and an isocurvature model for structure formation offers a viable and arguably attractive model for the early assembly of galaxies. If valid these conclusions complicate our work of adding structure formation to the standard model for cosmology, but it seems sensible to pay attention to evidence.Comment: 14 pages, 3 postscript figures, uses rspublic.st

Optical Tracer Size Differences Allow Quantitation of Active Pumping Rate Versus Stokes–Einstein Diffusion in Lymphatic Transport

Lymphatic uptake of interstitially administered agents occurs by passive convective–diffusive inflow driven by interstitial concentration and pressure, while the downstream lymphatic transport is facilitated by active propulsive contractions of lymphatic vessel walls. Near-infrared fluorescence imaging in mice was used to measure these central components of lymphatic transport for the first time, using two different-sized molecules––methylene blue (MB) and fluorescence-labeled antibody immunoglobulin G (IgG)-IRDye 680RD. This work confirms the hypothesis that lymphatic passive inflow and active propulsion rates can be separated based upon the relative differences in Stokes–Einstein diffusion coefficient. This coefficient specifically affects the passive-diffusive uptake when the interstitial volume and pressure are constant. Parameters such as mean time-to-peak signal, overall fluorescence signal intensities, and number of active peristaltic pulses, were estimated from temporal imaging data. While the mean time to attain peak signal representative of diffusion-dominated flow in the lymph vessels was 0.6±0.2  min for MB and 8±6  min for IgG, showing a size dependence, the active propulsion rates were 3.4±0.8  pulses/min and 3.3±0.5  pulses/min, respectively, appearing size independent. The propulsion rates for both dyes decreased with clearance from the interstitial injection-site, indicating intrinsic control of the smooth muscles in response to interstitial pressure. This approach to size-comparative agent flow imaging of lymphatic function can enable noninvasive characterization of diseases related to uptake and flow in lymph networks

The velocity peaks in the cold dark matter spectrum on Earth

The cold dark matter spectrum on earth is expected to have peaks in velocity space. We obtain estimates for the sizes and locations of these peaks. To this end we have generalized the secondary infall model of galactic halo formation to include angular momentum of the dark matter particles. This new model is still spherically symmetric and it has self-similar solutions. Our results are relevant to direct dark matter search experiments.Comment: 12 pages including 1 table and 4 figures, LaTeX, REVTEX 3.0 versio