A study to determine which of the selected indices were utilized by head nurses in planning for patient care and staff development

Thesis (M.S.)--Boston University, 1959

Spin-axis attitude estimation and magnetometer bias determination for the AMPTE mission

Algorithms were developed for magnetometer biases and spin axis attitude calculation. Numerical examples of the performance of the algorithm are given

Trapped Ar isotopes in meteorite ALH 84001 indicate Mars did not have a thick ancient atmosphere

Water is not currently stable in liquid form on the martian surface due to the present mean atmospheric pressure of ∼7 mbar and mean global temperature of ∼220 K. However, geomorphic features and hydrated mineral assemblages suggest that Mars’ climate was once warmer and liquid water flowed on the surface. These observations may indicate a substantially more massive atmosphere in the past, but there have been few observational constraints on paleoatmospheric pressures. Here we show how the [superscript 40]Ar/[superscript 36]Ar ratios of trapped gases within martian meteorite ALH 84001 constrain paleoatmospheric pressure on Mars during the Noachian era [∼4.56–3.8 billion years (Ga)]. Our model indicates that atmospheric pressures did not exceed ∼1.5 bar during the first 400 million years (Ma) of the Noachian era, and were <400 mbar by 4.16 Ga. Such pressures of CO[subscript 2] are only sufficient to stabilize liquid water on Mars’ surface at low latitudes during seasonally warm periods. Other greenhouse gases like SO[superscript 2] and water vapor may have played an important role in intermittently stabilizing liquid water at higher latitudes following major volcanic eruptions or impact events.United States. National Aeronautics and Space Administration. Mars Fundamental Research Program (Grant MFRP05-0108)Ann and Gordon Getty Foundatio

A chiral crystal in cold QCD matter at intermediate densities?

The analogue of Overhauser (particle-hole) pairing in electronic systems (spin-density waves with non-zero total momentum $Q$) is analyzed in finite-density QCD for 3 colors and 2 flavors, and compared to the color-superconducting BCS ground state (particle-particle pairing, $Q$=0). The calculations are based on effective nonperturbative four-fermion interactions acting in both the scalar diquark as well as the scalar-isoscalar quark-hole ('$\sigma$') channel. Within the Nambu-Gorkov formalism we set up the coupled channel problem including multiple chiral density wave formation, and evaluate the resulting gaps and free energies. Employing medium-modified instanton-induced 't Hooft interactions, as applicable around $\mu_q\simeq 0.4$ GeV (or 4 times nuclear saturation density), we find the 'chiral crystal phase' to be competitive with the color superconductor.Comment: 14 pages ReVTeX, including 11 ps-/eps-figure

An infrared study of modern and paleo-filamentous bacteria from Rio Tinto, Spain

The Rio Tinto River Basin in southwestern Spain is a natural acidic (pH ~2.3) drainage system that supports a diversity of acid tolerant bacteria and eukaryotes with iron and sulfur- oxidizing prokaryotes performing chemolithotrophy and supporting anaerobic respiration [1, 2]. River terrace deposits formed over the past 2 Myr have preserved remnants of this unique biosphere, particularly microbial filaments, which provide templates for iron sulphate and iron oxide precipitation [1, 2]. This process of permineralization causes organic material to become trapped within a mineral matrix and preserved over geological time. This study analysed cultured filamentous bacteria, modern biofilms and sediments, and river terrace deposits spanning 2.1 Myr to assess the preservation of organics in this extreme environment over time, and the ability to correlate them with a contemporary culture. Filamentous bacteria are preserved within optically translucent nanophase to crystalline jarosite and goethite within all samples. The cultures contained 1 μm diameter filaments, some partially encrusted with iron oxides with visible cell walls, and others completely free of iron oxides, that are morphologically comparable to those preserved in the Rio Tinto rock record. Organic compounds (e.g. aliphatic hydrocarbons, amides and carboxylic acids) were detected at various levels within the culture and river terraces using mid-IR spectroscopy. Rio Tinto is a natural laboratory allowing living cells to be studied and correlated to morphological and biomolecular fossils in the geological record. These deposits will provide predictive tools for biomarker studies that may be extended to analogous environments on ancient Earth or even Mars. [1] Fernández-Remolar et al. (2005) Earth Planet Sci Lett 240,149-167. [2] Fernández-Remolar & Knoll (2008) Icarus 194,72-85

Attitude and Phase Synchronization of Formation Flying Spacecraft: Lagrangian Approach

This article presents a unified synchronization framework with application to precision formation flying spacecraft. Central to the proposed innovation, in applying synchroniza- tion to both translational and rotational dynamics in the Lagrangian form, is the use of the distributed stability and performance analysis tool, called contraction analysis that yields exact nonlinear stability proofs. The proposed decentralized tracking control law synchronizes the attitude of an arbitrary number of spacecraft into a common time-varying trajectory with global exponential convergence. Moreover, a decentralized translational tracking control law based on phase synchronization is presented, thus enabling coupled translational and rotational maneuvers. While the translational dynamics can be adequately controlled by linear control laws, the proposed method permits highly nonlinear systems with nonlinearly coupled inertia matrices such as the attitude dynamics of space-craft whose large and rapid slew maneuvers justify the nonlinear control approach. The proposed method integrates both the trajectory tracking and synchronization problems in a single control framework