Advanced tracking systems design and analysis

The results of an assessment of several types of high-accuracy tracking systems proposed to track the spacecraft in the National Aeronautics and Space Administration (NASA) Advanced Tracking and Data Relay Satellite System (ATDRSS) are summarized. Tracking systems based on the use of interferometry and ranging are investigated. For each system, the top-level system design and operations concept are provided. A comparative system assessment is presented in terms of orbit determination performance, ATDRSS impacts, life-cycle cost, and technological risk

The genetic control of avascular area in mouse oxygen-induced retinopathy

Purpose: The C57BL/6ByJ and BALB/cByJ inbred strains of mice are, respectively, susceptible and resistant to oxygen-induced retinopathy (OIR). The purpose of this work was to investigate the genetic control of the retinal avascular area in mouse OIR using a mapping cross. Methods: The central retinal avascular area was measured on postnatal day 16 (P16) in C57BL/6ByJ, BALB/cByJ, 101 (C57BL/6ByJ x BALB/cByJ)F2, and 116 (BALB/cByJ x C57BL/6ByJ)F2 mice that had been subjected to the OIR protocol. A genome-wide scan was performed of selected albino and non-albino mice to determine quantitative trait loci associated with weight and avascular area. Results: C57BL/6ByJ mice had significantly larger avascular areas than BALB/cByJ ones. Albino mice of the F2 generation had smaller avascular areas than the non-albino mice. Genotyping was performed at 856 informative single nucleotide polymorphisms approximately evenly distributed across the genome from each of 85 selected F2 mice. Weight, sex, and the paternal grandmother were found to act as additive covariates associated with the avascular area on P16; mapping analyses that used a model incorporating these covariates found a quantitative trait locus on chromosome 7 related to avascular area. Mapping analyses that used a model that did not incorporate covariates found a quantitative trait locus on chromosome 9 related to avascular area. A quantitative trait locus for bodyweight on P16 was mapped to chromosome 5. Conclusions: The retinal avascular area in the mouse OIR model is under genetic control. Revascularization in OIR is related to the weight, strain of paternal grandmother, sex, and albinism. Our data support the existence of a quantitative trait locus on chromosome 5 that influences weight after exposure to hyperoxia, as well as quantitative trait loci on chromosomes 7 and 9 that modify susceptibility to OIR

Manifestation of incompatibility of marine residual fuels: a method for determining compatibility, studying composition of fuels and sediment

The results of studying the problem of active sediment formation when mixing residual fuels, caused by manifestation of incompatibility, are presented. A laboratory method has been developed for determining the compatibility and stability of fuels allowing identification of a quantitative characteristic of sediment formation activity. Laboratory studies were performed, and incompatible fuel components were identified. Tests were made to determine the quality indicators of samples and group individual composition of fuels. Results on the content of total and inorganic carbon in the obtained sediments were determined using Shimadzu TOC-V SSM 5000A. Chemical composition was determined and calculated on LECO CHN-628 analyser. Group composition of hydrocarbon fuels contained in the sediment was studied by gas chromato-mass spectrometry on GCMS-QP2010 Ultra Shimadzu. To obtain additional information on the structural group composition of fuel sediment, IR spectrometry was performed on IR-Fourier spectrometer IRAffinity-1. X-ray diffraction analysis of sediment samples was made using X-ray diffractometer XRD-7000 Shimadzu; interplanar distances d002 and d100 as well as Lс and Lа crystallite sizes served as the evaluation criteria. Microstructural analysis of total sediment was performed by scanning electron microscopy. The results of the research confirmed that the content of normal alkanes in the fuel mixture mainly affects sediment formation. Recommendations were drawn on preserving the quality of fuels and reducing sediment formation during storage and transportation

Radiation Specifications for Fission Power Conversion Component Materials

NASA has been supporting design studies and technology development that could provide power to an outpost on the moon, Mars, or an asteroid. One power-generation system that is independent of sunlight or power-storage limitations is a fission-based power plant. There is a wealth of terrestrial system heritage that can be transferred to the design and fabrication of a fission power system for space missions, but there are certain design aspects that require qualification. The radiation tolerance of the power conversion system requires scrutiny because the compact nature of a space power plant restricts the dose reduction methodologies compared to those used in terrestrial systems. An integrated research program has been conducted to establish the radiation tolerance of power conversion system-component materials. The radiation limit specifications proposed for a Fission Power System power convertor is 10 Mrad ionizing dose and 5 x 10(exp 14) neutron per square centimeter fluence for a convertor operating at 150 C. Specific component materials and their radiation tolerances are discussed. This assessment is for the power convertor hardware; electronic components are not covered here

Why are we not flooded by involuntary thoughts about the past and future? Testing the cognitive inhibition dependency hypothesis

© The Author(s) 2018In everyday life, involuntary thoughts about future plans and events occur as often as involuntary thoughts about the past. However, compared to involuntary autobiographical memories (IAMs), such episodic involuntary future thoughts (IFTs) have become a focus of study only recently. The aim of the present investigation was to examine why we are not constantly flooded by IFTs and IAMs given that they are often triggered by incidental cues while performing undemanding activities. One possibility is that activated thoughts are suppressed by the inhibitory control mechanism, and therefore depleting inhibitory control should enhance the frequency of both IFTs and IAMs. We report an experiment with a between-subjects design, in which participants in the depleted inhibition condition performed a 60-min high-conflict Stroop task before completing a laboratory vigilance task measuring the frequency of IFTs and IAMs. Participants in the intact inhibition condition performed a version of the Stroop task that did not deplete inhibitory control. To control for physical and mental fatigue resulting from performing the 60-min Stroop tasks in experimental conditions, participants in the control condition completed only the vigilance task. Contrary to predictions, the number of IFTs and IAMs reported during the vigilance task, using the probe-caught method, did not differ across conditions. However, manipulation checks showed that participants’ inhibitory resources were reduced in the depleted inhibition condition, and participants were more tired in the experimental than in the control conditions. These initial findings suggest that neither inhibitory control nor physical and mental fatigue affect the frequency of IFTs and IAMs.Peer reviewedFinal Published versio

Correlation between magnetic and crystal structural sublattices in palladium-doped FeRh alloys: Analysis of the metamagnetic phase transition driving forces

FeRh alloys doped with the third element exhibit a change in the lattice and magnetic subsystems, which are manifested in antiferromagnetic- ferromagnetic (AFM-FM) first-order phase transition temperature, the shrinkage of the temperate hysteresis under transition, and the reduction of the saturation magnetization. All aforementioned parameters are crucial for practical applications. To control them it is quite important to determine the driving forces of the metamagnetic transition and its origins. In this manuscript ab initio calculations and experimental studies results are presented, which demonstrate the correlation between the structural and magnetic properties of the Fe50Rh50−xPdx alloys. The qualitative analysis of the metamagnetic phase transition driving forces in palladium-doped FeRh alloys was performed to determine their contribution to the evolution of magnetic and lattice subsystems. In addition, the impact of the impurities phases together with its magnetic behavior on the AFM-FM phase transition was considered.Fil: Komlev, Aleksei S.. Lomonosov Moscow State University; RusiaFil: Karpenkov, Dmitriy Y.. National University of Science and Technology; Rusia. Lomonosov Moscow State University; RusiaFil: Gimaev, Radel R.. Lomonosov Moscow State University; RusiaFil: Chirkova, Alisa. Institute for Materials Science; AlemaniaFil: Akiyama, Ayaka. Hirosaki University; JapónFil: Miyanaga, Takafumi. Hirosaki University; JapónFil: Hupalo, Marcio Ferreira. Universidade Estadual do Ponta Grossa; BrasilFil: Aguiar, D.J.M.. Universidade Federal do Paraná; BrasilFil: Carvalho, Alexandre Magnus G.. Universidade Estadual de Maringá; Brasil. Universidade Federal de Sao Paulo; BrasilFil: Jiménez, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Cabeza, Gabriela Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Zverev, Vladimir I.. Lomonosov Moscow State University; RusiaFil: Perov, Nikolai S.. Lomonosov Moscow State University; Rusi

Polarised Quark Distributions in the Nucleon from Semi-Inclusive Spin Asymmetries

We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range $0.003$1 GeV$^2$. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at $Q^2$=10 GeV$^2$. The polarised $u$ valence quark distribution, $\Delta u_v(x)$, is positive and the polarisation increases with $x$. The polarised $d$ valence quark distribution, $\Delta d_v(x)$, is negative and the non-strange sea distribution, $\Delta \bar q(x)$, is consistent with zero over the measured range of $x$. We find for the first moments $\int_0^1 \Delta u_v(x) dx = 0.77 \pm 0.10 \pm 0.08$, $\int_0^1 \Delta d_v(x) dx = -0.52 \pm 0.14 \pm 0.09$ and $\int_0^1 \Delta \bar q(x) dx= 0.01 \pm 0.04 \pm 0.03$, where we assumed $\Delta \bar u(x) = \Delta \bar d(x)$. We also determine for the first time the second moments of the valence distributions $\int_0^1 x \Delta q_v(x) dx$.Comment: 17 page

New Constraints (and Motivations) for Abelian Gauge Bosons in the MeV-TeV Mass Range

We survey the phenomenological constraints on abelian gauge bosons having masses in the MeV to multi-GeV mass range (using precision electroweak measurements, neutrino-electron and neutrino-nucleon scattering, electron and muon anomalous magnetic moments, upsilon decay, beam dump experiments, atomic parity violation, low-energy neutron scattering and primordial nucleosynthesis). We compute their implications for the three parameters that in general describe the low-energy properties of such bosons: their mass and their two possible types of dimensionless couplings (direct couplings to ordinary fermions and kinetic mixing with Standard Model hypercharge). We argue that gauge bosons with very small couplings to ordinary fermions in this mass range are natural in string compactifications and are likely to be generic in theories for which the gravity scale is systematically smaller than the Planck mass - such as in extra-dimensional models - because of the necessity to suppress proton decay. Furthermore, because its couplings are weak, in the low-energy theory relevant to experiments at and below TeV scales the charge gauged by the new boson can appear to be broken, both by classical effects and by anomalies. In particular, if the new gauge charge appears to be anomalous, anomaly cancellation does not also require the introduction of new light fermions in the low-energy theory. Furthermore, the charge can appear to be conserved in the low-energy theory, despite the corresponding gauge boson having a mass. Our results reduce to those of other authors in the special cases where there is no kinetic mixing or there is no direct coupling to ordinary fermions, such as for recently proposed dark-matter scenarios.Comment: 49 pages + appendix, 21 figures. This is the final version which appears in JHE

Measurements of Transverse Energy Flow in Deep-Inelastic Scattering at HERA

Measurements of transverse energy flow are presented for neutral current deep-inelastic scattering events produced in positron-proton collisions at HERA. The kinematic range covers squared momentum transfers Q^2 from 3.2 to 2,200 GeV^2, the Bjorken scaling variable x from 8.10^{-5} to 0.11 and the hadronic mass W from 66 to 233 GeV. The transverse energy flow is measured in the hadronic centre of mass frame and is studied as a function of Q^2, x, W and pseudorapidity. A comparison is made with QCD based models. The behaviour of the mean transverse energy in the central pseudorapidity region and an interval corresponding to the photon fragmentation region are analysed as a function of Q^2 and W.Comment: 26 pages, 8 figures, submitted to Eur. Phys.