The Puzzle of the Flyby Anomaly

Close planetary flybys are frequently employed as a technique to place spacecraft on extreme solar system trajectories that would otherwise require much larger booster vehicles or may not even be feasible when relying solely on chemical propulsion. The theoretical description of the flybys, referred to as gravity assists, is well established. However, there seems to be a lack of understanding of the physical processes occurring during these dynamical events. Radio-metric tracking data received from a number of spacecraft that experienced an Earth gravity assist indicate the presence of an unexpected energy change that happened during the flyby and cannot be explained by the standard methods of modern astrodynamics. This puzzling behavior of several spacecraft has become known as the flyby anomaly. We present the summary of the recent anomalous observations and discuss possible ways to resolve this puzzle.Comment: 6 pages, 1 figure. Accepted for publication by Space Science Review

Neural network method for inverse modeling of material deformation

A method is described for inverse modeling of material deformation in applications of importance to the sheet metal forming industry. The method was developed in order to assess the feasibility of utilizing empirical data in the early stages of the design process as an alternative to conventional prototyping methods. Because properly prepared and employed artificial neural networks (ANN) were known to be capable of codifying and generalizing large bodies of empirical data, they were the natural choice for the application. The product of the work described here is a desktop ANN system that can produce in one pass an accurate die design for a user-specified part shape

Neural network-based resistance spot welding control and quality prediction

This paper describes the development and evaluation of neural network-based systems for industrial resistance spot welding process control and weld quality assessment. The developed systems utilize recurrent neural networks for process control and both recurrent networks and static networks for quality prediction. The first section describes a system capable of both welding process control and real-time weld quality assessment, The second describes the development and evaluation of a static neural network-based weld quality assessment system that relied on experimental design to limit the influence of environmental variability. Relevant data analysis methods are also discussed. The weld classifier resulting from the analysis successfldly balances predictive power and simplicity of interpretation. The results presented for both systems demonstrate clearly that neural networks can be employed to address two significant problems common to the resistance spot welding industry, control of the process itself, and non-destructive determination of resulting weld quality

Dependence of the Superconducting Transition Temperature of MgB2 on Pressure to 20 GPa

The dependence of Tc on nearly hydrostatic pressure has been measured for an isotopically pure (11B) MgB2 sample in a helium-loaded diamond-anvil-cell to nearly 20 GPa. Tc decreases monotonically with pressure from 39.1 K at ambient pressure to 20.9 K at 19.2 GPa. The initial dependence is the same as that obtained earlier (dTc/dP = -1.11(2) K/GPa) on the same sample in a He-gas apparatus to 0.7 GPa. The observed pressure dependence Tc(P) to 20 GPa can be readily described in terms of simple lattice stiffening within standard phonon-mediated BCS superconductivity.Comment: 9 pages, 3 figure

Suicide Following Traumatic Brain Injury: Pathogenesis and Neurocognitive Mechanisms

Traumatic brain injury (TBI) is associated with varied neuropsychiatric sequelae, including elevated risk for later suicidal behaviors (SBs). This chapter provides a qualitative narrative review of hypothesized biological and neurocognitive mechanisms linking TBI to subsequent SBs. The following selective review specifically highlights: (1) Structural and functional alterations to neural circuitry secondary to common head injuries (e.g., concussions or mild TBI) as well as severe or repetitive TBI (e.g., chronic traumatic encephalopathy); (2) Overlap between post-TBI neuropsychological deficits and proposed bio-behavioral indicators of suicide risk; and (3) Potential neurocognitive mediators of the relationship between TBI and SBs, with a particular focus on executive functions involved in self-regulation (i.e., cognitive and affective inhibitory control) and their neural substrates, e.g., corticolimbic, frontostriatal, and frontoparietal circuitry. The chapter concludes with theoretical and practical implications of this shared pathophysiology, based on the reviewed empirical literature

Phylogeography, population structure and evolution of coral-eating butterflyfishes (Family Chaetodontidae, genus Chaetodon, subgenus Corallochaetodon)

Aim: This study compares the phylogeography, population structure and evolution of four butterflyfish species in the Chaetodon subgenus Corallochaetodon, with two widespread species (Indian Ocean – C. trifasciatus and Pacific Ocean – C. lunulatus), and two species that are largely restricted to the Red Sea (C. austriacus) and north-western (NW) Indian Ocean (C. melapterus). Through extensive geographical coverage of these taxa, we seek to resolve patterns of genetic diversity within and between closely related butterflyfish species in order to illuminate biogeographical and evolutionary processes. Location: Red Sea, Indian Ocean and Pacific Ocean. Methods: A total of 632 individuals from 24 locations throughout the geographical ranges of all four members of the subgenus Corallochaetodon were sequenced using a 605 bp fragment (cytochrome b) of mtDNA. In addition, 10 microsatellite loci were used to assess population structure in the two widespread species. Results: Phylogenetic reconstruction indicates that the Pacific Ocean C. lunulatus diverged from the Indian Ocean C. trifasciatus approximately 3 Ma, while C. melapterus and C. austriacus comprise a cluster of shared haplotypes derived from C. trifasciatus within the last 0.75 Myr. The Pacific C. lunulatus had significant population structure at peripheral locations on the eastern edge of its range (French Polynesia, Johnston Atoll, Hawai'i), and a strong break between two ecoregions of the Hawaiian Archipelago. The Indian Ocean C. trifasciatus showed significant structure only at the Chagos Archipelago in the central Indian Ocean, and the two range-restricted species showed no population structure but evidence of recent population expansion. Main conclusions: Patterns of endemism and genetic diversity in Corallochaetodon butterflyfishes have been shaped by (1) Plio-Pleistocene sea level changes that facilitated evolutionary divergences at biogeographical barriers between Indian and Pacific Oceans, and the Indian Ocean and Red Sea, and (2) semi-permeable oceanographic and ecological barriers working on a shorter time-scale. The evolution of range-restricted species (Red Sea and NW Indian Ocean) and isolated populations (Hawai'i) at peripheral biogeographical provinces indicates that these areas are evolutionary incubators for reef fishes

ARPES Study of X-Point Band Overlaps in LaB6_6 and SmB6_6 - Contrast to SrB6_6 and EuB6_6

In contrast to our recent finding of an X-point band gap in divalent hexaborides, we report here that angle resolved photoemission spectroscopy (ARPES) data shows that the gap is absent for trivalent LaB$_6$ and is absent or nearly so for mixed valent SmB$_6$. This finding demonstrates a nontrivial evolution of the band structure from divalent to trivalent hexaborides.Comment: submitted to SCES '0

Consumption Behavior of Economics Education Students Faculty of Economics, State University of Manado

This study aims to determine the influence of financial literacy and social environmental factors on consumption behaviour of Economics Faculty of Economics students of Manado State University. The design of this study using the quantitative approach with survey method, with the number of samples is 67 students as respondents through proportionate stratified random sampling. The research instrument used questionnaire with a Likert scale which then tested the validity and reliability. Data analysis techniques include 1) Descriptive analysis; 2) Classical assumption test, and 3) Multiple linear regression analysis. The results showed: 1). There is a significant influence on financial literacy and student consumption behaviour, with the influence of financial literacy on student consumption behaviour of 54.4%; 2). There is a significant influence on social environment factor with student consumption behaviour, with the influence of social environment factor to student consumption behaviour equal to 37.5%; and 3). There is the influence of variable of financial literacy and social environment factor to student consumption behaviour variable with a contribution equal to 78.6%. Conclusion, partially or simultaneously financial literacy and social environmental factors have a significant effect on the consumption behaviour of students of Economics Education Faculty of Economics, State University of Manado

Abundance and evolution of galaxy clusters in cosmological models with massive neutrino

The time evolution of the number density of galaxy clusters and their mass and temperature functions are used to constrain cosmological parameters in the spatially flat dark matter models containing a fraction of hot particles (massive neutrino) additional to cold and baryonic matter. We test the modified MDM models with cosmic gravitational waves and show that they neither pass the cluster evolution test nor reproduce the observed height of the first acoustic peak in $\Delta T/T$ spectrum, and therefore should be ruled out. The models with a non-zero cosmological constant are in better agreement with observations. We estimate the free cosmological parameters in $\Lambda$MDM with a negligible abundance of gravitational waves, and find that within the parameter ranges $h\in (0.6, 0.7)$, $n\in (0.9, 1.1)$, (i) the value of $\Omega_\Lambda$ is strongly affected by a small fraction of hot dark matter, $f_\nu\equiv\Omega_\nu /\Omega_m\in (0, 0.2)$: $0.45 <\Omega_\Lambda <0.7$ ($1\sigma$ CL), and (ii) the redshift evolution of galaxy clusters alone reveals the following explicit correlation between $\Omega_\Lambda$ and $f_\nu$: $\Omega_\Lambda +0.5f_\nu =0.65\pm 0.1$. The present accuracy of observational data allows only to bound the fraction of hot matter, $f_\nu\in (0, 0.2)$ (the number of massive neutrino species remains undelimited, $N_\nu =1, 2, 3$).Comment: 9 pages, 7 figures, submitted in A&