System dynamics and simulation of LSS

Large Space Structures have many unique problems arising from mission objectives and the resulting configuration. Inherent in these configurations is a strong coupling among several of the designing disciplines. In particular, the coupling between structural dynamics and control is a key design consideration. The solution to these interactive problems requires efficient and accurate analysis, simulation and test techniques, and properly planned and conducted design trade studies. The discussion presented deals with these subjects and concludes with a brief look at some NASA capabilities which can support these technology studies

An Experimental Approach to Comparing Trust in Pastoral and Non-Pastoral Australia

It is generally held that rural Australians are more cooperative in character than their urban counterparts. To explore one aspect of this notion, we conducted an experiment which compared trust and trustworthiness among a sample of Australian senior high school students which included students with both pastoral and non-pastoral backgrounds. While student behaviour is unlikely to mimic adult behaviour, any significant differences between pastoral and non-pastoral students would suggest differences do exist between the social norms that guide pastoral and non-pastoral communities. We repeated our experiment at three different schools containing students from both pastoral and non-pastoral backgrounds, allowing us to draw comparisons. In total 78 students participated. Our experiments were based on similar experiments that have been applied across a range of contexts internationally (trust game/investment game). We did not find evidence of differences between students with pastoral and non-pastoral backgrounds, either in the level of trust in others or in trustworthiness, though our methods probably have a bias towards this conclusion. Our results concurred with other studies in showing that social distance is an important determinant of the level of cooperation.rural urban relations, economic behaviour, culture, arid zones, semiarid zones, pastoral society

Analysis of β-globin chromatin micro-environment using a novel 3C variant, 4Cv

Copyright: © 2010 Pink et al.Higher order chromatin folding is critical to a number of developmental processes, including the regulation of gene expression. Recently developed biochemical techniques such as RNA TRAP and chromosome conformation capture (3C) have provided us with the tools to probe chromosomal structures. These techniques have been applied to the β-globin locus, revealing a complex pattern of interactions with regions along the chromosome that the gene resides on. However, biochemical and microscopy data on the nature of β-globin interactions with other chromosomes is contradictory. Therefore we developed a novel 4C variant, Complete-genome 3C by vectorette amplification (4Cv), which allows an unbiased and quantitative method to examine chromosomal structure. We have used 4Cv to study the microenvironment of the β-globin locus in mice and show that a significant proportion of the interactions of β-globin are inter-chromosomal. Furthermore, our data show that in the liver, where the gene is active, β-globin is more likely to interact with other chromosomes, compared to the brain where the gene is silent and is more likely to interact with other regions along the same chromosome. Our data suggest that transcriptional activation of the β-globin locus leads to a change in nuclear position relative to the chromosome territory.Ryan Pink is supported by a grant from Action Medical Research; Daniel Caley is supported by a grant from The Dunhill Medical Trust; David Carter is supported by a grant from the British Society for Haematology

Using LaX scintillator in a new low-background Compton telescope

The ability of Compton telescopes to perform imaging and spectroscopy in space depends directly on the speed and energy resolution of the calorimeter detectors in the telescope. The calorimeter detectors flown on space-borne or balloon-borne Compton telescopes have included NaI(Tl), CsI(Na), HPGe and liquid organic scintillator. By employing LaX scintillators for the calorimeter, one can take advantage of the unique speed and resolving power of the material to improve the instrument sensitivity and simultaneously enhance its spectroscopic performance and thus its imaging performance. We present a concept for a space-borne Compton telescope that employs LaX as a calorimeter and estimate the improvement in sensitivity over past realizations of Compton telescopes. With some preliminary laboratory measurements, we estimate that in key energy bands, typically corrupted with neutron-induced internal nuclear emissions, this design enjoys a twenty-fold improvement in background rejection

Lipid-modulated assembly of magnetized iron-filled carbon nanotubes in millimeter-scale structures

Biomolecule-functionalized carbon nanotubes (CNTs) combine the molecular recognition properties of biomaterials with the electrical properties of nanoscale solid state transducers. Application of this hybrid material in bioelectronic devices requires the development of methods for the reproducible self-assembly of CNTs into higher-order structures in an aqueous environment. To this end, we have studied pattern formation of lipid-coated Fe-filled CNTs, with lengths in the 1–5 µm range, by controlled evaporation of aqueous CNT-lipid suspensions. Novel diffusion limited aggregation structures composed of end-to-end oriented nanotubes were observed by optical and atomic force microscopy. Significantly, the lateral dimension of assemblies of magnetized Fe-filled CNTs was in the millimeter range. Control experiments in the absence of lipids and without magnetization indicated that the formation of these long linear nanotube patterns is driven by a subtle interplay between radial flow forces in the evaporating droplet, lipid-modulated van der Waals forces, and magnetic dipole–dipole interactions. Keywords

Gas micro-well track imaging detectors for gamma-ray astronomy

We describe our program to develop gas micro-well detectors (MWDs) as three-dimensional charged particle trackers for use in advanced gamma-ray telescope concepts. A micro-well detector consists of an array of individual micro-patterned gas proportional counters opposite a planar drift electrode. The well anodes and cathodes may be connected in X and Y strips, respectively, to provide two-dimensional imaging. When combined with transient digitizer electronics, which record the time signature of the charge collected in the wells of each strip, full three-dimensional reconstruction of charged-particle tracks in large gas volumes is possible. Such detectors hold great promise for advanced Compton telescope (ACT) and advanced pair telescope (APT) concepts due to the very precise measurement of charged particle momenta that is possible (Compton recoil electrons and electron-positron pairs, respectively). We present preliminary lab results, including detector fabrication, prototype electronics, and initial detector testing. We also discuss applications to the ACT and APT mission concepts, based on GEANT3 and GEANT4 simulations

Quasi-Periodic Pulsations during the Impulsive and Decay phases of an X-class Flare

Quasi-periodic pulsations (QPP) are often observed in X-ray emission from solar flares. To date, it is unclear what their physical origins are. Here, we present a multi-instrument investigation of the nature of QPP during the impulsive and decay phases of the X1.0 flare of 28 October 2013. We focus on the character of the fine structure pulsations evident in the soft X-ray time derivatives and compare this variability with structure across multiple wavelengths including hard X-ray and microwave emission. We find that during the impulsive phase of the flare, high correlations between pulsations in the thermal and non-thermal emissions are seen. A characteristic timescale of ~20s is observed in all channels and a second timescale of ~55s is observed in the non-thermal emissions. Soft X-ray pulsations are seen to persist into the decay phase of this flare, up to 20 minutes after the non-thermal emission has ceased. We find that these decay phase thermal pulsations have very small amplitude and show an increase in characteristic timescale from ~40s up to ~70s. We interpret the bursty nature of the co-existing multi-wavelength QPP during the impulsive phase in terms of episodic particle acceleration and plasma heating. The persistent thermal decay phase QPP are most likely connected with compressive MHD processes in the post-flare loops such as the fast sausage mode or the vertical kink mode.Comment: 7 pages, 4 figures, 1 tabl

Position Resolution in LaBr3 and LaCl3 Scintillators Using Position-Sensitive Photomultiplier Tubes

Advanced scintillator materials such as LaBr3:Ce and LaCl3:Ce hold great promise for future hard X-ray and gamma-ray astrophysics missions due to their high density, high light output, good linearity, and fast decay times. Of particular importance for future space-based imaging instruments, such as coded-aperture telescopes, is the precise spatial location of individual gamma-ray interactions. We have investigated the position and energy resolution achievable within monolithic (5 cm × 5 cm × 1 cm) LaBr3:Ce and LaCl3:Ce crystals using position-sensitive light readout devices, including a position-sensitive photomultiplier tube and a multi-anode photomultiplier tube. We present the results of these tests and discuss the applicability of such advanced scintillators to future high-energy imaging astrophysics missions

Estimasi Bangkitan Perjalanan Penduduk Perumahan Di Kelurahan Dadok Tunggul Hitam Kota Padang

Transportation problems appear as a result of the rapid population growth rate, creating housing areas and community activities, which generate trips. This study aims to determine the trip generated by the residential areas in the Village of Dadok Tunggul Hitam consisting Green Arya, Rumah Idaman Wisma Lestari, Perumdam, Permata Dadok, and Trisandi Indah settlements. These residential areas change the land function that would later cause problems. The community activities generate trips toward the city center. The secondary data were collected from the government agencies and the primary data were collected through direct Surveys. Variables used in this study are the size of the household, car ownership, income level, and the number of working family members. The data were then analyzed using descriptive techniques and linier regression method. The results show the number of trips produced each day and factors that influence the trips generated