Cryogenic propellant management: Integration of design, performance and operational requirements

The integration of the design features of the Shuttle elements into a cryogenic propellant management system is described. The implementation and verification of the design/operational changes resulting from design deficiencies and/or element incompatibilities encountered subsequent to the critical design reviews are emphasized. Major topics include: subsystem designs to provide liquid oxygen (LO2) tank pressure stabilization, LO2 facility vent for ice prevention, liquid hydrogen (LH2) feedline high point bleed, pogo suppression on the Space Shuttle Main Engine (SSME), LO2 low level cutoff, Orbiter/engine propellant dump, and LO2 main feedline helium injection for geyser prevention

Assessing the Effectiveness of Corn Rootworm Control and Areawide Management of Corn Rootworms

Corn rootworm populations have been high the last couple of seasons. The higher density of the pest generates questions concerning the effectiveness of corn rootworm controls that have been used, especially insecticides. Corn rootworm infestations, and their injury, tend to be variable (spotty) across a field of corn. If more then a node of roots has been destroyed and there is a wind, the corn is likely to be lodged. The lodging provides a visual manifestation of the corn rootworm larval feeding. Because the infestations are not uniform across a field, the lodging is also variable. If one were to want to obtain the worst possible root-injury rating for the field, they would select lodged plants to dig and rate. If one wanted to produce a lower rating, say if they were responsible for the product applied to control the rootworm, they could choose plants that were not lodged. Therefore the rating of corn rootworm larval injury to corn can be biased by selectively sampling plants based on the above ground appearance, lodged or not lodged. To be fair to growers AND the vendor of a rootworm control product, an unbiased sampling program should be used

The Effectiveness of Monetary Policy Towards Stock Index Case Study : Jakarta Islamic Index 2006-2014

Fluctuation in economy situation is an important indicator for investor decision making. The investor actions are base on the minimum risk while having maximum profit. One of it is observing the condition of macro variables within monetary policy. This research aims to analyze the impact of inflation, money supply, exchange rate, and birate towards stock of Jakarta islamic Index. The type data used is times series periode 2006-2014. Multiple linier regression with chow test and dummy variable approach to compare and to know the behavior of each independent variables. The result shows partially that birate and exchange rate negatively impact Jakarta Islamic Index before global monetary crisis in 2008, while inflation and money supply not that significantly impact. After global monetary crisis in 2008, partially, birate variable and money supply significantly giving positive influence to Jakarta Islamic Index, while at same time exchange rate and inflation are not significantly influencial. Simultaneously, inflation, money supply, exchange rate, and birate influence Jakarta islamic Index

Analisis Determinan Kinerja Bank Pembiayaan Rakyat Syariah di Indonesia (Pendekatan Direct Error Correction Model)

Islamic banking is emerging as a breakthrough and an alternative to conventional banking. The shariah-compliant financial services industry is currently at a growing stage compared to the advanced conventional financial services industry. The presence of the Shariah People Financing Bank also contributed to the economy as a credit channeling institution and it is expected that the wheels of the economy will spin faster and give a positive effect to the national economy. This study aims to analyze the influence of internal and external factors on the performance of Sharia Bank Financing in Indonesia Year 2011-2016. The analytical tool used in this research is the Error Corretion Model (ECM) which assumes the existence of a long-run equilibrium relationship between two or more economic variables, however in the short term that occurs is disequilibrium. With the error correction mechanism, a proportion of disequilibrium in a period is corrected in the next period. The results of this study indicate in the short term, internal factors represented by CAR and BOPO, and external factors are represented Exchange Rate and Inflation does not affect the Return On Asset Bank Syariah Rakyat Rakyat. In the long run CAR, BOPO and Kurs have a significant effect, while inflation does not significantly affect Return On Asset of Rural Bank of Sharia Liabilities

Tau repeat regions contain conserved histidine residues that modulate microtubule-binding in response to changes in pH.

Tau, a member of the MAP2/tau family of microtubule-associated proteins, stabilizes and organizes axonal microtubules in healthy neurons. In neurodegenerative tauopathies, tau dissociates from microtubules and forms neurotoxic extracellular aggregates. MAP2/tau family proteins are characterized by three to five conserved, intrinsically disordered repeat regions that mediate electrostatic interactions with the microtubule surface. Here, we used molecular dynamics, microtubule-binding experiments, and live-cell microscopy, revealing that highly-conserved histidine residues near the C terminus of each microtubule-binding repeat are pH sensors that can modulate tau-microtubule interaction strength within the physiological intracellular pH range. We observed that at low pH (<7.5), these histidines are positively charged and interact with phenylalanine residues in a hydrophobic cleft between adjacent tubulin dimers. At higher pH (>7.5), tau deprotonation decreased binding to microtubules both in vitro and in cells. Electrostatic and hydrophobic characteristics of histidine were both required for tau-microtubule binding, as substitutions with constitutively and positively charged nonaromatic lysine or uncharged alanine greatly reduced or abolished tau-microtubule binding. Consistent with these findings, tau-microtubule binding was reduced in a cancer cell model with increased intracellular pH but was rapidly restored by decreasing the pH to normal levels. These results add detailed insights into the intracellular regulation of tau activity that may be relevant in both normal and pathological conditions

Molecular structure, DNA binding mode, photophysical properties and recommendations for use of SYBR Gold

SYBR Gold is a commonly used and particularly bright fluorescent DNA stain, however, its chemical structure is unknown and its binding mode to DNA remains controversial. Here, we solve the structure of SYBR Gold by NMR and mass spectrometry to be 2-N-(3-dimethylaminopropyl)-N-propylamino]-4-2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene-1-phenyl-quinolinium and determine its extinction coefficient. We quantitate SYBR Gold binding to DNA using two complementary approaches. First, we use single-molecule magnetic tweezers (MT) to determine the effects of SYBR Gold binding on DNA length and twist. The MT assay reveals systematic lengthening and unwinding of DNA by 19.1° ± 0.7° per molecule upon binding, consistent with intercalation, similar to the related dye SYBR Green I. We complement the MT data with spectroscopic characterization of SYBR Gold. The data are well described by a global binding model for dye concentrations ≤2.5~μM, with parameters that quantitatively agree with the MT results. The fluorescence increases linearly with the number of intercalated SYBR Gold molecules up to dye concentrations of ∼2.5~μM, where quenching and inner filter effects become relevant. In summary, we provide a mechanistic understanding of DNA-SYBR Gold interactions and present practical guidelines for optimal DNA detection and quantitative DNA sensing applications using SYBR Gold

Retrospective model-based inference guides model-free credit assignment

An extensive reinforcement learning literature shows that organisms assign credit efficiently, even under conditions of state uncertainty. However, little is known about credit-assignment when state uncertainty is subsequently resolved. Here, we address this problem within the framework of an interaction between model-free (MF) and model-based (MB) control systems. We present and support experimentally a theory of MB retrospective-inference. Within this framework, a MB system resolves uncertainty that prevailed when actions were taken thus guiding an MF credit-assignment. Using a task in which there was initial uncertainty about the lotteries that were chosen, we found that when participants’ momentary uncertainty about which lottery had generated an outcome was resolved by provision of subsequent information, participants preferentially assigned credit within a MF system to the lottery they retrospectively inferred was responsible for this outcome. These findings extend our knowledge about the range of MB functions and the scope of system interactions

Aging effect, reproducibility, and test-retest reliability of a new cerebral amyloid angiopathy MRI severity marker-cerebrovascular reactivity to visual stimulation

Background Decreased cerebrovascular reactivity, measured as changes in blood-oxygen-level-dependent (BOLD) signal, is a potential new cerebral amyloid angiopathy (CAA) severity marker. Before clinical application, the effect of aging on BOLD parameters, and reproducibility and test-retest reliability of these parameters should be assessed. Purpose Assess the effect of healthy aging on cerebrovascular reactivity (BOLD amplitude, time to peak, and time to baseline). And determine reproducibility and test-retest reliability of these parameters. Study Type Prospective-observational. Population Eighty-six healthy adults (mean age 56 years, 55% female), 10 presymptomatic D-CAA mutation carriers (mean age 34 years, 70% female), and 10 symptomatic D-CAA mutation carriers (mean age 54 years, 70% female). Field Strength/Sequence 3-T, three-dimensional (3D) T1-weighted MRI and gradient echo BOLD fMRI. Assessment To assess test-retest reliability of BOLD parameters, i.e. BOLD amplitude, time to peak, and time to baseline, BOLD fMRI scans were repeated three times immediately after each other, in both controls and mutation carriers. To assess reproducibility, BOLD fMRI scans were repeated with a 3-week interval for each subject. Statistical Tests Linear regression analyses and two-way mixed absolute agreement intra-class correlation approach. Results Healthy aging was associated with decreased BOLD amplitude (beta = -0.711) and prolonged time to baseline (beta = 0.236) in the visual cortex after visual stimulation Reproducibility of BOLD amplitude was excellent (ICC 0.940) in the subgroup of healthy adults. Test-retest reliability for BOLD amplitude was excellent in healthy adults (ICC 0.856-0.910) and presymptomatic D-CAA mutation carriers (ICC 0.959-0.981). In symptomatic D-CAA mutation carriers, test-retest reliability was poor for all parameters (ICCs < 0.5). Data Conclusion Healthy aging is associated with decreased cerebrovascular reactivity, measured by changes in BOLD response to visual stimulation. The BOLD amplitude appears to be a robust measurement in healthy adults and presymptomatic D-CAA mutation carriers, but not in symptomatic D-CAA mutation carriers.Multivariate analysis of psychological dat

High-yield methods for accurate two-alternative visual psychophysics in head-fixed mice

Research in neuroscience increasingly relies on the mouse, a mammalian species that affords unparalleled genetic tractability and brain atlases. Here, we introduce high-yield methods for probing mouse visual decisions. Mice are head-fixed, facilitating repeatable visual stimulation, eye tracking, and brain access. They turn a steering wheel to make two alternative choices, forced or unforced. Learning is rapid thanks to intuitive coupling of stimuli to wheel position. The mouse decisions deliver high-quality psychometric curves for detection and discrimination and conform to the predictions of a simple probabilistic observer model. The task is readily paired with two-photon imaging of cortical activity. Optogenetic inactivation reveals that the task requires mice to use their visual cortex. Mice are motivated to perform the task by fluid reward or optogenetic stimulation of dopamine neurons. This stimulation elicits a larger number of trials and faster learning. These methods provide a platform to accurately probe mouse vision and its neural basis

A Densified Liquid Methane Delivery System for the Altair Ascent Stage

The Altair Lunar Lander is currently carrying options for both cryogenic and hypergolic ascent stage propulsion modules. The cryogenic option uses liquid methane and liquid oxygen to propel Altair from the lunar surface back to rendezvous with the Orion command module. Recent studies have determined that the liquid methane should be densified by subcooling it to 93 K in order to prevent over-pressurization of the propellant tanks during the 210 day stay on the lunar surface. A trade study has been conducted to determine the preferred method of producing; loading, and maintaining the subcooled, densified liquid methane onboard Altair from a ground operations perspective. The trade study took into account the limitations in mass for the launch vehicle and the mobile launch platform as well as the historical reliability of various components and their thermal efficiencies. Several unique problems were encountered, namely delivering a small amount of a cryogenic propellant to a flight tank that is positioned over 350 ft above the launch pad as well as generating the desired delivery temperature of the methane at 93 K which is only 2.3 K above the methane triple point of 90.7 K. Over 20 methods of subcooled liquid methane production and delivery along with the associated system architectures were investigated to determine the best solutions to the problem. The top four cryogenic processing solutions were selected for further evaluation and detailed thermal modeling. This paper describes the results of the preliminary trade analysis of the 20 plus methane densification methods considered. The results of the detailed analysis will be briefed to the Altair Project Office and their propulsion team as well as the Ground Operations Project Office before the down-select is made between cryogenic and hypergolic ascent stages in August 2010