Orion GN&C Detection and Mitigation of Parachute Pendulosity

New techniques being employed by Orion guidance, navigation, and control (GN&C) using a reaction control system (RCS) under parachutes are described. Pendulosity refers to a pendulum-oscillatory mode that can occur during descent under main parachutes and that has been observed during Orion parachute drop tests. The pendulum mode reduces the ability of GN&C to maneuver the suspended vehicle resulting in undesirable increases to structural loads at touchdown. Parachute redesign efforts have been unsuccessful in reducing the pendulous behavior necessitating GN&C mitigation options. An observer has been developed to estimate the pendulum motion as well as the underlying wind velocity vector. Using this knowledge, the control system maneuvers the vehicle using two separate strategies determined by wind velocity magnitude and pendulum energy thresholds; at high wind velocities the vehicle is aligned with the wind direction and for cases with lower wind velocities and large pendulum amplitudes the vehicle is aligned such that it is perpendicular to the swing plane. Pendulum damping techniques using RCS thrusters are discussed but have not been selected for use onboard the Orion spacecraft. The techniques discussed in this paper will be flown on Exploration Mission 1 (EM-1)

Global Corporate Governance: Implications For A Functionally Harmonized Legal Infrastructure

As developing and centrally planned economies shift toward decentralized market economies, they will revise their corporate governance rules to attract foreign investors and foster economic growth.  However, the expansion of firms internationally creates the immediate problem of cross-border bankruptcy and policy makers will eventually have to turn to functional harmonization of national bankruptcy laws as well as other means of corporate governance to maintain fairness and to facilitate a freer flow of cross-border investment.   We propose three major changes to global governance:  (1) a functionally harmonized system of bankruptcy laws that supersede national bankruptcy laws  (2) contractual corporate governance via securities exchange listing and (3) arbitration as a means to enforce global recourse. &nbsp

Implications Of The Risk-Based Capital Requirements Of Implicit Recourse In Asset Securitizations In The Banking Industry

We consider implications of the risk-based capital requirements of implicit recourse in asset securitizations. These implications include issues in finance such as risk management and contracting between counterparties. The first part of our analysis deals with asset securitizations where originating institutions provide investors with implicit recourse. We show that the risk-based capital requirements associated with the new regulatory definition of implicit recourse may discourage some banks from offering implicit recourse in their asset securitizations. This suggests that the new regulatory definition of implicit recourse may be a workable compromise between supervisory regulators and originating institutions. We then consider a scenario where banks enter into reinsurance contracting with banks in other regions to mitigate some regional economic risks. These reinsurance contracts may enable banks to improve the performance of their balance sheet assets. Although we find weak correlation among equity returns for regional banks, future high correlation among bank portfolios could pose a problem to regulators because when a bank gets into financial distress this may spill over to other network banks. Widening yield spreads in asset securitizations might serve as an early warning signal of financial distress. Thus, regulators might devote more supervisory resources on originating institutions when their asset securitization yield spreads widen

Orion Touchdown Heading Control

At touchdown Orion must be aligned so that the crew person's feet are forward in the direction of the horizontal velocity. To ensure that this requirement is met active heading control is being implemented on the Orion crew module. This technique reduces probability of roll-over during splashdown, assures axial loads on the crew at touchdown, and alleviates structural requirements on impact allowing for a light-weight structural design. On-board sensors are used to measure current vehicle orientation and horizontal velocity used in generation of the heading error signal. Linear velocity measured by the IMU drifts while under parachutes due to wind gusts and has to be corrected by GPS; this makes GPS critical for successful landing. Jet fire logic is achieved by use of a phase-plane and commands are realized by using roll jets from the reaction control system (RCS); using pre existing hardware eliminates additional hardware and structural requirements. Touchdown performance is measured by an orientation envelope that was co-developed with structures so that the performance requirements overlap adding system redundancy. Heading control also introduces new difficulties to be addressed such as parachute line twist torque as well as increasing vehicle sensitivity to wind shifts and sea states. Solving these difficulties requires added complexity to flight software as well as increasing the propellant required to achieve successful touchdown. while offering promising results, the criticality of GPS along with a significant propellant cost raises questions on the effectiveness of using touchdown heading control

Self-reported effectiveness and physician consultation rate in users of over-the-counter histamine-2 receptor antagonists

Decreased physician visits for dyspepsia were predicted with the histamine-2 receptor antagonists (H2RA) release to over-the-counter (OTC) status. The aim of this study was to examine the presentation frequency for dyspeptic complaints before and after the OTC release of the H2RA and the self-reported effectiveness of OTC H2RA. METHODS : Two cross-sectional surveys were used in a community sample. The patients comprised a random age- and sex-stratified sample of 1600 ambulatory adults in 1993 and 1800 in 1997. Self-report, valid mail surveys gathered information on healthcare seeking and gastrointestinal symptoms in 1993 and 1997 and antisecretory use in 1997. RESULTS : Presentation frequency for dyspepsia was 22% in 1993 versus 23.5% in 1997. Only 16% of chronic users of the OTC H2RA obtained complete relief of symptomatic episodes. Use of an OTC H2RA was highly associated with presentation to a physician in the past year. CONCLUSIONS : OTC H2RA infrequently provided the complete relief desired by patients. Presentation frequency to physicians for dyspeptic complaints did not change with availability of H2RA OTC.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72813/1/j.1572-0241.2001.03602.x.pd

Peeling of Long, Straight Carbon Nanotubes from Surfaces

The adhesion of long, straight, single-walled carbon nanotubes to surfaces is examined usingmultidimensional force spectroscopy. We observed characteristic signatures in the deflection and frequency response of the cantilever indicative of nanotube buckling and slip-stickmotion as a result of compression and subsequent adhesion and peeling of the nanotube fromthe surface.The spring constant and the elastic modulus of the SWNT were estimated from the frequency shifts under tension. Using elastica modeling for postbuckled columns, we have determined the static coefficient of friction for the SWNT on alkanethiol-modified gold surfaces and showed that it varies with the identity of the monolayer terminal group.Fil: Barker, Kane M.. Georgia Institute of Technology. School of Chemistry and Biochemistry; Estados UnidosFil: Poggi, Mark A.. Georgia Institute of Technology. School of Chemistry and Biochemistry; Estados UnidosFil: Lizarraga, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. Georgia Institute of Technology. School of Chemistry and Biochemistry; Estados UnidosFil: Lillehei, Peter T.. NASA Langley Research Center. Advanced Materials and Processing Branch; Estados UnidosFil: Ferri, Aldo. Georgia Institute of Technology. George W. Woodruff School of Mechanical Engineering; Estados UnidosFil: Bottomley, Lawrence A.. Georgia Institute of Technology. School of Chemistry and Biochemistry; Estados Unido

Orion GN&C Detection and Mitigation of Parachute Pendulosity

New techniques being employed by Orion guidance, navigation, and control (GN&C) using a reaction control system (RCS) under parachutes are described. Pendulosity refers to a pendulum-oscillatory mode that can occur during descent under main parachutes and that has been observed during Orion parachute drop tests. The pendulum mode reduces the ability of GN&C to maneuver the suspended vehicle resulting in undesirable increases to structural loads at touch-down. Parachute redesign efforts have been unsuccessful in reducing the pendulous behavior necessitating GN&C mitigation options. An observer has been developed to estimate the pendulum motion as well as the underlying wind velocity vector. Using this knowledge the control system maneuvers the vehicle using two separate strategies determined by a wind velocity magnitude threshold; at high wind velocities the vehicle is aligned with the wind direction and for cases with lower wind velocities the vehicle is aligned such that it is perpendicular to the swing plane. Pendulum damping techniques using RCS thrusters are discussed but have not been selected for use onboard the Orion spacecraft. The techniques discussed in this paper will be flown on Exploration Mission 1 (EM-1)

The glycosphingolipid globotriaosylceramide in the metastatic transformation of colon cancer

The most devastating aspect of cancer is the emergence of metastases. Thus, identification of potentially metastatic cells among a tumor cell population and the underlying molecular changes that switch cells to a metastatic state are among the most important issues in cancer biology. Here we show that, although normal human colonic epithelial cells lack the glycosphingolipid globotriaosylceramide (Gb3), this molecule is highly expressed in metastatic colon cancer. In addition, a subpopulation of cells that are greatly enriched in Gb3 and have an invasive phenotype was identified in human colon cancer cell lines. In epithelial cells in culture, Gb3 was necessary and sufficient for cell invasiveness. Transfection of Gb3 synthase, resulting in Gb3 expression in noncancerous polarized epithelial cells lacking endogenous Gb3, induced cell invasiveness. Furthermore, Gb3 knockdown by small inhibitory RNA in colon cancer epithelial cells inhibited cell invasiveness. Gb3 is the plasma membrane receptor for Shiga toxin 1. The noncatalytic B subunit of Shiga toxin 1 causes apoptosis of human colon cancer cells expressing Gb3. Injections of the B subunit of Shiga toxin 1 into HT29 human colon cancer cells engrafted into the flanks of nude mice inhibited tumor growth. These data demonstrate the appearance of a subpopulation of Gb3 containing epithelial cells in the metastatic stage of human colon cancer and suggest their possible role in colon cancer invasiveness

Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques

13 pages, 6 figures, 4 tables, accepted for publication in the Astronomical Journal (submitted 25 Feb 2019; accepted 28 April 2019). Machine readable tables and Posteriors from the RadVel fits are available here: http://stephenkane.net/rvfits.tarThe sensitivities of radial velocity (RV) surveys for exoplanet detection are extending to increasingly longer orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feature that can either present as the sole detectable companion to the host star, or as an additional signal overlain on the signatures of previously discovered companion(s). A diagnostic that can confirm or constrain scenarios in which the trend is caused by an unseen stellar rather than planetary companion is the use of high-contrast imaging observations. Here, we present RV data from the Anglo-Australian Planet Search (AAPS) for 20 stars that show evidence of orbiting companions. Of these, six companions have resolved orbits, with three that lie in the planetary regime. Two of these (HD 92987b and HD 221420b) are new discoveries. Follow-up observations using the Differential Speckle Survey Instrument (DSSI) on the Gemini South telescope revealed that 5 of the 20 monitored companions are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data to place constraints on the mass of the companions for the remaining systems. Our analysis shows that a planetary-mass companion provides the most likely self-consistent explanation of the data for many of the remaining systems.Peer reviewedFinal Accepted Versio