Significant achievements in the planetary geology program, 1980

Recent developments in planetology research as reported at the 1980 NASA Planetology Program Principal Investigators meeting are summarized. Important developments are summarized in topics ranging from solar system evolution and comparative planetology to geologic processes active on other planetary bodies

Significant achievements in the planetary geology program, 1981

Recent developments in planetology research as reported at the 1981 NASA Planetary Geology Principal Investigators meeting are summarized. The evolution of the solar system, comparative planetology, and geologic processes active on other planets are considered. Galilean satellites and small bodies, Venus, geochemistry and regoliths, volcanic and aeolian processes and landforms, fluvial and periglacial processes, and planetary impact cratering, remote sensing, and cartography are discussed

The level of BMP4 signaling is critical for the regulation of distinct T-box gene expression domains and growth along the dorso-ventral axis of the optic cup

Background: Polarised gene expression is thought to lead to the graded distribution of signaling molecules providing a patterning mechanism across the embryonic eye. Bone morphogenetic protein 4 (Bmp4) is expressed in the dorsal optic vesicle as it transforms into the optic cup. Bmp4 deletions in human and mouse result in failure of eye development, but little attempt has been made to investigate mammalian targets of BMP4 signaling. In chick, retroviral gene overexpression studies indicate that Bmp4 activates the dorsally expressed Tbx5 gene, which represses ventrally expressed cVax. It is not known whether the Tbx5 related genes, Tbx2 and Tbx3, are BMP4 targets in the mammalian retina and whether BMP4 acts at a distance from its site of expression. Although it is established that Drosophila Dpp ( homologue of vertebrate Bmp4) acts as a morphogen, there is little evidence that BMP4 gradients are interpreted to create domains of BMP4 target gene expression in the mouse.Results: Our data show that the level of BMP4 signaling is critical for the regulation of distinct Tbx2, Tbx3, Tbx5 and Vax2 gene expression domains along the dorso-ventral axis of the mouse optic cup. BMP4 signaling gradients were manipulated in whole mouse embryo cultures during optic cup development, by implantation of beads soaked in BMP4, or the BMP antagonist Noggin, to provide a local signaling source. Tbx2, Tbx3 and Tbx5, showed a differential response to alterations in the level of BMP4 along the entire dorso-ventral axis of the optic cup, suggesting that BMP4 acts across a distance. Increased levels of BMP4 caused expansion of Tbx2 and Tbx3, but not Tbx5, into the ventral retina and repression of the ventral marker Vax2. Conversely, Noggin abolished Tbx5 expression but only shifted Tbx2 expression dorsally. Increased levels of BMP4 signaling caused decreased proliferation, reduced retinal volume and altered the shape of the optic cup.Conclusion: Our findings suggest the existence of a dorsal-high, ventral-low BMP4 signaling gradient across which distinct domains of Tbx2, Tbx3, Tbx5 and Vax2 transcription factor gene expression are set up. Furthermore we show that the correct level of BMP4 signaling is critical for normal growth of the mammalian embryonic eye

Radiation temperature measurements of the nitrogen afterglow plasma

Radiation temperature measurements of nitrogen afterglow plasm

SCR Blocking Pulse Gate Amplifier-Patent

Silicon controlled rectifier pulse gate amplifier for blocking false gating caused by negative transient voltage

Sterilizable liquid propulsion system Quarterly progress report, 2 Jan. - 31 Mar. 1967

Basic design, component selection, and materials compatibility tests for sterilizable liquid bipropellant propulsion syste

Representation of Propagation Parameters for the Plasma in a Magnetic Field

No abstract availabl

Transport phenomena in ionized gases as an initial value problem

Transport phenomena in ionized gases as initial value proble

State Case Studies of Infant and Early Childhood Mental Health Systems: Strategies for Change

Profiles efforts to develop mental health identification and intervention systems for children up to age 5 in Colorado, Indiana, Massachusetts, and Rhode Island. Examines hurdles, reform potentials, and lessons learned, including the role of partnerships

THE EFFECTS OF FUTURES TRADING BY LARGE HEDGE FUNDS AND CTAS ON MARKET VOLATILITY

This study uses the newly available data from the CFTC to investigate the market impact of futures trading by large hedge funds and CTAs. Regression results show that there is a positive relationship between the trading volume of large hedge funds and CTAs and market volatility. However, a positive relationship between hedge fund and CTA trading volume and market volatility is consistent with either a private information or noise trader hypothesis. Three additional tests are conducted to distinguish between the private information hypothesis and the noise trader hypothesis. The first test consisted of identifying the noise component exhibited in return variances over different holding periods. The variance ratio tests provide little support for the noise trader hypothesis. The second test examined whether positive feedback trading characterized large hedge fund and CTA trading behavior. These results suggest that trading decisions by large hedge funds and CTAs, although influenced in small part by past price changes, are not driven by past price changes. The third test consists of estimating the profits and losses associated with the open interest positions of large hedge funds and CTAs. This test is based on the argument that speculative trading can only be destabilizing if speculators buy when prices are high and sell when prices are low, which in turn, implies that destabilizing speculators lose money. Across all thirteen markets, the profit for large hedge funds and CTAs is estimated to be just under $400 million. This implies that the trading decisions are likely based on valuable private information. Overall, the evidence presented in this study suggests trading by large hedge funds and CTAs is based on private fundamental information. These findings imply large hedge funds and CTAs benefit market efficiency by bringing valuable, fundamental information to the market through their trading.hedge fund, commodity trading advisor, volatility, market efficiency, futures markets, Marketing,