bluuebunny/crossref_metadata_2025 huggingface dataset:
Allelopathy Between Zooplankton: A Mechanism for Interference Competition
Authors: Folt Carol , Goldman Charles R.
Published: October 2006

The filtering rate of the copepod
Diaptomus tyrrelli
is reduced in the presence of its potential competitor and predator,
Epischura nevadensis
, by as much as 60 percent. This effect is caused by a chemical released into the water by
Epischura
. The chemical does not pass through dialysis tubing with a pore size of 10
4
angstroms, indicating that it is a large molecular weight compound. The reduction in filtering rate is the result of interference competition between two species and may be linked to the evolution of a mechanism for avoiding predation.
Calcium-Induced Movement of Troponin-I Relative to Actin in Skeletal Muscle Thin Filaments
Authors: Tao Terence , Gong Bang-Jian , Leavis Paul C.
Published: October 2006

The role of troponin-I (the inhibitory subunit of troponin) in the regulation by Ca
2+
of skeletal muscle contraction was investigated with resonance energy transfer and photo cross-linking techniques. The effect of Ca
2+
on the proximity of troponin-I to actin in reconstituted rabbit skeletal thin filaments was determined. The distance between the cysteine residue at position 133 (Cys
133
) of troponin-I and Cys
374
of actin increases by approximately 15 angstroms on binding of Ca
2+
to troponin-C. Also, troponin-I labeled at Cys
133
with benzophenone-4-maleimide could be photo cross-linked to actin in the absence of Ca
2+
, but not in its presence. These results suggest that troponin-I is attached to actin in the Ca
2+
-free or relaxed state of muscle, and that it detaches from actin on Ca
2+
activation of contraction. Thus, troponin-I may function as a Ca
2+
-dependent molecular switch in regulation of skeletal muscle contraction.
Measurement of Solar Radius Changes
Authors: LaBonte Barry J. , Howard Robert
Published: October 2006

Photoelectric solar radius measurements since 1974 at Mount Wilson show no change in the solar radius, with a limit of about 0.1 arc second (1 standard deviation), over the interval. The limit is set by residual systematic effects.
Relativistic Jets in SS 433
Authors: Margon Bruce
Published: October 2006

A variety of recent optical, radio, and x-ray observations have confirmed the hypothesis that the peculiar star SS 433 is ejecting two narrow, opposed, highly collimated jets of matter at one-quarter the speed of light. This unique behavior is probably driven by mass exchange between a relatively normal star and a compact companion, either a neutron star or a black hole. However, numerous details regarding the energetics, radiation, acceleration, and collimation of the jets remain to be understood. This phenomenon may well be a miniature example of similar collimated ejection of gas by active extragalactic objects such as quasars and radio galaxies.
Voyager 2 Plasma Wave Observations at Saturn
Authors: Scarf F. L. , Gurnett D. A. , Kurth W. S. , Poynter R. L.
Published: October 2006

The first inbound Voyager 2 crossing of Saturn's bow shock [at 31.7 Saturn radii (
R
S
), near local noon] and the last outbound crossing (at 87.4
R
S
, near local dawn) had similar plasma wave signatures. However, many other aspects of the plasma wave measurements differed considerably during the inbound and outbound passes, suggesting the presence of effects associated with significant north-south or noon-dawn asymmetries, or temporal variations. Within Saturn's magnetosphere, the plasma wave instrument detected electron plasma oscillations, upper hybrid resonance emissions, half-gyrofrequency harmonics, hiss and chorus, narrowband electromagnetic emissions and broadband Saturn radio noise, and noise bursts with characteristics of static. At the ring plane crossing, the plasma wave instrument also detected a large number of intense impulses that we interpret in terms of ring particle impacts on Voyager 2.
Observations of a Comet on Collision Course with the Sun
Authors: Michels D. J. , Sheeley N. R. , Howard R. A. , Koomen M. J.
Published: October 2006

A brilliant new comet (1979 XI: Howard-Koomen-Michels) was discovered in data from the Naval Research Laboratory's orbiting SOLWIND coronagraph. An extensive sequence of pictures, telemetered from the P78-1 satellite, shows the coma, accompanied by a bright and well-developed tail, passing through the coronagraph's field of view at a few million kilometers from the sun. Preliminary orbital calculations based on the observed motion of the comet's head and morphology of the tail indicate that this previously unreported object is a sungrazing comet and may be one of the group of Kreutz sungrazers. It appears from the data that the perihelion distance was less than 1 solar radius, so that the cometary nucleus encountered dense regions of the sun's atmosphere, was completely vaporized, and did not reappear after the time of closest approach to the sun. After this time, however, cometary debris, scattered into the ambient solar wind, caused a brightening of the corona over one solar hemisphere and to heliocentric distances of 5 to 10 solar radii.
Lower Devonian Gametophytes: Relation to the Phylogeny of Land Plants
Authors: Remy Winfried
Published: October 2006

Three gametophytic plants now known from the Lower Devonian of Scotland and Germany show common features in their fertile parts. The morphological and anatomical structures indicate affinities to bryophytic gametophytes, although there is no evidence for a parasitic sporogonium-like sporophyte as in the Bryophyta. Several of the vascular plant sporophytes from the Rhynie Chert also have a few characteristics reminiscent of bryophytes. But these ancient gametophytes, if related to the sporophytes, indicate a closer relation of Bryophyta to Tracheophyta than would the study of sporophytes alone.
A 49-Kilodalton Phosphoprotein in theDrosophilaPhotoreceptor Is an Arrestin Homolog
Authors: Yamada Takuma , Takeuchi Yutaka , Komori Naoka , Kobayashi Hisao , Sakai Yutaka , Hotta Yoshiki , Matsumoto Hiroyuki
Published: October 2006

The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in theDrosophilaphotoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3′,5′-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C.
Solar Neutrino Production of Technetium-97 and Technetium-98
Authors: Cowan G. A. , Haxton W. C.
Published: October 2006

It may be possible to determine the boron-8 solar neutrino flux, averaged over the past several million years, from the concentration of technetium-98 in molybdenite. The mass spectrometry of this system is greatly simplified by the absence of stable technetium isotopes, and the presence of the fission product technetium-99 provides a monitor of uranium-induced backgrounds. This geochemical experiment could provide the first test of nonstandard solar models that suggest a relation between the chlorine-37 solar neutrino puzzle and the recent ice age.
Localization of Calcium in Amyloplasts of Root-Cap Cells Using Ion Microscopy
Authors: Chandra S. , Chabot J. F. , Morrison G. H. , Leopold A. C.
Published: October 2006

An ion microscope has been used to demonstrate that the calcium ion is present in the amyloplasts of root-cap cells of corn, pea, and lettuce. The localization of calcium in the gravity-sensing organelle suggests a possible role of calcium in the gravity-sensing mechanism of plant roots.
Venus: Global Surface Radar Reflectivity
Authors: Pettengill G. H. , Ford P. G. , Nozette S.
Published: October 2006

Observations of the surface of Venus, carried out by the Pioneer Venus radar mapper at a wavelength of 17 centimeters, reveal a global mean reflectivity at normal incidence of 0.13 ± 0.03. Over the surface, variations from a low of 0.03 ± 0.01 to a high of 0.4 ± 0.1 are found, with Theia Mons, previously identified as possibly volcanic, showing a value of 0.28 ± 0.07. Regions of high reflectivity may consist of rocks with substantial inclusions of highly conductive sulfides.
Calcium Ionophore A23187 Stimulates Cytokinin-Like Mitosis in
Funaria
Authors: Saunders Mary Jane , Hepler Peter K.
Published: October 2006

The plant hormone cytokinin stimulates asymmetrical division in target cells of the protonema of the moss
Funaria hygrometrica
, leading to bud formation. The initial division can be induced in the absence of cytokinin by the calcium ionophore A23187 in medium containing calcium. These findings suggest that increases in the concentration of intracellular calcium are essential to bud initiation. Therefore mitotic regulation by cytokinin may be due, at least in part, to the modulation of intracellular calcium ion concentration.
Detoxification Enzyme Differences Between a Herbivorous and Predatory Mite
Authors: Mullin C. A. , Croft B. A. , Strickler K. , Matsumura F. , Miller J. R.
Published: October 2006

The detoxification capabilities of the predatory mite
Amblyseius fallacis
and its herbivorous prey
Tetranychus urticae
are fundamentally different. The activities of mixed-function oxidase and trans-epoxide hydrolase are higher in the prey than in the predator; those of
cis
-epoxide hydrolase and glutathione transferase are lower; and esterase activity is similar. Dissimilarities may be related both to differing adaptations to plant allelochemicals and to the higher respiration rate of the predator. Hydrolytic and conjugating reactions appear more important than oxidative pathways in imparting organophosphate resistance to these acarines. These resistances provide insecticide selectivity favorable to the predator and improved integrated pest control.
Regulation of Progesterone Receptor-Mediated Transcription by Phosphorylation
Authors: Denner Larry A. , Weigel Nancy L. , Maxwell Beth L. , Schrader William T. , O'Malley Bert W.
Published: October 2006

The progesterone receptor (PR) in the chicken oviduct is a phosphoprotein that regulates gene transcription in the presence of progesterone. Treatment with progesterone in vivo stimulates phosphorylation of the progesterone receptor. With transient transfection assays, the present work has tested whether phosphorylation participates in the regulation of PR-mediated transcription. Treatment with 8-bromo-cyclic adenosine monophosphate (8-Br cAMP), a stimulator of cAMP-dependent protein kinase [protein kinase A (PKA)], mimicked progesterone-dependent, receptor-mediated transcription in the absence of progesterone. Inhibition of PKA blocked hormone action. Treatment with okadaic acid, an inhibitor of protein phosphatases 1 and 2A, stimulated transcription in a manner similar to that of progesterone. These observations suggest that phosphorylation of the PR or other proteins in the transcription complex can modulate PR-mediated transcription in vivo.
The University, Industry, and Cooperative Research
Authors: Giamatti A. Bartlett
Published: October 2006

Yale University intends to issue a statement of policy governing the nature and extent of university and faculty involvement in the commercial application of scientific research. This policy will be based on the university's principles of openness and free dissemination of ideas, and will recognize the need of profit-oriented companies to treat knowledge as private property. The university will continue to allow relationships between faculty members and commercial companies, even in arrangements involving university-based results, but a faculty member who goes beyond any reasonable definition of "consulting" may be asked to take an unpaid leave of absence or to sever his or her ties with the university. While a university should not ignore the potential availability of funds from commercial sponsors, neither should it be driven to arrangements that are not compatible with the norms and mission of the university.
Neural Crest and the Origin of Vertebrates: A New Head
Authors: Gans Carl , Northcutt R. Glenn
Published: October 2006

Most of the morphological and functional differences between vertebrates and other chordates occur in the head and are derived embryologically from muscularized hypomere, neural crest, and epidermal (neurogenic) placodes. In the head, the neural crest functions as mesoderm and forms connective, skeletal, and muscular tissue. Both the neural crest and the epidermal placodes form special sense organs and other neural structures. These structures may be homologous to portions of the epidermal nerve plexus of protochordates. The transition to vertebrates apparently was associated with a shift from a passive to an active mode of predation, so that many of the features occurring only in vertebrates became concentrated in the head.
Origin of Whales in Epicontinental Remnant Seas: New Evidence from the Early Eocene of Pakistan
Authors: Gingerich Philip D. , Wells Neil A. , Russell Donald E. , Shah S. M. Ibrahim
Published: October 2006

Pakicetus inachusfrom the early Eocene of Pakistan is the oldest and most primitive cetacean known. The dentition ofPakicetusresembles that of carnivorous mesonychid land mammals as well as middle Eocene cetaceans. The otic region of the cranium lacks characteristic specializations of whales necessary for efficient directional hearing under water.Pakicetusoccurs with a land-mammal fauna in fluvial sediments bordering epicontinental Eocene remnants of the eastern Tethys seaway. Discovery ofPakicetusstrengthens earlier inferences that whales originated from terrestrial carnivorous mammals and suggests that whales made a gradual transition from land to sea in the early Eocene, spending progressively more time feeding on planktivorous fishes in shallow, highly productive seas and embayments associated with tectonic closure of eastern Tethys.
Modes of Larval Development and Rates of Speciation in Early Tertiary Neogastropods
Authors: Hansen Thor A.
Published: October 2006

Although most warm-water molluscs have planktotrophic larval stages, some living families of tropical neogastropods are dominated by nonplanktotrophic development. Fossil protoconchs of early Tertiary neogastropods indicate that some families became progressively dominated by nonplanktotrophic development through time. This trend may be the result of higher speciation rates for nonplanktotrophs and a unidirectional trend in developmental change.
A Program for Planetary Exploration
Authors: Morrison David , Hinners Noel W.
Published: October 2006

On the basis of a two-year study, the NASA Solar System Exploration Committee recommends a core program of planetary missions through the year 2000. By incorporating a number of cost-saving measures, an exciting program of planetary exploration can be achieved within a highly constrained NASA budget.
Phospholipid Methylation Unmasks Cryptic β-Adrenergic Receptors in Rat Reticulocytes
Authors: Strittmatter Warren J. , Hirata Fusao , Axelrod Julius
Published: October 2006

The effect of phospholipid methylation on the number of β-adrenergic receptor binding sites was examined in rat reticulocyte membranes. Stimulation of phosphatidylcholine synthesis by the introduction of the methyl donor
S
-adenosyl-L-methionine into reticulocyte ghosts increased the number of β-adrenergic receptor binding sites. The appearance of β-adrenergic binding sites was dependent on the formation of phosphatidylcholine by the enzyme that converts phosphatidyl-
N
-monomethylethanolamine to phosphatidylcholine, but not on the synthesis of phosphatidyl-
N
-monomethylethanolamine from phosphatidylethanolamine. Both the synthesis of phosphatidylcholine and the unmasking of cryptic receptors were time and temperature dependent and did not occur in the presence of the methyl transferase inhibitor,
S
-adenosyl-L-homocysteine.
Pituitary Hormones in Brain: Where, How, and Why?
Authors: Krieger Dorothy T. , Liotta Anthony S.
Published: October 2006

Peptide and protein hormones usually considered as being of pituitary origin have been detected within the central nervous system by means of radioimmunoassay, bioassay, and immunocytochemical techniques. Intracerebral administration of some of these hormones or fragments thereof elicit behavioral responses, suggesting that they may have a physiological role similar to that described for other peptidergic neurotransmitter or neuromodulator substances. Evidence available for some of these hormones indicates that they are synthesized within the central nervous system and that their regulation may differ from that of their pituitary counterparts.
Chesapeake Bay: An Unprecedented Decline in Submerged Aquatic Vegetation
Authors: Orth Robert J. , Moore Kenneth A.
Published: October 2006

Data on the distribution and abundance of submerged aquatic vegetation in Chesapeake Bay indicate a significant reduction in all species in all sections of the bay during the last 15 to 20 years. This decline is unprecedented in the bay's recent history. The reduction in one major species,
Zostera marina
, may be greater than the decline that occurred during the pandemic demise of the 1930's.
Solar System Ice: Amorphous or Crystalline?
Authors: Smoluchowski R.
Published: October 2006

The role of meteoritic bombardment on icy surfaces in the solar system is investigated. Using recent theoretical results concerning the nature of ejecta from impact craters in ice, the author concludes that the ratio of amorphous to crystalline ice surfaces should be lower than 1.0.
Discovery of a New Gravitational Lens System
Authors: Lawrence C. R. , Schneider D. P. , Schmidt M. , Bennett C. L. , Hewitt J. N. , Burke B. F. , Turner E. L. , Gunn J. E.
Published: October 2006

A new gravitational lens system, the triple radio source MG2016+112, has been discovered. Five emission lines at a redshift of 3.2733 ± 0.0014 have been identified in the spectra of two stellar objects of magnitude 22.5 coincident with radio components 3.4 arc seconds apart. The lines are the narrowest ever observed in objects at such a large redshift. The redshift of a 23rd-magnitude extended optical object coincident with the third radio component has not been determined spectroscopically, but its known optical properties are consistent with those of a giant elliptical galaxy with a redshift of about 0.8.
Energy Problems in Latin America
Authors: Goldemberg José
Published: October 2006

Present energy consumption patterns, known reserves of conventional energy sources (oil, gas, coal, and hydroelectricity), and the impact of the oil crisis on the oil-importing countries of Latin America are discussed. New approaches to energy use, including improvements on end-use efficiency, fuel substitutions, nonconventional energy sources, and changes in consumption patterns, are important. Of particular significance are the alcohol program in Brazil and the possibilities for increased use of hydroelectricity. Investments needed to sustain a reasonable increase in production from conventional energy sources up to 1990 are presented.
Interstellar Matter and Chemical Evolution
Authors: Peimbert M. , Serrano A. , Torres-Peimbert S.
Published: October 2006

The determination of chemical abundances of the interstellar medium is related to three different areas of astronomy: pregalactic conditions, stellar evolution, and chemical evolution of galaxies. The observed abundances permit the testing of theories associated with these areas. Knowledge of the abundances of helium, carbon, nitrogen, and neon relative to the abundance of hydrogen in the interstellar medium puts limits on current models of cosmology, stellar evolution, and galactic evolution.
Species Duration and Evolution: Benthic Foraminifera on the Atlantic Continental Margin of North America
Authors: Buzas Martin A. , Culver Stephen J.
Published: October 2006

Average species durations were estimated for 131 commonly occurring modern species. The duration of species occurring at depths of less than 200 meters is 16 million years, while for those at greater than 200 meters and at all depths it is 25 to 26 million years. Species (less than 200 meters) distributed from Florida to Newfoundland and from Florida to Cape Hatteras have about the same durations (18 to 20 million years). The duration for species restricted to north of Cape Hatteras is only 7 million years. The data suggest that evolutionary rates are greater in shallower than in deeper depths and greatest in the shallower northern area.
Packing Structures and Transitions in Liquids and Solids
Authors: Stillinger Frank H. , Weber Thomas A.
Published: October 2006

Classification of potential energy minima—mechanically stable molecular packings—offers a unifying principle for understanding condensed phase properties. This approach permits identification of an inherent structure in liquids that is normally obscured by thermal motions. Melting and freezing occur through characteristic sequences of molecular packings, and a defect-softening phenomenon underlies the fact that they are thermodynamically first order. The topological distribution of feasible transitions between contiguous potential minima explains glass transitions and associated relaxation behavior.
gCap39, a Calcium Ion- and Polyphosphoinositide-Regulated Actin Capping Protein
Authors: Yu Fu-Xin , Johnston Paul A. , Südhof Thomas C. , Yin Helen L.
Published: October 2006

The polymerization of actin filaments is involved in growth, movement, and cell division. It has been shown that actin polymerization is controlled by gelsolin, whose interactions with actin are activated by calcium ion (Ca
2+
) and inhibited by membrane polyphosphoinositides (PPI). A smaller Ca
2+
- and PPI-regulated protein, gCap39, which has 49% sequence identity with gelsolin, has been identified by cDNA cloning and protein purification. Like gelsolin, gCap39 binds to the fast-growing (+) end of actin filaments. However, gCap39 does not sever actin filaments and can respond to Ca
2+
and PPI transients independently, under conditions in which gelsolin is ineffective. The coexistence of gCap39 with gelsolin should allow precise regulation of actin assembly at the leading edge of the cell.
High-Resolution Nuclear Magnetic Resonance of Solids
Authors: Maciel Gary E.
Published: October 2006

The development of line-narrowing techniques, such as magic-angle spinning (MAS) and high-power decoupling, has led to powerful high-resolution nuclear magnetic resonance approaches for solid samples. In favorable cases (for instance, where high abundances of protons are present) cross polarization (CP) provides a means of circumventing the time bottleneck caused by inefficient spin-lattice relaxation in many solids. The combined CP-MAS approach for carbon-13 with proton decoupling has become a popular and routine experiment for organic solids. For many nuclides with spin quantum number I > 1/2 the central nuclear magnetic resonance transition can be employed in high-resolution experiments that involve rapid sample spinning. A continuing stream of advances holds great promise for the use of high-resolution techniques for the characterization of solids by a wide range of nuclides.
Cretaceous-Paleocene Terrestrial Faunas of India: Lack of Endemism During Drifting of the Indian Plate
Authors: Sahni Ashok
Published: October 2006

Recent paleontological investigations of six sections fringing the Deccan volcanic outcrops of the Indian peninsula indicate that terrestrial faunas during the Cretaceous-Paleocene transition lacked the endemism predicted by geophysical models of an oceanically isolated Indian subcontinent. At the generic and familial level there is a close correspondence between the Cretaceous vertebrates of peninsular India, Africa, and Madagascar. This suggests that a dispersal corridor, consisting of presently submerged aseismic elements (the Mascarene Plateau and the Chagos-Laccadive Ridge), existed between these landmasses about 80 million years ago as India drifted close to eastern Africa.
Droplet Impacts Upon Liquid Surfaces
Authors: Ching Bruce , Golay Michael W. , Johnson Thomas J.
Published: October 2006

The absorption and rebounding of single droplets and streams of droplets (of diameter less than 1200 micrometers) impacting upon the surface of a deep liquid have been examined experimentally. Conservation of mechanical energy and momentum have been used to explain rebounding droplet interactions, and impaction criteria have been established regarding the absorption of droplet streams. Surface tension is the dominant mechanism governing the observed behavior. Single droplets were never observed to rebound.
Ultrahigh Pressure: Beyond 2 Megabars and the Ruby Fluorescence Scale
Authors: Bell P. M. , Mao H. K. , Goettel K.
Published: October 2006

A new design of the diamond-window, high-pressure cell has permitted static pressure of 2.8 megabars to be generated for the first time. The design is unusually stable mechanically, and thus it should be possible to use the new cell to study most materials, including hydrogen, in the unexplored pressure region above 1 megabar.
Materials for Optical Information Processing
Authors: Glass A. M.
Published: October 2006

The goal for optical information processing is to use the unique characteristics of light which are not readily achieved with electronic devices, namely, ultrahigh speed (picoseconds), a high degree of parallelism (image processing), and conductor-free interconnection. The requirements of the nonlinear materials to perform such functions, using all-optical interactions, are discussed and the limitations of the nonlinear mechanisms are outlined.
Stable Carbon Isotope Ratios of Rock Varnish Organic Matter: A New Paleoenvironmental Indicator
Authors: Dorn Ronald I. , DeNiro Michael J.
Published: October 2006

Stable carbon isotope ratios of organic matter in rock varnishes of Holocene age from western North America and the Middle East show a strong association with the environment. This isotopic variability reflects the abundance of plants with different photosynthetic pathways in adjacent vegetation. Analyses of different layers of varnish on late Pleistocene desert landforms indicate that the carbon isotopic composition of varnish organic matter is a paleoenvironmental indicator.
Pentagonal and Icosahedral Order in Rapidly Cooled Metals
Authors: Nelson David R. , Halperin Bertrand I.
Published: October 2006

The discovery of an alloy of aluminum and manganese with sharp Bragg diffraction spots and an icosahedral point group symmetry was announced last year. The icosahedral symmetry appears to be an intrinsic property of the material and not an artifact of twinning. There are remarkable similarities between the observed diffraction patterns and aperiodic tesselations of space called Penrose tiles. The relation between the experiments and Penrose tiles, as well as phenomenological descriptions of the icosahedral aluminum-manganese alloy as a superposition of incommensurate density waves, are reviewed. Other types of exotic crystallography are also discussed.
Geochemical Indicator of Tectonic Stress Resulting in an Earthquake in Central Japan, 1984
Authors: Sugisaki Ryuichi , Sugiura Tutomu
Published: October 2006

Conspicuous changes in gas composition were observed at a fumarole and a mineral spring just before the occurrence of an inland earthquake (magnitude, 6.8) in central Japan in September 1984; the fumarole and spring were 9 and 50 kilometers, respectively, from the earthquake's epicenter. Deep-seated fluids emitted as a result of the compressional stress of the earth tide had been observed previously at this mineral spring and at a lava lake in Hawaii. By analogy, the gas anomaly observed before the earthquake in Japan probably resulted from deep-seated fluids being squeezed to the surface by the tectonic stress that caused the earthquake.
Methylene: A Paradigm for Computational Quantum Chemistry
Authors: Schaefer Henry F.
Published: October 2006

The year 1970 has been suggested as a starting date for the "third age of quantum chemistry," in which theory takes on not only qualitative but also quantitative value. In fact, each of the years 1960, 1970, 1972, and 1977 is of historical value in the unraveling of the structure and energetics of the CH
2
molecule, methylene. What took place for methylene, namely the establishment of credibility for theory, has subsequently taken place for many other molecules. Three important roles for quantitative theory are outlined: (i) theory precedes experiment; (ii) theory overturns experiment, as resolved by later experiments; and (iii) theory and experiment work together to gain insight that is afforded independently to neither. Several examples from each of the three classes are given.
Deciphering the Message in Protein Sequences: Tolerance to Amino Acid Substitutions
Authors: Bowie James U. , Reidhaar-Olson John F. , Lim Wendell A. , Sauer Robert T.
Published: October 2006

An amino acid sequence encodes a message that determines the shape and function of a protein. This message is highly degenerate in that many different sequences can code for proteins with essentially the same structure and activity. Comparison of different sequences with similar messages can reveal key features of the code and improve understanding of how a protein folds and how it performs its function.
Plasma Wave Observations at Comet Giacobini-Zinner
Authors: Scarf Frederick L. , Coroniti Ferdinand V. , Kennel Charles F. , Gurnett Donald A. , Ip Wing-Huen , Smith Edward J.
Published: October 2006

The plasma wave instrument on the International Cometary Explorer (ICE) detected bursts of strong ion acoustic waves almost continuously when the spacecraft was within 2 million kilometers of the nucleus of comet Giacobini-Zinner. Electromagnetic whistlers and low-level electron plasma oscillations were also observed in this vast region that appears to be associated with heavy ion pickup. As ICE came closer to the anticipated location of the bow shock, the electromagnetic and electrostatic wave levels increased significantly, but even in the midst of this turbulence the wave instrument detected structures with familiar bow shock characteristics that were well correlated with observations of localized electron heating phenomena. Just beyond the visible coma, broadband waves with amplitudes as high as any ever detected by the ICE plasma wave instrument were recorded. These waves may account for the significant electron heating observed in this region by the ICE plasma probe, and these observations of strong wave-particle interactions may provide answers to longstanding questions concerning ionization processes in the vicinity of the coma. Near closest approach, the plasma wave instrument detected broadband electrostatic noise and a changing pattern of weak electron plasma oscillations that yielded a density profile for the outer layers of the cold plasma tail. Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.
Laboratory Experiments in Economics: The Implications of Posted-Price Institutions
Authors: Plott Charles R.
Published: October 2006

In recent years a methodology for performing laboratory experiments in economics has been developed. The object of the methodology is to integrate clearly motivated but largely subjectively determined human decisions with the organizational features of markets. The nature of the incentive system and the use of market organization as an independent variable are described. Initial results of basic research that involved assessment of the effects of the "posted-price" institution demonstrated that the effect of the institution is to raise prices and lower market efficiency. The existence of such effects and the close proximity of the laboratory posted-price institution to the rate-posting institution required by the government in several industries has led to a series of policy-related experiments. The results have also led to more basic research efforts on seemingly unrelated topics.
The Space Shuttle Program: A Policy Failure?
Authors: Logsdon John M.
Published: October 2006

The 5 January 1972 announcement by President Richard Nixon that the United States would develop during the 1970's a new space transportation system—the space shuttle—has had fundamental impacts on the character of U.S. space activities. In retrospect, it can be argued that the shuttle design chosen was destined to fail to meet many of the policy objectives established for the system; the shuttle's problems in serving as the primary launch vehicle for the United States and in providing routine and cost-effective space transportation are in large part a result of the ways in which compromises were made in the 1971-72 period in order to gain White House and congressional approval to proceed with the program. The decision to develop a space shuttle is an example of a poor quality national commitment to a major technological undertaking.
Recent Earthquake Prediction Research in Japan
Authors: Mogi Kiyoo
Published: October 2006

Japan has experienced many major earthquake disasters in the past. Early in this century research began that was aimed at predicting the occurrence of earthquakes, and in 1965 an earthquake prediction program was started as a national project. In 1978 a program for constant monitoring and assessment was formally inaugurated with the goal of forecasting the major earthquake that is expected to occur in the near future in the Tokai district of central Honshu Island. The issue of predicting the anticipated Tokai earthquake is discussed in this article as well as the results of research on major recent earthquakes in Japan—the Izu earthquakes (1978 and 1980) and the Japan Sea earthquake (1983).
Deregulation: Causes and Consequences
Authors: Bailey Elizabeth E.
Published: October 2006

As a consequence of deregulation, there have been fundamental changes in the way transportation and communications firms are conducting business. Companies are finding that they must be driven by market opportunities and financial needs, not by regulatory considerations. Prices must be based on cost, operations must become more efficient, and consumer-oriented product niches must be found. Moreover, deregulation has added a new element in industrial dynamics, by fostering more relations between the various modes of transportation and by cross-fertilization in computer and telecommunication technology. All in all, a more competitive and innovative spirit emerges from deregulation.
Advent and Course of Pastoralism in the Kalahari
Authors: Denbow James R. , Wilmsen Edwin N.
Published: October 2006

It has long been thought that farming and herding were comparatively recent introductions into the Kalahari and that it has been a preserve of foraging "Bushmen" for thousands of years. Agropastoral Bantu-speakers were thought to have entered this region only within the last two centuries. However, fully developed pastoralism and metallurgy are now shown to have been established in the Kalahari from A.D. 500, with extensive grain agriculture and intracontinental trade added by A.D. 800. Archeological, linguistic, and historical evidence delineates the continuation of mixed economies in the region into the present. Consequences of this revised view for anthropological theory and for policy planning concerning contemporary Kalahari peoples are indicated.
Functional Domains and Upstream Activation Properties of Cloned Human TATA Binding Protein
Authors: Peterson Michael Gregory , Tanese Naoko , Pugh B. Franklin , Tjian Robert
Published: October 2006

The TATA binding protein, TFIID, plays a central role in the initiation of eukaryotic mRNA synthesis. Here, we present a human cDNA clone for this factor. Comparison of its predicted protein sequence with those from
Drosophila
and yeast reveals a highly conserved carboxyl-terminal 180 amino acids. By contrast, the amino-terminal region of TFIID has diverged in both sequence and length. A striking feature of the human protein is a stretch of 38 glutamine residues in the NH
2
-terminal region. Expression of human TFIID in both
Escherichia coli
and HeLa cells produces a protein that binds specifically to a TATA box and promotes basal transcription; the conserved COOH-terminal portion of the protein is sufficient for both of these activities. Recombinant TFIID forms a stable complex on a TATA box either alone or in combination with either of the general transcription factors, TFIIA or TFIIB. Full-length recombinant TFIID is able to support Sp1 activated transcription in a TFIID-depleted nuclear extract, while a deletion of the NH
2
-terminal half of the protein is not. These results indicate the importance of the NH
2
-terminal region for upstream activation functions and suggest that additional factors (co-activators) are required for mediating interactions with specific regulators.
Fabrics in Polar Ice Sheets: Development and Prediction
Authors: Alley Richard B.
Published: October 2006

Fabrics in polar ice sheets provide a record of deformational history and control the viscosity of ice during further deformation; they affect geophysical sensing of ice sheets and provide an accessible analogue to fabric development during deformation of other geological and engineering materials. A new synthesis of experimental and theoretical results shows that
c
-axis fabrics are quantitatively related to cumulative strain and stress state in ice sheets for the full range of likely flow patterns. Basal shear, divergent flow, and parallel flow cause
c
axes to rotate toward the vertical axis, whereas convergent flow causes
c
axes to rotate toward a vertical plane transverse to flow.
Subsidence in the Northeastern Nile Delta: Rapid Rates, Possible Causes, and Consequences
Authors: Stanley Daniel Jean
Published: October 2006

Holocene fluvial and marine deposits have accumulated in a graben-like structure on the northeastern margin of the Nile delta. This part of the delta, which includes Lake Manzala, Port Said, and the northern Suez Canal, has subsided rapidly at rates of up to 0.5 centimeter per year since about 7500 years ago. This subsidence has diverted at least four major distributaries of the Nile River into this region. The combined effects of continued subsidence and sea level rise may flood a large part of the northern delta plain by as much as 1 meter by the year 2100. The impact of continued subsidence, now occurring when sediment input along the coast has been sharply reduced because of the Aswan High Dam, is likely to be substantial, particularly in the Port Said area and as far inland as south of Lake Manzala.
The El Niño Cycle: A Natural Oscillator of the Pacific Ocean—Atmosphere System
Authors: Graham Nicholas E. , White Warren B.
Published: October 2006

Research conducted during the past decade has led to an understanding of many of the mechanisms responsible for the oceanic and atmospheric variability associated with the El Niño—Southern Oscillation (ENSO). However, the reason for one of the fundamental characteristics of this phenomena, its quasi-periodicity, has remained unclear. Recently available evidence from a number of sources now suggests that the ENSO "cycle" operates as a natural oscillator based on relatively simple couplings between the tropical atmospheric circulation, the dynamics of the warm upper layer of the tropical ocean, and sea surface temperatures in the eastern equatorial Pacific. This concept and recent field evidence supporting the natural coupled oscillator hypothesis are outlined.
Superconducting Bi-Ca-Sr-Cu-O Fibers Grown by the Laser-Heated Pedestal Growth Method
Authors: Feigelson R. S. , Gazit D. , Fork D. K. , Geballe T. H.
Published: October 2006

Superconducting fibers of several compositions including the nominal composition Bi
2
CaSrCu
2
O
8
have been grown by means of the laser-heated pedestal growth method. The influence of starting composition and growth conditions on structure and superconducting properties is discussed. The
a-b
planes of the material are parallel to the fiber axis (along the growth direction), providing the ideal condition for conduction along the copper-oxygen planes.
A New Laboratory Source of Ozone and Its Potential Atmospheric Implications
Authors: Slanger T. G. , Jusinski L. E. , Black G. , Gadd G. E.
Published: October 2006

Although 248-nanometer radiation falls 0.12 electron volt short of the energy needed to dissociate O
2
, large densities of ozone (O
3
) can be produced from unfocused 248-nanometer KrF excimer laser irradiation of pure O
2
. The process is initiated in some undefined manner, possibly through weak two-photon O
2
dissociation, which results in a small amount of O
3
being generated. As soon as any O
3
is present, it strongly absorbs the 248-nanometer radiation and dissociates to vibrationally excited ground state O
2
(among other products), with a quantum yield of 0.1 to 0.15. During the laser pulse, a portion of these molecules absorb a photon and dissociate, which results in the production of three oxygen atoms for one O
3
molecule destroyed. Recombination then converts these atoms to O
3
, and thus O
3
production in the system is autocatalytic. A deficiency exists in current models of O
3
photochemistry in the upper stratosphere and mesosphere, in that more O
3
is found than can be explained. A detailed analysis of the system as it applies to the upper atmosphere is not yet possible, but with reasonable assumptions about O
2
vibrational distributions resulting from O
3
photodissociation and about relaxation rates of vibrationally excited O
2
, a case can be made for the importance of including this mechanism in the models.
Solid-State Ice Volcanism on the Satellites of Uranus
Authors: Jankowski David G. , Squyres Steven W.
Published: October 2006

Voyager images of the uranian satellites Ariel and Miranda show flow features with morphologies indicating that ice has been extruded to the satellites' surfaces in the solid state. These images provide the first observational evidence for solid-state ice volcanism in the solar system. Topographic profiles have been measured across a number of flow features on Ariel. With a simple model of extrusion, spreading, and cooling of a viscous flow, the initial viscosity of the flow material is found to have been no more than about 10
16
poise, far lower than expected for H
2
O ice at the ambient surface temperatures in the uranian system. Sharply reduced viscosities may have resulted from incorporation of ices like NH
3
or CH
4
in the uranian satellites.
A Synchrotron X-ray Study of a Solid-Solid Phase Transition in a Two-Dimensional Crystal
Authors: Wolf Sharon Grayer , Landau Ehud M. , Lahav Meir , Leiserowitz Leslie , Deutsch Moshe , Kjaer Kristian , Als-Nielsen Jens
Published: October 2006

A measurement and interpretation on a molecular level of a phase transition in an ordered Langmuir monolayer is reported. The diagram of surface pressure (π) versus molecular area of a monolayer of chiral (
S
)-[CF
3
-(CF
2
)
9
-(CH
2
)
2
-OCO-CH
2
-CH
2
(NH
3
+
)CO
2
-
] over water shows a change in slope at about π
s
= 25 millinewtons per meter. Grazing-incidence x-ray diffraction and specular reflectivity measurements indicate a solid-solid phase transition at π
s
. The diffraction pattern at low pressures reveals two diffraction peaks of equal intensities, with lattice spacings
d
of 5.11 and 5.00 angstroms; these coalesce for π ≥ π
s
. Structural models that fit the diffraction data show that at π > π
s
the molecules pack in a two-dimensional crystal with the molecules aligned vertically. At π < π
s
there is a molecular tilt of 16° ± 7°. Independent x-ray reflectivity data yield a tilt of 26° ± 7°. Concomitant with the tilt, the diffraction data indicate a transition from a hexagonal to a distorted-hexagonal lattice. The hexagonal arrangement is favored because the -(CF
2
)
9
CF
3
moiety adopts a helical conformation. Compression to 70 millinewtons per meter yields a unit cell with increased crystallinity and a coherence length exceeding 1000 angstroms.
Input Management of Production Systems
Authors: Odum Eugene P.
Published: October 2006

Nonpoint sources of pollution, which are largely responsible for stressing regional and global life-supporting atmosphere, soil, and water, can only be reduced (and ultimately controlled) by input management that involves increasing the efficiency of production systems and reducing the inputs of environmentally damaging materials. Input management requires a major change, an about-face, in the approach to management of agriculture, power plants, and industries because the focus is on waste reduction and recycling rather than on waste disposal. For large-scale ecosystem-level situations a top-down hierarchical approach is suggested and illustrated by recent research in agroecology and landscape ecology.
Intermetallic Compounds for High-Temperature Structural Use
Authors: Taub A. I. , Fleischer R. L.
Published: October 2006

The next generation of efficient turbines and engines will require materials that can withstand operating temperatures approaching 2000°C. Intermetallic compounds with high melting temperatures are candidates for this application, but the obstacle of their limited ductility must first be overcome. Because the available data on these materials is limited, a survey of the effects of chemistry and crystal structure must be performed. With the use of melting temperature and density as figures of merit, the most likely candidates have been identified for preliminary screening.
A Diet-Induced Developmental Polymorphism in a Caterpillar
Authors: Greene Erick
Published: October 2006

Caterpillars of the spring brood of
Nemoria arizonaria
develop into mimics of the oak catkins upon which they feed. Caterpillars from the summer brood emerge after the catkins have fallen and they develop instead into mimics of oak twigs. This developmental polymorphism may be triggered by the concentration of defensive secondary compounds in the larval diet: all caterpillars raised on catkins, which are low in tannin, developed into catkin morphs; those raised on leaves, which are high in tannin, developed into twig morphs; most raised on artificial diets of catkins with elevated tannin concentrations developed into twig morphs.
Length-of-Day Variations Caused by El Niño-Southern Oscillation and Quasi-Biennial Oscillation
Authors: Chao B. Fong
Published: October 2006

Two prominent interannual atmospheric fluctuations, the El Niño-Southern Oscillation in the troposphere-ocean system and the Quasi-Biennial Oscillation in the equatorial stratosphere, account for most of the observed interannual length-of-day (LOD) variation from 1964 through 1987, with a relative contribution of about 2 to 1. Thus the atmosphere-LOD connection extends from seasonal and shorter periods to interannual periods up to about 10 years.