bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon-Mediated Organic Synthesis
Authors: Paquette Leo A.
Published: October 2006

Organic chemists have used the chemical properties of tetracovalent silicon in a remarkable variety of new synthetic transformations. In carbon-functional silanes, exceptional stabilization is provided to a carbocation center in the beta position when the carbon-silicon bond lies in plane. This phenomenon directs electrophilic attack to the silicon-substituted carbon in aryl-, vinyl-, and alkynylsilanes and to carbon-3 in allylsilanes. For different reasons, silicon also stabilizes a carbon-metal bond in the alpha position. Consequently, access to many silicon-containing organometallics is readily available. The exceptional strength of silicon-oxygen and silicon-fluorine bonds is yet another factor that controls the chemical reactivity of silicon reagents. In recent developments, preparative chemists have taken advantage of these properties in imaginative and useful ways.
Selenium in Reducing Waters
Authors: Cutter Gregory A.
Published: October 2006

The analysis of selenium species in reducing waters provides important insight into the element's biogeochemical cycle. The absence of selenate and selenite in reducing waters suggests that some removal mechanism could be operative, but the presence in these waters of about 1 nanomole per liter of dissolved organic selenide indicates that the regeneration of selenium in the form of organic species may be the dominant process. The data demonstrate that the regenerative and biogeochemical cycles of selenium are quite complex.
Polyamines and Plant Stress: Activation of Putrescine Biosynthesis by Osmotic Shock
Authors: Flores Hector E. , Galston Arthur W.
Published: October 2006

The putrescine content of oat leaf cells and protoplasts increases up to 60-fold within 6 hours of exposure to osmotic stress (0.4 to 0.6 molar sorbitol). Barley, corn, wheat, and wild oat leaves show a similar response. Increased arginine decarboxylase activity parallels the rise in putrescine, whereas ornithine decarboxylase remains unchanged. DL-α-Difluoromethylarginine, a specific irreversible inhibitor of arginine decarboxylase, prevents the stress-induced rise in increase in arginine decarboxylase activity and putrescine synthesis, indicating the preferential activation of this pathway.
Hyperkalemic Periodic Paralysis and the Adult Muscle Sodium Channel α-Subunit Gene
Authors: Fontaine Bertrand , Khurana Tejvir S. , Hoffman Eric P. , Bruns Gail A. P. , Haines Jonathan L. , Trofatter James A. , Hanson Mark P. , Rich Jaimie , McFarlane Heather , Yasek Diane McKenna , Romano Donna , Gusella James F. , Brown Robert H.
Published: October 2006

Hyperkalemic periodic paralysis (HYPP) is an autosomal dominant disorder characterized by episodes of muscle weakness due to depolarization of the muscle cell membrane associated with elevated serum potassium. Electrophysiological studies have implicated the adult muscle sodium channel. Here, portions of the adult muscle sodium channel α-subunit gene were cloned and mapped near the human growth hormone locus (
GH1
) on chromosome 17. In a large pedigree displaying HYPP with myotonia, these two loci showed tight linkage to the genetic defect with no recombinants detected. Thus, it is likely that the sodium channel α-subunit gene contains the HYPP mutation.
Associative Learning in Egglaying Site Selection by Apple Maggot Flies
Authors: Prokopy Ronald J. , Averill Anne L. , Cooley Sylvia S. , Roitberg Carol A.
Published: October 2006

Evidence is presented demonstrating that associative learning during oviposition in
Crataegus
or apple hosts can significantly influence the propensity of apple maggot flies to accept or reject these hosts in future encounters. The data suggest that within resource patches of a given host type there may be an enhancement of foraging efficiency.
Sedimentation Field Flow Fractionation: Applications
Authors: Kirkland J. J. , Yau W. W.
Published: October 2006

Sedimentation field flow fractionation is a powerful, new, high-resolution separation method for a wide variety of colloids, micelles, particulates, and soluble macromolecules of biological interest. Advances in instrumentation allow sedimentation field flow fractionation operation with rotor speeds up to 32,000 revolutions per minute (∼85,000 gravities), which permits separation of materials as small as 5 × 10
5
molecular weight, depending on sample density. Compared to conventional centrifugation techniques, the gentle, mass-separating sedimentation field flow fractionation method is capable of higher resolution in shorter times.
Experimental Induction of Altered Nonmicrofibrillar Cellulose
Authors: Brown R. Malcolm , Haigler Candace , Cooper Kay
Published: October 2006

Cellulose produced by
Acetobacter xylinum
was experimentally modified during its biosynthesis. In the presence of fluorescent brightening agents, such as Calcofluor White M2R or Tinopal LPW, nonmicrofibrillar sheets of cellulose were synthesized by the bacteria. These sheets could then be converted to fibrils by washing with distilled water. Possible mechanisms for these modifications of cellulose assembly are discussed.
Control of the Interferon-Induced 68-Kilodalton Protein Kinase by the HIV-1
tat
Gene Product
Authors: Roy Sophie , Katze Michael G. , Parkin Neil T. , Edery Isaac , Hovanessian Ara G. , Sonenberg Nahum
Published: October 2006

The
tat
-responsive region (TAR) of the human immunodeficiency virus-1 (HIV-1) exhibits a trans-inhibitory effect on translation in vitro by activating the interferon-induced 68-kilodalton protein kinase (p68 kinase). Productive infection by HIV-1 was shown to result in a significant decrease in the amount of cellular p68 kinase. The steady-state amount of p68 kinase was also reduced in interferon-treated HeLa cell lines stably expressing
tat
, as compared to the amount of the kinase in interferon-treated control HeLa cells. Thus, the potential translational inhibitory effects of the TAR RNA region mediated by activation of p68 kinase may be downregulated by
tat
during productive HIV-1 infection.
Some Marine Ecological Phenomena: Chemical Basis and Biomedical Potential
Authors: Scheuer Paul J.
Published: October 2006

Analysis of secondary metabolites derived from marine organisms has revealed a broad spectrum of novel molecular architecture. The function of these compounds in their natural habitat is linked to various aspects of species survival, and the compounds have also served as characteristic chemical markers through successive trophic levels. Fundamental questions concerning the locus of synthesis in complex and intricate assemblies of plants and animals and the pathways of biosynthesis are beginning to be answered. It is now apparent that the marine environment gives rise to some distinctive chemistry, which is generated along characteristic pathways. Some of the newly described compounds have already become valuable tools in biomedicine.
Clay Mineralogy of the Cretaceous-Tertiary Boundary Clay
Authors: Rampino Michael R. , Reynolds Robert C.
Published: October 2006

Analyses of the clay mineralogy of samples from the Cretaceous-Tertiary boundary layer at four localities show that the boundary clay is neither mineralogically exotic nor distinct from locally derived clays above and below the boundary. The significant ejecta component in the clay that is predicted by the asteroid-impact scenario was not detected.
Measurement of Ultrafast Phenomena in the Femtosecond Time Domain
Authors: Shank C. V.
Published: October 2006

Considerable progress has taken place in the generation and application of ultrashort optical pulses. The methods and techniques for extending time-resolved measurements into the femtosecond (10
–15
second) time domain are described, and recent applications and fertile areas for investigation with femtosecond pulses are discussed.
Zeolite Molecular Sieve 4A: Anomalous Compressibility and Volume Discontinuities at High Pressure
Authors: Hazen R. M.
Published: October 2006

Unit cell parameters of synthetic zeolite 4A were measured at several pressures to 40 kilobars with both water and an alcohol mixture as hydrostatic pressure media. Compression in water was normal, with no observed phase transitions. Compression in alcohols was twice as great as in water, and three volume discontinuities were observed. These volume changes in alcohol were rapid with increasing pressure but sluggish in reverse. High-pressure "phases," all of which are dimensionally cubic, are progressively more compressible at high pressure. These unusual high-pressure phenomena, which indicate significant interactions between zeolite 4A and the hydrostatic media, are consistent with differences in zeolite adsorption of water and alcohols.
Dorid Nudibranch Elaborates Its Own Chemical Defense
Authors: Cimino Guido , De Rosa Salvatore , De Stefano Salvatore , Sodano Guido , Villani Guido
Published: October 2006

A biosynthetic experiment with mevalonic acid labeled with carbon-14 showed that the nudibranc
Dendrodoris limbata
elaborates polygodial, a sesquiterpenoid dialdehyde stored in the mantle, which constitutes its chemical defense against predators. Previously described nudibranchs drew defensive chemicals from their preys.
East Pacific Rise Near 13°N: Geology of New Hydrothermal Fields
Authors: Hekinian R. , Fevrier M. , Avedik F. , Cambon P. , Charlou J. L. , Needham H. D. , Raillard J. , Boulegue J. , Merlivat L. , Moinet A. , Manganini S. , Lange J.
Published: October 2006

Abundant massive sulfide deposits are present at the crest of the East Pacific Rise near 13° North, where the opening rate is about 12 centimeters per year. Large manganese and helium-3 anomalies in seawater samples, evidence of intense present-day activity of hydrothermal springs, indicate that sulfides are still being produced along this segment of the rise. Massive sulfides also occur on adjacent off-axis seamounts.
A cDNA for a Protein That Interacts with the Human Immunodeficiency Virus Tat Transactivator
Authors: Nelbock Peter , Dillon Patrick J. , Perkins Ann , Rosen Craig A.
Published: October 2006

The human immunodeficiency virus (HIV)
tat
protein (Tat) is a positive regulator of virus gene expression and replication. Biotinylated Tat was used as a probe to screen a λgt11 fusion protein library, and a complementary DNA encoding a protein that interacts with Tat was cloned. Expression of this protein, designated TBP-1 (for Tat binding protein-1), was observed in a variety of cell lines, with expression being highest in human cells. TBP-1 was localized predominantly in the nucleus, which is consistent with the nuclear localization of Tat. In cotransfection experiments, expression of TBP-1 was able to specifically suppress Tat-mediated transactivation. The strategy described may be useful for direct identification and cloning of genes encoding proteins that associate with other proteins to modulate their activity in a positive or negative fashion.
A Direct and Active Influence of Gravity on the Behavior of a Marine Invertebrate Larva
Authors: Pires Anthony , Woollacott Robert M.
Published: October 2006

Larvae of the bryozoans
Bugula neritina
and
Bugula stolonifera
exhibit an apparent negative geotaxis under conditions of darkness and constant temperature. This behavior cannot be accounted for by buoyancy since the larvae are negatively bouyant, nor is it a consequence of gradients in the partial pressures of dissolved gases since the response occurs under conditions where the gradient is reversed or when experiments are conducted in chambers with interfaces of only glass and water. Pressure bomb experiments indicate that the behavior is not a barokinesis. Centrifuge experiments, however, showed that larvae of
Bugula stolonifera
orient directly and actively to gravity, while those of
Bugula neritina
have some other measure of geographic up. Since bryozoan larvae lack statocysts, the sensory apparatus mediating the gravity response in
Bugula stolonifera
is still unknown.
Parthenogenesis in the Endemic Australian Lizard
Heteronotia binoei
(Gekkonidae)
Authors: MORITZ C.
Published: October 2006

Chromosome variation in the gekkonid lizard
Heteronotia binoei
reveals that this endemic Australian vertebrate reproduces by parthenogenesis. Triploid parthenogenetic females are distributed throughout central and western Australia and are all heterozygotes for one or more pericentric inversions that also distinguish the extant bisexual diploid cytotypes. These data on karyotype provide strong evidence that the various clones have arisen through multiple hybridization events between bisexual ancestors.
The Start of Sulfur Oxidation in Continental Environments: About 2.2 × 10
9
Years Ago
Authors: Hattori Keiko , Krouse H. Roy , Campbell Finley A.
Published: October 2006

Whereas dissimilatory sulfate reduction in marine environments has been postulated on the basis of sulfur isotope abundances as commencing before about 2.8 × 10
9
years ago, data from the Huronian Supergroup, Canada, suggest that oxidative-reductive reactions involving sulfur in continental environments were not significant before about 2.2 × 10
9
years ago.
Cerebral Cortices of East African Early Hominids
Authors: Falk Dean
Published: October 2006

An endocast of the frontal lobe of a reconstructed skull, which is approximately 2 million years old, from the Koobi Fora region of Kenya appears to represent the oldest human-like cortical sulcal pattern in the fossil record, while the endocast from another skull from the same region produces an endocast that appears apelike in its frontal lobe and similar to endocasts from earlier South African australopithecines. New analysis of paleoanatomical evidence thus indicates that at least two taxa of early hominids coexisted in East Africa.
Petrologic Monitoring of 1981 and 1982 Eruptive Products from Mount St. Helens
Authors: Cashman Katharine V. , Taggart Joseph E.
Published: October 2006

New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.
Deep Earthquakes Beneath Mount St. Helens: Evidence for Magmatic Gas Transport?
Authors: Weaver Craig S. , Zollweg James E. , Malone Stephen D.
Published: October 2006

Small-magnitude earthquakes began beneath Mount St. Helens 40 days before the eruption of 20 March 1982. Unlike earlier preeruption seismicity for this volcano, which had been limited to shallow events (less than 3 kilometers), many of these earthquakes were deep (between 5 and 11 kilometers). The location of these preeruptive events at such depth indicates that a larger volume of the volcanic system was affected prior to the 20 March eruption than prior to any of the earlier dome-building eruptions. The depth-time relation between the deep earthquakes and the explosive onset of the eruption is compatible with the upward migration of magmatic gas released from a separate deep reservoir.
Nestmate and Kin Recognition in Interspecific Mixed Colonies of Ants
Authors: Carlin Norman F. , Hölldobler Bert
Published: October 2006

Recognition of nestmates and discrimination against aliens is the rule in the social insects. The principal mechanism of nestmate recognition in carpenter ants (
Camponotus
) appears to be odor labels or "discriminators" that originate from the queen and are distributed among, and learned by, all adult colony members. The acquired odor labels are sufficiently powerful to produce indiscriminate acceptance among workers of different species raised together in artificially mixed colonies and rejection of genetic sisters reared by different heterospecific queens.
Mesozoic Mammals from Arizona: New Evidence on Mammalian Evolution
Authors: Jenkins Farish A. , Crompton A. W. , Downs William R.
Published: October 2006

Knowledge of early mammalian evolution has been based on Old World Late Triassic-Early Jurassic faunas. The discovery of mammalian fossils of approximately equivalent age in the Kayenta Formation of northeastern Arizona gives evidence of greater diversity than known previously. A new taxon documents the development of an angular region of the jaw as a neomorphic process, and represents an intermediate stage in the origin of mammalian jaw musculature.
Microbial Transformation of Sulfate in Forest Soils
Authors: Swank Wayne T. , Fitzgerald John W. , Ash Jaru T.
Published: October 2006

Incubation of forest soils containing sulfate labeled with sulfur-35 showed rapid conversion of the added sulfate to organic sulfur forms by microbial populations. Activity rates were highest in the forest floor, but significant activity was observed throughout the soil profile. The annual potential sulfur incorporation for forest floor and soil combined is estimated to be 30 kilograms per hectare. The metabolism of inorganic sulfate to organic forms can be a major process in the sulfur cycle, influencing sulfate accumulation and mobility in forest ecosystems.
Antiquity of the Continental Slope Along the Middle-Atlantic Margin of the United States
Authors: Prior D. B. , Coleman J. M. , Doyle E. H.
Published: October 2006

A detailed high-resolution geophysical study of part of the continental slope along the mid-Atlantic margin of the United States indicates that it is an ancient, relict landscape largely unmodified by modern slope processes. The slope morphology is heavily influenced by bedrock outcrops, including joints and bedding planes, rather than by any single degradational process. A pelagic drape averaging 3 to 5 meters in thickness blankets the slope. Carbon-14 dates from eight drop cores show that the drape was deposited in late Pleistocene and Holocene times. The Holocene part of the drape, comprising the uppermost 1 meter, was deposited at a continuous rate of 10 centimeters per 1000 years. Most features on the slope predate the drape cover.
The Frequency of Meteorite Falls on the Earth
Authors: Halliday Ian , Blackwell Alan T. , Griffin Arthur A.
Published: October 2006

Photographic observations from a network of 60 cameras in western Canada are used to derive the influx rate of meteorites on the earth's surface, the first time instrumental data have been used for this purpose. Forty-three observed events are believed to have dropped between 0.1 and 12 kilograms of meteorites each. The flux values are corrected for a minor latitude effect and agree with earlier estimates near 10 kilograms but vary more slowly with mass. Eight events per year drop at least 1 kilogram of meteorites in an area of 10
6
square kilometers.
Voltage-Dependent Calcium and Potassium Ion Conductances: A Contingency Mechanism for an Associative Learning Model
Authors: Alkon Daniel L.
Published: October 2006

Persistent light-induced depolarization results from Ca
2+
influx across a photoreceptor membrane. The marked dependence on potential of this Ca
2+
influx and a Ca
2+
-dependent K
+
efflux accounts for enhancement of the light-induced depolarization when light is paired with rotation. A positive feedback cycle between light-induced depolarization and synaptic depolarization due to stimulus pairing can explain long-lasting behavioral changes produced by associative training but not control paradigms. The sensitivity of this Ca
2+
influx to intracellular levels of adenosine 3′,5′-monophosphate suggests biochemical steps for this model of associative learning.
Turbidity Currents: Monitoring Their Occurrence and Movement with a Three-Dimensional Sensor Network
Authors: Weirich Frank H.
Published: October 2006

Detailed field data on the occurrence, flow pattern, and internal dynamics of both surge and continuous turbidity currents have been obtained with a three-dimensional array of optical and thermal sensors. The array, operated in a glacial lake in southeastern British Columbia, collected detailed information on the character of surge events with velocities reaching 110 centimeters per second and continuous underflows exceeding 90 centimeters per second. The findings (i) indicate that such currents are frequent events, occurring with density differences between the incoming stream water and the lake water as low as 0.19 kilogram per cubic meter of water; (ii) document the differences in the initiation and internal characteristics of the continuous and surge events; and (iii) support the concept of erosion by turbidity currents.
Seismic Potential Revealed by Surface Folding: 1983 Coalinga, California, Earthquake
Authors: Stein Ross S. , King Geoffrey C. P.
Published: October 2006

The 2 May 1983 Coalinga, California, earthquake (magnitude 6.5) failed to rupture through surface deposits and, instead, elastically folded the top few kilometers of the crust. The subsurface rate of fault slip and the earthquake repeat time are estimated from seismic, geodetic, and geologic data. Three larger earthquakes (up to magnitude 7.5) during the past 20 years are also shown to have struck on reverse faults concealed beneath active folds.
Predator-Induced Defense in a Marine Bryozoan
Authors: Harvell C. Drew
Published: October 2006

Laboratory experiments showed that predation by both trophically specialized and generalized nudibranch species triggers rapid induction of defensive spines in the bryozoan
Membranipora membranacea
. Spines effectively control the pattern and extent of intracolony mortality caused by nudibranch predation. Previously found only in plants, rotifers, and cladocerans, consumer-induced defenses may be widespread among clone-forming or colonial taxa exposed to nonfatal encounters with predators.
Sinking of Volcanic Ash in Uncompacted Sediment in Williams Lake, Washington
Authors: Anderson Roger Y. , Nuhfer Edward B. , Dean Walter E.
Published: October 2006

Volcanic ash from the eruption of Mount St. Helens on 18 May 1980 fell into Williams Lake in eastern Washington and was temporarily suspended at the sediment-water interface. After several months of compaction, the ash layer broke up and sank into lower density uncompacted lake sediment. Stratigraphic time displacements of several hundred years and a failure to recognize discontinuous ash layers in sediment cores are possible consequences of this process.
How Big Is the Universe of Exons?
Authors: Dorit Robert L. , Schoenbach Lloyd , Gilbert Walter
Published: October 2006

If genes have been assembled from exon subunits, the frequency with which exons are reused leads to an estimate of the size of the underlying exon universe. An exon database was constructed from available protein sequences, and homologous exons were identified on the basis of amino acid identity; statistically significant matches were determined by Monte Carlo methods. It is estimated that only 1000 to 7000 exons were needed to construct all proteins.
Io's Sodium Cloud
Authors: Goldberg Bruce A. , Garneau Glenn W. , LaVoie Susan K.
Published: October 2006

The first two-dimensional images of the source region of Io's neutral sodium cloud have been acquired by ground-based observation. Observed asymmetries in its spatial brightness distribution provide new evidence that the cloud is supplied by sodium that is ejected nonisotropically from Io or its atmosphere. Complementary, high-time-resolution, calibrated image sequences that give the first comprehensive picture of the variations of the fainter regions of the cloud extending more than 10
5
kilometers from Io were also obtained. These data demonstrate that the cloud exhibits a persistent systematic behavior coupled with Io's orbital position, a distinct "east-west orbital asymmetry," a variety of spatial morphologies, and true temporal changes. The geometric stability of the sodium source is also indicated. Isolation of the cloud's temporal changes constitutes an important milestone toward its utilization as a long-term probe of Io and the inner Jovian magnetosphere.
Laser-Induced Fluorescence and Bonding of Metal Dimers
Authors: Bondbey V. E.
Published: October 2006

This article describes a technique for the spectroscopic of metal clusters and intermetallic compounds. First, metallic samples are vaporized by a pulsed YAG (yttrium-aluminum garnet) laser, and then the gaseous products are excited with a pulsed-dye laser until they fluoresce. A time-resolved, fluorescence spectrum is then measured by the product. The application of this technique to the study of metal dimers is reviewed, with emphasis on recent results from Be
2
and Cr
2
. Studies of such species often yield insights into the chemistry of metals and metal-metal bonding.
Hydrothermal Vent Animals: Distribution and Biology
Authors: Grassle J. Frederick
Published: October 2006

Hydrothermal vent communities characterized by large clams, mussels, and vestimentiferan worms thrive on chemosynthetic microbial production. There are similarities in the animal distributions at vent communities from 20°S to 46°N on the Mid-Ocean Ridge in the Pacific Ocean and at cold sulfide seeps in the Gulf of Mexico. Vent communities, consisting of at least 16 previously unknown families of invertebrates, are at least 200 million years old. Since the life-span of a vent is only tens of years, the species survive by rapid growth and widespread dispersal of larvae with the subsequent colonization of new vents.
Seismic-Reflection Signature of Cretaceous Continental Breakup on the Wilkes Land Margin, Antarctica
Authors: Eittreim Stephen L. , Hampton Monty A. , Childs Jonathan R.
Published: October 2006

The passive (rifted) continental margin of Wilkes Land, Antarctica, is characterized on seismic reflection records by (i) in the south, a block-faulted sequence of highly stratified continental beds overlain by two distinct unconformities; (ii) a transitional, greatly thinned continental crust overlain by material interpreted to be flood basalt; and (iii) in the north, oceanic crust with a boundary ridge at its edge. The Mohorovičić discontinuity can be followed across the continent-ocean boundary and shows a progressive thinning of continental crust to a minimum of 2.5 kilometers at its northern edge.
Influence of Solar Heating and Precipitation Scavenging on the Simulated Lifetime of Post—Nuclear War Smoke
Authors: Malone Robert C. , Auer Lawrence H. , Glatzmaier Gary A. , Wood Michael C. , Toon Owen B.
Published: October 2006

The behavior of smoke injected into the atmosphere by massive fires that might follow a nuclear war was simulated. Studies with a three-dimensional global atmospheric circulation model showed that heating of the smoke by sunlight would be important and might produce several effects that would decrease the efficiency with which precipitation removes smoke from the atmosphere. The heating gives rise to vertical motions that carry smoke well above the original injection height. Heating of the smoke also causes the tropopause, which is initially above the smoke, to reform below the heated smoke layer. Smoke above the tropopause is physically isolated from precipitation below. Consequently, the atmospheric residence time of the remaining smoke is greatly increased over the prescribed residence times used in previous models of nuclear winter.
Studies of Unusual Simple Molecules by Neutralization-Reionization Mass Spectrometry
Authors: McLafferty Fred W.
Published: October 2006

Reactive or unstable molecules are key intermediates in many important reactions, but can be difficult to prepare for experimental studies. Species with missing (:CH-OH) or extra (H
3
) substituents can often be formed conveniently in the gas phase by neutralizing a beam of a more stable ionic counterpart (CH = O
+
H, H
3
+
). Reionization of the neutral after ∼ 10
-6
seconds tests its stability, whereas its unimolecular chemistry can be probed by preparing it with different amounts of internal energy. The resulting neutral products are reionized and mass analyzed. Isomers are then characterized by ion dissociation and a third mass-analysis step. Many unusual molecules have been characterized with this technique, which can also be used to probe complex unimolecular chemistry, such as that of cyclobutadiene and ethylene oxide.
1981N1: A Neptune Arc?
Authors: Hubbard W. B.
Published: October 2006

An object in the vicinity of Neptune detected in 1981 by simultaneous stellar occultation measurements at observatories near Tucson, Arizona, was interpreted as a new Neptune satellite. A reinterpretation suggests that it may have instead been a Neptune arc similar to one observed in 1984. The 1981 object, however, did not occult the star during simultaneous observations at Flagstaff, Arizona. This result constrains possible arc geometries.
Inertial Confinement Fusion with Light Ion Beams
Authors: VanDevender J. Pace , Cook Donald L.
Published: October 2006

The Particle Beam Fusion Accelerator II (PBFA II) is presently under construction and is the only existing facility with the potential of igniting thermonuclear fuel in the laboratory. The accelerator will generate up to 5 megamperes of lithium ions at 30 million electron volts and will focus them onto an inertial confinement fusion (ICF) target after beam production and focusing have been optimized. Since its inception, the light ion approach to ICF has been considered the one that combines low cost, high risk, and high payoff. The beams are of such high density that their self-generated electric and magnetic fields were thought to prohibit high focal intensities. Recent advances in beam production and focusing demonstrate that these self-forces can be controlled to the degree required for ignition, break-even, and high gain experiments. ICF has been pursued primarily for its potential military applications. However, the high efficiency and cost-effectiveness of the light ion approach enhance its potential for commercial energy application as well.
Temperature Regulation of Bacterial Activity During the Spring Bloom in Newfoundland Coastal Waters
Authors: Pomeroy Lawrence R. , Deibel Don
Published: October 2006

While the spring phytoplankton bloom in Newfoundland coastal waters is in progress during April and May, at water temperatures between -1° and +2°C, bacterial growth and respiratory rates remain low. Microbial community respiration is not measurable at -0.2°C. Particulate materials that would be utilized by microorganisms in 2 to 3 days at 20° to 25°C require 11 days at 4°C and 18 days at -0.2°C. Thus, photosynthesis is active but microbial utilization of the products is suppressed. High secondary production in cold water may result from the low rate of microbial decomposition, enabling herbivores to utilize much of the primary production.
Eclogites, Pyroxene Geotherm, and Layered Mantle Convection
Authors: Basu Asish R. , Ongley Jennifer S. , MacGregor Ian D.
Published: October 2006

Temperatures of equilibration for the majority (81 percent) of the eclogite xenoliths of the Roberts Victor kimberlite pipe in South Africa range between 1000° and 1250°C, falling essentially on the gap of the lower limb of the subcontinental inflected geotherm derived from garnet peridotite xenoliths. In view of the Archean age (>2.6 × 10
9
years) of these eclogites and their stratigraphic position on the geotherm, it is proposed that the inflected part of the geotherm represents the convective boundary layer beneath the conductive lid of the lithospheric plate. The gradient of 8 Celsius degrees per kilometer for the inflection is characteristic of a double thermal boundary layer and suggests layered convection rather than whole mantle convection for the earth.
NMR Studies of Simple Molecules on Metal Surfaces
Authors: Wang Po-Kang , Ansermet Jean-Philippe , Rudaz Serge L. , Wang Zhiyue , Shore Susan , Slichter Charles P. , Sinfelt J. H.
Published: October 2006

In recent years, improvements in the sensitivity of nuclear magnetic resonance have made it possible to detect progressively smaller numbers of nuclei. Experiments and studies previously thought to be impractical can now be undertaken, for example, the study of phenomena at surfaces. Nuclear magnetic resonance has been applied to study simple molecules (carbon monoxide, acetylene, and ethylene) adsorbed on metal surfaces (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metals, in the form of clusters 10 to 50 angstroms in diameter, supported on alumina, are typical of real catalysts. The experiments provide information about the bonding of the molecules to the metal, the structures the molecules assume after adsorption, the motion of molecules on the surface, the breakup of molecules induced by heating, and the products of such breakup.
A Single Genetic Unit Specifies Two Transposition Functions in the Maize Element
Activator
Authors: Dooner Hugo , English James , Ralston Edward , Weck Edward
Published: October 2006

The self-mobile maize transposable element
Ac (Activator)
displays two
trans
-acting genetic functions: it induces transposition of the element
Ds (Dissociation)
but, as its dosage is increased, it also inhibits transposition. Previous work has shown that the 4563 base pair (bp)—long
Ac
element contains three open reading frames (ORF's) and that a deletion in ORF 1 in
wx-m9(Ds)
, a
Ds
derivative from
Ac
isolated at the
wx
(
waxy
) locus, results in loss of transposition. The
Ds
element in the
bronze
allele
bz-m2(DI)
is shown to have arisen from
Ac
by a 1312-bp deletion that is located almost entirely within ORF 2 and does not affect ORF 1. The
Ds
elements in
wx-m9(Ds)
and
bz-m2(DI),
defective in ORF 1 and ORF 2, respectively, do not complement genetically to restore the transposition function of
Ac;
therefore, this function must be specified jointly by ORF's 1 and 2. Furthermore, since
bz-m2(DI)
does not contribute to
Ac'
s inhibitory dosage effect, both
Ac
properties result from the expression of the same genetic functional unit.
Oblique Impact: A Process for Obtaining Meteorite Samples from Other Planets
Authors: O'Keefe John D. , Ahrens Thomas J.
Published: October 2006

Cratering flow calculations for a series of oblique to normal (10° to 90°) impacts of silicate projectiles onto a silicate halfspace were carried out to determine whether or not the gas produced upon shock-vaporizing both projectile and target material would form a downstream jet that could entrain and propel SNC meteorites from the Martian surface. The difficult constraints that the impact origin hypothesis for SNC meteorites has to satisfy are that these meteorites are lightly to moderately shocked and yet have been accelerated to speeds in excess of the Martian escape velocity (more than 5 kilometers per second). Two-dimensional finite difference calculations were performed that show that at highly probable impact velocities (7.5 kilometers per second), vapor plume jets are produced at oblique impact angles of 25° to 60° and have speeds as great as 20 kilometers per second. These plumes flow nearly parallel to the planetary surface. It is shown that upon impact of projectiles having radii of 0.1 to 1 kilometer, the resulting vapor jets have densities of 0.1 to 1 gram per cubic centimeter. These jets can entrain Martian surface rocks and accelerate them to velocities greater than 5 kilometers per second. This mechanism may launch SNC meteorites to earth.
Characterization of Compounds That Induce Symbiosis Between Sea Anemone and Anemone Fish
Authors: Murata Michio , Miyagawa-Kohshima Kazuko , Nakanishi Koji , Naya Yoko
Published: October 2006

The species-specific partnership between the sea anemone and anemone fish in many parts of the Indo-Pacific region is a well-known phenomenon. Chemicals secreted by the sea anemone to elicit symbiotic behavior of the fish have been studied for two host-guest pairs,
Radianthus kuekenthali
(sea anemone)—
Amphiprion perideraion
(anemone fish) and
Stoichactis kenti-A. ocellaris.
A new pyridinium compound, amphikuemin, which induces characteristic attracted swimming (toward the chemical stimulus) in
A. perideraion
, has been isolated from
R. kuekenthali
and characterized. Several other chemicals that elicit characteristic symbiotic movements have also been identified.
A Structural Basis for Hering's Law: Projections to Extraocular Motoneurons
Authors: Moschovakis Adonis K. , Scudder Charles A. , Highstein Steven M.
Published: October 2006

Conjugate eye movements are executed through the concurrent activation of several muscles in both eyes. The neural mechanisms that underlie such synergistic muscle activations have been a matter of considerable experimentation and debate. In order to investigate this issue, the projections of a class of primate premotoneuronal cells were studied, namely, the vertical medium-lead burst neurons (VMLBs), which drive vertical rapid eye movements. Axons of upward VMLBs ramify bilaterally within motoneuron pools that supply the superior rectus and inferior oblique muscles of both eyes. Axons of downward VMLBs ramify ipsilaterally in the inferior rectus portion of the oculomotor nucleus and in the trochlear nucleus. Thus, VMLBs can drive vertical motoneuron pools of both eyes during conjugate vertical rapid eye movements; these data support Hering's law.
Impending United States Energy Crisis
Authors: Hirsch Robert L.
Published: October 2006

The U.S. oil and gas industry has been dramatically weakened by the recent oil price collapse. Domestic drilling activity reached a new post-World War II low during the summer of 1986. Given a weak, unstable oil price outlook, U.S. capability will continue to deteriorate. In the last year U.S. imports of foreign oil have risen significantly, and if market forces alone dominate, U.S. dependence is expected to rise from 32% in 1983 to the 50 to 70% level in the not-too-distant future. The 1973 oil embargo and the subsequent attempts to improve U.S. energy security vividly demonstrated the huge costs and long periods of time required to change our energy system. These facts, coupled with the nation's generally short-term orientation, suggest a strong likelihood of a new U.S. energy crisis in the early to middle 1990s.
Pheromone Components and Active Spaces: What Do Moths Smell and Where Do They Smell It?
Authors: Linn C. E. , Campbell M. G. , Roelofs W. L.
Published: October 2006

The pheromone-mediated flight behavior of male Oriental fruit moths was observed in the field to test the hypothesis that male activation far downwind of a female is initiated by the major, or most abundant, component of the pheromone blend. Males responded at significantly greater distances to the three-component pheromone blend produced by females than to the major component alone or to either binary mixture containing the major component and one minor component. These results support the alternative hypothesis that the active space of a multicomponent pheromone is a function of male perception of the female-released blend of components, rather than of the major component alone, and that so-called minor components have a greater impact on male behavior farther downwind of a female than previously thought.
Transgenic Plants as Tools to Study the Molecular Organization of Plant Genes
Authors: St. Schell Jozef
Published: October 2006

Transgenic plants are generated in nature by
Agrobacterium tumefaciens
, a pathogen that produces disease through the transfer of some of its own DNA into susceptible plants. The genes are carried on a plasmid. Much has been learned about how the plasmid is transferred, how the plasmid-borne genes are organized, regulated, and expressed, and how the bacteria's pathogenic effects are produced. The
A. tumefaciens
plasmid has been manipulated for use as a general vector for the transfer of specific segments of foreign DNA of interest (from plants and other sources) into plants; the activities of various genes and their regulation by enhancer and silencer sequences have been assessed. Future uses of the vector (or others like it that have different host ranges) by the agriculture industry are expected to aid in moving into vulnerable plants specific genes that will protect them from such killers as nonselective herbicides, insects, and viruses.
Migration and Western Europe: The Old World Turning New
Authors: Therborn Göran
Published: October 2006

The 1960s meant a historical turn of Western Europe, becoming an immigration area. Net immigration has been concentrated to some of the prosperous Western European countries and has been mainly determined by the demand of their particular national labor regimes. The size of alien employment has been very differently affected by the 1973 crisis, but a multiethnical society will remain a novel feature of most Western European countries. Political abdication from full employment and technological change makes a ghetto of un(der)employment a likely prospect of a large part of the second generation of recent immigrants into Western Europe.
The Recent Decline of Unionization in the United States
Authors: Farber Henry S.
Published: October 2006

The dramatic decline in unionization during the last decade is investigated with the use of survey data from 1977 and 1984. First, it is found that only a small fraction of the decline in unionization can be accounted for by shifts in labor force structure. Second, there has been a substantial drop in demand for union representation among nonunion workers that can be accounted for by an increase in the job satisfaction of nonunion workers and a decrease in nonunion workers' reports that unions improve wages and working conditions. Finally, there has been a substantial increase in employer resistance to unionization that is likely to have made it more difficult for unions to organize even those workers who desire union representation. Increased foreign and increased nonunion domestic competition (particularly in deregulated industries) may be key underlying causes of these changes.
Gas-Phase Polymerization: Ultraslow Chemistry
Authors: Reiss Howard
Published: October 2006

The mechanism of formation of polymer molecules in the gas phase is difficult to study because the involatile polymers tend to condense out of that phase. However, new techniques, involving the use of cloud chambers, have enabled workers to use the nucleation of liquid drops in supersaturated monomer vapors to detect single polymer molecules and therefore to work with so few simultaneously growing polymers that aggregation and condensation are avoided. Chain polymerization in which the chain carriers are either radicals or ions can therefore be studied in the vapor. Furthermore, the ability to work with such small concentrations of growing polymeric radicals, for example, makes it possible to avoid encounters between them that lead to recombination and the formation of "dead" polymers that are incapable of further growth. Many aspects of gas-phase polymerization can be studied including, besides radical and ion chains, ring-opening polymerization, initiation, radiation-induced polymerization, and especially "ultraslow" chemistry.
New Asymptotics for Old Wave Equations
Authors: Klauder John R.
Published: October 2006

Wave equations govern the propagation of acoustical or optical fields in diverse physical settings of interest to oceanographers, geologists, atmospheric scientists, among others. For wavelengths much smaller than all other length scales in the system the wave equation solution is generally expressed as a superposition of waveforms, each of which is determined by properties of the rays of geometrical acoustics or optics. Typically such solutions are accurate except in the vicinity of one or another caustic surface such as those defined as a surface across which a jump in the number of rays tracing through each point occurs. When numerous caustic surfaces exist, which is the generic situation, standard asymptotic solutions prove unsuitable. In this report a new asymptotic expression that overcomes deficiencies in previous approximations is introduced and characterized in an elementary way.
Inhibition of Leishmanias But Not Host Macrophages by the Antitubulin Herbicide Trifluralin
Authors: Chan Marion Man-Ying , Fong Dunne
Published: October 2006

The dinitroaniline herbicide trifluralin (α, α, α-trifluoro-2,6-dinitro-
N,N
-dipropyl-
p
-toluidine), at micromolar concentrations, selectively inhibited both proliferation and differentiation of the parasitic protozoan
Leishmania mexicana amazonensis
. In vitro, radioactive trifluralin showed specific binding to leishmania tubulin but not to mammalian tubulin. Because herbicides such as trifluralin are economical and are considered safe for man and domesticated animals, they may serve as useful sources of potential antiparasitic agents.
Disruption of the Nitrogen Cycle in Acidified Lakes
Authors: Rudd J. W. M. , Kelly C. A. , Schindler D. W. , Turner M. A.
Published: October 2006

Experimental acidification of two small soft-water lakes caused nitrification to cease at
p
H values of 5.4 to 5.7. The resulting blockage of the nitrogen cycle caused a progressive accumulation of ammonium. When the experimental acidification of one of the lakes was ended and the
p
H was raised to 5.4, nitrification resumed after a time lag of 1 year.
A Synthetic HIV-1 Protease Inhibitor with Antiviral Activity Arrests HIV-Like Particle Maturation
Authors: McQuade T. J. , Tomasselli A. G. , Liu L. , Karacostas V. , Moss B. , Sawyer T. K. , Heinrikson R. L. , Tarpley W. G.
Published: October 2006

A synthetic peptidemimetic substrate of the human immunodeficiency virus 1 (HIV-1) protease with a nonhydrolyzable pseudodipeptidyl insert at the protease cleavage site was prepared. The peptide U-81749 inhibited recombinant HIV-1 protease in vitro (inhibition constant
K
i
of 70 nanomolar) and HIV-1 replication in human peripheral blood lymphocytes (inhibitory concentration IC
50
of 0.1 to 1 micromolar). Moreover, 10 micromolar concentrations of U-81749 significantly inhibited proteolysis of the HIV-1 gag polyprotein (p55) to the mature viral structural proteins p24 and p17 in cells infected with a recombinant vaccinia virus expressing the HIV-1
gag-pol
genes. The HIV-1 like particles released from inhibitor-treated cells contained almost exclusively p55 and other gag precursors, but not p24. Incubation of HIV-like particles recovered from drug-treated cultures in drug-free medium indicated that inhibition of p55 proteolysis was at least partially reversible, suggesting that U-81749 was present within the particles.
Soft X-ray Images of the Solar Corona with a Normal-Incidence Cassegrain Multilayer Telescope
Authors: Walker Arthur B. C. , Lindblom Joakim F. , Barbee Troy W. , Hoover Richard B.
Published: October 2006

High-resolution images of the sun in the soft x-ray to extreme ultraviolet (EUV) regime have been obtained with normal-incidence Cassegrain multilayer telescopes operated from a sounding rocket in space. The inherent energy-selective property of multilayer-coated optics allowed distinct groups of emission lines to be isolated in the solar corona and the transition region. The Cassegrain telescopes provided images in bands centered at 173 and 256 angstroms. The bandpass centered at 173 angstroms is dominated by emission from the ions Fe IX and Fe X. This emission is from coronal plasma in the temperature range 0.8 × 10
6
to 1.4 × 10
6
K. The images have angular resolution of about 1.0 to 1.5 arc seconds, and show no degradation because of x-ray scattering. Many features of coronal structure, including magnetically confined loops of hot plasma, coronal plumes, polar coronal holes, faint structures on the size scale of supergranulation and smaller, and features due to overlying cool prominences are visible in the images. The density structure of polar plumes, which are thought to contribute to the solar wind, has been derived from the observations out to 1.7 solar radii.