bluuebunny/crossref_metadata_2025 huggingface dataset:
The Accumulation of Cosmogenic Chlorine-36 in Rocks: a Method for Surface Exposure Dating
Authors: Phillips Fred M. , Leavy Brian D. , Jannik Nancy O. , Elmore David , Kubik Peter W.
Published: October 2006

Because of the reaction of cosmic rays with elements in minerals, chlorine-36 accumulates in rocks exposed at the earth's surface. This suggests that the ratio of chlorine-36 to stable chloride can be used as a geochronometer. Reasonable agreement has been obtained between measurements of chlorine-36 in volcanic rocks of known age and calculations of chlorine-36 production based on rock composition and cosmic-ray flux. The buildup of chlorine-36 should be a useful means for measuring the surface exposure time of young volcanic rocks and geomorphic features in the age range of 10
3
to 10
6
years.
Hydrothermal Germanium Over the Southern East Pacific Rise
Authors: Mortlock Richard A. , Froelich Philip N.
Published: October 2006

Germanium enrichment in the oceanic water column above the southern axis of the East Pacific Rise results from hydrothermal solutions emanating from hot springs along the rise crest. This plume signature provides a new oceanic tracer of reactions between seawater and sea floor basalts during hydrothermal alteration. In contrast to the sharp plumes of
3
He and manganese, the germanium plume is broad and diffuse, suggesting the existence of pervasive venting of low-temperature solutions off the ridge axis.
Thermal Spectrum of Uranus: Implications for Large Helium Abundance
Authors: Orton Glenn S.
Published: October 2006

An analysis of the infrared spectrum of Uranus' disk between 7 micrometers and 3 millimeters suggests a volume mixing ratio for helium in the atmosphere of 40 ± 20 percent, more than for the sun, Jupiter, or Saturn. Alternative explanations require even more extreme assumptions regarding gas abundances or aerosol vertical distribution and spectral properties. The most serious difficulty with a model containing large amounts of helium is devising a credible evolutionary or chemical model explaining the absence or segregation of so much hydrogen.
Insecticide Resistance: Challenge to Pest Management and Basic Research
Authors: Brattsten L. B. , Holyoke C. W. , Leeper J. R. , Raffa K. F.
Published: October 2006

The agricultural use of synthetic insecticides usually protects crops but imposes strong selection pressures that can result in the development of resistance. The most important resistance mechanisms are enhancement of the capacity to metabolically detoxify insecticides and alterations in target sites that prevent insecticides from binding to them. Insect control methods must incorporate strategies to minimize resistance development and preserve the utility of the insecticides. The most promising approach, integrated pest management, includes the use of chemical insecticides in combination with improved cultural and biologically based techniques.
Venus: Detailed Mapping of Maxwell Montes Region
Authors: Alexandrov Yu. N. , Crymov A. A. , Kotelnikov V. A. , Petrov G. M. , Rzhiga O. N. , Sidorenko A. I. , Sinilo V. P. , Zakharov A. I. , Akim E. L. , Basilevski A. T. , Kadnichanski S. A. , Tjuflin Yu. S.
Published: October 2006

From October 1983 to July 1984, the north hemisphere of Venus, from latitude 30° to latitude 90°, was mapped by means of the radar imagers and altimeters of the spacecraft Venera 15 and Venera 16. This report presents the results of the radar mapping of the Maxwell Montes region, one of the most interesting features of Venus' surface. A radar mosaic map and contour map have been compiled.
The International Cometary Explorer Mission to Comet Giacobini-Zinner
Authors: von Rosenvinge Tycho T. , Brandt John C. , Farquhar Robert W.
Published: October 2006

The International Cometary Explorer (ICE) became the first spacecraft ever to encounter a comet when it passed through the tail of comet Giacobini-Zinner. An overview of this encounter is presented, including highlights of the results.
Comet Giacobini-Zinner: In Situ Observations of Energetic Heavy Ions
Authors: Ipavich F. M. , Galvin A. B. , Gloeckler G. , Hovestadt D. , Klecker B. , Scholer M.
Published: October 2006

Conclusive evidence is presented for the existence of energetic (∼35,000 to 150,000 electron volts), heavy (≳12 atomic mass units), singly charged cometary ions within ∼1.5 × 10
6
kilometers of comet Giacobini-Zinner. The observations were made with the University of Maryland/Max-Planck-Institut ultralow-energy charge analyzer on the International Cometary Explorer spacecraft. The most direct evidence for establishing the mass of these ions was obtained from an analysis of the energy signals in one of the solid-state detectors; it is significant at the three-sigma level. Maximum fluxes were recorded ∼1 hour before and ∼1 hour after closest approach to the cometary nucleus. Transformation of the particle angular distributions observed at ∼50,000 kilometers radial distance from the comet during the inbound pass into a rest frame in which the distributions are nearly isotropic requires a transformation velocity that is consistent with the local solar wind velocity if one assumes that these particles are primarily singly ionized with a mass of 18 ± 6 atomic mass units. The existence of a frame of reference in which these water-group ions were isotropic implies that they underwent strong pitch angle scattering after their ionization. Particle energies in the rest frame extend to substantially higher values than would be expected if these ions were locally ionized and then picked up by the solar wind, implying that the ions were accelerated or heated. The derived ion density, ∼0.1 per cubic centimeter, is consistent with a crude model for the production and transport of pickup ions.
Cool Water: Demonstration of a Clean and Efficient New Coal Technology
Authors: Spencer D. F. , Alpert S. B. , Gilman H. H.
Published: October 2006

Cool Water, the world's first commercial-scale, integrated coal gasification combined cycle power plant, has been operating successfully since May 1984 near Barstow, California. The 100-megawatt plant, which was completed ahead of schedule and under budget, is probably the cleanest coal-fired power generating facility now in commercial operation. An ongoing demonstration program at Cool Water shows that future baseload power plants that use this technology can be built modularly in increments of a few hundred megawatts and compete economically with much larger, conventional coal-fired power plants equipped for flue gas desulfurization.
New Dates on Northern Yukon Artifacts: Holocene Not Upper Pleistocene
Authors: Nelson D. E. , Morlan Richard E. , Vogel J. S. , Southon J. R. , Harington C. R.
Published: October 2006

New radiocarbon dates on four artifacts that were thought to provide evidence for human occupation of the Yukon Territory during the upper Pleistocene indicate that all four are of late Holocene age. The original radiocarbon age obtained for one artifact (the so-called "Old Crow flesher") was in error by almost 26,000 years.
The Discovery of Dust Trails in the Orbits of Periodic Comets
Authors: Sykes Mark V. , Lebofsky Larry A. , Hunten Donald M. , Low Frank
Published: October 2006

Analysis of data from the Infrared Astronomical Satellite has yielded evidence for narrow trails of dust coincident with the orbits of periodic comets Tempel 2, Encke, and Gunn. Dust was found both ahead of and behind the orbital positions of these comets. This dust was produced by the low-velocity ejection of large particles during perihelion passage. More than 100 additional dust trails are suggested by the data, almost all near the detection limits of the satellite. Many of these dust trails may be derived from previously unobserved comets.
Rapid-Cycling Populations of
Brassica
Authors: Williams Paul H. , Hill Curtis B.
Published: October 2006

Rapid-cycling populations of six economically important species in the genus
Brassica
have unusual potential for resolving many problems in plant biology and for use in education. Rapid-cycling brassicas can produce up to ten generations of seed per year and serve as models for research in genetics, host-parasite relations, molecular biology, cell biology, plant biochemistry, population biology, and plant breeding. Brassicas are a highly diverse group of crop plants that have great economic value as vegetables and as sources of condiment mustard, edible and industrial oil, animal fodder, and green manure. These plants can also be used in the classroom as convenient, rapidly responding, living plant materials for "hands on" learning at all levels of our educational system.
High-Pressure Ruby and Diamond Fluorescence: Observations at 0.21 to 0.55 Terapascal
Authors: Xu J. A. , Mao H. K. , Bell P. M.
Published: October 2006

A diamond-anvil, high-pressure apparatus was used to extend the upper pressure limit of static laboratory experiments. Shifts of the
R
1
strong fluorescent line of ruby were observed that correspond to static pressures of 0.21 to 0.55 terapascal (2.1 to 5.5 megabars) at 25°C. Sensitive spectroscopic techniques in the pressure range 0.15 to 0.28 terapascal were used to observe ruby and diamond fluorescence separately; these two fluorescent emissions overlap strongly at high pressures. At pressures greater than approximately 0.28 terapascal, the diamond fluorescence diminished and the ruby fluorescence reappeared strongly. Pressure was determined by extrapolation of the calibrated shift of the ruby
R
1
line.
Detection of Water Vapor in Halley's Comet
Authors: Mumma Michael J. , Weaver Harold A. , Larson Harold P. , Davis D. Scott , Williams Michael
Published: October 2006

Gaseous, neutral H
2
O was detected in the coma of comet Halley on 22.1 and 24.1 December 1985 Universal Time. Nine spectral lines of the ν
3
band (2.65 micrometers) were found by means of a Fourier transform spectrometer (λ/Δλ ∼10
5
) on the NASA-Kuiper Airborne Observatory. The water production rate was ∼6 × 10
28
molecules per second on 22.1 December and 1.7 × 10
29
molecules per second on 24.1 December UT. The numbers of spectral lines and their intensities are in accord with nonthermal-equilibrium cometary models. Rotational populations are derived from the observed spectral line intensities and excitation conditions are discussed. The ortho-para ratio was found to be 2.66 ± 0.13, corresponding to a nuclear-spin temperature of 32 K (+5 K, -2 K), possibly indicating that the observed water vapor originated from a low-temperature ice.
Indication of Increasing Solar Ultraviolet-B Radiation Flux in Alpine Regions
Authors: Blumthaler Mario , Ambach Walter
Published: October 2006

Measurements at the Jungfraujoch High Mountain Station (Swiss Alps, 47°N, 3576 meters above sea level) indicate that there has been a slight increase of about 1 percent per year in the flux of solar ultraviolet-B radiation (290 to 330 nanometers) since 1981. A Robertson-Berger detector was used to measure solar erythemal radiation. The increase can be related to a long-term ozone depletion.
Japanese Research and Technology Policy
Authors: Lynn Leonard
Published: October 2006

Until recently the Japanese did not spend much on research and what they did spend was concentrated on the commercial development of technology. As a result there have so far been few Japanese breakthroughs in either science or technology. Dramatic changes have recently occurred, however, and Japan now trails only the United States and the Soviet Union in research spending. Beyond this, Japanese policy-makers are making a determined effort to overcome Japan's social and institutional barriers to scientific creativity.
Brownian Motion and Nonequilibrium Statistical Mechanics
Authors: Kubo Ryogo
Published: October 2006

This article is a personal reflection of the branch of nonequilibrium statistical mechanics called the linear response theory that has as its heart the fluctuation-dissipation thereom, which states that irreversible processes in nonequilibrium are necessarily related to thermal fluctuations in equilibrium. Its origin lies in the Einstein relation for the diffusion constant and the mobility of a Brownian particle. The short history of the fluctuation-dissipation theorem is described. Then the linear response theory is briefly summarized and the meaning of stochastization is considered. The Langevin equation approach and its extensions are reviewed.
Percolation and Galaxies
Authors: Schulman Lawrence S. , Seiden Philip E.
Published: October 2006

A theory is presented in which much of the structure of spiral galaxies arises from a percolation phase transition that underlies the phenomenon of propagating star formation. According to this view, the appearance of spiral arms is a consequence of the differential rotation of the galaxy and the characteristic divergence of correlation lengths for continuous phase transitions. Other structural properties of spiral galaxies, such as the distribution of the gaseous components and the luminosity, arise directly from a feedback mechanism that pins the star formation rate close to the critical point of the phase transition. The approach taken in this article differs from traditional dynamical views. The argument is presented that, at least for some galaxies, morphological and other features are already fixed by general properties of phase transitions, irrespective of detailed dynamic or other considerations.
Prime Tests and Keeping Proofs Secret
Authors: Kolata Gina
Published: October 2006

Stanford, California. On 29 July through 2 August, a group of computer scientists, mathematical physicists, and mathematicians met at Stanford University for a conference on Mathematics and Computers. It was a varied meeting—the talks ranged from the mathematics of chaos to a talk by the peripatetic Hungarian mathematician Paul Erdos on number theory problems that might be interesting to work on. In addition, software vendors set up shop, inviting investigators to bring their problems and try them on different systems.

On the last day of the conference, when the talks were in the field of computational complexity—the difficulty of doing certain computer calculations—two new computer science tricks were presented and are recounted here.
K
+
Current Diversity Is Produced by an Extended Gene Family Conserved in
Drosophila
and Mouse
Authors: Wei Aguan , Covarrubias Manuel , Butler Alice , Baker Keith , Pak Michael , Salkoff Lawrence
Published: October 2006

The
Drosophila
Shaker
gene on the X chromosome has three sister genes,
Shal
,
Shab
, and
Shaw
, which map to the second and third chromosomes. This extended gene family encodes voltage-gated potassium channels with widely varying kinetics (rate of macroscopic current activation and inactivation) and voltage sensitivity of steady-state inactivation. The differences in the currents of the various gene products are greater than the differences produced by alternative splicing of the
Shaker
gene. In
Drosophila
, the transient (A current) subtype of the potassium channel (
Shaker
and
Shal
) and the delayed-rectifier subtype (
Shab
and
Shaw
) are encoded by homologous genes, and there is more than one gene for each subtype of channel. Homologs of
Shaker
,
Shal
,
Shab
, and
Shaw
are present in mammals; each
Drosophila
potassium-channel gene may be represented as a multigene subfamily in mammals.
Effect of Phospholipase C-γ Overexpression on PDGF-induced Second Messengers and Mitogenesis
Authors: Margolis B. , Zilberstein A. , Franks C. , Felder S. , Kremer S. , Ullrich A. , Rhee S. G. , Skorecki K. , Schlessinger J.
Published: October 2006

Platelet-derived growth factor (PDGF) stimulates phospholipase C (PLC) activity and the phosphorylation of the γ isozyme of PLC (PLC-γ) in vitro and in living cells. The role of PLC-γ in the phosphoinositide signaling pathway was addressed by examining the effect of overexpression of PLC-γ on cellular responses to PDGF. Overexpression of PLC-γ correlated with PDGF-induced tyrosine phosphorylation of PLC-γ and with PDGF-induced breakdown of phosphatidylinositol 4,5-bisphosphate (PIP
2
). However, neither bradykinin- nor lysophosphatidic acid-induced phosphoinositide metabolism was enhanced in the transfected cells, suggesting that the G protein-coupled phosphoinositide responses to these ligands are mediated by other PLC isozymes. The enhanced PDGF-induced generation of inositol trisphosphate (IP3) did not enhance intracellular calcium signaling or influence PDGF-induced DNA synthesis. Thus, enzymes other than PLC-γ may limit PDGF-induced calcium signaling and DNA synthesis. Alternatively, PDGF-induced calcium signaling and DNA synthesis may use biochemical pathways other than phosphoinositide metabolism for signal transduction.
Miocene Characid Fishes from Colombia: Evolutionary Stasis and Extirpation
Authors: Lundberg John G. , Machado-Allison Antonio , Kay Richard F.
Published: October 2006

Fossil fishes from the Miocene La Venta fauna of the Magdalena River Valley, Colombia, are identified as
Colossoma macropomum
(Characidae), a living species from the Orinoco and Amazon basins. The fossils document a long and conservative history for a species that is highly specialized for feeding on streamside plants. The phylogenetically advanced position of
Colossoma
in the subfamily Serrasalminae implies that six related genera and other higher characid taxa originated well before 15 million years ago. This discovery also corroborates neontological evidence for a vicariance event that contributed species from Miocene Orinoco-Amazon faunas to the original Magdalena region fauna. The fossils suggest a formerly diverse Magdalena fauna that has suffered local extinction, perhaps associated with late Cenozoic tectonism. This new evidence may help explain the depauperate nature of the modern Magdalena River.
Polarized Electron Probes of Magnetic Surfaces
Authors: Celotta Robert J. , Pierce Daniel T.
Published: October 2006

The magnetic properties of surfaces are now being explored with electron spectroscopies that use electron spin polarization techniques. The increased activity in surface magnetic measurements with polarized electron beams is spurred by new scientific and technological challenges and is made feasible by recent advances in the technology of sources and detectors of polarized electrons. The ability to grow thin films and to engineer artificial structures permits new phenomena to be investigated at magnetic surfaces and interfaces. For such investigations, spin-polarized electron techniques—such as polarized electron scattering, polarized photoemission, polarized Auger spectroscopy, and scanning electron microscopy with polarization analysis—have been and will probably continue to be used to great advantage.
Uplifted Marine Terraces Along the Alpine Fault, New Zealand
Authors: Bull William B. , Cooper Alan F.
Published: October 2006

Three types of evidence indicate that marine terraces are widespread in the Southern Alps of New Zealand. (i) Remnants of shore platforms occur as distinct levels of notched ridge crests and flat summits; degraded sea cliffs are common. (ii) Scattered quartz beach pebbles occur on 16 of 18 levels of exhumed shore platforms in the Fox-Franz Josef type area to altitudes as high as 1700 meters. (iii) Altitudinal spacings of New Zealand terrace flights allow correlation with 18 dated global marine terraces at New Guinea, which were formed during glacio-eustatic highstands of sea level within the last 336 × 10
3
years. Inferred uplift rates at Fox-Franz Josef increased from 3.2 to 7.8 meters per 10
3
years since about 135 × 10
3
to 140 × 10
3
years ago, presumably because of increased convergence between the Pacific and Australian plates.
The Need for Central and Peripheral Tolerance in the B Cell Repertoire
Authors: Goodnow Christopher C. , Adelstein Stephen , Basten Antony
Published: October 2006

The immune system normally avoids producing antibodies that react with autologous ("self") antigens by censoring self-reactive T and B cells. Unlike the T cell repertoire, antibody diversity is generated within the B cell repertoire in two phases; the first occurs by gene rearrangement in primary lymphoid organs, and the second phase involves antigen-driven hypermutation in peripheral lymphoid organs. The possibility that distinct cellular mechanisms may impose self tolerance at these two different phases of B cell diversification may explain recent findings in transgenic mouse models, in which self-reactive B cells appear to be silenced both by functional inactivation and by physical elimination.
Phonon Density of States and Specific Heat of Forsterite, Mg
2
SiO
4
Authors: Rao K. R. , Chaplot S. L. , Choudhury Narayani , Ghose Subrata , Price D. L.
Published: October 2006

The phonon density of states of the geophysically important mineral forsterite has been calculated with a rigid-ion model, which gives good agreement with an experimental measurement by inelastic neutron scattering. The density of states has been used to calculate the specific heat as a function of temperature, the results of which are in excellent agreement with calorimetrically measured values. The rigid-ion model takes account of the interatomic interactions and normal modes of vibration on a detailed microscopic basis, and is therefore more realistic than the Debye and other empirical models used previously.
A Sheep in Wolf's Clothing: Tephritid Flies Mimic Spider Predators
Authors: Mather Monica H. , Roitberg Bernard D.
Published: October 2006

Mimicry where prey resemble predators to avoid predation is unusual. Snowberry flies,
Rhagoletis zephyria
Snow, possess striped wing patterns that resemble the legs of jumping spiders. Observations and comparisons of responses of the jumping spider
Salticus scenicus
(Clerck) to conspecifics, snowberry flies, and other prey flies showed that snowberry flies can avoid predation by jumping spiders through spider mimicry. The mimicry effect was decreased by obliterating snowberry fly wing stripes.
Some Concepts in Reaction Dynamics
Authors: Polanyi John C.
Published: October 2006

The objective in this work has been one which I have shared with the two other 1986 Nobel lecturers in chemistry, D. R. Herschbach and Y. T. Lee, as well as with a wide group of colleagues and co-workers who have been responsible for bringing this field to its current state. That state is summarized in the title; we now have some concepts relevant to the motions of atoms and molecules in simple reactions, and some examples of the application of these concepts. We are, however, richer in vocabulary than in literature. The great epics of reaction dynamics remain to be written. I shall confine myself to some simple stories.
Molecular Beam Studies of Elementary Chemical Processes
Authors: Lee Yuan Tseh
Published: October 2006

The experimental investigation of elementary chemical reactions is presently in a very exciting period. The advance in modern microscopic experimental methods, especially crossed molecular beams and laser technology, has made it possible to explore the dynamics and mechanisms of important elementary chemical reactions in great detail. Through the continued accumulation of detailed and reliable knowledge about elementary reactions, we will be in a better position to understand, predict, and control many time-dependent macroscopic chemical processes that are important in nature or to human society.

In addition, because of recent improvements in the accuracy of theoretical predictions based on large-scale ab initio quantum mechanical calculations, meaningful comparisons between theoretical and experimental findings have become possible. In the remaining years of the 20th century, there is no doubt that the experimental investigation of the dynamics and mechanisms of elementary chemical reactions will play a very important role in bridging the gap between the basic laws of mechanics and the real world of chemistry.
The Large Crater Origin of SNC Meteorites
Authors: Vickery A. M. , Melosh H. J.
Published: October 2006

A large body of evidence strongly suggests that the shergottite, nakhlite, and Chassigny (SNC) meteorites are from Mars. Various mechanisms for the ejection of large rocks at martian escape velocity (5 kilometers per second) have been investigated, but none has proved wholly satisfactory. This article examines a number of possible ejection and cosmic-ray exposure histories to determine which is most plausible. For each possible history, the Melosh spallation model is used to estimate the size of the crater required to produce ejecta fragments of the required size with velocities ≥ 5 kilometers per second and to produce a total mass of solid ejecta consistent with the observed mass flux of SNC meteorites. Estimates of crater production rates on Mars are then used to evaluate the probability that sufficiently large craters have formed during the available time. The results indicate that the SNC meteorites were probably ejected from a very large crater (> 100 kilometers in diameter) about 200 million years ago, and that cosmic-ray exposure of the recovered meteorites was initiated after collisional fragmentation of the original ejecta in space at much later times (0.5 to 10 million years ago).
Possible Tornado-Like Tracks on Mars
Authors: Grant John A. , Schultz Peter H.
Published: October 2006

Distinct atmospheric conditions suggest that dark, ephemeral, filamentary lineations on the martian surface may be formed during the passage of intense atmospheric vortices.
Seismomagnetic Observation During the 8 July 1986 Magnitude 5.9 North Palm Springs Earthquake
Authors: Johnston M. J. S. , Mueller R. J.
Published: October 2006

A differentially connected array of 24 proton magnetometers has operated along the San Andreas fault since 1976. Seismomagnetic offsets of 1.2 and 0.3 nanotesla were observed at epicentral distances of 3 and 9 kilometers, respectively, after the 8 July 1986 magnitude 5.9 North Palm Springs earthquake. These seismomagnetic observations are the first obtained of this elusive but long-anticipated effect. The data are consistent with a seismomagnetic model of the earthquake for which right-lateral rupture of 20 centimeters is assumed on a 16-kilometer segment of the Banning fault between the depths of 3 and 10 kilometers in a region with average magnetization of 1 ampere per meter. Alternative explanations in terms of electrokinetic effects and earthquake-generated electrostatic charge redistribution seem unlikely because the changes are permanent and complete within a 20-minute period.
Turbidity Current Activity in a British Columbia Fjord
Authors: Prior David B. , Bornhold Brian D. , Wiseman William J. , Lowe Donald R.
Published: October 2006

A year-long monitoring program within an elongated channel-fan system in Bute Inlet of British Columbia, Canada, detected active sand-transporting turbidity currents. Measurements of bottom velocities and sediment collected in traps, as well as damage to moorings and equipment, captured the signatures of frequent energetic events. Maximum calculated velocities achieved were 335 centimeters per second, with flow thicknesses of more than 30 meters. Coarse sand was transported at least 6 to 7.5 meters above the sea floor. Turbidity currents flowed a minimum distance of 25.9 kilometers, but possibly as far as 40 to 50 kilometers, over bottom slopes of generally less than 1°.
Salicylic Acid: A Natural Inducer of Heat Production in
Arum
Lilies
Authors: Raskin Ilya , Ehmann Axel , Melander Wayne R. , Meeuse Bastiaan J. D.
Published: October 2006

For more than 50 years the identity of "calorigen," the agent that triggers pronounced heat production in the flowers and inflorescences of some thermogenic plants, remained obscure. Mass spectroscopic analysis of highly purified calorigen extracted from the male flowers of
Sauromatum guttatum
Schott (voodoo lily) revealed the presence of 2-hydroxybenzoic (salicylic) acid. Application of salicylic acid at 0.13 microgram per gram (fresh weight) to sections of the upper part of the plant's immature spadix, known as the appendix, led to temperature increases of as much as 12 Celsius degrees. These increases duplicated, in both magnitude and timing, the temperature increases produced by the crude calorigen extract. The sensitivity of appendix tissue to salicylic acid increases daily with the approach of anthesis and is controlled by the photoperiod. Thus, at least in some
Arum
lilies, salicylic acid functions as an endogenous regulator of heat production.
Soluble Human Complement Receptor Type 1: In Vivo Inhibitor of Complement Suppressing Post-Ischemic Myocardial Inflammation and Necrosis
Authors: Weisman Harlan F. , Bartow Thomas , Leppo Michelle K. , Marsh Henry C. , Carson Gerald R. , Concino Michael F. , Boyle Michael P. , Roux Kenneth H. , Weisfeldt Myron L. , Fearon Douglas T.
Published: October 2006

The complement system is an important mediator of the acute inflammatory response, and an effective inhibitor would suppress tissue damage in many autoimmune and inflammatory diseases. Such an inhibitor might be found among the endogenous regulatory proteins of complement that block the enzymes that activate C3 and C5. Of these proteins, complement receptor type 1 (CR1; CD35) has the most inhibitory potential, but its restriction to a few cell types limits its function in vivo. This limitation was overcome by the recombinant, soluble human CR1, sCR1, which lacks the transmembrane and cytoplasmic domains. The sCR1 bivalently bound dimeric forms of its ligands, C3b and methylamine-treated C4 (C4-ma), and promoted their inactivation by factor I. In nanomolar concentrations, sCR1 blocked complement activation in human serum by the two pathways. The sCR1 had complement inhibitory and anti-inflammatory activities in a rat model of reperfusion injury of ischemic myocardium, reducing myocardial infarction size by 44 percent. These findings identify sCR1 as a potential agent for the suppression of complement-dependent tissue injury in autoimmune and inflammatory diseases.
Autophosphorylation of Protein Kinase C at Three Separated Regions of Its Primary Sequence
Authors: Flint Andrew J. , Paladini Rudolph D. , Koshland Daniel E.
Published: October 2006

The major autophosphorylation sites of the rat βII isozyme of protein kinase C were identified. The modified threonine and serine residues were found in the amino-terminal peptide, the carboxyl-terminal tail, and the hinge region between the regulatory lipid-binding domain and the catalytic kinase domain. Because this autophosphorylation follows an intrapeptide mechanism, extraordinary flexibility of the protein is necessary to phosphorylate the three regions. Comparison of the sequences surrounding the modified residues showed no obvious recognition motif nor any similarity to substrate phosphorylation sites, suggesting that proximity to the active site may be the primary criterion for their phosphorylation.
Biological Invasion by
Myrica faya
Alters Ecosystem Development in Hawaii
Authors: Vitousek Peter M. , Walker Lawrence R. , Whiteaker Louis D. , Mueller-Dombois Dieter , Matson Pamela A.
Published: October 2006

The exotic nitrogen-fixing tree
Myrica faya
invades young volcanic sites where the growth of native plants is limited by a lack of nitrogen.
Myrica
quadruples the amount of nitrogen entering certain sites and increases the overall biological availability of nitrogen, thereby altering the nature of ecosystem development after volcanic eruptions.
Very High Energy Gamma-Ray Binary Stars
Authors: Lamb R. C. , Weekes T. C.
Published: October 2006

One of the major astronomical discoveries of the last two decades was the detection of luminous x-ray binary star systems in which gravitational energy from accretion is released by the emission of x-ray photons, which have energies in the range of 0.1 to 10 kiloelectron volts. Recent observations have shown that some of these binary sources also emit photons in the energy range of 10
12
electron volts and above. Such sources contain a rotating neutron star that is accreting matter from a companion. Techniques to detect such radiation are ground-based, simple, and inexpensive. Four binary sources (Hercules X-1, 4U0115+63, Vela X-1, and Cygnus X-3) have been observed by at least two independent groups. Although the discovery of such very high energy "gamma-ray binaries" was not theoretically anticipated, models have now been proposed that attempt to explain the behavior of one or more of the sources. The implications of these observations is that a significant portion of the more energetic cosmic rays observed on Earth may arise from the action of similar sources within the galaxy during the past few million years.
Infrared Laser Spectroscopy of Molecular Ions
Authors: Saykally Richard J.
Published: October 2006

The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules. Velocity modulation laser spectroscopy, which exploits the motions of charged particles in electrical plasmas to eliminate interference from neutral absorbers, is rapidly producing a large body of new results for both positive and negative molecular ions. This information will have an important impact on chemistry, biology, and astrophysics.
Synchrotron X-ray Diffraction Measurements of Single-Crystal Hydrogen to 26.5 Gigapascals
Authors: Mao H. K. , Jephcoat A. P. , Hemley R. J. , Finger L. W. , Zha C. S. , Hazen R. M. , Cox D. E.
Published: October 2006

The crystal structure and equation of state of solid hydrogen have been determined directly to 26.5 gigapascals at room temperature by new synchrotron x-ray diffraction techniques. Solid hydrogen remains in the hexagonal close-packed structure under these pressure-temperature conditions and exhibits increasing structural anisotropy with pressure. The pressure-volume curve determined from the x-ray data represents the most accurate experimental measurement of the equation of state to date in this pressure range. The results remove the discrepancy between earlier indirect determinations and provide a new experimental constraint on the molecular-to-atomic transition predicted at higher pressures.
The 1987 Whittier Narrows Earthquake in the Los Angeles Metropolitan Area, California
Authors: Hauksson Egill , Jones Lucile M. , Davis Thomas L. , Hutton L. Katherine , Williams Patrick , Bent Allison L. , Brady A. Gerald , Reasenberg Paul A. , Michael Andrew J. , Yerkes Robert F. , Etheredge Edwin , Porcella Ronald L. , Johnston Malcolm J. S. , Reagor Glen , Stover Carl W. , Bufe Charles G. , Cranswick Edward , Shakal Anthony K.
Published: October 2006

The Whittier Narrows earthquake sequence (local magnitude,
M

L

= 5.9), which caused over $358-million damage, indicates that assessments of earthquake hazards in the Los Angeles metropolitan area may be underestimated. The sequence ruptured a previously unidentified thrust fault that may be part of a large system of thrust faults that extends across the entire east-west length of the northern margin of the Los Angeles basin. Peak horizontal accelerations from the main shock, which were measured at ground level and in structures, were as high as 0.6
g
(where
g
is the acceleration of gravity at sea level) within 50 kilometers of the epicenter. The distribution of the modified Mercalli intensity VII reflects a broad north-south elongated zone of damage that is approximately centered on the main shock epicenter.
A β
3
Integrin Mutation Abolishes Ligand Binding and Alters Divalent Cation-Dependent Conformation
Authors: Loftus Joseph C. , O'Toole Timothy E. , Plow Edward F. , Glass Alison , Frelinger Andrew L. , Ginsberg Mark H.
Published: October 2006

The ligand-binding function of integrin adhesion receptors depends on divalent cations. A mutant α
IIb
β
3
integrin (platelet gpIIb/IIIa) that lacks ligand recognition shows immunologic evidence of a perturbed interaction with divalent cations. This was found to be caused by a G → T mutation that resulted in an Asp
119
→ Tyr
119
substitution in the β
3
subunit. This residue is proximal to bound ligand and is in a conserved region among integrins that are enriched in oxygenated residues. The spacing of these residues aligns with the calcium-binding residues in EF hand proteins, suggesting interaction with receptor-bound divalent cation as a mechanism of ligand binding common to all integrins.
Dynamic Properties of Molecularly Thin Liquid Films
Authors: Israelachvili Jacob N. , McGuiggan Patricia M. , Homola Andrew M.
Published: October 2006

An experimental technique is described for simultaneously measuring the static and dynamic interactions of very thin liquid films between two surfaces as they are moved normally or laterally relative to each other. Film thickness can be measured and controlled to 1 angstrom. Initial results are presented of the transition in the physical properties of liquid films only one molecular layer thick to thicker films whose properties are practically indistinguishable from the bulk. In particular, the results show that two molecularly smooth surfaces, when close together in simple liquids, slide (shear) past each other while separated by a discrete number of molecular layers, and that the frictional force is "quantized" with the number of layers.
Insecticidal Activity and Lectin Homology of Arcelin Seed Protein
Authors: Osborn Thomas C. , Alexander Danny C. , Sun Samuel S. M. , Cardona Cesar , Bliss Fredrick A.
Published: October 2006

Arcelin, a major seed protein discovered in wild beans (
Phaseolus vulgaris
), has toxic effects on an important bean bruchid pest,
Zabrotes subfasciatus.
Transfer of the arcelin-1 allele to bean cultivars and addition of purified arcelin to artificial seeds results in high levels of insect resistance. The nucleotide and derived amino acid sequences of the arcelin-1 complementary DNA are very similar to those of genes encoding the bean seed lectin, phytohemagglutinin. The gene or genes encoding arcelin may have evolved from a phytohemagglutinin gene or genes resulting in an effective mechanism for resistance to bean bruchids.
Antarctic Ozone Depletion Chemistry: Reactions of N
2
O
5
with H
2
O and HCl on Ice Surfaces
Authors: Tolbert Margaret A. , Rossi Michel J. , Golden David M.
Published: October 2006

The reactions of dinitrogen pentoxide (N
2
O
5
) with H
2
O and hydrochloric acid (HCl) were studied on ice surfaces in a Knudsen cell flow reactor. The N
2
O
5
reacted on ice at 185 K to form condensed-phase nitric acid (HNO
3
). This reaction may provide a sink for odd nitrogen (NO

x

) during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. A lower limit to the sticking coefficient, γ, for N
2
O
5
on ice is 1 × 10
-3
. Moreover, N
2
O
5
reacted on HCl-ice surfaces at 185 K, with γ greater than 3 × 10
-3
. This reaction, which produced gaseous nitryl chloride (ClNO
2
) and condensed-phase HNO
3
, proceeded until all of the HCl within the ice was depleted. The ClNO
2
, which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide (NO
2
), may be important in the partitioning of NO

x

between gaseous and condensed phases in the Antarctic winter.
Sampling Rare and Elusive Populations
Authors: Sudman Seymour , Sirken Monroe G. , Cowan Charles D.
Published: October 2006

The sampling of rare and elusive populations is difficult because the costs of locating such populations are substantial and can exceed actual interviewing costs. There are efficient probability methods that have been developed recently that reduce these costs. If the special populations are geographically clustered, efficient sampling involves the rapid location of segments in which no members of the special population are located with the use of Census data, telephone screening, or incomplete lists. Populations that are not geographically clustered can be located by network sampling and use of large previously gathered samples. Characteristics of mobile populations such as the homeless can be estimated by capture-recapture methods.
Seismic Slip and Down-Dip Strain Rates in Wadati-Benioff Zones
Authors: Bevis Michael
Published: October 2006

The rate of accumulation of seismic moment in Wadati-Benioff zones is used to estimate strain rates in subducting slabs that are sinking through the asthenosphere. Between depths of 75 and 175 kilometers a typical down-dip strain rate is about 10
-15
per second, which implies that slabs in this depth range typically accumulate strains of order 10
-1
. This result is in accord with geometrical arguments that subducted slabs must experience large membrane strains to deform to their observed shapes. Mantle seismicity (repeated catastrophic shear failure) is apparently a primary mechanism by which large membrane strains accumulate in the cold cores of subducting slabs. Slabs are penetratively deformed, and they have low flexural rigidity compared to oceanic plates at the earth's surface.
Bacterial Manganese Reduction and Growth with Manganese Oxide as the Sole Electron Acceptor
Authors: Myers Charles R. , Nealson Kenneth H.
Published: October 2006

Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium,
Alteromonas putrefaciens
MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.
Mixing in Starts
Authors: Wallerstein George
Published: October 2006

Analysis of the chemical and isotopic composition of stellar surfaces reveals the types of nuclear reactions that have occurred in the stellar interiors as well as the timing and depths from which material once deep in the star has reached the surface. Mass loss from the stellar surface and, in some cases, mass transfer from a companion enhance the opportunity to observe material that is the product of internal nuclear reactions. Detailed studies show substantial deficiencies in current models with the timing and depth of convective and other forms of mixing.
Deuterium on Mars: The Abundance of HDO and the Value of D/H
Authors: Owen Tobias , Maillard Jean Pierre , de Bergh Catherine , Lutz Barry L.
Published: October 2006

Deuterium on Mars has been detected by the resolution of several Doppler-shifted lines of HDO near 3.7 micrometers in the planet's spectrum. The ratio of deuterium to hydrogen is (9 ± 4) × 10
-4
; the abundance of H
2
0 was derived from lines near 1.1 micrometers. This ratio is enriched on Mars over the teiluric value by a factor of 6 ± 3. The enrichment implies that hydrogen escaped more rapidly from Mars in the past than it does now, consistent with a dense and warm ancient atmosphere on the planet.
Protein Sorting to Mitochondria: Evolutionary Conservations of Folding and Assembly
Authors: Hartl Franz-Ulrich , Neupert Walter
Published: October 2006

According to the endosymbiont hypothesis, mitochondria have lost the autonomy of their prokaryotic ancestors. They have to import most of their proteins from the cytosol because the mitochondrial genome codes for only a small percentage of the polypeptides that reside in the organelle. Recent findings show that the sorting of proteins into the mitochondrial subcompartments and their folding and assembly follow principles already developed in prokaryotes. The components involved may have structural and functional equivalents in bacteria.
Syrian Hamster Female Protein: Analysis of Female Protein Primary Structure and Gene Expression
Authors: Dowton S. Bruce , Woods Derek E. , Mantzouranis Evangelia C. , Colten Harvey R.
Published: October 2006

The concentration in plasma of the female protein (FP) of the golden Syrian hamster is regulated by sex steroids and by mediators of the acute-phase response to tissue injury or inflammation. A complementary DNA (cDNA) clone corresponding to FP was isolated from a hamster liver cDNA library and used to determine the nucleotide sequence and derived amino acid sequence of native FP. The primary sequence of FP is 69 percent identical to human serum amyloid P component and 50 percent identical to human C-reactive protein. Evidence showed that sex-limited and acute-phase control of the FP gene is pretranslational. The FP protein is thus a useful model for investigating dual regulation of expression of a single gene.
Correlated Measurements of DNA, RNA, and Protein in Individual Cells by Flow Cytometry
Authors: Crissman Harry A. , Darzynkiewicz Zbigniew , Tobey Robert A. , Steinkamp John A.
Published: October 2006

A cytochemical method was developed to differentially stain cellular DNA, RNA, and proteins with fluorochromes Hoechst 33342, pyronin Y, and fluorescein isothiocyanate, respectively. The fluorescence intensities, reflecting the DNA, RNA, and protein content of individual cells, were measured in a flow cytometer after sequential excitation by three lasers tuned to different excitation wavelengths. The method offers rapid analysis of changes in the cellular content of RNA and protein as well as in the RNA-protein, RNA-DNA, and protein-DNA ratios in relation to cell cycle position for large cell populations. An analysis of cycling cell populations (exponentially growing CHO cultures) and noncycling CHO cells arrested in the G
1
phase by growth in isoleucine-free medium demonstrated the potential of the technique.
Ca
2+
and Ca
2+
-Activated K
+
Currents in Mammalian Gastric Smooth Muscle Cells
Authors: Mitra Raman , Morad Martin
Published: October 2006

Inward movement of calcium through voltage-dependent channels in muscle is thought to initiate the action potential and trigger contraction. Calcium-activated potassium channels carry large outward potassium currents that may be responsible for membrane repolarization. Calcium and calcium-activated potassium currents were identified in enzymatically isolated mammalian gastric myocytes. These currents were blocked by cadmium and nifedipine but were not substantially affected by diltiazem or D600. No evidence for a tetrodotoxin-sensitive sodium current or an inwardly rectifying potassium current was found.
Gas-Phase Clusters: Spanning the States of Matter
Authors: Castleman A. W. , Keesee R. G.
Published: October 2006

Gas-phase clusters, which are weakly bound aggregates comprised of either atoms or molecules, often display properties that lie between those of the gaseous and condensed states. Interesting questions arise concerning how large a cluster must be before it will display bulk properties. Currently there is extensive research activity directed toward studies of their formation and varying properties and reactivity as a function of the degree of aggregation. Results serve to elucidate at the molecular level the course of change of a system to be followed from the gas to the condensed state, thereby enabling a spanning of the states of matter.
Curvature and Propagation Velocity of Chemical Waves
Authors: Foerster Petra , Müller Stefan C. , Hess Benno
Published: October 2006

The collision of circular chemical waves in an excitable medium, the Belousov-Zhabotinskii reaction, leads to characteristic cusplike structures. The high curvatures of these structures are especially suitable for experimentally verifying the predicted proportionality between the velocity and the shape of traveling waves. A computerized spectrophotometric video technique with microscopic resolution was used to determine the proportionality factor (2 × 10
-5
square centimeter per second), which in this case is the diffusion coefficient of the autocatalytic species of the reaction system. A numerical calculation of the spatiotemporal evolution of the cusp structure is in good agreement with the experimental observations.