bluuebunny/crossref_metadata_2025 huggingface dataset:
Catalysis: New Perspectives from Surface Science
Authors: Goodman D. W. , Houston J. E.
Published: October 2006

One-sixth of the value of all goods manufactured in the United States involves catalytic processes. However, in spite of this dramatic economic impact, little is known about this broad subject at the molecular level. In the last two decades a variety of techniques have been developed for studying at the atomic level the structure, composition, and chemical bonding at surfaces. These techniques have been used to study adsorption and reaction on metal single crystals in an ultrahigh vacuum environment or to analyze catalysts before and after reaction. An important new development has been the coupling of an apparatus for the measurement of reaction kinetics at elevated pressures with an ultrahigh vacuum system for surface analysis. This approach has demonstrated that metal single crystals can be used to successfully model many important catalytic reactions and has established a direct link between the results of ultrahigh vacuum surface measurements and the chemistry that occurs under typical catalytic-processing conditions.
Mesoscale Oceanographic Processes Beneath the Ice of Fram Strait
Authors: Manley T. O. , Hunkins K. L. , Villanueva J. Z. , Van Leer J. , Gascard J. C. , Jeannin P. F.
Published: October 2006

A major component of the Fram Strait Marginal Ice Zone Experiment was the investigation of air-sea-ice interactions, processes, and circulation patterns found behind the local ice edge and on scales greater than 10 kilometers (mesoscale and large scale). Neutrally buoyant floats, ice-tethered cyclesondes, and helicopter-based measurements were used to obtain uniquely integrated and consistent views of the mesoscale ocean features beneath the ice cover of Fram Strait. Within the vicinity of the Yermak Plateau, three distinct regions of mesoscale motion were observed that coincided with the shallow topography of the plateau, the northward flowing Atlantic water over the western flank of the plateau, and the strong current-shear zone of the East Greenland Polar Front. A subice meander of the front was also observed, which was probably occluded subsequently.
Freezing
Authors: Haymet A. D. J.
Published: October 2006

There is no first principles theory of freezing or melting, even for the simplest materials. The prediction of phase diagrams is an important first step in understanding the crystal-melt interface, crystallization near equilibrium, and nucleation. Recently, a new approximate theory for the freezing of classical liquids, known as the density functional theory, has been developed. The predictions of the theory are relatively accurate and its mathematical structure is simple enough to provide an attractive starting point for theories of more complex, dynamical phenomena.
The ASYST Software for Scientific Computing
Authors: Hary David , Oshio Koichi , Flanagan Steven D.
Published: October 2006

The acceptance of ASYST by the scientific community could dramatically change the way scientific data are handled and reduce the need for extensive in-house software development for many applications. However, there is no substitute for a well-conceived use of any software. We feel that the full acceptance of the ideas and concepts pioneered by Adaptable Laboratory Software and other software houses will depend on the ability of the scientific community to fully test and verify the procedures used by such products. Only then can the results produced by these software packages be subjected to confirmation which is crucial to rigorous scientific endeavor.
Propagation in Cell Culture of the Dinoflagellate
Amyloodinium
, an Ectoparasite of Marine Fishes
Authors: Noga Edward J.
Published: October 2006

Amyloodinium ocellatum
, a common dinoflagellate ectoparasite of marine fishes, was successfully propagated on a fish gill cell line. In vitro infections were similar in cytopathology and development to those reported on natural hosts, and large numbers of parasites could be produced. Exposure of parasites in cell culture to an antiprotozoal drug produced a dose-dependent inhibition of infectivity that was much more sensitive than a motility assay previously used to assess the toxic effects of a drug on protozoan ectoparasites. This propagation system may be a useful model for studying the biology and control of protozoan skin parasites of fishes and for quantitatively studying hostparasite interaction at cellular interfaces.
Chemistry of Molecular Growth Processes in Flames
Authors: Smyth Kermit C. , Miller J. Houston
Published: October 2006

Chemical mechanisms of pyrolysis, growth, and oxidation processes in flames have traditionally been inferred from spatial profile measurements of species concentrations. Experimental investigations now include the detection of numerous minor species such as reactive radicals and intermediate hydrocarbons. In assessing a proposed mechanism important new constraints can be established when the detailed species profile data are combined with velocity and temperature measurements and analyzed to determine production and destruction rates for specific molecules. Recent results on hydrocarbon diffusion flames provide new information on the interplay between chemical and transport processes. These measurements have led to direct tests of proposed routes for the formation of aromatic hydrocarbons and the first, small soot particles. The inception chemistry of hydrocarbon growth reactions and initial particle formation is thought to control soot formation, flame radiation and energy transfer, and pollutant emission in combustion environments.
The Shapes of Random Walks
Authors: Rudnick Joseph , Gaspari George
Published: October 2006

A theoretical description of the shape of a random object is presented that is analytically simple in application but quantitatively accurate. The asymmetry of the object is characterized in terms of the invariants of a tensor, analogous to the moment-of-inertia tensor, whose eigenvalues are the squares of the principal radii of gyration. The complications accompanying ensemble averaging because of random processes are greatly reduced when the object is embedded in a space of high dimensionality,
d
. Exact analytical expressions are presented in the case of infinite spatial dimensions, and a procedure for developing an expansion in powers of l/
d
is discussed for linear chain and ring-type random walks. The first two terms in such an expansion lead to results for various shape parameters that agree remarkably well with those calculated by computer simulation. The method can be extended to yield an approximate, but extremely accurate, expression for the probability distribution function directly. The theoretical approach discussed here can, in principle, be used to describe the shape of other random fractal objects as well.
Magnetic Field Reversals, Polar Wander, and Core-Mantle Coupling
Authors: Courtillot Vincent , Besse Jean
Published: October 2006

True polar wander, the shifting of the entire mantle relative to the earth's spin axis, has been reanalyzed. Over the last 200 million years, true polar wander has been fast (approximately 5 centimeters per year) most of the time, except for a remarkable standstill from 170 to 110 million years ago. This standstill correlates with a decrease in the reversal frequency of the geomagnetic field and episodes of continental breakup. Conversely, true polar wander is high when reversal frequency increases. It is proposed that intermittent convection modulates the thickness of a thermal boundary layer at the base of the mantle and consequently the core-to-mantle heat flux. Emission of hot thermals from the boundary layer leads to increases in mantle convection and true polar wander. In conjunction, cold thermals released from a boundary layer at the top of the liquid core eventually lead to reversals. Changes in the locations of subduction zones may also affect true polar wander. Exceptional volcanism and mass extinctions at the Cretaceous-Tertiary and Permo-Triassic boundaries may be related to thermals released after two unusually long periods with no magnetic reversals. These environmental catastrophes may therefore be a consequence of thermal and chemical couplings in the earth's multilayer heat engine rather than have an extraterrestrial cause.
Cloning and Detection of DNA from a Nonculturable Plant Pathogenic Mycoplasma-like Organism
Authors: Kirkpatrick Bruce C. , Stenger Drake C. , Morris T. Jack , Purcell Alexander H.
Published: October 2006

The ability to detect, quantify, and differentiate nonculturable mycoplasma-like organisms (MLOs) would greatly facilitate epidemiological and taxonomical studies of this unique group of plant and insect pathogens. DNA isolated from extracts of insects infected with the Western X-disease MLO was cloned in
Escherichia coli
. X-disease-specific clones, when labeled and used as probes, readily detected X-disease MLOs in infected plants and insects but did not hybridize with DNA from healthy plants or insects, or from several other plant pathogenic MLOs or spiroplasmas. These methods provide both a sensitive diagnostic tool and a basis for genetically differentiating MLOs.
Cumulative Impacts of Oil Fields on Northern Alaskan Landscapes
Authors: Walker D. A. , Webber P. J. , Binnian E. F. , Everett K. R. , Lederer N. D. , Nordstrand E. A. , Walker M. D.
Published: October 2006

Proposed further developments on Alaska's Arctic Coastal Plain raise questions about cumulative effects on arctic tundra ecosystems of development of multiple large oil fields. Maps of historical changes to the Prudhoe Bay Oil Field show indirect impacts can lag behind planned developments by many years and the total area eventually disturbed can greatly exceed the planned area of construction. For example, in the wettest parts of the oil field (flat thaw-lake plains), flooding and thermokarst covered more than twice the area directly affected by roads and other construction activities. Protecting critical wildlife habitat is the central issue for cumulative impact analysis in northern Alaska. Comprehensive landscape planning with the use of geographic information system technology and detailed geobotanical maps can help identify and protect areas of high wildlife use.
Exchange of Materials Between Terrestrial Ecosystems and the Atmosphere
Authors: Mooney Harold A. , Vitousek Peter M. , Matson Pamela A.
Published: October 2006

Many biogenic trace gases are increasing in concentration or flux or both in the atmosphere as a consequence of human activities. Most of these gases have demonstrated or potential effects on atmospheric chemistry, climate, and the functioning of terrestrial ecosystems. Focused studies of the interactions between the atmosphere and the biosphere that regulate trace gases can improve both our understanding of terrestrial ecosystems and our ability to predict regional- and global-scale changes in atmospheric chemistry.
End-Cretaceous Mass Extinction Event: Argument for Terrestrial Causation
Authors: Hallam Anthony
Published: October 2006

The end-Cretaceous mass extinctions were not a geologically instantaneous event and were selective in character. These features are incompatible with the original Alvarez hypothesis of their being caused by a single asteroid impact that produced a world-embracing dust cloud with devastating environmental consequences. By analysis of physical and chemical evidence from the stratigraphic record it is shown that a modified extraterrestrial model in which stepwise extinctions resulted from encounter with a comet shower is less plausible than one intrinsic to the earth, involving significant disturbance in the mantle.
Low-Input Cropping for Acid Soils of the Humid Tropics
Authors: Sanchez Pedro A. , Benites Jose R.
Published: October 2006

A low-input cropping system has been developed at Yurimaguas, Peru, to serve as a transition technology between shifting and continuous cultivation for acid soils of the humid tropics. Principal features are slash-and-burn clearing, rotation of acid-tolerant upland rice and cowpea cultivars, maximum residue return, no tillage, and no lime or fertilizer applications. When yields decline as a result of increasing weed pressure and nutrient deficiencies, a kudzu fallow is grown for 1 year. Subsequent options include fertilizer-based continuous cultivation, pastures, or agroforestry. The system preserves some agroecosystem diversity and contributes toward a sustainable level of production and income for farmers in humid tropical regions.
Crystal Structure of α
1
: Implications for Protein Design
Authors: Hill Christopher P. , Anderson Daniel H. , Wesson Laura , DeGrado William F. , Eisenberg David
Published: October 2006

X-ray diffraction shows the structure of a synthetic protein model, formed from noncovalent self-association of a 12-residue peptide and of sulfate ions at low pH. This peptide is a fragment of a 16-residue polypeptide that was designed to form an amphiphilic α helix with a ridge of Leu residues along one helical face. By interdigitation of the leucines of four such helices, the design called for self-association into a four-α-helical bundle. The crystal structure (2.7 angstrom resolution;
R
factor = 0.215) reveals a structure more complex than the design, with both a tetramer and a hexamer. The α-helical tetramer with leucine interior has more oblique crossing angles than most four-α-helical bundles; the hexamer has a globular hydrophobic core of 12 leucine residues and three associated sulfate ions. Computational analysis suggests that the hexameric association is tighter than the tetrameric one. The consistency of the structure with the design is discussed, as well as the divergence.
Linking Earth, Ocean, and Air at the AGU
Authors: Kerr Richard A.
Published: October 2006

December's annual fall meeting of the American Geophysical Union presented another opportunity for specialists in everything from air pollution to the origin of Earth to immerse themselves in their narrow disciplines as well as cross into related areas. Overlap between disciplines can be peripheral but interesting, as in the examples below. The amount of salt in surface water can influence ocean circulation and thus climate, and water passing from the crust through sediments into the ocean can help control the concentration and composition of seawater salts.
AAAS Meeting: Science Smorgasbord with Snow
Authors: Booth William
Published: October 2006

Attendance at the AAAS annual meeting in Boston was at a record high for recent years, with 8700 people braving the half-finished Hynes Convention Center as well as wet snow and gale-force winds that closed Logan Airport on the first full day of the conference. Some hardy participants arrived by train. Others, including some of the speakers, were required to stay in Boston longer than they had planned. But perhaps the Soviets, of which there were 13 in a high-ranking delegation, were made to feel at home. The sessions on Soviet science were a major drawing card, but many other symposia, ranging from the science of protein folding to arms control, attracted large audiences. Some highlights follow.
Checking the Pulse of PitCon '88
Authors: Barnes Deborah M.
Published: October 2006

At PitCon '88—otherwise known as the Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spectroscopy—exhibited instruments capitalized on improvements in existing technology rather than novel concepts or design. This year's models feature increasing automation, particularly for aspects of sample presentation. The 1988 generation of so-called hyphenated systems emphasize a combination of techniques within the same work station—gas chromatography to detect and separate organic contaminants combined with mass spectrometry to identify them, for example. And in keeping with strict environmental standards, many companies are stressing the ability of their latest instruments to detect levels of environmental pollutants in the parts per billion, rather than parts per million, range.

PitCon '88 lured more than 25,000 participants to New Orleans for the week of 22 to 26 February. Approximately 830 companies displayed their wares at 2400 booths, and it took two separate facilities to house them. Specialized symposia on advances in spectroscopic, chromatographic, and electrochemical techniques increased in number as did the number of individual talks and posters. And new this year were three general interest symposia—identifying antiques by spectrochemical techniques, cholesterol, and drug testing in the workplace.
Induction of Chronic Myelogenous Leukemia in Mice by the P210

bcr/abl

Gene of the Philadelphia Chromosome
Authors: Daley George Q. , Van Etten Richard A. , Baltimore David
Published: October 2006

In tumor cells from virtually all patients with chronic myelogenous leukemia, the Philadelphia chromosome, a fusion of chromosomes 9 and 22, directs the synthesis of the P210

bcr/abl

protein. The protein-tyrosine kinase activity and hybrid structure of P210

bcr/abl

are similar to the oncogene product of the Abelson murine leukemia virus, P160

gag
/v-
abl

, which induces acute lymphomas. To determine whether P210

bcr/abl

can induce chronic myelogenous leukemia, murine bone marrow was infected with a retrovirus encoding P210

bcr/abl

and transplanted into irradiated syngeneic recipients. Transplant recipients developed several hematologic malignancies; prominent among them was a myeloproliferative syndrome closely resembling the chronic phase of human chronic myelogenous leukemia. Tumor tissue from diseased mice harbored the provirus encoding P210

bcr/abl

. These results demonstrate that P210

bcr/abl

expression can induce chronic myelogenous leukemia. Retrovirus-mediated expression of the protein provides a murine model system for further analysis of the disease.
U1 Small Nuclear RNA Genes Are Subject to Dosage Compensation in Mouse Cells
Authors: Mangin Marguerite , Ares Manuel , Weiner Alan M.
Published: October 2006

Multiple copies of a gene that encodes human U1 small nuclear RNA were introduced into mouse C127 cells with bovine papilloma virus as the vector. For some recombinant constructions, the human U1 gene copies were maintained extrachromosomally on the viral episome in an unrearranged fashion. The relative abundance of human and mouse U1 small nuclear RNA varied from one cell line to another, but in some lines human U1 RNA accounted for as much as one-third of the total U1. Regardless of the level of human U1 expression, the total amount of U1 RNA (both mouse and human) in each cell line was nearly the same relative to endogenous mouse 5S or U2 RNA. This result was obtained whether measurements were made of total cellular U1 or of only the U1 in small nuclear ribonucleoprotein particles that could be precipitated with antibody directed against the Sm antigen. The data suggest that the multigene families encoding mammalian U1 RNA are subject to some form of dosage compensation.
Building Black Holes: Supercomputer Cinema
Authors: Shapiro Stuart L. , Teukolsky Saul A.
Published: October 2006

A new computer code can solve Einstein's equations of general relativity for the dynamical evolution of a relativistic star cluster. The cluster may contain a large number of stars that move in a strong gravitational field at speeds approaching the speed of light. Unstable star clusters undergo catastrophic collapse to black holes. The collapse of an unstable cluster to a supermassive black hole at the center of a galaxy may explain the origin of quasars and active galactic nuclei. By means of a supercomputer simulation and color graphics, the whole process can be viewed in real time on a movie screen.
The Position of the Gulf Stream During Quaternary Glaciations
Authors: Keffer T. , Martinson D. G. , Corliss B. H.
Published: October 2006

Ocean general circulation theories predict that the position of the boundary between subtropical and subpolar gyres (and therefore the position of the Gulf Stream-North Atlantic Current system and the subpolar-subtropical front) is set by the line of zero "Ekman pumping," where there is no convergence or divergence of water in the directly wind-forced surface layer of the ocean. In the present-day North Atlantic Ocean this line runs southwest to northeast, from off the Carolinas to off Ireland. However, during the last ice age (18,000 years ago) the subpolar-subtropical boundary ran more zonally, directly toward Gibraltar. A numerical atmospheric general circulation model indicates that the field of Ekman pumping 18,000 years ago was modified by the presence of a continental ice cap more than 3 kilometers thick such that the line of zero Ekman pumping overlaid the paleogyre boundary. These results demonstrate that the presence of a thick continental ice sheet could have caused changes in sea surface temperatures in the North Atlantic during Quaternary glaciations by altering wind patterns.
Flood Basalt Volcanism During the Past 250 Million Years
Authors: Rampino Michael R. , Stothers Richard B.
Published: October 2006

A chronology of the initiation dates of major continental flood basalt volcanism is established from published potassium-argon (K-Ar) and argon-argon (Ar-Ar) ages of basaltic rocks and related basic intrusions. The dating is therefore independent of the biostratigraphic and paleomagnetic time scales. Estimated errors of the initiation dates of the volcanic episodes determined from the distributions of the radiometric ages are, approximately, plus or minus 4 percent. There were 11 distinct episodes during the past 250 million years. Sometimes appearing in pairs, the episodes have occurred quasi-periodically with a mean cycle time of 32 ± 1 (estimated, error of the mean) million years. The initiation dates of the episodes are close to the estimated dates of mass extinctions of marine organisms. Showers of impacting comets may be the cause.
Future Beam-Controlled Processing Technologies for Microelectronics
Authors: Kern Dieter P. , Kuech Thomas F. , Oprysko Modest M. , Wagner Al , Eastman Dean E.
Published: October 2006

Beam-controlled processes that utilize photons, electrons, ions, and molecules have become essential in the fabrication of microelectronics. These processes are required for the deposition, patterning, etching, and characterization of semiconductor, packaging, and processing-related materials that form the basis of the integrated circuit. Fabrication techniques demand an increasing precision as the physical size of the device structures shrink to submicrometer dimensions. In this article, selected examples of beam-controlled processes expected to be important in the microelectronics industry are described. The continued rapid advances in microelectronics technology that underlie the electronic information-processing industry require the continued development and refinement of these new techniques.
Insensitivity to Ethylene Conferred by a Dominant Mutation in
Arabidopsis thaliana
Authors: Bleecker Anthony B. , Estelle Mark A. , Somerville Chris , Kende Hans
Published: October 2006

Ethylene influences a number of developmental processes and responses to stress in higher plants. The molecular basis for the action of ethylene was investigated in mutants of
Arabidopsis thaliana
that have altered responses to ethylene. One mutant line, which has a dominant mutation at a locus designated
etr
, lacks a number of responses to ethylene that are present in the wild-type plant. These include inhibition of cell elongation, promotion of seed germination, enhancement of peroxidase activity, acceleration of leaf senescence, and feedback suppression of ethylene synthesis by ethylene. These diverse responses, which occur in different tissues of
Arabidopsis
, appear to share some common element in their transduction pathways—for example, a single receptor for ethylene. Results of ethylene binding experiments in vivo indicate that this receptor may be affected by the
etr
mutation.
A Novel Receptor Capable of Monitoring Applied Pressure in the Abdomen of an Insect
Authors: Chiang R. Gary , Davey K. G.
Published: October 2006

A pair of receptors, responding tonically to pressure applied internally, occurs on the ventral body wall of abdominal segments two to five in the adult of the blood-feeding insect,
Rhodnius prolixus.
These receptors are located in a region of the body wall subject to forces directly related to the size and movement of the stomach, an enlarged region of the midgut which stores the blood meal, and are therefore well suited for monitoring the degree of distension there. The initiation of many endocrinological processes in
Rhodnius
is known to be associated with the detection, over a period of several days, of abdominal distension, and these sensory receptors are capable of responding to abdominal distension for extended periods of time.
Expression and Modulation of Voltage-Gated Calcium Channels After RNA Injection in
Xenopus
Oocytes
Authors: Dascal Nathan , Snutch Terry P. , Lübbert Hermann , Davidson Norman , Lester Henry A.
Published: October 2006

Calcium ions flow into cells through several distinct classes of voltage-dependent calcium-selective channels. Such fluxes play important roles in electrical signaling at the cell membrane and in chemical signaling within cells. Further information about calcium channels was obtained by injecting RNA isolated from rat brain, heart, and skeletal muscle into
Xenopus
oocytes. Macroscopic currents through voltage-operated calcium channels were resolved when the endogenous calcium-dependent chloride current was blocked by replacing external calcium with barium and chloride with methanesulfonate. The resulting barium current was insensitive to tetrodotoxin but was completely blocked by cadmium or cobalt. With both heart and brain RNA at least two distinct types of calcium ion conductance were found, distinguishable by their time course and inactivation properties. In oocytes injected with heart RNA, the slowly inactivating component was selectively blocked by the calcium-channel antagonist nifedipine. Barium ion currents induced by heart RNA were modulated by isoproterenol, cyclic adenosine monophosphate, and acetylcholine.
Significance of "Tethyan" Fossils in the American Cordillera
Authors: Newton Cathryn R.
Published: October 2006

Equatorial faunas of the ancient Tethyan seaway, which extended from western Europe to southeastern Asia, comprise some of the most diverse marine taxa in the fossil record. Comparable or identical "Tethyan" species that occur far from the Tethyan seaway in Paleozoic and Mesozoic rocks of the North and South American Cordillera have long been considered as a major biogeographic anomaly. Two leading theories to account for the occurrence of these anomalous "Tethyan" faunas in the Cordillera are that they were transported long distances to the east on tectonic blocks (suspect terranes that originated near the Tethys) or that they migrated westward via undiscovered marine corridors through continental areas of Pangea. An alternative model is that these "Tethyan" fauna were pantropic species that extended with attenuated diversities into the eastern proto-Pacific Ocean. This pantropic model can better account for the distribution patterns of many Paleozoic and early Mesozoic "Tethyan" species in the American Cordillera and provides a steady state hypothesis against which the other models can be tested. The distribution of pre-Cretaceous "Tethyan" faunas is similar to the known pantropic distribution of many Cretaceous and Cenozoic tropical biotas. During the Cenozoic, taxa were most diverse in the Tethys and Indo-West Pacific regions but extended with attenuated diversity to many parts of the equatorial Pacific Ocean, including the west coasts of North and South America. The eastern Pacific occurrence of many Indo-West Pacific species provides a modern analog for the occurrence of many anomalous "Tethyan" fossils in the American Cordillera.
Reductive Dechlorination of Polychlorinated Biphenyls by Anaerobic Microorganisms from Sediments
Authors: Quensen John F. , Tiedje James M. , Boyd Stephen A.
Published: October 2006

Microorganisms from Hudson River sediments reductively dechlorinated most polychlorinated biphenyls (PCBs) in Aroclor 1242 under anaerobic conditions, thus demonstrating PCB dechlorination by anaerobic bacteria in the laboratory. The most rapid dechlorination was observed at the highest PCB concentration used; at 700 parts per million Aroclor, 53 percent of the total chlorine was removed in 16 weeks, and the proportion of mono- and dichlorobiphenyls increased from 9 to 88 percent. Dechlorination occurred primarily from the meta and para positions; congeners that were substituted only in the ortho position (or positions) accumulated. These dechlorination products are both less toxic and more readily degraded by aerobic bacteria. These results indicate that reductive dechlorination may be an important environmental fate of PCBs, and suggest that a sequential anaerobic-aerobic biological treatment system for PCBs may be feasible.
Active Polar Region on the Nucleus of Comet Halley
Authors: Reitsema H. J. , Delamere W. A. , Whipple F. L.
Published: October 2006

The images of the nucleus of comet Halley returned by the Giotto spacecraft reveal a number of active regions on the surface, one of which is near the expected location of the rotation pole. This feature is larger and brighter than other source regions, suggesting that the mechanism that drives this source is also different. At this active region near the rotation pole, the sun was circumpolar for a significant portion of the solar encounter. Continuous insolation heated the nucleus to greater depths than in other areas, producing the broad, active polar region.
Is There a U.S. Productivity Crisis?
Authors: Baumol William J.
Published: October 2006

Long-term data on U.S. productivity growth show its enormous contribution to U.S. living standards but do not confirm fears that the country is losing its manufacturing jobs to other countries. Growth in U.S. manufacturing productivity shows no downward trend; the U.S. share of world manufacturing employment is rising and, although the share of U.S. service sector jobs has increased, that in Japan has risen three times as quickly. The threats to U.S. productivity growth are mostly shorter term, for example, the federal deficit that absorbs savings which would otherwise be used to modernize and expand plant and equipment.
The Greenhouse Effect: Science and Policy
Authors: Schneider Stephen H.
Published: October 2006

Global warming from the increase in greenhouse gases has become a major scientific and political issue during the past decade. That infrared radiation is trapped by greenhouse gases and particles in a planetary atmosphere and that the atmospheric CO
2
level has increased by some 25 percent since 1850 because of fossil fuel combustion and land use (largely deforestation) are not controversial; levels of other trace greenhouse gases such as methane and chlorofluorocarbons have increased by even larger factors. Estimates of present and future effects, however, have significant uncertainties. There have also recently been controversial claims that a global warming signal has been detected. Results from most recent climatic models suggest that global average surface temperatures will increase by some 2° to 6°C during the next century, but future changes in greenhouse gas concentrations and feedback processes not properly accounted for in the models could produce greater or smaller increases. Sea level rises of 0.5 to 1.5 meters are typically projected for the next century, but there is a small probability of greater or even negative change. Forecasts of the distribution of variables such as soil moisture or precipitation patterns have even greater uncertainties. Policy responses range from engineering countermeasures to passive adaptation to prevention and a "law of the atmosphere." One approach is to implement those policies now that will reduce emissions of greenhouse gases and have additional societal benefits. Whether the uncertainties are large enough to suggest delaying policy responses is not a scientific question per se, but a value judgment.
Chemico-Viscous Remanent Magnetization in the Fe
3
O
4-y
Fe
2
O
3
System
Authors: Özdemir Özden , Dunlop David J.
Published: October 2006

The chemical remanent magnetization (CRM) acquired when single-domain size magnetite (Fe
3
0
4
) oxidizes to maghemite (γFe
2
O
3
) in a 50-microtesla field at a series of 13 temperatures from 100° to 656°C is of similar intensity to viscous remanent magnetization (VRM) acquired under the same field and temperature conditions by unoxidized magnetite. The remanences of the oxidized and unoxidized phases also have similar resistances to demagnetization. These similarities imply that the remanence of the oxidized material is a chemico-viscous remanent magnetization (CVRM) having some of the characteristics of both classic growth CRM and thermally activated VRM. At low temperatures in partially oxidized grains, VRM of the magnetite core and growth CRM of the maghemite surface layer contribute about equally to CVRM. Near the Curie point, intensity of CVRM increases to a Hopkinson-type peak. High-temperature CVRM is more resistant to demagnetization than the thermoremanent magnetization (TRM) produced from cooling through the Curie point.
Epitaxial Growth of Diamond Films on Si(111) at Room Temperature by Mass-Selected Low-Energy C
+
Beams
Authors: Robertson J. L. , Moss S. C. , Lifshitz Y. , Kasi S. R. , Rabalais J. W. , Lempert G. D. , Rapoport E.
Published: October 2006

Diamond films (∼0.7 micrometer thick) have been epitaxially grown on Si(111) substrates at room temperature with mass-selected 120-electronvolt C
+
ions. The diamond reflections observed in x-ray diffraction are well localized at their predicted positions, indicating that (i) the diamond(111) and (220) planes are parallel to the Si(111) and (220), respectively; (ii) the diamond rotational spread around its (111) normal is ∼1.7°; and (iii) the mosaic block size is ∼150 Å. The film growth is discussed in terms of subplantation—a shallow subsurface implantation model. This discovery is an important step toward diamond semiconductor devices.
The First High-Energy Neutrino Experiment
Authors: Schwartz Mel
Published: October 2006

This article describes the state of knowledge of weak interactions in 1960, the conception and implementation of the first high-energy neutrino experiment, and the not altogether unexpected result that the muon neutrino is different from the electron neutrino.
Star Formation in Irregular Galaxies
Authors: Hunter D. A. , Gallagher J. S.
Published: October 2006

Irregular galaxies can be viewed as laboratories for studying the processes of star formation. This class of galaxy, unlike the more familiar spiral galaxies, forms stars without spiral arms and does so from a chemically less-evolved interstellar medium. In this article the problems associated with star formation in irregular galaxies are outlined and their relevance to our understanding of star formation as a general astrophysical process is discussed.
Epitope Mapping by Chemical Modification of Free and Antibody-Bound Protein Antigen
Authors: Burnens André , Demotz Stéphane , Corradin Giampietro , Binz Hans , Bosshard Hans Rudolf
Published: October 2006

A monoclonal antibody bound to a protein antigen slows the rate of chemical modification of amino acid residues located at the epitope. By comparing the degree of acetylation of 18 lysine and 7 threonine residues in free and antibody-bound horse cytochrome c, a discontiguous, conformational epitope was characterized on this protein antigen. The new approach is particularly suitable to probe discontiguous and conformational epitopes, which are difficult to analyze by other procedures.
Substance P Activation of Rheumatoid Synoviocytes: Neural Pathway in Pathogenesis of Arthritis
Authors: Lotz Martin , Carson Dennis A. , Vaughan John H.
Published: October 2006

Several clinical features are consistent with nervous system involvement in the pathogenesis of rheumatoid arthritis. The neuropeptide substance P is one possible mediator of this interaction, since it can be released into joint tissues from primary sensory nerve fibers. The potential effects of the peptide on rheumatoid synoviocytes were examined. The results show that substance P stimulates prostaglandin E
2
and collagenase release from synoviocytes. Furthermore, synoviocyte proliferation was increased in the presence of the neuropeptide. Similar effects were observed with a truncated form of substance P. Synoviocytes were sensitive to very small doses of the neuropeptide (10
-9
M
), and its effects were inhibited by a specific antagonist. Thus, the specific stimulation of synoviocytes by the neuropeptide substance P represents a pathway by which the nervous system might be directly involved in the pathogenesis of rheumatoid arthritis.
Mutants of Bovine Pancreatic Trypsin Inhibitor Lacking Cysteines 14 and 38 Can Fold Properly
Authors: Marks Cara Berman , Naderi Hossein , Kosen Phyllis Anne , Kuntz Irwin D. , Anderson Stephen
Published: October 2006

It is a generally accepted principle of biology that a protein's primary sequence is the main determinant of its tertiary structure. However, the mechanism by which a protein proceeds from an unfolded, disordered state to a folded, relatively well-ordered, native conformation is obscure. Studies have been initiated to examine the "genetics" of protein folding, with mutants of bovine pancreatic trypsin inhibitor (BPTI) being used to explore the nature of the specific intramolecular interactions that direct this process. Previous work with BPTI chemically modified at cysteines 14 and 38 indicated that transient disulfide bond formation by these residues contributed to efficient folding at 25°C. In the present work, mutants of BPTI in which these cysteines were replaced by alanines or threonines were made and the mutant proteins were produced by a heterologous
Escherichia coli
expression system. At 25°C in vitro, the refolding behavior of these mutants was characterized by a pronounced lag. However, when expressed at 37°C in
E. coli
, or when refolded at 37° or 52°C in vitro, the mutant proteins folded readily into the native conformation, albeit at a rate somewhat slower than that exhibited by wild-type BPTI. These results indicate that, at physiological temperatures, BPTI lacking cysteines 14 and 38 can refold quantitatively.
Raf
, a
Trans
-Acting Locus, Regulates the α-Fetoprotein Gene in a Cell-Autonomous Manner
Authors: Vogt Thomas F. , Solter Davor , Tilghman Shirley M.
Published: October 2006

Genetic analysis provides an approach for identifying regulatory loci that govern the expression of specific genes within the context of the entire organism. Such analyses have defined two unlinked regulatory loci, termed
raf
and
Rif
, that modulate the levels of α-fetoprotein in liver. Of primary importance for the isolation and characterization of the
raf
product is to determine whether it is produced by the hepatocyte or whether it is produced by a different cell type. By means of analysis of α-fetoprotein expression in livers of embryo aggregation chimeras derived from mice of different
raf
genotypes it was possible to conclude that the product of the
raf
locus is expressed as a hepatocyte autonomous function that acts in
trans
to regulate the level of α-fetoprotein messenger RNA.
Cretaceous Cold-Seep Communities and Methane-Derived Carbonates in the Canadian Arctic
Authors: Beauchamp Benoit , Harrison J. Christopher , Nassichuk Walter W. , Krouse H. Roy , Eliuk Leslie S.
Published: October 2006

Lower Cretaceous cold-seep fossil assemblages have been found in the Canadian Arctic Archipelago. Serpulid worm tubes and bivalves are most abundant in these communities; in contrast, fossils are scarce in the surrounding strata. The fossils are contained in an isotopically light (δ
13
C = -25 to -50 per mil) carbonate rock groundmass that is interpreted to have formed from bacterial oxidation of methane. The rocks were deposited at intermediate depth (≤400 meters) in a cold marine environment; nearby normal faults may have provided a conduit for seeping methane and hydrogen sulfide needed to fuel chemosynthetic bacteria, and in turn, the higher life forms.
Geomagnetic Origin for Transient Particle Events from Nuclear Reactor-Powered Satellites
Authors: Share G. H. , Kurfess J. D. , Marlow K. W. , Messina D. C.
Published: October 2006

Transient events observed since 1980 by the Gamma-Ray Spectrometer experiment on the Solar Maximum Mission satellite (SMM) have been identified with radiation emitted from 18 different Soviet nuclear reactor—powered satellites. Most of these satellites are similar to Cosmos 954 and 1402 which reentered the atmosphere. Gamma radiation from these satellites was detected when they passed within about 400 to 500 kilometers of SMM. Positron annihilation line radiation (511 kiloelectron volts) and charged-particle events were detected when SMM encountered clouds of positrons and electrons emitted by these satellites and stored up to tens of minutes in the geomagnetic field. The rate of these events varied from about 1 in 5 days to over 30 per day and was strongly dependent on the operating altitudes of the Cosmos satellites and density of the upper atmosphere.
Reexamination of the Three-Dimensional Structure of the Small Subunit of RuBisCo from Higher Plants
Authors: Knight Stefan , Andersson Inger , Brändén Carl-Ivar
Published: October 2006

The structure of L
8
S
8
RuBisCo (where L is the large subunit and S is the small subunit) from spinach has been determined to a resolution of 2.8 ångstrom by using fourfold averaging of an isomorphous electron density map based on three heavy-atom derivatives. The structure of the S subunit is different from that previously reported for the tobacco S subunit in spite of 75 percent sequence identity. The elements of secondary structure, four antiparallel β strands and two α helices, are the same, but the topology and direction of the polypeptide chain through these elements differ completely. One of these models is clearly wrong. The spinach model has hydrophobic residues in the core between the α helices and β sheet as well as conserved residues in the subunit interactions. The deletion of residues 49 to 62 that is present in the
Anabaena
sequence removes a loop region in the spinach model. The positions of three mercury atoms in the heavy-atom derivatives agree with the assignment of side chains in the spinach structure.
High-Speed Chromosome Sorting
Authors: Gray J. W. , Dean P. N. , Fuscoe J. C. , Peters D. C. , Trask B. J. , van den Engh G. J. , Van Dilla M. A.
Published: October 2006

Dual-beam high-speed sorting has been developed to facilitate purification of chromosomes based on DNA staining with the fluorescent dyes Hoechst 33258 and chromomycin A3. Approximately 200 chromosomes per second of two types can be sorted from a suspension of chromosomes isolated from human lymphoblasts while fluorescent objects (chromosomes, debris fragments, chromosome clumps, and nuclei) are processed at the rate of about 20,000 per second. This sorting rate is approximately ten times that possible with conventional sorters. Chromosomes of a single type can be sorted with a purity of about 90 percent. DNA from the sorted chromosomes is suitable for construction of recombinant DNA libraries and for gene mapping.
Interpretation of Cloud-Climate Feedback as Produced by 14 Atmospheric General Circulation Models
Authors: Cess R. D. , Potter G. L. , Blanchet J. P. , Boer G. J. , Ghan S. J. , Kiehl J. T. , Le Treut H. , Li Z.-X. , Liang X.-Z. , Mitchell J. F. B. , Morcrette J.-J. , Randall D. A. , Riches M. R. , Roeckner E. , Schlese U. , Slingo A. , Taylor K. E. , Washington W. M. , Wetherald R. T. , Yagai I.
Published: October 2006

Understanding the cause of differences among general circulation model projections of carbon dioxide-induced climatic change is a necessary step toward improving the models. An intercomparison of 14 atmospheric general circulation models, for which sea surface temperature perturbations were used as a surrogate climate change, showed that there was a roughly threefold variation in global climate sensitivity. Most of this variation is attributable to differences in the models' depictions of cloud-climate feedback, a result that emphasizes the need for improvements in the treatment of clouds in these models if they are ultimately to be used as climatic predictors.
Surface Discharges on Natural Dielectrics in the Solar System
Authors: Campins Humberto , Krider E. Philip
Published: October 2006

When Earth-orbiting spacecraft are exposed to large fluxes of energetic charged particles, electric discharges occur on circuit boards, solar panels, and other dielectric surfaces. Large fluxes of energetic particles can produce such discharges on natural materials in the solar system. Surface discharges will occur under a variety of conditions, but particularly favorable environments are expected to occur within the magnetospheres of the giant planets; an example is the surface of Io.
Evidence for a Heterogeneous Upper Mantle in the Cabo Ortegal Complex, Spain
Authors: Girardeau Jacques , Ibarguchi José Ignaki Gil , Jamaa Nejib Ben
Published: October 2006

A well-preserved fragment of a heterogeneous upper mantle is present in the Cabo Ortegal Complex (Spain). This section is made of harzburgite containing a large volume of pyroxenite. The pyroxenite is concentrated in a layer 300 meters thick by 3 kilometers long. In this layer, ultramafic rocks, essentially pyroxenite (massive websterite and clinopyroxenite) and minor dunite, alternate without any rhythmicity. Part of this layering is of primary magmatic origin and possibly resulted from crystallization of magmas in dikes intruded into the host peridotite under mantle conditions.
Proteosome-Lipopeptide Vaccines: Enhancement of Immunogenicity for Malaria CS Peptides
Authors: Lowell George H. , Ballou W. Ripley , Smith Lynette F. , Wirtz Robert A. , Zollinger Wendell D. , Hockmeyer Wayne T.
Published: October 2006

Proteosomes are hydrophobic, membranous, multimolecular preparations of meningococcal outer membrane proteins that are also B cell mitogens. These characteristics suggested that proteosomes may serve as carrier proteins and adjuvants to enhance peptide immunogenicity. Although high titers of malaria circumsporozoite (CS) antibodies protect against malaria, vaccines thus far tested in humans have been insufficiently immunogenic to be clinically useful. Here it is shown that synthetic CS peptides hydrophobically complexed to proteosomes by way of lauroyl-cysteine become highly immunogenic in mice without other adjuvants. The high titers of antibodies produced and the safety of proteosomes in humans suggest that this novel system is widely applicable for the development of peptide vaccines to protect against many diseases.
Antiphosphotyrosine Recovery of Phospholipase C Activity After EGF Treatment of A-431 Cells
Authors: Wahl Matthew I. , Daniel Thomas O. , Carpenter Graham
Published: October 2006

A tenfold increase in phospholipase C activity specific for phosphatidylinositol 4,5-bisphosphate (PIP
2
) was immunopurified from extracts of A-431 epidermoid carcinoma cells stimulated with epidermal growth factor. This finding suggests a biochemical link between growth factor-stimulated tyrosine kinase activity and PIP
2
hydrolysis.
Spatially Resolved Organic Analysis of the Allende Meteorite
Authors: Zenobi Renato , Philippoz Jean-Michel , Zare Richard N. , Buseck Peter R.
Published: October 2006

The distribution of polycyclic aromatic hydrocarbons (PAHs) in the Allende meteorite has been probed with two-step laser desorption/laser multiphoton ionization mass spectrometry. This method allows direct in situ analysis with a spatial resolution of 1 square millimeter or better of selected organic molecules. Spectra from freshly fractured interior surfaces of the meteorite show that PAH concentrations are locally high compared to the average concentrations found by wet chemical analysis of pulverized samples. The data suggest that the PAHs are primarily associated with the fine-grained matrix, where the organic polymer occurs. In addition, highly substituted PAH skeletons were observed. Interiors of individual chondrules were devoid of PAHs at our detection limit (about 0.05 parts per million).