bluuebunny/crossref_metadata_2025 huggingface dataset:
MHC-Linked Protection from Diabetes Dissociated from Clonal Deletion of T Cells
Authors: Böhme Jan , Schuhbaur Brigitte , Kanagawa Osami , Benoist Christophe , Mathis Diane
Published: October 2006

The I-E molecule of the major histocompatibility complex (MHC) can prevent the spontaneous development of diabetes in nonobese diabetic (NOD) mice. The mechanism of this protection has been investigated by breeding wild-type and promoter-mutated E
α

k

transgenes onto the NOD genetic background. Animals carrying the various mutated transgenes expressed I-E on different subsets of immunocompetent cells, and thus cells important for the I-E protective effect could be identified. Although the wild-type transgene prevented the infiltration of lymphocytes into pancreatic islets, none of the mutants did. However, all of the transgenes could mediate the intrathymic elimination of T cells bearing antigen receptors with variable regions that recognize I-E. Thus, the I-E molecule does not protect NOD mice from diabetes simply by inducing the deletion of self-reactive T cells.
Orbits of the Small Satellites of Saturn
Authors: Synnott S. P. , Peters C. F. , Smith B. A. , Morabito L. A.
Published: October 2006

Orbital parameter values and associated uncertainties determined from Voyager 1 imaging data for the satellites 1980S1, 1980S3, 1980S6, 1980S26, 1980S27, and 1980S28 are presented.
Inhibition of T Cell Receptor Expression and Function in Immature CD4
+
cD8
+
Cells by CD4
Authors: Nakayama Toshinori , June Carl H. , Munitz Terry I. , Sheard Michael , McCarthy Susan A. , Sharrow Susan O. , Samelson Lawrence E. , Singer Alfred
Published: October 2006

Most immature CD4
+
CD8
+
thymocytes express only a small number of T cell receptor (TCR) molecules on their surface, and the TCR molecules they do express are only marginally capable of transducing intracellular signals. TCR expression and function was not intrinsically low in immature CD4
+
CD8
+
thymocytes, but was found to be actively inhibited by CD4-mediated signals. Indeed, release of CD4
+
CD8
+
thymocytes from CD4-mediated signals resulted in significant increases in both TCR expression and signaling function. These results suggest that, in CD4
+
CD8
+
cells developing in the thymus, increased TCR expression and function requires release from CD4-mediated inhibition.
Lateral P-Velocity Gradients near Major Strike-Slip Faults in California
Authors: Stierman Donald J. , Zappe Steve O.
Published: October 2006

The P-wave velocity in shallow crystalline rock decreases systematically from a normal value of about 5.5 kilometers per second 20 kilometers or more from the Garlock and San Andreas faults to less than 3 kilometers per second at distances of less than 2 kilometers from these faults. This lateral velocity gradient closely resembles the shear stress profile. It is proposed that the velocity gradient results from increased fracturing nearer these major strike-slip faults and that this fracturing dominates the response of the shallow crust to tectonic stress.
Hydrothermal Vent Clam and Tube Worm
13
C/
12
C: Further Evidence of Nonphotosynthetic Food Sources
Authors: Rau Greg H.
Published: October 2006

The stable carbon isotope ratios in clam mantle tissues taken from both Galápagos and 21°N hydrothermal vent sites were similar to the unusually low ratios of carbon-13 to carbon-12 previously reported for a Galápagos hydrothermal vent mussel. In marked contrast to these bivalves, vestimentiferan worm tissues from a Galápagos vent had isotope ratios that were higher than those of open ocean biota. These observations suggest that more than one nonpelagic and nonphotosynthetic carbon fixation pathway is of nutritional importance to vent animals, and that at least one of these pathways is common to two geographically separated vent sites.
Prokaryotic Cells in the Hydrothermal Vent Tube Worm
Riftia pachyptila
Jones: Possible Chemoautotrophic Symbionts
Authors: Cavanaugh Colleen M. , Gardiner Stephen L. , Jones Meredith L. , Jannasch Holger W. , Waterbury John B.
Published: October 2006

The existence of a symbiotic association between vestimentiferan tube worms from deep-sea hydrothermal vents and chemoautotrophic sulfur-oxidizing prokaryotes, based on histological and enzymatic evidence, is suggested.
Organically Bound Metals in a Solvent-Refined Coal: Metallograms for a Wyoming Subbituminous Coal
Authors: Taylor Larry T. , Hausler Douglas W. , Squires Arthur M.
Published: October 2006

Fractions of a solvent-refined coal that contain organically bound species of magnesium, calcium, titanium, iron, copper, or zinc have been isolated. The fractions represent a wide range of chemical types and molecular size. Their isolation is a step toward speciation.
Uranium Series Dating of Human Skeletal Remains from the Del Mar and Sunnyvale Sites, California
Authors: Bischoff James L. , Rosenbauer Robert J.
Published: October 2006

Uranium series analyses of human bone samples from the Del Mar and Sunnyvale sites indicate ages of 11,000 and 8,300 years, respectively. The dates are supported by internal concordancy between thorium-230 and protactinium-231 decay systems. These ages are significantly younger than the estimates of 48,000 and 70,000 years based on amino acid racemization, and indicate that the individuals could derive from the population waves that came across the Bering Strait during the last sea-level low.
Photochemical Oxidants Potentiate Yield Losses in Snap Beans Attributable to Sulfur Dioxide
Authors: Heggestad Howard E. , Bennett Jesse H.
Published: October 2006

Field-grown snap beans (
Phaseolus vulgaris
) were given recurring midday exposures to sulfur dioxide in open-top field chambers containing ambient photochemical oxidants. There was a linear correlation (correlation coefficient = –.99) between increasing concentrations of sulfur dioxide and the yields of snap beans. Synergism was indicated for the mixtures of ambient ozone plus sulfur dioxide, leading to threefold greater yield losses in nonfiltered air than in charcoal-filtered air (to remove the ozone). Even the lowest sulfur dioxide dose in nonfiltered air reduced the yields of Astro, a cultivar that exhibited no visible pollutant-induced foliar injury.
Science and Industry
Authors: Crawford Allan R.
Published: October 2006

Industry is concerned with basic science as the source of its technology, as the force of its philosophy of deductive thought, as its eye to the future, and as the impetus it provides for industrial innovation. Industry's strengthened advocacy of the support of basic science is essential for its future growth.
Agglutinin from Alfalfa Necessary for Binding and Nodulation by
Rhizobium meliloti
Authors: Paau Alan S. , Leps Walter T. , Brill Winston J.
Published: October 2006

A protein that specifically agglutinates
Rhizobium meliloti
, the alfalfa root nodule endosymbiont, has been purified from alfalfa seed. Material cross-reactive to antiserum prepared against the purified agglutinin is present in all alfalfa varieties that were tested but is absent in corn and other legumes not nodulated by
Rhizobium meliloti
. Studies with nonnodulating mutants of this microorganism incapable of binding to alfalfa roots suggest that the agglutinin is responsible for specific recognition between
Rhizobium meliloti
and alfalfa and that this recognition is an essential step in nodule formation.
Phase Transitions and Nonplanar Conformers in Crystalline
n
-Alkanes
Authors: Snyder Robert G. , Maroncelli Mark , Qi Song Ping , Strauss Herbert L.
Published: October 2006

Crystals of
n
-alkanes show a remarkable series of solid-solid phase transitions. In the odd
n
-alkanes C
25
, C
27
, and C
29
a previously unknown transition is found by both calorimetry and infrared spectroscopy. The ubiquitous presence of nonplanar conformations of the chains is shown by infrared spectroscopy. The nonplanar conformers constitute approximately half the molecules in the highest temperature solid phase of C
29
.
Epifluorescence and Video Analysis of Vacuole Motility and Development in Stomatal Cells of
Allium
Authors: Palevitz Barry A. , O'Kane Dennis J.
Published: October 2006

The vacuole in stomatal cells of
Allium
undergoes major changes in shape during differentiation, switching from a globular form in new guard mother cells to a network of interconnected tubules and chambers, and then back to a globular form as guard cells mature. In addition, vacuolar network elements exhibit characteristic movements and rearrangements
.
Caterpillar Setae: Insulation for an Ectotherm
Authors: Casey Timothy M. , Hegel Jeri R.
Published: October 2006

Gypsy moth caterpillars have long, soft setae distributed along the lateral portions of the body, but only short, stiff setae on the dorsal surface. Setae act as selective insulation for caterpillars by reducing the rates of convective heat exchange without affecting the rates of radiative heat exchange. Changes in posture abolish the effects of the setae by maximizing convection and minimizing radiant heat uptake.
The Coalescence of Two East Australian Current Warm-Core Eddies
Authors: Cresswell George R.
Published: October 2006

Two warm-core eddies coalesced in about 20 days as their centers rotated around a point on the contracting line that joined them. In the process of forming the new eddy, the subsurface isothermal-isohaline "signature" layer of one eddy was uplifted and somewhat depleted while that of the other was depressed.
Heat Production by Sediment: Ecological Significance
Authors: Pamatmat Mario M.
Published: October 2006

Sediments held at constant temperature evolve heat at rates that can be measured by direct calorimetry. The heat production rates decrease with depth from the surface layer. Total heat flux is an indication of the rate of degradation of potential chemical energy originally fixed by photosynthesis and represents benthic energy flow.
Controlling Cotton's Insect Pests: A New System
Authors: Adkisson Perry L. , Niles George A. , Walker J. Knox , Bird Luther S. , Scott Helen B.
Published: October 2006

Cotton is more heavily treated with insecticides than any other crop in the United States. In southern Texas, this heavy treatment resulted in insecticide-resistant strains of major pests which almost destroyed the industry in the late 1960's and early 1970's. An integrated insect control program based on new short-season cotton varieties and traditional cultural practices has restored production in the area. The new system has been widely implemented because it produces greater net returns by reducing the use of insecticides, fertilizer, and irrigation.
Volcanic Gases in the April 1979 Soufriere Eruption
Authors: Cronn Dagmar R. , Nutmagul Winai
Published: October 2006

Six gas samples from the 17 April 1979 Soufriere eruption plume were analyzed for carbonyl sulfide, carbon disulfide, carbon monoxide, carbon dioxide, methane, nitrous oxide, fluorocarbon-11, fluorocarbon-12, methyl chloroform, and carbon tetrachloride. Only carbon monoxide, carbon dioxide, carbonyl sulfide, and carbon disulfide were found to have increased mixing ratios as compared with those in clean tropospheric air, but the increases were not sufficient to contribute greatly to the global budgets of these four components.
Antibodies to Clathrin Inhibit Endocytosis But Not Recycling to the Trans Golgi Network in Vitro
Authors: Draper Rockford K. , Goda Yukiko , Brodsky Frances M. , Pfeffer Suzanne R.
Published: October 2006

Mannose 6-phosphate receptors carry newly synthesized lysosomal enzymes from the trans Golgi network (TGN) to prelysosomes and then return to the TGN to carry out another round of lysosomal enzyme delivery. Although clathrin-coated vesicles mediate the export of mannose 6-phosphate receptors from the TGN, nothing is known about the transport vesicles used to carry these receptors back to the TGN. Two different in vitro assays used in this study show that an antibody that interferes with clathrin assembly blocks receptor-mediated endocytosis of transferrin, but has no effect on the recycling of the 300-kilodalton mannose 6-phosphate receptor from prelysosomes to the TGN. These results suggest that the transport of mannose 6-phosphate receptors from prelysosomes to the TGN does not involve clathrin.
The Organization of Work in China's Communes
Authors: Gonzalez Nancie L.
Published: October 2006

There has been speculation that China's communes are undergoing drastic changes and that work patterns are being redefined so as to make individuals or households the basic production units in agriculture. A brief but intensive anthropological study in 17 communes suggests that, although collectivization is still considered to be the ideal form in more advanced areas, responsibility for some tasks is being assigned to households in some poorer communes in an effort to increase production and farm incomes and enhance development. Significant permanent improvements seem hinged to the rise of rural industry, which increasingly rewards individual efforts within the context of a basically collective social organization. The system is complex and is more flexible than it has been in the recent past.
Actinide Organometallic Chemistry
Authors: Marks Tobin J.
Published: October 2006

The stoichiometric and catalytic chemistry of metal-organic compounds having actinide-to-carbon bonds is in a stage of rapid growth. Chemical, structural, and bonding characteristics have been identified which differ in interesting and informative ways from those of
d
-block transition element compounds.
Homologous Recombination and Stable Transfection in the Parasitic Protozoan
Trypanosoma brucei
Authors: Lee Mary Gwo-Shu , Van der Ploeg Lex H. T.
Published: October 2006

Development of methods for the manipulation of the genomes of parasitic protozoa will lead to enhanced understanding of parasite biology and host-parasite relationships. Efficient gene transfer and targeted integration by homologous recombination were achieved in the parasitic protozoan
Trypanosoma brucei
, the causative agent of sleeping sickness. An expression vector with the neomycin phosphotransferase gene (
neo
), under the control of a procyclic acidic repetitive protein (PARP) gene promoter, was targeted into an intergenic region in βα-tubulin-gene tandem array. Sixteen copies of
neo
were found in a tandem array in one of the transfectants where the PARP promoter controlled α-amanitin-resistant transcription of
neo
, whereas transcription of tubulin genes remained α-amanitin-sensitive.
Interoceanic Differences in the Reproduction of Coral-Reef Fishes
Authors: Thresher R. E.
Published: October 2006

Eggs of demersal spawning coral-reef fishes of the tropical western Atlantic are smaller than those of related species in the western Pacific. Decreased egg volume may result in increased fecundity per unit body weight of Atlantic species, a factor that may underlie apparent differences in the stability of the respective coral-reef fish communities.
Some Emerging Applications of Lasers
Authors: Christensen C. Paul
Published: October 2006

New laser applications are emerging in almost every field of science. Many of them show both a high degree of technical sophistication and broad practical utility. The progress being made is illustrated by specific applications in three areas: laser microchemistry, optical disk data storage, and remote sensing.
Developments in Electrochemical Instrumentation
Authors: Osteryoung Janet
Published: October 2006

Commercial electrochemical instrumentation is in a state of mature development. Microprocessors are used mainly as devices for data handling, and there are no commercial computer-based instruments. Progress in the science and proliferation of applications depend on noninstrumental factors such as electrode materials.
A Fossil Noctuid Moth Egg from the Late Cretaceous of Eastern North America
Authors: Gall Lawrence F. , Tiffney Bruce H.
Published: October 2006

A moth egg assignable to the family Noctuidae (Lepidoptera) is described from 75-million-year-old sediments from Martha's Vineyard, Massachusetts. This sample, which extends the fossil record of this family and modern heteroneuran moths back to the Cretaceous, may provide insight into the coevolution of moths and flowering plants, as well as have implications for the evolution of bats.
Precision Measurements and Fundamental Constants
Authors: Pipkin Francis M. , Ritter Rogers C.
Published: October 2006

Recent developments in the techniques for making precision measurements and their use in the determination of the fundamental constants are reviewed. Particularly noteworthy developments are clocks with high stability, the proposed redefinition of the meter in terms of the standard for time, and the increased precision with which electrical standards can be maintained. The relevance of precision measurements to tests of general relativity is briefly discussed.
Ingested Mineral Fibers: Elimination in Human Urine
Authors: Cook Philip M. , Olson Gayle F.
Published: October 2006

Sediment in human urine examined by transmission electron microscopy contains amphibole fibers which originate from the ingestion of drinking water contaminated with these mineral fibers. The ingestion of filtered water results in the eventual disappearance of amphibole fibers from urine. These observations provide the first direct evidence for the passage of mineral fibers through the human gastrointestinal mucosa under normal conditions of the alimentary canal.
Norwegian Remote Sensing Experiment in a Marginal Ice Zone
Authors:   NORSEX Group
Published: October 2006

The Norwegian Remote Sensing Experiment in the marginal ice zone north of Svalbard took place in fall 1979. Coordinated passive and active microwave measurements were obtained from shipborne, airborne, and satellite instruments together with in situ observations. The obtained spectra of emissivity (frequency range, 5 to 100 gigahertz) should improve identification of ice types and estimates of ice concentration. Mesoscale features along the ice edge were revealed by a 1.215-gigahertz synthetic aperture radar. Ice edge location by the Nimbus 7 scanning multichannel microwave radiometer was shown to be accurate to within 10 kilometers.
When Is an Island Community in Equilibrium?
Authors: Simberloff Daniel
Published: October 2006

To determine whether the number of species in a biota is in equilibrium requires a colonization model. In a simple Markov model, each species' extinction and immigration probabilities are estimated independently from available data. For one inland and two island avifaunas, a simulation with these probabilities shows that the trajectories of species richness through time do not manifest the regulatory tendencies expected if species interactions cause species richness to be continuously redressed toward an equilibrium.
Space-Filling Models of Kinase Clefts and Conformation Changes
Authors: Anderson C. M. , Zucker F. H. , Steitz T. A.
Published: October 2006

Space-filling models of yeast hexokinase, adenylate kinase, and phosphoglycerate kinase drawn by computer clearly portray the bilobal character of these phosphoryl transfer enzymes, and the deep cleft which is formed between the lobes. A dramatic conformational change occurs in hexokinase as glucose binds to the bottom of the cleft, which causes the two lobes of hexokinase to come together. A substrate-induced closing of the active site cleft is postulated to occur in other kinases as well. This change may provide a mechanism by which some of these enzymes reduce their inherent adenosine triphosphatase activity and could be a general requirement of the kinase reaction.
A Morphogenetically Competent Soybean Suspension Culture
Authors: Christianson M. L. , Warnick D. A. , Carlson P. S.
Published: October 2006

A morphogenetically competent suspension culture was derived from embryonic axes of
Glycine max
cv. Mitchell. The cultural history included visual selection for nonfriable, embryo-like structures, recurrent selection in a regime of 2,4-dichlorophenoxyacetic acid exposure and withdrawal, and the replacement of the nitrogen in a Murashige and Skoog salts-based medium with 20 millimolar ammonium citrate. The embryoids produced by this suspension are capable of completing plantlet development. The suspension can be maintained by serial subculture.
Determination of Thermal Histories of Archeological Cereal Grains with Electron Spin Resonance Spectroscopy
Authors: Hillman G. C. , Robins G. V. , Oduwole D. , Sales K. D. , McNeil D. A. C.
Published: October 2006

The thermal histories of archeological cereal grains were examined by electron spin resonance spectroscopy. Studies with modern samples of heated cereal grain showed that the parameters of the electron spin resonance signal characterize the maximum temperature to which the sample had previously been heated. This technique has applicability in archeology and other disciplines.
Guidance of Peripheral Pioneer Neurons in the Grasshopper: Adhesive Hierarchy of Epithelial and Neuronal Surfaces
Authors: Berlot John , Goodman Corey S.
Published: October 2006

An important question in developmental neurobiology is how a neuron finds its way over long distances to its correct target during embryogenesis. Peripheral pioneer neurons in insect embryos have been used for study because of the relative simplicity of the early embryonic appendages, and the accessibility of the identified neurons whose growth cones traverse this terrain. The data presented suggest an adhesive hierarchy of both epithelial and neuronal surfaces that guides the first growth cones from the appendages of the grasshopper embryo.
Chemistry and Chemical Intermediates in Supersonic Free Jet Expansions
Authors: Miller Terry A.
Published: October 2006

Short-lived intermediates often play key roles in determining the course of chemical reactions. Recently the combination of sophisticated laser techniques and supersonic free jet expansions has offered new insight into the structure and reactivity of such intermediates. Because of their extremely reactive nature the intermediates are produced in situ in the expansion. The free jet expansion provides cooling of the intermediates to very low temperatures, so that even complex organic free radicals and molecular ions can be identified and characterized. Radical-radical reactions and ionic cluster formation likewise proceed in the expansion and can be monitored by laser spectroscopy.
The Structure of Abelsonite
Authors: Storm Carlyle B. , Krane Jostein , Skjetne Tore , Telnaes Nils , Branthaver Jan F. , Baker Earl W.
Published: October 2006

Abelsonite, a C
31
nickel-porphyrin of the deoxophylloerythroetioporphyrin type, is shown to have methyl groups in the 2, 3, 7, 12, and 18 positions and ethyl groups in the 8 and 17 positions by high-resolution, high-field
1
H nuclear magnetic resonance and nuclear Overhauser effect studies. Removal of the nickel by treatment with methanesulfonic acid permitted confirmation of the structure on the free base porphyrin and demonstrated structural integrity under the conditions required for demetallation. The structure is best accounted for geochemically by the hypothesis that abelsonite is derived from a chlorophyll.
Arginine Decarboxylase and Polyamines Required for Embryogenesis in the Wild Carrot
Authors: Feirer Russell P. , Mignon Gail , Litvay John D.
Published: October 2006

Embryogenic cultures of
Daucus carota
treated with 1 millimolar α-difluoromethylarginine, a specific inhibitor of arginine decarboxylase, exhibited nearly a 50 percent reduction in embryo formation compared with controls. Putrescine and spermidine concentrations in the treated cells were greatly reduced. Addition of putrescine, spermidine, or spermine to the culture medium restored embryogenesis in the treated cultures. Embryogenesis was not significantly affected by α-difluoromethylornithine, an inhibitor of ornithine decarboxylase. These results suggest that polyamines have a major function in plant embryo development and that the wild carrot synthesizes polyamines through the biosynthetic pathway involving arginine decarboxylase rather than ornithine decarboxylase.
The Energetic Basis of Specificity in the Eco RI Endonuclease—DNA Interaction
Authors: Lesser David R. , Kurpiewski Michael R. , Jen-Jacobson Linda
Published: October 2006

High sequence selectivity in DNA-protein interactions was analyzed by measuring discrimination by Eco RI endonuclease between the recognition site GAATTC and systematically altered DNA sites. Base analogue substitutions that preserve the sequence-dependent conformational motif of the GAATTC site permit deletion of single sites of protein-base contact at a cost of +1 to +2 kcal/mol. However, the introduction of any one incorrect natural base pair costs +6 to +13 kcal/mol in transition state interaction energy, the resultant of the following interdependent factors: deletion of one or two hydrogen bonds between the protein and a purine base; unfavorable steric apposition between a group on the protein and an incorrectly placed functional group on a base; disruption of a pyrimidine contact with the protein; loss of some crucial interactions between protein and DNA phosphates; and an increased energetic cost of attaining the required DNA conformation in the transition state complex. Eco RI endonuclease thus achieves stringent discrimination by both "direct readout" (protein-base contacts) and "indirect readout" (protein-phosphate contacts and DNA conformation) of the DNA sequence.
Replication in Plastic of Three-Dimensional Fossils Preserved in Indurated Clastic Sedimentary Rocks
Authors: Zapasnik Henryk T. , Johnston Paul A.
Published: October 2006

A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves three steps: the dissolution of carbonate in fossiliferous rocks with hydrochloric acid, impregnation of resulting voids with liquid plastic, and dissolution of the rock matrix with hydrofluoric acid, leaving a concentrate of plastic-replaced fossils.
Induced Resistance of Cotton Seedlings to Mites
Authors: Karban Richard , Carey James R.
Published: October 2006

Mite populations grew more rapidly on new growth of cotton seedlings that had never been exposed to mites than on new growth of plants whose cotyledons had been previously exposed to them. Experiments in which a second mite introduction on the exposed plants involved a different mite species produced this same result. The substance or substances responsible for the response are transported systemically among leaves of cotton seedlings.
Atmospheric Emissions Photometric Imaging Experiment
Authors: Mende S. B. , Swenson G. R. , Clifton K. S.
Published: October 2006

The atmospheric emissions photometric imaging experiment was flown on Spacelab 1 to study faint natural and artificial atmospheric emission phenomena. The instrument imaged optical emission in the region 2000 to 7500 angstroms with a television system consisting of two optical channels, one wide-angle and one telephoto. A third optical channel imaged onto the photochathode of a microchannel plate photomultiplier tube that has 100 discrete anodes. A hand-held image intensifier camera with an objective grating permitted spectral analysis of the earth's airglow and the shuttle glow. Preliminary data show magnesium ion emission features in the lower ionosphere as well as the spacecraft glow spectrum.
Interstratified Clays as Fundamental Particles
Authors: Nadeau P. H. , Wilson M. J. , McHardy W. J. , Tait J. M.
Published: October 2006

Materials representing common interstratified clay minerals are shown to be composed of aggregates of fundamental particles. Transmission electron microscopy and x-ray diffraction demonstrate that the x-ray diffraction characteristics of a wide range of interstratification can be modeled experimentally by utilizing materials containing only three types of particles. The data have been incorporated into a new model that regards interstratified clay minerals as populations of fundamental particles whose x-ray diffraction patterns result from interparticle diffraction.
Computer Simulations of the Atmospheric Chemistry of Sulfate and Nitrate Formation
Authors: Seigneur Christian , Saxena Pradeep , Roth Philip M.
Published: October 2006

Simulations of the atmospheric chemistry of sulfate and inorganic nitrate formation have been carried out by means of a detailed gas phase—liquid phase chemical kinetic mechanism. Consideration has been given to the effect of changes in sulfur dioxide, nitrogen oxides, and reactive hydrocarbon concentrations on sulfate and nitrate formation for conditions typical of the midwestern and northeastern United States. The results indicate significant nonlinearities in the chemistry of acid formation, particularly between sulfur dioxide and sulfate concentrations.
Flying Squirrels Are Monophyletic
Authors: Thorington Richard W.
Published: October 2006

Seven genera of flying squirrels share five characters of wrist anatomy, which form a functional complex associated with the support of the patagium. In these characters, they differ from all genera of tree and ground squirrels examined. Among mammals, gliding membranes have evolved independently in several other groups. The manner of attachment of the patagium to the forelimb is different in each and demonstrates five morphologies differing from that of flying squirrels. This complex wrist anatomy of flying squirrels provides evidence that gliding evolved only once among squirrels and that the flying squirrels are a monophyletic group.
Requirement of
ets
-2 Expression for
Xenopus
Oocyte Maturation
Authors: Chen Zhang-Qun , Burdett Laura A. , Seth Arun K. , Lautenberger James A. , Papas Takis S.
Published: October 2006

A molecular clone of the
Xenopus laevis
ets-2
gene was isolated from an oocyte complementary DNA library. The amount of messenger RNA (mRNA) in each oocyte or embryo was almost constant during oogenesis and was maintained until the blastula stage of embryonic development, indicating that the observed 3.2-kilobase transcript is a maternal message. The only normal adult tissue in which
ets-2
mRNA was detected was the ovary. Injection of antisense oligonucleotides homologous to the
ets-2
sequence into oocytes led to degradation of the mRNA and blocked hormone-induced germinal vesicle breakdown. The
ets-2
product is thus required for the meiotic maturation of
Xenopus
oocytes.
Deep Seismic Sounding with Nuclear Explosives in the Soviet Union
Authors: Scheimer J. F. , Borg I. Y.
Published: October 2006

A large geophysical program of exploration that uses deep seismic sounding has been under way in the Soviet Union for decades. Underground nuclear explosives have been used as strong seismic sources since 1971. The wide spacing between these seismic sources—for example, 500 kilometers—has permitted seismic exploration of inaccessible areas in traverses up to 3000 kilometers in length. During the same time an ultra-deep drilling program has also been under way. The data gathered have been used to elucidate details of the crust as well as to describe layering and inhomogeneities in the underlying mantle. By Soviet account, deep seismic sounding has been instrumental in confirming the existence of numerous sedimentary structures containing oil and gas fields in western and eastern Siberia.
Space Research in the Era of the Space Station
Authors: Frost Kenneth J. , McDonald Frank B.
Published: October 2006

With the continuing flights and increasing capabilities of the space shuttle, and with the design and development of a space station, there will be a significant increase in our space research capabilities during the 1990's. Ways in which the nation's space science program may evolve in response to these developments are described.
Do Frogs Communicate with Seismic Signals?
Authors: Lewis Edwin R. , Narins Peter M.
Published: October 2006

Male white-lipped frogs exhibit conspicuous behavioral responses to calling conspecific males that are nearby but out of view. Since the calls often are accompanied by strong seismic signals (thumps), and since the male white-lipped frog exhibits the most acute sensitivity to seismic stimuli yet observed in any animal, these animals may use seismic signals as well as auditory signals for intraspecific communication.
Rapid Switching of Plant Gene Expression Induced by Fungal Elicitor
Authors: Cramer Carole L. , Ryder Thomas B. , Bell John N. , Lamb Chris J.
Published: October 2006

The pattern of messenger RNA synthesis in suspension-cultured bean cells (
Phaseolus vulgaris
L.) was analyzed by blot hybridization and in vitro translation of newly synthesized messenger RNA. The RNA was separated from preexisting RNA by organomercurial affinity chromatography after in vivo labeling with 4-thiouridine. The elicitor induced the synthesis of messenger RNA's encoding phenylalanine ammonia-lyase, chalcone synthase, and chalcone isomerase, three enzymes of phenylpropanoid metabolism involved in the synthesis of isoflavonoidderived phytoalexins. This is part of a rapid and extensive change in the pattern of messenger RNA synthesis directing production of a set of proteins associated with expression of disease resistance.
New Ways to Study Developmental Genes in Spore-Forming Bacteria
Authors: Youngman Philip , Zuber Peter , Perkins John B. , Sandman Kathleen , Igo Michele , Losick Richard
Published: October 2006

The regulated activation of numerous sets of genes in multiple chromosomal locations is a hallmark of cellular differentiation in both eukaryotes and prokaryotes. Certain species of bacteria that experience complex developmental cycles are especially attractive as systems in which to study the mechanisms of this kind of gene regulation because they are highly amenable to both biochemical and genetic approaches.
Bacillus subtilis
, which undergoes extensive cellular differentiation when it sporulates, is one such system. Many new methods are now available in this Gram-positive species for identifying, manipulating, and studying the regulation of genes involved in spore formation, including the use of transposable genetic elements that create gene fusions in vivo as an automatic consequence of insertions into genes.
Computer Applications in the Humanities
Authors: Raben Joseph
Published: October 2006

The earliest and still most prevalent use of computers in the humanities is the compilation of concordances, rationalized vocabulary lists for literary works. The residue of these efforts has created the potential for extensive databases of natural-language text for a wide range of studies and for instruction. As yet, however, computer-aided instruction has focused on mechanical skills, like spelling and grammar. With rapid advances in storage (like videodisks) and in communications between computers, humanists are finding a challengingly altered environment in which to study and teach.
Characterization of Io's Volcanic Activity by Infrared Polarimetry
Authors: Goguen Jay D. , Sinton William M.
Published: October 2006

The thermal emission from Io's volcanic hot spots is linearly polarized. Infrared measurements at 4.76 micrometers show disk-integrated polarization as large as 1.6 percent. The degree and position angle of linear polarization vary with Io's rotation in a manner characteristic of emission from a small number of hot spots. A model incorporating three hot spots best fits the data. The largest of these hot spots lies to the northeast of Loki Patera, as mapped from Voyager, and the other spot on the trailing hemisphere is near Ra Patera. The hot spot on the leading hemisphere corresponds to no named feature on the Voyager maps. The value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur.
Strained-Layer Epitaxy of Germanium-Silicon Alloys
Authors: Bean John C.
Published: October 2006

Despite the dominant position of silicon in semiconductor electronics, its use is ultimately limited by its incompatibility with other semiconducting materials. Strained-layer epitaxy overcomes problems of crystallographic compatibility and produces high-quality heterostructures of germanium-silicon layers on silicon. This opens the door to a range of electronic and photonic devices that are based on bandstructure physics.
Local Influences on Shear-Flow Turbulence in the Equatorial Ocean
Authors: Moum J. N. , Caldwell D. R.
Published: October 2006

A 12-day series of 1749 profiles of turbulent kinetic energy dissipation above the equatorial undercurrent at 140° west showed that, in the upper 110 meters of the ocean, the dissipation radically decreased during the solar heating period each day. Daily averages were linearly related to the local wind power. When integrated over the depth range of 10 to 110 meters, the dissipation was 10.6 ergs per square centimeter per second or 0.92 ± 0.10 percent of the wind power, a proportion not substantially different from those found in mid-latitude surface mixed layers. These results suggest that much of the energy dissipated above the equatorial undercurrent may be extracted directly from the local wind.
Rates of Elementary Reactions: Measurement and Applications
Authors: Kaufman Frederick
Published: October 2006

Modern experimental techniques for measuring rate parameters of elementary reactions have transformed the field of gas-phase reaction kinetics from one of indirect inference to one of direct determination. Recent progress in the principal techniques is described, a few examples are given of the hundreds of elementary reactions for which rate information has become available, and comparison with reaction rate theory is briefly discussed. Some generalizations regarding the dependence of rate parameters on structure and thermodynamics are drawn, and successful applications to atmospheric and combustion modeling and measurement are presented.
Origin of the Sudbury Complex by Meteoritic Impact: Neodymium Isotopic Evidence
Authors: Faggart Billy E. , Basu Asish R. , Tatsumoto Mitsunobu
Published: October 2006

Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 ± 21 × 10
6
years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.
The MerR Metalloregulatory Protein Binds Mercuric Ion as a Tricoordinate, Metal-Bridged Dimer
Authors: Helmann John D. , Ballard Barry T. , Walsh Christopher T.
Published: October 2006

Bacterial MerR proteins are dimeric DNA-binding proteins that mediate the Hg(II)-dependent induction of mercury resistance operons. Site-directed mutagenesis of the
Bacillus
sp. RC607 MerR protein reveals that three of four Cys residues per monomer are required for Hg(II) binding at the single high-affinity binding site. Inactive mutant homodimers can exchange subunits to form heterodimers active for Hg(II) binding. Studies of a heterodimer retaining only three of eight cysteine residues per dimer reveal that Cys
79
in one subunit and Cys
114
and Cys
123
in the second subunit are necessary and sufficient for high-affinity Hg(II) binding in an asymmetric, subunit bridging coordination complex.
Postindustrial Melanism in the Peppered Moth
Authors: Cook L. M. , Mani G. S. , Varley M. E.
Published: October 2006

New data show the geographical pattern of frequency of the melanic morph
carbonaria
of the peppered moth,
Biston betularia
, in 1983-84. These frequencies are compared with data from 1952 to 1970. After 20 years of smoke control, the area of high melanic frequency has contracted to the northeast. The change indicates a disadvantage to
carbonaria
of about 12 percent compared with 20 years ago. Computer simulations, which do not include the assumption of heterozygote advantage, provide a good match to the surface for the period 1952 to 1970, and also the 1983-84 surface. Experiments on visual predation have been criticized as giving unrepresentative estimates of selection but they permit satisfactory simulations to be made.
In Situ Measurements of Chemical Distributions in a Deep-Sea Hydrothermal Vent Field
Authors: Johnson Kenneth S. , Beehler Carl L. , Sakamoto-Arnold Carole M. , Childress James J.
Published: October 2006

Large changes in the concentration of sulfide around a hydrothermal vent in the Galápagos Rift provide direct evidence for the consumption of sulfide by the organisms of the vent community. These changes were detected with a new chemical analyzer capable of measuring silicate, sulfide, oxygen, and temperature on the sea floor at depths of 2500 meters. More than 10,000 measurements showed systematic variations in the sulfide and oxygen concentrations due to biogenic oxidation of sulfide in the hydrothermal solutions. Silicate concentration was highly correlated with temperature, but different trends were observed at different locations.
Radio Studies of Extragalactic Supernovae
Authors: Weiler Kurt W. , Sramek Richard A. , Panagia Nino
Published: October 2006

Some exploding stars (supernovae) are powerful emitters of centimeter radio radiation. Detailed observations have shown that these supernovae quickly become detectable in the radio range, first at shorter wavelengths (higher frequencies) and later at progressively longer and longer wavelengths (lower frequencies). This part of the phenomenon appears to be well explained by a monotonic decrease in the amount of ionized material surrounding the radio-emitting regions as the shock from the explosion travels outward. The radio emission itself is of a nonthermal, synchrotron origin, as is the case in most bright cosmic radio sources. Once the absorption effects become negligible, the radio intensity declines with time until reaching the detection limit of the telescope. Models suggest that the absorbing material originates in a dense wind of matter lost by the supernova progenitor star, or by its companion if it is in a binary system, in the last stages of evolution before the explosion. The synchrotron radio emission can be generated either externally by the shock wave from the explosion propagating through this same high density stellar wind or internally by a rapidly rotating neutron star, which is the collapsed core of the exploded star. Present results appear to favor the former model for at least the first several years after the supernova explosion, although the latter model remains viable.
Antarctic Mesopelagic Micronekton: Evidence from Seabirds That Pack Ice Affects Community Structure
Authors: Ainley D. G. , Fraser W. R. , Sullivan C. W. , Torres J. J. , Hopkins T. L. , Smith W. O.
Published: October 2006

Through a multidisciplinary project (AMERIEZ), with an unusual complement of components, previously unknown temporal and spatial dimensions to the structure of Antarctic epipelagic and mesopelagic communities were revealed. In late spring, an abundance of crustacean species thought to occur only below 300 meters was detected in ice-covered surface waters. Evident in ice-free waters were the expected occurrence patterns of these normally nonmigratory mesopelagic organisms. Where the pack was consolidated and little light penetrated to depth, primary and secondary production was confined to ice floes, and the physical environment immediately beneath the ice was reminiscent of a mesopelagic one. This suite of characteristics possibly explains why the crustaceans resided at the surface.
Anisotropy of the Cosmic Blackbody Radiation
Authors: Wilkinson David T.
Published: October 2006

The universe is filled with thermal radiation having a current temperature of 2.75 K. Originating in the very early universe, this radiation furnishes strong evidence that the Big Bang cosmology best describes our expanding universe from an incredibly hot, compacted early stage until now. The model can be used to extrapolate our physics backward in time to predict events whose effects might be observable in the 2.75 K radiation today. The spectrum and isotropy are being studied with sophisticated microwave radiometers on the ground, in balloons, and in satellites. The results are as predicted by the simple theory: the spectrum is that of a blackbody (to a few percent) and the radiation is isotropic (to 0.01 percent) except for a local effect due to our motion through the radiation. However, a problem is emerging. Primordial fluctuations in the mass density, which later became the great clusters of galaxies that we see today, should have left an imprint on the 2.75 K radiation—bumpiness on the sky at angular scales of about 10 arc minutes. They have not yet been seen.
Energetic Charged Particles in the Uranian Magnetosphere
Authors: Stone E. C. , Cooper J. F. , Cummings A. C. , McDonald F. B. , Trainor J. H. , Lal N. , McGuire R. , Chenette D. L.
Published: October 2006

During the encounter with Uranus, the cosmic ray system on Voyager 2 measured significant fluxes of energetic electrons and protons in the regions of the planet's magnetosphere where these particles could be stably trapped. The radial distribution of electrons with energies of megaelectron volts is strongly modulated by the sweeping effects of the three major inner satellites Miranda, Ariel, and Umbriel. The phase space density gradient of these electrons indicates that they are diffusing radially inward from a source in the outer magnetosphere or magnetotail. Differences in the energy spectra of protons having energies of approximately 1 to 8 megaelectron volts from two different directions indicate a strong dependence on pitch angle. From the locations of the absorption signatures observed in the electron flux, a centered dipole model for the magnetic field of Uranus with a tilt of 60.1 degrees has been derived, and a rotation period of the planet of 17.4 hours has also been calculated. This model provides independent confirmation of more precise determinations made by other Voyager experiments.
Regular Intervals Between Hawaiian Earthquakes: Implications for Predicting the Next Event
Authors: Wyss Max
Published: October 2006

During the years 1941 through 1983 five earthquake mainshocks of moderate magnitude occurred at regular intervals of 10.5 ± 1.5 years within a 6-kilometer radius in Hawaii. It is proposed that these Kaoiki earthquakes will continue to occur at regular intervals because the strain accumulation rate and the strained volume remain constant. With appropriate instrumentation, it may be possible to refine predictions of subsequent Kaoiki earthquakes.
New Directions in the Relation Between Public and Private Debt
Authors: Friedman Benjamin M.
Published: October 2006

Until the 1980s the outstanding indebtedness of government and private-sector borrowers in the United States exhibited sufficient negative covariation that total outstanding debt remained steady relative to nonfinancial economic activity. Three hypotheses—one based on lenders' behavior, one on borrowers' behavior, and one on credit market institutional arrangements—provide potential explanations for this phenomenon. Since 1980 the U.S. debt markets have departed from these previously prevailing patterns, however, as both government and private borrowing have risen sharply.