bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Domains of Yeast U6 Small Nuclear RNA Required for Both Steps of Nuclear Precursor Messenger RNA Splicing
Authors: Fabrizio Patrizia , Abelson John
Published: October 2006

U6 is one of the five small nuclear RNA's (snRNA's) that are required for splicing of nuclear precursor messenger RNA (pre-mRNA). The size and sequence of U6 RNA are conserved among organisms as diverse as yeast and man, and so it has been proposed that U6 RNA functions as a catalytic element in splicing. A procedure for in vitro reconstitution of functional yeast U6 small nuclear ribonucleoproteins (snRNP's) with synthetic U6 RNA was applied in an attempt to elucidate the function of yeast U6 RNA. Two domains in U6 RNA were identified, each of which is required for in vitro splicing. Single nucleotide substitutions in these two domains block splicing either at the first or the second step. Invariably, U6 RNA mutants that block the first step of splicing do not enter the spliceosome. On the other hand, those that block the second step of splicing form a spliceosome but block cleavage at the 3′ splice site of the intron. In both domains, the positions of base changes that block the second step of splicing correspond exactly to the site of insertion of pre-mRNA-type introns into the U6 gene of two yeast species, providing a possible explanation for the mechanism of how these introns originated and adding further evidence for the proposed catalytic role of U6 RNA.
Database Systems
Authors: Blasgen Michael W.
Published: October 2006

Database systems, computer systems that are principally devoted to the management of large amounts of data, are becoming more and more important to the operation of many enterprises. This article surveys the technology of database software and hardware, describing some of the principal issues related to the user's view of data, sharing, concurrent access, security, and integrity.
Stages of Neurotransmitter Development in Autonomic Neurons
Authors: Black Ira B.
Published: October 2006

The ontogeny of neurotransmitters in autonomic neurons proceeds through the successive stages of early expression, definitive expression, modulation, and regulation, extending from embryonic life to maturity. Although different extracellular signals influence development at different stages, a number of signals that influence development continue to govern transmitter function during maturity. The sequential ontogenetic stages parallel the progressive restriction of mutability of phenotypic expression; however, some degree of neuronal mutability appears to persist through maturity.
Coral Gas: Oxygen Production in
Millepora
on the Great Barrier Reef
Authors: Bellamy Nigel , Risk Michael J.
Published: October 2006

Large volumes of a gas consisting of 69 percent molecular oxygen and 31 percent molecular nitrogen with trace amounts of carbon monoxide, carbon dioxide, and methane have been found trapped inside skeletons of the common hydrozoan
Millepora
. Volumes were low in the morning and reached a maximum by late afternoon. The oxygen was probably produced by the endolithic (boring) algae, with which the
Millepora
skeletons are very heavily infested. Oxygen production by endolithic algae in
Millepora
and in other substrates could influence estimates of reef productivity based on measurements of dissolved gases.
Batan Grande: A Prehistoric Metallurgical Center in Peru
Authors: Shimada Izumi , Epstein Stephen , Craig Alan K.
Published: October 2006

Recent archeological fieldwork on the north coast of Peru permits a preliminary reconstruction of a prill-extraction copper and copper alloy smelting process heretofore undocumented in the New World. The process was applied on a large scale during the late pre-Hispanic period. This study provides strong support for the claim that central Andean metallurgy constituted one of the major independent metallurgical traditions of the world.
Homology of Cytokine Synthesis Inhibitory Factor (IL-10) to the Epstein-Barr Virus Gene BCRFI
Authors: Moore Kevin W. , Vieira Paulo , Fiorentino David F. , Trounstine Mary L. , Khan Tariq A. , Mosmann Timothy R.
Published: October 2006

Complementary DNA clones encoding mouse cytokine synthesis inhibitory factor (CSIF; interleukin-10), which inhibits cytokine synthesis by T
H
1 helper T cells, were isolated and expressed. The predicted protein sequence shows extensive homology with an uncharacterized open reading frame, BCRFI, in the Epstein-Barr virus genome, suggesting the possibility that this herpes virus exploits the biological activity of a captured cytokine gene to enhance its survival in the host.
Molecular Localization of the Transforming and Secretory Properties of PDGF A and PDGF B
Authors: LaRochelle William J. , Giese Neill , May-Siroff Mary , Robbins Keith C. , Aaronson Stuart A.
Published: October 2006

Human platelet-derived growth factor (PDGF) is a connective tissue cell mitogen comprised of two related chains encoded by distinct genes. The B chain is the homolog of the v-
sis
oncogene product. Properties that distinguish these ligands include greater transforming potency of the B chain and more efficient secretion of the A chain. By a strategy involving the generation of PDGF A and B chimeras, these properties were mapped to distinct domains of the respective molecules. Increased transforming efficiency segregated with the ability to activate both α and β PDGF receptors. These findings genetically map PDGF B residues 105 to 144 as responsible for conformational alterations critical to β PDGF receptor interaction and provide a mechanistic basis for the greater transforming potency of the PDGF B chain.
Changes in Sodium Channel Gating Produced by Point Mutations in a Cytoplasmic Linker
Authors: Moorman J. Randall , Kirsch Glenn E. , Brown Arthur M. , Joho Rolf H.
Published: October 2006

Voltage-gated sodium channels are transmembrane proteins of approximately 2000 amino acids and consist of four homologous domains (I through IV). In current topographical models, domains III and IV are linked by a highly conserved cytoplasmic sequence of amino acids. Disruptions of the III-IV linker by cleavage or antibody binding slow inactivation, the depolarization-induced closed state characteristic of sodium channels. This linker might be the positively charged "ball" that is thought to cause inactivation by occluding the open channel. Therefore, groups of two or three contiguous lysines were neutralized or a glutamate was substituted for an arginine in the III-IV linker of type III rat brain sodium channels. In all cases, inactivation occurred more rapidly rather than more slowly, contrary to predictions. Furthermore, activation was delayed in the arginine to glutamate mutation. Hence, the III-IV linker does not simply act as a charged blocker of the channel but instead influences all aspects of sodium channel gating.
Observations of Strain Accumulation Across the San Andreas Fault Near Palmdale, California, with a Two-Color Geodimeter
Authors: Langbein J. O. , Linker M. F. , McGarr A. , Slater L. E.
Published: October 2006

Two-color laser ranging measurements during a 15-month period over a geodetic network spanning the San Andreas fault near Palmdale, California, indicate that the crust expands and contracts aseismically in episodes as short as 2 weeks. Shear strain parallel to the fault has accumulated monotonically since November 1980, but at a variable rate. Improvements in measurement precision and temporal resolution over those of previous geodetic studies near Palmdale have resulted in the definition of a time history of crustal deformation that is much more complex than formerly realized.
Lizard Tail Autotomy: Function and Energetics of Postautotomy Tail Movement in
Scincella lateralis
Authors: Dial Benjamin E. , Fitzpatrick Lloyd C.
Published: October 2006

Handling of autotomized, thrashing and autotomized, exhausted tails of the lizard
Scincella lateralis
by mammals and snakes was tested to examine the function of postautotomy tail movement. Tail movement attracted a mammal's attack to the tail, permitting the lizard to escape and increased the time required for a snake to subdue a tail before swallowing it, increasing the lizard's escape time by 40 percent. Lactate concentrations of autotomized tails after movement were compared to those of intact tails after rest in
S. lateralis
, a species with a high rate of autotomized tail thrashing, and
Anolis carolinensis
, a species with a low rate of thrashing. Postautotomy movement increased tail lactate concentration in both species, but mean tail lactate concentration in
S. lateralis
was 60 percent higher than that in
A. carolinensis
, and a third higher than that reported for whole-body lactate content of the very mobile lizard
Dipsosaurus dorsalis
.
Localization of the Neurally Mediated Arrhythmogenic Properties of Digitalis
Authors: Somberg John C. , Smith Thomas W.
Published: October 2006

Available evidence suggests that the propensity of digitalis glycosides to produce cardiac arrhythmias is due in part to their neuroexcitatory effects. We have performed experiments in cats which support the existence of a neurogenic component in the etiology of digitalis-induced ventricular arrhythmias. Our data further indicate that the locus of this neural effect lies within an area of the medulla 2 millimeters above to 2 millimeters below the obex. These findings, when considered with the effects of polar cardiac glycosides that do not cross the blood-brain barrier, suggest that the area postrema may be the site of neural activation.
Winteraceous Pollen in the Lower Cretaceous of Israel: Early Evidence of a Magnolialean Angiosperm Family
Authors: Walker James W. , Brenner Gilbert J. , Walker Audrey G.
Published: October 2006

Pollen of the primitive angiosperm family Winteraceae has been discovered in the Aptian-Albian of Israel, extending the fossil record of this phylogenetically important family of flowering plants from the uppermost Upper Cretaceous back some 40 million years to the upper Lower Cretaceous. This appears to represent the earliest known record of a magnolialean angiosperm family and is convincing evidence for the existence in the Early Cretaceous of an extant family of angiosperms.
Regulation of an Enzyme by Phosphorylation at the Active Site
Authors: Hurley James H. , Dean Antony M. , Sohl Julie L. , Koshland Daniel E , Stroud Robert M.
Published: October 2006

The isocitrate dehydrogenase of
Escherichia coli
is an example of a ubiquitous class of enzymes that are regulated by covalent modification. In the three-dimensional structure of the enzyme-substrate complex, isocitrate forms a hydrogen bond with Ser
113
, the site of regulatory phosphorylation. The structures of Asp
113
and Glu
113
mutants, which mimic the inactivation of the enzyme by phosphorylation, show minimal conformational changes from wild type, as in the phosphorylated enzyme. Calculations based on observed structures suggest that the change in electrostatic potential when a negative charge is introduced either by phosphorylation or site-directed mutagenesis is sufficient to inactivate the enzyme. Thus, direct interaction at a ligand binding site is an alternative mechanism to induced conformational changes from an allosteric site in the regulation of protein activity by phosphorylation.
Replicative Senescence: the Human Fibroblast Comes of Age
Authors: Goldstein Samuel
Published: October 2006

Human diploid fibroblasts undergo replicative senescence predominantly because of arrest at the G
1
/S boundary of the cell cycle. Senescent arrest resembles a process of terminal differentiation that appears to involve repression of proliferation-promoting genes with reciprocal new expression of antiproliferative genes, although post-transcriptional factors may also be involved. Identification of participating genes and clarification of their mechanisms of action will help to elucidate the universal cellular decline of biological aging and an important obverse manifestation, the rare escape of cells from senescence leading to immortalization and oncogenesis.
The Fate of
Amoco Cadiz
Oil
Authors: Gundlach Erich R. , Boehm Paul D. , Marchand Michel , Atlas Ronald M. , Ward David M. , Wolfe Douglas A.
Published: October 2006

The
Amoco Cadiz
oil spill (223,000 metric tons) of March 1978 is the largest and best studied tanker spill in history. Of the total oil lost, 30,000 tons (13.5 percent) rapidly became incorporated into the water column, 18,000 tons (8 percent) were deposited in subtidal sediments, 62,000 tons (28 percent) washed into the intertidal zone, and 67,000 tons (30 percent) evaporated. While still at sea, approximately 10,000 tons of oil were degraded microbiologically. After 3 years, the most obvious effects of the spill have passed, although hydrocarbon concentrations remain elevated in those estuaries and marshes that were initially most heavily oiled.
Lessons from the Silica "Decline" in Lake Michigan
Authors: Shapiro Joseph , Swain Edward B.
Published: October 2006

A new analysis of data obtained from water treatment plants on Lake Michigan fails to support published contentions, based on such data, that the silica content of the lake has declined during the last five decades. The purported silica decline appears to have been due to changes in analytical methods and laboratories. Had such changes been avoided, an invaluable record of the silica content of the lake could have been obtained.
Eruption Prediction Aided by Electronic Tiltmeter Data at Mount St. Helens
Authors: Dzurisin Daniel , Westphal James A. , Johnson Daniel J.
Published: October 2006

Telemetry from electronic tiltmeters in the crater at Mount St. Helens contributed to accurate predictions of all six effusive eruptions from June 1981 to August 1982. Tilting of the crater floor began several weeks before each eruption, accelerated sharply for several days, and then abruptly changed direction a few minutes to days before extrusion began. Each episode of uplift was caused by the intrusion of magma into the lava dome from a shallow source, causing the dome to inflate and eventually rupture. Release of magma pressure and increased surface loading by magma added to the dome combined to cause subsidence just prior to extrusion.
A Cellulolytic Nitrogen-Fixing Bacterium Cultured from the Gland of Deshayes in Shipworms (Bivalvia: Teredinidae)
Authors: Waterbury John B. , Calloway C. Bradford , Turner Ruth D.
Published: October 2006

A novel bacterium has been isolated in pure culture from the gland of Deshayes in six species of teredinid bivalves. It is the first bacterium known to both digest cellulose and fix nitrogen, and it is a participant in a unique symbiotic relation with shipworms that may explain how teredinids are able to use wood as their principal food source.
Pinosylvin Methyl Ether Deters Snowshoe Hare Feeding on Green Alder
Authors: Bryant John P. , Wieland Gregory D. , Reichardt Paul B. , Lewis Vince E. , McCarthy Michael C.
Published: October 2006

Pinosylvin methyl ether (PME), a toxic phenol, is a potent deterrent to showshoe hare feeding on green alder. Concentrations of PME found in green alder parts can account for the low palatability of winter-dormant foliar buds and staminate catkins but cannot affect internode palatability. The lack of a PME-related defense system in internodes suggests that green alder has at least a two-level defense system: defense of growth stages and defense of parts within growth stages.
Microwave Measurements of Carbon Monoxide on Titan
Authors: Muhleman D. O. , Berge G. L. , Clancy R. T.
Published: October 2006

The ratio of the flux density of Titan was measured in two 200-megahertz bands, one centered on the (1-0) rotation line of carbon monoxide at 115.3 gigahertz and the other 2600 megahertz lower. The measurements were made with a complex-correlation technique on the new millimeter-wavelength interferometer at the Owens Valley Radio Observatory, Big Pine, California. The excess flux in the carbon monoxide band is interpreted as a strong detection of carbon monoxide and a mixing ratio, assumed constant, of 6 × 10
-5
. The brightness temperature of Titan at 112.6 gigahertz is 69 ± 10 kelvins, consistent with atmospheric emission from just below the tropopause.
Water Uptake by Roots Controls Water Table Movement and Sediment Oxidation in Short
Spartina
Marsh
Authors: Dacey John W. H. , Howes Brian L.
Published: October 2006

Downward movement of the water table during both day and night in the short grass zone of intertidal salt marshes is due not to drainage but to water uptake by roots. Removal of water from the sediment results in the entry of air into the sediment, suggesting a feedback between plant growth, water uptake, and sediment oxidation. The water balance of
Spartina alterniflora
appears to influence the internal morphology of its roots, potentially giving rise to a new mechanism for the mass flow of gas in plants.
An Equatorial Pacific Ocean Source of Atmospheric Mercury
Authors: Fitzgerald W. F. , Gill G. A. , Kim J. P.
Published: October 2006

Pronounced increases in total gaseous mercury (TGM) in the near surface marine atmosphere were found in the equatorial region (4°N to 10°S) of the Pacific Ocean at 160° W. The atmospheric enhancement of TGM corresponded closely to sea-surface manifestations of equatorial upwelling as reflected in measured changes of temperature and nutrient concentrations as well as to variations of reactive mercury in surface seawater. The elevated atmospheric TGM levels most probably result from oceanic mercury evasion associated with upwelling and increased biological production that occurs in the equatorial Pacific Ocean. This evidence of sea-to-air mercury transfer supports model predictions of an oceanic source of atmospheric mercury and suggests that marine-derived mercury emissions should occur in other biologically productive regimes.
The Vega Particulate Shell: Comets or Asteroids?
Authors: Weissman Paul R.
Published: October 2006

The Infrared Astronomical Satellite (IRAS) science team has discovered a shell of particulate material around the star Vega. At the mean distance and temperature of the shell, the expected condensation products from a protostellar nebula would be dominated by frozen volatiles, in particular water ice. It is not possible to discriminate between dirty ice and silicate materials in the Vega shell on the basis of the IRAS data. The Vega shell is probably a ring of cometary bodies with an estimated minimum mass of 15 earth masses, analogous to one that has been hypothesized for the solar system. A possible hot inner shell around Vega may be an asteroid-like belt of material a few astronomical units from the star.
A Dynamical Instability of Spark-Ignited Engines
Authors: Kantor Jeffrey C.
Published: October 2006

A simple model for spark-ignited engines is proposed in which the residual exhaust gases of a combustion event affect ignition of the subsequent charge. The model is an example of a one-dimensional, discrete, nonlinear mapping of an interval. Laminar flame correlations incorporated within models for ignition exhibit Arrhenius kinetics. Small variations of the ignition time with respect to the expansion cycle alter the work produced by each cycle, thereby altering the exhaust-gas temperature. It is shown that the mixing of hot residual gases with a fresh charge is a sufficient mechanism to produce an instability of the ignition process, resulting in oscillatory behavior. When this instability is compounded with the effects of mixture turbulence, one obtains a novel picture of the well-known phenomenon of "cyclic dispersion" exhibited by such engines.
Morphine-Naloxone Interactions: A Role for Nonspecific Morphine Excitatory Effects in Withdrawal
Authors: Stevens David R. , Klemm W. R.
Published: October 2006

The opiate antagonist naloxone precipitates withdrawal when given either 15 minutes after or 1 minute before a single injection of morphine in drug-naive mice. We propose that withdrawal signs arise from a synergistic mixture of excitatory influences that are direct (agonistic action on nonspecific opiate receptors) and indirect (sensory and affective disorders, stress, hormonal and neurotransmitter dysfunction, and so forth). The predominant effects during precipitated withdrawal are assumed to be direct, whereas during abstinence in tolerant animals they are indirect.
A Deep 6-Centimeter Radio Source Survey
Authors: Fomalont E. B. , Kellermann K. I. , Wall J. V. , Weistrop D.
Published: October 2006

The Very Large Array has been used to survey a small region of sky at a wavelength of 6 centimeters down to a completeness level of 60 microjanskys—about 100 times weaker than the faintest radio sources that have been detected with other instruments. The observed source count at flux densities below 100 millijanskys converges in a manner similar to the lower frequency counts, although there is some evidence for an excess of sources weaker than 100 microjanskys. The sources in the survey are preferentially identified with faint galaxies.
Volcanic Hotspots on Io: Stability and Longitudinal Distribution
Authors: Johnson T. V. , Morrison D. , Matson D. L. , Veeder G. J. , Brown R. H. , Nelson R. M.
Published: October 2006

We report the first results of a program to determine the longitudinal distribution of volcanic activity on Jupiter's satellite Io. Infrared measurements at 8.7, 10, and 20 micrometers have been taken at a variety of orbital longitudes: strong variation in the 8.7- and 10-micrometer flux with longitude demonstrates that infrared emission arising from volcanic hotspots on Io is strongly concentrated in a few locations. Analysis of these data suggests that the active volcanic regions observed by the Voyager experimenters are still active, particularly the region around the feature known as Loki. Another source of flux, although of somewhat smaller magnitude, is indicated on the opposite hemisphere. If these sources are the only major volcanic centers on Io, then current global heat flow estimates must be revised downward. However, heat flow from as yet unobserved longitudes, hotspots at high latitudes, and conducted heat flow must still be measured.
Extensive Volcanism Associated with the Separation of Australia and Antarctica
Authors: Jones J. B. , Fitzgerald M. J.
Published: October 2006

Alternating hard and soft layers characterize the Gull Rock and Tuit Members of the late Eocene Blanche Point Formation, South Australia. Originally the formation was mainly a mixture of volcanic ash, sponge spicules, and calcareous fossil remains, with hard layers produced later by selective silicification. It resembles Cretaceous sediments from western Europe and the eastern coast of the United States, and in each case it appears that alteration of volcanic ash produced smectite and clinoptilolite with release of silica that subsequently crystallized as opal-CT. The occurrence of similar deposits from New Zealand to as far west as Albany, Western Australia, indicates extensive volcanic activity south of Australia in the late Eocene resulting from rifting and separation from Antarctica.
Discovery of New Variable Radio Sources in the Nucleus of the Nearby Galaxy Messier 82
Authors: Kronberg Philipp P. , Sramek Richard A.
Published: October 2006

Widespread variability has been discovered in a large population of radio sources close to the nucleus of an active galaxy. The galaxy, Messier 82 (M82), and others similar to it show evidence for enhanced nuclear activity and unusually strong far-infrared emission. The observational data, obtained with the National Radio Astronomy Observatory's Very Large Array in New Mexico over the past 3 years, provide the first direct "look" at a starburst—the phenomenon of sudden, rapid star formation which occurs near the nucleus of a small fraction of galaxies. Nearly all the brightest of about 40 radio sources in M82's nucleus decreased in intensity over 2.7 years up to October 1983. One source, which in February 1981 was ten times as bright as our Galaxy's most luminous supernova remnant, turned off within only a few months. Most of the other ten strongest sources are declining so rapidly that they will fade into the background within 30 years. Thus, new supernovae are expected to appear in M82's nucleus every few years. The discovery has revealed the "engine room" of the mysterious activity in M82 and, by implication, similar active galaxies which have disturbed nuclei and which are unusually luminous in the far infrared. An estimate of the rate of energy input by the radio-visible supernovae closely matches the far-infrared luminosities which were recently measured for M82 and other similar galaxies.
Transformation of Amorphous Calcium Phosphate to Crystalline Dahllite in the Radular Teeth of Chitons
Authors: Lowenstam H. A. , Weiner S.
Published: October 2006

A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The
c
axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.
Highly Supercooled Cirrus Cloud Water: Confirmation and Climatic Implications
Authors: Sassen Kenneth , Liou Kuo Nan , Kinne Stefan , Griffin Michael
Published: October 2006

Liquid cloud droplets supercooled to temperatures approaching -40°C have been detected at the base of a cirrostratus cloud through a combination of ground-based, polarization laser radar (lidar) and in situ aircraft measurements, Solar and thermal infrared radiative budget calculations based on these observations indicate that significant changes in the atmospheric heating distribution and the surface radiative budget may be attributed to liquid layers in cirrus clouds.
Surface Science and Catalysis
Authors: Somorjai Gabor A.
Published: October 2006

During the last 20 years, surface scientists have developed a variety of techniques that make it possible to study, on the molecular level, the structure, composition, and chemical bonding in the surface monolayer. Both single-crystal model catalysts and real catalyst systems that are active in important chemical processes have been investigated by a combination of ultrahigh-vacuum surface science techniques and high-pressure kinetic techniques in an effort to determine the relation between the structure and composition of the surface and the rates of reaction and selectivities. The structure of the atomic surface, a strongly adsorbed overlayer, and the oxidation states of surface atoms are the important molecular features of an active catalyst. As a consequence of modern surface science, the design and preparation of catalysts has developed from an art into a high technology.
Mutual Restraint in Tree Swallows: A Test of the TIT FOR TAT Model of Reciprocity
Authors: Lombardo Michael P.
Published: October 2006

The TIT FOR TAT model of reciprocity, which is based on a successful program for the game known as the Prisoner's Dilemma, was experimentally tested on a population of tree swallows (
Tachycineta bicolor
). Parent and nonbreeding tree swallows have conflicts of interests that resemble those in the Prisoner's Dilemma. TIT FOR TAT predicts restraint of conflict before a competitor's act of defection, retaliation after defection, and a resumption of restraint following retaliation. After a simulated act of defection by nonbreeders, parents behaved as predicted by the model.
Cerebral Vessels Have the Capacity to Transport Sodium and Potassium
Authors: Eisenberg Howard M. , Suddith Robert L.
Published: October 2006

The activity of Na
+
, K
+
-activated adenosinetriphosphatase and the uptake of a potassium analog, rubidium, were found to be similar in cerebral microvessels and choroid plexus when measured in vitro. This similarity suggests that sodium and potassium concentrations in the nascent brain extracellular fluid are determined by the same active process that regulates their concentration in nascent cerebrospinal fluid. The brain microvessels may thereby play an active role in brain potassium homeostasis and brain extracellular fluid formation.
Pollution Aerosol in the Northeast: Northeastern-Midwestern Contributions
Authors: Rahn Kenneth A. , Lowenthal Douglas H.
Published: October 2006

In recent years, atmospheric scientists have been endeavoring to determine the relative contributions of local and distant sources to pollution aerosol in eastern North America. Elemental analysis of aerosol from various sites in the northeastern United States has revealed a persistent northeastern "foreground" upon which pulses of midwestern aerosol are superimposed every few days, in response to large-scale meteorological features. Regional apportionment of tracer elements and sulfate in summer and winter samples from Narragansett, Rhode Island, and Underhill, Vermont, shows that most of the elements come predominantly from northeastern sources. Notable exceptions include arsenic and indium, for which Canadian nonferrous smelters are important sources, and sulfur and selenium, for which the Midwest is an important source. During 1982 and 1983, the Northeast and the Midwest contributed comparably to aerosol sulfate at Narragansett and Underhill, in spite of the fact that the emissions of sulfur dioxide in the Midwest were ten times those in the Northeast; Canadian smelters accounted for less than 10 percent of the total sulfate. During a major pollution episode in July 1982, northeastern and midwestern sources produced comparable sulfate concentrations in Rhode Island, whereas midwestern sources dominated northeastern sources in Vermont. Thus, although distant midwestern sources affect the quantity of pollution aerosol in the Northeast and may dominate episodically, nearer northeastern sources are comparably important on the long term.
Epizootic Carcinoma in the Winter Flounder,
Pseudopleuronectes americanus
Authors: Murchelano R. A. , Wolke R. E.
Published: October 2006

The winter flounder,
Pseudopleuronectes americanus
, is an esteemed food fish and has sustained an important commercial and recreational fishery for many years in the northeastern United States. Histopathologic examinations of hepatic tissues of winter flounder from Boston Harbor revealed a high prevalence of neoplasms. The lesions, designated as cholangiocarcinomas and hepatocarcinomas, were found in 16 of 200 fish examined and resembled those experimentally induced in rodents by exposure to carcinogens.
Floral Mimicry Induced by Mummy-Berry Fungus Exploits Host's Pollinators as Vectors
Authors: Batra Lekh R. , Batra Suzanne W. T.
Published: October 2006

Leaves and shoots of blueberries (
Vaccinium
spp.) and huckleberries (
Gaylussacia
sp.) when infected by ascospores of
Monilinia
spp. become ultraviolet-reflective and fragrant and secrete sugars at their lesions. Insects that normally pollinate these hosts are attracted to the discolored leaves, ingest the sugars, and transmit conidia to their flowers, resulting in sclerotia (mummy-berry) formation.
Gas Jets Associated with Star Formation
Authors: Welch W. J. , Vogel S. N. , Plambeck R. L. , Wright M. C.H. , Bieging J. H.
Published: October 2006

Young stellar objects of both high and low luminosity emit energetic jets or winds of material that are often highly collimated and often bipolar. Near the stars, turbulent swept-up gas is observed in the emission of interstellar molecules such as carbon monoxide, and small, bright regions of water maser emission and the nebulous bright patches known as Herbig-Haro objects appear to be participating in the outflows. There are striking changes in chemical abundances associated with the attendant shocks. Probably every star goes through this phase, which may mark the end of its period of accretion.
Dispersal Pathways for Particle-Associated Pollutants
Authors: Young Robert A. , Swift Donald J. P. , Clarke Thomas L. , Harvey George R. , Betzer Peter R.
Published: October 2006

Particle-associated pollutants (totaling 10
7
metric tons per year) are introduced into the New York Bight by ocean dumping, estuarine discharge, sewage outfalls, eolian transport, and shipping waste and spillage. Oceanic and estuarine circulation processes dilute and transport the particles by a natural dispersal system that also tends to be highly distributive; particle-associated pollutants apparently seek the same sinks in the Hudson River shelf valley and intracoastal wetlands, regardless of their point of introduction.
Dopaminergic Inhibition of Adrenergic Neurotransmission as a Model for Studies on Dopamine Receptor Mechanisms
Authors: Steinsland Odd S. , Hieble J. Paul
Published: October 2006

Dopamine and apomorphine produced concentration-dependent inhibition of adrenergic neurotransmission in the isolated, perfused, rabbit ear artery. The inhibitory action of both dopamine and apomorphine was competitively antagonized by haloperidol and several other antipsychotic drugs. The calculated affinities of these drugs for the dopaminergic receptor correlate closely with both the pharmacological potencies of these drugs in vivo and their reported potencies as inhibitors of [
3
H]haloperidol binding to "dopamine receptors" in brain homogenates.
Role of Seasonality in the Evolution of Climate During the Last 100 Million Years
Authors: Crowley Thomas J. , Short David A. , Mengel John G. , North Gerald R.
Published: October 2006

A simple climate model has been used to calculate the effect of past changes in the land-sea distribution on the seasonal cycle of temperatures during the last 100 million years. Modeled summer temperatures decreased over Greenland by more than 10°C and over Antarctica by 5° to 8°C. For the last 80 million years, this thermal response is comparable in magnitude to estimated atmospheric carbon dioxide effects. Analysis of paleontological data provides some support for the proposed hypothesis that large changes due to seasonality may have sometimes resulted in an ice-free state due to high summer temperatures rather than year-round warmth. Such "cool" non-glacials may have prevailed for as much as one-third of the last 100 million years.
The Zeolite Cage Structure
Authors: Newsam J. M.
Published: October 2006

Zeolites are typically aluminosilicates whose framework structures have pores of molecular dimensions. They are widely used as ion exchangers and sorbents and in hydrocarbon conversion catalysis and separations. Recent zeolite research has focused on widening the scope of synthetic procedures, on further exploiting zeolites in commercial processes, and on applying modern characterization techniques to unraveling the complexities of zeolite structural properties.
Monooxygenase Induction and Chlorobiphenyls in the Deep-Sea Fish
Coryphaenoides armatus
Authors: Stegeman John J. , Kloepper-Sams Pamela J. , Farrington John W.
Published: October 2006

Inhibition of liver microsomal ethoxyresorufin
O
-deethylase and aryl hydrocarbon hydroxylase activities by α-naphthoflavone and by polyclonal antibodies to hydrocarbon-inducible cytochrome P-450E from teleost liver indicated a xenobiotic-induced origin of these activities in the deep-sea fish
Coryphaenoides armatus
. Specific recognition of a protein by antibodies to P-450E in an immunoblot assay further indicated xenobiotic-induced cytochrome P-450 in these animals. Levels of apparently induced cytochrome P-450 and monooxygenase activity correlated positively with the tissue content of chlorobiphenyls of known inducing activity, implicating such compounds in biochemical effects occurring in the deep ocean.
Extended Oxygen Delivery from the Nerve Hemoglobin of
Tellina alternata
(Bivalvia)
Authors: Kraus David W. , Colacino James M.
Published: October 2006

An oxygen-binding hemoglobin localized in the nerves of
Tellina alternata
(Bivalvia) required 30 minutes to unload oxygen when excised nerves were exposed to pure nitrogen. Neural excitability under these conditions could be sustained only until deoxygenation of the hemoglobin was complete. When the oxygen-combining function of the hemoglobin was abolished with carbon monoxide, the neural excitability ceased within a few minutes of oxygen removal, a response identical to that of hemoglobinless homologous nerves of other bivalves. These results demonstrate that aerobic activity can be supported by the oxygen stored on hemoglobin in microscopic tissues for a considerable time under anoxic conditions.
Scaling Up an Immobilized Enzyme System
Authors: Weetall Howard H. , Pitcher Wayne H.
Published: October 2006

The development of an immobilized enzyme system for commercial application involves a series of decisions and compromises beginning with the choice of enzyme support and ending with the decision on operational mode. Each step is dependent on the other steps, and all the steps influence the overall economics of the final process. Compromises need to be made about the support, method of enzyme attachment, reactor type, kinetic behavior, and operating strategy. Selection of the enzyme carrier and its composition will have a major effect on the
p
H optimum, metal requirements, and overall performance of the immobilized enzyme system. The reactor type and its behavior will also affect performance. For commercial applications the fixed-bed reactor is generally the reactor type of choice. Knowledge of the appropriate kinetics is necessary to achieve the desired product quality and to reduce cost. One important kinetic parameter is reaction velocity under real world conditions. Rate expressions must take into consideration back-mixing and mass transfer limitations, both internal and external to the immobilized enzyme particles. In addition to understanding kinetic behavior, one must devise a proper operating strategy for producing the greatest amount of product at the least cost, while maintaining constant productivity over time. The success of any scale-up will be determined by the final processing cost as compared to that of the alternatives.
Primary Sequence Information from Intact Proteins by Electrospray Ionization Tandem Mass Spectrometry
Authors: Loo Joseph A. , Edmonds Charles G. , Smith Richard D.
Published: October 2006

Tandem mass spectrometry has been used to obtain information related to portions of the primary sequence for an intact protein, bovine ribonuclease A. Multiply charged molecular ions, generated by electrospray ionization, were collisionally dissociated at low energies in a triple quadrupole mass spectrometer to yield singly and multiply charged fragment ions that can be assigned to the known sequence of the protein. Dissociation of the highly charged molecular ions resulted in pairs of complementary product ions. The higher order (gas-phase) protein structure affects the dissociation processes, as observed in comparisons of tandem mass spectra of the native and disulfide-reduced forms of ribonuclease A.
Photometry from Voyager 2: Initial Results from the Uranian Atmosphere, Satellites, and Rings
Authors: Lane Arthur L. , Hord Charles W. , West Robert A. , Esposito Larry W. , Simmons Karen E. , Nelson Robert M. , Wallis Brad D. , Buratti Bonnie J. , Horn Linda J. , Graps Amara L. , Pryor Wayne R.
Published: October 2006

The Voyager 2 photopolarimeter successfully completed the Uranus encounter, acquiring new data on the planet's atmosphere, its principal satellites, and its ring system. Spatially resolved photometry of the atmosphere at 0.27 micrometer shows no enhancement in absorption toward the pole, unlike the case for Jupiter and Saturn. Stellar occultation measurements indicate the temperature at the 1-millibar level over the north pole is near 90 kelvins. The geometric albedos of the five large satellites of Uranus were measured at 0.27 and 0.75 micrometer and indicate the presence of low albedo, spectrally flat absorbing material. Titania seems to have a fluffy surface, as indicated by its phase curve. The nine ground-based rings were detected, and their internal structure, optical depths, and positions were determined. The sharp edges of the ε ring made it possible to measure its edge thickness (less than 150 meters) and particle sizes (less than 30 meters); little or no dust was detected. New narrow rings and partial rings (arcs) were measured, and the narrow component of the η ring was found to be discontinuous.
The Volatility of Stock Market Prices
Authors: Shiller Robert J.
Published: October 2006

If the volatility of stock market prices is to be understood in terms of the efficient markets hypothesis, then there should be evidence that true investment value changes through time sufficiently to justify the price changes. Three indicators of change in true investment value of the aggregate stock market in the United States from 1871 to 1986 are considered: changes in dividends, in real interest rates, and in a direct measure of intertemporal marginal rates of substitution. Although there are some ambiguities in interpreting the evidence, dividend changes appear to contribute very little toward justifying the observed historical volatility of stock prices. The other indicators contribute some, but still most of the volatility of stock market prices appears unexplained.
Apogeotropic Roots in an Amazon Rain Forest
Authors: Sanford Robert L.
Published: October 2006

Roots of some tropical trees grow vertically upward on the stems of neighboring trees. Apogeotropic roots occur in 12 species across five families. These roots, originating as fine roots in the mineral soil, grow upward as fast as 5.6 centimeters in 72 hours. Apogeotropic root growth may be an adaptation to extremely low soil nutrient availability in Amazon forests. In these forests upward-growing roots obtain nutrients via the predictable pathway of precipitation that flows down along the stem. Apogeotropic roots form a nutrient cycling pathway in which nutrients are absorbed and transported directly from plant to plant, without entering the soil solution.
The Onshore Transport of an Oil Spill by Internal Waves
Authors: Shanks Alan L.
Published: October 2006

Internal waves generated by tidal currents concentrated and transported an oil spill (liquid asphalt) onshore. Plankton net samples were collected in front of and behind a set of internal waves as well as in the convergence and divergence zones over the waves. Tar "balls" were most abundant (greater than 30-fold) in the samples from the convergence zone. Comparison of the abundance of tar balls in front of and behind the set of waves suggests that the internal waves "caught" about 68% of the asphalt encountered and concentrated and swept shoreward tar balls from almost 8 kilometers of ocean.
Markarian 348: A Tidally Disturbed Seyfert Galaxy
Authors: Simkin Susan M. , Su Hong-Jun , van Gorkom Jacqueline , Hibbard, John
Published: October 2006

Combined optical and radio images of galaxies can provide new insights into the sizes, masses, and possible evolution of these objects. Deep optical and neutral hydrogen images of Markarian 348, a type 2 Seyfert galaxy, show that it is a gigantic spiral (perhaps the largest known non-cluster galaxy). Measurements of the neutral hydrogen velocity field and spiral structure, and detection of an optical "tidal plume," all provide evidence that it has been subject to tidal disruption. The measured velocities yield a mass-to-light ratio for this object (within a radius of 130 kiloparsecs from its nucleus) that is similar to the ratio found for the inner regions of most galaxies of similar type. This is one of the few cases where detailed velocity measurements have demonstrated that a galaxy with an active nucleus has been subject to extensive tidal perturbation.
Intercalation Complex of Proflavine with DNA: Structure and Dynamics by Solid-State NMR
Authors: Tang Pei , Juang Chi-Long , Harbison Gerard S.
Published: October 2006

The structure of the complex formed between the intercalating agent proflavine and fibrous native DNA was studied by one- and two-dimensional high-resolution solid-state nuclear magnetic resonance (NMR). Carbon-13-labeled proflavine was used to show that the drug is stacked with the aromatic ring plane perpendicular to the fiber axis and that it is essentially immobile. Natural abundance carbon-13 NMR of the DNA itself shows that proflavine binding does not change the puckering of the deoxyribose ring. However, phosphorus-31 NMR spectra show profound changes in the orientation of the phosphodiester grouping on proflavine binding, with some of the phosphodiesters tilting almost parallel to the helix axis, and a second set almost perpendicular. The first group to the phosphodiesters probably spans the intercalation sites, whereas the tilting of the second set likely compensates for the unwinding of the DNA by the intercalator.
Amino Acid Composition of Proteins: Selection Against the Genetic Code
Authors: Jukes Thomas H. , Holmquist Richard , Moise Herbert
Published: October 2006

Distribution of amino acids in 68 representative proteins is compared with their distribution among 61 codons of the genetic code. Average amounts of lysine, aspartic acid, glutamic acid, and alanine are above the levels anticipated from the genetic code, and arginine, serine, leucine, cysteine, proline, and histidine are below such levels. Arginine plus lysine account for 11.0 percent of codons and aspartic acid plus glutamic acid account for 11.3 percent; thus the average charge is roughly neutral.
The Jupiter-Io Connection: An Alfvén Engine in Space
Authors: Belcher John W.
Published: October 2006

Much has been learned about the electromagnetic interaction between Jupiter and its satellite Io from in situ observations. Io, in its motion through the Io plasma torus at Jupiter, continuously generates an Alfvén wing that carries two billion kilowatts of power into the jovian ionosphere. Concurrently, Io is acted upon by a J × B force tending to propel it out of the jovian system. The energy source for these processes is the rotation of Jupiter. This unusual planet-satellite coupling serves as an archetype for the interaction of a large moving conductor with a magnetized plasma, a problem of general space and astrophysical interest.
The Microstructure of High—Critical Current Superconducting Films
Authors: Chaudhari P. , LeGoues F. K. , Segmüller Armin
Published: October 2006

The microstructure of superconducting films that have shown high-critical current densities has been studied. The films are shown to be epitaxial and contain twins and precipitates. The main difference between these films and low current carrying samples is the absence of grain boundaries. These boundaries are therefore identified as the cause of the lower critical current in ceramic samples.
Disorder in Al-Li-Cu and Al-Mn-Si Icosahedral Alloys
Authors: Heiney P. A. , Bancel P. A. , Horn P. M. , Jordan J. L. , LaPlaca S. , Angilello J. , Gayle F. W.
Published: October 2006

Faceted dendrites of icosahedral Al
6
Li
3
Cu have been studied by high-resolution x-ray scattering. The samples display long-range icosahedral symmetry both in their diffraction patterns and in their macroscopic morphology. Despite the appearance of well-defined facets, the samples have a high degree of atomic disorder. The Bragg peaks have symmetry-dependent shapes and widths that scale linearly with G
⊥
(phason momentum). The peak widths are surprisingly similar to those found in icosahedral Al-Mn-Si alloys in both their absolute magnitude and their dependence on G
⊥
. The origin of these features in models for the icosahedral phase is discussed.