bluuebunny/crossref_metadata_2025 huggingface dataset:
Echo-Planar Imaging: Magnetic Resonance Imaging in a Fraction of a Second
Authors: Stehling Michael K. , Turner Robert , Mansfield Peter
Published: October 2006

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in real time, mapping of water diffusion and temperature in tissue, mapping of organ blood pool and perfusion, functional imaging of the central nervous system, depiction of blood and cerebrospinal fluid flow dynamics, and movie imaging of the mobile fetus in utero. Through shortened patient examination times, higher patient throughput, and lower cost per MRI examination, EPI may become a powerful tool for early diagnosis of some common and potentially treatable diseases such as ischemic heart disease, stroke, and cancer.
Quiescent T Lymphocytes as an Inducible Virus Reservoir in HIV-1 Infection
Authors: Bukrinsky M. I. , Stanwick T. L. , Dempsey M. P. , Stevenson M.
Published: October 2006

To better understand the basis for human immunodeficiency virus type 1 (HIV-1) persistence and latency, the form in which viral DNA exists in the peripheral T lymphocyte reservoir of infected individuals was investigated. In asymptomatic individuals, HIV-1 was harbored predominantly as full-length, unintegrated complementary DNA. These extrachromosomal DNA forms retained the ability to integrate upon T cell activation in vitro. In patients with acquired immunodeficiency syndrome (AIDS), there was an increase in integrated relative to extrachromosomal DNA forms. By analysis of DNA from patient lymphocyte subpopulations depleted of human lymphocyte antigen-Dr receptor-positive cells, quiescent T cells were identified as the source of extrachromosomal HIV-1 DNA. Thus quiescent T lymphocytes may be a major and inducible HIV-1 reservoir in infected individuals.
How Old Are the Eukaryotes?
Authors: Schopf J. William , Oehler Dorothy Zeller
Published: October 2006

Evidence from Precambrian sediments appears to indicate that nucleated (eukaryotic) organisms had become well established and relatively diverse about 850 ± 100 million years ago and that eukaryotes were probably extant, and may have first appeared, as early as 1400 ± 100 million years ago.
Microfossils in
Conophyton
from the Soviet Union and Their Bearing on Precambrian Biostratigraphy
Authors: Schopf J. William , Sovietov Yu. K.
Published: October 2006

Silicified specimens of the Vendian (late Precambrian) "index fossil"
Conophyton gaubitza
from South Kazakstan contain a diverse assemblage of well-preserved cyanophytic and apparently eukaryotic algae, the first stromatolitic microbiota to be reported from the Soviet Union. Unlike the stromatolites in which they occur, the microorganisms that apparently built this form of
Conophyton
did not become extinct at the end of the Precambrian.
Infrared Thermal Mapping of the Martian Surface and Atmosphere: First Results
Authors: Kieffer Hugh H. , Chase Stillman C. , Miner Ellis D. , Palluconi Frank Don , Münch Guido , Neugebauer Gerry , Martin Terry Z.
Published: October 2006

The Viking infrared thermal mapper measures the thermal emission of the martian surface and atmosphere and the total reflected sunlight. With the high resolution and dense coverage being achieved, planetwide thermal structure is apparent at large and small scales. The thermal behavior of the best-observed areas, the landing sites, cannot be explained by simple homogeneous models. The data contain clear indications for the relevance of additional factors such as detailed surface texture and the occurrence of clouds. Areas in the polar night have temperatures distinctly lower than the CO
2
condensation point at the surface pressure. This observation implies that the annual atmospheric condensation is less than previously assumed and that either thick CO
2
clouds exist at the 20-kilometer level or that the polar atmosphere is locally enriched by noncondensable gases.
Argon Content of the Martian Atmosphere at the Viking 1 Landing Site: Analysis by X-ray Fluorescence Spectroscopy
Authors: Clark Benton C. , Toulmin Priestley , Baird A. K. , Keil Klaus , Rose Harry J.
Published: October 2006

The argon content of the martian atmosphere at the Viking 1 landing site is ≤ 0.15 millibar or ≤ 2 percent by volume (95 percent confidence level).
The Viking Landing Sites: Selection and Certification
Authors: Masursky H. , Crabill N. L.
Published: October 2006

During the past several years the Viking project developed plans to use Viking orbiter instruments and Earth-based radar to certify the suitability of the landing sites selected as the safest and most scientifically rewarding using Mariner 9 data. During June and July 1976, the Earth-based radar and orbital spacecraft observations of some of the prime and backup sites were completed. The results of these combined observations indicated that the Viking 1 prime landing area in the Chryse region of Mars is geologically varied and possibly more hazardous than expected, and was not certifiable as a site for the Viking 1 landing. Consequently, the site certification effort had to be drastically modified and lengthened to search for a site that might be safe enough to attempt to land. The selected site considered at 47.5°W, 22.4°N represented a compromise between desirable characteristics observed with visual images and those inferred from Earth-based radar. It lies in the Chryse region about 900 kilometers northwest of the original site. Viking 1 landed successfully at this site on 20 July 1976.
A Hexagonal (Wurtzite) Form of Silicon
Authors: Jennings H. M. , Richman M. H.
Published: October 2006

The existence of a hexagonal (wurtzite) form of silicon, similar to that form of diamond (carbon) observed in meteorites and in the laboratory, has been identified by x-ray diffraction in reaction-bonded silicon nitride containing unreacted silicon. The presence of this phase is due to stresses created in the silicon by the nitridation reaction.
The "Soil" of Mars (Viking 1)
Authors: Shorthill Richard W. , Moore Henry J. , Scott Ronald F. , Hutton Robert E. , Liebes Sidney , Spitzer Cary R.
Published: October 2006

The location of the Viking 1 lander is most ideal for the study of soil properties because it has one footpad in soft material and one on hard material. As each soil sample was acquired, information on soil properties was obtained. Although analysis is still under way, early results on bulk density, particle size, angle of internal friction, cohesion, adhesion, and penetration resistance of the soil of Mars are presented.
Radiohalos in Coalified Wood: New Evidence Relating to the Time of Uranium Introduction and Coalification
Authors: Gentry Robert V. , Christie Warner H. , Smith David H. , Emery J. F. , Reynolds S. A. , Walker Raymond , Cristy S. S. , Gentry P. A.
Published: October 2006

The discovery of embryonic halos around uranium-rich sites that exhibit very high
238
U/
206
Pb ratios suggests that uranium introduction may have occurred far more recently than previously supposed. The discovery of
210
Po halos derived from uranium daughters, some elliptical in shape, further suggests that uranium-daughter infiltration occurred prior to coalification when the radionuclide transport rate was relatively high and the matrix still plastically deformable.
High Photosynthetic Capacity of a Winter Annual in Death Valley
Authors: Mooney H. A. , Ehleringer J. , Berry J. A.
Published: October 2006

Camissonia claviformis
, a winter annual of Death Valley, California, that fixes carbon dioxide by the C
3
mechanism, has an in situ photosynthetic rate at midday in spring of nearly 6 nanomoles of carbon dioxide per square centimeter per second—an exceptionally high rate. Camissonia fixes absorbed noon sunlight in the 400- to 700-nanometer region into chemical energy with an efficiency of 8.5 percent, which is 80 percent of that theoretically possible for intact leaves. This performance is primarily due to an unusual capacity to utilize high irradiances. Factors associated with this include a high stomatal conductance to carbon dioxide and high levels of soluble protein and ribulose-1,5-diphosphate carboxylase.
Ascorbic Acid as a Factor Controlling the Development of Cyanide-Insensitive Respiration
Authors: Arrigoni Oreste , Arrigoni-Liso Rosalia , Calabrese Giuseppe
Published: October 2006

Lycorine, an inhibitor of ascorbic acid biosynthesis, prevents the elicitation of KCN-insensitive respiration in aerated potato tuber slices. Ascorbic acid administration prevents the lycorine effect. Because KCN-insensitive respiration, which takes place during the aerobic incubation of potato tuber slices, specifically depends on the synthesis of new proteins, we suggest that ascorbic acid could be required to carry out a synthetic process.
Greenhouse Effects due to Man-Made Perturbations of Trace Gases
Authors: Wang W. C. , Yung Y. L. , Lacis A. A. , Mo T. , Hansen J. E.
Published: October 2006

Nitrous oxide, methane, ammonia, and a number of other trace constituents in the earth's atmosphere have infrared absorption bands in the spectral region 7 to 14 μm and contribute to the atmospheric greenhouse effect. The concentrations of these trace gases may undergo substantial changes because of man's activities. Extensive use of chemical fertilizers and combustion of fossil fuels may perturb the nitrogen cycle, leading to increases in atmospheric N
2
O, and the same perturbing processes may increase the amounts of atmospheric CH
4
and NH
3
. We use a one-dimensional radiative-convective model for the atmospheric thermal structure to compute the change in the surface temperature of the earth for large assumed increases in the trace gas concentrations; doubling the N
2
O, CH
4
, and NH
3
concentrations is found to cause additive increases in the surface temperature of 0.7°, 0.3°, and 0.1°K, respectively. These systematic effects on the earth's radiation budget would have substantial climatic significance. It is therefore important that the abundances of these trace gases be accurately monitored to determine the actual trends of their concentrations.
Variations in the Earth's Orbit: Pacemaker of the Ice Ages
Authors: Hays J. D. , Imbrie John , Shackleton N. J.
Published: October 2006

1) Three indices of global climate have been monitored in the record of the past 450,000 years in Southern Hemisphere ocean-floor sediments.

2) Over the frequency range 10
–4
to 10
–5
cycle per year, climatic variance of these records is concentrated in three discrete spectral peaks at periods of 23,000, 42,000, and approximately 100,000 years. These peaks correspond to the dominant periods of the earth's solar orbit, and contain respectively about 10, 25, and 50 percent of the climatic variance.

3) The 42,000-year climatic component has the same period as variations in the obliquity of the earth's axis and retains a constant phase relationship with it.

4) The 23,000-year portion of the variance displays the same periods (about 23,000 and 19,000 years) as the quasi-periodic precession index.

5) The dominant, 100,000-year climatic

component has an average period close to, and is in phase with, orbital eccentricity. Unlike the correlations between climate and the higher-frequency orbital variations (which can be explained on the assumption that the climate system responds linearly to orbital forcing), an explanation of the correlation between climate and eccentricity probably requires an assumption of nonlinearity.

6) It is concluded that changes in the earth's orbital geometry are the fundamental cause of the succession of Quaternary ice ages.

7) A model of future climate based on the observed orbital-climate relationships, but ignoring anthropogenic effects, predicts that the long-term trend over the next several thousand years is toward extensive Northern Hemisphere glaciation.
Mineralogic and Petrologic Implications of Viking Geochemical Results From Mars: Interim Report
Authors: Baird A. K. , Toulmin Priestley , Clark Benton C. , Rose Harry J. , Keil Klaus , Christian Ralph P. , Gooding James L.
Published: October 2006

Chemical results from four samples of martian fines delivered to Viking landers 1 and 2 are remarkably similar in that they all have high iron; moderate magnesium, calcium, and sulfur; low aluminum; and apparently very low alkalies and trace elements. This composition is best interpreted as representing the weathering products of mafic igneous rocks. A mineralogic model, derived from computer mixing studies and laboratory analog preparations, suggests that Mars fines could be an intimate mixture of about 80 percent iron-rich clay, about 10 percent magnesium sulfate (kieserite?), about 5 percent carbonate (calcite), and about 5 percent iron oxides (hematite, magnetite, maghemite, goethite?). The mafic nature of the present fines (distributed globally) and their probable source rocks seems to preclude large-scale planetary differentiation of a terrestrial nature.
Chromosome Aberrations and Cancer
Authors: Solomon Ellen , Borrow Julian , Goddard Audrey D.
Published: October 2006

Cancer may be defined as a progressive series of genetic events that occur in a single clone of cells because of alterations in a limited number of specific genes: the oncogenes and tumor suppressor genes. The association of consistent chromosome aberrations with particular types of cancer has led to the identification of some of these genes and the elucidation of their mechanisms of action. Consistent chromosome aberrations are observed not only in rare tumor types but also in the relatively common lung, colon, and breast cancers. Identification of additional mutated genes through other chromosomal abnormalities will lead to a more complete molecular description of oncogenesis.
Posttranslational Glutamylation of α-tubulin
Authors: Eddé Bernard , Rossier Jean , Le Caer Jean-Pierre , Desbruyères Elizabeth , Gros François , Denoulet Philippe
Published: October 2006

The high degree of tubulin heterogeneity in neurons is controlled mainly at the posttranslational level. Several variants of α-tubulin can be posttranslationally labeled after incubation of cells with [
3
H]acetate or [
3
H]glutamate. Peptides carrying the radioactive moiety were purified by high-performance liquid chromatography. Amino acid analysis, Edman degradation sequencing, and mass spectrometric analysis of these peptides led to the characterization of a posttranslational modification consisting of the successive addition of glutamyl units on the γ-carboxyl group of a glutamate residue (Glu
445
). This modification, localized within a region of α-tubulin that is important in the interactions of tubulin with microtubule-associated proteins and calcium, could play a role in regulating microtubule dynamics.
Microwave Spectroscopic Imagery of the Earth
Authors: Staelin D. H. , Rosenkranz P. W. , Barath F. T. , Johnston E. J. , Waters J. W.
Published: October 2006

The microwave spectrometer on the Nimbus 6 satellite has produced the first microwave spectral images of the earth. It has yielded global maps of (i) atmospheric temperature profiles, (ii) the distributions of water vapor and liquid water over ocean, and (iii) the coverage and type of ice and snow. The method has potential for operational synoptic monitoring.
Early Flakes from Sozudai, Japan: Are They Man-Made?
Authors: Bleed Peter
Published: October 2006

Some archeologists consider the lowest component of the Sozudai site to be evidence of a human occupation of southern Japan during the early Würm period. Others deny that the Sozudai objects are artifacts. With separate test procedures, flakes in the Sozudai assemblage were identified and compared to the standard developed by A. S. Barnes. These procedures indicate that flakes in the Sozudai assemblage are of human origin.
Amyloid β Protein Precursor Gene and Hereditary Cerebral Hemorrhage with Amyloidosis (Dutch)
Authors: Van Broeckhoven C. , Haan J. , Bakker E. , Hardy J. A. , Van Hul W. , Wehnert A. , Vegter-Van der Vlis M. , Roos R. A. C.
Published: October 2006

Human hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D), an autosomal dominant form of cerebral amyloid angiopathy (CAA), is characterized by extensive amyloid deposition in the small leptomeningeal arteries and cortical arterioles, which lead to an early death of those afflicted in their fifth or sixth decade. Immunohistochemical and biochemical studies have indicated that the amyloid subunit in HCHWA-D is antigenically related to and homologous in sequence with the amyloid β protein isolated from brains of patients with Alzheimer's disease and Down syndrome. The amyloid β protein is encoded by the amyloid β protein precursor (APP) gene located on chromosome 21. Restriction fragment length polymorphisms detected by the APP gene were used to examine whether this gene is a candidate for the genetic defect in HCHWA-D. The data indicate that the APP gene is tightly linked to HCHWA-D and therefore, in contrast to familial Alzheimer's disease, cannot be excluded as the site of mutation in HCHWA-D.
Inhibition of Factor VIIa-Tissue Factor Coagulation Activity by a Hybrid Protein
Authors: Girard Thomas J. , MacPhail Louise A. , Likert Karen M. , Novotny William F. , Miletich Joseph P. , Broze George J.
Published: October 2006

Lipoprotein-associated coagulation inhibitor (LACI) appears to inhibit tissue factor (TF)-induced blood coagulation by forming a quaternary inhibitory complex containing factor Xa, LACI, factor VIIa, and TF. A genetically engineered hybrid protein consisting of the light chain of factor Xa and the first Kunitz-type inhibitor domain of LACI is shown to directly inhibit the activity of the factor VIIa-TF catalytic complex. Unlike inhibition of factor VIIa-TF activity by native LACI, inhibition by the hybrid protein is not dependent on factor Xa. In an assay of TF-induced coagulation, 50% TF inhibition occurs with hybrid protein at 35 nanograms per milliliter, whereas LACI at 2.5 micrograms per milliliter is required for an equivalent effect. γ-Carboxylation of glutamic acid residues in the factor Xa light chain portion of the hybrid protein is required for inhibitory activity, indicating that the first Kunitz-type domain of LACI alone is not sufficient for inhibition of factor VIIa-TF.
Cloning and Expression of a Rat Brain GABA Transporter
Authors: Guastella John , Nelson Nathan , Nelson Hannah , Czyzyk Linda , Keynan Shoshi , Miedel May C. , Davidson Norman , Lester Henry A. , Kanner Baruch I.
Published: October 2006

A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter γ-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in
Xenopus
oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated [
3
H]GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium-and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters. The GAT-1 protein shares antigenic determinants with a native rat brain GABA transporter. The nucleotide sequence of GAT-1 predicts a protein of 599 amino acids with a molecular weight of 67 kilodaltons. Hydropathy analysis of the deduced protein suggests multiple transmembrane regions, a feature shared by several cloned transporters; however, database searches indicate that GAT-1 is not homologous to any previously identified proteins. Therefore, GAT-1 appears to be a member of a previously uncharacterized family of transport molecules.
Germ Line p53 Mutations in a Familial Syndrome of Breast Cancer, Sarcomas, and Other Neoplasms
Authors: Malkin David , Li Frederick P. , Strong Louise C. , Fraumeni Joseph F. , Nelson Camille E. , Kim David H. , Kassel Jayne , Gryka Magdalena A. , Bischoff Farideh Z. , Tainsky Michael A. , Friend Stephen H.
Published: October 2006

Familial cancer syndromes have helped to define the role of tumor suppressor genes in the development of cancer. The dominantly inherited Li-Fraumeni syndrome (LFS) is of particular interest because of the diversity of childhood and adult tumors that occur in affected individuals. The rarity and high mortality of LFS precluded formal linkage analysis. The alternative approach was to select the most plausible candidate gene. The tumor suppressor gene, p53, was studied because of previous indications that this gene is inactivated in the sporadic (nonfamilial) forms of most cancers that are associated with LFS. Germ line p53 mutations have been detected in all five LFS families analyzed. These mutations do not produce amounts of mutant p53 protein expected to exert a trans-dominant loss of function effect on wild-type p53 protein. The frequency of germ line p53 mutations can now be examined in additional families with LFS, and in other cancer patients and families with clinical features that might be attributed to the mutation.
Two-Billion-Year Granulites in the Late Precambrian Metamorphic Basement Along the Southern Peruvian Coast
Authors: Dalmayrac B. , Lancelot J. R. , Leyreloup A.
Published: October 2006

Uranium-lead data indicate that the high-pressure granulitic and charnockitic nuclei within the medium-grade metamorphic complex of the Peruvian coastal area must be related to an orogenic event 2 × 10
9
years ago. As in western Africa and Brazil, this old granulitic basement is reworked by Late Precambrian orogeny. Its presence along the Peru-Chile Trench must be taken into account in interpreting the anomalously high strontium isotopic ratios of recent calc-alkaline volcanism.
Calcium Oxalate: Occurrence in Soils and Effect on Nutrient and Geochemical Cycles
Authors: Graustein William C. , Cromack Kermit , Sollins Phillip
Published: October 2006

Whewellite and weddellite, calcium salts of oxalic acid, have been found in the litter layer of several different soils, indicating that oxalate is a major metabolic product of fungi in natural environments. The presence of oxalate in soil solution speeds weathering of soil minerals and increases the availability of nutrients to vegetation.
Evidence for 115 Kilometers of Right Slip on the San Gregorio-Hosgri Fault Trend
Authors: Graham S. A. , Dickinson W. R.
Published: October 2006

The San Gregorio-Hosgri fault trend is a component of the San Andreas fault system on which there may have been about 115 kilometers of post-early Miocene right-lateral strike slip. If so, right slip on the San Andreas and San Gregorio-Hosgri faults accounts for most of the movement between the Pacific and North American plates since mid-Miocene time. Furthermore, the magnitude of right slip on a Paleogene proto-San Andreas fault inferred from the present distribution of granitic basement is reduced considerably when Neogene-Recent San Gregorio-Hosgri right slip is taken into account.
Atmospheric Carbon Dioxide and Carbon Reservoir Changes
Authors: Stuiver Minze
Published: October 2006

The net release of CO
2
from the biosphere to the atmosphere between 1850 and 1950 is estimated to amount to 1.2 × 10
9
tons of carbon per year. During this interval, changes in land use reduced the total terrestrial biomass by 7 percent. There has been a smaller reduction in biomass over the last few decades. In the middle 19th century the air had a CO
2
content of approximately 268 parts per million, and the total increase in atmospheric CO
2
content since 1850 has been 18 percent. Major sinks for fossil fuel CO
2
are the thermocline regions of large oceanic gyres. About 34 percent of the excess CO
2
generated so far is stored in surface and thermocline gyre waters, and 13 percent has been advected into the deep sea. This leaves an airborne fraction of 53 percent.
Localized Compressional Velocity Decrease Precursory to the Kalapana, Hawaii, Earthquake
Authors: Johnston Arch C.
Published: October 2006

A delay in the arrival times of compressional or
P
waves of 0.15 to 0.2 second from deep distant earthquakes has been detected at the closest seismograph station to the 20 November 1975 earthquake at Kalapana, Hawaii (surface-wave magnitude
M
S
= 7.2). This delay appeared approximately 3.5 years prior to the quake, and travel times returned to normal several months before it. The
P
-wave arrival times at other nearby stations remained constant during this period, an indication that the decreased velocity implied by the delay in travel time was associated with this normal-faulting earthquake and was confined to distances less than 20 kilometers from the epicenter.
Aeolanthus biformifolius
De Wild.: A Hyperaccumulator of Copper from Zaïre
Authors: Malaisse F. , Gregoire J. , Brooks R. R. , Morrison R. S. , Reeves R. D.
Published: October 2006

Aeolanthus biformifolius
(Labiatae) from Shaba Province, Zaïre, has been shown to be a hyperaccumulator of copper. The copper content of the total plant during the rest period after the rainy season was 1.3 percent (dry weight basis) and is easily the highest copper concentration ever found in living material. This species should be classified as a "copper flower" because of its exclusive occurrence over mineralized ground.
Diversity in Tropical Rain Forests and Coral Reefs
Authors: Connell Joseph H.
Published: October 2006

The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained.
Avian Eggs: Thermoregulatory Value of Very High Near-Infrared Reflectance
Authors: Bakken G. S. , Vanderbilt V. C. , Buttemer W. A. , Dawson W. R.
Published: October 2006

Studies of the spectral reflectance of the eggs of 25 species of birds from nine families disclosed uniformly high reflectance (often above 90 percent) in the near infrared. This property is associated with the presence of the eggshell pigments protoporphyrin and the bilins. These pigments allow coloration for cryptic or other purposes with minimum solar heating, a combination not possible with the melanin pigments typical of vertebrates.
Night-Shocker: Predatory Behavior of the Pacific Electric Ray (
Torpedo californica
)
Authors: Bray Richard N. , Hixon Mark A.
Published: October 2006

Diving observations off Santa Barbara, California, indicate that Pacific electric rays (
Torpedo californica
) enter inshore reefs at night and actively prey on fish with the aid of powerful electric discharges.
(
S
)-9-(2,3-Dihydroxypropyl)adenine: An Aliphatic Nucleoside Analog with Broad-Spectrum Antiviral Activity
Authors: De Clercq Erik , Descamps Johan , De Somer Pierre , Holý Antonín
Published: October 2006

(
S
)-9-(2,3-Dihydroxypropyl)adenine, a novel nucleoside analog, the sugar moiety of which is replaced by an aliphatic chain, inhibits the replication in vitro of several DNA and RNA viruses, including vaccinia, herpes simplex (types 1 and 2), measles, and vesicular stomatitis. It is also effective in vivo in reducing the mortality rate of mice inoculated intranasally with vesicular stomatitis virus.
Reshaping the Cortical Motor Map by Unmasking Latent Intracortical Connections
Authors: Jacobs Kimberle M. , Donoghue John P.
Published: October 2006

The primary motor cortex (MI) contains a map organized so that contralateral limb or facial movements are elicited by electrical stimulation within separate medial to lateral MI regions. Within hours of a peripheral nerve transection in adult rats, movements represented in neighboring MI areas are evoked from the cortical territory of the affected body part. One potential mechanism for reorganization is that adjacent cortical regions expand when preexisting lateral excitatory connections are unmasked by decreased intracortical inhibition. During pharmacological blockade of cortical inhibition in one part of the MI representation, movements of neighboring representations were evoked by stimulation in adjacent MI areas. These results suggest that intracortical connections form a substrate for reorganization of cortical maps and that inhibitory circuits are critically placed to maintain or readjust the form of cortical motor representations.
Cadherin Cell Adhesion Receptors as a Morphogenetic Regulator
Authors: Takeichi Masatoshi
Published: October 2006

Cadherins are a family of cell adhesion receptors that are crucial for the mutual association of vertebrate cells. Through their homophilic binding interactions, cadherins play a role in cell-sorting mechanisms, conferring adhesion specificities on cells. The regulated expression of cadherins also controls cell polarity and tissue morphology. Cadherins are thus considered to be important regulators of morphogenesis. Moreover, pathological examinations suggest that the down-regulation of cadherin expression is associated with the invasiveness of tumor cells.
P
-State Pairing and the Ferromagnetism of ZrZn
2
Authors: Enz C. P. , Matthias B. T.
Published: October 2006

It is ascertained that, within the range of stability, the transition temperature of the superconducting solutions between Ti and Zr and between Zr and Hf, and the Curie point of the corresponding ferromagnetic solutions between TiZn
2
and ZrZn
2
and between ZrZn
2
and HfZn
2
, follow a parallel behavior. From this correlation it is concluded that the weak itinerant ferromagnetism of ZrZn
2
must be due to electron-phonon interaction. Theoretical arguments are advanced to show that the underlying mechanism is hindered
p
-state pairing, due to a strongly localized repulsive part of the pair-potential that acts as a Hubbard interaction and gives rise to a Stoner instability.
Adrenergic Excitation of Cutaneous Pain Receptors Induced by Peripheral Nerve Injury
Authors: Sato Jun , Perl Edward R.
Published: October 2006

The mechanisms by which peripheral nerve injuries sometimes lead to causalgia, aberrant burning pain peripheral to the site of nerve damage, are uncertain, although the sympathetic nervous system is known to be involved. Whether such syndromes could be the result of the development of responsiveness by some cutaneous pain receptors (C-fiber nociceptors) to sympathetic efferent activity as a consequence of the nerve injury was tested in an animal model. After nerve damage but not in its absence, sympathetic stimulation and norepinephrine were excitatory for a subset of skin C-fiber nociceptors and enhanced the responsiveness of these nociceptors to tissue-damaging stimulation. These effects were demonstrable within days after nerve lesions, occurred at the cutaneous receptive terminal region, were manifest in sensory fibers that had not degenerated after the injury, and were mediated by α
2
-adrenergic-like receptors.
Calcium as a Coagonist of Inositol 1,4,5-Trisphosphate-Induced Calcium Release
Authors: Finch Elizabeth A. , Turner Timothy J. , Goldin Stanley M.
Published: October 2006

Inositol 1,4,5-trisphosphate (IP
3
)-induced calcium release from intracellular stores is a regulator of cytosolic-free calcium levels. The subsecond kinetics and regulation of IP
3
-induced calcium-45 release from synaptosome-derived microsomal vesicles were resolved by rapid superfusion. Extravesicular calcium acted as a coagonist, potentiating the transient IP
3
-induced release of calcium-45. Thus, rapid elevation of cytosolic calcium levels may trigger IP
3
-induced calcium release in vivo. Extravesicular calcium also produced a more slowly developing, reversible inhibition of IP
3
-induced calcium-45 release. Sequential positive and negative feedback regulation by calcium of IP
3
-induced calcium release may contribute to transients and oscillations of cytosolic-free calcium in vivo.
Quantitative Elemental Analyses by Plasma Emission Spectroscopy
Authors: Fassel Velmer A.
Published: October 2006

Argon-supported inductively coupled plasmas operated at atmospheric pressures are excellent vaporization-atomization-excitation-ionization sources for analytical atomic emission spectroscopy. When a polychromator is used for observing the emitted spectra, the metals and metalloids can be determined simultaneously at the ultratrace, trace, minor, and major concentration levels under one set of experimental parameters. Alternatively, programmable scanning spectrometers may be utilized for sequential determinations. The atomization-excitation process is remarkably free of interelement interactions, the powers of detection are in the part per billion range for most elements, and sample manipulation requirements prior to analyses are often minimal. The technique meets the requirements of an analytical system for the simultaneous or sequential determination of the elements at all concentration levels to an unusual high degree.
Neodymium and Strontium Isotope Evidence for Crustal Contamination of Continental Volcanics
Authors: Carter S. R. , Evensen N. M. , Hamilton P. J. , O'Nions R. K.
Published: October 2006

Combined neodymium and strontium isotope studies on Tertiary volcanics from northwest Scotland indicate that their parental mantle isotopic compositions have been substantially modified in many instances by contamination with the Precambrian continental crust through which they were erupted. The occurrence of samarium-neodymium and rubidium-strontium "pseudoisochrons" of different ages in these contaminated continental volcanics indicates that they are artifacts of the contamination processes and have no temporal significance with respect to mantle fractionation events.
Paleocirculation of the Deep North Atlantic: 150,000-Year Record of Benthic Foraminifera and Oxygen-18
Authors: Streeter S. Stephen , Shackleton N. J.
Published: October 2006

Benthic foraminiferal faunas in a piston core from 3331 meters at 44°N on the Mid-Atlantic Ridge show striking variations in the relative abundance of species.
Uvigerina peregrina
, which is broadly distributed today in the South Atlantic and in the Pacific in water that has been long isolated from the surface, is absent in the North and Equatorial Atlantic at depths occupied by highly oxygenated North Atlantic deep water. This species dominated the fauna at this site for much of the past 150,000 years. It is suggested that North Atlantic deepwater production was much reduced or eliminated at times of
Uvigerina peregrina
abundance, as a result of cooling and stratification of the Norwegian Sea surface, coincident with the times of the southward migration of the polar front in the North Atlantic.
Sea-Level Fluctuations and Deep-Sea Sedimentation Rates
Authors: Worsley Thomas R. , Davies Thomas A.
Published: October 2006

Sediment accumulation rate curves from 95 drilled cores from the Pacific basin and sea-level curves derived from continental margin seismic stratigraphy show that high biogenous sediment accumulation rates correspond to low eustatic sea levels for at least the last 48 million years. This relationship fits a simple model of high sea levels producing lower land/sea ratios and hence slower chemical erosion of the continents, and vice versa.
Hydraulic Transients: A Seismic Source in Volcanoes and Glaciers
Authors: St. Lawrence William , Qamar Anthony
Published: October 2006

A source for certain low-frequency seismic waves is postulated in terms of the water hammer effect. The time-dependent displacement of a water-filled subglacial conduit is analyzed to demonstrate the nature of the source. Preliminary energy calculations and the observation of hydraulically generated seismic radiation from a dam indicate the plausibility of the proposed source.
Strain-Softening Instability Model for the San Fernando Earthquake
Authors: Stuart W. D.
Published: October 2006

Changes in the ground elevation observed before and immediately after the 1971 San Fernando, California, earthquake are consistent with a theoretical model in which fault zone rocks are strain-softening after peak stress. The model implies that the slip rate of the fault increased to about 0.1 meter per year near the focus before the earthquake.
Submarine Thermal Springs on the Galápagos Rift
Authors: Corliss John B. , Dymond Jack , Gordon Louis I. , Edmond John M. , von Herzen Richard P. , Ballard Robert D. , Green Kenneth , Williams David , Bainbridge Arnold , Crane Kathy , van Andel Tjeerd H.
Published: October 2006

The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible
Alvin
. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis.
Rearing Regimen Producing Piglet Diarrhea (Rotavirus) and Its Relevance to Acute Infantile Diarrhea
Authors: Lecce James G. , King Margaret W. , Dorsey William E.
Published: October 2006

Piglets were weaned when 1 day old and thus were denied further access to the antibodies supplied by their dam's milk. They were placed in a nursery in which contamination by the ubiquitous rotavirus steadily increased with continuous use causing a progressive increase in the incidence of vomiting, diarrhea, and death among the piglets. A similar syndrome involving an antigenically related rotavirus and analogous management practices occurs in human infants.
Biologically Active Pituitary Hormones in the Rat Brain Amygdaloid Nucleus
Authors: Pacold S. T. , Kirsteins L. , Hojvat S. , Lawrence A. M. , Hagen T. C.
Published: October 2006

While an attempt was being made to identify the source of the growth hormone releasing factor present in cerebral spinal fluid of man, it was discovered that cells of the rat amygdaloid nucleus, grown in tissue culture, produce a material that is immunologically and chromatographically identical to growth hormone found in the pituitary. Immunoperoxidase staining revealed dense accumulation of the peroxidase-antibody to growth hormone complex in amygdala cells. Significant amounts of growth hormone and adrenocorticotropin could be extracted from this limbic structure. Extracts containing immunoequivalent amounts of growth hormone were measured by bioassay in hypophysectomized rats. Stimulation of the growth of epiphyseal cartilage by extracts of the amygdala was comparable to the stimulation by extracts of anterior pituitary glands. The stimulatory effect of amygdala extracts on adrenal and gonadal size and weight and on growth of thyroid follicular epithelium was also comparable to that of pituitary extracts.
Synchronous Bursts of Action Potentials in Ganglion Cells of the Developing Mammalian Retina
Authors: Meister Markus , Wong Rachel O. L. , Baylor Denis A. , Shatz Carla J.
Published: October 2006

The development of orderly connections in the mammalian visual system depends on action potentials in the optic nerve fibers, even before the retina receives visual input. In particular, it has been suggested that correlated firing of retinal ganglion cells in the same eye directs the segregation of their synaptic terminals into eye-specific layers within the lateral geniculate nucleus. Such correlations in electrical activity were found by simultaneous recording of the extracellular action potentials of up to 100 ganglion cells in the isolated retina of the newborn ferret and the fetal cat. These neurons fired spikes in nearly synchronous bursts lasting a few seconds and separated by 1 to 2 minutes of silence. Individual bursts consisted of a wave of excitation, several hundred micrometers wide, sweeping across the retina at about 100 micrometers per second. These concerted firing patterns have the appropriate spatial and temporal properties to guide the refinement of connections between the retina and the lateral geniculate nucleus.
Spectral Analysis of Zooplankton Spatial Heterogeneity
Authors: Mackas David L. , Boyd Carl M.
Published: October 2006

Continuous estimates were obtained of zooplankton abundance, chlorophyll fluorescence, and water temperature along 10- to 100-kilometer transects of the North Sea. Spectral analysis methods were applied to the data. The "patchiness" of the plankton was distributed over all the length scales resolved with no indication of a characteristic patch size. The relative intensity of the zooplankton patchiness was greater than that of the phytoplankton at all spatial scales, with this difference becoming progressively greater for finer-scale features. In the North Sea data, the concentrations of phytoplankton and zooplankton consistently showed negative spatial correlations.
Aluminum Leaching Response to Acid Precipitation: Effects on High-Elevation Watersheds in the Northeast
Authors: Cronan Christopher S. , Schofield Carl L.
Published: October 2006

Atmospheric inputs of sulfuric acid and nitric acid to noncalcareous higher-elevation watersheds in the White Mountain and Adirondack regions lead to comparatively high concentrations of dissolved aluminum in surface and ground waters. This phenomenon appears to result from modern increases in soil aluminum leaching. Transport of this aluminum to acidified lakes can lead to fish mortality. Combined results from areas of silicate bedrock in the United States and Europe suggest that aluminum represents an important biogeochemical linkage between terrestrial and aquatic environments exposed to acid precipitation.
Brontides: Natural Explosive Noises
Authors: Gold Thomas , Soter Steven
Published: October 2006

Episodes of explosive noises of natural origin, or brontides, have been well documented, often in association with seismic activity and in a few cases as precursors to major earthquakes. Ground-to-air acoustic transmission from shallow earthquakes can account for many of these episodes, but not for all, and other causes, such as the sudden eruption of gas from high-pressure sources in the ground may at times have been responsible. Confusion with distant thunder or artillery at times of anomalous sound propagation complicates the analysis, and more recently the greatly increased frequency of artificial explosive noises and sonic booms has tended to mask the recognition of natural brontides.
Deep Crustal Drilling in the North Atlantic Ocean
Authors: Hall J. M. , Robinson P. T.
Published: October 2006

Oceanic crustal drilling by R. V.
Glomar Challenger
at 15 sites in the North Atlantic has led to a complex picture of the upper half kilometer of the crust. Elements of the picture include the absence of the source for linear magnetic anomalies, marked episodicity of volcanic activity, ubiquitous low temperature alteration and evidence for large scale tectonic disturbance. Comparison sections in the Pacific and much deeper crustal drilling are needed to attack problems arising from the North Atlantic results.
Stratospheric Wave Spectra Resembling Turbulence
Authors: Dewan Edmond M.
Published: October 2006

Pollution effects on ozone raise the question of the significance of turbulence in vertical transport in the stratosphere. The aircraft in situ measurements of velocity fluctuations previously employed to estimate turbulence transport were, it is hypothesized, due to atmospheric waves, despite their classical turbulence spectrum. This new hypothesis implies that previous turbulence estimates are invalid. Experimental tests are suggested.
Encounter with Venus: An Update
Authors: Colin Lawrence
Published: October 2006

This report is an introduction to the accompanying collection of early results from the Pioneer Venus orbiter and multiprobe missions, which encountered Venus on 4 December and 9 December 1978, respectively. Initial results for the multiprobe mission and for the first 30 days of the orbiter mission were reported in the 23 February issue of
Science
. Additional mission features and updated mission parameters based on refined tracking data and trajectory computations are presented here. New scientific results for both missions are given in the subsequent reports which cover the first 130 days (or orbits) of the nominal 243-day orbiter mission.
Energy Analysis of the Solar Power Satellite
Authors: Herendeen R. A. , Kary T. , Rebitzer J.
Published: October 2006

The energy requirements to build and operate the proposed Solar Power Satellite are evaluated and compared with the energy it produces. Because the technology is so speculative, uncertainty is explicitly accounted for. For a proposed 10-gigawatt satellite system, the energy ratio, defined as the electrical energy produced divided by the primary nonrenewable energy required over the lifetime of the system, is of order 2, where a ratio of 1 indicates the energy breakeven point. This is significantly below the energy ratio of today's electricity technologies such as light-water nuclear or coal-fired electric plants.
Mosquitoes: Biting Behavior Inhibited by Ecdysone
Authors: Beach Raymond
Published: October 2006

Biting in
Anopheles freeborni
is inhibited during ovarian development. Biting inhibition is triggered by ecdysone, a hormone produced by the ovary during oogenesis. Biting inhibition does not occur in females after the removal of ovaries, but is restored by replacing ovaries or injecting ecdysone. Ecdysone also inhibits biting behavior when it is fed to females. This is the first example of ecdysone controlling a nonmolt-related behavior in insects.
Photosynthetic Marine Mollusks: In vivo
14
C Incorporation into Metabolites of the Sacoglossan
Placobranchus ocellatus
Authors: Ireland Chris , Scheuer Paul J.
Published: October 2006

In seawater enriched with carbon-14-labeled sodium hydrogen carbonate the sacoglossan
Placobranchus ocellatus
when exposed to light incorporates carbon-14 at a rate 50-fold of that for animals kept in the dark. 9,10-Deoxytridachione, a secondary metabolite of the mollusk, undergoes a photorearrangement to photodeoxytridachione in vivo.
Can Rapid Climatic Change Cause Volcanic Eruptions?
Authors: Rampino Michael R. , Self Stephen , Fairbridge Rhodes W.
Published: October 2006

Many major volcanic eruptions coincide with cooling trends of decadal or longer duration that began significantly before the eruptions. Dust veils provide positive feedback for short-term (less than 10 year) global cooling, but seem unlikely to trigger glaciations or even minor climate fluctuations in the 10- to 100-year range. On the contrary, variations in climate lead to stress changes on the earth's crust—for instance, by loading and unloading of ice and water masses and by axial and spin-rate changes that might augment volcanic (and seismic) potential.
Geology of the Athabasca Oil Sands
Authors: Mossop Grant D.
Published: October 2006

In-place bitumen resources in the Alberta oil sands are estimated at 1350 billion barrels. Open-pit mining and hot water extraction methods, which involve the handling of huge tonnages of earth materials, are being employed in the two commercial plants now operating. In situ recovery methods will be required to tap the 90 percent of reserves that are too deeply buried to be surface mined. Development of in situ technologies will be painstaking and expensive, and success will hinge on their compatibility with extremely complex geological conditions in the subsurface.