bluuebunny/crossref_metadata_2025 huggingface dataset:
Allotropy in Some Rare-Earth Metals at High Pressures
Authors: Piermarini G. J. , Weir C. E.
Published: October 2006

Allotropes of lanthanum, cerium, praseodymium, and neodymium have been observed at elevated pressures with an x-ray diffraction camera which incorporates a diamondanvil, high-pressure cell. In each case a high-pressure modification was observed which has a face-centered cubic structure. At room temperature the unit cell dimensions (a
0
) for the high-pressure face-centered cubic structures and approximate pressures at which they were determined are as follows: La, 5.17 Å (23 kb); Ce, 4.82 Å (15 kb); Pr, 4.88 Å (40 kb); and Nd, 4.80 Å (50 kb). The unit cell dimensions for the high-pressure forms of La, Pr, and Nd apparently have never been reported.
X-Ray-Induced Bulk Photovoltaic Effect in Insulators
Authors: Taimuty S. I. , Feinstein L. , Softky S. D.
Published: October 2006

When an insulator, sandwiched between metals of dissimilar work functions, is irradiated with x-radiation, a voltage related to the contact potential difference of the metals is observed. This phenomenon, known as the bulk photovoltaic effect, has been demonstrated in a variety of metal-insulator-metal combinations. Evidence that the voltage is not generated by junctions, barrier layers, or similar other phenomena is presented.
Amethyst: Optical Properties and Paramagnetic Resonance
Authors: Barry T. I. , Moore W. J.
Published: October 2006

Color centers in amethyst are produced by the action of ionizing radiation on precursor centers that arise from substitution of Fe
+3
for Si
+4
in the α-quartz structure. These Fe
+3
centers provide the dominant features of the electron paramagnetic resonance spectrum of amethyst. The three equivalent Si
+4
sites are unequally occupied by Fe
+3
, a circumstance that explains the optical biaxiality of amethyst.
Growth-Inhibiting Agents from
Mercenaria
Extracts: Chemical and Biological Properties
Authors: Schmeer M. Rosarii
Published: October 2006

Preliminary studies of the chemical nature of an antitumor agent from the common quahog,
Mercenaria mercenaria
, are reported. The agent has a regressive and an inhibiting effect on sarcoma 180 and on Krebs 2 carcinoma in Swiss albino mice.
DNA from Bacteriophage Lambda: Molecular Length and Conformation
Authors: MacHattie L. A. , Thomas C. A.
Published: October 2006

The length of the DNA molecules from wild-type λ bacteriophage is 17.2 μ, corresponding to a molecular weight of 33 million in the B form. The molecules from a double-deletion mutant of λ are 23 percent shorter. Both types of molecules join ends at 60°C to form circular molecules or polymers. The point of junction cannot be distinguished by any irregularity in the uniform duplex molecule.
Daily Rhythmicity of Corpus Allatum and Neurosecretory Cells in
Drosophila melanogaster
(Meig)
Authors: Rensing Ludger
Published: October 2006

Adult females of
Drosophila melanogaster
show a bimodal daily rhythmicity in the function of neurosecretory and corpus allatum cells. This result was obtained by measuring the size of the nuclei and determining the pattern of neurohormone secretion.
Infrared Study of Selective Deuteration of Kaolinite and Halloysite at Room Temperature
Authors: Ledoux Robert L. , White Joe L.
Published: October 2006

Deuteration of expanded hydrazine-kaolinite complex at room temperature shifts the infrared stretching frequencies of the inner-surface hydroxyls from 3695, 3670, and 3650 cm
-1
to 2725, 2710, and 2698 cm
-1
, respectively, and the inner hydroxyls absorbing at 3620 cm
-1
to 2675 cm
-1
. The OH-OD exchange for the inner-surface hydroxyls varies from 60 to 67 percent, whereas it is only 22 percent for the inner hydroxyls.
Viscosity and Self-Diffusion of Liquid Metals
Authors: Grosse Aristid V.
Published: October 2006

It is demonstrated that the empirical relationship between activation energy of viscosity and the melting point of a metal is also true for the energy of self-diffusion, in view of the Stokes-Einstein relation. The provision is that viscosity and self-diffusion be expressed in a self-consistent manner, as provided, for example, by the J. Frenkel's theory of liquids. Thus, one can now estimate either the viscosity or the self-diffusion of any metal over a substantial temperature range from its known melting point.
Persistence of
Neorickettsiae helminthoeca
in an Endoparasite of the Pacific Salmon
Authors: Farrell R. Keith , Lloyd Marilyn A. , Earp Brian
Published: October 2006

Silver salmon (
Oncorhynchus kisutch
) infected with the metacercariae of the "salmon poisoning" fluke (
Nanophyetus salmincola
) remain infected after they have migrated to sea. Metacercariae remain viable in such salmon for at least 33½ months. These metacercariae are capable of transmitting salmon disease (
Neorickettsiae helminthoeca
) to susceptible dogs throughout this period.
"Chromaffin" Cell: Electron Microscopic Identification in the Human Dermis
Authors: McGavran Malcolm H.
Published: October 2006

A granulated cell in human skin has an ultrastructure similar to that of chromaffin cells of the adrenal medulla. This cell is closely associated with unmyelinated axons and may be the site of peripheral store of noradrenaline.
Intracellular Regulatory Mechanisms
Authors: Umbarger H. E.
Published: October 2006

The study of metabolic regulation in microorganisms has revealed several simple but efficient regulatory circuits. In one, the operation of an entire sequence of enzymes is controlled by the activity of the initial enzyme which contains a specific inhibitor site. When this site is combined with the endproduct of the sequence, the catalytic site is rendered inactive. In another, the formation of an entire sequence of enzymes is controlled by means of a cytoplasmic mediator which blocks the transcription of the genetic message (repression) when activated by the endproduct, or which allows the transcription (induction) when activated by the substrate of the first enzyme in the sequence. Additional circuits have been proposed for the regulation of RNA and DNA synthesis. The same regulatory devices could account, in part, for intracellular metabolic control in more complex animal and plant forms. However, superimposed upon these simple control circuits will be found others which take advantage of the greater degree of organization in these cells and of the possibilities for regulating gene function that are provided by the chromosomes. The pattern of proteins with special control sites, such as have evolved in the relatively simple controls found in bacteria, may also be found essential for intercellular controls involving nervous and humoral mechanisms.
Xenon Hexafluoride: Preparation of Pure Form and Melting Point
Authors: Sheft Irving , Spittler Thomas M. , Martin Francis H.
Published: October 2006

Xenon hexafluoride forms an addition compound with sodium fluoride which can be used to separate it from the other xenon fluorides and oxyfluoride. The melting point of pure xenon hexafluoride prepared in this way was 47.7 ± 0.2°C.
Evidence from 12
S
Ribosomal RNA Sequences that Onychophorans Are Modified Arthropods
Authors: Ballard J. William O. , Olsen Gary J. , Faith Daniel P. , Odgers Wendy A. , Rowell David M. , Atkinson Peter W.
Published: October 2006

The evolutionary relationships of the onychophorans (velvet worms) and the monophyly of the arthropods have generated considerable debate. Cladistic analyses of 12
S
ribosomal RNA sequences indicate that arthropods are monophyletic and include the onychophorans. Maximum parsimony analyses and monophyly testing within arthropods indicate that myriapods (millipedes and centipedes) form a sister group to all other assemblages, whereas crustaceans (shrimps and lobsters) plus hexapods (insects and allied groups) form a well-supported monophyletic group. Parsimony analysis further suggests that onychophorans form a sister group to chelicerates (spiders and scorpions) and crustaceans plus hexapods, but this relationship is not well supported by monophyly testing. These relationships conflict with current hypotheses of evolutionary pathways within arthropods.
Enzymatic Dissection of the Mammalian Ovary
Authors: Grob Howard S.
Published: October 2006

Incubation of the ovaries of rats and mice with the proteolytic enzyme "pronase" caused the step by step dispersal of cellular elements from the tissue. The first subunits to be liberated were the outermost follicles or corpora lutea or both. Next, these subunits were dispersed. It is possible to obtain isolated single follicles in all stages of development: corpora lutea, isolated cell layers from within follicles, suspensions containing free cells, and ova in all phases of maturation.
Insecticide Sevin: Effect of Aerial Spraying on Drift of Stream Insects
Authors: Coutant Charles C.
Published: October 2006

There was a rise in the rate of drift of aquatic insects in a stream contained within an area of woodland sprayed with Sevin for control of the gypsy moth. It appears from the pattern of drift that there was a drastic reduction of the standing crop of stream insects as a result of the spraying.
High-Pressure Polymorphs in the Silver Iodide Phase Diagram
Authors: Davis Briant L. , Adams Leason H.
Published: October 2006

A good x-ray diffraction pattern has been obtained for the new phase of silver iodide stable in the vicinity of 3 kilobars at room temperature. A stability diagram of the six phases of silver iodide is presented to show the probable position of the narrow stability field of this phase. The x-ray diffraction data indicate that the cell symmetry of the new phase is probably orthorhombic.
Uricase: Localization in Hepatic Microbodies
Authors: Hruban Zdenek , Swift Hewson
Published: October 2006

Microbodies of rat hepatic cells and hepatomas contain a crystalloid with the same structural characteristics as crystals of purified uricase, when viewed by electron microscopy. We conclude that crystalline uricase is located within hepatic microbodies.
Cycloheximide: Aspects of Inhibition of Protein Synthesis in Mammalian Cells
Authors: Ennis H. L. , Lubin M.
Published: October 2006

Cycloheximide and acetoxycycloheximide specifically inhibit protein synthesis in L-cells growing in suspension culture. In extracts of rat liver, the drugs inhibit transfer of amino acid from soluble RNA to polypeptide. Unlike puromycin, these drugs do not accelerate release of nascent polypeptide chains. The drugs have no effect on protein synthesis in extracts of
Escherichia coli
.
Coxsackie A9 Virus: Mutation from Drug Dependence to Drug Independence
Authors: Eggers Hans J. , Tamm Igor
Published: October 2006

During the multiplication of Coxsackie A9 virus dependent on 2-(α-hydroxybenzyl)-benzimidazole there arise some drug-independent virus particles, which are either drug-resistant or drug-sensitive. We studied the properties of such revertant particles under conditions which did not favor the selection of resistant over sensitive virus particles. These particles exhibited a wide range of responses to 2-(α-hydroxybenzyl)-benzimidazole, from high sensitivity to high resistance. Subclones showed the same degree of sensitivity or resistance as the respective parent clones.
Cretaceous Mammals from Montana
Authors: Sloan Robert E. , Van Valen Leigh
Published: October 2006

A series of Cretaceous mammal faunas, beginning with standard late Cretaceous faunas and continuing with three of Paleocene aspect, are summarized. Four families (Eucosmodontidae, Taeniolabididae, Leptictidae, Arctocyonidae) and one order (Condylarthra) of Tertiary mammals are extended into the Cretaceous. New genera
Cimexomys
,
Stygimys
,
Procerberus
, and
Protungulatum
are described, as is a small species of
Catopsalis
. The skeleton of a multituberculate is restored and multituberculate classification is revised.
Radiocarbon Determinations for Estimating Groundwater Flow Velocities in Central Florida
Authors: Hanshaw Bruce B. , Back William , Rubin Meyer
Published: October 2006

Carbon-14 activity was determined from HCO
3
-
in samples of groundwater obtained from the principal artesian aquifer in Florida. From these data the "age" of water obtained from a series of wells, each progressively farther down gradient on the piezometric surface, was established. Relative carbon-14 ages indicated a velocity of groundwater movement of 23 feet (7 meters) per year for about 85 miles (137 kilometers) of travel. A velocity of 23 feet per year was calculated independently from Darcy's law.
Scenedesmus obliquus
Sexuality
Authors: Trainor Francis P. , Burg Carol Ann
Published: October 2006

The flagellated cells of two mixed strains of
Scenedesmus obliquus
can initiate a sexual cycle when grown at 15°C in a defined medium lacking a nitrogen source. Clumps of five to ten cells, paired gametes, plasmogamy, and quadriflagellated zygotes were observed.
Sulfur: A New High-Pressure Form
Authors: Bååk Tryggve
Published: October 2006

Under high pressures and elevated temperatures, rhombic sulfur is converted to a new cubic form; this form was quenched at room temperature and pressure and studied by x-ray diffraction. Phase boundaries for this new form have been established.
Activation Energy of Direct-Current Electrical Conductivity of Ice with HF and NH
3
Added
Authors: Chai S. Y. , Vogelhut P. O.
Published: October 2006

The activation energies of ice with varying amounts of impurities added were investigated with sintered platinum electrodes. For both types of impurities the activation energy was minimum at a concentration of 10
-4
M
. The experimental arrangement and possible reasons for the existence of a minimum in activation energy are discussed.
Pox Pottery: Earliest Identified Mexican Ceramic
Authors: Brush Charles F.
Published: October 2006

The earliest known ceramics from Mexico, termed "Pox Pottery," may mark the transition from a nomadic to a settled way of life. The presence of "Pox Pottery" in both coastal Guerrero and the Tehuacan Valley might provide evidence as to the type of environment in which this change first occurred.
Brain Catecholamines: Relation to the Defense Reaction Evoked by Amygdaloid Stimulation in Cat
Authors: Reis Donald J. , Gunne Lars-Magnus
Published: October 2006

Electrical stimulation of the amygdala of cats, evoking a defense reaction, was associated with a reduction in the noradrenalin content of the brain and adrenal glands but not in the dopamine content of the brain. When stimulation resulted in quieting or sleep, catecholamine concentrations were unaffected. Changes in brain noradrenalin, therefore, appear related to production of the defense response and not to nonspecific amygdalofugal pathway excitation.
Crystal and Molecular Structure of a Phospholipid Component: L-α-Glycerophosphorylcholine Cadmium Chloride Trihydrate
Authors: Sundaralingam M. , Jensen L. H.
Published: October 2006

The structure of L-α-glycerophosphorylcholine cadmium chloride trihydrate has been determined by the conventional, single-crystal, x-ray diffraction technique. The phospholipid component displays the characteristic
gauche
conformation for the choline residue and the
gauche
-
gauche
conformation for the glycerol moiety. Therefore, a possible model for the structures of phospholipids is similar to that proposed by Finean.
Callose: Lateral Movement of Assimilates from Phloem
Authors: Webster David B. , Currier Herbert H.
Published: October 2006

Brief heating of cotton petioles increased phloem callose and decreased lateral movement of assimilates containing carbon-14. The heat-induced phloem callose appears to have been responsible for part of this decrease; we conclude, therefore, that lateral movement from sieve tubes was along protoplasmic connections.
Fumarate Reductase in the Control of Heme Biosynthesis
Authors: Kurumada Takao , Labbe Robert F.
Published: October 2006

A drug-induced stimulation of heme biosynthesis in mouse liver was accompanied by altered fumarate metabolism. In liver homogenate, fumarate-1,4-C
14
was incorporated, via succinate and succinyl coenzyme A, into heme at an accelerated rate. This pathway of fumarate utilization was inhibited by acetoacetate but not by β-hydroxybutyrate. Fumarate reduction to succinate required reduced nicotinamide adenine dinucleotide. The enzyme fumarate reductase is suggested as a link between terminal oxidation and cellular control of the heme biosynthetic pathway.
Internally Perfused Axons: Effects of Two Different Anions on Ionic Conductance
Authors: Adelman W. J. , Dyro F. M. , Senft J. P.
Published: October 2006

Voltage-clamped giant axons of squid, internally perfused with potassium chloride solutions, showed reduced initial transient membrane conductance to voltage and increased overall (leakage) conductance. Unclamped axons showed reduced action and resting potentials. Ionic conductances and membrane potentials were maintained or restored by perfusion with potassium fluoride solutions. As much as 90 percent of internal fluoride could be replaced with chloride without alteration of normal properties of membrane.
Analysis of Complex Vascular Systems in Plants: Optical Shuttle Method
Authors: Zimmermann M. H. , Tomlinson P. B.
Published: October 2006

The "optical shuttle" is an improved method of photographing with a motion-picture camera, one by one, sequential sections mounted on separate slides. The optical output from two microscopes is combined so that the images can be focused on a single film plane. Slides are photographed alternately through the microscopes. Simultaneous viewing of two successive sections in the microscopes enables initial precise alignment of images. Complex anatomical structures can thus be analyzed with relative ease.
Electron Microscopy: Tight Junctions in Synapses of the Chick Ciliary Ganglion
Authors: de Lorenzo A. J. Darin
Published: October 2006

Examination of the synaptic membranes in calyciform endings of the chick ciliary ganglion has shown tight junctions selectively located on axon hillocks of postsynaptic neurons. Observations of similar membrane fusion in other junctions that involve electrotonic transmission suggest the possibility of identifying electrotonic junctions by electron microscopy.
Secretion into the Cerebrospinal Fluid by Caudal Neurosecretory Neurons
Authors: Fridberg Gunnar , Nishioka Richard S.
Published: October 2006

Neurons of the regenerating caudal neurosecretory system of
Tilapia mossambica
and of the normal system of
Albula vulpes
send processes into the central canal of the spinal cord. Evidence for appreciable release of secretion into the cerebrospinal fluid from these processes has been obtained with both light and electron microscopes.
Replication of the RNA of Bacteriophage f2
Authors: Lodish Harvey F. , Zinder Norton D.
Published: October 2006

Events occurring after infection of bacteria with wild-type and a temperature-sensitive mutant phage indicate that there are two enzymatic activities necessary to replicate phage RNA. One converts single strands into double strands, while the other uses double strands to synthesize viral RNA. The mutant is deficient in the first activity, probably because the mutation is in the gene specifying the requisite enzyme. On the basis of these and other results, a model is presented for the replication of phage RNA.
Piezoelectricity in Secondary Explosives
Authors: Maycock J. N. , Grabenstein D. E.
Published: October 2006

A theory for the formation of "hot spots" necessary for the initiation of an explosion is discussed in light of experimental evidence that most solid explosives are highly piezoelectric.
Classical Conditioning of Pain-Elicited Aggression
Authors: Vernon Walter , Ulrich Roger
Published: October 2006

Unconditioned aggression between paired animals in response to electric shock has been previously demonstrated. In this study, with the use of classical Pavlovian conditioning procedures, aggression was produced between paired rats as a response to a tone stimulus.
Sceloporus occidentalis
: Preferred Body Temperature of the Western Fence Lizard
Authors: McGinnis Samuel M.
Published: October 2006

Given equal thermal opportunities during four seasonal test periods, western fence lizards active above ground preferred constant body temperature throughout the year. Lizards recovered from subsurface retreats in the fall exhibited a mean body temperature significantly lower than that for sequestered lizards recorded during winter, spring, and summer.
Nonthrombogenic Plastic Surfaces
Authors: Leininger R. I. , Cooper C. W. , Epstein M. M. , Falb R. D. , Grode G. A.
Published: October 2006

Heparin has been chemically combined with a number of plastic surfaces rendering them nonthrombogenic as judged by Lee-White coagulation tests in vitro with human blood. Addition of quaternary ammonium groups to the plastic permitted formation of insoluble complexes with heparin. These heparinized surfaces were essentially nonthrombogenic and adsorb blood proteins to a significantly smaller degree from dilute solution than do the unmodified plastic surfaces. The affinity of the formed blood elements for these modified surfaces is much less than for the unmodified surfaces.
Heterosis: Complementation by Mitochondria
Authors: McDaniel Robert G. , Sarkissian Igor V.
Published: October 2006

Many (but not all) hybrids between two genetic pure lines show heterosis; that is the hybrids grow more rapidly or larger than the parental pure lines. The mechanism is not known. Two corn crosses were studied. In one hybrid known to exhibit heterosis, the mitochondria and an artificial 1:1 mixture of parent mitochondria showed heterosis with respect to oxidation and phosphorylation. In the other cross, neither the hybrid plant, its mitochondria, nor the mixture of parent mitochondria showed heterosis.
Crystallographic Structure of the Nitrogenase Iron Protein from
Azotobacter vinelandii
Authors: Georgiadis M. M. , Komiya H. , Chakrabarti P. , Woo D. , Kornuc J. J. , Rees D. C.
Published: October 2006

The nitrogenase enzyme system catalyzes the ATP (adenosine triphosphate)-dependent reduction of dinitrogen to ammonia during the process of nitrogen fixation. Nitrogenase consists of two proteins: the iron (Fe)-protein, which couples hydrolysis of ATP to electron transfer, and the molybdenum-iron (MoFe)-protein, which contains the dinitrogen binding site. In order to address the role of ATP in nitrogen fixation, the crystal structure of the nitrogenase Fe-protein from
Azotobacter vinelandii
has been determined at 2.9 angstrom (Å) resolution. Fe-protein is a dimer of two identical subunits that coordinate a single 4Fe:4S cluster. Each subunit folds as a single α/β type domain, which together symmetrically ligate the surface exposed 4Fe:4S cluster through two cysteines from each subunit. A single bound ADP (adenosine diphosphate) molecule is located in the interface region between the two subunits. Because the phosphate groups of this nucleotide are ∼20 Å from the 4Fe:4S cluster, it is unlikely that ATP hydrolysis and electron transfer are directly coupled. Instead, it appears that interactions between the nucleotide and cluster sites must be indirectly coupled by allosteric changes occurring at the subunit interface. The coupling between protein conformation and nucleotide hydrolysis in Fe-protein exhibits general similarities to the H-Ras p21 and recA proteins that have been recently characterized structurally. The Fe-protein structure may be relevant to the functioning of other biochemical energy-transducing systems containing two nucleotide-binding sites, including membrane transport proteins.
Laser as Light Source for Optical Diffractometers; Fourier Analysis of Electron Micrographs
Authors: Berger J. E. , Zobel C. Richard , Engler P. E.
Published: October 2006

Fourier analysis of electron micrographs has been accomplished under optimum conditions with a gas laser as the light source for an optical diffractometer.
Muscle Relaxation: Evidence for an Intrafibrillar Restoring Force in Vertebrate Striated Muscle
Authors: Parsons C. , Porter K. R.
Published: October 2006

Observations of contracting muscle fibrils in cultured cells indicate that the force which restores the resting length of the sarcomere comes from the contractile elements themselves and not from external elasticity, as is now generally accepted. In light of biochemical studies on the contraction-relaxation cycle, it is postulated that the elongating force is one of internal elasticity in the sarcomere, which arises during contraction from the distortion of bonds between filaments and/or structural proteins. This mechanism of restoration may serve to establish optimal sarcomere length for production of maximum contractile force, and in cardiac muscle this mechanism may be a factor in ventricular filling.
Subclasses of Human Immunoglobulin A Based on Differences in the Alpha Polypeptide Chains
Authors: Vaerman Jean-Pierre , Heremans Joseph F.
Published: October 2006

Antiserum from goats immunized with heavy polypeptide chains from a γA-type myeloma globulin was absorbed with serum from patients with selective absence of immunoglobulin A (γA). The resulting reagents could be used for the classification of 58 γA-myeloma proteins into two distinct antigenic types, respectively called subclasses He and Le. These differences were shown to be related to the heavy (alpha) polypeptide chains and independent of the integrity of interchain disulfide bridges. The γA-immunoglobulin from normal serum appears to consist, for the most part, of molecules with Le subclass specificity.
Binocular Disappearance of Monocular Symmetry
Authors: Julesz Bela
Published: October 2006

In an earlier demonstration binocular shapes were produced from monocularly shapeless, random-dot stereo images. A reversal of this phenomenon is demonstrated. A stereo image is devised in which the monocularly apparent shapes of bilateral symmetry disappear when stereoscopically viewed. This phenomenon sharpens the implications of the earlier one.
Tris Buffer Attenuates Acetylcholine Responses in
Aplysia
Neurons
Authors: Wilson Wilkie A. , Clark Margaret T. , Pellmar Terry C.
Published: October 2006

The commonly used buffering agent tris(hydroxymethyl)methylamine (tris) antagonizes the action of iontophoretically applied acetylcholine on neurons of
Aplysia californica
. Concentrations of 5 to 10 millimolar tris markedly reduced both excitatory and inhibitory responses.
Toxicity of Aquatic Herbicides to
Daphnia magna
Authors: Crosby D. G. , Tucker R. K.
Published: October 2006

Accurate determination of the acute toxicities of a series of 16 aquatic herbicides to
Daphnia magna
reveals that several of them may present a hazard to food-chain microfauna whether the compounds are environmentally destroyed or not.
Electron Paramagnetic Resonance of Methyl Radicals on Porous Glass Surface
Authors: Fujimoto M. , Gesser H. D. , Garbutt B. , Cohen A.
Published: October 2006

The photolysis of methyl iodide on a porous glass surface has been studied by electron paramagnetic resonance. A large number of methyl radicals can be stabilized over a wide range of temperature. The surface of porous Vycor glass is an excellent host for trapping free radicals.
Perceptual Grouping Produced by Changes in Orientation and Shape
Authors: Beck Jacob
Published: October 2006

The relative effectiveness of changes in orientation and shape in producing perceptual grouping has been studied using a method based on threshold judgments. Statistical analyses of the threshold values show that rotating some of the figures in a field from a vertical position to a slant of 45° facilitates segregating the field into separate perceptual groups. In contrast, changes in the shape or orientation of these figures, which leave their component lines vertical and horizontal, do not reliably aid grouping. The results also suggest that the similarity of the figures composing the field is not a good predictor of the degree to which the figures will cohere to form distinct perceptual groups.
Light-Induced Changes in Pineal Hydroxyindole-
O
-Methyltransferase: Abolition by Lateral Hypothalamic Lesions
Authors: Axelrod Julius , Snyder Solomon H. , Heller Alfred , Moore Robert Y.
Published: October 2006

The activity of hydroxyindole-
O
-methyltransferase, the melatoninforming enzyme in the pineal gland, is several times greater in rats kept in continuous darkness than in those kept in continuous light. Lesions transecting the medial forebrain bundle in the lateral hypothalamus suppress these differences in enzyme activity and abolish light-induced changes in pineal weight. These findings indicate that the medial forebrain bundle may participate in the control of this enzymatic response to environmental lighting.
Adrenalectomy and Coat Color in Deer Mice
Authors: Bronson F. H. , Clarke S. H.
Published: October 2006

Adrenalectomy in prairie deer mice is followed by a profound darkening of the fur which occurs within 1 to 3 months. The phenomenon is most noticeable on the normally unpigmented ventral surfaces which turn dark gray or black. A possible mechanism for such hyperpigmentation would involve increased release of melanocyte-stimulating hormones.
Pseudo-Fivefold Symmetry in Carbonyl Process Nickel
Authors: Downs Gene L. , Braun Japnell D.
Published: October 2006

Grains with pseudo-fivefold symmetry have been observed in nickel prepared by thermal decomposition of nickel carbonyl. These grains were studied by transmission electron microscopy and electron diffraction techniques. The defect structure and composite symmetry varied within a given sample, and the size of the grains varied with the thickness of the sample.
Galactic Depolarization of the 21-Centimeter-Wavelength Radiation of Extragalactic Sources
Authors: Bologna J. M. , McClain E. F. , Slonaker R. M.
Published: October 2006

The dependence of the degree of linear polarization of the radiation from 213 extragalactic sources on galactic coordinates was investigated at 21-centimeter wavelength. In addition to the previously known latitude effect, the depolarization of the radiation during transit through our galaxy is also a function of galactic longitude. One possible explanation is that galactic depolarization is a simple function of the distance traveled by the radiation through an extended galactic halo.
Vegetal Messenger RNA Localization Directed by a 340-nt RNA Sequence Element in
Xenopus
Oocytes
Authors: Mowry Kimberly L. , Melton Douglas A.
Published: October 2006

Contained within a single cell, the fertilized egg, is information that will ultimately specify the entire organism. During early embryonic cleavages, cells acquire distinct fates and their differences in developmental potential might be explained by localization of informational molecules in the egg. The mechanisms by which Vg1 RNA, a maternal mRNA, is translocated to the vegetal pole of
Xenopus
oocytes may indicate how developmental signals are localized. Data presented here show that a 340-nucleotide localization signal present in the 3′ untranslated region of Vg1 RNA is sufficient to direct RNA localization to the vegetal pole.
Cyclic 2′,3′-Phosphates and Nontemplated Nucleotides at the 3′ End of Spliceosomal U6 Small Nuclear RNA's
Authors: Lund Elsebet , Dahlberg James E.
Published: October 2006

Spliceosomal U6 small nuclear RNA (U6 RNA) in species as diverse as man, frog, fruitfly, and soybean have at their 3′ ends a cyclic 2′,3′-phosphate (>p) apparently derived from uridylic acid residues that were added post-transcriptionally. The 3′ ends of U6 RNA's from various sources may be processed in different ways, or to different extents, depending on the organism or stage of development. The presence of a >p terminus on U6 RNA may influence the activity of U6 RNA either directly during splicing or indirectly by ensuring that the RNA has a defined length or proper conformation (or both).
Ethical Issues in Research with Human Subjects
Authors: Wolfensberger Wolf
Published: October 2006

It is obvious that many disciplines confront ethical problems in research in which situational details may vary, but in which the same ethical principles may prevail. I write not in order to propose a definitive set of rules but to demonstrate how situations posing ethical problems can be reduced and more readily resolved by rational analysis of underlying issues and principles; I hope to stimulate further analysis and dialogue. It might be particularly helpful if researchers in a wide range of disciplines contributed experiences permitting a sharpening of guidelines. Finally, it is conceivable that a code of ethics might eventually be promulgated by a supradisciplinary body such as the AAAS, and that such a code could then be adapted and adopted by other scientific bodies and professional organizations—even by specific agencies such as research institutes, clinics, institutions, and schools.
Visual Adaptation to Gradual Change of Intensity
Authors: Anstis S. M.
Published: October 2006

The eye can adapt to the rate of change of brightness. After exposure of the eye to a light that grows gradually brighter, a steady light appears to grow gradually dimmer, and vice versa. A field containing shading gives larger aftereffects than a spatially uniform field.
Depression in Infant Monkeys Separated from Their Mothers
Authors: Kaufman I. Charles , Rosenblum Leonard A.
Published: October 2006

The mothers of four pigtail (
Macaca nemestrina
) infants living in a group were removed for 4 weeks. All infants reacted initially with agitation. Three of the four infants then became severely depressed. The depression lasted about a week and was strikingly similar to the "anaclitic depression" of human infants who lost their mothers. When they were reunited, all four dyads showed a marked and prolonged intensification of the mother-infant relationship.
Hexagonal Diamonds in Meteorites: Implications
Authors: Hanneman R. E. , Strong H. M. , Bundy F. P.
Published: October 2006

A new polymorph of carbon, hexagonal diamond, has been discovered in the Canyon Diablo and Goalpara meteorites. This phase had been synthesized recently under specific high-pressure conditions in the laboratory. Our results provide strong evidence that diamonds found in these meteorites were produced by intense shock pressures acting on crystalline graphite inclusions present within the meteorite before impact, rather than by disintegration of larger, statically grown diamonds, as some theories propose.
Metabolic Aspects of Acid-Base Change
Authors: Lotspeich William D.
Published: October 2006

The state of metabolic acidosis involves changes of a varied and subtle nature in other organs as well as in the kidney. This fact has been illustrated in metabolic studies with glutamine, a major substrate of the kidney and of various other organs.

In addition to the well-described increase in renal glutaminase enzymes, the hexose monophosphate-shunt enzymes also are much more active during metabolic acidosis; this phenomenon is limited to the kidney; its exact meaning remains speculative, but its possible relation to renal excretion of acid, lipogenesis, and gluconeogenesis during acidosis has been discussed.

In the kidney there are metabolic changes associated with ammonium chloride acidosis that affect the basic mechanisms of gene-directed growth. There is a renal regenerative process during this kind of acidosis that resembles in some respects the compensatory hypertrophy in the remaining kidney after unilateral nephrectomy, from which it also differs in important ways. Lastly, we must now regard the role of glutamine in renal metabolism as an affair that goes well beyond the specific needs of formation of ammonia during the normal and acidotic states. Glutamine enters the general metabolic mill of the kidney, its carbon skeleton is incorporated into all the major tissue components, and it is an important source material for gluconeogenesis in the kidney; all of these renal functions of glutamine are increased during metabolic acidosis.

Thus there is a fruitful field of exploration ahead, not only in the biochemical aspects of the renal response, but also in the metabolic interrelations among different organs during various types of acid-base change. This article, in concentrating on metabolic acidosis, gives only a glimpse of a broader picture to come.
Heterologous Antilymphocyte Globulin: Studies in vitro
Authors: Humphrey Loren J. , Kauffman H. Myron , Dunn Ellis
Published: October 2006

Incubation of dog-lymphocyte cultures with globulin from antiserum to lymphocytes resulted in a greater percentage of transformed cells than incubation with phytohemagglutinin. Viability counts demonstrated that this globulin and phytohemagglutinin had approximately equal degrees of cytotoxicity.
Evoked Potentials: Three-Dimensional Display
Authors: Burns Stephen K. , Borbély Alexander A. , Hall Robert D.
Published: October 2006

Procedures are described for displaying large numbers of evoked potentials. A photographic superposition of average evoked responses, with the concurrent modulation of the brightness of each trace, yields a display having the appearance of a three-dimensional surface formed from hundreds of average responses.
Transformation of Gibbsite to Chlorite in Ocean Bottom Sediments
Authors: Swindale L. D. , Fan Pow-Foong
Published: October 2006

Numerous grains of gibbsite surrounded by zones of chlorite were found in six samples of sediment taken from Waimea Bay off the coast of Kauai, Hawaii. The chlorite has formed from the gibbsite, and growth bands in the chlorite either are parallel to chlorite-gibbsite interfaces or are concentric around small remnants of gibbsite. Aggregates were found that appeared to be composed of two or more gibbsite grains surrounded by chlorite bands that have grown together. The index of refraction of the chlorite ranged from 1.58 to 1.60 and the chlorite displayed anomalous blue interference colors. The gibbsite was formed on land under conditions of strong weathering and strong leaching. When transported to the sea, the gibbsite was deposited in a solution containing silicic acid, magnesium, potassium, and hydrogen ions, in which it is unstable. Chlorite, a stable mineral in this solution, replaced the gibbsite.
Phenotypic Masking and Streptomycin Dependence
Authors: Gorini Luigi , Rosset Roland , Zimmermann Robert A.
Published: October 2006

In attempting to define the role of ribosomes in the mechanism of streptomycin dependence, a new phenomenon has been discovered. Analysis of this phenomenon—called phenotypic masking—leads to the conclusion that "streptomycin dependent" mutants are actually "drug dependent" because their dependence is equally satisfied by several drugs. These drugs, some of which are totally unrelated chemically, act on the ribosome and induce misreading in vitro and suppression in vivo.
Characteristics of Hurricanes
Authors: Miller Banner I.
Published: October 2006

Tropical cyclones derive their energy from the release of latent heat of condensation; they have been compared to simple heat engines, although they are not very efficient ones since only about 3 percent or less of the heat released within the cyclone is converted into kinetic energy. Tropical cyclones are warm-core, direct circulations in the sense that ascent takes place at warmer temperatures than does descent, thus converting heat energy into potential energy and potential energy to kinetic energy.
Enhancement of Flicker by Lateral Inhibition
Authors: Ratliff Floyd , Knight B. W. , Toyoda Jun-ichi , Hartline H. K.
Published: October 2006

Sinusoidal modulation of illumination on the compound eye of the horseshoe crab,
Limulus
, produces a corresponding variation in the rate of discharge of optic nerve impulses. Increasing the area of illumination decreases the variation at low frequencies of modulation, but unexpectedly enhances—or "amplifies"—the variation at the intermediate frequencies to which the eye is most sensitive. Both effects must result from inhibition since it is the only significant lateral influence in this eye.
Slow Virus Kidney Disease of Mice
Authors: Baker Frederick D. , Hotchin John
Published: October 2006

Preliminary observations based on organ weight differential, renal function, and glomerular lesions in mice infected neonatally with lymphocytic choriomeningitis indicate the presence of a slow virus-induced kidney disease of mice. This condition is accompanied by a marked decrease in the size of the kidneys, with progressive diminution of renal function, as shown by measurements of creatinine and urea clearance.
"C"-Type Viral Particles in Plasma of Cats with Feline Leukemia
Authors: Kawakami Thomas G. , Theilen Gordon H. , Dungworth Donald L. , Munn Robert J. , Beall Sharon G.
Published: October 2006

Linear sucrose-density gradient was used to detect and isolate typical "C"-type viral particles in plasma of cats with spontaneous and experimentally induced leukemia. The density of the agent is similar to known murine leukemia virus (1.15 to 1.17 grams per cubic centimeter). In the electron microscope the virus showed typical "C"-type particle morphology with various maturation stages. The maximum diameter of the mature viral particles in plasma was 115 millimicrons, a diameter slightly larger than budding particles observed in tissue. Leukemia was transmitted with cellular and cell-free inoculum after a 5-week period of latency.
Allergic Adenohypophysitis: New Experimental Disease of the Pituitary Gland
Authors: Levine Seymour
Published: October 2006

The pituitary gland has been added to the roster of organs in which inflammatory disease, probably autoimmune in origin, can be induced by injection of the corresponding tissue plus adjuvants.
Lymphocytic Choriomeningitis: Production of Antibody by "Tolerant" Infected Mice
Authors: Oldstone Michael B. A. , Dixon Frank J.
Published: October 2006

Newborn mice infected with lymphocytic choriomeningitis virus are not immunologically tolerant to the agent but, rather, appear to make antibody to the virus. This antibody was detectable only in the kidneys, where presumably it had been deposited in the glomeruli in the form of complexes of antibody, virus, and complement.
Defensive Use of a "Fecal Shield" by a Beetle Larva
Authors: Eisner Thomas , van Tassell Eileen , Carrel James E.
Published: October 2006

The larva of
Cassida rubiginosa
carries a tight packet of cast skins and feces on a fork held over its back. The packet is a maneuverable shield used by the larva to protect itself against attack. It is highly effective in blocking the bite of ants.
Control of Aldosterone Secretion by the Pituitary Gland
Authors: Palmore William P. , Mulrow Patrick J.
Published: October 2006

In the rat, the pituitary gland is essential for the stimulation of aldosterone secretion by sodium depletion. Hypophysectomy abolishes the response to sodium depletion, whereas whole pituitary gland injections partially restore it. The response cannot be restored by injections of either adrenocorticotropin or growth hormone, nor by adrenocorticotropin plus thyroxin. The pituitary gland must secrete a hormone or possibly several hormones which are necessary for the adrenal gland to respond to sodium depletion.
Electronic Properties of Amorphous Materials
Authors: Tauc Jan
Published: October 2006

A possible approach to the understanding of electronic properties of amorphous materials is to compare them with the corresponding crystalline materials, whose properties have been well explained. This approach has been exploited in the simple case of amorphous germanium, and I have indicated how the observed optical properties can be used to obtain information on the changes of electronic states, and what complications arise when we try to understand the transport properties.
Dense-Gas Chromatography of Nonvolatile Substances of High Molecular Weight
Authors: McLaren Lilian , Myers Marcus N. , Giddings J. Calvin
Published: October 2006

Working at pressures of up to 2000 atmospheres, more than ten times higher than in previous gas chromatography, we used the solvent power of dense gases to enable migration of chromatographic substances of molecular weights as high as 400,000. Carotenoids, corticol steroids, sterols, nucleosides, amino acids, carbohydrates, and several polymers have been caused to migrate, separated, and detected in NH
3
and CO
2
carrier gases at temperatures of 140° and 40°C, just above the respective critical points. Previously such compounds either defied separation by gas chromatography or had to be chromatographed as their more volatile derivatives.
Cabbage Aphid: Effect of Isolation on Form and on Endocrine Activity
Authors: White Dinah F.
Published: October 2006

Isolated wingless cabbage aphids,
Brevicoryne brassicae
(L.), produced only wingless young. Aphids isolated from birth all became wingless, whereas over 50 percent of grouped controls developed wings. Isolation caused hyperactivity of the corpus allatum; this hyperactivity may have caused the wingless form.
Morphogenetic Interaction of Presumptive Neural and Mesodermal Cells Mixed in Different Ratios
Authors: Toivonen Sulo , Saxén Lauri
Published: October 2006

Cells of the presumptive forebrain region and axial mesoderm of
Triturus
neurulae were disaggregated and combined in different ratios. The differentiation of the central nervous system in these explants was dependent on the relative amount of mesodermal cells present: an increase of mesodermal cells resulted in a corresponding increase in the frequency with which caudal structures of the central nervous system developed and a gradual loss of the forebrain formations.
Incidence of Gross Chromosomal Errors among Tall Criminal American Males
Authors: Telfer Mary A. , Baker David , Clark Gerald R. , Richardson Claude E.
Published: October 2006

Chromosome studies on 129 tall men surveyed in four different institutions for the care of criminal males in Pennsylvania showed that 1 in 11 subjects displayed aneuploidy of the sex chromosomes; specifically, five cases of 47,XYY and seven cases of Klinefelter syndrome were identified. All the aneuploid subjects were mentally ill; none had been cytogenetically diagnosed.
Lactate Dehydrogenase Isozymes in Parthenogenetic Teiid Lizards (
Cnemidophorus
)
Authors: Neaves William B. , Gerald Park S.
Published: October 2006

Heterozygosity occurs at the lactate dehydrogenase b-locus in two diploid parthenogenetic species of
Cnemidophorus
. Each such species produces two different B subunits, one of which is also found in two sexual species and in two triploid parthenogenetic species; the other occurs also in a third sexual species. Interspecific hybridization between sexual species carrying different b-alleles and producing different B subunits may be responsible for the heterozygosity at the lactate dehydrogenase b-locus in diploid parthenogenetic
Cnemidophorus
.
Photodimer of Thymine in Ultraviolet-Irradiated DNA: Proof of Structure by X-ray Diffraction
Authors: Camerman Norman , Camerman Arthur
Published: October 2006

Dimethylthymine was photodimerized with ultraviolet radiation, and the structure of one of the resulting dimers, the
cis
5,5 : 6,6 isomer, was determined by single-crystal x-ray diffraction. This isomer is the same as that obtained by ultraviolet irradiation of DNA; hence the structure of the thymine dimer in irradiated DNA is now proved.
Cytomembrane Differentiation in the Endoplasmic Reticulum-Golgi Apparatus-Vesicle Complex
Authors: Grove S. N. , Bracker C. E. , Morré D. J.
Published: October 2006

Diversity of cytomembrane types is confirmed in hyphae of the fungus
Pythium ultimum
by electron microscopy. A transition in membrane morphology across stacks of dictyosome cisternae (from endoplasmic reticulumlike at one pole to plasma membrane-like at the opposite pole) suggests that dictyosomes of the Golgi apparatus are sites of membrane interconversion.
Shell Use: An Adaptation for Emigration from the Sea by the Coconut Crab
Authors: Reese Ernst S.
Published: October 2006

The coconut crab
Birgus latro
(L.) emigrates from the sea during the postlarval glaucothoe stage. Glaucothoes show ancestral hermit crab behavior of living in empty gastropod shells which protect them during this vulnerable time.