Search Results - (Author, Cooperation:T. A. Miller)

2018-06-08

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Immunobiology and Immunotherapy, Transplantation, Plenary Papers, Clinical Trials and Observations

2011-07-09

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2012-03-09

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2018-11-02

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Materials Science, Physics

1077-3118

AIP Digital Archive

Physics

A highly strain tolerant family of conductors has been developed for the high-temperature superconductor Bi2Sr2Ca1Cu2O8−δ by fabricating a microfilamentary composite in which discontinuous filaments of the superconductors are separated from one another by very thin layers of Ag. The Ag provides a region of plastic flow and the strain tolerance. The Ag also provides barriers to supercurrent flow and to overcome these barriers, long slender filaments of Bi(2212) are arranged to have enormous overlap areas perpendicular to the direction of average current flow. This requires filament length to diameter ratios of about 10 000 to 1 and Ag barrier thicknesses on the order of 20 nm. This permits high Jc values even though the sample has a dense array of barriers. At 4.2 K and 0.3 T, critical current densities typically fall smoothly from 1000 to 800 A/cm2 as the strain increases from 0 to 1.6%.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The conversion of long slender filaments of Bi-based high-temperature superconductors from the amorphous to the crystalline phase has been studied in order to determine the suitability of these fibers for use in a multifilamentary magnet conductor. For very fine filaments, coarsening may be a problem, so special emphasis was placed on the optimum values of time and temperature used for recrystallization. Amorphous fibers approximately 1 μm in diameter can be crystallized to form granular filaments about 0.2 μm thick (in the c direction) and 3 to 4 μm wide. The c axis generally grows perpendicular to the long axis of the fiber.

Electronic Resource

1551-2916

Blackwell Publishing Journal Backfiles 1879-2005

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Nanocrystalline SnOx particles (x= 0–2) were synthesized using tetramethyltin (Sn(CH3)4) vapor as the particle precursor reactant in hydrogen/oxygen/argon (H2/O2/Ar) flames. The particle composition and morphology were characterized using X-ray diffractometry, transmission electron microscopy, and nitrogen (N2) surface adsorption. By controlling the concentration of oxygen in the reactant gases and the flame temperatures, metallic tin (Sn), tin monoxide (romarchite SnO), and/or tin dioxide (cassiterite SnO2) were generated. The crystalline powders consisted of both discrete primary particles and agglomerates, with average primary particle sizes of 23–24 nm for SnO2 and 69 nm for Sn (based on specific surface area measurements of bulk powders collected in the exhaust region of the flame). The compositional results were interpreted using equilibrium and detailed chemical kinetics models.

Electronic Resource

1436-5065

Springer Online Journal Archives 1860-2000

Geography

Physics

Summary An analysis of data pertaining to the period 1861–1986 reveals that (1) a 1 °C rise in the mean annual air temperature of the British Isles has historically been associated with a 35% drop in the percentage of days that the United Kingdom has experienced cyclonic flow, and (2) a 2 °C increase in the mean annual air temperature over the sea to the north has typically been matched by a 60% drop in the percentage of days that the isles have experienced cyclonic flow originating from that source region. These findings raise significant questions about the oft-reported claim that CO2-induced global warming will lead to an increase in world storminess.

Electronic Resource

1420-9071

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary Proctolin at concentrations 10−8–10−7 M elevated by 40% brain adenylate cyclase activity of adultLocusta migratoria migratorioides R.F. In moulting individuals, proctolin caused a decrease in brain adenylate cyclase activity, and it proved to be ineffective in the larvae. Proctolin caused only a slight decrease on guanylate cyclase activity of the brain at every developmental stage.

Electronic Resource

1420-9071

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary Octopamine and proctolin at concentrations below 10−8 M reversibly induce a spontaneous rhythmic depolarization which occurs in body-wall muscles ofLucilia larvae. The effect appears to be postsynaptic and mediated by receptors specific for each substance.

Electronic Resource

1420-9071

Pectinophora gossypiella ; pink bollworm moth ; insecticide resistance ; pheromones ; sticky traps ; permethrin ; fenvalerate

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary A novel pheromone-baited sticky trap laced with insecticides proved to be a simple and effective means of monitoring insecticide resistance in the pink bollworm moth. Adult males from fields treated frequently with pyrethroid insecticides showed up to 20-fold resistance to permethrin and up to 14.5-fold resistance to fenvalerate.

Electronic Resource

1432-1351

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary 1. The reversal potential of the fast and slow excitatory postsynaptic potential (EPSP) of longitudinal body wall muscles 6A and 7A ofMusca domestica larvae were studied in various saline solutions. 2. The reversal potentials of both fast and slow EPSPs are made more negative by decreasing the sodium ion concentration and made more positive by increasing the potassium ion concentration. The reversal potential of the slow EPSP becomes more negative with increasing bicarbonate ion concentration, whereas the reversal potential of the fast EPSP is unaffected by changes in bicarbonate ions. 3. If both axons are stimulated to give a composite response, the slight difference in the reversal potentials of the fast and slow EPSPs gives a biphasic wave form at membrane potentials near reversal. The size of this biphasic wave increases with increasing bicarbonate ion concentration. 4. Analysis of the haemolymph ofMusca larvae revealed a bicarbonate ion concentration of 10.32 mM (S.D.±1.3) and a pH of 7.1 (S.D.±0.05). 5. It is concluded that fast and slow responses use different ionic channels. It is tentatively suggested that bicarbonate ions affect the reversal potential of the slow EPSP by increasing the intracellular potassium concentration. The fast and slow EPSP may therefore utilise channels whose conductances are differentially sensitive to intracellular potassium concentration.

Electronic Resource

1432-1351

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary 1. Body wall muscles 6A and 7A ofMusca larvae are each dually innervated by a single fast and a single slow axon. Perfusion of 1 mM E-glutamate abolished the neurally evoked fast EPSP but not the slow EPSP, while 1 mM aspartate abolished the slow EPSP but not the fast EPSP. 2. Iontophoresis of L-glutamate or aspartate from single or multibarreled micropipettes produced potentials when ejected at localised sites on the muscle surface. These sites were identified as synaptic terminals by recording extracellular synaptic currents and the ability to evoke antidromic nerve impulses and EPSPs upon focal stimulation. 3. The site of action of iontophoretically applied E-glutamate corresponded to the fast neuromuscular junction, while that of aspartate corresponded to the slow neuromuscular junction. The conduction velocity of antidromic impulses evoked by focal stimulation was lower in slow axons than in fast axons. Sensitive sites could therefore be unequivocally identified as fast or slow synapses. 4. The two types of receptor (glutamate-preferring and aspartate-preferring) were agonist specific, although each agonist would act as an antagonist of the other receptor type. 5. The ionic fluxes of the fast EPSP were the same as for L-glutamate potentials, and the ionic fluxes of the slow EPSP were the same as for aspartate potentials. In conditions where comparisons were possible, there was no significant difference between the reversal potentials of iontophoretically applied L-glutamate and the neurally evoked fast EPSP. Similarly, there was no significant difference between iontophoretically applied aspartate and the neurally evoked slow EPSP. The reversal potentials of iontophoretically applied L-glutamate and aspartate were significantly different. 6. When axonal conduction was blocked with tetrodotoxin (TTX), graded focal stimulation of nerve terminals produced graded postsynaptic potentials. At identified fast terminals, the evoked graded potentials were similar in time course to iontophoretically applied L-glutamate potentials while at slow terminals, evoked potentials were similar to aspartate potentials. 7. When blunt iontophoretic micropipettes were positioned over fast synapses in the presence of TTX, the postsynaptic membrane became desensitised to both ejected L-glutamate and the natural transmitter. Dose-response curves of iontophoretically applied L-glutamate in the presence of the natural transmitter at the same terminal region indicated competitive interaction between L-glutamate and the natural transmitter. 8. Iontophoretic potentials could not be obtained in the presence of either 6 mM calcium or 20 mM magnesium, although large EPSPs could be recorded under these conditions. Iontophoretic potentials could be evoked in these conditions if 10 mM bicarbonate ions were present. 9. It is concluded the L-glutamate is a specific agonist at the fast transmitter receptor, while aspartate is a specific agonist at the slow transmitter receptor. However, in view of the different effects of calcium on the neurally evoked potential and the iontophoretic potentials, a better understanding of these synapses is needed before claiming a transmitter role for these amino acids.

Electronic Resource

1432-0878

Locust ; Insect visceral muscle ; Alary muscle ; Dorsal diaphragm Innervation ; Neuromuscular junction

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary The alary muscles of Locusta migratoria adults make up the major tissue of the dorsal diaphragm which separates pericardial and perivisceral sinuses in the abdomen. The alary muscles are striated with a sarcomere at rest measuring about 9 μm. The Z-line has a staggered-beaded arrangement with A-bands and I-bands readily discernable. Thick myofilaments are surrounded by 10 or more thin filaments. The sarcoplasm has few mitochondria near the area of the Z-line, dyads are present and sarcoplasmic reticulum is poorly developed. Axons which innervate the alary muscle are either contained within invaginated folds of the sarcolemma of the muscle cells or the muscle cells send finger-like projections to envelop the axons. The synaptic terminals contain synaptic vesicles between 40 and 45 nm in diameter and a few electron-dense granules near or less than 170 nm in diameter. Away from synaptic terminals the axon profiles show few or no granules. The axons are accompanied everywhere by well-developed glial cells. This then is not typical neurosecretomotor innervation, however, the presence of electron-dense granules suggests the possibility of peptidergic neurotransmission.

Electronic Resource

1573-2568

CYTOPROTECTION ; DIMETHYL-PROSTAGLANDIN E2 ; PROTEIN KINASE C ; CALCIUM EFFLUX ; MICROTUBULES ; Caco-2 CELLS

Springer Online Journal Archives 1860-2000

Medicine

Abstract Prostaglandins (PG) protect gastrointestinalcells against damage induced by ethanol (EtOH) and othernoxious agents, a process termed cytoprotection. Thepresent study investigated the relationships between microtubule (MT) stability, protein kinase C(PKC) activation, and calcium efflux as a possiblemechanism of PG's protective action using a humancolonic cell line (Caco-2) exposed to known damagingconcentrations of EtOH (7.5% and 10% ). Preincubation ofCaco-2 cells with 16,16-dimethyl-PGE2 (PG,2.6 μM) significantly increased PKC activity in thesecells. Pretreatment of Caco-2 cells with 50 μM OAG (asynthetic diacylglycerol and PKC activator) or 30 nM TPA(a direct PKC activator) prior to exposure to 7.5% or10% EtOH for 5 min significantly reduced cell injury, asdetermined by trypan blue exclusion, and increased MT stability, as confirmed by confocalmicroscopy. Pretreatment of Caco-2 cells with 4alpha-PDD (an inactive phorbol ester, 20 nM) failed toprevent cell injury and disruption of the MTcytoskeleton. Preincubation with staurosporine (a PKC inhibitor, 3 nM)abolished the protective effects of PG in cells exposedto 7.5% and 10% EtOH. Incubation of Caco-2 cells withA23187 (a Ca2+ ionophore), similar to 10%EtOH, caused a significant reduction in cell viability andMT stability. Preincubation with A23187 in combinationwith PG or OAG prior to subsequent exposure to EtOHsignificantly abolished the protective effects of PG or OAG pretreatment. Finally, pretreatmentwith OAG, TPA, or PG resulted in significant increasesin calcium-45 efflux, which correlated with increasedstability of the MT cytoskeleton. These data suggest that PG possesses direct protective effectsagainst EtOH injury in Caco-2 cells and may act bystabilizing MT through the PKC signal transductionpathway and/or stimulation of calcium efflux from thecells.

Electronic Resource

1572-9605

Superconductivity ; environmental contamination ; amorphous ; YBa2Cu3O7-δ

Springer Online Journal Archives 1860-2000

Electrical Engineering, Measurement and Control Technology

Physics

Abstract A study of the environmental contamination of amorphous YBa2Cu3O7-δ fibers has been undertaken in order to determine the best method to handle these materials during the fabrication of superconducting wire. The fibers often need to be handled in organic solvents as part of the cleaning and manipulating process. In organics that are free of water, the fibers retain their mechanical strength with little carbon contamination or other ill effects. Water, however, causes premature crystallization and destroys the mechanical strength of the fibers.

Electronic Resource

0739-4462

permethrin ; deltamethrin ; giant axon ; escape behavior ; flight muscle ; Musca domestica ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry

Wiley InterScience Backfile Collection 1832-2000

Biology

Recovery from pyrethroid poisoning was studied in groups of adult female houseflies treated with LD50 doses of trans-permethrin or deltamethrin. The first overt sign of recovery was the appearance of normal posture, which was followed by jumping behavior and finally, coordinated flight when the flies had fully recovered. Prior to full recovery, treated houseflies were able to maintain normal posture and usually jump, but they could not fly. When tethered, these flightless houseflies responded to loss of tarsal contact by initiating normal patterned activity in the dorsolongitudinal flight muscles, yet the wings did not move. In flightless flies displaying jumping behavior, electrical stimulation of the brain evoked responses in the pleurosternal muscle, which controls thoracic tension during flight. Thus, many of the motor systems responsible for flight behavior seemed to be functional in flightless flies. Carbofuran, a carbamate anticholinesterase known to initiate spontaneous flight behavior from within the central nervous system, failed to elicit this response in flightless flies. These results suggested that the flightless condition was due to a disruption in central nervous pathways, and not to peripheral neuromuscular block. The pattern of recovery of different behaviors analyzed in this study was found to be consistent with the Jacksonian Hierarchy Principle, and the utility of this principle in guiding the design of new behavior-modifying compounds is discussed.

5 Ill.

Electronic Resource