10,771 research outputs found

    Antenna Impedance in a Warm Plasma

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    Impedance of biconical and cylindrical dipoles in warm isotropic plasm

    Arkansas Soybean Performance Tests 2018

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    Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

    Quantum discord in spin-cluster materials

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    The total quantum correlation (discord) in Heisenberg dimers is expressed via the spin-spin correlation function, internal energy, specific heat or magnetic susceptibility. This allows one to indirectly measure the discord through neutron scattering, as well as calorimetric or magnetometric experiments. Using the available experimental data, we found the discord for a number of binuclear Heisenberg substances with both antiferro- and ferromagnetic interactions. For the dimerized antiferromagnet copper nitrate Cu(NO_3)_2*2.5H_2O, the three independent experimental methods named above lead to a discord of approximately 0.2-0.3 bit/dimer at a temperature of 4 K. We also determined the temperature behavior of discord for hydrated and anhydrous copper acetates, as well as for the ferromagnetic binuclear copper acetate complex [Cu_2L(OAc)]*6H_2O, where L is a ligand.Comment: 7 pages, 6 figure

    The fabrication of biodegradable nanospheres from novel hydroxalkanoates for the delivery of actives of pharmaceutical and agricultural interest

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    This work describes the fabrication of nanospheres from a range of novel polyhydroxyalkanoates supplied by Monsanto, St Louis, Missouri, USA for the delivery of selected actives of both pharmaceutical and agricultural interest. Initial evaluation of established microsphere and nanosphere fabrication techniques resulted in the adoption and optimisation of a double sonication solvent evaporation method involving the synperonic surfactant F68. Nanospheres could be consistently generated with this method. Studies on the incorporation and release of the surrogate protein Bovine Serum Albumin V demonstrated that BSA could be loaded with between 10-40% w/w BSA without nanosphere destabilisation. BSA release from nanospheres into Hanks Balanced Salts Solution, pH 7.4, could be monitored for up to 28 days at 37°C. The incorporation and release of the Monsanto actives - the insecticide Admire® ({ 1-[(6-chloro-3-pyridinyl)methyIJ-N-nitro-2-imidazolidinimine}) and the plant growth hormone potassium salt Gibberellic acid (GA3K) from physico-chemically characterised polymer nanospheres was monitored for up to 37 days and 28 days respectively, at both 4°C and 23°C. Release data was subsequently fitted to established kinetic models to elaborate the possible mechanisms of release of actives from the nanospheres. The exposure of unloaded nanospheres to a range of physiological media and rural rainwater has been used to investigate the role polymer biodegradation by enzymatic and chemical means might play in the in vivo release of actives and agricultural applications. The potential environmental biodegradation of Monsanto polymers has been investigated using a composting study (International Standard ISO/FDIS 14855) in which the ultimate aerobic biodegradation of the polymers has been monitored by the analysis of evolved carbon dioxide. These studies demonstrated the potential of the polymers for use in the environment, for example as a pesticide delivery system

    Kinematics in Kapteyn's Selected Area 76: Orbital Motions Within the Highly Substructured Anticenter Stream

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    We have measured the mean three-dimensional kinematics of stars in Kapteyn's Selected Area (SA) 76 (l=209.3, b=26.4 degrees) that were selected to be Anticenter Stream (ACS) members on the basis of their radial velocities, proper motions, and location in the color-magnitude diagram. From a total of 31 stars ascertained to be ACS members primarily from its main sequence turnoff, a mean ACS radial velocity (derived from spectra obtained with the Hydra multi-object spectrograph on the WIYN 3.5m telescope) of V_helio = 97.0 +/- 2.8 km/s was determined, with an intrinsic velocity dispersion sigma_0 = 12.8 \pm 2.1 km/s. The mean absolute proper motions of these 31 ACS members are mu_alpha cos (delta) = -1.20 +/- 0.34 mas/yr and mu_delta = -0.78 \pm 0.36 mas/yr. At a distance to the ACS of 10 \pm 3 kpc, these measured kinematical quantities produce an orbit that deviates by ~30 degrees from the well-defined swath of stellar overdensity constituting the Anticenter Stream in the western portion of the Sloan Digital Sky Survey footprint. We explore possible explanations for this, and suggest that our data in SA 76 are measuring the motion of a kinematically cold sub-stream among the ACS debris that was likely a fragment of the same infalling structure that created the larger ACS system. The ACS is clearly separated spatially from the majority of claimed Monoceros ring detections in this region of the sky; however, with the data in hand, we are unable to either confirm or rule out an association between the ACS and the poorly-understood Monoceros structure.Comment: Accepted to ApJ. 48 pages, 20 figures, preprint forma

    Restructuring Programming Instruction in the Computer Information Systems Curriculum: One Department\u27s Approach

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    The rationale for and details of one Computer Information Systems (CIS) department\u27s plans for a drastic restructuring of the CIS curriculum are presented. The proposed approach is compared with current and developing model curricula for both computer science (CS) and computer information systems programs. The new curriculum\u27s approach to information systems construction is characterized by delivering training in the use of fourth generation development tools, the assembly of software components, event-driven programming and client/server practices. The development tools, the programming environment and the client interface are all equipped with a graphical user interface (GUI)

    Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes

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    We report the results of a spectroscopic study of the Bootes (Boo) dwarf spheroidal (dSph) galaxy carried out with the WIYN telescope and the Hydra multifiber spectrograph. Radial velocities have been measured for 58 Boo candidate stars selected to have magnitudes and colors consistent with its red and asymptotic giant branches. Within the 13' half-light radius, seven members of Boo yield a systemic velocity of V_r=95.6+-3.4 km/s and a velocity dispersion of 6.6+-2.3 km/s. This implies a mass on the order of 1 x 10^7 M_sun, similar to the inferred masses of other Galactic dSphs. Adopting a total Boo luminosity of L=1.8 x 10^4 L_sun to 8.6 x 10^4 L_sun implies M/L ~ 610 to 130, making Boo, the most distorted known Milky Way dwarf galaxy, potentially also the darkest. From the spectra of Boo member stars we estimate its metallicity to be [Fe/H] ~ -2.5, which would make it the most metal poor dSph known to date.Comment: Accepted for publication in ApJ Letter

    Deletion of Tsc2 in nociceptors reduces target innervation, ion channel expression, and sensitivity to heat

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    AbstractThe mechanistic target of rapamycin complex 1 (mTORC1) is known to regulate cellular growth pathways, and its genetic activation is sufficient to enhance regenerative axon growth following injury to the central or peripheral nervous systems. However, excess mTORC1 activation may promote innervation defects, and mTORC1 activity mediates injury-induced hypersensitivity, reducing enthusiasm for the pathway as a therapeutic target. While mTORC1 activity is required for full expression of some pain modalities, the effects of pathway activation on nociceptor phenotypes and sensory behaviors are currently unknown. To address this, we genetically activated mTORC1 in mouse peripheral sensory neurons by conditional deletion of its negative regulator Tuberous Sclerosis Complex 2 (Tsc2). Consistent with the well-known role of mTORC1 in regulating cell size, soma size and axon diameter of C-nociceptors were increased in Tsc2-deleted mice. Glabrous skin and spinal cord innervation by C-fiber neurons were also disrupted. Transcriptional profiling of nociceptors enriched by fluorescence-associated cell sorting (FACS) revealed downregulation of multiple classes of ion channels as well as reduced expression of markers for peptidergic nociceptors in Tsc2-deleted mice. In addition to these changes in innervation and gene expression, Tsc2-deleted mice exhibited reduced noxious heat sensitivity and decreased injury-induced cold hypersensitivity, but normal baseline sensitivity to cold and mechanical stimuli. Together, these data show that excess mTORC1 activity in sensory neurons produces changes in gene expression, neuron morphology and sensory behavior.</jats:p

    Mutual cross-talk between fibronectin integrins and the EGF receptor: Molecular basis and biological significance

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    Extension of the plasma membrane is one of the first steps in cell migration. Understanding how cells “choose” between various types of membrane protrusion enhances our knowledge of both normal and cancer cell physiology. The EGF receptor is a paradigm for understanding how transmembrane receptor tyrosine kinases regulate intracellular signaling following ligand stimulation. Evidence from the past decade indicates that EGF receptors also form macromolecular complexes with integrin receptors leading to EGF receptor transactivation during cell adhesion. However, relatively little is known about how these complexes form and impact cell migration. Our recent work characterized a molecular complex between EGF receptor and β3 integrin which recognizes RGD motifs in extracellular matrix proteins. Complex formation requires a dileucine motif (679-LL) in the intracellular juxtamembrane region of the EGF receptor that also controls whether or not the receptor undergoes Src kinase-dependent phosphorylation at Tyr-845. In contrast to wild-type receptors, mutant EGF receptors defective for Tyr-845 phosphorylation form complexes with β1 integrin that also binds RGD motifs. In addition, we have discovered that EGF receptor antagonizes small GTPase RhoA by mediating membrane recruitment of its regulatory GAP p190RhoGAP. In this addendum we discuss a potential new role for Src-dependent EGF receptor transactivation in integrin/EGF receptor complex formation. We also discuss how our study fits with previous observations linking p190RhoGAP to RhoA-dependent cytoskeletal rearrangements involved in cell migration, and provide new data that the EGF receptor is compartmentalized to relatively immature zyxin-poor focal adhesions which are the likely site of p190RhoGAP signaling
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