Search results for "Magnetism"
showing 10 items of 1934 documents
Spin Glasses on Thin Graphs
1995
In a recent paper we found strong evidence from simulations that the Isingantiferromagnet on ``thin'' random graphs - Feynman diagrams - displayed amean-field spin glass transition. The intrinsic interest of considering such random graphs is that they give mean field results without long range interactions or the drawbacks, arising from boundary problems, of the Bethe lattice. In this paper we reprise the saddle point calculations for the Ising and Potts ferromagnet, antiferromagnet and spin glass on Feynman diagrams. We use standard results from bifurcation theory that enable us to treat an arbitrary number of replicas and any quenched bond distribution. We note the agreement between the f…
Domain walls in supersymmetric QCD: The taming of the zoo
2000
We provide a unified picture of the domain wall spectrum in supersymmetric QCD with Nc colors and Nf flavors of quarks in the (anti-) fundamental representation. Within the framework of the Veneziano-Yankielowicz-Taylor effective Lagrangian, we consider domain walls connecting chiral symmetry breaking vacua, and we take the quark masses to be degenerate. For Nf/Ncm** there is no domain wall. We numerically determine m* and m** as a function of Nf/Nc, and we find that m** approaches a constant value in the limit that this ratio goes to one.
La imagen del magnetismo animal en la literatura de ficción : los casos de Poe, Doyle y Du Maurier
2014
En el presente trabajo nos acercamos a la imagen social del fenómeno conocido como mesmerismo o magnetismo animal a través del análisis de las obras: The Facts in the Case of Mr. Valdemar (1845) de Edgar Allan Poe, The Great Keinplatz Experiment (1885) de Conan Doyle y Trilby (1894) de George Du Maurier. Mostraremos cuál es el estereotipo del magnetizador y los usos que observamos del mesmerismo. Nos acercaremos a los espacios y actores del trasunto mesmerico presentado en los relatos. Tendremos en cuenta la recepción por parte del público de estas historias y las relaciones con los conocimientos mesmericos e hipnóticos que tenían los autores de éstas. En la actualidad, investigadores acadé…
Histidine-rich glycoprotein-induced vascular normalization improves EPR-mediated drug targeting to and into tumors
2018
Tumors are characterized by leaky blood vessels, and by an abnormal and heterogeneous vascular network. These pathophysiological characteristics contribute to the enhanced permeability and retention (EPR) effect, which is one of the key rationales for developing tumor-targeted drug delivery systems. Vessel abnormality and heterogeneity, however, which typically result from excessive pro-angiogenic signaling, can also hinder efficient drug delivery to and into tumors. Using histidine-rich glycoprotein (HRG) knockout and wild type mice, and HRG-overexpressing and normal t241 fibrosarcoma cells, we evaluated the effect of genetically induced and macrophage-mediated vascular normalization on th…
Einstein's Washington Manuscript on Unified Field Theory
2020
In this note, we point attention to and briefly discuss a curious manuscript of Einstein, composed in 1938 and entitled "Unified Field Theory," the only such writing, published or unpublished, carrying this title without any further specification. Apparently never intended for publication, the manuscript sheds light both on Einstein's modus operandi as well as on the public role of Einstein's later work on a unified field theory of gravitation and electromagnetism.
Mössbauer Spectroscopy: Elegance and versatility in chemical diagnostics
2010
Dedicated to Professor Rudolf Ludwig Mossbauer on the occasion of his 80th birthday . Soon after the discovery of the recoilless nuclear resonance fluorescence by Rudolf L. Mossbauer some fifty years ago a new spectroscopic technique developed quickly on the basis of this resonance phenomenon as an excellent tool for the investigation of materials through electric and magnetic hyperfine interactions between electrons and suitable Mo uml ssbauer nu-clides. Many disciplines of solid state research have benefited from applications of the new tool for non-destructive phase analysis. Chemists in particular have recognized the information that can be derived from Mo uml ssbauer spectra regarding …
Magnetic properties of colloidal cobalt nanoclusters
2010
Abstract. Co nanoclusters were synthesized by an inverse-micelle chemical route. The magnetic and microstructural properties of the nanoparticles have been analyzed as a function of the surfactant (AOT and DEHP) and the drying method. Microstructural analysis has been performed by TEM and XANES; magnetic properties have been studied by hysteresis loops and zero-field cooling - field cooling (ZFC-FC) curves. TEM images show 2 to 4 nm sized particles spherical in shape. XANES measurements point out a significant presence of Co3O4 with metallic Co and some Co2+ bound to the surfactant. The presence of antiferromagnetic Co3O4 explains the magnetic transition observed at low T in both ZFC-FC mea…
Raman scattering in nanosized nickel oxide NiO
2007
Magnetic ordering in nanosized (100 and 1500 nm) nickel oxide NiO powders, prepared by the plasma synthesis method, was studied using Raman scattering spectroscopy in a wide range of temperatures from 10 to 300 K. It was observed that the intensity of two- magnon band decreases rapidly for smaller crystallites size. This effect is attributed to a decrease of antiferromagnetic spin correlations and leads to the antiferromagnetic-to- paramagnetic phase transition .
Absence of element specific ferromagnetism in Co doped ZnO investigated by soft X-ray resonant reflectivity
2010
On the quest for the intrinsic origin of ferromagnetism (FM) in ZnO doped with a few percent transition metal, we show detailed X-ray resonant magnetic reflectivity (XRMR) measurements, performed at the Co L2,3 and the O K edges of pulsed laser deposition (PLD) prepared samples. These samples show ferromagnetism at room temperature (RT) (QUID: about 2μB /Co). But in contrast to the QUID measurements, element specific reflection measurements as a function of angle (θ-2θ scans) and energy (const. qz) do not show any sign of ferromagnetism. Therefore, we can exclude without doubt Co as a possible origin for FM in this system. Our results are in perfect agreement with earlier published XMCD dat…
Electronic and vibronic problems of nanosized mixed valence clusters: Advances and challenges
2013
Here we discuss the electronic and vibronic problems of mixed valency (MV) in molecular clusters which are of current interest in areas as diverse as solid-state chemistry, biochemistry, and molecular magnetism. Modern research in these areas is focused on the nanosized clusters at the border between classical and quantum scales and for this reason they are particularly difficult to study. First, we describe a general approach to the evaluation of the energy pattern of MV systems containing arbitrary number of localized spins and itinerant electrons with due account for the double exchange and other relevant interactions, like interelectronic Coulomb repulsion in instantly localized configu…