11,836 research outputs found
Magnetic Vortex Resonance in Patterned Ferromagnetic Dots
We report a high-resolution experimental detection of the resonant behavior
of magnetic vortices confined in small disk-shaped ferromagnetic dots. The
samples are magnetically soft Fe-Ni disks of diameter 1.1 and 2.2 um, and
thickness 20 and 40 nm patterned via electron beam lithography onto microwave
co-planar waveguides. The vortex excitation spectra were probed by a vector
network analyzer operating in reflection mode, which records the derivative of
the real and the imaginary impedance as a function of frequency. The spectra
show well-defined resonance peaks in magnetic fields smaller than the
characteristic vortex annihilation field. Resonances at 162 and 272 MHz were
detected for 2.2 and 1.1 um disks with thickness 40 nm, respectively. A
resonance peak at 83 MHz was detected for 20-nm thick, 2-um diameter disks. The
resonance frequencies exhibit weak field dependence, and scale as a function of
the dot geometrical aspect ratio. The measured frequencies are well described
by micromagnetic and analytical calculations that rely only on known properties
of the dots (such as the dot diameter, thickness, saturation magnetization, and
exchange stiffness constant) without any adjustable parameters. We find that
the observed resonance originates from the translational motion of the magnetic
vortex core.Comment: submitted to PRB, 17 pages, 5 Fig
Characterization of Megatrypanum trypanosomes from European Cervidae
Megatrypanum trypanosomes have been isolated from a number of different European Cervidae, but on the basis of morphology it has not been possible to define the species to which these isolates belong. We isolated Trypanosoma (Megatrypanum) theileri from 10 cattle, and Megatrypanum trypanosomes from 11 fallow deer (Cervus dama), 9 red deer (Cervus elaphus), and 4 roe deer (Capreolus capreolus) by blood culture on a biphasic medium (NNN agar slopes). Trypanosomes were propagated in Schneider's Drosophila medium and characterized by isoenzyme analysis and molecular karyotyping. Isocitrate dehydrogenase and phosphoglucomutase were visualized after starch gel electrophoresis of trypanosome lysates. By cluster analysis of this data all isolates from deer were clearly separated from the T. (M.) theileri isolates from cattle. Isolates from roe deer were different not only from T. (M.) theileri but also from the other deer isolates. Isolates from fallow deer and red deer were grouped together. Thus, there are probably at least two different species of Megatrypanum trypanosomes in the three Cervidae. One parasitizing roe deer, the other, apparently less host specific species, infecting red deer and fallow deer. Separation of the chromosomes of Megatrypanum trypanosomes by pulsed-field gradient gel electrophoresis (PFGE) showed that each isolate contained a large number (> 18) of chromosomes ranging in size from 300 to > 2200 kb. The molecular karyotypes were similar for all isolates, although no isolate was identical to anothe
Thermal and Surface Core-Electron Binding-Energy Shifts in Metals
High-resolution photoemission spectra from the shallow core levels of alkali metals and of In have been obtained between 78 K and room temperature. The data yield values for the alkali-metal surface-atom core-level shift and show thermal shifts of comparable size for bulk and surface. The positive surface shifts are due to the spill-out of conduction-electron charge, which is responsible for the surface dipole layer. The surface shifts are in good agreement with values obtained from a Born-Haber cycle expressed in terms of surface energies. The thermal shifts are proportional to the lattice expansion, and arise from both initial-state and final-state effects. As the lattice expands, the Fermi level decreases, decreasing the core-electron binding energy. At the same time, the expansion of the conduction-electron charge increases rs, thereby decreasing the potential at the core level and increasing the binding energy. The expansion also decreases the relaxation energy, further increasing the core-electron binding energy. In the alkali metals, the combined potential- and relaxation-energy terms dominate the Fermi-level term, making the shifts positive. In divalent metals the three terms tend to cancel, while in trivalent metals it is the Fermi-level term that dominates, making the shifts negative
A user-centric system architecture for residential energy consumption reduction
Long-term energy consumption reduction can be achieved more readily through sensible cooperation between end users and technological advancements. The DANCER project presented here proposes a user-centric residential energy management system, with the intention to achieve long-term energy related behavioural changes, thus improving the energy efficiency of modern homes. Although, it follows the same basic principles as other contemporary approaches, it focuses on minimizing the interaction of the user with the system. This is achieved through an improved feedback mechanism and a generic, policy based service that takes advantage of the modularity and generality of the software architecture. The proposed system is designed to support a variety of technologies (WiFi, Zigbee, X10), in order to ameliorate the input and output of the decision making operation. In this paper, the general outline of the DANCER system architecture and its most important components are discussed and the prototype test-bed is presented. Special consideration is given to the implementation, operation and response behaviour of the prototype
The reality of cross-disciplinary energy research in the United Kingdom:a social science perspective
Cross-disciplinary research is essential in understanding and reducing energy usage, however the reality of this collaboration comes with many challenges. This paper provides an insight into the integration of social science in energy research, drawing on the expertise and first hand experiences of a range of social science researchers (predominantly Early Career Researchers (ECRs)) working on UK cross-disciplinary projects in energy demand. These researchers, participants in a workshop dedicated to understanding the integration of social science in energy research, identified four groups of challenges to successful integration: Differing expectations of the role of social scientists; Working within academia; Feeling like a valued member of the team; and Communicating and comprehension between disciplines. Suggestions of how to negotiate those challenges included: Management and planning; Increasing contact; Sharing experience; and Understanding team roles. The paper offers a definition of âsuccessâ in cross-disciplinary energy research from the perspective of social science ECRs, comprising external, internal and personal components. Using the logics of interdisciplinarity, this paper suggests that integration of the social sciences in the projects discussed may be partial at best and highlights a need to recognise the challenges ECRs face, in order to achieve full integration and equality of disciplines
Coiling Instability of Multilamellar Membrane Tubes with Anchored Polymers
We study experimentally a coiling instability of cylindrical multilamellar
stacks of phospholipid membranes, induced by polymers with hydrophobic anchors
grafted along their hydrophilic backbone. Our system is unique in that coils
form in the absence of both twist and adhesion. We interpret our experimental
results in terms of a model in which local membrane curvature and polymer
concentration are coupled. The model predicts the occurrence of maximally tight
coils above a threshold polymer occupancy. A proper comparison between the
model and experiment involved imaging of projections from simulated coiled
tubes with maximal curvature and complicated torsions.Comment: 11 pages + 7 GIF figures + 10 JPEG figure
The heating mechanism for the warm/cool dust in powerful, radio-loud AGN
The uncertainty surrounding the nature of the heating mechanism for the dust
that emits at mid- to far-IR (MFIR) wavelengths in active galaxies limits our
understanding of the links between active galactic nuclei (AGN) and galaxy
evolution, as well as our ability to interpret the prodigious infrared and
sub-mm emission of some of the most distant galaxies in the Universe. Here we
report deep Spitzer observations of a complete sample of powerful, intermediate
redshift (0.05 < z < 0.7) radio galaxies and quasars. We show that AGN power,
as traced by [OIII]5007 emission, is strongly correlated with both the mid-IR
(24 micron) and the far-IR (70 micron) luminosities, however, with increased
scatter in the 70 micron correlation. A major cause of this increased scatter
is a group of objects that falls above the main correlation and displays
evidence for prodigious recent star formation activity at optical wavelengths,
along with relatively cool MFIR colours. These results provide evidence that
illumination by the AGN is the primary heating mechanism for the dust emitting
at both 24 and 70 microns, with starbursts dominating the heating of the cool
dust in only 20 -- 30% of objects. This implies that powerful AGN are not
always accompanied by the type of luminous starbursts that are characteristic
of the peak of activity in major gas-rich mergers.Comment: 13 pages, 3 figures. Accepted for publication in astrophysical
journal letter
3-Hydroxy-3-methylglutaric aciduria: Response to carnitine therapy and fat and leucine restriction
A female infant, born to first cousin parents, lapsed into coma with severe metabolic acidosis on day three of life. The gas chromatographic/mass spectrometric urinary organic acid profile showed marked elevation of the leucine metabolites 3-hydroxy-3-methylglutaric, 3-methylglutaconic, 3-methylglutaric and 3-hydroxy-isovaleric acids. Less than 5% of the normal activity of the enzyme 3-hydroxy-3-methylglutaryl CoA lyase was detected in cultured skin fibroblasts. The patient's total and free carnitine was initially low but rose to normal levels after placing her on dl -carnitine (100 mg kg â1 d â1 ). On a diet providing 87 mg kg â1 d â1 of leucine and only 25% of total calories as fat and 2 g kg â1 d â1 protein, the concentration of the urinary organic acids fell markedly. She is now 15 months old with normal growth and development. This regimen appears effective in the early treatment of 3-hydroxy-3-methylglutaric aciduria.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42492/1/10545_2005_Article_BF01800039.pd
The HPS electromagnetic calorimeter
The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called âheavy photon.â Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015â2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. The detector is a homogeneous calorimeter, made of 442 lead-tungstate (PbWO4) scintillating crystals, each read out by an avalanche photodiode coupled to a custom trans-impedance amplifier
Quantum decision making by social agents
The influence of additional information on the decision making of agents, who
are interacting members of a society, is analyzed within the mathematical
framework based on the use of quantum probabilities. The introduction of social
interactions, which influence the decisions of individual agents, leads to a
generalization of the quantum decision theory developed earlier by the authors
for separate individuals. The generalized approach is free of the standard
paradoxes of classical decision theory. This approach also explains the
error-attenuation effects observed for the paradoxes occurring when decision
makers, who are members of a society, consult with each other, increasing in
this way the available mutual information. A precise correspondence between
quantum decision theory and classical utility theory is formulated via the
introduction of an intermediate probabilistic version of utility theory of a
novel form, which obeys the requirement that zero-utility prospects should have
zero probability weights.Comment: This paper has been withdrawn by the authors because a much extended
and improved version has been submitted as arXiv:1510.02686 under the new
title "Role of information in decision making of social agents
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