1,716 research outputs found
Observation of electron spin resonance of negative ions in liquid helium
Electron spin resonance signals of negative ions in liquid helium were observed. The line width and g-value were measured. Electrons injected into helium by field emission from ferromagnetic tips are shown to be polarized. A new technique for the measurement of electron spin polarization is presented
Micro Electro Kinetic Actuator (MEKA) arrays for active sublayer control of turbulent boundary layers
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77296/1/AIAA-2002-267-217.pd
Does geothermal exploitation trigger earthquakes in Tuscany?
For the past 25 years, power production has been accompanied by a small but steady increase in seismicity near geothermal wells. A new project seeks to explore why
Blowout limits of turbulent jet diffusion flames for arbitrary source conditions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76791/1/AIAA-25186-342.pd
An improved seismicity picture of the Southern Tyrrhenian area by the use of OBS and land-based networks: the TYDE experiment
The problem of large location uncertainties for seismicity occurring in the Southern Tyrrhenian
Sea have been partially exceeded during the implementation of the long-term scientific mission of
the TYrrhenian Deep sea Experiment (TYDE), which allowed the installation of 14 wide-band
Ocean Bottom Seismometers (OBS) and Hydrophones (OBH) in the period December 2000 â May
2001 on the sea-bottom floor around the Aeolian and Ustica Islands. Local events recorded at landstations
have been observed also on the seismograms of the Ocean Bottom Seismic Network
(OBSN). Moreover, some hundreds of low magnitude events, undetected from the land networks,
have been recorded.
We combined the readings of body wave arrival times from OBS-OBH with those from landstations
to localise seismic events. We focused our study on three clusters of events representative
of the seismic activity of the area: (i) âdeepâ events, (ii) Ustica (iii) NE-Sicily. The analysis of the
integrated data set of the seismicity off-shore and on-shore, obtained from the combined land-OBS
seismic network (Ustica sequence and Deep events), has improved locations in terms of RMS
residuals, azimuthal gap, epicentral and hypocentral errors. Moreover, further classes of events have
been analysed: the first one includes some local events that could be located only by integrating single trigger readings from the few available land-stations with the OBSN-data; the second one
comprises local events that have been detected only by the OBS-OBH stations. In particular, the last
cluster underlines the importance of an OBSN in the Tyrrhenian deep basin to reveal its unknown
intense micro-seismicity, permitting to better understand both the tectonic and geodynamic picture
of the area
Seismic array analysis of Tornillo-like signals recorded in Tuscany
With the scientific purpose to monitor the micro-seismicity in the Central Apennines, we recently
deployed in Eastern Tuscany (Casentino) a temporary 12 element seismic array, composed
exclusively of 3-component seismometers. During the one month of registration we recorded an
unexpected high rate of local micro-seismicity with up to 180 events per day
Theory for Electron-Doped Cuprate Superconductors: d-wave symmetry order parameter
Using as a model the Hubbard Hamiltonian we determine various basic
properties of electron-doped cuprate superconductors like
and for a
spin-fluctuation-induced pairing mechanism. Most importantly we find a narrow
range of superconductivity and like for hole-doped cuprates -
symmetry for the superconducting order parameter. The superconducting
transition temperatures for various electron doping concentrations
are calculated to be much smaller than for hole-doped cuprates due to the
different Fermi surface and a flat band well below the Fermi level. Lattice
disorder may sensitively distort the symmetry via
electron-phonon interaction
Conceptual aspects of QCD factorization in hadronic B decays
I review the meaning of ``QCD factorization'' in hadronic two-body B decays
and then discuss recent results of theoretical (rather than phenomenological)
nature: the proof of factorization at two loops; the identification of
``chirally enhanced'' power corrections; and the role of annihilation
contributions.Comment: 10 pages, LaTeX. Based on talks presented at the UK Phenomenology
Workshop on Heavy Flavour and CP Violation, 17 - 22 September 2000, Durham,
proceedings to appear in J. Phys. G; the 5th International Symposium on
Radiative Corrections (RADCOR2000), Carmel, California, September 11 - 15,
2000; the 4th Workshop on Continuous Advances in QCD, Minneapolis, 12-14 May
2000; the Vth International Workshop on Heavy Quark Physics, Dubna, 6-8 April
200
Charge current in ferromagnet - triplet superconductor junctions
We calculate the tunneling conductance spectra of a ferromagnetic metal /
insulator / triplet superconductor from the reflection amplitudes using the
Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor, we
assume one special -wave order parameter, having line nodes, and two two
dimensional -wave order parameters with line nodes, breaking the time
reversal symmetry. Also we examine nodeless pairing potentials. The evolution
of the spectra with the exchange potential depends solely on the topology of
the gap. The weak Andreev reflection within the ferromagnet results in the
suppression of the tunneling conductance and eliminates the resonances due to
the anisotropy of the pairing potential. The tunneling spectra splits
asymmetrically with respect to under the influence of an external
magnetic field. The results can be used to distinguish between the possible
candidate pairing states of the superconductor SrRuO.Comment: 15 pages with 8 figure
The Non-thermal Radio Jet Toward the NGC 2264 Star Formation Region
We report sensitive VLA 3.6 cm radio observations toward the head of the Cone
nebula in NGC 2264, made in 2006. The purpose of these observations was to
study a non-thermal radio jet recently discovered, that appears to emanate from
the head of the Cone nebula. The jet is highly polarized, with well-defined
knots, and one-sided. The comparison of our images with 1995 archive data
indicates no evidence of proper motions nor polarization changes. We find
reliable flux density variations in only one knot, which we tentatively
identify as the core of a quasar or radio galaxy. An extragalactic location
seems to be the best explanation for this jet.Comment: 12 pages, 5 figure
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