3,521 research outputs found
SU(4) Fermi Liquid State and Spin Filtering in a Double Quantum Dot System
We study a symmetrical double quantum dot (DD) system with strong capacitive
inter-dot coupling using renormalization group methods. The dots are attached
to separate leads, and there can be a weak tunneling between them. In the
regime where there is a single electron on the DD the low-energy behavior is
characterized by an SU(4)-symmetric Fermi liquid theory with entangled spin and
charge Kondo correlations and a phase shift . Application of an external
magnetic field gives rise to a large magneto-conductance and a crossover to a
purely charge Kondo state in the charge sector with SU(2) symmetry. In a four
lead setup we find perfectly spin polarized transmission.Comment: 4 pages, 4 figures, ReVTe
Two-phonon 1- state in 112Sn observed in resonant photon scattering
Results of a photon scattering experiment on 112Sn using bremsstrahlung with
an endpoint energy of E_0 = 3.8 MeV are reported. A J = 1 state at E_x =
3434(1) keV has been excited. Its decay width into the ground state amounts to
Gamma_0 = 151(17) meV, making it a candidate for a [2+ x 3-]1- two-phonon
state. The results for 112Sn are compared with quasiparticle-phonon model
calculations as well as the systematics of the lowest-lying 1- states
established in other even-mass tin isotopes. Contrary to findings in the
heavier stable even-mass Sn isotopes, no 2+ states between 2 and 3.5 MeV
excitation energy have been detected in the present experiment.Comment: 10 pages, including 2 figures, Phys. Rev. C, in pres
SPI/INTEGRAL observation of the Cygnus region
We present the analysis of the first observations of the Cygnus region by the
SPI spectrometer onboard the Integral Gamma Ray Observatory, encompassing
600 ks of data. Three sources namely Cyg X-1, Cyg X-3 and EXO 2030+375
were clearly detected. Our data illustrate the temporal variability of Cyg X-1
in the energy range from 20 keV to 300 keV. The spectral analysis shows a
remarkable stability of the Cyg X-1 spectra when averaged over one day
timescale. The other goal of these observations is SPI inflight calibration and
performance verification. The latest objective has been achieved as
demonstrated by the results presented in this paper.Comment: 6 pages, 10 figures, accepted for publication in A&A (special
INTEGRAL volume
Use of long-term microdialysis subcutaneous glucose monitoring in the management of neonatal diabetes - A first case report
In neonatal diabetes mellitus (NDM), a rare genetic disorder, insulin therapy is required but the management is difficult. Frequent blood glucose determinations are necessary in most cases. Microdialysis subcutaneous glucose monitoring (MSGM) is feasible in neonates and has been proposed to reduce painful blood sampling and blood loss. We have applied long-term MSGM to a small-fordate female newborn with transient NDM. We found a good correlation of subcutaneous and blood glucose concentration over a wide range of values. MSGM enabled a reduction in blood glucose determinations during optimization of intravenous insulin treatment and initiation of continuous subcutaneous insulin infusion. We conclude that long-term MSGM is feasible and may reduce painful blood sampling and blood loss in NDM. Furthermore, long-term MSGM may hold a potential for avoiding hypoglycemic episodes and earlier discharge. Copyright (C) 2006 S. Karger AG, Basel
Can filesharers be triggered by economic incentives? Results of an experiment
Illegal filesharing on the internet leads to considerable financial losses for artists and copyright owners as well as producers and sellers of music. Thus far, measures to contain this phenomenon have been rather restrictive. However, there are still a considerable number of illegal systems, and users are able to decide quite freely between legal and illegal downloads because the latter are still difficult to sanction. Recent economic approaches account for the improved bargaining position of users. They are based on the idea of revenue-splitting between professional sellers and peers. In order to test such an innovative business model, the study reported in this article carried out an experiment with 100 undergraduate students, forming five small peer-to-peer networks.The networks were confronted with different economic conditions.The results indicate that even experienced filesharers hold favourable attitudes towards revenue-splitting.They seem to be willing to adjust their behaviour to different economic conditions
Minimizing complications during retropubic radical prostatectomy - is ureteral stenting necessary?
<p>Abstract</p> <p>Objectives and aims</p> <p>To avoid damage to the ureters during bladder neck preparation in radical prostatectomy for prostate cancer, it may be helpful to insert ureteral stents temporarily or to intravenously administer indigo carmine dye for enhanced visualisation of ureteric orifices. We evaluated our bladder neck preserving technique at radical prostatectomy with regard to ureteric injuries.</p> <p>Patients and methods</p> <p>We analysed 369 consecutive radical prostatectomies operated in our clinic in a bladder neck preserving technique. The following parameters were assessed in this retrospective study: number of prophylactic ureteric stent insertions, application of indigo carmine dye, observed injuries of the ureters by the surgeon, postoperative increase of serum creatinine and postoperative status of kidney ultrasound.</p> <p>Results</p> <p>In 7/369 prostatectomies (1.90%) a ureteric stent insertion was performed, indigo carmine was not applied to any patient at all, yet no intraoperative injury of a ureter was observed by a surgeon. No revision was necessary due to a ureteral injury within the observation period of one year after surgery. In 17 patients with preoperative normal creatinine value a pathological value was observed on the first postoperative day (mean 1.4 mg/dl). In these patients no consecutive postrenal acute renal failure was observed, no hydronephrosis was monitored by ultrasound and no further intervention was necessary.</p> <p>Conclusions</p> <p>Bladder neck preserving operation technique does not implicate the need of prophylactic ureteric stent insertions and has no higher incidence of ureteric injuries.</p
Universality of Decoherence
We consider environment induced decoherence of quantum superpositions to
mixtures in the limit in which that process is much faster than any competing
one generated by the Hamiltonian of the isolated system. While
the golden rule then does not apply we can discard . By allowing
for simultaneous couplings to different reservoirs, we reveal decoherence as a
universal short-time phenomenon independent of the character of the system as
well as the bath and of the basis the superimposed states are taken from. We
discuss consequences for the classical behavior of the macroworld and quantum
measurement: For the decoherence of superpositions of macroscopically distinct
states the system Hamiltonian is always negligible.Comment: 4 revtex pages, no figure
Multiwaveband Observations of Quasars with Flat Radio Spectra and Strong Millimeter Emission
We present multiwaveband observations of a well selected sample of 28 quasars
and two radio galaxies with flat radio spectra and strong millimeter wave
emission (referred to here as FSRQ's). The observations include multifrequency
VLBI measurements, X-ray observations with ROSAT and submillimeter observations
with the JCMT. Particularly interesting among many findings is a correlation
between the X-ray to millimeter spectral index and fraction of flux density
contained in the VLBI core. This tendency toward higher X-ray fluxes from
sources with stronger jet emission implies that the knots in the jet are the
prominent source of X-rays.Comment: 38 pages, 17 figures, 12 tables, accepted for publication in Ap J
Suppl, May 199
Warren McCulloch and the British cyberneticians
Warren McCulloch was a significant influence on a number of British cyberneticians, as some British pioneers in this area were on him. He interacted regularly with most of the main figures on the British cybernetics scene, forming close friendships and collaborations with several, as well as mentoring others. Many of these interactions stemmed from a 1949 visit to London during which he gave the opening talk at the inaugural meeting of the Ratio Club, a gathering of brilliant, mainly young, British scientists working in areas related to cybernetics. This paper traces some of these relationships and interaction
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