1,349 research outputs found
Frequency Shifts Inherent in the 6328 a Helium-neon Laser
Frequency shifts inherent in helium neon lase
Development of lasers for plasma diagnostics
Optical heterodyne system used to measure electron density of plasm
Urological procedures in Central Europe and the current reality based on the national registries of Czech Republic, Hungary, and Poland (2012 status)
INTRODUCTION: In recent years, the laparoscopic approach in oncologic urology seems more attractable to the surgeons. It is considered to have the same oncologic quality as open surgery, but is less invasive in patients. It is used widely in all of Europe, but with various frequency. The aim of the study was to present a various amount of oncourological procedures from three neighbouring countries - Poland, Czech Republic and Hungary. Prostatectomy, cystectomy, nephrectomy and tumorectomy (Nephron Sparing Procedures - NSS) were presented as a list of procedures prepared from the national registry. MATERIAL AND METHODS: The total amount of procedures was presented, as well as the LO (Lap to Open procedures) index, P/P (procedures/population) index, ratio of cystectomy/population, and cystectomy/TURBT. RESULTS: In the Czech Republic, the most complex procedures are performed (laparoscopic/robotic prostatectomy, NSS LAP, LAP nephrectomy) in the majority when analysing the country's population. In Hungary and Czech Republic, there are more laparoscopic/robotic radical prostatectomies performed, than open ones. In Poland the largest number of cystectomies is performed when analysing the country's population, but it is difficult to explain the much higher ratio of 6.57 TUR/one cystectomy. In the Czech Republic this procedure is performed in almost one quarter of the patients (23.36%). Interestingly, in Hungary the cystectomy with pouch creation is performed in about 67.65% cases. The highest reimbursement for surgical procedure is present in the Czech Republic with approximately 20-40% more than when compared to Poland or Hungary. CONCLUSIONS: The definitive leader in Central Europe (based on the national registry) is the Czech Republic, where the most complex procedures are performed (laparoscopic/robotic prostatectomy, NSS LAP, LAP nephrectomy) in biggest amounts when analysing the country's population. Explanation of such circumstances, can be the higher reimbursement rate for surgical procedure in this country
High-carrier-density electron dynamics in low-temperature-grown GaAs
Pump-probe differential transmission measurements examine high-carrier-density phenomena in as-grown and annealed GaAs samples grown at temperatures from 210 to 270 °C. We observe trap saturation and Auger recombination, and accurately model the measurements on annealed samples with a simple two level rate equation, allowing us to extract the trapped-electron lifetimes. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70634/2/APPLAB-70-24-3245-1.pd
Dephasing times in quantum dots due to elastic LO phonon-carrier collisions
Interpretation of experiments on quantum dot (QD) lasers presents a
challenge: the phonon bottleneck, which should strongly suppress relaxation and
dephasing of the discrete energy states, often seems to be inoperative. We
suggest and develop a theory for an intrinsic mechanism for dephasing in QD's:
second-order elastic interaction between quantum dot charge carriers and
LO-phonons. The calculated dephasing times are of the order of 200 fs at room
temperature, consistent with experiments. The phonon bottleneck thus does not
prevent significant room temperature dephasing.Comment: 4 pages, 1 figure, accepted for Phys. Rev. Let
Early impact of aortic wrapping on patients undergoing aortic valve replacement with mild to moderate ascending aorta dilatation
<p>Abstract</p> <p>Background</p> <p>The management of mild to moderate dilatation of the ascending aorta of less than 5 cm is controversial, particularly when concomitant surgical correction of aortic valve is required. We investigate the impact of a simple method of aorta reduction using Dacron graft wrapping during aortic valve replacement on the rest of the aorta.</p> <p>Methods</p> <p>We studied 14 patients who had ascending aorta dilatation of 4-5 cm before undergoing aortic wrapping during their aortic valve replacement and compared with their post-operative imaging within a month.</p> <p>Results</p> <p>The diameters of the ascending aorta wrapped with the Dacron graft were significantly reduced within 4 weeks after surgery from 44.7 ± 2.6 to 33.6 ± 3.9 mm (p < 0.001). This was associated with significant reduction in the diameter of rest of ascending aorta: coronary sinuses (from 37.9 ± 4.9 mm to 33.3 ± 6.1 mm; p < 0.001), sinotubular junction (from 33.2 ± 4.7 mm to 30.6 ± 4.4 mm, p = 0.02), and aortic arch (from 34.7 ± 4.3 mm to 32.6 ± 4.1 mm, p = 0.03).</p> <p>Conclusions</p> <p>Reduction of ascending aortic dilatation by wrapping with a Dacron graft in this preliminary study is associated with favourable early reversed aortic remodelling. This supports the hypothesis that correction of mild-moderate dilatation of the ascending aorta with Dacron wrapping at the time of aortic valve surgery may prevent the progression of the dilatation, although the long-term study on a larger population is needed to confirm its benefits.</p
Geometry dependence of Auger carrier capture rates into cone-shaped self-assembled quantum dots
Determination of the b quark mass at the M_Z scale with the DELPHI detector at LEP
An experimental study of the normalized three-jet rate of b quark events with
respect to light quarks events (light= \ell \equiv u,d,s) has been performed
using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by
the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are
found to agree with theoretical predictions treating mass corrections at
next-to-leading order. Measurements of the b quark mass have also been
performed for both the b pole mass: M_b and the b running mass: m_b(M_Z). Data
are found to be better described when using the running mass. The measurement
yields: m_b(M_Z) = 2.85 +/- 0.18 (stat) +/- 0.13 (exp) +/- 0.19 (had) +/- 0.12
(theo) GeV/c^2 for the CAMBRIDGE algorithm. This result is the most precise
measurement of the b mass derived from a high energy process. When compared to
other b mass determinations by experiments at lower energy scales, this value
agrees with the prediction of Quantum Chromodynamics for the energy evolution
of the running mass. The mass measurement is equivalent to a test of the
flavour independence of the strong coupling constant with an accuracy of 7
permil.Comment: 24 pages, 10 figures, Accepted by Eur. Phys. J.
Study of Leading Hadrons in Gluon and Quark Fragmentation
The study of quark jets in e+e- reactions at LEP has demonstrated that the
hadronisation process is reproduced well by the Lund string model. However, our
understanding of gluon fragmentation is less complete. In this study enriched
quark and gluon jet samples of different purities are selected in three-jet
events from hadronic decays of the Z collected by the DELPHI experiment in the
LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are
defined by requiring a rapidity gap and their sum of charges is studied. An
excess of leading systems with total charge zero is found for gluon jets in all
cases, when compared to Monte Carlo Simulations with JETSET (with and without
Bose-Einstein correlations included) and ARIADNE. The corresponding leading
systems of quark jets do not exhibit such an excess. The influence of the gap
size and of the gluon purity on the effect is studied and a concentration of
the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is
observed, indicating that gluon jets might have an additional hitherto
undetected fragmentation mode via a two-gluon system. This could be an
indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.
Measurement and Interpretation of Fermion-Pair Production at LEP energies above the Z Resonance
This paper presents DELPHI measurements and interpretations of
cross-sections, forward-backward asymmetries, and angular distributions, for
the e+e- -> ffbar process for centre-of-mass energies above the Z resonance,
from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are
consistent with the predictions of the Standard Model and are used to study a
variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering
and several models which include physics beyond the Standard Model: the
exchange of Z' bosons, contact interactions between fermions, the exchange of
gravitons in large extra dimensions and the exchange of sneutrino in R-parity
violating supersymmetry.Comment: 79 pages, 16 figures, Accepted by Eur. Phys. J.
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