Vasektomie heute

Dahm, Franz-Josef; Dahm, P.; Dahm, Johannes

doi:10.1007/s00120-003-0301-z

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…where t=T/T c , ν=hf/∆, δ = ∆(0)/kT c and R res is the residual resistance. Fig.9 shows that the experimental data can be nicely fitted by (6), with ∆(0) fixed to ∆ π (0) and with only three free parameters left (solid line). Attempts to get a good fit by setting ∆(0) to ∆ σ (0) or to ∆*(0) did not lead to reasonable results (dashed and dotted lines, respectively).…”

Section: Effective Gapmentioning

confidence: 90%

“…They deduced this argument from the observation of a single anomalous peak around t=T/T c =0. 6. The presence of such a peak can be explained in the framework of the BCS theory.…”

Section: Introductionmentioning

confidence: 97%

“…When the superconducting state is entered and the gap opens, a singularity appears in the density of states at the gap edges, increasing the microwave conductivity. 6 When the gap becomes larger than k B T, upon lowering the temperature, quasiparticles condense and microwave conductivity is suppressed. The peak at t=0.6 is consistent with a small gap.…”

Section: Introductionmentioning

confidence: 99%

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Effective gap at microwave frequencies inMgB2thin films with strong interband scattering

et al. 2005

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The microwave properties of polycrystalline MgB 2 thin films prepared by the so-called in-situ method are investigated. The characterization of the films at microwave frequencies was obtained by a coplanar resonator technique. The analysis of the experimental data results in the determination of penetration depth, surface impedance and complex conductivity. The aim of this work is to set the experimental results in a consistent framework, involving the two-band model in the presence of impurity scattering. The energy gaps are calculated and the contribution of intra-and inter-band scattering is considered. From the comparison between the calculated gap values and the experimental data it turns out that the temperature dependence of the penetration depth 1 can be accounted for by an effective mean energy gap, in agreement with the predictions of Kogan et al. [Phys. Rev. B 69, 132506 (2004)]. On the other hand, the temperature dependence of the real part of the microwave conductivity and of the surface resistance is accounted for by the single smaller gap, in agreement with the work of Jin et al. [Phys. Rev. Lett. 91, 127006 (2003)]. Since these findings rely on the same calculated gap structure, the required consistency is fulfilled.74.70. Ad, 74.25.Nf IntroductionSince the discovery of its superconducting properties, magnesium diboride (MgB 2 ) has generated a great deal of interest because of its simple structure, relatively high critical temperature and two-gap nature. The Fermi surface of MgB 2 consists of two threedimensional sheets, from the π bonding and antibonding bands, and two nearly cilindrical sheets from the two-dimensional σ bands. 1 Many physical properties of MgB 2 are reasonably described within a model with two separated energy gaps, ∆ π and ∆ σ . 2,3 Nevertheless, the role of interband and intraband scattering has to be considered: 2,3 it is still not completely clear, also due to the wide spread quality of samples used in different experiments. In fact, a significant scattering between the different Fermi sheets may reduce the effective gap structure to a single isotropic gap. Recently, the expected 2 observation of single-gap superconductivity at high impurity level has been observed in C-substituted MgB 2 single crystals by point-contact spectroscopy. 4 When the level of impurities is high enough, the two gaps merge into a single gap with a ratio 2∆/k B T c close to the standard BCS value.The role of the two bands in determining the microwave conductivity in MgB 2 thin films is controversial as well. The temperature dependence of the microwave conductivity in caxis oriented films was interpreted by Jin et al. 5 in terms of a dominant contribution of the π band. They deduced this argument from the observation of a single anomalous peak around t=T/T c =0.6. The presence of such a peak can be explained in the framework of the BCS theory. When the superconducting state is entered and the gap opens, a singularity appears in the density of states at the gap edges, increasing the microwave ...

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Section: Effective Gapmentioning

confidence: 90%

“…They deduced this argument from the observation of a single anomalous peak around t=T/T c =0. 6. The presence of such a peak can be explained in the framework of the BCS theory.…”

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effective gap at microwave frequencies inMgB2thin films with strong interband scattering

et al. 2005

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“…It is still unclear whether this T c maximum is an intrinsic HTS property since the synthesis of higher-n members of the HTS families turns out to be more and more complicated [107,108,109,110]. In particular, there is at present no preparation technique that alllows to adjust here a sufficiently high oxygen content 21 or to provide otherwise sufficient electronic doping that would allow to clarify the possible range of T c optimization for higher n HTS A-m2(n-1)n 22 [107,110]. Hence the question is still open if such an optimized T c may eventually continue to increase towards higher n, possibly up to T c ~ 200 K as can be estimated for optimized infinite-layer HTS based on model-independent theoretical considerations extrapolating from T c (n = 1) ~ 100 K of Hg-1201 [121].…”

Section: Structure and T Cmentioning

confidence: 96%

“…As for the fullerides, in spite of the high T c a phononic mechanism is highly plausible: Strong Coulomb correlation effects are not expected since the conduction electron system does neither involve inner atomic shells nor a reduction of the effective dimensionality. Nevertheless, new theoretical ingredients are required for a satisfactory explanation of the experiments [21].…”

Section: Introductionmentioning

confidence: 99%

Superconducting Materials — A Topical Overview

Hott¹,

Kleiner

Wolf³

et al.

Frontiers in Superconducting Materials

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Ischämische Hodennekrose nach Vasektomie

Rolfes

Lümmen

2011

Urologe

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Taking the clinical case of a patient who developed unilateral testicular necrosis following vasectomy as a starting point, the early and late complications of this procedure are described based on a literature review.In the USA 7% of all men undergo vasectomy, as compared to 2% in Germany. Early postoperative complications include bleeding/hematoma (0.5-18%), infection (0.3-32.9%), epididymitis (0.4-6.1%), granuloma (0.07-90%), and rare complications such as vas deferens abscess, vesicular gland abscess, vasovenous fistula, testicular necrosis, arteriovenous fistula, pulmonary embolism, endocarditis, scrotal skin necrosis and Fournier's disease which mostly have been reported in the form of case reports. Late complications are chronic pain (0.5-18%), pain during sex (2.9%), hydrocele (0-4%) as well as spermatocele (1.6%). There is a failure rate of 4.3-16% as concluded from the number of patients with nonmotile sperm in the post-vasectomy semen analysis. The postoperative paternity rate is 0-4%.Bilateral vasectomy is a secure way of contraception; perioperative and late complications are on an average rare, however, with a range up to 90%. In individual cases severe complications occur, which should be detected at an early stage. Therefore a close follow-up should be maintained after this outpatient procedure. One should ask for risk factors of endocarditis or thrombosis preoperatively. The patient should be informed of the possible loss of a testicle because of the severity of this complication. Postoperative semen analysis is obligatory.

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Vasektomie heute

Cited by 6 publications

References 8 publications

Effective gap at microwave frequencies inMgB2thin films with strong interband scattering

Effective gap at microwave frequencies inMgB2thin films with strong interband scattering

Superconducting Materials — A Topical Overview

Ischämische Hodennekrose nach Vasektomie

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