1,405 research outputs found
Primary umbilical endometriosis:a cause of a painful umbilical nodule
A female patient presented with a painful swelling in the umbilicus. Ultrasonography demonstrated a hypodense nodule of 1.8 cm. Surgical exploration revealed a subcutaneous, dark discoloured, lobulated swelling at the bottom of the umbilicus, which turned out to be primary umbilical endometriosis (PUE). Primary umbilical endometriosis is a rare and benign disorder, caused by the presence of ectopic endometrial tissue in the umbilicus, which can present as a painful, discoloured swelling in the umbilicus. The clinical distinction between primary umbilical endometrioses and other causes of an umbilical nodule is difficult. Additional imaging modalities do not show any pathognomonic signs for establishing this diagnose. Surgical exploration and excision are a safe and definitive treatment of primary umbilical endometrioses. This case highlights the importance of including PUE in the differential diagnosis of women with a painful umbilical nodule
Vortex lattices in strong type-II superconducting two-dimensional strips
We show how to calculate semi-analytically the dense vortex state in strong
type-II superconducting nanostructures. For the specific case of a strip, we
find vortex lattice solutions which also incorporate surface superconductivity.
We calculate the energy cost to displace individual vortex rows parallel to the
surfaces and find that this energy oscillates with the magnetic field.
Remarkably, we also find that, at a critical field below , this
''shear'' energy becomes strictly zero for the surface rows due to an
unexpected mismatch with the bulk lattice.Comment: Title, abstract, and some text paragraphs have been rewritte
Evolution of communication signals and information during species radiation
Communicating species identity is a key component of many animal signals. However, whether selection for species recognition systematically increases signal diversity during clade radiation remains debated. Here we show that in woodpecker drumming, a rhythmic signal used during mating and territorial defense, the amount of species identity information encoded remained stable during woodpeckers’ radiation. Acoustic analyses and evolutionary reconstructions show interchange among six main drumming types despite strong phylogenetic contingencies, suggesting evolutionary tinkering of drumming structure within a constrained acoustic space. Playback experiments and quantification of species discriminability demonstrate sufficient signal differentiation to support species recognition in local communities. Finally, we only find character displacement in the rare cases where sympatric species are also closely related. Overall, our results illustrate how historical contingencies and ecological interactions can promote conservatism in signals during a clade radiation without impairing the effectiveness of information transfer relevant to inter-specific discrimination
Vortex Motion Noise in Micrometre-Sized Thin Films of the Amorphous Nb0.7Ge0.3 Weak-Pinning Superconductor
We report high-resolution measurements of voltage (V) noise in the mixed
state of micrometre-sized thin films of amorphous Nb0.7Ge0.3, which is a good
representative of weak-pinning superconductors. There is a remarkable
difference between the noise below and above the irreversibility field Birr.
Below Birr, in the presence of measurable pinning, the noise at small applied
currents resembles shot noise, and in the regime of flux flow at larger
currents decreases with increasing voltage due to a progressive ordering of the
vortex motion. At magnetic fields B between Birr and the upper critical field
Bc2 flux flow is present already at vanishingly small currents. In this regime
the noise scales with (1-B/Bc2)^2 V^2 and has a frequency (f) spectrum of 1/f
type. We interpret this noise in terms of the properties of strongly driven
depinned vortex systems at high vortex density.Comment: 8 pages, 5 figures, version accepted for publication in PR
Current preconception care practice in the Netherlands — An evaluation study among birth care professionals
Objective: To evaluate the current practice of preconception care in the Netherlands and the perceptions of birth care professionals concerning preconception care. Methods: We have developed a digital questionnaire and conducted a cross-sectional study by distributing the questionnaire among 102 organisations: 90 primary care midwifery practices and obstetric departments of 12 hospitals in the Southwest region of the Netherlands between December 2020 and March 2021. One birth care professional per organization was asked to complete the questionnaire. Descriptive statistics were used to present the results. Findings: Respondents of eighty-three organisations (81.4 %) filled in the questionnaire, of whom 74 respondents were independent primary care midwives and 9 respondents were obstetricians. Preconception care mostly consisted of an individual consultation in which personalized health and lifestyle advice was given. Among the respondents, 44.4 % reported that the organization had a preconception care protocol. The way in which the consultation was carried out, as well as the health and lifestyle related questions asked, differed between respondents. More than 85 % of the respondents inquire about the following possible risk factors for complications: maternal illnesses, obstetric history, folic acid supplement intake, alcohol intake, smoking, substance abuse, hereditary disease, prescription medication, dietary habits, overweight, and birth defects in the family. The respondents acknowledged that preconception care should be offered to all couples who wish to become pregnant, as opposed to offering preconception care only to those with an increased risk of complications. Still, respondents do not receive many questions regarding the preconception period or requests for preconception care consultations. Key conclusion: Birth care professionals acknowledge the need for preconception care for all couples. In the Netherlands, preconception care consists mostly of an individual consultation with recommendations for health and lifestyle advice. However, the identification of risk factors varies between birth care professionals and less than half of the respondents indicate that they have a protocol available in their practice. Furthermore, the demand of parents-to-be for preconception care is low. More research, that includes more obstetricians, is necessary to investigate if there is a difference between the care provided by primary care midwives and obstetricians. Implications for practice:To increase the awareness and uptake of preconception care, it would be prudent to emphasize its importance to parents-to-be and professionals, and actively promote the use of widespread, standardized protocols for birth care professionals.</p
Ion-channeling analysis of boron clusters in silicon
We have measured axially channeled Rutherford backscattering spectra of Si1-xGex nanofilms in silicon(001). A step in the yield of the host crystal was found for off-normal axes at the depth of the nanofilm. The step was measured as a function of the angle between the incoming beam and the [011] axis and shows two maxima. It is found that Monte Carlo simulations assuming tetragonal distortion reproduce the experimental results. A universal curve was derived which enables determination of the tetragonal distortion from ion-channeling experiments, for a given film thickness. The results are compared with XRD measurements
Erratum: “Ion-channeling analysis of boron clusters in silicon” [J. Appl. Phys. 90, 4741 (2001)]
Melting of two dimensional solids on disordered substrate
We study 2D solids with weak substrate disorder, using Coulomb gas
renormalisation. The melting transition is found to be replaced by a sharp
crossover between a high liquid with thermally induced dislocations, and a
low glassy regime with disorder induced dislocations at scales larger than
which we compute (, the Larkin and
translational correlation lengths). We discuss experimental consequences,
reminiscent of melting, such as size effects in vortex flow and AC response in
superconducting films.Comment: 4 pages, uses RevTeX, Amssymb, multicol,eps
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