189 research outputs found

    Response to ``Comment on `Primordial magnetic seed field amplification by gravitational waves' "

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    Here we respond to the comment by Tsagas (gr-qc/0503042) on our paper gr-qc/0503006. We show that the results in that comment are flawed and cannot be used for drawing conclusion about the nature of magnetic field amplification by gravitational waves, and give further support that the results of gr-qc/0503006 are correct.Comment: 4 pages, 2 figures, to appear in Physical Review

    1+1+2 Electromagnetic perturbations on non-vacuum LRS class II space-times: Decoupling scalar and 2-vector harmonic amplitudes

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    We use the covariant and gauge-invariant 1+1+2 formalism of Clarkson and Barrett \cite{Clarkson2003} to analyze electromagnetic (EM) perturbations on non-vacuum {\it locally rotationally symmetric} (LRS) class II space-times. Ultimately, we show how to derive six real decoupled equations governing the total of six EM scalar and 2-vector harmonic amplitudes. Four of these are new, and result from expanding the complex EM 2-vector which we defined in \cite{Burston2007} in terms of EM 2-vector harmonic amplitudes. We are then able to show that there are four precise combinations of the amplitudes that decouple, two of these are polar perturbations whereas the remaining two are axial. The remaining two decoupled equations are the generalized Regge-Wheeler equations which were developed previously in \cite{Betschart2004}, and these govern the two EM scalar harmonic amplitudes. However, our analysis generalizes this by including a full description and classification of energy-momentum sources, such as charges and currents.Comment: 9 page

    Genital Dysplasia and Immunosuppression: Why Organ-Specific Therapy Is Important

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    Background Young patients with Crohn's disease (CD) show a high prevalence of human papillomavirus (HPV) which is the main cause of high-grade squamous intraepithelial lesions (HSIL). A major complication for patients undergoing immunocompromising therapy is the development of genital dysplasia. Methods We report the case of a 32-year-old patient with recurrent genital dysplasia under long-term therapy for CD with a focus on different drug-related, immunosuppressive mechanisms. Results Gynecological examination and biopsy revealed high-grade vulvar intraepithelial neoplasia (VIN) positive for HPV 16 treated with laser vaporization. Due to the combination of HPV positivity, intraoperative multilocularity, and CD, follow-up examinations were performed every 6 months. One year later, the patient showed a VIN at a new location and additionally, a cervical intraepithelial neoplasia (CIN), which were surgically treated. Catch-up HPV vaccination was applied accessorily. After the switch from a TNF-α blocker to vedolizumab, which acts as a gut-selective anti-integrin, the subsequent PAP smear, vulvoscopy, and colposcopy showed no more evidence of dysplasia. Conclusions This case report highlights that gut-selective immunosuppression with vedolizumab might be favorable in young HPV-positive patients due to a good side effect profile. Regular screening and HPV vaccination are a mainstay of dysplasia prevention and control. The risk for HPV-associated dysplasia in immunosuppressed patients is highly dependent on the choice of immunosuppressive therapy

    1+1+2 Electromagnetic perturbations on general LRS space-times: Regge-Wheeler and Bardeen-Press equations

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    We use the, covariant and gauge-invariant, 1+1+2 formalism developed by Clarkson and Barrett, and develop new techniques, to decouple electromagnetic (EM) perturbations on arbitrary locally rotationally symmetric (LRS) space-times. Ultimately, we derive 3 decoupled complex equations governing 3 complex scalars. One of these is a new Regge-Wheeler (RW) equation generalized for LRS space-times, whereas the remaining two are new generalizations of the Bardeen-Press (BP) equations. This is achieved by first using linear algebra techniques to rewrite the first-order Maxwell equations in a new complex 1+1+2 form which is conducive to decoupling. This new complex system immediately yields the generalized RW equation, and furthermore, we also derive a decoupled equation governing a newly defined complex EM 2-vector. Subsequently, a further decomposition of the 1+1+2 formalism into a 1+1+1+1 formalism is developed, allowing us to decompose the complex EM 2-vector, and its governing equations, into spin-weighted scalars, giving rise to the generalized BP equations

    Histomorphological analysis of the urogenital diaphragm in elderly women: a cadaver study

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    The objective of this study was to describe the histomorphological structure of the urogenital diaphragm in elderly women using a modern morphometric procedure. Biopsies were taken from the posterior margin of the urogenital diaphragm of 22 female cadavers (mean age, 87years) using a 60-mm punch. Hematoxylin/eosin and Goldner sections were analyzed with the Cavalieri estimator. The mean thickness of the urogenital diaphragm was 5.5mm. The main component was connective tissue. All biopsies contained smooth muscle. Eighteen biopsies contained more smooth muscle than striated muscle. In six of 22 biopsies, no striated muscle was found. The ratio of striated to smooth muscle to connective tissue was 1:2.3:13.3. Muscle fibers were dispersed in all parts of the urogenital diaphragm. The urogenital diaphragm of elderly women mainly consists of connective tissue. Smooth muscle was also found but to a lesser extent. The frequently used English term "perineal membrane” for the urogenital diaphragm is justified and well describes our findings in elderly wome

    A protocol for developing, disseminating, and implementing a core outcome set (COS) for childbirth pelvic floor trauma research.

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    BACKGROUND: More than 85% of women sustain different degrees of trauma during vaginal birth. Randomized controlled trials on childbirth pelvic floor trauma have reported a wide range of outcomes and used different outcome measures. This variation restricts effective data synthesis, impairing the ability of research to inform clinical practice. The development and use of a core outcome set (COS) for childbirth pelvic floor trauma aims to ensure consistent use of outcome measures and reporting of outcomes. METHODS: An international steering group, within CHORUS, an International Collaboration for Harmonising Outcomes, Research and Standards in Urogynaecology and Women's Health, including academic community members, researchers, healthcare professionals, policy makers and women with childbirth pelvic floor trauma will lead the development of this COS. Relevant outcome parameters will be identified through comprehensive literature reviews. The selected outcomes will be entered into an international, multi-perspective online Delphi survey. Subsequently and based on the results of the Delphi surveys consensus will be sought on 'core' outcomes. DISCUSSION: Dissemination and implementation of the resulting COS within an international context will be supported and promoted. Embedding the COS for childbirth pelvic floor trauma within future clinical trials, systematic reviews, and clinical practice guidelines is expected to enrich opportunities for comparison of future clinical trials and allow better synthesis of outcomes, and will enhance mother and child care. The infrastructure created by developing a COS for childbirth pelvic floor trauma could be leveraged in other settings, for example, advancing research priorities and clinical practice guideline development

    Cosmic magnetic fields from velocity perturbations in the early Universe

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    We show, using a covariant and gauge-invariant charged multifluid perturbation scheme, that velocity perturbations of the matter-dominated dust Friedmann-Lemaitre-Robertson-Walker (FLRW) model can lead to the generation of cosmic magnetic fields. Moreover, using cosmic microwave background (CMB) constraints, it is argued that these fields can reach strengths of between 10^{-28} and 10^{-29} G at the time the dynamo mechanism sets in, making them plausible seed field candidates.Comment: 11 pages, 1 figure, IOP style, minor changes and typos correcte

    Nr. 3: Die Behandlung bei Belastungsinkontinenz

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    Sobald die Diagnose Belastungsinkontinenz gesichert ist, kann diese heute mit etablierten Behandlungsmethoden erfolgreich angegangen werden. Im Folgenden werden konservative und chirurgische Massnahmen nach heutigem Goldstandard erläutert

    Perfect magnetohydrodynamics as a field theory

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    We propose the generally covariant action for the theory of a self-coupled complex scalar field and electromagnetism which by virtue of constraints is equivalent, in the regime of long wavelengths, to perfect magnetohydrodynamics (MHD). We recover from it the Euler equation with Lorentz force, and the thermodynamic relations for a prefect fluid. The equation of state of the latter is related to the scalar field's self potential. We introduce 1+3 notation to elucidate the relation between MHD and field variables. In our approach the requirement that the scalar field be single valued leads to the quantization of a certain circulation in steps of â„Ź\hbar; this feature leads, in the classical limit, to the conservation of that circulation. The circulation is identical to that in Oron's generalization of Kelvin's circulation theorem to perfect MHD; we here characterize the new conserved helicity associated with it. We also demonstrate the existence for MHD of two Bernoulli-like theorems for each spacetime symmetry of the flow and geometry; one of these is pertinent to suitably defined potential flow. We exhibit the conserved quantities explicitly in the case that two symmetries are simultaneously present, and give examples. Also in this case we exhibit a new conserved MHD circulation distinct from Oron's, and provide an example.Comment: RevTeX, 16 pages, no figures; clarifications added and typos corrected; version to be published in Phys. Rev.
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