Changes in the mean echogenicity and area of the puborectalis muscle during pregnancy and postpartum

INTRODUCTION AND HYPOTHESIS: Three-dimensional (3D) and four-dimensional (4D) volume transperineal ultrasound imaging is increasingly used to assess changes in the dimensions of the pelvic floor during pregnancy and after delivery. Little is known with regard to the area of the puborectalis muscle and its structural changes. Echogenicity measurement, a parameter that provides information on the structure of muscles, is increasingly used in orthopaedics and neuromuscular disease evaluation. This study is aimed at assessing the changes in the mean echogenicity of the puborectalis muscle (MEP) and the puborectalis muscle area (PMA) during first pregnancy and after childbirth. METHODS: The MEP and PMA of 254 women during first pregnancy were measured at 12 and 36 weeks’ gestation and 6 months postpartum. To determine the effect of child-birth on MEP and PMA, the results at 6 months postpartum were separately analysed for vaginal deliveries, operative vaginal deliveries (ventouse) and caesarean section deliveries. Mean differences in MEP and PMA were analysed using ANOVA statistics. RESULTS: The MEP at 6 months postpartum was, independent of manoeuvre, significantly (p < 0.001) lower than MEP values during pregnancy. After caesarean delivery, the PMA was significantly smaller at maximum pelvic floor contraction than PMA after vaginal delivery (p = 0.003) or operative vaginal delivery (p = 0.002). CONCLUSION: Our study indicates that structural changes in the puborectalis muscle during and after pregnancy, as measured by MEP, occur and can be analysed. In addition, the mode of delivery affects the area of the puborectalis during contraction after delivery. For true volume analysis, as part of an assessment of contractility of the puborectalis muscle we will need 3D volume analysis

Measuring echogenicity and area of the puborectalis muscle:method and reliability

OBJECTIVES: To develop a semi-automated method to assess puborectalis muscle echogenicity on three-dimensional/four-dimensional (3D/4D) volume transperineal ultrasound images using 4D View and Matlab® software and evaluate its intra- and interobserver reliability. METHOD: The data of 23 women in their first trimester were included. 3D/4D volume datasets were obtained at rest. Two inexperienced observers were trained by an experienced observer to construct tomographic ultrasound images (TUI) from the original data and to delineate all structures. Puborectalis muscle area (PMA) and the mean echogenicity of the puborectalis muscle (MEP) were calculated offline. Intra- and interobserver reliability were determined by intraclass correlation coefficients (ICC) and their 95% CIs. RESULTS: The development of a semi-automated method to calculate puborectalis area and echogenicity is described in detail. PMA and MEP measurements in pregnant women demonstrated almost perfect intraobserver reliability for both inexperienced observers, with ICC values ranging from 0.88 to 0.99. The interobserver reliability showed ICCs of 0.63 for PMA and almost perfect ICC values, of 0.96-0.98, for echogenicity. The majority of intraobserver mismatch between two delineations of PMA occurred near the borders. CONCLUSIONS: Matlab software can be used to provide reliable measurements of the area and echogenicity of the puborectalis muscle. As the latter can be used to assess structural changes in the puborectalis muscle, it appears a promising new tool for studying pelvic floor structural anatomy

Method and reliability of measuring midurethral area and echogenicity, and changes during and after pregnancy

INTRODUCTION AND HYPOTHESIS: Internal closure of the urethral sphincter is one of the mechanisms in maintaining continence. Little is known about changes in the urethral sphincter during pregnancy. We designed this study to develop a reliable method to measure the area and mean echogenicity of the midurethra during and after pregnancy and to assess changes over time. METHODS: Two observers independently segmented the urethra as follows: in the sagittal plane, the urethra was positioned vertically, the marker was placed in the middle section of the lumen of the urethra, and eight tomographic US images of 2.5 -mm slices were obtained. The central image was selected, and area and mean echogenicity were calculated automatically. Intra- and interobserver reliability were determined by intraclass correlation coefficients (ICC) and their 95% confidence intervals (CI). Two hundred and eighty women underwent TPUS at 12 weeks and 36 weeks of gestation and 6 months postpartum, and 3D/4D transperineal ultrasound (TPUS) images of 40 pregnant nulliparous women were used for the reliability study. Paired t tests were used to assess changes in echogenicity and area. RESULTS: The ICC for measuring the area was substantial, at 0.77 and for measuring mean echogenicity was almost perfect, at 0.86. In the total study group (n = 280), midurethral area and mean echogenicity were significantly lower 6 months after delivery compared with 12 and 36 weeks of gestation. CONCLUSIONS: Our protocol for measuring area and mean echogenicity of the midurethra is reliable. This study indicates that structural changes in the midurethraoccur during pregnancy

Quantum Chi-Squared and Goodness of Fit Testing

The density matrix in quantum mechanics parameterizes the statistical properties of the system under observation, just like a classical probability distribution does for classical systems. The expectation value of observables cannot be measured directly, it can only be approximated by applying classical statistical methods to the frequencies by which certain measurement outcomes (clicks) are obtained. In this paper, we make a detailed study of the statistical fluctuations obtained during an experiment in which a hypothesis is tested, i.e. the hypothesis that a certain setup produces a given quantum state. Although the classical and quantum problem are very much related to each other, the quantum problem is much richer due to the additional optimization over the measurement basis. Just as in the case of classical hypothesis testing, the confidence in quantum hypothesis testing scales exponentially in the number of copies. In this paper, we will argue 1) that the physically relevant data of quantum experiments is only contained in the frequencies of the measurement outcomes, and that the statistical fluctuations of the experiment are essential, so that the correct formulation of the conclusions of a quantum experiment should be given in terms of hypothesis tests, 2) that the (classical) $\chi^2$ test for distinguishing two quantum states gives rise to the quantum $\chi^2$ divergence when optimized over the measurement basis, 3) present a max-min characterization for the optimal measurement basis for quantum goodness of fit testing, find the quantum measurement which leads both to the maximal Pitman and Bahadur efficiency, and determine the associated divergence rates.Comment: 22 Pages, with a new section on parameter estimatio

Hysterectomy Does Not Cause Constipation

PURPOSE: This study was designed to evaluate the risk on development and persistence of constipation after hysterectomy. METHODS: We conducted a prospective, observational, multicenter study with three-year follow-up in 13 teaching and nonteaching hospitals in the Netherlands. A total of 413 females who underwent hysterectomy for benign disease other than symptomatic uterine prolapse were included. All patients underwent vaginal hysterectomy, subtotal abdominal hysterectomy, or total abdominal hysterectomy. A validated disease-specific quality-of-life questionnaire was completed before and three years after surgery to assess the presence of constipation. RESULTS: Of the 413 included patients, 344 (83 percent) responded at three-year follow-up. Constipation had developed in 7 of 309 patients (2 percent) without constipation before surgery and persisted in 16 of 35 patients (46 percent) with constipation before surgery. Preservation of the cervix seemed to be associated with an increased risk of the development of constipation (relative risk, 6.6; 95 percent confidence interval, 1.3-33.3; P=0.02). Statistically significant risk factors for the persistence of constipation could not be identified. CONCLUSIONS: Hysterectomy does not seem to cause constipation. In nearly half of the patients reporting constipation before hysterectomy, this symptom will disappear

Corrections to the universal behavior of the Coulomb-blockade peak splitting for quantum dots separated by a finite barrier

Building upon earlier work on the relation between the dimensionless interdot channel conductance g and the fractional Coulomb-blockade peak splitting f for two electrostatically equivalent dots, we calculate the leading correction that results from an interdot tunneling barrier that is not a delta-function but, rather, has a finite height V and a nonzero width xi and can be approximated as parabolic near its peak. We develop a new treatment of the problem for g much less than 1 that starts from the single-particle eigenstates for the full coupled-dot system. The finiteness of the barrier leads to a small upward shift of the f-versus-g curve at small values of g. The shift is a consequence of the fact that the tunneling matrix elements vary exponentially with the energies of the states connected. Therefore, when g is small, it can pay to tunnel to intermediate states with single-particle energies above the barrier height V. The correction to the zero-width behavior does not affect agreement with recent experimental results but may be important in future experiments.Comment: Title changed from ``Non-universal...'' to ``Corrections to the universal...'' No other changes. 10 pages, 1 RevTeX file with 2 postscript figures included using eps

Минералогические исследования в пещерной системе Снежная-Меженного-Иллюзия (Западный Кавказ, Бзыбский хребет): предварительные результаты и направления дальнейших работ

В статье приводятся сведения о минеральном составе водных хемогенных и водных механических отложений в пещерной системе Снежная-Меженного-Иллюзия. В состав водных хемогенных отложений входят Mg- и Sr-содержащий кальцит, арагонит, гипс, гидромагнезит, целестин, стронцианит, доломит, гетит, рутил и циркон. Водные механические отложения сложены преимущественно доломитом, кварцем и кальцитом. В схожих по морфологии и микроклимату частях пещерной системы наблюдаются одинаковые вторичные минералы.У статті наводяться відомості про мінеральний склад водних хемогенних і водних механічних відкладень в печерній системі Сніжна-Меженого-Ілюзія. До складу водних хемогенних відкладень входять кальцит, який містить Mg і Sr, арагоніт, гіпс, гідромагнезіт, целестин, стронціаніт, доломіт, гетит, рутил і циркон. Водні механічні відкладення складені переважно доломітом, кварцом і кальцитом. У схожих за морфологєю та мікрокліматом частинах печерної системи спостерігаються однакові вторинні мінерали.The article presents the preliminary characteristic of the mineral composition of chemogenic formations and clastic deposits of Snezhnaya-Mezhennogo-Illusia cave system. Chemogenic formations are composed by Mg- and Sr-calcite, aragonite, gypsum and hydromagnesite, celestite, strontianite, dolomite, goethite, rutile and zircon. Clastic sediments are composed mainly by dolomite, quartz and calcite. Same secondary minerals are observed in those parts of the cave system that have similar morphology and microclimate

Correlated charge polarization in a chain of coupled quantum dots

Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of $e/2$.Comment: 9 pages, 3 figures, 1 tabl

Coulomb effects in tunneling through a quantum dot stack

Tunneling through two vertically coupled quantum dots is studied by means of a Pauli master equation model. The observation of double peaks in the current-voltage characteristic in a recent experiment is analyzed in terms of the tunnel coupling between the quantum dots and the coupling to the contacts. Different regimes for the emitter chemical potential indicating different peak scenarios in the tunneling current are discussed in detail. We show by comparison with a density matrix approach that the interplay of coherent and incoherent effects in the stationary current can be fully described by this approach.Comment: 6 pages, 6 figure