Misaligned gas discs around eccentric black-hole binaries and implications for the final-parsec problem

We investigate the evolution of low mass (Md /Mb = 0.005) misaligned gaseous discs around eccentric supermassive black hole (SMBH) binaries. These are expected to form from randomly oriented accretion events onto a SMBH binary formed in a galaxy merger. When expanding the interaction terms between the binary and a circular ring to quadrupole order and averaging over the binary orbit, we expect four non-precessing disc orientations: aligned or counter-aligned with the binary, or polar orbits around the binary eccentricity vector with either sense of rotation. All other orientations precess around either of these, with the polar precession dominating for high eccentricity. These expectations are borne out by smoothed particle hydrodynamics simulations of initially misaligned viscous circumbinary discs, resulting in the formation of polar rings around highly eccentric binaries in contrast to the co-planar discs around circular binaries. Moreover, we observe disc tearing and violent interactions between differentially precessing rings in the disc significantly disrupting the disc structure and causing gas to fall onto the binary with little angular momentum. While accretion from a polar disc may not promote SMBH binary coalescence (solving the `final-parsec problem'), ejection of this infalling low-angular momentum material via gravitational slingshot is a possible mechanism to reduce the binary separation. Moreover, this process acts on dynamical rather than viscous time scales, and so is much faster.Comment: 12 pages, 9 figures, Accepted for publication in MNRA

A family of potential-density pairs for galactic bars

We present a family of analytical potential-density pairs for barred discs, which can be combined to describe galactic bars in a realistic way, including boxy/peanut components. We illustrate this with two reasonable compound models. Computer code for the evaluation of potential, forces, density, and projected density is freely provided.Comment: 10 pages, accepted for publication at MNRA

The efficacy of ultrasonographic morphological index using Depriest score in ovarian cancer prediction

Background: Ovarian cancer is the second most common cancer after cancer breast and the most lethal gynecologic malignancy in developed countries.The objective of this study was to evaluate the efficacy of ultrasonographic morphological index using Depriest score et al in identifying ovarian cancer and to calculate its specificity, sensitivity, positive predictive value and negative predictive value in ovarian cancer prediction.Methods: Preoperative estimation of morphological index by Depriest score using vaginal ultrasound examination for 130 cases with ovarian masses, followed by laparotomy, and histopathological examination of the masses. Correlation of the cases morphological index score was done for histopathological nature of masses whether it is benign or malignant. Calculation of the Depriest index score was done using 3 parameters which are tumor volume, cyst wall structure and thickness and Septal structure.Results: A significant difference were found between mean Depriest score (p=0.001) of malignant cases (mean score 8.27±1.77) and benign cases (mean score 4.38±1.61) while the mean volume showed no significant difference (p=0.101) between malignant (mean volume 3.24±0.69) and benign cases (mean volume 3.00±0.91). In relation to CA125 there was a significant difference (p=0.001) between malignant (mean CA125 86.34±73.87) and benign cases (mean CA125 31.48±12.83).Conclusions: Depriest et al morphological index is an effective and cost efficient method for malignant ovarian masses prediction and differentiation from benign masses

Comparison between Pap smear and visual inspection with acetic acid in screening of premalignant cervical intraepithelial lesion and subclinical early cancer cervix

Background: The objective of the study was to compare the sensitivity, specificity, positive predictive value and negative predictive value of VIA and Pap smear in screening of premalignant cervical intraepithelial lesion and subclinical early cancer cervix.Methods: An observational prospective study was done for 350 patients attending the gynecology outpatient clinic of the shatby maternity university hospital for any reasons, VIA and Pap test were done for all patients, then colposcopic guided biopsy from cases with positive colposcopic findings. Histopathological examination was done for collected biopsy. Collected data was statistically analyzed to compare between both tests (PAP and VIA).Results: Our results showed that the sensitivity of PAP test was 83.3%, specificity was 90.7%, positive predictive value was 50.8%, negative predictive value was 97.9% and accuracy was 90% while the VIA test had a sensitivity of 66.7%, specificity was 91%, positive predictive value was 46.1%, negative predictive value was 95.9% and accuracy was 88.5%.Conclusions: Via test has comparable results to Pap test regarding its sensitivity, specificity, positive predictive value, negative predictive value and accuracy and can be used as an alternative primary test to screen premalignant cervical intraepithelial lesion and subclinical early cancer cervix

WInDI: a Warp-Induced Dust Instability in protoplanetary discs

We identify a new dust instability that occurs in warped discs. The instability is caused by the oscillatory gas motions induced by the warp in the bending wave regime. We first demonstrate the instability using a local 1D (vertical) toy model based on the warped shearing box coordinates and investigate the effects of the warp magnitude and dust Stokes number on the growth of the instability. We then run 3D SPH simulations and show that the instability is manifested globally by producing unique dust structures that do not correspond to gas pressure maxima. The 1D and SPH analysis suggest that the instability grows on dynamical timescales and hence is potentially significant for planet formation.Comment: Accepted for publication in MNRAS, 13 pages, 10 figure