Gravitating discs around black holes

Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole--disc system by analytical solutions of stationary, axially symmetric Einstein's equations. Then, more detailed considerations are focused to middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring, however, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging and completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the environment around. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star--disc interactions, which can be recognised in observational properties, such as the relation between the central mass and stellar velocity dispersion.Comment: Accepted for publication in CQG; high-resolution figures will be available from http://www.iop.org/EJ/journal/CQ

The Cultural and Financial Dynamics of Female Entrepreneurs as Well as Their Empowering Ventures

This research examines how female entrepreneurs in Bangladesh navigate the cultural, social, and financial challenges of F-commerce, where informal digital platforms like Facebook and Instagram have become vital spaces for women-led businesses. In addition, despite the growth of digital entrepreneurship, existing models such as the gendered growth framework and ‘TOCOM contingency model’ often overlook how localized cultural dynamics shape women’s entrepreneurial experiences. To bridge this gap, this research explores how these dynamics influence not only the constraints female entrepreneurs face, but also the motivations and resilience strategies that drive their success. However, grounded in ‘Consumer Culture Theory’ and enriched by anthropological perspectives, this research uses a qualitative approach, featuring instrumental case studies and in-depth interviews. The analysis, conducted through NVivo coding, captures both the lived realities and the strategic digital engagements of these women. Although the outcome is a proposed conceptual framework that links culture, motivation, and F-commerce participation offering insight into how female entrepreneurs adapt, persist, and redefine their roles in the digital economy. Therefore, this research also outlines practical recommendations to enhance digital inclusion and gender equity through skills training, mentorship, as well as policy support

Design, Analysis and Testing of a Novel Mitral Valve for Transcatheter Implantation

Mitral regurgitation is a common mitral valve dysfunction which may lead to heart failure. Because of the rapid aging of the population, conventional surgical repair and replacement of the pathological valve are often unsuitable for about half of symptomatic patients, who are judged high-risk. Transcatheter valve implantation could represent an effective solution. However, currently available aortic valve devices are inapt for the mitral position. This paper presents the design, development and hydrodynamic assessment of a novel bi-leaflet mitral valve suitable for transcatheter implantation. The device consists of two leaflets and a sealing component made from bovine pericardium, supported by a self-expanding wireframe made from superelastic NiTi alloy. A parametric design procedure based on numerical simulations was implemented to identify design parameters providing acceptable stress levels and maximum coaptation area for the leaflets. The wireframe was designed to host the leaflets and was optimised numerically to minimise the stresses for crimping in an 8 mm sheath for percutaneous delivery. Prototypes were built and their hydrodynamic performances were tested on a cardiac pulse duplicator, in compliance with the ISO5840-3:2013 standard. The numerical results and hydrodynamic tests show the feasibility of the device to be adopted as a transcatheter valve implant for treating mitral regurgitation

Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB

Excited-state spectroscopy from the first Facility for Rare Isotope Beams (FRIB) experiment is reported. A 24(2)-$\mu$s isomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keV $\gamma$ rays in coincidence with $^{32}\textrm{Na}$ nuclei. This is the only known microsecond isomer ($1{\text{ }\mu\text{s}}\leq T_{1/2} < 1\text{ ms}$) in the region. This nucleus is at the heart of the $N=20$ island of shape inversion and is at the crossroads of spherical shell-model, deformed shell-model, and ab initio theories. It can be represented as the coupling of a proton hole and neutron particle to $^{32}\textrm{Mg}$, $^{32}\textrm{Mg}+\pi^{-1} + \nu^{+1}$. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of $^{32}\textrm{Mg}$, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformed $2^+$ state at 885 keV and a low-lying shape-coexisting $0_2^+$ state at 1058 keV. We suggest two possible explanations for the 625-keV isomer in $^{32}$Na: a $6^-$ spherical shape isomer that decays by $E2$ or a $0^+$ deformed spin isomer that decays by $M2$. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.Comment: 7 pages, 5 figures, accepted by Physical Review Letter

Characterizing domain-specific open educational resources by linking ISCB Communities of Special Interest to Wikipedia

Wikipedia is one of the most important channels for the public communication of science and is frequently accessed as an educational resource in computational biology. Joint efforts between the International Society for Computational Biology (ISCB) and the Computational Biology taskforce of WikiProject Molecular Biology (a group of expert Wikipedia editors) have considerably improved computational biology representation on Wikipedia in recent years. However, there is still an urgent need for further improvement in quality, especially when compared to related scientific fields such as genetics and medicine. Facilitating involvement of members from ISCB Communities of Special Interest (COSIs) would improve a vital open education resource in computational biology, additionally allowing COSIs to provide a quality educational resource highly specific to their subfield.We generate a list of around 1500 English Wikipedia articles relating to computational biology and describe the development of a binary COSI-Article matrix, linking COSIs to relevant articles and thereby defining domain-specific open educational resources. Our analysis of the COSI-Article matrix data provides a quantitative assessment of computational biology representation on Wikipedia against other fields and at a COSI-specific level. Furthermore, we conducted similarity analysis and subsequent clustering of COSI-Article data to provide insight into potential relationships between COSIs. Finally, based on our analysis, we suggest courses of action to improve the quality of computational biology representation on Wikipedia

Hydatid cysts in muscles: clinical manifestations, diagnosis, and management of this atypical presentation

ABSTRACTINTRODUCTION: Hydatid cysts are rarely detected in muscle tissue (0.7-0.9%), even in endemic countries. The aim of this study was to present information regarding the clinical manifestations, diagnosis, and management of muscle echinococcosis.METHODS: Twenty-two patients with hydatid cysts in the muscle were followed from January 2006 through December 2014.RESULTS: Twenty-four sites of muscle involvement were observed in the 22 patients. Fifteen (68%) of our patients were women, while seven (32%) were men. The mean age was 28.1 ± 15.4 (6-61) years. The most frequent locations were the thigh (27.2%) and the paravertebral region (13.6%). Most patients reported a painless slow-growing mass with normal overlying skin. Most (90.2%) cases were treated by surgical excision and fine-needle aspiration.CONCLUSIONS: Primary muscle hydatid cyst should be considered in the differential diagnosis in cystic masses of the muscular system without pain and localized enlargement of soft tissue, especially in endemic areas. Hydatid cyst should be investigated using serological tests and imaging modalities. If possible, total surgical excision of hydatid cyst in the muscle should be performed

Esophageal and Gastric Malignancies After Bariatric Surgery: a Retrospective Global Study

Background: Bariatric surgery can influence the presentation, diagnosis, and management of gastrointestinal cancers. Esophagogastric (EG) malignancies in patients who have had a prior bariatric procedure have not been fully characterized. Objective: To characterize EG malignancies after bariatric procedures. Setting: University Hospital, United Kingdom. Methods: We performed a retrospective, multicenter observational study of patients with EG malignancies after bariatric surgery to characterize this condition. Results: This study includes 170 patients from 75 centers in 25 countries who underwent bariatric procedures between 1985 and 2020. At the time of the bariatric procedure, the mean age was 50.2 ± 10 years, and the mean weight 128.8 ± 28.9 kg. Women composed 57.3% (n = 98) of the population. Most (n = 64) patients underwent a Roux-en-Y gastric bypass (RYGB) followed by adjustable gastric band (AGB; n = 46) and sleeve gastrectomy (SG; n = 43). Time to cancer diagnosis after bariatric surgery was 9.5 ± 7.4 years, and mean weight at diagnosis was 87.4 ± 21.9 kg. The time lag was 5.9 ± 4.1 years after SG compared to 9.4 ± 7.1 years after RYGB and 10.5 ± 5.7 years after AGB. One third of patients presented with metastatic disease. The majority of tumors were adenocarcinoma (82.9%). Approximately 1 in 5 patients underwent palliative treatment from the outset. Time from diagnosis to mortality was under 1 year for most patients who died over the intervening period. Conclusion: The Oesophago-Gastric Malignancies After Obesity/Bariatric Surgery study presents the largest series to date of patients developing EG malignancies after bariatric surgery and attempts to characterize this condition.info:eu-repo/semantics/publishedVersio

Emissão de metano por decomposição de resíduo florestal inundado

A construção de represas pode aumentar a emissão de gases do efeito estufa (GEE), principalmente metano (CH4) pela decomposição anaeróbica dos resíduos florestais, como galhos, ramos, folhas e miscelânea inundados. Objetivou-se, neste estudo, avaliar a emissão de CH4 após a inundação do solo coberto com resíduos florestais. Unidades experimentais foram construídas com tubos de PVC contendo solo e diferentes combinações de dose (0; 21,2; 42,3 e 64,1 Mg ha-1) e tipo de resíduos (folhas, ramos e miscelânea, galhos e composição original) e água de rio. O delineamento experimental foi inteiramente casualizado com arranjo fatorial e três repetições. As taxas de emissão de CH4 foram monitoradas em 19 eventos durante um ano (Fevereiro/2012 a Março/2013). Cerca de 75 dias após a incubação do solo com resíduos florestais verificou-se aumento das emissões de CH4, ocorrendo dois picos de emissão, aos 111 e aos 249 dias. A emissão acumulada de CH4 no primeiro ano de alagamento foi de 200 g C m-2 na dose zero, passando a valores próximos a 400 g C m-2 nas doses de 21,2 Mg ha-1 e maiores, não havendo efeito do tipo de resíduo, apenas da dose, como fator isolado

Comparison of the results of fixation of reverse-oblique intertrochanteric and short-segment subtrochanteric fractures using dynamic hip screw (DHS) and dynamic condylar screw (DCS)

Background: In intertrochanteric fractures, dynamic hip screw (DHS) is the most frequently used tool, but several studies did not give good results for this device in reverse-oblique and transverse fractures. Current study aimed to compare fixation results of reverse-oblique intertrochanteric and short-segment subtrochanteric fractures using dynamic condylar screw (DCS) and DHS in patients referred to Alzahra and Kashani Hospitals in Isfahan, Iran. Methods: In a cross-sectional study, medical files of the patients referred to emergency units of the two hospitals who were diagnosed with intertrochanteric or subtrochanteric fractures and underwent DHS or DCS surgery more than 6 months before were assessed; they were invited for follow-up visit and examination. Written consent forms were taken from all the patients upon their entry; and they were examined in terms of complications including nonunion and failure of device and level of fracture improvement. These cases were evaluated by simple radiography, too. Results obtained from examination of patients in addition to demographic information were recorded in the data collection form for each patient. Findings: Perfect union was observed in 14 (of 25) patients in DHS group and 21 (of 25) patients in DCS group (56 vs. 84) six months after the surgery. Bone union was significantly better in DCS group (P = 0.031). In addition, six months after the surgery, the devices used in 14 people in DHS group and 24 people in DCS group were fixed and the difference between the two groups was significant (P = 0.001). 14 and 24 patients had total recovery in DHS and DCS groups, respectively (20 vs. 44) with a significant difference (P = 0.020). Conclusion: Considering obtained results, it can be concluded that using DCS is recommended over DHS due to severity of pain, bone union and fixation of the device. © 2016, Isfahan University of Medical Sciences(IUMS). All rights reserved