Warped and eccentric discs around black holes

Accretion discs around black holes in X-ray binary stars are warped if the spin axis of the black hole is not perpendicular to the binary orbital plane. They can also become eccentric through an instability involving a resonance with the binary orbit. Depending on the thickness of the disc and the efficiency of dissipative processes, these global deformations may be able to propagate into the innermost part of the disc in the form of stationary bending or density waves. We describe the solutions in the linear regime and discuss the conditions under which a warp or eccentricity is likely to produce significant activity in the inner region, which may include the excitation of quasi-periodic oscillations.Comment: 6 pages, 3 figures; accepted for inclusion in the proceedings of "Cool Discs, Hot Flows: The Varying Faces of Accreting Compact Objects," ed. M. Axelsson (New York: AIP

Excitation of trapped oscillations in discs around black holes

High-frequency quasi-periodic oscillations detected in the light curves of black hole candidates can, according to one model, be identified with hydrodynamic oscillations of the accretion disc. We describe a non-linear coupling mechanism, suggested by Kato, through which inertial waves trapped in the inner regions of accretion discs around black holes are excited. Global warping and/or eccentricity of the disc have a fundamental role in this coupling: they combine with trapped modes, generating negative energy waves, that are damped as they approach the inner edge of the disc or their corotation resonance. As a result of this damping, inertial oscillations are amplified. We calculate the resulting eigenfunctions and their growth rates.Comment: 6 pages, 2 figures; accepted for inclusion in the proceedings of "Cool Discs, Hot Flows: The Varying Faces of Accreting Compact Objects," ed. M. Axelsson (New York: AIP

Saluting the drum! : the new Puerto Rican Bomba movement

textDrawing upon Critical Race and racialization theories, this dissertation aims at providing a different approach to “The New Puerto Rican Bomba Movement”. Bomba is a musical genre of African roots developed in Puerto Rico upon the arrival of African populations during the slave trade in the sixteenth century. In the last two decades, a proliferation of Bomba groups and schools performing and teaching this peculiar rhythm has taken place. Through the study of Bomba, I seek to contribute to the understanding of racial dynamics in Puerto Rico, and their intersectionalities with class, gender, and national discourses. Through extended participant observation of Bomba performances, unstructured and structured interviews with Bomba musicians, teachers, and scholars and archival research, my purpose is to question and explore constructions of race in Puerto Rican music, and show how processes of racialization operate both socially and politically in the island. In this sense, Bomba will allow me to analyze how Puerto Rican national identity has been constructed in recent years, which elements have been adopted as a national heritage and which have been forgotten or rejected. At the same time, it will shed light on how national discourse aligns or deviates from current social conditions and racial relationships. Through the case study of “The New Puerto Rican Bomba Movement”, I attempt to unravel two interrelated paradoxes: (1) despite hegemonic discourses on Puerto Rican nationalism, which portray the Puerto Rican subject as mixed race, most Puerto Ricans self-identify racially as white or Black. (2) Based on the assumption of a racially mixed national subject, Puerto Rico reaffirms itself as a racial democracy, “The great Puerto Rican family”. This discourse contrasts with daily speeches and practices that emphasize racial exclusions and inequalities. Paradoxically, despite the fact that Puerto Ricans are considered a racially mixed nation, in the 2000 Census, 80.5 % self identified as white, whereas 8 % chose to identify as Black. A decade later, the results of the 2010 Census showed that 12.4 % of the population identified as Black and 75.8 % as white.Anthropolog

Genome-wide analysis identifies genetic effects on reproductive success and ongoing natural selection at the FADS locus

: Identifying genetic determinants of reproductive success may highlight mechanisms underlying fertility and identify alleles under present-day selection. Using data in 785,604 individuals of European ancestry, we identified 43 genomic loci associated with either number of children ever born (NEB) or childlessness. These loci span diverse aspects of reproductive biology, including puberty timing, age at first birth, sex hormone regulation, endometriosis and age at menopause. Missense variants in ARHGAP27 were associated with higher NEB but shorter reproductive lifespan, suggesting a trade-off at this locus between reproductive ageing and intensity. Other genes implicated by coding variants include PIK3IP1, ZFP82 and LRP4, and our results suggest a new role for the melanocortin 1 receptor (MC1R) in reproductive biology. As NEB is one component of evolutionary fitness, our identified associations indicate loci under present-day natural selection. Integration with data from historical selection scans highlighted an allele in the FADS1/2 gene locus that has been under selection for thousands of years and remains so today. Collectively, our findings demonstrate that a broad range of biological mechanisms contribute to reproductive success

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

AlgaeTraits: a trait database for (European) seaweeds

The analysis of biological and ecological traits has a long history in evolutionary and ecological research. However, trait data are often scattered and standardised terminology that transcends taxonomic and biogeographical context are generally missing. As part of the development of a global trait database of marine species, we collated trait information for European seaweeds and structured the data within the standardised framework of the World Register of Marine Species (WoRMS). We collected 45 175 trait records for 21 biologically and ecologically relevant traits of seaweeds. This resulted in a trait database for 1745 European seaweed species of which more than half (56 %) of the records were documented at the species level, while the remaining 44% were documented at a higher taxonomic level and subsequently inherited at lower levels. The trait database for European seaweeds will serve as a foundation for future research on diversity and evolution of seaweeds and their responses to global changes. The data will contribute to developing detailed trait-based ecosystem models and will be an important tool to inform marine conservation policies. The data are publicly accessible through the AlgaeTraits portal, https://doi.org/10.14284/574 (AlgaeTraits, 2022)

Novel benzo[b]thiophene derivatives as new potential antidepressants with rapid onset of action.

We report benzo[b]thiophene derivatives synthesized according to a dual strategy. 8j, 9c, and 9e with affinity values toward 5-HT(7)R and 5-HTT were selected to probe their antidepressant activity in vivo using the forced swimming text (FST). The results showed significant antidepressant activity after chronic treatment. 9c was effective in reducing the immobility time in FST even after acute treatment. These findings identify these compounds as a new class of antidepressants with a rapid onset of action

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially