Exceptional Gegenbauer polynomials via isospectral deformation

In this paper, we show how to construct exceptional orthogonal polynomials (XOP) using isospectral deformations of classical orthogonal polynomials. The construction is based on confluent Darboux transformations, where repeated factorizations at the same eigenvalue are allowed. These factorizations allow us to construct Sturm–Liouville problems with polynomial eigenfunctions that have an arbitrary number of realvalued parameters. We illustrate this new construction by exhibiting the class of deformed Gegenbauer polynomials, which are XOP families that are isospectral deformations of classical Gegenbauer polynomials.Spanish MINECO through Juan de la Cierva fellowship FJC2019-039681-I, Spanish State Research Agency through BCAM Severo Ochoa excellence accreditation SEV-2017-0718, Basque Government through the BERC Programme 2022-2025, projects PGC2018-096504-B-C33 and RTI2018-100754-B-I00 from FEDER/Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion, the European Union under the 2014-2020 ERDF Operational Programme, and the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (project FEDER-UCA18-108393

Exceptional Gegenbauer polynomials via isospectral deformation

In this paper, we show how to construct exceptional orthogonal polynomials (XOP) using isospectral deformations of classical orthogonal polynomials. The construction is based on confluent Darboux transformations, where repeated factorizations at the same eigenvalue are allowed. These factorizations allow us to construct Sturm-Liouville problems with polynomial eigenfunctions that have an arbitrary number of realvalued parameters. We illustrate this new construction by exhibiting the class of deformed Gegenbauer polynomials, which are XOP families that are isospectral deformations of classical Gegenbauer polynomials

D3-branes wrapped on a spindle

We construct supersymmetric $AdS_3\times \Sigma$ solutions of minimal gauged supergravity in $D=5$, where $\Sigma$ is a two-dimensional orbifold known as a spindle. Remarkably, these uplift on $S^5$, or more generally on any regular Sasaki-Einstein manifold, to smooth solutions of type IIB supergravity. The solutions are dual to $d=2$, $\mathcal{N}=(0,2)$ SCFTs and we show that the central charge for the gravity solution agrees with a field theory calculation associated with D3-branes wrapped on $\Sigma$. Unlike for smooth $\Sigma$ the superconformal R-symmetry mixes with the $U(1)$ isometry of the spindle.Comment: 6 pages. Minor changes. Matches published versio

A neuronal network of mitochondrial dynamics regulates metastasis.

The role of mitochondria in cancer is controversial. Using a genome-wide shRNA screen, we now show that tumours reprogram a network of mitochondrial dynamics operative in neurons, including syntaphilin (SNPH), kinesin KIF5B and GTPase Miro1/2 to localize mitochondria to the cortical cytoskeleton and power the membrane machinery of cell movements. When expressed in tumours, SNPH inhibits the speed and distance travelled by individual mitochondria, suppresses organelle dynamics, and blocks chemotaxis and metastasis, in vivo. Tumour progression in humans is associated with downregulation or loss of SNPH, which correlates with shortened patient survival, increased mitochondrial trafficking to the cortical cytoskeleton, greater membrane dynamics and heightened cell invasion. Therefore, a SNPH network regulates metastatic competence and may provide a therapeutic target in cancer

On the muon neutrino mass

During the runs of the PS 179 experiment at LEAR of CERN, we photographed an event of antiproton-Ne absorption, with a complete pi+ -> mu+ ->e+ chain. From the vertex of the reaction a very slow energy pi+ was emitted. The pi+ decays into a mu+ and subsequently the mu+ decays into a positron. At the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino. Measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass: m_nu < 2.2 MeV at a 90% confidence level. A statistical analysis has been performed of the factors contributing to the square value of the neutrino mass limit.Comment: 18 pages, 5 eps figure

Gender differences of fatigue in the workplace for surgeons

Purpose Previous literature identifies increased burnout in female surgeons and contributors to fatigue outside of work. However, it is not yet understood whether there are gender discrepancies of contributors to fatigue or coping mechanisms for workplace fatigue in surgeons. This study aims to identify gender differences in causes of fatigue, how fatigue occurs and any interventions/strategies that surgeons may use/know to try and mitigate the effects of fatigue. Methods Using an online questionnaire at a single hospital in England, the questionnaire asked whether surgeons had been subject to any contributors to fatigue at work and what contributes to their fatigue at work using a list of multiple-choice answers. Results 97% of surgeons suffer from at least one contributor to fatigue. Females were statistically more likely to suffer from musculoskeletal injuries at work than males and more likely to suffer from mental exhaustion. Females were significantly more likely to contribute fatigue to prolonged static postures, lack of control during the shift and high levels of demand. To mitigate fatigue, females were significantly more likely to change positions whilst operating. Males were less reluctant to adopt Microbreaks during surgery to reduce musculoskeletal fatigue. Conclusions Our analysis identifies gender differences with coping mechanisms and the onset of fatigue. There is still a stigma attached to workplace fatigue in surgeons. Acknowledgement of these gender differences in fatigue is critical to reducing the statistical likelihood of fatigue onset in both genders. Further research should identify whether surgical operating rooms are adequately suitable for females. </jats:sec

Quantitative prediction of stone fragility from routine single and dual energy CT: proof of feasibility

Rationale and Objectives Previous studies have demonstrated a qualitative relationship between stone fragility and internal stone morphology. The goal of this study was to quantify morphological features from dual-energy CT images and assess their relationship to stone fragility. Materials and Methods Thirty-three calcified urinary stones were scanned with micro CT. Next, they were placed within torso-shaped water phantoms and scanned with the dual-energy CT stone composition protocol in routine use at our institution. Mixed low-and high-energy images were used to measure volume, surface roughness, and 12 metrics describing internal morphology for each stone. The ratios of low- to high-energy CT numbers were also measured. Subsequent to imaging, stone fragility was measured by disintegrating each stone in a controlled ex vivo experiment using an ultrasonic lithotripter and recording the time to comminution. A multivariable linear regression model was developed to predict time to comminution. Results The average stone volume was 300 mm3 (range 134–674 mm3). The average comminution time measured ex vivo was 32 s (range 7–115 s). Stone volume, dual-energy CT number ratio and surface roughness were found to have the best combined predictive ability to estimate comminution time (adjusted R2= 0.58). The predictive ability of mixed dual-energy CT images, without use of the dual-energy CT number ratio, to estimate comminution time was slightly inferior, with an adjusted R2 of 0.54. Conclusion Dual-energy CT number ratios, volume, and morphological metrics may provide a method for predicting stone fragility, as measured by time to comminution from ultrasonic lithotripsy