On a Dirichlet boundary value problem for an Ermakov-Painlevé I equation : a Hamiltonian EPI system

Here, a proto-type Ermakov–Painlevé I equation is introduced and a homogeneous Dirichlet-type boundary value problem analysed. In addition, a novel Ermakov– Painlevé I system is set down which is reducible by an involutory transformation to the autonomous Ermakov–Ray–Reid system augmented by a single component Ermakov– Painlevé I equation. Hamiltonian such systems are delimited

Tidally-driven Roche-Lobe Overflow of Hot Jupiters with MESA

Many exoplanets have now been detected in orbits with ultra-short periods, very close to the Roche limit. Building upon our previous work, we study the possibility that mass loss through Roche lobe overflow (RLO) may affect the evolution of these planets, and could possibly transform a hot Jupiter into a lower-mass planet (hot Neptune or super-Earth). We focus here on systems in which the mass loss occurs slowly ("stable mass transfer" in the language of binary star evolution) and we compute their evolution in detail with the binary evolution code MESA. We include the effects of tides, RLO, irradiation and photo-evaporation of the planet, as well as the stellar wind and magnetic braking. Our calculations all start with a hot Jupiter close to its Roche limit, in orbit around a sun-like star. The initial orbital decay and onset of RLO are driven by tidal dissipation in the star. We confirm that such a system can indeed evolve to produce lower-mass planets in orbits of a few days. The RLO phase eventually ends and, depending on the details of the mass transfer and on the planetary core mass, the orbital period can remain around a few days for several Gyr. The remnant planets have a rocky core and some amount of envelope material, which is slowly removed via photo-evaporation at nearly constant orbital period; these have properties resembling many of the observed super-Earths and sub-Neptunes. For these remnant planets we also predict an anti-correlation between mass and orbital period; very low-mass planets ($M_{\rm pl}\,\lesssim\,5\,M_{\oplus}$) in ultra-short periods ($P_{\rm orb}$<1d) cannot be produced through this type of evolution.Comment: 14 pages, 7 figures, 2 tables. Accepted by ApJ. The manuscript has been revised significantly to address the referee's comments. A link to MESA inlist files is now provided on page

On Dirichlet two-point boundary value problems for the Ermakov–Painlevé IV equation

Two-point boundary value problems of Dirichlet-type are investigated for a hybrid Ermakov-Painlev´e IV equation. Existence and uniqueness results are established in terms of the Painlev´e parameters. In addition, it is shown how Ermakov invariants may be used to systematically obtain solutions of a coupled Ermakov-Painlev´e IV system in terms of seed solutions of the canonical integrable Painlev´e IV equation.Fil: Amster, Pablo Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Rogers, Colin. University Of New South Wales; Australi

Plugging gaps in professionalism education: a resident-generated curriculum

Background: Professionalism is often taught to residents and medical students in case-based sessions using faculty-developed curriculum and faculty-led discussion. Resident-generated curriculum has been rarely published. After professional misconduct by a faculty member and reports of unprofessional conduct by residents from internal surveys of medical students, we surveyed our internal medicine residents to ask about gaps in professionalism training and optimal venues for professionalism education. Purpose: To develop case-based discussions within the morning report structure for resident-led discussion on professionalism topics that were not addressed by our standard faculty-generated curriculum. Description: A paper-based 9 item survey was distributed to residents at an attendance-required educational conference. 39 residents returned the survey. The survey revealed that a significant number of residents had engaged in less than ideal standards of professionalism at some time and that many residents had observed unprofessional behavior among attendings. Based on the results of this survey, one of the authors (RM) wrote 7 clinical cases involving ethical or professional dilemmas faced by residents that were infrequently addressed in our program. Topics addressed in these scenarios included respect for patients (specifically use of disparaging comments or labels), placing patient care needs above individual physicians needs, working through conflicts with other admitting services, providing medical care to a family member or significant other, inter-professional relationships with consulting residents, appropriate means of dealing with non-compliant patients who frequently \u27bounce,\u27 patient ownership when one resident admits a patient to another team\u27s service, appropriate use of social media, and appropriate use of cut-and-paste function in the electronic health record. All of the scenarios also discussed responding to colleagues (including faculty) who were observed to engage in the unprofessional conduct highlighted in the case. Once per month instead of our usual morning report, one resident chose one or two cases of their choice and led discussion with residents and students. Faculty were invited to attend, but the chief resident requested that their input be restricted to posing questions instead of leading discusions. Over the course of twelve months, all cases were discussed at least once. Cases discussing respect for patients and appropriate use of social media were especially popular and chosen for over 50% of the sessions. Compared to our regular ethics conferences, these sessions were better attended and had more discussion by medical students. Conclusions: Resident-led discussion of resident-generated scenarios addressed perceived gaps in professionalism education in our internal medicine training program. Respect for patients and appropriate use of social media were the most frequently discussed topics.\u2

On a Neumann Boundary Value Problem for Painlevé II in Two Ion Electro-Diffusion

A two-point Neumann boundary value problem for a two ion electro-diffusion model reducible to the Painlevé II equation is investigated. The problem is unconventional in that the model equation involves yet-to-be determined boundary values of the solution. In prior work by Thompson, the existence of a solution was established subject to an inequality on the physical parameters. Here, a two-dimensional shooting method is used to show that this restriction may be removed. A practical algorithm for the solution of the boundary value problem is presented in an appendixFil: Amster, Pablo Gustavo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemática; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Kwong, M. K.. Hong Kong Polytechnic University; ChinaFil: Rogers, C.. University Of New South Wales; Australi

A Painlevé II model in two-ion electrodiffusion with radiation boundary conditions

Existence, uniqueness, and multiplicity properties are established via a variational formulation for a Painlevé II model subject to radiation boundary conditions in two-ion electrodiffusion. Numerical experiments using an adapted shooting method are also presented to support the theoretical results.Fil: Amster, Pablo Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemática; ArgentinaFil: Kwong, Man Kam. The Hong Kong Polytechnic University; Hong KongFil: Rogers, Colin. University of New South Wales. Faculty of Science; Australi

A new species of Lynceus (Crustacea: Branchiopoda: Laevicaudata) from Patagonia, with comments on laevicaudatan systematics

Lynceus mallinensis, a new species of laevicaudatan clam shrimp is described from a single temporary pool in Chubut province, Patagonia, Argentina. The form of the male rostrum necessitates a reevaluation of rostral characters for the genus. This species differs from L. rotundirostris, the only known Lynceus from Patagonia, by the absence of a distinct umbo. L. mallinensis is the fourth species of this genus and the fifth laevicaudatan to be reported from South America. The systematical position of the Laevicaudata is discussed in the Introduction.Lynceus mallinensis, una nueva especie de Laevicaudata, es descrita a partir de material recolectado en un mallín temporal en la provincia de Chubut, Patagonia, Argentina. Esta especie difiere de L. rotundirostris, la única especie descrita en Patagonia, por la ausencia de umbo. L. mallinensis es la cuarta especie del género y el quinto Laevicaudata registrado en América del Sur.Fil: Pessacq, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia; ArgentinaFil: Epele, Luis Beltran. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia; ArgentinaFil: Rogers, D. Christopher. University of Kansas; Estados Unido

Graph algorithms for machine learning: a case-control study based on prostate cancer populations and high throughput transcriptomic data

Background The continuing proliferation of high-throughput biological data promises to revolutionize personalized medicine. Confirming the presence or absence of disease is an important goal. In this study, we seek to identify genes, gene products and biological pathways that are crucial to human health, with prostate cancer chosen as the target disease. Materials and methods Using case-control transcriptomic data, we devise a graph theoretical toolkit for this task. It employs both innovative algorithms and novel two-way correlations to pinpoint putative biomarkers that classify unknown samples as cancerous or normal. Results and conclusion Observed accuracy on real data suggests that we are able to achieve sensitivity of 92% and specificity of 91%

Sovereign Rating, Macroeconomic Indicators and Firm Performance: Evidence from Latin America

macroeconomic indicators and the performance of non-financial listed companies based in five Latin America emerging countries, from 2010 to 2017. Using a sample of 1,424 non-financial listed firms, the authors employed a panel data regression. The Chow, Breusch-Pagan and Hausman tests confirmed the fixed effects hypothesis. Return on asset, return on equity and Tobin’s Q were used to measure firm performance. The evidence points that the sovereign rating quality increases return on assets and the market value of Latin American firms. Financial leverage, as well as gross domestic product, interest and inflation rates positively affect company performance, while corporate tax significantly decrease return on asset and Tobin’ Q. The study found significant differences of the effects of sovereign rating, gross domestic product and corporate tax between the performance of companies based in Brazil and their pairs based in Argentina, Chile, Colombia and Mexico. The study provides empirical evidence on the implications of the sovereign rating and macroeconomic policies on companies’ performance in Latin America, considering that few studies address these macroeconomic aspects in the corporate finance field. The empirical evidence has implications related to macroeconomic policies, as well as the consequences of the rating agencies report on managerial decisions Keywords: Sovereign Rating, Macroeconomic Indicators, Leverage, Performance, Latin America. DOI: 10.7176/RHSS/11-8-06 Publication date: April 30th 202

Spatial optical phase-modulating metadevice with subwavelength pixelation

Dynamic control over optical wavefronts enables focusing, diffraction and redirection of light on demand, however, sub-wavelength resolution is required to avoid unwanted diffracted beams that are present in commercial spatial light modulators. Here we propose a realistic metadevice that dynamically controls the optical phase of reflected beams with sub-wavelength pixelation in one dimension. Based on reconfigurable metamaterials and nanomembrane technology, it consists of individually moveable metallic nanowire actuators that control the phase of reflected light by modulating the optical path length. We demonstrate that the metadevice can provide on-demand optical wavefront shaping functionalities of diffraction gratings, beam splitters, phase-gradient metasurfaces, cylindrical mirrors and mirror arrays — with variable focal distance and numerical aperture — without unwanted diffraction