Tracing planet-induced structures in circumstellar disks using molecular lines

Circumstellar disks are considered to be the birthplace of planets. Specific structures like spiral arms, gaps, and cavities are characteristic indicators of planet-disk interaction. Investigating these structures can provide insights into the growth of protoplanets and the physical properties of the disk. We investigate the feasibility of using molecular lines to trace planet-induced structures in circumstellar disks. Based on 3D hydrodynamic simulations of planet-disk interactions, we perform self-consistent temperature calculations and produce N-LTE molecular line velocity-channel maps and spectra of these disks using our new N-LTE line radiative transfer code Mol3D. Subsequently, we simulate ALMA observations using the CASA simulator. We consider two nearly face-on inclinations, 5 disk masses, 7 disk radii, and 2 different typical pre-main-sequence host stars (T Tauri, Herbig Ae). We calculate up to 141 individual velocity-channel maps for five molecules/isotopoloques in a total of 32 rotational transitions to investigate the frequency dependence of the structures indicated above. We find that the majority of protoplanetary disks in our parameter space could be detected in the molecular lines considered. However, unlike the continuum case, gap detection is not straightforward in lines. For example, gaps are not seen in symmetric rings but are masked by the pattern caused by the global (Keplerian) velocity field. We identify specific regions in the velocity-channel maps that are characteristic of planet-induced structures. Simulations of high angular resolution molecular line observations demonstrate the potential of ALMA to provide complementary information about the planet-disk interaction as compared to continuum observations. In particular, the detection of planet-induced gaps is possible under certain conditions.(abridged)Comment: 19 pages, 19 figures, accepted for publication in A&

La revista Miscel·lània Zoològica: apuntes para su historia

In a little over four decades the journal Miscel·lània Zoològica published some 900 papers. A simple review of the contents of these articles reveals several characteristics: the issues most commonly dealt with were faunistics and taxonomy, with insects making up the most frequently analyzed group. The geographical range was centred on the Iberian peninsula, mainly Catalonia. The intellectual heritage of Miscel·lània Zoològica has been continued since 2001 by the journal Animal Biodiversity and Conservation and by Arxius de Miscel·lània Zoològica as of this current volume. It is now time to start writing the history of Miscel·lània Zoològica.Durante más de cuatro décadas la revista Miscel·lània Zoològica ha publicado cerca de 900 artículos. Una simple revisión de los contenidos de estos artículos revela algunas características. La faunística y la taxonomía fueron las temáticas más tratadas y los insectos el grupo zoológico más estudiado. El ámbito geográfico se ha centrado en la península Ibérica, principalmente Cataluña. La herencia intelectual de Miscel·lània Zoològica la han recogido la revista Animal Biodiversity and Conservation, desde el año 2001, y Arxius de Miscel·lània Zoològica, a partir del presente volumen. Ha llegado el momento de empezar a escribir la historia de Miscel·lània Zoològica

Burnett Description for Plane Poiseuille Flow

Two recent works have shown that at small Knudsen number ~K! the pressure and temperature profiles in plane Poiseuille flow exhibit a different qualitative behavior from the profiles obtained by the Navier-Stokes equations. Tij and Santos [J. Stat. Phys. 76, 1399 (1994)] used the Bhatnagar-Gross-Kook model to show that the temperature profile is bimodal and the pressure profile is nonconstant. Malek-Mansour, Baras, and Garcia [Physica A 240, 255 (1997)] qualitatively confirmed these predictions in computer experiments using the direct simulation Monte Carlo method (DSMC). In this paper we compare the DSMC measurements of hydrodynamic variables and non-equilibrium fluxes with numerical solutions of the Burnett equations. Given that they are in better agreement with molecular-dynamics simulations [E. Salomons and M. Mareschal, Phys. Rev. Lett. 69, 269 (1992)] of strong shock waves than Navier-Stokes [F. J. Uribe, R. M. Velasco, and L. S. Garcı´a-Colı´n, Phys. Rev. Lett. 81, 2044 (1998)], and that they are second order in Knudsen number suggests that the Burnett equations may provide a better description for large K. We find that for plane Poiseuille flow the Burnett equations do not predict the bimodal temperature profile but do recover many of the other anomalous features

Corruption and entrepreneurship: A bibliometric analysis

The impact of corruption on entrepreneurial dynamics became an attractive topic for scholars after the appearance of public scandals that led to the delegitimization of many governments in the last 40 years. The research that explored the relationship between corruption and entrepreneurship has produced controversial results. It appears that the interaction of these two constructs is influenced by contextual factors both at an individual and national level of analysis. By using a bibliometric methodology and a fractional counting method to analyse the scientific literature on corruption and entrepreneurship, this paper identifies and analyses 180 articles recorded in the Scopus database. It represents a contribution by showing the state of the art of research on corruption and entrepreneurship and proposes future lines of research. Important results have been found about the evolution of the volume of articles and citations on this topic over time. Significant academic interest in this field commenced in the 21st century, and more specifically in the last ten years. This work also provides findings about the most prolific journals, institutions and authors, as well as the most relevant countries, with the United States and United Kingdom leading in terms of the number of publications. In addition, an in-depth analysis of authors' keywords has identified different trends, such as institutions, economic growth, shadow economy, regulation, Africa, culture, economic development, business environment, and informal economy. Finally, some future research lines are proposed, such as institutional theory, tax morale, corruption perceptions, European regions, risk aversion and institutional entrepreneurship

Retos y oportunidades de los ambientes de geometría dinámicos

A raíz de una experiencia didáctica de cuatro profesores en un curso acerca del uso de tecnologías digitales en la clase de matemáticas, se produjo una reflexión de los retos y oportunidades que ofrecen los ambientes de geometría dinámicos (AGD) para la enseñanza de la geometría