An analytical model of radial dust trapping in protoplanetary disks

We study dust concentration in axisymmetric gas rings in protoplanetary disks. Given the gas surface density, we derived an analytical total dust surface density by taking into account the differential concentration of all the grain sizes. This model allows us to predict the local dust-to-gas mass ratio and the slope of the particle size distribution, as a function of radius. We test this analytical model comparing it with a 3D magneto-hydrodynamical simulation of dust evolution in an accretion disk. The model is also applied to the disk around HD 169142. By fitting the disk continuum observations simultaneously at $\lambda = 0.87$, 1.3, 3.0 mm, we obtain a global dust-to-gas mass ratio $\epsilon_{\rm global} = 1.05 \times 10^{-2}$ and a viscosity coefficient $\alpha = 1.35 \times 10^{-2}$. This model can be easily implemented in numerical simulations of accretion disks

The role of environmental accounting in organizational change: An exploration of Spanish companies

Critique originated by earlier theorization of environmental accounting, as a way of building environmentalist visibility of business, led Gray et al., to study environmental accounting in the dynamics of organizational change. They concluded that environmental accounting is being used to ``negotiate the conception of the environment'' by companies that have not significantly changed. In order to investigate whether Gray et al.'s model and conclusions apply to a different cultural context, we have conducted nine case studies in Spain. We found that Spanish organizations are not truly changing their conventional perception of the environment, even in those cases where generalized structural and organizational changes are taking place. Moreover, the use of environmental accounting is coupled with an attempt to negotiate and control the environmental agenda

Oxidoperoxidomolybdenum(VI) complexes with acylpyrazolonate ligands: synthesis, structure and catalytic properties

Oxidoperoxido–molybdenum(VI) complexes containing acylpyrazolonate ligands were obtained by reaction of [Mo(O)(O)2(H2O)n] with the corresponding acylpyrazolone compounds HQR. Complexes Ph4P[Mo(O)(O2)2(QR)] (R = neopentyl, 1; perfluoroethyl, 2; hexyl, 3; phenyl, 4; naphthyl, 5; methyl, 6; cyclohexyl, 7; ethylcyclopentyl, 8) were obtained if the reaction was carried out with one equivalent of HQR in the presence of Ph4PCl. Alternatively, neutral complexes [Mo(O)(O2)(QR)2] (R = neopentyl, 9; hexyl, 10; cyclohexyl, 11) were formed when two equivalents of HQR were used in the reaction. These complexes were isolated in good yields as yellow or yellow-orange crystalline solids and were spectroscopically (IR, 1H, 13C{1H} and 31P{1H} NMR), theoretically (DFT) and structurally characterised (X-ray for 1, 2, 9 and 10). Compounds 1 and 9 were selected to investigate their catalytic behaviour in epoxidation of selected alkenes and oxidation of selected sulphides, while 10 and 11 were tested as catalyst precursors in the deoxygenation of selected epoxide substrates to alkenes, using PPh3 as the oxygen-acceptor. Complexes Ph4P[Mo(O)(O2)2(QR)] were shown to be poor catalyst precursors in oxidation reactions, while the activity of [Mo(O)(O2)(QR)2] species is good in all the studied reactions and comparable to related oxidoperoxido–molybdenum(VI) complexes. Complex [Mo(O)2(QC6)2], 12, was obtained by treatment of 10 with one equivalent of PPh3, demonstrating that the first step in the epoxide deoxygenation mechanism was the oxygen atom transfer toward the phosphane.Junta de Andalucía (Proyecto de Excelencia, FQM-7079)Universidad de Sevilla (VI Plan Propio

Informe sobre avances en la informatización del Archivo Rubén Darío (www.ucm.es/info/rdario)

This brief text offers information on the progress that has been made in the computerisation of the nearly five thousand documents of the Archive Rubén Darío. It presents the Archive’s web page, comments some of the difficulties that have been faced, offers technical details on the computerisation and an index of the Archive’s contents so as to enable researchers to travel through the web page.Este breve texto ofrece información sobre los avances que se han hecho en la informatización de los casi cinco mil documentos del Archivo Rubén Darío. Presenta la página web del Archivo, comenta las dificultades experimentadas en la labor de informatización, ofrece detalles técnicos sobre la digitalización y transcribe un índice de los contenidos del Archivo para facilitar la labor del investigador

Grain-size measurements in protoplanetary disks indicate fragile pebbles and low turbulence

Recent laboratory experiments have revealed that destructive collisions of icy dust particles may occur at much lower velocities than previously believed. These low fragmentation velocities push down the maximum grain size in collisional growth models. Motivated by the smooth radial distribution of pebble sizes inferred from ALMA/VLA multi-wavelength continuum analysis, we propose a concise model to explain this feature and aim to constrain the turbulence level at the midplane of protoplanetary disks. Our approach is built on the assumption that the fragmentation threshold is the primary barrier limiting pebble growth within pressure maxima. Consequently, the grain size at the ring location can provide direct insights into the turbulent velocity governing pebble collisions and, by extension, the turbulence level at the disk midplane. We validate this method using the Dustpy code, which simulates dust transport and coagulation. We apply our method to 7 disks, TW Hya, IM Lup, GM Aur, AS 209, HL Tau, HD 163296, and MWC 480, for which grain sizes have been measured from multi-wavelength continuum analysis. A common feature emerges from our analysis, with an overall low turbulence coefficient of $\alpha\sim10^{-4}$ observed in five out of seven disks when taking fragmentation velocity $v_{\rm frag} = 1{\rm \,m\,s}^{-1}$. A higher fragmentation velocity would imply a turbulence coefficient significantly larger than the current observational constraints. IM Lup stands out with a relatively higher coefficient of $10^{-3}$. Notably, HL Tau exhibits an increasing trend in $\alpha$ with distance, which supports enhanced turbulence at its outer disk region, possibly associated with the infalling streamer onto HL~Tau. The current (sub)mm pebble size constrained in disks implies low levels of turbulence, as well as fragile pebbles consistent with recent laboratory measurements.Comment: 11 pages, 8 figures, 2 tables, Accepted for publication in A&

La violencia de género en la agenda del Parlamento español (1979-2004)

ResumenObjetivosDescribir sistemáticamente las características de los procesos de formulación y toma de decisiones vinculadas al poder legislativo del Estado español en materia de violencia de género.MétodosBúsqueda y análisis de contenido cuantitativo de todas las iniciativas parlamentarias del Congreso de los Diputados y del Senado sobre violencia de género (1979-2004). Se calculó la razón entre las iniciativas de violencia de género y las iniciativas de otros temas por años y legislaturas. Se analizó la probabilidad de presentar iniciativas sobre violencia de género por sexo y según pertenencia al gobierno u oposición (odds ratio [OR], intervalo de confianza [IC] del 95% y significación estadística [método Mantel-Haenszel]).ResultadosEn 26 años se produjeron 322.187 iniciativas parlamentarias, de las que 569 fueron sobre violencia de género. Destacan las tasas de iniciativas de 1998 (4,12 por 1.000), 2001 (4,49 por 1.000) y 2004 (9,19 por 1.000). El 67% fueron preguntas al gobierno. La mayoría fueron tramitadas sin acuerdo o decisión (81%). Los hombres presentaron mayor probabilidad de incluir preguntas en sus iniciativas (OR=17,08; IC del 95%, 5,91-55,62), pero las mujeres promovieron el 60% de las iniciativas sobre el tema. La probabilidad de preguntar fue mayor entre los miembros del gobierno (OR=2,63; IC del 95%, 1,32-5,31), aunque la oposición lideró el 88% de las iniciativas.ConclusionesEn España, se ha producido una incipiente construcción política de la violencia de género que puede llevar al desarrollo de verdaderas estrategias. La actividad parlamentaria sobre el tema debería mantenerse a largo plazo, puesto que el problema persiste.AbstractAimsTo systematically examine the characteristics of the processes of formulating and taking decisions on gender-based violence in the Spanish Parliament.MethodsA search was performed for all parliamentary initiatives on gender-based violence in the Spanish parliament (1979-2004) and their qualitative content was analyzed. The ratio between initiatives on gender-based violence and those on other issues was calculated by years and legislatures. The probability of presenting initiatives on gender-based violence was analyzed by sex and political group (government vs. opposition) (odds ratio, 95% CI and statistical significance using the Mantel-Haenszel method).ResultsIn the 26 years studied, there were 322,187 initiatives, of which 569 concerned gender-based violence. Initiatives on this issue increased in 1998 (4.12 per 1,000), 2001 (4.49 per 1,000) and 2004 (9.19 per 1,000). Sixty-seven percent were questions to the government. The majority of the initiatives were registered without agreement or decision (81%). Men had a higher probability of asking questions (OR=17.08; 95%CI, 5.91-55.62), but women instigated 60% of the initiatives. Parliamentary groups in government showed a higher probability of asking questions (OR=2.63; 95%CI, 1.32-5.31), but 88% of the initiatives were promoted by the opposition.ConclusionsThe process of policy construction has been started in Spain, which could lead to the development of true policies on gender-based violence in the future. Parliamentary activity on this issue should be maintained in the longterm, as the problem shows no sign of abating