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

Comportamiento de la variedad Nu OPAL (Gossypium hirsutum L.) bajo diferentes arreglos espaciales

This research was carried out to determine the spatial arrangement with higher yield potential field of Nu Opal cotton variety under the agroecological conditions of the middle Sinu Valley. Were evaluated six different population densities from the variation of the distances among rows (from 1,0; 0,9; 0,8; 0,7; 0,6 to 0,5 m) and setting two plants per meter. These were compared with the density of population used by farmers in the producing area (62.500 plants ha-1). Treatments were arranged in a design of a randomized complete block (RCBD) with four replications. Planting was carried out in the experimental station Turipaná CORPOICA CI in the second half of 2006. The results showed that the spatial arrangements used did not affect neither the expression of plant height and flowering, nor the components of fiber quality. In contrast, significant differences (P<0,05) for the number of buttons and field performance were encountered. The highest yield of cotton-seed and fiber was shown for the control treatment to 5370,7 and 2028,3 kg ha-1 respectively. Notably, the treatment of 40,000 plants ha-1 had similar yields to the control with 5137,4 kg ha-1 of cotton-seed and 1986,7 kg ha-1 of fiber, having numerical but not statistical difference (P>< 0,05) for the number of buttons and field performance were encountered. The highest yield of cotton-seed and fiber was shown for the control treatment to 5370,7 and 2028,3 kg ha-1 respectively. Notably, the treatment of 40,000 plants ha-1 had similar yields to the control with 5137,4 kg ha-1 of cotton-seed and 1986,7 kg ha-1 of fiber, having numerical but not statistical difference (P>0,05) between them.Esta investigación se realizó con el objetivo de determinar el arreglo espacial con mayor potencial de rendimiento de campo de la variedad de algodón Nu Opal bajo las condiciones agroecológicas del Valle del Sinú Medio. Se evaluaron seis densidades de población a partir de la variación de las distancias entre surcos (desde 1,0; 0,9; 0,8; 0,7; 0,6 y 0,5 m) y fijando dos plantas por metro. Estas fueron comparadas con la densidad de población utilizada por los agricultores (62.500 plantas ha-1). Los tratamientos fueron dispuestos en un diseño de bloques completos al azar (DBCA) con cuatro repeticiones. La siembra experimental se realizó en el centro experimental CORPOICA CI Turipaná en el segundo semestre del año 2006. Los resultados resaltan que los arreglos espaciales utilizados no afectaron  la altura de planta, floración ni los componentes de calidad de la fibra. En cambio, se encontraron diferencias significativas (P<0,05) para el número de botones y el rendimiento de campo.  El mayor rendimiento de algodón-semilla y fibra fue mostrado por el tratamiento testigo con 5.370,7 kg ha-1 y 2.028,3 kg ha-1, respectivamente. Cabe destacar que el tratamiento de 40.000 plantas.ha-1 presentó rendimientos similares con 5.137,4 kg ha-1 de algodón-semilla y 1.986,7 kg ha-1 de fibra, habiendo diferencia numérica pero no estadística (P>0,05) entre ello

Porous Dust Particles in Protoplanetary Disks: Application to the HL Tau Disk

Dust particle sizes constrained from dust continuum and polarization observations by radio interferometry are inconsistent by at least an order of magnitude. Motivated by porous dust observed in small Solar System bodies (e.g., from the Rosetta mission), we explore how the dust particle's porosity affects the estimated particle sizes from these two methods. Porous particles have lower refractive indices, which affect both opacity and polarization fraction. With weaker Mie interference patterns, the porous particles have lower opacity at mm wavelengths than the compact particles if the particle size exceeds several hundred microns. Consequently, the inferred dust mass using porous particles can be up to a factor of six higher. The most significant difference between compact and porous particles is their scattering properties. The porous particles have a wider range of particle sizes with high linear polarization from dust self-scattering, allowing mm-cm-sized particles to explain polarization observations. With a Bayesian approach, we use porous particles to fit HL Tau disk's multi-wavelength continuum and mm-polarization observations from ALMA and VLA. The moderately porous particles with sizes from 1 mm-1 m can explain both continuum and polarization observations, especially in the region between 20-60 au. If the particles in HL Tau are porous, the porosity should be from 70% to 97% from current polarization observations. We also predict that future observations of the self-scattering linear polarization at longer wavelengths (e.g., ALMA B1 and ngVLA) have the potential to further constrain the particle's porosity and size.Comment: 39 pages, 18 figures, 1 table, accepted to be published in The Astrophysical Journa

Compactifications of the Klebanov-Witten CFT and new AdS 3 backgrounds

In this paper we find various new backgrounds in Type IIB, IIA and M-theory with an $AdS_3$-factor. The solutions are smooth and preserve small amounts of SUSY. These new backgrounds are found by application of non-Abelian T-duality (sometimes combined with T-duality) on the supergravity solution dual to the Klebanov-Witten CFT compactified to two dimensions. The field theory aspects encoded by these backgrounds are studied. We give a detailed account of conserved charges, central charges, entanglement entropy and Wilson loops. Further, we present a possible field theory interpretation for our backgrounds.Comment: 38 pages plus appendices, 6 figure

The Radial Distribution of Dust Particles in the HL Tau Disk from ALMA and VLA Observations

Understanding planet formation requires one to discern how dust grows in protoplanetary disks. An important parameter to measure in disks is the maximum dust grain size present. This is usually estimated through measurements of the dust opacity at different millimeter wavelengths assuming optically thin emission and dust opacity dominated by absorption. However, Atacama Large Millimeter/submillimeter Array (ALMA) observations have shown that these assumptions might not be correct in the case of protoplanetary disks, leading to overestimation of particle sizes and to underestimation of the disk\u27s mass. Here, we present an analysis of high-quality ALMA and Very Large Array images of the HL Tau protoplanetary disk, covering a wide range of wavelengths, from 0.8 mm to 1 cm, and with a physical resolution of ~7.35 au. We describe a procedure to analyze a set of millimeter images without any assumption about the optical depth of the emission, and including the effects of absorption and scattering in the dust opacity. This procedure allows us to obtain the dust temperature, the dust surface density, and the maximum particle size at each radius. In the HL Tau disk, we found that particles have already grown to a few millimeters in size. We detect differences in the dust properties between dark and bright rings, with dark rings containing low dust density and small dust particles. Different features in the HL Tau disk seem to have different origins. Planet–disk interactions can explain substructure in the external half of the disk, but the internal rings seem to be associated with the presence of snow lines of several molecules

Fulguraçao endocavitária com choques elétricos de alta energia na taquicardia ventricular incessante

A taquicardia ventricular incessante, definida como aquela com duraçao superior a 24 horas, freqüência acima de 120 sístoles por minuto, refratária à cardioversao elétrica e aos antiarrítmicos disponíveis, é uma arritmia rara e grave, que pode culminar com a morte, se nao for tratada agressivamente. Sao mostrados os resultados imediatos e evoluçao clínica de 6 pacientes portadores deste distúrbio, com idade média de 57 anos, sendo 5 do sexo masculino, tratados por fulguraçao endocavitária com choques elétricos de alta energia. Em 3, havia miocardiopatia chagásica crônica; os demais apresentavam infarto do miocárdio cicatrizado, sendo um deles com artérias coronárias normais. A taquicardia ventricular teve duraçao média de 9,8 dias, refratária à lidocaína, procainamida, propafenona, amiodarona, difenil-hidantoína, potássio e magnésio, administrados por via venosa e a cardioversoes elétricas (92 tentativas) ou estimulaçao artificial endocavitária. O mapeamento eletrofisiológico localizou a origem da taquicardia, nas seguintes regioes: inferior do ventrículo esquerdo, em 3; ínfero-apical do ventrículo esquerdo, em 2; ínfero-lateral do ventrículo esquerdo, em 1. Foram aplicados 2 choques em cada paciente, com intensidade que variou entre 100 e 300J (média de 195,8J). Em 2 casos, foi necessária uma nova sessao de ablaçao, sendo aplicados 4 choques (entre 200 e 300J). Houve reversao da arritmia em todos, sem complicaçoes. Um dos pacientes faleceu 6 meses após o procedimento, por complicaçoes d

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection