Size Matters to Lesbians,Too: Queer Feminist Interventions into the Scale of Big Data

How can we recognize those whose lives and data become attached to the far-from-groundbreaking framework of “small data”? Specifically, how can marginalized people who do not have the resources to produce, self-categorize, analyze, or store “big data” claim their place in the big data debates? I examine the place of lesbians and queer women in the big data debates through the Lesbian Herstory Archive's not “big” enough lesbian, gay, bisexual, trans, and queer (LGBTQ) organizing history data set—perhaps the largest data set known to exist on LGBTQ activist history—as one such alternative. In a contribution to critical data studies, I take a queer feminist approach to the scale of big data by reading for the imbricated scales and situated knowledge of data.     

An embedded fracture modeling framework for simulation of hydraulic fracturing and shear stimulation

A numerical modeling framework is described that is able to calculate the coupled processes of fluid flow, geomechanics, and rock failure for application to general engineering problems related to reservoir stimulation, including hydraulic fracturing and shear stimulation. The numerical formulation employs the use of an embedded fracture modeling approach, which provides several advantages over more traditional methods in terms of computational complexity and efficiency. Specifically, the embedded fracture modeling strategy avoids the usual requirement that the discretization of the fracture domain conforms to the discretization of the rock volume surrounding the fractures. As fluid is exchanged between the two domains, conservation of mass is guaranteed through a coupling term that appears as a simple source term in the governing mass balance equations. In this manner, as new tensile fractures nucleate and propagate subject to mechanical effects, numerical complexities associated with the introduction of new fracture control volumes are largely negated. In addition, the ability to discretize the fractures and surrounding rock volume independently provides the freedom to choose an acceptable level of discretization for each domain separately. Three numerical examples were performed to demonstrate the utility of the embedded fracture model for application to problems involving fluid flow, mechanical deformation, and rock failure. The results of the numerical examples confirm that the embedded fracture model was able to capture accurately the complex and nonlinear evolution of reservoir permeability as new fractures propagate through the reservoir and as fractures fail in shear.     

Orbital stability of systems of closely-spaced planets,II: configurations with coorbital planets

We numerically investigate the stability of systems of 1 \({{\rm M}_{\oplus}}\) planets orbiting a solar-mass star. The systems studied have either 2 or 42 planets per occupied semimajor axis, for a total of 6, 10, 126, or 210 planets, and the planets were started on coplanar, circular orbits with the semimajor axes of the innermost planets at 1 AU. For systems with two planets per occupied orbit, the longitudinal initial locations of planets on a given orbit were separated by either 60° (Trojan planets) or 180°. With 42 planets per semimajor axis, initial longitudes were uniformly spaced. The ratio of the semimajor axes of consecutive coorbital groups in each system was approximately uniform. The instability time for a system was taken to be the first time at which the orbits of two planets with different initial orbital distances crossed. Simulations spanned virtual times of up to 1 × 10⁸, 5 × 10⁵, and 2 × 10⁵ years for the 6- and 10-planet, 126-planet, and 210-planet systems, respectively. Our results show that, for a given class of system (e.g., five pairs of Trojan planets orbiting in the same direction), the relationship between orbit crossing times and planetary spacing is well fit by the functional form log(t _c /t ₀) = b β + c, where t _c is the crossing time, t ₀ = 1 year, β is the separation in initial orbital semimajor axis (in terms of the mutual Hill radii of the planets), and b and c are fitting constants. The same functional form was observed in the previous studies of single planets on nested orbits (Smith and Lissauer 2009). Pairs of Trojan planets are more stable than pairs initially separated by 180°. Systems with retrograde planets (i.e., some planets orbiting in the opposite sense from others) can be packed substantially more closely than can systems with all planets orbiting in the same sense. To have the same characteristic lifetime, systems with 2 or 42 planets per orbit typically need to have about 1.5 or 2 times the orbital separation as orbits occupied by single planets, respectively.     

AquaEnv: An Aquatic Acid–Base Modelling Environment in R

AquaEnv is an integrated software package for aquatic chemical model generation focused on ocean acidification and antropogenic CO₂ uptake. However, the package is not restricted to the carbon cycle or the oceans: it calculates, converts, and visualizes information necessary to describe pH, related CO₂ air–water exchange, as well as aquatic acid–base chemistry in general for marine, estuarine or freshwater systems. Due to the fact that it includes the relevant acid–base systems, it can also be applied to pore water systems and anoxic waters. AquaEnv is implemented in the open source programming language R , which allows for a flexible and versatile application: AquaEnv ’s functionality can be used stand-alone as well as seamlessly integrated into reactive-transport models in the R modelling environment. Additionally, AquaEnv provides a routine to simulate and investigate titrations of water samples with a strong acid or base, as well as a routine that allows for a determination of total alkalinity and total carbonate values from recorded titration curves using non-linear curve-fitting.     

Rotating deep annulus convection: The steady high amplitude wave regime—Internal thermal fields

Abstract

In the high-amplitude wave regime, at each point in the axial plane, the temperature has a maximum, a minimum, and a time (or longitudinally) averaged value due to the propagation of the regular waves. The axial-plane profile of each of these three temperature fields was measured for 53 different combinations of ω, Δr _w T and n. A few sample profiles are displayed.

Correlations of several internal thermal parameters (especially Ro _g,t ) with the externally imposed parameters, are given along with the spatial variation of the thermal fields. Ro _g,t is always less than the value which would occur if the symmetrical regime existed, while the variation of Sz _g,t with the imposed parameters is about the same as for the symmetrical regime. The parametric variation of the wave amplitude is the only quantity dependent on n. Based on the parametric variation of the fields, the wave regime diagram can be subdivided into several different regions : a quasi-conductive, a conductive-convective zone, and a region at large rotation rates and temperature differences characterized by Ro _g,t = Ro _g,w ², Sz _o,l = Ro _g,w , and ΔT′ = (z′)^0.6.

The Ro _g, l fields are compared to existing theory and some of the experimental stability diagrams of Fultz et al. (1964) are reconstructed using the internal instead of the externally imposed Rossby number. The transition from three to four waves via a “minor wave” is illustrated.     

Tidal heating in Enceladus

The heating in Enceladus in an equilibrium resonant configuration with other saturnian satellites can be estimated independently of the physical properties of Enceladus. We find that equilibrium tidal heating cannot account for the heat that is observed to be coming from Enceladus. Equilibrium heating in possible past resonances likewise cannot explain prior resurfacing events.     

Automated Boundary-extraction And Region-growing Techniques Applied To Solar Magnetograms

We present an automated approach to active region extraction from full-disc MDI longitudinal magnetograms. This uses a region-growing technique in conjunction with boundary-extraction to define a number of enclosed contours as belonging to separate regions of magnetic significance on the solar disc. This provides an objective definition of active regions and areas of plage on the Sun. A number of parameters relating to the flare potential of each region are discussed.     

Avalanche models of active region heating and flaring

In a previous paper, we suggested that the twisting of coronal magnetic fiels by photospheric motions produces the steady heating of an active region, while braiding of these fields stores energy which is eventually released in an avalanche process, as sporadic large flares. We explore these ideas with numerical simulations. Our results indicate that the combined effect of twisting and braiding can account for the observed power input and the flare frequency spectrum of typical active regions.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under coooperative agreement with the National Science Foundation.