The Impact of Type Ia Supernovae in Quiescent Galaxies: I. Formation of the Multiphase Interstellar medium

A cool phase of the interstellar medium has been observed in many giant elliptical galaxies, but its origin remains unclear. We propose that uneven heating from Type Ia supernovae (SNe Ia), together with radiative cooling, can lead to the formation of the cool phase. The basic idea is that since SNe Ia explode randomly, gas parcels which are not directly heated by SN shocks will cool, forming multiphase gas. We run a series of idealized high-resolution numerical simulations, and find that cool gas develops even when the overall SNe heating rate $H$ exceeds the cooling rate $C$ by a factor as large as 1.4. We also find that the time for multiphase gas development depends on the gas temperature. When the medium has a temperature $T = 3\times 10^6$ K, the cool phase forms within one cooling time \tc; however, the cool phase formation is delayed to a few times \tc\ for higher temperatures. The main reason for the delay is turbulent mixing. Cool gas formed this way would naturally have a metallicity lower than that of the hot medium. For constant $H/C$, there is more turbulent mixing for higher temperature gas. We note that this mechanism of producing cool gas cannot be captured in cosmological simulations, which usually fail to resolve individual SN remnants.Comment: 16 pages, 11 figures, published by ApJ. This work is part of the SMAUG project, see more information at https://www.simonsfoundation.org/flatiron/center-for-computational-astrophysics/galaxy-formation/smaug/papersplash

Evolution of supernovae-driven superbubbles with conduction and cooling

We use spherically symmetric hydrodynamic simulations to study the dynamical evolution and internal structure of superbubbles (SBs) driven by clustered supernovae (SNe), focusing on the effects of thermal conduction and cooling in the interface between the hot bubble interior and cooled shell. Our simulations employ an effective diffusivity to account for turbulent mixing from nonlinear instabilities that are not captured in 1D. The conductive heat flux into the shell is balanced by a combination of cooling in the interface and evaporation of shell gas into the bubble interior. This evaporation increases the density, and decreases the temperature, of the SB interior by more than an order of magnitude relative to simulations without conduction. However, most of the energy conducted into the interface is immediately lost to cooling, reducing the evaporative mass flux required to balance conduction. As a result, the evaporation rate is typically a factor of $\sim$3-30 lower than predicted by the classical similarity solution of Weaver et al. (1977), which neglects cooling. Blast waves from the first $\sim$30 SNe remain supersonic in the SB interior because reduced evaporation from the interface lowers the mass they sweep up in the hot interior. Updating the Weaver solution to include cooling, we construct a new analytic model to predict the cooling rate, evaporation rate, and temporal evolution of SBs. The cooling rate, and hence the hot gas mass, momentum, and energy delivered by SBs, is set by the ambient ISM density and the efficiency of nonlinear mixing at the bubble/shell interface.Comment: 26 pages, 14 figures, plus appendices. Accepted to MNRA

Methodologies for Housing Justice Resource Guide

This Resource Guide is the outcome of a Summer Institute on Methodologies for Housing Justice convened by the Institute on Inequality and Democracy at UCLA Luskin as part of the Housing Justice in Unequal Cities Network, which is supported by the National Science Foundation (BCS 1758774). Held in Los Angeles in August 2019, the Summer Institute brought together participants from cities around the world. As is the case with the overall scope and purpose of the Housing Justice in Unequal Cities Network, it created a shared terrain of scholarship for movement-based and university-based scholars. Dissatisfied with the canonical methods that are in use in housing studies and guided by housing justice movements that are active research communities, the Summer Institute was premised on the assertion that methodology is political. Methodology is rooted in arguments about the world and involves relations of power and knowledge. The method itself – be it countermapping or people’s diaries – does not ensure an ethics of solidarity and a purpose of justice. Such goals require methodologies for liberation. Thus, as is evident in this Resource Guide, our endeavor foregrounds innovative methods that are being used by researchers across academia and activism and explicitly situates such methods in an orientation towards housing justice

Metodologías para la justicia de la vivienda: Guia de recursos

Esta Guía de Recursos es el resultado de un Instituto de Verano sobre Metodologías para la Justicia en la Vivienda convocado por el Instituto sobre Desigualdad y Democracia de UCLA Luskin como parte de la Red de Justicia en la Vivienda en Ciudades Desiguales, que es apoyada por la Fundación Nacional de Ciencias (BCS 1758774). Celebrado en Los Ángeles en agosto de 2019, el Instituto de Verano reunió a participantes de ciudades de todo el mundo. Al igual que el alcance y el propósito general de la Red de Justicia en las Ciudades Desiguales, creó un terreno compartido de para estudiosos del movimiento y académicos de universidades. Con una insatisfacción a los métodos canónicos que se utilizan en los estudios sobre la vivienda y guiado por los movimientos de justicia de la vivienda que son comunidades de investigación activa, el Instituto de verano se basó en la afirmación de que la metodología es política. La metodología se basa en argumentos sobre el mundo e implica relaciones de poder y conocimiento. El método por sí mismo -ya sea el contra ataque al mapeo o los diarios de la genteno asegura una ética de solidaridad y un propósito de justicia. Tales objetivos requieren metodologías para la liberación. Por lo tanto, como es evidente en esta Guía de Recursos, nuestro esfuerzo pone en primer plano los métodos innovadores que están siendo utilizados por los investigadores en todo el mundo académico y el activismo y sitúa explícitamente tales métodos en una orientación hacia la vivienda la justicia

Expanding the utilization of sustainable plant products in aquafeeds: a review

Continued growth and intensification of aquaculture production depends upon the development of sustainable protein sources to replace fish meal in aquafeeds. This document reviews various plant feedstuffs, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various fish species in aquaculture. The plant feedstuffs considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuffs are considered along with the presence of any bioactive compounds that may positively or negatively affect the target organism. Lipid composition of these feedstuffs is not specifically considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid profiles to meet the metabolic requirements of fish and maximize human health benefits are important aspects. Specific strategies and techniques to optimize the nutritional composition of plant feedstuffs and limit potentially adverse effects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuffs in aquaculture to reduce dependence of animal feedstuffs and thereby enhance the sustainability of aquaculture.This article is from Aquaculture Research 38 (2007): 551, doi: 10.1111/j.1365-2109.2007.01704.x.</p