Speculations on the postnatural: Restoration, accumulation, and sacrifice at the Salton Sea

Using a regional political ecology lens, this paper explores emerging geographies and politics of a “postnatural” ecomodernist turn in mainstream environmentalism. We examine the unfolding case of ecological restoration and renewable energy development at Southern California’s Salton Sea. Ambitious proposals to restore the massive, increasingly degraded lake (and finance restoration) by reengineering it as a hub for geothermal energy generation and high-tech green industry hinge upon the ambiguity and malleability of restoration in an environment long classified as postnatural. These plans coincide with a broader rush on renewable energy sites in the California desert, and mounting conflicts over water and land with legacy agro-industrial interests. The case illustrates significant problems within postnatural environmentalism. First, it demonstrates how theorizations of the postnatural can intersect with green capitalist projects of re(e)valuation and development, as the Sea’s managers manipulate environmental framings to support accumulation-minded projects, and accumulation imperatives swamp other functionalities of restoration. Meanwhile, despite the flourishing of postnatural discourses, the “pristine” is shown to do continued work as the Sea becomes a sacrifice zone for development deflected from better-protected spaces. This postnatural positioning has rendered the Salton Sea vulnerable to neoliberal austerity and speculation in ways that compromise its future existence

The Yamabe invariant for axially symmetric two Kerr black holes initial data

An explicit 3-dimensional Riemannian metric is constructed which can be interpreted as the (conformal) sum of two Kerr black holes with aligned angular momentum. When the separation distance between them is large we prove that this metric has positive Ricci scalar and hence positive Yamabe invariant. This metric can be used to construct axially symmetric initial data for two Kerr black holes with large angular momentum.Comment: 14 pages, 2 figure

Evaluation of positive G sub Z tolerance following simulated weightlessness (bedrest)

The magnitude of physiologic changes which are known to occur in human subjects exposed to varying levels of + G sub Z acceleration following bed rest simulation of weightlessness was studied. Bed rest effects were documented by fluid and electrolyte balance studies, maximal exercise capability, 70 deg passive tilt and lower body negative pressure tests and the ability to endure randomly prescribed acceleration profiles of +2G sub Z, +3G sub Z, and +4G sub Z. Six healthy male volunteers were studied during two weeks of bed rest after adequate control observations, followed by two weeks of recovery, followed by a second two-week period of bed rest at which time an Air Force cutaway anti-G suit was used to determine its effectiveness as a countermeasure for observed cardiovascular changes during acceleration. Results showed uniform and significant changes in all measured parameters as a consequence of bed rest including a reduced ability to tolerate +G sub Z acceleration. The use of anti-G suits significantly improved subject tolerance to all G exposures and returned measured parameters such as heart rate and blood pressure towards or to pre-bed-rest (control) values in four of the six cases

Gating-by-tilt of mechanosensitive membrane channels

We propose an alternative mechanism for the gating of biological membrane channels in response to membrane tension that involves a change in the slope of the membrane near the channel. Under biological membrane tensions we show that the energy difference between the closed (tilted) and open (untilted) states can far exceed kBT and is comparable to what is available under simple ilational gating. Recent experiments demonstrate that membrane leaflet asymmetries (spontaneous curvature) can strong effect the gating of some channels. Such a phenomenon would be more easy to explain under gating-by-tilt, given its novel intrinsic sensitivity to such asymmetry.Comment: 10 pages, 2 figure

Microscopic formulation of the Zimm-Bragg model for the helix-coil transition

A microscopic spin model is proposed for the phenomenological Zimm-Bragg model for the helix-coil transition in biopolymers. This model is shown to provide the same thermophysical properties of the original Zimm-Bragg model and it allows a very convenient framework to compute statistical quantities. Physical origins of this spin model are made transparent by an exact mapping into a one-dimensional Ising model with an external field. However, the dependence on temperature of the reduced external field turns out to differ from the standard one-dimensional Ising model and hence it gives rise to different thermophysical properties, despite the exact mapping connecting them. We discuss how this point has been frequently overlooked in the recent literature.Comment: 11 pages, 2 figure

Relationship of Dietary Aluminum, Phosphorus, and Calcium to Phosphorus and Calcium Metabolism and Growth Performance of Broiler Chicks

Dietary treatments providing three levels of added Al (0, .196, or .392%) as aluminum sulfate and of available phosphorus (Pav) (.45, .68, or .78%) in a factorial arrangement were administered to day-old chicks in Experiment 1. Plasma inorganic phosphorus (Pi) was significantly (P \u3c .05) elevated by increasing Pav and was decreased by Al. Body weight gain, feed intake, and the gain:feed ratio at Day 21 were significantly decreased by increased concentrations of Al, but were unaffected by the Pav concentrations. Decreases of 39 and 73% in weight gain and of 34 and 66% in feed intake resulted from feeding .196 and .392% AL respectively. In Experiment 2, day-old chicks were fed diets supplemented with 0 or .392% Al in combination with .9% Ca plus .45% Pav, .9% Ca plus .78% Pav, 1.8% Ca plus .45% Pav, or 1.8% Caplus .9% Pav. After 21 days, the supplemental A1 resulted in: 1) significantly poorer growth performance; 2) decreased plasma Pi, total Ca, Zn, and Mg; and 3) decreased tibia weight and breaking strength. Elevating Pav improved growth performance, plasma Pi, and tibia weight and strength, and decreased plasma total Ca. Increasing dietary Ca significantly decreased plasma Pi and increased plasma total Ca without affecting other parameters. Increasing Pav alleviated the negative effect of Al on plasma Pi without correcting the negative effect of Al on growth performance

On the existence of initial data containing isolated black holes

We present a general construction of initial data for Einstein's equations containing an arbitrary number of black holes, each of which is instantaneously in equilibrium. Each black hole is taken to be a marginally trapped surface and plays the role of the inner boundary of the Cauchy surface. The black hole is taken to be instantaneously isolated if its outgoing null rays are shear-free. Starting from the choice of a conformal metric and the freely specifiable part of the extrinsic curvature in the bulk, we give a prescription for choosing the shape of the inner boundaries and the boundary conditions that must be imposed there. We show rigorously that with these choices, the resulting non-linear elliptic system always admits solutions.Comment: 11 pages, 2 figures, RevTeX

Reachability in Parametric Interval Markov Chains using Constraints

Parametric Interval Markov Chains (pIMCs) are a specification formalism that extend Markov Chains (MCs) and Interval Markov Chains (IMCs) by taking into account imprecision in the transition probability values: transitions in pIMCs are labeled with parametric intervals of probabilities. In this work, we study the difference between pIMCs and other Markov Chain abstractions models and investigate the two usual semantics for IMCs: once-and-for-all and at-every-step. In particular, we prove that both semantics agree on the maximal/minimal reachability probabilities of a given IMC. We then investigate solutions to several parameter synthesis problems in the context of pIMCs -- consistency, qualitative reachability and quantitative reachability -- that rely on constraint encodings. Finally, we propose a prototype implementation of our constraint encodings with promising results

Initial data for fluid bodies in general relativity

We show that there exist asymptotically flat almost-smooth initial data for Einstein-perfect fluid's equation that represent an isolated liquid-type body. By liquid-type body we mean that the fluid energy density has compact support and takes a strictly positive constant value at its boundary. By almost-smooth we mean that all initial data fields are smooth everywhere on the initial hypersurface except at the body boundary, where tangential derivatives of any order are continuous at that boundary. PACS: 04.20.Ex, 04.40.Nr, 02.30.JrComment: 38 pages, LaTeX 2e, no figures. Accepted for publication in Phys. Rev.

Membranes in rod solutions: a system with spontaneously broken symmetry

We consider a dilute solution of infinitely rigid rods near a curved, perfectly repulsive surface and study the contribution of the rod depletion layer to the bending elastic constants of membranes. We find that a spontaneous curvature state can be induced by exposure of BOTH sides of the membrane to a rod solution. A similar result applies for rigid disks with a diameter equal to the rod's length. We also study the confinement of rods in spherical and cylindrical repulsive shells. This helps elucidate a recent discussion on curvature effects in confined quantum mechanical and polymer systems.Comment: 10 pages, 2 figures, 1 table; submitted to PR