The Invisible Forest: Conservation Easement Databases and the End of the Clandestine Conservation of Natural Lands

Olmsted talks about invisible forest refers to forest lands -- and, for that matter, any other land types -- protected by a perpetual conservation easement, the existence and location of which are concealed from the public, whether deliberately or because of the opaque nature of the easement process. Because easements, like other forms of deeds, must be recorded at the local land registry or recorder\u27s office, they can never be made undiscoverable. But, despite the efforts of some states and conservation organizations to compile conservation easement data for public consumption, there are few functional systems that comprehensively track and provide easy access to conservation easement data

The 1930s origins of California's Farmworker-Church alliance

In the 1930s, Social Gospel ministers in the Los Angeles area organized to help farmworkers in Southern California. The reformist pastors worked across class, denominational, and racial lines and transcended language barriers as they built urban, coastal support for immigrant farmworkers in interior valleys. In the end, they failed, largely because employers were able to use the Communist affiliations of the farmworker union leaders to Red-bait and intimidate the ministers. Only when a later generation of labor leaders distanced their movement from Communism and grounded it in Christian rhetoric and imagery would this religious-labor alliance achieve victory

Dynamical Coarse-Graining of Highly Fluctuating Membranes under Shear Flow

The effect of strong shear flow on highly fluctuating lamellar systems stabilized by intermembrane collisions via the Helfrich interaction is studied. Advection enters the microscopic equation of motion for a single membrane via a non-linear coupling. Upon coarse-graining the theory for a single bilayer up to the length scale of the collision length, at which a hydrodynamic description applies, an additional dynamical coupling is generated which is of the form of a wavevector-dependent tension that is non-linear in the applied shear rate. This new term has consequences for the effects of strong flow on the stability and dynamics of lamellar surfactant phases.Comment: 17 pages, 6 figure, submitted to Phys Rev

Dynamics and flow-induced phase separation in polymeric fluids

The past few years have seen many advances in our understanding of the dynamics of polymeric fluids. These include improvements on the successful reptation theory; an emerging molecular theory of semiflexible chain dynamics; and an understanding of how to calculate and classify ``phase diagrams'' for flow-induced transitions. Experimentalists have begun mapping out the phase behavior of wormlike micelles, a ``living'' polymeric system, in flow: these systems undergo transitions into shear-thinning or shear-thickening phases, whose variety is remarkably rich and poorly understood. Polymeric ideas must be extended to include the delicate charge and composition effects which conspire to stabilize the micelles and are strongly influenced by flow.Comment: 6 pages, 2 figures, submitted to Current Opinion in Colloid and Interface Scienc

Some properties of membranes in nematic solvents

The fluctuation spectrum of membranes in nematic solvents is altered by the boundary condition imposed on the bulk nematic director by the curved membrane. We discuss some properties of single and multi-membrane systems in nematic solvents, primarily based on the Berreman-de~Gennes model. We show that: membranes in nematic solvents are more rigid and less rough than in their isotropic counterparts; have a different Helfrich steric stabilization energy, proportional to $d^{-3}$, and hence a different compression modulus in the lamellar state; and can exhibit phase separation via unbinding during a quench into the nematic state. We also discuss the preparation and possible experimental effects of nematic-mediated surfactant membrane system

Foreword

The land trust community and governments at all levels have become married to conservation easements as their land conservation tool of choice. The numbers speak for themselves: as of the date of this writing, there were reportedly 1,700 land trusts that have protected twelve million acres of land by use of conservation easements. The bulk of this growth both in conservation easements and the land trusts that deploy them has occurred since the 1980s when federal income tax incentives became more fully utilized by conservation easement donors. But the parties to this marriage have become complacent and inattentive in the face of a rapidly changing world resulting from global ecological catastrophes such as climate change and accelerated species extinction

Phase Coexistence of Complex Fluids in Shear Flow

We present some results of recent calculations of rigid rod-like particles in shear flow, based on the Doi model. This is an ideal model system for exhibiting the generic behavior of shear-thinning fluids (polymer solutions, wormlike micelles, surfactant solutions, liquid crystals) in shear flow. We present calculations of phase coexistence under shear among weakly-aligned (paranematic) and strongly-aligned phases, including alignment in the shear plane and in the vorticity direction (log-rolling). Phase coexistence is possible, in principle, under conditions of both common shear stress and common strain rate, corresponding to different orientations of the interface between phases. We discuss arguments for resolving this degeneracy. Calculation of phase coexistence relies on the presence of inhomogeneous terms in the dynamical equations of motion, which select the appropriate pair of coexisting states. We cast this condition in terms of an equivalent dynamical system, and explore some aspects of how this differs from equilibrium phase coexistence.Comment: 16 pages, 10 figures, submitted to Faraday Discussion

Two-dimensional perturbations in a scalar model for shear banding

We present an analytical study of a toy model for shear banding, without normal stresses, which uses a piecewise linear approximation to the flow curve (shear stress as a function of shear rate). This model exhibits multiple stationary states, one of which is linearly stable against general two-dimensional perturbations. This is in contrast to analogous results for the Johnson-Segalman model, which includes normal stresses, and which has been reported to be linearly unstable for general two-dimensional perturbations. This strongly suggests that the linear instabilities found in the Johnson-Segalman can be attributed to normal stress effects.Comment: 16 pages, 10 figures, to appear in EPJE, available online first, click DOI or http://www.springerlink.com/content/q1q0187385017628

A non-monotonic constitutive model is not necessary to obtain shear banding phenomena in entangled polymer solutions

In 1975 Doi and Edwards predicted that entangled polymer melts and solutions can have a constitutive instability, signified by a decreasing stress for shear rates greater than the inverse of the reptation time. Experiments did not support this, and more sophisticated theories incorporated Marrucci's idea (1996) of removing constraints by advection; this produced a monotonically increasing stress and thus stable constitutive behavior. Recent experiments have suggested that entangled polymer solutions may possess a constitutive instability after all, and have led some workers to question the validity of existing constitutive models. In this Letter we use a simple modern constitutive model for entangled polymers, the non-stretching Rolie-Poly model with an added solvent viscosity, and show that (1) instability and shear banding is captured within this simple class of models; (2) shear banding phenomena is observable for weakly stable fluids in flow geometries that impose a sufficiently inhomogeneous total shear stress; (3) transient phenomena can possess inhomogeneities that resemble shear banding, even for weakly stable fluids. Many of these results are model-independent.Comment: 5 figure