Phase growth in bistable systems with impurities

A system of coupled chaotic bistable maps on a lattice with randomly distributed impurities is investigated as a model for studying the phenomenon of phase growth in nonuniform media. The statistical properties of the system are characterized by means of the average size of spatial domains of equivalent spin variables that define the phases. It is found that the rate at which phase domains grow becomes smaller when impurities are present and that the average size of the resulting domains in the inhomogeneous state of the system decreases when the density of impurities is increased. The phase diagram showing regions where homogeneous, heterogeneous, and chessboard patterns occur on the space of parameters of the system is obtained. A critical boundary that separates the regime of slow growth of domains from the regime of fast growth in the heterogeneous region of the phase diagram is calculated. The transition between these two growth regimes is explained in terms of the stability properties of the local phase configurations. Our results show that the inclusion of spatial inhomogeneities can be used as a control mechanism for the size and growth velocity of phase domains forming in spatiotemporal systems.Comment: 7 pages, 12 figure

Extended Hamiltonian systems in multisymplectic field theories

We consider Hamiltonian systems in first-order multisymplectic field theories. We review the properties of Hamiltonian systems in the so-called restricted multimomentum bundle, including the variational principle which leads to the Hamiltonian field equations. In an analogous way to how these systems are defined in the so-called extended (symplectic) formulation of non-autonomous mechanics, we introduce Hamiltonian systems in the extended multimomentum bundle. The geometric properties of these systems are studied, the Hamiltonian equations are analyzed using integrable multivector fields, the corresponding variational principle is also stated, and the relation between the extended and the restricted Hamiltonian systems is established. All these properties are also adapted to certain kinds of submanifolds of the multimomentum bundles in order to cover the case of almost-regular field theories.Comment: 36 pp. The introduction and the abstract have been rewritten. New references are added and some little mistakes are corrected. The title has been slightly modifie

Integrating Theatre and Biology: How Embodied Performance Can Enhance Empathy Among College Science Students

In these field notes, we examine the integration of the arts into a 20-person honors biology seminar at UC Riverside “Beyond Science: Being Humane Amid Human Rights Crises.” We held a four-hour workshop to examine the ways in which performance and theatrical storytelling can enhance science learning. The workshop provided a unique avenue for exploring how human activities result in downward consequences including refugee displacement, one of the course objectives. In addition to the workshop, we conducted surveys and a focus group with the students to better understand their experience incorporating the arts into their science class. A key concept that arose in the focus group was how engaging with theatre contributed to students’ empathy

Further Evidence for Seed Size Variation in the Genus Zostera: Exploratory Studies with Z. japonica and Z. asiatica

Recent studies found seed size variation within the seagrass Zostera marina, one of nine species in the genus Zostera. The objectives of this study were to determine if variation also exists in the seeds of two other species Zostera japonica and Zostera asiatica within this genus. Results indicate that: (1) length and weight varied between two populations (one indigenous population from Akkeshi-Ko, Japan, and one exotic population from Willapa Bay, Washington, USA) of the small-bodied intertidal seagrass species Z. japonica, and (2) seed-size classes were discernable. Preliminary investigations were also initiated with a Japanese population of Z. asiatica, a large-bodied subtidal seagrass species. Z. japonica seeds from the exotic population were significantly (P \u3c 0.00 1) longer and heavier when compared to those from the indigenous population, a finding which may help explain both the process of the earlier introduction and the recent expansion of this exotic in the northeastern Pacific. Also, preliminary results indicate that Z. asiatica seeds are heavier than both those of Z. marina and Z. japonica, which suggests that larger seeds may be associated with large-bodied plants in this genus, an observation that should direct future seed ecology studies within the genus. These findings demonstrate that, similar to the study of terrestrial angiosperms, investigations designed to describe the comparative ecology of marine seed-bearing plants should include an evaluation of seed size

Horne v. Department of Agriculture: Expanding Per Se Takings While Endorsing State Sovereign Ownership of Wildlife

In Horne v. Department of Agriculture, the Supreme Court expanded its so-called per se analysis under the Takings Clause to government actions impairing possession of personal property. The Court decided that a New Deal era agricultural program effected a taking by requiring raisin growers to turn over a portion of their crops in certain years to a governmental body that disposes of the raisins in noncompetitive markets. The raisin marketing program, which by law only persists with continuing support from the raisin industry itself, aims to control the market supply of raisins, and thereby elevate and stabilize the prices received by raisin growers. Despite the unusual character of the program, a majority of the Court ruled that certain dissident raisin growers were entitled to prevail on their theory that government appropriations of personal property interests in raisins were governed by the same per se takings rule that applies to government appropriations of real property. The Court\u27s analysis of the takings issue is problematic for a number of reasons , including 1) the fact that these particular plaintiffs, who were proceeding in the capacity of raisin handlers, were not the actual owners of the raisins at issue, and therefore could not legitimately claim a taking of their private property; 2) the Court\u27s modern precedents and traditional practice support the idea that government has broader latitude in controlling personal property than real property, contradicting the Court\u27s new per se rule; 3) there was a substantial question as to whether the program imposed an unconstitutional taking of property without just compensation, given the significant offsetting benefits growers received from this price support system; and 4) the Court failed to give the government the opportunity to defend the conditions imposed on raisin growers by showing that that the conditions satisfied the standards articulated in Nollan v. California Coastal Commission and Dolan v. City of Tigard. Each of these issues provided a proper basis for affirming the Ninth Circuit\u27s rejection of the takings argument. Nevertheless, Chief Justice John Roberts\u27 majority opinion either ignored or skimmed over all these issues and applied a per se takings rule to this context. Figuring out the implications of the Horne decision for drug forfeiture laws, unwholesome food recalls, and animal cruelty statutes has been left to other days and other cases. The Horne decision did include an unexpected result of considerable benefit to government defendants, however: the Court distinguished the raisin marketing program from a similar program involving oysters that it upheld against a takings challenge in a 1929 decision. The Chief Justice explained that, unlike raisins, oysters were public property. The Court thereby ratified the venerable but somewhat misunderstood doctrine of sovereign ownership of wildlife. States employ this doctrine, inherited from England and nearly universally adopted by American states, to uphold wildlife conservation regulations and defeat claims of private ownership. Often referred to as the wildlife trust, the doctrine is the kind of background principle of property law that the Court recognized as defeating claims of takings in its 1992 decision of Lucas v. South Carolina Coastal Commission. In this article we examine the Horne decision in some detail. Although the case does extend the Court\u27s takings jurisprudence to an uncertain extent by applying the per se analysis to personal property, we think the long-term ramifications of the decision lie in the Court\u27s recognition of the sovereign ownership of wildlife. That doctrine not only will defeat private takings claims but should sanction affirmative regulation of wildlife and protection for its habitat, authorize government actions to recover damages against those harming wildlife and wildlife habitat, and reinforce public standing to enforce the wildlife trust

A note on the cylindrical collapse of counter-rotating dust

We find analytical solutions describing the collapse of an infinitely long cylindrical shell of counter-rotating dust. We show that--for the classes of solutions discussed herein--from regular initial data a curvature singularity inevitably develops, and no apparent horizons form, thus in accord with the spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for publication in Int. J. Mod. Phys.

A Multicultivar Approach for Grape Bunch Weight Estimation Using Image Analysis

The determination of bunch features that are relevant for bunch weight estimation is an important step in automatic vineyard yield estimation using image analysis. The conversion of 2D image features into mass can be highly dependent on grapevine cultivar, as the bunch morphology varies greatly. This paper aims to explore the relationships between bunch weight and bunch features obtained from image analysis considering a multicultivar approach. A set of 192 bunches from four cultivars, collected at sites located in Portugal and South Africa, were imaged using a conventional digital RGB camera, followed by image analysis, where several bunch features were extracted, along with physical measurements performed in laboratory conditions. Image data features were explored as predictors of bunch weight, individually and in a multiple stepwise regression analysis, which were then tested on 37% of the data. The results show that the variables bunch area and visible berries are good predictors of bunch weight (R2 ranging from 0.72 to 0.90); however, the simple regression lines fitted between these predictors and the response variable presented significantly different slopes among cultivars, indicating cultivar dependency. The elected multiple regression model used a combination of four variables: bunch area, bunch perimeter, visible berry number, and average berry area. The regression analysis between the actual and estimated bunch weight yielded a R2 = 0.91 on the test set. Our results are an important step towards automatic yield estimation in the vineyard, as they increase the possibility of applying image-based approaches using a generalized model, independent of the cultivarinfo:eu-repo/semantics/publishedVersio