20,662 research outputs found
\u3ci\u3eLibellula Flavida\u3c/i\u3e (Odonata: Libellulidae), a Dragonfly New to Ohio
Libellula flavida, a widespread but uncommon dragonfly of southeastern and south central North America, is now recorded from Ohio. A breeding population was discovered in an acidic fen on the site of a sandstone quarry in southern Ohio
Technique for calibrating angular measurement devices when calibration standards are unavailable
A calibration technique is proposed that will allow the calibration of certain angular measurement devices without requiring the use of absolute standard. The technique assumes that the device to be calibrated has deterministic bias errors. A comparison device must be available that meets the same requirements. The two devices are compared; one device is then rotated with respect to the other, and a second comparison is performed. If the data are reduced using the described technique, the individual errors of the two devices can be determined
Percolation of even sites for random sequential adsorption
Consider random sequential adsorption on a red/blue chequerboard lattice with
arrivals at rate on the red squares and rate on the blue squares.
We prove that the critical value of , above which we get an infinite
blue component, is finite and strictly greater than .Comment: 35 pages. 13 figure
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Water governance and poverty: a framework for analysis
YesIn this paper we present a framework for understanding water governance, through which we
critique some of the assumptions underlying the current consensus on good governance.
Specifically, we suggest that current approaches are based on incomplete or partial
understandings of the concepts of governance. We question the idea that governance can be
identified as an abstract set of principles, without the need for contextualisation and localisation.
In particular, we suggest that there is a general lack of understanding of the way local
interactions shape and influence governance processes. Finally, and with specific reference to
the MDGs and the water sector, we question the implicit assumption that `good¿ governance is
necessarily pro-poor governance.
The paper addresses these issues through a critical discussion of governance, from which we
develop a framework for conceptualising water governance. The framework draws on theories of
governance, institutions and structuration, but is also informed by recent empirical research and
experiences from the field. We apply the framework to a specific case in Southwestern Tanzania
and raise a number of issues and challenges for further research
General self-motivation and strategy identification : Case studies based on Sokoban and Pac-Man
(c) 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, we use empowerment, a recently introduced biologically inspired measure, to allow an AI player to assign utility values to potential future states within a previously unencountered game without requiring explicit specification of goal states. We further introduce strategic affinity, a method of grouping action sequences together to form "strategies," by examining the overlap in the sets of potential future states following each such action sequence. We also demonstrate an information-theoretic method of predicting future utility. Combining these methods, we extend empowerment to soft-horizon empowerment which enables the player to select a repertoire of action sequences that aim to maintain anticipated utility. We show how this method provides a proto-heuristic for nonterminal states prior to specifying concrete game goals, and propose it as a principled candidate model for "intuitive" strategy selection, in line with other recent work on "self-motivated agent behavior." We demonstrate that the technique, despite being generically defined independently of scenario, performs quite well in relatively disparate scenarios, such as a Sokoban-inspired box-pushing scenario and in a Pac-Man-inspired predator game, suggesting novel and principle-based candidate routes toward more general game-playing algorithms.Peer reviewedFinal Accepted Versio
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How institutions elude design: river basin management and sustainable livelihoods.
YesThis paper challenges ideas that it is possible to `get the institutions right¿ in the management of natural resources. It engages with the literature and policy specifying `design principles¿ for robust institutions and uses data from a river basin management project in Usangu, Tanzania, to illustrate the complexity of institutional evolution. The paper draws on emerging `post-institutionalist¿ perspectives to reject over-formalised managerial approaches in favour of those that accept the dynamic nature of institutional formation, and accommodate a variety of partial and contingent solutions. Data from Usangu suggests that external `crafting¿ is inevitably problematic because, to a certain extent, institutions elude design
Dynamic mimicry in an Indo-Malayan octopus
During research dives in Indonesia (Sulawesi and Bali), we filmed a distinctive long-armed octopus, which is new to science. Diving over 24 h periods revealed that the 'mimic octopus' emerges during daylight hours to forage on sand substrates in full view of pelagic fish predators. We observed nine individuals of this species displaying a repertoire of postures and body patterns, several of which are clearly impersonations of venomous animals co-occurring in this habitat. This 'dynamic mimicry' avoids the genetic constraints that may limit the diversity of genetically polymorphic mimics but has the same effect of decreasing the frequency with which predators encounter particular mimics. Additionally, our observations suggest that the octopus makes decisions about the most appropriate form of mimicry to use, allowing it to enhance further the benefits of mimicking toxic models by employing mimicry according to the nature of perceived threats
The 3D modeling of high numerical aperture imaging in thin films
A modelling technique is described which is used to explore three dimensional (3D) image irradiance distributions formed by high numerical aperture (NA is greater than 0.5) lenses in homogeneous, linear films. This work uses a 3D modelling approach that is based on a plane-wave decomposition in the exit pupil. Each plane wave component is weighted by factors due to polarization, aberration, and input amplitude and phase terms. This is combined with a modified thin-film matrix technique to derive the total field amplitude at each point in a film by a coherent vector sum over all plane waves. Then the total irradiance is calculated. The model is used to show how asymmetries present in the polarized image change with the influence of a thin film through varying degrees of focus
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