2,034 research outputs found
Interrupting the social amplification of risk process: a case study in collective emissions reduction
One of the main approaches we have for studying the progressive divergence of understandings around a risk issue is that of social risk amplification. This article describes a case study of a particular environmental contaminant, a chemical flame retardant that could be interpreted as having produced a risk amplifying process. It describes in particular how a group of industrial organizations acted collectively to reduce emissions of this contaminant, in an apparent attempt to avert regulation and boycottsâthat is, to intercept the social amplification process and avoid its secondary effects. The aim of the study was to investigate the constitutive qualities of this collective action: the qualities that defined it and made it effective in the eyes of those involved. These include institutionalisation and independence, the ability to confer individual as well as collective benefit, the capacity to attract (rather than avoid) criticism, and the âbrandingâ that helps communicate what otherwise appear to be a set of unconnected, local actions. Although the risk amplification framework has been criticised for implying that there is some externally given risk level that is subsequently amplified, it does appear to capture the mentality of actors involved in issues of this kind. They talk and act as though they believe they are participants in a risk amplification process
Year-round and Migratory Birds of the Flint Hills
The Flint Hills support a wide diversity of birds. with some 250 species having been recorded. They range in size from the Ruby-throated Hummingbird (3 grams) to the 10-kg Wild Turkey. Birds tend to specialize by habitat, and each habitat---be it tallgrass prairie, shrublands, riparian forest, cropland, or farmstead---supports its own assemblage of bird species
Computation of steady and unsteady quasi-one-dimensional viscous/inviscid interacting internal flows at subsonic, transonic, and supersonic Mach numbers
Computations of viscous-inviscid interacting internal flowfields are presented for steady and unsteady quasi-one-dimensional (Q1D) test cases. The unsteady Q1D Euler equations are coupled with integral boundary-layer equations for unsteady, two-dimensional (planar or axisymmetric), turbulent flow over impermeable, adiabatic walls. The coupling methodology differs from that used in most techniques reported previously in that the above mentioned equation sets are written as a complete system and solved simultaneously; that is, the coupling is carried out directly through the equations as opposed to coupling the solutions of the different equation sets. Solutions to the coupled system of equations are obtained using both explicit and implicit numerical schemes for steady subsonic, steady transonic, and both steady and unsteady supersonic internal flowfields. Computed solutions are compared with measurements as well as Navier-Stokes and inverse boundary-layer methods. An analysis of the eigenvalues of the coefficient matrix associated with the quasi-linear form of the coupled system of equations indicates the presence of complex eigenvalues for certain flow conditions. It is concluded that although reasonable solutions can be obtained numerically, these complex eigenvalues contribute to the overall difficulty in obtaining numerical solutions to the coupled system of equations
Generation of non-stationary stochastic fields using Generative Adversarial Networks with limited training data
In the context of generating geological facies conditioned on observed data,
samples corresponding to all possible conditions are not generally available in
the training set and hence the generation of these realizations depends primary
on the generalization capability of the trained generative model. The problem
becomes more complex when applied on non-stationary fields. In this work, we
investigate the problem of training Generative Adversarial Networks (GANs)
models against a dataset of geological channelized patterns that has a few
non-stationary spatial modes and examine the training and self-conditioning
settings that improve the generalization capability at new spatial modes that
were never seen in the given training set. The developed training method
allowed for effective learning of the correlation between the spatial
conditions (i.e. non-stationary maps) and the realizations implicitly without
using additional loss terms or solving a costly optimization problem at the
realization generation phase. Our models, trained on real and artificial
datasets were able to generate geologically-plausible realizations beyond the
training samples with a strong correlation with the target maps
Surface analysis for students in Nuclear Engineering and Radiological Sciences
Students in Nuclear Engineering and Radiological Sciences at the University of Michigan are required to learn about the various applications of radiation. Because of the broad applicability of accelerators to surface analysis, one of these courses includes a laboratory session on surface analysis techniques such as Rutherford Backscattering Analysis (RBS) and Nuclear Reaction Analysis (NRA). In this laboratory session, the students determine the concentration of nitrogen atoms in various targets using RBS and NRA by way of the 14N(d,α)12C reaction. The laboratory is conducted in a handsâon format in which the students conduct the experiment and take the data. This paper describes the approach to teaching the theory and experimental methods behind the techniques, the conduct of the experiment and the analysis of the data. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87310/2/856_1.pd
Floral Neighborhood and Pollination Success in Four Hummingbird-Pollinated Cloud Forest Plant Species
In a cloud forest at Monteverde, Costa Rica, was examined pollen loads received by selfâcompatible flowers of two pairs of plant species pollinated by hummingbirds: Hansteinia blepharorachis and Razisea spicata (Acanthaceae), and Besleria triflora and Drymonia rubra (Gesneriaceae). Each pair consisted of one species (Hansteinia or Besleria) pollinated by shortâbilled hummingbirds and a related species (Razisea or Drymonia) pollinated by longâbilled hummingbirds. At three different times per species, separated by 1â3 mo, we examined flowers on 28â40 focal plants from a wide variety of floral neighborhoods, ranging from plants isolated from conspecifics, either by distance or by other flowering species pollinated by the same hummingbirds, to plants surrounded by conspecifics. Because shortâbilled hummingbirds often restrict foraging to areas of high flower density, and because shortâtubed flowers adapted for hummingbirds often have similar pollen placement, we predicted that shortâtubed flowers isolated from conspecifics would receive fewer conspecific grains and more heterospecific grains than shortâtubed flowers surrounded by conspecifics. Because longâbilled hummingbirds often forage over large areas and because longâtubed flowers adapted for hummingbirds tend to diverge in pollen placement, we predicted that pollination of longâtubed flowers would be relatively unaffected by floral neighborhood. Effects on pollen loads of floral neighborhood (nearness to or isolation from other flowers) followed few patterns consistent with our prediction or with conventional theory. (1) There were no consistent effects of floral neighborhoods on numbers of heterospecific grains deposited on stigmas; in all four species, regardless of corolla length, effects of particular neighborhood variables (as determined with stepwise multiple regression) were as likely to run exactly counter to conventional models as to corroborate models. (2) In none of the 12 sampling runs did increases in absolute densities of neighboring heterospecific flowers adversely affect pollination. (3) However, in two runs, loads of conspecific grains increased with increases in the absolute density of neighboring conspecific flowers, and/or (in three runs) with increases in their relative density (proportion of conspecifics among neighboring flowers). These runs all involved shortâflowered species rather than longâflowered species, tending confirm our initial prediction, but half the sampling runs, even of shortâflowered species, failed to show any densityâdependent effects from neighboring flowers pollinated by the same hummingbirds. Flowers frequently received fewer conspecific grains than they had ovules to be fertilized. Therefore the potential existed for floral neighborhoods to affect seed set and fitness of plants. Nevertheless, even though neotropical hummingbirdâpollinated flowers have been cited as examples of species whose flowering peaks are displaced through competition for pollination, competitive effects from neighboring heterospecific plants were only sporadic in the species we examined, and were particularly infrequent in those species with long flowers adapted for longâbilled hummingbirds
Effect of MGA on Performance, Sexual Behavior, Carcass Quality and Tenderness in Mixed-Sex Pens of Cattle
The effect of MGA in mixed pens of steers and heifers was evaluated over a three-year period at the ISU Armstrong Research Farm near Lewis, Iowa. Two pens of approximately 40 head were fed diets with or without MGA in each of three replications. Estrus and riding activity was monitored using the Heat Watch system. At slaughter, in addition to routine carcass data collection, a rib sample was collected from each carcass for tenderness evaluation. There was no effect on dry matter intake due to MGA treatment. Mixed-sex pens that were fed MGA were 4% more efficient than controls. MGA-fed steers gained similarly to control steers. MGA fed heifers gained 8% faster than control heifers. MGA highly reduced measures of estrus and riding activity throughout the feeding period. MGA feeding improved marbling and tenderness measured in both steers and heifers. These data suggest that MGA has potential to improve performance, quality grade, and tenderness in mixed pens of steers and heifers
Disturbance, Pollinator Predictability, and Pollination Success Among Costa Rican Cloud Forest Plants
Cloud forest at Monteverde, Costa Rica experiences frequent natural disturbance. To determine whether species interactions vary spatially due to physical heterogeneity produced by disturbance, we examined relationships between 22 plant species and 11 nectarâfeeding bird species in 14 study plots distributed among three patch types: larger landslideâlike gaps (handâcleared areas along a trail), small gaps (formed by recent treefalls), and understory of closedâcanopy forest. Species we describe here flowered in two or three patch types. The aspects of pollination we examined varied little with patch type. Mean frequency of pollinator visits varied with patch type in a few plant species but not in most, and there was no significant trend across species. Pollen loads carried by 314 mistânetted hummingbirds did not vary significantly with patch type, either in total number of grains or number of species represented. Cumulative pollen loads that hummingbirds deposited on stigmas of two species of Acanthaceae (Razisea spicata and Hansteinia blepharorachis) did not vary consistently with patch type, except that Hansteinia flowers in treefall gaps received fewer heterospecific pollen grains than flowers in the other two patch types. Frequency of fruit set varied significantly with patch type in three of the four species examined, but the direction of variation in one of these was opposite to the direction of the other two. The absolute frequency with which flowers were pierced by nectarârobbing hummingbirds did not vary significantly with patch type, although the frequency of piercing relative to legitimate pollinator visits did increase in the large gaps. We attribute the latter result to aggregation of the hummingbird Eupherusa eximia, a chronic nectar robber, at dense clumps of longâflowered plant species that occurred in large gaps. Only one feature we examined suggested that patch type might directly affect the nature of species interactions: in two different analyses, the level of variation in frequency of hummingbird visits to flowers declined from large gaps to small gaps to forest. Results suggest that, unless the disturbance initiating a patch is unusually severe or widespread, interactions between the plants and hummingbirds examined are insensitive to patch type. Such species, existing in naturally dynamic forests throughout their recent evolutionary histories, presumably have become accommodated to frequent smallâscale disturbance. Results also suggest that those habitatârelated contrasts in plant reproductive traits and plantâpollinator interactions documented in other studies, which compare habitats initiated by anthropogenic disturbances with undisturbed patches, may be artifacts to some extent. Anthropogenically generated disturbance mosaics may promote the spread of species whose reproductive traits evolved under very different circumstances from mosaics generated by natural disturbances
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