Exploring associations between micro-level models of innovation diffusion and emerging macro-level adoption patterns

A micro-level agent-based model of innovation diffusion was developed that explicitly combines (a) an individual's perception of the advantages or relative utility derived from adoption, and (b) social influence from members of the individual's social network. The micro-model was used to simulate macro-level diffusion patterns emerging from different configurations of micro-model parameters. Micro-level simulation results matched very closely the adoption patterns predicted by the widely-used Bass macro-level model (Bass, 1969). For a portion of the domain, results from micro-simulations were consistent with aggregate-level adoption patterns reported in the literature. Induced Bass macro-level parameters and responded to changes in micro-parameters: (1) increased with the number of innovators and with the rate at which innovators are introduced; (2) increased with the probability of rewiring in small-world networks, as the characteristic path length decreases; and (3) an increase in the overall perceived utility of an innovation caused a corresponding increase in induced and values. Understanding micro to macro linkages can inform the design and assessment of marketing interventions on micro-variables - or processes related to them - to enhance adoption of future products or technologies.Comment: 20 pages, 4 figures and a table of supplementary data. Accepted for publicatio

Sea surface temperature variability in Panamá and Galápagos: Extreme temperatures causing coral bleaching

We examined associations between warm sea surface temperature (SST) anomalies and coral bleaching in the Galápagos Islands and the Gulf of Panamá, in the tropical eastern Pacific Ocean. Interannual SST variability is dominated by the El Niño‐Southern Oscillation phenomenon at Galápagos, whereas only strong events have an SST signature in Panamá. We explored various SST‐related metrics potentially associated with bleaching occurrence: maximum absolute SST, SST anomaly, and the combined effect of intensity and duration of both SST anomalies (described via a “degree days” index) and high SST events. In Galápagos, three Niño years (1983, 1987, and 1992) coincided with bleaching. These were the top three years in both maximum annual SSTs and degree days values. In Panamá, bleaching in 1983 coincided with high maximum SSTs and high degree days. In contrast, no bleaching was detected in 1972 despite high values of both quantities. We found all temperature‐related metrics to be highly correlated, and it was impossible to isolate their effects

Surface hydrography and phytoplankton of the Brazil-Malvinas currents confluence

Results are presented on the phytoplankton species composition and abundance from bottle samples collected in September 1989 near the confluence of the Brazil and Malvinas currents off Argentina. The phytoplankton assemblages were dominated by diatoms and dinoflagellates. A surface diatom bloom was found along the west side of the Brazil Current, and was dominated by Thalassiosira delicatula Ostenfeld emend. Hasle (cell numbers up to 5.5 × 105 cells 1−1) The bloom was associated with strong temperature gradients separating Brazil and Malvinas waters, and with the presence of a cyclonic eddy near the confluence of the currents. These features were detected in satellite imagery coincident with the in situ sampling dates

Exploring the association between swordfish catch rates and thermal fronts on U.S. longline grounds in the western North Atlantic

Associations between ocean surface thermal fronts and the swordfish catch rates of U.S. longline vessels were explored. The study area was the western North Atlantic off the United States, extending from 32°N to 45°N and from 76°W to 63°W. To locate and describe fronts, we used three variables computed from satellite-derived sea surface temperature (SST): horizontal gradient, distance to nearest thermal surface front, and frontal density. Most of the fishing effort analysed occurred along the edge of the continental shelf, where there was a high frequency of frontal presence. Very high catch per unit effort (CPUE) occurred more frequently in the vicinity of fronts than would be expected by chance. The high variability of CPUE that could not be explained by our frontal parameters suggested other, unmeasured, factors also influenced catch rates

Statistics of Brazil Current rings observed from AVHRR: 1993 to 1998

A 6‐year time series of sea surface temperature fields derived from NOAA polar‐orbiter AVHRR 5‐day composites is used to estimate the lifetime, size, and trajectory of 43 warm‐core rings shed by the Brazil Current at the Southwestern Atlantic region in a consistent fashion for the first time. Ring lifetimes range from 11 to 95 days, and are not bi‐modal as is the case for the Gulf Stream anticyclones. Translational speeds range from 4.2 to 27.2 km/day with a mean value of 13.1 km/day. After formation, rings are mostly elliptical with a mean major radius of 126 ± 50 km and a minor radius of 65 ± 22 km. None of the rings seem to last more than four months in the region. An attempt to explore possible connections between ring shedding variability and the Antarctic Dipole is also addressed

Interdisciplinary production of knowledge with participation of stakeholders: A case study of a collaborative project on climate variability, human decisions and agricultural ecosystems in the Argentine Pampas

► Interdisciplinary teams are increasingly common in integrative research but conditions for success in this type of work remain unclear. ► A self-reflective assessment on the collaborative process should be an essential component of integrated assessments. ► Different issues and conflicts arise as interdisciplinary collaboration evolves from project design to project assessment. ► The lack of consensus on criteria for assessment of interdisciplinary research is often ranked as a major challenge. There is a growing perception that science is not responding adequately to the global challenges of the 21st century. Addressing complicated, “wicked” current and future environmental issues requires insights and methods from many disciplines. Furthermore, to reach social robustness in a context of uncertainty and multiple values and objectives, participation of relevant social actors is required. As a consequence, interdisciplinary research teams with stakeholder or practitioner involvement are becoming an emerging pattern for the organization of integrative scientific research or integrated assessments. Nevertheless, still there is need to learn from actual experiences that bring together decision makers and scholars from different disciplines. This paper draws lessons from a self-reflective study of the collaborative process in two interdisciplinary, multi-institutional, multinational research teams addressing linkages between climate variability, human decisions and agricultural ecosystems in the Argentine Pampas. During project design, attention must be placed on team composition, ensuring not only that the needed talents are included, but also recruiting investigators with an open attitude toward interdisciplinary interaction. As the project begins, considerable effort must be dedicated to shared problem definition and development of a common language. Simple conceptual models and considerable redundancy in communication are helpful. As a project evolves, diverging institutional incentives, tensions between academic publication and outreach or policy-relevant outputs, disciplinary biases, and personality issues play increasingly important roles. Finally, toward a project's end the challenge arises of assessing interdisciplinary, integrative work. The lack of consensus on criteria for assessment of results is often ranked as a major practical difficulty of this kind of research. Despite many efforts to describe and characterize collaborative research on complex problems, conditions for success (including the very definition of “success”) remain to be rigorously grounded on actual cases. Toward this goal, we argue that a self-reflective process to identify and intervene on factors that foster or impede cooperative production of knowledge should be an essential component of integrated assessments involving scientists, practitioners and stakeholders

Estimating daily solar radiation in the Argentine Pampas

Solar radiation is an important input to crop growth models used for risk management and assessment purposes. Methods are explored to estimate daily solar radiation in the Argentine Pampas, one of the most important agricultural areas in the world. Two scenarios are considered: (i) sunshine duration data are available for a given location, or (ii) only daily temperature (minimum and maximum) and precipitation records exist. If sunshine duration data are available, an association between this quantity and atmospheric transmissivity yields daily radiation estimates with a root mean square error (RMSE) of 1.5 MJ m −2 per day. Without sunshine duration records, daily temperature and precipitation can be used to estimate atmospheric transmittance and then compute daily radiation values. A model linking predictors that are proxies of cloudiness and atmospheric humidity to atmospheric transmittance was fitted using Generalized Additive Models (GAMs), a modern statistical technique that does not assume any a priori functional forms for the association between predictors and predictand. The errors in radiation estimates using temperature and precipitation are larger (RMSE of 3.2 MJ m −2 per day) than those derived from sunshine duration, but they are comparable to results for other locations and methods. Most importantly, daily radiation estimates have small bias and the errors show no systematic patterns with season or other variables

Temporal variations in the separation of Brazil and Malvinas Currents

The separation of the Brazil and Malvinas (Falkland) Currents from the western boundary is explored with the use of satellite and drifter data. The location of the separation of these boundary currents from the continental margin over a multiyear period is determined by digitizing the crossing of the surface thermal front indicative of each feature with the 1000 m isobath. Three years (July 1984 to June 1987) of 1 km resolution AVHRR data collected by the Argentina Meteorological Service and 4 years of lower resolution Global Retrieval Tape (GRT) data were used to generate a total time series extending from November 1981 to June 1987; i.e. 5 1 2 years. The mean latitudes of separation from the shelf break are 35.8 ± 1.1° for the Brazil Current and 38.6 ± 0.9° for the Malvinas Current. The along-coast ranges of the separation positions, 930 and 850 km, respectively, are quite large relative to similar statistics for the Gulf Stream or Kuroshio. Observed temporal variability suggests cyclical excursions of the currents along the coast at semi-annual and annual periods, although there is considerable interannual variation in the signal. Drifter trajectories overlaid on satellite images demonstrate events associated with the annual transition in 1984–1985. Shorter time-scale perturbations in the currents' separation latitudes occur in the 30–60 day band, which corresponds to the mesoscale eddy field. The connection of the variation in the separation with various possible forcing mechanisms is briefly discussed, along with the problem of gaining a theoretical understanding of this dynamic situation. Finally, the extensions of the two currents into the South Atlantic interior are described statistically using the high resolution data set