317 research outputs found
Understanding Informed Design through Trade-Off Decisions With an Empirically-Based Protocol for Students and Design Educators
Trade-off decisions, which necessitate striking a balance between two or more desirable but competing features, are a crucial part of design practice. However, they are known to be difficult for student designers to make. While designers, educators, and researchers have numerous methods to assess the quality of design artifacts, these methods are not necessarily easy to use, nor do they indicate design competency. Moreover, they are not grounded in a definition of engineering design. The objectives of this study were twofold. First, we developed a protocol to depict design artifact quality through the lens of design trade-off decisions. We aimed to produce a protocol that:(1) encompasses multiple complementary and competing dimensions, (2) can be applied consistently and systematically, and (3) indicates design competency. We conceptualized a quantitative representation of the degree to which a design artifact addresses human, technical, and economic requirements called the Trade-off Value Protocol. Second, we tested the Trade-off Value Protocol by applying it to 398 middle school studentsâ design artifacts of energy-efficient homes. We used an etic approach of thematic analysis to identify the patterns of variation therein. We found five distinct patterns of variation in the set of student design artifacts, which suggested certain trends in the way that students address design dimensions and demonstrate varying levels of design competency. The Trade-off Value Protocol isolates an important feature of design competency with which beginning designers often struggle and could be a tool for educators to help students become more informed designers
Evapotranspiration in the Nile Basin: Identifying Dynamics, Trends, and Drivers 2002-2011
Analysis of the relationship between evapotranspiration (ET) and its natural and anthropogenic drivers is critical in water-limited basins such as the Nile. The spatiotemporal relationships of ET with rainfall and vegetation dynamics in the Nile Basin during 2002â2011 were analyzed using satellite-derived data. Non-parametric statistics were used to quantify ET-rainfall interactions and trends across land cover types and subbasins. We found that 65% of the study area (2.5 million km2) showed significant (p \u3c 0.05) positive correlations between monthly ET and rainfall, whereas 7% showed significant negative correlations. As expected, positive ET-rainfall correlations were observed over natural vegetation, mixed croplands/natural vegetation, and croplands, with a few subbasin-specific exceptions. In particular, irrigated croplands, wetlands and some forests exhibited negative correlations. Trend tests revealed spatial clusters of statistically significant trends in ET (6% of study area was negative; 12% positive), vegetation greenness (24% negative; 12% positive) and rainfall (11% negative; 1% positive) during 2002â2011. The Nile Delta, Ethiopian highlands and central Uganda regions showed decline in ET while central parts of Sudan, South Sudan, southwestern Ethiopia and northeastern Uganda showed increases. Except for a decline in ET in central Uganda, the detected changes in ET (both positive and negative) were not associated with corresponding changes in rainfall. Detected declines in ET in the Nile delta and Ethiopian highlands were found to be attributable to anthropogenic land degradation, while the ET decline in central Uganda is likely caused by rainfall reduction
A New Approach to Evaluate and Reduce Uncertainty of Model-Based Biodiversity Projections for Conservation Policy Formulation
Biodiversity projections with uncertainty estimates under different climate, land-use, and policy scenarios are essential to setting and achieving international targets to mitigate biodiversity loss. Evaluating and improving biodiversity predictions to better inform policy decisions remains a central conservation goal and challenge. A comprehensive strategy to evaluate and reduce uncertainty of model outputs against observed measurements and multiple models would help to produce more robust biodiversity predictions. We propose an approach that integrates biodiversity models and emerging remote sensing and in-situ data streams to evaluate and reduce uncertainty with the goal of improving policy-relevant biodiversity predictions. In this article, we describe a multivariate approach to directly and indirectly evaluate and constrain model uncertainty, demonstrate a proof of concept of this approach, embed the concept within the broader context of model evaluation and scenario analysis for conservation policy, and highlight lessons from other modeling communities
Spectroscopic Evidence for Interstellar Ice in Comet Hyakutake
Volatile compounds in comets are the most pristine materials surviving from the time of formation of the Solar System, and thus potentially provide information about conditions that prevailed in the primitive solar material. Moreover, comets may have supplied a substantial fraction of the volatiles on the terrestrial planets, perhaps including organic compounds that played a role in the origin of life on Earth. Here we report the detection of hydrogen isocyanide (HNC) in comet Hyakutake. The abundance of HNC relative to hydrogen cyanide (HCN) is very similar to that observed in quiescent interstellar molecular clouds, and quite different from the equilibrium ratio expected in the outermost solar nebula, where comets are thought to form. Such a departure from equilibrium has long been considered a hallmark of gas-phase chemical processing in the interstellar medium, suggesting that interstellar gases have been incorporated into the comet's nucleus, perhaps as ices frozen onto interstellar grains. If this interpretation is correct, our results should provide constraints on the temperature of the solar nebula, and the subsequent chemical processes that occurred in the region where comets formed
Deriving Hourly Evapotranspiration Rates with SEBS: A Lysimetric Evaluation
Numerous energy balance (EB) algorithms have been developed to use remote sensing data for mapping evapotranspiration (ET) on a regional basis. Adopting any single or combination of these models for an operational ET remote sensing program requires a thorough evaluation. The Surface Energy Balance System (SEBS) was evaluated for its ability to estimate hourly ET rates of summer tall and short crops grown in the Texas High Plains by using 15 Landsat 5 Thematic Mapper scenes acquired during 2006 to 2009. Performance of SEBS was evaluated by comparing estimated hourly ET values with measured ET data from four large weighing lysimeters, each located at the center of a 4.3 ha field in the USDA-ARS Conservation and Production Research Laboratory in Bushland, TX. The performance of SEBS in estimating hourly ET was good for crops under both irrigated and dryland conditions. A locally derived, surface albedo-based soil heat flux (G) model further improved the G estimates. Root mean square error and mean bias error were 0.11 and â0.005 mm hâ1, respectively, and the NashâSutcliff model efficiency was 0.85 between the measured and calculated hourly ET. Considering the equal or better performance with a minimal amount of ancillary data as compared to with other EB algorithms, SEBS is a promising tool for use in an operational ET remote sensing program in the semiarid Texas High Plains. However, thorough sensitivity and error propagation analyses of input variables to quantify their impact on ET estimations for the major crops in the Texas High Plains under different agroclimatological conditions are needed before adopting the SEBS into operational ET remote sensing programs for irrigation scheduling or other purposes
Depression and alcohol use among the Dutch residential home elderly: Is there a shared vulnerability?
The purpose of this article is to investigate whether data from an older population sample would support the co-occurrence between depression and (problematic) alcohol use found in the general population and in clinical samples. Additionally, important predictors concerning these phenomena are identified in this population, by interviewing 156 inhabitants of five residential homes (mean age 84 years), using several questionnaires. The results showed that there is no link present between depression and alcohol use in this very old, mostly female population. Our results found a relation between the personality traits extraversion and openness to experience with both depression as well as alcohol use. Neuroticism was only related to depressive symptoms. Chronic diseases was related to non-alcohol use and parental problem drinking was found to be a risk factor for late life problem drinking. Future studies should aim at developing screening instruments for alcohol use in this population and, because of the importance of the personality traits, aim at developing or adapting of psychotherapeutic interventions fit for this population. Keywords: Depression, alcohol use, older adults, residential homes, personalit
Rate-Induced Transitions in Networked Complex Adaptive Systems: Exploring Dynamics and Management Implications Across Ecological, Social, and Socioecological Systems
Complex adaptive systems (CASs), from ecosystems to economies, are open
systems and inherently dependent on external conditions. While a system can
transition from one state to another based on the magnitude of change in
external conditions, the rate of change -- irrespective of magnitude -- may
also lead to system state changes due to a phenomenon known as a rate-induced
transition (RIT). This study presents a novel framework that captures RITs in
CASs through a local model and a network extension where each node contributes
to the structural adaptability of others. Our findings reveal how RITs occur at
a critical environmental change rate, with lower-degree nodes tipping first due
to fewer connections and reduced adaptive capacity. High-degree nodes tip later
as their adaptability sources (lower-degree nodes) collapse. This pattern
persists across various network structures. Our study calls for an extended
perspective when managing CASs, emphasizing the need to focus not only on
thresholds of external conditions but also the rate at which those conditions
change, particularly in the context of the collapse of surrounding systems that
contribute to the focal system's resilience. Our analytical method opens a path
to designing management policies that mitigate RIT impacts and enhance
resilience in ecological, social, and socioecological systems. These policies
could include controlling environmental change rates, fostering system
adaptability, implementing adaptive management strategies, and building
capacity and knowledge exchange. Our study contributes to the understanding of
RIT dynamics and informs effective management strategies for complex adaptive
systems in the face of rapid environmental change.Comment: 25 pages, 4 figures, 1 box, supplementary informatio
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