Temporal and spatial variations in phytoplankton productivity in surface waters of a warm-temperate, monomictic lake in New Zealand

Surface phytoplankton productivity measurements were carried out in morphologically complex Lake Rotoiti with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. Measurements were carried out monthly at two depths at each of three morphologically diverse stations for 1 year throughout the lake. Productivity at the surface of the shallow embayment was significantly higher in most months of the year compared with the surface of the other two stations but there were no significant differences from September to December 2004. There were no relationships between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between sites found in this study indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole lake productivity estimates may vary greatly depending on the location and depth of productivity measurements

Effects of Diffusion on Photocurrent Generation in Single-Walled Carbon Nanotube Films

We have studied photocurrent generation in large carbon nanotube (CNT) films using electrodes with different spacings. We observe that the photocurrent depends strongly on the position of illumination, with maximum observed response occurring upon illumination at the electrode edges. The rate of change of the response decays exponentially, with the fastest response occurring for samples with the smallest electrode spacing. We show that the time response is due to charge carrier diffusion in low-mobility CNT films

The promise of community-based participatory research for health equity: a conceptual model for bridging evidence with policy.

Insufficient attention has been paid to how research can be leveraged to promote health policy or how locality-based research strategies, in particular community-based participatory research (CBPR), influences health policy to eliminate racial and ethnic health inequities. To address this gap, we highlighted the efforts of 2 CBPR partnerships in California to explore how these initiatives made substantial contributions to policymaking for health equity. We presented a new conceptual model and 2 case studies to illustrate the connections among CBPR contexts and processes, policymaking processes and strategies, and outcomes. We extended the critical role of civic engagement by those communities that were most burdened by health inequities by focusing on their political participation as research brokers in bridging evidence and policymaking

Human Perceptions of Fairness in Algorithmic Decision Making: A Case Study of Criminal Risk Prediction

As algorithms are increasingly used to make important decisions that affect human lives, ranging from social benefit assignment to predicting risk of criminal recidivism, concerns have been raised about the fairness of algorithmic decision making. Most prior works on algorithmic fairness normatively prescribe how fair decisions ought to be made. In contrast, here, we descriptively survey users for how they perceive and reason about fairness in algorithmic decision making. A key contribution of this work is the framework we propose to understand why people perceive certain features as fair or unfair to be used in algorithms. Our framework identifies eight properties of features, such as relevance, volitionality and reliability, as latent considerations that inform people's moral judgments about the fairness of feature use in decision-making algorithms. We validate our framework through a series of scenario-based surveys with 576 people. We find that, based on a person's assessment of the eight latent properties of a feature in our exemplar scenario, we can accurately (> 85%) predict if the person will judge the use of the feature as fair. Our findings have important implications. At a high-level, we show that people's unfairness concerns are multi-dimensional and argue that future studies need to address unfairness concerns beyond discrimination. At a low-level, we find considerable disagreements in people's fairness judgments. We identify root causes of the disagreements, and note possible pathways to resolve them.Comment: To appear in the Proceedings of the Web Conference (WWW 2018). Code available at https://fate-computing.mpi-sws.org/procedural_fairness

Random Matrix Theory and the Fourier Coefficients of Half-Integral Weight Forms

Conjectured links between the distribution of values taken by the characteristic polynomials of random orthogonal matrices and that for certain families of L-functions at the centre of the critical strip are used to motivate a series of conjectures concerning the value-distribution of the Fourier coefficients of half-integral weight modular forms related to these L-functions. Our conjectures may be viewed as being analogous to the Sato-Tate conjecture for integral weight modular forms. Numerical evidence is presented in support of them.Comment: 28 pages, 8 figure

Influence of Surface Emissivity on the Heat Loss through the Wall Behind the Heater

AbstractThe paper presents a solution to a problem of heat transfer through the external wall region behind the heater, which is actively warming up and through which additional heat loses occur. Author developed a method for temperature calculations on the inner surface of the external wall region behind the heater, that takes into account inner wall surface material reflection coefficient. According to the author's conducted calculations it is possible to show, that due to application of a baffle, made of aluminum foil with low emission coefficient, temperature of the wall surface behind the heater declines as well as the heat loses through this part of the wall. Calculations made by proposed method allows us to estimate efficiency of materials with low surface emission coefficient application in the exterior walls

Technology Transfer: A Contact Sport

Technology transfer is a dynamic process, involving dynamic people as the bridge between NASA Langley Research Center and the outside world. This bridge, for nonaerospace applications, is known as the Technology Applications Group. The introduction of new innovations and expertise where they are needed occurs through a 'push' and 'pull' process. A 'push' occurs when a new technology is first developed with high commercial potential and then a company is found to licence or further develop the technology. The 'pull' process occurs through problem statements. A company or group will submit a written statement of what they need and the shortcomings of commercially available technology. The Technology Transfer Team (T3) reviews these problem statements and decides where NASA LaRC can offer assistance. A researcher or group of researchers are then identified who can help solve the problem and they are put in contact with the company. Depending upon the situation in either method, a Space Act Agreement (SAA), or outline of the responsibilities for each party, is developed

Asymmetric Interspecific Competition Between Specialist Herbivores That Feed on Tamarisk in Western Colorado

Four closely related species of leaf beetles (Diorhabda spp.; Coleoptera:Chrysomelidae) have been introduced into the western United States as biocontrol agents for the invasive Eurasian shrub tamarisk (Tamarix spp.; Violales:Tamaricaceae). These beetles have since continued to spread and establish throughout the western United States. Another exotic insect, the tamarisk leafhopper (Opsius stactogalus, Fieber;Hemiptera: Cicadellidae), had previously become established in these areas and now shares tamarisk as a host plant with the beetles. To assess more carefully the potential for interactions between leafhoppers and beetles, field censuses and cage studies were conducted to determine the phenologies and potential interactions of O. stactogolus and D. carinulata when attacking Tamarix ramosissima (Ledebour) in western Colorado. The leafhopper underwent development through at least three generations per season, whereas the beetle was shown to develop through two generations per season. Variation in leafhopper abundance was associated with the extent and type of foliar damage to tamarisk trees. Individual trees with greatest D. carinulata abundances and subsequent defoliation had significantly reduced O. stactogalus abundances thereafter. Abundance of O. stactogalus was also shown to vary significantly among tamarisk plants in cage settings where leafhoppers were given the choice of potted tamarisk plants with ~50% damage to foliage from D. carinulata versus undamaged plants. In contrast, D. carinulata abundance was not shown to differ strongly in response to O. stactogalus damage in the field or in cage experiments. Field results across sites, however, showed similar trends of reduced beetle abundance on plants more heavily attacked by leafhoppers, and larval growth tests suggested slight reductions in larval pupation and adult emergence of D. carinulata when grown on O. stactogalus-damaged tamarisk. It is not clear if slight tendencies in D. carinulata abundance along with much stronger responses in O. stactogalus abundance were the result of limited plant material, rather than an induced plant defense. It is clear, however, that these specialist herbivores are interacting in an asymmetric competitive fashion while feeding on the same host plant