The effects of urbanization on floods in the Austin metropolitan area, Texas

This report looks at compiled data from 1956-1980 to "provide a technique for estimating the magnitude and frequency of flood-peak discharges at ungaged sites and to estimate the effects of changes in urbanization on flood peaks."The effects of urbanization on flood peaks in streams in the Austin metropolitan area were studied in two separate analyses. In the first analysis, annual peak discharge records at 13 streamflow-gaging sites were used to compute a recorded flood frequency relation for each site. Rainfall and streamflow data for 10 to 20 storms for each of these sites were used to calibrate a rainfall-runoff model in which a 55-year rainfall record was used to simulate 55 annual peak discharges. These simulated discharges also were used to develop a flood-frequency relation at each site. The flood-frequency relations from recorded and generated data were then combined by weighting the recorded flood frequency by the years of record at each site to produce a combined (or weighted) flood frequency at each site. Flood frequencies for all 13 sites were subsequently regressed against basin characteristics at each site to determine possible effects of urbanization. The regression analysis of the combined flood-frequency data for the 13 sites yielded an equation for estimating floods of a given recurrence interval at ungaged sites in the Austin area as a function of the contributing drainage area, the total impervious area percentage, and basin shape. The regression equation estimates that a near fully developed hypothetical drainage basin (impervious area percentage, 45) would have discharges for the 2- and 100-year recurrence interval that are 99 percent and 73 percent greater, respectively, than discharges for those frequencies from a rural drainage basin (impervious percentage, 0). In the second analysis, records at one streamflow-gaging site on Waller Creek were analyzed for changes in rainfall-runoff and flood-frequency relations due to urbanization. Annual peak discharges from 1956 to 1980 and data from a total of 80 storms at the Waller Creek site were analyzed. Both analyses showed increases comparable to those predicted using the equations developed from the 13-station analysis. The last 14 years of record (the near fully developed land-use stage for the Waller Creek analysis) at the two sites on Waller Creek were part of the 13-station analysis. The U.S. Geological Survey, in cooperation with the Texas Department of Water Resources began limited investigations of urban watersheds in Austin in 1954, with the installation of two streamflow-gaging stations and three recording rain gages in the Waller Creek watershed. In 1963, a streamflow gage and three recording rain gages were installed at Wilbarger Creek watershed, a rural area just north of Austin. In cooperation with the City of Austin, the urban study was expanded in 1975 to include additional streamflow and rainfall gaging stations and the collection of surface water-quality data. The number of streamflow-gaging stations increased from 2 to 25 and the number of recording rain gages increased from 3 to 31.Waller Creek Working Grou

Toward a social psychophysics of face communication

As a highly social species, humans are equipped with a powerful tool for social communication—the face, which can elicit multiple social perceptions in others due to the rich and complex variations of its movements, morphology, and complexion. Consequently, identifying precisely what face information elicits different social perceptions is a complex empirical challenge that has largely remained beyond the reach of traditional research methods. More recently, the emerging field of social psychophysics has developed new methods designed to address this challenge. Here, we introduce and review the foundational methodological developments of social psychophysics, present recent work that has advanced our understanding of the face as a tool for social communication, and discuss the main challenges that lie ahead

Beryllium 7 and Lead 210 in the western hemisphere Arctic atmosphere: Observations from three recent aircraft-based sampling programs

Concentrations of the natural radionuclides 7Be and 210Pb were determined in aerosol samples collected in the western hemisphere Arctic during the recent NOAA Arctic Gas and Aerosol Sampling Program (AGASP 3) and NASA Global Tropospheric Experiment/Arctic Boundary Layer Expeditions (GTE/ABLE 3A and ABLE 3B) missions. Beryllium 7 showed a free tropospheric concentration maximum between 4 and 5 km in the summer of 1990. Previous 7Be data obtained in the late 1950s and early 1960s also indicated a similar vertical distribution of 7Be near 70°N. Injection of stratospheric air through tropopause folds associated with the Arctic jet near 70°N appears to explain the presence of a layer of air near 4–5 km in the high Arctic free troposphere with elevated 7Be concentrations. The vertical distribution of 210Pb showed a distinct difference between the high-Arctic and sub-Arctic in the summer of 1988. At latitudes greater than 65°N, 210Pb concentrations at 3–6 km were elevated compared to those below 1 km. The reverse of this trend was observed near 60°N. These same vertical distributions were also apparent in aerosol SO42−, determined in separate aerosol samples collected on the same flights (Talbot et al., this issue). The results for 210Pb suggest that some of the difference between the summer troposphere in the high- and sub-Arctic is also due to enhanced stratosphere-troposphere exchange in the vicinity of the Arctic jet. These observations, and other findings from ABLE 3A presented in this issue, suggest that for some species the stratosphere may be a principal source influencing their distribution in the Arctic summer troposphere. For example, intrusions of stratospheric air constitute the dominant source term for tropospheric budgets of 7Be and ozone, and may be important in the 210Pb, SO42−, and NOybudgets. Further investigation, including determination of detailed 7Be and 210Pb distributions, is needed to quantify the stratospheric impact on the chemistry of the Arctic troposphere during the summer

In situ evidence for renitrification in the Arctic lower stratosphere during the polar aura validation experiment (PAVE)

In-situ measurements of nitric acid (HNO3), ozone (O3), and nitrous oxide (N2O) were made from the NASA DC-8 during the Polar Aura Validation Experiment in January/February 2005. In the lower stratosphere (9–12.5 km, potential temperature 300–350 K) characteristic compact relationships were observed between all three gases. The ratio HNO3/O3 averaged 3.5 (±0.7) ppt/ppb. Samples with enhanced HNO3/O3 (\u3e4.0) were most abundant under the edge of the Arctic Polar vortex in airmasses with enhanced mixing ratios of both gases (\u3e400 ppb O3 and \u3e2000 ppt HNO3) and reduced mixing ratios of N2O (\u3c305 ppb), indicating air from higher levels in the stratosphere. Relationships to N2O in the anomalous samples under the vortex edge indicate that increases in HNO3/O3 reflect renitrification at DC-8 flight levels, with no indication of significant O3 loss. Renitrified air was only observed at potential temperatures above 340 K, and was most abundant on the PAVE flights on 27 and 29 January

Four not six: revealing culturally common facial expressions of emotion

As a highly social species, humans generate complex facial expressions to communicate a diverse range of emotions. Since Darwin’s work, identifying amongst these complex patterns which are common across cultures and which are culture-specific has remained a central question in psychology, anthropology, philosophy, and more recently machine vision and social robotics. Classic approaches to addressing this question typically tested the cross-cultural recognition of theoretically motivated facial expressions representing six emotions, and reported universality. Yet, variable recognition accuracy across cultures suggests a narrower cross-cultural communication, supported by sets of simpler expressive patterns embedded in more complex facial expressions. We explore this hypothesis by modelling the facial expressions of over 60 emotions across two cultures, and segregating out the latent expressive patterns. Using a multi-disciplinary approach, we first map the conceptual organization of a broad spectrum of emotion words by building semantic networks in two cultures. For each emotion word in each culture, we then model and validate its corresponding dynamic facial expression, producing over 60 culturally valid facial expression models. We then apply to the pooled models a multivariate data reduction technique, revealing four latent and culturally common facial expression patterns that each communicates specific combinations of valence, arousal and dominance. We then reveal the face movements that accentuate each latent expressive pattern to create complex facial expressions. Our data questions the widely held view that six facial expression patterns are universal, instead suggesting four latent expressive patterns with direct implications for emotion communication, social psychology, cognitive neuroscience, and social robotics

“Waiting for Godot”- Restructuring on Small Family Farms

This paper examines the extent to which favourable off-farm labour market conditions coupled with growth in land values have contributed to the observed resilience of small scale family farms. We use data from Northern Ireland and employ farm household optimisation models to analyse household decision making processes that contribute to the observed inertia in farm structure. The analysis indicates that farm household behaviour is influenced not just by current farm income, but also expected capital asset returns. Increased wealth, associated with continuing land ownership, gives rise to the proposition that the link between off-farm incomes, increased land values and remaining in farming may be associated with farmers pursuing wealth maximizing objectives, whilst still maintaining a rural way of life. Alongside increased wealth through land ownership the farm household model quantifies the importance of off-farm income removing the pressure from farming income to fund all family consumption needs. This enables households to sustain low-income farming activities in order to pursue other objectives such as wealth management (including tax efficient transfer of wealth) and lifestyle. Consequently, the results indicate that the survival of small-scale family farms may be much less sensitive to agricultural support policies than has been commonly suggested. In an extension that explores the effects of the recent economic turbulence due to the ‘credit crunch’ we find that the households remain resilient even when subjected to a protracted period of reduced off-farm employment.Farm households, resilience, wealth accumulation, off-farm income, Consumer/Household Economics, Productivity Analysis, C61, Q12,

Value added or misattributed? A multi-institution study on the educational benefit of labs for reinforcing physics content

Instructional labs are widely seen as a unique, albeit expensive, way to teach scientific content. We measured the effectiveness of introductory lab courses at achieving this educational goal across nine different lab courses at three very different institutions. These institutions and courses encompassed a broad range of student populations and instructional styles. The nine courses studied had two key things in common: the labs aimed to reinforce the content presented in lectures, and the labs were optional. By comparing the performance of students who did and did not take the labs (with careful normalization for selection effects), we found universally and precisely no added value to learning from taking the labs as measured by course exam performance. This work should motivate institutions and departments to reexamine the goals and conduct of their lab courses, given their resource-intensive nature. We show why these results make sense when looking at the comparative mental processes of students involved in research and instructional labs, and offer alternative goals and instructional approaches that would make lab courses more educationally valuable.Comment: Accepted to Phys Rev PE

PrAGMATiC: a Probabilistic and Generative Model of Areas Tiling the Cortex

Much of the human cortex seems to be organized into topographic cortical maps. Yet few quantitative methods exist for characterizing these maps. To address this issue we developed a modeling framework that can reveal group-level cortical maps based on neuroimaging data. PrAGMATiC, a probabilistic and generative model of areas tiling the cortex, is a hierarchical Bayesian generative model of cortical maps. This model assumes that the cortical map in each individual subject is a sample from a single underlying probability distribution. Learning the parameters of this distribution reveals the properties of a cortical map that are common across a group of subjects while avoiding the potentially lossy step of co-registering each subject into a group anatomical space. In this report we give a mathematical description of PrAGMATiC, describe approximations that make it practical to use, show preliminary results from its application to a real dataset, and describe a number of possible future extensions

The preservation of atmospheric nitrate in snow at Summit, Greenland

There is great interest in using nitrate NO3 isotopic composition in ice cores to track the history of precursor nitrogen oxides (NOx = NO + NO2) in the atmosphere. Nitrate NO3 however can be lost from the snow by surface processes, such as photolysis back to NOx upon exposure to sunlight, making it difficult to interpret records of NO3 as a tracer of atmospheric NOx loading. In a campaign consisting of two field seasons (May–June) at Summit, Greenland, high temporal frequency surface snow samples were collected and analyzed for the oxygen isotopic composition of NO3. The strong, linear relationship observed between the oxygen isotopes of NO3 in both 2010 and 2011, is difficult to explain in the presence of significant post depositional processing of NO3 unless several unrelated variables change in concert. Therefore, the isotopic signature of NO3 in the snow at Summit is most feasibly explained as preserved atmospheric NO3 deposition