Climate, Wildfire, and Erosion Ensemble Foretells More Sediment in Western USA Watersheds

The area burned annually by wildfires is expected to increase worldwide due to climate change. Burned areas increase soil erosion rates within watersheds, which can increase sedimentation in downstream rivers and reservoirs. However, which watersheds will be impacted by future wildfires is largely unknown. Using an ensemble of climate, fire, and erosion models, we show that postfire sedimentation is projected to increase for nearly nine tenths of watersheds by \u3e10% and for more than one third of watersheds by \u3e100% by the 2041 to 2050 decade in the western USA. The projected increases are statistically significant for more than eight tenths of the watersheds. In the western USA, many human communities rely on water from rivers and reservoirs that originates in watersheds where sedimentation is projected to increase. Increased sedimentation could negatively impact water supply and quality for some communities, in addition to affecting stream channel stability and aquatic ecosystems

Impact of Air Quality Regulations on Entrepreneurial Activity

The objective of this paper is to examine the impact of NAAQS non-attainment status on the entrepreneurial activity in a metropolitan statistical area (MSA). Most of the existing research on the relationship between non-attainment and the financial robustness of areas focuses on the big polluters (e.g., plastics, organic chemicals, steel smelting and refining, etc.), and examines how many of the big polluters failed or relocated, measured by the change in the number of plants/businesses when an area moved from attainment to non-attainment. Our paper will use a 306 MSA panel data set over the 1989-2003 timeframe, to address the question more comprehensively by looking at all industries, not just a targeted few polluters. Controlling for other time-variant confounding effects, such as population growth, per-capita income, tax rate changes, minimum wage rates, energy costs, regional inflation measures, and spatial phenomena (such as, natural disasters) we isolate the effect of non-attainment status on large polluters as well as the linkage industries. We show that if an area is designated non-attainment status in a particular year, it leads to a decline in the total number of business starts in the MSA in the following year. We also determine whether the impact of non-attainment varies across businesses of different sizes

Climate Change, Water Supply, and Agriculture in the Arid Western United States: Eighty Years of Agricultural Census Observations from Idaho

As the population and agricultural development in the U.S. expanded west throughout the 20th century, major water infrastructure projects were initiated in order to meet irrigation demand and to reduce the risk and uncertainty associated with highly variable water supplies.2 Agriculture in the arid and semi-arid western U.S. is particularly vulnerable to variability in water supply, and has evolved to rely heavily on major water infrastructure projects.3 In 2007, of the 57 million acres of irrigated cropland and pastureland in the U.S., nearly three-quarters was in the 17 western-most contiguous states; in 2008, irrigated agriculture applied 91.2 million acre-feet of water, with over four-fifths being used in the arid west

Gene-flow between populations of cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is highly variable between years

Both large and small scale migrations of Helicoverpa armigera Hübner in Australia were investigated using AMOVA analysis and genetic assignment tests. Five microsatellite loci were screened across 3142 individuals from 16 localities in eight major cotton and grain growing regions within Australia, over a 38-month period (November 1999 to January 2003). From November 1999 to March 2001 relatively low levels of migration were characterized between growing regions. Substantially higher than average gene-flow rates and limited differentiation between cropping regions characterized the period from April 2001 to March 2002. A reduced migration rate in the year from April 2002 to March 2003 resulted in significant genetic structuring between cropping regions. This differentiation was established within two or three generations. Genetic drift alone is unlikely to drive genetic differentiation over such a small number of generations, unless it is accompanied by extreme bottlenecks and/or selection. Helicoverpa armigera in Australia demonstrated isolation by distance, so immigration into cropping regions is more likely to come from nearby regions than from afar. This effect was most pronounced in years with limited migration. However, there is evidence of long distance dispersal events in periods of high migration (April 2001–March 2002). The implications of highly variable migration patterns for resistance management are considered.K.D. Scott, K.S. Wilkinson, N. Lawrence, C.L. Lange, L.J. Scott, M.A. Merritt, A.J. Lowe and G.C Graha

The Determinants of Credit Allocations in a Market-Based Trading System: Evidence from the RECLAIM Program

This paper examines the determinants of emission credit allocations under the Regional Clean Air Incentives Market (RECLAIM) - a program aimed at reducing nitrogen oxides (NOX) and sulfur oxides (SOX) - in the greater Los Angeles area. Our results suggest that deviations in the allocation of emission credits can be systematically explained by firm-level factors and the location of the facility. Our results also indicate that deviations in the allocation of emission credits may have been made in an attempt to regulate toxics, and that certain industries were protected in the early stages of the program

Measuring the Effects of the Clean Air Act Amendments on Ambient PM\u3csub\u3e10\u3c/sub\u3e Concentrations: The Critical Importance of a Spatially Disaggregated Analysis

We examine the effects of the 1990 Clean Air Act Amendments (CAAAs) on ambient concentrations of PM10 in the United States between 1990 and 2005. We find that non-attainment designation has no effect on the \u27average monitor\u27 in non-attainment counties, after controlling for weather and socioeconomic characteristics at the county level. In sharp contrast, if we allow for heterogeneous treatment by type of monitor and county, we do find that the 1990 CAAAs produced substantial effects. Our best estimate suggests that PM10 concentrations at monitors with concentrations above the national annual standard dropped by between 7µg/m3 and 9µg/m3, which is roughly equivalent to a 11-14% drop. We also show that monitors which were in violation of the daily standard experience two fewer days in violation of the daily standard the following year. Empirical results suggest that this treatment effect is independent of whether the EPA has finalized the non-attainment designation

Comparing Differences for Non-Introgressing Genes in Chickadees

Hybridization between species plays a very important role in the overall evolutionary history of many taxa. The study of hybrid zones can also provide insight into how species are responding to environmental factors such as climate change and changes in species interactions. The hybrid zone between the northern black-capped chickadee (Poecile atricapillus) and the southern Carolina chickadee (Poecile carolinensis) provides an insight into how hybridization is affecting two distinct species. As climate change worsens and Carolina chickadees are pushed more north to avoid sweltering temperatures, the hybrid zone is actively moving with them about 1 kilometer every year. Black-capped and Carolina hybrids have reduced fitness in the wild. Hybrids tend to have higher basal metabolic rates, less muscle growth, and less neuron growth to prepare for winter caching. There are genes that are not introgressed well into hybrids, and exploring why those genes are not introgressing could give an insight into why hybrids have such low survival rates. Our goal was to look at what functions those genes may have, and to see if the genes that don’t introgress have lots of differences between the two chickadee species. We used full genome transcripts from both black-capped and Carolina chickadees to look at the differences in the non-introgressing genes. Using a list of genes from the most to least non-introgressing, we pulled the top ten sequences from black-capped and Carolina transcripts and aligned them using the program Geneious. We also pulled ten random genes from the full transcripts to align and compare as a control. We calculated the percent that matched in nucleotides for each alignment. After getting this percentage, we calculated the mean percent for both the top ten non-introgressing genes and the ten random genes. The mean percent for the top ten genes was 97.5%, and the mean for the random genes was 98.7%. After determining that the data set did not follow a normal distribution using the Shapiro-Wilks tests, we used a Wilcoxon ranked sum test to calculate a p-value. With a p-value of 0.0169, the difference in means between the two gene sets is significant. This suggests that there might be some differences in the genes that do not allow them to be inherited by hybrids, and it upholds reproductive isolation between the black-capped and Carolina chickadee species

P53-dependent apoptosis modulates the cellular response to oncogenes and the cytotoxicity of anticancer agents

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 1994.GRSN 680118Includes bibliographical references (leaves 226-254).by Scott William Lowe.Ph.D

Decoding information from neural populations in the visual cortex

Visual perception in mammals is made possible by the visual system and the visual cortex. However, precisely how visual information is coded in the brain and how training can improve this encoding is unclear. The ability to see and process visual information is not an innate property of the visual cortex. Instead, it is learnt from exposure to visual stimuli. We first considered how visual perception is learnt, by studying the perceptual learning of contrast discrimination in macaques. We investigated how changes in population activity in the visual cortices V1 and V4 correlate with the changes in behavioural response during training on this task. Our results indicate that changes in the learnt neural and behavioural responses are directed toward optimising the performance on the training task, rather than a general improvement in perception of the presented stimulus type. We report that the most informative signal about the contrast of the stimulus within V1 and V4 is the transient stimulus-onset response in V1, 50 ms after the stimulus presentation begins. However, this signal does not become more informative with training, suggesting it is an innate and untrainable property of the system, on these timescales at least. Using a linear decoder to classify the stimulus based on the population activity, we find that information in the V4 population is closely related to the information available to the higher cortical regions involved with decision making, since the performance of the decoder is similar to the performance of the animal throughout training. These findings suggest that training the subject on this task directs V4 to improve its read out of contrast information contained in V1, and cortical regions responsible for decision making use this to improve the performance with training. The structure of noise correlations between the recorded neurons changes with training, but this does not appear to cause the increase in behavioural performance. Furthermore, our results suggest there is feedback of information about the stimulus into the visual cortex after 300 ms of stimulus presentation, which may be related to the high-level percept of the stimulus within the brain. After training on the task, but not before, information about the stimulus persists in the activity of both V1 and V4 at least 400 ms after the stimulus is removed. In the second part, we explore how information is distributed across the anatomical layers of the visual cortex. Cortical oscillations in the local field potential (LFP) and current source density (CSD) within V1, driven by population-level activity, are known to contain information about visual stimulation. However the purpose of these oscillations, the sites where they originate, and what properties of the stimulus is encoded within them is still unknown. By recording the LFP at multiple recording sites along the cortical depth of macaque V1 during presentation of a natural movie stimulus, we investigated the structure of visual information encoded in cortical oscillations. We found that despite a homogeneous distribution of the power of oscillations across the cortical depth, information was compartmentalised into the oscillations of the 4 Hz to 16 Hz range at the granular (G, layer 4) depths and the 60Hz to 170Hz range at the supragranular (SG, layers 1–3) depths, the latter of which is redundant with the population-level firing rate. These two frequency ranges contain independent information about the stimulus, which we identify as related to two spatiotemporal aspects of the visual stimulus. Oscillations in the visual cortex with frequencies <40 Hz contain information about fast changes in low spatial frequency. Frequencies >40 Hz and multi-unit firing rates contain information about properties of the stimulus related to changes, both slow and fast, at finer-grained spatial scales. The spatiotemporal domains encoded in each are complementary. In particular, both the power and phase of oscillations in the 7 Hz to 20Hz range contain information about scene transitions in the presented movie stimulus. Such changes in the stimulus are similar to saccades in natural behaviour, and this may be indicative of predictive coding within the cortex

Housing Market Effects of Inclusionary Zoning

This article presents an empirical analysis of the effects of inclusionary zoning policies on housing prices and starts in California during the period from 1988 through 2005. The analysis compares cities with and without such policies and isolates the effects of inclusionary zoning programs by carefully controlling for spatial and temporal conditions, such as the neighborhood or school district within which the house is located and changing market conditions over time. The analysis found that inclusionary zoning policies had measurable effects on housing markets in jurisdictions that adopt them; specifically, the price of single-family houses increases and the size of single-family houses decreases. The analysis also found that, although the cities with such programs did not experience a significant reduction in the rate of single-family housing starts, they did experience a marginally significant increase in multifamily housing starts. The magnitude of this shift varied with the stringency of the inclusionary requirements. Finally, the analysis found that the size of market-rate houses in cities that adopted inclusionary zoning increased more slowly than in cities without such programs. The results are fully consistent with economic theory and demonstrate that inclusionary zoning policies do not come without costs