Voluntary Pollution Abatement and Regulation

Altruism, Voluntary Pollution Abatement, Regulation, Environmental Economics and Policy, Q52, Q58, K32,

The Cost of Unconventional Gas Extraction: A Hedonic Analysis

We focus on identification and estimation of potentially negative environmental impacts of unconventional natural gas extraction on property values in the United States and advance previous research by contributing new data and new identification strategies for isolating these potential impacts. Our study area consists of two counties in Pennsylvania that are home to large amounts of unconventional natural gas extraction but are otherwise isolated from other resource extraction industries or large urban areas. We deploy parametric, semi-parametric, and matching hedonic regression models that include recent quasi-experimental methods and, in contrast to previous research and much popular intuition, we fail to find robust significance that negative environmental externalities of natural gas extraction are manifested in nearby property values. While there may be plausible risks associated with unconventional natural gas extraction, we do not find consistent evidence to suggest that these risks significantly affect nearby property values

Evaluating the environmental Kuznets curve

We examine the empirical evidence for an environmental Kuznets curve using a semiparametric smooth coefficient regression model that allows us to incorporate flexibility in the parameter estimates, while maintaining the basic econometric structure that is typically used to estimate the pollution-income relationship. This allows us to assess the sensitivity to parameter heterogeneity of typical parametric models used to estimate the relationship between pollution and income, as well as identify why the results from such models are seldom found to be robust. Our results confirm that the resulting relationship between pollution and income is fragile; we show that the estimated pollution-income relationship depends substantially on the heterogeneity of the slope coefficients and the parameter values at which the relationship is evaluated. Different sets of parameters obtained from the semiparametric model give rise to many different shapes for the pollution-income relationship that are commonly found in the literature

The economic implications of clustering on Hispanic entrepreneurship in the US

This article assesses the effect of Hispanic clustering on Hispanic self-employment in the US and the extent to which endogenous social factors within a cluster may encourage Hispanics to start a business. We address key identification issues in the clustering literature by applying a series of robust econometric techniques to US census data. The study provides empirical evidence on the role of Hispanic clustering on Hispanic entrepreneurship. This article also tackles the constructs of Hispanic entrepreneurial heterogeneity and suggests the clustering of second-generation Hispanics as a potential indicator of the Hispanic entrepreneurial environment. The study derives insight on the economic implications of Hispanic clustering and its benefits and suggests policy recommendations to promote success among Hispanic entrepreneurs. We propose that generational differences across Hispanics is not merely an ethnic control variable, but rather an important factor for the design of strategies and incentives at the federal, state, and local level

Cladistic Parsimony Analysis of Internal Transcribed Spacer Region (nrDNA) Sequences of Bouteloua and Relatives (Gramineae: Chloridoideae)

Chloridoideae) employing cladistic parsimony analysis of nuclear ribosomal internal transcribed spacer region (ITS1 + 5.8S + ITS2) DNA sequences. Included were Aegopogon (2 of 4 species), Bouteloua (34 of 42), Buchloë (1 of 1), Buchlomimus (1 of 1), Cathestecum (2 of 4), Cyclostachya (1 of 1), Griffithsochloa (1 of 1), Hilaria (1 of 7), Opizia (2 of 2), Pentarrhaphis (2 of 3), Pleuraphis (2 of 3), Pringleochloa (1 of 1), Soderstromia (1 of 1), and five outgroup genera/species for a total of I8 genera, 56 species, and ten varieties. In all, the ITS region of 72 plants was sequenced and analyzed utilizing PAUP. Aegopogon, the Hilaria-Pleuraphis clade, and Tragus (an outgroup representative) formed a tetratomy with a clade containing the remaining ingroup taxa. Neither Bouteloua nor its two subgenera, Bouteloua and Chondrosium, were found to be monophyletic. Bouteloua chondrosioides was sister to Opizia. Bouteloua rigidiseta formed a clade with Buchlomimus and Pringleochloa. Bouteloua eludens formed a clade with Buchloë, Cathestecum, Griffithsochloa, Pentarrhaphis, and Soderstromia. Bouteloua annua and B. aristidoides (subg. Bouteloua) formed a clade with B. eriopoda, B. eriostachya, B. hirsuta, and B. pectinata (subg. Chondrosium). Bouteloua juncea, which has been included in the B. curtipendula complex, was not a member of that clade. No new circumscriptions were proposed, although recognition of Bouteloua in the broad sense, with Chondrosium reduced to synonymy, was advocated. The findings suggested homoplasy in morphological, anatomical, and breeding system traits

Automated CT and MRI Liver Segmentation and Biometry Using a Generalized Convolutional Neural Network.

PurposeTo assess feasibility of training a convolutional neural network (CNN) to automate liver segmentation across different imaging modalities and techniques used in clinical practice and apply this to enable automation of liver biometry.MethodsWe trained a 2D U-Net CNN for liver segmentation in two stages using 330 abdominal MRI and CT exams acquired at our institution. First, we trained the neural network with non-contrast multi-echo spoiled-gradient-echo (SGPR)images with 300 MRI exams to provide multiple signal-weightings. Then, we used transfer learning to generalize the CNN with additional images from 30 contrast-enhanced MRI and CT exams.We assessed the performance of the CNN using a distinct multi-institutional data set curated from multiple sources (n = 498 subjects). Segmentation accuracy was evaluated by computing Dice scores. Utilizing these segmentations, we computed liver volume from CT and T1-weighted (T1w) MRI exams, and estimated hepatic proton- density-fat-fraction (PDFF) from multi-echo T2*w MRI exams. We compared quantitative volumetry and PDFF estimates between automated and manual segmentation using Pearson correlation and Bland-Altman statistics.ResultsDice scores were 0.94 ± 0.06 for CT (n = 230), 0.95 ± 0.03 (n = 100) for T1w MR, and 0.92 ± 0.05 for T2*w MR (n = 169). Liver volume measured by manual and automated segmentation agreed closely for CT (95% limit-of-agreement (LoA) = [-298 mL, 180 mL]) and T1w MR (LoA = [-358 mL, 180 mL]). Hepatic PDFF measured by the two segmentations also agreed closely (LoA = [-0.62%, 0.80%]).ConclusionsUtilizing a transfer-learning strategy, we have demonstrated the feasibility of a CNN to be generalized to perform liver segmentations across different imaging techniques and modalities. With further refinement and validation, CNNs may have broad applicability for multimodal liver volumetry and hepatic tissue characterization

Mass Segregation in the Globular Cluster Palomar 5 and its Tidal Tails

We present the stellar main sequence luminosity function (LF) of the disrupted, low-mass, low-concentration globular cluster Palomar 5 and its well-defined tidal tails, which emanate from the cluster as a result of its tidal interaction with the Milky Way. The results of our deep (B ~ 24.5) wide-field photometry unequivocally indicate that preferentially fainter stars were removed from the cluster so that the LF of the cluster's main body exhibits a significant degree of flattening compared to other globular clusters. There is clear evidence of mass segregation, which is reflected in a radial variation of the LFs. The LF of the tidal tails is distinctly enhanced with faint, low-mass stars. Pal 5 exhibits a binary main sequence, and we estimate a photometric binary frequency of roughly 10%. Also the binaries show evidence of mass segregation with more massive binary systems being more strongly concentrated toward the cluster center.Comment: 14 pages, 12 figures, accepted for publication in the Astronomical Journa

Should all microfinance institutions mobilize microsavings? Evidence from economies of scope

Published version of an article from the journal: Empirical Economics. Also available from the publisher on SpringetLink: http://dx.doi.org/10.1007/s00181-014-0861-3We extend a recently developed generalized local polynomial estimator into a semiparametric smooth coefficient framework to estimate a generalized cost function. The advantage of the generalized local polynomial approach is that we can simultaneously choose the degree of polynomial for each continuous nonparametric regressor and the bandwidths via data-driven methods. We provide estimates of scope economies from the joint production of microloans and microdeposits for a dataset of Microfinance Institutions from over 50 countries. Our approach allows analysis on all Microfinance Institutions rather than only those offering just microloans. Moreover, the smooth coefficient estimator provides a general interface in which to account for both direct and indirect environmental factors. We find substantial scope economies in general, of about 10% at the median, as well as evidence that economies of scope vary across the type of services and country in which the MFIs operate, suggesting key insights into policy prescriptions

Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of HF signals with microradian precision

Precision phase readout of optical beat note signals is one of the core techniques required for intersatellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of $\mu \textrm{rad}/\sqrt{\textrm{Hz}}$ at frequencies between $0.1\,\textrm{mHz}$ and $1\,\textrm{Hz}$. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, that was developed in the scope of an ESA technology development activity.Comment: submitted to Review of Scientific Instruments on April 30th 201

Phylogenetics of Chloridoideae (Gramineae): a Preliminary Study Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL–F Sequences

The phylogeny of Chloridoideae (Gramineae) was inferred from parsimony analyses of DNA sequences from two genomes—the chloroplast trnL intron, trnL 3\u27 exon, and trnL–F intergenic spacer, and the nuclear ribosomal internal transcribed spacer region (ITS1 + 5.8S + ITS2). Eighty species representing 66 chloridoid genera were sampled, including all but four of the native New World genera. Analyses of the individual and combined data sets were performed. The phylogenies were found to be highly congruent. Of the four tribes and seven subtribes of Chloridoideae sensu Clayton and Renvoize (1986) whose phylogenetic status could be tested with our taxon sample, only Orcuttieae and Uniolinae were monophyletic. The phylogenies suggested significant homoplasy in morphological traits, including inflorescence type, number of florets per spikelet, and number of lemma nerves. We propose a new classification based on the three main clades in the phylogenies—tribes Cynodonteae, Eragrostideae, and Zoysieae. The Eragrostideae clade is well resolved and supported and is further divided into three subtribes, Cotteinae, Eragrostidinae, and Uniolinae. Cynodonteae include most of the genera in our study, but the clade is poorly resolved. However, a clade formed of Muhlenbergia and nine other genera is present in both phylogenies and is well resolved and supported. A number of interesting, well-supported relationships are evident in the phylogenies, including Pappophorum–Tridens flavus, Tragus–Willkommia, and Gouinia–Tridens muticus–Triplasis–Vaseyochloa. Except for Bouteloua, no genus represented by multiple species proved to be monophyletic in the phylogenies