The uneasy case for lower Parking Standards

Minimum parking requirements are the norm for urban and suburban development in the United States (Davidson and Dolnick (2002)). The justification for parking space requirements is that overflow parking will occupy nearby street or off-street parking. Shoup (1999) and Willson (1995) provides cases where there is reason to believe that parking space requirements have forced parcel developers to place more parking than they would in the absence of parking requirements. If the effect of parking minimums is to significantly increase the land area devoted to parking, then the increase in impervious surfaces would likely cause water quality degradation, increased flooding, and decreased groundwater recharge. However, to our knowledge the existing literature does not test the effect of parking minimums on the amount of lot space devoted to parking beyond a few case studies. This paper tests the hypothesis that parking space requirements cause an oversupply of parking by examining the implicit marginal value of land allocated to parking spaces. This is an indirect test of the effects of parking requirements that is similar to Glaeser and Gyourko (2003). A simple theoretical model shows that the marginal value of additional parking to the sale price should be equal to the cost of land plus the cost of parking construction. We estimate the marginal values of parking and lot area with spatial methods using a large data set from the Los Angeles area non-residential property sales and find that for most of the property types the marginal value of parking is significantly below that of the parcel area. This evidence supports the contention that minimum parking requirements significantly increase the amount of parcel area devoted to parking. JEL codes:R52, H23Parking, Land Use, Sprawl

Revenue-Recycling and the Efficiency and Spatial Distributional Impacts of Development Taxes

Recent studies that compare the efficiency and distributional impacts of alternative instruments to curb sprawl typically ignore what to do with the revenues from anti-sprawl policies, such as development taxes. This paper extends first-best analysis of development taxes aimed at preserving land at the urban fringe to account for interactions with other distortions within the urban system. By incorporating urban decline at the city core, which in turn, generates negative neighborhood spillover effects and extra pressure for development at the urban fringe, we provide a more complete framework to evaluate the efficiency and distributional impacts of development taxes. We consider three potential alternative schemes to recycle the revenues: lump sum recycling, earmarked revenues to purchase conservation easements that permanently save open space and earmarked revenues to subsidize a revitalization program at the city core. In this setting, when revenues from the development tax are earmarked to fund a conservation easement there is an additional welfare gain (relative to the lump sum case) because the threat of future conversation of open space is fully eliminated. Similarly, when revenues are earmarked to fund a revitalization program at the city core, there are additional sources of welfare that make this policy preferred relative to the lump-sum recycling scheme. Finally, we also explore the spatial distributional impacts of these three alternative recycling schemes.Urban Sprawl, Revenue-Recycling, Regional Coordination, Spatial Modeling, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy, Q31, R14, R38,

Welfare Effects of Anti-Sprawl Policies in the Presence of Urban Decline

This paper extends first-best analysis of anti-sprawl policies, such as development taxes, and examines the welfare effects of development taxes in the presence of urban decline at the city core. We find that anti-sprawl policies generate several important feedbacks within the urban system, generating additional welfare gains and affecting the level of urban decline and suburban sprawl. Further, the optimal development tax exceeds the (first-best) Pigouvian level, irrespective of whether or not revenues are returned lump-sum to all landowners or earmarked for urban decline mitigation.urban sprawl, development taxes, second-best policies, spatial modeling, Land Economics/Use,

Urban Deforestation and Urban Development

This paper has developed a model of a single forest owner operating with perfect foresight in a dynamic open-city environment that allows for switching between alternative competing land uses (forest and urban use) at some point in the future. The model also incorporates external values of an even-aged standing forest in addition to the value of timber when it is harvested. Timber is exploited based on a multiple rotation model a la Faustmann with clear-cut harvesting. In contrast to previous models, our alternative land use to forest land is endogenous. Within this framework, we study the problem of the private owner as well as that of the social planner, when choosing the time to harvest, the time to convert land and the intensity of development. We also examine the extent to which the two-way linkage between urban development and forest management practices (timber production and provision of forest amenities) contributes to economic efficiency and improvements in non-market forest benefits. Finally, we consider policy options available to a regulator seeking to achieve improvements in efficiency including anti-sprawl policies (impact fees and density controls) and forest policies such a yield tax. Numerical simulations illustrate our analytical results. JEL codes:Deforestation, Urban Development, Forest Management Practices, Anti-Sprawl Policies, Yield Taxes

Parking and Urban Form

This paper analyzes the provision of residential parking in a monocentric city, with the ultimate goal of appraising the desirability and effects of regulations such as a minimum-parking requirement (MPR) per dwelling. The analysis considers three different regimes for provision of parking space: surface parking, underground parking, and structural parking, with the latter two regimes involving capital investment either in the form of an underground parking garage or an above-ground parking structure. Parking area is viewed as a dwelling attribute that, along with floor space, provides utility. In addition, road congestion in the neighborhood (which affects the commuting costs of local residents) depends on the average amount of off-street parking per dwelling, an externality that is ignored by profit-maximizing developers, making the equilibrium inefficient. The analysis explores the equilibrium spatial behavior of the two dwelling attributes as well as residential and parking structural density, and analysis of land rent shows which parking regimes are present in different parts of the city. Efficiency requires an increase in parking area per dwelling at each location, which can be achieved in a crude fashion by an MPR, whose effects are analyzed

In vitro polarized Raman analysis for the evaluation of the efficacy of CPP-ACP remineralizing mousse in tooth hypomineralization

UID/FIS/ 04559/2020The purpose of this in vitro study is to evaluate the efficacy of a commercially available tooth mousse in the remineralization of human enamel in cases of Molar-incisor-hypomineralization (MIH). Treatment protocol with GC Tooth Mousse containing Casein phosphopeptide amorphous calcium phosphate (CPP-ACP) was applied to 12 teeth (4 healthy, 4 hypomineralized with white opacities and 4 hypomineralized with yellow opacities) and the samples were evaluated with polarized Raman microscopy. The depolarization ratio of the symmetric stretching band of phosphate band was compared in each sample before and after treatment with the tooth mousse. The mean depolarization ratio values decreased in all three groups, after the treatment protocol, with significant differences (p < 0.05) for the two hypomineralized teeth’ groups. These results allowed us to conclude that there was an improvement in mineral density and organization of the hypomineralized enamel after treatment with CPP-ACP tooth mousse.publishersversionpublishe

Tuning the Kinetic Stability of the Amorphous Phase of the Chloramphenicol Antibiotic

We employ broadband dielectric spectroscopy to study the relaxation dynamics and crystallization kinetics of a broad-spectrum antibiotic, chloramphenicol, in its supercooled liquid form. Two dynamic processes are observed: the structural a relaxation, which becomes kinetically frozen at Tg = 302 ± 1 K, and an intramolecular secondary relaxation. Under isothermal conditions, the supercooled drug displays interconversion between different isomers, followed by recrystallization. Recrystallization follows the Avrami law with Avrami exponent n = 1.3 ± 0.1, consistent with a one dimensional growth of crystalline platelets, as observed by electron microscopy. Exposure to humid atmosphere and subsequent heating to high temperature is found to degrade the compound. The partially degraded sample displays a much lower tendency to crystallize, likely because the presence of the degradation products results in spatial frustration. This sample exhibits enhanced conductivity and an additional relaxation, intermediate to the ones observed in the pure sample, which likely corresponds to the noncooperative dynamics of the main degradation product. We find that dispersing the antibiotic in polylactic acid results in an amorphous sample which does not crystallize at room temperature for relatively long times.Peer ReviewedPostprint (published version

Heterologous expression and structure prediction of a xylanase identified from a compost metagenomic library

Xylanases are key biocatalysts in the degradation of the 1,4glycosidic linkages in the xylan backbone of hemicellulose. These enzymes are potentially applied in a wide range of bioprocessing industries under harsh conditions. Metagenomics has emerged as powerful tools for the bioprospection and discovery of interesting bioactive molecules from extreme ecosystems with unique features, such as high temperatures. In this study, an innovative combination of function-driven screening of a compost metagenomic library and automatic extraction of halo areas with in-house MATLAB functions resulted in the identification of a promising clone with xylanase activity (LP4). The LP4 clone proved to be an effective xylanase producer under submerged fermentation conditions. Sequence and phylogenetic analyses revealed that the xylanase, Xyl4, corresponded to an endo-1,4--xylanase belonging to glycosyl hydrolase family 10 (GH10). When xyl4 was expressed in Escherichia coli BL21(DE3), the enzyme activity increased about 2-fold compared to the LP4 clone. To get insight on the interaction of the enzyme with the substrate and establish possible strategies to improve its activity, the structure of Xyl4 was predicted, refined, and docked with xylohexaose. Our data unveiled, for the first time, the relevance of the amino acids Glu133 and Glu238 for catalysis, and a close inspection of the catalytic site suggested that the replacement of Phe316 by a bulkier Trp may improve Xyl4 activity. Our current findings contribute to enhancing the catalytic performance of Xyl4 towards industrial applications.info:eu-repo/semantics/publishedVersio

Herschel observations of interstellar chloronium

Using the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared (HIFI), we have observed para-chloronium (H2Cl+) toward six sources in the Galaxy. We detected interstellar chloronium absorption in foreground molecular clouds along the sight-lines to the bright submillimeter continuum sources Sgr A (+50 km/s cloud) and W31C. Both the para-H2-35Cl+ and para-H2-37Cl+ isotopologues were detected, through observations of their 1(11)-0(00) transitions at rest frequencies of 485.42 and 484.23 GHz, respectively. For an assumed ortho-to-para ratio of 3, the observed optical depths imply that chloronium accounts for ~ 4 - 12% of chlorine nuclei in the gas phase. We detected interstellar chloronium emission from two sources in the Orion Molecular Cloud 1: the Orion Bar photodissociation region and the Orion South condensation. For an assumed ortho-to-para ratio of 3 for chloronium, the observed emission line fluxes imply total beam-averaged column densities of ~ 2.0E+13 cm-2 and ~ 1.2E+13 cm-2, respectively, for chloronium in these two sources. We obtained upper limits on the para-H2-35Cl+ line strengths toward H2 Peak 1 in the Orion Molecular cloud and toward the massive young star AFGL 2591. The chloronium abundances inferred in this study are typically at least a factor ~10 larger than the predictions of steady-state theoretical models for the chemistry of interstellar molecules containing chlorine. Several explanations for this discrepancy were investigated, but none has proven satisfactory, and thus the large observed abundances of chloronium remain puzzling.Comment: Accepted for publication in the Astrophysical Journa

Phylogeography and modes of reproduction in diploid and tetraploid halophytes of Limonium species (Plumbaginaceae): evidence for a pattern of geographical parthenogenesis

Background and Aims The genus Limonium (Plumbaginaceae) has long been recognized to have sexual and apomictic (asexual seed formation) modes of reproduction. This study aimed to elucidate phylogeographical patterns and modes of reproduction in diploid and tetraploid Limonium species, namely three putative sexual diploid species with morphological affinities (L. nydeggeri, L. ovalifolium, L. lanceolatum) and three related, probably apomict tetraploid species (L. binervosum, L. dodartii, L. multiflorum). Methods cpDNA diversity and differentiation between natural populations of the species were investigated using two chloroplast sequence regions (trnL intron and trnL–trnF intergenic spacer). Floral heteromorphies, ovule cytoembryological analyses and pollination and crossing tests were performed in representative species of each ploidy group, namely diploid L. ovalifolium and tetraploid L. multiflorum, using plants from greenhouse collections. Key Results and Conclusions Genetic analyses showed that diploid species have a higher haplotype diversity and a higher number of unique (endemic) haplotypes than tetraploid species. Network analysis revealed correlations between cpDNA haplotype distribution and ploidy groups, species groups and geographical origin, and haplotype sharing within and among species with distinct ploidy levels. Reproductive biology analyses showed that diploid L. ovalifolium mainly forms meiotically reduced tetrasporic embryo sacs of Gagea ova, Adoxa and Drusa types. Limonium multiflorum, however, has only unreduced, diplosporic (apomictic) embryo sacs of Rudbeckia type, and autonomous apomictic development seems to occur. Taken together, the findings provide evidence of a pattern of ‘geographical parthenogenesis’ in which quaternary climatic oscillations appear to be involved in the geographical patterns of coastal diploid and tetraploid Limonium speciesinfo:eu-repo/semantics/publishedVersio