Does Britain or the United States Have the Right Gasoline Tax?

This paper develops an analytical framework for assessing the second-best optimal level of gasoline taxation, taking into account unpriced pollution, congestion, and accident externalities and interactions with the broader fiscal system. We provide calculations of the optimal taxes for the United States and the United Kingdom under a wide variety of parameter scenarios, with the gasoline tax substituting for a distorting tax on labor income. Under our central parameter values, the second-best optimal gasoline tax is $1.01 per gallon for the United States and$1.34 per gallon for the United Kingdom. These values are moderately sensitive to alternative parameter assumptions. The congestion externality is the largest component in both nations, and the higher optimal tax for the United Kingdom is due mainly to a higher assumed value for marginal congestion cost. Revenue-raising needs, incorporated in a “Ramsey” component, also play a significant role, as do accident externalities and local air pollution. The current gasoline tax in the United Kingdom ($2.80 per gallon) is more than twice this estimated optimal level. Potential welfare gains from reducing it are estimated at nearly one-fourth the production cost of gasoline used in the United Kingdom. Even larger gains in the United Kingdom can be achieved by switching to a tax on vehicle miles with equal revenue yield. For the United States, the welfare gains from optimizing the gasoline tax are smaller, but those from switching to an optimal tax on vehicle miles are very large.gasoline tax, pollution, congestion, accidents, fiscal interactions

Should Urban Transit Subsidies Be Reduced?

This paper derives intuitive and empirically useful formulas for the optimal pricing of passenger transit and for the welfare effects of adjusting current fare subsidies, for peak and off-peak urban rail and bus systems. The formulas are implemented based on a detailed estimation of parameter values for the metropolitan areas of Washington (D.C.), Los Angeles, and London. Our analysis accounts for congestion, pollution, and accident externalities from automobiles and from transit vehicles; scale economies in transit supply; costs of accessing and waiting for transit service as well as service crowding costs; and agency adjustment of transit frequency, vehicle size, and route network to induced changes in demand for passenger miles. The results support the efficiency case for the large fare subsidies currently applied across mode, period, and city. In almost all cases, fare subsidies of 50 percent or more of operating costs are welfare improving at the margin, and this finding is robust to alternative assumptions and parameters.transit subsidies, scale economies, traffic congestion, welfare effects

Should Urban Transit Subsidies Be Reduced?

This paper derives intuitive and empirically useful formulas for the optimal pricing of passenger transit and for the welfare effects of adjusting current fare subsidies, for peak and off-peak urban rail and bus systems. The formulas are implemented based on a detailed estimation of parameter values for the metropolitan areas of Washington (D.C.), Los Angeles, and London. Our analysis accounts for congestion, pollution, and accident externalities from automobiles and from transit vehicles; scale economies in transit supply; costs of accessing and waiting for transit service as well as service crowding costs; and agency adjustment of transit frequency, vehicle size, and route network to induced changes in demand for passenger miles. The results support the efficiency case for the large fare subsidies currently applying across mode, period, and city. In almost all cases, fare subsidies of 50% or more of operating costs are welfare improving at the margin, and this finding is robust to alternative assumptions and parameters.Transit subsidies; Scale economies; Traffic congestion; Welfare effects

Welfare and Distributional Effects of Road Pricing Schemes for Metropolitan Washington, DC

Economists have long advocated congestion pricing as an efficient way of allocating scarce roadway capacity. However, with a few exceptions, congestion tolls are rarely used in practice and strongly opposed by the public and elected officials. Although high implementation costs and privacy issues are alleviated as appropriate technologies are developed, the concerns that congestion pricing will adversely affect low-income travelers remain. In this paper, we use a strategic transportation planning model calibrated for the Washington, DC, metropolitan area to compare the welfare and distributional effects of three pricing schemes: value pricing (HOT lanes), limited congestion pricing, and comprehensive congestion pricing. We find that social welfare gains from HOT lanes amount to three-quarters of those from the comprehensive road pricing. At the same time, a HOT lanes policy turns out to be much more equitable than other road pricing schemes, with all income groups strictly benefiting even before the toll revenue is recycled.traffic congestion, congestion pricing, value pricing, HOT lanes, HOV lanes

Optimization of metasurfaces for lasing with symmetry constraints on the modes

The development of active metasurface systems, such as lasing metasurfaces, requires the optimization of multiple modes at the absorption and lasing wavelength bands, including their quality factor, mode profile and angular dispersion. Often, these requirements are contradictory and impossible to obtain with conventional design techniques. Importantly, the properties of the eigenmodes of a metasurface are directly linked to their symmetry, which offers an opportunity to explore mode symmetry as an objective in optimization routines for active metasurface design. Here, we propose and numerically demonstrate a novel multi-objective optimization technique based on symmetry projection operators to quantify the symmetry of the metasurface eigenmodes. We present, as an example, the optimization of a lasing metasurface based on up-converting nano-particles. Our technique allows us to optimize the absorption mode dispersion, as well as the directionality of the lasing emission and therefore offers advantages for novel lasing systems with high directionality and low lasing threshold.Comment: 20 pages, 5 figure

Molecular Analysis Confirming the Introduction of Nile Crocodiles, Crocodylus niloticus Laurenti 1768 (Crocodylidae), in Southern Florida, with an Assessment of Potential for Establishment, Spread, and Impacts.

The state of Florida, USA, has more introduced herpetofauna than any other governmental region on Earth. Four species of nonnative crocodilians have been introduced to Florida (all since 1960), one of which is established. Between 2000–2014 we field-collected three nonnative crocodilians in Miami-Dade County, Florida, and one in Hendry County, Florida. We used DNA barcoding and molecular phylogenetics to determine species identification and native range origin. Also, we described diet, movement, and growth for one crocodile. Our molecular analyses illustrated that two of the crocodiles we collected are most closely related to Nile Crocodiles (Crocodylus niloticus) from South Africa, suggesting this region as a source population. We, thus, documented the first known introduction of C. niloticus in Florida. Two, and possibly three of the introduced crocodiles shared the same haplotype, suggesting they are likely from the same introduction pathway or source. One animal was captured, measured, marked, and released, then recaptured 2 y later allowing us to calculate growth rate (40.5 cm/y) and movement. The most likely route of travel by waterway (i.e., canal) illustrates that this animal traveled at least 29 km from its original capture site. One crocodile escaped from a facility in Hendry County, Florida, and survived in 1,012 ha of semi-wild habitat for three to four years, confirming that this species can survive in southern Florida

Stabilization of the RAS:PDE6D complex is a novel strategy to inhibit RAS signaling

This work was supported by Cancer Research UK core funding number A17196.RAS is a major anticancer drug target which requires membrane localization to activate downstream signal transduction. The direct inhibition of RAS has proven to be challenging. Here, we present a novel strategy for targeting RAS by stabilizing its interaction with the prenyl-binding protein PDE6D and disrupting its localization. Using rationally designed RAS point mutations, we were able to stabilize the RAS:PDE6D complex by increasing the affinity of RAS for PDE6D, which resulted in the redirection of RAS to the cytoplasm and the primary cilium and inhibition of oncogenic RAS/ERK signaling. We developed an SPR fragment screening and identified fragments that bind at the KRAS:PDE6D interface, as shown through cocrystal structures. Finally, we show that the stoichiometric ratios of KRAS:PDE6D vary in different cell lines, suggesting that the impact of this strategy might be cell-type-dependent. This study forms the foundation from which a potential anticancer small-molecule RAS:PDE6D complex stabilizer could be developed.Publisher PDFPeer reviewe

The continuum of fetal alcohol spectrum disorders in four rural communities in south africa: Prevalence and characteristics

Prevalence and characteristics of the continuum of diagnoses within fetal alcohol spectrum disorders (FASD) were researched in previously unstudied rural, agricultural, lower socioeconomic populations in South Africa (ZA)

The continuum of fetal alcohol spectrum disorders in a community in South Africa: Prevalence and characteristics in a fifth sample

The prevalence and characteristics of the continuum of diagnoses within fetal alcohol spectrum disorders (FASD) were researched in a fifth sample in a South African community