Carbon Tariffs: Impacts on Technology Choice, Regional Competitiveness, and Global Emissions

Carbon regulation is intended to reduce global emissions, but there is growing concern that such regulation may simply shift production to unregulated regions, potentially increasing overall carbon emissions in the process. Carbon tariffs have emerged as a possible mechanism to address this concern by imposing carbon costs on imports at the regulated region's border. Advocates claim that such a mechanism would level the playing field whereas opponents argue that such a tariff is anti-competitive. This paper analyzes how carbon tariffs affect technology choice, regional competitiveness, and global emissions through a model of imperfect competition between "domestic" (i.e., carbon-regulated) firms and "foreign" (i.e., unregulated) firms, where domestic firms have the option to offshore production and the number of foreign entrants is endogenous. Under a carbon tariff, results indicate that foreign firms would adopt clean technology at a lower emissions price than domestic producers, with the number of foreign entrants increasing in emissions price only over intervals where offshore foreign firms hold this technology advantage. Further, domestic firms would only offshore production under a carbon tariff to adopt technology strictly cleaner than technology utilized domestically. As a consequence, under a carbon tariff, foreign market share is non-monotonic in emissions price, and global emissions conditionally decrease. Without a carbon tariff, foreign share monotonically increases in emissions price, and a shift to offshore production results in a strict increase in global emissions.Carbon regulation; Carbon leakage; Technology choice; Imperfect competition

The Equivalence Principle as a Stepping Stone from Special to General Relativity: A Socratic Dialog

In this paper we show how the student can be led to an understanding of the connection between special relativity and general relativity by considering the time dilation effect of clocks placed on the surface of the Earth. This paper is written as a Socratic dialog between a lecturer Sam and a student Kim.Comment: 8 pages, 1 figure, uses the revtex4 documentclass. Submitted to the American Journal of Physics. Minor modification and corrections following referees' comment

A Search for a Sub-Earth Sized Companion to GJ 436 and a Novel Method to Calibrate Warm Spitzer IRAC Observations

We discovered evidence for a possible additional 0.75 R_Earth transiting planet in the NASA EPOXI observations of the known M dwarf exoplanetary system GJ 436. Based on an ephemeris determined from the EPOXI data, we predicted a transit event in an extant Spitzer Space Telescope 8 micron data set of this star. Our subsequent analysis of those Spitzer data confirmed the signal of the predicted depth and at the predicted time, but we found that the transit depth was dependent on the aperture used to perform the photometry. Based on these suggestive findings, we gathered new Warm Spitzer Observations of GJ 436 at 4.5 microns spanning a time of transit predicted from the EPOXI and Spitzer 8 micron candidate events. The 4.5 micron data permit us to rule out a transit at high confidence, and we conclude that the earlier candidate transit signals resulted from correlated noise in the EPOXI and Spitzer 8 micron observations. In the course of this investigation, we developed a novel method for correcting the intrapixel sensitivity variations of the 3.6 and 4.5 micron channels of the Infrared Array Camera (IRAC) instrument. We demonstrate the sensitivity of Warm Spitzer observations of M dwarfs to confirm sub-Earth sized planets. Our analysis will inform similar work that will be undertaken to use Warm Spitzer observations to confirm rocky planets discovered by the Kepler mission.Comment: 22 pages, 8 figures, accepted for publication in PAS

Highly accurate calculations of the rotationally excited bound states in three-body systems

An effective optimization strategy has been developed to construct highly accurate bound state wave functions in various three-body systems. Our procedure appears to be very effective for computations of weakly bound states and various excited states, including rotationally excited states, i.e. states with $L \ge 1$. The efficiency of our procedure is illustrated by computations of the excited $P^{*}(L = 1)-$states in the $dd\mu, dt\mu$ and $tt\mu$ muonic molecular ions, $P(L = 1)-$states in the non-symmetric $pd\mu, pt\mu$ and $dt\mu$ ions and $2^{1}P(L = 1)-$ and $2^{3}P(L = 1)-$states in He atom(s)

Conformational effects of nucleotide exchange in ras p21 proteins as studied by fluorescence spectroscopy

AbstractThe intrinsic fluorescence properties of the oncogene protein p21N-ras, p21H-ras and one of its transforming mutants, p21N-ras (Va1112), have been investigated. A mutant containing a single tryptophan at position 28 in p21H-ras (Trp28) has been specifically engineered to provide a probe of protein conformation on nucleotide binding. The proteins produced essentially similar circular dichroism spectra typical of alpha/beta proteins. A decrease in the intensity of the fluorescence emission spectrum due to tyrosine occurred on GDP/GTP nucleotide exchange in the native and mutant proteins. Selective excitation of the single tryptophan in p21 produced a decrease in fluorescence intensity which was accompanied by a blue shift in the wavelength of maximum emission on nucleotide exchange. A reduction in the residual Mg2+ ion concentration enhanced this effect

Preliminary Results on HAT-P-4, TrES-3, XO-2, and GJ 436 from the NASA EPOXI Mission

EPOXI (EPOCh + DIXI) is a NASA Discovery Program Mission of Opportunity using the Deep Impact flyby spacecraft. The EPOCh (Extrasolar Planet Observation and Characterization) Science Investigation will gather photometric time series of known transiting exoplanet systems from January through August 2008. Here we describe the steps in the photometric extraction of the time series and present preliminary results of the first four EPOCh targets.Comment: 4 pages, 2 figures. To appear in the Proceedings of the 253rd IAU Symposium: "Transiting Planets", May 2008, Cambridge, M

On X-ray Optical Depth in the Coronae of Active Stars

We have investigated the optical thickness of the coronal plasma through the analysis of high-resolution X-ray spectra of a large sample of active stars observed with the High Energy Transmission Grating Spectrometer on Chandra. In particular, we probed for the presence of significant resonant scattering in the strong Lyman series lines arising from hydrogen-like oxygen and neon ions. The active RS CVn-type binaries II Peg and IM Peg and the single M dwarf EV Lac show significant optical depth. For these active coronae, the Lya/Lyb ratios are significantly depleted as compared with theoretical predictions and with the same ratios observed in similar active stars. Interpreting these decrements in terms of resonance scattering of line photons out of the line-of-sight, we are able to derive an estimate for the typical size of coronal structures, and from these we also derive estimates of coronal filling factors. For all three sources we find that the both the photon path length as a fraction of the stellar radius, and the implied surface filling factors are very small and amount to a few percent at most. The measured Lya/Lyb ratios are in good agreement with APED theoretical predictions, thus indicating negligible optical depth, for the other sources in our sample. We discuss the implications for coronal structuring and heating flux requirements. For the stellar sample as a whole, the data suggest increasing quenching of Lya relative to Lyb as function of both L_x/L_bol and the density-sensitive MgXI forbidden to intercombination line ratio, as might generally be expected.Comment: Accepted for publication on the Astrophysical Journa

Peripheral blood leukocyte response and macrophage function during Eimeria adenoeides infection in turkey poults

Intestinal coccidiosis, caused by various species of Eimeria, is an economically important disease of chickens and turkeys. The peripheral blood leukocyte response and macrophage functions during a coccidial infection in turkeys have not been defined. To examine these aspects of innate immunity during primary Eimeria infection in turkeys, 4-week-old poults were orally inoculated with either 50,000 E. adenoeides oocyst (24 infected poults) or water (24 control poults). To monitor the concentrations and proportions of white blood cells (WBC) throughout the course of infection, heparinized blood was collected from 12 infected and 12 control poults prior to inoculation (day 0), and on days 4, 7, and 11 post-inoculation (PI). To study macrophage function, Sephadex-elicited abdominal exudate cells (macrophages) were collected on day 7 PI from 12 infected and 12 control poults. Macrophages were used to study phagocytosis of unopsonized and antibody-opsonized sheep red blood cells (SRBC), production of nitric oxide, and production of cytotoxic factors. E. adenoeides infection was associated with alterations in the concentration of WBC, including a decrease in the numbers of circulating lymphocytes on day 4 and a rise in lymphocytes and heterophils on day 11. Although phagocytic activity was not different in macrophages from infected and control poults, macrophages from infected poults exhibited greater cytotoxic activity. Data from these studies strongly suggest that components of innate immunity were recruited and activated during this primary infection of turkey poults with E. adenoeides. Further investigations are needed to determine the role of these components in limiting primary infection by E. adenoeides