The Influence of Shale gas on U.S. Energy and Environmental Policy

http://globalchange.mit.edu/research/publications/2219The emergence of U.S. shale gas resources to economic viability affects the nation’s energy outlook and the expected role of natural gas in climate policy. Even in the face of the current shale gas boom, however, questions are raised about both the economics of this industry and the wisdom of basing future environmental policy on projections of large shale gas supplies. Analysis of the business model appropriate to the gas shales suggests that, though the shale future is uncertain, these concerns are overstated. The policy impact of the shale gas is analyzed using two scenarios of greenhouse gas control—one mandating renewable generation and coal retirement, the other using price to achieve a 50% emissions reduction. The shale gas is shown both to benefit the national economy and to ease the task of emissions control. However, in treating the shale as a “bridge” to a low carbon future there are risks to the development of technologies, like capture and storage, needed to complete the task.This paper was supported by the U.S. Department of Energy, Office of Science (DE-FG02-94ER61937); the U.S. Environmental Protection Agency; the Electric Power Research Institute; and other U.S. government agencies and a consortium of 40 industrial and foundation sponsors

Numerical model of the Tikitere geothermal system

The Tikitere geothermal field is one of the 21 high-enthalpy geothermal fields in the Taupo Volcanic Zone (TVZ) in New Zealand. The field is renowned for the tourist attraction Hell’s Gate, which consists of many natural geothermal surface features. Based on geoscientific data from the open-source literature, a conceptual model was set up in Leapfrog Geothermal. A corresponding natural state reservoir model was then set up and calibrated using temperature and heat flux data from fourteen thermal areas. The calibrated numerical model matches the higher temperatures at the locations of some of the surface thermal features but does not match the estimated heat flows

Numerical model of the Tikitere geothermal system

The Tikitere geothermal field is one of the 21 high-enthalpy geothermal fields in the Taupo Volcanic Zone (TVZ) in New Zealand. The field is renowned for the tourist attraction Hell’s Gate, which consists of many natural geothermal surface features. Based on geoscientific data from the open-source literature, a conceptual model was set up in Leapfrog Geothermal. A corresponding natural state reservoir model was then set up and calibrated using temperature and heat flux data from fourteen thermal areas. The calibrated numerical model matches the higher temperatures at the locations of some of the surface thermal features but does not match the estimated heat flows

The effect of peer modelling and discussing modelled feedback principles on medical students' feedback skills: a quasi-experimental study

Background Teaching is an important professional skill for physicians and providing feedback is an important part of teaching. Medical students can practice their feedback skills by giving each other peer feedback. Therefore, we developed a peer feedback training in which students observed a peer that modelled the use of good feedback principles. Students then elaborated on the modelled feedback principles through peer discussion. This combination of peer modelling and discussing the modelled feedback principles was expected to enhance emulation of the feedback principles compared to (1) only peer modelling and (2) discussing the feedback principles without previous modelling. Methods In a quasi-experimental study design, 141 medical students were assigned randomly to three training conditions: peer modelling plus discussion (MD), non-peer modelled example (NM) or peer modelling without discussion (M). Before and after the training, they commented on papers written by peers. These comments served as a pre- and a post-measure of peer feedback. The comments were coded into different functions and aspects of the peer feedback. Non-parametrical Kruskall-Wallis tests were used to check for pre- and post-measure between-group differences in the functions and aspects. Results Before the training, there were no significant between-group differences in feedback functions and aspects. After the training, the MD-condition gave significantly more positive peer feedback than the NM-condition. However, no other functions or aspects were significantly different between the three conditions, mainly because the within-group interquartile ranges were large. Conclusions The large interquartile ranges suggest that students differed substantially in the effort placed into giving peer feedback. Therefore, additional incentives may be needed to motivate students to give good feedback. Teachers could emphasise the utility value of peer feedback as an important professional skill and the importance of academic altruism and professional accountability in the peer feedback process. Such incentives may convince more students to put more effort into giving peer feedback.Medical Education Researc

Genome-wide association study identifies loci on 12q24 and 13q32 associated with Tetralogy of Fallot

We conducted a genome-wide association study to search for risk alleles associated with Tetralogy of Fallot (TOF), using a northern European discovery set of 835 cases and 5159 controls. A region on chromosome 12q24 was associated (P = 1.4 × 10−7) and replicated convincingly (P = 3.9 × 10−5) in 798 cases and 2931 controls [per allele odds ratio (OR) = 1.27 in replication cohort, P = 7.7 × 10−11 in combined populations]. Single nucleotide polymorphisms in the glypican 5 gene on chromosome 13q32 were also associated (P = 1.7 × 10−7) and replicated convincingly (P = 1.2 × 10−5) in 789 cases and 2927 controls (per allele OR = 1.31 in replication cohort, P = 3.03 × 10−11 in combined populations). Four additional regions on chromosomes 10, 15 and 16 showed suggestive association accompanied by nominal replication. This study, the first genome-wide association study of a congenital heart malformation phenotype, provides evidence that common genetic variation influences the risk of TO

A model-based method for the prediction of whole body absorbed dose and bone marrow toxicity for ¹⁸⁶Re-HEDP treatment of skeletal metastases from prostate cancer

In high-activity rhenium-186 hydroxyethylidene diphosphonate ((186)Re-HEDP) treatment of bone metastatic disease from prostate cancer the dose-limiting factor is haematological toxicity. In this study, we examined the correlation of the injected activity and the whole-body absorbed dose with treatment toxicity and response. Since the best response is likely to be related to the maximum possible injected activity limited by the whole-body absorbed dose, the relationship between pre-therapy biochemical and physiological parameters and the whole-body absorbed dose was studied to derive an algorithm to predict the whole-body absorbed dose prior to injection of the radionuclide. The whole-body retention of radioactivity was measured at several time points after injection in a cohort of patients receiving activities ranging between 2,468 MBq and 5,497 MBq. The whole-body absorbed dose was calculated by fitting a sequential series of exponential phases to the whole-body time-activity data and by integrating this fit over time to obtain the whole-body cumulated activity. This was then converted to absorbed dose using the Medical Internal Radiation Dose (MIRD) committee methodology. Treatment toxicity was estimated by the relative decrease in white cell (WC) and platelet (Plt) counts after the injection of the radionuclide, and by their absolute nadir values. The criterion for a treatment response was a 50% or greater decrease in prostate-specific antigen (PSA) value lasting for 4 weeks. Alkaline phosphatase (AlkPh), chromium-51 ethylene diamine tetra-acetate ((51)Cr-EDTA) clearance rate and weight were measured before injection of the radionuclide. The whole-body absorbed dose showed a significant correlation with WC and Plt toxicity ( P=0.005 and 0.003 for the relative decrease and P=0.006 and 0.003 for the nadir values of WC and Plt counts respectively) in a multivariate analysis which included injected activity, whole-body absorbed dose, pre-treatment WC and Plt baseline counts, PSA and AlkPh values, and the pre-treatment Soloway score. The injected activity did not show any correlation with WC or Plt toxicity, but it did correlate with PSA response ( P=0.005). These results suggest that the administration of higher activities would be likely to generate a better response, but that the quantity of activity that can be administered is limited by the whole-body absorbed dose. We have derived and evaluated a model that estimates the whole-body absorbed dose on an individual patient basis prior to injection. This model uses the level of injected activity and pre-injection measurements of AlkPh, weight and (51)Cr-EDTA clearance. It gave good estimates of the whole-body absorbed dose, with an average difference between predicted and measured values of 15%. Furthermore, the whole-body absorbed dose predicted using this algorithm correlated with treatment toxicity. It could therefore be used to administer levels of activity on a patient-specific basis, which would help in the optimisation of targeted radionuclide therapy. We believe that algorithms of this kind, which use pre-injection biochemical and physiological measurements, could assist in the design of escalation trials based on a toxicity-limiting whole-body absorbed dose, rather than using the more conventional activity escalation approach

Using apatite to resolve the age and protoliths of mid-crustal shear zones: A case study from the Taxaquara Shear Zone, SE Brazil

Shear zones accommodate strain and facilitate migration of hydrothermal fluid and magma through the crust. Unravelling the deformation history of shear zones requires correspondence between the closure temperature of mineral geochronometers and the temperature of deformation. Here, we adopt apatite U–Pb-trace element analysis as a tool for dating deformation and tracing the protoliths of mid-crustal shear zones through a case study of the Taxaquara Shear Zone (TSZ), a major transpressional shear zone in the southern Ribeira Belt of SE Brazil. Apatite from mylonites in the TSZ yield U–Pb ages of 558–536 Ma, considering uncertiainties, which slightly overlap with 40Ar/39Ar ages of 538 ± 2 Ma from muscovite in the lower limit. The closure temperature of apatite is estimated at 500–460 °C, which is slightly higher than that estimated for syn-kinematic muscovite (445–420 °C). Apatite from shear zone mylonites has Sr/Y and LREE systematics typical of apatite from S- and I-type granitoids, suggesting the adjacent and undeformed Pilar do Sul and Piedade granites are the likely protoliths of the mylonites. This interpretation is supported by new U–Pb ages of ca. 605 Ma from prekinematic zircon and titanite from mylonites, which corresponds closely with new U–Pb apatite ages and previously published U–Pb monazites ages from the Pilar do Sul Granite. We suggest the U–Pb system of apatite in the TSZ was reset via volume diffusion during rapid cooling given that it preserves the igneous geochemical signatures. Moreover, this interpretation is consistent with the lower apatite closure temperature (500–460 °C) relatively to the temperature of deformation (530–480 °C). The revised ~560–535 Ma age for the TSZ demonstrates that it post-dates the collisional phase of the Ribeira Belt (620–595 Ma and 595–565 Ma), indicating protracted strain accommodation during the Brasiliano–Pan African orogeny, and supports correlation with the 600–550 Ma and 570–550 Ma transpressional Dom Feliciano and Kaoko Belts. This study demonstrates that apatite is a powerful tool for unravelling the history of mid-crustal shear zones as it is stable in a wide range of lithotypes, has trace element compositions that are sensitive to the environment of formation, and Pb closure temperatures typical of mid-crust conditions. U–Pb-trace element analysis of apatite provides a robust means to date shear zones that can be complimentary to, or independent of, more traditional 40Ar/39Ar analysis of mica or amphibole.B.V. Ribeiro, J.A. Mulder, F.M. Faleiros, C.L. Kirkland, P.A. Cawood, G. O, Sullivan, G.A.C. Campanha, M.A. Finch, R.F. Weinberg, O. Nebe