Organizational Design for Spill Containment in Deepwater Drilling Operations in the Gulf of Mexico: Assessment of the Marine Well Containment Company (MWCC)

The Deepwater Horizon oil spill in the Gulf of Mexico in April 2010 led to the deaths of 11 workers, a six-month moratorium on deepwater drilling in the Gulf, and nearly three months of massive engineering and logistics efforts to stop the spill. The series of failures before the well was finally capped and the spill contained revealed an inability to deal effectively with a well in deepwater and ultradeepwater. Ensuring that containment capabilities are adequate for drilling operations at these depths is therefore a salient challenge for government and industry. In this paper we assess the Marine Well Containment Company (MWCC), a consortium aimed at designing and building a system capable of containing future deepwater spills in the Gulf. We also consider alternatives for long-term readiness for deepwater spill containment. We focus on the roles of liability and regulation as determinants of readiness and the adequacy of incentives for technological innovation in oil spill containment technology to keep pace with advances in deepwater drilling capability. Liability and regulation can significantly influence the strength of these incentives. In addition, we discuss appropriate governance structure as a major determinant of the effectiveness of MWCC.oil spill, containment, industry R&D, liability, regulation, governance, innovation

Comparing Simulations of AGN Feedback

We perform adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) cosmological zoom simulations of a region around a forming galaxy cluster, comparing the ability of the methods to handle successively more complex baryonic physics. In the simplest, non-radiative case, the two methods are in good agreement with each other, but the SPH simulations generate central cores with slightly lower entropies and virial shocks at slightly larger radii, consistent with what has been seen in previous studies. The inclusion of radiative cooling, star formation, and stellar feedback leads to much larger differences between the two methods. Most dramatically, at z=5, rapid cooling in the AMR case moves the accretion shock well within the virial radius, while this shock remains near the virial radius in the SPH case, due to excess heating, coupled with poorer capturing of the shock width. On the other hand, the addition of feedback from active galactic nuclei (AGN) to the simulations results in much better agreement between the methods. In this case both simulations display halo gas entropies of 100 keV cm^2, similar decrements in the star-formation rate, and a drop in the halo baryon content of roughly 30%. This is consistent with AGN growth being self-regulated, regardless of the numerical method. However, the simulations with AGN feedback continue to differ in aspects that are not self-regulated, such that in SPH a larger volume of gas is impacted by feedback, and the cluster still has a lower entropy central core.Comment: 22 pages, 20 figures, 3 tables, Accepted to ApJ, comments welcom

The supporting-cell antigen: a receptor-like protein tyrosine phosphatase expressed in the sensory epithelia of the inner ear

After noise- or drug-induced hair-cell loss, the sensory epithelia of the avian inner ear can regenerate new hair cells. Few molecular markers are available for the supporting-cell precursors of the hair cells that regenerate, and little is known about the signaling mechanisms underlying this regenerative response. Hybridoma methodology was used to obtain a monoclonal antibody (mAb) that stains the apical surface of supporting cells in the sensory epithelia of the inner ear. The mAb recognizes the supporting-cell antigen (SCA), a protein that is also found on the apical surfaces of retinal Müller cells, renal tubule cells, and intestinal brush border cells. Expression screening and molecular cloning reveal that the SCA is a novel receptor-like protein tyrosine phosphatase (RPTP), sharing similarity with human density-enhanced phosphatase, an RPTP thought to have a role in the density-dependent arrest of cell growth. In response to hair-cell damage induced by noise in vivo or hair-cell loss caused by ototoxic drug treatment in vitro, some supporting cells show a dramatic decrease in SCA expression levels on their apical surface. This decrease occurs before supporting cells are known to first enter S-phase after trauma, indicating that it may be a primary rather than a secondary response to injury. These results indicate that the SCA is a signaling molecule that may influence the potential of nonsensory supporting cells to either proliferate or differentiate into hair cell

Alpha-synuclein aggregates increase the conductance of substantia nigra dopamine neurons, an effect partly reversed by the KATP channel inhibitor glibenclamide

Dopaminergic neurons in the substantia nigra pars compacta (SNpc) form an important part of the basal ganglia circuitry, playing key roles in movement initiation and co-ordination. A hallmark of Parkinson’s disease (PD) is the degeneration of these SNpc dopaminergic neurons leading to akinesia, bradykinesia and tremor. There is gathering evidence that oligomeric alpha synuclein (α-syn) is one of the major pathological species in PD, with its deposition in Lewy bodies closely correlated with disease progression. However the precise mechanisms underlying the effects of oligomeric α-syn on dopaminergic neuron function have yet to be fully defined. Here we have combined electrophysiological recording and detailed analysis to characterise the time-dependent effects of α-syn aggregates (consisting of oligomers and possibly small fibrils) on the properties of SNpc dopaminergic neurons. The introduction of α-syn aggregates into single dopaminergic neurons via the patch electrode significantly reduced both the input resistance and the firing rate without changing the membrane potential. These effects occurred after 8-16 minutes of dialysis but did not occur with the monomeric form of α-syn. The effects of α-syn aggregates could be significantly reduced by pre-incubation with the ATP-sensitive potassium channel (KATP) inhibitor glibenclamide. This data suggests that accumulation of α-syn aggregates in dopaminergic neurons may chronically activate KATP channels leading to a significant loss of excitability and dopamine release

Assessing recent warming using instrumentally homogeneous sea surface temperature records

Sea surface temperature (SST) records are subject to potential biases due to changing instrumentation and measurement practices. Significant differences exist between commonly used composite SST reconstructions from the National Oceanic and Atmospheric Administration’s Extended Reconstruction Sea Surface Temperature (ERSST), the Hadley Centre SST data set (HadSST3), and the Japanese Meteorological Agency’s Centennial Observation-Based Estimates of SSTs (COBE-SST) from 2003 to the present. The update from ERSST version 3b to version 4 resulted in an increase in the operational SST trend estimate during the last 19 years from 0.07° to 0.12°C per decade, indicating a higher rate of warming in recent years. We show that ERSST version 4 trends generally agree with largely independent, near-global, and instrumentally homogeneous SST measurements from floating buoys, Argo floats, and radiometer-based satellite measurements that have been developed and deployed during the past two decades. We find a large cooling bias in ERSST version 3b and smaller but significant cooling biases in HadSST3 and COBE-SST from 2003 to the present, with respect to most series examined. These results suggest that reported rates of SST warming in recent years have been underestimated in these three data sets

Developments in low-cost laser detection: wide field of view implementation and direction determination

The availability of low cost but relatively high power laser pointers (hundreds of mW) has led to misuse with potentially dangerous consequences, such as dazzling aircraft which has raised concerns about aircraft safety. A low cost laser detection system based on coherence detection has been developed and is able to detect weak, continuous laser sources even against bright background light. In this paper, we introduce the use of a cone mirror to extend the horizontal field of view of the detector (originally at 3°) to 360° to detect incoming beams from different directions. With the additional use of a camera in the system, we also determine the direction of the incoming laser beam. Finally, the sensitivity between the original system and the cone mirror system are compared: the new system showed promising results with a sensitivity below 100nW

FiberGLAST: a scintillating fiber approach to the GLAST mission

FiberGLAST is a scintillating fiber gamma-ray detector designed for the GLAST mission. The system described below provides superior effective area and field of view for modest cost and risk. An overview of the FiberGLAST instrument is presented, as well as a more detailed description of the principle elements of the primary detector volume. The triggering and readout electronics are described, and Monte Carlo Simulations of the instrument performance are presented

An Economic Examination of Potential Ethanol Production in Texas

Agribusiness, Agricultural and Food Policy, Resource /Energy Economics and Policy,