The Varieties of Resource Experience: How Natural Resource Export Structures Affect the Political Economy of Economic Growth

Many oil, mineral, and plantation crop-based economies experienced a substantial deceleration of growth since the commodity boom and bust of the 1970s and early 1980s. Rodrik (1999) has demonstrated that the magnitude of a country's growth deceleration since the 1970s is a function of both the magnitude of the shocks and a country's "social capability" for adapting to shocks. In this paper, we demonstrate that in this respect countries, with what we term "point source" natural resource exports are doubly disadvantaged. Not only are countries with these types of exports exposed to terms of trade shocks, but the institutional capability for responding to shocks is itself endogenous and negatively related to export composition. Using two different sources of export data and classifications of export composition, we show that point source and coffee/cocoa exporting countries do worse across an array of governance indicators (controlling for a wide array of other potential determinants of governance). This is not just a function of being a "natural resource" exporter, as countries with natural resource exports that are "diffuse" do not show the same strong differences-and have had more robust growth recoveries.economic growth, institutions, natural resource endowment

Two new, single-isomer, sulfated β-cyclodextrins for use as chiral resolving agents for enantiomer separations in capillary electrophoresis

Two novel, single-isomer, sulfated cyclodextrins, the sodium salts of heptakis(2- O-methyl-3-O-acetyl-6-O-sulfo)cyclomaltoheptaose (HMAS) and heptakis(2-O-methyl- 6-O-sulfo)cyclomaltoheptaose (HMS) were used as chiral resolving agents in both aqueous and non-aqueous electrophoretic separation of a set of pharmaceutically active weak base enantiomers. Enantiomers of twenty one of the twenty four weak bases were baseline resolved in one or more of the background electrolytes (BGE’s) used. An eight-step synthetic method was used to produce, on a large scale, the title compounds in greater than 97% purity. The purity of the synthetic intermediates and the final products were characterized by HPLC-ELSD and indirect UV-detection capillary electrophoresis (CE), respectively. X-ray crystallography, MALDI-TOF mass spectrometry and 1H as well as 13C NMR spectroscopy allowed for unambiguous characterization of the structure of each intermediate and the final product

Factors Affecting Lot Low Choice and Above and Lot Premium Choice Acceptance Rate of Beef Calves in the Tri-County Steer Carcass Futurity Program

Data describing 220 lots of beef cattle in the Tri-County Steer Carcass Futurity program from 2003 through 2007 were analyzed using a multiple regression statistical model to determine specific factors that influence lot low Choice and above rate and lot premium Choice (Certified Angus Beef © ) acceptance rate. Lot low Choice and above rate was similar for years 2005-2007. This rate was significantly lower in 2003 than 2004 but both the 2003 and 2004 rates were similar to the rate in all other years. Lots consisting of heifers had higher (P\u3c.05) low Choice and above rates than lots of steers or mixed-sex pens. The greater the amount of Angus influence in the cattle, the higher the low Choice and above rate (P\u3c.0001). An inverse relationship existed between feedlot in-weight and lot low Choice and above rate; those cattle with lighter feedlot arrival weights had higher % Choice and above rates (P=.0007). Cattle with lower disposition scores (calmer cattle) had higher % Choice and above rates (P=.0496). Low Choice and above rate increased as cattle became less efficient in converting feed to gain (P=.0027). An inverse relationship existed between cost of gain and low Choice and above rate; those cattle with lower cost of gain had higher low Choice and above rates (P=.0043). Lot low Choice and above rate increased as average daily gain increased (P=.0094). Factors examined that did not have a significant effect on lot low Choice and above rate were: mud score at final sort, geographic region of origin, lot mortality rate, number of harvest groups within each lot, days on feed, adjusted final weight, individual treatment cost per head, lot size, and season of harvest. Lot premium Choice acceptance rate was similar in each year from 2003-2006 but was significantly lower in 2007 compared with all other years. Lots consisting of heifers had higher (P\u3c.05) premium Choice acceptance rates than lots of steers or mixed-sex pens. Cattle harvested during the months October through December had a lower lot premium Choice acceptance rate than those harvested during January through March, April through June, or July through September (P\u3c.05). The greater the amount of Angus influence in the cattle, the higher the lot premium Choice acceptance rate (P\u3c.0064). An inverse relationship existed between feedlot in-weight and lot premium Choice acceptance rate; those cattle with lighter feedlot arrival weights had higher premium Choice acceptance rates (P\u3c.0001). Lot premium Choice acceptance rate increased as average daily gain increased (P=.0003); however lots of cattle that were less efficient at converting feed into gain had higher premium Choice acceptance rates (P\u3c.0104). Factors examined that did not have a significant effect on lot premium Choice acceptance rate were: mud score at final sort, individual treatment cost per head, number of harvest groups within each lot, days on feed, cost of gain, lot size, geographic region of origin, average disposition score, adjusted final weight, and lot mortality rate

Relaxation Dynamics of Pseudomonas aeruginosa Re^I(C)O_3(α-diimine)(HisX)^+ (X=83, 107, 109, 124, 126)Cu-^(II) Azurins

Photoinduced relaxation processes of five structurally characterized Pseudomonas aeruginosa Re^I(CO)_3(α-diimine)(HisX) (X = 83, 107, 109, 124, 126)Cu^(II) azurins have been investigated by time-resolved (ps−ns) IR spectroscopy and emission spectroscopy. Crystal structures reveal the presence of Re-azurin dimers and trimers that in two cases (X = 107, 124) involve van der Waals interactions between interdigitated diimine aromatic rings. Time-dependent emission anisotropy measurements confirm that the proteins aggregate in mM solutions (D2O, KPi buffer, pD = 7.1). Excited-state DFT calculations show that extensive charge redistribution in the ReI(CO)_3 → diimine ^3MLCT state occurs: excitation of this ^3MLCT state triggers several relaxation processes in Re-azurins whose kinetics strongly depend on the location of the metallolabel on the protein surface. Relaxation is manifested by dynamic blue shifts of excited-state ν(CO) IR bands that occur with triexponential kinetics: intramolecular vibrational redistribution together with vibrational and solvent relaxation give rise to subps, 2, and 8−20 ps components, while the ~10^2 ps kinetics are attributed to displacement (reorientation) of the Re^I(CO)_3(phen)(im) unit relative to the peptide chain, which optimizes Coulombic interactions of the Re^I excited-state electron density with solvated peptide groups. Evidence also suggests that additional segmental movements of Re-bearing β-strands occur without perturbing the reaction field or interactions with the peptide. Our work demonstrates that time-resolved IR spectroscopy and emission anisotropy of Re^I carbonyl−diimine complexes are powerful probes of molecular dynamics at or around the surfaces of proteins and protein−protein interfacial regions

The Role of MED31 in the Regulation of Mesenchymal Stem Cell State

Joseph Straub, Matthew Busby, Michael Osmun, Erik Beadle, and Jamie Newman are part of the School of Biological Sciences at Louisiana Tech University. Joseph Straub, Erik Beadle, and Jamie Newman are part of the Molecular Science and Nanotechnology department at Louisiana Tech University. Bruce Bunnell is a apart of the Tulane Center for Stem Cell Research and Regenerative Medicine at Tulane University

Direct Interaction between AR and PAK6 in Androgen-Stimulated PAK6 Activation

A p21-activated kinase 6 (PAK6) was previously identified to be an androgen receptor (AR) interacting protein through a yeast two-hybrid screening. We used hormone responsive prostate cancer LAPC4 and LNCap cell lines as models to study the signaling events associated with androgen stimulation and PAK6. An androgen-stimulated PAK6 kinase activation was observed in LAPC4 cells expressing endogenous PAK6 and in LNCap cells ectopically expressing a wild type PAK6. This activation was likely mediated through a direct interaction between AR and PAK6 since siRNA knock-down of AR in LAPC4 cells downregulated androgen-stimulated PAK6 activation. In addition, LNCap cells expressing a non-AR-interacting PAK6 mutant exhibited dampened androgen-stimulated kinase activation. As a consequence of androgen-stimulated activation, PAK6 was phosphorylated at multiple serine/threonine residues including the AR-interacting domain of PAK6. Furthermore, androgen-stimulation promoted prostate cancer cell motility and invasion were demonstrated in LNCap cells ectopically expressing PAK6-WT. In contrast, LNCap expressing non-AR-interacting mutant PAK6 did not respond to androgen stimulation with increased cell motility and invasion. Our results demonstrate that androgen-stimulated PAK6 activation is mediated through a direct interaction between AR and PAK6 and PAK6 activation promotes prostate cancer cells motility and invasion

Time-Dependent Mechanical Behavior of Proton Exchange Membrane Fuel Cell Electrodes

The electrodes used for Proton Exchange Membrane Fuel Cells (PEMFCs) are typically painted or sprayed onto the membrane during manufacturing, making it difficult to directly characterize their mechanical behavior as a stand-alone material. An experimental-numerical hybrid technique is devised to extract the electrode properties from the experimentally measured properties of Nafion® 211 membrane1 and a membrane electrode assembly (MEA) based on Nafion® 211 membrane at various temperatures, humidities, and strain rates. Within the linear regime, the rule-of-mixtures assuming an iso-strain condition is used to calculate the rate-dependent Young\u27s modulus of the electrodes. Beyond the linear regime, reverse analysis is conducted using finite element models of the MEA to determine the non-linear behavior of the electrodes. The mechanical damage mechanisms that occur in the MEA during tensile loading are also investigated through interrupted tension tests and then incorporated into the finite element models for determining the electrode behavior. The results suggest that the electrodes have similar behavior to Nafion® 211 membrane as functions of strain rate, temperature and humidity, but with lower Young\u27s modulus and proportional limit

Effect of Time-Dependent Material Properties on the Mechanical Behavior of PFSA Membranes Subjected to Humidity Cycling

A viscoelastic-plastic constitutive model is developed to characterize the time-dependent mechanical response of perfluorosulphonic acid (PFSA) membranes. This model is then used in finite element simulations of a representative fuel cell unit, (consisting of electrodes, gas diffusion layer and bipolar plates) subjected to standardized relative humidity (RH) cycling test conditions. The effects of hold times at constant RH, the feed rate of humidified air and sorption rate of water into the membrane on the stress response are investigated. While the longer hold times at high and low humidity lead to considerable redistribution of the stresses, the lower feed and sorption rates were found to reduce the overall stress levels in the membrane. The redistribution and reduction in stress magnitudes along with inelastic deformation during hydration eventually lead to development of residual tensile stresses after dehydration. Simulations indicate that these tensile stresses can be on the order of 9–10 MPa which may lead to mechanical degradation of the membrane. The simulation results show that time-dependent properties can have a significant effect on the in-plane stress response of the membrane