Productivity Volatility and the Misallocation of Resources in Developing Economies

We investigate the role of dynamic production inputs and their associated adjustment costs in shaping the dispersion of total factor productivity (TFP) and static measures of capital misallocation within a country. Using data on 5,010 establishments in 33 developing countries from the World Bank’s Enterprise Research Data, we find that countries exhibiting greater time-series volatility of productivity are also characterized by greater cross-sectional dispersion in productivity. Volatility in TFP explains one quarter to one third of cross-country productivity dispersion. We document a similar relationship between productivity volatility and the dispersion of the marginal revenue product of capital (static capital misallocation). We then use a standard model of investment with adjustment costs, parameterized using numbers calibrated to U.S. data, to show that increasing the volatility of productivity to the level observed in these developing economies can quantitatively replicate the observed relationship between static misallocation and volatility observed in the data. We find that sixty-one percent of the static capital misallocation in the data is captured by the model’s prediction. Our findings suggest that the dynamic process governing productivity shocks is a first-order determinant of differences in misallocation and, hence, income across countries.

Irreversible proliferation of magnetic moments at cleaved surfaces of the topological Kondo insulator SmB6

The compound SmB$_6$ is the best established realization of a topological Kondo insulator, in which a topological insulator state is obtained through Kondo coherence. Recent studies have found evidence that the surface of SmB$_6$ hosts ferromagnetic domains, creating an intrinsic platform for unidirectional ballistic transport at the domain boundaries. Here, surface-sensitive X-ray absorption (XAS) and bulk-sensitive resonant inelastic X-ray scattering (RIXS) spectra are measured at the Sm N$_{4,5}$-edge, and used to evaluate electronic symmetries, excitations and temperature dependence near the surface of cleaved samples. The XAS data show that the density of large-moment atomic multiplet states on a cleaved surface grows irreversibly over time, to a degree that likely exceeds a related change that has recently been observed in the surface 4f orbital occupation

A significant improvement in the superconducting properties of MgB2 by co-doping with graphene and nano-SiC

The effects of graphene (G) and nanosilicon carbide (SiC) co-doping on the superconducting properties of MgB2 were studied using bulk samples. SiC remains one of the best dopants which can significantly improve the high field performance, while graphene is emerging as a new dopant for MgB2, which can improve the zero field critical current density (Jc). The superconducting properties characterized by Jc, the intergrain connectivity, and the critical fields were significantly improved by the use of both SiC and graphene as dopants

Recent progress in the theory of random surfaces and simplicial quantum gravity

Some of the recent developments in the theory of random surfaces and simplicial quantum gravity is reviewed. For 2d quantum gravity this includes the failure of Regge calculus, our improved understanding of the $c>1$ regime, some surprises for q-state Potts models with $q > 4$, attempts to use renormalization group techniques, new critical behavior of random surface models with extrinsic curvature and improved algorithms. For simplicial quantum gravity in higher dimensions it includes a discussion of the exponential entropy bound needed for the models to be well defined, the question of ``computational ergodicity'' and the question of how to extract continuum behavior from the lattice simulations.Comment: 14 pages, missing csh command added to the tar compressed uuencoded ps-file. After removing header use csh file.uu to get ps-fil

(Mis)Allocation, Market Power, and Global Oil Extraction

We propose an approach to measuring the misallocation of production in a market that compares actual industry cost curves to undistorted (counterfactual) supply curves. As compared to traditional, TFPR-based, misallocation measures, this approach leverages cost data, such that results are readily mapped to welfare metrics. As an application, we analyze global crude oil extraction and quantify the extent of misallocation therein, together with the proportion attributable to market power. From 1970 to 2014, we find substantial misallocation, in the order of 744 billion USD, 14.1 percent to 21.9 percent of which is attributable to market power

Escherichia coli TatA and TatB Proteins Have N-out, C-in Topology in Intact Cells

The twin arginine protein transport (Tat) system translocates folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of chloroplasts. In Escherichia coli, TatA, TatB, and TatC are essential components of the machinery. A complex of TatB and TatC acts as the substrate receptor, whereas TatA is proposed to form the Tat transport channel. TatA and TatB are related proteins that comprise an N-terminal transmembrane helix and an adjacent amphipathic helix. Previous studies addressing the topological organization of TatA have given conflicting results. In this study, we have addressed the topological arrangement of TatA and TatB in intact cells by labeling of engineered cysteine residues with the membrane-impermeable thiol reagent methoxypolyethylene glycol maleimide. Our results show that TatA and TatB share an N-out, C-in topology, with no evidence that the amphipathic helices of either protein are exposed at the periplasmic side of the membrane. We further show that the N-out, C-in topology of TatA is fixed and is not affected by the absence of other Tat components or by the overproduction of a Tat substrate. These data indicate that topological reorganization of TatA is unlikely to accompany Tat-dependent protein transport

Application of Novel PCR-Based Methods for Detection, Quantitation, and Phylogenetic Characterization of Sutterella Species in Intestinal Biopsy Samples from Children with Autism and Gastrointestinal Disturbances

Gastrointestinal disturbances are commonly reported in children with autism and may be associated with compositional changes in intestinal bacteria. In a previous report, we surveyed intestinal microbiota in ileal and cecal biopsy samples from children with autism and gastrointestinal dysfunction (AUT-GI) and children with only gastrointestinal dysfunction (Control-GI). Our results demonstrated the presence of members of the family Alcaligenaceae in some AUT-GI children, while no Control-GI children had Alcaligenaceae sequences. Here we demonstrate that increased levels of Alcaligenaceae in intestinal biopsy samples from AUT-GI children result from the presence of high levels of members of the genus Sutterella. We also report the first Sutterella-specific PCR assays for detecting, quantitating, and genotyping Sutterella species in biological and environmental samples. Sutterella 16S rRNA gene sequences were found in 12 of 23 AUT-GI children but in none of 9 Control-GI children. Phylogenetic analysis revealed a predominance of either Sutterella wadsworthensis or Sutterella stercoricanis in 11 of the individual Sutterella-positive AUT-GI patients; in one AUT-GI patient, Sutterella sequences were obtained that could not be given a species-level classification based on the 16S rRNA gene sequences of known Sutterella isolates. Western immunoblots revealed plasma IgG or IgM antibody reactivity to Sutterella wadsworthensis antigens in 11 AUT-GI patients, 8 of whom were also PCR positive, indicating the presence of an immune response to Sutterella in some children

Bayesian Modeling of Perceived Surface Slant from Actively-Generated and Passively-Observed Optic Flow

We measured perceived depth from the optic flow (a) when showing a stationary physical or virtual object to observers who moved their head at a normal or slower speed, and (b) when simulating the same optic flow on a computer and presenting it to stationary observers. Our results show that perceived surface slant is systematically distorted, for both the active and the passive viewing of physical or virtual surfaces. These distortions are modulated by head translation speed, with perceived slant increasing directly with the local velocity gradient of the optic flow. This empirical result allows us to determine the relative merits of two alternative approaches aimed at explaining perceived surface slant in active vision: an “inverse optics” model that takes head motion information into account, and a probabilistic model that ignores extra-retinal signals. We compare these two approaches within the framework of the Bayesian theory. The “inverse optics” Bayesian model produces veridical slant estimates if the optic flow and the head translation velocity are measured with no error; because of the influence of a “prior” for flatness, the slant estimates become systematically biased as the measurement errors increase. The Bayesian model, which ignores the observer's motion, always produces distorted estimates of surface slant. Interestingly, the predictions of this second model, not those of the first one, are consistent with our empirical findings. The present results suggest that (a) in active vision perceived surface slant may be the product of probabilistic processes which do not guarantee the correct solution, and (b) extra-retinal signals may be mainly used for a better measurement of retinal information