Bias correction in a dynamic panel data model of economic growth: The African dummy re-examined

The discrepancy between the observed and expected growth rates of African economies in cross-country or panel growth regressions is often summarised in a significant African dummy. However, the existence of this dummy may be an artifact of the panel data techniques used. The standard LSDV (least squares dummy variable) method produces a large bias in the estimate of the coefficient on the lagged dependent variable, which could generate the observed African dummy. The lagged dependent variable in a growth model is used to calculate the cross-country rate of convergence. If, however, the convergence rate is overestimated, then the Africa dummy would result due to the clustering of African economies at the lower end of the world cross-country income distribution. Correcting for the bias - using Kiviet’s (1995) algorithm - allows a fresh look at the apparent systematic underperformance of African countries relative to their growth predictions. Little evidence remains of such underperformance by African economies once the relevant bias in the dynamic panel has been accounted for.growth regressions, dynamic panels, African dummy

Symmetry of large solutions of nonlinear elliptic equations in a ball

Let $g$ be a locally Lipschitz continuous real valued function which satisfies the Keller-Osserman condition and is convex at infinity, then any large solution of $-\Delta u+g(u)=0$ in a ball is radially symmetric

Inhibition of triosephosphate isomerase by phosphoenolpyruvate in the feedback-regulation of glycolysis.

The inhibition of triosephosphate isomerase (TPI) in glycolysis by the pyruvate kinase (PK) substrate phosphoenolpyruvate (PEP) results in a newly discovered feedback loop that counters oxidative stress in cancer and actively respiring cells. The mechanism underlying this inhibition is illuminated by the co-crystal structure of TPI with bound PEP at 1.6 Å resolution, and by mutational studies guided by the crystallographic results. PEP is bound to the catalytic pocket of TPI and occludes substrate, which accounts for the observation that PEP competitively inhibits the interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Replacing an isoleucine residue located in the catalytic pocket of TPI with valine or threonine altered binding of substrates and PEP, reducing TPI activity in vitro and in vivo. Confirming a TPI-mediated activation of the pentose phosphate pathway (PPP), transgenic yeast cells expressing these TPI mutations accumulate greater levels of PPP intermediates and have altered stress resistance, mimicking the activation of the PK-TPI feedback loop. These results support a model in which glycolytic regulation requires direct catalytic inhibition of TPI by the pyruvate kinase substrate PEP, mediating a protective metabolic self-reconfiguration of central metabolism under conditions of oxidative stress

CNT microtubes with entrapped Fe3O4 nanoparticles remove micropollutants through a heterogeneous electro-fenton process at neutral pH

Catalyst-coated carbon electrodes require two preparation stages: electrode assembly using carbon and polymeric binders and subsequent catalyst immobilization on the porous carbons electrode. Such conventional coating methods require several steps, which is time-, chemical-, and energy-consuming. Also, polymeric binders can impair the porosity and block catalytic sites of final electrodes. This study introduces a novel one-pot synthesis method in which Fe3O4 nanoparticles are entrapped within a multi-walled carbon nanotube network, the latter being templated with microtubular geometry. Such carbon microtubes (CMT) represent a standalone geometry, serving as a binder-free electrode for an energy-efficient heterogeneous electro-Fenton (HEF) process. Fe3O4-containing CMTs remove carbamazepine (CBZ), a frequently detected pharmaceutical micropollutant in water bodies. While almost all literature reports degradation at acidic conditions requiring the use of acid, this material system functions at pH 7 +/- 0.3 with lengthy reusability. The remarkable mineralization of the total oxidized CBZ emerges from the confinement of oxidation by-products in CMTs' 3D framework, where unselective radicals are formed once the electro-generated H2O2 reacts with embedded Fe3O4. Additionally, the 3D network prevents the entrapped catalysts from leaching in acidic environments because of the increased local pH during electrolysis

A Temporary Pause in the Replication Licensing Restriction Leads to Rereplication during Early Human Cell Differentiation

Gene amplifications in amphibians and flies are known to occur during development and have been well characterized, unlike in mammalian cells, where they are predominantly investigated as an attribute of tumors. Recently, we first described gene amplifications in human and mouse neural stem cells, myoblasts, and mesenchymal stem cells during differentiation. The mechanism leading to gene amplifications in amphibians and flies depends on endocycles and multiple origin-firings. So far, there is no knowledge about a comparable mechanism in normal human cells. Here, we describe rereplication during the early myotube differentiation of human skeletal myoblast cells, using fiber combing and pulse-treatment with EdU (50 -Ethynyl-20 -deoxyuridine)/CldU (5-Chlor-20 - deoxyuridine) and IdU (5-Iodo-20 -deoxyuridine)/CldU. We found rereplication during a restricted time window between 2 h and 8 h after differentiation induction. Rereplication was detected in cells simultaneously with the amplification of the MDM2 gene. Our findings support rereplication as a mechanism enabling gene amplification in normal human cells

Expression capable library for studies of Neisseria gonorrhoeae, version 1.0

Background The sexually transmitted disease, gonorrhea, is a serious health problem in developed as well as in developing countries, for which treatment continues to be a challenge. The recent completion of the genome sequence of the causative agent, Neisseria gonorrhoeae, opens up an entirely new set of approaches for studying this organism and the diseases it causes. Here, we describe the initial phases of the construction of an expression-capable clone set representing the protein-coding ORFs of the gonococcal genome using a recombination-based cloning system. Results The clone set thus far includes 1672 of the 2250 predicted ORFs of the N. gonorrhoeae genome, of which 1393 (83%) are sequence-validated. Included in this set are 48 of the 61 ORFs of the gonococcal genetic island of strain MS11, not present in the sequenced genome of strain FA1090. L-arabinose-inducible glutathione-S-transferase (GST)-fusions were constructed from random clones and each was shown to express a fusion protein of the predicted size following induction, demonstrating the use of the recombination cloning system. PCR amplicons of each ORF used in the cloning reactions were spotted onto glass slides to produce DNA microarrays representing 2035 genes of the gonococcal genome. Pilot experiments indicate that these arrays are suitable for the analysis of global gene expression in gonococci. Conclusion This archived set of Gateway® entry clones will facilitate high-throughput genomic and proteomic studies of gonococcal genes using a variety of expression and analysis systems. In addition, the DNA arrays produced will allow us to generate gene expression profiles of gonococci grown in a wide variety of conditions. Together, the resources produced in this work will facilitate experiments to dissect the molecular mechanisms of gonococcal pathogenesis on a global scale, and ultimately lead to the determination of the functions of unknown genes in the genome

1-(2-Hy­droxy­eth­yl)pyrrole-2,5-dione

The asymmetric unit of the title compound, C6H7NO3, contains two mol­ecules (A and B) related by a non-crystallographic twofold pseudo-axis. The mol­ecules are joined in the (AABB)n manner by O—H⋯O hydrogen bonds between their hy­droxy groups, thus forming C(2) chains along the a-axis direction. Neighboring mol­ecules of the same kind (A and A, or B and B) are related by inversion centers, so that all hy­droxy H atoms are disordered other two sets of sites with half occupancies (superimposed O—H⋯O and O⋯H—O fragments). The mol­ecules are further linked by C—H⋯O inter­actions, which can be considered to be weak hydrogen bonds

A strategy for the characterization of minute chromosome rearrangements using multiple color fluorescence in situ hybridization with chromosome-specific DNA libraries and YAC clones

The identification of marker chromosomes in clinical and tumor cytogenetics by chromosome banding analysis can create problems. In this study, we present a strategy to define minute chromosomal rearrangements by multicolor fluorescence in situ hybridization (FISH) with whole chromosome painting probes derived from chromosome-specific DNA libraries and Alu-polymerase chain reaction (PCR) products of various region-specific yeast artificial chromosome (YAC) clones. To demonstrate the usefulness of this strategy for the characterization of chromosome rearrangements unidentifiable by banding techniques, an 8p+ marker chromosome with two extra bands present in the karyotype of a child with multiple anomalies, malformations, and severe mental retardation was investigated. A series of seven-color FISH experiments with sets of fluorochrome-labeled DNA library probes from flow-sorted chromosomes demonstrated that the additional segment on 8p+ was derived from chromosome 6. For a more detailed characterization of the marker chromosome, three-color FISH experiments with library probes specific to chromosomes 6 and 8 were performed in combination with newly established telomeric and subtelomeric YAC clones from 6q25, 6p23, and 8p23. These experiments demonstrated a trisomy 6pter6p22 and a monosomy 8pter8p23 in the patient. The present limitations for a broad application of this strategy and its possible improvements are discusse

Coveting thy neighbors fitness as a means to resolve social dilemmas

In spatial evolutionary games the fitness of each individual is traditionally determined by the payoffs it obtains upon playing the game with its neighbors. Since defection yields the highest individual benefits, the outlook for cooperators is gloomy. While network reciprocity promotes collaborative efforts, chances of averting the impending social decline are slim if the temptation to defect is strong. It is therefore of interest to identify viable mechanisms that provide additional support for the evolution of cooperation. Inspired by the fact that the environment may be just as important as inheritance for individual development, we introduce a simple switch that allows a player to either keep its original payoff or use the average payoff of all its neighbors. Depending on which payoff is higher, the influence of either option can be tuned by means of a single parameter. We show that, in general, taking into account the environment promotes cooperation. Yet coveting the fitness of one's neighbors too strongly is not optimal. In fact, cooperation thrives best only if the influence of payoffs obtained in the traditional way is equal to that of the average payoff of the neighborhood. We present results for the prisoner's dilemma and the snowdrift game, for different levels of uncertainty governing the strategy adoption process, and for different neighborhood sizes. Our approach outlines a viable route to increased levels of cooperative behavior in structured populations, but one that requires a thoughtful implementation.Comment: 10 two-column pages, 5 figures; accepted for publication in Journal of Theoretical Biolog