Has there always been underpricing and long-run underperformance? : IPOs in Germany before World War I

This paper provides empirical evidence on initial public offerings (IPOs) by investigating the pricing and long-run performance of IPOs using a unique data set collected on the German capital market before World War I. Our findings indicate that underpricing of IPOs has existed, but has significantly decreased over time in our sample. Employing a mixture of distributions approach we also find evidence of price stabilization of IPOs. Concerning long-run performance, investors who bought their shares in the early after-market and held them for more than three years experienced significantly lower returns than the respective industry as a whole. Earlier versions of this paper were presented at the ABN-AMRO Conference on IPOs in Amsterdam, the Annual Meetings of the European Finance Association, the Annual Meetings of the Verein für Socialpolitik, the IX Tor Vergata International Conference on Banking and Finance in Rome, and at Johann Wolfgang Goethe-University in Frankfurt

Overcoming systematic DFT errors for hydrocarbon reaction energies

Despite the widespread use and numerous successful applications of density functional theory, descriptions of hydrocarbon reaction energies remain problematic. Illustrative examples include large underestimation of energies associated with alkane bond separation reactions and poor general description of intramolecular dispersion in hydrocarbons (e.g., B3LYP, MAD=14.1kcalmol−1). More recent, but not readily availably functionals, along with efficient posteriori corrections, not only show considerable improvement in the energy description of hydrocarbons but also help identify the sources of error in traditional DFT. Interactions in branched alkanes and compact hydrocarbons are adequately mimicked by systems compressed below their typical van der Waals distances. At these distances, standard DFT exchange functionals are overly repulsive for non-bonded density overlaps, and significant improvement is offered by the long-range corrected exchange functionals (e.g., LC-BLYP0.33, MAD=5.5kcalmol−1). For those systems, the neglect of long-range dispersion is found to be a critical shortcoming, as well as "overlap dispersion”, for which non-negligible amounts are captured by the correlation functional. Accounting for the missing dispersion interactions is of key importance. Accordingly, most noteworthy improvements over standard functionals are obtained by using non-local van der Waals density functionals (e.g., LC-S-VV09, MAD=3.6kcalmol−1, rPW86-VV09, MAD=5.8kcalmol−1), a dispersion corrected double hybrid (B2PLYP-D, MAD=2.5kcalmol−1), or by the addition of an atom pairwise density-dependent dispersion correction to a standard functional (e.g., PBE-dDXDM, MAD=0.8kcalmol−1). To a lesser extent, the reduction of the delocalization error (e.g., MCY3, MAD=6.3kcalmol−1) or careful parameter fitting (e.g., M06-2X, MAD=5.6kcalmol−1) also lowers the error

Splicing of human immunodeficiency virus RNA is position-dependent suggesting sequential removal of introns from the 5′ end

Transcription of the HIV-1 genome yields a single primary transcript, which is alternatively spliced to >30 mRNAs. Productive infection depends on inefficient and regulated splicing and appears to proceed in a tight 5′ to 3′ order. To analyse whether sequential splicing is mediated by the quality of splice sites or by the position of an intron, we inserted the efficient β-globin intron (BGI) into the 3′ region or 5′UTR of a subgenomic expression vector or an infectious proviral plasmid. RNA analysis revealed splicing of the 3′ BGI only if all upstream introns were removed, while splicing of the same intron in the 5′UTR was efficient and independent of further splicing. Furthermore, mutation of the upstream splice signal in the subgenomic vector did not eliminate the inhibition of 3′ splicing, although the BGI sequence was the only intron in this case. These results suggest that downstream splicing of HIV-1 RNAs is completely dependent on prior splicing of all upstream intron(s). This hypothesis was supported by the mutation of the major 5′ splice site in the HIV-1 genome, which completely abolished all splicing. It appears likely that the tight order of splicing is important for HIV-1 replication, which requires the stable production of intron containing RNAs, while splicing of 3′ introns on incompletely spliced RNAs would be likely to render them subject to nonsense-mediated decay

Continuous function optimization using hybrid ant colony approach with orthogonal design scheme

A hybrid Orthogonal Scheme Ant Colony Optimization (OSACO) algorithm for continuous function optimization (CFO) is presented in this paper. The methodology integrates the advantages of Ant Colony Optimization (ACO) and Orthogonal Design Scheme (ODS). OSACO is based on the following principles: a) each independent variable space (IVS) of CFO is dispersed into a number of random and movable nodes; b) the carriers of pheromone of ACO are shifted to the nodes; c) solution path can be obtained by choosing one appropriate node from each IVS by ant; d) with the ODS, the best solved path is further improved. The proposed algorithm has been successfully applied to 10 benchmark test functions. The performance and a comparison with CACO and FEP have been studied

Electronic Elements Governing the Binding of Small Molecules to a [Fe]-hydrogenase Mimic

[Fe]-hydrogenase, one of three types of hydrogenases, activates molecular hydrogen. Here, using DFT computations, we examine the electronic elements governing the binding of small ligands to a recently synthesized [Fe]-hydrogenase biomimic. Computed reaction free energies indicate that anionic species, such as CN- and H-, and acceptors, such as CO, bind favourably with the Fe centre. Ligands such as H2O, CH3CN, and H-2, however, do not bind iron. Protonation of an adjacent thiolate ligand on the mimic significantly increases the energies of ligand binding. Additional computational analysis reveals that the degree of electron donation from the ligand to the mimic correlates strongly with overall binding ability. The results give insights into the electronic elements of iron-small-molecule interaction in these model complexes

Natural inspirations for metal–ligand cooperative catalysis

In conventional homogeneous catalysis, supporting ligands act as spectators that do not interact directly with substrates. However, in metal–ligand cooperative catalysis, ligands are involved in facilitating reaction pathways that would be less favourable were they to occur solely at the metal centre. This catalysis paradigm has been known for some time, in part because it is at play in enzyme catalysis. For example, studies of hydrogenative and dehydrogenative enzymes have revealed striking details of metal–ligand cooperative catalysis that involve functional groups proximal to metal active sites. In addition to the more well-known [FeFe]-hydrogenase and [NiFe]-hydrogenase enzymes, [Fe]-hydrogenase, lactate racemase and alcohol dehydrogenase each makes use of cooperative catalysis. This Perspective highlights these enzymatic examples of metal–ligand cooperative catalysis and describes functional bioinspired molecular catalysts that also make use of these motifs. Although progress has been made in developing molecular catalysts, considerable challenges will need to be addressed before we have synthetic catalysts of practical value

Influence of cargo size on Ran and energy requirements for nuclear protein import

Previous work has shown that the transport of some small protein cargoes through the nuclear pore complex (NPC) can occur in vitro in the absence of nucleoside triphosphate hydrolysis. We now demonstrate that in the importin α/β and transportin import pathways, efficient in vitro transport of large proteins, in contrast to smaller proteins, requires hydrolyzable GTP and the small GTPase Ran. Morphological and biochemical analysis indicates that the presence of Ran and GTP allows large cargo to efficiently cross central regions of the NPC. We further demonstrate that this function of RanGTP at least partly involves its direct binding to importin β and transportin. We suggest that RanGTP functions in these pathways to promote the transport of large cargo by enhancing the ability of import complexes to traverse diffusionally restricted areas of the NPC

Overcoming systematic DFT errors for hydrocarbon reaction energies

Despite the widespread use and numerous successful applications of density functional theory, descriptions of hydrocarbon reaction energies remain problematic. Illustrative examples include large underestimation of energies associated with alkane bond separation reactions and poor general description of intramolecular dispersion in hydrocarbons (e.g., B3LYP, MAD = 14.1 kcal mol-1). More recent, but not readily availably functionals, along with efficient posteriori corrections, not only show considerable improvement in the energy description of hydrocarbons but also help identify the sources of error in traditional DFT. Interactions in branched alkanes and compact hydrocarbons are adequately mimicked by systems compressed below their typical van der Waals distances. At these distances, standard DFT exchange functionals are overly repulsive for non-bonded density overlaps, and significant improvement is offered by the long-range corrected exchange functionals (e.g., LC-BLYP0.33, MAD = 5.5 kcal mol-1). For those systems, the neglect of long-range dispersion is found to be a critical shortcoming, as well as ‘‘overlap dispersion’’, for which non-negligible amounts are captured by the correlation functional. Accounting for the missing dispersion interactions is of key importance. Accordingly, most noteworthy improvements over standard functionals are obtained by using non-local van der Waals density functionals (e.g., LC-S-VV09, MAD = 3.6 kcal mol-1, rPW86-VV09, MAD = 5.8 kcal mol-1), a dispersion corrected double hybrid (B2PLYP-D, MAD = 2.5 kcal mol-1), or by the addition of an atom pairwise densitydependent dispersion correction to a standard functional (e.g., PBE-dDXDM, MAD = 0.8 kcal mol-1). To a lesser extent, the reduction of the delocalization error (e.g., MCY3, MAD = 6.3 kcal mol-1) or careful parameter fitting (e.g., M06-2X, MAD = 5.6 kcal mol-1) also lowers the errors

Alkynylation of Thiols with Ethynylbenziodoxolone (EBX) Reagents: alpha- or beta- pi-Addition?

The alkynylation of thiols with EthynylBenziodoXolone (EBX) reagents is a fast and chemoselective method for the synthesis of thioalkynes. Combined experimental and computational studies are reported, which led to the identification of a new mechanism for this reaction, proceeding via an initial sulfur iodine interaction followed by beta-addition, alpha-elimination, and a 1,2-shift. Depending on the substituent on the alkyne, this mechanism can be favored over the previously disclosed concerted alpha-addition rti pathway

Bimetallic Oxidative Addition in Nickel-Catalyzed Alkyl-Aryl Kumada Coupling Reactions

The mechanism of alkylaryl Kumada coupling catalyzed by the nickel pincer complex Nickamine was studied. Experiments using radical-probe substrates and DFT calculations established a bimetallic oxidative addition mechanism. Kinetic measurements showed that transmetalation rather than oxidative addition was the turnover-determining step. The transmetalation involved a bimetallic pathway