Agency Contracts, Noncommitment Timing Strategies, and Real Options

Given an owner's noncommitment timing strategy and a manager's hidden action, we consider how the optimal compensation contract for the manager is designed and how the corresponding timing decisions to launch the project and replace the manager are determined. Using a real options approach, we show that in comparison with the firstbest case, the higher (lower)-quality project is launched later (at the same time as the first-best case), whereas the incumbent manager is replaced earlier. We also indicate that compared with the case of the owner’s commitment timing strategy and the manager's hidden action, the higher (lower)-quality project is launched later (at the same time as the first-best case), whereas the incumbent manager is (is not necessarily) replaced later if the hidden-action problem is severe enough (is not severe enough). Unlike the folklore result of the standard moral hazard model, severance pay may serve to minimize the compensation for the manager's loss of his option value caused by loss of corporate control by committing the owner to delaying replacement of the manager if the hidden-action problem is not too severe.CEO turnover, executive compensation, noncommitment, real options, severance pay.

Shift Energies of Characteristic X-rays and Auger Electrons for Ionized Atoms

Shift energies of characteristic X-rays and Auger electrons for several ionized atoms of Z＝6～17 have been computed as a function of the degree of ionization, taking Larkins' Hartree-Fock-Slater calculations for neon (Z＝10) and argon (Z＝18) as standards. A reasonable agreement is seen with the observed shift energies of X-rays for multiply ionized aluminium

Identification and characterization of novel components of a Ca2+/calmodulin-dependent protein kinase cascade in HeLa cells

AbstractIn this report, we cloned a novel calmodulin-kinase (CaM-KIδ) from HeLa cells and characterized its activation mechanism. CaM-KIδ exhibits Ca2+/CaM-dependent activity that is enhanced (∼30-fold) in vitro by phosphorylation of its Thr180 by CaM-K kinase (CaM-KK)α, consistent with detection of CaM-KIδ-activating activity in HeLa cells. We also identified a novel CaM-KKβ isoform (CaM-KKβ-3) in HeLa cells whose activity was highly Ca2+/CaM-independent. Transiently expressed CaM-KIδ exhibited enhanced protein kinase activity in HeLa cells without ionomycin stimulation. This sustained activation of CaM-KIδ was completely abolished by Thr180Ala mutation and inhibited by CaM-KK inhibitor, STO-609, indicating a functional CaM-KK/CaM-KIδ cascade in HeLa cells

The Use of Event-Related Potentials in Psychological Research

Event-related potentials (ERPs) are voltage fluctuations of the brain that are time-locked to some physical or mental occurrence. These potentials can be recorded safely from the human scalp and provide valuable information about the brain activity associated with perception, cognition, and behavior. This paper deals with theoretical issues concerning the use of ERPs in psychological research. Following a brief description of the basic method of ERP recording, technical problems that can occur in the recording and analysis of the ERP were discussed (e.g., ocular artifacts, averaging, and individual differences). Then, the problems of isolating and interpreting ERP components were addressed. Finally, the relationship between the ERP and other psychological measures was discussed in the light of functional systems of the brain. It was concluded that the ERP can serve as a valuable tool in psychological research only if it is combined with other psychological measures

Structural characterization of a binuclear center of a Cu-containing NO reductase homologue from Roseobacter denitrificans: EPR and resonance Raman studies

AbstractAerobic phototrophic bacterium Roseobacter denitrificans has a nitric oxide reductase (NOR) homologue with cytochrome c oxidase (CcO) activity. It is composed of two subunits that are homologous with NorC and NorB, and contains heme c, heme b, and copper in a 1:2:1 stoichiometry. This enzyme has virtually no NOR activity. Electron paramagnetic resonance (EPR) spectra of the air-oxidized enzyme showed signals of two low-spin hemes at 15 K. The high-spin heme species having relatively low signal intensity indicated that major part of heme b3 is EPR-silent due to an antiferromagnetic coupling to an adjacent CuB forming a Fe–Cu binuclear center. Resonance Raman (RR) spectrum of the oxidized enzyme suggested that heme b3 is six-coordinate high-spin species and the other hemes are six-coordinate low-spin species. The RR spectrum of the reduced enzyme showed that all the ferrous hemes are six-coordinate low-spin species. ν(Fe–CO) and ν(C–O) stretching modes were observed at 523 and 1969 cm−1, respectively, for CO-bound enzyme. In spite of the similarity to NOR in the primary structure, the frequency of ν(Fe–CO) mode is close to those of aa3- and bo3-type oxidases rather than that of NOR

Observation of a Dirac nodal line in AlB2

We have performed angle-resolved photoemission spectroscopy of AlB2 which is isostructural to high-temperature superconductor MgB2. Using soft-x-ray photons, we accurately determined the three-dimensional bulk band structure and found a highly anisotropic Dirac-cone band at the K point in the bulk hexagonal Brillouin zone. This band disperses downward on approaching the H point while keeping its degeneracy at the Dirac point, producing a characteristic Dirac nodal line along the KH line. We also found that the band structure of AlB2 is regarded as a heavily electron-doped version of MgB2 and is therefore well suited for fully visualizing the predicted Dirac nodal line. The present results suggest that (Al,Mg)B2 system is a promising platform for studying the interplay among Dirac nodal line, carrier doping, and possible topological superconducting properties.Comment: 6 pages, 3 figure

Pravastatin restored the infarct size-limiting effect of ischemic preconditioning blunted by hypercholesterolemia in the rabbit model of myocardial infarction

AbstractOBJECTIVESWe tested to find out whether pravastatin restores the infarct size (IS)-limiting effect of ischemic preconditioning (IP) and if it has any effect on the IP-induced activation of adenosine producing enzyme ecto-5′-nucleotidase which plays a key role in the IP-induced cardioprotection.BACKGROUNDThe IS-limiting effect of IP is blunted by hypercholesterolemia. Recently, HMG-CoA reductase inhibitors are shown to have direct cytoprotective effects.METHODSRabbits were fed with a normal or cholesterol (1%) added diet with or without pravastatin (5 mg/kg/day) treatment. Infarct size was measured after 30 min occlusion and 3 h reperfusion of circumflex coronary artery with or without the IP procedure (5 min occlusion and 10 min reperfusion). Additionally, ecto-5′-nucleotidase activities of ischemic and nonischemic myocardium were measured immediately after IP procedure.RESULTSThis dose of pravastatin did not normalize the increased level of serum cholesterol. The IS-limiting effect of preceding IP (IS reduced from 36.7% to 9.6%, p < 0.001) was abolished by hypercholesterolemia (from 46.1% to 31.3%, p = NS) and restored by pravastatin treatment (from 35.2% to 9.4%, p < 0.001). Pravastatin treatment did not affect IS or the effect of IP under normocholesterolemia. The activation of ecto-5′-nucleotidase presented as the activity ratio of ischemic to nonischemic myocardium (3.1-fold in normocholesterolemia) was blunted by hypercholesterolemia (1.8-fold, p < 0.05) and restored by pravastatin treatment (2.9-fold).CONCLUSIONSPravastatin, at the dose serum cholesterol was not normalized, restored the IS-limiting effect of IP and IP-induced ecto-5′-nucleotidase activation, which were both blunted by hypercholesterolemia. The activation of ecto-5′-nucleotidase may be worth further investigation as a possible mechanism for the hypercholesterolemia-induced retardation and pravastatin-mediated restoration of the cardioprotective effect of IP

Direct electrochemical analyses of human cytochromes b5 with a mutated heme pocket showed a good correlation between their midpoint and half wave potentials

<p>Abstract</p> <p>Background</p> <p>Cytochrome <it>b</it>₅performs central roles in various biological electron transfer reactions, where difference in the redox potential of two reactant proteins provides the driving force. Redox potentials of cytochromes <it>b</it>₅span a very wide range of ~400 mV, in which surface charge and hydrophobicity around the heme moiety are proposed to have crucial roles based on previous site-directed mutagenesis analyses.</p> <p>Methods</p> <p>Effects of mutations at conserved hydrophobic amino acid residues consisting of the heme pocket of cytochrome <it>b</it>₅were analyzed by EPR and electrochemical methods. Cyclic voltammetry of the heme-binding domain of human cytochrome <it>b</it>₅(HLMW<it>b</it>₅) and its site-directed mutants was conducted using a gold electrode pre-treated with β-mercarptopropionic acid by inclusion of positively-charged poly-L-lysine. On the other hand, static midpoint potentials were measured under a similar condition.</p> <p>Results</p> <p>Titration of HLMW<it>b</it>₅with poly-L-lysine indicated that half-wave potential up-shifted to -19.5 mV when the concentration reached to form a complex. On the other hand, midpoint potentials of -3.2 and +16.5 mV were obtained for HLMW<it>b</it>₅in the absence and presence of poly-L-lysine, respectively, by a spectroscopic electrochemical titration, suggesting that positive charges introduced by binding of poly-L-lysine around an exposed heme propionate resulted in a positive shift of the potential. Analyses on the five site-specific mutants showed a good correlation between the half-wave and the midpoint potentials, in which the former were 16~32 mV more negative than the latter, suggesting that both binding of poly-L-lysine and hydrophobicity around the heme moiety regulate the overall redox potentials.</p> <p>Conclusions</p> <p>Present study showed that simultaneous measurements of the midpoint and the half-wave potentials could be a good evaluating methodology for the analyses of static and dynamic redox properties of various hemoproteins including cytochrome <it>b</it>₅. The potentials might be modulated by a gross conformational change in the tertiary structure, by a slight change in the local structure, or by a change in the hydrophobicity around the heme moiety as found for the interaction with poly-L-lysine. Therefore, the system consisting of cytochrome <it>b</it>₅and its partner proteins or peptides might be a good paradigm for studying the biological electron transfer reactions.</p