Determinants of Firm Boundaries: Empirical Analysis of the Japanese Auto Industry from 1984 to 2002

We have assessed the determinants of the choice of integration, relational contracting (keiretsu sourcing) and market sourcing by seven Japanese automobile manufacturers (OEMs) with respect to 54 components in light of contract economics. Our major findings are the following. First, the specificity and interdependency of a component significantly promotes vertical integration over keiretsu and keiretsu over market, consistent with transaction cost economics. Second, interdependency is a more important consideration for the former choice than for the latter choice, and the reverse is the case for specificity. This suggests that the hold-up risk due to specific investment can be often effectively controlled by a relational contracting based on keiretsu sourcing, while accommodating non-contractible design changes may often require vertical integration. Third, while higher testability of a component makes the effects of specificity significantly smaller, it also promotes the choice of keiretsu sourcing over market sourcing. One interpretation of this last result is that while higher testability improves the contractibility of the component with high specificity, it simultaneously enhances the advantage of keiretsu sourcing since it provides more opportunities for the supplier to explore new information for a collaborative exploitation with an OEM.

Effects of sodium on electrical properties in Cu2ZnSnS4 single crystal

pre-printWe have studied the effect of sodium on the electrical properties of Cu2ZnSnS4 (CZTS) single crystal by using temperature dependence of Hall effect measurement. The sodium substitution on the cation site in CZTS is observed from the increasing of unit-cell size by powder X-ray diffraction. Sodium increases the effective hole concentration and makes the thermal activation energy smaller. The degree of compensation decreases with sodium incorporation, thus the hole mobility is enhanced. We revealed that sodium is important dopant in CZTS to control the electrical properties

Asymmetrical membrane fluidity of bovine adrenal chromaffin cells and granules and effect of trichosporin-B-VIa

AbstractWe examined membrane fluidity of bovine adrenal chromaffin cells and chromaffin granules using cationic trimethylammonium derivative of diphenylhexatriene (TMA-DPH) as a fluorescence probe. After adding TMA-DPH to the suspension of chromaffin cells and that of granules, it first bound to the outer layer of the plasma membrane of the cells and that of the granule membrane, then gradually penetrated the inner layer of each membrane and distributed to both leaflets of the respective membranes. Accompanying increases in the ratio of incorporated probe on the cytoplasmic side of the chromaffin cell membrane, its fluorescence anisotropy gradually decreased. However, in chromaffin granules, the fluorescence anisotropy gradually increased with increases in the ratio of incorporated probe. These findings suggest that the inner layer of the plasma membrane and outer layer of the granular membrane are more fluid than the corresponding side of each membrane, which is suitable for the fusion between both membranes. We also examined the effect of trichosporin-B-VIa, a fungal ion channel forming α-aminoisobutyric acid-containing peptide, on the fluidity of chromaffin cells using TMA-DPH. The peptide decreased the fluorescence anisotropy and increased the fluorescence intensity in the concentration range that induced Ca2+ dependent catecholamine secretion, suggesting that a change in lipid dynamics of the lipid bilayer of the plasma membrane was induced by this peptide

Role of proline residue in the channel-forming and catecholamine-releasing activities of the peptaibol, trichosporin-B-VIa

AbstractTrichosporin-B-VIa (TS-B-VIa) has a Pro14-kinked helical structure which is considered to be important for the formation of peptaibol-type ion-channels in lipid bilayer membranes. TS-B-VIa and its analog [Aid14]TS-B-VIa with Pro → Aib substitution at position 14, resulting in a straight helical structure, were tested for ion-channel-forming activity in planar lipid bilayer membranes and for ability to induce catecholamine secretion from cultured bovine adrenal chromaffin cells. Voltage-dependent multi-channel conductance, which is characteristic of TS-B-VIa, was also observed for [Aid14]TS-B-VIa. In single-channel measurements, current fluctuations induced by [Aid14]TS-B-VIa had a shorter life-time and showed fewer substates than those induced by TS-B-VIa. Catecholamine secretion induced by these peptides at low concentrations is completely Ca2+-dependent. At high concentrations, TS-B-VIa-induced secretion was partly independent of external Ca 2+, but this was not the case for the analog. The differences of behavior can be explained in terms of the differences of hydrophobicity, amphiphilicity, and magnitude of dipole moment due to the conformational changes around position 14 and the C-terminal domain caused by the Pro → Aib substitution

Association between acetylcholine receptor characteristics in biceps motor endplates and the epidemiological predictors for conversion from ocular to generalized myasthenia gravis

Objective: Epidemiological studies have identified various predictors of conversion from ocular myasthenia gravis (OMG) to secondary generalized myasthenia gravis (SGMG), but none have been confirmed. We investigated the effects of the epidemiological conversion predictors on the destruction of motor endplates in the biceps of patients with OMG and attempted to identify predictors of conversion to SGMG histologically.Methods: Patients with clinically diagnosed OMG who requested immunohistological diagnosis and who underwent muscle biopsy were included in this study. We immunostained the biceps motor endplate and semi-quantitatively measured the density and number of AChRs to determine their association with the epidemiological predictors of conversion from OMG to SGMG.Results: Thirteen patients with OMG were included, of which two patients with positive AChR antibody and concomitant thymoma converted to SGMG. In the classification according to the presence of AChR antibody, the AChR densities tended to be lower in the antibody-positive group than in the negative group (p=0.079), and the AChR numbers were significantly lesser in the AChR antibody-positive group than in the negative group (p=0.019). There were no differences in AChR densities or numbers according to sex, presence of thymic abnormalities, or presence of comorbid autoimmune diseases.Conclusion: In OMG, the AChR numbers in motor endplates of the biceps were significantly lesser in the AChR antibodypositive group than in the negative group. Since the muscle strength tends to decrease as the number of AChRs decreases, AChR antibody positivity may be a predictor of OMG to SGMG conversion, but further studies are needed to confirm

Free-carrier dynamics and band tails in Cu[2] ZnSn (S[x]Se[1−x] )[4] : Evaluation of factors determining solar cell efficiency

We investigated the composition-dependent photocarrier dynamics in Cu[2] ZnSn(S[x]Se[1−x])[4] (CZTSSe) single crystals using various types of steady-state and time-resolved optical spectroscopy. Photoluminescence spectroscopy shows that the band-tail states formed below the band edge decrease monotonically with increasing Se content. THz time-resolved spectroscopy clarifies that an increase in the Se content leads to a shorter lifetime of the free photocarriers. A trade-off between the composition-dependent band-tail density and the free-carrier lifetime occurs in CZTSSe single crystals. Our experimental results provide insights into the physics behind the low and composition-dependent conversion efficiency of CZTSSe-based solar cells

H-D Substitution in Interstellar Solid Methanol: A Key Route for D Enrichment

Deuterium enrichment of interstellar methanol is reproduced experimentally for the first time via grain-surface H-D substitution in solid methanol at an atomic D/H ratio of 0.1. Although previous gas-grain models successfully reproduce the deuterium enrichments observed in interstellar methanol molecules (D/H of up to 0.4, compared to the cosmic ratio of $\sim 10^{-5})$, the models exclusively focus on deuterium fractionation resulting from the successive addition of atomic hydrogen/deuterium on CO. The mechanism proposed here represents a key route for deuterium enrichment that reproduces the high observed abundances of deuterated methanol, including multiple deuterations.Comment: 4 pages, 4 figures, Accepted to the ApJ

Flame retardance-donated lignocellulose nanofibers (LCNFs) by the Mannich reaction with (amino-1,3,5-triazinyl)phosphoramidates and their properties

Nitrogen/phosphorus-containing melamines (NPCM), a durable flame-retardant, were prepared by the successive treatment of ArOH (Ar = BrnC6H5−n, n = 0, 1, 2, and 3) with POCl3 and melamine monomer. The prepared flame-retardants were grafted through the CH2 unit to lignocellulose nanofibers (LCNFs) by the Mannich reaction. The resulting three-component products were characterized using FT-IR (ATR) and EA. The thermal behavior of the NPCM-treated LCNF fabric samples was determined using TGA and DSC analyses, and their flammability resistances were evaluated by measuring their Limited Oxygen Index (LOI) and the UL-94V test. A multitude of flame retardant elements in the fabric samples increased the LOI values as much as 45 from 20 of the untreated LCNFs. Moreover, the morphology of both the NPCM-treated LCNFs and their burnt fabrics was studied with a scanning electron microscope (SEM). The heat release lowering effect of the LCNF fabric against the water-based paint was observed with a cone calorimeter. Furthermore, the mechanical properties represented as the tensile strength of the NPCM-treated LCNF fabrics revealed that the increase of the NPCM content in the PP-composites led to an increased bending strength with enhancing the flame-retardance