Statistical Maintenance Time Estimation Based on Stochastic Differential Equation Models in OSS Development Project

At present, the method of earned value management is often applied to the actual software projects in various IT companies. Also, open source software (OSS) are used under the various situations, because the OSS are useful for many users to make a cost reduction, standardization of systems, and quick delivery. Many OSS are developed under the peculiar development style known as bazaar method. According to the bazaar method, many faults are detected and fixed by developers around the world, and the fixed result will be reflected in the next release. In this paper, we discuss an OSS effort estimation model by using a conventional stochastic differential equation model. Moreover, we propose an optimal maintenance problem based on the proposed effort estimation model. Then, we discuss the optimal maintenance problem minimizing the maintenance effort and satisfying the earned value requirement, simultaneously. In addition, we also propose a method of judging whether the optimal maintenance time is an appropriate time from the viewpoint of the transition probability distribution of the cumulative number of maintenance effort, because proper management of maintenance effort affects software quality. Furthermore, several numerical examples of optimal maintenance time problem with earned value requirement are shown by using the effort data under actual OSS projec

Central fibroma of the jaw bone: a case report.

Central fibromas developing from within the jaw bone are comparatively rare in contrast to fibromatoid lesions in other parts of the oral region. We report a 13-year-old girl with a central fibroma which developed in the jaw bone.</p

The vestibular system is critical for the changes in muscle and bone induced by hypergravity in mice

Gravity changes concurrently affect muscle and bone as well as induce alterations in vestibular signals. However, the role of vestibular signals in the changes in muscle and bone induced by gravity changes remains unknown. We therefore investigated the effects of vestibular lesions (VL) on the changes in muscle and bone induced by 3 g hypergravity for 4 weeks in C57BL/6J mice. Quantitative computed tomography analysis revealed that hypergravity increased muscle mass surrounding the tibia and trabecular bone mineral content, adjusting for body weight in mice. Hypergravity did not affect cortical bone and fat masses surrounding the tibia. Vestibular lesions blunted the increases in muscle and bone masses induced by hypergravity. Histological analysis showed that hypergravity elevated the cross‐sectional area of myofiber in the soleus muscle. The mRNA levels of myogenic genes such as MyoD, Myf6, and myogenin in the soleus muscle were elevated in mice exposed to hypergravity. Vestibular lesions attenuated myofiber size and the mRNA levels of myogenic differentiation markers enhanced by hypergravity in the soleus muscle. Propranolol, a β‐blocker, antagonized the changes in muscle induced by hypergravity. In conclusion, this study is the first to demonstrate that gravity changes affect muscle and bone through vestibular signals and subsequent sympathetic outflow in mice

Fullerene-linked tetrabenzoporphyrins for solution-processed organic photovoltaics: flexible vs. rigid linkers

Solution processing of a layer-by-layer structure is possible with a precursor approach, in which the soluble precursors of the insoluble or low-solubility target materials are spin-coated on the substrate and converted to insoluble semiconducting films by heating. We attempted to construct a p-i-n structure (p: p-layer; i: interlayer, a mixture of p- and n-materials; n: n-layer) using a solution process. To increase the donor-acceptor interface area, we synthesized covalently linked donor-acceptor compounds, tetrabenzoporphyrin (BP)-fullerene (C60) dyad. To investigate the effect of the covalent connection of the donor and acceptor units on the film morphology and on the OPV performances, the BP and fullerene units were connected by a flexible or rigid linker (f-BP-C60 or r-BP-C60). To synthesize these dyads, new synthetic routes with mono-meso-substituted BPs using [2 + 2] and [2 + 1 + 1] condensation reactions were performed. The intramolecular fluorescence quenching efficiency of BP by the C60 unit of f-BP-C60 was higher than that of r-BP-C60 in CH2Cl2 because of the flexibility of the linker and the close location of the C60 unit to the BP unit. The carrier mobility in the r-BP-C60 film measured by the space-charge-limited-current (SCLC) technique was better than that of the f-BP-C60 film, and the bulk heterojunction (BHJ)-type OPV performance of the r-BP-C60 film was better than that of the f-BP-C60 film. In spite of the superior OPV performance of the r-BP-C60 device compared to the f-BP-C60, the short circuit current density (JSC) and FF of the p-i-n device with BP, f-BP-C60, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) for p-, i- and n-layers was better than the device with r-BP-C60 as the i-layer. AFM images of the layers and OPV performances suggested that the flexible f-BP-C60 is suitable for the i-layer on the highly crystalline BP film because the roughness of the BP film is leveled by the f-BP-C60, and the electric properties of the device are improved by the smooth interface