152 research outputs found

    An Empirical Analysis of Equity Market Expectations in the Recent Financial Turmoil Using Implied Moments and Jump Diffusion Processes

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    This paper investigates market expectations of future equity prices using the probability distribution and the moments implied in equity option prices. We first conduct, without assuming a particular model, a nonparametric analysis of the development of market expectations in four major markets during the financial turmoil following the summer of 2007. We then conduct a parametric analysis to reconsider these expectations from the perspective of a stochastic process, assuming jump diffusion processes that configure the implied distribution. These analyses reveal that the possibility of discontinuous price jumps in each country increased downwards during the recent financial turmoil, while volatilities determining the dispersion of continuous price changes surged. Viewing the results from the perspective of a probability distribution, we find that kurtosis and the absolute value of skewness declined, while variance dramatically increased.implied distribution, implied moment, jump diffusion process, nonparametric method, GMM, characteristic function GMM

    Electron Microscopic Studies of the Differentiation of Fat Cells in Human Fetal Skin**From the Department of Dermatology, Yamaguchi University, School of Medicine, Ube, Japan.

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    ABSTRACT1)Electron microscopic studies of primitive fat organs showing various degrees of fat storage from human fetuses 20 to 26 weeks of age were undertaken, with special reference to the origin of fat cells and the lipid formations in them. Based on this study, three types of cells, namely an undifferentiated-type cell, a young-type fat cell and a mature-type fat cell were discerned ultrastructurally, but they are considered to be identical concerning the morphology of mitochondria, smooth endoplasmic reticula and glycogen granules.2)Concerning the origin of white fat cells, it was revealed that young-type and mature-type fat cells are not derived from reticuloendothelial cells or fibroblasts but from a certain definite type of mesenchymal cell which we have referred to as the undifferentiated-type cell.3)The finding that cytoplasmic microvesicles are more prominent in young-type fat cells than in mature-type ones might be interpreted that the young-type cells may be actively releasing lipids or free fatty acids according to Williamson's concept of these organelles. But, contrary to Williamson's postulation, the young-type fat cells seem to be accumulating lipids or free fatty acids

    Diffusion-weighted imaging in the oral and maxillofacial region : usefulness of apparent diffusion coefficient maps and maximum intensity projection for characterization of normal structures and lesions

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    Background: The aim of this study was to investigate diffusion-weighted imaging (DWI) in the oral and maxillofacial region, with a special focus on the usefulness of apparent diffusion coefficient (ADC) maps and maximum intensity projection (MIP) for characterization of normal structures and lesions. Material/Methods: Thirty-five patients who underwent magnetic resonance imaging (MRI) for diagnosis of oral and maxillofacial lesions were included in this prospective study. DWI was performed on a 1.5 T unit, with b factor of 0 and 800 s/mm2; moreover, ADC maps were generated. ADC values were measured for normal structures, odontogenic infections, squamous cell carcinomas (SCC), and hemangiomas. Results: As regards the normal structures, the mean ADC value of the cerebrospinal fluid (3.65±0.60×10-3 mm2/s) in the upper neck area was higher than that of the spinal cord (0.74±0.15×10-3 mm2/s, P=0.000), lymph nodes (0.87±0.17×10-3 mm2/s, P=0.000), and Waldeyer’s ring (0.92±0.29×10-3 mm2/s, P=0.000). The mean ADC value of hemangiomas (1.52±0.31×10-3 mm2/s) was higher than that of odontogenic infections (0.85±0.36×10-3 mm2/s, P=0.034) and SCC (1.38±0.22×10-3 mm2/s, P=0.840). Furthermore, MIP (DWI) showed the normal structures and lesions in the oral and maxillofacial region in an improved way. Conclusions: DWI, ADC maps, and MIP can be used to characterize and differentiate normal structures and lesions in the oral and maxillofacial region

    Characteristic multimodal imaging of medication-related osteonecrosis of the jaw : comparison between oral and parenteral routes of medication administration

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    Background: To assess multimodal imaging features of medication-related osteonecrosis of the jaw (MRONJ) and to analyze the differences between oral and parenteral routes of medication administration. We retrospectively reviewed panoramic radiographs, CT, MRI, and bone scintigraphy of patients with MRONJ. Material/Methods: A retrospective study was conducted in 16 patients with MRONJ who underwent panoramic radiography, CT, MRI, and bone scintigraphy. Statistical analysis for the comparison between routes of medication administration and multimodal imaging features was performed with the Pearson's c2 test. Results: The percentage of cases with sequestrum separation was 25.0% (4/16 cases) on panoramic radiography and 81.3% (13/16 cases) on CT. The percentage of cases with periosteal bone proliferation on CT was 41.7% (5/12 cases) in the oral route of administration vs. 100% (4/4 cases) in the parenteral route of administration (p=0.042). The percentage of cases with spread of soft tissue inflammation to buccal and other spaces on CT and MRI was 33.3% (4/12 cases) in the oral route of administration vs. 100% (4/4 cases) in the parenteral route of administration (p=0.021). Conclusions: The sequestrum separation on panoramic radiography in patients with MRONJ was unclear in comparison to CT. Furthermore, characteristic CT findings of patients with MRONJ in the parenteral administration group were periosteal bone proliferation and spread of soft tissue inflammation to buccal and other spaces

    Comparison between squamous cell carcinoma and inflammatory diseases of the oral and maxillofacial region using gallium-67 scintigraphy with computed tomography and magnetic resonance imaging

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    Purpose: This study aimed to compare squamous cell carcinoma (SCC) with inflammatory diseases of the oral and maxillofacial region using gallium 67 (67Ga) scintigraphy with computed tomography (CT) and magnetic resonance imaging (MRI). Material and methods: Seventy patients with SCC and 15 patients with inflammatory diseases of the oral and maxillofacial region underwent 67Ga scintigraphy with CT and MRI. A comparison between imaging features of 67Ga scintigraphy, CT, and MRI and lesions was performed with the Pearson's chi-squared test. Results: 67Ga scintigraphy was positive for 25 of 39 patients with SCC positive on CT and/or MRI (64.1%) and for 13 of 15 patients with inflammatory diseases positive on CT and/or MRI (86.7%). The detection of inflammatory diseases with 67Ga scintigraphy was higher than that of SCC (p = 0.104). Conclusions: This study compared SCC with inflammatory diseases of the oral and maxillofacial region using 67Ga scintigraphy with CT and MRI. 67Ga scintigraphy is an effective technique for detection of inflammatory diseases of the oral and maxillofacial region

    Electrical Steels and Their Evaluation for Automobile Motors

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    Achieving high efficiency and high torque is an important target in EV motors. This paper describes the effect of the magnetic properties of electrical steels used as core materials for synchronous motors with permanent magnets, which are commonly used as the EV traction motors. It was confirmed that electrical steels, which have high flux density and low iron loss properties can realize high motor efficiency and torque. When PWM excitation is considered, thinner electrical steels are advantageous to suppress increased loss due to higher harmonics. Based on these results, electrical steels having high flux densities and low iron losses at high frequencies were developed. Document type: Articl

    Structural variations in parotid glands induced by radiation therapy in patients with oral carcinoma observed on contrast-enhanced computed tomography

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    Background: Xerostomia is one of the commonest radiation-induced complications in patients with head and neck carcinoma. The aim of this study was to assess structural variations in parotid glands induced by radiation therapy in patients with oral carcinoma with contras-enhanced computed tomography (CECT). Material/Methods: A retrospective study was performed in 41 patients with oral carcinoma who underwent CECT for head and neck malignancies before and after radiotherapy. We analyzed the relationship between parotid density variations, parotid volume change, as seen on CECT, and the mean radiation dose applied to the parotid glands in patients with oral carcinoma immediately after radiotherapy, and 2 and 3 years later. Results: Immediately after radiotherapy, high-density changes on contrast-enhanced CT were observed in 70.5% of the irradiated parotids. Low-density changes due to fat degeneration were seen in 46.2% and 72.2% of the irradiated parotids 2 and 3 years after radiotherapy, respectively. The mean dose applied to the parotids with the low-density changes and without such changes 3 years after radiotherapy was 46.0 Gy and 27.7 Gy, respectively (p=0.049). Furthermore, parotid shrinkage was observed in 63.6% of the irradiated parotids. Conclusions: This study suggests that the structural variations in parotid glands induced by radiotherapy included high-density changes that were observed immediately after radiotherapy and low-density changes that were seen at late follow-up. This study should be useful for clinicians in the assessment of radiation-induced injuries in the parotids with respect to early prediction of xerostomia

    Phospholipase C Produced by Clostridium botulinum Types C and D:Comparison of Gene, Enzymatic, and Biological Activities with Those of Clostridium perfringens Alpha-toxin

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    Clostridium botulinum type C and D strains recently have been found to produce PLC on egg yolk agar plates. To characterize the gene, enzymatic and biological activities of C. botulinum PLCs (Cb-PLCs), the cb-plc genes from 8 strains were sequenced, and 1 representative gene was cloned and expressed as a recombinant protein. The enzymatic and hemolytic activities of the recombinant Cb-PLC were measured and compared with those of the Clostridium perfringens alpha-toxin. Each of the eight cb-plc genes encoded a 399 amino acid residue protein preceded by a 27 residue signal peptide. The protein consists of 2 domains, the N- and C-domains, and the overall amino acid sequence identity between Cb-PLC and alpha-toxin was greater than 50%, suggesting that Cb-PLC is homologous to the alpha-toxin. The key residues in the N-domain were conserved, whereas those in the C-domain which are important in membrane interaction were different than in the alpha-toxin. As expected, Cb-PLC could hydrolyze egg yolk phospholipid, p-nitrophenylphosphorylcholine, and sphingomyelin, and also exhibited hemolytic activity;however, its activities were about 4- to over 200-fold lower than those of alpha-toxin. Although Cb-PLC showed weak enzymatic and biological activities, it is speculated that Cb-PLC might play a role in the pathogenicity of botulism or for bacterial survival

    Synchronization Error of Drum Kit Playing with a Metronome at Different Tempi by Professional Drummers

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    THE PRESENT STUDY EXAMINED THE SYNCHRONIZATION error (SE) of drum kit playing by professional drummers with an auditory metronome, focusing on the effects of motor effectors and tempi. Fifteen professional drummers attempted to synchronize a basic drumming pattern with a metronome as precisely as possible at tempi of 60, 120, and 200 beats per minute (bpm). In the 60 and 120 bpm conditions, the right hand (high-hat cymbals) showed small mean SE (∼2 ms), whereas the left hand (snare drum) and right foot (bass drum) preceded the metronome by about 10 ms. In the 200 bpm condition, the right hand was delayed by about 10 ms relative to the metronome, whereas the left hand and right foot showed small SE (∼1 ms). The absolute values of SE were smaller than those reported in previous tapping studies. In addition, the time series of SE were significantly correlated across the motor effectors, suggesting that each limb synchronized in relation to the other limbs rather than independently with the metronome
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