Reducing the Size Distortion of the KPSS Test

This paper proposes a new stationarity test based on the KPSS test with less size distortion. We extend the boundary rule proposed by Sul, Phillips and Choi (2005) to the autoregressive spectral density estimator and parametrically estimate the long-run variance. We also derive the finite sample bias of the numerator of the test statistic up to the 1/T order and propose a correction to the bias term in the numerator. Finite sample simulations show that the correction term effectively reduces the bias in the numerator and that the finite sample size of our test is close to the nominal one as long as the long-run parameter in the model satisfies the boundary condition.Stationary test, size distortion, boundary rule, bias correction

Investigating Finite Sample Properties of Estimators for Approximate Factor Models When N Is Small

This paper examines the finite sample properties of estimators for approximate factor models when N is small via simulation study. Although the "rule-of-thumb" for factor models does not support using approximate factor models when N is small, we find that the principal component analysis estimator and quasi-maximum likelihood estimator proposed by Doz et al. (2008) perform very well even in this case. Our findings provide an opportunity for applying approximate factor models to low-dimensional data, which was thought to have been inappropriate for a long time.Approximate factor model, Principal components, Quasi-maximum likelihood

Fast Color Removal Method Considering Differences between Colors

When a color image is converted into a monochrome one, luminance components of the pixels have been used as gray-levels for the representation of the monochrome image in HDTV standard. However, saliencies of the image embedded only in the chrominance components are disappeared in the monochrome image converted by using luminance components. To cope with this problem, A.A. Gooch et al. have proposed the salience-preserving color removal method called “Color2Gray.” The monochrome image well reected the impression of an input color image can be yielded by Color2Gray. However, the calculation cost of that algorithm is tremendous, and its utility is not so much. In this paper, fast Color2Gray algorithms are proposed. The effectiveness of the proposed method is illustrated through the experiments

Biomechanical and tribological properties of the temporomandibular joint : a narrative review

Background and Objective: Osteoarthritis in the temporomandibular joint (TMJ-OA) is known as the end stage of TMJ disorders (TMDs), and most of TMJ-OA patients exhibit joint pain as a main symptom. TMJ-OA is a multifactorial disease, associated with articular cartilage breakdown and eventual joint destruction. Functional overloading and increased joint friction in the TMJ are recognized to induce degradation and abrasion of the joint components, leading to the onset and progression of TMJ-OA. Therefore, insight into the biomechanical and tribological properties of the articular components in the TMJ might contribute to better understanding of the etiology of TMJ degradation, leading to the development and progress of effective treatment remedy for TMJ-OA. The challenging project in TMJ biomechanics aims to identify biomechanical microenvironment in the TMJ, to develop the diagnosis system for TMDs, and to develop a new treatment remedy for TMDs including TMJ tissue engineering. Methods: The databases PubMed, MEDLINE, and Web of Science were searched to retrieve relevant articles published in English from January 2000 to December 2020 using the keywords “temporomandibular joint” “friction” “joint lubrication” and “tribology” to investigate the biomechanical and tribological properties of the TMJ. Key Content and Findings: The present review consists of three parts. Part I is a brief review of the biomechanical properties of the TMJ articular components. In Part II, the TMJ lubrication is explained from the viewpoint of the joint tribology. In the final remarks, the possibility of TMJ computed simulation will be discussed. Conclusions: Future studies with much efforts are required to measure and visualize the biomechanical microenvironment within the TMJ during mandibular movements in clinical aspect

Risk of hepatitis B reactivation in patients treated with tumor necrosis factor-a inhibitors

The use of tumor necrosis factor-a (TNF-a) inhibitors has been increasing especially in patients with rheumatoid arthritis (RA). As TNF-a inhibitors are strongly immunosuppressive, the occurrence of hepatitis B virus (HBV) reactivation has recently been observed. Reports suggest a higher risk of complicating HBV reactivation in carriers who are treated with TNF-a inhibitors. Therefore, HBV carriers are recommended to undergo prophylactic administration of nucleos(t)ide analogs (NAs). Our literary analysis uncovered several characteristics of de novo hepatitis B due to TNF-a inhibitors. First, the time between the start of TNF-a inhibitors and the occurrence of de novo hepatitis was longer than one year. Second, patients were usually treated with additional non-biologic agents, which also had immunosuppressive effects. Third, the disease could be fatal. Fourth, several types of TNF-a inhibitors exhibited a risk of developing de novo hepatitis. Although the incidence of de novo hepatitis B varied among reports (05%/year), it is suggested that patients with prior HBV infection are at risk of developing de novo hepatitis due to TNF-a inhibitors. Many reports maintain that regular measurement of HBV DNA is effective in preventing de novo hepatitis. Prophylactic administration of NAs is also considered useful to avoid de novo hepatitis, although the issue of cost-effectiveness needs to be addressed. Lastly, whereas maintenance of circulating anti-HBs titer using HB vaccines may be effective in responders to prevent de novo hepatitis, further studies are required to clarify the utility of HB vaccination.ArticleHEPATOLOGY RESEARCH. 42(4):333-339 (2012)journal articl

Signs, Symptoms, and Morphological Features of Idiopathic Condylar Resorption in Orthodontic Patients : A Survey-Based Study

Background: Idiopathic condylar resorption (ICR) is an aggressive degenerative disease of the temporomandibular joint that is most frequently observed in teenage girls. However, no specific cause of ICR has been identified. To explore the specific causes of the onset and progression of ICR, we performed a survey-based study on ICR in orthodontic patients and described its subjective symptoms, clinical signs, and condylar morphological features. Methods: A total of 1735 participants were recruited from 2193 orthodontic patients. For each participant, subjective symptoms and clinical signs of temporomandibular disorders (TMDs) were evaluated through clinical examination and a questionnaire. Furthermore, three-dimensional computed tomography (CT) was performed to diagnose ICR. Results: Among the 1735 patients evaluated, ICR was present in two male and ten female patients. All 12 patients had maxillary protrusion and an anterior open bite. Four patients with ICR underwent orthodontic treatment. Based on CT findings, patients with ICR had significantly different condylar sizes and shapes from patients with TMDs alone. Conclusions: The coexistence of intrinsic and extrinsic factors, such as sex-hormone imbalance and a history of orthodontic treatment, might lead to the onset of ICR. We suggest that growing patients suspected of having ICR should undergo CT evaluation because CT findings may precede clinical symptoms and signs

Guidelines for avoiding risks resulting from discontinuation of nucleoside/nucleotide analogs in patients with chronic hepatitis B

Nucleoside/nucleotide analogs (NUC) can lead to rapid reduction in hepatitis B virus (HBV) DNA levels in blood and normalization of alanine aminotransferase levels in many patients. They also provide histological improvement which results in a reduction in liver carcinogenesis. However, it is difficult to completely remove viruses even by NUC and there are some problems such as emergence of resistant strains and hepatitis relapse resulting from discontinuation of treatment. One of the reasons for this is that NUC reduce the HBV DNA level in blood but have almost no effects on the HBV cccDNA level in hepatocyte nuclei, which are the origins of HBV replication, and HBV cccDNA remains for a long period. For treatment with NUC in patients with hepatitis B, it is considered that NUC should not be easily discontinued because discontinuation often results in hepatitis relapse. However, it has not been clearly revealed when and how hepatitis relapses after discontinuation. Although some patients do not experience hepatitis relapse after discontinuation of NUC, or experience only mild relapse and finally achieve a stable condition, it has not been established how to identify such patients efficiently. We performed research to investigate characteristics of the course after discontinuation of treatment and definition of hepatitis relapse and estimate the relapse rate. Guidelines for avoiding risks resulting from discontinuation of NUCs 2012 is summarized based on the study results. Because the guidelines are written in Japanese, we explain them in English as a review article.ArticleHEPATOLOGY RESEARCH. 44(1):1-8 (2014)journal articl

Multiscale Retinex with Data-dependent Offset

As one of methods to improve the image quality, there is a method called multiscale retinex (MSR) which has been proposed by D.J. Jobson et al. In MSR, the reection components of an image are extracted and emphasized, and then the image with improved quality is obtained. This method is very useful and powerful especially for the visibility improvement of dark regions of the image. However, the resulting image tends to give us the unnatural impression because luminance components are removed, and the global contrast of the image is decreased in the processing. In this paper, a new MSR with a variable offset, which changes dependently on the local luminance information of the image, is proposed in order to overcome the disadvantage of the conventional MSR, and to further improve the image quality. Through the experiments, the effectiveness of the proposed method is illustrated

The Roles of MicroRNAs in Glioblastoma Biology and Biomarker

MicroRNAs (miRNAs) are small, noncoding RNAs transcribed from DNA that are 18–24 nucleotides in length. A single miRNA has the capacity to regulate a large number of target messenger RNAs (mRNAs), and the main function of miRNAs is to downregulate gene expression. A large set of miRNAs is overexpressed or downregulated in various human cancers compared with normal tissues, and gene silencing by miRNAs enhances tumor malignancies