F^2-Softmax: Diversifying Neural Text Generation via Frequency Factorized Softmax

Despite recent advances in neural text generation, encoding the rich diversity in human language remains elusive. We argue that the sub-optimal text generation is mainly attributable to the imbalanced token distribution, which particularly misdirects the learning model when trained with the maximum-likelihood objective. As a simple yet effective remedy, we propose two novel methods, F^2-Softmax and MefMax, for a balanced training even with the skewed frequency distribution. MefMax assigns tokens uniquely to frequency classes, trying to group tokens with similar frequencies and equalize frequency mass between the classes. F^2-Softmax then decomposes a probability distribution of the target token into a product of two conditional probabilities of (i) frequency class, and (ii) token from the target frequency class. Models learn more uniform probability distributions because they are confined to subsets of vocabularies. Significant performance gains on seven relevant metrics suggest the supremacy of our approach in improving not only the diversity but also the quality of generated texts.Comment: EMNLP 202

Adjacent Segment Pathology Following Anterior Decompression and Fusion Using Cage and Plate for the Treatment of Degenerative Cervical Spinal Diseases

Study DesignRetrospective study.PurposeTo analyze the incidence and prevalence of clinical adjacent segment pathology (CASP) following anterior decompression and fusion with cage and plate augmentation for degenerative cervical diseases.Overview of LiteratureNo long-term data on the use of cage and plate augmentation have been reported.MethodsThe study population consisted of 231 patients who underwent anterior cervical discectomy and fusion (ACDF) with cage and plate for degenerative cervical spinal disease. The incidence and prevalence of CASP was determined by using the Kaplan-Meier survival analysis. To analyze the factors that influence CASP, data on preoperative and postoperative sagittal alignment, spinal canal diameter, the distance between the plate and adjacent disc, extent of fusion level, and the presence or absence of adjacent segment degenerative changes by imaging studies were evaluated.ResultsCASP occurred in 15 of the cases, of which 9 required additional surgery. At 8-year follow-up, the average yearly incidence was 1.1%. The rate of disease-free survival based on Kaplan-Meier survival analysis was 93.6% at 5 years and 90.2% at 8 years. No statistically significant differences in CASP incidence based on radiological analysis were observed. Significantly high incidence of CASP was observed in the presence of increased adjacent segment degenerative changes (p<0.001).ConclusionsACDF with cage and plate for the treatment of degenerative cervical disease is associated with a lower incidence in CSAP by 1.1% per year, and the extent of preoperative adjacent segment degenerative changes has been shown as a risk factor for CASP

Determination of an Applicable FRAX Model in Korean Women

We investigated which of the three FRAX fracture risk assessment tool models is most applicable to Korean women. For 306 postmenopausal women (mean age, 77 yr) with a hip fracture, fracture probabilities were calculated using FRAX models from Japan, Turkey and China. Data on bone mineral density (BMD) at the femoral neck were available for 103 patients. Significant differences existed among the models, independent of the inclusion of BMD in the calculation of fracture probabilities. The probabilities of both major osteoporotic fractures and hip fractures were significantly higher in the Japanese model than in the Turkish or Chinese models. In all of the models, the probabilities of a major osteoporotic fracture, but not of a hip fracture, decreased significantly if calculated without BMD values. By applying the Japanese model, the ten-year probabilities for major osteoporotic and hip fractures increased significantly with age. Our results suggest that the Japanese FRAX model might be the most appropriate for Korean women

Efficacy of Postoperative Radiograph for Evaluating the Prevertebral Soft Tissue Swelling after Anterior Cervical Discectomy and Fusion

Background: After surgery for degenerative spinal disease by the anterior approach, the degree of soft tissue swelling can be assessed simply using plain radiographs. However, there are little studies according to the surgical methods or extent of surgery, and no study had addressed the clinical meaning of swelling determined by plain radiography. The purpose of this study was to evaluate the clinical significance of prevertebral soft tissue swelling (PSTS) after anterior cervical fusion with plate fixation for the treatment of degenerative cervical spinal disorders. Methods: One hundred and thirty-five patients that underwent anterior cervical fusion with plate augmentation for degenerative cervical spondylosis were included in this study. PSTS differences were analyzed with respect to numbers of fusion segments and location of fusion. Cases were divided into two groups based on the amount of PSTS, and incidences of dyspnea, dysphagia, dysphonia were evaluated. Results: PSTS increments were significantly greater in patients that had undergone multi-level or high-level fusion. Complications of dyspnea, dysphagia and dysphonia were found more frequently in patients with marked PSTS group. Conclusions: Increments of PSTS after anterior cervical fusion for degenerative spinal disorders are greater and incidences of complications are higher in patients that undergo multi-level or high-level fusion. Thus, measurement of PSTS using consecutive cervical lateral radiographs after anterior cervical surgery is clinically meaningful procedure

Astaxanthin Improves Stem Cell Potency via an Increase in the Proliferation of Neural Progenitor Cells

The present study was designed to investigate the question of whether or not astaxanthin improves stem cell potency via an increase in proliferation of neural progenitor cells (NPCs). Treatment with astaxanthin significantly increased proliferation and colony formation of NPCs. For identification of possible activated signaling molecules involved in active cell proliferation occurring after astaxanthin treatment, total protein levels of several proliferation-related proteins, and expression levels of proliferation-related transcription factors, were assessed in NPCs. In Western blot analysis, astaxanthin induced significant activation of phosphatidylinositol 3-kinase (PI3K) and its downstream mediators in a time-dependent manner. Results of RT-PCR analysis showed upregulation of proliferation-related transcription factors and stemness genes. To estimate the relevance of PI3K and mitogen-activated protein, or extracellular signal-regulated kinase kinase (MEK) signaling pathways in cell growth of astaxanthin-treated NPCs, inhibition assays were performed with LY294002, a specific inhibitor of PI3K, and PD98059, a specific inhibitor of MEK, respectively. These results clearly showed that astaxanthin induces proliferation of NPCs via activation of the PI3K and MEK signaling pathways and improves stem cell potency via stemness acting signals

Interferometric Fiber Optic Sensors

Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair