1,816 research outputs found

    Differences of Upper Airway Morphology According to Obesity: Study with Cephalometry and Dynamic MD-CT

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    ObjectivesWe investigated difference of parameters of polysomnography, cephalometry and dynamic multi-detector computerized tomography (MD-CT) in wake and sleep states according to obesity.MethodsWe evaluated 93 patients who underwent polysomnography and cephalometry. MD-CT was performed in 68 of these 93 patients. Fifty-nine and 34 patients were classified as obese and non-obese, with obesity defined as BMI ≥25. Cephalometry results were analyzed for 12 variables. Using the MD-CT, we evaluated dynamic upper airway morphology in wake and sleep states and divided the upper airway into four parts named as high retropalatal (HRP), low retropalatal (LRP), high retroglossal (HRG), and low retroglossal (LRG). A minimal cross sectional area (mCSA) and collapsibility index (CI) were calculated for each airway level.ResultsDiastolic blood pressure (P=0.0005), neck circumference (P<0.0001), and apnea-hypopnea index (P<0.0001) were statistically significantly different between the obese and non-obese group. Among 12 cephalometric variables, there was a significant difference in only the distance from mandibular plane to hyoid bone (P=0.003). There was statistical difference in CI of HRG and LRG in sleep state (P=0.0449, 0.0281) but no difference in mCSA in wake and sleep states.ConclusionThe obese group had more severe sleep apnea than the non-obese group. We believe that the increased severity of apnea in the obese group may be have been due to increased collapsibility of the upper airway rather than decreased size of the upper airway

    Comb-rooted multi-channel synthesis of ultra-narrow optical frequencies of few Hz linewidth

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    We report a multi-channel optical frequency synthesizer developed to generate extremely stable continuous wave lasers directly out of the optical comb of an Er-doped fiber oscillator. Being stabilized to a high-finesse cavity with a fractional frequency stability of 3.8×10153.8\times10^{-15} at 0.1 s, the comb-rooted synthesizer produces multiple optical frequencies of ultra-narrow linewidth of 1.0 Hz at 1 s concurrently with an output power of tens of mW per each channel. Diode-based stimulated emission by injection locking is a key mechanism that allows comb frequency modes to sprout up with sufficient power amplification but no loss of original comb frequency stability. Channel frequencies are individually selectable with a 0.1 GHz increment over the entire comb bandwidth spanning 4.25 THz around a 1550 nm center wavelength. A series of out-of-loop test results is discussed to demonstrate that the synthesizer is able to provide stable optical frequencies with the potential for advancing diverse ultra-precision applications such as optical clocks comparison, atomic line spectroscopy, photonic microwaves generation, and coherent optical telecommunications.Comment: 19 pages, 4 figure

    Gating of memory encoding of time-delayed cross-frequency MEG networks revealed by graph filtration based on persistent homology

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    To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR. In good memory performers (R-hits minus false alarm), the coupling was stronger in R than NR between the right posterior cingulate (cue-alpha) and the left fusiform gyri (item-gamma). Gating of memory encoding was dictated by inter-regional negative alpha-gamma coupling. Our graph filtration over MEG network revealed these inter-regional time-delayed cross-frequency connectivity serve gating of memory encoding

    Hybrid XML Data Model Architecture for Efficient Document Management

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    XML has been known as a document standard in representation and exchange of data on the Internet, and is also used as a standard language for the search and reuse of scattered documents on the Internet. The issues related to XML are how to model data on effective and efficient management of semi-structured data and how to actually store the modeled data when implementing a XML contents management system. Previous researches on XML have limitations in (1) reproduction of XML documents from the stored data, (2) retrieval of XML sub-graph from search, (3) supporting only top-down search, not full-search, and (4) dependency of data structure on XML documents. The purpose of this paper is to present a hybrid XML data model architecture for the storage and search of XML document data. By representing both data and structure views of XML documents, this new XML data model technique overcomes the limitations of previous researches on data model for XML documents as well as the existing database systems such as relational and object-oriented data model

    Carnosol induces apoptotic cell death through ROS-dependent inactivation of STAT3 in human melanoma G361 cells

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    Melanoma is the leading cause of skin cancer deaths, and the poor prognosis of metastatic melanoma has made needs for a novel pharmacological treatment or efficient intervention. Carnosol, a major polyphenolic compound from Rosmarinus officinalis, has a wide range of biological activities including anti-cancer effect. However, the underlying molecular mechanisms of its anti-cancer effect remain poorly understood in malignant human melanoma cells. In the present study, we investigate the apoptotic effect and the underlying anti-cancer mechanisms of carnosol. Our results revealed that carnosol strongly induced apoptosis against human melanoma G361 cells in a dose- and time-dependent manner, and caused dramatical elevation in cellular reactive oxygen species (ROS) level during apoptosis. In mechanistic studies, carnosol treatment decreased protein level of anti-apoptotic B‑cell lymphoma 2 (Bcl-2) and B cell lymphoma-extra large (Bcl-xL), however, increased level of pro-apoptotic Bcl-2-associated X protein (Bax) protein. Moreover, carnosol escalated cellular level of p53, which was accompanied by a decline of mouse double minute 2 homolog (MDM2) level. Also, carnosol inhibited activation of Src and signal transducer and activator of transcription 3 (STAT3), therefore down-regulated STAT3-dependent gene expression, such as D-series cyclin and survivin. These changes by carnosol were attenuated by pre-treatment of N-acetyl cysteine, and abolished progression of carnosol-induced apoptosis. In conclusion, carnosol induced apoptosis in human melanoma G361 cells through ROS generation and inhibition of STAT3-mediated pathway. Our results provide molecular bases of carnosol-induced apoptosis, and suggest a novel candidate for human melanoma treatment.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A02050495, J.-S. Choi) and by the Ministry of Science, ICT and Future Planning 2017R1A2B4009831, K.- S. Chun)

    Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

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    Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity
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