121 research outputs found

    Development of a coronal mass ejection arrival time forecasting system using interplanetary scintillation observations

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    Coronal mass ejections (CMEs) cause disturbances in the environment of the Earth when they arrive at the Earth. However, the prediction of the arrival of CMEs still remains a challenge. We have developed an interplanetary scintillation (IPS) estimation system based on a global magnetohydrodynamic (MHD) simulation of the inner heliosphere to predict the arrival time of CMEs. In this system, the initial speed of a CME is roughly derived from white light coronagraph observations. Then, the propagation of the CME is calculated by a global MHD simulation. The IPS response is estimated by the three-dimensional density distribution of the inner heliosphere derived from the MHD simulation. The simulated IPS response is compared with the actual IPS observations made by the Institute for Space-Earth Environmental Research, Nagoya University, and shows good agreement with that observed. We demonstrated how the simulation system works using a halo CME event generated by a X9.3 flare observed on September 5, 2017. We find that the CME simulation that best estimates the IPS observation can more accurately predict the time of arrival of the CME at the Earth. These results suggest that the accuracy of the CME arrival time can be improved if our current MHD simulations include IPS data.Comment: 39 pages, 6 figures, accepted for publication in Earth, Planets and Spac

    OCTAD-S: Digital Fast Fourier Transform Spectrometers by FPGA

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    We have developed a digital fast Fourier transform (FFT) spectrometer made of an analog-to-digital converter (ADC) and a field-programmable gate array (FPGA). The base instrument has independent ADC and FPGA modules, which allow us to implement different spectrometers in a relatively easy manner. Two types of spectrometers have been instrumented, one with 4.096 GS/s sampling speed and 2048 frequency channels and the other with 2.048 GS/s sampling speed and 32768 frequency channels. The signal processing in these spectrometers has no dead time and the accumulated spectra are recorded in external media every 8 ms. A direct sampling spectroscopy up to 8 GHz is achieved by a microwave track-and-hold circuit, which can reduce the analog receiver in front of the spectrometer. Highly stable spectroscopy with a wide dynamic range was demonstrated in a series of laboratory experiments and test observations of solar radio bursts.Comment: 20 pages, 7 figures, accepted for publication in Earth, Planets and Spac

    Synthesis and characterization of oligonucleotides containing 2′-fluorinated thymidine glycol as inhibitors of the endonuclease III reaction

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    Endonuclease III (Endo III) is a base excision repair enzyme that recognizes oxidized pyrimidine bases including thymine glycol. This enzyme is a glycosylase/lyase and forms a Schiff base-type intermediate with the substrate after the damaged base is removed. To investigate the mechanism of its substrate recognition by X-ray crystallography, we have synthesized oligonucleotides containing 2′-fluorothymidine glycol, expecting that the electron-withdrawing fluorine atom at the 2′ position would stabilize the covalent intermediate, as observed for T4 endonuclease V (Endo V) in our previous study. Oxidation of 5′- and 3′-protected 2′-fluorothymidine with OsO(4) produced two isomers of thymine glycol. Their configurations were determined by NMR spectroscopy after protection of the hydroxyl functions. The ratio of (5R,6S) and (5S,6R) isomers was 3:1, whereas this ratio was 6:1 in the case of the unmodified sugar. Both of the thymidine glycol isomers were converted to the corresponding phosphoramidite building blocks and were incorporated into oligonucleotides. When the duplexes containing 2′-fluorinated 5R- or 5S-thymidine glycol were treated with Escherichia coli endo III, no stabilized covalent intermediate was observed regardless of the stereochemistry at C5. The 5S isomer was found to form an enzyme–DNA complex, but the incision was inhibited probably by the fluorine-induced stabilization of the glycosidic bond

    Chemical synthesis of oligodeoxyribonucleotides containing the Dewar valence isomer of the (6–4) photoproduct and their use in (6–4) photolyase studies

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    The pyrimidine(6–4)pyrimidone photoproduct, a major UV lesion formed between adjacent pyrimidine bases, is transformed to its Dewar valence isomer upon exposure to UVA/UVB light. We have synthesized a phosphoramidite building block of the Dewar photoproduct formed at the thymidylyl(3′–5′)thymidine site and incorporated it into oligodeoxyribonucleotides. The diastereoisomers of the partially protected dinucleoside monophosphate bearing the (6–4) photoproduct, which were caused by the chirality of the phosphorus atom, were separated by reversed-phase chromatography, and the (6–4) photoproduct was converted to the Dewar photoproduct by irradiation of each isomer with Pyrex-filtered light from a high-pressure mercury lamp. The Dewar photoproduct was stable under both acidic and alkaline conditions at room temperature. After characterization of the isomerized base moiety by NMR spectroscopy, a phosphoramidite building block was synthesized in three steps. Although the ordinary method could be used for the oligonucleotide synthesis, benzimidazolium triflate as an alternative activator yielded better results. The oligonucleotides were used for the analysis of the reaction and the binding of Xenopus (6–4) photolyase. Although the affinity of this enzyme for the Dewar photoproduct-containing duplex was reportedly similar to that for the (6–4) photoproduct-containing substrate, the results suggested a difference in the binding mode

    Characterization of a Y-Family DNA Polymerase eta from the Eukaryotic Thermophile Alvinella pompejana

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    Human DNA polymerase η (HsPolη) plays an important role in translesion synthesis (TLS), which allows for replication past DNA damage such as UV-induced cis-syn cyclobutane pyrimidine dimers (CPDs). Here, we characterized ApPolη from the thermophilic worm Alvinella pompejana, which inhabits deep-sea hydrothermal vent chimneys. ApPolη shares sequence homology with HsPolη and contains domains for binding ubiquitin and proliferating cell nuclear antigen. Sun-induced UV does not penetrate Alvinella's environment; however, this novel DNA polymerase catalyzed efficient and accurate TLS past CPD, as well as 7,8-dihydro-8-oxoguanine and isomers of thymine glycol induced by reactive oxygen species. In addition, we found that ApPolη is more thermostable than HsPolη, as expected from its habitat temperature. Moreover, the activity of this enzyme was retained in the presence of a higher concentration of organic solvents. Therefore, ApPolη provides a robust, human-like Polη that is more active after exposure to high temperatures and organic solvents

    Postoperative Urinary Retention in Japanese Elderly Males with a Femoral Neck or Trochanteric Fracture

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    We assessed risk factors for postoperative urinary retention (UR) in elderly males with femoral bone fractures: 169 Japanese males (mean age 81.95 ± 1.19 years) who had undergone hip surgery at a municipal hospital (Toyama, Japan). A multiple logistic regression analysis was used to test possible risk factors for UR: age, body mass index, serum albumin, cognitive impairment, activities of daily living (ADL), and history of diabetes mellitus (DM). UR occurred in 24 (14.2%) of the 169 patients. A multivariate logistic regression analysis with age adjustment showed that ADL (odds ratio [OR] 3.88; 95% confidence interval [CI]: 1.2-12.5, p=0.023) was significantly associated with the development of UR, and a history of DM showed marginal significance for UR occurrence (OR 0.36, 95%CI: 0.11-10, p=0.064). These results suggests that ADL is a risk factor for UR development in elderly males who have undergone surgery for femoral neck or trochanter fractures

    コウジョウセン ニュウトウガン ト ハシモトビョウ ノ カンベツ ニ ツイテ

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    Introduction: Thyroid fine-needle cytology is the first line clinical method for thyroid nodule to select patients for surgery, because papillary carcinoma has diagnostic characteristics in cytology, such as nuclear enlargement, nuclear grooves and nuclear inclusions. However over-diagnosis of Hashimoto disease is well known fact to occur frequently.Materials and Methods: Morphometric analysis of cytological samples from Hashimoto disease, papillary carcinoma and benign adenomatous nodule were carried out 4 cases each using Papanicolaou stained conventional smear samples.Results: Sizes of clusters were evaluated by counting number of follicular cells in the cluster. It was larger in papillary carcinoma (63.3/cluster) and benign (43.9/cluster) than Hashimoto disease (18.9/cluster) (P=0.006). The nuclear diameter increased in Hashimoto disease and the average of the longest diameter was 6.5μm and the shortest was 5.5μm, which was overlapped with those of papillary carcinoma. The number of nuclear grooves increased from benign (<1%), Hashimoto disease (6%) to papillary carcinoma (16%).Conclusion: There are significant overlap between Hashimoto disease and papillary carcinoma morphologically. For more accurate diagnosis of Hashimoto disease may be achieved only with combined morphological features

    胃十二指腸運動機能の推移が評価できたCeliac Artery Compression Syndromeの1例

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    症例は40歳代の女性.X-1年1月頃より食後の心窩部や左季肋部の痛み,張り感などが出現し,上部消化管内視鏡検査で症状の原因となる器質的疾患は指摘されないため,X年10月当科に紹介された.体外式超音波検査(US)で腹腔動脈(CA)の呼吸性変位が指摘され,CAの血流測定を行ったところCeliac Artery Compression Syndrome (CACS)と診断された.本人が手術を希望せず,約2年半経過した現在も上腹部症状に対して内服薬のみ投与している.症状に胃十二指腸運動機能異常の関与も疑われたため,US を用いた胃十二指腸運動機能検査は4回施行され,その結果は内服薬の選択に利用された.運動機能検査の結果は4回目が最も改善しており,同時に施行した症状問診票の腹痛症状は4回目が最も軽かった.比較的長期にわたり症状と消化管運動機能の推移を観察したCACS症例の報告は過去になく,本稿が最初の報告である.We reported a case of a woman in her 40\u27s with celiac artery compression syndrome (CACS). She presented a dull pain and fullness in the upper part of her abdomen during and soon after eating. Blood and urine examinations revealed no obvious abnormalities, and upper gastrointestinal endoscopy indicated no obvious causes for the symptom. After a routine abdominal ultrasound (US), measurement of celiac artery blood flow showed high bloodflow velocity, which met the US diagnostic criteria for CACS. The evidence of CACS was supported by contrast-enhanced computed tomography, showing an obvious narrowing of the celiac artery in the expiration phase. Since she did not accept surgical therapy, treatment using oral medicine continued for about 2 years and six months. Meanwhile, the US examination for evaluating gastro-duodenal motility was performed 4 times. This is the first report that showing long-term progress of the symptoms and gastro-duodenal motility in this CACS patient
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