98 research outputs found

    Tunable tunnel coupling in a double quantum antidot with cotunneling via localized state

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    Controlling tunnel coupling between quantum antidots (QADs) in the quantum Hall (QH) regime is problematic. We propose and demonstrate a scheme for tunable tunnel coupling between two QADs by utilizing a cotunneling process via a localized state as a third QAD. The effective tunnel coupling can be tuned by changing the localized level even with constant nearest-neighbor tunnel couplings. We systematically study the variation of transport characteristics in the effectively triple QAD system at the Landau level filling factor Ξ½=2\nu =2. The tunable tunnel coupling is clarified by analyzing the anti-crossing of Coulomb blockade peaks in the charge stability diagram, in agreement with numerical simulations based on the master equation. The scheme is attractive for studying coherence and interaction in QH systems.Comment: 11 pages, 8 figure

    Influence of River Inflow and Microbial Activity on Distribution of Dissolved Organic Carbon in the Northern Part of Ariake Sea, Kyushu, Japan

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    To identify the factors controlling the distribution of dissolved organic carbon (DOC) in the northern Ariake Sea (Japan), we measured DOC, salinity and chlorophyll a (Chl. a) along transect lines from the largest river discharging into the Ariake Sea (the Chikugo River) to the opposite shore. The DOC concentration was significantly correlated with salinity, although no correlation was found between the Chl. a concentration and DOC. Thus, river inflow is the primary source of DOC. However, the expected concentration of riverine DOC, represented by the y-intercept of the regression curve between salinity and DOC, was much higher than the DOC concentration of the Chikugo River, suggesting the presence of additional DOC sources to the Ariake Sea. We conducted particulate organic matter (POM) decomposition experiments and observed DOC production after incubation. Thus, microbial POM decomposition may be a source of excess DOC. This study is the first to show that river inflow and microbial decomposition of POM affect the DOC distribution in the northern Ariake Sea

    Automated Data Augmentations for Graph Classification

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    Data augmentations are effective in improving the invariance of learning machines. We argue that the corechallenge of data augmentations lies in designing data transformations that preserve labels. This is relativelystraightforward for images, but much more challenging for graphs. In this work, we propose GraphAug, a novelautomated data augmentation method aiming at computing label-invariant augmentations for graph classification.Instead of using uniform transformations as in existing studies, GraphAug uses an automated augmentationmodel to avoid compromising critical label-related information of the graph, thereby producing label-invariantaugmentations at most times. To ensure label-invariance, we develop a training method based on reinforcementlearning to maximize an estimated label-invariance probability. Comprehensive experiments show that GraphAugoutperforms previous graph augmentation methods on various graph classification tasks

    Apparent stratospheric ozone loss rate over Eureka in 1994/95, 1995/96, and 1996/97 inferred from ECC ozonesonde observations

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    Many ECC-type ozonesondes were launched at the Canadian Arctic Eureka observatory(80Β°N , 86Β°W ), one of the most northern stations in the Arctic, during winters from 1993/94 to 2001/02, and the temporal evolutions of the vertical ozone profiles were obtained in detail. The lower stratospheric temperature over Eureka was very low inside the polar vortex and the largest ozone loss was observed in 1999/2000, as reported in a previous paper. Similarly, Eureka was often or persistently inside the vortex in the lower stratosphere(around the 470K isentropic surface level) in the winters of 1994/95, 1995/96, and 1996/97. Very low temperatures were observed inside the vortex in the lower stratosphere over Eureka, as indicated by detection of PSCs by Mie lidar. Observations of tracers(N_2O, total reactive nitrogen species(NOy), and others) inside the vortex during these winters using an ER-2 aircraft and balloons indicated that the effect of air parcel mixing across the vortex edge was minimal, based on the tracer-tracer relationship(e.g., Y. Kondo et al.; J. Geophys. Res., 104D, 8215, 1999). Therefore, significant decreases of the in-travortex ozone mixing ratio in the lower stratosphere were considered to be chemical ozone losses due to chlorine activation of PSCs following diabatic descent. The apparent ozone loss rate inside the vortex over Eureka was estimated for each year. The rates ranged from 0.01 to 0.03ppmv/day, less than that observed in 1999/2000(0.04ppmv/day). The observations were conducted at a single station; however, the apparent ozone loss rate over Eureka inside the vortex each year agrees with loss rates obtained in other studies

    Spatio-temporal distribution of environmental DNA derived from Japanese sea nettle jellyfish Chrysaora pacifica in Omura Bay, Kyushu, Japan

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    We surveyed the spatial and temporal distribution of Japanese sea nettle jellyfish Chrysaora pacifica in Omura Bay, Japan, using an environmental DNA (eDNA) method. In 2018, the C. pacifica eDNA concentration increased from March?May at all depths. The seasonal pattern of C. pacifica eDNA was consistent with previous reports based on visual observations along the Japanese coast. Thus, the eDNA method might have advantages to follow the seasonal pattern of C. pacifica while being less time-consuming and less laborious compared with traditional methods. The eDNA concentrations tended to reach a maximum near and/or below the pycnocline throughout this study. Therefore, the vertical distribution of C. pacifica medusae may have been restricted by strong pycnocline formation in July and August 2018. However, even with a weak pycnocline, which C. pacifica should be able to swim across, the apparent distribution of C. pacifica eDNA seems to be restricted by the pycnocline. Therefore, the eDNA method cannot, currently, accurately assess the absolute vertical distribution pattern of C. pacifica, especially when a pycnocline is formed

    Sarcopenia, intramuscular fat deposition, and visceral adiposity independently predict the outcomes of hepatocellular carcinoma

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    Background & AimsObesity defined by body mass index (BMI) significantly increases the risk of hepatocellular carcinoma (HCC). In contrast, not only obesity but also underweight is associated with poor prognosis in patients with HCC. Differences in body composition rather than BMI were suggested to be true determinants of prognosis. However, this hypothesis has not been demonstrated conclusively.MethodsWe measured skeletal muscle index (SMI), mean muscle attenuation (MA), visceral adipose tissue index, subcutaneous adipose tissue index, and visceral to subcutaneous adipose tissue area ratios (VSR) via computed tomography in a large-scale retrospective cohort of 1257 patients with different stages of HCC, and comprehensively analyzed the impact of body composition on the prognoses.ResultsAmong five body composition components, low SMI (called sarcopenia), low MA (called intramuscular fat [IMF] deposition), and high VSR (called visceral adiposity) were significantly associated with mortality, independently of cancer stage or Child-Pugh class. A multivariate analysis revealed that sarcopenia (hazard ratio [HR], 1.52; 95% confidence interval [CI], 1.18–1.96; p=0.001), IMF deposition (HR, 1.34; 95% CI, 1.05–1.71; p=0.020), and visceral adiposity (HR, 1.35; 95% CI, 1.09–1.66; p=0.005) but not BMI were significant predictors of survival. The prevalence of poor prognostic body composition components was significantly higher in underweight and obese patients than in normal weight patients.ConclusionsSarcopenia, IMF deposition, and visceral adiposity independently predict mortality in patients with HCC. Body composition rather than BMI is a major determinant of prognosis in patients with HCC

    Analysis of DOC and Ram for NSCLC

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    Background: Current clinical trials demonstrated that combination regimens comprising chemotherapy and immunotherapy lead to better patient outcomes compared to chemotherapy alone as the first line of treatment for non-small cell lung cancer (NSCLC). In addition, the combination therapy of docetaxel (Doc) and ramucirumab (Ram) was considered one of the standard treatments for advanced or relapsed NSCLC patients. However, little is known about the therapeutic responders of this combination therapy among previously treated NSCLC patients. In the present study, we aimed to identify predictive factors for therapeutic response, including programmed death-ligand 1 (PD-L1) expression in tumors, for Doc treatment in combination with Ram. Methods: We retrospectively analyzed a total of 135 advanced or relapsed NSCLC patients who were refractory to platinum-based chemotherapy at eleven institutions in Japan between July 2016 and November 2018. Results: Our observations showed that PD-L1 expression in tumors is not associated with the efficacy of combined therapy of Doc and Ram in previously treated NSCLC patients. Analysis of the patient clinical profiles indicated that prior treatment with immune checkpoint inhibitors (ICIs) is a reliable predictor for the good progression-free survival (PFS) to this combination therapy (P=0.041). Conclusions: Our retrospective study indicated that combination regimens comprising chemotherapy and ICIs followed by Doc and Ram could be an optimal therapeutic option for NSCLC patients regardless of the PD-L1 status of tumors. Further investigations are required to strengthen clinical evidence demonstrating the effectiveness of the combination therapy of Doc plus Ram in previously treated NSCLC patients

    Peritoneal cecal cancer metastasis to a mesh-plug prosthesis : A case report

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    We report the case of a 77-year-old man who presented to our hospital with cecal cancer, lung metastasis, and liver metastasis in January 2013. After four courses of modified infusional intravenous fluorouracil and levofolinate with oxaliplatin (mFOLFOX 6) + bevacizumab, there was no new metastatic lesion and lung metastasis reduction was observed. Ileocecal resection was performed in May, left lower lung lobectomy in August, and extended right posterior segmentectomy + S8 partial liver resection was performed in December. The tumor marker declined initially ; thereafter, it gradually increased. Computed tomography (CT) performed in April 2014 revealed right inguinal mass around the mesh-plug prosthesis. A positron emission tomography-CT (PET-CT) also revealed a high 2-fluoro-2-deoxy-D-glucose (FDG) uptake at the same site. Right inguinal tumor resection was performed in July. Cancer tissues were confirmed by performing intraoperative rapid pathological diagnosis, and R0 resection could be achieved. Previous studies have reported malignant tumor metastases to the mesh-plug prosthesis, and this was believed to one of the sites that cancer cells can easily engraft. In particular, in patients with a history of advanced malignant tumors, if mass formation around the artifact insertion site is observed, the possibility of peritoneal metastasis should be considered

    Combined resection of re-recurrent lateral lymph nodes and external iliac vein : Case Report and Literature

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    Herein, we describe the operative procedure for combined resection of re-recurrent lateral lymph nodes and the external iliac vein. There is no consensus on the clinical implications of resection of locally re-recurrent colorectal tumors, as the operative procedure is extremely difficult. We present the case of a 52- year-old woman who underwent abdominoperineal resection. About one year later, we excised a recurrent lymph node in the left lateral obturator area through an extraperitoneal approach. About 18 months later, lymph node re-recurrence in the left external iliac area was observed. Re-recurrent lymph nodes directly invade the left external iliac vein.We removed the re-recurrent lymph node with combined, radical segmental resection of the left external iliac vein, left obturator artery and vein, and left obturator nerve
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