143 research outputs found

    Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

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    We present the particle-in-cell (PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely (perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 MeV under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments

    Use of 3D-computed tomography angiography for planning the surgical removal of pineal region meningiomas using Poppen's approach: a report of ten cases and a literature review

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    <p>Abstract</p> <p>Background</p> <p>There are several treatment approaches for pineal region meningiomas, such as Poppen's approach, Krause's approach and combinations of the two approaches. We present our experience with the use of 3D-computed tomography angiography for planning the surgical removal of pineal region meningiomas using a suboccipital transtentorial approach (Poppen's approach) and evaluate the role of Poppen's approach.</p> <p>Methods</p> <p>During the period from January 2005 to June 2010, ten patients presented to us with pineal region meningioma. MRI was routinely used to define the tumor size, position, and its relevant complications while 3D-CTA was applied to define the blood supply of the tumor and the venous complex (VC) shift before operations. Most of the meningiomas had developed at both sides of the tentorial plane and extended laterally with typical characteristics of a pineal region tumor.</p> <p>Results</p> <p>All tumors were completely removed surgically without any injury to the VC. Postoperative intracranial infection occurred in one case who recovered after antibiotics were given. Postoperative intraventricular hemorrhage and pneumocephalus were found in one case, but fully recovered after conservative treatment. In the nine cases of concurrent hydrocephalus, this was gradually relieved in eight patients and the single case that became aggravated was successfully treated with ventriculoperitoneal shunt. Moreover, the follow-up MRI examinations did not indicate any recurrence of the meningiomas.</p> <p>Conclusion</p> <p>We found that the use of Poppen's approach is strongly supported for the successful removal of pineal region meningiomas without serious complications.</p

    Detecting the causal effect of soil moisture on precipitation using convergent cross mapping

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    As a vital land surface parameter, soil moisture influences climate through its impact on water and energy cycles. However, the effect of soil moisture on precipitation has been strongly debated. In this study, a new causal detection method, convergent cross mapping (CCM), was applied to explore the causality between soil moisture and precipitation over low- and mid-latitude regions in the Northern Hemisphere. CCM method generally identified a strong effect of soil moisture on precipitation. Specifically, the optimal effect of soil moisture on precipitation occurred with a lag of one month and clearly decreased after four months, suggesting that soil moisture has potentials to improve the accuracy of precipitation forecast at a sub-seasonal scale. In addition, as climate (i.e., aridity index) changed from dry to wet, the effect of soil moisture on precipitation first increased and then decreased with peaks in semi-arid and semi-humid areas. These findings statistically support the hypothesis that soil moisture impacts precipitation and also provide a reference for the design of climate prediction systems

    Monitoring and predicting drought based on multiple indicators in an arid area, China

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    Droughts are one of the costliest natural disasters. Reliable drought monitoring and prediction are valuable for drought relief management. This study monitors and predicts droughts in Xinjiang, an arid area in China, based on the three drought indicators, i.e., the Standardized Precipitation Index (SPI), the Standardized Soil Moisture Index (SSMI) and the Multivariate Standardized Drought Index (MSDI). Results indicate that although these three indicators could capture severe historical drought events in the study area, the spatial coverage, persistence and severity of the droughts would vary regarding different indicators. The MSDI could best describe the overall drought conditions by incorporating the characteristics of the SPI and SSMI. For the drought prediction, the predictive skill of all indicators gradually decayed with the increasing lead time. Specifically, the SPI only showed the predictive skill at a 1-month lead time, the MSDI performed best in capturing droughts at 1- to 2-month lead times and the SSMI was accurate up to a 3-month lead time owing to its high persistence. These findings might provide scientific support for the local drought management

    Ube2L6 promotes M1 macrophage polarization in HFD-fed obese mice via ISGylation of STAT1 to trigger STAT1 activation

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    Introduction: In obesity-related type 2 diabetes mellitus (T2DM), M1 macrophages aggravate chronic inflammation and insulin resistance. ISG15-conjugation enzyme E2L6 (Ube2L6) has been demonstrated as a promoter of obesity and insulin resistance. This study investigated the function and mechanism of Ube2L6 in M1 macrophage polarization in obesity. Methods: Obesity was induced in Ube2L6AKO mice and age-matched Ube2L6flox/flox control mice by high-fat diet (HFD). Stromal vascular cells (SVCs) were isolated from epididymal white adipose tissue of mice. Polarization induction was performed in mouse bone marrow-derived macrophages (BMDMs) by exposure to IFN-γ, lipopolysaccharide (LPS), or IL-4. F4/80 expression was assessed by immunohistochemistry staining. Expression of M1/M2 macrophage markers and target molecules was determined by flow cytometry, RT-qPCR, and Western blotting, respectively. Protein interaction was validated by co-immunoprecipitation (Co-IP) assay. The release of TNF-α and IL-10 was detected by ELISA. Results: The polarization of pro-inflammatory M1 macrophages together with an increase in macrophage infiltration were observed in HFD-fed mice, which could be restrained by Ube2L6 knockdown. Additionally, Ube2L6 deficiency triggered the repolarization of BMDMs from M1 to M2 phenotypes. Mechanistically, Ube2L6 promoted the expression and activation of signal transducer and activator of transcription 1 (STAT1) through interferon-stimulated gene 15 (ISG15)-mediated ISGlylation, resulting in M1 macrophage polarization. Conclusion: Ube2L6 exerts as an activator of STAT1 via post-translational modification of STAT1 by ISG15, thereby triggering M1 macrophage polarization in HFD-fed obese mice. Overall, targeting Ube2L6 may represent an effective therapeutic strategy for ameliorating obesity-related T2DM

    Republican personality cults in wartime China: contradistinction and collaboration

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    This paper explores the development of the Wang Jingwei personality cult during the Japanese occupation of China (1937–1945). It examines how the collaborationist Chinese state led by Wang sought to distinguish its figurehead from the person he had replaced, Nationalist leader Chiang Kai-shek. Drawing on visual, archival, and published sources, it traces the development of the Wang cult from the early years of the war, and argues that the unusual context in which the cult evolved ultimately undermined its coherence. The case of Wang Jingwei illustrates how the Chinese case more broadly can enhance our understandings of personality cults that develop under occupation. To this end, I compare the Wang regime with various European “collaborationist” governments that sought to promote their leaders in similar ways

    Raman spectroscopy: A prospective intraoperative visualization technique for gliomas

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    The infiltrative growth and malignant biological behavior of glioma make it one of the most challenging malignant tumors in the brain, and how to maximize the extent of resection (EOR) while minimizing the impact on normal brain tissue is the pursuit of neurosurgeons. The current intraoperative visualization assistance techniques applied in clinical practice suffer from low specificity, slow detection speed and low accuracy, while Raman spectroscopy (RS) is a novel spectroscopy technique gradually developed and applied to clinical practice in recent years, which has the advantages of being non-destructive, rapid and accurate at the same time, allowing excellent intraoperative identification of gliomas. In the present work, the latest research on Raman spectroscopy in glioma is summarized to explore the prospect of Raman spectroscopy in glioma surgery
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