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Background removal from global auroral images:Data-driven dayglow modeling

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Earth and Planetary Physics 2024年第1期8卷 247-257页

作者： A.Ohma M.Madelaire K.M.Laundal j.P.Reistad S.M.Hatch S.Gasparini S.j.walker Birkeland Centre for Space Science Department of Physics and TechnologyUniversity of BergenBergenNorway

Global images of auroras obtained by cameras on spacecraft are a key tool for studying the near-Earth ***,the cameras are sensitive not only to auroral emissions produced by precipitating particles,but also to dayglow emissions produced by photoelectrons induced by *** emissions and scattered sunlight can contribute to the background *** fully utilize such images in space science,background contamination must be removed to isolate the auroral *** we outline a data-driven approach to modeling the background intensity in multiple images by formulating linear inverse problems based on B-splines and spherical *** approach is robust,flexible,and iteratively deselects outliers,such as auroral *** final model is smooth across the terminator and accounts for slow temporal variations and large-scale asymmetries in the *** demonstrate the model by using the three far ultraviolet cameras on the Imager for Magnetopause-to-Aurora Global Exploration(IMAGE)*** method can be applied to historical missions and is relevant for upcoming missions,such as the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission.

关键词： aurora dayglow modeling global auroral images far ultraviolet images dayglow removal

Intracranial pressure is elevated at 24h post-stroke inmice

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Neuroprotection 2024年第1期2卷 60-64页

作者： Kirby E.Warren Rebecca j.Hood Fredrick R.walker Neil j.Spratt School of Biomedical Sciences and Pharmacy University of NewcastleCallaghanAustralia Hunter Medical Research Institute NewLambton HeightsAustralia School of Biomedicine Discipline of Anatomy and PathologyFaculty of Health and Medical SciencesThe University of AdelaideAdelaideAustralia Department of Neurology John Hunter HospitalNewLambton HeightsAustralia

Background:It has long been assumed that post-stroke intracranial pressure(ICP)elevation occurs because of large infarct and edema ***,we have repeatedly shown IcP elevation at 24 h post-stroke in the presence of little to no edema in *** processes are often conserved across species and types of ***,we aimed to determine if an ICP rise occurs at 24 h post-stroke in the presence of small infarct and edema volumes in ***:Mice were randomized by random number table to either photothrombotic stroke or sham surgery(n=15).Epidural ICP was recorded using a fiber optic catheter at 1 h post-stroke(baseline)and between 23 and ***:ICP was significantly higher at 24 h compared to baseline in stroke animals(n=6;10.71±6.45mmHg vs.3.74±2.20mmHg,respec-tively;p=0.03).ICP at 24 h was also significantly higher in stroke mice compared to sham(n=6;3.45±1.43mmHg;p=0.02).There was no change in ICP in sham mice(p=0.9).Edema volumes in stroke animals were small(0.04±0.04 mm3)and unlikely to have caused significant ICP ***:This study provides evidence of an edema-independent ICP elevation following small ischemic stroke in *** occurrence of this rise supports our findings in other species and suggests it is caused by a previously undescribed mechanism.

关键词： cerebraledema intracranial pressure ischemic stroke

Wada试验记忆的不对称预测颞叶切除术预后的局限性

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世界核心医学期刊文摘(神经病学分册) 2006年第1期 35-35页

作者： Kirsch H.E. walker j.a. Winstanley F.S. 周永 UCSFEpilepsy Center 400 Parnassus Ave. San Francisco CA 94143-0138 United States Dr.

Background: The intracarotid amobarbital (Wada) test can be used to evaluate hemispheric memory capacity before anterior temporal lobectomy (ATL). Most patients demonstrate better memory with injection ipsilateral to planned resection (expected asymmetry EA ), but a substantial minority show better memory with contralateral injection (unexpected asymmetry UA ). Both degree and direction of Wada memory asymmetry (WMA) have been associated with worse surgical outcome in small series. Reports also suggest that UA is associated with greater decline in verbal memory after left ATL (L-ATL). Methods: The relationship between WMA and surgical outcome (at 3 months, 1 year, and last follow-up) was examined in a large group of ATL patients (108 L, 119 R) with both EA and UA. Also, memory in a subgroup (96 L, 108 R) was examined, comparing subscores of the Rey Auditory Verbal Learning Test obtained preoperatively, at 3 months, and at 1 year. Results: Thirty-six percent of L-ATL and 8%of R-ATL patients had UA. UA was associated with worse surgical outcome at 1 year for R-ATL patients but was not associated with worse outcome for L-ATL patients. There was no correlation between WMA and persistent postoperative verbal memory change for patients with L-or R-ATL. Conclusions: Unexpected asymmetry is uncommon in patients with right anterior temporal lobectomy (R-ATL) and may be a risk marker of poor surgical outcome. This relationship may be obscured by language confounds in patients with L-ATL. The results suggest that Wada asymmetry (using mixed stimuli) does not predict postoperative verbal memory; it is unclear whether this finding is generalizable to centers using only nonverbal stimuli.

关键词：手术预后记忆能力 Wada 不对称

Beyond first-line chemotherapy for advanced pancreatic cancer:An expanding array of therapeutic options?

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World journal of Gastroenterology 2014年第9期20卷 2224-2236页

作者： Evan j walker Andrew H Ko University of California Helen Diller Family Comprehensive Cancer Center San Francisco CA 94115 United States

While an increasing number of therapeutic options are now available for the first-line treatment of locally advanced or metastatic pancreatic cancer,the optimal choice for treatment in the second-line setting and beyond is less well defined.A variety of cytotoxic agents,either alone or in combination,have been evaluated,although primarily in the context of small single-arm or retrospective *** regimens have been associated with median progression-free survival rates in the range of 2-4 mo and overall survival rates between 4-8mo,highlighting the very poor prognosis of patients who are candidates for such *** therapies studied in this chemotherapy-refractory setting,meanwhile,have produced even worse efficacy *** the current article,we review the clinical evidence for treatment of refractory disease,primarily in patients who have progressed on front-line gemcitabine-based *** the process,we highlight the limitations of the available data to date as well as some of the challenges in designing appropriate clinical trials in this salvage setting,including how to select an appropriate control arm given the absence of a wellestablished reference standard,and the importance of incorporating predictive biomarkers and quality of life measures whenever possible into study design.

关键词： Pancreatic cancer Refractory Second-line chemotherapy Gemcitabine

Gastrointestinal disease in children with autism spectrum disorders:Etiology or consequence?

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World journal of Psychiatry 2021年第9期11卷 605-618页

作者： Arthur Krigsman Stephen j walker Pediatric Gastroenterology Resources of New York and Texas GeorgetownTX 78628United States Institute for Regenerative Medicine Wake Forest Baptist Medical CenterWinston SalemNC 27157United States

Chronic gastrointestinal(GI)symptoms and disorders are common in children with autism spectrum disorder and have been shown to be significantly correlated with the degree of behavioral and cognitive *** this unique population,GI symptoms often arise very early in development,during infancy or toddlerhood,and may be misdiagnosed-or not diagnosed at all–due in part to the challenges associated with recognition of symptoms in a minimally or noncommunicative *** demonstrating that the gut-brain-axis can communicate gut dysbiosis and systemic immune dysregulation in a bidirectional manner raises the question as to whether an untreated gastrointestinal disorder can directly impact neurodevelopment or,conversely,whether having a neurodevelopmental disorder predisposes a child to chronic GI *** the data presented in this mini review,we conclude that the preponderance of available evidence would suggest the former scenario is more strongly supported.

关键词： Autism spectrum disorder Gastrointestinal disease Immune dysregulation Neurodevelopment

Eddy Calculation and Vacuum Field Reconstruction on EAST

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Plasma Science and Technology 2011年第2期13卷 145-152页

作者：罗正平肖炳甲 j.a.LEUER M.L.walker 袁旗平 Institute of Plasma Physics Chinese Academy of Sciences General Atomics DⅢ-D National Fusion Facility

A new method, by using eigenmodes to reduce the fitting parameters and precalculated eddy current based on a lump parameter circuit equation, is applied to reconstruct the vacuum field for EAST plasma startup.

关键词： EAST eddy calculation vacuum field reconstruction tokamak

三维炭纤维预型体上烷烃气的催化炭沉积(英文)

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新型炭材料 2009年第3期24卷 251-259页

作者： Matthew j Thornton Gavin S walker School of Mechanical Materials and Manufacturing EngineeringUniversity of NottinghamUniversity ParkNottingham

研究了承载镍催化剂的三维(3D)炭纤维预型体,在含氢或无氢条件下,乙烷和合成天然气在其上面化学气相沉积形成的炭沉积率和碳纳米构结物。观察了炭沉积所获石墨纳米纤维、碳纳米管和石墨碳壳,得知沉积碳的纳米结构取决于沉积温度和碳源... 详细信息

研究了承载镍催化剂的三维(3D)炭纤维预型体,在含氢或无氢条件下,乙烷和合成天然气在其上面化学气相沉积形成的炭沉积率和碳纳米构结物。观察了炭沉积所获石墨纳米纤维、碳纳米管和石墨碳壳,得知沉积碳的纳米结构取决于沉积温度和碳源气组成。在650℃～800℃温间,总沉积时程直至12h,研究了烃类碳源气在氢气平衡下,从体积分数100%到20%变化情况。经Ni(NO3)2-6H2O甲醇溶液浸渍的3D炭纤维预型体在炭沉积前因溶液分解可还原出Ni。采用质量变化测定法、热谱-质谱分析仪、SEM、TEM和XRD对样品进行表征。结果表明:纤维状炭与囊包炭的比率随氢气含量的增加而增加,随反应温度的增高而减少。出乎意料的是,氢气的添加并不延长催化剂的寿命。该工艺过程对炭/炭复合材料的制备展示出良好的潜力。

关键词：催化生长炭炭纤维烷烃气浸渍显微镜方法

Stable isotope paleohydrology and chemostratigraphy of the Albian Wayan Formation from the wedge-top depozone,North American Western Interior Basin

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Science China Earth Sciences 2017年第1期60卷 44-57页

作者： jeffrey B.ROSS Greg A.LUDVIGSON Andreas MOLLER Luis A.GONZALEZ j.D.walker Department of Geology University of Kansas Kansas Geological Survey University of Kansas

Understanding of the role of atmospheric moisture and heat transport in the climate system of the Cretaceous greenhouse world represents a major challenge in Earth system science. Stable isotopic paleohydrologic data from mid-Cretaceous paleosols in North America, from paleoequatorial to paleoArctic latitudes, have been used to constrain the oxygen isotope mass balance of the Albian hydrologic cycle. Over the range from 40°-50°N paleolatitude, sideritic paleosols predominate, indicating paleoenvironments with positive precipitation-evaporation （P-E） balances. Local exceptions occur on leeward side of the Sevier Orogen, where calcic paleosols in the wedge-top depozone record paleoenvironments with negative P-E balances in the orographic rain shadow. Stratigraphic sections in the Wayan Formation of Idaho （WF） were sampled from the wedge-top depozone. The units consist of stacked m-scale mudstone paleosols separated by m-scale sandstone-siltstone beds. Sections were sampled for organic carbon isotope profiles, and B-horizons from 6 well-developed paleosols were sampled for detrital zircons to determine maximum depositional ages. The first of these from the WF has produced a U-Pb concordia age of 101.0±1.1 Ma. This same WF section has produced a stratigraphic trend of upwardly decreasing δ18C values ranging from -24‰ upwards to -27‰ VPDB, suggesting correlation to the late Albian C15 C-isotope segment. Pedogenic carbonates from the WF principally consist of micritic calcite, with carbon-oxygen isotope values that array along meteoric calcite lines （MCLs） with δ18O values that range from -9.47‰ up to -8.39‰ VPDB. At approximately 42°N paleolatitude, these MCL values produce calculated paleoprecipitation values of-8.12‰ to -7.04‰ VSMOW, a range that is consistent with the estimates produced from other proxies at the same paleolatitudes across North America. These results indicate that despite the orographic rain shadow effect, the processes of meridional atmospheric moist

关键词： Cretaceous Paleoclimate Wayan Formation Pedogenic carbonates Geochronology

Effects of Gamma Irradiation for Sterilization on Aqueous Dispersions of Length Sorted Carbon Nanotubes

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Nano Research 2011年第4期4卷 393-404页

作者： jeffrey A. Fagan Nancy j. Lin Rolf Zeisler Angela R. Hight walker Polymers Division National Institute of Standards and Technology Gaithersburg MD 20899 USA Analytical Chemistry Division National Institute of Standards and Technology Gaithersburg MD 20899 USA Optical Technology Division. National Institute of Standards and Technology Gaithersburg MD 20899. USA

There is currently great interest in the potential use of carbon nanotubes as delivery vessels for nanotherapeutics and other medical applications. However, no data are available on the effects of sterilization methods on the properties of nanotube dispersions, the form in which most medical applications will be processed. Here we show the effects of gamma irradiation from a 60Co source on the dispersion and optical properties of single-wall carbon nanotubes in aqueous dispersion. Samples of different length-refined populations were sealed in ampoules and exposed to a dose of approximately 28 kGy, a level sufficient to ensure sterility of the dispersions. In contrast to literature results for solid-phase nanotube samples, the effects of gamma irradiation on the dispersion and optical properties of the nanotube samples were found to be minimal. Based on these results, gamma irradiation appears sufficiently non-destructive to be industrially useful for the sterilization of nanotube dispersions.

关键词： Nanotube single-wall nanotube (SWNT) single-wall carbon nanotube (SWCNT) gamma irradiation sterilization dispersion