检索结果-南通市图书馆

Development of ^(18)F-labeled radiotracers for neuroreceptor imaging with positron emission tomography

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2014年第5期30卷 777-811页

作者： Peter Brust Jrg van den Hoff Jrg Steinbach Helmholtz-Zentrum Dresden-Rossendorf Institute of Radiopharmaceutical Cancer ResearchPermoserstrasse 15Leipzig04318Germany

Positron emission tomography （PET） is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide routinely used in the radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109.8 min. The delivery of such radiotracers into the brain provides images of transport, metabolic, and neurotransmission processes on the molecular level. After a short introduction into the principles of PET, this review mainly focuses on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as described here provides molecular probes which not only are useful for imaging of human brain diseases, but also allow molecular neuroreceptor imaging studies in various small-animal models of disease, including genetically- engineered animals. Furthermore, they provide a powerful tool for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo.

关键词： Alzheimer's disease autoradiography blood-brain barrier brain tumor cholinergic system kinetic modeling metabolism molecular imaging neurodegeneration positron emission tomography precursor psychiatric disorder radiotracer sigma receptor

Experimental and Numerical Investigation of the Flow in Rotating Diverging Channels

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2010年第2期19卷 115-119页

作者： R.A.van den Braembussche J.Prinsier A.Di Sante von Karman Institute for Fluid Dynamics Turbomachinery and Propulsion Department Waterloose steenweg presently at ALSToM PoWER Steam Turbines R&D Brown Boveri Strasse 7

This paper reports on an experimental and numerical study at low Reynolds number in order to evaluate the influence of the Coriolis forces on the flow in radial rotating channels. operating conditions correspond to the flow in radial impellers for micro gasturbine applications. A comparison of detailed flow measurements with CFD resuits indicates that Navier Stokes solvers with standard k-ω and SST turbulence models predict the flow surprisingly well and that no extra corrections for Coriolis forces are required at these operating conditions

关键词： Coriolis forces turbulence models rotating channels boundary layers

Evolution of real area of contact due to combined normal load and sub-surface straining in sheet metal

在线全文

学校读者我要写书评

暂无评论

Friction 2021年第4期9卷 840-855页

作者： Meghshyam SHISoDE Javad HAZRAT Tanmaya MISHRA Matthijn DE RooIJ Ton van den BooGAAED Nonlinear Solid Mechanics Faculty of Engineering TechnologyUniversity of TwenteEnschede 7522 NBThe Netherlands Surface Technology and Tribology Faculty of Engineering TechnologyUniversity of TwenteEnschede 7522 NBThe Netherlands

Understanding asperity flattening is vital for a reliable macro-scale modeling of friction and *** sheet metal forming processes,sheet surface asperities are deformed due to contact forces between the tools and the *** addition,as the sheet metal is strained while retaining the normal load,the asperity deformation increases *** of the asperities determines the real area of contact which influences the friction and wear at the tool-sheet metal *** real area of contact between two contacting rough surfaces depends on type of loading,material behavior,and topography of the contacting *** this study,an experimental setup is developed to investigate the effect of a combined normal load and sub-surface strain on real area of *** and zinc coated steel sheets(GI)with different coating thicknesses,surface topographies,and substrate materials are used in the experimental *** element(FE)analyses are performed on measured surface profiles to further analyze the behavior observed in the experiments and to understand the effect of surface topography,and coating thickness on the evolution of the real area of ***,an analytical model is presented to determine the real area contact under combined normal load and sub-surface *** results show that accounting for combined normal load and sub-surface straining effects is necessary for accurate predictions of the real area of contact.

关键词： asperity flattening real area of contact sub-surface strain zinc coating sheet metal forming

How non-rapid eye movement sleep and Alzheimer pathology are linked

在线全文

学校读者我要写书评

暂无评论

World Journal of Psychiatry 2021年第11期11卷 1027-1038页

作者： Annelies Falter Maarten J A van den Bossche Department of Geriatric Psychiatry University Psychiatric Center KU LeuvenLeuven 3000Belgium Center for Neuropsychiatry Research Group PsychiatryDepartment of NeurosciencesLeuven Brain InstituteKU LeuvenLeuven 3000Belgium

Alzheimer's disease(AD)is a multifactorial neurodegenerative disorder characterized by the presence of senile plaques and neurofibrillary *** attempts to identify characteristic factors that are associated with the presence of the AD pathology on the one hand and that increase the risk of developing AD on the *** in non-rapid eye movement(NREM)sleep may meet both requirements for various ***,NREM-sleep is important for optimal memory *** addition,studies report that the presence of AD pathology is associated with NREM-sleep ***,more and more results appear to suggest that sleep problems are not only a symptom of AD but can also increase the risk of *** of these studies suggest that it is primarily a lack of NREM-sleep that is responsible for this increased ***,the majority investigated sleep only through subjective reporting,as a result of which NREMsleep could not be analyzed *** aim of this literature study is therefore to present the results of the studies that relate the AD pathology and NREM-sleep(registered by electroencephalography).Furthermore,we try to evaluate whether NREM-sleep analysis could be used to support the diagnosis of AD and whether NREM-sleep deficiency could be a causal factor in the development of AD.

关键词： Alzheimer’s disease Mild cognitive impairment Sleep Non-rapid eye movement sleep Amyloid beta-peptides Tau proteins Electroencephalography

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

神经网络补偿机床热变形误差的机器学习技术

机械工程学报 2000年第1期36卷 92-95,105页

作者：杨庆东 van den bergh C Venherck P KruthJP 北京机械工业学院机械系北京100085 比利时鲁文大学

研究了以神经网络（ＮＮ）为模型的软件补偿不同机床热误差。提出知识获取是神经网络建模的关键环节。两种数控机床被用来研究分析热变形，通过测量实验获取学习数据，特别是温度测量和传感器数目的选取。介绍了机器学习技术和学习数据... 详细信息

研究了以神经网络（ＮＮ）为模型的软件补偿不同机床热误差。提出知识获取是神经网络建模的关键环节。两种数控机床被用来研究分析热变形，通过测量实验获取学习数据，特别是温度测量和传感器数目的选取。介绍了机器学习技术和学习数据组织方法，包括归纳学习和推理学习。给出了预报补偿的结果和精度评价。

关键词：热变形知识获取神经网络误差补偿机床

Fearful imagery induces hyperventilation and dyspnea in medically unexplained dyspnea

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2008年第1期121卷 56-62页

作者： HAN Jiang-na ZHU Yuan-jue LUo Dong-mei LI Shun-wei Ilse van Diest omer van den bergh KarelP van de Woestijne Department of Pneumology Peking Union Medical CollegeHospital Chinese Academy of Medical Sciences Beijing 100730China Department of Psychology University of Leuven B-3000 LeuvenBelgium Department of Pneumology U Z Gasthuisberg B-3000 LeuvenBelgium

Background Medically unexplained dyspnea refers to a condition characterized by a sensation of dyspnea and is typically applied to patients presenting with anxiety and hyperventilation without underlying cardiopulmonary pathology. We were interested to know how anxiety triggers hyperventilation and elicits subjective symptoms in those patients. Using an imagery paradigm, we investigated the role of fearful imagery in provoking hyperventilation and in eliciting symptoms, specifically dyspnea. Methods Forty patients with medically unexplained dyspnea and 40 normal subjects matched for age and gender were exposed to scripts and asked to imagine both fearful and restful scenarios, while end-tidal PCo2 （PetCo2） and breathing frequency were recorded and subjective symptoms evaluated. The subject who had PetCo2 falling more than 5 mmHg from baseline and persisting at this low level for more than 15 seconds in the imagination was regarded as a hyperventilation responder. Results In patients with medically unexplained dyspnea, imagination of fearful scenarios, being blocked in an elevator in particular, induced anxious feelings, and provoked a significant fall in PetCo2 （P〈0.05）. Breathing frequency tended to increase. Eighteen out of 40 patients were identified as hyperventilation responders compared to 5 out of 40 normal subjects （P〈0.01）. The patients reported symptoms of dyspnea, palpitation or fast heart beat in the same fearful script imagery. Additionally, PetCo2 fall was significantly correlated with the intensity of dyspnea and palpitation experienced during the mental imagery on one hand, and with anxiety symptoms on the other. Conclusions Fearful imagery provokes hyperventilation and induces subjective symptoms of dyspnea and palpitation in patients with medically unexplained dyspnea.

关键词： medically unexplained dyspnea hyperventilation anxiety dyspnea mental imagery

The reproductive biology of a Central American cichlid Neetroplus nematopus in Lake Xiloá ,Nicaragua

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2010年第1期56卷 43-51页

作者： Kenneth R.McKAYE Jeremy HALE Eric P.van den berghE World Wide Fund for Nature Finland Universidad de Centroamericana Department of Mathematics Science and Technology Ave Maria University Latin American Campus

This study was conducted to provide a five-year database on the breeding seasonality and breeding biology of a Central American cichlid fish Neetroplus nematopus, a biparental substratum-spawning cichlid that cares for its eggs, wrigglers, and fry for up to six weeks. A total of 503 breeding pairs were monitored for breeding success. Breeding pairs of N. nematopus are sexually dimorphic in size, with females averaging 39% of male body mass. Fry emerged from 85% of nesting cavities. After three weeks, only 30% of the broods were present in the nesting cavity; these broods had a 30% survival rate, giving a 9% overall survival rate. Nineteen percent of the successful parents with three-week-old broods adopted foreign fry. A consistent unimodal breeding peak in December was observed for five years. This breeding peak differed dramatically from the bimodal breeding season 20 years found in the 1970s. The effects of extensive grenade fishing practices during the 1980s might have played a substantial role in the observed change. Grenade fishing stopped in 1991, and the number ofN. nematopus pairs increased by 136% from 1990 to 1995. With increased density of breeding fish, the breeding season for this species also expanded. The balance between divergent selection due to competition for breeding sites and stabilizing selection due to predation pressure on offspring is likely to mold the breeding season for N. nematopus and other cichlids of Lake Xilofi. We suggest that brood adoption and synchrony of breeding is a strategy to reduce predation on the parent＇s own young [Current Zoology 56 （1）： 43-51 2010].

关键词： Nicaragua Cichlids Breeding Reproduction Synchrony Seasonality

Insights into the radial water jet drilling technology-Application in a quarry

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 236-248页

作者： Thomas Reinsch Bob Paap Simon Hahn Volker Wittig Sidney van den Berg GFZ German Research Centre for Geosciences Telegrafenberg14473 PotsdamGermany TNo Sustainable Geo EnergyUtrechtThe Netherlands International Geothermal Centre-GZB Lennershofstr.14044801 BochumGermany Well Services Group Phileas Foggstraat 65NL-7825 AL EmmenThe Netherlands

In this context, we applied the radial water jet drilling(RJD) technology to drill five horizontal holes into a quarry wall of the Gildehaus quarry close to Bad Bntheim, Germany. For testing the state-of-the-art jetting technology, a jetting experiment was performed to investigate the influence of geological heterogeneity on the jetting performance and the hole geometry, the influence of nozzle geometry and jetting pressure on the rate of penetration, and the possibility of localising the jetting nozzle utilizing acoustic activity. It is observed that the jetted holes can intersect fractures under varying angles, and the jetted holes do not follow a straight path when jetting at ambient surface condition. Cuttings from the jetting process retrieved from the holes can be used to estimate the reservoir rock permeability. Within the quarry, we did not observe a change in the rate of penetration due to jetting pressure *** monitoring was partially successful in estimating the nozzle location. Although the experiments were performed at ambient surface conditions, the results can give recommendations for a downhole application in deep wells.

关键词： Acoustic monitoring Drilling performance Trajectory Permeability Rock properties Radial water jet drilling(RJD)

Comparison of three types of warm-up upon sprint ability in experienced soccer players

在线全文

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2019年第6期8卷 574-578页

作者： Roland van den Tillaar Eirik Lerberg Erna von Heimburg Department of Teacher Education Nord Tr?ndelag University College

Purpose:The study aimed to compare the effects of a long general warm-up,a long specific warm-up,and a short specific warm-up upon sprint ability in soccer ***:Twelve male soccer players(age:18.3±0.8 years,mean±SD;body mass:76.4±7.2 kg;body height:1.79±0.05 m) conducted 3 types of warm-ups with 1 week in between:a long general warm-up,a long specific warm-up,and a short specific warm-up followed by 3 sprints of 40 m *** best,average,and total sprinting times together with heart rate and ratings of perceived exertion were ***:The sprint times(best,average,and total time) were significantly better when performing a long specific or short specific warm-up compared with the long general warm-up(all p on exertion was significantly lower during the specific short warm-up(4.92 ± 0.90) compared with the longer ones(6.00 ± 0.74 and 6.25 ± 0.87,respectively).Conclusion:Specificity is more important in a warm-up routine before sprint performance than the duration of the warm-up.

关键词： Duration Performance Received perception exertion Running Specificity Total sprinting times