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Is Faster Necessarily Better? 3G Take-Up Rates and the Implications for Next Generation Services

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International Journal of Communications, Network and System Sciences 2012年第8期5卷 463-480页

作者： christian m. Dippon NERA Economic Consulting San Francisco USA

most countries have allocated 3G spectrum and are in the process of allocating advanced wireless services and 4G spectrum, both of which promise subscribers significantly faster broadband speeds. Operators anticipate that subscribers will adopt these services swiftly thereby justifying the large investments. Yet, why is it the case that only two countries in the world have more 3G than 2G subscribers? This study examines the drivers behind 3G diffusion using linear probability models and qualitative choice (logit) analysis. Time series diffusion models show that diffusion patterns follow an s-curve pattern, favoring the Gompertz curve.

关键词： Spectrum Diffusion Broadband Linear Probability models Qualitative Choice Analysis

Widely tunable,high-power,femtosecond noncollinear optical parametric oscillator in the visible spectral range

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Photonics Research 2021年第9期9卷 1715-1718页

作者： ROBIN mEVERT YULIYA BINHAmmER christian m.DIETRICH LUISE BEICHERT JOSéR.CARDOSO DE ANDRADE THOmAS BINHAmmER JINTAO FAN UWE mORGNER Institute of Quantum Optics Leibniz University HannoverWelfengarten 1D-30167 HannoverGermany Cluster of Excellence PhoenixD Welfengarten 1D-30167 HannoverGermany neoLASE GmbH Hollerithallee 17D-30419 HannoverGermany

Ultrafast visible radiation is of great importance for many applications ranging from spectroscopy to *** some regions in the visible range are not covered by laser gain media,optical parametric oscillators offer an added *** a high-power broadband laser source,the ability to rapidly tune the frequency of pulses with high-power spectral density offers an extra benefit for experiments such as multicolor spectroscopy or ***,we demonstrate a broadband,high-power,rapidly tunable femtosecond noncollinear optical parametric oscillator with a signal tuning range of 440–720 nm in the visible *** oscillator is pumped by the third harmonic of an Yb-fiber laser at 345 nm with a repetition rate of 50.2 ***,the signal wavelength is tuned by changing the cavity length only,and output powers up to 452 m W and pulse durations down to 268 fs are *** is,to the best of our knowledge,the first demonstration of a quickly tunable femtosecond optical parametric oscillator that covers nearly the entire visible spectral range with high output power.

关键词： tunable power tuning

The environmental threats from lead ammunition

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Eco-Environment & Health 2023年第1期2卷 16-17页

作者： christian Sonne Su Shiung Lam Niels Kanstrup Aarhus University Faculty of Technological SciencesDepartment of EcoscienceDK-4000 RoskildeDenmark Sustainability Cluster School of EngineeringUniversity of Petroleum&Energy StudiesDehradunUttarakhand 248007India Higher Institution Centre of Excellence(HICoE) Institute of Tropical Aquaculture and Fisheries(AKUATROP)Universiti Malaysia Terengganu21030 Kuala NerusTerengganuMalaysia University Centre for Research and Development Department of ChemistryChandigarh UniversityGharuanMohaliPunjabIndia Department of Ecoscience Aarhus UniversityC.F.Møllers Alle 88000 Aarhus CDenmark

Lead(Pb)is an extremely toxic persistent element,considered a factor in the fall of the Roman Empire 2000 years ago due to its use in plumbing and as a wine sweetener[1].The effects of lead include adverse neurological effects,reproductive impairment,and anaemia[2].One continuing source of lead in the environment is lead ammunition,which presents health risks to consumers of game meat,including humans,predatory and scavenging birds,and other animals.

关键词： continuing birds sweet

Growth and form of Quercus robur and Fraxinus excelsior respond distinctly different to initial growing space: results from 24-year-old Nelder experiments

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Journal of Forestry Research 2013年第1期24卷 1-14页

作者： christian Kuehne Patrick Pyttel Edgar Kublin Jürgen Bauhus Institute of Silviculture University of FreiburgD-79085 Freiburg i.Br.Germany. Faculty of Forests and Forestry University of Applied Sciences Wei- henstephan-TriesdorfHans-Carl-von-Carlowitz-Platz 3D-85354 FreisingGermany Department of Biometry and Informatics Forest Research Station Baden-WürttembergPostfach 708D-79007 FreiburgGermany

Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to first dead and first live branch and branchiness） and stem and crown form of 24-year-old pedunculate oak （Quercus robur [L.]） and European ash （Fraxinus excelsior [L.]） were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha？1. mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots a

关键词： spacing trial stocking self-thinning intraspecific competition qualification spatially explicit modelling generalized additive model

Development and evaluation of an individual tree growth and yield model for the mixed species forest of the Adirondacks Region of New York, USA

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Forest Ecosystems 2017年第1期4卷 66-82页

作者： Aaron Weiskittel christian Kuehne John Paul mcTague mike Oppenheimer University of maine School of Forest Resources Orono ME 04469 USA. Rayonier Forest Research Center Yulee FL 32041 USA Rayonier Foresl Resources Fernandina Beach FL 32035 USA. University of maine 5755 I Nutting Hall Orono ME 04469-5755 USA.

Background： Growth and yield models are important tools for forest planning. Due to its geographic location, topology, and history of management, the forests of the Adirondacks Region of New York are unique and complex. However, only a relatively limited number of growth and yield models have been developed and/or can be reasonably extended to this region currently. methods： in this analysis, 571 long-term continuous forest inventory plots with a total of 10 - 52 years of measurement data from four experimental forests maintained by the State University of New York College of Environmental Science and Forestry and one nonindustrial private forest were used to develop an individual tree growth model for the primary hardwood and softwood species in the region. Species-specific annualized static and dynamic equations were developed using the available data and the system was evaluated for long-term behavior. Results： Equivalence tests indicated that the Northeast Variant of the Forest Vegetation Simulator （FVS-NE） was biased in its estimation of tree total and bole height, diameter and height increment, and mortality for most species examined. In contrast, the developed static and annualized dynamic, species-specific equations performed quite well given the underlying variability in the data. Long-term model projections were consistent with the data and suggest a relatively robust system for prediction. Conclusions： Overall, the developed growth model showed reasonable behavior and is a significant improvement over existing models for the region. The model also highlighted the complexities of forest dynamics in the region and should help improve forest planning efforts there.

关键词： Individual tree growth model mixed species Forest vegetation simulator

modeling of the Saltwater Intrusion Using the Level Set method. Application to Henry’s Problem

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Computational Water, Energy, and Environmental Engineering 2022年第1期11卷 11-33页

作者： Joachna meya Loua-Bouayi christian Tathy Adolphe Kimbonguila manounou Laboratoire mécanique Energétique et Ingénierie Ecole Nationale Supérieure Polytechnique Université Marien Ngouabi Brazzaville Congo

The salt intrusion phenomenon is caused by overexploitation of aquifers in coastal areas. This physical phenomenon has been the subject of numerous studies and numerous methods have been proposed, with the aim of protecting the quality of the water in these aquifers. This work proposes a two-dimensional saline intrusion model using the sharp interface approach and the level set method. It consists of a parabolic equation modeling the underground flow and a hyperbolic Equation (the level set equation) which makes it possible to track the evolution of the interface. High-order numerical schemes such as the space scheme WENO5 and the third-order time scheme TVD-RK were used for the numerical resolution of the hyperbolic equation. To limit the tightening of the contour curves of the level set function, the redistanciation or reinitialization algorithm proposed by mily:Verdana;">Su

关键词： Confined Aquifer Seawater Intrusion Level Set method Sharp Interface Henry Problem

Comparison of Cox model methods in A Low-dimensional Setting with Few Events

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Genomics, Proteomics & Bioinformatics 2016年第4期14卷 235-243页

作者： Francisco m. Ojeda christian miiller Daniela Bornigen David-Alexandre Tregouet Arne Schillert matthias Heinig Tanja Zeller Renate B. Schnabel Department of General and Interventional Cardiology University Heart Center Hamburg-Eppendorf 20246 Hamburg Germany German Center for Cardiovascular Research (DZHK) Hamburg |Kiel| Luebeck Germany Sorbonne Universites University Pierre et marie Curie Paris 06 Institut National pour la Sante et la Recherche Medicale (INSERM) Unite Mixte de Recherche en Sante (UMR_S) 1166 F-75013 Paris France Institute for Cardiometaholism and Nutrition (ICAN) F-75013 Paris France Institut fur medizinische Biometrie und Statistik Universitat zu Lubeck Universitatsklinikum Schleswig-Holstein Campus Lubeck 23562 Lubeck Germany Institute of Computational Biology German Research Center for Environmental Health Helmholtz Zentrum Munchen 85764 Neuherberg Germany

Prognostic models based on survival data frequently make use of the Cox proportional hazards model. Developing reliable Cox models with few events relative to the number of predictors can be challenging, even in low-dimensional datasets, with a much larger number of observations than variables. In such a setting we examined the performance of methods used to estimate a Cox model, including （i） full model using all available predictors and estimated by standard techniques, （ii） backward elimination （BE）, （iii） ridge regression, （iv） least absolute shrinkage and selection operator （lasso）, and （v） elastic net. Based on a prospective cohort of patients with manifest coronary artery disease （CAD）, we performed a simulation study to compare the predictive accuracy, calibration, and discrimination of these approaches, Candidate predictors for incident cardiovascular events we used included clinical variables, biomarkers, and a selection of genetic variants associated with CAD. The penalized methods, i.e., ridge, lasso, and elastic net, showed a comparable performance, in terms of predictive accuracy, calibration, and discrimination, and outperformed BE and the full model. Excessive shrinkage was observed in some cases for the penalized methods, mostly on the simulation scenarios having the lowest ratio of a number of events to the number of variables. We conclude that in similar settings, these three penalized methods can be used interchangeably. The full model and backward elimination are not recommended in rare event scenarios.

关键词： Proportional hazards regression Penalized regression Events per variable Coronary artery disease

Isolation and characterisation of human gingival margin-derived STRO-1/mACS^+ and mACS^-cell populations

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International Journal of Oral Science 2015年第2期7卷 80-88页

作者： Karim m Fawzy El-Sayed Sebastian Paris christian Graetz Neemat Kassem mohamed mekhemar Hendrick Ungefroren Fred Fndrich Christof Drfer Clinic for Conservative Dentistry and Periodontology School of Dental MedicineChristian Albrechts University Oral medicine and Periodontology Department Faculty of Oral and Dental MedicineCairo University Department of Operative and Preventive Dentistry Charite-Universitatsmedizin Berlin Department of Clinical Pathology Faculty of MedicineCairo University Clinic for Applied Cellular Therapy Christian Albrechts University

Recently,gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting（mACS） showed remarkable periodontal regenerative potential in *** a second-stage investigation,the present study＇s aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive（mACS~＋） and STRO-1-negative（mACS^-） cell populations from the human free gingival *** were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 ***,the mACS~＋ and mACS^- cell fractions were characterized by flow cytometry for expression of CD14,CD34,CD45,CD73,CD90,CD105,CD146/mUC18 and ***-forming unit（CFU） and multilineage differentiation potential were assayed for both cell *** marker expression was examined using real-time polymerase chain reaction（PCR）.mACS~＋ and mACS- cell fractions showed plastic ***~＋ cells,in contrast to mACS- cells,showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs（P〈0.01）.more than 95%of mACS~＋ cells expressed CD105,CD90 and CD73;lacked the haematopoietic markers CD45,CD34 and CD14,and expressed STRO-1 and CD146/***- cells showed a different surface marker expression profile,with almost no expression of CD14 or STRO-1,and more than 95%of these cells expressed CD73,CD90 and CD146/mUC18,as well as the haematopoietic markers CD34 and CD45 and ***~＋ cells could be differentiated along osteoblastic,adipocytic and chondroblastic *** contrast,mACS- cells demonstrated slight osteogenic *** mACS~＋ cells showed significantly higher expression of collagen I（P〈0.05） and collagen III（P〈0.01）,whereas mACS^- cells demonstrated higher expression of osteonectin（P〈0.05;mannWhitney）.The present study is the first to compare gingival mACS~＋ and mACS- cell populations demo

关键词： gingival progenitor populations margin periodontal cytometry collagen isolation dental sorting

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中非共和国民主化进程中的国际干预

中非共和国民主化进程中的国际干预

作者： Gonendji Galeyo christian Junior 华东政法大学

学位级别：硕士

1959年是中非共和国政治、体制和法律历史上特别重要的时期。1959年2月19日,这个在1958年12月1日宣布成立的共和国国家通过了第一部宪法。新建立的政治体制推动了两个政权的合作,尤其体现在分享法律的主动权上。这也反映在议会议程的一... 详细信息

1959年是中非共和国政治、体制和法律历史上特别重要的时期。1959年2月19日,这个在1958年12月1日宣布成立的共和国国家通过了第一部宪法。新建立的政治体制推动了两个政权的合作,尤其体现在分享法律的主动权上。这也反映在议会议程的一致决定上。最后,它体现在将立法权下放给行政部门,即通常在议会休会期间,政府可以通过法令的形式采取立法措施。此外,行政机关和立法机关还享有施压手段和互惠行为。一方面,谴责动议允许议会在发生危机时推翻政府;另一方面,行政机关拥有解散权,这允许它在正常任期结束之前终止代表的任期。与此同时,新兴法治的组成部分的军队凭借其组织和结构也构成了一支能够确保卫领土完整和维持秩序的部队。这支军队由大都市训练出来的军官组成,其力量来自纪律、凝聚力和及其非政治性甚至是中立形象。它被视为主权的熔炉。中非军队正是本着这种精神成立的,其征聘不考虑所有区域、种族和政治因素。同时,为向潜在的外国投资者提供保障,也应采取适当的安全措施。在经济上,中非共和国被认为是一个“富国”。该国拥有木材、棉花等自然资源以及钻石、黄金等富饶的,具有相当大的经济潜力。社会经济水平与政治频率之间有很强的相关性。换句话说,经济发展的相对水平有利于减少社会冲突,阶级对立的减少有助于和平的政治理解和更好地尊重人权和自由。总的来说,中非共和国在法律上、政治上、制度上和经济上都具备了确保货物和人民的法律和物质安全的条件。这一新的政治秩序的运作在国际、区域和国家各级带来了很大的希望。中非共和国的开国总统巴泰勒米·波冈达于1959年3月29日死于一场飞机失事,继而无法实现他的梦想,而失事具体情况尚不清楚。从那时起,中非共和国经历了一个非常多事的宪政政治演变,出现了不同的伟大政治家。1960年8月13日宣布独立后,中非共和国设立了共和国总统一职,由已经担任政府总统的大卫·达科担任。大卫·达科被选为共和国总统,从而集中了所有的行政权力。他从此成为共和国总统和政府的总统。1962年11月7日,他把事实上是单一政党的m.E.S.A.N转变为法律上的单一政党,并中止了《宪法》。1965年12月31日晚上,也就是新年前夜,军事政变发生,他被他的堂兄,即让·贝德尔·博卡萨中校驱逐出境。让·贝德尔·博卡萨的一生分为三个阶段:1966年至1972年,他担任军政府领导人;1972年至1976年,他宣布自己是总统;同年12月4日,新宪法确立中非共和国为中非帝国。最后阶段,他的政权残暴,并且存在大规模侵犯人权的行为,例如他封自己为“博卡萨一世皇帝”时。但中非帝国并没有持续太久,因为1979年9月20日,博卡萨在一场军事政变中被推翻:在法国伞兵的保护下,大卫·达科推翻了帝国政权,宣布回归共和国。这一行动被称为。独裁者的倒台后,大卫·达科通过1981年3月15日的选举重新掌权。然而,这次选举协商的有争议的结果产生了一场前所未有的政治危机,其结果是人命的损失,甚至危及国家的平衡。1981年9月1日,时任武装部队参谋长安德烈·柯林巴将军发动政变接管了权力。总统安德烈·柯林巴在1993年以前一直在总统制的框架内领导中非共和国,一方面作为军事领导人和军政府首脑,另一方面作为政治领导人。1980年代末的民主化之风吹走了中非共和国的一党政权,而人民有效参与政治生活的可能性实际上是不存在的。总统安德烈·柯林巴迫于形势,特别是内部和外部[13]的要求,于1993年8月22日接受了投票箱的裁决,昂热-菲利克斯·帕塔塞在第二轮选举中掌权。“民主选举”的昂热-菲利克斯·帕塔塞频繁面临军事政变企图和经济不稳定、社会危机、管理不善和腐败引发的军队哗变。然而,他的权力只持续了10年,因为在2003年3月15日,他的前参谋长弗朗索瓦·博齐泽将军在叛乱后被赶下台,并在2005年6月11日的选举后上台。综上所述,中非共和国从1958年至今的政治史可谓是“多事之秋”。这个国家以一个接一个的独裁政治政权而出名,这些政权的领导人每次都为了自己的个人利益而从根本上改变宪法文本。四十多年来,政府的管理方法一直存在缺陷。这导致了诸如权力过度个人化、基本人权被剥夺、未经选举和不负责任的政府占主导地位等现象。自独立以来,中非共和国一直饱受贫困、独裁和政治不稳定的困扰。所有不同政权的其他特征是腐败、裙带关系、即兴发挥、少数人没收权力、专断、缺乏明确的政治意愿和远见、排外、商业和权力概念狭隘。除此之外,中非政治家的特点也导致了国家政治生活中各角色之间的信任危机。几乎无一例外,中非共和国的每一位领导人上台后都被军事政变推翻。仅在这四十年中,中非共和国就经历了至少十次军事起义,除此之外,还有一种准永久性的叛乱状态,尽管不断组织所谓的,但这种状态尚未被根除。当然,中非共和国自1960年8月13日独立以来至今所经历的军事-政治危机是对人所固有的权利和

关键词：中非政治体制国际社会民主干预