检索结果-南通市图书馆

Gluon number fluctuations and diffusive scaling effect

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

Frontiers of physics 2011年第1期6卷 100-105页

作者： Wolfgang fischer Department of Physics Bielefeld University of Applied Sciences Bielefeld 33615 Germany

The diffusive scaling is studied based on pomeron loop equations in the fixed coupling case. At Y 〉〉 YDS, the gluon number fluctuations become important, the geometric scaling is replaced by the diffusive scaling. In the diffusive scaling regime, the deep inelastic scattering （DIS） total scattering cross-section is a function of single variable ln[1/（r^2Qs^2（z））]. We show that the deep inelastic scattering experimental data lie on a single curve, which seems to indicate the existence of the diffusive scaling phenomenology in the deep inelastic scattering.

关键词： gluon number fluctuations proton structure function pomeron loop

Geometric Bone Modeling:From Macro to Micro Structures

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

Journal of Computer Science & Technology 2010年第3期25卷 614-622页

作者： Oded Zaideman Anath fischer Laboratory for Computer Aided Design & Life Cycle Engineering Faculty of Mechanical Engineering Technion Israel Institute of Technology

There is major interest within the bio-engineering community in developing accurate and non-invasive means for visualizing, modeling and analyzing bone micro-structures. Bones are composed of hierarchical bio-composite materials characterized by complex multi-scale structural geometry. The process of reconstructing a volumetric bone model is usually based upon CT/MRI scanned images. Meshes generated by current commercial CAD systems cannot be used for further modeling or analysis. Moreover, recently developed methods are only capable of capturing the micro-structure for small volumes （biopsy samples）. This paper examines the problem of re-meshing a 3D computerized model of bone micro- structure. The proposed method is based on the following phases： defining sub-meshes of the original model in a grid-based structure, remeshing each sub-mesh using the neural network （NN） method, and merging the sub-meshes into a global mesh. Applying the NN method to micro-structures proved to be quite time consuming. Therefore, a parallel, grid-based approach was applied, yielding a simpler structure in each grid cell. The performance of this method is analyzed, and the method is demonstrated on real bone micro-structures. Furthermore, the method may be used as the basis for generating a multi-resolution bone geometric model.

关键词： bone modeling micro-structures micro CT (#CT) scanning technology

Micro-site Conditions of Epiphytic Orchids in a Human Impact Gradient in Kathmandu Valley, Nepal

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2012年第3期9卷 331-342页

作者： Yagya Prasad ADHIKARI Anton fischer Hagen Siegfried fischer Geobotany Department of Ecology and Ecosystem Management Technische Universitt München Hans-Carl-von-Carlowitz-Platz 2 D-85354 Freising Germany

We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of sing

关键词： Human impact Host tree Micro-climate Epiphytic orchids Remote sensing Conservation Nepal

Epiphytic orchids and their ecological niche under anthropogenic influence in central Himalayas,Nepal

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第5期13卷 774-784页

作者： ADHIKARI Yagya Prasad fischer anton fischer Hagen Siegfried Geobotany Department of Ecology and Ecosystem ManagementTechnische Universit?t München

The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions：（1） What is the ecological niche of the different epiphytic orchid species？（2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.

关键词： Host characteristics Epiphytic orchids Anthropogenic disturbances Canopy ecosystem Ecological niche Himalayas

Liquid-phase epitaxy of metal organic framework thin films

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第12期54卷 1851-1866页

作者： fischer Roland A. Organometallics and Materials Chemistry Ruhr-Universitt Bochum

Metal-organic framework(MOF) thin films are multilayer materials ranging from nanometers to micrometers in thickness,physically or chemically adhesive to a(functionalized) substrate and,in an ideal case,exhibiting low roughness and high *** innovative approaches have been developed for MOF thin film *** these advanced materials,surface-attached metal-organic frameworks(SURMOFs) are an important class of MOF ***,fabricated in a step-by-step liquid phase epitaxial(LPE) fashion by alternating deposition of metal and organic linker precursors on a functionalized substrate,for example,thiolate-based self-assembled monolayers(SAMs),have already exhibited their utility in both research and potential *** combine surface science and the chemistry of MOFs,possessing the following unique advantages that cannot be accessed through other methods:(i) precisely controlling thickness,roughness and homogeneity as well as growth orientation,(ii) studying of MOF growth mechanism,(iii) modifying/tailoring MOFs' structures during the SURMOF growth and thus creating customizable properties,and(iv) existing in the form of thin film/membrane for direct applications,for example,as *** review discusses the oriented and crystalline SURMOFs fabricated by LPE approach,covering their preparation,growth mechanism,and characterization methodology as well as applications based upon the most newly updated knowledge.

关键词： coordination chemistry metal-organic frameworks (MOFs) liquid phase epitaxy step-by-step approach surface science thin film

SOME ALMOST ALL RESULTS CONCERNINGTHE PJATECKII-SAPIRO PRIME NUMBERS

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1996年第3期17卷 279-288页

作者： fischer,D. ZHANTAO InstituteofMathematics Albert-LudwigsUniversityAlbertstrasse23bD-W-7800FreiburgGermany. InstituteofMathematics ShandongUniversityJinan250100China.

The distribution of the Pjateckii-Sapiro prime numbers in arithmetic progressions is investigated, and a Bombier i- Vinogr adov typ e mean- value t heorem and anot her almost all resultconcerning this problem are esta... 详细信息

关键词： Pjateckii-Sapiro prime number Arithmetic progression Bombieri-Vinogradov type mean-value theorem

The essence of bidirectional programming

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第5期58卷 76-96页

作者： fischer Sebastian HU ZhenJiang PACHECO Hugo Department of Computing Science Christian-Albrechts-University of Kiel Information Systems Architecture Research Division National Institute of Informatics Department of Informatics The Graduate University for Advanced Studies (SOKENDAI) School of Electronics Engineering and Computer Science Peking University Department of Computer Science Cornell University

Bidirectional transformations(BXs), programs with a forward transformation and a backward transformation that maintain consistency between input and output, are routinely written in ways that do not let programmers specify their behavior completely. Several bidirectional programming languages exist to aid programmers in writing BXs with increased maintainability but decreased expressiveness. Such languages allow programmers to write BXs as one program for both directions, which is easier to maintain than separate programs for each direction. However, the maintainability provided by existing bidirectional languages comes at the cost of expressiveness because the ambiguity of synchronization is solved by default strategies which are hidden from programmers. The programmers’ inability to influence synchronization strategies has led to the proposal of a vast number of approaches that consider tailor-made synchronization strategies for particular *** this paper, we argue that such ambiguity is essential for BX and advocate that the synchronization strategy should not be hidden from programmers but considered from the start. We propose a novel approach to specifying so-called well-behaved bidirectional programs by their backward transformations, capable of expressing all aspects of a BX while retaining maintainability. Soundness of our approach results from a systematic analysis, based on existing mathematical concepts, of the instrumental laws of well-behaved BXs. We show that well-behaved BXs are uniquely determined by their backward transformations and corresponding forward transformations can be obtained for free.

关键词： bidirectional transformation software adaption and coevolution bidirectional programming

Transplanting neural progenitors to build a neuronal relay across the injured spinal cord

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2014年第12期9卷 1173-1176页

作者： Christopher Haas Itzhak fischer Drexel University College of Medicine Department of Neurobiology & Anatomy

Cellular transplantation for repair of spinal cord injury is a prom- ising therapeutic strategy that includes the use of a variety of neural and non-neural cells isolated or derived from embryonic and adult tissue as well as embryonic stem cells and induced plu- ripotent stem cells. In particular, transplants of neural progenitor cells （NPCs） have been shown to limit secondary injury and scar formation and create a permissive environment in the injured spinal cord through the provision of neurotrophic molecules and growth supporting matrices that promote growth of injured host axons. Importantly, transplants of NPC are unique in their poten- tial to replace lost neural cells - including neurons, astrocytes,

关键词： Transplanting neural progenitors to build a neuronal relay across the injured spinal cord CSPG NPC GRP

Parthenolide:a novel pharmacological approach to promote nerve regeneration

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2016年第10期11卷 1566-1567页

作者： Heike Diekmann Dietmar fischer Division of Experimental Neurology Department of NeurologyHeinrich-Heine-University

Traumatic axonal lesions disrupt the connections between neurons and their targets, leading to loss of motoric and sensory functions. Although lesioned peripheral nerves can principally regenerate, the rate of recovery depends on the mode and severity of the respective injury （Grinsell and Keating, 2014）. While injuries close to the innervation site have good chances of recovery, long distance regeneration is particularly problematic due to relatively slow axonal growth rates, which even under favorable conditions do not normally exceed 1-2 mm per day （Sunderland, 1947）.

关键词： BDNF NGF