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Street networks in relation to landforms： Implications for fast-growing cities

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Journal of geographical Sciences 2014年第2期24卷 363-381页

作者： Nahid MOHAJERI Agust gudmundsson Department of geography University College London Gower Street Pearson Building London WCIE 6BT UK Solar Energy and Building Physics Laboratory (LESO-PB) Ecole Polytechnique Federale de Lausanne(EPFL) 1015 Lausanne Switzerland Department of Earth Sciences Queen's Building Royal Holloway University of London Egham TW20 0EXUK

In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful （a river） and Khorramabad （moun- tains and valleys）, but no clear effects on the cities of Yazd and Nain. Also, where the street orientation is peaked, the gibbs/Shannon entropy （a measure of dispersion or spread） is low, but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are, on average, shorter and denser （more streets per unit area） than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts, implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades, with the newer outer parts expanding rapidly. As shown here, the rapidly formed outer parts （with greater dispersion in street patterns） have significantly different textures from those of the older inner parts, indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide, particularly for analysing the effects of landforms on city shape and texture.

关键词： street networks entropy landscapes gIS spatial analysis

Intracranial Pressure and the Role of the Vagus Nerve: A Hypothesis

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World Journal of Neuroscience 2014年第2期4卷 164-169页

作者： gardar gudmundsson Uppsalir Medical Center Reykjavik Iceland

There is reason to believe that the vagus nerve carries sensory afferent messages from the intracranial cavity as it does from the other body cavities. Considering the arachnoid granulations as a secretory apparatus instead of an organ transporting cerebrospinal fluid, a simple model can be built. Assuming that the arachnoid granulations produce nitric oxide in accordance with changes in the intracranial pressure, the jugular foramen with the vagus nerve lying just subendothelially is where this message would be received. Other chemical substances from the granulations or other intracranial tissues could of course also act as messengers. This would mean that the brain stem could adjust to changes in intracranial pressure with small changes in cerebral venous resistance. The general idea is that intracranial pressure is a passive function of the intracranial pressure-volume relationship. But the hypothesis suggests that the vagus nerve constantly mediates changes in intracranial pressure to the brain stem that can rapidly adjust cerebral venous resistance. This control is totally intracranial and easily overridden by considerable changes in absorption of spinal fluid or intracranial calamities. This article looks for clues in support of the idea that the vagus nerve mediates intracranial pressure changes to the brain stem.

关键词： Intracranial Pressure Vagus Nerve Nitric Oxide Arachnoid granulations Jugular Foramen Cerebrospinal Fluid

Normal Pressure Hydrocephalus: A Simple Hypothesis

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Open Journal of Modern Neurosurgery 2013年第1期3卷 4-8页

作者： gardar gudmundsson Uppsalir Medical Center Reykjavik Iceland

Normal pressure hydrocephalus is a devious phenomenon. It is a disease that is difficult to diagnose and difficult to treat, the only treatment being a ventriculo-peritoneal shunt, though good shunting results rarely pass a 70% level of effectiveness. We need to understand its pathophysiology better before things will improve. Although some colleagues know it as a possible “reversible dementia” others hardly know about its existence. Solutions would also have value for the general understanding of hydrocephalus of other types. Many theories have been published recently in the search for the missing pieces in this puzzle and I feel that my own postulations could turn out to be useful. After years of diagnosing and operating on hydrocephalus patients I propose that: 1) There is reason to believe that patients with the Apoprotein E3/3 genotype and a high head size percentile are particularly vulnerable to developing idiopathic normal pressure hydrocephalus (iNPH). 2) The classical theory that the arachnoid granulations (Ag) transport cerebrospinal fluid (CSF) into the venous circulation is wrong. I postulate, that the Ag essentially are sensors, registering the pressure differences between the CSF in the subarachnoidal space at the top of the skull and the venous pressure in the sagittal sinus. The Ag’s endothelium produces nitric oxide (NO) as a messenger that is received by the vagus nerve at the jugular foramen. 3) The disease has its fundamental pathology in the subpial space in the large cisternas and along the large vessels under the brain. Here the intravenous absorption of cerebrospinal fluid (CSF) takes place. Cerebrospinal fluid is transported into the subpial venules and veins, driven by the pulse pressure of the subpial arteries. Morphological changes in the pial/subpial anatomy explain the existence of acquired normal pressure hydrocephalus (aNPH).

关键词： Normal Pressure Hydrocephalus ApoE3 Head Size Arachnoid granulations Subpial Absorption

Simulations of Heat and Moisture Conditions in a Retrofit Wall Construction with Vacuum Insulation Panels

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Journal of Civil Engineering and Architecture 2013年第7期7卷 781-788页

作者： Kjartan gudmundsson Peyman Karami Department of Civil and Architectural Engineering Royal Institute of Technology (KTH) Stockholm 100 44 Sweden

Vacuum insulation panels provide unprecedented possibilities for renovating the existing building stock in a manner that reduces the thermal losses through the building envelope. This study is focused on the implementation of VIPs （vacuum insulation panels） in energy retrofit projects with rendered outer walls. Particular emphasis is put on reducing the thermal bridges due to mechanical fasteners and at the joints of the panels. These are evaluated through a parametric study of the impact of the thermal conductivity of the joints of the panels and the adjacent insulation layer as well as the material of the fasteners. The study is carried out with 3D FEM （finite element method） simulations software. Furthermore, the moisture conditions in the construction are studied. The dynamic moisture behavior of a wall construction is modeled with a two dimensional FEM model. The long term effects of vapor diffusion are investigated in terms of accumulated moisture and the risk of condensation. The results illustrate that vacuum insulation on the outside of the wall construction does not pose a moisture problem to the construction. The simulations are based on a draft of a new technical solution for the refurbishment of a building that is typical for the great Swedish building program of the 1970s.

关键词： Vacuum insulation panels retrofit project thermal bridges parametric study moisture conditions FEM model.

Cement Bonded Particle Boards with Different Types of Natural Fibres—Using Carbon Dioxide Injection for Increased Initial Bonding

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Open Journal of Composite Materials 2018年第1期8卷 28-42页

作者： Bjorn Marteinsson Edgar gudmundsson Faculty of Civil and Environmental Engineering University of IcelandReykjavikIceland Innovation Center Iceland ReykjavikIceland Speca ReykjavikIceland

The effect of CO2 injection on initial strength increase and hardening of cement-fibre mix in a cement bonded particle board (CBPB) production was evaluated. Different cement contents, formation pressure and types of fibres were considered. The initial strength increase with CO2 injection is so much faster than this caused by conventional hydration that the produced samples do not need additional curing before they can be stored. Similar strength and stiffness values as in conventional products on the market are gained with lower cement content for similar types of fibres. Visual inspection of board surfaces aged for 13 years in a harsh exterior environment as well as comparison of strength and stiffness values for these boards when new and after ageing, gives a very satisfying result. The combined effect of the above discussed gains results in markedly increased productivity at lower cost and lower environmental impacts than is possible in traditional CBPB production.

关键词： Fibre Cements Carbon Dioxide Initial Hardening Natural Fibres Strength Durability

glucosamine increases the expression of YKL-40 and osteogenic marker genes in hMSC during osteogenic differentiation

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Natural Products and Bioprospecting 2012年第2期2卷 87-91页

作者： Ramona LIEDER Sigrídur Thóra REYNISDOTTIR Finnbogi THORMÓDSSON Chuen-How Ng Jon Magnús EINARSSON Jóhannes gÍSLASON Jóhannes BJORNSSON Sveinn gudmundsson Pétur Henry PETERSEN Olafur Eysteinn SIgurJONSSON The Blood Bank Landspitali University HospitalSnorrabraut 60105 ReykjavikIceland School of Science and Engineering Reykjavik UniversityMenntavegi 1101 ReykjavikIceland genis ehf Vatnagördum 18104 ReykjavikIceland Biomedical Center University of IcelandVatnsmyrarvegi 16101 ReykjavikIceland Department of Anatomy Medical FacultyUniversity of IcelandVatnsmyrarvegi 16101 ReykjavikIceland Department of Pathology Landspitali University HospitalBaronsstig101 ReykjavikIceland

Human mesenchymal stem cells(hMSC)can be expanded in vitro and differentiated towards osteogenic,chondrogenic or adipogenic lineages,making them an attractive source for tissue engineering and regenerative ***-like-proteins(CLPs)belong to the family 18 glycosyl hydrolases and are believed to play a role in inflammation and tissue *** aim of this study was to determine the effect of the aminosugar glucosamine on the expression of the CLP YKL-40 during osteogenic differentiation of *** did not affect multipotency of hMSC nor proliferation rate of undifferentiated ***-40 was expressed during both expansion of undifferentiated hMSC and during osteogenic differentiation.A slight but non-significant increase in YKL-40 expression was observed with glucosamine,accompanied by a pH-dependent delay in ***,glucosamine induced higher expression of osteogenic marker genes.

关键词： YKL-40 mesenchymal stem cells osteogenic differentiation chitinase-like-protein

聚集在岩浆房周围的张应力对侵入作用和喷出作用频率的影响

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国外火山地质 1990年第3期 91-104页

作者： Agust gudmundsson 林峻

目前,人们对与火山作用伴生的侵入和喷出作用频率的控制因素了解甚少。作者认为对离散板块边界的火山来说,其侵入和喷出作用的频率主要取决于供给岩浆的岩浆房周围张应力的聚集。这种应力的聚集主要是与扩张作用有关的外加张应力和岩浆... 详细信息

目前,人们对与火山作用伴生的侵入和喷出作用频率的控制因素了解甚少。作者认为对离散板块边界的火山来说,其侵入和喷出作用的频率主要取决于供给岩浆的岩浆房周围张应力的聚集。这种应力的聚集主要是与扩张作用有关的外加张应力和岩浆房的高/宽比值的函数。快的扩张速度和大的高/宽比值导致张应力在岩浆房周围快速聚集,从而增加了侵入作用的频率。现已发现,就一条火山带中相同深度岩浆房而言,其中高/宽比值最大的岩浆房通常岩浆

关键词：岩浆房浅部冰岛侵入作用板块运动北欧地球动力学张应力拉应力岩墙群周围

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自动气道量化与特发性肺纤维化的死亡率相关

国际医学放射学杂志 2024年第1期 127-127页

作者： W.K.Cheung A.Pakzad N.Mogulkoc S.Needleman B.Rangelov E.gudmundsson 刘莹莹

摘要目的检验气道量化指标是否与特发性肺纤维化（IPF）的死亡率相关。方法观察性队列研究埃格大学医院的IPF病人（90例），采用气道分析工具Air Quant计算了第2～6

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In-situ characterization of metal nanoparticles and their organic coatings using laser-vaporization aerosol mass spectrometry

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Nano Research 2015年第12期8卷 3780-3795页

作者： Patrik T. Nilsson Axel C. Eriksson Linus Ludvigsson Maria E. Messing Erik Z. Nordin Anders gudmundsson Bengt O. Meuller Knut Deppert Edward C. Fortner Timothy B. Onasch Joakim H. Pagels Ergonomics and Aerosol Technology Lund University P.O. Box 118 Lund SE-22100 Sweden Nuclear Physics Lund University P.O. Box 118 LundSE-22100 Sweden Solid State Physics Lund University P.O. Box 118 Lund SE-22100 Sweden Synchrotron Radiation Research Lund University P.O. Box 118 Lund SE-22100 Sweden Aerodyne Research Inc. Billefica MA 01821-3976 USA

The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent offiine analysis, which may alter the particle characteristics. In this work, we use laser-vaporization aerosol mass spectrometry （LV-AMS） with 70-eV electron ionization for real-time, in-situ nanoparticle characterization. The particle characteristics are examined for various aerosol synthesis methods, degrees of sintering, and for controlled condensation of organic material to simulate surface coating/functionalization. The LV-AMS is used to characterize several types of metal nanoparticles （Ag, Au, Pd, PdAg, Fe, Ni, and Cu）. The degree of oxidation of the Fe and Ni nanoparticles is found to increase with increased sintering temperature, while the surface organic-impurity content of the metal particles decreases with increased sintering temperature. For aggregate metal particles, the organic-impurity content is found to be similar to that of a monolayer. By comparing different equivalent-diameter measurements, we demonstrate that the LV-AMS can be used in tandem with a differential mobility analyzer to determine the compactness of synthesized metal particles, both during sintering and during material addition for surface functionalization. Further, materials supplied to the particle production line downstream of the particle generators are found to reach the generators as contaminants. The capacity for such in-situ observations is important, as it facilitates rapid response to undesired behavior within the particle production process. This study demonstrates the utility of real-time, in-situ aerosol mass spectrometric measurements to characterize metal nanoparticles obtained directly from the synthesis process line, including their chemical composition, shape, and contamination, providing the potential for effective optimization of process operating p

关键词： metal aeroso1 organic surface coating contamination morphology alloy spark discharge