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Search Results: 1 - 10 of 7787 matches for " Philip Becksch?fer "
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Enhanced Structural Complexity Index: An Improved Index for Describing Forest Structural Complexity  [PDF]
Philip Beckschfer, Philip Mundhenk, Christoph Kleinn, Yinqiu Ji, Douglas W. Yu, Rhett D. Harrison
Open Journal of Forestry (OJF) , 2013, DOI: 10.4236/ojf.2013.31005
Abstract:

The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural

On the exposure of hemispherical photographs in forests
Beckschfer P,Seidel D,Kleinn C,Xu J
iForest : Biogeosciences and Forestry , 2013, DOI: 10.3832/ifor0957-006
Abstract: At least 10 different methods to determine exposure for hemispherical photographs were used by scientists in the last two decades, severely hampering comparability among studies. Here, an overview of the applied methods is reported. For the standardization of photographic exposure, a time-consuming reference measurement in the open land towards the unobstructed sky was required so far. The two Histogram Methods proposed here make use of the technical advances of digital cameras which enable users to assess a photograph’s histogram directly at the location of measurement. This avoids errors occurring due to variations in sky lighting happening in the time span between taking the reference measurement and reaching the sample location within the forest. The Histogram Methods speed up and simplify taking hemispherical photographs, and introduce an objectively applicable, standardized approach. We highlight the importance of correct exposure by quantifying the overestimation of gap fraction resulting from auto-exposed photographs under a wide range of canopy openness situations. In our study, gap fraction derived from auto-exposed photographs reached values up to 900% higher than those derived from non-overexposed photographs. By investigating the size of the largest gap per photograph and the number of small gaps (gaps contributing less than 0.1% to gap fraction), we concluded that the overestimation of gap fraction resulted mainly from the overexposure of vegetation surrounding large gaps.
Echocardiographic assessment and percutaneous closure of multiple atrial septal defects
Andrew RJ Mitchell, Philip Roberts, Jonas Eichh?fer, Jonathan Timperley, Oliver JM Ormerod
Cardiovascular Ultrasound , 2004, DOI: 10.1186/1476-7120-2-9
Abstract: Atrial septal defect (ASD) closure is now commonly performed using a transcatheter, percutaneous approach and with the Amplatzer septal occluder, large defects can be safely closed [1,2]. Device deployment requires a rim of atrial septal tissue surrounding the defect to allow effective capture of the septum by the occluder. The rim of tissue is also important to separate the septal occluder from important structures including the inferior vena cava, coronary sinus and the atrioventricular valves.The majority of patients require a single device for closure of the ASD but a small proportion of patients may have more than one defect in the atrial septum. This can be difficult to diagnose using transthoracic echocardiography (TTE) as abnormal colour flow obscures the origins of the shunt, particularly if the second defect is situated inferiorly. We report three cases of patients referred for ASD closures that were found to have multiple ASDs and the techniques used to close these defects.A 34-year old woman was referred for consideration of percutaneous ASD closure. The ASD had been diagnosed when the patient was 12 years old and TTE had suggested that the right ventricle was dilating. At cardiac catheterisation there were mildly elevated right ventricular systolic pressures and a pulmonary to systemic flow ratio of over two. The secundum ASD was estimated to be 15 mm wide using TTE with aneurysmal formation of the interatrial septum. The patient was admitted for percutaneous ASD closure and underwent uncomplicated placement of a 17 mm Amplatzer septal occluder. Transesophageal echocardiography (TEE) during the procedure revealed the presence of a second ASD near the inferior vena cava and a small post-procedure shunt. The septal occluder did not completely cover both defects. Equivalent chest x-ray radiation dose (assuming a single posteroanterior projection chest x-ray is eight centi-Gray/cm2) was 400. Repeat TTE continued to demonstrate left to right shunting and the
Stability and Hierarchy of Quasi-Stationary States: Financial Markets as an Example
Yuriy Stepanov,Philip Rinn,Thomas Guhr,Joachim Peinke,Rudi Sch?fer
Quantitative Finance , 2015, DOI: 10.1088/1742-5468/2015/08/P08011
Abstract: We combine geometric data analysis and stochastic modeling to describe the collective dynamics of complex systems. As an example we apply this approach to financial data and focus on the non-stationarity of the market correlation structure. We identify the dominating variable and extract its explicit stochastic model. This allows us to establish a connection between its time evolution and known historical events on the market. We discuss the dynamics, the stability and the hierarchy of the recently proposed quasi-stationary market states.
Dynamics of quasi-stationary systems: Finance as an example
Philip Rinn,Yuriy Stepanov,Joachim Peinke,Thomas Guhr,Rudi Sch?fer
Quantitative Finance , 2015,
Abstract: We propose a combination of cluster analysis and stochastic process analysis to characterize high-dimensional complex dynamical systems by few dominating variables. As an example, stock market data are analyzed for which the dynamical stability as well as transitions between different stable states are found. This combined method also allows to set up new criteria for merging clusters to simplify the complexity of the system. The low-dimensional approach allows to recover the high-dimensional fixed points of the system by means of an optimization procedure.
Role of NOD2/CARD15 in coronary heart disease
Nour Eddine El Mokhtari, Stephan J Ott, Almut Nebel, Arne Sch?fer, Philip Rosenstiel, Matti F?rster, Michael Nothnagel, Rüdiger Simon, Stefan Schreiber
BMC Genetics , 2007, DOI: 10.1186/1471-2156-8-76
Abstract: In atherectomy tissue of CHD patients, NOD2 was detected in inflammatory cells at the luminal sides of the lesions. However, the allele and genotype frequencies of the three major CARD15 polymorphisms did not differ between CHD patients and controls.The NOD2 up-regulation in atheroma lesions indicates an involvement of this protein in the pathology of CHD. Although NOD2 could be important in local immune response mechanisms, none of the analyzed CARD15 variants seem to play a significant role in the etiology of CHD.Over the last years, it has become apparent that inflammation is a driving factor in the pathophysiology of coronary heart disease (CHD). Immune cells infiltrate the coronary artery lesion, and their mediator molecules aggravate progression and activation of the atherosclerotic lesions [1-4]. The importance of elevated C-reactive protein (CRP) as a negative prognostic marker of disease progression underlines the role of inflammation as a pathogenic factor [5]. There is increasing evidence from sero-epidemiological and animal studies that bacterial infection may be involved in the pathophysiology of the local chronic inflammatory process underlying atherosclerosis [6-9]. The initial observation of a specific infection with a single pathogen, e.g. Chlamydia pneumoniae, was increasingly challenged by new experimental findings demonstrating the presence of a wide spectrum of bacteria in the atherosclerotic plaque [10]. The variety and composition of bacterial species are compatible with the bacterial flora of human mucosal barriers [10,11], such as the oral cavity, the gastrointestinal, and the respiratory tract. As bacteria can translocate into the blood or lymph system from barrier organ surfaces, a secondary colonization of the plaques has been suggested. Lethiniemi et al. recently proposed that the destroyed surface of atheromas might act as mechanical sieves collecting bacteria from the circulation [11]. Impairment of mucosal barriers could therefore be
Reducing consumption to avert catastrophic global climate change: The case of aviation  [PDF]
Philip Cafaro
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.51A016
Abstract:

Avoiding potentially catastrophic global climate change is a moral imperative, demanding significant reductions in greenhouse gas emissions from all important transport sectors, including aviation. However, because passenger flights and freight traffic are increasing much faster than efficiency improvements, the aviation sector will not be able to reduce emissions, or even stabilize them at current levels, without direct, forceful action to reduce demand. This paper reviews the ethical principles and empirical realities supporting the case for reducing worldwide aviation traffic. It argues that most passenger air travel and air freight shipping represents unnecessary luxury consumption, which responsible moral agents should willingly reduce in order to mitigate global climate change. It considers several mechanisms for doing so, and contends that they may succeed, but only if combined with an explicit recognition and binding commitment that for the foreseeable future, aviation must be a slow-growth or no-growth sector of the world economy.

Weak vertical diffusion allows maintenance of cold halocline in the central Arctic
Ilker,FER,
Ilker
,FER

大气和海洋科学快报 , 2009,
Abstract: In spring preceding the record minimum summer ice cover detailed microstructure measurements were made from drifting pack ice in the Arctic Ocean, 110 km from the North Pole. Profiles of hydrography, shear, and temperature microstructure collected in the upper water column covering the core of the Atlantic Water are analyzed to determine the diapycnal eddy diffusivity, the eddy diffusivity for heat, and the turbulent flux of heat. Turbulence in the bulk of the cold halocline layer was not strong enough to generate significant buoyancy flux and mixing. Resulting turbulent heat flux across the upper cold halocline was not significantly different than zero. The results show that the low levels of eddy diffusivity in the upper cold halocline lead to small vertical turbulent transport of heat, thereby allowing the maintenance of the cold halocline in the central Arctic.
Linking Regional Science and Urban Economics: Long-Run Interactions among Preferences for Amenities and Public Goods  [PDF]
Philip E. Philip E. Graves
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.33035
Abstract: The linked nature of long-term patterns of urban deconcentration and regional change (from rustbelt to sunbelt in the U.S., but with similar phenomena increasingly world-wide) is analyzed in a framework that emphasizes heterogeneous human preferences. The focus is on the important interactions that exist between local and regional amenities, whether exogenous or endogenous. The central thesis is that persistent exogenous amenity variation among regions provides an underlying pattern of regional growth and decline. However, inappropriate provision of local public goods in central cities is seen to lead both to non-optimally large levels of suburbanization and to rates of regional change that are also non-optimally large.
Accelerated Growth Plate Mineralization and Foreshortened Proximal Limb Bones in Fetuin-A Knockout Mice
Jong Seto, Bj?rn Busse, Himadri S. Gupta, Cora Sch?fer, Stefanie Krauss, John W. C. Dunlop, Admir Masic, Michael Kerschnitzki, Paul Zaslansky, Peter Boesecke, Philip Catalá-Lehnen, Thorsten Schinke, Peter Fratzl, Willi Jahnen-Dechent
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047338
Abstract: The plasma protein fetuin-A/alpha2-HS-glycoprotein (genetic symbol Ahsg) is a systemic inhibitor of extraskeletal mineralization, which is best underscored by the excessive mineral deposition found in various tissues of fetuin-A deficient mice on the calcification-prone genetic background DBA/2. Fetuin-A is known to accumulate in the bone matrix thus an effect of fetuin-A on skeletal mineralization is expected. We examined the bones of fetuin-A deficient mice maintained on a C57BL/6 genetic background to avoid bone disease secondary to renal calcification. Here, we show that fetuin-A deficient mice display normal trabecular bone mass in the spine, but increased cortical thickness in the femur. Bone material properties, as well as mineral and collagen characteristics of cortical bone were unaffected by the absence of fetuin-A. In contrast, the long bones especially proximal limb bones were severely stunted in fetuin-A deficient mice compared to wildtype littermates, resulting in increased biomechanical stability of fetuin-A deficient femora in three-point-bending tests. Elevated backscattered electron signal intensities reflected an increased mineral content in the growth plates of fetuin-A deficient long bones, corroborating its physiological role as an inhibitor of excessive mineralization in the growth plate cartilage matrix - a site of vigorous physiological mineralization. We show that in the case of fetuin-A deficiency, active mineralization inhibition is a necessity for proper long bone growth.
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