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Showing papers by "Technical University of Denmark published in 2010"


Journal ArticleDOI
TL;DR: Biofilms can be prevented by early aggressive antibiotic prophylaxis or therapy and they can be treated by chronic suppressive therapy and a promising strategy may be the use of enzymes that can dissolve the biofilm matrix as well as quorum-sensing inhibitors that increase biofilm susceptibility to antibiotics.

2,637 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocells.
Abstract: Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject of continuing research and are commercially interesting in terms of new products from the pulp and paper industry and the agricultural sector. Cellulose nanofibers can be extracted from various plant sources and, although the mechanical separation of plant fibers into smaller elementary constituents has typically required high energy input, chemical and/or enzymatic fiber pre-treatments have been developed to overcome this problem. A challenge associated with using nanocellulose in composites is the lack of compatibility with hydrophobic polymers and various chemical modification methods have been explored in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose.

2,546 citations


Journal ArticleDOI
TL;DR: Density functional theory calculations explain copper's unique ability to convert CO2 into hydrocarbons, which may open up (photo-)electrochemical routes to fuels as mentioned in this paper, which may lead to new energy sources.
Abstract: Density functional theory calculations explain copper's unique ability to convert CO2 into hydrocarbons, which may open up (photo-)electrochemical routes to fuels.

2,420 citations


Journal ArticleDOI
TL;DR: An online tool to draw survival plots, which can be used to assess the relevance of the expression levels of various genes on the clinical outcome both in untreated and treated breast cancer patients, and which validated the capability of microarrays to determine estrogen receptor status in 1,231 patients.
Abstract: Validating prognostic or predictive candidate genes in appropriately powered breast cancer cohorts are of utmost interest. Our aim was to develop an online tool to draw survival plots, which can be used to assess the relevance of the expression levels of various genes on the clinical outcome both in untreated and treated breast cancer patients. A background database was established using gene expression data and survival information of 1,809 patients downloaded from GEO (Affymetrix HGU133A and HGU133+2 microarrays). The median relapse free survival is 6.43 years, 968/1,231 patients are estrogen-receptor (ER) positive, and 190/1,369 are lymph-node positive. After quality control and normalization only probes present on both Affymetrix platforms were retained (n = 22,277). In order to analyze the prognostic value of a particular gene, the cohorts are divided into two groups according to the median (or upper/lower quartile) expression of the gene. The two groups can be compared in terms of relapse free survival, overall survival, and distant metastasis free survival. A survival curve is displayed, and the hazard ratio with 95% confidence intervals and logrank P value are calculated and displayed. Additionally, three subgroups of patients can be assessed: systematically untreated patients, endocrine-treated ER positive patients, and patients with a distribution of clinical characteristics representative of those seen in general clinical practice in the US. Web address: www.kmplot.com . We used this integrative data analysis tool to confirm the prognostic power of the proliferation-related genes TOP2A and TOP2B, MKI67, CCND2, CCND3, CCNDE2, as well as CDKN1A, and TK2. We also validated the capability of microarrays to determine estrogen receptor status in 1,231 patients. The tool is highly valuable for the preliminary assessment of biomarkers, especially for research groups with limited bioinformatic resources.

2,395 citations


Journal ArticleDOI
TL;DR: In this paper, a second version of the van der Waals density functional was proposed, employing a more accurate semilocal exchange functional and the use of a large N asymptote gradient correction in determining the vdW kernel.
Abstract: We propose a second version of the van der Waals density functional of Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)], employing a more accurate semilocal exchange functional and the use of a large-N asymptote gradient correction in determining the vdW kernel. The predicted binding energy, equilibrium separation, and potential-energy curve shape are close to those of accurate quantum chemical calculations on 22 duplexes. We anticipate the enabling of chemically accurate calculations in sparse materials of importance for condensed matter, surface, chemical, and biological physics.

2,218 citations


Journal ArticleDOI
TL;DR: This article presents the projector augmented-wave (PAW) method as implemented in the GPAW program package using a uniform real-space grid representation of the electronic wavefunctions and implements the two common formulations of TDDFT, namely the linear-response and the time propagation schemes.
Abstract: Electronic structure calculations have become an indispensable tool in many areas of materials science and quantum chemistry. Even though the Kohn-Sham formulation of the density-functional theory (DFT) simplifies the many-body problem significantly, one is still confronted with several numerical challenges. In this article we present the projector augmented-wave (PAW) method as implemented in the GPAW program package (https://wiki.fysik.dtu.dk/gpaw) using a uniform real-space grid representation of the electronic wavefunctions. Compared to more traditional plane wave or localized basis set approaches, real-space grids offer several advantages, most notably good computational scalability and systematic convergence properties. However, as a unique feature GPAW also facilitates a localized atomic-orbital basis set in addition to the grid. The efficient atomic basis set is complementary to the more accurate grid, and the possibility to seamlessly switch between the two representations provides great flexibility. While DFT allows one to study ground state properties, time-dependent density-functional theory (TDDFT) provides access to the excited states. We have implemented the two common formulations of TDDFT, namely the linear-response and the time propagation schemes. Electron transport calculations under finite-bias conditions can be performed with GPAW using non-equilibrium Green functions and the localized basis set. In addition to the basic features of the real-space PAW method, we also describe the implementation of selected exchange-correlation functionals, parallelization schemes, Delta SCF-method, x-ray absorption spectra, and maximally localized Wannier orbitals.

1,822 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a review of CO2, its synthetic reactions and their possible role in future CO2 mitigation schemes that have to match the scale of man-made CO2 in the atmosphere, which rapidly approaches 1 teraton.
Abstract: The increase in atmospheric carbon dioxide is linked to climate changes; hence there is an urgent need to reduce the accumulation of CO2 in the atmosphere. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers offers a way to mitigate the increasing CO2 buildup. This review covers six important CO2 transformations namely: chemical transformations, photochemical reductions, chemical and electrochemical reductions, biological conversions, reforming and inorganic transformations. Furthermore, the vast research area of carbon capture and storage is reviewed briefly. This review is intended as an introduction to CO2, its synthetic reactions and their possible role in future CO2 mitigation schemes that has to match the scale of man-made CO2 in the atmosphere, which rapidly approaches 1 teraton.

1,771 citations


Journal ArticleDOI
TL;DR: High-resolution mass spectrometry–based proteomics was applied to investigate the proteome and phosphoproteome of the human cell cycle on a global scale and quantified 6027 proteins and 20,443 unique phosphorylation sites and their dynamics, finding that nuclear proteins and proteins involved in regulating metabolic processes have high phosphorylated site occupancy in mitosis, suggesting that these proteins may be inactivated by phosphorylate in mitotic cells.
Abstract: Eukaryotic cells replicate by a complex series of evolutionarily conserved events that are tightly regulated at defined stages of the cell division cycle. Progression through this cycle involves a large number of dedicated protein complexes and signaling pathways, and deregulation of this process is implicated in tumorigenesis. We applied high-resolution mass spectrometry-based proteomics to investigate the proteome and phosphoproteome of the human cell cycle on a global scale and quantified 6027 proteins and 20,443 unique phosphorylation sites and their dynamics. Co-regulated proteins and phosphorylation sites were grouped according to their cell cycle kinetics and compared to publicly available messenger RNA microarray data. Most detected phosphorylation sites and more than 20% of all quantified proteins showed substantial regulation, mainly in mitotic cells. Kinase-motif analysis revealed global activation during S phase of the DNA damage response network, which was mediated by phosphorylation by ATM or ATR or DNA-dependent protein kinases. We determined site-specific stoichiometry of more than 5000 sites and found that most of the up-regulated sites phosphorylated by cyclin-dependent kinase 1 (CDK1) or CDK2 were almost fully phosphorylated in mitotic cells. In particular, nuclear proteins and proteins involved in regulating metabolic processes have high phosphorylation site occupancy in mitosis. This suggests that these proteins may be inactivated by phosphorylation in mitotic cells.

1,447 citations


Journal ArticleDOI
TL;DR: Implementation of a new toxicity testing paradigm firmly based on human biology by transitioning from current expensive and lengthy in vivo testing with qualitative endpoints to in vitro toxicity pathway assays on human cells or cell lines using robotic high-throughput screening with mechanistic quantitative parameters.
Abstract: With the release of the landmark report Toxicity Testing in the 21st Century: A Vision and a Strategy, the U.S. National Academy of Sciences, in 2007, precipitated a major change in the way toxicity testing is conducted. It envisions increased efficiency in toxicity testing and decreased animal usage by transitioning from current expensive and lengthy in vivo testing with qualitative endpoints to in vitro toxicity pathway assays on human cells or cell lines using robotic high-throughput screening with mechanistic quantitative parameters. Risk assessment in the exposed human population would focus on avoiding significant perturbations in these toxicity pathways. Computational systems biology models would be implemented to determine the dose-response models of perturbations of pathway function. Extrapolation of in vitro results to in vivo human blood and tissue concentrations would be based on pharmacokinetic models for the given exposure condition. This practice would enhance human relevance of test results, and would cover several test agents, compared to traditional toxicological testing strategies. As all the tools that are necessary to implement the vision are currently available or in an advanced stage of development, the key prerequisites to achieving this paradigm shift are a commitment to change in the scientific community, which could be facilitated by a broad discussion of the vision, and obtaining necessary resources to enhance current knowledge of pathway perturbations and pathway assays in humans and to implement computational systems biology models. Implementation of these strategies would result in a new toxicity testing paradigm firmly based on human biology.

1,398 citations


Journal ArticleDOI
TL;DR: A review of the published knowledge on the oxy-fuel process can be found in this paper, focusing particularly on the combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics.

1,042 citations


Journal ArticleDOI
TL;DR: The presented devices are thus competitive for consumer electronics but ill-suited for on-grid electricity production in their current form.
Abstract: Upscaling of the manufacture of polymer solar cells is detailed with emphasis on cost analysis and practical approach. The device modules were prepared using both slot-die coating and screen printing the active layers in the form of stripes that were serially connected. The stripe width was varied and the resultant performance analysed. Wider stripes give access to higher geometric fill factors and lower aperture loss while they also present larger sheet resistive losses. An optimum was found through preparation of serially connected stripes having widths of 9, 13 and 18 mm with nominal geometric fill factors (excluding bus bars) of 50, 67 and 75% respectively. In addition modules with lengths of 6, 10, 20, 22.5 and 25 cm were explored. The devices were prepared by full roll-to-roll solution processing in a web width of 305 mm and roll lengths of up to 200 m. The devices were encapsulated with a barrier material in a full roll-to-roll process using standard adhesives giving the devices excellent stability during storage and operation. The total area of processed polymer solar cell was around 60 m2 per run. The solar cells were characterised using a roll-to-roll system comprising a solar simulator and an IV-curve tracer. After characterisation the solar cell modules were cut into sheets using a sheeting machine and contacted using button contacts applied by crimping. Based on this a detailed cost analysis was made showing that it is possible to prepare complete and contacted polymer solar cell modules on this scale at an area cost of 89 € m−2 and an electricity cost of 8.1 € Wp−1. The cost analysis was separated into the manufacturing cost, materials cost and also the capital investment required for setting up a complete production plant on this scale. Even though the cost in € Wp−1 is comparable to the cost for electricity using existing technologies the levelized cost of electricity (LCOE) is expected to be significantly higher than the existing technologies due to the inferior operational lifetime. The presented devices are thus competitive for consumer electronics but ill-suited for on-grid electricity production in their current form.

Journal ArticleDOI
TL;DR: Wheat straw biorefinery could be the near-term solution for clean, efficient and economically-feasible production of bioethanol as well as high value-added products.

Journal ArticleDOI
TL;DR: Both theory and experimental data showed that unweighted least-squares fitting of a Gaussian squanders one-third of the available information, a popular formula for its precision exaggerates beyond Fisher's information limit, and weighted least-Squares may do worse, whereas maximum-likelihood fitting is practically optimal.
Abstract: We optimally localized isolated fluorescent beads and molecules imaged as diffraction-limited spots, determined the orientation of molecules and present reliable formulas for the precision of various localization methods. Both theory and experimental data showed that unweighted least-squares fitting of a Gaussian squanders one-third of the available information, a popular formula for its precision exaggerates beyond Fisher's information limit, and weighted least-squares may do worse, whereas maximum-likelihood fitting is practically optimal.

Book
29 Oct 2010
TL;DR: Industrial designers with a background in conventional (clocked) design to be able to understand asynchronous design sufficiently to assess what it has to offer and whether it might be advantageous in their next design task.
Abstract: Principles of Asynchronous Circuit Design - A Systems Perspective addresses the need for an introductory text on asynchronous circuit design. Part I is an 8-chapter tutorial which addresses the most important issues for the beginner, including how to think about asynchronous systems. Part II is a 4-chapter introduction to Balsa, a freely-available synthesis system for asynchronous circuits which will enable the reader to get hands-on experience of designing high-level asynchronous systems. Part III offers a number of examples of state-of-the-art asynchronous systems to illustrate what can be built using asynchronous techniques. The examples range from a complete commercial smart card chip to complex microprocessors. The objective in writing this book has been to enable industrial designers with a background in conventional (clocked) design to be able to understand asynchronous design sufficiently to assess what it has to offer and whether it might be advantageous in their next design task.

Journal ArticleDOI
30 Apr 2010-Science
TL;DR: A catalytic process for the direct formation of methyl lactate from common sugars by Lewis acidic zeotypes, such as Sn-Beta, catalyze the conversion of mono- and disaccharides that are dissolved in methanol tomethyl lactate at 160°C.
Abstract: Presently, very few compounds of commercial interest are directly accessible from carbohydrates by using nonfermentive approaches. We describe here a catalytic process for the direct formation of methyl lactate from common sugars. Lewis acidic zeotypes, such as Sn-Beta, catalyze the conversion of mono- and disaccharides that are dissolved in methanol to methyl lactate at 160 degrees C. With sucrose as the substrate, methyl lactate yield reaches 68%, and the heterogeneous catalyst can be easily recovered by filtration and reused multiple times after calcination without any substantial change in the product selectivity.

Journal ArticleDOI
TL;DR: The rapidly expanding field of polymer and organic solar cells is reviewed in the context of materials, processes and devices that significantly deviate from the standard approach which involves rigid glass substrates, indium-tinoxide electrodes, spincoated layers of conjugated polymer/fullerene mixtures and evaporated metal electrodes in a flat multilayer geometry as mentioned in this paper.
Abstract: The rapidly expanding field of polymer and organic solar cells is reviewed in the context of materials, processes and devices that significantly deviate from the standard approach which involves rigid glass substrates, indium-tin-oxide electrodes, spincoated layers of conjugated polymer/fullerene mixtures and evaporated metal electrodes in a flat multilayer geometry. It is likely that significant advances can be found by pursuing many of these novel ideas further and the purpose of this review is to highlight these reports and hopefully spark new interest in materials and methods that may be performing less than the current state-of-the-art in their present form but that may have the potential to outperform these pending a larger investment in effort.

Journal ArticleDOI
11 Feb 2010-Nature
TL;DR: This genome sequence of an ancient human obtained from ∼4,000-year-old permafrost-preserved hair provides evidence for a migration from Siberia into the New World some 5,500 years ago, independent of that giving rise to the modern Native Americans and Inuit.
Abstract: We report here the genome sequence of an ancient human. Obtained from approximately 4,000-year-old permafrost-preserved hair, the genome represents a male individual from the first known culture to settle in Greenland. Sequenced to an average depth of 20x, we recover 79% of the diploid genome, an amount close to the practical limit of current sequencing technologies. We identify 353,151 high-confidence single-nucleotide polymorphisms (SNPs), of which 6.8% have not been reported previously. We estimate raw read contamination to be no higher than 0.8%. We use functional SNP assessment to assign possible phenotypic characteristics of the individual that belonged to a culture whose location has yielded only trace human remains. We compare the high-confidence SNPs to those of contemporary populations to find the populations most closely related to the individual. This provides evidence for a migration from Siberia into the New World some 5,500 years ago, independent of that giving rise to the modern Native Americans and Inuit.

Journal ArticleDOI
TL;DR: A genome-wide meta-analysis of gene sets (groups of genes that encode the same biological pathway or process) in 410 samples from patients with symptomatic Parkinson’s and subclinical disease and healthy controls identified 10 gene sets that were all associated with PD.
Abstract: Parkinson’s disease affects 5 million people worldwide, but the molecular mechanisms underlying its pathogenesis are still unclear. Here, we report a genome-wide meta-analysis of gene sets (groups of genes that encode the same biological pathway or process) in 410 samples from patients with symptomatic Parkinson’s and subclinical disease and healthy controls. We analyzed 6.8 million raw data points from nine genome-wide expression studies, and 185 laser-captured human dopaminergic neuron and substantia nigra transcriptomes, followed by two-stage replication on three platforms. We found 10 gene sets with previously unknown associations with Parkinson’s disease. These gene sets pinpoint defects in mitochondrial electron transport, glucose utilization, and glucose sensing and reveal that they occur early in disease pathogenesis. Genes controlling cellular bioenergetics that are expressed in response to peroxisome proliferator–activated receptor γ coactivator-1α (PGC-1α) are underexpressed in Parkinson’s disease patients. Activation of PGC-1α results in increased expression of nuclear-encoded subunits of the mitochondrial respiratory chain and blocks the dopaminergic neuron loss induced by mutant α-synuclein or the pesticide rotenone in cellular disease models. Our systems biology analysis of Parkinson’s disease identifies PGC-1α as a potential therapeutic target for early intervention.

Journal ArticleDOI
TL;DR: In this paper, the improvement of the performance of roll-to-roll processed polymer solar cell modules through miniaturization of the device outline is described, and the solar cell module was used to charge a polymer lithium ion battery through a blocking diode.
Abstract: The improvement of the performance of roll-to-roll processed polymer solar cell modules through miniaturization of the device outline is described. The devices were prepared using full roll-to-roll processing comprising flexographic printing, slot-die coating and rotary screen printing to create 5 mm wide lines of ZnO, P3HT:[60/70]PCBM, PEDOT:PSS and silver on an ITO-PET substrate. The lines were spaced by 1 mm and the devices were completed by encapsulation using roll-to-roll lamination on both sides using a pressure sensitive adhesive and a multilayered barrier material having a UV-filter with a cut-off at 390 nm, oxygen and water vapor transmission rates of respectively 0.01 cm3 m−2 bar−1 day−1 and 0.04 g m−2 day−1. The final modules comprised 16 serially connected cells. The technical yield was 89% based on the criterion that the Voc had to be larger than 7.2 V. This set of modules gave respectively a voltage, current, fill factor and power conversion efficiency of 8.47 ± 0.41 V, −23.20 ± 4.10 mA, 35.4 ± 2.8% and 1.96 ± 0.34% in the case of modules based on P3HT:[60]PCBM. A total of 1960 modules were prepared for each run and the best power conversion reached was 2.75% for devices based on P3HT:[70]PCBM. The solar cell modules were used to demonstrate the complete manufacture of a small lamp entirely using techniques of flexible electronics. The solar cell module was used to charge a polymer lithium ion battery through a blocking diode. The entire process was fully automated and demonstrates the capacity of polymer solar cells in the context of flexible and printed electronics. Finally a comparison was made between the learning curve for OPV and crystalline silicon solar cells in terms of the cost per watt peak and the cumulative watt peak. OPV as a technology was found to have a significantly steeper learning curve.

Journal ArticleDOI
TL;DR: It was found that the reactions taking place at the interface between the active layer and the PEDOT:PSS were the major cause of device failure in the case of these inverted devices, which are compatible with full roll-to-roll (R2R) coating and industrial manufacture.
Abstract: The spatial distribution of reaction products in multilayer polymer solar cells induced by water and oxygen atmospheres was mapped and used to elucidate the degradation patterns and failure mechani...

Journal ArticleDOI
TL;DR: This study aimed to narrow the gap in knowledge by providing a large scale dataset of over 17,000 HLA-peptide binding affinities for a set of 11 HLA DP and DQ alleles and found that prediction methodologies developed for HLA DR molecules perform equally well for DP or DQ molecules.
Abstract: MHC class II binding predictions are widely used to identify epitope candidates in infectious agents, allergens, cancer and autoantigens. The vast majority of prediction algorithms for human MHC class II to date have targeted HLA molecules encoded in the DR locus. This reflects a significant gap in knowledge as HLA DP and DQ molecules are presumably equally important, and have only been studied less because they are more difficult to handle experimentally. In this study, we aimed to narrow this gap by providing a large scale dataset of over 17,000 HLA-peptide binding affinities for a set of 11 HLA DP and DQ alleles. We also expanded our dataset for HLA DR alleles resulting in a total of 40,000 MHC class II binding affinities covering 26 allelic variants. Utilizing this dataset, we generated prediction tools utilizing several machine learning algorithms and evaluated their performance. We found that 1) prediction methodologies developed for HLA DR molecules perform equally well for DP or DQ molecules. 2) Prediction performances were significantly increased compared to previous reports due to the larger amounts of training data available. 3) The presence of homologous peptides between training and testing datasets should be avoided to give real-world estimates of prediction performance metrics, but the relative ranking of different predictors is largely unaffected by the presence of homologous peptides, and predictors intended for end-user applications should include all training data for maximum performance. 4) The recently developed NN-align prediction method significantly outperformed all other algorithms, including a naive consensus based on all prediction methods. A new consensus method dropping the comparably weak ARB prediction method could outperform the NN-align method, but further research into how to best combine MHC class II binding predictions is required.

Journal ArticleDOI
21 Jan 2010-Nature
TL;DR: A ‘stimulated slip’ model is developed to explain the strong size dependence of deformation twinning in crystals, and the sample size in transition is relatively large and easily accessible in experiments, making the understanding of size dependence relevant for applications.
Abstract: Deformation twinning(1-6) in crystals is a highly coherent inelastic shearing process that controls the mechanical behaviour of many materials, but its origin and spatio-temporal features are shrouded in mystery. Using micro-compression and in situ nano-compression experiments, here we find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal(7,8), until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium's ideal strength(9,10). We develop a 'stimulated slip' model to explain the strong size dependence of deformation twinning. The sample size in transition is relatively large and easily accessible in experiments, making our understanding of size dependence(11-17) relevant for applications.


Book
13 Dec 2010
TL;DR: In this paper, the authors present the solution of plasticity problems in rigid-plastic materials, including reinforced concrete structures, using the Elastic Theory of Plasticity (ELT).
Abstract: Introduction The Theory of Plasticity Constitutive Equations Extremum Principles for Rigid-Plastic Materials The Solution of Plasticity Problems Reinforced Concrete Structures Yield Conditions Concrete Yield Conditions for Reinforced Disks Yield Conditions for Slabs Reinforcement Design The Theory of Plain Concrete Statical Conditions Geometrical Conditions Virtual Work Constitutive Equations The Theory of Plane Strain for Coulomb Materials Applications Disks Statical Conditions Geometrical Conditions Virtual Work Constitutive Equations Exact Solutions for Isotropic Disks The Effective Compressive Strength of Reinforced Disks General Theory of Lower Bound Solutions Strut and Tie Models Shear Walls Homogenous Reinforcement Solutions Design According to the Elastic Theory Beams Beams in Bending Beams in Shear Beams in Torsion Combined Bending, Shear, and Torsion Slabs Statical Conditions Geometrical Conditions Virtual Work, Boundary Conditions Constitutive Equations Exact Solutions for Isotropic Slabs Upper Bound Solutions for Isotropic Slabs Lower Bound Solutions Orthotropic Slabs Analytical Optimum Reinforcement Solutions Numerical Methods Membrane Action Punching Shear of Slabs Introduction Internal Loads or Columns Edge and Corner Loads Concluding Remarks Shear in Joints Introduction Analysis of Joints by Plastic Theory Strength of Different Types of Joints The Bond Strength of Reinforcing Bars Introduction The Local Failure Mechanism Failure Mechanisms Analysis of Failure Mechanisms Assessment of Anchor and Splice Strength Effect of Transverse Pressure and Support Reaction Effect of Transverse Reinforcement Concluding Remarks

Journal ArticleDOI
TL;DR: The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group of Enterobacteriaceae.
Abstract: Escherichia coli is an important component of the biosphere and is an ideal model for studies of processes involved in bacterial genome evolution. Sixty-one publically available E. coli and Shigella spp. sequenced genomes are compared, using basic methods to produce phylogenetic and proteomics trees, and to identify the pan- and core genomes of this set of sequenced strains. A hierarchical clustering of variable genes allowed clear separation of the strains into clusters, including known pathotypes; clinically relevant serotypes can also be resolved in this way. In contrast, when in silico MLST was performed, many of the various strains appear jumbled and less well resolved. The predicted pan-genome comprises 15,741 gene families, and only 993 (6%) of the families are represented in every genome, comprising the core genome. The variable or ‘accessory’ genes thus make up more than 90% of the pan-genome and about 80% of a typical genome; some of these variable genes tend to be co-localized on genomic islands. The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group of Enterobacteriaceae.

Journal ArticleDOI
TL;DR: In this paper, the authors analyse observations from an extensive network of flux towers in Europe that reveal a difference between the temporal responses of forest and grassland ecosystems during heatwaves and conclude that the conservative water use of forest contributes to increased temperatures in the short term, but mitigates the impact of the most extreme heat and/or long-lasting events.
Abstract: Recent European heatwaves have raised interest in the impact of land cover conditions on temperature extremes. At present, it is believed that such extremes are enhanced by stronger surface heating of the atmosphere, when soil moisture content is below average. However, the impact of land cover on the exchange of water and energy and the interaction of this exchange with the soil water balance during heatwaves is largely unknown. Here we analyse observations from an extensive network of flux towers in Europe that reveal a difference between the temporal responses of forest and grassland ecosystems during heatwaves. We find that initially, surface heating is twice as high over forest than over grassland. Over grass, heating is suppressed by increased evaporation in response to increased solar radiation and temperature. Ultimately, however, this process accelerates soil moisture depletion and induces a critical shift in the regional climate system that leads to increased heating. We propose that this mechanism may explain the extreme temperatures in August 2003. We conclude that the conservative water use of forest contributes to increased temperatures in the short term, but mitigates the impact of the most extreme heat and/or long-lasting events.

Book ChapterDOI
01 Jan 2010
TL;DR: An overview of very large scale neighborhood search methods is given and recent variants and extensions like variable depth search and adaptive large neighborhood search are discussed.
Abstract: Heuristics based on large neighborhood search have recently shown outstanding results in solving various transportation and scheduling problems. Large neighborhood search methods explore a complex neighborhood by use of heuristics. Using large neighborhoods makes it possible to find better candidate solutions in each iteration and hence traverse a more promising search path. Starting from the large neighborhood search method, we give an overview of very large scale neighborhood search methods and discuss recent variants and extensions like variable depth search and adaptive large neighborhood search.

Journal ArticleDOI
TL;DR: In this article, a semi-transparent flexible polymer solar cells were manufactured in a full roll-to-roll process under ambient conditions and encapsulation was printed onto the back side of the polymer solar cell module followed by sheeting and application of discrete components and vias.
Abstract: Semitransparent flexible polymer solar cells were manufactured in a full roll-to-roll process under ambient conditions. After encapsulation a silver based circuit was printed onto the back side of the polymer solar cell module followed by sheeting and application of discrete components and vias. The discrete components were white light LEDs, a blocking diode, a lithium ion battery, vias and button contacts in two adjacent corners. The completed lamp has outside dimensions of 22.5 × 30.5 cm, a weight of 50 g and a very flat outline. The battery and components were the thickest elements and measured < 1 mm. A hole with a ring was punched in one corner to enable mechanical fixation or tying. The lamp has two states. In the charging state it has a completely flat outline and will charge the battery when illuminated from either side while the front side illumination is preferable. When used as a lamp two adjacent corners are joined via button contacts whereby the device can stand on a horizontal surface and the circuit is closed such that the battery discharges through the LEDs that illuminate the surface in front of the lamp. Several different lamps were prepared using the same solar cell and circuitry while varying the amount of white LEDs employed and by variation of the number of batteries and the individual battery capacity. The lamp prototype was developed through two early prototypes and the final and serially produced prototype was subjected to field tests in Zambia. Some of the lamps were recovered and the experiences gained with the prototype are presented allowing for further development that takes systemic factors such as the immediate response and spontaneous handling of the lamp by someone with no prior knowledge of the lamp or its workings.

Journal ArticleDOI
TL;DR: In this article, the authors study the oxygen reduction reaction (ORR) mechanism on a Pt(1 1/1/1) surface using density functional theory calculations and find that at low overpotentials the surface is covered with a half dissociated water layer.

Journal ArticleDOI
TL;DR: This paper reviews quantitative operations management approaches to food distribution management, and relates this to challenges faced by the industry, with main focus on three aspects: food quality, food safety, and sustainability.
Abstract: The management of food distribution networks is receiving more and more attention, both in practice and in the scientific literature. In this paper, we review quantitative operations management approaches to food distribution management, and relate this to challenges faced by the industry. Here, our main focus is on three aspects: food quality, food safety, and sustainability. We discuss the literature on three decision levels: strategic network design, tactical network planning, and operational transportation planning. For each of these, we survey the research contributions, discuss the state of the art, and identify challenges for future research.