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Showing papers by "University of Bremen published in 2014"


Journal ArticleDOI
TL;DR: In this article, first-principles calculations of the adsorption of CO, CO2, NH3, NO, and NO2 gas molecules on a monolayer phosphorene were performed.
Abstract: Recent reports on the fabrication of phosphorene, that is, mono- or few-layer black phosphorus, have raised exciting prospects of an outstanding two-dimensional (2D) material that exhibits excellent properties for nanodevice applications. Here, we study by first-principles calculations the adsorption of CO, CO2, NH3, NO, and NO2 gas molecules on a monolayer phosphorene. Our results predict superior sensing performance of phosphorene that rivals or even surpasses that of other 2D materials such as graphene and MoS2. We determine the optimal adsorption positions of these molecules on the phosphorene and identify molecular doping, that is, charge transfer between the molecules and phosphorene, as the driving mechanism for the high adsorption strength. We further calculated the current-voltage (I-V) relation using the nonequilibrium Green's function (NEGF) formalism. The transport features show large (1-2 orders of magnitude) anisotropy along different (armchair or zigzag) directions, which is consistent with the anisotropic electronic band structure of phosphorene. Remarkably, the I-V relation exhibits distinct responses with a marked change of the I-V relation along either the armchair or the zigzag directions depending on the type of molecules. Such selectivity and sensitivity to adsorption makes phosphorene a superior gas sensor that promises wide-ranging applications.

846 citations


Journal ArticleDOI
TL;DR: In this article, the authors derived an analytical formula for the shadow of a Kerr-Newman-NUT-anti-de Sitter black hole for an observer at given Boyer-Lindquist coordinates in the domain of outer communication.
Abstract: We consider the Pleba\ifmmode \acute{n}\else \'{n}\fi{}ski class of electrovacuum solutions to the Einstein equations with a cosmological constant. These space-times, which are also known as the Kerr-Newman-NUT--(anti--)de Sitter space-times, are characterized by a mass $m$, a spin $a$, a parameter $\ensuremath{\beta}$ that comprises electric and magnetic charge, a NUT parameter $\ensuremath{\ell}$ and a cosmological constant $\mathrm{\ensuremath{\Lambda}}$. Based on a detailed discussion of the photon regions in these space-times (i.e., of the regions in which spherical lightlike geodesics exist), we derive an analytical formula for the shadow of a Kerr-Newman-NUT--(anti--)de Sitter black hole for an observer at given Boyer-Lindquist coordinates $({r}_{O},{\ensuremath{\vartheta}}_{O})$ in the domain of outer communication. We visualize the photon regions and the shadows for various values of the parameters.

368 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide biochemical evidence that thaumarchaeal ammonia oxidizers assimilate inorganic carbon via a modified version of the autotrophic hydroxypropionate/hydroxybutyrate cycle of Crenarchaeota, which is far more energy efficient than any other aerobic autoregressive pathway.
Abstract: Archaea of the phylum Thaumarchaeota are among the most abundant prokaryotes on Earth and are widely distributed in marine, terrestrial, and geothermal environments All studied Thaumarchaeota couple the oxidation of ammonia at extremely low concentrations with carbon fixation As the predominant nitrifiers in the ocean and in various soils, ammonia-oxidizing archaea contribute significantly to the global nitrogen and carbon cycles Here we provide biochemical evidence that thaumarchaeal ammonia oxidizers assimilate inorganic carbon via a modified version of the autotrophic hydroxypropionate/hydroxybutyrate cycle of Crenarchaeota that is far more energy efficient than any other aerobic autotrophic pathway The identified genes of this cycle were found in the genomes of all sequenced representatives of the phylum Thaumarchaeota, indicating the environmental significance of this efficient CO2-fixation pathway Comparative phylogenetic analysis of proteins of this pathway suggests that the hydroxypropionate/hydroxybutyrate cycle emerged independently in Crenarchaeota and Thaumarchaeota, thus supporting the hypothesis of an early evolutionary separation of both archaeal phyla We conclude that high efficiency of anabolism exemplified by this autotrophic cycle perfectly suits the lifestyle of ammonia-oxidizing archaea, which thrive at a constantly low energy supply, thus offering a biochemical explanation for their ecological success in nutrient-limited environments

339 citations


Journal ArticleDOI
TL;DR: The biological functions of copper in the brain are summarized and the current knowledge on the mechanisms involved in copper transport, storage and export of brain cells are described.

339 citations


Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of ozone absorption cross-sections measured in a laboratory in the broad spectral range 213-1100 nm with a spectral resolution of 0.02-0.24 nm (full width at half maximum, FWHM) in the atmosphereherically relevant temperature range from 193 K to 293 K.
Abstract: . We report on the temperature dependence of ozone absorption cross-sections measured in our laboratory in the broad spectral range 213–1100 nm with a spectral resolution of 0.02–0.24 nm (full width at half maximum, FWHM) in the atmospherically relevant temperature range from 193 K to 293 K. The temperature dependence of ozone absorption cross-sections was established using measurements at eleven temperatures. This investigation is superior in terms of spectral range and number of considered temperatures compared to the previous studies. The methodology of the absolute broadband measurements, experimental procedures and spectra processing were described in our companion paper together with the associated uncertainty budget. In this paper, we report in detail on our data below room temperature and compare them with literature data using direct comparisons as well as the standard approach using a quadratic polynomial in temperature fitted to the cross-section data.

303 citations


21 May 2014
TL;DR: Given a fixed state description based on instantiated predicates, a general abstraction scheme is provided to automatically create admissible domain-independent memory-based heuristics for planning problems, where abstractions are found in factorizing the planning space.
Abstract: Heuristic search planning effectively finds solutions for large planning problems, but since the estimates are either not admissible or too weak, optimal solutions are found in rare cases only In contrast, heuristic pattern databases are known to significantly improve lower bound estimates for optimally solving challenging single-agent problems like the 24-Puzzle or Rubik’s Cube This paper studies the effect of pattern databases in the context of deterministic planning Given a fixed state description based on instantiated predicates, we provide a general abstraction scheme to automatically create admissible domain-independent memory-based heuristics for planning problems, where abstractions are found in factorizing the planning space We evaluate the impact of pattern database heuristics in A* and hill climbing algorithms for a collection of benchmark domains

299 citations


Journal ArticleDOI
TL;DR: In this article, a new approach uses both the concept of modular hierarchy for network construction and the methods of statistical inference to address this problem, succeeding where the existing approaches see difficulties, and characterizing and identifying modules is highly nontrivial and still an outstanding problem in networks research.
Abstract: Social, technological, and biological networks are known to organize into modules or ``communities.'' Characterizing and identifying modules is highly nontrivial and still an outstanding problem in networks research. A new approach uses both the concept of modular hierarchy for network construction and the methods of statistical inference to address this problem, succeeding where the existing approaches see difficulties.

284 citations


Journal ArticleDOI
TL;DR: There is a higher prevalence of obesity in populations from southern Europe and in population groups with lower education and income levels, which confirm the need to develop and reinforce European public health policies to prevent early obesity and to reduce these health inequalities and regional disparities.
Abstract: There is a lack of common surveillance systems providing comparable figures and temporal trends of the prevalence of overweight (OW), obesity and related risk factors among European preschool and school children. Comparability of available data is limited in terms of sampling design, methodological approaches and quality assurance. The IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS) study provides one of the largest European data sets of young children based on state-of-the-art methodology. To assess the European distribution of weight status according to different classification systems based on body mass index (BMI) in children (2.0–9.9 years). To describe the prevalence of weight categories by region, sex, age and socioeconomic position. Between 2007 and 2010, 18 745 children from eight European countries participated in an extensive, highly standardised protocol including, among other measures, anthropometric examinations and parental reports on socio-demographic characteristics. The combined prevalence of OW/obesity ranges from more than 40% in southern Europe to less than 10% in northern Europe. Overall, the prevalence of OW was higher in girls (21.1%) as compared with boys (18.6%). The prevalence of OW shows a negative gradient with social position, with some variation of the strength and consistency of this association across Europe. Overall, population groups with low income and/or lower education levels show the highest prevalence of obesity. The use of different reference systems to classify OW results in substantial differences in prevalence estimates and can even reverse the reported difference between boys and girls. There is a higher prevalence of obesity in populations from southern Europe and in population groups with lower education and income levels. Our data confirm the need to develop and reinforce European public health policies to prevent early obesity and to reduce these health inequalities and regional disparities.

283 citations


Journal ArticleDOI
TL;DR: The benefits that cloud computing offers for fifth-generation (5G) mobile networks are explored and the implications on the signal processing algorithms are investigated.
Abstract: Cloud computing draws significant attention in the information technology (IT) community as it provides ubiquitous on-demand access to a shared pool of configurable computing resources with minimum management effort. It gains also more impact on the communication technology (CT) community and is currently discussed as an enabler for flexible, cost-efficient and more powerful mobile network implementations. Although centralized baseband pools are already investigated for the radio access network (RAN) to allow for efficient resource usage and advanced multicell algorithms, these technologies still require dedicated hardware and do not offer the same characteristics as cloud-computing platforms, i.e., on-demand provisioning, virtualization, resource pooling, elasticity, service metering, and multitenancy. However, these properties of cloud computing are key enablers for future mobile communication systems characterized by an ultradense deployment of radio access points (RAPs) leading to severe multicell interference in combination with a significant increase of the number of access nodes and huge fluctuations of the rate requirements over time. In this article, we will explore the benefits that cloud computing offers for fifth-generation (5G) mobile networks and investigate the implications on the signal processing algorithms.

272 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence.

256 citations


Journal ArticleDOI
TL;DR: Study of the ground-state and finite-density optical response of molybdenum disulfide by solving the semiconductor Bloch equations, using ab initio band structures and Coulomb interaction matrix elements reveals a redshift of the excitonic ground- state absorption.
Abstract: We study the ground-state and finite-density optical response of molybdenum disulfide by solving the semiconductor Bloch equations, using ab initio band structures and Coulomb interaction matrix elements. Spectra for excited carrier densities up to 1013 cm–2 reveal a redshift of the excitonic ground-state absorption, whereas higher excitonic lines are found to disappear successively due to Coulomb-induced band gap shrinkage of more than 500 meV and binding-energy reduction. Strain-induced band variations lead to a redshift of the lowest exciton line by ∼110 meV/% and change the direct transition to indirect while maintaining the magnitude of the optical response.

Journal ArticleDOI
TL;DR: SCIATRAN as discussed by the authors is a comprehensive software package for the modeling of radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared including multiple scattering processes, polarization, thermal emission and ocean-atmosphere coupling.
Abstract: SCIATRAN is a comprehensive software package for the modeling of radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared ( 0.18 – 40 μ m ) including multiple scattering processes, polarization, thermal emission and ocean–atmosphere coupling. The software is capable of modeling spectral and angular distributions of the intensity or the Stokes vector of the transmitted, scattered, reflected, and emitted radiation assuming either a plane-parallel or a spherical atmosphere. Simulations are done either in the scalar or in the vector mode (i.e. accounting for the polarization) for observations by space-, air-, ship- and balloon-borne, ground-based, and underwater instruments in various viewing geometries (nadir, off-nadir, limb, occultation, zenith-sky, off-axis). All significant radiative transfer processes are accounted for. These are, e.g. the Rayleigh scattering, scattering by aerosol and cloud particles, absorption by gaseous components, and bidirectional reflection by an underlying surface including Fresnel reflection from a flat or roughened ocean surface. The software package contains several radiative transfer solvers including finite difference and discrete-ordinate techniques, an extensive database, and a specific module for solving inverse problems. In contrast to many other radiative transfer codes, SCIATRAN incorporates an efficient approach to calculate the so-called Jacobians, i.e. derivatives of the intensity with respect to various atmospheric and surface parameters. In this paper we discuss numerical methods used in SCIATRAN to solve the scalar and vector radiative transfer equation, describe databases of atmospheric, oceanic, and surface parameters incorporated in SCIATRAN, and demonstrate how to solve some selected radiative transfer problems using the SCIATRAN package. During the last decades, a lot of studies have been published demonstrating that SCIATRAN is a valuable tool for a wide range of remote sensing applications. Here, we present some selected comparisons of SCIATRAN simulations to published benchmark results, independent radiative transfer models, and various measurements from satellite, ground-based, and ship instruments. Methods for solving inverse problems related to remote sensing of the Earth's atmosphere using the SCIATRAN software are outside the scope of this study and will be discussed in a follow-up paper. The SCIATRAN software package along with a detailed User's Guide is freely available for non-commercial use via the webpage of the Institute of Environmental Physics (IUP), University of Bremen: http://www.iup.physik.uni-bremen.de/sciatran .

Journal ArticleDOI
TL;DR: A simplified quantum theoretical interpretation of DPC is presented, which enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors.
Abstract: By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

Journal ArticleDOI
17 Jan 2014-Science
TL;DR: Evidence is presented that hydrates play a role in the observed seepage of gas, but it is confirmed that seepages off Svalbard has been ongoing for at least 3000 years and that seasonal fluctuations of 1° to 2°C in the bottom-water temperature cause periodic gas hydrate formation and dissociation, which focus seeping at the observed sites.
Abstract: Methane hydrate is an icelike substance that is stable at high pressure and low temperature in continental margin sediments. Since the discovery of a large number of gas flares at the landward termination of the gas hydrate stability zone off Svalbard, there has been concern that warming bottom waters have started to dissociate large amounts of gas hydrate and that the resulting methane release may possibly accelerate global warming. Here, we corroborate that hydrates play a role in the observed seepage of gas, but we present evidence that seepage off Svalbard has been ongoing for at least 3000 years and that seasonal fluctuations of 1° to 2°C in the bottom-water temperature cause periodic gas hydrate formation and dissociation, which focus seepage at the observed sites.

Journal ArticleDOI
23 May 2014-Science
TL;DR: An artificial neural network trained with 199 sulfate profiles is developed, constrained with geomorphological and geochemical maps to estimate global sulfate-reduction rate distributions, showing how deeply sulfates penetrate marine sediments worldwide and how quickly that sulfate is chemically reduced by microbes in the sub–sea-floor.
Abstract: Sulfate reduction is a globally important yet poorly quantified redox process in marine sediments. We developed an artificial neural network trained with 199 sulfate profiles, constrained with geomorphological and geochemical maps to estimate global sulfate reduction rate distributions. Globally, 11.3 Tmol sulfate are reduced yearly, ~15% of previous estimates, accounting for the oxidation of 12-29% of the organic carbon flux to the sea floor. Combined with global cell distributions in marine sediments, these results indicate a strong contrast in sub–sea-floor prokaryote habitats: in continental margins global cell numbers in sulfate-depleted sediment exceed those in the overlying sulfate-bearing sediment by an order of magnitude, whereas in the abyss most life occurs in oxic and/or sulfate-reducing sediments.

Journal ArticleDOI
TL;DR: In this paper, the authors assess the link between dimensions of agile supply chain, competitive objectives and business performance in the UK North Sea upstream oil and gas industry and identify the most important dimensions and attributes of supply chain agility.

Journal ArticleDOI
TL;DR: An efficient algorithm for the inference of stochastic block models in large networks, capable of delivering results which are indistinguishable from the more exact and numerically expensive MCMC method in many artificial and empirical networks, despite being much faster.
Abstract: We present an efficient algorithm for the inference of stochastic block models in large networks. The algorithm can be used as an optimized Markov chain Monte Carlo (MCMC) method, with a fast mixing time and a much reduced susceptibility to getting trapped in metastable states, or as a greedy agglomerative heuristic, with an almost linear O(Nln2N) complexity, where N is the number of nodes in the network, independent of the number of blocks being inferred. We show that the heuristic is capable of delivering results which are indistinguishable from the more exact and numerically expensive MCMC method in many artificial and empirical networks, despite being much faster. The method is entirely unbiased towards any specific mixing pattern, and in particular it does not favor assortative community structures.

Journal ArticleDOI
TL;DR: In this paper, a study of psychischen Auffalligkeiten bei Kindern und Jugendlichen is presented, i.e., the negative effects of psychophysics on children and adolescents, in the context of the KiGGS Welle 1 (Erhebungszeitraum 2009-2012).
Abstract: Psychische Auffalligkeiten bei Kindern und Jugendlichen belasten die Betroffenen, die Familie und das soziale Umfeld und besitzen eine hohe Public-Health-Relevanz. Mit der Studie KiGGS Welle 1 (Erhebungszeitraum 2009–2012) liegen Daten zu psychischen Auffalligkeiten im Kindes- und Jugendalter vor, die es ermoglichen, sowohl aktuelle Pravalenzen als auch Trends mit Bezug auf die KiGGS-Basiserhebung (2003–2006) uber einen 6-Jahres-Zeitraum zu berichten. Das Screening psychischer Auffalligkeiten in KiGGS Welle 1 erfolgte mit dem Symptomfragebogen des Strengths and Difficulties Questionnaire (SDQ) bei 10.353 Sorgeberechtigten im telefonischen Interview. In KiGGS Welle 1 wurde zusatzlich auch der SDQ-Impactfragebogen eingesetzt. Insgesamt 20,2 % (95 %-KI: 18,9–21,6 %) der Kinder und Jugendlichen im Alter von 3 bis 17 Jahren liesen sich in der KiGGS Welle 1 mit dem SDQ-Symptomfragebogen einer Risikogruppe fur psychische Auffalligkeiten (grenzwertig auffallig oder auffallig im SDQ-Gesamtproblemwert, deutsche Normierung) zuordnen: In der KiGGS-Basiserhebung waren dies 20,0 % (19,1–20,9 %; altersstandardisiert auf die Bevolkerung zum 31.12.2010, deutsche Normierung). Damit lies sich insgesamt keine bedeutsame Veranderung uber die Zeit in der Haufigkeit psychischer Auffalligkeiten nachweisen. Auch in der Stratifizierung nach Geschlecht, Altersgruppen und Sozialstatus zeigten sich in Bezug auf die Risikogruppe keine statistisch signifikanten Pravalenzunterschiede zwischen der KiGGS-Basiserhebung und KiGGS Welle 1. Der statistische Vergleich der Skalenmittelwerte zeigte sowohl bei Madchen als auch bei Jungen hohere Werte bezuglich der Subskalen fur emotionale Probleme, Verhaltensprobleme und prosoziales Verhalten sowie geringere Mittelwerte fur die Subskala Peer-Probleme in KiGGS Welle 1. Die zum Teil gering ausgepragten Veranderungen uber die Zeit konnten jedoch auf Modeeffekte (schriftliche Befragung in der KiGGS-Basiserhebung vs. Telefoninterview in der KiGGS Welle 1) zuruckzufuhren sein. Die Subskala Hyperaktivitat blieb uber beide Messzeitraume unverandert. In Bezug auf Beeintrachtigung infolge psychischer Probleme, erhoben mit dem SDQ-Impactfragebogen, ergaben sich fur den Impactscore sowie fur Chronizitat und familiare Belastungen mehr und langer andauernde Beeintrachtigungen bei Jungen. Die anhaltend hohe Pravalenz und das gleichbleibend hohe Ausmas von emotionalen und verhaltensbedingten Auffalligkeiten sollten Anlass zu vermehrten praventiven Anstrengungen geben.

Book
22 May 2014
TL;DR: Text- image Relations in Perspective and Empirical Methods Multimodal Cohesion and Text-Image Relations and Pragmatics, which describes the relationships between text and image, are presented.
Abstract: Text and image are used together in an increasingly flexible fashion and many disciplines and areas of study are now attempting to understand how these combinations work.This introductory textbook explores and analyses the various approaches to multimodality and offers a broad, interdisciplinary survey of all aspects of the text-image relation. It leads students into detailed discussion concerning a number of approaches that are used. It also brings out their strengths and weaknesses using illustrative example analyses and raises explicit research questions to reinforce learning. Throughout the book, John Bateman looks at a wide range of perspectives: socio-semiotics, visual communication, psycholinguistic approaches to discourse, rhetorical approaches to advertising and visual persuasion, and cognitive metaphor theory. Applications of the styles of analyses presented are discussed for a variety of materials, including advertisements, picture books, comics and textbooks. Requiring no prior knowledge of the area, this is an accessible text for all students studying text and image or multimodality within English Language and Linguistics, Media and Communication Studies, Visual and Design Studies.

Journal ArticleDOI
TL;DR: The metabolic syndrome score shows a positive trend with age, particularly regarding the upper percentiles of the score, and a new definition is proposed that should improve clinical guidance and serve as a useful tool in pediatric obesity research.
Abstract: To estimate the prevalence of the metabolic syndrome (MetS) using reference standards obtained in European children and to develop a quantitative MetS score and describe its distribution in children. Population-based survey in eight European countries, including 18745 children 2.0 to 10.9 years, recruited during a second survey. Anthropometry (weight, height and waist circumference), blood pressure and serum-fasting triglycerides, HDL cholesterol, glucose and insulin were measured. We applied three widely accepted definitions of the pediatric MetS and we suggest a new definition, to guide pediatricians in decisions about close monitoring or even intervention (values of at least three of the MetS components exceeding the 90th or 95th percentile, respectively). We used a z-score standardisation to calculate a continuous score combining the MetS components. Among the various definitions of MetS, the highest prevalence (5.5%) was obtained with our new definition requiring close observation (monitoring level). Our more conservative definition, requiring pediatric intervention gives a prevalence of 1.8%. In general, prevalences were higher in girls than in boys. The prevalence of metabolic syndrome is highest among obese children. All definitions classify a small percentage of thin or normal weight children as being affected. The metabolic syndrome score shows a positive trend with age, particularly regarding the upper percentiles of the score. According to different definitions of pediatric MetS, a non-negligible proportion of mostly prepubertal children are classified as affected. We propose a new definition of MetS that should improve clinical guidance. The continuous score developed may also serve as a useful tool in pediatric obesity research. It has to be noted, however, that the proposed cutoffs are based on a statistical definition that does not yet allow to quantify the risk of subsequent disease.

Journal ArticleDOI
TL;DR: In this article, the authors identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade, and conclude that substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region.
Abstract: A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires transformational advances from the existing sparse, exploratory framework towards a dense, robust, and sustained system in all components: anthropogenic emissions, the atmosphere, the ocean, and the terrestrial biosphere. The paper is addressed to scientists, policymakers, and funding agencies who need to have a global picture of the current state of the (diverse) carbon observations. We identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade. A key conclusion is the substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region. In order to establish flux and stock diagnostics over areas such as the southern oceans, tropical forests, and the Arctic, in situ observations will have to be complemented with remote-sensing measurements. Remote sensing offers the advantage of dense spatial coverage and frequent revisit. A key challenge is to bring remote-sensing measurements to a level of long-term consistency and accuracy so that they can be efficiently combined in models to reduce uncertainties, in synergy with ground-based data. Bringing tight observational constraints on fossil fuel and land use change emissions will be the biggest challenge for deployment of a policy-relevant integrated carbon observation system. This will require in situ and remotely sensed data at much higher resolution and density than currently achieved for natural fluxes, although over a small land area (cities, industrial sites, power plants), as well as the inclusion of fossil fuel CO2 proxy measurements such as radiocarbon in CO2 and carbon-fuel combustion tracers. Additionally, a policy-relevant carbon monitoring system should also provide mechanisms for reconciling regional top-down (atmosphere-based) and bottom-up (surface-based) flux estimates across the range of spatial and temporal scales relevant to mitigation policies. In addition, uncertainties for each observation data-stream should be assessed. The success of the system will rely on long-term commitments to monitoring, on improved international collaboration to fill gaps in the current observations, on sustained efforts to improve access to the different data streams and make databases interoperable, and on the calibration of each component of the system to agreed-upon international scales.

Journal ArticleDOI
01 May 2014-Nature
TL;DR: It is shown that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean.
Abstract: The response of the tropical climate in the Indian Ocean realm to abrupt climate change events in the North Atlantic Ocean is contentious. Repositioning of the intertropical convergence zone is thought to have been responsible for changes in tropical hydroclimate during North Atlantic cold spells, but the dearth of high-resolution records outside the monsoon realm in the Indian Ocean precludes a full understanding of this remote relationship and its underlying mechanisms. Here we show that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean. Our results are based on new, high-resolution sea surface temperature and seawater oxygen isotope records of well-dated sedimentary archives from the tropical eastern Indian Ocean for the past 45,000 years, combined with climate model simulations of Atlantic circulation slowdown under Marine Isotope Stages 2 and 3 boundary conditions. Similar conditions in the east and west of the basin rule out a zonal dipole structure as the dominant forcing of the tropical Indian Ocean hydroclimate of millennial-scale events. Results from our simulations and proxy data suggest dry conditions in the northern Indian Ocean realm and wet and warm conditions in the southern realm during North Atlantic cold spells.

Journal ArticleDOI
TL;DR: This Theme Issue focuses on technologies, models and applications to monitor changes in the product shelf life, defined as the time remaining until the quality of a food product drops below an acceptance limit, to uncover and prevent invisible or latent losses in product quality.
Abstract: The need to feed an ever-increasing world population makes it obligatory to reduce the millions of tons of avoidable perishable waste along the food supply chain. A considerable share of these losses is caused by non-optimal cold chain processes and management. This Theme Issue focuses on technologies, models and applications to monitor changes in the product shelf life, defined as the time remaining until the quality of a food product drops below an acceptance limit, and to plan successive chain processes and logistics accordingly to uncover and prevent invisible or latent losses in product quality, especially following the first-expired-first-out strategy for optimized matching between the remaining shelf life and the expected transport duration. This introductory article summarizes the key findings of this Theme Issue, which brings together research study results from around the world to promote intelligent food logistics. The articles include three case studies on the cold chain for berries, bananas and meat and an overview of different post-harvest treatments. Further contributions focus on the required technical solutions, such as the wireless sensor and communication system for remote quality supervision, gas sensors to detect ethylene as an indicator of unwanted ripening and volatile components to indicate mould infections. The final section of this introduction discusses how improvements in food quality can be targeted by strategic changes in the food chain.

Journal ArticleDOI
TL;DR: In this paper, video data recorded in the heads of French Mediterranean canyons was used to identify the species, fishing impacts and litter recognized in the video films recorded from 180 to 700m depth.
Abstract: Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rhone). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic impacts show that seafloor disturbance by benthic fishing is mainly attributable to trawling in the Gulf of Lion and to long lines where rocky substrates are present. The bauxite residue (red mud) expelled in the Cassidaigne canyon was seen to prevent fauna from settling at the bottom of the canyon and it covered much of the flanks. Litter was present in all of the canyons and especially in considerable quantities in the Ligurian Sea, where the heads of the canyons are closer to the coast. Three Marine Protected Areas and one fishing area with restricted access have recently been established and should permit the preservation of these deep ecosystems.


Journal ArticleDOI
01 Feb 2014-Geology
TL;DR: The mechanisms that control hydrogen generation and magnetite formation during serpentinization of mantle peridotite remain poorly understood as discussed by the authors, however, some completely serpentinized peridots have as much as 6.15 wt% magnetite, whereas others are nearly magnetite free.
Abstract: Serpentinization of mantle peridotite generates molecular hydrogen that can be exploited by microorganisms to gain metabolic energy; however, the mechanisms that control hydrogen generation and magnetite formation during serpentinization remain poorly understood. We have examined partly to completely serpentinized peridotites recovered during the Ocean Drilling Program and find a remarkable variation in the abundance of magnetite. Some completely serpentinized peridotites have as much as 6.15 wt% magnetite, whereas others are nearly magnetite free (

Journal ArticleDOI
Lawrence N. Hudson1, Tim Newbold2, Tim Newbold3, Sara Contu1  +270 moreInstitutions (167)
TL;DR: A new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world is described and assessed.
Abstract: Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species Existing global databases of species’ threat status or population time series are dominated by charismatic species The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines We describe and assess a new database of more than 16 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – wwwpredictsorguk) We make site-level summary data available alongside this article The full database will be publicly available in 2015

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TL;DR: In this paper, a comprehensive evaluation of state-of-the-art models against Last Glacial Maximum and mid-Holocene climates, using reconstructions of land and ocean climates and simulations from the Palaeoclimate Modelling and Coupled Modeling Intercomparison Projects, is presented.
Abstract: Past climates provide a test of models’ ability to predict climate change. We present a comprehensive evaluation of state-of-the-art models against Last Glacial Maximum and mid-Holocene climates, using reconstructions of land and ocean climates and simulations from the Palaeoclimate Modelling and Coupled Modelling Intercomparison Projects. Newer models do not perform better than earlier versions despite higher resolution and complexity. Differences in climate sensitivity only weakly account for differences in model performance. In the glacial, models consistently underestimate land cooling (especially in winter) and overestimate ocean surface cooling (especially in the tropics). In the mid-Holocene, models generally underestimate the precipitation increase in the northern monsoon regions, and overestimate summer warming in central Eurasia. Models generally capture large-scale gradients of climate change but have more limited ability to reproduce spatial patterns. Despite these common biases, some models perform better than others.

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TL;DR: In this article, the authors provide an overview of new knowledge on oxygen depletion (hypoxia) and related phenomena in aquatic systems resulting from the EU-FP7 project HYPOX (http://www.hypox.net).
Abstract: In this paper we provide an overview of new knowledge on oxygen depletion (hypoxia) and related phenomena in aquatic systems resulting from the EU-FP7 project HYPOX (“In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and landlocked water bodies”, www.hypox.net). In view of the anticipated oxygen loss in aquatic systems due to eutrophication and climate change, HYPOX was set up to improve capacities to monitor hypoxia as well as to understand its causes and consequences. Temporal dynamics and spatial patterns of hypoxia were analyzed in field studies in various aquatic environments, including the Baltic Sea, the Black Sea, Scottish and Scandinavian fjords, Ionian Sea lagoons and embayments, and Swiss lakes. Examples of episodic and rapid (hours) occurrences of hypoxia, as well as seasonal changes in bottom-water oxygenation in stratified systems, are discussed. Geologically driven hypoxia caused by gas seepage is demonstrated. Using novel technologies, temporal and spatial patterns of watercolumn oxygenation, from basin-scale seasonal patterns to meter-scale sub-micromolar oxygen distributions, were resolved. Existing multidecadal monitoring data were used to demonstrate the imprint of climate change and eutrophication on long-term oxygen distributions. Organic and inorganic proxies were used to extend investigations on past oxygen conditions to centennial and even longer timescales that cannot be resolved by monitoring. The effects of hypoxia on faunal communities and biogeochemical processes were also addressed in the project. An investigation of benthic fauna is presented as an example of hypoxia-devastated benthic communities that slowly recover upon a reduction in eutrophication in a system where naturally occurring hypoxia overlaps with anthropogenic hypoxia. Biogeochemical investigations reveal that oxygen intrusions have a strong effect on the microbially mediated redox cycling of elements. Observations and modeling studies of the sediments demonstrate the effect of seasonally changing oxygen conditions on benthic mineralization pathways and fluxes. Data quality and access are crucial in hypoxia research. Technical issues are therefore also addressed, including the availability of suitable sensor technology to resolve the gradual changes in bottom-water oxygen in marine systems that can be expected as a result of climate change. Using cabled observatories as examples, we show how the benefit of continuous oxygen monitoring can be maximized by adopting proper quality control. Finally, we discuss strategies for state-of-the-art data archiving and dissemination in compliance with global standards, and how ocean observations can contribute to global earth observation attempts.

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05 Jun 2014-ACS Nano
TL;DR: The experiments suggest that the antibacterial activity of nanodiamond is linked to the presence of partially oxidized and negatively charged surfaces, specifically those containing acid anhydride groups, which explains the previously reported biocompatibility of Nanodiamonds.
Abstract: Nanodiamonds are a class of carbon-based nanoparticles that are rapidly gaining attention, particularly for biomedical applications, i.e., as drug carriers, for bioimaging, or as implant coatings. Nanodiamonds have generally been considered biocompatible with a broad variety of eukaryotic cells. We show that, depending on their surface composition, nanodiamonds kill Gram-positive and -negative bacteria rapidly and efficiently. We investigated six different types of nanodiamonds exhibiting diverse oxygen-containing surface groups that were created using standard pretreatment methods for forming nanodiamond dispersions. Our experiments suggest that the antibacterial activity of nanodiamond is linked to the presence of partially oxidized and negatively charged surfaces, specifically those containing acid anhydride groups. Furthermore, proteins were found to control the bactericidal properties of nanodiamonds by covering these surface groups, which explains the previously reported biocompatibility of nanodiamonds. Our findings describe the discovery of an exciting property of partially oxidized nanodiamonds as a potent antibacterial agent.