Results 4141-4160 of 6532.
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See detailSystems Ecology of microbiomes: identifying key functions
Wilmes, Paul UL

Scientific Conference (2018, August)

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See detailThe integration of quantitative big data from microbial consortia: what is there to gain?
Wilmes, Paul UL

Scientific Conference (2018, August)

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See detailEnergy-Efficient Resource Optimization with Wireless Power Transfer for Secure NOMA Systems
Lei, Lei UL; Chang, Zheng; Hu, Yun et al

in IEEE/CIC International Conference on Communications in China (ICCC 2018) (2018, August)

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See detailExperimental and numerical investigation into the softening Behavior of a packed bed of iron ore pellets
Baniasadi, Mehdi UL; Peters, Bernhard UL

in Powder Technology (2018), 339

In this contribution, the softening process of a packed bed of pre-reduced pellets is investigated numerically and experimentally. For this purpose, pellets were reduced to different reduction degrees in ... [more ▼]

In this contribution, the softening process of a packed bed of pre-reduced pellets is investigated numerically and experimentally. For this purpose, pellets were reduced to different reduction degrees in a reduction apparatus. The range of reduction degree (RD) was selected 50 − 80%, which is an acceptable range for iron-bearing materials reaching the cohesive zone. Then, softening experiments under load for a packed bed of pre-reduced pellets in a lab-scale furnace at a temperature range of 800oC to initial melt formation point were carried out. For the modeling part, the newly developed eXtended Discrete Element Method (XDEM) is used. This method is able to predict the deformation of particles over temperature which needs an extension to include heat transfer to DEM. Heat transfer between particle-particle, particle-wall, and particle-gas is considered. To validate the XDEM results with the measurements, an appropriate relationship between Young's modulus of the pellet versus temperature has been estimated. The effect of load on the bed shrinkage is also discussed. FactSage version 7.0 software was used to compute the initial melt point with the phase equilibrium for a 5-component FeO − SiO2 − CaO − MgO − Al2O3 system. [less ▲]

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See detailIntegrated time-resolved multi-omics for understanding microbial niche ecology
Herold, Malte UL; Narayanasamy, Shaman UL; Martinez Arbas, Susana UL et al

Poster (2018, August)

Microbial communities are strongly shaped by the niche breadths of their constituent populations. However, a detailed understanding of microbial niche ecology is typically lacking. Integrated multi-omic ... [more ▼]

Microbial communities are strongly shaped by the niche breadths of their constituent populations. However, a detailed understanding of microbial niche ecology is typically lacking. Integrated multi-omic analyses of host- or environment-derived samples offer the prospect of resolving fundamental and realised niches in situ. In turn, this is considered a prerequisite for niche engineering in order to drive an individual population or a community towards a specific phenotype, e.g., improvement of a biotechnological process. Here, we sampled floating islets on the surface of an activated sludge tank in a time-series spanning 51 time-points over 14 months. Multi-omics datasets (metagenomics, metatranscriptomics, metaproteomics, and (meta-)metabolomics) were generated for all time-points. Leveraging nucleotide sequencing data, we analyzed the community structure and reconstructed genomes for specific populations of interest. Moreover, based on their metabolic potential, three major groups emerged, serving as proxies for their respective fundamental niches . Time-resolved linkage of the proteomic and transcriptomic data to the reconstructed genomes revealed a fine-grained picture of niche realization. In particular, environmental factors (temperature, metabolites, oxygen) were significantly associated with gene expression of individual populations. Furthermore, we subjected the community to controlled oxygen conditions (stable or dynamic) in a bioreactor experiment and measured the transcriptomic response. Our results suggest short-term adaptations of populations of interest with respect to lipid metabolism, among other pathways. In conclusion, our work demonstrates how longitudinal multi-omic datasets can be integrated in order to further our understanding of microbial niche ecology within a biotechnological process with potential applications beyond waste water treatment. [less ▲]

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See detailAb initio and semiempirical modeling of excitons and trions in monolayer TiS3
Torun, Engin UL; Sahin, H.; Chavez, A. et al

in Physical Review. B, Condensed Matter (2018), 98

We explore the electronic and the optical properties of monolayer TiS3, which shows in-plane anisotropy and is composed of a chain-like structure along one of the lattice directions. Together with its ... [more ▼]

We explore the electronic and the optical properties of monolayer TiS3, which shows in-plane anisotropy and is composed of a chain-like structure along one of the lattice directions. Together with its robust direct band gap, which changes very slightly with stacking order and with the thickness of the sample, the anisotropic physical prop- erties of TiS3 make the material very attractive for various device applications. In this study, we present a detailed investigation on the effect of the crystal anisotropy on the excitons and the trions of the TiS3 monolayer. We use many-body perturbation theory to calculate the absorption spectrum of anisotropic TiS3 monolayer by solving the Bethe-Salpeter equation. In parallel, we implement and use a Wannier-Mott model for the excitons that takes into account the anisotropic effective masses and Coulomb screening, which are obtained from ab initio calculations. This model is then extended for the investigation of trion states of monolayer TiS3. Our calculations indicate that the absorption spectrum of monolayer TiS3 drastically depends on the polarization of the incoming light, which excites different excitons with distinct binding energies. In addition, the binding energies of positively and the negatively charged trions are observed to be distinct and they exhibit an anisotropic probability density distribution. [less ▲]

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See detailOptical control of polarization in ferroelectric heterostructures
Tao, Li; Lipatov, Alexej; Lu, Haidong et al

in Nature Communications (2018), 9

In the ferroelectric devices, polarization control is usually accomplished by application of an electric field. In this paper, we demonstrate optically induced polarization switching in BaTiO3-based ... [more ▼]

In the ferroelectric devices, polarization control is usually accomplished by application of an electric field. In this paper, we demonstrate optically induced polarization switching in BaTiO3-based ferroelectric heterostructures utilizing a two-dimensional narrow-gap semiconductor MoS2 as a top electrode. This effect is attributed to the redistribution of the photo-generated carriers and screening charges at the MoS2/BaTiO3 interface. Specifically, a two-step process, which involves formation of intra-layer excitons during light absorption followed by their decay into inter-layer excitons, results in the positive charge accumulation at the interface forcing the polarization reversal from the upward to the downward direction. Theoretical modeling of the MoS2 optical absorption spectra with and without the applied electric field provides quantitative support for the proposed mechanism. It is suggested that the discovered effect is of general nature and should be observable in any heterostructure comprising a ferroelectric and a narrow gap semiconductor. [less ▲]

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See detailTEI Transviewer
Armaselu, Florentina UL; Reis, Frederic UL; Jones, Catherine UL et al

Software (2018)

TEI Transviewer is an interface intended to the exploration of primary and secondary sources, at the document level, in historical or other types of digital editions involving the representation of ... [more ▼]

TEI Transviewer is an interface intended to the exploration of primary and secondary sources, at the document level, in historical or other types of digital editions involving the representation of original material. Its name comes from the combination of the terms transformation and viewing, supposing the transformation of documents in XML-TEI format (directly in the browser or by means of a server/dedicated editor) so that they can be viewed in the browser. [less ▲]

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See detailThe RNA Complement of Outer Membrane Vesicles From Salmonella enterica Serovar Typhimurium Under Distinct Culture Conditions
Malabirade, Antoine UL; Habier, Janine UL; Heintz-Buschart, Anna et al

in Frontiers in Microbiology (2018), 9

Bacterial outer membrane vesicles (OMVs), as well as OMV-associated small RNAs, have been demonstrated to play a role in host–pathogen interactions. The presence of larger RNA transcripts in OMVs has been ... [more ▼]

Bacterial outer membrane vesicles (OMVs), as well as OMV-associated small RNAs, have been demonstrated to play a role in host–pathogen interactions. The presence of larger RNA transcripts in OMVs has been less studied and their potential role in host–pathogen interactions remains largely unknown. Here we analyze RNA from OMVs secreted by Salmonella enterica serovar Typhimurium (S. Typhimurium) cultured under different conditions, which mimic host–pathogen interactions. S. Typhimurium was grown to exponential and stationary growth phases in minimal growth control medium (phosphate-carbon-nitrogen, PCN), as well as in acidic and phosphate-depleted PCN, comparable to the macrophage environment and inducing therefore the expression of Salmonella pathogenicity island 2 (SPI-2) genes. Moreover, Salmonella pathogenicity island 1 (SPI-1), which is required for virulence during the intestinal phase of infection, was induced by culturing S. Typhimurium to the stationary phase in Lysogeny Broth (LB). For each condition, we identified OMV-associated RNAs that are enriched in the extracellular environment relative to the intracellular space. All RNA classes could be observed, but a vast majority of rRNA was exported in all conditions in variable proportions with a notable decrease in LB SPI-1 inducing media. Several mRNAs and ncRNAs were specifically enriched in/on OMVs dependent on the growth conditions. Important to note is that some RNAs showed identical read coverage profiles intracellularly and extracellularly, whereas distinct coverage patterns were observed for other transcripts, suggesting a specific processing or degradation. Moreover, PCR experiments confirmed that distinct RNAs were present in or on OMVs as full-length transcripts (IsrB-1/2; IsrA; ffs; SsrS; CsrC; pSLT035; 10Sa; rnpB; STM0277; sseB; STM0972; STM2606), whereas others seemed to be rather present in a processed or degraded form. Finally, we show by a digestion protection assay that OMVs are able to prevent enzymatic degradation of given full-length transcripts (SsrS, CsrC, 10Sa, and rnpB). In summary, we show that OMV-associated RNA is clearly different in distinct culture conditions and that at least a fraction of the extracellular RNA is associated as a full-length transcripts with OMVs, indicating that some RNAs are protected by OMVs and thereby leaving open the possibility that those might be functionally active. [less ▲]

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See detailBlockchain-Based, Decentralized Access Control for IPFS
Steichen, Mathis UL; Fiz Pontiveros, Beltran UL; Norvill, Robert UL et al

in The 2018 IEEE International Conference on Blockchain (Blockchain-2018) (2018, July 30)

Large files cannot be efficiently stored on blockchains. On one hand side, the blockchain becomes bloated with data that has to be propagated within the blockchain network. On the other hand, since the ... [more ▼]

Large files cannot be efficiently stored on blockchains. On one hand side, the blockchain becomes bloated with data that has to be propagated within the blockchain network. On the other hand, since the blockchain is replicated on many nodes, a lot of storage space is required without serving an immediate purpose, especially if the node operator does not need to view every file that is stored on the blockchain. It furthermore leads to an increase in the price of operating blockchain nodes because more data needs to be processed, transferred and stored. IPFS is a file sharing system that can be leveraged to more efficiently store and share large files. It relies on cryptographic hashes that can easily be stored on a blockchain. Nonetheless, IPFS does not permit users to share files with selected parties. This is necessary, if sensitive or personal data needs to be shared. Therefore, this paper presents a modified version of the InterPlanetary Filesystem (IPFS) that leverages Ethereum smart contracts to provide access controlled file sharing. The smart contract is used to maintain the access control list, while the modified IPFS software enforces it. For this, it interacts with the smart contract whenever a file is uploaded, downloaded or transferred. Using an experimental setup, the impact of the access controlled IPFS is analyzed and discussed. [less ▲]

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See detailA Proof of Entropy Minimization for Outputs in Deletion Channels via Hidden Word Statistics
Atashpendar, Arash UL; Mestel, David UL; Roscoe, A.W. (Bill) et al

E-print/Working paper (2018)

From the output produced by a memoryless deletion channel from a uniformly random input of known length n, one obtains a posterior distribution on the channel input. The difference between the Shannon ... [more ▼]

From the output produced by a memoryless deletion channel from a uniformly random input of known length n, one obtains a posterior distribution on the channel input. The difference between the Shannon entropy of this distribution and that of the uniform prior measures the amount of information about the channel input which is conveyed by the output of length m, and it is natural to ask for which outputs this is extremized. This question was posed in a previous work, where it was conjectured on the basis of experimental data that the entropy of the posterior is minimized and maximized by the constant strings 𝟶𝟶𝟶… and 𝟷𝟷𝟷… and the alternating strings 𝟶𝟷𝟶𝟷… and 𝟷𝟶𝟷𝟶… respectively. In the present work we confirm the minimization conjecture in the asymptotic limit using results from hidden word statistics. We show how the analytic-combinatorial methods of Flajolet, Szpankowski and Vall\'ee for dealing with the hidden pattern matching problem can be applied to resolve the case of fixed output length and n→∞, by obtaining estimates for the entropy in terms of the moments of the posterior distribution and establishing its minimization via a measure of autocorrelation. [less ▲]

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See detailResponse functions as quantifiers of non-Markovianity
Strasberg, Philipp UL; Esposito, Massimiliano UL

in Physical Review Letters (2018)

Quantum non-Markovianity is crucially related to the study of dynamical maps, which are usually derived for initially factorized system-bath states. We here demonstrate that linear response theory also ... [more ▼]

Quantum non-Markovianity is crucially related to the study of dynamical maps, which are usually derived for initially factorized system-bath states. We here demonstrate that linear response theory also provides a way to derive dynamical maps, but for initially correlated (and in general entangled) states. Importantly, these maps are always time-translational invariant and allow for a much simpler quantification of non-Markovianity compared to previous approaches. We apply our theory to the Caldeira-Leggett model, for which our quantifier is valid beyond linear response and can be expressed analytically. We find that a classical Brownian particle coupled to an Ohmic bath can already exhibit non-Markovian behaviour, a phenomenon related to the initial state preparation procedure. Furthermore, for a peaked spectral density we demonstrate that there is no monotonic relation between our quantifier and the system-bath coupling strength, the sharpness of the peak or the resonance frequency in the bath. [less ▲]

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See detailSubtle Fluorination of Conjugated Molecules Enables Stable Nanoscale Assemblies on Metal Surfaces
Niederhausen, Jens; Zhang, Yuan; Kabeer, Fairoja et al

in Journal of Physical Chemistry C (2018), 122(33), 10

In molecular self-assembly on surfaces, the structure is governed by the intricate balance of attractive and repulsive forces between molecules as well as between molecules and the substrate. Frequently ... [more ▼]

In molecular self-assembly on surfaces, the structure is governed by the intricate balance of attractive and repulsive forces between molecules as well as between molecules and the substrate. Frequently, repulsive interactions between molecules adsorbed on a metal surface dominate in the low-coverage regime, and dense self-assembled structures can only be observed close to full monolayer coverage. Here, we demonstrate that fluorination at selected positions of conjugated molecules provides for sufficiently strong, yet nonrigid, H···F bonding capability that (i) enables the formation of stable nanoscale molecular assemblies on a metal surface and (ii) steers the assemblies’ structure. This approach should be generally applicable and will facilitate the construction and study of individual nanoscale molecular assemblies with structures that are not attainable in the high-coverage regime. [less ▲]

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See detailDetailed Fluctuation Theorems: A Unifying Perspective
Riccardo, Rao; Esposito, Massimiliano UL

in Entropy (2018)

We present a general method to identify an arbitrary number of fluctuating quantities which satisfy a detailed fluctuation theorem for all times within the framework of time-inhomogeneous Markovian jump ... [more ▼]

We present a general method to identify an arbitrary number of fluctuating quantities which satisfy a detailed fluctuation theorem for all times within the framework of time-inhomogeneous Markovian jump processes. In doing so, we provide a unified perspective on many fluctuation theorems derived in the literature. By complementing the stochastic dynamics with a thermodynamic structure (i.e., using stochastic thermodynamics), we also express these fluctuating quantities in terms of physical observables. [less ▲]

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See detailA holding control strategy for diverging bus lines
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Scientific Conference (2018, July 24)

We introduce a holding criterion for network configurations with lines that operate jointly along a common corridor and then individually diverge. The proposed holding decision rule accounts for all ... [more ▼]

We introduce a holding criterion for network configurations with lines that operate jointly along a common corridor and then individually diverge. The proposed holding decision rule accounts for all different passengers groups in the overlapping segment and takes care of the transition to individual line operation. The holding rule is evaluated using simulation for different demand levels and segmentations and compared with other control schemes for a real-world network. Results show that gains in overall network performance as well as for specific passenger groups can be achieved under specific demand distributions. [less ▲]

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See detailImpact of visa liberalisation on countries of destination
Sommarribas, Adolfo UL; Nienaber, Birte UL

Report (2018)

Historically, Luxembourg has developed during the last 68 years strong links with the Western Balkan countries. In 1970, a labour agreement was signed between the Grand Duchy of Luxembourg and the Former ... [more ▼]

Historically, Luxembourg has developed during the last 68 years strong links with the Western Balkan countries. In 1970, a labour agreement was signed between the Grand Duchy of Luxembourg and the Former Republic of Yugoslavia to provide for workers to come to work in Luxembourg. This bilateral agreement created a diaspora from the Western Balkans in Luxembourg. Montenegrin nationals represent the largest third-country national population while the Serbians and the Bosnians represents the 3rd and 4th largest nationality groups. There has been a significant number of naturalisations from the West Balkan countries during the last 10 years. This diaspora was a significant “pull factor” during the Yugoslav Wars (1991-1999) and the economic crisis of 2008. This study was unable to verify direct and automatic links between the entering into force of the visa liberalisation agreements with the West Balkans countries and Eastern Partnership countries and an impact for Luxembourg. The large majority of increases, independently if it is legal migration, irregular migration or international protection did not occur during the next year following the entering into force of the agreements. These increases occurred generally during the second year or later. Concerning visa liberalisation agreements with the Western Balkan countries, the first findings are a dramatic increase of international protection applicants from those countries since the agreements came into force. In the international protection field and in the framework of the return decisions, the visa liberalisation agreement had a negative impact generating stress for all the public administrations during 2011 and 2012, which have to deal with international protection and the return mechanism. During 2011, there was a significant increase of applicants from Macedonia and Serbia and in 2012 from Albania and Bosnia-Herzegovina. This situation placed the Luxembourgish authorities under significant stress to deal with this significant inflow of applicants, whose applications were, in the large majority of cases (80%), rejected. However, this situation obliged the Luxembourgish government to take measures in order to deal in a very efficient manner with these inflows of international protection applicants as well as to overhaul the entire international protection procedure. These measures can be divided into two different: procedural measures and implementation measures. The most significant procedural measures are: a) the introduction of the fast track procedure and the implementation of the ultra-expedite procedure; b) the introduction of these countries in the list of safe countries of origin. These measures allow the authorities to deal more efficiently with the massive influx of international protection applicants coming from the region. The implementation measures are: a) No access to social aid for the applicant benefiting from a commitment to cover all expenses by a Luxembourg national, EU citizen or TCN residing in Luxembourg; b) substantial decrease in monthly cash amounts of social aid for adult individuals and households; c) Recruitment and reallocation of staff in the Directorate of Immigration and the Luxembourg Reception and Integration office; d) implementing the Assisted voluntary return Balkans (AVR Balkans) which only covers the return bus ticket; and e) strengthen cooperation with the authorities of the Western Balkan countries. During 2017, there was an increase in the number of international protection applicants from Georgia and Ukraine, even though both countries are included in the list of safe countries of origin. As Luxembourg does not have external borders with the exception of the International Airport, it is not possible to obtain pertinent information concerning the detection of irregular entries in the territory. Nevertheless, there is some evidence that some individuals from these countries have taken advantage of the visa liberalisation agreements to come to work irregularly in Luxembourg, even if it is not possible to quantify the scale of the phenomenon. The findings of this study do not show an increase in the number of applications for authorisation of stay or residence permits (remunerated and study activities), so the EU visa liberalisation agreements did not have any impact in the legal migration field. The increase of application was visible after the second year of entering into force of these agreements but the numbers were not significant in regard with number of applications made by third-country nationals during the same period. However, the short-stay visits (i.e. friends, family, tourism, etc.) seem not only to have been facilitated, but also increased. In some cases, these short-visits have also been used not only to visit family and friends but also to be familiarized with the Luxembourgish society and to explore job opportunities and look for housing. This is probably the only positive impact that the visa liberalization agreements have had. Seen that the visa liberalisation agreements only allow travelling without a visa, but they do not allow working and staying in the country, and based on the data collected there is not possible to establish a link between them and any significant impact with regard to economy and to criminality (especially related to traffic of human beings or smuggling, where the numbers are very low and not directly related in most cases to nationals concerned by this study). [less ▲]

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See detailCARRIER GRAPHS FOR REPRESENTATIONS OF THE RANK TWO FREE GROUP INTO ISOMETRIES OF HYPERBOLIC THREE SPACE
Tan, Ser Peow; Xu, Binbin UL

E-print/Working paper (2018)

Carrier graphs were first introduced for closed hyperbolic 3-manifolds by White. In this paper, we first generalize this definition to carrier graphs for representations of a rank two free group into the ... [more ▼]

Carrier graphs were first introduced for closed hyperbolic 3-manifolds by White. In this paper, we first generalize this definition to carrier graphs for representations of a rank two free group into the isometry group of hyperbolic three space. Then we prove the existence and the finiteness of minimal carrier graphs for those representations which are discrete, faithful and geometrically finite, and more generally, those that satisfy certain finiteness conditions first introduced by Bowditch. [less ▲]

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See detailStrain and Damage Self-Sensing of BFRP Laminates Fabricated with CNFs/Epoxy Composites under Tension
Wang, Y.L; Wang, Y.S.; Wan, B.L. et al

in Composites. Part A, Applied Science and Manufacturing (2018)

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile ... [more ▼]

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile loadings. The conduction mechanisms based on the tunnel conduction and percolation conduction theories as well as the damage evolution were also explored. A compensation circuit with a half-bridge configuration was proposed. The results indicated the resistivity of the CNFs/BFRP laminates and CNFs/epoxy composites exhibited similar change rule, indicating that the conductive networks of CNFs/BFRP laminates were governed by CNFs/epoxy composites. With the increase of strain under monotonic tensile loading, the electrical resistance response could be classified into three stages corresponding to different damage modes. This confirmed CNFs/BFRP laminates have excellent self-sensing abilities to monitor their internal damages. Moreover, stable and repeatable strain self-sensing capacity of the CNFs/BFRP laminates was verified under cyclic tensile loading because the electrical resistance varied synchronously with the applied strain. [less ▲]

Detailed reference viewed: 31 (2 UL)