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Peer Reviewed
See detailHydrogeological investigations at the Membach station, Belgium and application to correct long periodic gravity variations
Van Camp, M.; Vanclooster, M.; Crommen, O. et al

in Journal of Geophysical Research (2006), 111

A comprehensive hydrogeological investigation regarding the influence of variations in local and regional water mass on superconducting gravity measurements is presented for observations taken near the ... [more ▼]

A comprehensive hydrogeological investigation regarding the influence of variations in local and regional water mass on superconducting gravity measurements is presented for observations taken near the geodynamic station of Membach, Belgium. Applying a regional water storage model, the gravity contribution due to the elastic deformation of the Earth was derived. In addition, the Newtonian gravity effect induced by the local water mass variations was calculated, using soil moisture observations taken at the ground surface (about 48 m above the gravimeters). The computation of the gravimetric effect is based on a digital elevation model with spatially discretized rectangular prisms. The obtained results are compared with the observations of a superconducting gravimeter (SG). We find that the seasonal variations can be reasonably well predicted with the regional water storage model and the local Newtonian effects. Shorter-period effects depend on the local changes in hydrology. This result shows the sensitivity of SG observations to very local water storage changes. [less ▲]

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See detailHydrogeophysical Tools for Investigating Groundwater Storage in the Subsurface of a Karst System
Watlet, Arnaud; Van Noten, K.; Lecocq, T. et al

Poster (2014, September 14)

Detailed reference viewed: 115 (5 UL)
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See detailHydrokinetic and Solar Energy Contribution to a Reliable Energy Supply
Norta, David Peter Benjamin UL; Sachau, Jürgen UL; Allelein, Hans-Josef

Poster (2013, November 18)

Detailed reference viewed: 109 (14 UL)
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See detailHydrokinetic Energy for Enlightening the Future of Rural Communities in Uttarakhand
Tewari, Udit; Norta, David Peter Benjamin UL; Kolmsee, Karl

in Proceedings International Conference on Hydropower for Sustainable Development (2015, February 07)

Uttarakhand is a northern state of India located in the foothills of the Himalayan mountain ranges. It is rich in water resources with many perennial rivers originating in the state and has enormous ... [more ▼]

Uttarakhand is a northern state of India located in the foothills of the Himalayan mountain ranges. It is rich in water resources with many perennial rivers originating in the state and has enormous potential for hydropower generation. Despite of this fact the recent floods and agitation on setting up large and small hydropower plants has put a question mark on the future hydropower development and thus future of rural electrification in the state. In this context, the paper presents an idea of using hydrokinetic energy as a viable solution for securing low impact and viable power for rural communities in Uttarakhand. [less ▲]

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See detailHydrokinetic Micro-Power Generation in Small Rivers - a New Approach
Norta, David Peter Benjamin UL; Ramanathan, Sriram; Sachau, Jürgen UL et al

in Renewable Energy and Power Quality Journal (2015)

The so called German electrical “Energiewende” is mainly based on the installation of solar photovoltaic and wind energy converters as the main new renewable European generation resources. The third ... [more ▼]

The so called German electrical “Energiewende” is mainly based on the installation of solar photovoltaic and wind energy converters as the main new renewable European generation resources. The third renewable energy resource, the hydropower has been already developed within the last decades and grew not significantly in the last years. Since some years the development of smaller hydrokinetic turbines increased. The smaller size of some hydrokinetic turbines enables new, unused sites to be harnessed in smaller rivers. The paper deals with the key specifications of hydrokinetic turbines and their influence on a villages’ energy supply. It introduces the concept of a turbine with variable immersion depths to exploit also locations with a varying water level. Based on historical hydrological data a propeller and oscillating hydrofoil type of hydrokinetic turbine are compared, it was found that the variable immersion depths increases the energy harvest. Furthermore, it is shown that in a generation portfolio of hydrokinetic and solar power plants an average Luxembourgish household theoretically renewable supplied has to exchange less energy with the power grid, the higher its share of hydrokinetic generation is. [less ▲]

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See detailHydrokinetic Micro-Power Generation in Small Rivers - a New Approach
Norta, David Peter Benjamin UL; Ramanathan, Sriram; Sachau, Jürgen UL et al

Poster (2015, March 25)

The so called German electrical “Energiewende” is mainly based on the installation of solar photovoltaic and wind energy converters as the main new renewable European generation resources. The third ... [more ▼]

The so called German electrical “Energiewende” is mainly based on the installation of solar photovoltaic and wind energy converters as the main new renewable European generation resources. The third renewable energy resource, the hydropower has been already developed within the last decades and grew not significantly in the last years. Since some years the development of smaller hydrokinetic turbines increased. The smaller size of some hydrokinetic turbines enables new, unused sites to be harnessed in smaller rivers. The paper deals with the key specifications of hydrokinetic turbines and their influence on a villages’ energy supply. It introduces the concept of a turbine with variable immersion depths to exploit also locations with a varying water level. Based on historical hydrological data a propeller and oscillating hydrofoil type of hydrokinetic turbine are compared, it was found that the variable immersion depths increases the energy harvest. Furthermore, it is shown that in a generation portfolio of hydrokinetic and solar power plants an average Luxembourgish household theoretically renewable supplied has to exchange less energy with the power grid, the higher its share of hydrokinetic generation is. [less ▲]

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See detailHydrological effects on gravity at the station of Walferdange, Luxembourg
Lampitelli, Carmine UL

Doctoral thesis (2010)

In this study, we look at the physical relationship between water storage variations driven by local precipitation events and local gravity changes at Walferdange, in the Grand Duchy of Luxembourg. A ... [more ▼]

In this study, we look at the physical relationship between water storage variations driven by local precipitation events and local gravity changes at Walferdange, in the Grand Duchy of Luxembourg. A synthesis of the different approaches that can be found in recent literature is proposed. Then, a new and simple scheme is provided to remove the effects of precipitation events in the gravity observations, For the gravity observations, we use the data collected by the superconducting gravimeter CT040 (SG) located in the Walferdange Underground Laboratory for Geodynamics (WULG), which provides high resolution relative gravity measurements from December 2003. In addition, a statistical analysis is presented to determine the correlation between the gravity signal variations registered by the SG and the water level of the nearby flowing Alzette River. The idea is that the gravity variation due to the precipitation should appear before the change in river level. Contrarily to the simple precipitation data, the gravity observation should also contain information on the degree of soil saturation, which depends on processes having a seasonal variability, as evapotranspiration, and on hydrogeological parameters like hydraulic conductivity. Understanding the relationship and temporal dependence between the observed precipitation and the gravity changes might improve the capacity to predict extreme events like flooding. [less ▲]

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See detailHydrological mass changes inferred from high-low satellite-to-satellite tracking data
van Dam, Tonie UL; Weigelt, Matthias UL; Tourian, M. J. et al

Scientific Conference (2013, April)

The technique of deriving time variable gravity (TVG) field observations from high-low satellite-to-satellite tracking (hl-SST) is beginning to establish itself as a valuable and supplementary source for ... [more ▼]

The technique of deriving time variable gravity (TVG) field observations from high-low satellite-to-satellite tracking (hl-SST) is beginning to establish itself as a valuable and supplementary source for the determination and description of long wavelength geophysical phenomena. Recent developments in data processing techniques have pushed the limits of the accuracy of these types of observations and now allows for realistic determinations of long-term trends and annual amplitudes of hydrological signals. We use CHAMP data and a dedicated signal processing to derive annual and inter-annual variations in the largest catchments of the Earth system, e.g. Amazon, Ob and Lena. Results are validated by computing the correlation of aggregated water storage changes from CHAMP (and GRACE) with the hydro-meteorological storage changes. High noise levels demand a stronger filtering, e.g. larger filtering radius (1000-1400km), than usually applied in case of GRACE. We therefore also investigate the effect of filtering on the consistency with the hydrological mass changes and estimate the signal to noise ratio and the spatial and temporal dependency of the noise. We will show that hl-SST observations are a viable source of information for TVG which can even serve as a reliable substitute in the event of the impending end of GRACE's active lifetime. [less ▲]

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See detailHydrologische Effekte in der terrestrischen Gravimetrie
Weigelt, Matthias UL

Presentation (2011, November)

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See detailHydrolyzed infant formula and early β-cell autoimmunity: a randomized clinical trial
Knip, M.; Åkerblom, H.K.; Becker, D. et al

in JAMA : Journal of the American Medical Association (2014), 311(22), 2279-2287

Importance The disease process leading to clinical type 1 diabetes often starts during the first years of life. Early exposure to complex dietary proteins may increase the risk of β-cell autoimmunity in ... [more ▼]

Importance The disease process leading to clinical type 1 diabetes often starts during the first years of life. Early exposure to complex dietary proteins may increase the risk of β-cell autoimmunity in children at genetic risk for type 1 diabetes. Extensively hydrolyzed formulas do not contain intact proteins. Objective To test the hypothesis that weaning to an extensively hydrolyzed formula decreases the cumulative incidence of diabetes-associated autoantibodies in young children. Design, Setting, and Participants A double-blind randomized clinical trial of 2159 infants with HLA-conferred disease susceptibility and a first-degree relative with type 1 diabetes recruited from May 2002 to January 2007 in 78 study centers in 15 countries; 1078 were randomized to be weaned to the extensively hydrolyzed casein formula and 1081 were randomized to be weaned to a conventional cows’ milk–based formula. The participants were observed to April 16, 2013. Interventions The participants received either a casein hydrolysate or a conventional cows’ milk formula supplemented with 20% of the casein hydrolysate. Main Outcomes and Measures Primary outcome was positivity for at least 2 diabetes-associated autoantibodies out of 4 analyzed. Autoantibodies to insulin, glutamic acid decarboxylase, and the insulinoma-associated–2 (IA-2) molecule were analyzed using radiobinding assays and islet cell antibodies with immunofluorescence during a median observation period of 7.0 years (mean, 6.3 years). Results The absolute risk of positivity for 2 or more islet autoantibodies was 13.4% among those randomized to the casein hydrolysate formula (n = 139) vs 11.4% among those randomized to the conventional formula (n = 117). The unadjusted hazard ratio for positivity for 2 or more autoantibodies among those randomized to be weaned to the casein hydrolysate was 1.21 (95% CI, 0.94-1.54), compared with those randomized to the conventional formula, while the hazard ratio adjusted for HLA risk, duration of breastfeeding, vitamin D use, study formula duration and consumption, and region was 1.23 (95% CI, 0.96-1.58). There were no clinically significant differences in the rate of reported adverse events between the 2 groups. Conclusions and Relevance Among infants at risk for type 1 diabetes, the use of a hydrolyzed formula, when compared with a conventional formula, did not reduce the incidence of diabetes-associated autoantibodies after 7 years. These findings do not support a benefit from hydrolyzed formula. [less ▲]

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See detailHydroxycoumarin OT-55 kills CML cells alone or in synergy with imatinib or Synribo: Involvement of ER stress and DAMP release
Mazumder, A; Lee, JY; Talhi, O et al

in Cancer Letters (2018)

We synthetized and investigated the anti-leukemic potential of the novel cytostatic bis(4-hydroxycoumarin) derivative OT-55 which complied with the Lipinski's rule of 5 and induced differential toxicity ... [more ▼]

We synthetized and investigated the anti-leukemic potential of the novel cytostatic bis(4-hydroxycoumarin) derivative OT-55 which complied with the Lipinski's rule of 5 and induced differential toxicity in various chronic myeloid leukemia (CML) cell models. OT-55 triggered ER stress leading to canonical, caspase-dependent apoptosis and release of danger associated molecular patterns. Consequently, OT-55 promoted phagocytosis of OT-55-treated CML cells by both murine and human monocyte-derived macrophages. Moreover, OT-55 inhibited tumor necrosis factor α-induced activation of nuclear factor-кB and produced synergistic effects when used in combination with imatinib to inhibit colony formation in vitro and Bcr-Abl+ patient blast xenograft growth in zebrafish. Furthermore, OT-55 synergized with omacetaxine in imatinib-resistant KBM-5 R cells to inhibit the expression of Mcl-1, triggering apoptosis. In imatinib-resistant K562 R cells, OT-55 triggered necrosis and blocked tumor formation in zebrafish in combination with omacetaxine. [less ▲]

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See detailHyMN: An Interest-based Multimedia Providing System for Hybrid Wireless Networks
Andronache, Adrian UL; Brust, Matthias R. UL; Rothkugel, Steffen UL

in Proceedings of Broadband and Wireless Computing, Communications, and Applications (BWCCA-2006) (2006)

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See detailA hyper-reduction method using adaptivity to cut the assembly costs of reduced order models
Hale, Jack UL; Schenone, Elisa; Baroli, Davide UL et al

E-print/Working paper (2019)

At every iteration or timestep of the online phase of some reduced-order modelling schemes, large linear systems must be assembled and then projected onto a reduced order basis of small dimension. The ... [more ▼]

At every iteration or timestep of the online phase of some reduced-order modelling schemes, large linear systems must be assembled and then projected onto a reduced order basis of small dimension. The projected small linear systems are cheap to solve, but assembly and projection are now the dominant computational cost. In this paper we introduce a new hyper-reduction strategy called reduced assembly (RA) that drastically cuts these costs. RA consists of a triangulation adaptation algorithm that uses a local error indicator to con- struct a reduced assembly triangulation specially suited to the reduced order basis. Crucially, this reduced assembly triangulation has fewer cells than the original one, resulting in lower assembly and projection costs. We demonstrate the efficacy of RA on a Galerkin-POD type reduced order model (RAPOD). We show performance increases of up to five times over the baseline Galerkin-POD method on a non-linear reaction-diffusion problem solved with a semi-implicit time-stepping scheme and up to seven times for a 3D hyperelasticity problem solved with a continuation Newton-Raphson algorithm. The examples are implemented in the DOLFIN finite element solver using PETSc and SLEPc for linear algebra. Full code and data files to produce the results in this paper are provided as supplementary material. [less ▲]

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See detailHyperbolic dispersion metasurfaces for molecular biosensing
Palermo, Giovanna; Sreekanth, Kandammathe Valiyaveedu; Maccaferri, Nicolò UL et al

in Nanophotonics (in press)

Sensor technology has become increasingly crucial in medical research and clinical diagnostics to directly detect small numbers of low-molecular-weight biomolecules relevant for lethal diseases. In recent ... [more ▼]

Sensor technology has become increasingly crucial in medical research and clinical diagnostics to directly detect small numbers of low-molecular-weight biomolecules relevant for lethal diseases. In recent years, various technologies have been developed, a number of them becoming core label-free technologies for detection of cancer biomarkers and viruses. However, to radically improve early disease diagnostics, tracking of disease progression and evaluation of treatments, today’s biosensing techniques still require a radical innovation to deliver high sensitivity, specificity, diffusion-limited transport, and accuracy for both nucleic acids and proteins. In this review, we discuss both scientific and technological aspects of hyperbolic dispersion metasurfaces for molecular biosensing. Optical metasurfaces have offered the tantalizing opportunity to engineer wavefronts while its intrinsic nanoscale patterns promote tremendous molecular interactions and selective binding. Hyperbolic dispersion metasurfaces support high-k modes that proved to be extremely sensitive to minute concentrations of ultralow-molecular-weight proteins and nucleic acids. [less ▲]

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See detailHyperbolic ends with particles and grafting on singular surfaces
chen, qiyu; Schlenker, Jean-Marc UL

in Annales de L'Institut Henri Poincaré. Analyse Non Linéaire (2019), 36(1), 181-216

We prove that any hyperbolic end with particles (cone singularities along infinite curves of angles less than π) admits a unique foliation by constant Gauss curvature surfaces. Using a form of duality ... [more ▼]

We prove that any hyperbolic end with particles (cone singularities along infinite curves of angles less than π) admits a unique foliation by constant Gauss curvature surfaces. Using a form of duality between hyperbolic ends with particles and convex globally hyperbolic maximal (GHM) de Sitter spacetime with particles, it follows that any convex GHM de Sitter spacetime with particles also admits a unique foliation by constant Gauss curvature surfaces. We prove that the grafting map from the product of Teichm\"uller space with the space of measured laminations to the space of complex projective structures is a homeomorphism for surfaces with cone singularities of angles less than π, as well as an analogue when grafting is replaced by "smooth grafting". [less ▲]

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Peer Reviewed
See detailHyperbolic manifolds with convex boundary
Schlenker, Jean-Marc UL

in Invent. Math. (2006), 163(1), 109--169

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See detailHyperbolic Meta-Antennas Enable Full Control of Scattering and Absorption of Light
Maccaferri, Nicolò UL; Zhao, Yingqi; Isoniemi, Tommi et al

in Nano Letters (2019), 19(3), 1851-1859

We introduce a novel concept of hybrid metal-dielectric meta-antenna supporting type II hyperbolic dispersion, which enables full control of absorption and scattering of light in the visible/near-infrared ... [more ▼]

We introduce a novel concept of hybrid metal-dielectric meta-antenna supporting type II hyperbolic dispersion, which enables full control of absorption and scattering of light in the visible/near-infrared spectral range. This ability lies in the different nature of the localized hyperbolic Bloch-like modes excited within the meta-antenna. The experimental evidence is corroborated by a comprehensive theoretical study. In particular, we demonstrate that two main modes, one radiative and one non-radiative, can be excited by direct coupling with the free-space radiation. We show that the scattering is the dominating electromagnetic decay channel, when an electric dipolar mode is induced in the system, whereas a strong absorption process occurs when a magnetic dipole is excited. Also, by varying the geometry of the system, the relative ratio of scattering and absorption, as well as their relative enhancement and/or quenching, can be tuned at will over a broad spectral range, thus enabling full control of the two channels. Importantly, both radiative and nonradiative modes supported by our architecture can be excited directly with far-field radiation. This is observed to occur even when the radiative channels (scattering) are almost totally suppressed, thereby making the proposed architecture suitable for practical applications. Finally, the hyperbolic meta-antennas possess both angular and polarization independent structural integrity, unlocking promising applications as hybrid meta-surfaces or as solvable nanostructures. [less ▲]

Detailed reference viewed: 132 (16 UL)