—The dependence of synthetic earthquake catalog obtained by numerical modelling of block-structur... more —The dependence of synthetic earthquake catalog obtained by numerical modelling of block-structure dynamics for the Vrancea (Romania) seismoactive region on values of the model parameters is studied. The features of the synthetic seismicity, such as the spatial distribution of epicentres, the level of seismic activity, the relative activity of the different faults, are considered as functions of the directions of motions of the different blocks of the structure. The likelihood of the features of the synthetic and of the real seismicity could be used as criterion for the reconstruction of the direction of the tectonic motions.
This paper presents a 3-D regionalized model of the European crust and mantle velocity structure ... more This paper presents a 3-D regionalized model of the European crust and mantle velocity structure down to depths of approximately 300 km. The model is entirely based upon the existing geological and geophysical literature and it Ž. incorporates topographic and bathymetric features. The resulting model, which we call EurID European I-Data set , consists of approximately 6400 1-D vertical structures having an average separation of about 100 km. EurID is compared quantitatively with EUR-S91, a recent S-wave velocity tomographic model obtained from body and surface wave waveform w inversion Zielhuis, A., Nolet, G., 1994. Shear-wave velocity variations in the upper mantle beneath central Europe, x Ž. Geophys. J. Int., 117: 695–715. It is found that the S-wave velocities in EurID and in EUR-S91 Zielhuis and Nolet, 1994 do not differ by more than about 4% over most of the area. To validate EurID, surface wave dispersion analysis is performed along some selected paths. The fundamental mode group–velocity curves obtained using 1-D average models derived from EurID are found in good agreement with those determined from observations. Broadband waveform synthetics are also calculated along the same paths and compared with the observed time series. Overall, we believe that EurID is representative of our current knowledge of the crustrupper mantle structure beneath Europe and it can be used to model realistically ground motion for periods above 10 s within structurally homogeneous regions. The first digital version of this structure database is available for public use. q 1998 Published by Elsevier Science B.V.
—A seismically active region is modelled as a system of absolutely rigid blocks separated by infi... more —A seismically active region is modelled as a system of absolutely rigid blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is viscous-elastic. The system of blocks moves as a consequence of prescribed motion of the boundary blocks and of the underlying medium. When, for some part of a fault plane the stress exceeds a certain strength level, a stress-drop (''a failure'') occurs, and it can cause failures in other parts of the fault planes. In our model the failures represent earthquakes. As a result of the numerical simulation a synthetic earthquake catalog is produced. The procedure is applied to the numerical modelling of the dynamics of the block-structure, which approximates the tectonic structure of the Vrancea region. The result of the numerical experiment is a synthetic earthquake catalog with the space distribution of epicenters close to the real distribution and the frequency-magnitude relations (Gutenberg-Richter curves) obtained for the synthetic and real catalogs possessing some common features.
The application of the CN algorithm to a new earthquake catalogue, for the period fi-om 1932 to 1... more The application of the CN algorithm to a new earthquake catalogue, for the period fi-om 1932 to 1993, obtained by merging Romanian and U.S.S.R. data, allows us to monitor, on the intermediate time scale, the preparation of strong, intermediate-depth earthquakes in the Vrancea region. Four of the five strong earthquakes with magnitudes above 6.4 are predicted. The total duration of the Time of Increased Probability (TIP) of the occurrence of an earthquake (TIP) occupies 21.7% of the time interval under consideration, i.e., about 2.5 years for each strong earthquake.
The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation i... more The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation in laterally inhomogeneous geological profiles imbedded in a vertically inhomogeneous half-space in which an earthquake source is buried. To this end, an efficient hybrid modal summation-boundary integral equation method (MSM-BIEM) is developed and applied. The MSM is used as a tool for simulating wave propagation from the source position to the multilayered laterally inhomogeneous geological profile where the BIEM is applied. The proposed model and the hybrid tool are used to investigate the phenomena of site effects. In fact, such a methodology has the potential to investigate the combined effects of different physical phenomena like surface topography, lateral inhomogeneity and the existence of water saturation in soils on the estimation of site effects. The model and hybrid computational tool developed are applied to contribute to the seismic risk analysis of the Bulgarian capital Sofia.
Geology 38; no. 1; p. 59–62; doi: 10.1130/G30570.1;, 2010
While the superficial expression of oceanic ridges is generally symmetric, their deeper roots may... more While the superficial expression of oceanic ridges is generally symmetric, their deeper roots may be asymmetric. Based on a surface wave tomographic three-dimensional model of the Earth’s upper 300 km, we construct a global cross section parallel to the equator of the net rotation of the lithosphere, the so-called tectonic equator. Shear wave velocities indicate a difference between the western and eastern fl anks of the three major oceanic rift basins (Pacifi c, Atlantic, and Indian ridges). In general, the western limbs have a faster velocity and thicker lithosphere relative to the eastern or northeastern one, whereas the upper asthenosphere is faster in the eastern limb than in the western limb. We interpret the difference between the two fl anks as the combination of mantle depletion along the oceanic rifts and of the westward migration of the ridges and the lithosphere relative to the mantle. The low-velocity layer in the upper asthenosphere at the depth of 120–200 km is assumed to represent the decoupling between the lithosphere and the underlying mantle. It is also well defi ned by the distribution of radial anisotropy that reaches minimum values close to the rifts, but with an eastward offset. These results could be explained in the frame of the westward drift of the lithosphere relative to the underlying mantle.
NATO Science for Peace and Security Series C: Environmental Security, 2009
The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation i... more The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation in laterally inhomogeneous geological profiles imbedded in a vertically inhomogeneous half-space in which an earthquake source is buried. To this end, an efficient hybrid modal summation-boundary integral equation method (MSM-BIEM) is developed and applied. The MSM is used as a tool for simulating wave propagation from the source position to the multilayered laterally inhomogeneous geological profile where the BIEM is applied. The proposed model and the hybrid tool are used to investigate the phenomena of site effects. In fact, such a methodology has the potential to investigate the combined effects of different physical phenomena like surface topography, lateral inhomogeneity and the existence of water saturation in soils on the estimation of site effects. The model and hybrid computational tool developed are applied to contribute to the seismic risk analysis of the Bulgarian capital Sofia.
2015 European Conference on Networks and Communications (EuCNC), 2015
ABSTRACT The provisioning of e-health and specifically m-health services requires the usage of ad... more ABSTRACT The provisioning of e-health and specifically m-health services requires the usage of advanced and reliable communication techniques to offer acceptable Quality of Experience (QoE) for doctors in the transfer of biomedical data between involved parties (i.e. flawless, or almost flawless, and prompt enough delivery) using wired or wireless access networks. To overcome the restrictions of conventional communication systems and to address the challenges imposed by wireless/mobile multimedia transfer and adaptation for health-care applications, the CONCERTO project proposes a cross-layer optimized architecture with all the needed critical building blocks integrated for medical media content fusion, delivery and access, even on the move in emergency contexts. This paper describes the proposed reference system architecture, presenting the developed components and mechanisms in a comprehensive way, depicting and clarifying the overall picture and highlighting the impact of the CONCERTO approach in the healthcare domain. The evaluation of the proposed system is carried out both via simulation analysis and, more importantly, via validation involving real medical staff.
Applied Power Electronics Conference and Exposition Annual IEEE Conference, 2005
A reliable and highly efficient power-conditioning unit is fundamental for the commercial success... more A reliable and highly efficient power-conditioning unit is fundamental for the commercial success of fuel cell systems. A DC/DC converter especially designed for grid parallel applications and capable of operating over a wide input voltage range is presented. The proposed converter operation principle is based on the slow transients required by the fuel cell stacks and on the possibility of
Mice were fed powdered food which contained nifedipine, verapamil or diltiazem for 28 days. Long ... more Mice were fed powdered food which contained nifedipine, verapamil or diltiazem for 28 days. Long lasting treatment with nifedipine (0.28 mg/g b.w./day) or verapamil (0.27 mg/g b.w./day), but not with diltiazem (0.38 mg/g b.w./day) reduced the number of 3H-nitrendipine recognition sites in membranes prepared from cerebral cortex, caudate nucleus, and hippocampus. In addition, the veratridine-elicited stimulation of 45Ca-uptake in slices of the same brain areas was decreased in mice which were fed nifedipine or verapamil for 28 days.
2009 IFIP/IEEE International Symposium on Integrated Network Management-Workshops, 2009
Abstract Next-generation networks (NGNs) employ the Internet protocol (IP) over a wide variety of... more Abstract Next-generation networks (NGNs) employ the Internet protocol (IP) over a wide variety of packet-switching technologies, which often lack in fault resilience enabling features. An overlay MPLS infrastructure with its fast-reroute mechanisms can be deployed to overcome such an issue. Addressing NGNs robust to single link and node failures, an offline method to effectively calculate working and recovery paths for highly demanding services, is proposed and analyzed. The strength of our work is the ability to address two ...
The transmission of audio-video coded signals in real time applications over ATM networks require... more The transmission of audio-video coded signals in real time applications over ATM networks requires sophisticated techniques for synchronization and buffer control. The presence of ATM cell delay variation (CDV) represents the major jitter source affecting the ...
Prion diseases are fatal neurodegenerative diseases that occur either spontaneously or geneticall... more Prion diseases are fatal neurodegenerative diseases that occur either spontaneously or genetically or are caused by infection. Spontaneously occurring prion diseases are age related. The infectious agents, called prions, are proteinaceous infectious particles, composed mainly of the host-encoded prion protein (PrP) in a misfolded, insoluble, and aggregated isoform. Advanced glycation end products (AGEs) are well known to contribute to protein misfolding, insolubility, and aggregation. Thus, we studied if AGE-modification could influence PrP aggregation. We analyzed PrP preparations immunochemically to determine if they contain AGE-modified PrP. We also studied the influence of AGE modifications on the PrP aggregation process in vitro.
Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to d... more Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to deposits of naturally occurring proteins in the brain. In case of Creutzfeldt-Jakob disease (CJD), these deposits consist of prion protein (PrP). CJD has three etiologies: spontaneous, genetic, or caused by infection. A polymorphism within the PrP gene is associated with susceptibility of infection. The main event in prion diseases is the conversion of PrP from its naturally occurring isoform to its disease-associated isoform. Here, we present the adaption of a previously reported in vitro conversion system based on hamster recombinant PrP to analyze amyloid fibril formation of human recombinant PrP. We further compare the aggregation characteristics of the human PrP according to the polymorphism variants M129 and V129.
—The dependence of synthetic earthquake catalog obtained by numerical modelling of block-structur... more —The dependence of synthetic earthquake catalog obtained by numerical modelling of block-structure dynamics for the Vrancea (Romania) seismoactive region on values of the model parameters is studied. The features of the synthetic seismicity, such as the spatial distribution of epicentres, the level of seismic activity, the relative activity of the different faults, are considered as functions of the directions of motions of the different blocks of the structure. The likelihood of the features of the synthetic and of the real seismicity could be used as criterion for the reconstruction of the direction of the tectonic motions.
This paper presents a 3-D regionalized model of the European crust and mantle velocity structure ... more This paper presents a 3-D regionalized model of the European crust and mantle velocity structure down to depths of approximately 300 km. The model is entirely based upon the existing geological and geophysical literature and it Ž. incorporates topographic and bathymetric features. The resulting model, which we call EurID European I-Data set , consists of approximately 6400 1-D vertical structures having an average separation of about 100 km. EurID is compared quantitatively with EUR-S91, a recent S-wave velocity tomographic model obtained from body and surface wave waveform w inversion Zielhuis, A., Nolet, G., 1994. Shear-wave velocity variations in the upper mantle beneath central Europe, x Ž. Geophys. J. Int., 117: 695–715. It is found that the S-wave velocities in EurID and in EUR-S91 Zielhuis and Nolet, 1994 do not differ by more than about 4% over most of the area. To validate EurID, surface wave dispersion analysis is performed along some selected paths. The fundamental mode group–velocity curves obtained using 1-D average models derived from EurID are found in good agreement with those determined from observations. Broadband waveform synthetics are also calculated along the same paths and compared with the observed time series. Overall, we believe that EurID is representative of our current knowledge of the crustrupper mantle structure beneath Europe and it can be used to model realistically ground motion for periods above 10 s within structurally homogeneous regions. The first digital version of this structure database is available for public use. q 1998 Published by Elsevier Science B.V.
—A seismically active region is modelled as a system of absolutely rigid blocks separated by infi... more —A seismically active region is modelled as a system of absolutely rigid blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is viscous-elastic. The system of blocks moves as a consequence of prescribed motion of the boundary blocks and of the underlying medium. When, for some part of a fault plane the stress exceeds a certain strength level, a stress-drop (''a failure'') occurs, and it can cause failures in other parts of the fault planes. In our model the failures represent earthquakes. As a result of the numerical simulation a synthetic earthquake catalog is produced. The procedure is applied to the numerical modelling of the dynamics of the block-structure, which approximates the tectonic structure of the Vrancea region. The result of the numerical experiment is a synthetic earthquake catalog with the space distribution of epicenters close to the real distribution and the frequency-magnitude relations (Gutenberg-Richter curves) obtained for the synthetic and real catalogs possessing some common features.
The application of the CN algorithm to a new earthquake catalogue, for the period fi-om 1932 to 1... more The application of the CN algorithm to a new earthquake catalogue, for the period fi-om 1932 to 1993, obtained by merging Romanian and U.S.S.R. data, allows us to monitor, on the intermediate time scale, the preparation of strong, intermediate-depth earthquakes in the Vrancea region. Four of the five strong earthquakes with magnitudes above 6.4 are predicted. The total duration of the Time of Increased Probability (TIP) of the occurrence of an earthquake (TIP) occupies 21.7% of the time interval under consideration, i.e., about 2.5 years for each strong earthquake.
The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation i... more The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation in laterally inhomogeneous geological profiles imbedded in a vertically inhomogeneous half-space in which an earthquake source is buried. To this end, an efficient hybrid modal summation-boundary integral equation method (MSM-BIEM) is developed and applied. The MSM is used as a tool for simulating wave propagation from the source position to the multilayered laterally inhomogeneous geological profile where the BIEM is applied. The proposed model and the hybrid tool are used to investigate the phenomena of site effects. In fact, such a methodology has the potential to investigate the combined effects of different physical phenomena like surface topography, lateral inhomogeneity and the existence of water saturation in soils on the estimation of site effects. The model and hybrid computational tool developed are applied to contribute to the seismic risk analysis of the Bulgarian capital Sofia.
Geology 38; no. 1; p. 59–62; doi: 10.1130/G30570.1;, 2010
While the superficial expression of oceanic ridges is generally symmetric, their deeper roots may... more While the superficial expression of oceanic ridges is generally symmetric, their deeper roots may be asymmetric. Based on a surface wave tomographic three-dimensional model of the Earth’s upper 300 km, we construct a global cross section parallel to the equator of the net rotation of the lithosphere, the so-called tectonic equator. Shear wave velocities indicate a difference between the western and eastern fl anks of the three major oceanic rift basins (Pacifi c, Atlantic, and Indian ridges). In general, the western limbs have a faster velocity and thicker lithosphere relative to the eastern or northeastern one, whereas the upper asthenosphere is faster in the eastern limb than in the western limb. We interpret the difference between the two fl anks as the combination of mantle depletion along the oceanic rifts and of the westward migration of the ridges and the lithosphere relative to the mantle. The low-velocity layer in the upper asthenosphere at the depth of 120–200 km is assumed to represent the decoupling between the lithosphere and the underlying mantle. It is also well defi ned by the distribution of radial anisotropy that reaches minimum values close to the rifts, but with an eastward offset. These results could be explained in the frame of the westward drift of the lithosphere relative to the underlying mantle.
NATO Science for Peace and Security Series C: Environmental Security, 2009
The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation i... more The study presents and solves the 2-D elastodynamic model for seismic in-plane wave propagation in laterally inhomogeneous geological profiles imbedded in a vertically inhomogeneous half-space in which an earthquake source is buried. To this end, an efficient hybrid modal summation-boundary integral equation method (MSM-BIEM) is developed and applied. The MSM is used as a tool for simulating wave propagation from the source position to the multilayered laterally inhomogeneous geological profile where the BIEM is applied. The proposed model and the hybrid tool are used to investigate the phenomena of site effects. In fact, such a methodology has the potential to investigate the combined effects of different physical phenomena like surface topography, lateral inhomogeneity and the existence of water saturation in soils on the estimation of site effects. The model and hybrid computational tool developed are applied to contribute to the seismic risk analysis of the Bulgarian capital Sofia.
2015 European Conference on Networks and Communications (EuCNC), 2015
ABSTRACT The provisioning of e-health and specifically m-health services requires the usage of ad... more ABSTRACT The provisioning of e-health and specifically m-health services requires the usage of advanced and reliable communication techniques to offer acceptable Quality of Experience (QoE) for doctors in the transfer of biomedical data between involved parties (i.e. flawless, or almost flawless, and prompt enough delivery) using wired or wireless access networks. To overcome the restrictions of conventional communication systems and to address the challenges imposed by wireless/mobile multimedia transfer and adaptation for health-care applications, the CONCERTO project proposes a cross-layer optimized architecture with all the needed critical building blocks integrated for medical media content fusion, delivery and access, even on the move in emergency contexts. This paper describes the proposed reference system architecture, presenting the developed components and mechanisms in a comprehensive way, depicting and clarifying the overall picture and highlighting the impact of the CONCERTO approach in the healthcare domain. The evaluation of the proposed system is carried out both via simulation analysis and, more importantly, via validation involving real medical staff.
Applied Power Electronics Conference and Exposition Annual IEEE Conference, 2005
A reliable and highly efficient power-conditioning unit is fundamental for the commercial success... more A reliable and highly efficient power-conditioning unit is fundamental for the commercial success of fuel cell systems. A DC/DC converter especially designed for grid parallel applications and capable of operating over a wide input voltage range is presented. The proposed converter operation principle is based on the slow transients required by the fuel cell stacks and on the possibility of
Mice were fed powdered food which contained nifedipine, verapamil or diltiazem for 28 days. Long ... more Mice were fed powdered food which contained nifedipine, verapamil or diltiazem for 28 days. Long lasting treatment with nifedipine (0.28 mg/g b.w./day) or verapamil (0.27 mg/g b.w./day), but not with diltiazem (0.38 mg/g b.w./day) reduced the number of 3H-nitrendipine recognition sites in membranes prepared from cerebral cortex, caudate nucleus, and hippocampus. In addition, the veratridine-elicited stimulation of 45Ca-uptake in slices of the same brain areas was decreased in mice which were fed nifedipine or verapamil for 28 days.
2009 IFIP/IEEE International Symposium on Integrated Network Management-Workshops, 2009
Abstract Next-generation networks (NGNs) employ the Internet protocol (IP) over a wide variety of... more Abstract Next-generation networks (NGNs) employ the Internet protocol (IP) over a wide variety of packet-switching technologies, which often lack in fault resilience enabling features. An overlay MPLS infrastructure with its fast-reroute mechanisms can be deployed to overcome such an issue. Addressing NGNs robust to single link and node failures, an offline method to effectively calculate working and recovery paths for highly demanding services, is proposed and analyzed. The strength of our work is the ability to address two ...
The transmission of audio-video coded signals in real time applications over ATM networks require... more The transmission of audio-video coded signals in real time applications over ATM networks requires sophisticated techniques for synchronization and buffer control. The presence of ATM cell delay variation (CDV) represents the major jitter source affecting the ...
Prion diseases are fatal neurodegenerative diseases that occur either spontaneously or geneticall... more Prion diseases are fatal neurodegenerative diseases that occur either spontaneously or genetically or are caused by infection. Spontaneously occurring prion diseases are age related. The infectious agents, called prions, are proteinaceous infectious particles, composed mainly of the host-encoded prion protein (PrP) in a misfolded, insoluble, and aggregated isoform. Advanced glycation end products (AGEs) are well known to contribute to protein misfolding, insolubility, and aggregation. Thus, we studied if AGE-modification could influence PrP aggregation. We analyzed PrP preparations immunochemically to determine if they contain AGE-modified PrP. We also studied the influence of AGE modifications on the PrP aggregation process in vitro.
Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to d... more Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to deposits of naturally occurring proteins in the brain. In case of Creutzfeldt-Jakob disease (CJD), these deposits consist of prion protein (PrP). CJD has three etiologies: spontaneous, genetic, or caused by infection. A polymorphism within the PrP gene is associated with susceptibility of infection. The main event in prion diseases is the conversion of PrP from its naturally occurring isoform to its disease-associated isoform. Here, we present the adaption of a previously reported in vitro conversion system based on hamster recombinant PrP to analyze amyloid fibril formation of human recombinant PrP. We further compare the aggregation characteristics of the human PrP according to the polymorphism variants M129 and V129.
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