Modeling mountain building and the seismic cycle in the Himalaya of Nepal

A host of information is now available regarding the geological and thermal structure as well as deformation rate across the Himalaya of central Nepal. These data are reconciled in a two-dimensional mechanical model that incorporates the rheological layering of the crust which depends on the local temperature and surface processes. Over geological timescale (5 Ma) the ∼20 mm/yr estimated shortening rate across the range is accommodated by localized thrust faulting along the Main Himalayan Thrust fault (MHT). The MHT reaches the surface along the foothills, where it is called the Main Frontal Thrust fault (MFT). The MHT flattens beneath the Lesser Himalaya and forms a midcrustal ramp at the front of the Higher Himalaya, consistent with the river incision and the anticlinal structure of the Lesser Himalaya. Farther northward the MHT roots into a subhorizontal shear zone that coincides with a midcrustal seismic reflector. Aseismic slip along this shear zone is accommodated in the interseismic period by elastic straining of the upper crust, increasing the Coulomb stress beneath the front of the Higher Himalaya, where most of the microseismic activity clusters. Negligible deformation of the hanging wall requires a low apparent friction coefficient (μ) less than ∼0.3 on the flat portion of the MHT. On the ramp, μ might be as high as 0.6. Sensitivity tests show that a rather compliant, quartz-rich rheology and a high radioactive heat production in the upper crust of ∼2.5 μW/m^3 is required. Erosion affects the thermal structure and interplays with crustal deformation. A dynamic equilibrium is obtained in which erosion balances tectonic uplift maintaining steady state thermal structure, topography, and deformation field. Using a linear diffusion model of erosion, we constrain the value of the mass diffusivity coefficient to 0.5–1.6×l0^4 m^2/yr. This study demonstrates that the data are internally consistent and compatible with current understanding of the mechanics of crustal deformation and highlight the role of viscous flow in the lower crust and of surface erosion in orogeny processes on the long term as well as during interseismic period

Stress buildup in the Himalaya

The seismic cycle on a major fault involves long periods of elastic strain and stress accumulation, driven by aseismic ductile deformation at depth, ultimately released by sudden fault slip events. Coseismic slip distributions are generally heterogeneous with most of the energy being released in the rupture of asperities. Since, on the long term, the fault's walls generally do not accumulate any significant permanent deformation, interseismic deformation might be heterogeneous, revealing zones of focused stress buildup. The pattern of current deformation along the Himalayan arc, which is known to produce recurring devastating earthquakes, and where several seismic gaps have long been recognized, might accordingly show significant lateral variations, providing a possible explanation for the uneven microseismic activity along the Himalayan arc. By contrast, the geodetic measurements show a rather uniform pattern of interseismic strain, oriented consistently with long-term geological deformation, as indicated from stretching lineation. We show that the geodetic data and seismicity distribution are reconciled from a model in which microseismicity is interpreted as driven by stress buildup increase in the interseismic period. The uneven seismicity pattern is shown to reflect the impact of the topography on the stress field, indicating low deviatoric stresses (<35 MPa) and a low friction (<0.3) on the Main Himalayan Thrust. Arc-normal thrusting along the Himalayan front and east-west extension in southern Tibet are quantitatively reconciled by the model

XPS Study of the Band Alignment at the Interface ITO/CuI

The band alignment at the interface of an ITO/CuI heterojunction is studied by X-ray photoelectron spectroscopy (XPS). The measurements have been performed on samples obtained under the same experimental conditions as those used to achieve organic photovoltaic cells. The CuI upper layer was 3 nm thick. The semidirect XPS technique used to measure the band offsets allows us to estimate the band discontinuities at the interface ITO/CuI: ΔEv = 2.10 eV and ΔEc = 1.56 eV. This band alignment induces an increase of the work function of the anode when the structure ITO/CuI is used as electrode in organic solar cells for instance. As a matter of fact, the measurement, by means of a Kelvin probe, of the work function of the structures ITO/CuI, shows that it is significantly higher than that of ITO alone: 5.2 eV and 4.8 eV.

Standardized on-road tests assessing fitness-to-drive in people with cognitive impairments: A systematic review.

The on-road assessment is the gold standard because of its ecological validity. Yet existing instruments are heterogeneous and little is known about their psychometric properties. This study identified existing on-road assessment instruments and extracted data on psychometric properties and usability in clinical settings. A systematic review identified studies evaluating standardized on-road evaluation instruments adapted for people with cognitive impairment. Published articles were searched on PubMed, CINHAL, PsycINFO, Web of Science, and ScienceDirect. Study quality and the level of evidence were assessed using the COSMIN checklist. The collected data were synthetized using a narrative approach. Usability was subjectively assessed for each instrument by extracting information on acceptability, access, cost, and training. The review identified 18 published studies between 1994 and 2016 that investigated 12 different on-road evaluation instruments: the Performance-Based Driving Evaluation, the Washington University Road Test, the New Haven, the Test Ride for Practical Fitness to Drive, the Rhode Island Road Test, the Sum of Manoeuvres Score, the Performance Analysis of Driving Ability, the Composite Driving Assessment Scale, the Nottingham Neurological Driving Assessment, the Driving Observation Schedule, the Record of Driving Errors, and the Western University's On-road Assessment. Participants were mainly male (64%), between 48 and 80 years old, and had a broad variety of cognitive disorders. Most instruments showed reasonable psychometric values for internal consistency, criterion validity, and reliability. However, the level of evidence was poor to support any of the instruments given the low number of studies for each. Despite the social and health consequences of decisions taken using these instruments, little is known about the value of a single evaluation and the ability of instruments to identify expected changes. None of the identified on-road evaluation instruments seem currently adapted for clinical settings targeting rehabilitation and occupational priorities rather than road security alone. PROSPERO registration number CRD42018103276

FPGA Mezzanine Cards for CERN’s Accelerator Control System

Field Programmable Gate Arrays (FPGAs) have become a key player in modern real time control systems. They offer determinism, simple design, high performance and versatility. A typical hardware architecture consists of an FPGA interfaced with a control bus and a variable number of digital IOs, ADCs and DACs depending on the application. Until recently the low-cost hardware paradigm has been using mezzanines containing a front end interface plus custom logic (typically an FPGA) and a local bus that interfaces the mezzanine to a carrier. As FPGAs grow in size and shrink in price, hardware reuse, testability and bus access speed could be improved if the user logic is moved to the carrier. The new FPGA Mezzanine Card (FMC) Vita 57 standard is a good example of this new paradigm. In this paper we present a standard kit of FPGA carriers and IO mezzanines for accelerator control. Carriers form factors will be VME, PCI and PCIe. The carriers will feature White Rabbit support for accurate synchronization of distributed systems. Initial plans include IO mezzanines for 100Ms/s ADCs and DACs, digital drivers and inputs, high accuracy time tag units and fine delay generators

Control of the MKQA tuning and aperture kickers of the LHC

The large hadron collider (LHC) at CERN has been equipped with four fast pulsed kicker magnets in RA43 situated at point 4 which are part of the measurement system for the tune and the dynamic aperture of the LHC beam (Beam 1 and Beam 2). For the tune measurement 'Q', the magnets will excite oscillations in part of the beam. This is achieved by means of a generator producing a 5 µs base half-sine pulse of 1.2 kA [1] amplitude, superimposed with a 3rd harmonic to produce a 2 µs flat top. A kick repetition rate of 2 Hz will be possible. To measure the dynamic aperture 'A' of the LHC at different beam energies, the same magnets will also be driven by a more powerful generator which produces a 43 µs base half-sine current pulse of 3.8 kA. For the 'A' mode a thyristor is used as switching element inside the generator. A final third mode named 'AC dipole' will rely on the beam being excited coherently at a frequency close but outside its Eigen-frequencies by an oscillating dipole field. The beam is expected to oscillate at the exciter frequency of 3 kHz with a phase shift of π/2. The 'AC dipole' will use two 18 kW audio amplifiers capable of driving the magnets at 1 kHz(rms) around 3 kHz or between 2.7 kHz and 4 kHz. The complete system uses supervisory control implemented with Siemens PLC technology with added Siemens PROFIsafe safety feature to treat the various interlocks that have been introduced in the circuits and to assu re a safe functioning and provide 'LOCAL' and 'REMOTE' control (via CCC) of the complete installation

On the use of dislocations to model interseismic strain and stress build-up at intracontinental thrust faults

Creeping dislocations in an elastic half-space are commonly used to model interseismic deformation at subduction zones, and might also apply to major intracontinental thrust faults such as the Main Himalayan Thrust. Here, we compare such models with a more realistic 2-D finite element model that accounts for the mechanical layering of the continental lithosphere and surface processes, and that was found to fit all available constraints on interseismic and long-term surface displacements. These can also be fitted satisfactorily from dislocation models. The conventional back-slip model, commonly used for subduction zones, may, however, lead to a biased inference about the geometry of the locked portion of the thrust fault. We therefore favour the use of a creeping buried dislocation that simulates the ductile shear zone in the lower crust. A limitation of dislocation models is that the mechanical response of the lithosphere to the growth of the topography by bending of the elastic cores and ductile flow in the lower crust cannot be easily introduced. Fortunately these effects can be neglected because we may assume, to first order, a stationary topography. Moreover, we show that not only can dislocation models be used to adjust surface displacements but, with some caution, they can also provide a physically sound rationale to interpret interseismic microseismicity in terms of stress variations

MoO3/CuI hybrid buffer layer for the optimization of organic solar cells based on a donor-acceptor triphenylamine

We investigate the effect of anode buffer layers (ABLs) on the performances of multi-layer heterojunction solar cells with thienylenevinylene-triphenylamine with peripheral dicyanovinylene groups (TDCV-TPA) as donor material and fullerene C-60 as acceptor. The deposition of a CuI layer between the ITO anode and the electron donor significantly improves the short-circuit current density (J(sc)) and fill factor (FF) but reduces the open-circuit voltage (V-oc). On the other hand, a MoO3 buffer layer increases the V-oc but leads to limited J(sc) and FF values, thus reducing power conversion efficiency (PCE). In this context, we show that the use of a hybrid anode buffer layer MoO3/CuI leads to a considerable improvement of the cells performances and a PCE of 2.50% has been achieved. These results are discussed on the basis of the dual function of MoO3 and CuI. While both of them reduce the hole injection barrier, CuI improves the conductivity of the organic film through an improvement of molecular order while MoO3 prevents leakage current through the diode. Finally the results of a cursory study of the ageing process provide further support to this interpretation of the effects of the various buffer layers. (C) 2012 Elsevier B.V. All rights reserved