yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic ...structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independent-particle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oft-neglected physical effects such as electron-phonon interactions to the implementation of a real-time propagation scheme for simulating linear and non-linear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools.
Long‐term landslide deformation is disruptive and costly in urbanized environments. We rely on TerraSAR‐X satellite images (2009–2014) and an improved data processing algorithm (SqueeSAR™) to produce ...an exceptionally dense Interferometric Synthetic Aperture Radar ground deformation time series for the San Francisco East Bay Hills. Independent and principal component analyses of the time series reveal four distinct spatial and temporal surface deformation patterns in the area around Blakemont landslide, which we relate to different geomechanical processes. Two components of time‐dependent landslide deformation isolate continuous motion and motion driven by precipitation‐modulated pore pressure changes controlled by annual seasonal cycles and multiyear drought conditions. Two components capturing more widespread seasonal deformation separate precipitation‐modulated soil swelling from annual cycles that may be related to groundwater level changes and thermal expansion of buildings. High‐resolution characterization of landslide response to precipitation is a first step toward improved hazard forecasting.
Plain Language Summary
In an ever‐expanding urban environment, we opt to live with the risk of catastrophic natural hazards through a perceived safety net of building codes and engineering solutions. Unfortunately, our concern for these hazards is often focused on their immediate impact to our everyday lives and does not account for imperceptible processes that may become significant over decades in time. Notoriously, some landslides slowly and continuously deform, ultimately causing costly unpredicted damage to homes, lifelines, and other infrastructure. Recent advances in satellite technology allow us to accurately measure these long‐term movements, tracking where and when they occur. We show that the duration and amount of seasonal precipitation and associated water pressure changes determine how fast the landslides move and how recent drought conditions have slowed their advance. The satellite data allow us to differentiate the landslide deformation from normal seasonal changes in unaffected areas, giving us greater predictability of this hazard.
Key Points
Independent component analysis of radar interferometry time series reveals four spatiotemporal deformation patterns on and off landslides
Seasonal and drought‐related pore pressure changes modulate landslide deformation
Precipitation also produces widespread soil shrink/swell and groundwater‐related surface deformation
Purpose
The purpose of this study is to evaluate the kinematics changes of the knee after cutting of the ACL with or without injury of the anterolateral structures.
Methods
In this study, the role of ...the ACL and one of the secondary restraints in controlling knee stability using a navigation system was evaluated. The kinematics of the knee was evaluated in different conditions of instability: ACL intact, after dissection of the posterolateral (PL) bundle, after dissection of the anteromedial (AM) bundle, and after lesion of the lateral capsular ligament (LCL). Anterior tibial translation and rotation were measured with a computer navigation system in 10 fresh-frozen cadaveric knees by use of a manual maximum load. Anterior translation was evaluated at 30°, 60°, and 90° of flexion; rotation at 0°, 15°, 30°, 45°, 60°, and 90°.
Results
Cutting the PL bundle does not increase anterior translation and rotation of the knee. Cutting the AM bundle significantly increased the anteroposterior (AP) translation at 30° and 60° (
P
= 0.01), but does not increase rotation of the knee. Cutting the LCL increased anterior translation at 60° (
P
= 0.04) and rotation at 30°, 45°, and 60° (
P
= 0.03).
Conclusions
Within the testing conditions of this study, the PL bundle does not affect anterior translation and rotation of the knee; the AM bundle is the primary restraint of the anterior translation but does not affect rotation of the knee while the lesion of the LCL increases tibial rotation and could be related to the pivot shift phenomenon, so it is more correct and biomechanical valid to assess and repair the associated lesion of the antero-lateral structure of the knee at the time of ACL surgery.
We investigate the performance of beyond-GW approaches in many-body perturbation theory by addressing atoms described within the spherical approximation via a dedicated numerical treatment based on ...B-splines and spherical harmonics. We consider the GW, second Born (2B), and GW + second order screened exchange (GW+SOSEX) self-energies and use them to obtain ionization potentials from the quasi-particle equation (QPE) solved perturbatively on top of independent-particle calculations. We also solve the linearized Sham–Schlüter equation (LSSE) and compare the resulting xc potentials against exact data. We find that the LSSE provides consistent starting points for the QPE but does not present any practical advantage in the present context. Still, the features of the xc potentials obtained with it shed light on possible strategies for the inclusion of beyond-GW diagrams in the many-body self-energy. Our findings show that solving the QPE with the GW+SOSEX self-energy on top of a PBE or PBE0 solution is a viable scheme to go beyond GW in finite systems, even in the atomic limit. However, GW shows a comparable performance if one agrees to use a hybrid starting point. We also obtain promising results with the 2B self-energy on top of Hartree–Fock, suggesting that the full time-dependent Hartree–Fock vertex may be another viable beyond-GW scheme for finite systems.
Discrete and temporarily stable natural reflectors or permanent scatterers (PS) can be identified from long temporal series of interferometric SAR images even with baselines larger than the so-called ...critical baseline. This subset of image pixels can be exploited successfully for high accuracy differential measurements. The authors discuss the use of PS in urban areas, like Pomona, CA, showing subsidence and absidence effects. A new approach to the estimation of the atmospheric phase contributions, and the local displacement field is proposed based on simple statistical assumptions. New solutions are presented in order to cope with nonlinear motion of the targets.
Optical leveling campaigns, tiltmeters, GPS and InSAR are geodetic techniques used to detect and monitor surface deformation phenomena. In particular, InSAR data from satellite radar sensors are ...gaining increasing attention for their cost-effectiveness and unique technical features, making possible the monitoring of large areas, even revisiting the past. Moreover, more advanced InSAR techniques (PSInSAR™, SqueeSAR™) developed in the last decade are capable of providing millimeter precision, comparable to optical leveling, and a high spatial density of displacement measurements, over long periods of time without need of installing equipment or otherwise accessing the study area.
Thanks to the high density and quality of the measurements the PSInSAR data can be successfully used in geophysical inversion, to measure the permeability of oil reservoirs and/or to evaluate the possibilities and risks due to seismic faulting in the sequestration of CO2. In these cases, the precision, the sub weekly frequency of the measurements and the time required for the data to be available are the most important aspects, more relevant than the spatial resolution.
Until recently, the main limitation to the application of InSAR was the relatively long revisiting time (24 or 35days) and the quite long waiting period for the delivery of the acquired data. The new Sentinel-1 mission, based on a constellation of two satellites, is expected to reduce such limitations guaranteeing a revisit cycle of 6days on a global scale and in particular over Europe and Canada and providing a high level of service reliability with near-real-time delivery of data within 24h, important for risk management applications. The new X band satellite SAR constellations like Cosmo Skymed and TerraSAR X have also a short revisiting time, from 4 to 11days. However, their coverage is limited to well definite areas, and an expensive decision has to be made if to initiate the observations on any target. Sentinel 1, instead, yields global and costless observations and thus, after the end of the commissioning phase, will always produce present and past ground motion for any target.
It's important to underline that the millimeter accuracy, applying the InSAR analysis with Sentinel-1, will be achieved within a shorter observation time frame, thanks to the increased number of acquired images per year (Attema et al. 2010, De Zan et al., 2008). Results from ground based radar show that this improved precision is indeed achievable from C to Ku band, provided that an accurate model of the delay due to atmospheric water vapor is available or that precise reference points are close by.
► Millimeter motions of the terrain are needed for CO2 sequestration monitoring. ► The permeability of the reservoir is measured and reopening of faults is observed. ► Millimeter precision is attained by radar interferometry, with PSInSAR methodology. ► Alternate methodologies like GPS and optical have yet to be proven adequate to the task. ► Atmospheric delays can be practically removed if reference points are closer than 1km.
Permanent scatterers in SAR interferometry Ferretti, A.; Prati, C.; Rocca, F.
IEEE transactions on geoscience and remote sensing,
2001-Jan., 2001, 2001-01-00, 20010101, Letnik:
39, Številka:
1
Journal Article
Recenzirano
Temporal and geometrical decorrelation often prevents SAR interferometry from being an operational tool for surface deformation monitoring and topographic profile reconstruction. Moreover, ...atmospheric disturbances can strongly compromise the accuracy of the results. The authors present a complete procedure for the identification and exploitation of stable natural reflectors or permanent scatterers (PSs) starting from long temporal series of interferometric SAR images. When, as it often happens, the dimension of the PS is smaller than the resolution cell, the coherence is good even for interferograms with baselines larger than the decorrelation one, and all the available images of the ESA ERS data set can be successfully exploited. On these pixels, submeter DEM accuracy and millimetric terrain motion detection can be achieved, since atmospheric phase screen (APS) contributions can be estimated and removed. Examples are then shown of small motion measurements, DEM refinement, and APS estimation and removal in the case of a sliding area in Ancona, Italy. ERS data have been used.
The relative low resolution (~25 m times 5 m on the ground) of spaceborne C-band synthetic aperture radar (SAR) data as acquired, for example, by European Space Agency sensors ERS and Envisat, can be ...significantly increased (up to submeter precisions) by processing coherently long series of images. Moreover, by analyzing the amplitude of the radar signal and by exploiting polarization diversity, the main radar characteristics of urban targets can be estimated, and a system for automatic recognition of a set of scattering structures can be developed. In this paper, we study the variation of the amplitude of the received radar signal as a function of the acquisition geometry normal baseline and Doppler centroid (DC) to retrieve the extension of the targets in range and azimuth. The dependence of the radar amplitude on temperature at the time of acquisition has been discovered to be very useful to identify extended resonating targets. Dihedrals are discriminated from specular or trihedral reflectors through the phase of Envisat alternating polarization (AP) acquisitions. By means of all gathered radar measurements, the bases for the development of a system for the automatic recognition of six main typologies of urban SAR targets (ground-level and elevated backscatterers, simple and resonating dihedrals, poles and trihedrals) have been laid. Radar data are then combined with in situ surveys and aerial photos, allowing a first assessment of the methodology in urban area.
Critical librarianship, or critlib, has made its way into the mainstream of library and information science through conferences, scholarly publications, social media, and other outlets. Over the past ...10 years critical library instruction specifically has continued to be a much presented and published topic. Classes and other groups that come through our libraries are opportunities for us to teach, learn, and empower. The care and critical perspectives we bring into the classroom are necessary, but are we also fostering this type of environment in the workplace? Are we doing enough to turn the critical lens on ourselves? As a woman of color in a predominantly white profession, it is difficult to not feel as though critical librarianship is performative. There is a time and place to refer to theory and another to engage in practice. Throughout this article I will illustrate that while critical pedagogy in librarianship has changed the way we teach information literacy and think of the teacher/student relationship, it's been slower to change power relations between library colleagues. We ask our students to critically examine a resource and to see what is being left out of the conversation. It's time to not only ask the same of us and the profession but also for us to take action.
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