A preliminary study of the mountain lion : felis oregonensis sp.

Bibliography: p. 58-59https://digitalrepository.unm.edu/unm_bulletin/1029/thumbnail.jp

Eleven Case Studies of Failures in Geotechnical Engineering, Engineering Geology, and Geophysics: How They Could Have Been Avoided

When a failure occurs, geotechnical engineers, engineering geologists, and geophysicists assign its cause to an event that immediately precedes the failure, such as an earthquake, heavy rainfall, flood, or other natural event. Assigning the failure to the immediate event is misplaced; the metastasis occurred because marginally stable conditions were allowed to exist through substandard investigations by the technical personnel, improper design, and inadequate review by the permitting agency. The fundamental cause of the failure is human error and is manifested in one or more of six categories. (1) Before the investigation, during discussions with the client. (2) During the investigation, by collecting inadequate, incomplete, or incorrect data; altering the field or test data to make them more favorable. (3) After the investigation, when the inadequate data and invalid conclusions are incorporated in the final report. (4) During the review process, when the reviewers accept the substandard report. (5) After the agency approves the substandard report. (6) After the agency grants the permit that allows construction to begin and after the work begins. Eleven case studies of failures are described including landslides, dam failures, floods, and ground subsidence. Each case study identifies (1) the immediate event, (2) the fundamental cause, (3) how the inadequacies and deficiencies in one or more of the six categories contributed to the failure, and (4) how the failure could have been prevented. Each of these failures resulted in civil or criminal court action. Depending on the facts in each case, penalties were imposed on the engineer, geologist, or geophysicist

Ariel - Volume 6 Number 1

Editors John Lammie Curt Cummings Frank Chervenak J.D. Kanofsky Mark Dembert Entertainment Robert Breckenridge Joe Conti Gary Kaskey Photographer Larry Glazerman Overseas Editor Mike Sinason Circulation Jay Amsterdam Humorist Jim McCann Staff Ken Jaffe Bob Sklaroff Halley Faus

Morphological stability of electromigration-driven vacancy islands

The electromigration-induced shape evolution of two-dimensional vacancy islands on a crystal surface is studied using a continuum approach. We consider the regime where mass transport is restricted to terrace diffusion in the interior of the island. In the limit of fast attachment/detachment kinetics a circle translating at constant velocity is a stationary solution of the problem. In contrast to earlier work [O. Pierre-Louis and T.L. Einstein, Phys. Rev. B 62, 13697 (2000)] we show that the circular solution remains linearly stable for arbitrarily large driving forces. The numerical solution of the full nonlinear problem nevertheless reveals a fingering instability at the trailing end of the island, which develops from finite amplitude perturbations and eventually leads to pinch-off. Relaxing the condition of instantaneous attachment/detachment kinetics, we obtain non-circular elongated stationary shapes in an analytic approximation which compares favorably to the full numerical solution.Comment: 12 page

New insights into water splitting at mesoporous α-Fe₂O₃ films: a study by modulated transmittance and impedance spectroscopies

Closed access. This article was published in the Journal of the American Chemical Society [© American Chemical Society] and the definitive version is available at: http://dx.doi.org/10.1021/ja209530sThin mesoporous films of α-Fe2O3 have been prepared on conducting glass substrates using layer-by-layer self-assembly of ca. 4 nm hydrous oxide nanoparticles followed by calcining. The electrodes were used to study the oxygen evolution reaction (OER) in the dark and under illumination using in situ potential-modulated absorption spectroscopy (PMAS) and light-modulated absorption spectroscopy (LMAS) combined with impedance spectroscopy. Formation of surface-bound higher-valent iron species (or “surface trapped holes”) was deduced from the PMAS spectra measured in the OER onset region. Similar LMAS spectra were obtained at more negative potentials in the onset region of photoelectrochemical OER, indicating involvement of the same intermediates. The impedance response of the mesoporous α-Fe2O3 electrodes exhibits characteristic transmission line behavior that is attributed to slow hopping of holes, probably between surface iron species. Frequency-resolved PMAS and LMAS measurements revealed slow relaxation behavior that can be related to the impedance response and that indicates that the lifetime of the intermediates (or trapped holes) involved in the OER is remarkably long

Near-field photocurrent nanoscopy on bare and encapsulated graphene

Opto-electronic devices utilizing graphene have already demonstrated unique capabilities, which are much more difficult to realize with conventional technologies. However, the requirements in terms of material quality and uniformity are very demanding. A major roadblock towards high-performance devices are the nanoscale variations of graphene properties, which strongly impact the macroscopic device behaviour. Here, we present and apply opto-electronic nanoscopy to measure locally both the optical and electronic properties of graphene devices. This is achieved by combining scanning near-field infrared nanoscopy with electrical device read-out, allowing infrared photocurrent mapping at length scales of tens of nanometers. We apply this technique to study the impact of edges and grain boundaries on spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can also be applied to encapsulated graphene/hexagonal boron nitride (h-BN) devices, where we observe strong charge build-up near the edges, and also address a device solution to this problem. The technique enables nanoscale characterization for a broad range of common graphene devices without the need of special device architectures or invasive graphene treatment

Linear scaling quantum transport methodologies

Altres ajuts: SR, AWC and JHG acknowledge PRACE and the Barcelona Supercomputing Center (Project No. 2015133194). ICN2 is funded by the CERCA Programme/Generalitat de Catalunya.In recent years, predictive computational modeling has become a cornerstone for the study of fundamental electronic, optical, and thermal properties in complex forms of condensed matter, including Dirac and topological materials. The simulation of quantum transport in realistic models calls for the development of linear scaling, or order-N, numerical methods, which then become enabling tools for guiding experimental research and for supporting the interpretation of measurements. In this review, we describe and compare different order-N computational methods that have been developed during the past twenty years, and which have been used extensively to explore quantum transport phenomena in disordered media. We place particular focus on the zero-frequency electrical conductivities derived within the Kubo-Greenwood​ and Kubo-Streda formalisms, and illustrate the capabilities of these methods to tackle the quasi-ballistic, diffusive, and localization regimes of quantum transport in the noninteracting limit. The fundamental issue of computational cost versus accuracy of various proposed numerical schemes is addressed in depth. We then illustrate the usefulness of these methods with various examples of transport in disordered materials, such as polycrystalline and defected graphene models, 3D metals and Dirac semimetals, carbon nanotubes, and organic semiconductors. Finally, we extend the review to the study of spin dynamics and topological transport, for which efficient approaches for calculating charge, spin, and valley Hall conductivities are described