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"Graves, Robert"
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Using a grid-search approach to validate the Graves–Pitarka broadband simulation method
This work assesses the ability of the Graves–Pitarka simulation approach to reproduce observed ground motions for 12 California and Baja California earthquakes. A total of 240 realizations are computed for each earthquake and compared with recorded strong motions from near-fault sites. In addition to spatial variability in slip, each realization samples from discrete combinations of average rupture speed, rise time, and down-dip fault width. Ground motions for each realization of a given earthquake are compared to the observations using a pseudo-spectral acceleration goodness-of-fit (GoF) metric. Parameters for the lowest misfit cases are then tabulated to develop relations for estimating median values and ranges for future applications. The results are generally consistent with published scaling relations for estimating rupture dimensions as a function of magnitude. Additionally, I find the average rise time scales as 2.3×αT×10-9×Mo1/3 (Mo is seismic moment in dyne-cm) and average rupture speed as (0.765±0.075)×αT-1×Vs (Vs is local shear wave velocity), where aT is a mechanism adjustment ranging from a value of 1.0 for pure strike-slip to 0.9 for pure reverse-slip cases. There are cases where slightly different combinations of parameters produce equally good fits to the observations, demonstrating the non-uniqueness of using a single GoF metric in this approach. Nonetheless, the results reinforce the importance of adequately sampling ranges of rupture parameters when performing validations, as well as when simulating ground motions for future events.
Journal Article
A deep learning-based algorithm for 2-D cell segmentation in microscopy images
Background
Automatic and reliable characterization of cells in cell cultures is key to several applications such as cancer research and drug discovery. Given the recent advances in light microscopy and the need for accurate and high-throughput analysis of cells, automated algorithms have been developed for segmenting and analyzing the cells in microscopy images. Nevertheless, accurate, generic and robust whole-cell segmentation is still a persisting need to precisely quantify its morphological properties, phenotypes and sub-cellular dynamics.
Results
We present a single-channel whole cell segmentation algorithm. We use markers that stain the whole cell, but with less staining in the nucleus, and without using a separate nuclear stain. We show the utility of our approach in microscopy images of cell cultures in a wide variety of conditions. Our algorithm uses a deep learning approach to learn and predict locations of the cells and their nuclei, and combines that with thresholding and watershed-based segmentation. We trained and validated our approach using different sets of images, containing cells stained with various markers and imaged at different magnifications. Our approach achieved a 86% similarity to ground truth segmentation when identifying and separating cells.
Conclusions
The proposed algorithm is able to automatically segment cells from single channel images using a variety of markers and magnifications.
Journal Article
Lawrence and the Arabs
The real story of T. E. Lawrence's life as told by the author of I, Claudius. \"A combination of history, biography, and . . . an amazingly human tale\" ( Boston Evening Transcript).
Immortalized in the film Lawrence of Arabia, the real T. E. Lawrence was a leader, a war strategist, and a scholar, and is here immortalized in an intimate biography written by his close friend, the award-winning British novelist, poet and classicist Robert Graves.
As a student at Oxford, T. E. Lawrence was fascinated with Middle Eastern history and culture, and underwent a four-month visit to Syria to study the fortifications built by the crusaders. Later, he returned to the region, this time as an archaeologist working with the British Army's Intelligence unit in Egypt during World War I. From there, in 1916, he joined Arab rebels fighting against Turkish domination. His brilliance as a desert war tactician earned him the respect of the Turkish fighters and worldwide renown.
\"Interesting and informative.\" — New York Herald Tribune
\"[Mr. Graves] has done his job admirably and without any too obvious excesses of hero worship.\" — New Statesman
\"[Readers] will consult Mr. Graves for information about this man.\" — The New Republic
eBook
The Greek myths : the complete and definitive edition
'Icarus disobeyed his father's instructions and began soaring towards the sun, rejoiced by the lift of his great sweeping wings. Presently, when Daedalus looked over his shoulder, he could no longer see Icarus; but scattered feathers floated on the waves below...' These are the greatest stories ever told - the labours of Hercules, the voyage of the Argonauts, Theseus and the minotaur, Midas and his golden touch, the Trojan War and Odysseus's journey home - brought together into one epic and unforgettable story. Ideal for the first time reader, it can be read as a single page-turning narrative, while full commentaries as well as a comprehensive index of names make it equally valuable for anyone seeking an authoritative and detailed account of the spectacular stories that make up the bedrock of Western literature. The Greek Myths is a classic among classics, a treasure trove of extraordinary tales and a masterful work of literature in its own right.
Book
CyberShake: A Physics-Based Seismic Hazard Model for Southern California
CyberShake, as part of the Southern California Earthquake Center’s (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200 km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i.e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2 s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process.
Journal Article
The Islands of Unwisdom
Swashbuckling historical fiction from the author of I, Claudius. \"A cleverly balanced mixture of spice, fact, humor and adventure on and off the high seas\" ( Kirkus Reviews).
Set in the Age of Exploration, The Islands of Unwisdom tells the story of the ill-fated Don Álvaro de Mendaña y Neyra, a Spanish explorer set on finding the Solomon Islands, the mythical source of King Solomon's vast wealth. Driven by greed, ambition, and lust, Don Alvaro and his wife, the beautiful and dangerous Ysabel, lead a crew of adventurers beyond the horizon in search of the wealth of their wildest dreams.
However, that's not exactly what they find. In the hands of master historical novelist, classicist, and poet Robert Graves, this tale offers a fascinating look at a brutal and bloody era, and insights into the reasons for Spain's failure to ultimately dominate world exploration during this time.
eBook