180 research outputs found

    Total Variation Regularization of Geodetically and Geologically Constrained Block Models for the Western United States

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    Geodetic observations of interseismic deformation in the Western United States provide con- straints on microplate rotations, earthquake cycle processes, and slip partitioning across the Pacific–North America Plate boundary. These measurements may be interpreted using block models, in which the upper crust is divided into microplates bounded by faults that accumulate strain in a first-order approximation of earthquake cycle processes. The number and geometry of microplates are typically defined with boundaries representing a limited subset of the large number of potentially seismogenic faults. An alternative approach is to include a large number of potentially active faults bounding a dense array of microplates, and then algorithmically estimate the boundaries at which strain is localized. This approach is possible through the application of a total variation regularization (TVR) optimization algorithm, which simultaneously minimizes the L2 norm of data residuals and the L1 norm of the variation in the differential block motions. Applied to 3-D spherical block models, the TVR algorithm can be used to reduce the total variation between estimated rotation vectors, effectively grouping microplates that rotate together as larger blocks, and localizing fault slip on the boundaries of these larger block clusters. Here we develop a block model comprised of 137 microplates derived from published fault maps, and apply the TVR algorithm to identify the kinematically most important faults in the western United States. This approach reveals that of the 137 microplates considered, only 30 unique blocks are required to approximate deformation in the western United States at a residual level of \u3c2 mm yr−1

    The Role of Slow Slip Events in the Cascadia Subduction Zone Earthquake Cycle

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    Slow slip events (SSEs) detected on the Cascadia Subduction Zone interface at 30–50 km depth imply a release of accumulated strain. However, studies of interseismic deformation in Cascadia typically find coupling on the upper 30 km of the interface, which is generally accepted as defining the seismogenic zone. Estimates of coupling using net interseismic velocities (including SSE effects) and restricting coupling to the shallow interface may underestimate slip deficit accumulation at depths \u3e30 km. Here, we detect reversals in GPS motion as indications of SSEs, then use SSE displacements to estimate cumulative slow slip from 2007 to 2021. We calculate pure interseismic velocities, correcting for SSE displacements, and use them to constrain an elastic block model, estimating slip deficit on the subduction interface down to 50 km. By evaluating slip deficit and slow slip independently, we examine SSEs’ effect on interseismic strain accumulation, and the effect of inter-SSE slip deficit and slow slip on vertical deformation of the forearc. We find that moderate to high coupling extends to 40 km depth, and while shallow coupling is consistent with previous estimates of the seismogenic zone, a deeper region of slip deficit beneath the Olympic Peninsula may be partially (61%) relieved aseismically by SSEs. Patterns of surface uplift suggest that complete relief of deep coupling over multiple decades may be accomplished by time-varying rates of aseismic slip

    Health Promotion in the Public Sector: A Case Study from Policy to Practice

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    Employee wellness programs are popular among employers because they have the potential to lead to positive outcomes for the employees and the organization. Moving from a public policy to local implementation, or the process of "operationalizing," presents a challenge within most organizations. The case study presented here provides an illustration of one public university?s attempt to interpret and apply a state policy to implement a wellness program for its employees. It features a description of the policy, a description of the context in which the policy is implemented and provides observations of the challenges and successes implementing the policy, lessons learned, and future directions

    Curating Nasa's Future Extraterrestrial Sample Collections: the Role of Advanced Curation

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    The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (JSC) (henceforth referred to herein as NASA Curation Office) is responsible for curating all of NASA's extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10F "Curation of Extraterrestrial Materials," JSC is charged with "The curation of all extraterrestrial material under NASA control, including future NASA missions." The Directive goes on to define Curation as including "...documentation, preservation, preparation, and distribution of samples for re-search, education, and public outreach." Here we describe some of the ongoing efforts to ensure that the future activities of the NASA Curation Office are working towards a state of maximum proficiency

    Physicochemical characterization and genotoxicity of the broad class of carbon nanotubes and nanofibers used or produced in US facilities

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    Background Carbon nanotubes and nanofibers (CNT/F) have known toxicity but simultaneous comparative studies of the broad material class, especially those with a larger diameter, with computational analyses linking toxicity to their fundamental material characteristics was lacking. It was unclear if all CNT/F confer similar toxicity, in particular, genotoxicity. Nine CNT/F (MW #1-7 and CNF #1-2), commonly found in exposure assessment studies of U.S. facilities, were evaluated with reported diameters ranging from 6 to 150 nm. All materials were extensively characterized to include distributions of physical dimensions and prevalence of bundled agglomerates. Human bronchial epithelial cells were exposed to the nine CNT/F (0-24 mu g/ml) to determine cell viability, inflammation, cellular oxidative stress, micronuclei formation, and DNA double-strand breakage. Computational modeling was used to understand various permutations of physicochemical characteristics and toxicity outcomes. Results Analyses of the CNT/F physicochemical characteristics illustrate that using detailed distributions of physical dimensions provided a more consistent grouping of CNT/F compared to using particle dimension means alone. In fact, analysis of binning of nominal tube physical dimensions alone produced a similar grouping as all characterization parameters together. All materials induced epithelial cell toxicity and micronuclei formation within the dose range tested. Cellular oxidative stress, DNA double strand breaks, and micronuclei formation consistently clustered together and with larger physical CNT/F dimensions and agglomerate characteristics but were distinct from inflammatory protein changes. Larger nominal tube diameters, greater lengths, and bundled agglomerate characteristics were associated with greater severity of effect. The portion of tubes with greater nominal length and larger diameters within a sample was not the majority in number, meaning a smaller percentage of tubes with these characteristics was sufficient to increase toxicity. Many of the traditional physicochemical characteristics including surface area, density, impurities, and dustiness did not cluster with the toxicity outcomes. Conclusion Distributions of physical dimensions provided more consistent grouping of CNT/F with respect to toxicity outcomes compared to means only. All CNT/F induced some level of genotoxicity in human epithelial cells. The severity of toxicity was dependent on the sample containing a proportion of tubes with greater nominal lengths and diameters

    Doctors' personal health care choices: A cross-sectional survey in a mixed public/private setting

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    <p>Abstract</p> <p>Background</p> <p>Among Western countries, it has been found that physicians tend to manage their own illnesses and tend not have their own independent family physicians. This is recognized as a significant issue for both physicians and, by extension, the patients under their care, resulting in initiatives seeking to address this. Physicians' personal health care practices in Asia have yet to be documented.</p> <p>Methods</p> <p>An anonymous cross-sectional postal questionnaire survey was conducted in Hong Kong, China. All 9570 medical practitioners in Hong Kong registered with the Hong Kong Medical Council in 2003 were surveyed. Chi-square tests and logistic regression models were applied.</p> <p>Results</p> <p>There were 4198 respondents to the survey; a response rate of 44%. Two-thirds of respondents took care of themselves when they were last ill, with 62% of these self-medicating with prescription medication. Physicians who were graduates of Hong Kong medical schools, those working in general practice and non-members of the Hong Kong College of Family Physicians were more likely to do so. Physician specialty was found to be the most influential reason in the choice of caregiver by those who had ever consulted another medical practitioner. Only 14% chose consultation with a FM/GP with younger physians and non-Hong Kong medical graduates having a higher likelihood of doing so. Seventy percent of all respondents believed that having their own personal physician was unnecessary.</p> <p>Conclusion</p> <p>Similar to the practice of colleagues in other countries, a large proportion of Hong Kong physicians self-manage their illnesses, take self-obtained prescription drugs and believe they do not need a personal physician. Future strategies to benefit the medical care of Hong Kong physicians will have to take these practices and beliefs into consideration.</p

    From the Blazar Sequence to the Blazar Envelope: Revisiting the Relativistic Jet Dichotomy in Radio-loud AGN

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    We revisit the concept of a blazar sequence that relates the synchrotron peak frequency ({\nu}peak) in blazars with synchrotron peak luminosity (Lpeak, in {\nu}L{\nu}) using a large sample of radio-loud AGN. We present observational evidence that the blazar sequence is formed from two populations in the synchrotron {\nu}peak - Lpeak plane, each forming an upper edge to an envelope of progressively misaligned blazars, and connecting to an adjacent group of radio galaxies having jets viewed at much larger angles to the line of sight. When binned by jet kinetic power (Lkin; as measured through a scaling relationship with extended radio power), we find that radio core dominance decreases with decreasing synchrotron Lpeak, revealing that sources in the envelope are generally more misaligned. We find population-based evidence of velocity gradients in jets at low kinetic powers (~ 10^42-10^44.5 erg/s), corresponding to FR I radio galaxies and most BL Lacs. These low jet power 'weak jet' sources, thought to exhibit radiatively inefficient accretion, are distinguished from the population of non-decelerating, low synchrotron-peaking (LSP) blazars and FR II radio galaxies ('strong' jets) which are thought to exhibit radiatively efficient accretion. The two-population interpretation explains the apparent contradiction of the existence of highly core-dominated, low-power blazars at both low and high synchrotron peak frequencies, and further implies that most intermediate synchrotron peak (ISP) sources are not intermediate in intrinsic jet power between LSP and high synchrotron-peaking (HSP) sources, but are more misaligned versions of HSP sources with similar jet powers.Comment: 17 pages, 8 figures, 2 appendice

    The Seventh Data Release of the Sloan Digital Sky Survey

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    This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11663 deg^2 of imaging data, with most of the roughly 2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry over 250 deg^2 along the Celestial Equator in the Southern Galactic Cap. A coaddition of these data goes roughly two magnitudes fainter than the main survey. The spectroscopy is now complete over a contiguous area of 7500 deg^2 in the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog (UCAC-2), reducing the rms statistical errors at the bright end to 45 milli-arcseconds per coordinate. A systematic error in bright galaxy photometr is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat-fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. (Abridged)Comment: 20 pages, 10 embedded figures. Accepted to ApJS after minor correction

    Saturation genome editing of 11 codons and exon 13 of BRCA2 coupled with chemotherapeutic drug response accurately determines pathogenicity of variants.

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    The unknown pathogenicity of a significant number of variants found in cancer-related genes is attributed to limited epidemiological data, resulting in their classification as variant of uncertain significance (VUS). To date, Breast Cancer gene-2 (BRCA2) has the highest number of VUSs, which has necessitated the development of several robust functional assays to determine their functional significance. Here we report the use of a humanized-mouse embryonic stem cell (mESC) line expressing a single copy of the human BRCA2 for a CRISPR-Cas9-based high-throughput functional assay. As a proof-of-principle, we have saturated 11 codons encoded by BRCA2 exons 3, 18, 19 and all possible single-nucleotide variants in exon 13 and multiplexed these variants for their functional categorization. Specifically, we used a pool of 180-mer single-stranded donor DNA to generate all possible combination of variants. Using a high throughput sequencing-based approach, we show a significant drop in the frequency of non-functional variants, whereas functional variants are enriched in the pool of the cells. We further demonstrate the response of these variants to the DNA-damaging agents, cisplatin and olaparib, allowing us to use cellular survival and drug response as parameters for variant classification. Using this approach, we have categorized 599 BRCA2 variants including 93-single nucleotide variants (SNVs) across the 11 codons, of which 28 are reported in ClinVar. We also functionally categorized 252 SNVs from exon 13 into 188 functional and 60 non-functional variants, demonstrating that saturation genome editing (SGE) coupled with drug sensitivity assays can enhance functional annotation of BRCA2 VUS
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