Regional and temporal variability of melts during a Cordilleran magma pulse: Age and chemical evolution of the Jurassic arc, eastern Mojave Desert, California

Intrusive rock sequences in the central and eastern Mojave Desert segment of the Jurassic Cordilleran arc of the western United States record regional and temporal variations in magmas generated during the second prominent pulse of Mesozoic continental arc magmatism. U/Pb zircon ages provide temporal control for describing variations in rock and zircon geochemistry that reflect differences in magma source components. These source signatures are discernible through mixing and fractionation processes associated with magma ascent and emplacement. The oldest well-dated Jurassic rocks defining initiation of the Jurassic pulse are a 183 Ma monzodiorite and a 181 Ma ignimbrite. Early to Middle Jurassic intrusive rocks comprising the main stage of magmatism include two high-K calc-alkalic groups: to the north, the deformed 183–172 Ma Fort Irwin sequence and contemporaneous rocks in the Granite and Clipper Mountains, and to the south, the 167–164 Ma Bullion sequence. A Late Jurassic suite of shoshonitic, alkali-calcic intrusive rocks, the Bristol Mountains sequence, ranges in age from 164 to 161 Ma and was emplaced as the pulse began to wane. Whole-rock and zircon trace-element geochemistry defines a compositionally coherent Jurassic arc with regional and secular variations in melt compositions. The arc evolved through the magma pulse by progressively greater input of old cratonic crust and lithospheric mantle into the arc magma system, synchronous with progressive regional crustal thickening

Subduction Initiation and Early Evolution of the Easton Metamorphic Suite, Northwest Cascades, Washington

The Easton metamorphic suite, in the northwest Cascades of Washington State, preserves an inverted metamorphic sequence with ultramafic rocks underlain by amphibolite and high-temperature blueschist juxtaposed above low-temperature blueschists. The sequence is interpreted as a metamorphic sole and younger accreted rocks that formed during and after the initiation of Farallon plate subduction beneath North America in Jurassic time. Two high-temperature deformation events are recorded in the metamorphic sole at ∼10 kbar and ∼760 °C to 590 °C between \u3e167 and 164 Ma. High-temperature blueschist partly overprints the amphibolite but may have accreted separately at ∼530 °C between ca. 165 and 163 Ma. Retrograde metamorphism and post-tectonic white mica record cooling of the metamorphic sole to ∼350 °C by ca. 160 Ma. Subsequent underplating of the Darrington Phyllite occurred at ∼7 kbar and ∼320 °C prior to ca. 148 Ma until at least ca. 142 Ma. Blueschist-facies conditions and exhumation to ∼5 kbar occurred between ca. 140 and 136 Ma during later accretion and deformation of Shuksan greenschist-blueschist. Cooling ages from the high-temperature metamorphic sole require that subduction began prior to 167 Ma, before or during the formation of ophiolite-related rocks within the Northwest Cascades thrust system. Rapid cooling of the metamorphic sole below 400 °C until ca. 157 Ma through combined thermal relaxation of the subduction zone and partial exhumation was followed by at least 26 m.y. of a steady thermal state as younger units were accreted and exhumed. The record of high-pressure–low-temperature metamorphism suggests that the Easton metamorphic suite formed in a large ocean basin rather than an arc-proximal marginal basin. The metamorphic history also argues against previously suggested correlations of the Easton metamorphic suite with units of the Franciscan complex to the south in California. The temperature-time history of the Easton suite is consistent with models for the early evolution of subduction zones

Ethical Issues in the Development of Readiness Cohorts in Alzheimer's Disease Research.

There is growing interest in the development of novel approaches to secondary prevention trials in Alzheimer's disease to facilitate screening and recruitment of research participants and to reduce the time and costs associated with clinical trials. Several international research collaborations are setting up research infrastructures that link existing research cohorts, studies or patient registries to establish 'trial-ready' or 'readiness' cohorts. From these cohorts, individuals are recruited into clinical trial platforms. In setting up such research infrastructures, researchers must make ethically challenging design decisions in at least three areas: re-contacting participants in existing research studies, obtaining informed consent for participation in a readiness cohort, and disclosure of Alzheimer's disease-related biomarkers. These ethical considerations have been examined by a dedicated workgroup within the European Prevention of Alzheimer's Dementia (EPAD) project, a trans-European longitudinal cohort and adaptive proof-of-concept clinical trial platform. This paper offers recommendations for the ethical management of re-contact, informed consent and risk disclosure which may be of value to other research collaborations in the process of developing readiness cohorts for prevention trials in Alzheimer's disease and other disease areas.This work was funded through the Ethical Legal and Social Implications work package of the European Prevention of Alzheimer’s Dementia (EPAD) study EPAD receives support from the Innovative Medicines Initiative Joint Undertaking under grant agreement n° 115736, resources of which are composed of financial contribution from the European Union’s Seventh Framework Programme (FP7/2007-2013) and EFPIA companies’ in kind contribution. RM was also funded through the UK National Institute of Health Research grant to the Cambridge Biomedical Research Centre

An analysis of passive earth pressure modification due to seepage flow effects

Using an assumed vertical retaining wall with a drainage system along the soil-structure interface, this paper analyses the effect of anisotropic seepage flow on the development of passive earth pressure. Extremely unfavourable seepage flow inside the backfill, perhaps due to heavy rainfall, will dramatically increase the active earth pressure while reducing the passive earth pressure; thus increasing the probability of instability of the retaining structure. In this paper, a trial and error analysis based on limit equilibrium is applied to identify the optimum failure surface. The flow field is computed using Fourier series expansion, and the effective reaction force along the curved failure surface is obtained by solving a modified Kötter equation considering the effect of seepage flow. This approach correlates well with other existing results. For small values of both the internal friction angle and the interface friction angle, the failure surface can be appropriately simplified with a planar approximation. A parametric study indicates that the degree of anisotropic seepage flow affects the resulting passive earth pressure. In addition, incremental increases in the effective friction angle and interface friction both lead to an increase in the passive earth pressure.National Key Basic Research Program of China (No. 2015CB057801), the National Key R & D program of China (No. 2016YFC0800204), and Natural Science Foundation of China (Nos. 51578499 & 51761130078)

'Exacerbation-free time' to assess the impact of exacerbations in patients with chronic obstructive pulmonary disease (COPD):a prospective observational study

COPD exacerbations are commonly quantified as rate per year. However, the total amount of time a patient suffers from exacerbations may be stronger related to his or her disease burden than just counting exacerbation episodes. In this study, we examined the relationship between exacerbation frequency and exacerbation-free time, and their associations with baseline characteristics and health-related quality of life. A total of 166 COPD patients reported symptom changes during 12 months. Symptom-defined exacerbation episodes were correlated to the number of exacerbation-free weeks per year. Analysis of covariance was used to examine the effects of baseline characteristics on annual exacerbation frequency and exacerbation-free weeks, Spearman's rank correlations to examine associations between the two methods to express exacerbations and the Chronic Respiratory Questionnaire (CRQ). The correlation between exacerbation frequency and exacerbation-free weeks was -0.71 (p < 0.001). However, among frequent exacerbators (i.e., ≥3 exacerbations/year, n = 113) the correlation was weak (r = -0.25; p < 0.01). Smokers had less exacerbation-free weeks than non-smokers (β = -5.709, p < 0.05). More exacerbation-free weeks were related to better CRQ Total (r = 0.22, p < 0.05), Mastery (r = 0.22, p < 0.05), and Fatigue (r = 0.23, p < 0.05) scores, whereas no significant associations were found between exacerbation frequency and CRQ scores. In COPD patients with frequent exacerbations, there is substantial variation in exacerbation-free time. Exacerbation-free time may better reflect the burden of exacerbations in patients with COPD than exacerbation frequency does

U-Pb and Hf Isotopic Evidence for an Arctic Origin of Terranes in Northwestern Washington

New field, U-Pb, and Lu-Hf zircon data constrain the geologic history, age, and origin of the Yellow Aster Complex (YAC) in northwestern Washington, providing insight into the tectonic history of this and related Paleozoic arc terranes of the western North American Cordillera. Mapping shows that the oldest YAC rocks consist of quartzofeldspathic paragneiss (meta-arkose) and quartzose calc-silicate paragneiss (metacalcareous siltstone) in gradational contact. Paragneisses are cut by syn-tectonic and post-tectonic intrusions and faulted against granitic orthogneiss. U-Pb zircon results show that (1) maximum depositional ages of paragneisses are Silurian to Early Devonian (432– 390 Ma); (2) detrital zircons from quartzose calc-silicate paragneisses show a broad age peak from 1900 to 1000 Ma, while quartzofeldspathic paragneisses contain several distinct Precambrian age peaks, including at 2.0–1.8 Ga and 2.5–2.4 Ga; (3) paragneisses contain early Paleozoic grains with peaks ca. 420–400 and ca. 460–440 Ma; (4) pre-tectonic orthogneiss and syn-tectonic and post-tectonic dikes range from ca. 410–406 Ma; and (5) intrusive rocks contain apparently xenocrystic ca. 480–440 Ma grains. Lu-Hf isotope data show that nearly all Paleozoic zircons have negative εHf(t) values, and zircons in the meta-arkose samples are more negative than those in the calc-silicate. Zircons in several meta-arkose samples yield εHf(t) values of –40 to –57, rare in the North American Cordillera, and requires the involvement of Mesoarchean to Eoarchean crustal components. The most likely source region with crust as old as Eoarchean and early Paleozoic magmatism is the Greenland Caledonides, which implies derivation from the Arctic margin of northeastern Laurentia or Baltica. The chemistry and petrology of the igneous rocks suggest that the terrane was in a continental arc setting before, during, and after deposition of the sedimentary rocks. The data constrain deformation, metamorphism, and magmatism in the YAC to a brief period in the Early Devonian, from ca. 410 to 400 Ma. Age and Hf patterns of the YAC are similar to elements of the Yukon-Tanana and Alexander terranes. Our study shows that the complex history of metamorphosed terranes requires analysis of multiple isotopic and petrologic proxies, and U-Pb analysis of both igneous (n = 50) and detrital (n = 400) zircons to confirm or refute terrane and provenance correlations

The Future of Psychopharmacological Enhancements: Expectations and Policies

The hopes and fears expressed in the debate on human enhancement are not always based on a realistic assessment of the expected possibilities. Discussions about extreme scenarios may at times obscure the ethical and policy issues that are relevant today. This paper aims to contribute to an adequate and ethically sound societal response to actual current developments. After a brief outline of the ethical debate concerning neuro-enhancement, it describes the current state of the art in psychopharmacological science and current uses of psychopharmacological enhancement, as well as the prospects for the near future. It then identifies ethical issues regarding psychopharmacological enhancements that require attention from policymakers, both on the professional and on the governmental level. These concern enhancement research, the gradual expansion of medical categories, off-label prescription and responsibility of doctors, and accessibility of enhancers on the Internet. It is concluded that further discussion on the advantages and drawbacks of enhancers on a collective social level is still needed

Quality of spirometry and related diagnosis in primary care with a focus on clinical use

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