2,090 research outputs found
Characterization of potential sources of magnetic anomalies within the crust in a tectonically active region: Amphibolites and migmatites from Potrillo Maar, New Mexico
The purpose was to characterize the oxide mineralogy and petrology of samples collected from Potrillo Maar, New Mexico with the goal of explaining the magnetic anamoly that is observed over this region from remote sensing. Potrillo Maar is a diatreme that has brought rocks from all depths in the crust to the surface almost instantaneously. The samples are therefore thought to be representative of the crust as it exists today below this portion of the Rio Grande Rift. It is generally believed that oxide minerals (magnetite, hematite, etc.) are responsible for the magnetic signature of the crust. The samples from Portillo Maar therefore offer a unique opportunity to examine the magnetic mineralogy of the entire crust. The results indicate that the magnetic anamoly observed over Rio Grande Rift may be consequence of the tectonic activity that caused mylonitization of the rocks and allowed the infiltration of oxidizing fluids
A BAYESIAN HIERARCHICAL FRAMEWORK FOR SPATIAL MODELING OF fMRI DATA
Functional neuroimaging techniques enable investigations into the neural basis of human cognition, emotions, and behaviors. In practice, applications of functional magnetic resonance imaging (fMRI) have provided novel insights into the neuropathophysiology of major psychiatric,neurological, and substance abuse disorders, as well as into the neural responses to their treatments. Modern activation studies often compare localized task-induced changes in brain activity between experimental groups. One may also extend voxel-level analyses by simultaneously considering the ensemble of voxels constituting an anatomically defined region of interest (ROI) or by considering means or quantiles of the ROI. In this work we present a Bayesian extension of voxel-level analyses that offers several notable benefits. First, it combines whole-brain voxel-by-voxel modeling and ROI analyses within a unified framework. Secondly, an unstructured variance/covariance for regional mean parameters allows for the study of inter-regional functional connectivity, provided enough subjects are available to allow for accurate estimation. Finally, an exchangeable correlation structure within regions allows for the consideration of intra-regional functional connectivity. We perform estimation for our model using Markov Chain Monte Carlo (MCMC) techniques implemented via Gibbs sampling which, despite the high throughput nature of the data, can be executed quickly (less than 30 minutes). We apply our Bayesian hierarchical model to two novel fMRI data sets: one considering inhibitory control in cocaine-dependent men and the second considering verbal memory in subjects at high risk for Alzheimerâs disease. The unifying hierarchical model presented in this manuscript is shown to enhance the interpretation content of these data sets
Strontium Isotope Zoning in Garnet: Implications for Metamorphic Matrix Equilibration, Geochronology and Phase Equilibrium Modelling
In principle, garnet growth rates may be calculated from 87Rb/86Sr and 87Sr/86Sr measurements in garnet subsamples and the surrounding rock matrix. Because of low Rb/Sr, garnet should passively record the matrix decay of 87Rb to 87Sr as a progressive increase in 87Sr/86Sr from core to rim. This concept was tested by collecting Rb-Sr data for five garnet grains from four major orogenic belts: eastern Vermont (c. 380 Ma), western New Hampshire (c. 320 Ma), southern Chile (c. 75 Ma) and northwestern Italy (c. 35 Ma). Both normal Sr isotope zoning (increasing 87Sr/86Sr from core to rim) and inverse Sr zoning (decreasing 87Sr/86Sr from core to rim) were observed. Garnet and matrix isotope data commonly yielded grossly inaccurate model ages. Incomplete Rb and Sr equilibration among matrix minerals is invoked to explain the deviations between theoretical v. measured zoning patterns and the age disparities. Initially, the reactive matrix is dominated by rapidly equilibrating Rb-rich mica, which imparts high 87Sr/86Sr values in garnet cores. Progressive participation of slower equilibrating Sr-rich plagioclase buffers or even reduces 87Sr/86Sr, possibly leading to flat or decreasing 87Sr/86Sr from garnet cores to rims. Unusually high 87Sr/86Sr in garnet in combination with bulk matrix compositions causes erroneously young apparent ages, so metamorphic ages, growth rates, and associated heating and loading rates are likely suspect. Although Rb-Sr may be the most susceptible because of the profound disparities between mica and feldspar, zircon reactivity might influence the Lu-Hf system by up to a few per cent. The Sm-Nd system seems generally immune to these effects. Pseudosection analysis and conventional garnet geochronology, which presume complete matrix equilibration during metamorphism, may require modification to account for differences between whole-rock v. reactive matrix compositions
Accessory Mineral Eu Anomalies in Suprasolidus Rocks: Beyond Feldspar
Accessory mineral Eu anomalies (Eu/Eu*) are routinely measured to infer changes in the amount of feldspar over time, allowing accessory mineral UâPb dates to be linked to the progressive crystallization of igneous and metamorphic rocks and, by extension, geodynamic processes. However, changes in Eu/Eu* can reflect any process that changes the relative availability of Eu2+ and Eu3+. We constructed partitioning budgets for Sm, Eu2+, Eu3+, and Gd in suprasolidus metasedimentary rocks to investigate processes that can influence accessory mineral Eu anomalies. We modeled three scenarios: (1) closedâsystem, equilibrium crystallization; (2) fractionation of Eu by feldspar growth during melt crystallization; and (3) removal of Eu by melt extraction. In the closedâsystem equilibrium model, accessory mineral Eu/Eu* changes as a function of fO2 and monazite stability; Eu/Eu* changes up to 0.3 over a pressureâtemperature range of 4â12 kbar and 700â950°C. Fractionation of Eu by feldspar growth is modeled to decrease accessory mineral Eu/Eu* by ~0.05â0.15 per 10 wt% feldspar crystallized. Melt extraction has a smaller effect; removal of 10% melt decreases accessory mineral Eu/Eu* in the residue by â€0.05. Although these models demonstrate that fractionation of Eu by feldspar growth can be a dominant control on a rocks u budget, they also show that the common interpretation that Eu/Eu* only records feldspar growth and breakdown is an oversimplification that could lead to incorrect interpretation about the duration and rates of tectonic processes. Consideration of other processes that influence Eu anomalies will allow for a broader range of geological processes to be investigated by petrochronology.Plain Language SummaryMetamorphic rocksârocks in which new minerals grew in response to increase in pressure and temperature related to deep burial or subductionâand igneous rocksârocks that formed as magmas cool and crystallizeâprovide a direct record of how Earthâs continents have moved and changed through time. To read this record, geologists need to be able to measure the ages of metamorphism and magmatism: When did it happen? How long did it last? How does it relate to other rocks around the world? A common approach to addressing these questions is using UâPb dating of the minerals zircon, monazite, and apatite. The elements these minerals incorporate are indicative of how hot and how deep in the Earth they were when they grew. In this study we explore how geologists can use the concentrations of the element Europium (Eu) in these minerals to provide new insights into the geological meaning of UâPb dates, leading to more robust interpretations of Earthâs plate tectonic history.Key PointsEu anomalies in suprasolidus rocks record any process that changes the relative availability of Eu2+ and Eu3+, not just feldspar growthDisequilibrium is required for feldspar growth to strongly influence accessory mineral Eu anomaliesComparing accessory mineral Eu anomalies and Sr concentrations leads to more robust interpretation than evaluating Eu anomalies alonePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/1/ggge22268_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/3/ggge22268.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/2/ggge22268-sup-0001-2020GC009052-Text_SI-S01.pd
Giant resonances in exotic spherical nuclei within the RPA approach with the Gogny force
Theoretical results for giant resonances in the three doubly magic exotic
nuclei Ni, Sn and Sn are obtained from Hartree-Fock (HF)
plus Random Phase Approximation (RPA) calculations using the D1S
parametrization of the Gogny two-body effective interaction. Special attention
is paid to full consistency between the HF field and the RPA particle-hole
residual interaction. The results for the exotic nuclei, on average, appear
similar to those of stable ones, especially for quadrupole and octupole states.
More exotic systems have to be studied in order to confirm such a trend. The
low energy of the monopole resonance in Ni suggests that the compression
modulus in this neutron rich nucleus is lower than the one of stable ones.Comment: 16 pages, 10 figure
Libby Amphibole Contamination in Tree Bark Surrounding Historical Vermiculite Processing Facilities
Over a 70-year period, a mine near Libby, MT supplied nearly 80% of the worldâs vermiculite. Raw vermiculite, which was contaminated with naturally occurring amphibole in veins throughout the deposit, was shipped to processing sites throughout the United States for exfoliation. In this pilot study, tree bark samples were collected near processing facili-ties in Spokane, WA, Santa Ana, CA, Newark, CA, and Phoenix, AZ in an effort to determine if areas surrounding these facilities are today contaminated with Libby amphibole asbestos (AA). From areas surrounding each of the four his-torical processing sites, Libby AA was detected in a subset of the bark samples. At the Santa Ana, Newark and Phoenix facilities, actinolite-tremolite and other high Fe Ca-bearing amphibole were also measured from the bark samples. In addition, chrysotile was frequently measured in samples collected from each of the sites. From the results of this pilot study, it is evident that tree bark can serve as reservoirs of asbestos, and indicators of past and current contamination. These data also suggest that areas outside of these historical processing facilities may today have some level of existing contamination resulting from the operation of these facilities
Dual G9A/EZH2 inhibition stimulates anti-tumour immune response in ovarian high-grade serous carcinoma
Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumour immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10-CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells whilst suppressing tumour-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1-005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1-005 improved the survival of mice bearing Trp53-/- null ID8 ovarian tumours and resulted in tumour burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumour growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development
Entrances and exits: changing perceptions of primary teaching as a career for men
Original article can be found at: http://www.informaworld.com/smpp/title~content=t713640830~db=all Copyright Informa / Taylor and Francis. DOI: 10.1080/03004430802352087The number of men in teaching has always been small, particularly in early childhood, but those that do come into teaching usually do so for the same reasons as women, namely enjoyment of working with children, of wanting to teach and wanting to make a difference to children's lives. However, in two separate studies, the authors have shown that on beginning teacher training in 1998, and at the point of leaving the profession in 2005, men and women tend to emphasise different concerns. This article will explore those differences and seek possible explanations for how men's views of teaching might be changing over time.Peer reviewe
Pharmacological depletion of RNA splicing factor RBM39 by indisulam synergizes with PARP inhibitors in high-grade serous ovarian carcinoma
Ovarian high-grade serous carcinoma (HGSC) is the most common subtype of ovarian cancer with limited therapeutic options and a poor prognosis. In recent years, poly-ADP ribose polymerase (PARP) inhibitors have demonstrated significant clinical benefits, especially in patients with BRCA1/2 mutations. However, acquired drug resistance and relapse is a major challenge. Indisulam (E7070) has been identified as a molecular glue that brings together splicing factor RBM39 and DCAF15 E3 ubiquitin ligase resulting in polyubiquitination, degradation, and subsequent RNA splicing defects. In this work, we demonstrate that the loss of RBM39 induces splicing defects in key DNA damage repair genes in ovarian cancer, leading to increased sensitivity to cisplatin and various PARP inhibitors. The addition of indisulam also improved olaparib response in mice bearing PARP inhibitor-resistant tumors. These findings demonstrate that combining RBM39 degraders and PARP inhibitors is a promising therapeutic approach to improve PARP inhibitor response in ovarian HGSC
Social enterprise in the UK : models and trajectories (ICSEM Working Papers No. 40)
This paper begins by describing (in part A) the UK concept of social enterprise and how it is operationalised (section A.1); this is followed by an overview of the challenges of estimating the population of social enterprise in the UK, despite or because of different government-sponsored surveys (section A.2); this first part concludes with a review of the evolution of policy discourse for social enterprise (section A.3). The second part of the paper goes on to describe (sections B.1 to B.4) the different models that have evolved from different origins in the UK (with the main emphasis being on experience in England); in order to contextualise an understanding of these models, it describes three fields (section B.5)âwork integration, community development, and public services; these illustrate the fluidity of models in the UK, where typically different models may be found within each field. Finally, Part C describes at a general level the relevant institutional frameworks and trajectories of the main social enterprise models
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