CAN-HK : An a priori crustal model for the Canadian Shield

ACKNOWLEDGMENTS The United Kingdom component of the Hudson Bay Lithospheric Experiment (HuBLE) was supported by the Natural Environment Research Council (NERC) Grant Number NE/F007337/1, with financial and logistical support from the Geological Survey of Canada (GSC), Canada-Nunavut Geoscience Office (CNGO), SEIS-UK (the seismic node of NERC), and the First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. I. D. B. was funded by the Leverhulme Trust and acknowledges support through Grant Number RPG-2013- 332. The authors thank three anonymous reviewers for their constructive comments.Peer reviewe

The case for evidence-based policy to support stress-resilient cropping systems

Research and the dissemination of evidence-based guidelines for best practice in crop production are fundamental for the protection of our crop yields against biotic and abiotic threats, and for meeting ambitious food production targets by 2050. The advances in knowledge required for sustaining crop productivity targets will be gained through three research tracks: (1) basic strategic research in the field, for example, crop breeding, agronomy, and advanced phenotyping; (2) translational research involving the application of advances in fundamental science; and (3) pure fundamental research to fuel future translational research. We propose that policy and funding structures need to be improved to facilitate and encourage more interactions between scientists involved in all three research tracks, and also between researchers and farmers, to improve the effectiveness of delivering improvements in crop stress resilience. History illustrates that it is challenging for public researchers to “stretch across” all of these research tracks, with effective farm-level solutions being more likely when end-users and industry are directly engaged in the research pipeline. As research proceeds from fundamental through to applied research, the demand for experimental rigor and a wider understanding of appropriate methods and outcomes is paramount, that is, demonstrating value in yield at the field level requires the input of experienced practitioners from each research track. The development of evidence-based policies to support all funding structures and the engagement of producers with both the development of research, and with the findings of such research, will form an important capability in meeting food security targets. This commentary, concentrating on the development of policies to support research and its dissemination, is based on discussions held at the Stress Resilience Symposium organized by the Global Plant Council and Society of Experimental Biology in October 2015.Matthew Gilliham, Scott Chapman, Lisa Martin, Sarah Jose and Ruth Basto

Rapid detection of arsenic minerals using portable broadband NQR

The remote real-time detection of specific arsenic species would significantly benefit in minerals processing to mitigate the release of arsenic into aquatic environments and aid in selective mining. At present, there are no technologies available to detect arsenic minerals in bulk volumes outside of laboratories. Here we report on the first room-temperature broadband 75As nuclear quadrupole resonance (NQR) detection of common and abundant arsenic ores in the Earth crust using a large sample (0.78 L) volume prototype sensor. Broadband excitation aids in detection of natural minerals with low crystallinity. We briefly discuss how the proposed NQR detector could be employed in mining operations. Key Points Transformation of chemical analysis method to geophysical detection technologyFirst NQR ore characterization of selected arsenic minerals in bulk volumesBroadband NQR sensor to detect arsenic minerals with low crystallinit

Atypical chemokine receptor 4 shapes activated B cell fate

Activated B cells can initially differentiate into three functionally distinct fates-early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells-by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell-intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate

Hydrous upwelling across the mantle transition zone beneath the Afar Triple Junction

The mechanisms that drive the upwelling of chemical heterogeneity from the lower to upper mantle (e.g., thermal versus compositional buoyancy) are key to our understanding of whole mantle con- vective processes. We address these issues through a receiver function study on new seismic data from recent deployments located on the Afar Triple Junction, a location associated with deep mantle upwelling. The detailed images of upper mantle and mantle transition zone structure illuminate features that give insights into the nature of upwelling from the deep Earth. A seismic low-velocity layer directly above the mantle transition zone, interpreted as a stable melt layer, along with a prominent 520 km discontinuity sug- gest the presence of a hydrous upwelling. A relatively uniform transition zone thickness across the region suggests a weak thermal anomaly (<100 K) may be present and that upwelling must be at least partly driven by compositional buoyancy. The results suggest that the lower mantle is a source of volatile rich, chemically distinct upwellings that influence the structure of the upper mantle, and potentially the chemis- try of surface lavas

Seismic imaging of the Alaska Subduction Zone: implications for slab geometry and volcanism

Alaska has been a site of subduction and terrane accretion since the mid‐Jurassic. The area features abundant seismicity, active volcanism, rapid uplift, and broad intraplate deformation, all associated with subduction of the Pacific plate beneath North America. The juxtaposition of a slab edge with subducted, overthickened crust of the Yakutat terrane beneath central Alaska is associated with many enigmatic volcanic features. The causes of the Denali Volcanic Gap, a 400‐km‐long zone of volcanic quiescence west of the slab edge, are debated. Furthermore, the Wrangell Volcanic Field, southeast of the volcanic gap, also has an unexplained relationship with subduction. To address these issues, we present a joint ambient noise, earthquake‐based surface wave, and P‐S receiver function tomography model of Alaska, along with a teleseismic S wave velocity model. We compare the crust and mantle structure between the volcanic and nonvolcanic regions, across the eastern edge of the slab and between models. Low crustal velocities correspond to sedimentary basins, and several terrane boundaries are marked by changes in Moho depth. The continental lithosphere directly beneath the Denali Volcanic Gap is thicker than in the adjacent volcanic region. We suggest that shallow subduction here has cooled the mantle wedge, allowing the formation of thick lithosphere by the prevention of hot asthenosphere from reaching depths where it can interact with fluids released from the slab and promote volcanism. There is no evidence for subducted material east of the edge of the Yakutat terrane, implying the Wrangell Volcanic Field formed directly above a slab edge

Open Education and the emancipation of academic labour

I have previously argued that open education is a liberal project with a focus on the freedom of things rather than the freedom of people (Winn, Joss. 2012. “Open Education: From the Freedom of Things to the Freedom of People.” In Towards Teaching in Public: Reshaping the Modern University, edited by Michael Neary, Howard Stevenson, and Les Bell, 133– 147. London: Continuum). Furthermore, I have argued that despite an implicit critique of private property with its emphasis on ‘the commons’, the literature on open education offers no corresponding critique of academic labour (Neary, Mike, and Joss Winn. 2012. “Open Education: Common(s), Commonism and the New Common Wealth.” Ephemera: Theory & Politics in Organization 12 (4): 406–422). In this paper, I develop my critical position that an emancipatory form of education must work towards the emancipation of teachers and students from labour, the dynamic, social, creative source of value in capitalism. In making this argument, I first establish the fundamental characteristics of academic labour. I then offer a ‘form-analytic’ critique of open access, followed by a corresponding critique of its legal form. Finally, I critically discuss the potential of ‘open cooperatives’ as a transitional organisational form for the production of knowledge through which social relations become ‘transparent in their simplicity’ (Marx, Karl. 1976. Capital, Vol. 1. London: Penguin Classics, 172)

Comparison of Illumina and 454 Deep Sequencing in Participants Failing Raltegravir-Based Antiretroviral Therapy

Background: The impact of raltegravir-resistant HIV-1 minority variants (MVs) on raltegravir treatment failure is unknown. Illumina sequencing offers greater throughput than 454, but sequence analysis tools for viral sequencing are needed. We evaluated Illumina and 454 for the detection of HIV-1 raltegravir-resistant MVs. Methods: A5262 was a single-arm study of raltegravir and darunavir/ritonavir in treatment-naïve patients. Pre-treatment plasma was obtained from 5 participants with raltegravir resistance at the time of virologic failure. A control library was created by pooling integrase clones at predefined proportions. Multiplexed sequencing was performed with Illumina and 454 platforms at comparable costs. Illumina sequence analysis was performed with the novel snp-assess tool and 454 sequencing was analyzed with V-Phaser. Results: Illumina sequencing resulted in significantly higher sequence coverage and a 0.095% limit of detection. Illumina accurately detected all MVs in the control library at ≥0.5% and 7/10 MVs expected at 0.1%. 454 sequencing failed to detect any MVs at 0.1% with 5 false positive calls. For MVs detected in the patient samples by both 454 and Illumina, the correlation in the detected variant frequencies was high (R2 = 0.92, P<0.001). Illumina sequencing detected 2.4-fold greater nucleotide MVs and 2.9-fold greater amino acid MVs compared to 454. The only raltegravir-resistant MV detected was an E138K mutation in one participant by Illumina sequencing, but not by 454. Conclusions: In participants of A5262 with raltegravir resistance at virologic failure, baseline raltegravir-resistant MVs were rarely detected. At comparable costs to 454 sequencing, Illumina demonstrated greater depth of coverage, increased sensitivity for detecting HIV MVs, and fewer false positive variant calls

Sulfide melts and long-term low seismic wavespeeds in lithospheric and asthenospheric mantle

Some studies of lithospheric and asthenospheric seismic structure, report mantle velocities as low as ∼4% below the reference models used. While these low wavespeeds may be attributed to thermal effects in tectonically young or actively volcanic regions, in older, tectonically stable regions low velocity anomalies apparently persist even past the decay time of any thermal perturbation, rendering such a mechanism implausible. Low volume melts can also reduce wavespeeds, but their buoyancy should drain them upward away from source regions, preventing significant accumulation if they are able to segregate. Sulfide, ubiquitous as inclusions in lithospheric mantle xenoliths, forms dense, non-segregating melts at temperatures and volatile fugacities characteristic of even old lithospheric mantle. We show that 1–5 volume percent sulfide melts can act to permanently create reductions up to 5.5% in seismic wavespeeds in areas of the lithosphere and the asthenosphere disturbed by prior melting events that carry and concentrate sulfide