1,199 research outputs found
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2009.The radionuclides 231Pa and 230Th, produced in the water column and
removed from the ocean by particle scavenging and burial in sediments, offer a
means for paleoceanographers to examine past dynamics of both water column and
sedimentary processes. I show for the first time that a state of balance exists
between 230Th production and burial in the Central Arctic basins, based on
measured sedimentary 230Thxs inventories in box cores, establishing this nuclideâs
utility as a paleoceanographic indicator of sedimentary processes and as a
normalization tool. I present the first 230Th-normalized particle fluxes calculated for
the central Arctic: vertical particle fluxes were extremely low during the late glacial,
rose during the deglaciation due to particle inputs from shelf inundation, increased
productivity and ice-rafted debris, and fell again following the establishment of
interglacial conditions. A major event of lateral sediment redistribution, inferred
from surplus 230Thxs inventories, occurred in the Makarov Basin during the
deglaciation and may have been due to destabilization of slope and shelf sediments
as sea level rose.
I present the first high-resolution, radiocarbon-dated downcore records of
sedimentary 231Pa/230Th from the Arctic Ocean. Low ratios indicate that 231Pa was
exported from all sites during the late glacial period, with export decreasing during
the deglaciation and Holocene. 231Pa/230Th measurements in cores from three
continental slope sites show no evidence for a 231Pa sink related to boundary
scavenging on the continental slopes. Holocene 231Pa/230Th ratios show a very
significant variation by depth, with strong export of 231Pa at deep sites but little or
no export at shallow sites, a result which echoes findings for the South Atlantic and
the Pacific. The Arctic thus appears fundamentally similar to other ocean basins in
its 231Pa and 230Th dynamics, despite its peculiar qualities of sea ice cover, low
particle flux, and relatively isolated deep waters.My graduate work has been funded by NSF grants OCE-0402565 and OCE-
0550637 to Jerry McManus, ARC-0520073 to Bill Curry, and OCE-0118126 to Daniel
McCorkle. My graduate education was also supported by an IODP Schlanger Ocean
Drilling Fellowship, WHOI Fellowships from the WHOI Academic Programs Office, and
an MIT Presidential Fellowship
Health-related preferences of older patients with multimorbidity: the protocol for an evidence map
Introduction: Interaction of conditions and treatments, complicated care needs and substantial treatment burden make patientâphysician encounters involving multimorbid older patients highly complex. To optimally integrate patientsâ preferences, define and prioritise realistic treatment goals and individualise care, a patient-centred approach is recommended. However, the preferences of older patients, who are especially vulnerable and frequently multimorbid, have not been systematically investigated with regard to their health status. The purpose of this evidence map is to explore current research addressing health-related preferences of older patients with multimorbidity, and to identify the knowledge clusters and research gaps.
Methods and analysis: To identify relevant research, we will conduct searches in the electronic databases MEDLINE, EMBASE, PsycINFO, PSYNDEX, CINAHL, Social Science Citation Index, Social Science Citation Index Expanded and the Cochrane library from their inception. We will check reference lists of relevant articles and carry out cited reference research (forward citation tracking). Two independent reviewers will screen titles and abstracts, check full texts for eligibility and extract the data. Any disagreement will be resolved and consensus reached with the help of a third reviewer. We will include both qualitative and quantitative studies, and address preferences from the patientsâ perspectives in a multimorbid population of 60 years or older. There will be no restrictions on the publication language. Data extraction tables will present study and patient characteristics, aim of study, methods used to identify preferences and outcomes (ie, type of preferences). We will summarise the data using tables and figures (ie, bubble plot) to present the research landscape and to describe clusters and gaps.
Ethics and dissemination: Due to the nature of the proposed evidence map, ethics approval will not be required. Results from our research will be disseminated by means of specifically prepared materials for patients, at relevant (inter)national conferences and via publication in peer-reviewed journals
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Evidence Synthesis of Observational Studies in Environmental Health: Lessons Learned from a Systematic Review on Traffic-Related Air Pollution.
BACKGROUND: There is a long tradition in environmental health of using frameworks for evidence synthesis, such as those of the U.S. Environmental Protection Agency for its Integrated Science Assessments and the International Agency for Research on Cancer Monographs. The framework, Grading of Recommendations Assessment, Development, and Evaluation (GRADE), was developed for evidence synthesis in clinical medicine. The U.S. Office of Health Assessment and Translation (OHAT) elaborated an approach for evidence synthesis in environmental health building on GRADE. METHODS: We applied a modified OHAT approach and a broader narrative assessment to assess the level of confidence in a large systematic review on traffic-related air pollution and health outcomes. DISCUSSION: We discuss several challenges with the OHAT approach and its implementation and suggest improvements for synthesizing evidence from observational studies in environmental health. We consider the determination of confidence using a formal rating scheme of up- and downgrading of certain factors, the treatment of every factor as equally important, and the lower initial confidence rating of observational studies to be fundamental issues in the OHAT approach. We argue that some observational studies can offer high-confidence evidence in environmental health. We note that heterogeneity in magnitude of effect estimates should generally not weaken the confidence in the evidence, and consistency of associations across study designs, populations, and exposure assessment methods may strengthen confidence in the evidence. We mention that publication bias should be explored beyond statistical methods and is likely limited when large and collaborative studies comprise most of the evidence and when accrued over several decades. We propose to identify possible key biases, their most likely direction, and their potential impacts on the results. We think that the OHAT approach and other GRADE-type frameworks require substantial modification to align better with features of environmental health questions and the studies that address them. We emphasize that a broader, narrative evidence assessment based on the systematic review may complement a formal GRADE-type evaluation. https://doi.org/10.1289/EHP11532
The role of historical context in understanding past climate, pollution and health data in trans-disciplinary studies: reply to comments on More et al. 2017
Understanding the context from which evidence emerges is of paramount importance in reaching robust conclusions in scientific inquiries. This is as true of the present as it is of the past. In a transâdisciplinary study such as More et al. (2017, https://doi.org/10.1002/2017GH000064) and many others appearing in this and similar journals, a proper analysis of context demands the use of historical evidence. This includes demographic, epidemiological, and socioâeconomic dataâcommon in many studies of the impact of anthropogenic pollution on human healthâand, as in this specific case, also geoarchaeological evidence. These records anchor climate and pollution data in the geographic and human circumstances of history, without which we lose a fundamental understanding of the data itself. This article addresses Hinkley (2018, https://doi.org/10.1002/2018GH000105) by highlighting the importance of context, focusing on the historical and archaeological evidence, and then discussing atmospheric deposition and circulation in the specific region of our study. Since many of the assertions in Bindler (2018, https://doi.org/10.1002/2018GH000135) are congruent with our findings and directly contradict Hinkley (2018), this reply refers to Bindler (2018), whenever appropriate, and indicates where our evidence diverges
230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Costa, K. M., Hayes, C. T., Anderson, R. F., Pavia, F. J., Bausch, A., Deng, F., Dutay, J., Geibert, W., Heinze, C., Henderson, G., Hillaire-Marcel, C., Hoffmann, S., Jaccard, S. L., Jacobel, A. W., Kienast, S. S., Kipp, L., Lerner, P., Lippold, J., Lund, D., Marcantonio, F., McGee, D., McManus, J. F., Mekik, F., Middleton, J. L., Missiaen, L., Not, C., Pichat, S., Robinson, L. F., Rowland, G. H., Roy-Barman, M., Alessandro, Torfstein, A., Winckler, G., & Zhou, Y. 230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean. Paleoceanography and Paleoclimatology, 35(2), (2020): e2019PA003820, doi:10.1029/2019PA003820.230Th normalization is a valuable paleoceanographic tool for reconstructing highâresolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0â5,000 years ago, or 0â5 ka) and the Last Glacial Maximum (18.5â23.5 ka), and investigated the spatial structure of 230Thânormalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79â2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48â1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, sizeâdependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).We thank Zanna Chase and one anonymous reviewer for valuable feedback. K. M. C. was supported by a Postdoctoral Scholarship at WHOI. L. M. acknowledges funding from the Australian Research Council grant DP180100048. The contribution of C. T. H., J. F. M., and R. F. A. were supported in part by the U.S. National Science Foundation (USâNSF). G. H. R. was supported by the Natural Environment Research Council (grant NE/L002434/1). S. L. J. acknowledges support from the Swiss National Science Foundation (grants PP002P2_144811 and PP00P2_172915). This study was supported by the Past Global Changes (PAGES) project, which in turn received support from the Swiss Academy of Sciences and the USâNSF. This work grew out of a 2018 workshop in AixâMarseille, France, funded by PAGES, GEOTRACES, SCOR, USâNSF, AixâMarseille UniversitĂ©, and John Cantle Scientific. All data are publicly available as supporting information to this document and on the National Center for Environmental Information (NCEI) at https://www.ncdc.noaa.gov/paleo/study/28791
NaV1.7 and pain: contribution of peripheral nerves
The sodium channel NaV1.7 contributes to action potential generation and propagation. Loss-of-function mutations in patients lead to congenital indifference to pain, though it remains unclear where on the way from sensory terminals to CNS the signalling is disrupted. We confirm that conditional deletion of NaV1.7 in advillin expressing sensory neurons leads to impaired heat and mechanical nociception in behavioural tests. With single-fiber recordings from isolated skin we found (1) a significantly lower prevalence of heat responsiveness to in normally mechanosensitive C-fibers, although (2) the rare heat responses appeared quite vigorous and (3) heat-induced CGRP release was normal. In biophysical respects, while electrical excitability, rheobase and chronaxy were normal (4) axonal conduction velocity was 20% slower than in congenic wildtype mice (5) and when challenged with double pulses (< 100 ms interval), the second action potential showed more pronounced latency increase (6). Upon prolonged electrical stimulation at 2 Hz, (7) activity-dependent slowing of nerve fiber conduction was markedly less and (8) was less likely to result in conduction failure of the mutant single-fibers. Finally, recording of compound action potentials from the whole saphenous nerve confirmed slower conduction and less activity-dependent slowing as well as the functional absence of a large subpopulation of C-fibers (9) in conditional Nav1.7 knock-outs. In conclusion, the clear deficits in somatic primary afferent functions shown in our study may be complemented by previously reported synaptic dysfunction and opioidergic inhibition, together accounting for the complete insensitivity to pain in the human mutants lacking Nav1.7
Selenoprotein gene nomenclature
The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates
Enhancing the reporting of implementation research
In the 10 years since the inception of Implementation Science, we have witnessed a continued rise in the number of submissions received, reflecting the continued global interest in methods to enhance the uptake of research findings into healthcare practice and policy. We receive over 750 submissions annually, and there is now a large gap between what is submitted and what gets published. In this editorial, we restate the journal scope and current boundaries. We also identify some specific reporting issues that if addressed will help enhance the scientific reporting quality and transparency of the manuscripts we receive. We hope that this editorial acts as a further guide to researchers seeking to publish their work in Implementation Science
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