Seasonal variability of particulate organic radiocarbon in the northeast Pacific ocean

We present Delta(14)C measurements of particulate organic carbon (POC) collected on four cruises at our time series site (station M) in the northeast Pacific Ocean. We observe a large gradient with depth in the suspended POC Delta(14)C values (124-160 parts per thousand). These profiles display lower Delta(14)C values (by 20-30 parts per thousand) in samples between 2500 m and the bottom during June 1992 and July 1993 than those during February and October 1992. Values of Delta(14)C in sinking POC from deep-moored sediment trap collections suggest a semiannual trend that displays lower overall Delta(14)C in material collected during periods of high flux. A limited number of Delta(14)C measurements of small swimmers picked from the trap 650 m above bottom are similar to surface Delta(14)C measurements of dissolved inorganic carbon (DIG) and suspended POC, indicating a surface carbon source. Overall, we postulate that the major process causing lower Delta(14)C values of deep suspended and sinking POC is sorption (or biological incorporation) of \u27\u27old\u27\u27 DOC onto particulate matter. There appears to be a higher ratio of DOC sorbed to sinking particulate matter at times of high flux (late spring and early fall) that can be thought of as a \u27\u27stripping out\u27\u27 of DOC from the water column. The DIC Delta(14)C display a small seasonal variation in the surface waters and is not the sole source of the observed seasonality in the POC Delta(14)C signals

Comprehensive surface magnetotransport study of SmB6

After the theoretical prediction that SmB6 is a topological Kondo insulator, there has been an explosion of studies on the SmB6 surface. However, there is not yet an agreement on even the most basic quantities such as the surface carrier density and mobility. In this paper, we carefully revisit Corbino disk magnetotransport studies to find those surface transport parameters. We first show that subsurface cracks exist in the SmB6 crystals, arising both from surface preparation and during the crystal growth. We provide evidence that these hidden subsurface cracks are additional conduction channels, and the large disagreement between earlier surface SmB6 studies may originate from previous interpretations not taking this extra conduction path into account. We provide an update of more reliable magnetotransport data than the previous one (S. Wolgast et al., Phys. Rev. B 92, 115110) and find that the orders-of-magnitude large disagreements in carrier density and mobility come from the surface preparation and the transport geometry rather than the intrinsic sample quality. From this magnetotransport study, we find an updated estimate of the carrier density and mobility of 2.71×1013 (1/cm2) and 104.5 (cm2/Vsec), respectively. We compare our results with other studies of the SmB6 surface. By this comparison, we provide insight into the disagreements and agreements of the previously reported angle-resolved photoemission spectroscopy, scanning tunneling microscopy, and magnetotorque quantum oscillations measurements

Trouble in Paradise - A disabled person's right to the satisfaction of a self-defined need:Some conceptual and practical problems

This paper questions the usefulness of the rights-based approach to ameliorating the social situation of disabled people in Britain and advances two criticisms. First, that rights and self-de? ned needs have been under-theorised by disability theorists to the extent that they have insuf? ciently appreciated the problems that these approaches pose. The paper suggests that rights to appropriate resources to satisfy self-de? ned needs will generate vast numbers of competing rights claims and that the resulting tendency of rights to con? ict has been under-appreciated. Secondly, that there has been little consideration of how these con? icts might be reconciled. The ? rst two sections of the paper look at the concepts of ascribed and self-de? ned needs, respectively, whilst the ? nal one looks at some of the problems of the rights approach and some of the dif? culties of making self-de? ned need the basis of rights claims

Origin of the deep Bering Sea nitrate deficit : constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 19 (2005): GB4005, doi:10.1029/2005GB002508.On the basis of the normalization to phosphate, a significant amount of nitrate is missing from the deep Bering Sea (BS). Benthic denitrification has been suggested previously to be the dominant cause for the BS nitrate deficit. We measured water column nitrate 15N/14N and 18O/16O as integrative tracers of microbial denitrification, together with pore water-derived benthic nitrate fluxes in the deep BS basin, in order to gain new constraints on the mechanism of fixed nitrogen loss in the BS. The lack of any nitrate isotope enrichment into the deep part of the BS supports the benthic denitrification hypothesis. On the basis of the nitrate deficit in the water column with respect to the adjacent North Pacific and a radiocarbon-derived ventilation age of ∼50 years, we calculate an average deep BS (>2000 m water depth) sedimentary denitrification rate of ∼230 μmol N m−2 d−1 (or 1.27 Tg N yr−1), more than 3 times higher than high-end estimates of the average global sedimentary denitrification rate for the same depth interval. Pore water-derived estimates of benthic denitrification were variable, and uncertainties in estimates were large. A very high denitrification rate measured from the base of the steep northern slope of the basin suggests that the elevated average sedimentary denitrification rate of the deep Bering calculated from the nitrate deficit is driven by organic matter supply to the base of the continental slope, owing to a combination of high primary productivity in the surface waters along the shelf break and efficient down-slope sediment focusing along the steep continental slopes that characterize the BS.This study was supported by NSF grants OCE-0136449 and OCE-9981479 to D. M. S., OCE-0118126 and OCE-0324987 to D. C. M., and DFG grant LE 1326/1-1 to M. F. L. The BS cruise was funded by grant OPP-9912122

Sources and cycling of dissolved and particulate organic radiocarbon in the northwest Atlantic continental margin

Continental shelves and slopes are productive and dynamic ocean margin systems that also regulate the fluxes of terrestrial, riverine, and estuarine materials between the continents and oceans. In order to evaluate the ages, potential sources, and transformations of organic matter in an ocean margin system, we measured the radiocarbon (Delta (14)C and delta (13)C distributions of total dissolved organic carbon (DOC), suspended particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in waters of the Middle Atlantic Bight (MAB) continental shelf and slope in April-May 1994. The Delta (14)C of DOC was greatest (as high as -39 parts per thousand) in surface waters of the shelf, decreasing rapidly offshore and with depth, even in relatively shallow (25-50 in depth) shelf waters. The lowest Delta (14)C-DOC values were observed in deep slope waters, where they were significantly lower than values measured previously for the deep Sargasso Sea. There was a strong inverse relationship between Delta (14)C-DOC and delta (-13)C-DOC in all shelf and surface slope waters of the MAB, which is likely attributable to varying contributions of young, (14)C-enriched organic matter of terrestrial and/or riverine origin. The more highly (14)C-depleted DOC in deep : slope waters (as low as -442 parts per thousand) generally had a correspondingly lower delta (13)C (as low as -22.3 parts per thousand) component. However, this must originate from relic terrestrial material either in the MAB itself or be discharged to the MAB from rivers and estuaries. The isotopic signatures of POC were clearly differentiable from DOC and indicate that this pool also contained a broad range of both old and young material of terrestrial (delta (13)C as low as -24.9 parts per thousand) and marine (delta (13)C as high as -19.9 parts per thousand) origin throughout the MAB shelf and slope. The highest Delta (14)C-POC values (up to 78 parts per thousand) were observed in shallow shelf waters of the southern MAR Conversely, the lowest Delta (14)C-POC values (as low as -394 parts per thousand) were found in MAB deep slope waters and were also significantly more depleted in (14)C than POC from the central north Atlantic (Sargasso Sea). A multiple-source isotopic mass balance model employing both (14)C and (13)C was used to evaluate the relative contributions of both young and old terrigenous versus marine organic matter to DOC and POC in the MAR The results indicate that shelf and slope DOC is comprised of an old marine fraction (represented by offshore Sargasso Sea material) and either a young terrestrial/riverine/estuarine (TRE) component (in shelf and shallow slope waters) or a relic TRE component (in deep and some shallow slope waters). In contrast, suspended POC from the MAB appears to originate predominantly from a mixture of recent MAB primary production and an old, TRE component, similar to that observed in one of the major subestuaries of the Chesapeake Bay. These results suggest that both young and old sources of terrestrial and riverine organic matter can comprise a significant fraction of the DOC and POC in ocean margins. Preliminary calculations indicate that the export of this compositionally unique DOC and suspended POC may be significant terms in the organic carbon budgets of the MAB and other margin systems

Boost Camp’, a universal school-based transdiagnostic prevention program targeting adolescent emotion regulation; evaluating the effectiveness by a clustered RCT : a protocol paper

Abstract Background The transition from childhood into adolescence can be considered as a critical developmental period. Moreover, adolescence is associated with a decreased use of adaptive emotion regulation strategies and an increased use of maladaptive emotion regulation strategies increasing the risk of emotional problems. Targeting emotion regulation is therefore seen as an innovative prevention approach. The present study aims to evaluate the effectiveness of Boost camp, an innovative school-based prevention program targeting ER, on adolescents’ emotion regulation skills and emotional wellbeing. Also secondary outcomes and possible moderators will be included. Methods The aim is to reach 300 adolescents (16 class groups, 6 schools) in their first year of high school. A clustered Randomized Controlled Trial (RCT) with two conditions, intervention (n = 150) and control (n = 150), will be set up. Adolescents in the intervention condition will receive 14 lessons over the course of 2 days, followed by Booster sessions, and will be compared with adolescents in a non-intervention control group. The outcomes will be measured by self-report questionnaires at baseline, immediately after Boost camp, and at three and 6 months follow-up. Discussion Data-collection is planned to be completed in May 2018. Data-analyses will be finished the end of 2018. The presented paper describes the Boost camp program and the clustered RCT design to evaluate its effectiveness. It is expected that Boost camp will have beneficial effects. If found effective, Boost camp will have the potential to increase adolescent’s ER and well-being, and reduce the risk to become adults in need. The trials is registered on the 13th of June 2017 in ISRCTN registry [ISRCTN68235634]

Surface-dominated conduction up to 240 K in the Kondo insulator SmB6 under strain

SmB6 is a strongly correlated mixed-valence Kondo insulator with a newly discovered surface state, proposed to be of non-trivial topological origin. However, the surface state dominates electrical conduction only below T∗ ≈ 4 K (ref. ), limiting its scientific investigation and device application. Here, we report the enhancement of T∗ in SmB6 under the application of tensile strain. With 0.7% tensile strain we report surface-dominated conduction at up to a temperature of 240 K, persisting even after the strain has been removed. This can be explained in the framework of strain-tuned temporal and spatial fluctuations of f-electron configurations, which might be generally applied to other mixed-valence materials. We note that this amount of strain can be induced in epitaxial SmB6 films via substrate in potential device applications