bluuebunny/crossref_metadata_2025_split huggingface dataset:
Twin-cuvette measurement technique for investigation of dry deposition of O3 and PAN to plant leaves under controlled humidity conditions
Authors: Sun Shang , Moravek Alexander , von der Heyden Lisa , Held Andreas , Sörgel Matthias , Kesselmeier Jürgen 
Published: February 2016

Abstract. We present a dynamic twin-cuvette system for quantifying the trace-gas exchange fluxes between plants and the atmosphere under controlled temperature, light, and humidity conditions. Compared with a single-cuvette system, the twin-cuvette system is insensitive to disturbing background effects such as wall deposition. In combination with a climate chamber, we can perform flux measurements under constant and controllable environmental conditions. With an Automatic Temperature Regulated Air Humidification System (ATRAHS), we are able to regulate the relative humidity inside both cuvettes between 40 and 90 % with a high precision of 0.3 %. Thus, we could demonstrate that for a cuvette system operated with a high flow rate (> 20 L min−1), a temperature-regulated humidification system such as ATRAHS is an accurate method for air humidification of the flushing air. Furthermore, the fully automatic progressive fill-up of ATRAHS based on a floating valve improved the performance of the entire measurement system and prevented data gaps. Two reactive gas species, ozone (O3) and peroxyacetyl nitrate (PAN), were used to demonstrate the quality and performance of the twin-cuvette system. O3 and PAN exchange with Quercus ilex was investigated over a 14 day measurement period under controlled climate chamber conditions. By using O3 mixing ratios between 32 and 105 ppb and PAN mixing ratios between 100 and 350 ppt, a linear dependency of the O3 flux as well as the PAN flux in relation to its ambient mixing ratio could be observed. At relative humidity (RH) of 40 %, the deposition velocity ratio of O3 and PAN was determined to be 0.45. At that humidity, the deposition of O3 to the plant leaves was found to be only controlled by the leaf stomata. For PAN, an additional resistance inhibited the uptake of PAN by the leaves. Furthermore, the formation of water films on the leaf surface of plants inside the chamber could be continuously tracked with our custom built leaf wetness sensors. Using this modified leaf wetness sensor measuring the electrical surface conductance on the leaves, an exponential relationship between the ambient humidity and the electrical surface conductance could be determined.
Negligible effects of ocean acidification on Eurytemora affinis (Copepoda) offspring production
Authors: Almén Anna-Karin , Vehmaa Anu , Brutemark Andreas , Bach Lennart , Lischka Silke , Stuhr Annegret , Furuhagen Sara , Paul Allanah , Bermúdez J. Rafael , Riebesell Ulf , Engström-Öst Jonna 
Published: February 2016

Abstract. Ocean acidification is caused by increasing amounts of carbon dioxide dissolving in the oceans leading to lower seawater pH. We studied the effects of lowered pH on the calanoid copepod Eurytemora affinis during a mesocosm experiment conducted in a coastal area of the Baltic Sea. We measured copepod reproductive success as a function of pH, chlorophyll a concentration, diatom and dinoflagellate biomass, carbon to nitrogen (C : N) ratio of suspended particulate organic matter, as well as copepod fatty acid composition. The laboratory-based experiment was repeated four times during 4 consecutive weeks, with water and copepods sampled from pelagic mesocosms enriched with different CO2 concentrations. In addition, oxygen radical absorbance capacity (ORAC) of animals from the mesocosms was measured weekly to test whether the copepod's defence against oxidative stress was affected by pH. We found no effect of pH on offspring production. Phytoplankton biomass, as indicated by chlorophyll a concentration and dinoflagellate biomass, had a positive effect. The concentration of polyunsaturated fatty acids in the females was reflected in the eggs and had a positive effect on offspring production, whereas monounsaturated fatty acids of the females were reflected in their eggs but had no significant effect. ORAC was not affected by pH. From these experiments we conclude that E. affinis seems robust against direct exposure to ocean acidification on a physiological level, for the variables covered in the study. E. affinis may not have faced acute pH stress in the treatments as the species naturally face large pH fluctuations.
Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific
Authors: Arévalo-Martínez Damian L. , Kock Annette , Löscher Carolin R. , Schmitz Ruth A. , Stramma Lothar , Bange Hermann W. 
Published: February 2016

Abstract. Recent observations in the eastern tropical South Pacific (ETSP) have shown the key role of meso- and submesoscale processes (e.g. eddies) in shaping its hydrographic and biogeochemical properties. Off Peru, elevated primary production from coastal upwelling in combination with sluggish ventilation of subsurface waters fuels a prominent oxygen minimum zone (OMZ). Given that nitrous oxide (N2O) production–consumption processes in the water column are sensitive to oxygen (O2) concentrations, the ETSP is a region of particular interest to investigate its source–sink dynamics. To date, no detailed surveys linking mesoscale processes and N2O distributions as well as their relevance to nitrogen (N) cycling are available. In this study, we present the first measurements of N2O across three mesoscale eddies (two mode water or anticyclonic and one cyclonic) which were identified, tracked, and sampled during two surveys carried out in the ETSP in November–December 2012. A two-peak structure was observed for N2O, wherein the two maxima coincide with the upper and lower boundaries of the OMZ, indicating active nitrification and partial denitrification. This was further supported by the abundances of the key gene for nitrification, ammonium monooxygenase (amoA), and the gene marker for N2O production during denitrification, nitrite reductase (nirS). Conversely, we found strong N2O depletion in the core of the OMZ (O2 < 5 µmol L−1) to be consistent with nitrite (NO2−) accumulation and low levels of nitrate (NO3−), thus suggesting active denitrification. N2O depletion within the OMZ's core was substantially higher in the centre of mode water eddies, supporting the view that eddy activity enhances N-loss processes off Peru, in particular near the shelf break where nutrient-rich, productive waters from upwelling are trapped before being transported offshore. Analysis of eddies during their propagation towards the open ocean showed that, in general, “ageing” of mesoscale eddies tends to decrease N2O concentrations through the water column in response to the reduced supply of material to fuel N loss, although hydrographic variability might also significantly impact the pace of the production–consumption pathways for N2O. Our results evidence the relevance of mode water eddies for N2O distribution, thereby improving our understanding of the N-cycling processes, which are of crucial importance in times of climate change and ocean deoxygenation.
Scaling regimes and linear/nonlinear responses of last millennium climate to volcanic and solar forcings
Authors: Lovejoy Shaun , Varotsos Costas 
Published: February 2016

Abstract. At scales much longer than the deterministic predictability limits (about 10 days), the statistics of the atmosphere undergoes a drastic transition, the high-frequency weather acts as a random forcing on the lower-frequency macroweather. In addition, up to decadal and centennial scales the equivalent radiative forcings of solar, volcanic and anthropogenic perturbations are small compared to the mean incoming solar flux. This justifies the common practice of reducing forcings to radiative equivalents (which are assumed to combine linearly), as well as the development of linear stochastic models, including for forecasting at monthly to decadal scales. In order to clarify the validity of the linearity assumption and determine its scale range, we use last millennium simulations, with both the simplified Zebiak–Cane (ZC) model and the NASA GISS E2-R fully coupled GCM. We systematically compare the statistical properties of solar-only, volcanic-only and combined solar and volcanic forcings over the range of timescales from 1 to 1000 years. We also compare the statistics to multiproxy temperature reconstructions. The main findings are (a) that the variability in the ZC and GCM models is too weak at centennial and longer scales; (b) for longer than  ≈  50 years, the solar and volcanic forcings combine subadditively (nonlinearly) compounding the weakness of the response; and (c) the models display another nonlinear effect at shorter timescales: their sensitivities are much higher for weak forcing than for strong forcing (their intermittencies are different) and we quantify this with statistical scaling exponents.
Les grossesses chez les adolescentes autochtones au Canada
Authors: Joncas Jo-Anni , Roy Bernard 
Published: February 2016

Cet article dresse un portrait des recherches concernant les grossesses chez les adolescentes autochtones au Canada. Les statistiques indiquent que la prévalence des grossesses précoces est particulièrement marquée chez ces peuples. Une recension des écrits a été effectuée dans trois grandes bases de données. Dans un premier temps, les auteurs présentent l’état de la situation en explorant la problématique et les facteurs de risque relevés dans les écrits recensés. Même si les grossesses à l’adolescence peuvent être une expérience positive, les recherches montrent qu’elles ont généralement des effets négatifs à long terme sur le bien-être de la mère, de l’enfant et de la communauté. Différents facteurs de risque ont été documentés, comme la pauvreté, la précocité des activités sexuelles et la consommation de drogue et d’alcool. Dans un deuxième temps, les auteurs présentent trois approches explicatives qui ont été dégagées de ces écrits : l’approche culturelle, l’approche centrée sur l’accès aux services de santé et l’approche sociohistorique.
Observation of electric potential in organic thin-film transistor by bias-applied hard X-ray photoemission spectroscopy
Authors: Watanabe Takeshi , Tada Keisuke , Yasuno Satoshi , Oji Hiroshi , Yoshimoto Noriyuki , Hirosawa Ichiro 
Published: February 2016

Abstract
The effect of gate voltage on electric potential in a pentacene (PEN) layer was studied by hard X-ray photoelectron spectroscopy under a bias voltage. It was observed that applying a negative gate voltage substantially increases the width of a C 1s peak. This suggested that injected and accumulated carriers in an organic thin film transistor channel modified the potential depth profile in PEN. It was also observed that the C 1s kinetic energy tends to increase monotonically with threshold voltage.
Design and experimental demonstration of low-power CMOS magnetic cell manipulation platform using charge recycling technique
Authors: Niitsu Kiichi , Yoshida Kohei , Nakazato Kazuo 
Published: February 2016

Abstract
We present the world’s first charge-recycling-based low-power technique of complementary metal–oxide–semiconductor (CMOS) magnetic cell manipulation. CMOS magnetic cell manipulation associated with magnetic beads is a promissing tool for on-chip biomedical-analysis applications such as drug screening because CMOS can integrate control electronics and electro-chemical sensors. However, the conventional CMOS cell manipulation requires considerable power consumption. In this work, by concatenating multiple unit circuits and recycling electric charge among them, power consumption is reduced by a factor of the number of the concatenated unit circuits (1/N). For verifying the effectiveness, test chip was fabricated in a 0.6-µm CMOS. The chip successfully manipulates magnetic microbeads with achieving 49% power reduction (from 51 to 26.2 mW). Even considering the additional serial resistance of the concatenated inductors, nearly theoretical power reduction effect can be confirmed.
Attribution of extreme weather and climate events overestimated by unreliable climate simulations
Authors: Bellprat Omar , Doblas‐Reyes Francisco 
Published: February 2016

AbstractEvent attribution aims to estimate the role of an external driver after the occurrence of an extreme weather and climate event by comparing the probability that the event occurs in two counterfactual worlds. These probabilities are typically computed using ensembles of climate simulations whose simulated probabilities are known to be imperfect. The implications of using imperfect models in this context are largely unknown, limited by the number of observed extreme events in the past to conduct a robust evaluation. Using an idealized framework, this model limitation is studied by generating large number of simulations with variable reliability in simulated probability. The framework illustrates that unreliable climate simulations are prone to overestimate the attributable risk to climate change. Climate model ensembles tend to be overconfident in their representation of the climate variability which leads to systematic increase in the attributable risk to an extreme event. Our results suggest that event attribution approaches comprising of a single climate model would benefit from ensemble calibration in order to account for model inadequacies similarly as operational forecasting systems.
Influences of shear in the ion parallel drift velocity and of inhomogeneous perpendicular electric field on generation of oblique ion acoustic waves
Authors: Ilyasov Askar , Chernyshov Alexander , Mogilevsky Mikhail , Golovchanskaya Irina , Kozelov Boris 
Published: February 2016

AbstractIt is well known that the broadband electrostatic turbulence observed in the topside auroral ionosphere can be identified with electrostatic ion cyclotron and/or oblique ion acoustic waves. Under certain conditions generation of the ion cyclotron modes is inhibited, so that the oblique ion acoustic waves become the prevailing part of the broadband noise. While generation of ion cyclotron waves by the inhomogeneous distribution of energy density (IEDD) instability has been actively studied in recent years, much less attention was paid to the excitation of ion acoustic waves by means of the IEDD instability. In this work, influence of shear in the ion parallel drift velocities and of inhomogeneous perpendicular electric field on generation of nonlocal oblique ion acoustic mode is studied. It is demonstrated that the shear of the ion parallel drift velocities can generate ion acoustic waves. It is shown that this mechanism of instability development provides broadband spectrum in the frequency range around 0.1 of ion gyrofrequency, and thus, this instability can be invoked to explain the observed broadband electrostatic turbulence in the auroral region. Effect of the main background plasma parameters on excitation of oblique ion acoustic waves is analyzed.
Observation of > 5 wt % zinc at the Kimberley outcrop, Gale crater, Mars
Authors: Lasue J. , Clegg S. M. , Forni O. , Cousin A. , Wiens R. C. , Lanza N. , Mangold N. , Le Deit L. , Gasnault O. , Maurice S. , Berger J. A. , Stack K. , Blaney D. , Fabre C. , Goetz W. , Johnson J. , Le Mouélic S. , Nachon M. , Payré V. , Rapin W. , Sumner D. Y. 
Published: February 2016

AbstractZinc‐enriched targets have been detected at the Kimberley formation, Gale crater, Mars, using the Chemistry Camera (ChemCam) instrument. The Zn content is analyzed with a univariate calibration based on the 481.2 nm emission line. The limit of quantification for ZnO is 3 wt % (at 95% confidence level) and 1 wt % (at 68% confidence level). The limit of detection is shown to be around 0.5 wt %. As of sol 950, 12 targets on Mars present high ZnO content ranging from 1.0 wt % to 8.4 wt % (Yarrada, sol 628). Those Zn‐enriched targets are almost entirely located at the Dillinger member of the Kimberley formation, where high Mn and alkali contents were also detected, probably in different phases. Zn enrichment does not depend on the textures of the rocks (coarse‐grained sandstones, pebbly conglomerates, and resistant fins). The lack of sulfur enhancement suggests that Zn is not present in the sphalerite phase. Zn appears somewhat correlated with Na2O and the ChemCam hydration index, suggesting that it could be in an amorphous clay phase (such as sauconite). On Earth, such an enrichment would be consistent with a supergene alteration of a sphalerite gossan cap in a primary siliciclastic bedrock or a possible hypogene nonsulfide zinc deposition where Zn, Fe, Mn would have been transported in a reduced sulfur‐poor fluid and precipitated rapidly in the form of oxides.
Limits on the morphogenetic role of rain splash transport in hillslope evolution
Authors: Dunne Thomas , Malmon Daniel V. , Dunne Kieran B. J. 
Published: February 2016

AbstractAn experimentally parameterized equation for rain splash transport was generalized in order to compute annual sediment transport rates for a range of climates. The resulting equation was then used to examine the conditions under which rain splash transport can play a significant morphogenetic role in water‐eroded landscapes. Rain splash can generate convex hillslopes on short, steep hillslopes such as the margins of gullies in unconsolidated sediments. However, comparison of predicted profiles with long, convex hillslopes in postorogenic landscapes indicates that rain splash cannot transport sufficient quantities of sediment to produce the observed convex hillslope profiles. Rates of biogenic transport estimated from the literature also appear to be insufficient. Sheetwash transport appears to be the only process capable of molding these extensive convex hillslope profiles despite the common assumption that it generates exclusively concave forms.
Where glaciers meet water: Subaqueous melt and its relevance to glaciers in various settings
Authors: Truffer Martin , Motyka Roman J. 
Published: February 2016

AbstractGlacier change is ubiquitous, but the fastest and largest magnitude changes occur in glaciers that terminate in water. This includes the most rapidly retreating glaciers, and also several advancing ones, often in similar regional climate settings. Furthermore, water‐terminating glaciers show a large range in morphology, particularly when ice flow into ocean water is compared to that into freshwater lakes. All water‐terminating glaciers share the ability to lose significant volume of ice at the front, either through mechanical calving or direct melt from the water in contact. Here we present a review of the subaqueous melt process. We discuss the relevant physics and show how different physical settings can lead to different glacial responses. We find that subaqueous melt can be an important trigger for glacier change. It can explain many of the morphological differences, such as the existence or absence of floating tongues. Subaqueous melting is influenced by glacial runoff, which is largely a function of atmospheric conditions. This shows a tight connection between atmosphere, oceans and lakes, and glaciers. Subaqueous melt rates, even if shown to be large, should always be discussed in the context of ice supply to the glacier front to assess its overall relevance. We find that melt is often relevant to explain seasonal evolution, can be instrumental in shifting a glacier into a different dynamical regime, and often forms a large part of a glacier's mass loss. On the other hand, in some cases, melt is a small component of mass loss and does not significantly affect glacier response.
Scandium in the open ocean: A comparison with other group 3 trivalent metals
Authors: Parker C. E. , Brown M. T. , Bruland K. W. 
Published: February 2016

AbstractLittle is known about the distribution of scandium (Sc) in the open ocean. Since the 1970s there has been only one published depth profile of dissolved Sc. The work presented here reports depth profiles of dissolved Sc from GEOTRACES cruises in the North Atlantic, North Pacific, and South Pacific. This work also compares the reactivity of Sc with its trivalent periodic table groupmates in Group IIIB, yttrium (Y) and lanthanum (La), and Group IIIA, aluminum (Al) and gallium (Ga). Yttrium and La are classic nutrient‐type metals that increase in concentration in aging deep water; Al and Ga are classic scavenged‐type metals that do the opposite. Results indicate that Sc is a hybrid‐type metal with an inferred residence time on the order of 1000 years, and that Sc's inorganic speciation and reactivity are similar to Fe's and have the potential to give insights into the nonnutrient side of oceanic Fe cycling.
How does mass loading impact local versus global control on dayside reconnection?
Authors: Zhang B. , Brambles O. J. , Wiltberger M. , Lotko W. , Ouellette J. E. , Lyon J. G. 
Published: February 2016

AbstractThis paper investigates the effects of magnetospheric mass loading on the control of dayside magnetic reconnection using global magnetospheric simulations. The study iys motivated by a recent debate on whether the integrated dayside magnetic reconnection rate is solely controlled by local processes (local‐control theory) or global merging processes (global‐control theory). The local‐control theory suggests that the integrated dayside reconnection rate is controlled by the local plasma parameters. The global‐control theory argues that the integrated rate is determined by the net force acting on the flow in the magnetosheath rather than the local microphysics. Controlled numerical simulations using idealized ionospheric outflow specifications suggest a possible mixed‐control theory, that is, (1) a small amount of mass loading at the dayside magnetopause only redistributes local reconnection rate without a significant change in the integrated reconnection rate and (2) a large amount of mass loading reduces both local reconnection rates and the integrated reconnection rate on the dayside. The transition between global‐control‐ and local‐control‐dominated regimes depends on (but not limited to) the source region, the amount, the location, and the spatial extension of the mass loading at the dayside magnetopause.
Provenance of dust to Antarctica: A lead isotopic perspective
Authors: Gili Stefania , Gaiero Diego M. , Goldstein Steven L. , Chemale Jr Farid , Koester Edinei , Jweda Jason , Vallelonga Paul , Kaplan Michael R. 
Published: February 2016

AbstractAntarctic ice preserves an ~800 kyr record of dust activity in the Southern Hemisphere. Major efforts have been dedicated to elucidate the origin of this material in order to gain greater insight into the atmospheric dust cycle. On the basis of Pb isotopes in Antarctic dust samples and potential sources, this contribution demonstrates for the first time that Patagonia is the main contributor of dust to Antarctica during interglacial periods as well as glacials, although the potential importance of Tierra del Fuego remains unclear because of its geochemical similarities to Patagonia. An important new finding is that the Puna‐Altiplano sector of the continent is a second important dust source to eastern Antarctica during both glacials and interglacials, being more prominent during interglacials. The data indicate South America is the primary dust source to Antarctica during both glacials and interglacials.
A Powerful Method for the Direct Arylation of Furans at a Sterically Congested C−H Bond
Authors: Nishikata Takashi , Yamane Yu , Yamaguchi Yousui , Ishikawa Shingo 
Published: February 2016

AbstractThe direct arylation of furans at a sterically congested C−H bond are accomplished. Although there are many methods for catalytic C−H arylation, direct C−H arylation at bulky reaction sites is one of the most problematic issues in this area. In this study, we found that a PdCl2‐1,2‐bis(dicyclohexylphosphino)ethane (dcype) or PCy3 and silver salt system enables arylations at a sterically congested C−H bonds to produce “highly congested” and “very congested” triarylfurans.