bluuebunny/crossref_metadata_2025 huggingface dataset:
Public health benefits and risks of fish consumption: current scientific evidence v. media coverage
Authors: Pasquaré Federico A , Bettinetti Roberta , Fumagalli Sonia , Vignati Davide A
Published: September 2012

Objective

To evaluate if and how the current degree of scientific uncertainty about the safety of fish consumption is incorporated at the media level.

Design

We used a dedicated software (TalTac®) to investigate the content of 169 news articles related to ‘mercury and fish consumption’ that appeared from 1990 to 2010 in the two Italian broadsheets with the highest circulation figures, in order to identify journalistic frames used in the coverage of benefits v. risks associated with fish consumption. Hypotheses were made on how the public might change fish consumption patterns as a result of media coverage.

Setting

Italy.

Results

The two newspapers have different agendas in covering the issue. La Repubblica appears to support the view that, besides health benefits, there may be risks associated with fish consumption, while Corriere della Sera emphasizes health benefits more than possible risks. Depending on the preferred information source, the public could: (i) reduce its fish intake; (ii) increase its fish intake; or (iii) become confused about the problem and sceptical towards the media, as a result of conflicting journalistic frames.

Conclusions

The Italian media, in cooperation with scientists, public health nutritionists and dietitians, should place more emphasis on the existence of a few fish species with high to very high Hg levels and relatively low contents of beneficial n-3 fatty acids (e.g. swordfish and shark). This would enable consumers to make more educated purchasing decisions to maximize the benefits of n-3 intake while reducing possible risks from consuming Hg-contaminated fish.
Solar spot influence on Earth's molecular processes
Authors: Evstafyev Vladimir K.
Published: September 2012

The paper considers the two-century-old problem of how solar spots influence biological objects on the Earth. It describes the modern state of the kT-problem, which for a long time has been the most difficult obstacle in explaining solar activity effects. Based on recent advances in spin chemistry and magnetoplasticity physics, it is shown that a ‘molecular target’ sensitive to weak electromagnetic fields is spins in non-equilibrial states of the molecular system. A way of how solar spots can influence Earth's molecular, including biological, processes through a ‘transparency window’ in the Earth's atmosphere is proposed.
Follower Beliefs in the Co-Production of Leadership
Authors: Carsten Melissa K. , Uhl-Bien Mary
Published: September 2012

Drawing on a role-based approach to followership, we investigate followers’ beliefs about the co-production of leadership and examine the association of these beliefs with upward communication behaviors. We also investigate the potential moderating effects of leader consideration, leader-follower relationship quality, and autonomous work climate on the relationship between co-production beliefs and upward communication. The findings show a positive relationship between co-production beliefs and upward communication with leaders (i.e., voice and constructive resistance). Findings also show that leadership style, overall relationship quality, and autonomous work climate moderate the relationship between co-production beliefs and voice, but not constructive resistance. Interactions show that followers with weaker co-production beliefs use significantly less voice when leadership and contextual conditions were unfavorable, but that contextual conditions did not diminish the voice behaviors of those with stronger co-production beliefs. We discuss implications for both research and practice, and lay a foundation for how followership research may supplement and extend our understanding of the co-production of leadership in organizations.
Submitting to the Follower Label
Authors: Hoption Colette , Christie Amy , Barling Julian
Published: September 2012

Although the importance of followership has been discussed in organizational literature, negative connotations attached to the follower label persist, including followers’ lack of ability and power. In two studies, we found evidence for negative effects of the follower label. Participants who were labeled a follower (Study 1), or self-labeled as followers in their jobs (Study 2), reported lower positive affect, and in turn, fewer extra-role behaviors. These findings suggest that followers might be at risk for reinforcing their negative stereotypes by avoiding opportunities to show their abilities and demonstrate their independence. Recommendations for leaders and opportunities for future research are discussed.
Strength in Numbers
Authors: Lapierre Laurent M. , Bremner Nicholas L. , McMullan Alicia D.
Published: September 2012

In this theoretical paper, we explain how employees’ passive and proactive followership behavior can influence the extent to which their managers display socialized or personalized charismatic leadership. We argue that followership behaviors influence managers’ positive affect and psychological empowerment, which in turn drive the degree to which managers manifest their particular charismatic leadership inclination. However, these effects would depend on the strength of managers’ predisposition for one type of charismatic leadership or the other. Implications for charismatic leadership theory and future research are discussed.
LEND neutron data processing for the mapping of the Moon
Authors: Litvak M. L. , Mitrofanov I. G. , Sanin A. B. , Golovin D. V. , Malakhov A. V. , Boynton W. V. , Droege G. F. , Harshman K. , Starr R. D. , Milikh G. , Sagdeev R.
Published: September 2012

The Lunar Exploration Neutron Detector (LEND) aboard the Lunar Reconnaissance Orbiter (LRO) has been mapping the neutron flux from the Moon since July 2009. LEND has four different types of neutron detectors which allow a comprehensive study of lunar neutron emission: a pair of omnidirectional sensors for thermal and epithermal neutrons, a pair of Doppler filter sensors for thermal neutrons, four collimated sensors of epithermal neutrons, and a sensor of high‐energy neutrons. This paper describes the data reduction procedures to convert the raw data into the higher‐level PDS products containing neutron‐counting rate maps of the Moon.
A unified statistical model for hydrological variables including the selection of threshold for the peak over threshold method
Authors: Solari S. , Losada M. A.
Published: September 2012

This paper explores the use of a mixture model for determining the marginal distribution of hydrological variables, consisting of a truncated central distribution that is representative of the central or main‐mass regime, which for the cases studied is a lognormal distribution, and of two generalized Pareto distributions for the maximum and minimum regimes, representing the upper and lower tails, respectively. The thresholds defining the limits between these regimes and the central regime are parameters of the model and are calculated together with the remaining parameters by maximum likelihood. After testing the model with a simulation study we concluded that the upper threshold of the model can be used when applying the peak over threshold method. This will yield an automatic and objective identification of the threshold presenting an alternative to existing methods. The model was also applied to four hydrological data series: two mean daily flow series, the Thames at Kingston (United Kingdom), and the Guadalfeo River at Orgiva (Spain); and two daily precipitation series, Fort Collins (CO, USA), and Orgiva (Spain). It was observed that the model improved the fit of the data series with respect to the fit obtained with the lognormal (LN) and, in particular, provided a good fit for the upper tail. Moreover, we concluded that the proposed model is able to accommodate the entire range of values of some significant hydrological variables.
Seasonal and event dynamics of spatial soil moisture patterns at the small catchment scale
Authors: Rosenbaum U. , Bogena H. R. , Herbst M. , Huisman J. A. , Peterson T. J. , Weuthen A. , Western A. W. , Vereecken H.
Published: September 2012

Our understanding of short‐ and long‐term dynamics of spatial soil moisture patterns is limited due to measurement constraints. Using new highly detailed data, this research aims to examine seasonal and event‐scale spatial soil moisture dynamics in the topsoil and subsoil of the small spruce‐covered Wüstebach catchment, Germany. To accomplish this, univariate and geo‐statistical analyses were performed for a 1 year long 4‐D data set obtained with the wireless sensor network SoilNet. We found large variations in spatial soil moisture patterns in the topsoil, mostly related to meteorological forcing. In the subsoil, temporal dynamics were diminished due to soil water redistribution processes and root water uptake. Topsoil range generally increased with decreasing soil moisture. The relationship between the spatial standard deviation of the topsoil soil moisture (SDθ) and mean water content (
) showed a convex shape, as has often been found in humid temperate climate conditions. Observed scatter in topsoil SDθ(
) was explained by seasonal and event‐scale SDθ(
) dynamics, possibly involving hysteresis at both time scales. Clockwise hysteretic SDθ(
) dynamics at the event scale were generated under moderate soil moisture conditions only for intense precipitation that rapidly wetted the topsoil and increased soil moisture variability controlled by spruce throughfall patterns. This hysteretic effect increased with increasing precipitation, reduced root water uptake, and high groundwater level. Intense precipitation on dry topsoil abruptly increased SDθ but only marginally increased mean soil moisture. This was due to different soil rewetting behavior in drier upslope areas (hydrophobicity and preferential flow caused minor topsoil recharge) compared with the moderately wet valley bottom (topsoil water storage), which led to a more spatially organized pattern. This study showed that spatial soil moisture patterns monitored by a wireless sensor network varied with depth, soil moisture content, seasonally, and within single wetting and drying episodes. This was controlled by multiple factors including soil properties, topography, meteorological forcing, vegetation, and groundwater.
High‐resolution estimates of net community production and air‐sea CO2 flux in the northeast Pacific
Authors: Lockwood Deirdre , Quay Paul D. , Kavanaugh Maria T. , Juranek Lauren W. , Feely Richard A.
Published: September 2012

Rates of net community production (NCP) and air‐sea CO2 flux in the Northeast Pacific subarctic, transition zone and subtropical regions (22°N–50°N, 145°W–152°W) were determined on a cruise in August–September 2008 by continuous measurement of surface values of the ratio of dissolved oxygen to argon (O2/Ar) and the partial pressure of CO2 (pCO2). These estimates were compared with simultaneous measurements of sea surface temperature (SST), chlorophyll‐a (chl‐a), flow cytometry, and discrete surface nutrient concentrations. NCP and CO2 influx were greatest in the subarctic (45°N–50°N, 25.8 ± 4.6 and 4.1 ± 0.9 mmol C m−2 d−1) and northern transition zone (40°N–45°N, 17.1 ± 4.4 and 2.1 ± 0.5 mmol C m−2 d−1), with mean NCP ∼6–8× greater than mean CO2 invasion (error estimates reflect 1 σ confidence intervals). Contrastingly, the southern transition zone (32°N–40°N) and subtropics (22°N–32°N) had lower mean NCP (5.4 ± 1.8 and 8.1 ± 2.1 mmol C m−2 d−1, respectively) and mean CO2 efflux (3.0 ± 0.5 and 0.1 ± 0.0 mmol C m−2 d−1, respectively). In the subarctic and transition zone, NCP was highly correlated with surface chl‐a and CO2 influx, indicating strong coupling between the biological pump and CO2 uptake. Meridional trends in our NCP estimates in the transition zone and subtropics were similar to those for integrated summertime NCP along the cruise track determined using an upper ocean climatological carbon budget.
Decade‐scale decrease inb value prior to the M9‐class 2011 Tohoku and 2004 Sumatra quakes
Authors: Nanjo K. Z. , Hirata N. , Obara K. , Kasahara K.
Published: September 2012

The Gutenberg‐Richter frequency‐magnitude distribution of earthquakes has become well established in seismology. The slope of the relation between frequency and magnitude (b value) is typically 1, but it often shows variations around 1. Based on an analysis of seismicity prior to the 2011 Tohoku and 2004 Sumatra earthquakes (both in magnitude (M) 9 class), we show that the pronounced decade‐scale decrease inbvalue was a common precursor to both mega‐quakes around their hypocenters. This is the first report onM9‐class quakes to confirm a change inb value, which has been predicted based on the results of laboratory experiments. We propose that the b value is an important indicator of an impending great earthquake, and has great potential in terms of predicting a future large quake off the Pacific coast of Hokkaido, Japan.
Out‐of‐sequence thrusting in experimental Coulomb wedges: Implications for the structural development of mega‐splay faults and forearc basins
Authors: Haq Saad S. B.
Published: September 2012

We have investigated how an arc‐ward increase in bulk mechanical strength in an experimental accretionary prism influences the development, timing, and duration of slip on out‐of‐sequence thrusts. We have monitored the structural development and kinematics, in side‐view, during the development of a frontally accreting Coulomb wedge growing out in front of a critically tapered and mechanically stronger inner wedge. The inner‐wedge initially behaved as classic backstop to deformation with the most actively slipping thrust occurring near the deformation front on the forward most thrust structures. With continued growth, however, significant out‐of‐sequence slip on reactivated fore‐thrusts occurred in conjunction with slip on newly formed back‐thrusts in the inner‐wedge. This out‐of‐sequence deformation resulted in punctuated, rapid uplift of the model forearc basin and a noticeable break in topographic slope in the outer pro‐wedge. Cyclical out‐of‐sequence fore‐ and back‐thrusting, driven by ongoing frontal thrust imbrication, continued with periodic recovery of taper and was followed by additional out‐of‐sequence faulting and associated basin uplift.
Long period seismic source characterization at Popocatépetl volcano, Mexico
Authors: Arciniega‐Ceballos Alejandra , Dawson Phillip , Chouet Bernard A.
Published: September 2012

The seismicity of Popocatépetl is dominated by long‐period and very‐long period signals associated with hydrothermal processes and magmatic degassing. We model the source mechanism of repetitive long‐period signals in the 0.4–2 s band from a 15‐station broadband network by stacking long‐period events with similar waveforms to improve the signal‐to‐noise ratio. The data are well fitted by a point source located within the summit crater ∼250 m below the crater floor and ∼200 m from the inferred magma conduit. The inferred source includes a volumetric component that can be modeled as resonance of a horizontal steam‐filled crack and a vertical single force component. The long‐period events are thought to be related to the interaction between the magmatic system and a perched hydrothermal system. Repetitive injection of fluid into the horizontal fracture and subsequent sudden discharge when a critical pressure threshold is met provides a non‐destructive source process.
Regional surface mass anomalies from GRACE KBR measurements: Application of L‐curve regularization anda priori hydrological knowledge
Authors: Tangdamrongsub Natthachet , Hwang Cheinway , Shum C. K. , Wang Lei
Published: September 2012

We present a method of directly estimating surface mass anomalies at regional scales using satellite‐to‐satellite K‐band Ranging (KBR) data from the Gravity Recovery and Climate Experiment (GRACE) twin‐satellite mission. Geopotential differences based primarily on KBR measurement are derived using a modified energy integral method with an improved method to calibrate accelerometer measurements. Surface mass anomalies are computed based on a downward continuation process, with optimal regularization parameters estimated using the L‐curve criterion method. We derive the covariance functions in both space‐ and space‐time domains and use them as light constraints in the regional gravity estimation process in the Amazon basin study region. The space‐time covariance function has a time‐correlation distance of 1.27 months, which is evident that observations between neighboring months are correlated and the correlation should be taken into account. However, most of the current GRACE solutions did not consider such temporal correlations. In our study, the artifact in the regional gravity solution is mitigated by using the covariance functions. The averaged commission errors are estimated to be only 6.86% and 5.85% for the solutions based on the space‐covariance function (SCF) and the space‐time covariance function (STCF), respectively. Our regional gravity solution in the Amazon basin study region, which requires no further post‐processing, shows enhanced regional gravity signatures, reduced gravity artifacts, and the gravity solution agrees with NASA/GSFC's GRACE MASCON solution to about 1 cm RMS in terms of water thickness change over the Amazon basin study region. The regional gravity solution also retains the maximum signal energy while suppressing the short wavelength errors.
Linking enclave formation to magma rheology
Authors: Hodge K. F. , Jellinek A. M.
Published: September 2012

Magmatic enclaves record the history of deformation and disaggregation (i.e., fragmentation) of relatively hot, compositionally more mafic magmas injected into actively convecting silicic magma chambers through dikes. Enclave size distributions may provide crucial clues for understanding the nature of this mechanical mixing process. Accordingly, we conduct a comprehensive field study to measure enclave size distributions in six Cascade lava flows. Using results from recent fluid dynamics experiments along with thermodynamic and modeling constraints on key physical properties of the injected and host magmas (i.e., temperature, density and effective viscosity), we use the size distributions of enclaves to characterize the magmatic flow regime governing enclave formation. Scaling arguments suggest that the viscous stresses related to magma chamber flow acting against the yield strength of a crystallizing injected magma control the breakup of 1 m‐wide mafic dikes into millimeter‐ to centimeter‐scale enclaves. Our data analysis identifies a characteristic length scale of breakup that constrains the yield strength of the injected magmas in a more restrictive way than existing empirical models for yield strength based on crystal content. In all six lava flows, we show that the progressive fragmentation of the injected magma is self‐similar and characterized by a fractal dimensionDf ∼ 2, which is comparable to previous studies on enclaves. We also find a small but statistically significant dependence of Df on the effective viscosity ratio between host and enclave magmas, such that large variations in effective viscosity enhance breakup. This work demonstrates that field observations of enclave size distributions can reliably constrain the rheological and flow conditions in which enclaves form.
Sequential Bayesian techniques applied to non‐volcanic tremor
Authors: Yardim Caglar , Gerstoft Peter
Published: September 2012

This paper uses sequential Bayesian techniques such as particle filters and smoothers to track in time both the non‐volcanic tremor (NVT) source location on the plate interface and the angle of arrival via horizontal phase slowness. Sequential Bayesian techniques enable tracking of evolving geophysical parameters via sequential tremor observations. These techniques provide a formulation where the geophysical parameters that characterize dynamic, non‐stationary processes are continuously estimated as new data become available. In addition to the optimal solution, particle filters and smoothers can calculate the underlying probability densities for the desired parameters, providing the uncertainties in the estimates. The tremor tracking has been performed using array beamforming. Here it is demonstrated that the uncertainties both in the NVT source location estimates and phase slowness estimates are reduced using a particle filter compared to just using a beamformer based inversion. Particle smoothers further reduces the uncertainty, giving the best performance out of the three methods used here.
Space‐geodetic evidence for multiple magma reservoirs and subvolcanic lateral intrusions at Fernandina Volcano, Galápagos Islands
Authors: Bagnardi Marco , Amelung Falk
Published: September 2012

Using Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface deformation at Fernandina Volcano, Galápagos (Ecuador), acquired between January 2003 and September 2010, we study the structure and the dynamics of the shallow magmatic system of the volcano. Through the analysis of spatial and temporal variations of the measured line‐of‐sight displacement we identify multiple sources of deformation beneath the summit and the southern flank. At least two sources are considered to represent permanent zones of magma storage given their persistent or recurrent activity. Elastic deformation models indicate the presence of a flat‐topped magma reservoir at ∼1.1 km below sea level and an oblate‐spheroid cavity at ∼4.9 km b.s.l. The two reservoirs are hydraulically connected. This inferred structure of the shallow storage system is in agreement with previous geodetic studies and previous petrological analysis of both subaerial and submarine lavas. The almost eight‐year‐long observation interval provides for the first time geodetic evidence for two subvolcanic lateral intrusions from the central storage system (in December 2006 and August 2007). Subvolcanic lateral intrusions could provide the explanation for enigmatic volcanic events at Fernandina such as the rapid uplift at Punta Espinoza in 1927 and the 1968 caldera collapse without significant eruption.
Surface waves and wave‐coupled effects in lower atmosphere and upper ocean
Authors: Babanin Alexander V. , Onorato Miguel , Qiao Fangli
Published: September 2012

The article introduces the Special Issue of the Journal of Geophysical Research– Oceans which is based on the papers presented at or related to the new session of the General Assembly of the European Geosciences Union, first conducted in 2011. Topic of the session on the Surface Waves and Wave‐Coupled Effects highlights a new dimension of the present state of wind‐wave research. The surface waves is an important oceanographic topic in its own right, but it is also rapidly becoming clear that many large‐scale geophysical processes are essentially coupled with the surface waves, and those include climate, weather, tropical cyclones and other phenomena in the atmosphere and many issues of the upper‐ocean mixing below the interface.
Climate impacts of ice nucleation
Authors: Gettelman A. , Liu X. , Barahona D. , Lohmann U. , Chen C.
Published: September 2012

Several different ice nucleation parameterizations in two different General Circulation Models (GCMs) are used to understand the effects of ice nucleation on the mean climate state, and the Aerosol Indirect Effects (AIE) of cirrus clouds on climate. Simulations have a range of ice microphysical states that are consistent with the spread of observations, but many simulations have higher present‐day ice crystal number concentrations than in‐situ observations. These different states result from different parameterizations of ice cloud nucleation processes, and feature different balances of homogeneous and heterogeneous nucleation. Black carbon aerosols have a small (−0.06 Wm−2) and not statistically significant AIE when included as ice nuclei, for nucleation efficiencies within the range of laboratory measurements. Indirect effects of anthropogenic aerosols on cirrus clouds occur as a consequence of increasing anthropogenic sulfur emissions with different mechanisms important in different models. In one model this is due to increases in homogeneous nucleation fraction, and in the other due to increases in heterogeneous nucleation with coated dust. The magnitude of the effect is the same however. The resulting ice AIE does not seem strongly dependent on the balance between homogeneous and heterogeneous ice nucleation. Regional effects can reach several Wm−2. Indirect effects are slightly larger for those states with less homogeneous nucleation and lower ice number concentration in the base state. The total ice AIE is estimated at 0.27 ± 0.10 Wm−2 (1σ uncertainty). This represents a 20% offset of the simulated total shortwave AIE for ice and liquid clouds of −1.6 Wm−2.
Development of a fast, accurate radiative transfer model for the Martian atmosphere, past and present
Authors: Mischna Michael A. , Lee Christopher , Richardson Mark
Published: September 2012

We present details of an approach to creating ak‐distribution radiative transfer model (KDM) for use in the Martian atmosphere. Such models preserve the accuracy of more rigorous line‐by‐line models, but are orders of magnitude faster, and can be effectively implemented in 3‐D general circulation models. The approach taken here is sufficiently generalized that it can be employed for atmospheres of any arbitrary composition and mass, and demonstrations are provided for simulated atmospheres with a present‐day Martian surface pressure (∼6 mb) and a putative thick early Mars atmosphere (∼500 mb), both with and without atmospheric water vapor. KDM‐derived absorption coefficients are placed into a look‐up table at a set of gridded points in pressure, temperature and atmospheric composition, and a tri‐linear interpolation scheme is used to obtain the coefficients appropriate for the local atmospheric conditions. These coefficients may then be used within any of a variety of commonly used flux solvers to obtain atmospheric heating rates. A series of validation tests are performed with the KDM for both present‐day and early Mars atmospheric conditions, and the model is compared against several other widely used radiative transfer schemes, including several used in contemporary general circulation models. These validation results identify weaknesses in some other approaches and demonstrate the efficacy of the KDM, providing a rigorous test of these types of models for use in the Martian atmosphere. A demonstration of results obtained by implementing the KDM in a Mars general circulation model is provided.
Magnetic field direction and lunar swirl morphology: Insights from Airy and Reiner Gamma
Authors: Hemingway Doug , Garrick‐Bethell Ian
Published: September 2012

Many of the Moon's crustal magnetic anomalies are accompanied by high albedo features known as swirls. A leading hypothesis suggests that swirls are formed where crustal magnetic anomalies, acting as mini magnetospheres, shield portions of the surface from the darkening effects of solar wind ion bombardment, thereby leaving patches that appear bright compared with their surroundings. If this hypothesis is correct, then magnetic field direction should influence swirl morphology. Using Lunar Prospector magnetometer data and Clementine reflectance mosaics, we find evidence that bright regions correspond with dominantly horizontal magnetic fields at Reiner Gamma and that vertical magnetic fields are associated with the intraswirl dark lane at Airy. We use a genetic search algorithm to model the distributions of magnetic source material at both anomalies, and we show that source models constrained by the observed albedo pattern (i.e., strongly horizontal surface fields in bright areas, vertical surface fields in dark lanes) produce fields that are consistent with the Lunar Prospector magnetometer measurements. These findings support the solar wind deflection hypothesis and may help to explain not only the general form of swirls, but also the finer aspects of their morphology. Our source models may also be used to make quantitative predictions of the near surface magnetic field, which must ultimately be tested with very low altitude spacecraft measurements. If our predictions are correct, our models could have implications for the structure of the underlying magnetic material and the nature of the magnetizing field.
Flow processes near smooth and rough (concave) outer banks in curved open channels
Authors: Blanckaert K. , Duarte A. , Chen Q. , Schleiss A. J.
Published: September 2012

Flow processes near the (concave) outer bank in curved river reaches are investigated in a laboratory flume, with focus on the influence of the bank roughness. An outer‐bank cell of reversed secondary flow occurs for all the investigated roughness configurations of the outer bank. The cell widens the outer‐bank boundary layer, which reduces the flow forcing on the bank, but also advects high‐momentum fluid toward the lower part of the bank, which enhances the flow forcing on the bank. Increasing the roughness of the outer bank causes a considerable widening and strengthening of the outer‐bank cell, which amplifies both effects on the flow forcing. The widening of the outer‐bank boundary layer induced by the outer‐bank cell reduces the effective width of the channel, i.e., the width where most of the discharge is conveyed, which increases significantly the sediment transport capacity in the central part of the channel. The near‐bank processes are qualitatively similar but show considerable quantitative variations around the bend. The outer‐bank cell reaches its maximum strength in the zone that is most vulnerable to bed scour and bank erosion, which corroborates its morphological relevance. The outer cell is mainly generated by reversed near‐surface gradients in the profile of the streamwise velocity. The anisotropy of the cross‐stream turbulence is the major mechanism opposed to the outer‐bank cell. Increasing roughness of the outer bank amplifies all dominant mechanisms but does not modify their relative importance. The relevance of the experimental results for natural curved river configurations is discussed.
Bioavailability and diagenetic state of dissolved organic matter in riparian groundwater
Authors: Peter Simone , Shen Yuan , Kaiser Karl , Benner Ronald , Durisch‐Kaiser Edith
Published: September 2012

Riparian groundwater can exhibit considerable patchiness in the concentration and reactivity of dissolved organic matter (DOM), which ultimately shapes subsurface biogeochemical transformations. Free and combined amino acids are bioavailable constituents of DOM, and their concentration and composition can provide valuable information about the diagenetic state of DOM. Based on riparian groundwater samples and relevant DOM end‐member samples, we adapted the amino‐acid‐based marine DOM degradation index (DI) to groundwater. The groundwater DI was applied to evaluate the spatial and temporal variability in the bioavailability and diagenetic state of riparian DOM in a restored and a channelized section of the River Thur, Switzerland. Among different indicators for DOM diagenetic state (total hydrolysable amino acid concentrations, C‐normalized yields, and the contribution of nonprotein amino acids), the groundwater DI correlated best with the activity of the enzyme leucine‐aminopeptidase and bacterial secondary production in riparian groundwater. The “freshest” DOM was consistently found in the channel and during high‐flow conditions in the groundwater of the restored riparian section and was spatially constrained to a zone inhabited by a dense willow population. The use of amino acid data and the newly developed DI for DOM in groundwater is a promising approach for characterizing the spatial and temporal dynamics of DOM reactivity and diagenesis within riparian groundwater.
Initial GPS scintillation results from CASES receiver at South Pole, Antarctica
Authors: Deshpande K. B. , Bust G. S. , Clauer C. R. , Kim H. , Macon J. E. , Humphreys T. E. , Bhatti J. A. , Musko S. B. , Crowley G. , Weatherwax A. T.
Published: September 2012

Connected Autonomous Space Environment Sensor (CASES) Global Positioning System (GPS) software‐defined receivers developed for ionospheric scintillation studies have been deployed on Autonomous Adaptive Low‐Power Instrument Platforms (AAL‐PIP) at South Pole, Antarctica. In this paper, we describe the AAL‐PIP experimental setup focusing on CASES. We explain in detail the method developed for analyzing CASES data, and report initial AAL‐PIP CASES results. Furthermore, we compare the CASES measurements with those from a modified Novatel GSV4004 GPS Ionospheric Scintillations and TEC Monitor (GISTM) receiver at the South Pole. CASES receivers have been successfully deployed and reliably operated in equatorial and midlatitude regions. Four of these GPS receivers, for the first time, are deployed in high‐latitude regions as a part of the National Science Foundation (NSF) funded project of deploying space science instrument platforms, AAL‐PIPs, in Antarctica since December 2010–2011. We present initial scintillation results recorded by a CASES receiver at South Pole during the storm on 24 January 2012 along with AAL‐PIP magnetometer observations. We have deduced that the CASES receiver scintillation observations agree with those from the Novatel GPS scintillation receiver. Since this is the first time a CASES receiver has been deployed to operate in a high latitude, low temperature, and low humidity environment, we consider this comparison a demonstration of its reliable operation as a science‐grade scintillation receiver in such conditions. We plan to study high latitude ionospheric irregularities by using observations from CASES and other ancillary instruments from Antarctica coupled with physical parameters derived from models.
Displacement along the Red River Fault constrained by extension estimates and plate reconstructions
Authors: Mazur S. , Green C. , Stewart M. G. , Whittaker J. M. , Williams S. , Bouatmani R.
Published: September 2012

Significant E‐W extension and/or compression must have been generated by displacements along the Red River Fault (RRF) since its curvature does not match a small circle centered at the Euler pole for the Indochina–south China plate pair. The amount of extension perpendicular to the RRF offshore Vietnam depends on the magnitude of left‐lateral displacement along the RRF. In general, the larger the left‐lateral displacement along the fault, the smaller the amount of E‐W extension. All purely strike‐slip models of the opening of the South China Sea that assume large displacements (>250 km) along the RRF encounter major problems because they imply little extension, or even considerable shortening, offshore east Vietnam. This is inconsistent with the presence of large elongated basins offshore Vietnam. Using a plate tectonic model, we compare continental extension values implied by different magnitudes of displacement along the RRF with crustal stretching estimates derived from 2‐D profiles modeled from gravity data. We utilize 2‐D gravity forward models to restore the extended continental margin crust to its original position prior to extension. We find that substantial amounts of extension for offshore Vietnam can only be modeled assuming moderate displacements along the RRF compatible with the presence of a southward subducting proto–South China Sea. The total amount of ENE‐WSW extension offshore northern Vietnam constrained by our 2‐D gravity profiles and gravity inversion increases southward from 36 to 89 km along the Yinggehai Basin. These values of ENE‐WSW extension are consistent with 250 km of left‐lateral displacement along the RRF.
Forecast‐informed low‐flow frequency analysis in a Bayesian framework for the northeastern United States
Authors: Steinschneider Scott , Brown Casey
Published: September 2012

Structured variation in the frequency spectrum of critical hydrologic variables can have important implications for the design and management of water resources infrastructure, yet traditional hydrologic frequency analysis often ignores the influence of exogenous factors that can both precede and exert control over hydrologic responses. Moreover, emerging literature that has addressed predictable low‐frequency oscillations in the probabilistic nature of hydrologic variables has focused almost exclusively on flood flows. This study explores a new approach for conditioning the frequency spectrum of hydrologic extremes on seasonal predictors and applies the method to annual minimum 7 day low flows, a critical low‐flow statistic often utilized in water quality management and planning. A semiparametric local likelihood method is used to condition quantile estimates of the 7 day low flow on year‐to‐year hydroclimatic forecasts for two major rivers in the northeast United States. The local likelihood approach is employed in a Bayesian framework in which regional information is used to inform prior distributions of model parameters. The method is compared against a baseline approach that applies a static Bayesian inference with noninformative priors to derive unconditional parameter and quantile estimates. The implications of the approach for the efficacy of water quality regulations and as an adaptation to climate change are discussed.
Tradeoffs among watershed model calibration targets for parameter estimation
Authors: Price Katie , Purucker S. Thomas , Kraemer Stephen R. , Babendreier Justin E.
Published: September 2012

Hydrologic models are commonly calibrated by optimizing a single objective function target to compare simulated and observed flows, although individual targets are influenced by specific flow modes. Nash‐Sutcliffe efficiency (NSE) emphasizes flood peaks in evaluating simulation fit, while modified Nash‐Sutcliffe efficiency (MNS) emphasizes lower flows, and the ratio of the simulated to observed standard deviations (RSD) prioritizes flow variability. We investigated tradeoffs of calibrating streamflow on three standard objective functions (NSE, MNS, and RSD), as well as a multiobjective function aggregating these three targets to simultaneously address a range of flow conditions, for calibration of the Soil and Water Assessment Tool (SWAT) daily streamflow simulations in two watersheds. A suite of objective functions was explored to select a minimally redundant set of metrics addressing a range of flow characteristics. After each pass of 2001 simulations, an iterative informal likelihood procedure was used to subset parameter ranges. The ranges from each best‐fit simulation set were used for model validation. Values for optimized parameters vary among calibrations using different objective functions, which underscores the importance of linking modeling objectives to calibration target selection. The simulation set approach yielded validated models of similar quality as seen with a single best‐fit parameter set, with the added benefit of uncertainty estimations. Our approach represents a novel compromise between equifinality‐based approaches and Pareto optimization. Combining the simulation set approach with the multiobjective function was demonstrated to be a practicable and flexible approach for model calibration, which can be readily modified to suit modeling goals, and is not model or location specific.
NLRP3 promotes inflammation‐induced skin cancer but is dispensable for asbestos‐induced mesothelioma
Authors: Chow Melvyn T , Tschopp Jürg , Möller Andreas , Smyth Mark J
Published: September 2012

Asbestos exposure can result in serious and frequently lethal diseases, including malignant mesothelioma. The host sensor for asbestos‐induced inflammation is the NLRP3 inflammasome and it is widely assumed that this complex is essential for asbestos‐induced cancers. Here, we report that acute interleukin‐1β production and recruitment of immune cells into peritoneal cavity were significantly decreased in the NLRP3‐deficient mice after the administration of asbestos. However, NLRP3‐deficient mice displayed a similar incidence of malignant mesothelioma and survival times as wild‐type mice. Thus, early inflammatory reactions triggered by asbestos are NLRP3‐dependent, but NLRP3 is not critical in the chronic development of asbestos‐induced mesothelioma. Notably, in a two‐stage carcinogenesis‐induced papilloma model, NLRP3‐deficient mice showed a resistance phenotype in two different strain backgrounds, suggesting a tumour‐promoting role of NLRP3 in certain chemically‐induced cancer types.
Gobichelin A and B: mixed-ligandsiderophores discovered using proteomics
Authors: Chen Yunqiu , Unger Michelle , Ntai Ioanna , McClure Ryan A. , Albright Jessica C. , Thomson Regan J. , Kelleher Neil L.
Published: September 2012

PrISM (Proteomic Investigation of Secondary Metabolism), integrated with genomics and metabolomics, has led to the discovery of the new natural products, gobichelin A and B.
Haem oxygenase-1 overexpression alters intracellular iron distribution
Authors: Lanceta Lilibeth , Li Chi , Choi Augustine M. , Eaton John W.
Published: September 2012

Induction or ectopic overexpression of HO-1 (haem oxygenase 1) protects against a wide variety of disorders. These protective effects have been variably ascribed to generation of carbon monoxide (released during cleavage of the alpha-methene bridge of haem) and/or to production of the antioxidant bilirubin. We investigated HO-1-overexpressing A549 cells and find that, as expected, HO-1-overexpressing cells are resistant to killing by hydrogen peroxide. Surprisingly, these cells have approximately twice the normal amount of intracellular iron which usually tends to amplify oxidant killing. However, HO-1-overexpressing cells contain only ~25% as much ‘loose’ (probably redox active) iron. Indeed, inhibition of ferritin synthesis [via siRNA (small interfering RNA) directed at the ferritin heavy chain] sensitizes the HO-1-overexpressing cells to peroxide killing. It appears that HO-1 overexpression leads to enhanced destruction of haem, consequent 2–3-fold induction of ferritin, and compensatory increases in transferrin receptor expression and haem synthesis. However, there is no functional haem deficiency because cellular oxygen consumption and catalase activity are similar in both cell types. We conclude that, at least in many cases, the cytoprotective effects of HO-1 induction or forced overexpression may derive from elevated expression of ferritin and consequent reduction of redox active ‘loose’ iron.
Measurement of S‐phase duration of adult stem cells in the flatworm Macrostomum lignano by double replication labelling and quantitative colocalization analysis
Authors: Verdoodt Freija , Willems Maxime , Dhondt Ineke , Houthoofd Wouter , Bert Wim , De Vos Winnok H.
Published: September 2012

Platyhelminthes are highly attractive models for addressing fundamental aspects of stem cell biology in vivo. These organisms possess a unique stem cell system comprised of neoblasts that are the only proliferating cells during adulthood. We have investigated Ts (S‐phase duration) of neoblasts during homoeostasis and regeneration in the flatworm, Macrostomum lignano. A double immunohistochemical technique was used, performing sequential pulses with the thymidine analogues CldU (chlorodeoxyuridine) and IdU (iododeoxyuridine), separated by variable chase times in the presence of colchicine. Owing to the localized nature of the fluorescent signals (cell nuclei) and variable levels of autofluorescence, standard intensity‐based colocalization analyses could not be applied to accurately determine the colocalization. Therefore, an object‐based colocalization approach was devised to score the relative number of double‐positive cells. Using this approach, Ts (S‐phase duration) in the main population of neoblasts was ∼13 h. During early regeneration, no significant change in Ts was observed.
Influence of waterlogging on yield of wheat (Triticum aestivum), redox potentials, and concentrations of microelements in different soils in India and Australia
Authors: Yaduvanshi N. P. S. , Setter T. L. , Sharma S. K. , Singh K. N. , Kulshreshtha N.
Published: September 2012

Effects of waterlogging relative to drained conditions on grain yield were studied in relation to soil redox potentials and microelements (Fe and Mn) in soils from India and Western Australia, using waterlogging intolerant and tolerant varieties of wheat (Triticum aestivum L.) The grain yield of wheat decreased significantly with increasing duration of waterlogging in sodic soils. In Indian soils, soil redox potentials decreased sharply after waterlogging and were 150 and 210 mV at 10 days after waterlogging in alkali soil at pH 8.5 and pH 9.2, respectively. Two Australian soils were similarly reduced in redox potential with values of ~200 mV at 10 days after waterlogging, and redox potentials were further reduced to 100 mV and –50 mV for soils without and with added glucose, respectively, after 40 days of waterlogging. The Indian soils tended to be 2–10 times higher in DTPA-Mn than the Australian soils, whereas the Australian soils were up to 10 times higher in DTPA-Fe than the Indian soils. These increases were up to 10 and 60 times higher, respectively, than reported critical concentrations for wheat. After 21 days of waterlogging, the Indian soils were drained, and the re-aeration resulted in an increase in redox potential and a decrease in DTPA-Fe and -Mn in soil solutions, but this occurred slowly, taking 15–25 days. The results support the hypothesis that waterlogging tolerance is a product of tolerance to anoxia and microelement toxicities, and that these are both key factors limiting plant growth during and after waterlogging. These factors may also contribute to the large differences in screening wheat varieties for waterlogging tolerance in different soils.
Proton release from tea plant (Camellia sinensis L.) roots induced by Al(III) under hydroponic conditions
Authors: Wan Qing , Xu Ren-kou , Li Xing-hui
Published: September 2012

The mechanisms for soil acidification induced by tea plant growth are not well understood. Proton release from tea plant (Camellia sinensis L.) roots induced by aluminium (Al(III)) in solution-culture experiments was examined with an automatic titration system, to determine the effect of Al(III) uptake by the plants on soil acidification. Results indicated that the uptake of Al(III) by tea plants led to proton release from their roots and thus an increase in soil acidification. The uptake of Al(III) by tea plants and the amount of protons released from the roots were greater at pH 4.5 than at pH 5.0 and 4.0 and increased with increasing initial Al(III) concentration in the culture solutions. With the same initial pH, the amount of protons released from tea plant roots at a constant pH was much higher than that at non-constant pH. The presence of ammonium increased the amount of protons released from tea plant roots. Therefore, the uptake of Al by tea plants and subsequent release of protons from their roots may be an important mechanism by which they acidify soils in tea gardens.