bluuebunny/crossref_metadata_2025 huggingface dataset:
Business to Business Relationships: The Paradox of Network Constraints?
Authors: Ballantyne David , Williams John
Published: June 2010

The marketing significance of consumer and business relationships was reclaimed in the 1990s when relationship marketing came into its own as a field of marketing inquiry. This article contributes to the current debate about the scope of relationship marketing and especially the meaning of network relationships. This question is discussed in a business to business context, using the network approach of the Industrial Marketing and Purchasing (IMP) group as a lens. We critique three relationship ‘paradoxes’ (Håkansson and Ford, 2002) which appear to place limits on managerial action in networks. These paradoxes are considered from alternative viewpoints in order to attempt a resolution to the logical conundrum they present. We conclude that Håkansson and Ford's paradoxes indeed signal a range of constraints on managerial independence but the situation is far from paradoxical. We offer suggestions for cognitive mapping of relationships within the knowable network at the level of the firm and call for an ontological shift in understanding firm-level strategies in the network context.
Substrate metabolism, appetite and feeding behaviour under low and high energy turnover conditions in overweight women
Authors: Burton Francesca L. , Malkova Dalia , Caslake Muriel J. , Gill Jason M. R.
Published: June 2010

The present study aimed to investigate whether substrate metabolism, appetite and feeding behaviour differed between high and low energy turnover conditions. Thirteen overweight premenopausal women completed two 1 d trials: low energy turnover (LET) and high energy turnover (HET), in a randomised, cross-over design. In LET, subjects consumed a test breakfast (49 % carbohydrate, 37 % fat, 14 % protein) calculated to maintain energy balance over a 6 h observation period, during which metabolic rate and substrate utilisation were measured and blood samples taken. Immediately following this anad libitumbuffet meal was provided. HET was identical to LET, except that subjects walked on a treadmill for 60 min at 50 % VO2maxbefore the test breakfast, which was increased in size (by about 65 %) to replace the energy expended during the walk and maintain energy balance over the observation period. Postprandial fat balance (i.e. the difference between fat intake and oxidation) was lower and carbohydrate balance higher in HET compared with LET throughout the postprandial period (P < 0·05 for both). After the buffet meal, carbohydrate balance did not differ between trials but energy and fat balances were lower (by 0·28 MJ and 11·6 g, respectively) in HET compared with LET (P < 0·001 for both). Carbohydrate balance immediately before the buffet meal correlated negatively with buffet energy intake (r− 0·49) and postprandial acylated ghrelin responses (r− 0·48), and positively with postprandial glucose responses (r0·49). These findings demonstrate that HET resulted in a more positive carbohydrate balance than LET, which associated with lower subsequent energy intake. This may have implications for the regulation of body weight.
Selenoprotein P gene r25191g/a polymorphism and quantification of selenoprotein P mRNA level in patients with Kashin-Beck disease
Authors: Sun Wenyan , Wang Xin , Zou Xiuzhen , Song Ruixia , Du Xiaohong , Hu Jun , Xiong Yongmin
Published: June 2010

Kashin-Beck disease (KBD) is an endemic and deformable osteoarthrosis. Epidemiological study has revealed that lower Se level is the principal environmental factor in the pathogenesis of KBD. Selenoprotein P (SEPP1) is a special selenoprotein, which is the primary form of Se in vivo. Our aim was to investigate the putative association of SEPP1 r25191g/a single nucleotide polymorphism (SNP) with KBD risk and the SEPP1 transcriptional levels in whole blood and articular cartilage tissue of KBD cases and controls, respectively. One hundred and sixty-seven cases with KBD and 166 control subjects from Shaanxi province of China were included in the present study. The detection of SNP r25191g/a in the 3′ untranslated region was performed using an efficient technique, tetra-primer amplification refractory mutation system PCR. A quantitative analysis of SEPP1 mRNA in KBD and control groups by real-time PCR was also performed. The present results show no significant difference in genotype and allele distribution of SNP r25191g/a between individuals with KBD and controls (P = 0·279 and 0·428, respectively). There was also no association between SNP r25191g/a and risk of KBD (OR 1·153; 95 % CI 0·533, 2·496). However, the frequency of the rare genotype AG of SNP r25191g/a was significantly lower in Chinese population than in the Caucasians. It was shown that the SEPP1 mRNA expression in whole blood was lower in KBD patients than in the control group (0·149-fold, P < 0·001), but that it was much higher in articular cartilage tissue (4·53-fold, P = 0·012). Our aim was to lay a foundation for us to further study the association between the pathogenesis of KBD and SEPP1.
Fractal functional quantization of mean-regular stochastic processes
Authors: GRAF SIEGFRIED , LUSCHGY HARALD , PAGÈS GILLES
Published: June 2010

We investigate the functional quantization problem for stochastic processes with respect toLp(IRd, μ)-norms, where μ is a fractal measure namely, μ is self-similar or a homogeneous Cantor measure. The derived functional quantization upper rate bounds are universal depending only on the mean-regularity index of the process and the quantization dimension of μ and as universal rates they are optimal. Furthermore, for arbitrary Borel probability measures μ we establish a (nonconstructive) link between the quantization errors of μ and the functional quantization errors of the process in the spaceLp(IRd, μ).
Accurate Detection of Low Levels of Fluorescence Emission in Autofluorescent Background: Francisella-Infected Macrophage Cells
Authors: Davis Ryan W. , Timlin Jerilyn A. , Kaiser Julia N. , Sinclair Michael B. , Jones Howland D.T. , Lane Todd W.
Published: June 2010

Cellular autofluorescence, though ubiquitous when imaging cells and tissues, is often assumed to be small in comparison to the signal of interest. Uniform estimates of autofluorescence intensity obtained from separate control specimens are commonly employed to correct for autofluorescence. While these may be sufficient for high signal-to-background applications, improvements in detector and probe technologies and introduction of spectral imaging microscopes have increased the sensitivity of fluorescence imaging methods, exposing the possibility of effectively probing the low signal-to-background regime. With spectral imaging, reliable monitoring of signals near or even below the noise levels of the microscope is possible if compensation for autofluorescence and background signals can be performed accurately. We demonstrate the importance of accurate autofluorescence modeling and the utility of spectral imaging and multivariate analysis methods using a case study focusing on fluorescence confocal spectral imaging of host-pathogen interactions. In this application fluorescent proteins are produced when Francisella novicida invade host macrophage cells. The resulting analyte signal is spectrally overlapped and typically weaker than the cellular autofluorescence. In addition to discussing the advantages of spectral imaging for following pathogen invasion, we present the spectral properties and cellular origin of macrophage autofluorescence.
Behavior of Au Species in Au/Fe2O3 Catalysts Characterized by Novel In Situ Heating Techniques and Aberration-Corrected STEM Imaging
Authors: Allard Lawrence F. , Flytzani-Stephanopoulos Maria , Overbury Steven H.
Published: June 2010

The recent advent of a novel design of in situ heating technology for electron microscopes has permitted unprecedented control of elevated temperature studies of catalytic materials, particularly when coupled with the sub-Ångström imaging performance of a modern aberration-corrected scanning transmission electron microscope (STEM). Using micro-electro-mechanical-systems (MEMS)-based Aduro™ heating chips from Protochips, Inc. (Raleigh, NC, USA) allows nearly instantaneous heating and cooling of catalyst powders, avoiding effects of temperature ramping as experienced with standard heating stages. The heating technology also provides stable operation limited only by the inherent drift in the microscope stage, thus allowing full image resolution to be achieved even at elevated temperatures. The present study details the use of both the high X-Y spatial resolution in both dark-field and simultaneous bright-field imaging, along with the high resolution in Z (depth sectioning) provided by the large probe incidence semiangle in the aberration-corrected instrument, to characterize the evolution of microstructure in a commercial Au/Fe2O3 water-gas shift catalyst during elevated temperature treatment. The phenomenon of Au diffusion to the surface of hematite support particles to form discrete crystalline Au nanoparticles in the 1–2 nm size range, after a prior leaching treatment to remove surface Au species has been characterized.
Transmission Electron Microscopy of Lipid Vesicles for Drug Delivery: Comparison between Positive and Negative Staining
Authors: Bello Valentina , Mattei Giovanni , Mazzoldi Paolo , Vivenza Nicoletta , Gasco Paolo , Idee Jean Marc , Robic Caroline , Borsella Elisabetta
Published: June 2010

Lipid-containing nanostructures, in the form of solid lipid nanoparticles or iron oxide nanoparticles (NPs) coated with a lipid shell, were used as case studies for assessing and optimizing staining for transmission electron microscopy structural and compositional characterization. These systems are of paramount importance as drug delivery systems or as bio-compatible contrast agents. In particular, we have treated the systems with a negative (phospshotungstic acid) or with a positive (osmium tetroxide) staining agent. For iron-oxide NPs coated with the lipid shell, negative staining was more efficient with respect to the positive one. Nevertheless, in particular cases the combination of the two staining procedures provided more complete morphological and compositional characterization of the particles.
Can satellite glial cells be therapeutic targets for pain control?
Authors: Jasmin Luc , Vit Jean-Philippe , Bhargava Aditi , Ohara Peter T.
Published: June 2010

Satellite glial cells (SGCs) undergo phenotypic changes and divide the following injury into a peripheral nerve. Nerve injury, also elicits an immune response and several antigen-presenting cells are found in close proximity to SGCs. Silencing SCG-specific molecules involved in intercellular transport (Connexin 43) or glutamate recycling (glutamine synthase) can dramatically alter nociceptive responses of normal and nerve-injured rats. Transducing SGCs with glutamic acid decarboxylase can produce analgesia in models of trigeminal pain. Taken together these data suggest that SGCs may play a role in the genesis or maintenance of pain and open a range of new possibilities for curing neuropathic pain.
Unifying the field of comparative judicial politics: towards a general theory of judicial behaviour
Authors: Dyevre Arthur
Published: June 2010

The field of judicial politics had long been neglected by political scientists outside the United States. But the past 20 years have witnessed considerable change. There is now a large body of scholarship on European courts and judges. In addition, judicial politics is on its way to become a sub-field of comparative politics in its own right. Examining the models used in the literature, this article suggests that this geographical convergence is also bringing about theoretical convergence. One manifestation of theoretical convergence is that models of judicial decision-making once deemed inapplicable in Europe are now used in studies of European courts too. But the convergence trend goes further. What we already know about judges and the contexts in which they operate suggests a way of reconciling the various attitudinal and institutionalist approaches used by scholars on both sides of the Atlantic within a general, unifying theory of judicial behaviour. The emerging theory provides a framework to assess the weight and interactions of a wide range of determinants of judicial decision-making across countries and legal systems.
A case study of EMIC wave‐associated He+ energization in the outer magnetosphere: Cluster and Double Star 1 observations
Authors: Zhang J.‐C. , Kistler L. M. , Mouikis C. G. , Dunlop M. W. , Klecker B. , Sauvaud J.‐A.
Published: June 2010

On December 4, 2004, the COmposition and DIstribution Function (CODIF) Analyzer on board the Cluster spacecraft observed a prolonged He+ energization event from 06:00 to 10:30 UT. In this paper, we perform a case study of the event by using in situ plasma and magnetic field measurements from the Cluster and Double Star Program (DSP) Tan Ce 1 (TC1) spacecraft. In the event, the He+ ions were energized up to 1 keV. The He+ ion heating was associated with three consecutive EMIC waves, which occurred near the dusk‐side magnetospheric flank, L = 13.1–14.5, a region where EMIC wave activity has not been reported before. As a result, the observed wave frequencies, as low as 0.03 Hz, are far lower than those of typical EMIC waves, i.e., 0.1–5 Hz. It is found that the first wave had already propagated for some time and exhibited a large spatial extent, while the latter two were newly generated at the expense of anisotropic, energetic (>1 keV) protons and had sharper spatial boundaries. Unlike the patchy wave activity, the He+ energization region displayed a continuous spatial distribution and corresponded to a region of enhanced cold ion density. The reason for the presence of the anisotropic protons and cold density in this region is most likely the quiet geomagnetic conditions, which allow the proton anisotropy to develop and the plasmaspheric plume to expand into such high L‐values. A discrepancy, found in the comparison of particle and wave observations with linear theory, suggests that the theory should include He+ and/or nonlinear effects.
Cassini observations of narrowband radio emissions in Saturn's magnetosphere
Authors: Wang Z. , Gurnett D. A. , Fischer G. , Ye S.‐Y. , Kurth W. S. , Mitchell D. G. , Leisner J. S. , Russell C. T.
Published: June 2010

The Radio and Plasma Wave Science instrument (RPWS) on board the Cassini spacecraft has detected numerous narrowband radio emissions in Saturn's magnetosphere from September 2005 to May 2007. Typically, the narrowband radio emissions occur after an intensification of Saturn kilometric radiation (SKR) and last for several days. These emissions often occur near 5 kHz, with a modulation period of about 10.8 h, similar to the planet's rotation period. Other apparently associated bands also occur at higher frequencies, typically from 20 to 30 kHz. Both 5 kHz and 20 to 30 kHz emissions tend to decrease in intensity with increasing time and slowly drift upward in frequency after the onset. Our study shows that the narrowband radio emissions tend to be observed on the nightside at a radial distance range from 5 to 50 Saturn radii and tend to be observed more frequently at higher latitudes. The rotational modulation of narrowband radio emissions in Saturn's magnetosphere acts like a flashing light rather than a rotating beacon, similar to the source of SKR. These emissions are believed to be generated by mode conversion from anisotropy‐driven electrostatic instabilities near the upper hybrid frequency. Comparisons with Cassini neutral particle imaging data show that transient hot plasma clouds, corotating with the planet inside the orbit of Titan, might be the source for narrowband radio emissions. Comparisons with Cassini Magnetometer data reveal that the narrowband radio emissions tend to occur 1 or 2 days after the compression of the magnetotail.
Straining and advection contributions to the mixing process of the Patos Lagoon coastal plume, Brazil
Authors: Marques Wilian C. , Fernandes Elisa H. L. , Moller Osmar O.
Published: June 2010

The Southern Brazilian Shelf is a region influenced by freshwater, and the evolution of stratification can present important ecological consequences in this area. The aim of this paper was to investigate the importance of straining and advection processes that affect the stratification and destratification of the water column along the Southern Brazilian inner shelf, a region that is influenced by the Patos Lagoon coastal plume. The study was carried out through 3‐D numerical modeling experiments and the results were analyzed using the potential energy anomaly equation and wavelet analysis. Results showed that the potential energy anomaly showed strong variability over a time scale of several days and followed the wind pattern over the study region, and was accompanied by the monthly modulation of river discharge and remote effects associated with variability in oceanic circulation. However, the most important events in synoptic time scales occurred in periods shorter than 20 days and were coincident with the passage of meteorological systems over the study region. Straining and advection were the most important mechanisms for the evolution of stratification in the adjacent coastal region. Nonlinearities and dispersion terms were as important as modulation effects, mainly during periods of high fluvial discharge. Close to the Patos Lagoon mouth, vertical advection explained most of the stratification evolution, due to the morphological characteristics in this region. In the frontal region and far field of the plume, the following two regions must be considered: the northeast part, which is characterized by the convergence of the coastal currents and ebb flows associated with the freshwater discharge that promote the domination of the cross‐shore straining and advection, and the southwest part, which is controlled by the coastal currents that result in the domination by alongshore straining and advection and cross‐shore advection terms. Close to the mouth of the Patos Lagoon, the occurrence of downward velocities generated downward displacement of the isopycnals, which decreases the potential energy anomalies, and vice versa. Near the frontal region, the anomalies were dependent on the intensity of the fluvial discharge. During moderate to high discharge events, the northeastward currents intensified mixing along shore, which decreased the potential energy anomalies. In the same way, the southwestward currents intensified the spreading of freshwater and increased the stratification and the potential energy anomalies.
Vertical profiling of tropical precipitation using passive microwave observations and its implications regarding the crash of Air France 447
Authors: Haddad Ziad S. , Park Kyung‐Won
Published: June 2010

In a recent study by Haddad and Park (2009), a method was proposed to use colocated simultaneous observations by the space‐borne Tropical Rainfall Measuring Mission (TRMM) precipitation radar and microwave imager to train the microwave radiometer to retrieve vertical profiles of precipitation in the absence of radar observations. This radar‐trained passive‐microwave approach was developed for midlatitude precipitation regimes, where it was found that the inhomogeneity of the rain within the radiometer field of view was the main impediment to the estimation of the vertical distribution of rain. The approach constrains the brightness temperature combinations used in the retrieval to lie in the orthogonal complement to the two main clear‐sky principal components in brightness temperature space. This note summarizes the results of applying this approach to observations over the Atlantic Intertropical Convergence Zone during May 2009 and deriving estimates of the uncertainty in passive‐microwave retrievals of the storm‐top height and of the first vertical principal component of the rain. The results are illustrated on a serendipitous granule of data taken while the TRMM radar was unfortunately not operational, about 20 min after the last transmission from the ill‐fated flight Air France 447.
Temperature‐dependent photoabsorption cross section of cyanodiacetylene in the vacuum UV
Authors: Fray N. , Bénilan Y. , Gazeau M.‐C. , Jolly A. , Schwell M. , Arzoumanian E. , Ferradaz T. , Es‐Sebbar Et. , Guillemin J.‐C.
Published: June 2010

Using synchrotron radiation as a tunable VUV light source, we have measured, for the first time, the absolute photoabsorption cross sections of HC5N with a spectral resolution of 0.05 nm in the region between 80 and 205 nm from 233 to 298 K. The measured cross sections are used to predict the HC5N photodestruction rate in the solar system and to model a transmission spectrum in Titan's atmosphere. Comparing the latter with that acquired by the Ultraviolet Imaging Spectrograph on board the Cassini spacecraft, we have determined an upper limit of 2.7 × 10−5 on the HC5N abundance at 1100 km.
Assessing general relationships between aboveground biomass and vegetation structure parameters for improved carbon estimate from lidar remote sensing
Authors: Ni‐Meister Wenge , Lee Shihyan , Strahler Alan H. , Woodcock Curtis E. , Schaaf Crystal , Yao Tian , Ranson K. Jon , Sun Guoqing , Blair J. Bryan
Published: June 2010

Lidar‐based aboveground biomass is derived based on the empirical relationship between lidar‐measured vegetation height and aboveground biomass, often leading to large uncertainties of aboveground biomass estimates at large scales. This study investigates whether the use of any additional lidar‐derived vegetation structure parameters besides height improves aboveground biomass estimation. The analysis uses data collected in the field and with the Laser Vegetation Imaging Sensor (LVIS), and the Echidna® validation instrument (EVI), a ground‐based hemispherical‐scanning lidar data in New England in 2003 and 2007. Our field data analysis shows that using wood volume (approximated by the product of basal area and top 10% tree height) and vegetation type (conifer/softwood or deciduous/hardwood forests, providing wood density) has the potential to improve aboveground biomass estimates at large scales. This result is comparable to previous individual‐tree based analyses. Our LVIS data analysis indicates that structure parameters that combine height and gap fraction, such as RH100*cover and RH50*cover, are closely related to wood volume and thus biomass particularly for conifer forests. RH100*cover and RH50*cover perform similarly or even better than RH50, a good biomass predictor found in previous study. This study shows that the use of structure parameters that combine height and gap fraction (rather than height alone) improves the aboveground biomass estimate, and that the fusion of lidar and optical remote sensing (to provide vegetation type) will provide better aboveground biomass estimates than using lidar alone. Our ground lidar analysis shows that EVI provides good estimates of wood volume, and thus accurate estimates of aboveground biomass particularly at the stand level.
Deepest mantle viscosity: Constraints from Earth rotation anomalies
Authors: Peltier W. R. , Drummond R.
Published: June 2010

The radial variation of viscosity from Earth's surface to the core‐mantle boundary is most accurately determined on the basis of observations related to the glacial isostatic adjustment (GIA) process. Beneath a depth of approximately 1250 km the primary constraints available pertain to the anomalies in Earth's rotational state that have previously been shown to be intimately linked to the same GIA process responsible for postglacial sea level variability. It is demonstrated that these anomalies are capable of resolving a difference between D″ viscosity and that of the overlying region which extends upwards to the 1250 km depth horizon. A “trade‐off” is shown to exist between the viscosities in these deepest mantle layers that may be resolved by the observed direction of true polar wander.
Temporary acceleration of the hydrological cycle in response to a CO2 rampdown
Authors: Wu Peili , Wood Richard , Ridley Jeff , Lowe Jason
Published: June 2010

Current studies of the impact of climate change mitigation options tend to scale patterns of precipitation change linearly with surface temperature. Using climate model simulations, we show a nonlinear hydrological response to transient global warming and a substantial side effect of climate mitigation. In an idealised representation of mitigation action, where we reverse the trend of global warming, the precipitation response shows significant hysteresis behaviour due to heat previously accumulated in the ocean. Stabilising or reducing CO2 concentrations in the atmosphere is found temporarily to strengthen the global hydrological cycle, while reducing rainfall over some tropical and subtropical regions. The drying trend under global warming over The Amazon, Australia and western Africa may intensify for decades after CO2 reductions. The inertia due to accumulated heat in the ocean implies a commitment to hydrological cycle changes long after stabilisation or reduction of atmospheric CO2 concentration.
Impact of various inorganic oxyanions on the removal rates of hexavalent chromium mediated by zero-valent iron
Authors: Rivero-Huguet Mario , Marshall William D.
Published: June 2010

Environmental context.Oxyanions in soil extract can interfere with the zero valent iron induced reduction of chromium(VI) to chromium(III). At pH 6, the reaction rate was decreased (2 to 6-fold) by an equivalent of arsenate, phosphate or silicate but was increased by sulfate and remained unchanged by borate or nitrate. At pH 2, not only was the rate of reaction dramatically increased (∼900-fold) but interferences from the major components of soil solution (nitrate, silicate and sulfate) were minimised.
Abstract.The rate of zero-valent iron (ZVI) mediated reduction of CrVI was dependent on the condition of the ZVI surface, the pH of the medium and on the presence of inorganic oxyanions that can interfere with the process by competing for active sites on the ZVI surface. Whereas at pH 2, a single exponential decay provided an acceptable fit to the data, for pH 6 an appreciably better fit to the data was obtained with the sum of two exponential decays. The surface area normalised rate constant (kSA1) corresponding to the first decay was considered to model reactions at exposed active sites and kSA2, corresponding to the second decay, was considered to model decomposition kinetics through an intervening oxyhydroxide layer above the ZVI surface. The rate of CrVI reduction was decreased ∼900-fold when the pH was increased from 2 to 6 in the absence of competing ions. At pH 2, interferences from the major components of soil solution (nitrate, silicate and sulfate) were minimised.
Tolerance of seven perennial grasses to high nickel in sand culture
Authors: Kopittke P. M. , Blamey F. P. C. , Kopittke R. A. , Asher C. J. , Menzies N. W.
Published: June 2010

Environmental context.High concentrations of Ni in soil may occur either naturally or as a result of human activities. We used a sand culture system to investigate the suitability of seven perennial grasses for the revegetation of Ni-contaminated sites. This study provides information on the toxic effects of Ni on plant growth and gives consideration to the health of animals consuming these plants, thereby increasing the accuracy of risk assessments.
Abstract.Although grasses are commonly used to revegetate disturbed areas, comparatively little is known regarding the tolerance of perennial grasses to toxic levels of trace metals. A sand culture experiment was conducted to investigate the tolerance of seven perennial grasses to high concentrations of Ni. The activity of Ni2+ in solution that resulted in a 50% reduction in shoot growth ranged from 50 µM for Sabi grass (Urochloa mosambicensis (Hack.) Dandy cv. Saraji) to 13 µM for curly Mitchell grass (Astrebla lappacea (Lindl.) Domin). In most grasses, growth in the high-Ni2+ treatments resulted in shoot Ni concentrations at or above the toxicity threshold for consumption by cattle (100 µg Ni g–1). Based upon their tolerance to Ni, and the extent to which they translocate Ni to the shoots, Sabi grass, signal grass (Brachiaria decumbens Stapf. cv. Basilisk) and buffel grass (Cenchrus ciliaris (L.) cv. Biloela) appear well suited for the phytostabilisation of Ni-contaminated sites in subtropical and tropical regions.
A method for determination of retention of silver and cerium oxide manufactured nanoparticles in soils
Authors: Cornelis Geert , Kirby Jason K. , Beak Douglas , Chittleborough David , McLaughlin Mike J.
Published: June 2010

Environmental context.Soils are the environmental compartment likely to be exposed most to manufactured nanoparticles, but there is no method available at present to assess their retention, which determines potential mobility and bioavailability. Optimisation and application of a method to determine retention values for silver (Ag) and cerium oxide (CeO2) manufactured nanoparticles in soils found in many cases that they differed from the partitioning of their bulk and soluble counterparts. Wider application of this method can assist in comparing the risk of many different manufactured nanoparticles with other contaminants in soil systems and model their relationship to soil properties.
Abstract.Methods to study the retention of manufactured nanoparticles (MNP) are lacking for soils that are likely to be increasingly exposed to MNP. In this study we present, for the first time, a method to determine retention values (Kr) of Ag and CeO2 MNP, that can be ranked among solid–liquid partitioning (Kd) values of bulk (micrometre-sized) forms, soluble salts and other possible contaminants of soils. After method optimisation, suspensions containing 1.24 mg kg–1 Ag as Ag MNP and 1.30 mg kg–1 Ce as CeO2 MNP were added to five soils. More than 7% of Ag MNP occurred as soluble AgI after 24 h and the range of Kr values of Ag MNP (77–2165 L kg–1) and CeO2 MNP (1.1–2828 L kg–1) contrasted with Kd values of soluble AgI, CeIII and CeIV salts and bulk Ag and CeO2 powders in different soils.
Divergent metabolome and proteome suggest functional independence of dual phloem transport systems in cucurbits
Authors: Zhang Baichen , Tolstikov Vladimir , Turnbull Colin , Hicks Leslie M. , Fiehn Oliver
Published: June 2010

Cucurbitaceous plants (cucurbits) have long been preferred models for studying phloem physiology. However, these species are unusual in that they possess two different phloem systems, one within the main vascular bundles [fascicular phloem (FP)] and another peripheral to the vascular bundles and scattered through stem and petiole cortex tissues [extrafascicular phloem (EFP)]. We have revisited the assumption that the sap released after shoot incision originates from the FP, and also investigated the long-standing question of why the sugar content of this sap is ~30-fold less than predicted for requirements of photosynthate delivery. Video microscopy and phloem labeling experiments unexpectedly reveal that FP very quickly becomes blocked upon cutting, whereas the extrafascicular phloem bleeds for extended periods. Thus, all cucurbit phloem sap studies to date have reported metabolite, protein, and RNA composition and transport in the relatively minor extrafascicular sieve tubes. Using tissue dissection and direct sampling of sieve tube contents, we show that FP in fact does contain up to 1 M sugars, in contrast to low-millimolar levels in the EFP. Moreover, major phloem proteins in sieve tubes of FP differ from those that predominate in the extrafascicular sap, and include several previously uncharacterized proteins with little or no homology to databases. The overall compositional differences of the two phloem systems strongly indicate functional isolation. On this basis, we propose that the fascicular phloem is largely responsible for sugar transport, whereas the extrafascicular phloem may function in signaling, defense, and transport of other metabolites.
Motorized RhoGAP myosin IXb (Myo9b) controls cell shape and motility
Authors: Hanley Peter J. , Xu Yan , Kronlage Moritz , Grobe Kay , Schön Peter , Song Jian , Sorokin Lydia , Schwab Albrecht , Bähler Martin
Published: June 2010

Directional motility is a fundamental function of immune cells, which are recruited to sites of pathogen invasion or tissue damage by chemoattractant signals. To move, cells need to generate lamellipodial membrane protrusions at the front and retract the trailing end. These elementary events are initiated by Rho-family GTPases, which cycle between active GTP-bound and inactive GDP-bound states. How the activity of these “molecular switches” is spatially coordinated is only beginning to be understood. Here, we show that myosin IXb (Myo9b), a Rho GTPase-activating protein (RhoGAP) expressed in immune cells, is essential for coordinating the activity of Rho. We generated Myo9b-deficient mice and show that Myo9b−/−macrophages have strikingly defective spreading and polarization. Furthermore, Myo9b−/−macrophages fail to generate lamellipodia in response to a chemoattractant, and migration in a chemotactic gradient is severely impaired. Inhibition of Rho rescues the Myo9b−/−phenotype, but impairs tail retraction. We also found that Myo9b is important in vivo. Chemoattractant-induced monocyte recruitment to the peritoneal cavity is substantially reduced in Myo9b−/−mice. Thus, we identify the “motorized Rho inhibitor” Myo9b as a key molecular component required for spatially coordinated cell shape changes and motility.
Cochlea-scaled entropy, not consonants, vowels, or time, best predicts speech intelligibility
Authors: Stilp Christian E. , Kluender Keith R.
Published: June 2010

Speech sounds are traditionally divided into consonants and vowels. When only vowels or only consonants are replaced by noise, listeners are more accurate understanding sentences in which consonants are replaced but vowels remain. From such data, vowels have been suggested to be more important for understanding sentences; however, such conclusions are mitigated by the fact that replaced consonant segments were roughly one-third shorter than vowels. We report two experiments that demonstrate listener performance to be better predicted by simple psychoacoustic measures of cochlea-scaled spectral change across time. First, listeners identified sentences in which portions of consonants (C), vowels (V), CV transitions, or VC transitions were replaced by noise. Relative intelligibility was not well accounted for on the basis of Cs, Vs, or their transitions. In a second experiment, distinctions between Cs and Vs were abandoned. Instead, portions of sentences were replaced on the basis of cochlea-scaled spectral entropy (CSE). Sentence segments having relatively high, medium, or low entropy were replaced with noise. Intelligibility decreased linearly as the amount of replaced CSE increased. Duration of signal replaced and proportion of consonants/vowels replaced fail to account for listener data. CSE corresponds closely with the linguistic construct of sonority (or vowel-likeness) that is useful for describing phonological systematicity, especially syllable composition. Results challenge traditional distinctions between consonants and vowels. Speech intelligibility is better predicted by nonlinguistic sensory measures of uncertainty (potential information) than by orthodox physical acoustic measures or linguistic constructs.
Paradoxical glomerular filtration of carbon nanotubes
Authors: Ruggiero Alessandro , Villa Carlos H. , Bander Evan , Rey Diego A. , Bergkvist Magnus , Batt Carl A. , Manova-Todorova Katia , Deen William M. , Scheinberg David A. , McDevitt Michael R.
Published: June 2010

The molecular weight cutoff for glomerular filtration is thought to be 30–50 kDa. Here we report rapid and efficient filtration of molecules 10–20 times that mass and a model for the mechanism of this filtration. We conducted multimodal imaging studies in mice to investigate renal clearance of a single-walled carbon nanotube (SWCNT) construct covalently appended with ligands allowing simultaneous dynamic positron emission tomography, near-infrared fluorescence imaging, and microscopy. These SWCNTs have a length distribution ranging from 100 to 500 nm. The average length was determined to be 200–300 nm, which would yield a functionalized construct with a molecular weight of ∼350–500 kDa. The construct was rapidly (
t
1/2
∼ 6 min) renally cleared intact by glomerular filtration, with partial tubular reabsorption and transient translocation into the proximal tubular cell nuclei. Directional absorption was confirmed in vitro using polarized renal cells. Active secretion via transporters was not involved. Mathematical modeling of the rotational diffusivity showed the tendency of flow to orient SWCNTs of this size to allow clearance via the glomerular pores. Surprisingly, these results raise questions about the rules for renal filtration, given that these large molecules (with aspect ratios ranging from 100:1 to 500:1) were cleared similarly to small molecules. SWCNTs and other novel nanomaterials are being actively investigated for potential biomedical applications, and these observations—that high aspect ratio as well as large molecular size have an impact on glomerular filtration—will allow the design of novel nanoscale-based therapeutics with unusual pharmacologic characteristics.
Abrupt change of Antarctic moisture origin at the end of Termination II
Authors: Masson-Delmotte V. , Stenni B. , Blunier T. , Cattani O. , Chappellaz J. , Cheng H. , Dreyfus G. , Edwards R. L. , Falourd S. , Govin A. , Kawamura K. , Johnsen S. J. , Jouzel J. , Landais A. , Lemieux-Dudon B. , Lourantou A. , Marshall G. , Minster B. , Mudelsee M. , Pol K. , Röthlisberger R. , Selmo E. , Waelbroeck C.
Published: June 2010

The deuterium excess of polar ice cores documents past changes in evaporation conditions and moisture origin. New data obtained from the European Project for Ice Coring in Antarctica Dome C East Antarctic ice core provide new insights on the sequence of events involved in Termination II, the transition between the penultimate glacial and interglacial periods. This termination is marked by a north–south seesaw behavior, with first a slow methane concentration rise associated with a strong Antarctic temperature warming and a slow deuterium excess rise. This first step is followed by an abrupt north Atlantic warming, an abrupt resumption of the East Asian summer monsoon, a sharp methane rise, and a CO2overshoot, which coincide within dating uncertainties with the end of Antarctic optimum. Here, we show that this second phase is marked by a very sharp Dome C centennial deuterium excess rise, revealing abrupt reorganization of atmospheric circulation in the southern Indian Ocean sector.
Adenovirus 12 E4orf6 inhibits ATR activation by promoting TOPBP1 degradation
Authors: Blackford Andrew N. , Patel Rakesh N. , Forrester Natalie A. , Theil Kathrin , Groitl Peter , Stewart Grant S. , Taylor A. Malcolm R. , Morgan Iain M. , Dobner Thomas , Grand Roger J. A. , Turnell Andrew S.
Published: June 2010

Activation of the cellular DNA damage response is detrimental to adenovirus (Ad) infection. Ad has therefore evolved a number of strategies to inhibit ATM- and ATR-dependent signaling pathways during infection. Recent work suggests that the Ad5 E4orf3 protein prevents ATR activation through its ability to mislocalize the MRN complex. Here we provide evidence to indicate that Ad12 has evolved a different strategy from Ad5 to inhibit ATR. We show that Ad12 utilizes a CUL2/RBX1/elongin C-containing ubiquitin ligase to promote the proteasomal degradation of the ATR activator protein topoisomerase-IIβ–binding protein 1 (TOPBP1). Ad12 also uses this complex to degrade p53 during infection, in contrast to Ad5, which requires a CUL5-based ubiquitin ligase. Although Ad12-mediated degradation of p53 is dependent upon both E1B-55K and E4orf6, Ad12-mediated degradation of TOPBP1 is solely dependent on E4orf6. We propose that Ad12 E4orf6 has two principal activities: to recruit the CUL2-based ubiquitin ligase and to act as substrate receptor for TOPBP1. In support of the idea that Ad12 E4orf6 specifically prevents ATR activation during infection by targeting TOPBP1 for degradation, we demonstrate that Ad12 E4orf6 can inhibit the ATR-dependent phosphorylation of CHK1 in response to replication stress. Taken together, these data provide insights into how Ad modulates ATR signaling pathways during infection.
Survival differences and the effect of environmental instability on breeding dispersal in an Adélie penguin meta-population
Authors: Dugger Katie M. , Ainley David G. , Lyver Phil O'B. , Barton Kerry , Ballard Grant
Published: June 2010

High survival and breeding philopatry was previously confirmed for the Adélie penguin (Pygoscelis adeliae) during a period of stable environmental conditions. However, movements of breeding adults as a result of an unplanned natural experiment within a four-colony meta-population provided interesting insights into this species’ population dynamics. We used multistate mark-recapture models to investigate apparent survival and dispersal of breeding birds in the southwestern Ross Sea during 12 breeding seasons (1996–2007). The natural experiment was facilitated by the temporary grounding of two immense icebergs that (i) erected a veritable fence separating colonies and altering migration routes and (ii) added additional stress by trapping extensive sea ice in the region during 5 of 12 y. Colony size varied by orders of magnitude, allowing investigation of apparent survival and dispersal rates in relation to both environmental conditions and colony size within this meta-population. Apparent survival was lowest for the smallest colony (4,000 pairs) and similar for the medium (45,000 pairs) and large colonies (155,000 pairs), despite increased foraging effort expended by breeders at the largest colony. Dispersal of breeding birds was low (<1%), except during years of difficult environmental conditions when movements increased, especially away from the smallest colony (3.5%). Decreased apparent survival at the smallest colony could reflect differences in migration chronology and winter habitat use compared with the other colonies, or it may reflect increased permanent emigration to colonies outside this meta-population. Contrary to current thought, breeding penguins are not always philopatric. Rather, stressful conditions can significantly increase dispersal rates.
Imaging tuberculosis with endogenous β-lactamase reporter enzyme fluorescence in live mice
Authors: Kong Ying , Yao Hequan , Ren Hongjun , Subbian Selvakumar , Cirillo Suat L. G. , Sacchettini James C. , Rao Jianghong , Cirillo Jeffrey D.
Published: June 2010

The slow growth rate and genetic intractability of tubercle bacilli has hindered progress toward understanding tuberculosis, one of the most frequent causes of death worldwide. We overcame this roadblock through development of near-infrared (NIR) fluorogenic substrates for β-lactamase, an enzyme expressed by tubercle bacilli, but not by their eukaryotic hosts, to allow real-time imaging of pulmonary infections and rapid quantification of bacteria in living animals by a strategy called reporter enzyme fluorescence (REF). This strategy has a detection limit of 6 ± 2 × 102colony-forming units (CFU) of bacteria with the NIR substrate CNIR5 in only 24 h of incubation in vitro, and as few as 104CFU in the lungs of live mice. REF can also be used to differentiate infected from uninfected macrophages by using confocal microscopy and fluorescence activated cell sorting.Mycobacterium tuberculosisand the bacillus Calmette–Guérin can be tracked directly in the lungs of living mice without sacrificing the animals. Therapeutic efficacy can also be evaluated through loss of REF signal within 24 h posttreatment by using in vitro whole-bacteria assays directly in living mice. We expect that rapid quantification of bacteria within tissues of a living host and in the laboratory is potentially transformative for tuberculosis virulence studies, evaluation of therapeutics, and efficacy of vaccine candidates. This is a unique use of an endogenous bacterial enzyme probe to detect and image tubercle bacilli that demonstrates REF is likely to be useful for the study of many bacterial infections.
Theory for polymer analysis using nanopore-based single-molecule mass spectrometry
Authors: Reiner Joseph E. , Kasianowicz John J. , Nablo Brian J. , Robertson Joseph W. F.
Published: June 2010

Nanometer-scale pores have demonstrated potential for the electrical detection, quantification, and characterization of molecules for biomedical applications and the chemical analysis of polymers. Despite extensive research in the nanopore sensing field, there is a paucity of theoretical models that incorporate the interactions between chemicals (i.e., solute, solvent, analyte, and nanopore). Here, we develop a model that simultaneously describes both the current blockade depth and residence times caused by individual poly(ethylene glycol) (PEG) molecules in a single α-hemolysin ion channel. Modeling polymer-cation binding leads to a description of two significant effects: a reduction in the mobile cation concentration inside the pore and an increase in the affinity between the polymer and the pore. The model was used to estimate the free energy of formation for K
+
-PEG inside the nanopore (≈-49.7 meV) and the free energy of PEG partitioning into the nanopore (≈0.76 meV per ethylene glycol monomer). The results suggest that rational, physical models for the analysis of analyte-nanopore interactions will develop the full potential of nanopore-based sensing for chemical and biological applications.
Regulation of cell motile behavior by crosstalk between cadherin- and integrin-mediated adhesions
Authors: Borghi Nicolas , Lowndes Molly , Maruthamuthu Venkat , Gardel Margaret L. , Nelson W. James
Published: June 2010

During normal development and in disease, cohesive tissues undergo rearrangements that require integration of signals from cell adhesions to neighboring cells and to the extracellular matrix (ECM). How a range of cell behaviors is coordinated by these different adhesion complexes is unknown. To analyze epithelial cell motile behavior in response to combinations of cell–ECM and cell–cell adhesion cues, we took a reductionist approach at the single-cell scale by using unique, functionalized micropatterned surfaces comprising alternating stripes of ECM (collagenIV) and adjustable amounts of E-cadherin-Fc (EcadFc). On these surfaces, individual cells spatially segregated integrin- and cadherin-based complexes between collagenIV and EcadFc surfaces, respectively. Cell migration required collagenIV and did not occur on surfaces functionalized with only EcadFc. However, E-cadherin adhesion dampened lamellipodia activity on both collagenIV and EcadFc surfaces and biased the direction of cell migration without affecting the migration rate, all in an EcadFc concentration-dependent manner. Traction force microscopy showed that spatial confinement of integrin-based adhesions to collagenIV stripes induced anisotropic cell traction on collagenIV and migration directional bias. Selective depletion of different pools of αE-catenin, an E-cadherin and actin binding protein, identified a membrane-associated pool required for E-cadherin–mediated adhesion and down-regulation of lamellipodia activity and a cytosolic pool that down-regulated the migration rate in an E-cadherin adhesion-independent manner. These results demonstrate that there is crosstalk between E-cadherin– and integrin-based adhesion complexes and that E-cadherin regulates lamellipodia activity and cell migration directionality, but not cell migration rate.