bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating GPP and Respiration Estimates Over Northern Midlatitude Ecosystems Using Solar‐Induced Fluorescence and Atmospheric CO2 Measurements
Authors: Byrne B. , Wunch D. , Jones D. B. A. , Strong K. , Deng F. , Baker I. , Köhler P. , Frankenberg C. , Joiner J. , Arora V. K. , Badawy B. , Harper A. B. , Warneke T. , Petri C. , Kivi R. , Roehl C. M. 
Published: August 2018

AbstractOn regional to global scales, few constraints exist on gross primary productivity (GPP) and ecosystem respiration (Re) fluxes. Yet constraints on these fluxes are critical for evaluating and improving terrestrial biosphere models. In this study, we evaluate the seasonal cycle of GPP, Re, and net ecosystem exchange (NEE) produced by four terrestrial biosphere models and FLUXCOM, a data‐driven model, over northern midlatitude ecosystems. We evaluate the seasonal cycle of GPP and NEE using solar‐induced fluorescence retrieved from the Global Ozone Monitoring Experiment‐2 and column‐averaged dry‐air mole fractions of CO2 (XCO2) from the Total Carbon Column Observing Network, respectively. We then infer Re by combining constraints on GPP with constraints on NEE from two flux inversions. An ensemble of optimized Re seasonal cycles is generated using five GPP estimates and two NEE estimates. The optimized Re curves generally show high consistency with each other, with the largest differences due to the magnitude of GPP. We find optimized Re exhibits a systematically broader summer maximum than modeled Re, with values lower during June–July and higher during the fall than Re. Further analysis suggests that the differences could be due to seasonal variations in the carbon use efficiency (possibly due to an ecosystem‐scale Kok effect) and to seasonal variations in the leaf litter and fine root carbon pool. The results suggest that the inclusion of variable carbon use efficiency for autotrophic respiration and carbon pool dependence for heterotrophic respiration is important for accurately simulating Re.
Faraday Rotation, Total Electron Content, and Their Sensitivity to the Average Parallel Component of the Magnetic Field
Authors: Cushley A. C. , Noël J.‐M. , Kabin K. 
Published: August 2018

AbstractA plane‐polarized electromagnetic wave that propagates through a plasma, (anti)parallel to a magnetic field, experiences a gradual rotation of its plane of polarization called Faraday rotation (FR). The FR angle depends on the integrated product of the electron density and the strength of the parallel magnetic field projection to the radio wave propagation direction. The integral is taken along the radio wave propagation direction over the entire path length. Therefore, accurate measurements or a suitable model for both the electron density and the magnetic field as well as the propagation trajectory are required for the interpretation of FR measurements. Many authors use the average value of the parallel magnetic field for estimation of FR from ionospheric total electron content measurements. Although it is known that the strength of Earth's geomagnetic field varies slowly at ionospheric altitudes, a reference height characteristic value or mean value may not always be appropriate. This work considers alternative methods to establish a characteristic value for the average parallel component of the magnetic field, particularly when independent FR and total electron content measurements are available.
Exploring Controls on Rainfall‐Runoff Events: 1. Time Series‐Based Event Separation and Temporal Dynamics of Event Runoff Response in Germany
Authors: Tarasova L. , Basso S. , Zink M. , Merz R. 
Published: August 2018

AbstractAnalyzing a response of catchments to rainfall inputs allows for deeper insights on the mechanisms of runoff generation at catchment scale. In this study an automated time series‐based event separation procedure consisting of available base flow separation, runoff event identification, and rainfall attribution methods and of a novel iterative procedure for the adjustment of thresholds used to identify single‐peak components of multiple‐peak events is proposed. Event runoff coefficient, time scale, rise time, and peak discharge of more than 220,000 identified rainfall‐runoff events are then used to analyze dynamics of event runoff response in 185 catchments at multiple temporal scales. In mountainous catchments with poor storage event runoff response is strongly controlled by the characteristics of rainfall and is generated by event‐fed saturation or infiltration excess. A distinct switch between saturated and unsaturated states occurs in these catchments. A weak relation between rainfall and runoff event properties is instead observed in lowland and hilly catchments with substantial storage, where a gradual transformation between functioning states occurs and the response is driven by preevent saturation. The seasonality of their event characteristics is governed by the contribution of snowmelt and the seasonality of the aridity index rather than of rainfall properties. Long‐term changes of total precipitation amount alone do not explain season‐specific long‐term changes of event characteristics that are rather consistent with changes of seasonal indicators of the wetness state. The effects of land use changes are detectable only in a few cases and display themselves mostly in the characteristic response time of catchments.
A Diagnostic Framework for Understanding Climatology of Tails of Hourly Precipitation Extremes in the United States
Authors: Papalexiou Simon Michael , AghaKouchak Amir , Foufoula‐Georgiou Efi 
Published: August 2018

AbstractHourly precipitation extremes are crucial in hydrological design. Their frequency and magnitude is encapsulated in the probability distribution tail. Traditional extreme‐analysis methods rely on theorems, like the Pickands‐Balkema‐de Haan, indicating specific type of tails assuming asymptotic convergence—a questionable assumption for real‐world samples. Moreover, popular stochastic models for hourly precipitation presume light‐tailed distributions to facilitate their mathematical formulation. In practice, limited information on hourly precipitation extremes makes identifying and quantifying their tail highly uncertain, especially on a station‐by‐station basis. Yet no comprehensive regional analysis of tails has been undertaken to quantify a climatology of tails for diagnostic and prognostic purposes. Here we undertake such an analysis for the conterminous United States. We introduce a novel Bayesian‐adjustment approach to assess the best model between power‐type and stretched‐exponential tails showing that the latter performs better. We present climatology of the tail and quantify its heaviness in over 4,000 hourly precipitation records across the United States and present three main conclusions. First, we show that hourly precipitation tails are heavier than those commonly used with important implications including underestimation of extremes. Second, we provide spatial maps of the tail behavior which reveal some strikingly coherent spatial patterns that can be used for inference in the absence of local observations. Third, we find a nonlinear increase in the tail heaviness with elevation and we formulate parametric functions to describe this law. These results can improve the accuracy of frequency analysis, probabilistic prediction, rainfall‐runoff modeling, and downscaling of historical observations and climate model projections.
U.S. Urban Water Prices: Cheaper When Drier
Authors: Luby Ian H. , Polasky Stephen , Swackhamer Deborah L. 
Published: August 2018

AbstractPublic water utilities are called upon to address multiple and often partially conflicting objectives, allocating potentially scarce water in an efficient and equitable manner while covering the costs of water supply. Economists typically advocate using prices to balance supply and demand of a scarce resource. But high prices necessary to balance supply and demand for scarce water may unduly burden poor households. We analyze the pricing policy of public water utilities in the major city of the 35 largest metropolitan areas in the United States. We would expect water prices to be higher in water‐stressed regions. However, we find the opposite pattern in the data: cities facing greater water scarcity tend to have lower water prices. Sacramento, Las Vegas, and Phoenix, have the lowest water prices. To address equity and ensure that all households have access to water, we would expect low prices on essential water use with higher prices for additional water beyond essential use. However, we find that the majority of cities have higher per unit water prices (average price) for low use than for high use. Such pricing may leave major urban areas in the United States ill‐prepared to meet future water shortages in an equitable manner.
In Situ and GRACE‐Based Groundwater Observations: Similarities, Discrepancies, and Evaluation in the High Plains Aquifer in Kansas
Authors: Brookfield A. E. , Hill M. C. , Rodell M. , Loomis B. D. , Stotler R. L. , Porter M. E. , Bohling G. C. 
Published: August 2018

AbstractRelating Gravity Recovery and Climate Experiment (GRACE)‐derived terrestrial water storage anomaly (aTWS) variations to in situ groundwater data is important to understanding GRACE data utility. Here GRACE‐derived annual changes in aTWS (ΔTWS) from National Aeronautics and Space Administration's Jet Propulsion Laboratory and Goddard Space Flight Center are compared to annual changes in saturated groundwater volumes (ΔGW) in the High Plains aquifer (HPA) and overlying alluvial aquifers in Kansas. Regression analysis suggests that trends in ΔTWS are strongly related to trends in ΔGWalluvial and weakly related to trends in ΔGWHPA, although the magnitude of ΔTWS is much larger than ΔGWalluvial and is similar to ΔGWHPA. Unlike alluvial aquifers, a thick vadose zone overlies the HPA. Estimates of changes in vadose zone water content (ΔVZ) using GRACE products are similar in magnitude to annual variations in North American Land Data Assimilation soil moisture data, suggesting an unexpected dominance of ΔVZ in ΔTWS despite significant groundwater depletion. Results demonstrate that water storage changes in shallow alluvial aquifers, the root zone, the deep vadose zone, and the HPA itself are all significant in the HPA region of Kansas. Consequently, GRACE observations cannot, alone, be taken to reflect variations in saturated zone groundwater storage in the HPA, or other large, heavily used aquifers subject to substantial groundwater depletion, when deep unsaturated zones exist. GRACE can best provide guidance on regional aquifer storage changes where water storage changes in the vadose zone and perched or adjacent aquifers are well constrained.
Junction-based lamellipodia drive endothelial cell rearrangements in vivo via a VE-cadherin-F-actin based oscillatory cell-cell interaction
Authors: Paatero Ilkka , Sauteur Loïc , Lee Minkyoung , Lagendijk Anne K. , Heutschi Daniel , Wiesner Cora , Guzmán Camilo , Bieli Dimitri , Hogan Benjamin M. , Affolter Markus , Belting Heinz-Georg 
Published: August 2018

AbstractAngiogenesis and vascular remodeling are driven by extensive endothelial cell movements. Here, we present in vivo evidence that endothelial cell movements are associated with oscillating lamellipodia-like structures, which emerge from cell junctions in the direction of cell movements. High-resolution time-lapse imaging of these junction-based lamellipodia (JBL) shows dynamic and distinct deployment of junctional proteins, such as F-actin, VE-cadherin and ZO1, during JBL oscillations. Upon initiation, F-actin and VE-cadherin are broadly distributed within JBL, whereas ZO1 remains at cell junctions. Subsequently, a new junction is formed at the front of the JBL, which then merges with the proximal junction. Rac1 inhibition interferes with JBL oscillations and disrupts cell elongation—similar to a truncation in ve-cadherin preventing VE-cad/F-actin interaction. Taken together, our observations suggest an oscillating ratchet-like mechanism, which is used by endothelial cells to move over each other and thus provides the physical means for cell rearrangements.
Ethanol facilitates socially evoked memory recall in mice by recruiting pain-sensitive anterior cingulate cortical neurons
Authors: Sakaguchi Tetsuya , Iwasaki Satoshi , Okada Mami , Okamoto Kazuki , Ikegaya Yuji 
Published: August 2018

AbstractAlcohol is a traditional social-bonding reinforcer; however, the neural mechanism underlying ethanol-driven social behaviors remains elusive. Here, we report that ethanol facilitates observational fear response. Observer mice exhibited stronger defensive immobility while observing cagemates that received repetitive foot shocks if the observer mice had experienced a brief priming foot shock. This enhancement was associated with an observation-induced recruitment of subsets of anterior cingulate cortex (ACC) neurons in the observer mouse that were responsive to its own pain. The vicariously activated ACC neurons projected their axons preferentially to the basolateral amygdala. Ethanol shifted the ACC neuronal balance toward inhibition, facilitated the preferential ACC neuronal recruitment during observation, and enhanced observational fear response, independent of an oxytocin signaling pathway. Furthermore, ethanol enhanced socially evoked fear response in autism model mice.
Long-lived polarization memory in the electronic states of lead-halide perovskites from local structural dynamics
Authors: Rivett Jasmine P. H. , Tan Liang Z. , Price Michael B. , Bourelle Sean A. , Davis Nathaniel J. L. K. , Xiao James , Zou Yatao , Middleton Rox , Sun Baoquan , Rappe Andrew M. , Credgington Dan , Deschler Felix 
Published: August 2018

AbstractAnharmonic crystal lattice dynamics have been observed in lead halide perovskites on picosecond timescales. Here, we report that the soft nature of the perovskite crystal lattice gives rise to dynamic fluctuations in the electronic properties of excited states. We use linear polarization selective transient absorption spectroscopy to study the charge carrier relaxation dynamics in lead-halide perovskite films and nanocrystals. We find that photo-excited charge carriers maintain an initial polarization anisotropy for several picoseconds, independent of crystallite size and composition, and well beyond the reported timescales of carrier scattering. First-principles calculations find intrinsic anisotropies in the transition dipole moment, which depend on the orientation of light polarization and the polar distortion of the local crystal lattice. Lattice dynamics are imprinted in the optical transitions and anisotropies arise on the time-scales of structural motion. The strong coupling between electronic states and structural dynamics requires a unique interpretation of recombination and transport mechanisms.
A myosin II nanomachine mimicking the striated muscle
Authors: Pertici Irene , Bongini Lorenzo , Melli Luca , Bianchi Giulio , Salvi Luca , Falorsi Giulia , Squarci Caterina , Bozó Tamás , Cojoc Dan , Kellermayer Miklós S. Z. , Lombardi Vincenzo , Bianco Pasquale 
Published: August 2018

AbstractThe contraction of striated muscle (skeletal and cardiac muscle) is generated by ATP-dependent interactions between the molecular motor myosin II and the actin filament. The myosin motors are mechanically coupled along the thick filament in a geometry not achievable by single-molecule experiments. Here we show that a synthetic one-dimensional nanomachine, comprising fewer than ten myosin II dimers purified from rabbit psoas, performs isometric and isotonic contractions at 2 mM ATP, delivering a maximum power of 5 aW. The results are explained with a kinetic model fitted to the performance of mammalian skeletal muscle, showing that the condition for the motor coordination that maximises the efficiency in striated muscle is a minimum of 32 myosin heads sharing a common mechanical ground. The nanomachine offers a powerful tool for investigating muscle contractile-protein physiology, pathology and pharmacology without the potentially disturbing effects of the cytoskeletal—and regulatory—protein environment.
Chemo-immunotherapy of colon cancer with focused ultrasound and Salmonella-laden temperature sensitive liposomes (thermobots)
Authors: Ektate Kalyani , Munteanu Maria Cristina , Ashar Harshini , Malayer Jerry , Ranjan Ashish 
Published: August 2018

AbstractUsing attenuated Salmonella that efficiently homes in solid tumors, here we developed thermobots that actively transported membrane attached low-temperature sensitive liposome (LTSL) inside colon cancer cells for triggered doxorubicin release and simultaneous polarized macrophages to M1 phenotype with high intensity focused ultrasound (HIFU) heating (40–42 °C). Biocompatibility studies showed that the synthesized thermobots were highly efficient in LTSL loading without impacting its viability. Thermobots demonstrated efficient intracellular trafficking, high nuclear localization of doxorubicin, and induced pro-inflammatory cytokine expression in colon cancer cells in vitro. Combination of thermobots and HIFU heating (~30 min) in murine colon tumors significantly enhanced polarization of macrophages to M1 phenotype and therapeutic efficacy in vivo compared to control. Our data suggest that the thermobots and focused ultrasound treatments have the potential to improve colon cancer therapy.
Chemometric Analysis of Cannabinoids: Chemotaxonomy and Domestication Syndrome
Authors: Mudge E. M. , Murch S. J. , Brown P. N. 
Published: August 2018

AbstractCannabis is an interesting domesticated crop with a long history of cultivation and use. Strains have been selected through informal breeding programs with undisclosed parentage and criteria. The term “strain” refers to minor morphological differences and grower branding rather than distinct cultivated varieties. We hypothesized that strains sold by different licensed producers are chemotaxonomically indistinguishable and that the commercial practice of identifying strains by the ratio of total THC and CBD is insufficient to account for the reported human health outcomes. We used targeted metabolomics to analyze 11 known cannabinoids and an untargeted metabolomics approach to identify 21 unknown cannabinoids. Five clusters of chemotaxonomically indistinguishable strains were identified from the 33 commercial products. Only 3 of the clusters produce CBDA in significant quantities while the other 2 clusters redirect metabolic resources toward the THCA production pathways. Six unknown metabolites were unique to CBD-rich strains and/or correlated to CBDA and 3 unknowns were found only in THC-rich strains. Together, these data indicate the domestication of the cannabis germplasm has resulted in a loss of the CBDA pathway in some strains and reallocation of resources between CBDA and THCA pathways in others. The impact of domestication is a lack of chemical diversity and loss of biodiversity in modern cannabis strains.
A fundamental catalytic difference between zinc and manganese dependent enzymes revealed in a bacterial isatin hydrolase
Authors: Sommer Theis , Bjerregaard-Andersen Kaare , Uribe Lalita , Etzerodt Michael , Diezemann Gregor , Gauss Jürgen , Cascella Michele , Morth J. Preben 
Published: August 2018

AbstractThe catalytic mechanism of the cyclic amidohydrolase isatin hydrolase depends on a catalytically active manganese in the substrate-binding pocket. The Mn2+ ion is bound by a motif also present in other metal dependent hydrolases like the bacterial kynurenine formamidase. The crystal structures of the isatin hydrolases from Labrenzia aggregata and Ralstonia solanacearum combined with activity assays allow for the identification of key determinants specific for the reaction mechanism. Active site residues central to the hydrolytic mechanism include a novel catalytic triad Asp-His-His supported by structural comparison and hybrid quantum mechanics/classical mechanics simulations. A hydrolytic mechanism for a Mn2+ dependent amidohydrolases that disfavour Zn2+ as the primary catalytically active site metal proposed here is supported by these likely cases of convergent evolution. The work illustrates a fundamental difference in the substrate-binding mode between Mn2+ dependent isatin hydrolase like enzymes in comparison with the vast number of Zn2+ dependent enzymes.
Short-term high glucose culture potentiates pancreatic beta cell function
Authors: Rebelato Eduardo , Santos Laila R. , Carpinelli Angelo R. , Rorsman Patrik , Abdulkader Fernando 
Published: August 2018

AbstractThe exposure of pancreatic islets to high glucose is believed to be one of the causal factors of the progressive lowering of insulin secretion in the development of type 2 diabetes. The progression of beta cell failure to type 2 diabetes is preceded by an early positive increase in the insulin secretory response to glucose, which is only later followed by a loss in the secretion capacity of pancreatic islets. Here we have investigated the electrophysiological mechanisms underlying the early glucose-mediated gain of function. Rodent pancreatic islets or dispersed islet cells were cultured in medium containing either 5.6 (control) or 16.7 (high-glucose) mM glucose for 24 h after isolation. Glucose-stimulated insulin secretion was enhanced in a concentration-dependent manner in high glucose-cultured islets. This was associated with a positive effect on beta cell exocytotic capacity, a lower basal KATP conductance and a higher glucose sensitivity to fire action potentials. Despite no changes in voltage-gated Ca2+ currents were observed in voltage-clamp experiments, the [Ca2+]I responses to glucose were drastically increased in high glucose-cultured cells. Of note, voltage-dependent K+ currents were decreased and their activation was shifted to more depolarized potentials by high-glucose culture. This decrease in voltage-dependent K+ channel (Kv) current may be responsible for the elevated [Ca2+]I response to metabolism-dependent and independent stimuli, associated with more depolarized membrane potentials with lower amplitude oscillations in high glucose-cultured beta cells. Overall these results show that beta cells improve their response to acute challenges after short-term culture with high glucose by a mechanism that involves modulation not only of metabolism but also of ion fluxes and exocytosis, in which Kv activity appears as an important regulator.