bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent changes in productivity and climate of Lake Ontario detected by isotopic analysis of sediments
Authors: Schelske Claire L. , Hodeli David A. 
Published: April 2010

Cores from Lake Ontario provide a record of lake responses to increased phosphorus loading that began after early forest clearance in the mid‐1800s. We measured 13C/12C ratios of organic and inorganic C (calcite) in the sediments to infer recent trends in primary production. The δ13C of organic C increased in response to historic increases in P enrichment until the mid‐1970s and then decreased in response to reduced P loading. The δ13C of calcite increased after 1940 but did not decrease in response to reduced P loading. We conclude that the results differ because δ13C of organic C is determined by primary production early in the seasonal cycle when flux of organic C to the sediments is greatest, whereas δ13C of calcite depends on the isotopic composition of dissolved inorganic C during late summer when calcite is precipitated.Calcite accumulation and its δ13C ratio oscillated after 1940 with peaks estimated at 1948, 1966, 1977, and 1983. These peaks correspond to minima in δ18O values, indicating calcite precipitation at higher temperature, and to years of early thermal stratification. We hypothesize that calcite accumulation and its stable isotopic ratios are controlled by interannual variability in onset of thermal stratification of the lake. Our results thus suggest a direct link from climate (i.e. thermal stratification) to interannual variation in lake productivity and to carbonate precipitation and its δ13C signature.
Clay turbidity: Regulation of phytoplankton production in a large, nutrient‐rich tropical lake
Authors: Lind Owen T. , Doyle Robert , Vodopich Darrell S. , Trotter Bruce G. , Limon J. Gualberto , Dcivalos‐Lind Laura 
Published: April 2010

Data from five sampling stations for 23 dates in 1 yr show that annual phytoplankton production in Lake Chapala is low (80 g C m−2) and governed by high inorganic turbidity. In the most turbid region of the lake, Secchi transparency averaged 0.2 m and the vertical light (PAR) attenuation coefficient (η″) averaged 9.7 m−1; in the least turbid region, Secchi transparency averaged 0.7 m (η″ averaged 2.3 m−1).Phytoplankton at the shallowest and most turbid station were most productive per unit volume, while the least turbid station, with a deep circulating water column, had the lowest volume‐based production. There was a considerable rainy vs. dry season difference in water transparency and in production. The lake became less turbid during the rainy season due to increased depth and lessened sediment resuspension. The annual lakewide production C.V. was 34% with the greatest day‐to‐day variation during the rainy season.Phytoplankton Chl a averaged 5.4 mg m−3 of the mixed water column for all regions. Chl a at the shallowest and most turbid station averaged almost twice that of the other stations. Chl a increased through the rainy season (as transparency and inorganic N content increased). Variation in inorganic N accounted for the greatest variation in Chl a at each region.
Development of a sequential extraction method for different forms of phosphorus in marine sediments
Authors: Ruttenberg Kathleen C. 
Published: April 2010

A sequential extraction method (SEDEX) has been developed to separately quantify five sedimentary P reservoirs: loosely sorbed P; ferric iron‐bound P; authigenic carbonate fluorapatite + biogenic apatite + CaCO3‐associated P; detrital apatite P; and organic P. The SEDEX method successfully separates two of the main categories of authigenic phosphate phases called upon most often as sedimentary sinks for diagenetically mobilized P: ferric oxyhydroxide‐associated P and authigenic carbonate fluorapatite (CFAP). It offers a means for separating authigenic CFAP from detrital apatite of igneous or metamorphic origin. The importance of this distinction is that CFAP represents an oceanic sink for reactive P, whereas detrital apatite does not. In addition, a means for reversing secondary adsorption of P onto residual solid surfaces during extraction has been developed.Extensive standardization of the SEDEX method for application to marine sediments has been performed with analogs for naturally occurring phosphatic phases.
Contrasting effects of Daphnia on ratios of nitrogen to phosphorus in a eutrophic, hard‐water lake
Authors: Sarnelle Orlando 
Published: April 2010

Daphnia manipulation in large enclosures, and whole‐lake observations before and after a fishkill, showed that intense Daphnia grazing produces large elevations in particulate N : P ratios (PN : PP) during clear‐water periods in a eutrophic lake. The direction of this effect was consistent with expected taxonomic variation among zooplankton in the N : P of excretion.N and P sedimentation (mg m−2 d−1) was reduced during Daphnia‐induced, clear‐water periods, despite increases in particle sinking velocities. In addition, there was an unexpected difference between seston N : P and the N : P of settled particles during clear water, resulting in a differential increase in average sinking velocity calculated for PP relative to PN.Daphnia effects on N : P later in the season appeared to be opposite to those during clear water. My data suggest that Daphnia grazing can reduce carbonate precipitation (whitings) by controlling algal biomass. Whitings were accompanied by large increases in sedimentary loss rates for total P (TP) and elevated TN : TP in the euphotic zone. Thus, Daphnia grazing may maintain relatively low TN : TP during summer in eutrophic, hard‐water lakes.
Early diagenesis in a marine sapropel, Mangrove Lake, Bermuda
Authors: Boudreau Bernard P. , Canfeld Donald E. , Mucci Alfonso 
Published: April 2010

The pore waters of a marine sapropel in Mangrove Lake (Bermuda) have been analyzed for a suite of diagenetically sensitive species, i.e. pH, SO42−, ∑H2S, Ca2+, ∑CO2, ∑NH4, ∑P04i Fe2+, and Mn2+. We have also measured a 210Pb depth profile (suggesting a burial velocity of 0.94 cm yr−1) and experimentally determined the rate constant for sulfate reduction (0.062 yr−1).Waves and turbulence have mixed sediment and pore waters to a depth of 15 cm. However, both stoichiometric and transport‐reaction models argue that molecular diffusion dominates solute transport beneath this mixed zone and that the pore waters are open to diffusion despite rapid burial. Diagenetic modeling shows further that diffusion accounts for 95% of the SO42−, ∑H2S, and ∑CO2 fluxes below the mixed layer. Comparison of model results with sulfur burial fluxes indicates that at least 94% of the generated ∑H2S diffuses out of the sediments. The pore‐water ∑CO2 is also within 5% of that predicted by our models. The : N ratio of the decaying organic matter is calculated to be between 3.86 and 6.87, which is less than half that obtained by analysis of the solids.The carbonate chemistry of the pore waters suggests that they are nearly saturated with respect to aragonite in the mixed zone, even though this mineral has not been identified in the solids. Precipitation in the mixed zone is confirmed by comparing the observed dissolved Ca profile with that expected for conservative behavior.
Efficient air traffic conflict resolution by minimizing the number of affected aircraft
Authors: Idan M. , Iosilevskii G. , Ben‐Yishay L. 
Published: April 2010

AbstractThe paper addresses local conflict resolution in dense air traffic scenarios. Currently, air traffic can reach a few thousands of aircraft airborne simultaneously over Europe or U.S., with predictions that it will grow significantly during the next two decades. All this traffic is expected to be organized well in advance and updated before take‐off, providing each aircraft a conflict‐free flight plan. Deviations from this plan, caused by the difference between the actual and predicted weather, equipment malfunctions, operational or airport delays, etc., may create in‐flight conflicts that will have to be resolved in a matter of minutes. Since real‐time re‐organization of the entire traffic is impractical due to high computational complexity, local re‐planning, affecting only the aircraft involved in the conflicts, is in order. In this paper we suggest a rapid local re‐planning algorithm. Its efficiency is attained by re‐computing new trajectories only for a minimal number of aircraft that resolves the conflicts. Finding optimal trajectories only for those aircraft not only reduces the computational effort, but also reduces average pilot workload. Copyright © 2010 John Wiley & Sons, Ltd.
How Noniridescent Colors Are Generated by Quasi‐ordered Structures of Bird Feathers
Authors: Noh Heeso , Liew Seng Fatt , Saranathan Vinodkumar , Mochrie Simon G. J. , Prum Richard O. , Dufresne Eric R. , Cao Hui 
Published: April 2010

AbstractWe investigate the mechanism of structural coloration by quasi‐ordered nanostructures in bird feather barbs. Small‐angle X‐ray scattering (SAXS) data reveal the structures are isotropic and have short‐range order on length scales comparable to optical wavelengths. We perform angle‐resolved reflection and scattering spectrometry to fully characterize the colors under directional and omni‐directional illumination of white light. Under directional lighting, the colors change with the angle between the directions of illumination and observation. The angular dispersion of the primary peaks in the scattering/reflection spectra can be well explained by constructive interference of light that is scattered only once in the quasi‐ordered structures. Using the Fourier power spectra of structure from the SAXS data we calculate optical scattering spectra and explain why the light scattering peak is the highest in the backscattering direction. Under omni‐directional lighting, colors from the quasi‐ordered structures are invariant with the viewing angle. The non‐iridescent coloration results from the isotropic nature of structures instead of strong backscattering.
Evidence for genes on chromosome 2 contributing to alcohol dependence with conduct disorder and suicide attempts
Authors: Dick Danielle M. , Meyers Jacquelyn , Aliev Fazil , Nurnberger John , Kramer John , Kuperman Sam , Porjesz Bernice , Tischfield Jay , Edenberg Howard J. , Foroud Tatiana , Schuckit Marc , Goate Alison , Hesselbrock Victor , Bierut Laura 
Published: April 2010

AbstractTwin studies provide strong evidence that there is a shared genetic liability that predisposes to a number of different psychiatric outcomes related to behavioral disinhibition. Further, alcohol dependence comorbid with other disinhibitory disorders is particularly heritable. Chromosome 2p14‐2q14.3 has been linked to multiple psychiatric conditions related to behavioral undercontrol. In the Collaborative Study on the Genetics of Alcoholism (COGA), we previously reported linkage to this region with alcohol dependence (AD), suicide attempts (SUI), and conduct disorder (CD). In this study, we follow‐up on these previous reports of linkage by combining the phenotypes in analyses that jointly consider the presence of multiple conditions. Linkage analyses of the combined phenotype of AD with CD or SUI results in a maximum LOD score of 5.4 in this region. In addition to this primary linkage peak, independent samples have reported linkage to other alcohol‐related phenotypes across chromosome 2. Accordingly, we followed‐up these linkage signals by testing for association with SNPs across chromosome 2 in a case–control sample, in which a subset of the cases consisted of alcohol‐dependent probands from the linkage sample. We find evidence of association with the combined AD with CD or SUI phenotype, with 23 genes surviving permutation testing. The number of associated genes across the chromosome may explain the persistent linkage findings reported on chromosome 2 across a number of independent studies of alcohol and disinhibitory phenotypes. Further, none of the genes were located directly under the primary COGA linkage peak, which has implications for association tests following‐up linkage peaks. © 2010 Wiley‐Liss, Inc.
Goldnanopartikel in Biologie und Medizin
Authors: Giljohann David A. , Seferos Dwight S. , Daniel Weston L. , Massich Matthew D. , Patel Pinal C. , Mirkin Chad A. 
Published: April 2010

AbstractGoldkolloide werden in Chemie, Biologie, Technik und Medizin häufig eingesetzt. Heute kann man diese Materialien reproduzierbar herstellen, mit einer scheinbar unbegrenzten Zahl an funktionellen Gruppen chemisch modifizieren und – in bestimmten Fällen – bis hinab zur Ebene einzelner Atome charakterisieren. Dieser Aufsatz behandelt neuere Entwicklungen hinsichtlich Synthese und Biokonjugation von Goldnanokonjugaten sowie deren Verwendung in Zellen. Es gibt heute viele Beispiele für hochempfindliche und selektive Assays auf der Basis von Goldkonjugaten. In den letzten Jahren war der Fokus auf den Einsatz solcher Materialien in der Therapie gerichtet. Strukturen, die als genregulierende Agentien, Wirkstofftransporter, Bildgebungsagentien und lichtempfindliche Therapeutika fungieren, wurden entwickelt und in Verbindung mit Zellen und vielen schwächenden Krankheiten erforscht. Diese Strukturen wurden nicht einfach als Alternativen zu molekularen Systemen gewählt, sondern weil ihre neuen physikalischen und chemischen Eigenschaften ihnen in zellulären und medizinischen Anwendungen erhebliche Vorteile verschaffen.
Gold Nanoparticles for Biology and Medicine
Authors: Giljohann David A. , Seferos Dwight S. , Daniel Weston L. , Massich Matthew D. , Patel Pinal C. , Mirkin Chad A. 
Published: April 2010

AbstractGold colloids have fascinated scientists for over a century and are now heavily utilized in chemistry, biology, engineering, and medicine. Today these materials can be synthesized reproducibly, modified with seemingly limitless chemical functional groups, and, in certain cases, characterized with atomic‐level precision. This Review highlights recent advances in the synthesis, bioconjugation, and cellular uses of gold nanoconjugates. There are now many examples of highly sensitive and selective assays based upon gold nanoconjugates. In recent years, focus has turned to therapeutic possibilities for such materials. Structures which behave as gene‐regulating agents, drug carriers, imaging agents, and photoresponsive therapeutics have been developed and studied in the context of cells and many debilitating diseases. These structures are not simply chosen as alternatives to molecule‐based systems, but rather for their new physical and chemical properties, which confer substantive advantages in cellular and medical applications.
Preliminary analysis on dynamic route choice behavior: Using probe‐vehicle data
Authors: Morikawa Taka , Miwa Tomio 
Published: April 2010

AbstractDynamic traffic assignment models have been attracting increasing attention with the progress of traffic management policies based on information technology. These dynamic estimation tools, however, just apply static route choice models either at only origin node or at every arrival node. This paper aims at providing some knowledge on drivers' dynamic route choice behavior using probe‐vehicle data. The results of analyses show that route choice behavior relates to the distance from driver's position to the destination and that dynamic route choice behavior is modeled better by considering decision process during the trip.
Drivers' route choice and learning mechanism under bounded information environment
Authors: Do Myungsik , Ryu Sikyun , Lee Seungjae 
Published: April 2010

AbstractIn this paper, we propose the theory of Rational Beliefs as the model of expectations that extends the theory of rational expectations to the postulated environments. Under the rational beliefs paradigm, drivers do not have structural knowledge of traffic conditions and they choose their routes based only on personal experiences and decision‐making rules. We found that if drivers have different decision‐making rules and experiences, then they form different beliefs of traffic conditions (e.g. average travel time) even though they have the same public information and use the same routes. Under the rational beliefs model, drivers are not motivated to renew their beliefs because the beliefs are compatible with their experiences. Therefore, the heterogeneity of beliefs does not disappear even though they have long‐term learning. In order to investigate how drivers form their beliefs of traffic conditions under bounded information environments, numerical experiment is carried out.
Equilibrium analysis of the scheduling of tours in congested networks
Authors: Heydecker Benjamin , Polak John 
Published: April 2010

AbstractIn this paper, we develop a model of travel in tours that joins several locations by travel through a congested network. We develop a microscopic analysis in continuous time of individual benefits obtained by spending time at each of the locations and costs incurred through travel between them. This is combined with a continuous time macroscopic equilibrium model of travel during congested peak periods to show how individuals' travel choices are influenced by the congestion that result from corresponding choices made by others. We show how different travellers can achieve identical net utilities by making different combinations of choices within the equilibrium. The resulting model can be used to investigate the effect on travel behaviour and individual utility of various transport interventions, and we illustrate this by considering the effect of a peak‐period charge that eliminates congestion.
The optimal dispatching of taxis under congestion: A rolling horizon approach
Authors: Wong K. I. , Bell Michael G. H. 
Published: April 2010

AbstractTaxis make an important contribution to transport in many parts of the world, offering demand‐responsive, door‐to‐door transport. In larger cities, taxis may be hailed on‐street or taken from taxi ranks. Elsewhere, taxis are usually ordered by phone. The objective of a taxi dispatcher is to maximize the efficiency of fleet utilization. While the spatial and temporal distribution of taxi requests has in general a high degree of predictability, real time traffic congestion information can be collected and disseminated to taxis by communication technologies. The efficiency of taxi dispatching may be significantly improved through the anticipation of future requests and traffic conditions. A rolling horizon approach to the optimisation of taxi dispatching is formulated, which takes the stochastic and dynamic nature of the problem into account. Numerical experiments are presented to illustrate the performances of the heuristics, taking the time dependency of travel times and passenger arrivals into account.
Liposomes destabilize tRNA during heat stress
Authors: Suga Keishi , Umakoshi Hiroshi , Tomita Hibiki , Tanabe Tomoyuki , Shimanouchi Toshinori , Kuboi Ryoichi 
Published: April 2010

AbstractBiomembranes play an important role in cellular response to heat stress. In this study, we focus on the interaction between liposomes and tRNA. Upon heat treatment we determined circular dichroism spectra of tRNA in presence of liposomes prepared from POPC (1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine) and cholesterol (Ch). To compare thermal stability, midpoint temperature (Tm) of tRNA was calculated from normalized θ208. Addition of POPC/Ch liposomes decreased the Tm value of tRNA from 48°C to 38°C. We conclude that POPC/Ch liposomes interact with tRNA and destabilize its conformation under heat stress.
A theoretical method to improve and optimize the design of bioartificial livers
Authors: Davidson Adam J. , Ellis Marianne J. , Chaudhuri Julian B. 
Published: April 2010

AbstractBioartificial livers (BALs) are a potentially effective countermeasure against liver failure, particularly in cases of acute or fulminant liver failure. It is hoped these devices can sustain a patient's liver function until recovery or transplant. However, no large‐scale clinical trial has yet proven that BALs are particularly effective and evidently design issues remain to be addressed. One aspect of BAL design that must be considered is the mass transfer of adequate oxygen to the hepatocytes within the device. We present here a mathematical modeling approach to oxygen mass transport in a BAL. A mathematical model based upon Krogh cylinders is outlined to describe a diffusion‐limited hollow fiber bioreactor. In addition, operating constraints are defined on the system—cells should not experience hypoxia and the cell population should be of adequate size. By combining modeling results with these operating constraints and presenting the results graphically, “operating region” charts can be constructed for the hollow fiber BAL (HF‐BAL). The effects of varying various operating parameters on the BAL are then established. It is found that smaller radii and short, thin walled fibers are generally advantageous while cell populations in excess of 10 billion could be supported in the BAL with a plasma flow rate of 200 mL/min. For fibers of intermediate length and lumen radius, the minimum number of fibers required to produce a viable design ranges approximately from 7,000–10,000. In theory, this may be enough to support patients with failing livers. Biotechnol. Bioeng. 2010;106: 980–988. © 2010 Wiley Periodicals, Inc.
Konflikte und Konfliktlösung in den Staaten sozialer Insekten. Zwischen Superorganismus und Polizeistaat
Authors: Heinze Jürgen 
Published: April 2010

AbstractDie Staaten sozialer Insekten galten lange als harmonische, konfliktfreie Superorganismen, in denen alle Individuen selbstlos zusammenarbeiten, um den Fortpflanzungserfolg des Staats als Ganzes zu maximieren. Diese Vorstellung hat sich in den vergangenen Jahren sehr stark gewandelt. Tatsächlich können Individuen egoistisch ihre Einzelinteressen verfolgen, was dem gesamten Staat schaden kann. Die Integrität von Insektenstaaten wird dadurch gewährleistet, dass egoistische Reproduktion durch Arbeiterinnen weitgehend unterbunden wird, sei es durch direkte Attacken von Seiten der Königin, die Etablierung von Dominanzhierarchien oder gegenseitige Überwachung und Bestrafung. Eine genaue Analyse der Vorgänge im Insektenstaat hilft zu verstehen, wie Kooperation zwischen an sich egoistischen Einzelindividuen aufrecht erhalten werden kann.
Redox‐Regulation. Ein Netzwerk zur flexiblen Adaptation von Stoffwechsel und Entwicklung bei Pflanzen
Authors: Scheibe Renate 
Published: April 2010

AbstractPflanzen benötigen Faktoren aus der Umwelt für ihr photoautotrophes Wachstum, jedoch sind sie durch ihre sessile Lebensweise Abweichungen vom Optimum ausgeliefert. Anpassung an sehr unterschiedliche Bedingungen ist ihnen aber möglich, da sie durch entsprechende Veränderung ihrer Reaktionsnorm eine hohe phänotypische Plastizität aufweisen. Alle Informationen werden integriert und über ein hochflexibles Netzwerk weitergeleitet und realisiert. Die Reaktionen der Pflanzen spielen sich auf allen Regulationsebenen ab und umfassen sehr schnelle biophysikalische und biochemische Prozesse (im Sekunden‐ und Minutenbereich) sowie mittel‐ und langfristige Reaktionen, die sich nach Stunden (Genexpression) oder erst nach Tagen (Wachstum) auswirken. In allen Bereichen spielen Redox‐Prozesse eine bedeutende Rolle. Eine Abweichung von der Redox‐Homöostase dient einerseits als Signal, andererseits müssen zu große Ungleichgewichte abgepuffert werden, um Schaden zu vermeiden.
Pinguine – Überlebenskünstler in der Antarktis. Klimawandel
Authors: Kostrzewa Achim 
Published: April 2010

AbstractDie lokalen und regionalen ökologischen Bedingungen werden die Zukunft der einzelnen Pinguinarten im Bereich der Antarktischen Halbinsel bestimmen. Veränderungen des Eisregimes, der Wassertemperatur und Salinität beeinflussen die Primärproduktion und damit die gesamten Nahrungsnetze in den Südpolargebieten nachhaltig. Mit der Erwärmung wandern Tiere weiter polwärts. Doch unser Wissen über die Seevogelbestände ist begrenzt: Je weiter polwärts eine Art vorkommt, wie der Kaiserpinguin oder die südlichsten Adeliekolonien, desto weniger gesicherte Daten sind vorhanden.