bluuebunny/crossref_metadata_2025 huggingface dataset:
Perchlorate formation on Mars through surface radiolysis‐initiated atmospheric chemistry: A potential mechanism
Authors: Wilson Eric H. , Atreya Sushil K. , Kaiser Ralf I. , Mahaffy Paul R.
Published: August 2016

Recent observations of the Martian surface by the Phoenix lander and the Sample Analysis at Mars indicate the presence of perchlorate (ClO4–). The abundance and isotopic composition of these perchlorates suggest that the mechanisms responsible for their formation in the Martian environment may be unique in our solar system. With this in mind, we propose a potential mechanism for the production of Martian perchlorate: the radiolysis of the Martian surface by galactic cosmic rays, followed by the sublimation of chlorine oxides into the atmosphere and their subsequent synthesis to form perchloric acid (HClO4) in the atmosphere, and the surface deposition and subsequent mineralization of HClO4 in the regolith to form surface perchlorates. To evaluate the viability of this mechanism, we employ a one‐dimensional chemical model, examining chlorine chemistry in the context of Martian atmospheric chemistry. Considering the chlorine oxide, OClO, we find that an OClO flux as low as 3.2 × 107 molecules cm–2 s–1 sublimated into the atmosphere from the surface could produce sufficient HClO4 to explain the perchlorate concentration on Mars, assuming an accumulation depth of 30 cm and integrated over the Amazonian period. Radiolysis provides an efficient pathway for the oxidation of chlorine, bypassing the efficient Cl/HCl recycling mechanism that characterizes HClO4 formation mechanisms proposed for the Earth but not Mars.
Fracture size and transmissivity correlations: Implications for transport simulations in sparse three‐dimensional discrete fracture networks following a truncated power law distribution of fracture size
Authors: Hyman J. D. , Aldrich G. , Viswanathan H. , Makedonska N. , Karra S.
Published: August 2016

We characterize how different fracture size‐transmissivity relationships influence flow and transport simulations through sparse three‐dimensional discrete fracture networks. Although it is generally accepted that there is a positive correlation between a fracture's size and its transmissivity/aperture, the functional form of that relationship remains a matter of debate. Relationships that assume perfect correlation, semicorrelation, and noncorrelation between the two have been proposed. To study the impact that adopting one of these relationships has on transport properties, we generate multiple sparse fracture networks composed of circular fractures whose radii follow a truncated power law distribution. The distribution of transmissivities are selected so that the mean transmissivity of the fracture networks are the same and the distributions of aperture and transmissivity in models that include a stochastic term are also the same. We observe that adopting a correlation between a fracture size and its transmissivity leads to earlier breakthrough times and higher effective permeability when compared to networks where no correlation is used. While fracture network geometry plays the principal role in determining where transport occurs within the network, the relationship between size and transmissivity controls the flow speed. These observations indicate DFN modelers should be aware that breakthrough times and effective permeabilities can be strongly influenced by such a relationship in addition to fracture and network statistics.
Using Genetically Encodable Self‐Assembling GdIII Spin Labels To Make In‐Cell Nanometric Distance Measurements
Authors: Mascali Florencia C. , Ching H. Y. Vincent , Rasia Rodolfo M. , Un Sun , Tabares Leandro C.
Published: August 2016

Double electron–electron resonance (DEER) can be used to study the structure of a protein in its native cellular environment. Until now, this has required isolation, in vitro labeling, and reintroduction of the protein back into the cells. We describe a completely biosynthetic approach that avoids these steps. It exploits genetically encodable lanthanide‐binding tags (LBT) to form self‐assembling GdIII metal‐based spin labels and enables direct in‐cell measurements. This approach is demonstrated using a pair of LBTs encoded one at each end of a 3‐helix bundle expressed in E. coli grown on GdIII‐supplemented medium. DEER measurements directly on these cells produced readily detectable time traces from which the distance between the GdIII labels could be determined. This work is the first to use biosynthetically produced self‐assembling metal‐containing spin labels for non‐disruptive in‐cell structural measurements.
Insight into the Inhibition of Drug‐Resistant Mutants of the Receptor Tyrosine Kinase EGFR
Authors: Engel Julian , Becker Christian , Lategahn Jonas , Keul Marina , Ketzer Julia , Mühlenberg Thomas , Kollipara Laxmikanth , Schultz‐Fademrecht Carsten , Zahedi René P. , Bauer Sebastian , Rauh Daniel
Published: August 2016

Targeting acquired drug resistance represents the major challenge in the treatment of EGFR‐driven non‐small‐cell lung cancer (NSCLC). Herein, we describe the structure‐based design, synthesis, and biological evaluation of a novel class of covalent EGFR inhibitors that exhibit excellent inhibition of EGFR‐mutant drug‐resistant cells. Protein X‐ray crystallography combined with detailed kinetic studies led to a deeper understanding of the mode of inhibition of EGFR‐T790M and provided insight into the key principles for effective inhibition of the recently discovered tertiary mutation at EGFR‐C797S.
Functionalization of Hydrogenated Graphene: Transition‐Metal‐Catalyzed Cross‐Coupling Reactions of Allylic C−H Bonds
Authors: Chua Chun Kiang , Sofer Zdeněk , Pumera Martin
Published: August 2016

The chemical functionalization of hydrogenated graphene can modify its physical properties and lead to better processability. Herein, we describe the chemical functionalization of hydrogenated graphene through a dehydrogenative cross‐coupling reaction between an allylic C−H bond and the α‐C−H bond of tetrahydrothiophen‐3‐one using Cu(OTf)2 as the catalyst and DDQ as the oxidant. The chemical functionalization was confirmed by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy and visualized by scanning electron microscopy. The functionalized hydrogenated graphene material demonstrated improved dispersion stability in water, bringing new quality to the elusive hydrogenated graphene (graphane) materials. Hydrogenated graphene provides broad possibilities for chemical modifications owing to its reactivity.
The Oxygen‐Rich Beryllium Oxides BeO4 and BeO6
Authors: Zhang Qingnan , Jerabek Paul , Chen Mohua , Zhou Mingfei , Frenking Gernot
Published: August 2016

Two novel isomers of BeO4 with the structures OBeOOO and OBe(O3) in the electronic triplet state have been prepared as well as the known disuperoxide complex Be(O2)2 in solid noble‐gas matrices. We also report the synthesis of the oxygen‐rich bis(ozonide) complex Be(O3)2 in the triplet state which has a D2d equilibrium geometry. The molecular structures were identified by infrared absorption spectroscopy with isotopic substitutions as well as quantum chemical calculations.
Searching for the Antigonea Theatre: A Magnetic Survey in an Ancient Epirus City
Authors: Schettino Antonio , Çondi Dhimiter , Perna Roberto , Pierantoni Pietro Paolo , Ghezzi Annalisa
Published: August 2016

We report on two magnetic surveys performed in July and September 2015 at the ancient Hellenistic city of Antigonea, located in southern Albania. The main objective of the two surveys was to find the city theatre and determine possible sites of future excavations. We suggest a new technique for dense collecting of magnetic data along difficult terrains, with minimization of the topographic effect. Evidence of a possible location of the theatre was found along the southern slope of the Jermë hill, just outside the city walls. Other interesting structures indicate the presence of many other buildings in this part of the Antigonea settlement. Copyright © 2016 John Wiley & Sons, Ltd. StartCopTextStartCopTextCopyright © 2016 John Wiley & Sons, Ltd.
Begrenzung der Rissbreite nach Eurocode 2
Authors: Tue Nguyen Viet , Turner Katrin
Published: August 2016

Die Bemessung von Stahlbetonbauteilen erfolgt derzeit nach EC2 [1]. Ein wesentlicher Punkt in der Bemessung ist die Ermittlung der Mindestbewehrung gemäß den Angaben im Abschnitt 7.3.2. Durch die kompakte Darstellung der Gleichungen (7.1) und (7.2) in der Norm sind die mechanischen Zusammenhänge für die Anwender nicht einfach zu erkennen. Dies führt nicht selten zur falschen Interpretation der einzelnen Parameter und somit zu falschen Bemessungsergebnissen. Da die Mindestbewehrung in einzelnen Fällen die maßgebende Bewehrung für die Auslegung der Bauteile ist, insbesondere bei dicken Bauteilen, werden in diesem Beitrag die mechanischen Hintergründe für die beiden Gleichungen (7.1) und (7.2) dargestellt und erläutert. Hiermit sollte den in Ingenieurbüros tätigen Bauingenieuren mehr Sicherheit gegeben werden.
ÖBB Steyrtalbrücke – Belastungsprobe und Langzeitmessungen
Authors: Geier Roman , Menge Moritz , Mack Thomas , Petraschek Thomas
Published: August 2016

Zwischen Linz und Selzthal wurde an der Phyrnbahn in den Jahren 2013 bis 2014 die Steyrtalbrücke bei km 65,621 erneuert. Wesentliches Entwurfskriterium der ÖBB Infrastruktur AG als Bauherr war das Bestreben eines unter Life‐Cycle‐Cost‐Betrachtung optimierten Brückenbaus, der u. a. auch trotz der großen Brückenlänge von 182 m ohne wartungsintensive Schienenauszüge auskommt.

Ausgehend von den normativen Vorgaben sowie gewissen Gestaltungsfreiräumen, welche die einschlägigen Normen zulassen, wurden bei der Planung Sonderwege bei der Ermittlung der Schienenspannungen aus der Interaktion beschritten. Die Ergebnisse der Berechnung Interaktion Gleis/Tragwerk ermöglichten schließlich tatsächlich den Verzicht auf Schienenauszüge.

Im Planungsprozess wurden zahlreiche Annahmen getroffen, die anschließend über umfangreiche Messungen des tatsäch lichen Verhaltens verifiziert wurden. Dazu sollten neben Messungen während der statischen und dynamischen Belastungsprobe auch Langzeitmessungen durchgeführt werden, um das Tragverhalten über die Zeit beurteilen zu können sowie eine Bestätigung der Rechenansätze beim Nachweis der Gleis/Tragwerk‐Interaktion zu ermöglichen.

In diesem Artikel sollen die Planung des Messsystems, die Durchführung und Ergebnisse der Messungen während der Belastungsprobe und des darauffolgenden Jahreszyklus erläutert werden.
Untersuchungen zur Genauigkeit von magnetisch induktiven Betondeckungsmessungen
Authors: Taffe Alexander , Jungen Barbara
Published: August 2016

Zerstörungsfreie Prüfverfahren (ZfP) zur Messung der Betondeckung sind seit Jahrzehnten bei der Ermittlung des Istzustands von Bestandsbauwerken und als Werkzeug zur Qualitätssicherung sowohl im Neubau als auch in der Betoninstandsetzung fest etabliert. Um zuverlässige Prüfaussagen zu erhalten, ist es zunächst erforderlich, durch die richtige Anwendung eines geeigneten Verfahrens genaue Messergebnisse zu erzeugen und diese dann richtig zu bewerten, z. B. durch einen statistischen Nachweis der Mindestbetondeckung. Daher konzentriert sich dieser Beitrag zunächst auf die Grundlagen von ZfPBau‐Verfahren zur präzisen Messung der Betondeckung. Hierbei sind magnetisch induktive Verfahren von radarbasierten Verfahren zu unterscheiden, deren jeweilige Möglichkeiten und Grenzen dargelegt werden. Im zweiten Teil wird die erzielbare Genauigkeit mit unterschiedlichen Geräten nach magnetisch induktivem Messprinzip anhand von systematischen Untersuchungen betrachtet. Dabei wird quantifiziert, mit welchen Abweichungen zu rechnen ist, wenn der Durchmesser nicht genau bekannt ist und dicht benachbarte Stäbe das Mess ergebnis beeinflussen. Abschließend werden die verminderten Abweichungen quantifiziert, wenn geräteeigene Nachbar stabskorrekturen verwendet werden. Das Ziel dieses Beitrags ist kein „Gerätetest”, vielmehr soll am Beispiel verschiedener Geräte auf der Basis unterschiedlicher Messprinzipien gezeigt werden, welche Genauigkeit unter welchen Einflussgrößen bei realen Messungen zu erzielen ist.
Enhancing fatty acid production in Escherichia coli by Vitreoscilla hemoglobin overexpression
Authors: Liu Di , Wan Ni , Zhang Fuzhong , Tang Yinjie J. , Wu Stephen G.
Published: August 2016

Our recent 13C‐metabolic flux analysis (13C‐MFA) study indicates that energy metabolism becomes a rate‐limiting factor for fatty acid overproduction in E. coli strains (after “Push‐Pull‐Block” based genetic modifications). To resolve this bottleneck, Vitreoscilla hemoglobin (VHb, a membrane protein facilitating O2 transport) was introduced into a fatty‐acid‐producing strain to promote oxygen supply and energy metabolism. The resulting strain, FAV50, achieved 70% percent higher fatty acid titer than the parent strain in micro‐aerobic shake tube cultures. In high cell‐density bioreactor fermentations, FAV50 achieved free fatty acids at a titer of 7.02 g/L (51% of the theoretical yield). In addition to “Push‐Pull‐Block‐Power” strategies, our experiments and flux balance analysis also revealed the fatty acid over‐producing strain is sensitive to metabolic burden and oxygen influx, and thus a careful evaluation of the cost‐benefit tradeoff with the guidance of fluxome analysis will be fundamental for the rational design of synthetic biology strains. Biotechnol. Bioeng. 2017;114: 463–467. © 2016 Wiley Periodicals, Inc.
Simple Preparation of Rhodococcus erythropolis DSM 44534 as Biocatalyst to Oxidize Diols into the Optically Active Lactones
Authors: Martinez‐Rojas Enriqueta , Olejniczak Teresa , Neumann Konrad , Garbe Leif‐Alexander , Boratyñski Filip
Published: August 2016

In the current study, we present a green toolbox to produce ecological compounds like lactone moiety. Rhodococcus erythropolis DSM 44534 cells have been used to oxidize both decane‐1,4‐diol (2a) and decane‐1,5‐diol (3a) into the corresponding γ‐ (2b) and δ‐decalactones (3b) with yield of 80% and enantiomeric excess (ee) = 75% and ee = 90%, respectively. Among oxidation of meso diols, (−)‐(1S,5R)‐cis‐3‐oxabicyclo[4.3.0]non‐7‐en‐2‐one (5a) with 56% yield and ee = 76% as well as (−)‐(2R,3S)‐cis‐endo‐3‐oxabicyclo[2.2.1]dec‐7‐en‐2‐one (6a) with 100% yield and ee = 90% were formed. It is worth mentioning that R. erythropolis DSM 44534 grew in a mineral medium containing ethanol as the sole source of energy and carbon Chirality 28:623–627, 2016. © 2016 Wiley Periodicals, Inc.
Supply chain optimization of flare‐gas‐to‐butanol processes in alberta
Authors: Hoseinzade Leila , Adams Thomas A.
Published: August 2016

In this work, the economic feasibility of combining a novel portable gas‐to‐methanol process with a novel methanol‐to‐butanol process is examined. The gas‐to‐methanol process converts waste flare gas into methanol using a series of truck‐mounted devices deployed at oil production wellheads. The methanol‐to‐butanol process uses a new proprietary catalyst which produces butanol via a diketene intermediate at a large centralized facility. The goal of this work is to identify the best ways of commercializing this technology in Alberta. To do this, a supply chain optimization model is formulated which considers specifically how many gas‐to‐methanol trucks should be used and where specifically in Alberta they should be deployed, the specific suppliers of CO2 to use, where the location of the central methanol‐to‐butanol facility should be chosen, and the costs of transportation of materials between locations. The model framework also considers the possibility of getting methanol in full or in part by alternative means such as producing methanol from conventional pipeline natural gas, or purchasing methanol from petrochemical or biomass‐based routes. The supply chain optimization problem is formulated as a nonconvex NLP and BARON is used in a Pareto analysis considering weighted combinations of economic and environmental objective functions. The resulting analysis provides a variety of possible viable strategies which can provide both profitability and reduced environmental emissions in Alberta by using a combination of the novel portable flare gas capture devices with more conventional gas‐to‐liquids technologies.
Characteristics of water holdup for oil and water mixture flows in horizontal, vertical, and inclined pipes
Authors: Xu Jing‐yu , Liu Shuo , Zhang Dong , Zhang Jian
Published: August 2016

In this work, the water holdup and slippage for oil and water mixture flows in horizontal, vertical, and inclined pipes have been investigated. A large group of experimental data was collected from 21 different sources covering the whole range of inclination angles from −90° to 90° to reveal the holdup characteristics and develop the drift velocity model. The results show that in horizontal flows the water holdup is dependent to the flow pattern, and yet in vertical flows the water holdup is similar to the input one and the flow direction shows a few influences on the holdup. In inclined flows, the Froude numbers are relatively independent of inclination angles when the angles are greater than 30°. Therefore, the changes of water holdup in the pipe with small inclination angles are more severe than those with large inclination angles. In addition, a satisfactory agreement between predicted and experimental holdups substantiates the general validity of the proposed drift velocity correlation for oil and water flows, especially for those with large inclination angles.
Characterization and modelling of a maldistributed Trickle Bed Reactor
Authors: Augier Frédéric , Fourati Manel , Haroun Yacine
Published: August 2016

A Trickle Bed Reactor equipped with a non‐ideal distribution tray is investigated. First, a non‐ideal co‐current trickling flow of nitrogen and heptane, induced by a partially plugged tray, is characterized experimentally using the γ‐tomography technique. Resulting liquid saturation data are used to validate the Euler‐Euler CFD model developed in previous work of Solomenko et al.[16] on a 3D realistic flow. The resulting 3D CFD model is then coupled with simple isothermal kinetics of heteroatom removal of heavy petroleum cuts, and the effect of maldistribution on reactor performance is discussed. The problem of CFD model reduction to a 1D reactor model is finally addressed based on transport of internal ages distribution theory. Different 1D models are compared based on reactor effluent throughput. It is shown that a 1D‐Multi Exit reactor model that respects both the age variance at the system outlet as well as the degree of mixing inside the reactor gives the best prediction of the reactor performance.
Next‐generation sequencing survey of biliary tract cancer reveals the association between tumor somatic variants and chemotherapy resistance
Authors: Ahn Daniel H. , Javle Milind , Ahn Chul W. , Jain Apurva , Mikhail Sameh , Noonan Anne M. , Wu Christina , Shroff Rachna T. , Chen James L. , Bekaii‐Saab Tanios
Published: August 2016

BACKGROUND

Biliary tract cancers (BTCs) are uncommon and are associated with a dismal prognosis. Combinations of gemcitabine and platinum chemotherapy (gemcitabine and platinum–based therapy [GP]) form the standard approach for treating advanced BTC. To characterize the spectrum of mutations and to identify potential biomarkers for a GP response in BTC, this study evaluated the genomic landscape and assessed whether mutations affecting DNA repair were associated with GP resistance.

METHODS

Pretreatment, formalin‐fixed, paraffin‐embedded samples from 183 BTC patients treated with GP were analyzed. Cox regression models were used to determine the association between mutations, progression‐free survival (PFS), and overall survival (OS).

RESULTS

When genes with an incidence > 10% were considered, no individual gene was independently predictive of a GP response. In patients with unresectable BTC who received GP as their first‐line therapy, the joint status of cyclin‐dependent kinase inhibitor 2A (CDKN2A), tumor protein 53 (TP53), and AT‐rich interaction domain 1A (ARID1A) was associated with PFS (P = .0004) and OS (P ≤ .0001). Patients with mutations in CDKN2A and TP53 were identified as a poor‐prognosis cohort with a median PFS of 2.63 months and a median OS of 5.22 months. Patients with mutant ARID1A, regardless of the single‐mutation status of TP53 or CDKN2A, had similar outcomes. A patient who exhibited mutations in all 3 genes had a median PFS of 20.37 months, and OS was not reached.

CONCLUSIONS

In the largest exploratory analysis of this kind for BTC, 3 prevalent, mutually exclusive mutations represent distinct patient cohorts. These mutations are prognostic and may represent a predictive biomarker for a GP response. Prospective studies to validate these findings are needed, and they should include the incorporation of therapies that exploit the genomic instability observed with these mutations in BTC. Cancer 2016;122:3657‐66. © 2016 American Cancer Society.
Risks of first and subsequent cancers among TP53 mutation carriers in the National Cancer Institute Li‐Fraumeni syndrome cohort
Authors: Mai Phuong L. , Best Ana F. , Peters June A. , DeCastro Rosamma M. , Khincha Payal P. , Loud Jennifer T. , Bremer Renée C. , Rosenberg Philip S. , Savage Sharon A.
Published: August 2016

BACKGROUND

Li‐Fraumeni syndrome (LFS) is an autosomal dominant cancer predisposition syndrome characterized by a very high lifetime cancer risk and an early age at diagnosis of a wide cancer spectrum. Precise estimates for the risk of first and subsequent cancers are lacking.

METHODS

The National Cancer Institute's Li‐Fraumeni Syndrome Study includes families meeting the diagnostic criteria for LFS or Li‐Fraumeni‐like syndrome, and individuals with a germline TP53 mutation, choroid plexus carcinoma, adrenocortical carcinoma, or ≥3 cancers. Herein, we estimated the cumulative risk and annual hazards for first and second cancers among TP53 mutation carriers (TP53 positive [TP53+]) using MATLAB statistical software.

RESULTS

This study evaluated 286 TP53+ individuals from 107 families. The cumulative cancer incidence was 50% by age 31 years among TP53+ females and 46 years among males, and nearly 100% by age 70 years for both sexes. Cancer risk was highest after age 20 years for females, mostly due to breast cancer, whereas among males the risk was higher in childhood and later adulthood. Among females, the cumulative incidence rates by age 70 years for breast cancer, soft tissue sarcoma, brain cancer, and osteosarcoma were 54%, 15%, 6%, and 5%, respectively. Among males, the incidence rates were 22%, 19%, and 11%, respectively, for soft tissue sarcoma, brain cancer, and osteosarcoma. Approximately 49% of those with 1 cancer developed at least another cancer after a median of 10 years. The average age‐specific risk of developing a second cancer was comparable to that of developing a first cancer.

CONCLUSIONS

The cumulative cancer risk in TP53 + individuals was very high and varied by sex, age, and cancer type. Additional work, including prospective risk estimates, is needed to better inform personalized risk management. Cancer 2016;122:3673‐81. © 2016 American Cancer Society.
A novel social network access control model using logical authorization language in cloud computing
Authors: Ma Li , Tao Lixin , Gai Keke , Zhong Yong
Published: August 2016

Current rapid increasing implementations in data diversity, autonomy, and dynamic privilege management, fine‐grained access controls in social networks have resulted in various challenges in applying existing access control models. The intercrossing relations lead to the complex access control system, which often brings risks when the system is updated or expanded. The implementations of cloud computing has further complicate the access controls due to multiple tenancies and service providers. We focus on this issue and propose a new social network access control model using logical authorization language, named as RuleSN, which can be efficiently used in cloud systems. This model provides high performance of authorization expressiveness and flexibility that can effectively describe relations of User to User (U2U), User to Resource (U2R), Resource to Resource (R2R) and attributes of users and resources. First, this paper elaborates the formal definitions of the RuleSN model. Second, we describe the model's authorization specification and verification policies and explain the syntax and semantics of the authorization language. Finally, the implementation, application, and expressiveness of the model discussed by examples. Copyright © 2016 John Wiley & Sons, Ltd.
Cooperative frameworks and network models for flying ad hoc networks: a survey
Authors: Sharma Vishal , Kumar Rajesh
Published: August 2016

Integrated frameworks have extended the applications of networks beyond a simple data sharing unit. Simultaneously, operating networks can form a layered structure that can operate as homogeneous as well as dissociated units. Networks using unmanned aerial vehicles follow similar criteria in their operability. Unmanned aerial vehicles can act as single searching unit controlled by human or can form an aerial swarm that can fly autonomously with the capability of forming an aerial network. Such aerial swarms are categorized as aerial ad hoc networks. Cooperation amongst different networks can be realized using various frameworks, models, architectures and middlewares. Several solutions have been developed that can provide easy network deployment of aerial nodes. However, a combined literature is not present that provides a comparison between these approaches. Keeping this in view, various cooperative approaches for similar formation using aerial vehicles have been discussed in this paper. The detailed study and comparative analysis of these approaches have been included. Further, the paper also includes various software solutions and their comparisons based on common parameters. Finally, various open issues have been discussed that can provide insight of ongoing research and problems that are yet to be resolved in these networks. Copyright © 2016 John Wiley & Sons, Ltd.
Bayesian adaptive design: improving the effectiveness of monitoring of the Great Barrier Reef
Authors: Kang Su Yun , McGree James M. , Drovandi Christopher C. , Caley M. Julian , Mengersen Kerrie L.
Published: August 2016

Monitoring programs are essential for understanding patterns, trends, and threats in ecological and environmental systems. However, such programs are costly in terms of dollars, human resources, and technology, and complex in terms of balancing short‐ and long‐term requirements. In this work, We develop new statistical methods for implementing cost‐effective adaptive sampling and monitoring schemes for coral reef that can better utilize existing information and resources, and which can incorporate available prior information. Our research was motivated by developing efficient monitoring practices for Australia's Great Barrier Reef. We develop and implement two types of adaptive sampling schemes, static and sequential, and show that they can be more informative and cost‐effective than an existing (nonadaptive) monitoring program. Our methods are developed in a Bayesian framework with a range of utility functions relevant to environmental monitoring. Our results demonstrate the considerable potential for adaptive design to support improved management outcomes in comparison to set‐and‐forget styles of surveillance monitoring.
Large, connected floodplain forests prone to flooding best sustain plant diversity
Authors: Johnson Sarah E. , Amatangelo Kathryn L. , Townsend Philip A. , Waller Donald M.
Published: August 2016

Dams, levees, and water withdrawals disrupt hydrologic regimes and associated floodplain forests. Because these forests are also responding to changes in land use, species invasions, and climate change, the relative effects of these factors are hard to disentangle. Most studies of floodplain forests lack historic data, requiring us to rely on recent data or contemporary spatial relationships to these drivers to infer those causes of vegetation dynamics. Here, we use survey data from the 1950s to reconstruct plant community changes across 40 floodplain forests in Wisconsin. We applied two partial least squares regression (PLS) models to evaluate how current site and landscape scale conditions and changes in these conditions since the 1950s influence contemporary patterns of community diversity and composition. Local site variables were among the most important in explaining current composition metrics and their changes, but historic landscape variables and changes in these were also important. Current local diversity (α) was the highest at sites prone to frequent flooding, even at sites in fragmented landscapes. Sites along sinuous rivers in large watershed areas with more contiguous forest had the highest abundance of wetland indicator plants in the re‐survey and had the largest increases in α diversity since the 1950s, despite having the highest presence of exotic species then. These same sites have converged in composition, reflecting increases in wetland indicator plants and common native species. These patterns of increasing α diversity coupled with declines in community distinctiveness are uncommon among long‐term studies. Increases in wetland plants may indicate that sites have become wetter with hydrologic changes, but these increases may also reflect improved colonization and establishment processes involving a robust regional pool of generalist wetland taxa. Woody and exotic plants typical of upland forests increased at rarely flooded sites in fragmented and urbanizing landscapes, indicating shifts towards a later‐successional conditions and a dampened disturbance regime. This has reduced local species diversity and increased regional distinctness at some sites. As hydrologic connections appear to best maintain native species diversity and composition, even in fragmented landscapes, managers should seek to recreate these whenever feasible.
Elephants in the understory: opposing direct and indirect effects of consumption and ecosystem engineering by megaherbivores
Authors: Coverdale Tyler C. , Kartzinel Tyler R. , Grabowski Kathryn L. , Shriver Robert K. , Hassan Abdikadir A. , Goheen Jacob R. , Palmer Todd M. , Pringle Robert M.
Published: August 2016

Positive indirect effects of consumers on their resources can stabilize food webs by preventing overexploitation, but the coupling of trophic and non‐trophic interactions remains poorly integrated into our understanding of community dynamics. Elephants engineer African savanna ecosystems by toppling trees and breaking branches, and although their negative effects on trees are well documented, their effects on small‐statured plants remain poorly understood. Using data on 117 understory plant taxa collected over 7 yr within 36 1‐ha experimental plots in a semi‐arid Kenyan savanna, we measured the strength and direction of elephant impacts on understory vegetation. We found that elephants had neutral effects on most (83–89%) species, with a similar frequency of positive and negative responses among the remainder. Overall, estimated understory biomass was 5–14% greater in the presence of elephants across a range of rainfall levels. Whereas direct consumption likely accounts for the negative effects, positive effects are presumably indirect. We hypothesized that elephants create associational refuges for understory plants by damaging tree canopies in ways that physically inhibit feeding by other large herbivores. As predicted, understory biomass and species richness beneath elephant‐damaged trees were 55% and 21% greater, respectively, than under undamaged trees. Experimentally simulated elephant damage increased understory biomass by 37% and species richness by 49% after 1 yr. Conversely, experimentally removing elephant damaged branches decreased understory biomass by 39% and richness by 30% relative to sham‐manipulated trees. Camera‐trap surveys revealed that elephant damage reduced the frequency of herbivory by 71%, whereas we detected no significant effect of damage on temperature, light, or soil moisture. We conclude that elephants locally facilitate understory plants by creating refuges from herbivory, which countervails the direct negative effects of consumption and enhances larger‐scale biomass and diversity by promoting the persistence of rare and palatable species. Our results offer a counterpoint to concerns about the deleterious impacts of elephant “overpopulation” that should be considered in debates over wildlife management in African protected areas: understory species comprise the bulk of savanna plant biodiversity, and their responses to elephants are buffered by the interplay of opposing consumptive and non‐consumptive interactions.
Early warning of critical transitions in biodiversity from compositional disorder
Authors: Doncaster C. Patrick , Alonso Chávez Vasthi , Viguier Clément , Wang Rong , Zhang Enlou , Dong Xuhui , Dearing John A. , Langdon Peter G. , Dyke James G.
Published: August 2016

Global environmental change presents a clear need for improved leading indicators of critical transitions, especially those that can be generated from compositional data and that work in empirical cases. Ecological theory of community dynamics under environmental forcing predicts an early replacement of slowly replicating and weakly competitive “canary” species by slowly replicating but strongly competitive “keystone” species. Further forcing leads to the eventual collapse of the keystone species as they are replaced by weakly competitive but fast‐replicating “weedy” species in a critical transition to a significantly different state. We identify a diagnostic signal of these changes in the coefficients of a correlation between compositional disorder and biodiversity. Compositional disorder measures unpredictability in the composition of a community, while biodiversity measures the amount of species in the community. In a stochastic simulation, sequential correlations over time switch from positive to negative as keystones prevail over canaries, and back to positive with domination of weedy species. The model finds support in empirical tests on multi‐decadal time series of fossil diatom and chironomid communities from lakes in China. The characteristic switch from positive to negative correlation coefficients occurs for both communities up to three decades preceding a critical transition to a sustained alternate state. This signal is robust to unequal time increments that beset the identification of early‐warning signals from other metrics.
Discrimination of Octahedral versus Trigonal Bipyramidal Coordination Geometries of Homogeneous TiIV, VV, and MoVI Amino Triphenolate Complexes through Nitroxyl Radical Units
Authors: Badetti Elena , Lloveras Vega , Romano Francesco , Di Lorenzo Rosalia , Veciana Jaume , Vidal‐Gancedo José , Zonta Cristiano , Licini Giulia
Published: August 2016

A new stable radical‐containing ligand and the corresponding VV, TiIV, and MoVI complexes have been synthesized and studied by electron paramagnetic resonance (EPR) spectroscopy. To achieve this goal, a novel strategy for the post‐derivatization of a triphenolamine (TPA) ligand has been developed. This has allowed the effective embedding of three TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy) radicals in the corresponding metal complexes. In these systems, dipolar interactions among the organic radicals are strongly dependent on the geometry assumed in solution: a |Δms| = 2 transition is observed when the geometry of the complexes is octahedral, whereas no signal is detected with trigonal bipyramidal geometries.
Magnetic Bistability in Macrocycle‐Based FeII Spin‐Crossover Complexes: Counter Ion and Solvent Effects
Authors: Milin Eric , Benaicha Bouabdellah , El Hajj Fatima , Patinec Véronique , Triki Smail , Marchivie Mathieu , Gómez‐García Carlos J. , Pillet Sébastien
Published: August 2016

Two new iron(II) complexes of formula [Fe(L2)](tcm)2·2H2O (1) and [Fe(L2)][Ni(CN)4]·H2O (2) {L2 = 1,8‐bis(2′‐pyridylmethyl)‐1,4,8,11‐tetraazacyclotetradecane; tcm– = [C(CN)3]– = tricyanomethanide anion} have been synthesized and characterized by X‐ray diffraction and magnetic measurements and compared with the previously described compound of the same series [Fe(L2)](BF4)2·H2O (3). The crystal structures of the three compounds show discrete iron(II) complexes in which the FeII ions adopt distorted FeN6 octahedral geometries. A hydrogen‐bonding network involving the water molecules and the different counter ions, tcm– in 1 and [Ni(CN)4]2– in 2, leads to chains for both compounds whereas compound 3 reveals no significant intermolecular contacts. For 1, the magnetic measurements show an abrupt and incomplete high‐spin→low‐spin (HS→LS) spin transition (ST) with a hysteresis of 9 K (T1/2down = 136 K; T1/2up = 145 K) that is also optically observed. Compound 2 presents slightly weaker intermolecular contacts and shows an abrupt ST at 85 K without hysteretic behaviour. Finally, compound 3, in which the FeII complex is well isolated, exhibits a gradual spin transition centred at 150 K. Detailed X‐ray diffraction studies performed at various temperatures (293–120 K) show strong modifications of the iron coordination sphere in 1 and 3, in agreement with the presence of a ST in this temperature range in both complexes.
Bis(N‐methylimidazole)‐Substituted Neutral Phthalocyanines {MIII(MeIm)2(Pc)·3–}0 (M = Al, Ga) Containing Radical Trianionic Phthalocyanine Macrocycles
Authors: Konarev Dmitri V. , Kuzmin Alexey V. , Khasanov Salavat S. , Otsuka Akihiro , Yamochi Hideki , Saito Gunzi , Lyubovskaya Rimma N.
Published: August 2016

Reduction of aluminium(III) and gallium(III) chloride phthalocyanines (Pc) in the presence of N‐methylimidazole (MeIm) by sodium fluorenone ketyl allows the dissolution of phthalocyanines. Slow mixing with n‐hexane crystallizes formally neutral compounds [AlIII(MeIm)2(Pc)·3–]0·MeIm (1) and [GaIII(MeIm)2(Pc)·3–]0·2C6H4Cl2 (2), which contain radical trianionic phthalocyanine {Pc·3–} macrocycles. The formation of Pc·3– is confirmed by the appearance of new bands in the NIR range with maxima at 999 (1) and 994 nm (2) and a blueshift of both the Soret and Q‐bands of the phthalocyanines. The phthalocyanine macrocycles in 1 and 2 are planar with the central metal atoms positioned exactly in the Pc plane. The average lengths of the M–N(Pc) and M–N(MeIm) bonds in 1 are 1.956(3) and 2.055(2) Å, and they are elongated up to 1.987(1) and 2.161(1) Å, respectively, in 2. The formation of the 19π‐electron system of Pc·3– results in partial disruption of the aromaticity with alternation of shorter and longer C–N(imine) bonds belonging to two oppositely located isoindole units in 1 and 2. The presence of unpaired spins on the macrocycles is justified by intense Lorentzian EPR signals with g = 2.0028 and linewidth (ΔH) = 0.648 mT in 1 and g = 2.0011 and ΔH = 0.551 mT in 2 at room temperature. The effective magnetic moment of 2 of 1.65 µB at 300 K indicates the contribution of one non‐interacting S = 1/2 spin per formula unit, which is weakly antiferromagnetically coupled with a Weiss temperature of –6 K. Weak coupling can be explained by weak π–π interaction between the Pc·3– macrocycles in 2.
Increase in cannabis use may indirectly affect the health status of a freshwater species
Authors: Parolini Marco , Castiglioni Sara , Magni Stefano , Della Torre Camilla , Binelli Andrea
Published: August 2016

Cannabis is the most used illicit drug worldwide and in some countries a new regulatory policy makes it legal under some restrictions. This situation could lead to a substantial increase in environmental levels of the cannabis active principle (Δ-9-tetrahydrocannabinol [Δ-9-THC]) and its main metabolite, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). Although previous studies have highlighted the toxicity of Δ-9-THC, the adverse effects of THC-COOH on aquatic organisms is completely unknown, even though such effects could be more significant because the environmental concentrations of THC-COOH are higher than those of the parent compound. The present study aimed to assess oxidative and genetic damage to the zebra mussel (Dreissena polymorpha) because of 14-d exposures to 3 THC-COOH concentrations, mimicking a current environmental situation (100 ng/L), as well as exposure to 2 possible worst-case scenarios (500 ng/L and 1000 ng/L), because of the potential increase in THC-COOH in surface waters. Variations in the activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione S-transferase (GST) were measured, as well as levels of lipid peroxidation and protein carbonyl content. Genetic injuries were investigated by single-cell gel electrophoresis assay, DNA diffusion assay, and the micronucleus test. A significant imbalance in antioxidant defense enzymes was noted in response to the 3 tested concentrations, whereas oxidative damage was noted only at the higher one. Moreover, an increase in DNA fragmentation in zebra mussel hemocytes, but no fixed genetic damage, was found. Although the results showed that THC-COOH toxicity was lower than that of Δ-9-THC, the increase in cannabis use might increase its levels in freshwaters, enhancing its hazard to bivalves and likely to the whole aquatic community. Environ Toxicol Chem 2017;36:472–479. © 2016 SETAC
Population modeling for pesticide risk assessment of threatened species—A case study of a terrestrial plant, Boltonia decurrens
Authors: Schmolke Amelie , Brain Richard , Thorbek Pernille , Perkins Daniel , Forbes Valery
Published: August 2016

Although population models are recognized as necessary tools in the ecological risk assessment of pesticides, particularly for species listed under the Endangered Species Act, their application in this context is currently limited to very few cases. The authors developed a detailed, individual-based population model for a threatened plant species, the decurrent false aster (Boltonia decurrens), for application in pesticide risk assessment. Floods and competition with other plant species are known factors that drive the species’ population dynamics and were included in the model approach. The authors use the model to compare the population-level effects of 5 toxicity surrogates applied to B. decurrens under varying environmental conditions. The model results suggest that the environmental conditions under which herbicide applications occur may have a higher impact on populations than organism-level sensitivities to an herbicide within a realistic range. Indirect effects may be as important as the direct effects of herbicide applications by shifting competition strength if competing species have different sensitivities to the herbicide. The model approach provides a case study for population-level risk assessments of listed species. Population-level effects of herbicides can be assessed in a realistic and species-specific context, and uncertainties can be addressed explicitly. The authors discuss how their approach can inform the future development and application of modeling for population-level risk assessments of listed species, and ecological risk assessment in general. Environ Toxicol Chem 2017;36:480–491. © 2016 SETAC
High‐order discontinuous Galerkin nonlocal transport and energy equations scheme for radiation hydrodynamics
Authors: Holec M. , Limpouch J. , Liska R. , Weber S.
Published: August 2016

The nonlocal theory of the radiative energy transport in laser‐heated plasmas of arbitrary ratio of the characteristic inhomogeneity scale length to the photon mean free paths is applied to define the closure relations of a hydrodynamic system. The corresponding transport phenomena cannot be described accurately using the Chapman–Enskog approach, that is, with the usual fluid approach dealing only with local values and derivatives. Thus, we directly solve the photon transport equation allowing one to take into account the effect of long‐range photon transport. The proposed approach is based on the Bhatnagar–Gross–Krook collision operator using the photon mean free path as a unique parameter. Such an approach delivers a calculation efficiency and an inherent coupling of radiation to the fluid plasma parameters in an implicit way and directly incorporates nonequilibrium physics present under the condition of intense laser energy deposition due to inverse bremsstrahlung. In combination with a higher order discontinuous Galerkin scheme of the transport equation, the solution obeys both limiting cases, that is, the local diffusion asymptotic usually present in radiation hydrodynamics models and the collisionless transport asymptotic of free‐streaming photons. In other words, we can analyze the radiation transport closure for radiation hydrodynamics and how it behaves when deviating from the conditions of validity of Chapman–Enskog method, which is demonstrated in the case of exact steady transport and approximate multigroup diffusion numerical tests. As an application, we present simulation results of intense laser‐target interaction, where the radiative energy transport is controlled by the mean free path of photons. Copyright © 2016 John Wiley & Sons, Ltd.
Divergence preserving reconstruction of the nodal components of a vector field from its normal components to edges
Authors: Liska Richard , Shashkov Mikhail
Published: August 2016

We have developed a new divergence preserving method for the reconstruction of the Cartesian components of a vector field from the orthogonal projection of a vector field to the normals to edges in two dimensional. In this method, discrete divergences computed from the nodal components and from the normal ones are exactly the same. Our new method consists of two stages. At the first stage, we use an extended version of the local procedure described in [J. Comput. Phys., 139:406–409, 1998] to obtain a ‘reference’ nodal vector. This local procedure is exact for linear vector fields; however, the discrete divergence is not preserved. Then, we formulate a constrained optimization problem, in which this reference vector plays the role of a target, and the divergence constraints are enforced by using Lagrange multipliers. It leads to the solution of ‘elliptic’ like discrete equations for the cell‐centered Lagrange multipliers. The new global divergence preserving method is exact for linear vector fields. We describe all details of our new method and present numerical results, which confirm our theory. Copyright © 2016 John Wiley & Sons, Ltd.
The Skewness Implied in the Heston Model and Its Application
Authors: Zhang Jin E. , Zhen Fang , Sun Xiaoxia , Zhao Huimin
Published: August 2016

In this paper, we provide an exact formula for the skewness of stock returns implied in the Heston (1993) model by using a moment‐computing approach. We compute the moments of It integrals by using It's Lemma skillfully. The model's affine property allows us to obtain analytical formulas for cumulants. The formulas for the variance and the third cumulant are written as time‐weighted sums of expected instantaneous variance, which are neater and more intuitive than those obtained with the characteristic function approach. Our skewness formula is then applied in calibrating Heston's model by using the market data of the CBOE VIX and SKEW. © 2016 Wiley Periodicals, Inc. Jrl Fut Mark 37:211–237, 2017