bluuebunny/crossref_metadata_2025 huggingface dataset:
Nerve ultrasound in diabetic polyneuropathy: Correlation with clinical characteristics and electrodiagnostic testing
Authors: Hobson‐Webb Lisa D. , Massey Janice M. , Juel Vern C.
Published: August 2012

Introduction: Diabetic polyneuropathy (DPN) is increasingly prevalent in the USA, but nerve ultrasound (US) findings have not been assessed systematically. Our aim was to establish the sonographic characteristics of lower extremity nerves in DPN and correlate them with electrodiagnostic (EDx) findings. Methods: Consecutive patients (n = 25) with evidence of DPN and 25 patient controls without DPN underwent blinded US imaging of the fibular and sural nerves. Nerve cross‐sectional area (CSA), diameter and echogenicity were recorded. Results: There were no differences in fibular or sural nerve CSA, diameter, or echogenicity between the 2 groups. No correlations between nerve CSA and EDx studies were found. In DPN, there were moderate inverse correlations with age (r = −0.44 sural ankle, r = −0.39 sural leg, r = −0.45 fibular ankle). Conclusions: US measurements of lower extremity nerves in DPN do not differ from controls or correlate with EDx findings. Novel US techniques and/or pedal nerve US may be necessary to detect differences. Muscle Nerve 47:379‐384, 2013
On parallel solution of linear elasticity problems. Part III: higher order finite elements
Authors: Gustafsson Ivar , Lindskog Gunhild
Published: August 2012

This is the third part of a trilogy on parallel solution of the linear elasticity problem. We consider the separate displacement ordering for a plain isotropic problem with full Dirichlet boundary conditions. The parallel solution methods presented in the first two parts of the trilogy are here generalised to higher order by using hierarchical finite elements. We discuss node numberings on regular grids for high degree of parallelism and even processor load as well as the problem of stability of the modified incomplete Cholesky factorisations used. Several preconditioning techniques for the conjugate gradient method are studied and compared for quadratic finite elements. Bounds for the condition numbers of the corresponding preconditioning methods are derived, and computer experiments are performed in order to confirm the theory and give recommendations on the choice of method. The parallel implementation is performed by message passing interface. Copyright © 2012 John Wiley & Sons, Ltd.
UV Grafting of a Vinyl Monomer Onto a Methanol Plasma Polymer
Authors: Muir Benjamin W. , Tarasova Anna
Published: August 2012

We have shown that it is possible to graft a vinyl monomer from a plasma polymer surface in the presence of UV light without the use of a photoinitiator. A polyethylene glycol methacrylate (PEGMA) coating can be grown from the surface of a methanol plasma polymer via photopolymerization. It is proposed that the graft polymerization occurs from the generation and initiation of surface radicals by the applied UV light, in the methanol plasma polymer and the PEGMA monomer in solution. The coatings were characterised using X‐ray Photoelectron Spectroscopy and Atomic Force Microscopy (AFM). AFM analysis showed the interaction forces obtained between a silica probe and the PEGMA graft coatings to be repulsive and long‐ranged. The PEGMA coating was shown to be low fouling when placed in a protein solution.

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Low temperature transport properties of the BiCuSeO system
Authors: Berardan David , Zhao Li‐Dong , Barreteau Celine , Dragoe Nita
Published: August 2012

The discovery of a 26 K superconductivity in the tetragonal iron‐based pnictide LaFeAsO1 − xFx (x = 0.05–0.12) has stimulated a tremendous search for superconductivity in a wide class of materials with similar structure. Beside superconductivity, promising thermoelectric properties have been discovered in this family in the cryogenic temperature range and in the p‐type BiCuSeO system around 400–600 °C. In this paper, we report on the effect of various substitutions on the low temperature properties of this system. Whatever the substitution, all samples revealed p‐type, and no superconductivity was observed. Moreover, although some of these compounds exhibit very promising thermoelectric properties above room temperature, this is not the case in the low temperature range.
A new structure for error covariance matrices and their adaptive estimation in EnKF assimilation
Authors: Wu Guocan , Zheng Xiaogu , Wang Liqun , Zhang Shupeng , Liang Xiao , Li Yong
Published: August 2012

Correct estimation of the forecast and observational error covariance matrices is crucial for the accuracy of a data assimilation algorithm. In this article we propose a new structure for the forecast error covariance matrix to account for limited ensemble size and model error. An adaptive procedure combined with a second‐order least squares method is applied to estimate the inflated forecast and adjusted observational error covariance matrices. The proposed estimation methods and new structure for the forecast error covariance matrix are tested on the well‐known Lorenz‐96 model, which is associated with spatially correlated observational systems. Our experiments show that the new structure for the forecast error covariance matrix and the adaptive estimation procedure lead to improvement of the assimilation results. Copyright © 2012 Royal Meteorological Society
Theoretical study of novel porphyrins bearing electron donor–acceptor groups
Authors: Caicedo Carolina , Martínez Ana , Rivera Ernesto
Published: August 2012

This research project is focused on molecules that comprise a series of asymmetrically A3B‐type meso‐substituted free‐base porphyrins and their related Zn‐metalloporphyrins. A and B were taken as electron‐donor and electron–acceptor groups. Full geometry optimizations without symmetry constrains were performed with B3LYP/6‐31G(d,P) methodology. Time‐dependent density functional theory calculations of the optimized structures indicate that there is a good agreement with the available experimental results. The highest occupied molecular orbital–lowest occupied molecular orbital (LUMO) gaps (ranging between 2.62 and 2.80 eV) are similar to those reported before for other porphyrins (2.29 eV). Also, the LUMO is situated close to the conduction band of titanium oxide, increasing the possibility of a charge transfer process. As porphyrins may act as electron transfer systems, the electron donor–acceptor capacity of these systems is characterized using two parameters; electrodonating (χ−) and electroaccepting (χ+) electronegativity. The main goal of this investigation is to analyze the electronic structure and the donor–acceptor properties of these porphyrins to see if these compounds could be useful for further applications related to the design of solar cells. © 2012 Wiley Periodicals, Inc.
Robust H ∞  control via a stable decentralized nonlinear output feedback controller
Authors: Harno Hendra G. , Petersen Ian R.
Published: August 2012

This paper presents a new method to construct a decentralized nonlinear robust H ∞  controller for a class of large‐scale nonlinear uncertain systems. The admissible uncertainties and nonlinearities in the system satisfy integral quadratic constraints and global Lipschitz conditions, respectively. The decentralized controller, which is required to be stable, is capable of exploiting known nonlinearities and interconnections between subsystems without treating them as uncertainties. Instead, additional uncertainties are introduced because of the discrepancies between nondecentralized and decentralized nonlinear output feedback controllers. The H ∞  control objective is to achieve an absolutely stable closed‐loop system with a specified disturbance attenuation level. A solution to this control problem involves stabilizing solutions to algebraic Riccati equations parametrized by scaling constants corresponding to the uncertainties and nonlinearities. This formulation is nonconvex; hence, an evolutionary optimization method is applied to solve the control problem considered. Copyright © 2012 John Wiley & Sons, Ltd.
Key exposure free chameleon hash schemes based on discrete logarithm problem
Authors: Lim Seongan , Lee Juhee , An Youngjoo
Published: August 2012

A chameleon hash scheme is a trapdoor collision‐resistant hash scheme, and it provides many interesting features in signature schemes with hash‐and‐sign construction. In this paper, we introduce the notion of key exposure threshold τ for a chameleon hash scheme for which a key exposure free chameleon hash scheme can be understood as the case with τ = ∞. We propose chameleon hash schemes CHτ with the key exposure threshold τ based on discrete logarithm problem (DLP). For τ < ∞, the proposed scheme is noninteractive and key exposure free as long as k ephemeral trapdoors are disclosed for k < τ. The proposed scheme CH∞ is a key exposure free chameleon hash scheme based on DLP, and it requires a label directory that can be managed by a third party. This improves the only known efficient key exposure free chameleon hash scheme based on DLP, which requires one interaction with the trapdoor holder. Copyright © 2012 John Wiley & Sons, Ltd.
Novel method to prepare biological samples using powerful magnets on TOF‐SIMS analysis
Authors: Chang Chun‐Chao , Chen Chun‐Nan , Lin Wei‐Jhih , Lo Tsui‐Yun , Lei Shiou‐Ling , Mai Fu‐Der
Published: August 2012

Imaging with time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) has been shown to be a powerful analytical tool for mapping the distribution of biologically relevant small molecules (<1000 Da) on a surface. To improve the success rate of sample preparation, a device was designed to cells freeze‐fracture by using powerful magnets. Quantum dots (QDs) were used to observe the changes in the cell after freeze‐fracture. Then, TOF‐SIMS was employed to analyze the ionic and molecular distribution in the cells associated with the disease. Copyright © 2012 John Wiley & Sons, Ltd.
Investigating Structural Alterations in Pyrogallol[4]arene‐Pyrene Nanotubular Frameworks
Authors: Kumari Harshita , Kline Steven R. , Wycoff Wei G. , Atwood Jerry L.
Published: August 2012

Small‐angle neutron scattering (SANS) and diffusion NMR studies are performed to investigate the stability and geometry of hydrogen‐bonded pyrene‐guest‐containing C‐hexylpyrogallol[4]arene (PgC6‐pyrene) nanotubular frameworks in solution. In the solid state, hydrogen‐bonded pyrogallol[4]arene tubes are formed; however, the scattering data for PgC6‐pyrene assemblies in acetone are best modeled as dimeric spheres of PgC6 with no pyrene guest. The result of diffusion NMR study also indicates the rearrangement of tubular entity into spherical framework in acetone. This is the first example of structural transformation of pyrogallol[4]arene nanotubes (guest‐exo) in solution. Individual hydrogen‐bonded spheres of PgC6 exhibits a uniform radius of ca. 8.6 Å and a diffusion coefficient of 9.12 × 10−10 m2 s−1 in acetone. The diffusion NMR measurements further gave, for the first time, insights into how the type of solvent (acetone vs. methanol vs. acetontitrile/D2O) governs the structural differences in these nanoassemblies. Solution‐phase structural alteration observed for PgC6‐pyrene gives evidence of enhanced stability of pyrogallol[4]arene nanocapsules over nanotubes.
Fault‐tolerant timestamp‐based two‐phase commit protocol for RESTful services
Authors: Maciel Luiz Alexandre Hiane da Silva , Hirata Celso Massaki
Published: August 2012

Service‐oriented architecture provides interoperability and weak coupling features for software development. Representational state transfer (REST) is an architectural style that has attracted attention in the SOA domain as it allows the development of Web services based on original principles of the World Wide Web. Unlike Web service specifications, which are based on Simple Object Access Protocol and Web Services Description Language, REST does not provide ‘official’ standards to address non‐functional requirements of services, such as security, reliability, and transaction control. The timestamp‐based two‐phase commit protocol for RESTful service (TS2PC4RS) algorithm specifies concurrency control of RESTful services during a transaction. An extension of the TS2PC4RS specifies the concurrency control of the Web services considering the update operation to meet some business rules. However, neither algorithm addresses transaction control when failures occur. In long‐term transactions, failures can occur and compromise the success of Web service applications. Two common failures traditionally considered in the analysis of protocols are host and connection failures. The aim of this paper is to address fault tolerance for TS2PC4RS and its extension. A fault‐tolerant protocol based on timeout and log records is proposed. The fault‐tolerant protocol provides support for the host and connection failures that may occur during a transaction execution. The fault‐tolerant mechanisms are used to meet the application domain business rules that guide the behavior of RESTful services. We describe the protocol using scenarios when failures occur. Copyright © 2012 John Wiley & Sons, Ltd.
Automatic review identification on the web using pattern recognition
Authors: van der Meer Jeroen , Frasincar Flavius
Published: August 2012

In this paper we propose the Automatic Review Recognition and annOtation of Webpages method, which is capable of identifying and annotating user submitted reviews on a Web page. The method consists of six steps: data preparation, page‐level pattern identification, subjectivity analysis, container structure analysis, review properties identification, and review annotation. For the evaluation, we have implemented the method and tested it on various review websites. On the basis of the performed evaluation, we conclude that our method is capable of identifying and annotating the majority of reviews. Copyright © 2012 John Wiley & Sons, Ltd.
Zur Reaktion von Triphenylphosphan mit Thionylchlorid
Authors: Klein Hans‐Friedrich , Kuhn Annette , Kuhn Norbert , Laufer Stefan , Ströbele Markus
Published: August 2012

Triphenylphosphine reacts with thionyl chloride to give [Ph3PCl]Cl, Ph3PO and Ph3PS the formation of the anions S(O)Cl and SCl being discussed; the crystal structure of [Ph3PCl]Cl·S(O)Cl2 is reported.
Do canopy herbivores mechanically facilitate subsequent litter decomposition in soil? A pilot study from a Neotropical cloud forest
Authors: Cárdenas Rafael E. , Dangles Olivier
Published: August 2012

There is increasing evidence that the above‐ and belowground components of ecosystems influence one another, thereby controlling key processes such as organic matter decomposition. The aim of this study was to test the hypothesis that leaf herbivory in forest canopies could facilitate subsequent leaf litter decomposition in soils, through changes in leaf quality (i.e., litter palatability) or geometric form (i.e., increased availability of leaf edges made by herbivore damages). In a 9‐month field experiment in an Ecuadorian tropical cloud forest, we compared the decomposition rates of entire leaves (EL) and 15 %‐damaged leaves (DL) of Ficuscuatrecasana showing similar initial leaf chemistry. We found that DL decomposed significantly faster than EL in early stages of decomposition (i.e., between 0 and 38 days). A parallel experiment using cellulose discs on which we simulated different degrees of damages revealed, however, that geometry per se (i.e., increased edge availability) did not influence decomposition rates. We discuss these contrasting results and propose that higher edge availability in damaged leaves may promote the access of microbes and/or macro‐detritivores to leaf tissues thereby enhancing the initial stages of leaf decomposition.
Identification of condition‐specific reference genes from microarray data for locusts exposed to hypobaric hypoxia
Authors: Zhao De-Jian , Guo Kun , Kang Le
Published: August 2012

Real‐time quantitative polymerase chain reaction (qPCR) is a routine and robust approach for measuring gene expression. The stability of reference genes in qPCR is crucial for the accurate quantification of gene expression. To provide reliable reference genes for studying the transcriptional responses of locust muscles to hypobaric hypoxia, we first examined the gene expression stability of the frequently used housekeeping genes 18S, GAPDH, and β‐actin. However, the expression of these three housekeeping genes was influenced by hypobaric hypoxia. Consequently, we identified five novel candidate reference genes from the locust microarray data. The gene expression stability of the five candidates, together with the three classical housekeeping genes, were evaluated using two distinct algorithms implemented in geNorm and NormFinder. GeNorm identified Ach (acetyl‐CoA hydrolase) and Pgp (phosphoglycolate phosphatase‐like) as the most stable genes and NormFinder further distinguished Ach as the most stable one. The validity of Ach as a reference gene was confirmed through comparison with 18S. This study exemplifies the necessity of validating reference genes before their application and the feasibility of identifying condition‐specific reference genes from large‐scale gene expression data.
Differential effects of developmental hypo‐ and hyperthyroidism on acetylcholinesterase and butyrylcholinesterase activity in the spinal cord of developing postnatal rat pups
Authors: Koohestani Faezeh , Brown Chester M. , Meisami Esmail
Published: August 2012

The plasticity and vulnerability of the rat spinal cord (SC) during postnatal development has been less investigated compared to other CNS structures. In this study, we determined the effects of thyroid hormonal (TH) deficiency and excess on postnatal growth and neurochemical development of the rat SC. The growth as well as the specific and total activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes of the SC were determined in hypo‐ and hyperthyroid rat pups at postnatal (P) days P1, P5, P10 and P21 (weaning), and were compared to age‐matched untreated normal controls. AChE is a cholinergic synaptic enzyme while BuChE is a metabolic enzyme mainly found in glial cells and neurovascular cells. The SC is rich in somatic motor, autonomic cholinergic neurons and associated interneurons. Daily subcutaneous injection of pups with thyroxine (T4) and administration of antithyroid goitrogen propylthiouracil (PTU) in the litter's drinking water were used to induce hyper‐ and hypothyroidism, respectively. Enzyme assays were carried out spectrophotometrically at the above‐mentioned ages, using SC homogenates with acetylthiocholine‐chloride as the substrate, together with specific cholinesterase inhibitors, which specifically target AChE and BuChE. SC weights were significantly lower at P10 and P21 in hypothyroid pups but unchanged in the hyperthyroid ones. Hypothyroidism significantly reduced both specific and total AChE activity in SC of P10 and P21 rat pups, while having no effects on the BuChE activity, although total BuChE activity was decreased due to reduced total tissue weight. In contrast both specific and total AChE activities were markedly and significantly increased (>100%) in the P10 and P21 hyperthyroid pups. However, BuChE specific activity was unaffected by this treatment. The results indicate that hypothyroid condition significantly reduces, while hyperthyroidism increases, the postnatal development of cholinergic synapses, thereby influencing the functional development of this major sensory and motor structure. However, the neurochemical development of glia and other non‐neuronal cells, where BuChE is mainly localized, is comparatively unaffected in these abnormal developmental conditions.
A mad crowd: Skinhead youth and the rise of nationalism in post-communist Russia
Authors: Worger Peter
Published: August 2012

This paper deals with the emergence of skinhead groups in Russia and the extent to which this subculture has influenced and been influenced by political developments in the country. The research builds on a wide variety of sources in order to explain the complex processes at work that have led to this social phenomenon. I intend to show that these groups signify a fundamental trend in Russian political culture rather than operating on the margins of it, and that they are the result of political reformations in the country and the spread of global capitalism.
Prejudice and Discrimination From Two Sides: How Do Middle-Eastern Australians Experience It and How Do Other Australians Explain It?
Authors: Pedersen Anne , Dunn Kevin , Forrest James , McGarty Craig
Published: August 2012

There is little quantitative research regarding the causes and expression of prejudice and discrimination against Middle-Eastern Australians. We report two studies, one from the perspective of new settlers and a second from the perspective of host communities. The first found that Middle-Eastern Australians reported more discrimination compared with non-Middle-Eastern Australians. More discrimination was reported by Middle-Eastern males compared with females on dealings with the police, disrespect, name-calling, and distrust. The second study, focusing on attitudes of other Australians, found that they were more likely to perceive that Middle-Eastern Australians would be discriminated against compared with their own social group. When the non-Middle-Eastern Australians in the survey were asked for reasons why Australians from the Middle East were discriminated against, the most prevalent themes were (a) perceived conflict with ‘Australian values’, (b) fear of Muslims, (c) fear of terrorism, (d) negative media and (e) fear of difference. The overall finding that there are strong levels of public acknowledgment of the higher discriminatory burden endured by Middle-Eastern Australians is seen as a positive in terms of (1) community action to address that burden through (2) counteracting the socially negative attitudes that underpin discrimination in some Australian communities.
On the inverse kinematics of an a priori unknown general 6R-Robot
Authors: Groh Friedemann , Groh Konrad , Verl Alexander
Published: August 2012

This paper looks at the inverse kinematics problem of an a priori unknown 6R-Robot from the representation point of view. It describes a new representation of the Euclidean motion group. With this representation, the inverse kinematics problem can be treated entirely numerical. No symbolical methods are required.
Manin's conjecture for a cubic surface with 2A2 + A1 singularity type
Authors: LE BOUDEC PIERRE
Published: August 2012

We establish Manin's conjecture for a cubic surface split over ℚ and whose singularity type is 2A2 + A1. For this, we make use of a deep result about the equidistribution of the values of a certain restricted divisor function in three variables in arithmetic progressions. This result is due to Friedlander and Iwaniec (and was later improved by Heath–Brown) and draws on the work of Deligne.
The ranks of central factor and commutator groups
Authors: KURDACHENKO LEONID A. , SHUMYATSKY PAVEL
Published: August 2012

The Schur Theorem says that if G is a group whose center Z(G) has finite index n, then the order of the derived group G′ is finite and bounded by a number depending only on n. In this paper we show that if G is a finite group such that G/Z(G) has rank r, then the rank of G′ is r-bounded. We also show that a similar result holds for a large class of infinite groups.
EVELINE MABEL BURNS: THE NEGLECTED CONTRIBUTIONS OF A SOCIAL SECURITY PIONEER
Authors: KASPER SHERRY DAVIS
Published: August 2012

From the 1920s to the 1980s, Dr. Eveline Mabel Burns made significant contributions to the discipline of economics. During her career, she taught at world-class universities, including the London School of Economics and Columbia University. She published in the fields of labor economics, general economic theory, economic forecasting, methodology, and social security in leading economic journals. In the 1930s, she began her work in establishing the social security system in the United States. Yet, despite this multitude of accomplishments, the work of Eveline Mabel Burns is barely discernible in accounts of the evolution of twentieth-century economics. This essay remedies that neglect by explicating her career and economics. First, it describes her early years as an economist as she determined the ultimate course of her professional career. Second, it outlines the hybrid institutional method of analysis she used. Third, it describes how she made use of this methodology in her work on social security. Finally, it concludes with an interpretation of her neglect in twentieth-century economics that highlights her gender and her use of institutional methods of analysis.
CLARE DE GRAFFENREID AND THE ART OF CONTROVERSY: A PRIZEWINNING WOMAN ECONOMIST IN THE FIRST DECADE OF THE AMERICAN ECONOMIC ASSOCIATION
Authors: DIMAND ROBERT W. , BLACK GEOFFREY
Published: August 2012

The outspoken social reformer Mary Clare de Graffenreid (born 1849, died 1921) stood out among the handful of early women members of the American Economic Association (founded 1885) as the winner of two essay competitions. In 1889, Clare de Graffrenreid’s essay shared the $100 first prize in an AEA essay competition on child labor, and appeared the following year in thePublications of the American Economic Association(1stseries, 5, 2, March 1890, pp. 194–271). In 1891 her essay “The Condition of Wage-Earning Women” (published inForum15, March 1893, pp. 68–82) won the $300 first prize in an AEA essay competition on women workers (the $200 second prize went to Helen Campbell’s “Women Wage Earners,” 1893). Her valedictory address at Wesleyan Female College in Macon, Georgia, in 1865 provided her first taste of public controversy, as the general commanding Union troops in the area responded by placing the college under guard and threatening to close it, but by far the most controversial of her twenty-seven publications was “The Georgia Cracker in the Cotton Mill” (Century Magazine, February 1891). This paper examines de Graffenreid’s career and contributions, and what her career reveals about the paths for women to participate in the AEA and the American economics profession in the late nineteenth century. After teaching Latin, literature, and mathematics for a decade at Georgetown Female Seminary, de Graffenreid had a non-academic career as an investigator with the Bureau of Labor (from 1888, Department of Labor) from 1886 until she retired in 1906. Despite her AEA prizes, her published lectures to other conferences (YWCA, National Conference of Charities and Correction), and her published testimony to the Industrial Commission on the Relations of Capital and Labor, she was never on the program of an AEA meeting. Like other women economists of her time, de Graffenreid crossed boundaries between scholarly research and social reform, and between different scholarly disciplines (e.g., publishing “Some Social Economic Problems” inAmerican Journal of Sociology, 1896). The paper examines how essay competitions provided women such as de Graffenreid and Campbell (and Julie-Victoire Daubié and Clémence Royer in France) with a voice in the predominately male economics profession of the late nineteenth century.
RELATIVE INCOME VS. PERMANENT INCOME: THE CRISIS OF THE THEORY OF THE SOCIAL SIGNIFICANCE OF CONSUMPTION
Authors: TREZZINI ATTILIO
Published: August 2012

The investigation of aggregate consumption underwent a radical change in the USA during the 1940s and 1950s. Principles deriving from the American Institutionalist tradition attained their greatest popularity in Duesenberry’s formulation just before they were rapidly abandoned. This paper examines this turning point by comparing Duesenberry’s relative income hypothesis and Friedman’s permanent income hypothesis. This also makes it possible to identify a particular feature of Duesenberry’s analysis—its heterogeneity—which must be taken into consideration by those seeking a return to Institutionalist principles in the analysis of aggregate consumption.
ADAM SMITH ON METHOD: NEWTONIANISM, HISTORY, INSTITUTIONS, AND THE “INVISIBLE HAND”
Authors: FIORI STEFANO
Published: August 2012

Smith was influenced by Newton’s method. Nonetheless, he introduced elements that led him far from the Newtonian perspective. The present essay analyzes how historical dimensions, contingencies, institutions, and conflicting human inclinations modify a Newtonian horizon. Finally, the paper focuses on how, in Smith’s view, institutions determine “unintended outcomes,” which are sometimes opposed to those of the market. In this sense, the “invisible hand” is not only the result of the behavior of myopic individuals trying to improve their conditions; it is also the outcome of the work of institutions that operate as structures autonomous with respect to individuals.
Report focuses on improving resilience to disasters
Authors: Showstack Randy
Published: August 2012

“Disaster resilience is everyone's business,” states a new report that calls for a series of local and national measures to increase resilience in the face of an increasingly costly toll from natural disasters to human lives and the economy. In 2011 natural disasters were responsible for damages in the United States exceeding $55 billion, and costs could increase with more people and structures located in harm's way and with the effects of extreme events, according to the report, Disaster Resilience: A National Imperative, issued by a committee of the U.S. National Academies on 1 August. Among the recommendations is for federal government agencies to incorporate national resilience as an organizing principle to guide federal government actions and programs. The report defines resilience as “the ability to prepare and plan for, absorb, recover from, and more successfully adapt to adverse events.”
Section of thermohaline circulation driven by transient current rings
Authors: Schultz Colin
Published: August 2012

The southward branch of the Atlantic Meridional Overturning Circulation (AMOC), the stretch that carries deep, cold water from the North Atlantic to the Southern Ocean, predominantly flows along the eastern shoreline of the Americas. This deep water transport, known as the Deep Western Boundary Current, hits a fork in the flow at 25°S, off the coast of Brazil. Here the current splits in two, with the majority continuing its southbound journey and a smaller ribbon veering to the east. This eastbound water travels at depth across the South Atlantic, eventually passing around Africa's southern coast. In its path from Brazil to Africa the water crosses lines of consistent vorticity—essentially traveling uphill. Though researchers have known of this current for decades, little is known of what drives it.
An assessment of geochemical preparation methods prior to organic carbon concentration and carbon isotope ratio analyses of fine‐grained sedimentary rocks
Authors: Könitzer Sven F. , Leng Melanie J. , Davies Sarah J. , Stephenson Michael H.
Published: August 2012

This study summarizes organic carbon isotope (δ13C) and total organic carbon (TOC) data from a series of tests undertaken to provide an appropriate methodology for pre‐analysis treatment of mudstones from an Upper Carboniferous sedimentary succession, in order to develop a consistent preparation procedure. The main treatments involved removing both inorganic carbonate and hydrocarbons (which might be extraneous) before δ13C and TOC analysis. The results show that decarbonating using hydrochloric acid causes significant reduction in δ13C and total carbon (TC) of the bulk material due to the removal of inorganic carbonate. These changes are most pronounced where soluble calcium carbonate (rather than Ca‐Mg‐Fe carbonate) is present. Deoiled samples show only slightly higher mean δ13C where visible bitumen was extracted from the bulk sample. Moreover, the isotopic signatures of the extracts are closely correlated to those of their respective bulk samples, suggesting that small yields of hydrocarbons were generated in situ with no isotopic fractionation. In addition, further δ13C and TC analyses were performed on samples where mixing of oil‐based drilling mud with brecciated core material had been undertaken. Brecciated mudstone material did not display distinct isotopic signals compared to the surrounding fine‐grained material. Overall we show that the most accurate assessment of bulk organic carbon isotopes and concentration in these samples can be achieved through decarbonating the material prior to measurement via the ‘rinse method’. However, our results support recent findings that pre‐analysis acid treatments can cause variable and unpredictable errors in δ13C and TOC values. We believe that, despite these uncertainties, the findings presented here can be applied to paleoenvironmental studies on organic matter contained within sedimentary rocks over a range of geological ages and compositions.
I‐STAL, a model for interpretation of Mg/Ca, Sr/Ca and Ba/Ca variations in speleothems and its forward and inverse application on seasonal to millennial scales
Authors: Stoll Heather M. , Müller Wolfgang , Prieto Manolo
Published: August 2012

Trace element ratios Mg/Ca, Sr/Ca, and Ba/Ca are readily measured in speleothems and may be closely related to hydrological balance, enhancing paleoclimate information inferred from stable isotope measurements. We develop a model which simulates the variation in dripwater chemistry resulting from variable degree of water‐rock interaction and prior calcite precipitation (PCP), with the latter process depending both on drip interval and drip oversaturation with respect to CaCO3. Partition coefficients between speleothem and dripwater are dependent on temperature for Mg and on speleothem growth rate for Sr and Ba, as observed in laboratory experiments. The drip oversaturation state, regulated both by cave pCO2 and the dilution and soil karst dissolution processes, strongly affects stalagmite trace element concentrations by modulating the extent of PCP and speleothem growth rates. Application of an inverse model confirms that seasonal CO2 cycles can explain the uncorrelated seasonal cycles in Mg/Ca and Sr/Ca observed in our speleothem records from NW Spain for which high CO2 coincides with dry season. In absence of seasonal variations in drip interval, cycles in cave pCO2 can produce seasonal covariation in Sr/Ca, Mg/Ca and Ba/Ca. In long time series (104 yr) where seasonal sampling resolution is not obtained in stalagmites, a change from dominance of summer to winter rainfall can shift the season of strongest stalagmite deposition to one of lower mean CO2 and hence greater PCP and higher Mg/Ca, Sr/Ca and Ba/Ca ratios. Caves best suited to record a dominantly water balance signal, such as mean drip intervals, are those with minimal seasonal variation in cave pCO2.
On the clustering of climate models in ensemble seasonal forecasting
Authors: Yuan Xing , Wood Eric F.
Published: August 2012

Multi‐model ensemble seasonal forecasting system has expanded in recent years, with a dozen coupled climate models around the world being used to produce hindcasts or real‐time forecasts. However, many models are sharing similar atmospheric or oceanic components which may result in similar forecasts. This raises questions of whether the ensemble is over‐confident if we treat each model equally, or whether we can obtain an effective subset of models that can retain predictability and skill as well. In this study, we use a hierarchical clustering method based on inverse trigonometric cosine function of the anomaly correlation of pairwise model hindcasts to measure the similarities among twelve American and European seasonal forecast models. Though similarities are found between models sharing the same atmospheric component, different versions of models from the same center sometimes produce quite different temperature forecasts, which indicate that detailed physics packages such as radiation and land surface schemes need to be analyzed in interpreting the clustering result. Uncertainties in clustering for different forecast lead times also make reducing redundant models more complicated. Predictability analysis shows that multi‐model ensemble is not necessarily better than a single model, while the cluster ensemble shows consistent improvement against individual models. The eight model‐based cluster ensemble forecast shows comparable performance to the total twelve model ensemble in terms of probabilistic forecast skill for accuracy and discrimination. This study also manifests that models developed in U.S. and Europe are more independent from each other, suggesting the necessity of international collaboration in enhancing multi‐model ensemble seasonal forecasting.
Tropical cyclone and extreme rainfall trends in East Asian summer monsoon since mid‐20th century
Authors: Chang Chih‐Pei , Lei Yonghui , Sui Chung‐Hisung , Lin Xiaohong , Ren Fumin
Published: August 2012

Proper interpretations of extreme rainfall trends in the Asian monsoon regions are complicated by tropical cyclones (TCs) from tropical oceans, whose rainfall trend may be different from the local monsoon (non‐TC) rain. Here we show that the trends over the China summer monsoon region have been distorted by western North Pacific typhoons, which bring rainfall with decreasing frequency and increasing intensity. Typically the latter is not sufficient to overcome the former, so TC‐related extreme rainfall trend is smaller than monsoon‐related extreme rainfall. The net impact underestimates the increasing trend and overestimates the decreasing trend in monsoon extreme rainfall over most areas. The effect is minimal in the Meiyu rain belt region, but reaches 30% in northeastern and southern China. The largest distortions occur on offshore islands in the main TC paths that underwent significant decadal variations. In Hainan, the −3%/decade trend becomes +7%/decade if typhoon rainfall is removed. An opposite case occurs in Taiwan, where the extreme rainfall trend is hugely inflated by local increases in TC rainfall. These opposite effects emphasize the importance of considering the different mechanisms of rainfall systems in order to avoid mis‐attribution of regional effects on extreme rainfall to thermodynamic consequences of global warming.
An intelligent agent for optimal river‐reservoir system management
Authors: Rieker Jeffrey D. , Labadie John W.
Published: August 2012

A generalized software package is presented for developing an intelligent agent for stochastic optimization of complex river‐reservoir system management and operations. Reinforcement learning is an approach to artificial intelligence for developing a decision‐making agent that learns the best operational policies without the need for explicit probabilistic models of hydrologic system behavior. The agent learns these strategies experientially in a Markov decision process through observational interaction with the environment and simulation of the river‐reservoir system using well‐calibrated models. The graphical user interface for the reinforcement learning process controller includes numerous learning method options and dynamic displays for visualizing the adaptive behavior of the agent. As a case study, the generalized reinforcement learning software is applied to developing an intelligent agent for optimal management of water stored in the Truckee river‐reservoir system of California and Nevada for the purpose of streamflow augmentation for water quality enhancement. The intelligent agent successfully learns long‐term reservoir operational policies that specifically focus on mitigating water temperature extremes during persistent drought periods that jeopardize the survival of threatened and endangered fish species.
Influence of delta-doping on the performance of Ge/Si quantum-dot mid-infrared photodetectors
Authors: Yakimov A. I. , Timofeev V. A. , Bloshkin A. A. , Kirienko V. V. , Nikiforov A. I. , Dvurechenskii A. V.
Published: August 2012

The effect of delta-doping on the performance of ten-period Ge/Si quantum-dot (QD) mid-infrared photodetectors (λmax≃3.4 μm) was investigated. Ge QDs fabricated by molecular-beam epitaxy at 500 °C are overgrown with Si at 600 °C. Each Si barrier contains a boron delta-doping layer located near the QD plane to provide holes to the dots. Within the sample set, we examined devices with different positions of the δ-doping layer with respect to the QD plane, different distances between the δ-doping layer and the QD plane, and different doping densities. All detectors show pronounced photovoltaic behavior implying the presence of an internal inversion asymmetry. We observed a reversal of the voltage dependence of responsivity with respect to zero bias when the δ-doping plane is carried from the bottom to the top of the dot layer. This result indicates that the main reason for the asymmetric photoresponse is the existence of a built-in electric field due to the placing dopants in the barriers. Devices with a lower doping density (pB=4×1011 cm−2) or with a shorter distance between the doping layer and QDs (d = 2 nm) are found to operate better in a photoconductive mode with the highest peak detectivity of about 6×1010 cm Hz1/2/W at T = 90 K and 0.2 V bias. The best performance is achieved for the device with pB=12×1011 cm−2 and d = 5 nm in a photovoltaic regime. At a sample temperature of 90 K and no applied bias, a responsivity of 0.83 mA/W and detectivity of 8×1010 cm Hz1/2/W at λ=3.4 μm were measured under normal incidence infrared radiation.
Wedge-local quantum fields on a nonconstant noncommutative spacetime
Authors: Much A.
Published: August 2012

Within the framework of warped convolutions we deform the massless free scalar field. The deformation is performed by using the generators of the special conformal transformations. The investigation shows that the deformed field turns out to be wedge-local. Furthermore, it is shown that the spacetime induced by the deformation with the special conformal operators is nonconstant noncommutative. The noncommutativity is obtained by calculating the deformed commutator of the coordinates.
Ab initio calculation of anisotropic magnetic properties of complexes. I. Unique definition of pseudospin Hamiltonians and their derivation
Authors: Chibotaru L. F. , Ungur L.
Published: August 2012

A methodology for the rigorous nonperturbative derivation of magnetic pseudospin Hamiltonians of mononuclear complexes and fragments based on ab initio calculations of their electronic structure is described. It is supposed that the spin-orbit coupling and other relativistic effects are already taken fully into account at the stage of quantum chemistry calculations of complexes. The methodology is based on the establishment of the correspondence between the ab initio wave functions of the chosen manifold of multielectronic states and the pseudospin eigenfunctions, which allows to define the pseudospin Hamiltonians in the unique way. Working expressions are derived for the pseudospin Zeeman and zero-field splitting Hamiltonian corresponding to arbitrary pseudospins. The proposed calculation methodology, already implemented in the SINGLE_ANISO module of the MOLCAS-7.6 quantum chemistry package, is applied for a first-principles evaluation of pseudospin Hamiltonians of several complexes exhibiting weak, moderate, and very strong spin-orbit coupling effects.
Drift and ion acoustic wave driven vortices with superthermal electrons
Authors: Ali Shan S. , Haque Q.
Published: August 2012

Linear and nonlinear analysis of coupled drift and acoustic mode is presented in an inhomogeneous electron-ion plasma with κ-distributed electrons. A linear dispersion relation is found which shows that the phase speed of both the drift wave and the ion acoustic wave decreases in the presence of superthermal electrons. Several limiting cases are also discussed. In the nonlinear regime, stationary solutions in the form of dipolar and monopolar vortices are obtained. It is shown that the condition for the boundedness of the solution implies that the speed of drift wave driven vortices reduces with increase in superthermality effect. Ignoring density inhomogeniety, it is investigated that the lower and upper limits on the speed of the ion acoustic driven vortices spread with the inclusion of high energy electrons. The importance of results with reference to space plasmas is also pointed out.
Measurements of ion cyclotron range of frequencies mode converted wave intensity with phase contrast imaging in Alcator C-Mod and comparison with full-wave simulations
Authors: Tsujii N. , Porkolab M. , Bonoli P. T. , Lin Y. , Wright J. C. , Wukitch S. J. , Jaeger E. F. , Green D. L. , Harvey R. W.
Published: August 2012

Radio frequency waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat tokamak plasmas. In ICRF heating schemes involving multiple ion species, the launched fast waves convert to ion cyclotron waves or ion Bernstein waves at the two-ion hybrid resonances. Mode converted waves are of interest as actuators to optimise plasma performance through current drive and flow drive. In order to describe these processes accurately in a realistic tokamak geometry, numerical simulations are essential, and it is important that these codes be validated against experiment. In this study, the mode converted waves were measured using a phase contrast imaging technique in D-H and D-3He plasmas. The measured mode converted wave intensity in the D-3He mode conversion regime was found to be a factor of ∼50 weaker than the full-wave predictions. The discrepancy was reduced in the hydrogen minority heating regime, where mode conversion is weaker.
Secondary phase Cu2SnSe3 vs. kesterite Cu2ZnSnSe4: Similarities and differences in lattice vibration modes
Authors: Beigom Mortazavi Amiri Narjes , Postnikov Andrei
Published: August 2012

The crystal structure of monoclinic semiconductor Cu2SnSe3 is optimized, in a first-principles local density approximation calculation by Siesta method, to be found in good agreement with available experimental data, on which base zone-center transversal phonon modes are further calculated. The comparison with a similar calculation for kesterite-phase Cu2ZnSnSe4 helps to identify vibration modes promising to serve as fingerprints for discrimination of these two materials from their lattice-dynamical properties. Moreover, a full analysis of vibration modes is done, which emphasizes an importance of structural motives present in Cu2SnSe3 but absent in kesterite, namely continuous planar chains and stripes of like cations/anions, for the manifestation of structure-specific vibration lines.