bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced Aircraft Flight Performance
Authors: Filippone Antonio
Published: January 2013

This book discusses aircraft flight performance, focusing on commercial aircraft but also considering examples of high-performance military aircraft. The framework is a multidisciplinary engineering analysis, fully supported by flight simulation, with software validation at several levels. The book covers topics such as geometrical configurations, configuration aerodynamics and determination of aerodynamic derivatives, weight engineering, propulsion systems (gas turbine engines and propellers), aircraft trim, flight envelopes, mission analysis, trajectory optimisation, aircraft noise, noise trajectories and analysis of environmental performance. A unique feature of this book is the discussion and analysis of the environmental performance of the aircraft, focusing on topics such as aircraft noise and carbon dioxide emissions.
Light and Photosynthesis in Aquatic Ecosystems
Authors: Kirk John T. O.
Published: January 2013

Beginning systematically with the fundamentals, the fully-updated third edition of this popular graduate textbook provides an understanding of all the essential elements of marine optics. It explains the key role of light as a major factor in determining the operation and biological composition of aquatic ecosystems, and its scope ranges from the physics of light transmission within water, through the biochemistry and physiology of aquatic photosynthesis, to the ecological relationships that depend on the underwater light climate. This book also provides a valuable introduction to the remote sensing of the ocean from space, which is now recognized to be of great environmental significance due to its direct relevance to global warming. An important resource for graduate courses on marine optics, aquatic photosynthesis, or ocean remote sensing; and for aquatic scientists, both oceanographers and limnologists.
Waves of War
Authors: Wimmer Andreas
Published: January 2013

Why did the nation-state emerge and proliferate across the globe? How is this process related to the wars fought in the modern era? Analyzing datasets that cover the entire world over long stretches of time, Andreas Wimmer focuses on changing configurations of power and legitimacy to answer these questions. The nationalist ideal of self-rule gradually diffused over the world and delegitimized empire after empire. Nationalists created nation-states wherever the power configuration favored them, often at the end of prolonged wars of secession. The elites of many of these new states were institutionally too weak for nation-building and favored their own ethnic communities. Ethnic rebels challenged such exclusionary power structures in violation of the principles of self-rule, and neighboring governments sometimes intervened into these struggles over the state. Waves of War demonstrates why nation-state formation and ethnic politics are crucial to understand the civil and international wars of the past 200 years.
Black Morocco
Authors: El Hamel Chouki
Published: January 2013

Black Morocco: A History of Slavery, Race, and Islam chronicles the experiences, identity and achievements of enslaved black people in Morocco from the sixteenth century to the beginning of the twentieth century. Chouki El Hamel argues that we cannot rely solely on Islamic ideology as the key to explain social relations and particularly the history of black slavery in the Muslim world, for this viewpoint yields an inaccurate historical record of the people, institutions and social practices of slavery in Northwest Africa. El Hamel focuses on black Moroccans' collective experience beginning with their enslavement to serve as the loyal army of the Sultan Isma'il. By the time the Sultan died in 1727, they had become a political force, making and unmaking rulers well into the nineteenth century. The emphasis on the political history of the black army is augmented by a close examination of the continuity of black Moroccan identity through the musical and cultural practices of the Gnawa.
A Double Hall Algebra Approach to Affine Quantum Schur–Weyl Theory
Authors: Deng Bangming , Du Jie , Fu Qiang
Published: January 2013

The theory of Schur–Weyl duality has had a profound influence over many areas of algebra and combinatorics. This text is original in two respects: it discusses affine q-Schur algebras and presents an algebraic, as opposed to geometric, approach to affine quantum Schur–Weyl theory. To begin, various algebraic structures are discussed, including double Ringel–Hall algebras of cyclic quivers and their quantum loop algebra interpretation. The rest of the book investigates the affine quantum Schur–Weyl duality on three levels. This includes the affine quantum Schur–Weyl reciprocity, the bridging role of affine q-Schur algebras between representations of the quantum loop algebras and those of the corresponding affine Hecke algebras, presentation of affine quantum Schur algebras and the realisation conjecture for the double Ringel–Hall algebra with a proof of the classical case. This text is ideal for researchers in algebra and graduate students who want to master Ringel–Hall algebras and Schur–Weyl duality.
The Poetics of Sovereignty in American Literature, 1885–1910
Authors: Hebard Andrew
Published: January 2013

During the Progressive Era, the United States regularly suspended its own laws to regulate racialized populations. Judges and administrators relied on the rhetoric of sovereignty to justify such legal practices, while in American popular culture, sovereignty helped authors coin tropes that have become synonymous with American exceptionalism today. In this book, Andrew Hebard challenges the notion of sovereignty as a 'state of exception' in American jurisprudence and literature at the turn of the twentieth century. Hebard explores how literary trends such as romance and realism helped conventionalize, and thereby sanction, the federal government's use of sovereignty in a range of foreign and domestic policy matters, including the regulation of overseas colonies, immigration, Native American lands, and extra-legal violence in the American South. Weaving historiography with close readings of Mark Twain, the Western, and other hallmarks of Progressive Era literature, Hebard's study offers a new cultural context for understanding the legal history of race relations in the United States.
Coming of Age in Nineteenth-Century India
Authors: Lal Ruby
Published: January 2013

In this engaging and eloquent history, Ruby Lal traces the becoming of nineteenth-century Indian women through a critique of narratives of linear transition from girlhood to womanhood. In the north Indian patriarchal environment, women's lives were dominated by the expectations of the male universal, articulated most clearly in household chores and domestic duties. The author argues that girls and women in the early nineteenth century experienced freedoms, eroticism, adventurousness and playfulness, even within restrictive circumstances. Although women in the colonial world of the later nineteenth century remained agential figures, their activities came to be constrained by more firmly entrenched domestic norms. Lal skillfully marks the subtle and complex alterations in the multifaceted female subject in a variety of nineteenth-century discourses, elaborated in four different sites - forest, school, household, and rooftops.
British Writers and MI5 Surveillance, 1930–1960
Authors: Smith James
Published: January 2013

Britain's domestic intelligence agencies maintained secret records on many left-wing writers after the First World War. Drawing on recently declassified material from 1930 to 1960, this revealing study examines how leading figures in Britain's literary scene fell under MI5 and Special Branch surveillance, and the surprising extent to which writers became willing participants in the world of covert intelligence and propaganda. Chapters devoted to W. H. Auden and his associates, theatre pioneers Ewan MacColl and Joan Littlewood, George Orwell and others describe methods used by MI5 to gather information through and about the cultural world. The book also investigates how these covert agencies assessed the political influence of such writers, providing scholars and students of twentieth-century British literature with an unprecedented account of clandestine operations in popular culture.
Nietzsche and Buddhist Philosophy
Authors: Panaïoti Antoine
Published: January 2013

Nietzsche once proclaimed himself the 'Buddha of Europe', and throughout his life Buddhism held enormous interest for him. While he followed Buddhist thinking in demolishing what he regarded as the two-headed delusion of Being and Self, he saw himself as advocating a response to the ensuing nihilist crisis that was diametrically opposed to that of his Indian counterpart. In this book Antoine Panaïoti explores the deep and complex relations between Nietzsche's views and Buddhist philosophy. He discusses the psychological models and theories which underlie their supposedly opposing ethics of 'great health' and explodes the apparent dichotomy between Nietzsche's Dionysian life-affirmation and Buddhist life-negation, arguing for a novel, hybrid response to the challenge of formulating a tenable post-nihilist ethics. His book will interest students and scholars of Nietzsche's philosophy, Buddhist thought and the metaphysical, existential and ethical issues that emerge with the demise of theism.
Vectors, Pure and Applied
Authors: Körner T. W.
Published: January 2013

Many books in linear algebra focus purely on getting students through exams, but this text explains both the how and the why of linear algebra and enables students to begin thinking like mathematicians. The author demonstrates how different topics (geometry, abstract algebra, numerical analysis, physics) make use of vectors in different ways and how these ways are connected, preparing students for further work in these areas. The book is packed with hundreds of exercises ranging from the routine to the challenging. Sketch solutions of the easier exercises are available online.
Australia 1942
Authors: Beazley Kim
Published: January 2013

In 1942, the shadow of modern war reached Australia's shores for the first time. In this compelling volume, leading historians explore why 1942 was such a pivotal year in Australia's history and explain how the nation confronted some of its greatest challenges. This broad ranging study covers key issues from political, economic and home front reform to the establishment of a new partnership with the United States; the role of the Air Force and the Navy; the bombing of Darwin; as well as the battles of Kokoda, Milne Bay, the Beachheads and Guadalcanal. Australia 1942 provides a unique and in-depth exploration of the controversy surrounding the potential for invasion. Japanese and Australian historians offer perspectives on Japanese military intentions and strategies towards Australia and the South Pacific. Generously illustrated, it is essential reading for anyone interested in one of Australia's most decisive and critical years.
Experimental study of nanofiber production through forcespinning
Authors: Padron Simon , Fuentes Arturo , Caruntu Dumitru , Lozano Karen
Published: January 2013

A newly developed method of producing nanofibers, called forcespinning, has proven to be a viable alternative to mass produce nanofibers. Unlike electrospinning, the most common method currently being employed (which draws fibers through the use of electrostatic force), forcespinning utilizes centrifugal forces which allow for a host of new materials to be processed into nanofibers (given that electric fields are not required) while also providing a significant increase in yield and ease of production. This work presents a detailed explanation of the fiber formation process. The study is conducted using high speed photography to capture the jet initiation process at the orifice and to track the trajectories of the resulting jets. The effects that influential controllable parameters have on the fiber trajectories and final fiber diameters are presented. The forcespinning controllable parameters include the spinneret angular velocity and aspect ratio, orifice radius and orientation, fluid viscoelasticity and surface tension, fluid fill level, solvent evaporation rate, temperature, and distance of spinneret orifice to collector.
Collisional and collective effects in two dimensional model for fast-electron transport in refluxing regime
Authors: Volpe L. , Batani D. , Morace A. , Santos J. J.
Published: January 2013

The relativistic laser-driven electron transport in partially or fully ionized matter has been investigated in many recent experiments. The high laser intensity achievable today (up to 1020 W/cm2) allows to generate electron current density above 1011 A/cm2. In this regime, electromagnetic effects start to be dominant over collisional ones. In this context, we have developed a simple 2D model for the fast electron transport accounting for (1) electric effects on the electron penetration range and (2) the electron refluxing in thin foils. We compare our model with those existing in literature and with some recent experimental results on fast electron transport in matter. The model predicts a maximum value for the electron penetration range in the region where the collisional and the resistive effects are comparable.
Bound state solutions of the Dirac equation for the trigonometric and hyperbolic Scarf-Grosche potentials using the Nikiforov-Uvarov method
Authors: Yahya W. A. , Oyewumi K. J.
Published: January 2013

The relativistic Dirac equation with equal (trigonometric and hyperbolic) Scarf-Grosche scalar and vector potentials in 3 + 1 and 1 + 1 space-time dimension are solved by using the Nikiforov-Uvarov method. The exact energy equations and the spinor wave functions are obtained for these sets of potentials. The bound states energy are calculated numerically. Also, with appropriate transformations, solutions of the fourth potential V4 can be deduced from the solutions of the third potential V3.
Rotational excitation of HDO and D2O by H2: Experimental and theoretical differential cross-sections
Authors: Sarma Gautam , Yang Chung-Hsin , Saha Ashim Kumar , Parker David H. , Wiesenfeld Laurent
Published: January 2013

We present state-to-state differential cross sections (DCSs) for rotationally inelastic scattering of HDO by normal- and para-H2 at collision energies of 580 cm−1 and 440 cm−1. (2+1) resonance enhanced multiphoton ionization is used to detect rotationally cold HDO molecules before collision and as scattering products, which occupy higher rotational states due to collision with H2. Relative integral cross sections of HDO are obtained by integrating its DCSs measured at the same experimental conditions. Experimental and theoretical DCSs of HDO scattered by normal- and para-H2 are in good agreement in 30°–180° range of scattering angles. This partial agreement shows the accuracy of the recently tested potential of H2O–H2, but now by using a completely different set of rotational transitions that are (unlike in H2O), not forbidden by nuclear spin restrictions. Similar results are presented for D2O scattered by normal-H2 at collision energy of 584 cm−1. The agreement between experiment and theory is, however, less good for forward scattering of HDO/D2O. A critical analysis of this discrepancy is presented.
Ray chaos in an architectural acoustic semi-stadium system
Authors: Yu Xiaojian , Zhang Yu
Published: January 2013

The semi-stadium system is composed of a semicircular cap and a rectilinear platform. In this study, a dynamic model of the side, position, and angle variables is applied to investigate the acoustic ray chaos of the architectural semi-stadium system. The Lyapunov exponent is calculated in order to quantitatively describe ray instability. The model can be reduced to the semi-circular and rectilinear platform systems when the rectilinear length is sufficiently small and large. The quasi-rectilinear platform and the semicircular systems both produce regular trajectories with the maximal Lyapunov exponent approaching zero. Ray localizations, such as flutter-echo and sound focusing, are found in these two systems. However, the semi-stadium system produces chaotic ray behaviors with positive Lyapunov exponents and reduces ray localizations. Furthermore, as the rectilinear length increases, the scaling laws of the Lyapunov exponent of the semi-stadium system are revealed and compared with those of the stadium system. The results suggest the potential application of the proposed model to simulate chaotic dynamics of acoustic ray in architectural enclosed systems.
Benchmarking density-functional theory calculations of NMR shielding constants and spin–rotation constants using accurate coupled-cluster calculations
Authors: Teale Andrew M. , Lutnæs Ola B. , Helgaker Trygve , Tozer David J. , Gauss Jürgen
Published: January 2013

Accurate sets of benchmark nuclear-magnetic-resonance shielding constants and spin–rotation constants are calculated using coupled-cluster singles–doubles (CCSD) theory and coupled-cluster singles–doubles–perturbative-triples [CCSD(T)] theory, in a variety of basis sets consisting of (rotational) London atomic orbitals. The accuracy of the calculated coupled-cluster constants is established by a careful comparison with experimental data, taking into account zero-point vibrational corrections. Coupled-cluster basis-set convergence is analyzed and extrapolation techniques are employed to estimate basis-set-limit quantities, thereby establishing an accurate benchmark data set. Together with the set provided for rotational g-tensors and magnetizabilities in our previous work [O. B. Lutnæs, A. M. Teale, T. Helgaker, D. J. Tozer, K. Ruud, and J. Gauss, J. Chem. Phys. 131, 144104 (2009)]10.1063/1.3242081, it provides a substantial source of consistently calculated high-accuracy data on second-order magnetic response properties. The utility of this benchmark data set is demonstrated by examining a wide variety of Kohn–Sham exchange–correlation functionals for the calculation of these properties. None of the existing approximate functionals provide an accuracy competitive with that provided by CCSD or CCSD(T) theory. The need for a careful consideration of vibrational effects is clearly illustrated. Finally, the pure coupled-cluster results are compared with the results of Kohn–Sham calculations constrained to give the same electronic density. Routes to future improvements are discussed in light of this comparison.
Dopant mapping in highly p-doped silicon by micro-Raman spectroscopy at various injection levels
Authors: Kunz T. , Hessmann M. T. , Seren S. , Meidel B. , Terheiden B. , Brabec C. J.
Published: January 2013

Micro-Raman spectroscopy has been used to investigate the acceptor distribution in highly p-doped silicon. As an example, the dopant distribution in crystalline thin-film layers, as developed for solar cells, was mapped. The method is based on the analysis of the Fano-type Raman peak shape which is caused by free charge carriers. For calibration of the Raman acceptor measurements (excitation at a wavelength of 532 nm), we used mono-crystalline reference samples whose acceptor concentration was determined by electrochemical capacitance voltage. We find a significant influence of light induced free charge carriers on the peak shape which results from typical Raman excitation. Thus, the selection of a suitable intensity is important to avoid a too low signal-to-noise ratio on the one hand and systematic errors due to light induced carriers on the other hand. Different evaluation methods, i.e., peak asymmetry versus peak width analysis, are compared in respect to interference caused by random noise of the spectra or else by internal stress in the sample. While the width analysis method is more robust to a low signal-to-noise ratio, the symmetry analysis is more reliable in case of high intrinsic stress.
A new method for the synthesis of epitaxial layers of silicon carbide on silicon owing to formation of dilatation dipoles
Authors: Kukushkin S. A. , Osipov A. V.
Published: January 2013

A new method is developed for the solid-phase synthesis of epitaxial layers when the substrate itself is involved into a chemical reaction and the reaction product grows in the interior of substrate layer. It opens up new possibilities for the relaxation of the elastic energy due to attraction of point defects formed during the chemical reaction in anisotropic media. In the same time, the attracting point dilatation centers compose relatively stable formations—dilatation dipoles, named by analogy with electric dipoles, providing significant reduction of the total elastic energy. The correspondent theory of interaction of point dilatation centers in anisotropic crystals is developed. It is eliminated that the most advantageous location of the dipoles is the direction (111) in crystals with cubic symmetry. In order to confirm the theory, the single-crystal silicon carbide films with the thickness up to 200 nm have been grown on silicon (111) substrates owing to the chemical reaction with carbon monoxide. Grown high-quality single-crystal silicon carbide films do not contain misfit dislocations despite the huge lattice mismatch value of ∼20%. Also the possibility of growing of thick wide-gap semiconductor films on such templates SiC/Si(111) and, accordingly, its integration into silicon electronics, is demonstrated. In particular, a working LED structure based on gallium nitride has been produced. Finally, the thermodynamic theory of new phase nucleation due to a chemical reaction has been developed and it was shown that in the case under consideration the chemical equilibrium constant generalizes the concentration of adatoms exploited in a one-component nucleation theory.
Protein structure prediction using global optimization by basin-hopping with NMR shift restraints
Authors: Hoffmann Falk , Strodel Birgit
Published: January 2013

Computational methods that utilize chemical shifts to produce protein structures at atomic resolution have recently been introduced. In the current work, we exploit chemical shifts by combining the basin-hopping approach to global optimization with chemical shift restraints using a penalty function. For three peptides, we demonstrate that this approach allows us to find near-native structures from fully extended structures within 10 000 basin-hopping steps. The effect of adding chemical shift restraints is that the α and β secondary structure elements form within 1000 basin-hopping steps, after which the orientation of the secondary structure elements, which produces the tertiary contacts, is driven by the underlying protein force field. We further show that our chemical shift-restraint BH approach also works for incomplete chemical shift assignments, where the information from only one chemical shift type is considered. For the proper implementation of chemical shift restraints in the basin-hopping approach, we determined the optimal weight of the chemical shift penalty energy with respect to the CHARMM force field in conjunction with the FACTS solvation model employed in this study. In order to speed up the local energy minimization procedure, we developed a function, which continuously decreases the width of the chemical shift penalty function as the minimization progresses. We conclude that the basin-hopping approach with chemical shift restraints is a promising method for protein structure prediction.
Modified embedded-atom method interatomic potential and interfacial thermal conductance of Si-Cu systems: A molecular dynamics study
Authors: Abs da Cruz Carolina , Chantrenne Patrice , Gomes de Aguiar Veiga Roberto , Perez Michel , Kleber Xavier
Published: January 2013

Thermal contact conductance of metal-dielectric systems is a key parameter that has to be taken into account for the design and reliability of nanostructured microelectronic systems. This paper aims to predict this value for Si-Cu interfaces using molecular dynamics simulations. To achieve this goal, a modified embedded atom method interatomic potential for Si-Cu system has been set based upon previous MEAM potentials for pure Cu and pure Si. The Si-Cu cross potential is determined by fitting key properties of the alloy to results obtained by ab initio calculations. It has been further evaluated by comparing the structure and energies of Cu dimmers in bulk Si and CumSin clusters to ab initio calculations. The comparison between MD and ab initio calculation also concerns the energy barrier of Cu migration along the (110) channel in bulk Si. Using this interatomic potential, non equilibrium molecular dynamics has been performed to calculate the thermal contact conductance of a Si-Cu interface at different temperature level. The results obtained are in line with previous experimental results for different kind of interfaces. This confirms that the temperature variation of the thermal conductance might not find its origin in the electron-phonon interactions at the interface nor in the quantification of the energy of the vibration modes. The diffuse mismatch model is also used in order to discuss these results.
Annealing effect in boron-induced interface charge traps in Si/SiO2 systems
Authors: Park H. , Choi B. , Steigerwald A. , Varga K. , Tolk N.
Published: January 2013

Boron-induced charge traps near the interface of Si/SiO2 systems are investigated by time-dependent second harmonic generation (TD-SHG), a technique which is sensitive to interface electric fields. Using this approach, we monitored the modification of the charge state of the traps after systematic annealing in H2, Ar, and 1 mTorr vacuum at the temperatures of about 200 °C and 800 °C, and in 100 °C deionized-water. The initial decreasing TD-SHG signals were found to be significantly diminished upon annealing in the non-oxygen environments. We attribute the observed TD-SHG experimental results to neutralization of the built-in boron-induced charge traps and discuss possible mechanisms.
Higher order geometric flows on three-dimensional locally homogeneous spaces
Authors: Das Sanjit , Prabhu Kartik , Kar Sayan
Published: January 2013

We analyse second order (in Riemann curvature) geometric flows (un-normalised) on locally homogeneous three manifolds and look for specific features through the solutions (analytic wherever possible, otherwise numerical) of the evolution equations. Several novelties appear in the context of scale factor evolution, fixed curves, phase portraits, approach to singular metrics, isotropization, and curvature scalar evolution. The distinguishing features linked to the presence of the second order term in the flow equation are pointed out. Throughout the article, we compare the results obtained, with the corresponding results for un-normalized Ricci flows.
Multi-dimensional admittance spectroscopy
Authors: Wieland K. , Vasko A. , Karpov V. G.
Published: January 2013

We introduce the concept of multi-dimensional admittance spectroscopy capable of characterizing thin-film diode structures in both the (standard) transversal and lateral directions. This extends the capabilities of standard admittance spectroscopy based on the model of leaky capacitor with area defined by the metal contacts. In our approach, the ac signal spreads in the lateral directions far beyond the contact area. The spreading range defines the area of the effective capacitor determining the measured capacitance and conductance. It depends on the ac signal frequency, dc bias, and various structure parameters. A phenomenological description of these dependencies here is verified numerically using our original software to model the distributed admittance via finite element circuits. We analyze the case of photovoltaic devices and show how the multi-dimensional admittance spectroscopy is sensitive to lateral nonuniformity of the system, particularly to the presence of shunts and weak diodes and their location. In addition, the proposed characterization provides information about the system lump parameters, such as sheet resistance, shunt resistance, and open circuit voltage.
Experimental and theoretical investigation of the electronic structure of Cu2O and CuO thin films on Cu(110) using x-ray photoelectron and absorption spectroscopy
Authors: Jiang Peng , Prendergast David , Borondics Ferenc , Porsgaard Soeren , Giovanetti Lisandro , Pach Elzbieta , Newberg John , Bluhm Hendrik , Besenbacher Flemming , Salmeron Miquel
Published: January 2013

The electronic structure of Cu2O and CuO thin films grown on Cu(110) was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The various oxidation states, Cu0, Cu+, and Cu2+, were unambiguously identified and characterized from their XPS and XAS spectra. We show that a clean and stoichiometric surface of CuO requires special environmental conditions to prevent loss of oxygen and contamination by background water. First-principles density functional theory XAS simulations of the oxygen K edge provide understanding of the core to valence transitions in Cu+ and Cu2+. A novel method to reference x-ray absorption energies based on the energies of isolated atoms is presented.
Trapped charge dynamics in InAs nanowires
Authors: Holloway Gregory W. , Song Yipu , Haapamaki Chris M. , LaPierre Ray R. , Baugh Jonathan
Published: January 2013

We study random telegraph noise in the conductance of InAs nanowire field-effect transistors due to single electron trapping in defects. The electron capture and emission times are measured as functions of temperature and gate voltage for individual traps, and are consistent with traps residing in the few-nanometer-thick native oxide, with a Coulomb barrier to trapping. These results suggest that oxide removal from the nanowire surface, with proper passivation to prevent regrowth, should lead to the reduction or elimination of random telegraph noise, an important obstacle for sensitive experiments at the single electron level.
How well can polarization models of pairwise nonadditive forces describe liquid water?
Authors: Akin-Ojo Omololu , Szalewicz Krzysztof
Published: January 2013

Properties of liquid water have been computed using a near-exact rigid-monomer two-body (pairwise-additive) force field and the same field supplemented by a simple, non-empirical polarization model of pairwise nonadditive many-body forces. The inclusion of nonadditive polarization forces leads to a dramatic decrease, sometimes by an order of magnitude, of the deviations of water properties computed using classical molecular dynamics from experiment results. The remaining deviations are typically of the order of 10%. The model correctly predicts the temperature dependence of the properties except for the density of supercooled water. This good performance is achieved despite the known failure of the polarization model in reproducing trimer nonadditive interaction energies, confirmed here by showing that for a random set of trimers with all O-O separations smaller than 3.4 Å, selected from simulation snapshots, the average error of the model relative to accurate ab initio values is 71%. However, the errors gradually decrease for larger trimers, more abundant in liquid, and one can estimate that the polarization model should reproduce the exact liquid interaction energy to within about 6%. Although this accuracy is consistent with the observed performance of the polarization model, it does not explain the dramatic improvements over the two-body model. These improvements are due to the restructuring of liquid into tetrahedral arrangements instigated by the nonadditive polarization forces. The deviations of our predictions from experiments are generally also consistent with the estimated contributions from leading neglected effects other than the exchange nonadditive forces: the monomer flexibility and quantum nuclear motion effects.
Remarks on the regularity criteria of generalized MHD and Navier-Stokes systems
Authors: Yamazaki Kazuo
Published: January 2013

We study the regularity criteria of the three dimensional generalized magnetohydrodynamics (MHD) and Navier-Stokes systems. In particular, we show that the regularity criteria of the generalized MHD system may be reduced to depend only on two diagonal entries of the Jacobian matrix of the velocity vector field or one vorticity component and one entry of the Jacobian matrix of the velocity vector field.
Dislocation line charge screening within n-type gallium nitride
Authors: Baghani Erfan , O'Leary Stephen K.
Published: January 2013

A revised electrostatic theory for the charged dislocation lines within n-type GaN is formulated, this formalism allowing for the screening of the charge trapped along the dislocation lines, by both free carriers and a partial ionization of the impurities within the space-charge region surrounding the dislocation lines. This goes beyond the abrupt space-charge region assumption of the Read model [W. T. Read, Jr., Philos. Mag. 45, 775 (1954)], where the only screening mechanism considered is a complete ionization of bulk donor atoms within the Read radius. In addition to determining the spatial distribution of the charge enveloping charged dislocation lines, this procedure also provides a solution to the electrostatic potential surrounding the dislocation lines. An iterative, self-consistent numerical approach to the solution of this problem is developed for the purposes of this analysis. A special limit for which the results of this model reduce to that of Read is indicated. The results obtained from our analysis are found to be in satisfactory agreement with experimental results from the literature.
Coherence decay measurement of v = 2 vibrons in solid parahydrogen
Authors: Kuma Susumu , Miyamoto Yuki , Nakajima Kyo , Fukumi Atsushi , Kawaguchi Kentarou , Nakano Itsuo , Sasao Noboru , Tanaka Minoru , Tang Jian , Taniguchi Takashi , Uetake Satoshi , Wakabayashi Tomonari , Yoshimi Akihiro , Yoshimura Motohiko
Published: January 2013

The coherence decay of the v = 2 vibrational state (vibrons) of solid parahydrogen was measured via time-resolved coherent anti-Stokes Raman spectroscopy. We found that the decay curve has a non-exponential time profile in the time scale of 200 ns at a low temperature below 5 K and a low orthohydrogen impurity concentration (∼0.01%). This behavior, as also observed in the case of the v = 1 vibrons, represents a signature of band structure of the v = 2 state in the solid phase. The maximum coherence decay time of 50 ns in an exponential part was achieved, which shows excellence of the v = 2 state for coherent processes. We also found that finite temperatures, orthohydrogen impurities, and other structural inhomogeneity accelerate the decay, hiding the non-exponential feature of the vibron band.
Direct growth of graphitic carbon on Si(111)
Authors: Thanh Trung Pham , Joucken Frédéric , Campos-Delgado Jessica , Raskin Jean-Pierre , Hackens Benoît , Sporken Robert
Published: January 2013

Appropriate conditions for direct growth of graphitic films on Si(111) 7 × 7 are investigated. The structural and electronic properties of the samples are studied by Auger electron spectroscopy, X-ray photoemission spectroscopy, low energy electron diffraction (LEED), Raman spectroscopy, and scanning tunneling microscopy (STM). In particular, we present STM images of a carbon honeycomb lattice grown directly on Si(111). Our results demonstrate that the quality of graphene films formed depends not only on the substrate temperature but also on the carbon buffer layer at the interface. This method might be very promising for graphene-based electronics and its integration into the silicon technology.
Non-Hermitian wave packet approximation of Bloch optical equations
Authors: Charron Eric , Sukharev Maxim
Published: January 2013

We introduce a non-Hermitian approximation of Bloch optical equations. This approximation provides a complete description of the excitation, relaxation, and decoherence dynamics of ensembles of coupled quantum systems in weak laser fields, taking into account collective effects and dephasing. In the proposed method, one propagates the wave function of the system instead of a complete density matrix. Relaxation and dephasing are taken into account via automatically adjusted time-dependent gain and decay rates. As an application, we compute the numerical wave packet solution of a time-dependent non-Hermitian Schrödinger equation describing the interaction of electromagnetic radiation with a quantum nano-structure, and compare the calculated transmission, reflection, and absorption spectra with those obtained from the numerical solution of the Liouville-von Neumann equation. It is shown that the proposed wave packet scheme is significantly faster than the propagation of the full density matrix while maintaining small error. We provide the key ingredients for easy-to-use implementation of the proposed scheme and identify the limits and error scaling of this approximation.
Dynamics in molecular and molecular-ionic crystals: A combined experimental and molecular simulation study of reorientational motions in benzene, pyridinium iodide, and pyridinium nitrate
Authors: Pajzderska A. , Gonzalez M. A. , Wąsicki J.
Published: January 2013

Molecular dynamics (MD) simulations for crystalline benzene (C6H6), pyridinium iodide [C5NH6]+I−, and pyridinium nitrate [C5NH6]+NO3− have been performed as a function of temperature and pressure. Despite the similar shape of the benzene molecule and the pyridinium cation, the experimental and simulated data have showed clear differences in their dynamics. Therefore, the rotational dynamics have been explored in detail by comparing thoroughly the existing experimental results together with new quasielastic neutron scattering (QENS) data obtained for (PyH)NO3 and molecular dynamics simulations. The correlation times, activation energy, geometry of motion of benzene molecule and pyridinium cation, isothermal compressibility, and activation volume obtained from the simulations are compared with the experimental results obtained by nuclear magnetic resonance and QENS methods. MD simulations have also revealed that reorientation of the pyridinium cation in pyridinium nitrate between two inequivalent positions is strongly affected by the hydrogen bond N–H⋅⋅⋅O between the cation and the anion and the influence of temperature on strength of the hydrogen bond is much more important than that of the pressure.
Simulation study of the polymer translocation free energy barrier
Authors: Polson James M. , Hassanabad Mostafa Fatehi , McCaffrey Anthony
Published: January 2013

Monte Carlo simulations are used investigate the properties of the free energy barrier associated with polymer translocation through a nanopore. We employ a multiple-histogram method to calculate the variation of the free energy with Q, a coordinate used to quantify the degree of translocation. The system is modeled as a flexible hard-sphere chain that translocates through a cylindrical hole in a hard flat wall. Some calculations were carried out for nanopores connected to a spherical cavity at one or both ends. Attractive monomer-nanopore interactions and a linear driving force through the nanopore were also included in some calculations. The properties of the free energy functions for short polymers were studied upon variation in all of the key system parameters, including polymer length, the nanopore dimensions, the strengths of the attractive, and driving force interactions. The results were analyzed using a simple theoretical model, whose only free parameter is the confinement free energy per link for monomers inside the nanopore. Generally, the results are in excellent quantitative agreement with the model. One notable feature of the free energy functions is the presence of oscillations whose amplitude increases with decreasing pore radius. These oscillations are due to the nature of the variation with Q of the orientational entropy of bonds at the two edges of the pore. A simple model was constructed to account for dependence of the oscillation amplitude and period on the system parameters. We propose that the theoretical models developed here can be used to make quantitatively accurate predictions of translocation free energy functions for very long polymers using simulation data acquired for short polymers.
Fast-SAXS-pro: A unified approach to computing SAXS profiles of DNA, RNA, protein, and their complexes
Authors: Ravikumar Krishnakumar M. , Huang Wei , Yang Sichun
Published: January 2013

A generalized method, termed Fast-SAXS-pro, for computing small angle x-ray scattering (SAXS) profiles of proteins, nucleic acids, and their complexes is presented. First, effective coarse-grained structure factors of DNA nucleotides are derived using a simplified two-particle-per-nucleotide representation. Second, SAXS data of a 18-bp double-stranded DNA are measured and used for the calibration of the scattering contribution from excess electron density in the DNA solvation layer. Additional test on a 25-bp DNA duplex validates this SAXS computational method and suggests that DNA has a different contribution from its hydration surface to the total scattering compared to RNA and protein. To account for such a difference, a sigmoidal function is implemented for the treatment of non-uniform electron density across the surface of a protein/nucleic-acid complex. This treatment allows differential scattering from the solvation layer surrounding protein/nucleic-acid complexes. Finally, the applications of this Fast-SAXS-pro method are demonstrated for protein/DNA and protein/RNA complexes.
Directed motion of periodically driven molecular motors: A graph-theoretical approach
Authors: Akimov Alexey V. , Mandal Dibyendu , Chernyak Vladimir Y. , Sinitsyn Nikolai A.
Published: January 2013

We propose a numerical algorithm for calculation of quantized directed motion of a stochastic system of interacting particles induced by periodic changes of control parameters on the graph of microstates. As a main application, we consider models of catenane molecular motors, which demonstrated the possibility of a similar control of directed motion of molecular components. We show that our algorithm allows one to calculate the motion of a system in the space of its microstates even when the considered phase space is combinatorially large (∼1 × 106 microscopic states). Several general observations are made about the structure of the phase diagram of the systems studied, which may be used for rational design and efficient control of new generations of molecular motors.
Tuning the magnetostructural phase transition in FeRh nanocomposites
Authors: Barua Radhika , Jiang Xiujuan , Jimenez-Villacorta Felix , Shield J. E. , Heiman D. , Lewis L. H.
Published: January 2013

Effects of nanostructuring on the magnetostructural response of the near-equiatomic FeRh phase were investigated in nanocomposite materials synthesized by rapid solidification and subsequent annealing of an alloy of nominal atomic composition (FeRh)5Cu95. Transmission electron microscopy studies confirm attainment of a phase-separated system of nanoscaled (∼10–15 nm diameter) precipitates, consistent with FeRh embedded in a Cu matrix. These nanoprecipitates are crystallographically aligned with the coarse-grained Cu matrix and possess an L10-type (CuAu 1) structure, in contrast to the B2 (CsCl)-type structure of bulk FeRh. It is proposed that the face-centered cubic crystal structure of the Cu matrix serves as a template for the formation and stabilization of the L10 structure in the FeRh nanoprecipitates. Magnetic measurements highlight the existence of multiple magnetic phases in the material exhibiting spin-glass (T ≤ 15 K), ferromagnetic and paramagnetic (T > 20 K) behavior. A thermally hysteretic magnetic transition, remarkably similar to the magnetostructural transition of bulk CsCl-type FeRh reported at Tt = 370 K, is observed in the nanostructured material at 130 K. This result not only emphasizes the sensitivity of the magnetic and structural properties of FeRh to changes in microstructural scale, but also highlights the potential for tailoring magnetostructural transitions in functional materials systems via nanostructuring.
Improved dielectric and magnetic properties of Ti modified BiCaFeO3 multiferroic ceramics
Authors: Reetu  , Agarwal Ashish , Sanghi Sujata , Ashima  , Ahlawat Neetu
Published: January 2013

Ti substituted BiCaFeO3 ceramics having compositions Bi0.8Ca0.2Fe1−xTixO3 (x = 0.0, 0.1, 0.2) were synthesized by the conventional solid state reaction method. Powder X-ray diffraction investigations performed at room temperature show that all samples possess a rhombohedrally distorted perovskite structure described by the space group R3c. Rietveld refinement presented a good agreement between the observed and calculated patterns. Dielectric response of these samples was analyzed in the frequency range 1 kHz–5 MHz at different temperatures. Dispersion in dielectric constant (έ) and dielectric loss factor (tanδ) values decreases with Ti substitution. έ increases and tanδ decreases significantly by Ti substitution. Magnetic measurements were carried out at room temperature up to a field of 20 kOe. Magnetic properties of Bi0.8Ca0.2FeO3 ceramic are greatly improved on Ti substitution along with a significant opening in the room temperature M-H hysteresis loop. The values of remnant magnetization (Mr) 0.08 and 0.13 emu/g; coercivity (Hc) 4.25 and 5.50 kOe are observed for samples with x = 0.1 and 0.2, respectively.
Enhancing the tumor discrimination using antibody-activated magnetic nanoparticles in ultra-low magnetic fields
Authors: Yang H. C. , Huang K. W. , Liao S. H. , Horng H. E. , Chieh J. J. , Chen H. H. , Chen M. J. , Chen K. L. , Wang L. M.
Published: January 2013

In this paper, we report an enhanced liver tumor discrimination for rats using antibody-activated magnetic nanoparticles (MNs) and ultra-low-field magnetic resonance imaging ex vivo. It was found that the intensity ratio between the magnetic resonance image of tumor and normal liver tissues is 2–3 absence of antibody-activated MNs in rats. The intensity ratio rises to ∼100 when antibody-activated MNs are expressed in liver tumors through vein injection. Enhancing tumor discrimination using antibody-activated MNs is demonstrated using T1-weighted contrast imaging in ultra-low magnetic fields.
Structure formation in binary mixtures of lipids and detergents: Self-assembly and vesicle division
Authors: Noguchi Hiroshi
Published: January 2013

Self-assembly dynamics in binary surfactant mixtures and structure changes of lipid vesicles induced by detergent solution are studied using coarse-grained molecular simulations. Disk-shaped micelles, the bicelles, are stabilized by detergents surrounding the rim of a bilayer disk of lipids. The self-assembled bicelles are considerably smaller than bicelles formed from vesicle rupture, and their size is determined by the concentrations of lipids and detergents and the interactions between the two species. The detergent-adsorption induces spontaneous curvature of the vesicle bilayer and results in vesicle division into two vesicles or vesicle rupture into worm-like micelles. The division occurs mainly via the inverse pathway of the modified stalk model. For large spontaneous curvature of the monolayers of the detergents, a pore is often opened, thereby leading to vesicle division or worm-like micelle formation.