bluuebunny/crossref_metadata_2025 huggingface dataset:
MR image reconstruction from generalized projections
Authors: Schultz Gerrit , Gallichan Daniel , Reisert Marco , Hennig Jürgen , Zaitsev Maxim
Published: November 2013

Purpose

Currently, the time required for image reconstruction is prohibitively long if data are acquired using multidimensional imaging trajectories that make use of multichannel systems equipped with nonlinear gradients. Methods are presented that reduce the computational complexity of the iterative time‐domain reconstruction algorithm down from O(N4) to O(N3).

Theory

For generalized projections, a large class of multidimensional imaging trajectories, the encoding matrix can be focused to sparse bands by introducing an appropriate filter function along the frequency‐encoding direction. The reconstruction can be speeded up by ignoring values below a predefined threshold level.

Methods

Two methods are presented that differ in how the filter is incorporated into the reconstruction algorithm. The first method represents, without implementation of a threshold, a weighted version of the time‐domain method, while the second method is equivalent to it.

Results

Simulation and measurement results show that image reconstruction from high‐resolution imaging data can be speeded up by up to two orders of magnitude. While the weighted reconstruction requires more iterations to reach an optimum than the second method, it is less sensitive to thresholding.

Conclusion

For complex spatial encoding strategies that involve nonlinear gradient fields, fast and accurate image reconstruction methods are provided that are particularly efficient for high‐resolution anatomical imaging. Magn Reson Med 72:546–557, 2014. © 2013 Wiley Periodicals, Inc.
Improved B0‐distortion correction in diffusion MRI using interlaced q‐space sampling and constrained reconstruction
Authors: Bhushan Chitresh , Joshi Anand A. , Leahy Richard M. , Haldar Justin P.
Published: November 2013

Purpose

To enable high‐quality correction of susceptibility‐induced geometric distortion artifacts in diffusion magnetic resonance imaging (MRI) images without increasing scan time.

Theory and Methods

A new method for distortion correction is proposed based on subsampling a generalized version of the state‐of‐the‐art reversed‐gradient distortion correction method. Rather than acquire each q‐space sample multiple times with different distortions (as in the conventional reversed‐gradient method), we sample each q‐space point once with an interlaced sampling scheme that measures different distortions at different q‐space locations. Distortion correction is achieved using a novel constrained reconstruction formulation that leverages the smoothness of diffusion data in q‐space.

Results

The effectiveness of the proposed method is demonstrated with simulated and in vivo diffusion MRI data. The proposed method is substantially faster than the reversed‐gradient method, and can also provide smaller intensity errors in the corrected images and smaller errors in derived quantitative diffusion parameters.

Conclusion

The proposed method enables state‐of‐the‐art distortion correction performance without increasing data acquisition time. Magn Reson Med 72:1218–1232, 2014. © 2013 Wiley Periodicals, Inc.
GENDER DIFFERENCES IN WRITTEN EXPRESSION CURRICULUM‐BASED MEASUREMENT IN THIRD‐ THROUGH EIGHTH‐GRADE STUDENTS
Authors: Fearrington Jamie Y. , Parker Patricia D. , Kidder‐Ashley Pamela , Gagnon Sandra G. , McCane‐Bowling Sara , Sorrell Christy A.
Published: November 2013

Many studies have found gender differences in certain areas of academic achievement, such as reading and math. Fewer studies have examined gender disparities in writing skills. The current study explored gender differences in written expression performance. Participants were 1,240 male and female students in third through eighth grade, representing five schools in a rural southeastern school district. Each student was administered an AIMSweb curriculum‐based measurement writing probe during the district's regularly scheduled fall, winter, and spring benchmarks. All measures were scored for total words written and correct writing sequences. Two‐way repeated measures analyses of variance were used to determine whether differences existed in the sample. A significant female advantage was found on both scoring indices at each grade level. These findings have strong instructional and theoretical implications for practicing school psychologists and other educators.
The EORTC emotional functioning computerized adaptive test: phases I–III of a cross‐cultural item bank development
Authors: Gamper Eva‐Maria , Groenvold Mogens , Petersen Morten Aa , Young Teresa , Costantini Anna , Aaronson Neil , Giesinger Johannes M. , Meraner Verena , Kemmler Georg , Holzner Bernhard ,   on behalf of the EORTC Quality of Life Group
Published: November 2013

Background

The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group is currently developing computerized adaptive testing measures for the Quality of Life Questionnaire Core‐30 (QLQ‐C30) scales. The work presented here describes the development of an EORTC item bank for emotional functioning (EF), which is one of the core domains of the QLQ‐C30.

Methods

According to the EORTC guidelines on module development, the development of the EF item bank comprised four phases, of which the phases I–III are reported in the present paper.

Phase I involved defining the theoretical framework for the EF item bank and a literature search. Phase II included pre‐defined item selection steps and a multi‐stage expert review process. In phase III, feedback from cancer patients from different countries was obtained.

Results

On the basis of literature search in phase I, a list of 1750 items was generated. These were reviewed and further developed in phase II with a focus on relevance, redundancy, clarity, and difficulty. The development and selection steps led to a preliminary list of 41 items. In phase III, patient interviews (N = 41; Austria, Denmark, Italy, and the UK) were conducted with the preliminary item list, resulting in some minor changes to item wording. The final list comprised 38 items.

Discussion

The phases I–III of the developmental process have resulted in an EF item list that was well accepted by patients in several countries. The items will be subjected to larger‐scale field testing in order to establish their psychometric characteristics and their fit to an item response theory model. © 2013 The Authors. Psycho‐Oncology published by John Wiley & Sons, Ltd.
Spectral characterization of Mg2Si pn ‐junction diode depending on RTA periods
Authors: Takezaki Masaaki , Yamanaka Yusuke , Uchikoshi Masahito , Udono Haruhiko
Published: November 2013

We have studied the effect of thermal annealing periods on the optoelectrical properties of Mg2Si pn ‐junction diodes fabricated by a conventional thermal diffusion process of Ag acceptor. The Au/Ag/n ‐Mg2Si (carrier concentration = 2 × 1015cm‐3, resistivity = 5‐10 Ωcm) substrate was annealed at 550 °C in the Ar‐atmosphere using a rapid thermal annealing (RTA) furnace. The annealing periods were varied between 2 and 10 minutes. Clear rectifying behavior of J ‐V characteristics was observed for the diodes annealed for more than 2 minutes. Spectral responsivity from the photon energy threshold of approximately 0.6 eV was demonstrated with the Mg2Si pn ‐junction diodes under the zero bias condition at room temperature. The maximum intensity of spectral responsivity was increased with decrease the annealing period. The spectral responsivity of the diode with the RTA periods of 4 minutes was approximately 4 times higher than that of 10 minutes annealed one. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The art of forging neurons: direct reprogramming of somatic cells into induced neuronal cells
Authors: Karow M. , Berninger B.
Published: November 2013

Cellular reprogramming has shed new light on the plasticity of terminally differentiated cells and unearthed novel strategies for cell-based therapies to treat neurological disor­ders. With accumulating knowledge of the programs underlying the genesis of the dis­tinct neural cell types, particularly the iden­tification of crucial transcription factors and microRNAs, reprogramming of somatic cells of different origins into induced neuronal cells or neural stem cells has been success­fully achieved. Starting with the general con­cept of reprogramming, we discuss three dif­ferent paradigms: (1) direct conversion of central nervous system (CNS) foreign cells such as skin fibroblasts into induced neuro­nal cells or neural stem cells; (2) transdiffer­entiation of CNS resident cells such as astro­cytes and brain pericytes into induced neuro­nal cells; (3) reprogramming of one neuronal subtype into another. The latter has already been successfully achieved in vivo during ear­ly brain development, providing a strong im­pulse to attempt direct reprogramming in si­tu for future brain repair.
Political Arithmetic and Sacred History: Population Thought in the English Enlightenment, 1660–1750
Authors: McCormick Ted
Published: November 2013

Current approaches to the history of early modern population thought focus on the state and secular governance, while standard treatments of Restoration and Augustan “political arithmetic” emphasize its economic or social-scientific content. This article recovers nonsecular uses of demographic quantification, excavating the use of political arithmetic in religious polemic between ca. 1660 and ca. 1750. As a form of empirical natural philosophy, political arithmetic suited the polemical needs of latitudinarian Anglicans and others combating deism, atheism, and preadamism; the demographic regularities it revealed furnished evidence of providential solicitude, while the history of population growth was a potential prop for scriptural chronologies. A strand of “sacred” political arithmetic thus contributed to natural theology while modeling—albeit inconsistently—new historical applications for empirical methodology. The article concludes by considering possible causes for the decline of this “sacred” strand of demographic quantification, while suggesting connections between it and better-known secular forms of Enlightenment-era population thought.
The Cock of the School: A Cultural History of Playground Violence in Britain, 1880–1940
Authors: Middleton Jacob
Published: November 2013

Violence was an important part of the educational experience of many British children during the nineteenth and twentieth centuries. It principally took the form of playground fights, in which children competed in displays of physical prowess to win the accolade “cock of the school,” the term attached to the best fighter. This article examines the background to these fights using autobiographical accounts produced by individuals educated between 1890 and 1940. Working from common themes in these accounts, it explains the structure and context of schoolyard fights. In particular, it examines the manner in which contemporary notions of masculinity influenced the conduct of children. Fighting was a means by which a schoolboy could act out a fantasy of manhood and, through this, relate to his peers and the school environment.
Mutton Dressed as Lamb? Fashioning Age in Georgian England
Authors: Vickery Amanda
Published: November 2013

Despite an established literature on gender, consumerism, and dress, there is almost no research on fashion and the life cycle. Meanwhile, the historiography on aging has addressed stigma, physicality, and sexuality, though only tangentially the manufacture of femininity through clothes. This article links the two separate historiographies. It is concerned with the ongoing fabrication of mature femininity through fashionable clothes, and the paradoxes inherent in that performance. The misogynist attack on dressy older women was pungent, but mature women still had to clothe themselves. Accusations of frolicking in a lamb fashion were mortifying, but keeping up appearances was vital too. This article examines the interplay of age and fashion, re-creating the distinctive way women of the middling ranks and lesser gentry negotiated the pitfalls of dressing past their prime, charting a perilous course between indignity and scorn on the one hand and invisibility on the other. Perceptions of age and aging bore unevenly on women and men. Nevertheless, conviction about the decorum of female sartorial retirement once the blush was off the peach and savage portrayals of hideous physical decline were counterbalanced by the blandishments of the market itself. Cumulatively, the Georgian marketplace tended to endorse the public profiles of older women, suggesting a galaxy of imagined performances that overwhelmed the misogynist discourse arguing for their obliteration.
Time-dependent, non-monotonic mixing in stratified turbulent shear flows: implications for oceanographic estimates of buoyancy flux
Authors: Mashayek A. , Caulfield C. P. , Peltier W. R.
Published: November 2013

We employ direct numerical simulation to investigate the efficiency of diapycnal mixing by shear-induced turbulence in stably stratified free shear layers for flows with bulk Richardson numbers in the range $0. 12\leq R{i}_{0} \leq 0. 2$ and Reynolds number $Re= 6000$. We show that mixing efficiency depends non-monotonically upon $R{i}_{0} $, peaking in the range 0.14–0.16, which coincides closely with the range in which both the buoyancy flux and the dissipation rate are maximum. By detailed analyses of the energetics of flow evolution and the underlying dynamics, we show that the existence of high mixing efficiency in the range $0. 14\lt R{i}_{0} \lt 0. 16$ is due to the emergence of a large number of small-scale instabilities which do not exist at lower Richardson numbers and are stabilized at high Richardson numbers. As discussed in Mashayek & Peltier (J. Fluid Mech., vol. 725, 2013, pp. 216–261), the existence of such a well-populated ‘zoo’ of secondary instabilities at intermediate Richardson numbers and the subsequent high mixing efficiency is realized only if the Reynolds number is higher than a critical value which is generally higher than that achievable in laboratory settings, as well as that which was achieved in the majority of previous numerical studies of shear-induced stratified turbulence. We furthermore show that the primary assumptions upon which the widely employed Osborn (J. Phys. Oceanogr. vol. 10, 1980, pp. 83–89) formula is based, as well as its counterparts and derivatives, which relate buoyancy flux to dissipation rate through a (constant) flux coefficient ($\Gamma $), fail at higher Richardson numbers provided that the Reynolds number is sufficiently high. Specifically, we show that the assumptions of fully developed, stationary, and isotropic turbulence all break down at high Richardson numbers. We show that the breakdown of these assumptions occurs most prominently at Richardson numbers above that corresponding to the maximum mixing efficiency, a fact that highlights the importance of the non-monotonicity of the dependence of mixing efficiency upon Richardson number, which we establish to be characteristic of stratified shear-induced turbulence. At high $R{i}_{0} $, the lifecycle of the turbulence is composed of a rapidly growing phase followed by a phase of rapid decay. Throughout the lifecycle, there is considerable exchange of energy between the small-scale turbulence and larger coherent structures which survive the various stages of flow evolution. Since shear instability is one of the most prominent mechanisms for turbulent dissipation of energy at scales below hundreds of metres and at various depths of the ocean, our results have important implications for the inference of turbulent diffusivities on the basis of microstructure measurements in the oceanic environment.
Interactions between plasma concentrations of folate and markers of vitamin B12status with cognitive performance in elderly people not exposed to folic acid fortification: the Hordaland Health Study
Authors: Doets Esmée L. , Ueland Per M. , Tell Grethe S. , Vollset Stein Emil , Nygård Ottar K. , van't Veer Pieter , de Groot Lisette C. P. G. M. , Nurk Eha , Refsum Helga , Smith A. David , Eussen Simone J. P. M.
Published: November 2013

A combination of high folate with low vitamin B12plasma status has been associated with cognitive impairment in a population exposed to mandatory folic acid fortification. The objective of the present study was to examine the interactions between plasma concentrations of folate and vitamin B12markers in relation to cognitive performance in Norwegian elderly who were unexposed to mandatory or voluntary folic acid fortification. Cognitive performance was assessed by six cognitive tests in 2203 individuals aged 72–74 years. A combined score was calculated using principal component analysis. The associations of folate concentrations, vitamin B12markers (total vitamin B12, holotranscobalamin (holoTC) and methylmalonic acid (MMA)) and their interactions in relation to cognitive performance were evaluated by quantile regression and least-squares regression, adjusted for sex, education, apo-ɛ4 genotype, history of CVD/hypertension and creatinine. Cross-sectional analyses revealed an interaction (P= 0·009) between plasma concentrations of folate and vitamin B12in relation to cognitive performance. Plasma vitamin B12concentrations in the lowest quartile ( < 274 pmol/l) combined with plasma folate concentrations in the highest quartile (>18·5 nmol/l) were associated with a reduced risk of cognitive impairment compared with plasma concentrations in the middle quartiles of both vitamins (OR 0·22, 95 % CI 0·05, 0·92). The interaction between folate and holoTC or MMA in relation to cognitive performance was not significant. In conclusion, this large study population unexposed to mandatory folic acid fortification showed that plasma folate, but not plasma vitamin B12, was associated with cognitive performance. Among the elderly participants with vitamin B12concentrations in the lower range, the association between plasma folate and cognitive performance was strongest.
Effects of habitat, group-size, sex-age class and seasonal variation on the behavioural responses of the mountain nyala (Tragelaphus buxtoni) in Munessa, Ethiopia
Authors: Tadesse Solomon A. , Kotler Burt P.
Published: November 2013

Activity patterns of animals are generally influenced by many factors. We hypothesized that the behavioural responses (i.e. activity time-budget allocated to vigilance, feeding and moving) of mountain nyala (Tragelaphus buxtoni) should vary with habitat type, season, group-size and sex-age class. We randomly established a total of 12 permanent walking transects with the aid of a GPS device across three major habitat types used by the mountain nyala (i.e. four transects in each habitat). Following each transect, we conducted focal-animal observations to quantify the time-budget allocated to vigilance, feeding and moving. A total of 119 and 116 focal-animals were assessed in the wet and dry season respectively. Moreover, along each transect, seven habitat variables were collected in systematically laid 109 circular plots each with a 5-m radius (i.e. 31, 41 and 37 plots in the cleared vegetation, plantation and natural forest respectively) in the wet and dry season. We developed behavioural models by correlating the time-budget (i.e. proportion of time vigilance, feeding and moving) of the focal-animals in accordance with habitat variables, group-size and sex-age class. In the wet season, mountain nyala devoted most of their time to vigilance, but they allocated the largest proportion of their time to moving in the dry season. Vigilance differed among the three habitats and was highest in the cleared vegetation during the dry season. Contrary to expectations, adult males were more vigilant than both adult females and sub-adults during the dry season. The behavioural models based on time-budget help to predict how the mountain nyala perceive their environment and trade-off between food acquisition and safety in the wet and dry season. The study also improves our understanding of the adaptive behavioural ecology of the endangered mountain nyala.
The Möbius–Wall congruences forp-adicL-functions of CM elliptic curves
Authors: BOUGANIS THANASIS
Published: November 2013

In this paper we prove, under a technical assumption, the so-called “Möbius–Wall” congruences between abelianp-adicL-functions of CM elliptic curves. These congruences are the analogue of those shown by Ritter and Weiss for the Tate motive, and offer strong evidences in favor of the existence of non-abelianp-adicL-functions for CM elliptic curves.
Molecular epidemiology ofStaphyloccocus aureuscolonization in the Old Order of Amish of Lancaster county, Pennsylvania, USA
Authors: ROGHMANN M.-C. , LONGINAKER N. , CROFT L. , JOHNSON J. K. , LYDECKER A. D. , STINE O. C.
Published: November 2013

Transmission ofStaphylococcus aureuscolonization in community-based populations is not well understood. We sought to describe the molecular epidemiology ofS. aureuscolonization in the Old Order Amish. The study was a prospective, observational study of healthy adults and their same-sex siblings who were cultured from the anterior nares twice.S. aureusisolates were characterized usingspatyping. Overall, 40% (159/398) of the study population was colonized withS. aureus. There were 84spatypes with the most abundantspatypes being t012 (13%) and t021 (7%). There was no clustering ofspatypes within sibling groups; however, there was clustering within households. There were 111S. aureus-colonized participant pairs living within the same household. Of these, 47% had concordantspatypes. The diversity ofspatypes across a relatively isolated, genetically homogenous population with a similar lifestyle is striking. Taken together this suggests thatS. aureustransmission is a local phenomenon limited to very close contact.
How Do the Features of Mindfulness-Based Cognitive Therapy Contribute to Positive Therapeutic Change? A Meta-Synthesis of Qualitative Studies
Authors: Cairns Victoria , Murray Craig
Published: November 2013

Background: The exploration of Mindfulness-based Cognitive Therapy through qualitative investigation is a growing area of interest within current literature, providing valuable understanding of the process of change experienced by those engaging in this therapeutic approach. Aims: This meta-synthesis aims to gain a deeper understanding of how the features of Mindfulness-based Cognitive Therapy contribute to positive therapeutic change. Method: Noblit and Hare's (1988) 7-step meta-ethnography method was conducted in order to synthesize the findings of seven qualitative studies. Results: The process of reciprocal translation identified the following five major themes: i) Taking control through understanding, awareness and acceptance; ii) The impact of the group; (iii) Taking skills into everyday life; (iv) Feelings towards the self; (v) The role of expectations. Conclusion: The synthesis of translation identified the higher order concept of “The Mindfulness-based Cognitive Therapy Journey to Change”, which depicts the complex interaction between the five themes in relation to how they contribute to positive therapeutic change. The findings are discussed in relation to previous research, theory and their implications for clinical practice.
Evaluation of Intrinsic Charge Carrier Transport at Insulator-Semiconductor Interfaces Probed by a Non-Contact Microwave-Based Technique
Authors: Honsho Yoshihito , Miyakai Tomoyo , Sakurai Tsuneaki , Saeki Akinori , Seki Shu
Published: November 2013

We have successfully designed the geometry of the microwave cavity and the thin metal electrode, achieving resonance of the microwave cavity with the metal-insulator-semiconductor (MIS) device structure. This very simple MIS device operates in the cavity, where charge carriers are injected quantitatively by an applied bias at the insulator-semiconductor interface. The local motion of the charge carriers was clearly probed through the applied external microwave field, also giving the quantitative responses to the injected charge carrier density and charge/discharge characteristics. By means of the present measurement system named field-induced time-resolved microwave conductivity (FI-TRMC), the pentacene thin film in the MIS device allowed the evaluation of the hole and electron mobility at the insulator-semiconductor interface of 6.3 and 0.34 cm2 V−1 s−1, respectively. This is the first report on the direct, intrinsic, non-contact measurement of charge carrier mobility at interfaces that has been fully experimentally verified.
Antitoxin MqsA Represses Curli Formation Through the Master Biofilm Regulator CsgD
Authors: Soo Valerie W. C. , Wood Thomas K.
Published: November 2013

MqsA, the antitoxin of the MqsR/MqsA toxin/antitoxin (TA) system, is a global regulator that reduces expression of several stress response genes (e.g., mqsRA, cspD and rpoS) by binding to the promoter palindromic motif [5′-AACCT (N)3AGGTT-3′]. We identified a similar mqsRA-like palindrome [5′-AACCT TA AGGTT-3′] 78 bp upstream of the transcription initiation site in the csgD promoter (p-csgD). CsgD is a master regulator for biofilm formation via its control of curli and cellulose production. We show here that MqsA binds to this palindrome in p-csgD to repress csgD transcription. As expected, p-csgD repression by MqsA resulted in reduced transcription from CsgD-regulated curli genes csgA and csgB (encoding the major and minor curlin subunits, respectively). Curli production was reduced in colonies and in planktonic cells upon MqsA production. Hence, MqsA directly represses p-csgD and thereby influences curli formation. This demonstrates that TA systems can impact overall cell physiology by fine-tuning cellular stress responses.
pH-sensitive unimolecular fluorescent polymeric micelles: from volume phase transition to optical response
Authors: You Shusen , Cai Qing , Müllen Klaus , Yang Wantai , Yin Meizhen
Published: November 2013

A schematic representation of volume phase transition and fluorescence response of unimolecular micelles.
The supramolecular interaction mediated chiral 1D cyanide-bridged metamagnet: synthesis, crystal structures and magnetic properties
Authors: Zhang Daopeng , Bian Yongzhong , Qin Jie , Wang Ping , Chen Xia
Published: November 2013

Two cyanide-bridged enantiopure one-dimensional single chain complexes have been synthesized and structurally characterized. Systematically magnetic investigations show the antiferromagnetic coupling between the Mn(iii)–Fe(iii) centers and the metamagnetic behavior at about 5.0 K.
Streamlining the conversion of biomass to polyesters: bicyclic monomers with continuous flow
Authors: Dakshinamoorthy Deivasagayam , Lewis Stewart P. , Cavazza Michael P. , Hoover Aaron M. , Iwig David F. , Damodaran Krishnan , Mathers Robert T.
Published: November 2013

Continuous flow methodology for the multi step synthesis of biomass derived aliphatic bicyclic-anhydride monomer. Polymerization with bio-based alcohols results in renewable polyesters with good thermal stability.
A 2D Particle in Cell model for ion extraction and focusing in electrostatic accelerators
Authors: Veltri P. , Cavenago M. , Serianni G.
Published: November 2013

Negative ions are fundamental to produce intense and high energy neutral beams used to heat the plasma in fusion devices. The processes regulating the ion extraction involve the formation of a sheath on a scale comparable to the Debye length of the plasma. On the other hand, the ion acceleration as a beam is obtained on distances greater than λD. The paper presents a model for both the phases of ion extraction and acceleration of the ions and its implementation in a numerical code. The space charge of particles is deposited following usual Particle in Cell codes technique, while the field is solved with finite element methods. Some hypotheses on the beam plasma transition are described, allowing to model both regions at the same time. The code was tested with the geometry of the NIO1 negative ions source, and the results are compared with existing ray tracing codes and discussed.
Linear-scaling symmetry-adapted perturbation theory with scaled dispersion
Authors: Maurer Simon A. , Beer Matthias , Lambrecht Daniel S. , Ochsenfeld Christian
Published: November 2013

We present a linear-scaling symmetry-adapted perturbation theory (SAPT) method that is based on an atomic orbital (AO) formulation of zeroth-order SAPT (SAPT0). The non-dispersive terms are realized with linear-scaling cost using both the continuous fast multipole method (CFMM) and the linear exchange (LinK) approach for integral contractions as well as our efficient Laplace-based coupled-perturbed self-consistent field method (DL-CPSCF) for evaluating response densities. The reformulation of the dispersion term is based on our linear-scaling AO Møller-Plesset second-order perturbation theory (AO-MP2) method, that uses our recently introduced QQR-type screening [S. A. Maurer, D. S. Lambrecht, J. Kussmann, and C. Ochsenfeld, J. Chem. Phys. 138, 014101 (2013)] for preselecting numerically significant energy contributions. Similar to scaled opposite-spin MP2, we neglect the exchange-dispersion term in SAPT and introduce a scaling factor for the dispersion term, which compensates for the error and at the same time accounts for basis set incompleteness effects and intramonomer correlation. We show in extensive benchmark calculations that the new scaled-dispersion (sd-)SAPT0 approach provides reliable results for small and large interacting systems where the results with a small 6-31G** basis are roughly comparable to supermolecular MP2 calculations in a triple-zeta basis. The performance of our method is demonstrated with timings on cellulose fragments, DNA systems, and cutouts of a protein-ligand complex with up to 1100 atoms on a single computer core.
Presymplectic current and the inverse problem of the calculus of variations
Authors: Khavkine Igor
Published: November 2013

The inverse problem of the calculus of variations asks whether a given system of partial differential equations (PDEs) admits a variational formulation. We show that the existence of a presymplectic form in the variational bicomplex, when horizontally closed on solutions, allows us to construct a variational formulation for a subsystem of the given PDE. No constraints on the differential order or number of dependent or independent variables are assumed. The proof follows a recent observation of Bridges, Hydon, and Lawson [Math. Proc. Cambridge Philos. Soc. 148(01), 159–178 (2010)] and generalizes an older result of Henneaux [Ann. Phys. 140(1), 45–64 (1982)] from ordinary differential equations (ODEs) to PDEs. Uniqueness of the variational formulation is also discussed.
Increasing Leidenfrost point using micro-nano hierarchical surface structures
Authors: Kwon Hyuk-min , Bird James C. , Varanasi Kripa K.
Published: November 2013

The Leidenfrost effect is undesirable in cooling applications as the vapor layer on which the liquid levitates acts as a heat transfer barrier. Here, we report on increasing the Leidenfrost temperature by surface textures that can promote droplet wetting at high superheat via capillary wicking. Counterintuitively, we find that sparser rather than denser textures increase the Leidenfrost temperature. Our experimental results are consistent with a physical model that balances capillary wetting pressures with dewetting pressures exerted by the escaping vapor. The physical mechanism suggests that hierarchical textures have a higher Leidenfrost temperature compared to single-length-scale textures, which is confirmed experimentally.
Emergence of complex and spinor wave functions in scale relativity. I. Nature of scale variables
Authors: Nottale Laurent , Célérier Marie-Noëlle
Published: November 2013

One of the main results of scale relativity as regards the foundation of quantum mechanics is its explanation of the origin of the complex nature of the wave function. The scale relativity theory introduces an explicit dependence of physical quantities on scale variables, founding itself on the theorem according to which a continuous and non-differentiable space-time is fractal (i.e., scale-divergent). In the present paper, the nature of the scale variables and their relations to resolutions and differential elements are specified in the non-relativistic case (fractal space). We show that, owing to the scale-dependence which it induces, non-differentiability involves a fundamental two-valuedness of the mean derivatives. Since, in the scale relativity framework, the wave function is a manifestation of the velocity field of fractal space-time geodesics, the two-valuedness of velocities leads to write them in terms of complex numbers, and yields therefore the complex nature of the wave function, from which the usual expression of the Schrödinger equation can be derived.
Characterizing N-dimensional anisotropic Brownian motion by the distribution of diffusivities
Authors: Heidernätsch Mario , Bauer Michael , Radons Günter
Published: November 2013

Anisotropic diffusion processes emerge in various fields such as transport in biological tissue and diffusion in liquid crystals. In such systems, the motion is described by a diffusion tensor. For a proper characterization of processes with more than one diffusion coefficient, an average description by the mean squared displacement is often not sufficient. Hence, in this paper, we use the distribution of diffusivities to study diffusion in a homogeneous anisotropic environment. We derive analytical expressions of the distribution and relate its properties to an anisotropy measure based on the mean diffusivity and the asymptotic decay of the distribution. Both quantities are easy to determine from experimental data and reveal the existence of more than one diffusion coefficient, which allows the distinction between isotropic and anisotropic processes. We further discuss the influence on the analysis of projected trajectories, which are typically accessible in experiments. For the experimentally most relevant cases of two- and three-dimensional anisotropic diffusion, we derive specific expressions, determine the diffusion tensor, characterize the anisotropy, and demonstrate the applicability for simulated trajectories.
The instantaneous fluctuation theorem
Authors: Petersen Charlotte F. , Evans Denis J. , Williams Stephen R.
Published: November 2013

We give a derivation of a new instantaneous fluctuation relation for an arbitrary phase function which is odd under time reversal. The form of this new relation is not obvious, and involves observing the system along its transient phase space trajectory both before and after the point in time at which the fluctuations are being compared. We demonstrate this relation computationally for a number of phase functions in a shear flow system and show that this non-locality in time is an essential component of the instantaneous fluctuation theorem.
Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations
Authors: Jin Chengjun , Strange Mikkel , Markussen Troels , Solomon Gemma C. , Thygesen Kristian S.
Published: November 2013

We study the effect of functional groups (CH3*4, OCH3, CH3, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group.
Electro-caloric effect in (Ba1−xCax)(Zr0.05Ti0.95)O3: A lead-free ferroelectric material
Authors: Singh Gurvinderjit , Tiwari V. S. , Gupta P. K.
Published: November 2013

Electro-caloric effect in lead-free (Ba1−xCax)(Zr0.05Ti0.95)O3 ferroelectric ceramics has been studied for x = 0.05, 0.08, and 0.10. The electro-caloric coefficient as high as 0.253 K mm/kV has been obtained near tetragonal-to-cubic phase transition for x = 0.08. This value is nearly the same as observed in lead-based ferroelectric materials. The higher value of electro-caloric coefficient at x = 0.08 is attributed to the higher polarization flexibility.
Electronic properties of III-nitride semiconductors: A first-principles investigation using the Tran-Blaha modified Becke-Johnson potential
Authors: Araujo Rafael B. , de Almeida J. S. , Ferreira da Silva A.
Published: November 2013

In this work, we use density functional theory to investigate the influence of semilocal exchange and correlation effects on the electronic properties of III-nitride semiconductors considering zinc-blende and wurtzite crystal structures. We find that the inclusion of such effects through the use of the Tran-Blaha modified Becke-Johnson potential yields an excellent description of the electronic structures of these materials giving energy band gaps which are systematically larger than the ones obtained with standard functionals such as the generalized gradient approximation. The discrepancy between the experimental and theoretical band gaps is then significantly reduced with semilocal exchange and correlation effects. However, the effective masses are overestimated in the zinc-blende nitrides, but no systematic trend is found in the wurtzite compounds. New results for energy band gaps and effective masses of zinc-blende and wurtzite indium nitrides are presented.
Experimental verification of the model by Klapper for 4H-SiC homoepitaxy on vicinal substrates
Authors: Kallinger Birgit , Polster Sebastian , Berwian Patrick , Friedrich Jochen , Danilewsky Andreas N.
Published: November 2013

4H-SiC homoepitaxial layers free of basal plane dislocations (BPDs) are urgently needed to overcome the so-called bipolar degradation of high-voltage devices. BPDs being present in substrates are able to either propagate to the epilayer or convert to harmless threading edge dislocations (TEDs) in the epilayer. The model by Klapper predicts the conversion of BPDs to TEDs to be more efficient for growth on vicinal substrates with low off-cut angle. This paper aims to verify the model by Klapper by an extensive variation of epitaxial growth parameters and the substrates' off-cut. It is shown that the off-cut angle is the key parameter for growth of BPD-free epilayers. Furthermore, it is shown that the model also describes adequately the behavior of different types of TEDs, i.e., TED II and TED III dislocations, during epitaxial growth. Therefore, the model by Klapper is verified successfully for 4H-SiC homoepitaxial growth on vicinal substrates.
Fullerene derivatives as electron donor for organic photovoltaic cells
Authors: Zhuang Taojun , Wang Xiao-Feng , Sano Takeshi , Hong Ziruo , Yang Yang , Kido Junji
Published: November 2013

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C60 bisadduct (ICBA) and phenyl C61-butyric acid methyl ester as the electron donors with fullerene C70 as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C70 PHJ cell gives clear external quantum efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.
Analytical Bond-order Potential for hcp-Y
Authors: Fan Kai-min , Yang Li , Tang Jing , Sun Qing-qiang , Dai Yun-ya , Peng Shu-ming , Zhou Xiao-song , Zu Xiao-tao
Published: November 2013

The lattice parameters, elastic constants, cohesive energy, structural energy differences, as well as the properties of point defects and planar defects of hexagonal close-packed yttrium (hcp-Y) have been studied with ab initio density functional theory for constructing an extensive database. Based on an analytical bond-order potential scheme, empirical many-body interatomic potential for hcp-Y has been developed. The model is fitted to some properties of Y, e.g., the lattice parameters, elastic constants, bulk modulus, cohesive energy, vacancy formation energy, and the structural energy differences. The present potential has ability to reproduce defect properties including the self-interstitial atoms formation energies, vacancy formation energy, divacancy binding energy, as well as the bulk properties and the thermal dynamic properties.
Effects of Non-specific and Specific Solvation on Adsorption of BPTI on Au Surface: Insight from Molecular Dynamics Simulation
Authors: Yang Wei , Zhang Li-yun , Li Meng-long , Pu Xue-mei , Zhao Nan-rong
Published: November 2013

Proteins adsorption at solid surfaces are of paramount important for many natural processes. However, the role of specific water in influencing the adsorption process has not been well understood. We used molecular dynamics simulation to study the adsorption of BPTI on Au surface in three water environments (dielectric constant model, partial and full solvation models). The result shows that a fast and strong adsorption can occur in the dielectric environment, which leads to significant structure changes, as confirmed by great deviation from the crystal structure, largely spreading along the Au surface, rapid lose in all secondary structures and the great number of atoms in contact with the surface. Compared to the dielectric model, slower adsorption and fewer changes in the calculated properties above are observed in the partial solvation system since the specific water layer weakens the adsorption effects. However, in the partial solvation system, the adsorption of polar Au surface causes a significant decrease in the specific hydration around the protein, which still results in large structure changes similar to the dielectric system, but with much less adsorption extent. Enough water molecules in the full solvation system could allow the protein to rotate, and to large extent preserve the protein native structure, thus leading to the slowest and weakest adsorption. On the whole, the effects of non-specific and specific solvation on the protein structure and adsorption dynamics are significantly different, highlighting the importance of the specific water molecule in the protein adsorption.
Graphene-gold Nanoparticle Composite Film Modified Electrode for Determination of Trace Mercury in Environmental Water
Authors: Wang Xue-mei , Wu Shou-guo , Liu Hao , Zhou Lei , Zhao Qi-ping
Published: November 2013

The graphene-gold nanoparticles composite film modified glassy carbon electrode (EG- AuNPs/GCE) was prepared by one-step coelectrodeposition and employed for determination of trace mercury in environmental water with differential pulse stripping voltammetry. Such a nanostructured composite film combined with the advantages of gold nanoparticles and graphene, can greatly promote the electron-transfer process and increase accumulation ability for Hg(II), leading to a remarkably improved sensitivity. The linear calibration curve ranged from 0.2 μg/L to 30 μg/L for Hg(II) and the detection limit (S/N=3) was found to be 0.03 μg/L at a deposition time of 300 s. Moreover, the stablity of the as-prepared electrode and interferences from other substances were evaluated. The modified electrode was successfully applied to the direct detection of Hg(II) in real water samples.
Fabrication of Monodisperse “Core-Satellite” Nanostructures by DNA-Programming: a Novel Class of Superstructured Building Blocks for Hierarchical Nanoassembly
Authors: Yang Yang , Bai Xue , Fang Ling-ling , Deng Zhao-xiang
Published: November 2013

Monodisperse nanoparticle assembly with tunable structure, composition and properties can be taken as a superstructured building block for the construction of hierarchical nanostructures from the bottom up, which also represents a great challenge in nanotechnology. Here we report on a facile and controllable method that enables a high yield fabrication of uniform gold nanoparticle (AuNP) core-satellites with definable number (in average) of the satellite particles and tunable core-to-satellite distance. The formation of the core-satellite nanostructures is driven by programmable DNA-basepairing, with the resulting nanocomplexes being isolatable via gel electrophoresis. By rationally controlling the DNA coverages on the core and shell particles, high production yields are achieved for the assembly/isolation process. As well, benefiting from a minimum DNA coverage on the satellite AuNPs, a strong affinity is observed for the as-prepared core-satellites to get adsorbed on protein-coated graphene oxide, which allows for a two-dimensional hierarchical assembly of the core-satellite structures. The resulting hierarchical nanoassemblies are expected to find applications in various areas, including plasmonics, biosensing, and nanocatalysis. The method should be generalizable to make even more complicated and higher-order structures by making use of the structural programmability of DNA molecules.
Exposure to Brefeldin A promotes initiation of meiosis in murine female germ cells
Authors: Zhang Lian-Jun , Chen Bo , Feng Xin-Lei , Ma Hua-Gang , Sun Li-lan , Feng Yan-Min , Liang Gui-Jin , Cheng Shun-Feng , Li Lan , Shen Wei
Published: November 2013

In mammals, ontogenesis starts from a fusion of spermatozoon and oocyte, which are produced by reductive nuclear division of a diploid germ cell in a specialised but complex biological process known as meiosis. However, little is known about the mechanism of meiotic initiation in germ cells, although many factors may be responsible for meiosis both in male and female gonads. In this study, 11.5 days post coitum (dpc) female fetal mouse genital ridges were cultured in vitro with exposure to Brefeldin A (BFA) for 6 h, and the changes in meiosis were detected. Synaptonemal-complex analysis implied that BFA played a positive role in meiosis initiation and this hypothesis was confirmed by quantitative PCR of meiosis-specific genes: stimulated by retinoic acid gene 8 (Stra8) and deleted in a zoospermia-like (DAZL). At the same time, mRNA expression of retinoic acid synthetase (Raldh2) and retinoic acid (RA) receptors increased in female gonads with in vitro exposure to BFA. Transplanting genital ridges treated with BFA into the kidney capsule of immunodeficient mice demonstrated that the development capacity of female germ cells was normal, while formation of primordial follicles was seen to be a result of accelerated meiosis after exposure to BFA. In conclusion, the study indicated that BFA stimulated meiosis initiation partly by RA signalling and then promoted the development of follicles.