bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidental Cardiac Findings on Thoracic Imaging
Authors: Kok Hong Kuan , Loo Bryan , Torreggiani William C. , Buckley Orla
Published: February 2013

The cardiac structures are well seen on nongated thoracic computed tomography studies in the investigation and follow-up of cardiopulmonary disease. A wide variety of findings can be incidentally picked up on careful evaluation of the pericardium, cardiac chambers, valves, and great vessels. Some of these findings may represent benign variants, whereas others may have more profound clinical importance. Furthermore, the expansion of interventional and surgical practice has led to the development and placement of new cardiac stents, implantable pacemaker devices, and prosthetic valves with which the practicing radiologist should be familiar. We present a collection of common incidental cardiac findings that can be readily identified on thoracic computed tomography studies and briefly discuss their clinical relevance.
Prediction of psychosis in clinical high-risk patients by the Schizotypal Personality Questionnaire. Results of the EPOS project
Authors: Salokangas R.K.R. , Dingemans P. , Heinimaa M. , Svirskis T. , Luutonen S. , Hietala J. , Ruhrmann S. , Juckel G. , Graf von Reventlow H. , Linszen D. , Birchwood M. , Patterson P. , Schultze-Lutter F. , Klosterkötter J.
Published: February 2013

Objective

Schizotypal features indicate proneness to psychosis in the general population. It is also possible that they increase transition to psychosis (TTP) among clinical high-risk patients (CHR). Our aim was to investigate whether schizotypal features predict TTP in CHR patients.

Methods

In the EPOS (European Prediction of Psychosis Study) project, 245 young help-seeking CHR patients were prospectively followed for 18 months and their TTP was identified. At baseline, subjects were assessed with the Schizotypal Personality Questionnaire (SPQ). Associations between SPQ items and its subscales with the TTP were analysed in Cox regression analysis.

Results

The SPQ subscales and items describing ideas of reference and lack of close interpersonal relationships were found to correlate significantly with TTP. The co-occurrence of these features doubled the risk of TTP.

Conclusions

Presence of ideas of reference and lack of close interpersonal relations increase the risk of full-blown psychosis among CHR patients. This co-occurrence makes the risk of psychosis very high.
The exact probability distribution of the rank product statistics for replicated experiments
Authors: Eisinga Rob , Breitling Rainer , Heskes Tom
Published: February 2013

The rank product method is a widely accepted technique for detecting differentially regulated genes in replicated microarray experiments. To approximate the sampling distribution of the rank product statistic, the original publication proposed a permutation approach, whereas recently an alternative approximation based on the continuous gamma distribution was suggested. However, both approximations are imperfect for estimating small tail probabilities. In this paper we relate the rank product statistic to number theory and provide a derivation of its exact probability distribution and the true tail probabilities.
Completion of cell division is associated with maximum telomerase activity in naturally synchronized cultures of the green algaDesmodesmus quadricauda
Authors: Ševčíková Tereza , Bišová Kateřina , Fojtová Miloslava , Lukešová Alena , Hrčková Kristýna , Sýkorová Eva
Published: February 2013

Telomerase maintains the ends of eukaryotic chromosomes, and its activity is an important parameter correlating with the proliferative capacity of cells. We have investigated cell cycle‐specific changes in telomerase activity using cultures ofDesmodesmus quadricauda, a model alga naturally synchronized by light/dark entrainment. A quantitative telomerase assay revealed high activity in algal cultures, with slight changes during the light period. Significantly increased telomerase activity was observed at the end of the dark phase, when cell division was complete. In contrast to other models, a natural separation between nuclear and cellular division typical for the cell cycle inD. quadricaudamade this observation possible.
Chemomechanical coupling mechanism of F1‐ATPase: Catalysis and torque generation
Authors: Watanabe Rikiya , Noji Hiroyuki
Published: February 2013

F
1‐ATPase (F
1), a rotary motor protein driven by ATP hydrolysis, is unique with respect to its high efficiency and reversibility in converting chemical energy into mechanical work. Single‐molecule studies have improved our understanding about the energy‐conversion mechanism of F
1 and the chemomechanical‐coupling scheme under ATP hydrolysis conditions. A novel single‐molecule technique was recently established to estimate the free‐energy change of F
1 during catalysis at elementary‐step resolution, advancing our understanding about the energy‐conversion mechanism of ATP hydrolysis and synthesis. The energy conversion mechanism of F
1 elucidated from single‐molecule studies provides us with important insights into the operating principles underlying molecular motors.
A novel RING finger gene, SbRFP1, increases resistance to cold‐induced sweetening of potato tubers
Authors: Zhang Huiling , Liu Xun , Liu Jun , Ou Yongbin , Lin Yuan , Li Meng , Song Botao , Xie Conghua
Published: February 2013

The modulation of the activity of enzymes associated with carbohydrate metabolism is important for potato cold‐induced sweetening (CIS). A novel RING finger gene SbRFP1 was cloned and its expression was found to be cold‐inducible in potato tubers of the CIS‐resistant genotypes. Transformation of SbRFP1 in potatoes confirmed its role in inhibiting β‐amylase and invertase activity, which consequently slowed down starch and sucrose degradation and the accumulation of reducing sugars in cold stored tubers. These findings strongly suggest that SbRFP1 may function as a negative regulator of BAM1 and StvacINV1 to decelerate the accumulation of reducing sugars in the process of potato CIS.
Activation of beta 1 but not beta 3 integrin increases cell traction forces
Authors: Lin Grace L. , Cohen Daniel M. , Desai Ravi A. , Breckenridge Mark T. , Gao Lin , Humphries Martin J. , Chen Christopher S.
Published: February 2013

Cell‐generated traction forces induce integrin activation, leading to focal adhesion growth and cell spreading. It remains unknown, however, whether integrin activation feeds back to impact the generation of cytoskeletal tension. Here, we used elastomeric micropost arrays to measure cellular traction forces in wildtype and integrin‐null cells. We report that activation of β1 but not β3 integrin, by either increasing density of immobilized fibronectin or treating with manganese, elicited fibroblast spreading and cytoskeletal tension. Furthermore, this force generation required Rho kinase and myosin activity. These findings suggest that integrin activation and cell traction forces comprise a bi‐directional signaling unit of cell adhesion.
miR‐370 is stage‐specifically expressed during mouse embryonic development and regulates Dnmt3a
Authors: Qi Liu , Hongjuan He , Ning Gu , Zhengbin Han , Yanjiang Xing , Tiebo Zeng , Zhijun Huang , Qiong Wu
Published: February 2013

MicroRNAs (miRNAs) are small non‐coding RNAs that participate in a large variety of biological processes. In this paper, the spatiotemporal expression pattern of miR‐370 was characterized during mouse embryonic development, and was found to be stage‐ and tissue‐specifically expressed. In addition, through luciferase reporter assays and western blot analyses, DNA methyltransferase 3A (Dnmt3a) was identified as a directly regulated target of miR‐370. Altogether, our results indicate that miR‐370 may play important roles in the morphogenesis of diverse organs, especially brain and adrenal glands, by mediating Dnmt3a expression during mouse development.
Reactive oxygen species scavenging activities in a chemiluminescence model and neuroprotection in rat pheochromocytoma cells by astaxanthin, beta‐carotene, and canthaxanthin
Authors: Chang Chi‐Sen , Chang Chia‐Lin , Lai Guia‐Hung
Published: February 2013

The objective of this study was to determine chemiluminescence (CL) antioxidant activities and neuroprotective effects of astaxanthin, beta‐carotene (β‐carotene), and canthaxanthin on undifferentiated rat pheochromocytoma (PC12) cells. We performed three CL antioxidant assays, and the three carotenoids showed varying degrees of antioxidant activity, with astaxanthin exhibiting the highest antioxidant activity than the other two samples. Results of a pyrogallol–luminol assay revealed β‐carotene to have higher antioxidant activity than canthaxanthin, whereas cupric sulfate–Phen–Vc–hydrogen peroxide (H2O2) assay showed canthaxanthin to have higher antioxidant activity than β‐carotene. Luminol–H2O2 assay showed the antioxidant activity series as canthaxanthin > β‐carotene at 62.5–1000 μg/mL and β‐carotene > canthaxanthin at 1000–4000 μg/mL. Astaxanthin exhibited partial neuroprotective activity against H2O2 and the strongest neuroprotective activity against amyloid beta‐peptide(25–35) [(Aβ)(25–35)]‐induced undifferentiated PC12 cell deaths at 0.5–5.0 μM. Canthaxanthin showed partial neuroprotective activity in Aβ(25–35)‐induced undifferentiated PC12 cell deaths at 1.0–5.0 μM. Astaxanthin protected undifferentiated PC12 cells from the damaging effects of H2O2 and Aβ(25–35) by the following ways: (1) scavenging superoxide anion radicals, hydroxyl radicals, and H2O2; (2) securing cell viability; (3) suppressing the production of reactive oxygen species; and (4) eliminating calcium ion influx. Our results conclusively show that astaxanthin has the merit as a potential neuron protectant.
Control of stationary cross-flow modes in a Mach 3.5 boundary layer using patterned passive and active roughness
Authors: Schuele Chan Yong , Corke Thomas C. , Matlis Eric
Published: February 2013

Spanwise-periodic roughness designed to excite selected wavelengths of stationary cross-flow modes was investigated in a three-dimensional boundary layer at Mach 3.5. The test model was a sharp-tipped$1{4}^{\circ } $right-circular cone. The model and integrated sensor traversing system were placed in the Mach 3.5 supersonic low disturbance tunnel (SLDT) equipped with an axisymmetric ‘quiet design’ nozzle at NASA Langley Research Center. The model was oriented at a$4. {2}^{\circ } $angle of attack to produce a mean cross-flow velocity component in the boundary layer over the cone. The research examined both passive and active surface roughness. The passive roughness consisted of indentations (dimples) that were evenly spaced around the cone at an axial location that was just upstream of the first linear stability neutral growth branch for cross-flow modes. The active roughness consisted of an azimuthal array of micrometre-sized plasma actuators that were designed to produce the effect of passive surface bumps. Two azimuthal mode numbers of the passive and active patterned roughness were examined. One had an azimuthal mode number that was in the band of initially amplified stationary cross-flow modes. This was intended to represent a controlled baseline condition. The other azimuthal mode number was designed to suppress the growth of the initially amplified stationary cross-flow modes and thereby increase the transition Reynolds number. The results showed that the stationary cross-flow modes were receptive to both the passive and active patterned roughness. Only the passive roughness was investigated at a unit Reynolds number where transition would occur on the cone. Transition front measurements using the Preston tube approach indicated that the transition Reynolds number had increased by 35 % with the subcritical wavenumber roughness compared with the baseline smooth tip cone, and by 40 % compared with the critical wavenumber roughness. Based on the similarities in the response of the stationary cross-flow modes with the active roughness, we expect it would produce a similar transition delay.
Nonlinear dust–ion acoustic waves in a dusty plasma with non-extensive electrons and ions
Authors: BACHA MUSTAPHA , TRIBECHE MOULOUD
Published: February 2013

Using the reductive perturbation approach, dust–ion acoustic solitons and double layers (DLs) have been studied in a dust–electron–positron–ion (d-e-p-i) plasma composed of q-distributed electrons and positrons, warm fluid ions, and a fraction of immobile dust grains. Existence domains of either solitary waves or DLs are presented and their parametric dependence determined. It is found that particle non-extensivity, dust concentration and positron concentration may drastically affect these existence domains and may play a key role in defining the polarity of these localized structures. Our results should assist in interpreting the nonlinear structures that may occur in astrophysical environments.
Race and Recruitment in the Indian Army: 1880–1918
Authors: ROY KAUSHIK
Published: February 2013

In 1914, the Indian Army was deployed against the enemies of the British Empire. This paper analyses the administrative mechanism as well as the imperial assumptions and attitudes which shaped the recruitment policy of the Indian Army during the First World War. From the late nineteenth century, the Martial Race theory (a bundle of contradictory ideas) shaped the recruitment policy. With certain modifications, this theory remained operational to the first decade of the twentieth century. The construction of the ‘martial races’ enabled the British to play-off different communities against each other to prevent the emergence of a unified anti-British sentiment among the colonized. During the Great War, faced with the rising demands of manpower, the army was forced to modify the Martial Race theory. However, a conscript army did not emerge in British-India. This was due to imperial policies, the inherent social divisions of Indian society, and because the demands for military manpower remained relatively low in comparison to India's demographic resources. Due to innovations in the theory and praxis of recruitment, the volume of recruitment showed a linear increase from 1914 to 1918, with maximum intensification of recruitment occurring during 1917 and 1918. But as the war ended in November 1918, despite the entry of several new communities, the bulk of the Indian Army still came from the traditional martial races.
Worlds beyond Westphalia: Daoist dialectics and the ‘China threat’
Authors: LING L. H. M.
Published: February 2013

Discourse in the US/West that a rising China threatens world order serves no national interest or international purpose. It subscribes only to Westphalian anxieties about the Other. Drawing on Daoist dialectics, this article shows how we can reframe this issue by revealing the complicities that bind even seemingly intractable opposites, thereby undermining the rationale for violence. By recognising the ontological parity between (US/Western) Self and (Chinese/non-Western) Other, we may begin to shift IR/world politics from hegemony to engagement, the ‘tragedy’ of great power politics to the freedom of discovery and creativity.
Pathways to global democracy? Escaping the statist imaginary
Authors: LITTLE ADRIAN , MACDONALD KATE
Published: February 2013

Critics of global democracy have often claimed that the social and political conditions necessary for democracy to function are not met at the global level, and are unlikely to be in the foreseeable future. Such claims are usually developed with reference to national democratic institutions, and the social conditions within national democratic societies that have proved important in sustaining them. Although advocates of global democracy have contested such sceptical conclusions, they have tended to accept the method of reasoning from national to global contexts on which they are based. This article critiques this method of argument, showing that it is both highly idealised in its characterisation of national democratic practice, and overly state-centric in its assumptions about possible institutional forms that global democracy might take. We suggest that if aspiring global democrats – and their critics – are to derive useful lessons from social struggles to create and sustain democracy within nation states, a less idealised and institutionally prescriptive approach to drawing global lessons from national experience is required. We illustrate one possible such approach with reference to cases from both national and global levels, in which imperfect yet meaningful democratic practices have survived under highly inhospitable – and widely varying – conditions.
The Archaeology of Mind: It's Not What You Think
Authors: Barrett John C.
Published: February 2013

Narratives of human evolution place considerable emphasis upon human cognitive development resulting from the evolution of brain architecture and witnessed by the production of ‘symbolic’ material culture. Recent work has modified the narrative to the extent that cognitive development is treated as the product of humanity's ability to download certain aspects of brain functionality, such as the storage of information, into external media. This article questions the centrality given to the history of brain architecture as determinate of human cognition by rejecting the widespread assumption that cognition trades in representations, either stored internally in the brain or downloaded externally into cultural media. The alternative, offered here, is that human cognitive development was constructed through the development of joint attention made possible by the anatomical development of hominins and that this sustained a shared empathy between social agents in their practical understanding of the qualities of materiality.
Ritual, Recycling and Recontextualization: Putting the Concealed Shoe into Context
Authors: Houlbrook Ceri
Published: February 2013

The concealed shoe is, possibly by design, shrouded in mystery. All that is known for certain on this subject is that a large number of shoes, usually old and damaged, were concealed in various, unconventional locations within buildings throughout England, and that this practice was particularly popular during the eighteenth and nineteenth centuries. Other than these few facts, all other information on the subject is speculation. With no contemporaneous written sources on the practice of concealing shoes, this article will utilize the archaeological evidence in order to ascertain the motivations behind the act of concealment. An analysis of two case studies of concealed shoe caches from North Yorkshire, with a particular focus on their locations and conditions, will hopefully prove invaluable in the investigation into this unusual practice, together with an examination of the relevant folk beliefs and superstitions of the period. It will also be questioned where the concealed shoe stands in relation to our everyday classificatory systems. As a marginal, mutable object, the concealed shoe boasts a highly complex biography, calling into question the pertinence of such categories as valuable/rubbish, and particular attention will be given to the shoes’ numerous recontextualizations, from practical footwear, to apotropaic device, to archaeological artefact; transitions which I have dubbed ‘ritual recycling’.
Des points fixes communs pour des difféomorphismes de qui commutent et préservent une mesure de probabilité
Authors: Béguin F. , Le Calvez P. , Firmo S. , Miernowski T.
Published: February 2013

Nous montrons des résultats d’existence de points fixes communs pour des homéomorphismes du plan ${ \mathbb{R} }^{2} $ ou la sphère ${ \mathbb{S} }^{2} $, qui commutent deux à deux et préservent une mesure de probabilité. Par exemple, nous montrons que des ${C}^{1} $-difféomorphismes ${f}_{1} , \ldots , {f}_{n} $ de ${ \mathbb{S} }^{2} $ suffisamment proches de l’identité, qui commutent deux à deux, et qui préservent une mesure de probabilité dont le support n’est pas réduit à un point, ont au moins deux points fixes communs.
Chemotherapie-Nebenwirkungen an Haut und Schleimhäuten
Authors: Trojan  , Borelli
Published: February 2013

Des effets indésirables de la chimiothérapie se manifestent souvent sur la peau. L'alopécie et la stomatite sont les plus fréquents. En particulier les réactions des muqueuses peuvent limiter la dose ou en cas d'infection secondaire mettre le patient en danger. Des changements des ongles ou des hyperpigmentations sont des problèmes cosmétiques. Pour le diagnostic des maladies spécifiques comme le syndrome acral d'erythrodysesthésie ou l'hidradénite eccrine neutrophile, la connaissance de l'image clinique est nécessaire. Des interactions avec la radiothérapie ou la lumière UV peuvent aggraver ou faire apparaître des réactions sur la peau. On peut observer également des réactions semblables avec des nouvelles substances ayant des mécanismes tout à fait différents et des thérapeutiques immunitaires comme les anticorps monoclonaux.
Embryonale und adulte Stammzellen
Authors: Englert
Published: February 2013

Stammzellen besitzen ein unbeschränktes Regenerationspotential und können die Identität verschiedener, differenzierter Zellen annehmen. Im Falle der embryonalen Stammzellen können sogar alle verschiedenen Zellen eines Organismus generiert werden. Jüngst rückt auch das bislang unterschätzte Differenzierungspotential adulter Stammzellen in den Mittelpunkt des Interesses. Diese Befunde haben neue Perspektiven unter anderem in der Transplantationsmedizin und der Zelltherapie für degenerative Erkrankungen eröffnet. Bis zur Realisierung dieser Möglichkeiten müssen allerdings sowohl ethische als auch wissenschaftlich-technische Hürden überwunden werden, die zum Beispiel in der geringen Verfügbarkeit der Zellen und der Möglichkeit von Abstoßungsreaktionen begründet liegen.
The economics of creative research
Authors: Couée Ivan
Published: February 2013

Scientific research is increasingly subject to benchmarking and ratings that inevitably influence funding and hiring decisions. This trend of applying economic measures to creative endeavour could well undermine both progress and academic freedom.
Inositides—confusion and clarification in Shangri‐La
Authors: Irvine Robin
Published: February 2013

The meeting ‘Inositide Signalling in Health and Disease’, sponsored and organized by the National Centre for Biological Research, Bangalore, and the Indian Academy of Sciences, was held in late November 2012 in the luxurious destination of Orange County Resort, Coorg, India.
Coupling biocatalysis and click chemistry: one-pot two-step convergent synthesis of enantioenriched 1,2,3-triazole-derived diols
Authors: Cuetos Aníbal , Bisogno Fabricio R. , Lavandera Iván , Gotor Vicente
Published: February 2013

The combination of biocatalysis and ‘click’ chemistry is shown to obtain chiral 1,2,3-triazole diols in a fully convergent one-pot two-step synthesis.
An exchangeable-tip scanning probe instrument for the analysis of combinatorial libraries of electrocatalysts
Authors: Rus Eric D. , Wang Hongsen , Legard Anna E. , Ritzert Nicole L. , Bruce Van Dover Robert , Abruña Héctor D.
Published: February 2013

A combined scanning differential electrochemical mass spectrometer (SDEMS)-scanning electrochemical microscope (SECM) apparatus is described. The SDEMS is used to detect and spatially resolve volatile electrochemically generated species at the surface of a substrate electrode. The SECM can electrochemically probe the reactivity of the surface and also offers a convenient means of leveling the sample. It is possible to switch between these two different scanning tips and techniques without moving the sample and while maintaining potential control of the substrate electrode. A procedure for calibration of the SDEMS tip-substrate separation, based upon the transit time of electrogenerated species from the substrate to the tip is also described. This instrument can be used in the characterization of combinatorial libraries of direct alcohol fuel cell anode catalysts. The apparatus was used to analyze the products of methanol oxidation at a Pt substrate, with the SDEMS detecting carbon dioxide and methyl formate, and a PtPb-modified Pt SECM tip used for the selective detection of formic acid. As an example system, the electrocatalytic methanol oxidation activity of a sputter-deposited binary PtRu composition spread in acidic media was analyzed using the SDEMS. These results are compared with those obtained from a pH-sensitive fluorescence assay.
Gyration tensor based analysis of the shapes of polymer chains in an attractive spherical cage
Authors: Arkın Handan , Janke Wolfhard
Published: February 2013

In a recent computational study, we found highly structured conformations for the polymer-attractive sphere model system. Those conformations are of highly ordered spherical shape or form two-dimensional planar, compact to extended, random coil structures. The observed conformations range from desorbed to partially or even completely adsorbed. In order to present their shape characteristics, here we calculate the gyration tensor and related shape descriptors.
Combined-hyperbolic-inverse-power-representation of potential energy surfaces: A preliminary assessment for $\bf H_3$H3 and $\bf HO_2$HO2
Authors: Varandas A. J. C.
Published: February 2013

The purpose is to fit an accurate smooth function of the many-body expansion type to a multidimensional large data set using a basis-set type method. By adopting a combined-hyperbolic-inverse-power-representation for the basis, the novel approach is tested in detail for the ground electronic state of tri-hydrogen and hydroperoxyl systems, assuming that their potential energy surfaces are single-sheeted representable. It is also shown that the method can be easily applicable to potential energy curves by considering as prototypes molecular oxygen and the hydroxyl radical.
Quantum dynamical structure factor of liquid neon via a quasiclassical symmetrized method
Authors: Monteferrante Michele , Bonella Sara , Ciccotti Giovanni
Published: February 2013

We apply the phase integration method for quasiclassical quantum time correlation functions [M. Monteferrante, S. Bonella, and G. Ciccotti, Mol. Phys. 109, 3015 (2011)10.1080/00268976.2011.619506] to compute the dynamic structure factor of liquid neon. So far the method had been tested only on model systems. By comparing our results for neon with experiments and previous calculations, we demonstrate that the scheme is accurate and efficient also for a realistic model of a condensed phase system showing quantum behavior.
State-to-state three-atom time-dependent reactive scattering in hyperspherical coordinates
Authors: Crawford Jeff , Parker Gregory A.
Published: February 2013

We present a time-dependent, hyperspherical wave packet method for calculating three-atom state-to-state S-matrix elements. The wave packet is propagated in time using adiabatically adjusting, principal axes hyperspherical coordinates that treat all arrangement channels equivalently, allowing the simultaneous analysis of the products in all three arrangement channels. We take advantage of the symmetry of the potential energy surface and decompose the initial wave packet into its component irreducible representations, propagating each component separately. Each irreducible representation component of the wave packet is analyzed by projecting it onto the hyperspherical basis at a fixed, asymptotic hyperradius, and irreducible representation dependent S-matrix elements are obtained by matching the hyperspherical projections to symmetry-adapted Jacobi coordinate boundary conditions. We obtain arrangement channel-dependent S-matrix elements as linear combinations of the irreducible representation dependent elements. State-to-state H + H2 and F + H2 results for zero total angular momentum are presented.
New insights for accurate chemically specific measurements of slow diffusing molecules
Authors: Hou Jianbo , Madsen Louis A.
Published: February 2013

Investigating the myriad features of molecular transport in materials yields fundamental information for understanding processes such as ion conduction, chemical reactions, and phase transitions. Molecular transport especially impacts the performance of ion-containing liquids and polymeric materials when used as electrolytes and separation media, with applications encompassing battery electrolytes, reverse-osmosis membranes, mechanical transducers, and fuel cells. Nuclear magnetic resonance (NMR) provides a unique probe of molecular translations by allowing measurement of all mobile species via spectral selectivity, access to a broad range of transport coefficients, probing of any material direction, and investigation of variable lengthscales in a material, thus, tying morphology to transport. Here, we present new concepts to test for and guarantee robust diffusion measurements. We first employ a standard pulsed-field-gradient (PFG) calibration protocol using 2H2O and obtain expected results, but we observe crippling artifacts when measuring 1H-glycerol diffusion with the same experimental parameters. A mathematical analysis of 2H2O and glycerol signals in the presence of PFG transients show tight agreement with experimental observations. These analyses lead to our principal findings that (1) negligible artifacts observed with low gyromagnetic ratio (γ) nuclei may become dominant when observing high γ nuclei, and (2) reducing the sample dimension along the gradient direction predictably reduces non-ideal behaviors of NMR signals. We further provide a useful quantitative strategy for error minimization when measuring diffusing species slower than the one used for gradient calibration.
Resistive switching near electrode interfaces: Estimations by a current model
Authors: Schroeder Herbert , Zurhelle Alexander , Stemmer Stefanie , Marchewka Astrid , Waser Rainer
Published: February 2013

The growing resistive switching database is accompanied by many detailed mechanisms which often are pure hypotheses. Some of these suggested models can be verified by checking their predictions with the benchmarks of future memory cells. The valence change memory model assumes that the different resistances in ON and OFF states are made by changing the defect density profiles in a sheet near one working electrode during switching. The resulting different READ current densities in ON and OFF states were calculated by using an appropriate simulation model with variation of several important defect and material parameters of the metal/insulator (oxide)/metal thin film stack such as defect density and its profile change in density and thickness, height of the interface barrier, dielectric permittivity, applied voltage. The results were compared to the benchmarks and some memory windows of the varied parameters can be defined: The required ON state READ current density of 105 A/cm2 can only be achieved for barriers smaller than 0.7 eV and defect densities larger than 3 × 1020 cm−3. The required current ratio between ON and OFF states of at least 10 requests defect density reduction of approximately an order of magnitude in a sheet of several nanometers near the working electrode.
A variational formulation of electrostatics in a medium with spatially varying dielectric permittivity
Authors: Jadhao Vikram , Solis Francisco J. , Olvera de la Cruz Monica
Published: February 2013

In biological and synthetic materials, many important processes involve charges that are present in a medium with spatially varying dielectric permittivity. To accurately understand the role of electrostatic interactions in such systems, it is important to take into account the spatial dependence of the permittivity of the medium. However, due to the ensuing theoretical and computational challenges, this inhomogeneous dielectric response of the medium is often ignored or excessively simplified. We develop a variational formulation of electrostatics to accurately investigate systems that exhibit this inhomogeneous dielectric response. Our formulation is based on a true energy functional of the polarization charge density. The defining characteristic of a true energy functional is that at its minimum it evaluates to the actual value of the energy; this is a feature not found in many commonly used electrostatic functionals. We explore in detail the charged systems that exhibit sharp discontinuous change in dielectric permittivity, and we show that for this case our functional reduces to a functional of only the surface polarization charge density. We apply this reduced functional to study model problems for which analytical solutions are well known. We demonstrate, in addition, that the functional has many properties that make it ideal for use in molecular dynamics simulations.
Compressed correlation functions and fast aging dynamics in metallic glasses
Authors: Ruta B. , Baldi G. , Monaco G. , Chushkin Y.
Published: February 2013

We present x-ray photon correlation spectroscopy measurements of the atomic dynamics in a Zr67Ni33 metallic glass, well below its glass transition temperature. We find that the decay of the density fluctuations can be well described by compressed, thus faster than exponential, correlation functions which can be modeled by the well-known Kohlrausch-Williams-Watts function with a shape exponent β larger than one. This parameter is furthermore found to be independent of both waiting time and wave-vector, leading to the possibility to rescale all the correlation functions to a single master curve. The dynamics in the glassy state is additionally characterized by different aging regimes which persist in the deep glassy state. These features seem to be universal in metallic glasses and suggest a nondiffusive nature of the dynamics. This universality is supported by the possibility of describing the fast increase of the structural relaxation time with waiting time using a unique model function, independently of the microscopic details of the system.
Layer-by-layer shuttered molecular-beam epitaxial growth of superconducting Sr1–xLaxCuO2 thin films
Authors: Maritato L. , Galdi A. , Orgiani P. , Harter J. W. , Schubert J. , Shen K. M. , Schlom D. G.
Published: February 2013

Superconducting Sr1–xLaxCuO2 thin films have been grown on GdScO3 substrates by reflection high-energy electron diffraction calibrated layer-by-layer molecular-beam epitaxy. X-ray diffraction analysis has confirmed the infinite layer structure after an in situ vacuum annealing step. In situ photoemission spectroscopy indicates that the vacuum annealing step employed immediately after film growth to achieve superconducting films results in oxygen loss from the films. The superconducting critical temperature depends on the La content x, with the highest value obtained for x∼0.10. Resistivity as a function of temperature ρ(T) curves of optimally doped samples show a T2 temperature dependence characteristic of a scattering process where electron-electron interactions dominate.
Superconductivity at 5 K in NdO0.5F0.5BiS2
Authors: Jha Rajveer , Kumar Anuj , Kumar Singh Shiva , Awana V. P. S.
Published: February 2013

We report appearance of superconductivity at 5 K in NdO0.5F0.5BiS2 and supplement the discovery [Demura et al., e-print arXiv:1207.5248] of the same in layered sulfide based compound. Detailed structural analysis showed that the studied compound is crystallized in tetragonal P4/nmm space group with lattice parameters a = 3.9911(3) Å and c = 13.3830(2) Å. Bulk superconductivity is established in NdO0.5F0.5BiS2 at 5 K by both transport and magnetic measurements. Electrical transport measurements showed superconducting Tc onset at 5.2 K and Tc (ρ = 0) at 4.7 K. Under applied magnetic field, both Tc onset and Tc (ρ = 0) decrease to lower temperatures and an upper critical field [Hc2(0)] of above 23 kOe is estimated. Isothermal magnetization exhibited typical type-II behavior with lower critical field (Hc1) of around 25 Oe. Specific heat [Cp(T)] is investigated in the temperature range of 1.9–50 K in zero external magnetic field. A Schottky-type anomaly is observed at low temperature below 7 K.
High pressure phase transition of ZnO/SiO2 core/shell nanospheres
Authors: Cheng Benyuan , Li Quanjun , Yao Mingguang , Liu Ran , Li Dongmei , Zou Bo , Cui Tian , Liu Jing , Chen Zhiqiang , Zhao Zhihui , Yang Bai , Liu Bingbing
Published: February 2013

The structural phase transition of ZnO/SiO2 core/shell nanospheres was studied under high pressure using synchrotron X-ray diffraction. The results indicated that the wurtzite structure of the ZnO core is stable up to 11.5 GPa, and then transforms into rocksalt phase. The onset transition pressure is higher than those of the bulk and nano ZnO. It is worth noting that the phase transition from wurtzite to rocksalt is irreversible, which is obviously different from the uncapped bulk and nano ZnO. The pure rocksalt structure ZnO was first obtained at ambient conditions without catalyst or high temperature treatment. We suggested that the SiO2 shells play important roles in the phase transition of inner ZnO cores. The effects of the SiO2 shells on the phase transition of ZnO cores were discussed.
High pressure and high temperature stabilization of cubic AlN in Ti0.60Al0.40N
Authors: Norrby N. , Lind H. , Parakhonskiy G. , Johansson M. P. , Tasnádi F. , Dubrovinsky L. S. , Dubrovinskaia N. , Abrikosov I. A. , Odén M.
Published: February 2013

In the present work, the decomposition of unstable arc evaporated Ti0.6Al0.4N at elevated temperatures and quasihydrostatic pressures has been studied both experimentally and by first-principles calculations. High pressure and high temperature (HPHT) treatment of the samples was realized using the multi anvil press and diamond anvil cell techniques. The products of the HPHT treatment of Ti0.6Al0.4N were investigated using x-ray diffractometry and transmission electron microscopy. Complimentary calculations show that both hydrostatic pressure and high temperature stabilize the cubic phase of AlN, which is one of the decomposition products of Ti0.6Al0.4N. This is in agreement with the experimental results which in addition suggest that the presence of Ti in the system serves to increase the stability region of the cubic c-AlN phase. The results are industrially important as they show that Ti0.6Al0.4N coatings on cutting inserts do not deteriorate faster under pressure due to the cubic AlN to hexagonal AlN transformation.
Active modulation of wavelength and radiation direction of fluorescence via liquid crystal-tuned surface plasmons
Authors: Li Haibo , Xu Shuping , Gu Yuejiao , Wang Kai , Xu Weiqing
Published: February 2013

Plasmonic elements which can tune light in micro-nano dimension have attracted much attention nowadays. However, available approaches for externally manipulating surface plasmons (SPs) are still in great demand. Here, we described an effective approach to modulate SPs by voltage signal. Through adding a liquid crystal cell with a dye layer to the Kretschmann configuration, the wavelength and the radiation direction of the fluorescence of dye can be modulated continuously and reversibly by changing applied voltages. This design has great application potentials in the development of tunable luminescent devices and smart plasmonic elements.
Chaos M-ary modulation and demodulation method based on Hamilton oscillator and its application in communication
Authors: Fu Yongqing , Li Xingyuan , Li Yanan , Yang Wei , Song Hailiang
Published: February 2013

Chaotic communication has aroused general interests in recent years, but its communication effect is not ideal with the restriction of chaos synchronization. In this paper a new chaos M-ary digital modulation and demodulation method is proposed. By using region controllable characteristics of spatiotemporal chaos Hamilton map in phase plane and chaos unique characteristic, which is sensitive to initial value, zone mapping method is proposed. It establishes the map relationship between M-ary digital information and the region of Hamilton map phase plane, thus the M-ary information chaos modulation is realized. In addition, zone partition demodulation method is proposed based on the structure characteristic of Hamilton modulated information, which separates M-ary information from phase trajectory of chaotic Hamilton map, and the theory analysis of zone partition demodulator's boundary range is given. Finally, the communication system based on the two methods is constructed on the personal computer. The simulation shows that in high speed transmission communications and with no chaos synchronization circumstance, the proposed chaotic M-ary modulation and demodulation method has outperformed some conventional M-ary modulation methods, such as quadrature phase shift keying and M-ary pulse amplitude modulation in bit error rate. Besides, it has performance improvement in bandwidth efficiency, transmission efficiency and anti-noise performance, and the system complexity is low and chaos signal is easy to generate.
Nucleation pathways on complex networks
Authors: Shen Chuansheng , Chen Hanshuang , Ye Miaolin , Hou Zhonghuai
Published: February 2013

Identifying nucleation pathway is important for understanding the kinetics of first-order phase transitions in natural systems. In the present work, we study nucleation pathway of the Ising model in homogeneous and heterogeneous networks using the forward flux sampling method, and find that the nucleation processes represent distinct features along pathways for different network topologies. For homogeneous networks, there always exists a dominant nucleating cluster to which relatively small clusters are attached gradually to form the critical nucleus. For heterogeneous ones, many small isolated nucleating clusters emerge at the early stage of the nucleation process, until suddenly they form the critical nucleus through a sharp merging process. Moreover, we also compare the nucleation pathways for different degree-mixing networks. By analyzing the properties of the nucleating clusters along the pathway, we show that the main reason behind the different routes is the heterogeneous character of the underlying networks.
Scattering and the relationship between quantum efficiency and emittance
Authors: Jensen Kevin L.
Published: February 2013

Simple models of the quantum efficiency (QE) and emittance (εn,rms) of metals are based on the neglect of scattered electrons to the emission current. The leading order terms in the Fowler-Dubridge equation for QE and the Dowell-Schmerge equation for emittance entail QE∝εn4. Here, a method to account for next-order contributions and the impact of scattered electrons to the relation is given.
Optoelectronic measurement of x-ray synchrotron pulses: A proof of concept demonstration
Authors: Durbin Stephen M. , Mahmood Aamer , Caffee Marc , Savikhin Sergei , Dufresne Eric M. , Wen Haidan , Li Yuelin
Published: February 2013

Optoelectronic detection using photoconductive coplanar stripline devices has been applied to measuring the time profile of x-ray synchrotron pulses, a proof of concept demonstration that may lead to improved time-resolved x-ray studies. Laser sampling of current vs time delay between 12 keV x-ray and 800 nm laser pulses reveal the ∼50 ps x-ray pulse width convoluted with the ∼200 ps lifetime of the conduction band carriers. For GaAs implanted with 8 MeV protons, a time profile closer to the x-ray pulse width is observed. The protons create defects over the entire depth sampled by the x-rays, trapping the x-ray excited conduction electrons and minimizing lifetime broadening of the electrical excitation.
A trilayer architecture for polymer photoconductors
Authors: Jin Zhiwen , Wang Jizheng
Published: February 2013

A trilayer architecture is designed for polymer photoconductors. In such a structure, photogenerated electrons in poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid ethyl ester (P3HT:PCBM) blend film will flow into a TiOx layer beneath and then diffuse into a underlying PCBM layer. Photogenerated holes and electrons are thus efficiently separated by the spacer TiOx, and, respectively, transport in P3HT and PCBM films, carrier recombination is thereby greatly suppressed. As a result, photocurrent of the PCBM/TiOx/P3HT:PCBM trilayer structure increases more than 200 times over that of the conventional P3HT:PCBM single layer device.
800 meV localization energy in GaSb/GaAs/Al0.3Ga0.7As quantum dots
Authors: Nowozin T. , Bonato L. , Högner A. , Wiengarten A. , Bimberg D. , Lin Wei-Hsun , Lin Shih-Yen , Reyner C. J. , Liang Baolai L. , Huffaker D. L.
Published: February 2013

The localization energies, capture cross sections, and storage times of holes in GaSb quantum dots (QDs) are measured for three GaSb/GaAs QD ensembles with different QD sizes. The structural properties, such as height and diameter, are determined by atomic force microscopy, while the electronic properties are measured using deep-level transient spectroscopy. The various QDs exhibit varying hole localization energies corresponding to their size. The maximum localization energy of 800 (±50) meV is achieved by using additional Al0.3Ga0.7As barriers. Based on an extrapolation, alternative material systems are proposed to further increase the localization energy and carrier storage time of QDs.
Fusing catalase to an alkane-producing enzyme maintains enzymatic activity by converting the inhibitory byproduct H
2
O
2
to the cosubstrate O
2
Authors: Andre Carl , Kim Sung Won , Yu Xiao-Hong , Shanklin John
Published: February 2013

Biologically produced alkanes represent potential renewable alternatives to petroleum-derived chemicals. A cyanobacterial pathway consisting of acyl–Acyl Carrier Protein reductase and an aldehyde-deformylating oxygenase (ADO) converts acyl–Acyl Carrier Proteins into corresponding n-1 alkanes via aldehyde intermediates in an oxygen-dependent manner (K
m
for O
2
, 84 ± 9 µM). In vitro, ADO turned over only three times, but addition of more ADO to exhausted assays resulted in additional product formation. While evaluating the peroxide shunt to drive ADO catalysis, we discovered that ADO is inhibited by hydrogen peroxide (H
2
O
2
) with an apparent K
i
of 16 ± 6 µM and that H
2
O
2
inhibition is of mixed-type with respect to O
2
. Supplementing exhausted assays with catalase (CAT) restored ADO activity, demonstrating that inhibition was reversible and dependent on H
2
O
2
, which originated from poor coupling of reductant consumption with alkane formation. Kinetic analysis showed that long-chain (C14–C18) substrates follow Michaelis–Menten kinetics, whereas short and medium chains (C8–C12) exhibit substrate inhibition. A bifunctional protein comprising an N-terminal CAT coupled to a C-terminal ADO (CAT–ADO) prevents H
2
O
2
inhibition by converting it to the cosubstrate O
2
. Indeed, alkane production by the fusion protein is observed upon addition of H
2
O
2
to an anaerobic reaction mix. In assays, CAT–ADO turns over 225 times versus three times for the native ADO, and its expression in
Escherichia coli
increases catalytic turnovers per active site by fivefold relative to the expression of native ADO. We propose the term “protection via inhibitor metabolism” for fusion proteins designed to metabolize inhibitors into noninhibitory compounds.