bluuebunny/crossref_metadata_2025 huggingface dataset:
Einfach ethisch entscheiden
Authors: Hecke Marcus
Published: December 2013

Kann, muss oder sollte eine begonnene Therapie fortgesetzt, intensiviert oder eingestellt werden? Nicht selten sind es schwierige Fragen wie diese, die sich dem behandelnden Team, dem Patienten aber auch Angehörigen stellen. Das Buch „Klinische Ethik – METAP“ möchte Mitgliedern des therapeutischen Teams eine Anleitung und Hilfestellung bieten, um ethische Problemstellungen zu erkennen, sie systematisch zu bearbeiten und letztlich einer angemessen Entscheidung entgegenzuführen. Die Buchstabenfolge METAP steht für Modular, Ethik, Therapieentscheide, Allokation und Prozess.
Mechanisms of IL‐8 suppression by Treponema denticola in gingival epithelial cells
Authors: Jo Ah‐ram , Baek Keum Jin , Shin Ji Eun , Choi Youngnim
Published: December 2013

The purpose of this study was to investigate the mechanism(s) of interleukin (IL)‐8 suppression by Treponema denticola, one of the major periodontal pathogens, in gingival epithelial cells. Immortalized human gingival epithelial HOK‐16B cells were infected with wild‐type (WT), dentilisin‐deficient (K1) or flagellin‐deficient (flgE) T. denticola in the presence or absence of 2% human serum for 24 h. The levels of IL‐8 expression were measured with real‐time reverse transcription PCR and ELISA. In the absence of human serum, the WT and flgE, but not K1, substantially reduced not only the levels of IL‐8 protein but also of IL‐8 mRNA. Such downregulation of IL‐8 mRNA was independent of bacterial invasion. Degradation of cytokine mixture by the WT, K1 and flgE revealed dentilisin‐dependent preferential degradation of tumor necrosis factor (TNF)‐α, an IL‐8‐inducing cytokine. WT and flgE significantly decreased the levels of TNFα secreted by HOK‐16B cells, suggesting modulation of IL‐8 through dentilisin‐mediated degradation of TNFα. The addition of human serum to the culture potentiated the suppressive effect of T. denticola, resulting in substantial reductions of IL‐8 and TNFα levels, even by K1. The serum‐dependent effects of T. denticola were attributed to its ability to suppress the accumulation of intracellular reactive‐oxygen species (ROS), a group of ubiquitous signaling molecules. Pretreatment with an antioxidant suppressed TNFα‐induced IL‐8 expression, confirming the role of ROS in TNFα signaling. Collectively, T. denticola targeted a key inflammatory cytokine and its signaling molecule to modulate the host innate immune response, which provides a new insight into modulation of host immunity by a periodontal pathogen.
Associations between surface markers on blood monocytes and carotid atherosclerosis in HIV‐positive individuals
Authors: Westhorpe Clare L V , Maisa Anna , Spelman Tim , Hoy Jennifer F , Dewar Elizabeth M , Karapanagiotidis Sofie , Hearps Anna C , Cheng Wan‐Jung , Trevillyan Janine , Lewin Sharon R , Sviridov Dmitri , Elliott Julian H , Jaworowski Anthony , Dart Anthony M , Crowe Suzanne M
Published: December 2013

Chronic HIV infection is associated with increased risk of cardiovascular disease (CVD), including in patients with virological suppression. Persistent innate immune activation may contribute to the development of CVD via activation of monocytes in these patients. We investigated whether changes in monocyte phenotype predict subclinical atherosclerosis in virologically suppressed HIV‐positive individuals with low cardiovascular risk. We enroled 51 virologically suppressed HIV‐positive individuals not receiving protease inhibitors or statins and 49 age‐matched uninfected controls in this study. Carotid artery intima‐media thickness (cIMT) was used as a surrogate marker for CVD, and traditional risk factors, including Framingham risk scores, were recorded. Markers of monocyte activation (CD14, CD16, CCR2, CX3CR1, CD38, HLA‐DR and CD11b) were measured in whole‐blood samples by flow cytometry. Associations were assessed using univariate and multivariate median regressions. Median cIMT was similar between HIV‐positive and HIV‐negative participants (P=0.3), although HIV‐positive patients had significantly higher Framingham risk score (P=0.009) and systemic inflammation. Expression of two monocyte markers, CD11b and CX3CR1, independently predicted carotid artery thickness in HIV‐positive individuals after controlling for Framingham risk score (P=0.025 and 0.015, respectively). These markers were not predictive of carotid artery thickening in controls. Our study indicates that monocyte surface markers may serve as novel predictors of CVD in HIV‐positive individuals and is consistent with an important role for monocyte activation in the progression of HIV‐related cardiovascular pathology.
MicroRNA-33 regulates sterol regulatory element-binding protein 1 expression in mice
Authors: Horie Takahiro , Nishino Tomohiro , Baba Osamu , Kuwabara Yasuhide , Nakao Tetsushi , Nishiga Masataka , Usami Shunsuke , Izuhara Masayasu , Sowa Naoya , Yahagi Naoya , Shimano Hitoshi , Matsumura Shigenobu , Inoue Kazuo , Marusawa Hiroyuki , Nakamura Tomoyuki , Hasegawa Koji , Kume Noriaki , Yokode Masayuki , Kita Toru , Kimura Takeshi , Ono Koh
Published: December 2013

MicroRNAs (miRs) are small non-protein-coding RNAs that bind to specific mRNAs and inhibit translation or promote mRNA degradation. Recent reports have indicated that miR-33, which is located within the intron of sterol regulatory element-binding protein (SREBP) 2, controls cholesterol homoeostasis and may be a potential therapeutic target for the treatment of atherosclerosis. Here we show that deletion of miR-33 results in marked worsening of high-fat diet-induced obesity and liver steatosis. Using miR-33−/−Srebf1+/− mice, we demonstrate that SREBP-1 is a target of miR-33 and that the mechanisms leading to obesity and liver steatosis in miR-33−/− mice involve enhanced expression of SREBP-1. These results elucidate a novel interaction between SREBP-1 and SREBP-2 mediated by miR-33 in vivo.
A proposal for a novel impact factor as an alternative to the JCR impact factor
Authors: Yang Zu-Guo , Zhang Chun-Ting
Published: December 2013

One disadvantage of the JCR impact factor, the most commonly used assessment tool for ranking and evaluating scientific journals, is its inability in distinguishing among different shapes of citation distribution curves, leading to unfair evaluation of journals in some cases. This paper aims to put forward an alternative impact factor (IF′) that can properly reflect citation distributions. The two impact factors are linearly and positively correlated and have roughly the same order of magnitude. Because of the ability of IF′ in distinguishing among different shapes of citation distribution curves, IF′ may properly reflect the academic performance of a scientific journal in a way that is different from the JCR impact factor with some unique features that reward journals with highly cited papers. Therefore, it is suggested that IF′ could be used to complement the JCR impact factor.
Structural and computational insights into the versatility of cadmium binding to proteins
Authors: Friedman Ran
Published: December 2013

Cadmium can bind to a variety of other metal binding protein, which may explain its toxicity. Calculations add to the understanding of the chemistry of cadmium–protein interactions.
Dietary gallic acid and anthocyanin cytotoxicity on human fibrosarcoma HT1080 cells. A study on the mode of action
Authors: Filipiak Kamila , Hidalgo Maria , Silvan Jose Manuel , Fabre Benjamin , Carbajo Rodrigo J. , Pineda-Lucena Antonio , Ramos Ana , de Pascual-Teresa Beatriz , de Pascual-Teresa Sonia
Published: December 2013

Effects of dietary gallic acid and anthocyanins on HT1080. A biochemical, computational and NMR study on the mechanisms involved.
Colorimetric detection of Ag ions with graphene oxide in dimethylformamide
Authors: Li XiaoLiang , He Yong Wu , Ryu Jae Sung , Yang Sung Ik
Published: December 2013

We report on the selective and sensitive colorimetric detection of Ag+ in a dimethylformamide (DMF) solution in the presence of graphene oxide based on the surface plasmon resonance absorption of Ag nanoparticles (NPs).
Understanding the oriented-attachment growth of nanocrystals from an energy point of view: a review
Authors: Lv Weiqiang , He Weidong , Wang Xiaoning , Niu Yinghua , Cao Huanqi , Dickerson James H. , Wang Zhiguo
Published: December 2013

Experimental and theoretical findings on the energies associated with the oriented-attachment nanocrystal growth are systematically reviewed in this article.
A novel liquid template corrosion approach for layered silica with various morphologies and different nanolayer thicknesses
Authors: Yang Wanliang , Li Baoshan
Published: December 2013

A novel liquid template corrosion method is developed to synthesize layered silica with different morphologies.
Janus nanobelts: fabrication, structure and enhanced magnetic–fluorescent bifunctional performance
Authors: Ma Qianli , Yu Wensheng , Dong Xiangting , Wang Jinxian , Liu Guixia
Published: December 2013

Janus nanobelts with enhanced magnetic–fluorescent bifunctional performance have been successfully fabricated by a specially designed parallel spinneret electrospinning technology.
Charge separation in Pt-decorated CdSe@CdS octapod nanocrystals
Authors: Conca Erika , Aresti Mauro , Saba Michele , Casula Maria Francesca , Quochi Francesco , Mula Guido , Loche Danilo , Kim Mee Rahn , Manna Liberato , Corrias Anna , Mura Andrea , Bongiovanni Giovanni
Published: December 2013

CdSe@CdS octapod nanocrystals are decorated with Pt domains and their potential for solar photocatalysis is investigated with ultrafast optical spectroscopy.
Large-area fabrication of highly reproducible surface enhanced Raman substrate via a facile double sided tape-assisted transfer approach using hollow Au–Ag alloy nanourchins
Authors: Liu Zhen , Cheng Lin , Zhang Lei , Jing Chao , Shi Xin , Yang Zhongbo , Long Yitao , Fang Jixiang
Published: December 2013

A simple and facile double sided tape-assisted transfer method was exploited to fabricate surface enhanced Raman scattering (SERS) substrates with prominent uniformity and reproducibility.
BixLa1−xVO4 solid solutions: tuning of electronic properties via stoichiometry modifications
Authors: Kwolek Przemysław , Pilarczyk Kacper , Tokarski Tomasz , Lewandowska Kornelia , Szaciłowski Konrad
Published: December 2013

Bismuth-lanthanum vanadate solid solutions of tunable electronic and optical properties are promising materials for novel optoelectronic devices.
Wholly printed polypyrrole nanoparticle-based biosensors on flexible substrate
Authors: Weng Bo , Morrin Aoife , Shepherd Roderick , Crowley Karl , Killard Anthony J. , Innis Peter C. , Wallace Gordon G.
Published: December 2013

The development of inkjet printable polypyrrole(PPy)/enzyme bio-ink successfully introduce bio-selectivity of specific bio-moleculars into conducting polymers. This method is suitable for massive industrial biosensor production.
The influence of fluorocarbon chain and phosphorylcholine on the improvement of hemocompatibility: a comparative study in polyurethanes
Authors: Tan Dongsheng , Li Zhen , Yao Xuelin , Xiang Chunlan , Tan Hong , Fu Qiang
Published: December 2013

The synergistic effect of a fluorocarbon chain and phosphorylcholine groups on the improvement of hemocompatibility in polyurethanes was investigated.
Sterically demanding zinc(ii) phthalocyanines: synthesis, optical, electrochemical, nonlinear optical, excited state dynamics studies
Authors: Swain Debasis , Singh Radhakant , Singh Varun Kumar , Krishna Narra Vamsi , Giribabu Lingamallu , Rao Soma Venugopal
Published: December 2013

Sterically hindered molecules like the title compounds, combined with their strong NLO coefficients make them potential candidates for photonic applications.
A novel reduced leakage current modulation technique for Z‐source inverter used in photovoltaic systems
Authors: Erginer Volkan , Sarul Mustafa Hadi
Published: December 2013

In this study a novel modulation technique is proposed to reduce common mode leakage current in a three‐phase Z‐Source inverter used in a photovoltaic (PV) system. The proposed method reduces common mode current as well as common mode voltage (CMV); moreover, it reduces inverter output current total harmonic distortion at high switching frequencies. At first, previously presented techniques are summarised. Then, proposed technique is presented theoretically. Finally, conventional space vector modulation and the proposed modulation technique are simulated for a 10 kW PV power generation system. The validity of the proposed modulation technique is verified through MATLAB/Simulink. Simulations are performed for different load power factors and switching frequencies with considering real application parameters to provide a certain comparison between conventional and proposed modulation techniques. The results are analysed considering both CMV, leakage current and inverter output current quality, and the results verify effectiveness of the proposed technique.
Keep IT simple – the challenge of interlaced IT architecture at Gothaer Systems
Authors: Basten Dirk , Joosten Dominik , Mellis Werner , Wallmueller Cornelia
Published: December 2013

The German direct insurer Gothaer Insurance Group is among the largest insurance companies in Germany. In recent years, Gothaer was facing the challenge of replacing its existing collection systems. The replacement system was one of SAP's key modules for Insurance Solution, a standard software product called FS-CD (Financial Services-Collections and Disbursements). The first stage of the project significantly exceeded time and budget objectives. The second stage was expected to encounter serious technical problems. Consequently, the entire project was called into question. A meeting of the IT steering committee was scheduled at short notice to decide upon the project's continuance. This case chronicles the series of events leading to that upcoming steering committee meeting.
Multibump solutions for quasilinear elliptic equations with critical growth
Authors: Liu Jiaquan , Wang Zhi-Qiang , Wu Xian
Published: December 2013

The current paper is concerned with constructing multibump solutions for a class of quasilinear Schrödinger equations with critical growth. This extends the classical results of Coti Zelati and Rabinowitz [Commun. Pure Appl. Math. 45, 1217–1269 (1992)] for semilinear equations as well as recent work of Liu, Wang, and Guo [J. Funct. Anal. 262, 4040–4102 (2012)] for quasilinear problems with subcritical growth. The periodicity of the potentials is used to glue ground state solutions to construct multibump bound state solutions.
Hydrogenated TiO2 film for enhancing photovoltaic properties of solar cells and self-sensitized effect
Authors: He Hongcai , Yang Kui , Wang Ning , Luo Feifei , Chen Haijun
Published: December 2013

Hydrogenated TiO2 film was obtained by annealing TiO2 film at 350 °C for 2 h with hydrogen, and TiO2 films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO2 film and pristine TiO2 film. Through optical and electrochemical characterization, the hydrogenated TiO2 film showed enhanced absorption and narrowed band gap, as well as reduced TiO2 surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO2 as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO2 film, which excited electrons injecting internal conduction band of TiO2 to generate more photocurrent.
Remarks on Hamiltonian structures in G2-geometry
Authors: Cho Hyunjoo , Salur Sema , Todd A. J.
Published: December 2013

In this article, we treat G2-geometry as a special case of multisymplectic geometry and make a number of remarks regarding Hamiltonian multivector fields and Hamiltonian differential forms on manifolds with an integrable G2-structure; in particular, we discuss existence and make a number of identifications of the spaces of Hamiltonian structures associated to the two multisymplectic structures associated to an integrable G2-structure. Along the way, we prove some results in multisymplectic geometry that are generalizations of results from symplectic geometry.
Analysis of thermal conductivity of polymeric nanocomposites under mechanical loading
Authors: Yu Suyoung , Yang Seunghwa , Cho Maenghyo
Published: December 2013

When the plastic deformation is applied to neat polymer, the polymer chains are aligned and the thermal conductivity of neat polymer increases linearly along the loading direction. However, the thermal conductivity change of nanocomposites consisting of polymer matrix and nanofillers during plastic deformation is not simple. The volume fraction and size of nanofillers scarcely affect the structural change of polymer chains during the plastic deformation. In this study, the structural change of polymeric materials according to the mechanical loading and its effect on the thermal transport properties are investigated through a molecular dynamics simulation. To investigate the effects of nanofiller, its volume fraction, and size on the thermal transport properties, the unit cells of neat amorphous nylon 6 and nanocomposites consisting of amorphous nylon 6 matrix and spherical silica particles are prepared. The molecular unit cells are uniaxially stretched by applying constant strain along the loading directions. Then, non-equilibrium molecular dynamics (NEMD) simulations are performed to estimate the thermal conductivities during plastic deformation. The alignment of polymer chains is analyzed by tracing the orientation correlation function of each polymer molecule and the free volume change during the mechanical loading is also analyzed.
Theoretical study of AlnV+ clusters and their interaction with Ar
Authors: Fernández Eva María , Vega Andrés , Balbás Luis Carlos
Published: December 2013

Recently, it has been experimentally elucidated whether a V impurity in AlnV+ clusters occupies an external or an internal site by studying their interaction with argon as a function of cluster size [S. M. Lang, P. Claes, S. Neukermans, and E. Janssens, J. Am. Soc. Mass Spectrom. 22, 1508 (2011)]. In the work presented here we studied, by means of density functional theoretic calculations, the structural and electronic properties of AlnV+ clusters with n = 14–21 atoms, as well as the adsorption of a single Ar atom on them. For n < 17 the lowest energy structure of AlnV+ is related to that of the pure \documentclass[12pt]{minimal}\begin{document}${\rm Al}_{\rm n+1}^+$\end{document} Al n+1+ cluster with the V atom substituting a surface Al atom. For n ⩾ 17 the V impurity becomes embedded in the cluster, in agreement with the experimental results, and the clusters adopt a fcc-like structure instead of the icosahedral-like skeleton of pure \documentclass[12pt]{minimal}\begin{document}${\rm Al}_{\rm n+1}^+$\end{document} Al n+1+. We have studied the binding energy per atom, the second energy difference, and the V and Al atom separation energies, in comparison with those of pure \documentclass[12pt]{minimal}\begin{document}${\rm Al}_{\rm n+1}^+$\end{document} Al n+1+. We also studied the adsorption of atomic Ar on endohedral and exohedral V doped clusters. The optimized Ar adsorption geometries are formed with Ar on top of a surface atom (V for n < 17, and Al for n ⩾ 17) without noticeable structural distortion of the host cluster. At the critical size (n = 17) of the exohedral-endohedral transition, the calculated Ar adsorption energy exhibits a drop and the Ar-cluster distance increases drastically, indicating that Ar becomes physisorbed rather than chemisorbed. All these results confirm the assumptions made by the experimentalists when interpreting their measurements.
Vapor condensation onto a non-volatile liquid drop
Authors: Inci Levent , Bowles Richard K.
Published: December 2013

Molecular dynamics simulations of miscible and partially miscible binary Lennard–Jones mixtures are used to study the dynamics and thermodynamics of vapor condensation onto a non-volatile liquid drop in the canonical ensemble. When the system volume is large, the driving force for condensation is low and only a submonolayer of the solvent is adsorbed onto the liquid drop. A small degree of mixing of the solvent phase into the core of the particles occurs for the miscible system. At smaller volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Mixing into the core of the droplet is also observed for partially miscible systems below an onset volume suggesting the presence of a solubility transition. We also develop a non-volatile liquid drop model, based on the capillarity approximations, that exhibits a solubility transition between small and large drops for partially miscible mixtures and has a hysteresis loop similar to the one observed in the deliquescence of small soluble salt particles. The properties of the model are compared to our simulation results and the model is used to study the formulation of classical nucleation theory for systems with low free energy barriers.
Peakon, pseudo-peakon, and cuspon solutions for two generalized Camassa-Holm equations
Authors: Li Jibin , Qiao Zhijun
Published: December 2013

In this paper, we study peakon, cuspon, and pseudo-peakon solutions for two generalized Camassa-Holm equations. Based on the method of dynamical systems, the two generalized Camassa-Holm equations are shown to have the parametric representations of the solitary wave solutions such as peakon, cuspon, pseudo-peakons, and periodic cusp solutions. In particular, the pseudo-peakon solution is for the first time proposed in our paper. Moreover, when a traveling system has a singular straight line and a heteroclinic loop, under some parameter conditions, there must be peaked solitary wave solutions appearing.
Laplace-Runge-Lenz vector in quantum mechanics in noncommutative space
Authors: Gáliková Veronika , Kováčik Samuel , Prešnajder Peter
Published: December 2013

The main point of this paper is to examine a  “hidden”  dynamical symmetry connected with the conservation of Laplace-Runge-Lenz vector (LRL) in the hydrogen atom problem solved by means of non-commutative quantum mechanics (NCQM). The basic features of NCQM will be introduced to the reader, the key one being the fact that the notion of a point, or a zero distance in the considered configuration space, is abandoned and replaced with a  “fuzzy”  structure in such a way that the rotational invariance is preserved. The main facts about the conservation of LRL vector in both classical and quantum theory will be reviewed. Finally, we will search for an analogy in the NCQM, provide our results and their comparison with the QM predictions. The key notions we are going to deal with are non-commutative space, Coulomb-Kepler problem, and symmetry.
Passing particle toroidal precession induced by electric field in a tokamak
Authors: Andreev V. V. , Ilgisonis V. I. , Sorokina E. A.
Published: December 2013

Characteristics of a rotation of passing particles in a tokamak with radial electric field are calculated. The expression for time-averaged toroidal velocity of the passing particle induced by the electric field is derived. The electric-field-induced additive to the toroidal velocity of the passing particle appears to be much smaller than the velocity of the electric drift calculated for the poloidal magnetic field typical for the trapped particle. This quantity can even have the different sign depending on the azimuthal position of the particle starting point. The unified approach for the calculation of the bounce period and of the time-averaged toroidal velocity of both trapped and passing particles in the whole volume of plasma column is presented. The results are obtained analytically and are confirmed by 3D numerical calculations of the trajectories of charged particles.
Nonlinear electron acceleration by oblique whistler waves: Landau resonance vs. cyclotron resonance
Authors: Artemyev A. V. , Vasiliev A. A. , Mourenas D. , Agapitov O. V. , Krasnoselskikh V. V.
Published: December 2013

This paper is devoted to the study of the nonlinear interaction of relativistic electrons and high amplitude strongly oblique whistler waves in the Earth's radiation belts. We consider electron trapping into Landau and fundamental cyclotron resonances in a simplified model of dipolar magnetic field. Trapping into the Landau resonance corresponds to a decrease of electron equatorial pitch-angles, while trapping into the first cyclotron resonance increases electron equatorial pitch-angles. For 100 keV electrons, the energy gained due to trapping is similar for both resonances. For electrons with smaller energy, acceleration is more effective when considering the Landau resonance. Moreover, trapping into the Landau resonance is accessible for a wider range of initial pitch-angles and initial energies in comparison with the fundamental resonance. Thus, we can conclude that for intense and strongly oblique waves propagating in the quasi-electrostatic mode, the Landau resonance is generally more important than the fundamental one.
Quantum transport through aromatic molecules
Authors: Ojeda J. H. , Rey-González R. R. , Laroze D.
Published: December 2013

In this paper, we study the electronic transport properties through aromatic molecules connected to two semi-infinite leads. The molecules are in different geometrical configurations including arrays. Using a nearest neighbor tight-binding approach, the transport properties are analyzed into a Green's function technique within a real-space renormalization scheme. We calculate the transmission probability and the Current-Voltage characteristics as a function of a molecule-leads coupling parameter. Our results show different transport regimes for these systems, exhibiting metal-semiconductor-insulator transitions and the possibility to employ them in molecular devices.
Homogeneous AlGaN/GaN superlattices grown on free-standing (11¯00) GaN substrates by plasma-assisted molecular beam epitaxy
Authors: Shao Jiayi , Zakharov Dmitri N. , Edmunds Colin , Malis Oana , Manfra Michael J.
Published: December 2013

Two-dimensional and homogeneous growth of m-plane AlGaN by plasma-assisted molecular beam epitaxy has been realized on free-standing (11¯00) GaN substrates by implementing high metal-to-nitrogen (III/N) flux ratio. AlN island nucleation, often reported for m-plane AlGaN under nitrogen-rich growth conditions, is suppressed at high III/N flux ratio, highlighting the important role of growth kinetics for adatom incorporation. The homogeneity and microstructure of m-plane AlGaN/GaN superlattices are assessed via a combination of scanning transmission electron microscopy and high resolution transmission electron microscopy (TEM). The predominant defects identified in dark field TEM characterization are short basal plane stacking faults (SFs) bounded by either Frank-Shockley or Frank partial dislocations. In particular, the linear density of SFs is approximately 5 × 10−5 cm−1, and the length of SFs is less than 15 nm.
Do Finite-Size Lyapunov Exponents detect coherent structures?
Authors: Karrasch Daniel , Haller George
Published: December 2013

Ridges of the Finite-Size Lyapunov Exponent (FSLE) field have been used as indicators of hyperbolic Lagrangian Coherent Structures (LCSs). A rigorous mathematical link between the FSLE and LCSs, however, has been missing. Here, we prove that an FSLE ridge satisfying certain conditions does signal a nearby ridge of some Finite-Time Lyapunov Exponent (FTLE) field, which in turn indicates a hyperbolic LCS under further conditions. Other FSLE ridges violating our conditions, however, are seen to be false positives for LCSs. We also find further limitations of the FSLE in Lagrangian coherence detection, including ill-posedness, artificial jump-discontinuities, and sensitivity with respect to the computational time step.
Field emission performance enhancement of Au nanoparticles doped graphene emitters
Authors: Chen Leifeng , He Hong , Lei Da , Menggen QiQiGe , Hu Liqin , Yang Deren
Published: December 2013

Graphene (GP) field emitters fabricated by the electrophoretic deposition (EPD) and their field emission performance can be enhanced and tailed simultaneously by chemical doping Au nanoparticles (NPs). It was found that doped Au NPs could both decrease the resistance of GP emitters and increase the density of field emission sites. The Au-doped GP emitters showed lower turn-on voltage, lower threshold field, higher field enhancement factor, higher luminance intensity, and emitting uniformity, compared with that of pristine GP. This study will provide us to further understand the role of doping effect on the GP emitters used for the future display.
Englert and Higgs are awarded the Nobel Prize in Physics
Authors: Schwarzschild Bertram M.
Published: December 2013

The prize comes in the wake of the much anticipated discovery of the spinless fundamental particle their theoretical work predicted half a century ago.
“Melting” ice yields hints of a second liquid water phase
Authors: Smart Ashley G.
Published: December 2013

New experimental findings bolster a controversial theory of supercooled water.
Ban on US–China space-program ties means missed opportunities for NASA
Authors: Kramer David
Published: December 2013

Sino-US cooperation could stretch budgets and benefit both countries in space science and human flight.
The future of the Higgs boson
Authors: Lykken Joseph , Spiropulu Maria
Published: December 2013

Experimentalists and theorists are still celebrating the Nobel-worthy discovery of the Higgs boson that was announced in July 2012 at CERN’s Large Hadron Collider. Now they are working on the profound implications of that discovery.
A reporter’s look at the progress of science
Authors: Day Charles
Published: December 2013

In 10 years, research can take many twists and turns—or not. Here’s a sampling.
The standard model’s greatest triumph
Authors: Gabrielse Gerald
Published: December 2013

The standard model predicts the electron magnetic moment to an astonishing accuracy of one part in a trillion.
Density and Built Form: Integrating ‘Spacemate’ with the Work of Martin and March
Authors: Steadman Philip
Published: December 2013

The ‘Spacemate’ diagram of Berghauser Pont and Haupt [2004 Spacemate: The Spatial Logic of Urban Density (Delft University Press, Delft); 2005 Nordisk Arkitekturforskning 4 55–68] relates together three geometrical properties of buildings: Density expressed as a floor space index (FSI), ground coverage, and number of storeys. The authors measured these variables in a sample of Dutch residential estates and showed how Spacemate segregates the buildings into distinct morphological types. Martin and March [1972 Urban Space and Structures (Cambridge University Press, Cambridge)] showed how three generic built forms—freestanding ‘pavilions’, parallel ‘streets’, and inward-looking ‘courts’—make use of land in distinctively different ways, again measuring density in terms of FSI. This paper brings the two pieces of work together and shows how Martin and March's analysis can provide further theoretical explanation for Berghauser Pont and Haupt's empirical findings. Two additional variables are introduced: depth of buildings in plan, and cut-off angles describing the distances by which buildings are separated. A more precise morphological categorisation is then possible.
Progestin priming before gonadotrophin stimulation and AI improves embryo development and normalises luteal function in the cat
Authors: Stewart Rosemary A. , Crosier Adrienne E. , Pelican Katharine M. , Pukazhenthi Budhan S. , Sitzmann Brandon D. , Porter Tom E. , Wildt David E. , Ottinger Mary Ann , Howard JoGayle
Published: December 2013

Exogenous gonadotrophins administered before AI can adversely alter endocrine dynamics and inhibit embryo development in felids. In the present study, we tested the hypothesis that priming the domestic cat ovary with progestin mitigates the negative influence of gonadotrophin therapy by normalising early embryogenesis and luteal function. Queens were given either: (1) progestin pretreatment plus chorionic gonadotrophins (n = 8; primed); or (2) gonadotrophins only (n = 8; unprimed). Ovulatory response was assessed laparoscopically, and cats with fresh corpora lutea (CL) were inseminated in utero. Ovariohysterectomy was performed 3 days later to recover intra-oviductal embryos for in vitro culture; one ovary was prepared for histology, and CL from the remaining ovary were excised and assessed for progesterone content and targeted gene expression. Of the six primed and seven unprimed queens inseminated, embryo(s) were recovered from five individuals per group. Embryos from progestin-primed donors more closely simulated normal stage in vivo development (P < 0.05). No 2- or 4-cell embryos from either group developed beyond 16-cells in vitro; however, 50% of unprimed and 66.7% of primed (P > 0.05) 5–16-cell embryos progressed to morulae or blastocysts by Day 4 of culture. Although histological characteristics were unaffected by progestin priming (P > 0.05), luteal progesterone was unusually high (P < 0.05) in unprimed compared with primed cats (72.4 ± 5.8 vs 52.2 ± 5.5 ng mg–1, respectively). Two genes associated with progesterone biosynthesis (luteinising hormone receptor and 3β-hydroxysteroid dehydrogenase) were upregulated in unprimed versus primed individuals (P = 0.05 and P < 0.05, respectively), indicating potential mechanistic pathways for the protective influence of pre-emptive progestin treatment. Building on earlier findings that progestin priming prevents spontaneous ovulation, increases ovarian sensitivity to gonadotrophins and ensures a normative endocrine environment, the present study demonstrates that pretreatment with this steroid also benefits embryo development and normalisation of early luteal function.
Regulation of Son of sevenless by the membrane-actin linker protein ezrin
Authors: Geißler Katja J. , Jung M. Juliane , Riecken Lars Björn , Sperka Tobias , Cui Yan , Schacke Stephan , Merkel Ulrike , Markwart Robby , Rubio Ignacio , Than Manuel E. , Breithaupt Constanze , Peuker Sebastian , Seifert Reinhard , Kaupp Ulrich Benjamin , Herrlich Peter , Morrison Helen
Published: December 2013

Significance

Activity of the small GTPase Ras (rat sarcoma) needs to be tightly regulated because aberrant activity has a potent oncogenic effect, causing several forms of cancer as well as developmental disorders known as RASopathies. We have identified the ezrin, radixin, and moesin protein family as a previously unknown component in the control of Ras activity. Ezrin functions in the assembly of a protein complex that facilitates the encounter of Ras with its activating enzyme, Son of sevenless. Thus ezrin mediates a spatiotemporal control of Ras activity that helps coordinate and safeguard Ras signaling output.
Phosphorylated K-Ras limits cell survival by blocking Bcl-xL sensitization of inositol trisphosphate receptors
Authors: Sung Pamela J. , Tsai Frederick D. , Vais Horia , Court Helen , Yang Jun , Fehrenbacher Nicole , Foskett J. Kevin , Philips Mark R.
Published: December 2013

Significance

K-Ras is mutated more often than any other oncogene, making the protein and the pathways it regulates attractive targets for anticancer drug discovery. We have shown that phosphorylation of serine 181 in the membrane-targeting region of K-Ras causes the protein to translocate from plasma membrane to intracellular membranes. Translocation is associated with toxicity but the mechanism has remained undefined. Here we show that phospho–K-Ras associates with inositol trisphosphate receptors (IP3Rs) on the endoplasmic reticulum (ER) and thereby blocks one of the prosurvival activities of Bcl-xL, which is to sensitize IP3Rs and thereby allow constitutive transfer of calcium from ER to mitochondria where it is required for efficient respiration. This pathway could be exploited to limit the oncogenic activity of mutant K-Ras.
Resolving the roles of immunity, pathogenesis, and immigration for rabies persistence in vampire bats
Authors: Blackwood Julie C. , Streicker Daniel G. , Altizer Sonia , Rohani Pejman
Published: December 2013

Significance

Bats are a frequent source of pathogen spillover to humans and livestock, and a reservoir for emerging infectious diseases. Transmission mechanisms within bat populations remain enigmatic, precluding effective management of zoonotic infections. Vampire bats transmit rabies virus throughout Latin America, causing lethal human rabies and thousands of livestock deaths every year. By selecting among competing transmission models applied to spatially replicated, longitudinal field data, we find that most rabies virus exposures are nonlethal and instead immunize bats, thus facilitating viral persistence. Further, frequent interactions among bats from different colonies are necessary to maintain the chain of transmission. We also evaluate the efficacy of bat culling and demonstrate that it has minimal effects on seroprevalence when spatially coordinated control is absent.
Collybistin activation by GTP-TC10 enhances postsynaptic gephyrin clustering and hippocampal GABAergic neurotransmission
Authors: Mayer Simone , Kumar Rohit , Jaiswal Mamta , Soykan Tolga , Ahmadian Mohammad Reza , Brose Nils , Betz Heinrich , Rhee Jeong-Seop , Papadopoulos Theofilos
Published: December 2013

Significance

Inhibitory synaptic transmission controls neuronal network activity, and its aberrant function is involved in many brain disorders, including schizophrenia, epilepsy, or mental retardation. We identified an as yet unknown mechanism by which the small GTPase TC10 determines the strength of inhibitory neurotransmission by activating collybistin, which in turn recruits the scaffold protein gephyrin and GABA
A
receptors to inhibitory postsynapses.
Presynaptic mitochondrial morphology in monkey prefrontal cortex correlates with working memory and is improved with estrogen treatment
Authors: Hara Yuko , Yuk Frank , Puri Rishi , Janssen William G. M. , Rapp Peter R. , Morrison John H.
Published: December 2013

Significance

Human and nonhuman primates are vulnerable to age- and menopause-related decline in working memory, a cognitive function reliant on the energy-demanding excitation of prefrontal cortex (PFC) neurons. The number and strength of presynaptic boutons providing inputs to these PFC neurons regulate their excitability. We show that poor working memory in rhesus monkeys is associated with a higher incidence of presynaptic boutons harboring malformed, donut-shaped mitochondria that form abnormally small synaptic contacts. Surgically induced menopause results in working memory impairment and a concomitant increase in presynaptic donut-shaped mitochondria, both of which are reversed by estradiol treatment. Our findings suggest that hormone replacement therapy benefits cognitive aging, in part, by promoting mitochondrial and synaptic health in the PFC.
Structural snapshots illustrate the catalytic cycle of β-galactocerebrosidase, the defective enzyme in Krabbe disease
Authors: Hill Chris H. , Graham Stephen C. , Read Randy J. , Deane Janet E.
Published: December 2013

Significance

Defects in the enzyme β-galactocerebrosidase (GALC) result in the devastating neurodegenerative disorder Krabbe disease. GALC is responsible for the degradation and recycling of glycosphingolipids that form the primary lipid component of the myelin sheath that insulates nerve cells. A detailed understanding of how GALC processes substrate will facilitate the development of new drug therapies for Krabbe disease. This study reveals a series of structural snapshots of GALC captured during different steps of the catalytic cycle. These structures identify specific residues within the active site that undergo significant movements during substrate cleavage, providing key insight into the catalytic mechanism of GALC.
Bioluminescent imaging of drug efflux at the blood–brain barrier mediated by the transporter ABCG2
Authors: Bakhsheshian Joshua , Wei Bih-Rong , Chang Ki-Eun , Shukla Suneet , Ambudkar Suresh V. , Simpson R. Mark , Gottesman Michael M. , Hall Matthew D.
Published: December 2013

Significance

The blood–brain barrier (BBB) prevents ingress of small molecules into the brain partly by expression of drug efflux transporters. Although several transporters are known to be involved, the role ABCG2 plays in this process is not clear. We demonstrate the ability to image ABCG2 function at the BBB by using luciferin in a luciferase-expressing mouse. This represents a direct measurement of ABCG2 function at the BBB, and demonstrates that ABCG2 does play a functional role at the BBB.
Stimulus-induced modulation of transcriptional bursting in a single mammalian gene
Authors: Molina Nacho , Suter David M. , Cannavo Rosamaria , Zoller Benjamin , Gotic Ivana , Naef Félix
Published: December 2013

Significance

Recent single-cell studies showed that gene transcription in mammals is fundamentally stochastic, occurring in short and intense transcriptional bursts. However, less is known on how transcriptional bursting is modulated upon stimulation. Here, we monitor the transcriptional response of a single allele of the endogenous
connective tissue growth factor
gene, encoding a secreted protein involved in wound healing and response to shear stress, to two different physiological stimuli in single cells. Analysis using stochastic modeling shows that both stimuli cause acute transcriptional responses characterized by transiently modified gene activities, and increased transcription rates that may last longer depending on the stimulus. These results provide insights on how transcriptional bursting kinetics can be adjusted to increase gene expression upon physiological stimulations.
Protein recognition and selection through conformational and mutually induced fit
Authors: Wang Qian , Zhang Pengzhi , Hoffman Laurel , Tripathi Swarnendu , Homouz Dirar , Liu Yin , Waxham M. Neal , Cheung Margaret S.
Published: December 2013

Significance

Protein–protein interactions drive most every biological process, but in many instances the domains mediating recognition are disordered. How specificity in binding is attained in the absence of defined structure is a fascinating problem but not well understood. Calmodulin presents a unique opportunity to investigate mechanisms for selectivity given that it interacts with several hundred different potential targets. In our work, a combined experimental and theoretical approach is taken to define how target selectivity occurs at the molecular level. Our study shows that the binding interactions require mutually induced conformational changes in both calmodulin and the target protein, and broadly informs how intrinsically disordered proteins can achieve both high affinity and high specificity.
Flavin reduction activates
Drosophila
cryptochrome
Authors: Vaidya Anand T. , Top Deniz , Manahan Craig C. , Tokuda Joshua M. , Zhang Sheng , Pollack Lois , Young Michael W. , Crane Brian R.
Published: December 2013

Significance

Cryptochromes (CRYs) are photosensors that play central roles in the circadian rhythms of plants and animals. CRYs are related to photolyase DNA-repair enzymes, but instead of binding DNA, insect CRYs bind a C-terminal tail (CTT) α-helix in the pocket that holds the light-sensing flavin molecule. There is no consensus on how light activates
Drosophila
CRY (dCRY). We show that reduction of the flavin to the anionic semiquinone by light or chemicals releases the CTT to activate dCRY. The target of dCRY, the protein Timeless, contains a sequence similar to the CTT, and dCRY recognizes this sequence selectively in the light. This study supports a model for CRY signaling in which flavin reduction is the critical step performed by light.
Mantle–slab interaction and redox mechanism of diamond formation
Authors: Palyanov Yuri N. , Bataleva Yuliya V. , Sokol Alexander G. , Borzdov Yuri M. , Kupriyanov Igor N. , Reutsky Vadim N. , Sobolev Nikolai V.
Published: December 2013

Significance

The primary question that we address in this study is what happens when a carbonate-bearing crust is subducted to depths where the Earth’s mantle is metal saturated. Subduction plays an important role in the evolution of the Earth’s interiors, but the mechanism of the interaction between the oxidized slab and reduced mantle remains unclear. Here we report the results of high-pressure redox-gradient experiments on the interaction between Mg-Ca-carbonate and metallic iron, modeling the processes at the mantle–slab boundary, and present mechanisms of diamond formation ahead of and behind the redox front. We demonstrate that the redox mechanism revealed in this study can explain the contrasting heterogeneity of natural diamonds on the composition of inclusions, carbon isotopic composition, and nitrogen impurity content.
Visible light alters yeast metabolic rhythms by inhibiting respiration
Authors: Robertson James Brian , Davis Chris R. , Johnson Carl Hirschie
Published: December 2013

Significance

In some organisms, respiration fluctuates cyclically, and these rhythms can be a sensitive gauge of metabolism. Constant or pulsatile exposure of yeast to visible wavelengths of light significantly alters and/or initiates these respiratory oscillations, revealing a further dimension of the challenges to yeast living in natural environments. Our results also have implications for the use of light as research tools—e.g., for excitation of fluorescence microscopically—even in organisms such as yeast that do not express specialized photoreceptive molecules. Moreover, the growth of yeast strains that are null for the
yeast activator protein-1
gene that regulates oxidative stress genes is exquisitely sensitive to visible light, indicating that light can both modulate respiration and induce oxidative stress.
The Burmese python genome reveals the molecular basis for extreme adaptation in snakes
Authors: Castoe Todd A. , de Koning A. P. Jason , Hall Kathryn T. , Card Daren C. , Schield Drew R. , Fujita Matthew K. , Ruggiero Robert P. , Degner Jack F. , Daza Juan M. , Gu Wanjun , Reyes-Velasco Jacobo , Shaney Kyle J. , Castoe Jill M. , Fox Samuel E. , Poole Alex W. , Polanco Daniel , Dobry Jason , Vandewege Michael W. , Li Qing , Schott Ryan K. , Kapusta Aurélie , Minx Patrick , Feschotte Cédric , Uetz Peter , Ray David A. , Hoffmann Federico G. , Bogden Robert , Smith Eric N. , Chang Belinda S. W. , Vonk Freek J. , Casewell Nicholas R. , Henkel Christiaan V. , Richardson Michael K. , Mackessy Stephen P. , Bronikowski Anne M. , Yandell Mark , Warren Wesley C. , Secor Stephen M. , Pollock David D.
Published: December 2013

Significance

The molecular basis of morphological and physiological adaptations in snakes is largely unknown. Here, we study these phenotypes using the genome of the Burmese python (
Python molurus bivittatus
), a model for extreme phenotypic plasticity and metabolic adaptation. We discovered massive rapid changes in gene expression that coordinate major changes in organ size and function after feeding. Many significantly responsive genes are associated with metabolism, development, and mammalian diseases. A striking number of genes experienced positive selection in ancestral snakes. Such genes were related to metabolism, development, lungs, eyes, heart, kidney, and skeletal structure—all highly modified features in snakes. Snake phenotypic novelty seems to be driven by the system-wide coordination of protein adaptation, gene expression, and changes in genome structure.