bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotational mode specificity in the Cl + CHD3 → HCl + CD3 reaction
Authors: Liu Rui , Wang Fengyan , Jiang Bin , Czakó Gábor , Yang Minghui , Liu Kopin , Guo Hua
Published: August 2014

By exciting the rotational modes of vibrationally excited CHD3(v1 = 1, JK), the reactivity for the Cl + CHD3 → HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories. It is shown that the higher reactivity for higher J states of CHD3 with K = 0 can be attributed to the enlargement of the cone of acceptance. On the other hand, the less pronounced enhancement for the higher J = K states is apparently due to the fact that the rotation along the C–H bond is less effective in opening up the cone of acceptance.
Role of seta angle and flexibility in the gecko adhesion mechanism
Authors: Hu Congcong , Alex Greaney P.
Published: August 2014

A model is developed to describe the reversible nature of gecko dry adhesion. The central aspect of this model is that the seta can be easily peeled away from the contacting surface by a small moment at the contact tip. It is shown that this contact condition is very sensitive, but can result in robust adhesion if individual setae are canted and highly flexible. In analogy to the “cone of friction,” we consider the “adhesion region”—the domain of normal and tangential forces that maintain adhesion. Results demonstrate that this adhesion region is highly asymmetric enabling the gecko to adhere under a variety of loading conditions associated with scuttling horizontally, vertically, and inverted. Moreover, under each of these conditions, there is a low energy path to de-adhesion. In this model, obliquely canted seta (as possessed by geckos) rather than vertically aligned fibers (common in synthetic dry adhesive) provides the most robust adhesion.
Microscopic theory of singlet exciton fission. III. Crystalline pentacene
Authors: Berkelbach Timothy C. , Hybertsen Mark S. , Reichman David R.
Published: August 2014

We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems.
Fusion proton diagnostic for the C-2 field reversed configuration
Authors: Magee R. M. , Clary R. , Korepanov S. , Smirnov A. , Garate E. , Knapp K. , Tkachev A.
Published: August 2014

Measurements of the flux of fusion products from high temperature plasmas provide valuable insights into the ion energy distribution, as the fusion reaction rate is a very sensitive function of ion energy. In C-2, where field reversed configuration plasmas are formed by the collision of two compact toroids and partially sustained by high power neutral beam injection [M. Binderbauer et al., Phys. Rev. Lett. 105, 045003 (2010); M. Tuszewski et al., Phys. Rev. Lett. 108, 255008 (2012)], measurements of DD fusion neutron flux are used to diagnose ion temperature and study fast ion confinement and dynamics. In this paper, we will describe the development of a new 3 MeV proton detector that will complement existing neutron detectors. The detector is a large area (50 cm2), partially depleted, ion implanted silicon diode operated in a pulse counting regime. While the scintillator-based neutron detectors allow for high time resolution measurements (∼100 kHz), they have no spatial or energy resolution. The proton detector will provide 10 cm spatial resolution, allowing us to determine if the axial distribution of fast ions is consistent with classical fast ion theory or whether anomalous scattering mechanisms are active. We will describe in detail the diagnostic design and present initial data from a neutral beam test chamber.
Comparative study of local structure of two cyanobiphenyl liquid crystals by molecular dynamics method
Authors: Gerts Egor D. , Komolkin Andrei V. , Burmistrov Vladimir A. , Alexandriysky Victor V. , Dvinskikh Sergey V.
Published: August 2014

Fully-atomistic molecular dynamics simulations were carried out on two similar cyanobiphenyl nematogens, HO-6OCB and 7OCB, in order to study effects of hydrogen bonds on local structure of liquid crystals. Comparable length of these two molecules provides more evident results on the effects of hydrogen bonding. The analysis of radial and cylindrical distribution functions clearly shows the differences in local structure of two mesogens. The simulations showed that anti-parallel alignment is preferable for the HO-6OCB. Hydrogen bonds between OH-groups are observed for 51% of HO-6OCB molecules, while hydrogen bonding between CN- and OH-groups occurs only for 16% of molecules. The lifetimes of H-bonds differ due to different mobility of molecular fragments (50 ps for N⋅⋅⋅H–O and 41 ps for O⋅⋅⋅H–O). Although the standard Optimized Potentials for Liquid Simulations - All-Atom force field cannot reproduce some experimental parameters quantitatively (order parameters are overestimated, diffusion coefficients are not reproduced well), the comparison of relative simulated results for the pair of mesogens is nevertheless consistent with the same relative experimental parameters. Thus, the comparative study of simulated and experimental results for the pair of similar liquid crystals still can be assumed plausible.
Skin-friction drag reduction in the turbulent regime using random-textured hydrophobic surfaces
Authors: Bidkar Rahul A. , Leblanc Luc , Kulkarni Ambarish J. , Bahadur Vaibhav , Ceccio Steven L. , Perlin Marc
Published: August 2014

Technologies for reducing hydrodynamic skin-friction drag have a huge potential for energy-savings in applications ranging from propulsion of marine vessels to transporting liquids through pipes. The majority of previous experimental studies using hydrophobic surfaces have successfully shown skin-friction drag reduction in the laminar and transitional flow regimes (typically Reynolds numbers less than ≃106 for external flows). However, this hydrophobicity induced drag reduction is known to diminish with increasing Reynolds numbers in experiments involving wall bounded turbulent flows. Using random-textured hydrophobic surfaces (fabricated using large-length scalable thermal spray processes) on a flat plate geometry, we present water-tunnel test data with Reynolds numbers ranging from 106 to 9 × 106 that show sustained skin-friction drag reduction of 20%–30% in such turbulent flow regimes. Furthermore, we provide evidence that apart from the formation of a Cassie state and hydrophobicity, we also need a low surface roughness and an enhanced ability of the textured surface to retain trapped air, for sustained drag reduction in turbulent flow regimes. Specifically, for the hydrophobic test surfaces of the present and previous studies, we show that drag reduction seen at lower Reynolds numbers diminishes with increasing Reynolds number when the surface roughness of the underlying texture becomes comparable to the viscous sublayer thickness. Conversely, test data show that textures with surface roughness significantly smaller than the viscous sublayer thickness and textures with high porosity show sustained drag reduction in the turbulent flow regime. The present experiments represent a significant technological advancement and one of the very few demonstrations of skin-friction reduction in the turbulent regime using random-textured hydrophobic surfaces in an external flow configuration. The scalability of the fabrication method, the passive nature of this surface technology, and the obtained results in the turbulent regime make such hydrophobic surfaces a potentially attractive option for hydrodynamic skin-friction drag reduction.
Microstructured multi-well plate for three-dimensional packed cell seeding and hepatocyte cell culture
Authors: Goral Vasiliy N. , Au Sam H. , Faris Ronald A. , Yuen Po Ki
Published: August 2014

In this article, we present a microstructured multi-well plate for enabling three-dimensional (3D) high density seeding and culture of cells through the use of a standard laboratory centrifuge to promote and maintain 3D tissue-like cellular morphology and cell-specific functionality in vitro without the addition of animal derived or synthetic matrices or coagulants. Each well has microfeatures on the bottom that are comprised of a series of ditches/open microchannels. The dimensions of the microchannels promote and maintain 3D tissue-like cellular morphology and cell-specific functionality in vitro. After cell seeding with a standard pipette, the microstructured multi-well plates were centrifuged to tightly pack cells inside the ditches in order to enhance cell-cell interactions and induce formation of 3D cellular structures during cell culture. Cell-cell interactions were optimized based on cell packing by considering dimensions of the ditches/open microchannels, orientation of the microstructured multi-well plate during centrifugation, cell seeding density, and the centrifugal force and time. With the optimized cell packing conditions, we demonstrated that after 7 days of cell culture, primary human hepatocytes adhered tightly together to form cord-like structures that resembled 3D tissue-like cellular architecture. Importantly, cell membrane polarity was restored without the addition of animal derived or synthetic matrices or coagulants.
Proper conformal symmetries in self-dual Einstein spaces
Authors: Chudecki Adam , Dobrski Michał
Published: August 2014

Proper conformal symmetries in self-dual Einstein spaces are considered. It is shown that such symmetries are admitted only by the Einstein spaces of the type \documentclass[12pt]{minimal}\begin{document}$[\textrm {N},-] \otimes [\textrm {N},-]$\end{document}[N,−]⊗[N,−]. Spaces of the type \documentclass[12pt]{minimal}\begin{document}$[\textrm {N}] \otimes [-]$\end{document}[N]⊗[−] are considered in details. Existence of the proper conformal Killing vector implies existence of the isometric, covariantly constant, and null Killing vector. It is shown that there are two classes of \documentclass[12pt]{minimal}\begin{document}$[\textrm {N}] \otimes [-]$\end{document}[N]⊗[−]-metrics admitting proper conformal symmetry. They can be distinguished by analysis of the associated anti-self-dual (ASD) null strings. Both classes are analyzed in details. The problem is reduced to single linear partial differential equation (PDE). Some general and special solutions of this PDE are presented.
Progress in development of neutron energy spectrometer for deuterium plasma operation in KSTAR
Authors: Tomita H. , Yamashita F. , Nakayama Y. , Morishima K. , Yamamoto Y. , Sakai Y. , Cheon M. S. , Isobe M. , Ogawa K. , Hayashi S. , Kawarabayashi J. , Iguchi T.
Published: August 2014

Two types of DD neutron energy spectrometer (NES) are under development for deuterium plasma operation in KSTAR to understand behavior of beam ions in the plasma. One is based on the state-of-the-art nuclear emulsion technique. The other is based on a coincidence detection of a recoiled proton and a scattered neutron caused by an elastic scattering of an incident DD neutron, which is called an associated particle coincidence counting-NES. The prototype NES systems were installed at J-port in KSTAR in 2012. During the 2012 and 2013 experimental campaigns, multiple shots-integrated neutron spectra were preliminarily obtained by the nuclear emulsion-based NES system.
Mechanics of the injected pulsejet into gelatin gel and evaluation of the effect by puncture and crack generation and growth
Authors: Kato T. , Arafune T. , Washio T. , Nakagawa A. , Ogawa Y. , Tominaga T. , Sakuma I. , Kobayashi E.
Published: August 2014

Recently, fluid jets have become widely used in medical devices and have been created and evaluated in clinical environments. Such devices are classified into two broad groups; those adopting continuous jets and those adopting discrete (or pulsed) jets. We developed a discrete jet device for brain cancer treatment, called a laser-induced liquid jet (LILJ) system. Although several studies have evaluated the availability and described the treatment mechanisms of fluid jet devices, the mechanisms of the fluid and injected material remain under-investigated. In this paper, we report the mechanism of frequent pulsejet injections into a viscoelastic biological material; namely, simulated gelatin brain tissue. The mechanism is evaluated by the injection depth, an easily measured parameter. To explain the injection mechanism, we propose that the pulsejet is pressured by forces introduced by resistance on the side surface of the hole and the reaction force proportionate to the injection depth. The pulsejet generated and propagated cracks in the gelatin, and the resistance eventually fractured the side surface of the hole. We evaluated the proposed model by measuring the behavior of pulsejets injected into gelatin by the LILJ. From the results, the following conclusions were obtained. First, the proposed model accurately describes the behavior of the injected pulsejet. Second, whether the hole or crack growth largely increases the final injection depth can be evaluated from differences in the decay constant. Finally, crack growth increases the final injection depth when the number of the injected pulsejets is greater than the inverse of the decay constant.
Substitution effect on the magnetic and transport properties of CeNi0.8−xMnxBi2
Authors: Kim Soo-Whan , Lee Kyujoon , Adroja D. T. , Demmel F. , Taylor J. W. , Jung Myung-Hwa
Published: August 2014

We report the results of Mn substitution for Ni in CeNi0.8Bi2 (i.e., CeNi0.8−xMnxBi2). All the samples have an antiferromagnetic ordered state below TN = 5.0 K due to localized 4f-magnetic moment on the Ce ions. Besides this antiferromagnetic ordering caused by Ce, the magnetic and transport properties are abruptly changed with increasing Mn contents at the boundary composition of x = 0.4. The magnetic state is changed into a ferromagnetic state around 200 K for x > 0.4, where the electrical resistivity is strongly suppressed to become simple metallic. These results of ferromagnetism and metallicity can be explained by the double exchange mechanism, rather than the simple picture of Doniach phase diagram. The mixed valence states of Ni and Mn ions are confirmed by X-ray photoelectron spectroscopy. For x ≤ 0.4, the initial Ni3+ state gradually changes to the Ni2+ state with increasing x up to 0.4. On further increase of x > 0.4, the Ni2+ state is replaced by the Mn2+ state, which gradually changes to the final Mn3+ state. We also present an inelastic neutron scattering (INS) measurements on CeNi0.8Bi2 (i.e., x = 0) between 1.2 and 12 K. The high energy INS study reveals the presence of two well-defined crystal electric field (CEF) excitations near 9 meV and 19 meV at 1.2 K and 6 K, while the low energy INS study reveals the presence of quasielastic scattering above 4 K. We will discuss our INS results of CeNi0.8Bi2 based on the CEF model.
Reduction of Cu-rich interfacial layer and improvement of bulk CuO property through two-step sputtering for p-CuO/n-Si heterojunction solar cell
Authors: Masudy-Panah Saeid , Dalapati Goutam Kumar , Radhakrishnan K. , Kumar Avishek , Tan Hui Ru
Published: August 2014

Copper-rich interfacial-layer (Cu-rich IL) is formed during sputter deposition of cupric oxide (CuO) layer on silicon (Si). It has significant impact on the performance of p-CuO/n-Si heterojunction solar cells. In this report, CuO films deposited on Si at different RF-power levels using single and two-step RF-sputtering techniques and p-CuO/n-Si heterojunction solar cells have been investigated. Systematic characterization using XPS, AFM, XRD, Raman, and HR-TEM reveal that two-step RF-sputtering technique offers better crystal quality CuO film with thinner Cu-rich IL layer. Photovoltaic (PV) properties with an open-circuit voltage (Voc) of 421 mV, short circuit current (Jsc) of 4.5 mA/cm2, and a photocurrent of 8.3 mA/cm2 have been achieved for the cells prepared using two-step sputtering method, which are significantly higher than that for the solar cells fabricated using a single-step sputtering. The PV properties were further improved by depositing CuO films at higher working pressure with nitrogen doping. The efficiency of the best device achieved is approximately 1.21%, which is the highest value reported for p-CuO/n-Si heterojunction based solar cells.
Spray-cooling concept for wind-based compressed air energy storage
Authors: Qin C. , Loth E. , Li P. , Simon T. , Van de Ven J.
Published: August 2014

Wind turbine output energy varies over time with local wind speed and is typically inconsistent with grid power demand. Without energy storage, the resulting difference between rated (peak) power and average power output leads to over-sizing of electrical generator and transmission lines. This conventional arrangement can be avoided if wind turbines can be coupled with energy storage to eliminate the output variations and instead produce their average power on a continuous basis. This would allow a smaller, lower-cost, constant-speed generator and a reduced capacity transmission system sized only for average power output. To accomplish this goal, this study discusses a concept for a storage system for a 5 MW off-shore wind turbine, which integrates a spray-based compressed air energy storage with a 35 MPa accumulator. The compressor employs a liquid piston for air sealing and employs water spray to augment heat transfer for high-efficiency. The overall compression is proposed in three stages with pressure ratios of 10:1, 7:1, and 5:1, all operated at 1 Hz to maintain moderate liquid surface acceleration. Based on a simple and fundamental description of the system, compression efficiency was found to be strongly dependent on droplet surface area, which can be achieved through either high mass loading or small drop sizes. The simulations also show that direct injection spray can increase overall three-stage compression efficiency to as high as 89%, substantially better than the 27% associated with a conventional adiabatic compression at the same pressure ratio. In addition, this study introduces a key performance parameter, termed the Levelization Factor, which can be used to quantify the impact of storage on wind energy systems. However, experiments and simulations based on 3-D geometries with design details are needed to determine the potential of this concept.
In-situ optical transmission electron microscope study of exciton phonon replicas in ZnO nanowires by cathodoluminescence
Authors: Yang Shize , Tian Xuezeng , Wang Lifen , Wei Jiake , Qi Kuo , Li Xiaomin , Xu Zhi , Wang Wenlong , Zhao Jimin , Bai Xuedong , Wang Enge
Published: August 2014

The cathodoluminescence spectrum of single zinc oxide (ZnO) nanowires is measured by in-situ optical Transmission Electron Microscope. The coupling between exciton and longitudinal optical phonon is studied. The band edge emission varies for different excitation spots. This effect is attributed to the exciton propagation along the c axis of the nanowire. Contrary to free exciton emission, the phonon replicas are well confined in ZnO nanowire. They travel along the c axis and emit at the end surface. Bending strain increases the relative intensity of second order phonon replicas when excitons travel along the c-axis.
Ga lithography in sputtered niobium for superconductive micro and nanowires
Authors: Henry M. David , Wolfley Steve , Monson Todd , Lewis Rupert
Published: August 2014

This work demonstrates the use of focused ion beam (FIB) implanted Ga as a lithographic mask for plasma etching of Nb films. Using a highly collimated Ga beam of a FIB, Nb is implanted 12 nm deep with a 14 nm thick Ga layer providing etch selectivity better than 15:1 with fluorine based etch chemistry. Implanted square test patterns, both 10 μm by 10 μm and 100 μm by 100 μm, demonstrate that doses above than 7.5 × 1015 cm−2 at 30 kV provide adequate mask protection for a 205 nm thick, sputtered Nb film. The resolution of this dry lithographic technique is demonstrated by fabrication of nanowires 75 nm wide by 10 μm long connected to 50 μm wide contact pads. The residual resistance ratio of patterned Nb films was 3. The superconducting transition temperature (Tc) = 7.7 K was measured using a magnetic properties measurement system. This nanoscale, dry lithographic technique was extended to sputtered TiN and Ta here and could be used on other fluorine etched superconductors such as NbN, NbSi, and NbTi.
Carbon nanotube light sensors with linear dynamic range of over 120 dB
Authors: Wei Nan , Liu Yang , Xie Huanhuan , Wei Fei , Wang Sheng , Peng Lian-Mao
Published: August 2014

We show that a carbon nanotube (CNT) diode fabricated by asymmetric contacts shows a linear photocurrent in response to illumination for over six decades or dynamic range of 120 dB; in particular, it shows no sign of degradation under illumination intensity of up to 100 kW/cm2. This CNT diode also exhibits a continued response for incident wavelength from 1165 nm to 2100 nm, promising potentials applications in robust and wide bandwidth light sensing.
Effects of threading dislocations on drain current dispersion and slow transients in unpassivated AlGaN/GaN/Si heterostructure field-effect transistors
Authors: Ghosh Saptarsi , Dinara Syed Mukulika , Mukhopadhyay Partha , Jana Sanjay K. , Bag Ankush , Chakraborty Apurba , Chang Edward Yi , kabi Sanjib , Biswas Dhrubes
Published: August 2014

Current transient analysis combined with response to pulsed bias drives have been used to explore the possibilities of threading dislocations affecting the current dispersion characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs). A growth strategy is developed to modulate the dislocation density among the heterostructures grown on silicon by plasma-assisted molecular-beam epitaxy. Slow pulsed I-V measurements show severe compressions and appear to be significantly dependent on the threading dislocation density. By analyzing the corresponding slow detrapping process, a deep-level trap with emission time constant in the order of seconds was identified as the cause. Among the specimens, both in the epilayers and at the surface, the number of dislocations was found to have a notable influence on the spatial distribution of deep-level trap density. The observations confirm that the commonly observed degraded frequency performance among AlGaN/GaN HFETs in the form of DC-radio frequency dispersions can at least partly be correlated with threading dislocation density.
Clogging by sieving in microchannels: Application to the detection of contaminants in colloidal suspensions
Authors: Sauret Alban , Barney Erin C. , Perro Adeline , Villermaux Emmanuel , Stone Howard A. , Dressaire Emilie
Published: August 2014

We report on a microfluidic method that allows measurement of a small concentration of large contaminants in suspensions of solid micrometer-scale particles. To perform the measurement, we flow the colloidal suspension through a series of constrictions, i.e., a microchannel of varying cross-section. We show and quantify the role of large contaminants in the formation of clogs at a constriction and the growth of the resulting filter cake. By measuring the time interval between two clogging events in an array of parallel microchannels, we are able to estimate the concentration of contaminants whose size is selected by the geometry of the microfluidic device. This technique for characterizing colloidal suspensions offers a versatile and rapid tool to explore the role of contaminants on the properties of the suspensions.
Investigating the magnetovolume effect in isotropic body-centered-cubic iron using spin-lattice dynamics simulations
Authors: Chui C. P. , Zhou Yan
Published: August 2014

The understanding of the magnetovolume effect lacks explicit consideration of spin-lattice coupling at the atomic level, despite abundant theoretical and experimental studies throughout the years. This research gap is filled by the recently developed spin-lattice dynamics technique implemented in this study, which investigates the magnetovolume effect of isotropic body-centered-cubic (BCC) iron, a topic that has previously been subject to macroscopic analysis only. This approach demonstrates the magnetic anomaly followed by the volumetric changes associated with the effect, each characterized by the corresponding field-induced inflection temperature. The temperature of the heat capacity peaks is useful in determining the temperature for retarding the atomic volume increase. Moreover, this work shows the correlation between the effects of temperature and field strength in determining the equilibrium atomic volume of a ferromagnetic material under a magnetic field.
Graphene chemical vapor deposition at very low pressure: The impact of substrate surface self-diffusion in domain shape
Authors: Cunha T. H. R. , Ek-Weis J. , Lacerda R. G. , Ferlauto A. S.
Published: August 2014

The initial stages of graphene chemical vapor deposition at very low pressures (<10−5 Torr) were investigated. The growth of large graphene domains (∼up to 100 μm) at very high rates (up to 3 μm2 s−1) has been achieved in a cold-wall reactor using a liquid carbon precursor. For high temperature growth (>900 °C), graphene grain shape and symmetry were found to depend on the underlying symmetry of the Cu crystal, whereas for lower temperatures (<900 °C), mostly rounded grains are observed. The temperature dependence of graphene nucleation density was determined, displaying two thermally activated regimes, with activation energy values of 6 ± 1 eV for temperatures ranging from 900 °C to 960 °C and 9 ± 1 eV for temperatures above 960 °C. The comparison of such dependence with the temperature dependence of Cu surface self-diffusion suggests that graphene growth at high temperatures and low pressures is strongly influenced by copper surface rearrangement. We propose a model that incorporates Cu surface self-diffusion as an essential process to explain the orientation correlation between graphene and Cu crystals, and which can clarify the difference generally observed between graphene domain shapes in atmospheric-pressure and low-pressure chemical vapor deposition.
Double-graded bandgap in Cu(In,Ga)Se2 thin film solar cells by low toxicity selenization process
Authors: Wang Yi-Chih , Shieh Han-Ping D.
Published: August 2014

A low-toxic selenization with post gallium diffusion (PGD) treatment has been demonstrated to increase the bandgap in the surface Cu(In,Ga)Se2 (CIGSe) absorbers and to form double-graded bandgap profiles to improve the cell efficiency. The CIGSe absorber with PGD for 5 min increased open-circuit voltage from 0.49 to 0.66 V and efficiency from 9.2% to 13.2%, contributed by the enhancement of carrier recombination in the space-charge region. The reduction in short-circuit current from 30.8 to 29.9 mA/cm2, attributed to the absorption loss in long-wavelength regions, can be potentially improved by further optimization of the minimum bandgap value in gradient valley.
Automated estimation of leaf area development in sweet pepper plants from image analysis
Authors: Horgan Graham W. , Song Yu , Glasbey Chris A. , van der Heijden Gerie W. A. M. , Polder Gerrit , Dieleman J. Anja , Bink Marco C. A. M. , van Eeuwijk Fred A.
Published: August 2014

High-throughput automated plant phenotyping has recently received a lot of attention. Leaf area is an important characteristic in understanding plant performance, but time-consuming and destructive to measure accurately. In this research, we describe a method to use a histogram of image intensities to automatically measure plant leaf area of tall pepper (Capsicum annuum L.) plants in the greenhouse. With a device equipped with several cameras, images of plants were recorded at 5-cm intervals over a height of 3 m, at a recording distance of less than 60 cm. The images were reduced to a small set of principal components that defined the design matrix in a regression model for predicting manually measured leaf area as obtained from destructive harvesting. These regression calibrations were performed for six different developmental times. In addition, development of leaf area was investigated by fitting linear relations between predicted leaf area and time, with special attention given to the genotype by time interaction and its genetic basis in the form of quantitative trait loci (QTLs). The experiment comprised parents, F1 progeny and eight genotypes of a recombinant inbred population of pepper. Although the current trial contained a limited number of genotypes, an earlier identified QTL related to leaf area growth could be confirmed. Therefore, image analysis, as presented in this paper, provides a powerful and efficient way to study and identify the genetic basis of growth and developmental processes in plants.
Reconstruction of scalar and vectorial components in X-ray dark-field tomography
Authors: Bayer Florian L. , Hu Shiyang , Maier Andreas , Weber Thomas , Anton Gisela , Michel Thilo , Riess Christian P.
Published: August 2014

Significance

X-ray Talbot−Lau grating interferometry provides a differential phase contrast and a dark-field image containing scattering information. The dark-field image is sensitive to granular and fibrous microstructures with sizes in the range of the grating periods (circa 5 μm), much below the typical resolution of medical imaging techniques like angiography or fluoroscopy (circa 150 μm). Dark-field contrast is influenced by the orientation of the microstructure in the object. We present an approach to recover the local microstructure orientation in a tomographic 3D reconstruction. Per voxel, we quantitatively reconstruct the vector of the dominant local orientation and the amount of (an)isotropic scattering for relatively large samples using a standard medical X-ray setup. This is experimentally shown for various specimens exhibiting varying degrees of structural orderings.
Automodification switches PARP-1 function from chromatin architectural protein to histone chaperone
Authors: Muthurajan Uma M. , Hepler Maggie R. D. , Hieb Aaron R. , Clark Nicholas J. , Kramer Michael , Yao Tingting , Luger Karolin
Published: August 2014

Significance

Poly-ADP-ribosylation (PARylation) is an abundant posttranslational modification in eukaryotes. The responsible enzyme, poly [ADP-ribose] polymerase 1 (PARP-1), binds to chromatin and shapes its architecture. It is activated by DNA damage and other triggers, and catalyzes the addition of long chains of poly-ADP ribose (PAR) mainly to itself. The biological effects of PARylation are unknown. Here, we show that PARylation confers the ability to bind histones and to assemble nucleosomes upon PARP-1, and also affects its interaction with chromatin. The rapid turnover of PAR groups provides a mechanism for switching PARP-1 function from nucleosome binder to nucleosome assembler. This explains the involvement of active PARP-1 in both transcription and DNA damage repair, because histone chaperone activity is required during both processes.
Mannan induces ROS-regulated, IL-17A–dependent psoriasis arthritis-like disease in mice
Authors: Khmaladze Ia , Kelkka Tiina , Guerard Simon , Wing Kajsa , Pizzolla Angela , Saxena Amit , Lundqvist Katarina , Holmdahl Meirav , Nandakumar Kutty Selva , Holmdahl Rikard
Published: August 2014

Significance

We identified a previously undescribed disease mechanism for psoriasis (Ps) and psoriasis arthritis (PsA)-like disease by developing a new mouse model having characteristic features similar to those of Ps and PsA in human patients. Mannan-induced activation of tissue macrophages triggers IL-17A secretion from γδ T cells, causing Ps-like inflammation. Such inflammation was significantly increased under a reduced oxidative environment. Increased frequency of monocytes/macrophages, depletion experiments, and the disease suppressor function of macrophage-derived reactive oxygen species clearly argue in favor of a role for monocytes/macrophages in this disease model, which is in accordance with the findings in patients with the psoriatic form of skin lesions and arthritis. This novel PsA model could be immensely useful to test new therapeutics for patients with Ps and PsA.
Xylan utilization in human gut commensal bacteria is orchestrated by unique modular organization of polysaccharide-degrading enzymes
Authors: Zhang Meiling , Chekan Jonathan R. , Dodd Dylan , Hong Pei-Ying , Radlinski Lauren , Revindran Vanessa , Nair Satish K. , Mackie Roderick I. , Cann Isaac
Published: August 2014

Significance

Fermentation of dietary fiber in the lower gut of humans is a critical process for the function and integrity of both the bacterial community and host cells. Here we demonstrate that two human gut commensal
Bacteroides
are equipped with unique enzymes that allow degradation of xylan, a common hemicellulose in human diets. Furthermore, we identify a novel carbohydrate-binding module (CBM) family that disrupts the catalytic domain of a glycoside hydrolase 10 (GH10) endoxylanase and facilitates the hydrolytic activity of the enzyme. The conservation of the unique modular architecture of the GH10 endoxylanase in the genomes of diverse Bacteroidetes suggests a critical role in fiber digestion in this phylum.
Pseudomonas aeruginosa
triggers CFTR-mediated airway surface liquid secretion in swine trachea
Authors: Luan Xiaojie , Campanucci Verónica A. , Nair Manoj , Yilmaz Orhan , Belev George , Machen Terry E. , Chapman Dean , Ianowski Juan P.
Published: August 2014

Significance

Cystic fibrosis (CF) is a genetic disorder caused by mutations in the gene encoding for the anion channel cystic fibrosis transmembrane conductance regulator (CFTR). Several organs are affected in CF, but most of the morbidity and mortality comes from lung disease caused by the failure to clear bacteria. Bacterial clearance depends on a layer of airway surface liquid (ASL) covering the airways, rich in antimicrobial compounds and mucins, that removes bacteria from the airway through mucociliary clearance. This study provides the first demonstration that inhalation of bacteria triggers CFTR-dependent ASL secretion. We suggest that this response to inhaled pathogens is an important but previously unknown part of the innate immune response that would be missing in CF patients, resulting in reduced bacterial killing and facilitating infection.
Label-free probe of HIV-1 TAT peptide binding to mimetic membranes
Authors: Rao Yi , Kwok Sheldon J. J. , Lombardi Julien , Turro Nicholas J. , Eisenthal Kenneth B.
Published: August 2014

Significance

The TAT protein is important in the progression of AIDS. Studies show that a small highly charged region of the protein, the TAT peptide, enables the protein to penetrate cells. We have developed a laser method, which differs from traditional methods and, being sensitive to surface charge, enables us to probe mechanisms of binding and penetration of artificial membranes. Using this method, which does not require a label for detection, we measured the electric potential, the strength of TAT binding to artificial membranes, and the maximum number of TATs that bind to a given liposome. This special property to transport molecules across membranes, which could not penetrate otherwise, has delivery applications for molecules of biomedical importance.
Mitochondrial reactive oxygen species are scavenged by Cockayne syndrome B protein in human fibroblasts without nuclear DNA damage
Authors: Cleaver James E. , Brennan-Minnella Angela M. , Swanson Raymond A. , Fong Ka-wing , Chen Junjie , Chou Kai-ming , Chen Yih-wen , Revet Ingrid , Bezrookove Vladimir
Published: August 2014

Significance

Mitochondria are often considered a source of reactive oxygen species (ROS) that cause damage to cellular components including nuclear DNA. This endogenous damage is thought to underlie neurodegeneration, especially in diseases such as Cockayne syndrome (CS) that lack transcription-coupled DNA repair (TCR). We find no evidence, however, for any nuclear DNA damage from increased mitochondrial ROS. Our results indicate that the neurodegenerative symptoms in CS may be mitochondrial in origin, independent of nuclear DNA damage and repair.
Revisiting border conflicts between FrameNet and Construction Grammar
Authors: Timponi Torrent Tiago , Meireles Lage Ludmila , Sampaio Thais Fernandes , da Silva Tavares Tatiane , da Silva Matos Ely Edison
Published: August 2014

This paper proposes three policies for the annotation of constructions in FrameNet Brasil, and, potentially, in other FrameNets. Annotation policies are defined so as to both avoid uncontrolled redundancy in the database and respect the theoretical and methodological foundations of Frame Semantics and Construction Grammar. The first policy is concerned with the task of deciding whether a given piece of language should be analyzed as an instance of a construction, or as a valence pattern of a lexical unit; the second specifies criteria for the definition of Construct Elements; finally, the third policy regulates the interconnections between constructions and frames in the database.
Exploiting FrameNet for Swedish
Authors: Friberg Heppin Karin , Gronostaj Maria Toporowska
Published: August 2014

This paper presents work on developing Swedish FrameNet (SweFN) as a resource analogous to the original Berkeley-based FrameNet. We describe the theoretical and practical basics of FrameNet, and articulate some multilingual issues that arise in expanding a linguistic resource from one language to another. SweFN uses FrameNet as a starting point in order to save time and effort, and to make it compatible with other FrameNet-based resources. The lexical units are from the pivot lexicon SALDO, making SweFN compatible with other resources of the larger project SweFN++. It is a corpus-based resource, meant to support tasks within natural language processing relying on semantic data.
Multilingual lexicographic annotation for domain-specific electronic dictionaries
Authors: Timponi Torrent Tiago , Martins Salomão Maria Margarida , da Silva Matos Ely Edison , Gamonal Maucha Andrade , Gonçalves Júlia , de Souza Bruno Pereira , Gomes Daniela Simões , Peron-Corrêa Simone Rodrigues
Published: August 2014

This paper reports on the development of a domain-specific multilingual electronic dictionary covering the domains of soccer, tourism and the World Cup: the Copa 2014 FrameNet Brasil project. Specifically, we discuss three points: (i) the definition of the tourism frames and their deployment as interlingual representations; (ii) the implementation of the trilingual annotation software used for populating the Copa 2014 database; and (iii) the creation of the Translation relation, a computational solution for the deployment of frames as interlingual representations.
Lexical norms, language comprehension, and the epistemology of testimony
Authors: Begby Endre
Published: August 2014

It has recently been argued (for instance by Sanford Goldberg, expanding on earlier work by Tyler Burge) that public linguistic norms are implicated in the epistemology of testimony by way of underwriting the reliability of language comprehension. This paper argues that linguistic normativity, as such, makes no explanatory contribution to the epistemology of testimony, but instead emerges naturally out of a collective effort to maintain language as a reliable medium for the dissemination of knowledge. Consequently, the epistemologies of testimony and language comprehension are deeply intertwined from the start, and there is no room for grounding the one in terms of the other.
The role of phage display in therapeutic antibody discovery
Authors: Chan Conrad E. Z. , Lim Angeline P. C. , MacAry Paul A. , Hanson Brendon J.
Published: August 2014

Phage display involves the expression of selected proteins on the surface of filamentous phage through fusion with phage coat protein, with the genetic sequence packaged within, linking phenotype to genotype selection. When combined with antibody libraries, phage display allows for rapid in vitro selection of antigen-specific antibodies and recovery of their corresponding coding sequence. Large non-immune and synthetic human libraries have been constructed as well as smaller immune libraries based on capturing a single individual’s immune repertoire. This completely in vitro process allows for isolation of antibodies against poorly immunogenic targets as well as those that cannot be obtained by animal immunization, thus further expanding the utility of the approach. Phage antibody display represents the first developed methodology for high throughput screening for human therapeutic antibody candidates. Recently, other methods have been developed for generation of fully human therapeutic antibodies, such as single B-cell screening, next-generation genome sequencing and transgenic mice with human germline B-cell genes. While each of these have their particular advantages, phage display has remained a key methodology for human antibody discovery due its in vitro process. Here, we review the continuing role of this technique alongside other developing technologies for therapeutic antibody discovery.
The ratio of pattern speeds in double-barred galaxies
Authors: Font Joan , Beckman John E. , Zaragoza-Cardiel Javier , Fathi Kambiz , Epinat Benoit , Amram Philippe
Published: August 2014

We have obtained two-dimensional velocity fields in the ionized gas of a set of eight double-barred galaxies, at high spatial and spectral resolution, using their Hα emission fields measured with a scanning Fabry–Perot spectrometer. Using the technique by which phase reversals in the non-circular motion indicate a radius of corotation, taking advantage of the high angular and velocity resolution, we have obtained the corotation radii and the pattern speeds of both the major bar and the small central bar in each of the galaxies; there are few such measurements in the literature. Our results show that the inner bar rotates more rapidly than the outer bar by a factor between 3.3 and 3.6.
The Reliabilities of Radiographic Measurements of Cervical Sagittal Alignment in Ankylosing Spondylitis
Authors: Shin Jong Ki , Lee Jung Sub , Kang Sung Shik , Lee Jae Myung , Youn Bu Hyun
Published: August 2014

Study Design:

This is a prospective study design.

Objective:

To test the interobserver and intraobserver reliabilities of 5 specific measures of global cervical sagittal alignment in patients with ankylosing spondylitis (AS), and to suggest a better means of measuring cervical sagittal alignment.

Summary of Background Data:

The intraobserver and interobserver reliabilities of several different methods of measuring cervical lordosis have been reported. However, they have not been studied till yet in patients with AS.

Methods:

Interobserver and intraobserver reliabilities of 5 specific measures of cervical lordosis were evaluated in patients with AS. Eighty patients with AS were allocated to a nonankylosis or an ankylosis group, and the reliabilities of the Cobb C1–C7, Cobb C2–C7, centroid, posterior tangent, and Ishihara index methods were evaluated.

Results:

The intraclass and interclass correlation coefficients (ICCs) of all 5 methods were generally high. For the 80 study subjects, ICCs were ≥0.84 (excellent) for all 5 radiographic methods. However, comparison of the ICCs, 95% confidence intervals, and mean absolute differences (MAD) between groups with varying degrees of ankylosis showed that the reliability of lordosis measurements decreased as the severity of ankylosis increased. The 5 methods consistently demonstrated higher ICCs for both interobserver and intraobserver comparisons in the nonankylosis group. However, in the ankylosis group, the Cobb C1–C7 method demonstrated high ICCs for both interobserver and intraobserver comparisons, whereas the other 4 methods had high ICCs only for intraobserver comparisons. The intraobserver MADs were similar for the 5 methods (2.4–3.9), but the interobserver MADs of measurement methods in both groups showed low measurement reliability except for the Cobb C1–C7 methods.

Conclusions:

This study provides a reliability analysis of different cervical lordosis measurement methods in AS, and shows that the Cobb C1–C7 method provides a reliable means for measuring cervical lordosis in AS.
Family Satisfaction in Critical Care Units: Does an Open Visiting Hours Policy Have an Impact?
Authors: Baharoon Salim , Al Yafi Walid , Al Qurashi Ahmad , Al Jahdali Hamdan , Tamim Hani , Alsafi Eiman , Al Sayyari Abdullah A.
Published: August 2014

Objective

For critically ill patients, the interaction between health care providers and family members is essential in daily decision making. Improving this relationship has a positive impact on satisfaction with the overall care provided to patients and reduces family member symptoms of depression, anxiety, and posttraumatic stress disorder. In this study, we analyzed the impact of visitation policy (open versus restricted) on family satisfaction using the previously well-validated Critical Care Family Satisfaction Survey (CCFSS) questionnaire.

Methods

This is a cross-sectional prospective observational study conducted between November 1, 2009, and January 31, 2010, in 2 critical care units with 2 different visiting policy systems, unit A (open visiting hours) and B (restricted visiting hours), comparing family satisfaction in both units using the CCFSS questionnaire. Responses were grouped in 5 satisfaction constructs, namely, the support construct, which assesses the degree of satisfaction with the support of the intensive care staff as perceived by relatives; the assurance construct, which assesses the degree of satisfaction regarding honest answers being given and the responder's confidence that the patient is receiving the best care possible; the proximity construct, which assesses the degree of satisfaction with the physical and emotional access to the patient; the information construct, which assesses the degree of satisfaction with the adequacy of information given to relatives; and the comfort construct, which assesses satisfaction with physical comfort and amenities.

Results

During the study period, 115 questionnaires were distributed in each of the 2 sites. The response rates in units A and B were 92% (106) and 100% (115), respectively. The mean stay time in the intensive care unit was 3.7 days. There were more trauma cases in unit A and more cardiac patients in unit B. There was no significant difference between the 2 units in any of the 5 satisfaction constructs, the support, assurance, proximity, information, and comfort constructs, although there was a nonsignificant trend favoring the unit with the more liberal visit policy regarding amenities (unit A).

Conclusions

We concluded that family satisfaction to care provided in intensive care as measured by the CCFSS questionnaire was not influenced by frequency of visitation among Saudi families. Factors other than open visiting hours may be important to evaluate.