bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of processing conditions on rheological, thermal, and electrical properties of multiwall carbon nanotube/epoxy resin composites
Authors: Ivanov E. , Kotsilkova R. , Krusteva E. , Logakis E. , Kyritsis A. , Pissis P. , Silvestre C. , Duraccio D. , Pezzuto M.
Published: January 2011

We report on the effect of processing conditions on rheology, thermal and electrical properties of nanocomposites containing 0.02–0.3 wt % multiwall carbon nanotubes in an epoxy resin. The influence of the sonication, the surface functionalization during mixing, as well as the application of external magnetic field (EMF) throughout the curing process was examined. Rheological tests combined with optical microscopy visualization are proved as a very useful methodology to determine the optimal processing conditions for the preparation of the nanocomposites. The Raman spectra provide evidence for more pronounced effect on the functionalized with hardener compositions, particularly by curing upon application of EMF. Different chain morphology of CNTs is created depending of the preparation conditions, which induced different effects on the thermal and electrical properties of the nanocomposites. The thermal degradation peak is significantly shifted towards higher temperatures by increasing the nanotube content, this confirming that even the small amount of carbon nanotubes produces a strong barrier effect for the volatile products during the degradation. The ac conductivity measurements revealed lower values of the percolation threshold (pc) in the range of 0.03–0.05 wt %. CNTs for the nanocomposites produced by preliminary dispersing of nanotubes in the epoxy resin, compared to those prepared by preliminary functionalization of the nanotubes in the amine hardener. This is attributed to the higher viscosity and stronger interfacial interactions of the amine hardener/CNT dispersion which restricts the reorganization of the nanotubes. The application of the EMF does not influence the pc value but the dc conductivity values (σdc) of the nanocomposites increased at about one order of magnitude due to the development of the aforementioned chain structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Free volume changes on optical switching in azobenzene‐polymethylmethacrylate blends studied by a pulsed low‐energy positron beam
Authors: Harms Stephan , Rätzke Klaus , Pakula Christina , Zaporojtchenko Vladimir , Strunskus Thomas , Egger Werner , Sperr Peter , Faupel Franz
Published: January 2011

Polymers including chromophores, which can be switched by light, have been studied extensively during the last years due to a host of potential applications which arise from the marked changes in physical properties on switching. Even though there is clear evidence that the free volume has a significant influence on the isomerization kinetics, the question of free volume changes on switching was only addressed recently. Using a pulsed low‐energy positron beam the ortho‐positronium lifetime τ3 was taken as a very sensitive free volume probe, and no change in free volume was detected on isomerization in an azobenzene‐polymethylmethacrylate (PMMA) copolymer containing about 8 wt % of the azobenzene moiety. Here, we report for the first time on free volume changes in an azobenzene‐PMMA blend with an azobenzene moiety concentration as high as 40 wt %. Using the same pulsed low‐energy positron beam, small but significant changes of τ3 were observed between the structurally relaxed dark and the UV‐illuminated states suggesting a decrease in free volume of the order of 10%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Urinary CD14 as a potential biomarker for benign prostatic hyperplasia – discovery by combining MALDI‐TOF‐based biostatistics and ESI‐MS/MS‐based stable‐isotope labeling
Authors: Cheng Hong‐Lin , Huang Hung‐Jen , Ou Bing‐Yuan , Chow Nan‐Haw , Chen Yen‐Wen , Tzai Tzong‐Shin , Wu Chin‐Jen , Chen Shu‐Hui
Published: January 2011

Purpose: Quest for specific urinary biomarkers for benign prostatic hyperplasia (BPH).

Experimental design: Proteomics studies were conducted with urines of the training set to discovering marker candidates that could differentiate BPH from normal subjects by matching results deduced from MALDI‐TOF of individual samples and results deduced from nanoLC‐ESI‐MS/MS‐based stable isotope dimethyl labeling of two pooled samples (BPH and normal). Samples were digested before analysis and such an approach takes into account the subject‐to‐subject variation and differential amount, as well as protein identification. Selected markers were validated by ELISA conducted on the training set and the test set as well as another set of urines collected from prostate cancer patients.

Results: Nine marker candidates were identified from proteomics studies; CD14, prostate‐specific antigen and pancreatic α‐amylase precursor were further selected for ELISA validation. Urinary CD14 is among the best match with high specificity (>81%) for both training and test sets. In addition, from the study of prostate cancer patients, CD14 also allows the distinction of BPH from cancer with high specificity (84–100%) when combined with urinary prostate‐specific antigen.

Conclusions and clinical relevance: Urinary CD14 is suggested to have a high specificity in the diagnosis of BPH in distinction from normal as well as cancer subjects.
Influence of tube diameter on carbon nanotube interconnect delay and power output
Authors: Rai Mayank Kumar , Sarkar Sankar
Published: January 2011

This paper address the influence of tube diameter on single walled carbon nanotube (CNT) bundle interconnect delay and power output in Very Large Scale application. We find that single‐walled carbon nanotube (SWCNT) bundle interconnects are of lower delay than copper interconnect due to low resistance and inductance. Power dissipation decreases with increase in tube diameter of the constituent SWCNT. CNT interconnect resistance and inductance increases with increase in tube diameter. On the other hand, with increase in tube diameter interconnect capacitance decreases. There is a trade off between delay and power dependence on tube diameter.
SR phase contrast imaging to address the evolution of defects during SiC growth
Authors: Argunova Tatiana S. , Gutkin Mikhail Yu. , Je Jung Ho , Mokhov Evgeniy N. , Nagalyuk Sergey S. , Hwu Yeukuang
Published: January 2011

Sliced SiC boule grown by physical vapor transport is investigated using synchrotron white beam phase contrast imaging combined with Bragg diffraction. The evolution of defects is revealed. In the early growth stage, foreign polytype inclusions not only induce massive generation of full‐core dislocations and dislocated micropipes but also attract them, forming slit‐type pores at the boundaries of inclusions.

In the intermediate stage, when inclusions stop to grow and become overgrown by the matrix, the pore density significantly reduces, which is attributed to their transformation into new micropipes. In the later stage, the micropipe density decreases, providing evidence for their partial annihilation and healing. Mechanisms for the evolution from inclusions to pores and finally to micropipes during the crystal growth are further discussed.
Solution‐processed semitransparent p–n graphene oxide:CNT/ZnO heterojunction diodes for visible‐blind UV sensors
Authors: Cuong Tran Viet , Tien Huynh Ngoc , Luan Van Hoang , Pham Viet Hung , Chung Jin Suk , Yoo Dae Hwang , Hahn Sung Hong , Koo Kee‐Kahb , Kohl Paul A. , Hur Seung Hyun , Kim Eui Jung
Published: January 2011

A high quality transparent p–n heterojunction device comprised of 1D zinc oxide (ZnO) nanorods (NRs) and an ultrathin 2D graphene oxide (GO):carbon nanotube (CNT) hybrid film was fabricated through a solution process. The turn on voltage and ideality factor of the device were 1.5 V and 6.1, respectively. Optical measurements revealed that the UV absorption of the ZnO NRs increased after a GO:CNT hybrid film was spray‐coated onto the NRs. As a result, the device exhibited a high response to UV illumination. The fabricated diode displayed high rectifying characteristics and excellent performance as a visible‐blind UV sensor.
Temperature‐dependent light‐output characteristics of GaInN light‐emitting diodes with different dislocation densities
Authors: Chhajed Sameer , Cho Jaehee , Schubert E. Fred , Kim Jong Kyu , Koleske Daniel D. , Crawford Mary H.
Published: January 2011

We have experimentally investigated the temperature dependence of optical‐output power of light‐emitting diodes (LEDs) with different threading dislocation densities (TDDs) to assess the influence of the TDD on the temperature stability of LEDs. Whereas the LED with high TDD shows a 64% decrease in optical‐output power when the ambient temperature increases from 20 to 150 °C, the LED with low TDD shows only a 54% decrease. The temperature dependence of the optical‐output power and current dependence of the characteristic temperature Tch of LEDs shows that short radiative recombination lifetime and low TDDs are essential to obtain LED characteristics that are tolerant of high temperatures.
Quantum coherence in photosynthetic complexes
Authors: Calhoun Tessa R. , Fleming Graham R.
Published: January 2011

The initial steps of photosynthesis require the absorption and subsequent transfer of energy through an intricate network of pigment–protein complexes. Held within the protein scaffold of these complexes, chromophore molecules are densely packed and fixed in specific geometries relative to one another resulting in Coulombic coupling. Excitation energy transfer through these systems can be accomplished with near unity quantum efficiency [Wraight and Clayton, Biochim. Biophys. Acta 333, 246 (1974)]. While replication of this feat is desirable for artificial photosynthesis, the mechanism by which nature achieves this efficiency is unknown. Recent experiments have revealed the presence of long‐lived quantum coherences in photosynthetic pigment–protein complexes spanning bacterial and plant species with a variety of functions and compositions. Its ubiquitous presence and wavelike energy transfer implicate quantum coherence as key to the high efficiency achieved by photosynthesis.
Time‐resolved spectroscopy of exciton‐related states in single crystals and single crystalline films of Lu3Al5O12 and Lu3Al5O12:Ce
Authors: Babin V. , Bichevin V. , Gorbenko V. , Kink M. , Makhov A. , Maksimov Yu. , Nikl M. , Stryganyuk G. , Zazubovich S. , Zorenko Yu.
Published: January 2011

Time‐resolved excitation spectra were measured at the same conditions at 10 K in the 4–20 eV energy range for the luminescence of self‐trapped and various localized excitons as well as of Ce3+‐, Pb2+‐, and Bi3+‐related centers in single crystals and single crystalline films of Lu3Al5O12 garnet. The decay kinetics of the intrinsic 4.9 and 3.65 eV luminescence of Lu3Al5O12 crystals were studied at 4.2–300 K in the 10−9–10−3 s time range. The origin and structure of the exciton states as well as the luminescence, energy transfer, and recombination processes, taking place under excitation in the exciton absorption region, were discussed. The influence of various defects on the scintillation characteristics of Ce3+‐ and Pr3+‐doped Lu3Al5O12 crystals was considered.
Crystal orientation of GaN layers on (1010) m‐plane sapphire
Authors: Frentrup Martin , Ploch Simon , Pristovsek Markus , Kneissl Michael
Published: January 2011

Based on the atomic arrangement of the $(10{\bar {1}}0)$ m‐plane sapphire surface, we have developed a model for the initial nucleation process of gallium‐nitride (GaN). This model describes why $(11{\bar {2}}2)$ and $(10{\bar {1}}{\bar {3}})$ are the preferred orientations of GaN on the $(10{\bar {1}}0)$ sapphire. The experimental results from high‐resolution X‐ray diffraction measurements, like the crystallographic relations and the twinning of the $(1{\bar {1}}0{\bar {3}})$ orientation are explained by the model too. Our model also predicts that $(11{\bar {2}}2)$ thin films are metal‐polar and $(1{\bar {1}}0{\bar {3}})$ thin films are nitrogen‐polar.
Stacking fault‐related luminescence features in semi‐polar GaN
Authors: Tischer Ingo , Feneberg Martin , Schirra Martin , Yacoub Hady , Sauer Rolf , Thonke Klaus , Wunderer Thomas , Scholz Ferdinand , Dieterle Levin , Müller Erich , Gerthsen Dagmar
Published: January 2011

We report about defect‐related emission bands in GaN. We establish a direct correlation between results from spatially and spectrally resolved cathodoluminescence bands at 3.32, 3.23, 3.20, 3.16, and 3.07 eV with findings obtained by transmission electron microscopy. The band around 3.32 eV was unambiguously assigned to I2 basal plane stacking faults (BSFs). The bands at 3.23, 3.20, 3.16, and 3.07 eV were detected in sample regions, where BSFs exist, but were not assigned to specific defect types, except for the 3.07 eV line which is a phonon replica of the transition at 3.16 eV.
Ni‐doped ZnO: Studies on structural and magnetic properties
Authors: Mohapatra J. , Mishra D. K. , Kamilla S. K. , Medicherla V. R. R. , Phase D. M. , Berma V. , Singh S. K.
Published: January 2011

The Zn1–xNixO (0 ≥ x ≥ 0.1) systems were synthesized by a solid‐state reaction technique at 700 °C for 7 h. The X‐ray diffraction (XRD) pattern reveals the presence of secondary peaks due to NiO in Ni overdoped (>0.03) ZnO matrix. The compositional mapping on 5% Ni‐doped ZnO on an electron probe microstructural analyzer (EPMA) indicates the segregation of oxides of Ni on the bulk surface. The ZnO samples doped with 3 and 5% Ni exhibit room‐temperature ferromagnetism (RTFM). But, 7 and 10% Ni‐doped ZnO samples do not exhibit ferromagnetism. Possibly, the enhanced antiferromagnetic interaction between neighboring Ni–Ni ions suppresses the ferromagnetic ordering, at higher doping concentrations of Ni, resulting in a rapid decrease in magnetic moments.
Effect of chirality and curvature of single‐walled carbon nanotubes on the adsorption of uracil
Authors: Rajarajeswari M. , Iyakutti K. , Kawazoe Y.
Published: January 2011

Adsorption of uracil on single‐walled carbon nanotubes (SWCNTs) (5,2) and (5,5) in the presence of water molecules has been investigated using first‐principles technique. Uracil is adsorbed on the nanotube noncovalently through π–π stacking interaction. The binding strength of uracil varies with the chirality of the carbon nanotubes. Addition of water molecules inside and outside the nanotube altered the interaction of the uracil with the nanotube and modifies the binding strength. Orientation of the water molecule and the charge transfer through the CH bonds are the important factors in the interaction of the water molecule with the carbon nanotube.
Graphene allotropes
Authors: Enyashin Andrey N. , Ivanovskii Alexander L.
Published: January 2011

Using the density‐functional‐based tight‐binding method (DF‐TB) we performed a systematic comparative study of stability, structural, and electronic properties for 12 various types of graphene allotropes, which are likely candidates for engineering of novel graphene‐like materials.
Extra formation of positronium in amorphous polymers at low temperature
Authors: Laforest N. , Bas C. , De Baerdemaker J. , Djourelov N. , Dauwe C.
Published: January 2011

Positron annihilation lifetime spectroscopy measurements of polystyrene and poly(methyl methacrylate) have been performed at 20 K during ∼400 h. An increase of the probability of positronium (Ps) formation with irradiation time is observed. This effect is due to the accumulation of shallow‐trapped electrons which are stable at low temperatures. Detailed analyses of the lifetime spectra within the blob model framework show that these electrons induced by the previous positron tracks act as extra blob electrons: they either recombine with a cation or form Ps. This kinetic analysis introduced by the blob model indicates that no formation of Ps occurs after the blob recombination in these amorphous polymers. An increase of the free positron lifetime with the measuring time is also observed. This effect can not be explained in terms of artifact of discrete analysis caused by the existence of an ortho‐positronium lifetime distribution.
Scanning thermal microscopy: A nanoprobe technique for studying the thermal properties of nanocomponents
Authors: Wielgoszewski Grzegorz , Sulecki Przemysław , Gotszalk Teodor , Janus Paweł , Grabiec Piotr , Hecker Michael , Ritz Yvonne , Zschech Ehrenfried
Published: January 2011

In this paper, a novel micromachined scanning thermal microscopy (SThM) microcantilever with a sharp, conductive platinum tip is proposed for temperature and thermal conductivity measurements in sub‐micron structures of micro‐ and nanoelectronic components. The idea and physical background of SThM operation is presented, together with brief description of probes and example images of a planar polycrystalline‐silicon microfuse obtained using passive‐ and active‐mode SThM.
Effect of electronic structure on single‐photon emission in InAs/InP quantum dot with quasi‐resonant excitation
Authors: Miyazawa T. , Takemoto K. , Nakaoka T. , Saito T. , Hirose S. , Sakuma Y. , Yokoyama N. , Arakawa Y.
Published: January 2011

We investigated the electronic structures of so‐called ‘double‐capped’ InAs/InP quantum dot suitable for a 1.55‐μm band single‐photon emitter. From a transmission‐electron‐microscope image of the quantum dots, we extracted accurate information of the size and shape. We calculated the electron and hole eigenenergies by applying an 8‐band k·p perturbation method into the quantum dot model based on the obtained size and shape. The calculated energies of the excitonic excited states agreed well with the resonant absorption peaks in a previously measured photoluminescence excitation spectrum with peaks that had been selected for quasi‐resonant excitation to improve single‐photon purity. This result suggests that the direct exciton creation into these states contributes to the suppression of excess carriers in the vicinity of the quantum dots, thus leading to a decrease in unwanted multiple‐photon emission probabilities. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Yield shear stress dependence on nanoindentation strain rate in bulk GaN crystal
Authors: Fujikane Masaki , Yokogawa Toshiya , Nagao Shijo , Nowak Roman
Published: January 2011

The strain rate controlled nanoindentation was performed in c‐plane (0001) and m‐plane (10–10) GaN crystals. The indentation velocity was ranged from 0.16 to 800 nm/s. The significant displacement bursts were detected after every perfect elastically deformations and they allowed us to calculate the maximum shear stress τmax. The τmax dependences on strain rate in two crystal orientations involved that the two perpendicular compressions induced the same plastic deformation mechanism. Comparing the obtained τmax with the Peierls potential and maximum shear stress in each slip system, {10–11} 〈11–20〉 dislocation nucleation may support the origin of the plastic deformation in GaN crystal. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of growth temperature of partial GaAs cap on InAs quantum dots in In‐flush process for single dot spectroscopy
Authors: Kumagai Naoto , Ohkouchi Shunsuke , Shirane Masayuki , Igarashi Yuichi , Nomura Masahiro , Ota Yasutomo , Yorozu Shinichi , Iwamoto Satoshi , Arakawa Yasuhiko
Published: January 2011

We have investigated effects of growth temperature of partial GaAs cap (Tcap) on InAs quantum dots (QDs) in indium‐flush (In‐flush) process with atomic force microscopy (AFM) and micro photoluminescence (μ‐PL) measurements. Tcap in In‐flush process are varied from 385 °C to 485 °C as an experimental parameter. In order to investigate the effects of Tcap on structural property of single InAs QD, shape of QD in initial capping process are characterized by AFM measurements in air at room temperature. While isotropic shape of QDs is kept in low Tcap conditions below about 440 °C, in‐plane anisotropy of initial shape of QDs are increased with increasing of Tcap due to elongation to the [1$ \bar 1 $0] direction. μ‐PL measurements are performed at 7K for the investigation of the effects of Tcap on optical property in single InAs QDs. In low Tcap conditions from 410 °C to 435 °C, distinct emissions from excitonic states in single QDs are observed. In the same Tcap range, the AFM result shows that isotropic shape of QDs is kept. On the other hand, in high Tcap conditions above about 440 °C, indefinite peaks and broad emissions appear remarkably. Excitonic emissions which are observed in low Tcap range are hardly observed in this high Tcap range (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarization dependence of two‐photon absorption coefficient and nonlinear susceptibility tensor in InP
Authors: Matsusue Toshio , Bando Hiroyuki , Fujita Shoichi , Takayama Yusuke
Published: January 2011

Two‐photon absorption (TPA) effect in (001) InP is investigated using fs laser. Its dependences on wavelength and polarization are clarified by single and double beam methods with linearly polarized lights. Characteristic features are revealed and discussed with scaling law, crystal bonding and mutual relation of polarizations for double beams. The results are successfully analyzed on the basis of the third‐order susceptibility tensor for comprehensive understanding of TPA effect at any polarization geometry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thin film bilayers of multiferroic bismuth ferrite on Pt–Si substrate
Authors: Wu Jiagang , Wang John , Xiao Dingquan , Zhu Jianguo
Published: January 2011

A multiferroics/multiferroics BiFeO3/Bi0.90La0.10Fe0.90Zn0.10O3 (BFO/BLFZO) bilayer was deposited on Pt/TiO2/SiO2/Si substrates by radio frequency sputtering. The BLFZO layer strongly affects the phase purity, orientation growth, and leakage current of BFO layer. The bilayered capacitor exhibits a high dielectric permittivity of ∼162 and an improved magnetic behavior of 2Ms ∼ 34.6 emu/cm3, together with an excellent fatigue endurance. A remanent polarization of 2Pr ∼ 116.2 μC/cm2 for the bilayered capacitor is better than those of reported BFO bilayers. The impedance study indicates that lower freely mobile charges are responsible for the improved electrical behavior of the BFO/BLFZO bilayer. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectrum of infrasound radiation from supercell storms
Authors: Akhalkatsi M. , Gogoberidze G.
Published: January 2011

We consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high values of convective available potential energy (CAPE), which are known to favour significant tornadoes, also lead to a strong enhancement of a supercell's low‐frequency acoustic radiation. Copyright © 2011 Royal Meteorological Society
Robust adaptive‐sliding mode tracking of state delayed nonlinear plants with actuator failures
Authors: Mirkin Boris , Gutman Per‐Olof , Shtessel Yuri
Published: January 2011

In this paper, we develop two sliding mode—model reference adaptive control (MRAC) schemes for a class of delayed nonlinear dynamic systems under actuator failure that are robust with respect to actuator failures, to an unknown plant delay, to a nonlinear perturbation, and to an external disturbance with unknown bounds. Appropriate Lyapunov–Krasovskii‐type functionals with ‘virtual’ adaptation gains are introduced to design the adaptation algorithms, and to prove stability. Two different controllers are designed: one with discontinuous and another with continuous control actions, respectively. Copyright © 2011 John Wiley & Sons, Ltd.
Fusion of visual and infrared face verification systems
Authors: Choi Byounggyu , Kim Youngsung , Toh Kar‐Ann
Published: January 2011

This paper presents a two‐stage procedure to combine multiple face traits for identity authentication. At the first stage, a high dimensional random projection is applied to the raw visual and infrared face images to extract useful information relevant to each identity. This is followed by a dimension reduction using eigenfeature regularization and extraction (ERE). At the second stage, the scores from two verification systems based on each face modality are fused by an error minimization algorithm. This error minimization algorithm directly optimizes the verification accuracy by adjusting the parameters of a polynomial classifier. Two data sets consisting of visual and infrared face images have been used for experimentation. Our empirical observation shows encouraging results regarding the effectiveness of the proposed method. Copyright © 2011 John Wiley & Sons, Ltd.
TCP SYN‐based DDoS attack on EKG signals monitored via a wireless sensor network
Authors: Petana Einar , Kumar Sanjeev
Published: January 2011

Internet distributed denial of service (DDoS) attacks are known to exhaust computing resources of a computer. In many cases, even if the attack is not sufficiently strong to completely crash a computing system, its adverse effects can be devastating for the information being processed on the system. When such information is too critical as an electrocardiogram (EKG) signal, the signal itself becomes vulnerable to such attacks also. In this experimental paper, we evaluate the adverse effects of TCP SYN‐based DDoS attacks on EKG signals remotely collected by using wireless sensor networks (WSNs). In lab, we deployed two applications (Serial Forwarder and Oscilloscope GUI) to display the EKG signal on remote monitoring station. Such EKG signal was delivered by a WSN (motes running a modified version of OscilloscopeRF with an analog channel enabled and TOSBase) to collect and send the EKG data. It was found that even though the computing resource of the remote computer running the applications to display the EKG signals was almost exhausted under a DDoS attack, the system was still responding (alive) and displaying the collected EKG signal. However, the normal EKG signal pattern was distorted due to the resource exhaustion caused by the DDoS attack, which in turn made the EKG signal unreliable for medical diagnosis and remote monitoring. In order to understand effect of TCP SYN attack on the EKG signal pattern, the attack was launched at different loads in a controlled lab environment. Finally, an Intrusion Prevention System was deployed in the network to mitigate the adverse effects of attack in the network in an attempt to recover a good EKG signal. Copyright © 2011 John Wiley & Sons, Ltd.
Using general systems theory to understand how farmers manage variability
Authors: Kaine Geoff , Cowan Lisa
Published: January 2011

Climate change is likely to increase the variability in environmental conditions that Australian farmers will have to contend with, potentially threatening farm viability. In this research we use general systems theory to describe how farmers use the three types of system regulators (aggregation, error control and anticipation) to manage variability in the environment. We present codling moth management as an example of system regulation in agriculture. We found that adaptation to climate change is likely to require that farmers modify the structure of their farm systems by changing their combination of system regulators. Decisions regarding changes in structure may favour certain types or system regulators over others. This has implications for policy development to support farm adaptation. Copyright © 2011 John Wiley & Sons, Ltd.
Progressive collapse analysis of an RC building with exterior partially infilled walls
Authors: Tsai Meng‐Hao , Huang Tsuei‐Chiang
Published: January 2011

Exterior partially infilled walls of RC condominium buildings are often monolithically cast with beams and/or columns in Taiwan. In practice, they are regarded as non‐structural elements in usual structural design, and only their weight is conservatively considered. In this study, effects of three common types of exterior partially infilled walls on the progressive collapse potential of an RC building are investigated. Linear and nonlinear static analyses under different column‐loss scenarios are carried out. Analysis results indicate that influence of the partially infilled walls differs from each type. Changes in the demand‐to‐capacity ratios indicate that without considering the walls, the moment demand of beams may be overestimated. However, their shear demand may be underestimated, especially with the panel‐type walls. Meanwhile, they may increase the collapse resistance of the building frame under column loss but with decreased ductility capacity. From the structural aspect, with a constant opening rate of 60%, the wing‐type wall is a better option than the parapet‐ and panel‐type walls. The panel‐type wall appears to be the worst choice since shear failure of their connected beam members may be induced. Copyright © 2011 John Wiley & Sons, Ltd.
Accuracy of sonographic weight estimation as a function of fetal sex
Authors: Melamed N. , Ben‐Haroush A. , Meizner I. , Mashiach R. , Glezerman M. , Yogev Y.
Published: January 2011

Objectives

To determine whether the accuracy of sonographic fetal weight estimation is related to fetal sex.

Methods

The accuracy of sonographic fetal weight estimation was compared between male and female fetuses using 3672 sonographic weight estimations performed within 3 days prior to delivery. Fetal weight was estimated using eight regression models that are based on different combinations of the following biometric parameters: abdominal circumference (AC), femur diaphysis length (FL), biparietal diameter (BPD) and head circumference (HC).

Results

In seven out of the eight models tested, the presence of a male fetus was associated with a significantly lower systematic error compared with a female fetus (−0.2 to 2.1% vs. 1.3 to 6%, P < 0.001). On multivariate analysis, fetal sex was independently associated with sonographic accuracy so that the likelihood of a weight estimation within 10% of birth weight was 30% higher for male fetuses compared with female fetuses. The biometric parameters that contributed most to these sex‐related differences were FL and AC, while models that included HC were associated with the lowest differences in the systematic error between male fetuses and female fetuses. For most models, the random error and correlation between estimated weight and birth weight were not affected by fetal sex (8.1–12.8% vs. 8.2–13.6%, and 0.856–0.944 vs. 0.842–0.944, respectively).

Conclusion

Sonographic estimation of fetal weight is more accurate for male fetuses than for female fetuses. The use of sex‐specific models may improve the accuracy of fetal weight estimation for female fetuses. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Isolated hyperechoic fetal colon before 36 weeks' gestation reveals cystinuria
Authors: Amat S. , Czerkiewicz I. , Benoist J.‐F. , Eurin D. , Fontanges M. , Muller F.
Published: January 2011

Objectives

To determine whether there is an association between the fetal ultrasound finding of hyperechoic colon and the gestational age at which it presents and cystinuria.

Methods

A prospective national survey was performed in France including all observations of isolated fetal hyperechoic colon detected at routine second‐ and third‐trimester ultrasound over a 2‐year period. Collected images were reviewed by experts. Colon was defined as being hyperechoic when its echogenicity was at least equal to that of the iliac bone. It was diagnosed when large tubular echogenic portions of the colon, without a focal mass and without posterior acoustic shadows, were observed at the periphery of the abdomen. Urinary amino acid analysis was performed after birth in the cases identified to test for cystinuria.

Results

Nineteen fetuses with ultrasound findings of hyperechoic colon were included, and the mothers of 16 of these agreed to participate in the study. In eight of nine cases of hyperechoic colon observed before 36 weeks' gestation cystinuria was confirmed at birth. In the seven remaining cases, observed after 36 weeks, none was found to have cystinuria and all had normal images at previous routine ultrasound scans at 22 and 33 weeks. When present, no difference in the sonographic appearance of hyperechoic colon was noted between the two groups. In the cystinuria‐affected cases, the length of the hyperechoic mass appeared to increase with gestational age.

Conclusions

In our experience, the presence of a hyperechoic colon at routine ultrasound scan before 36 weeks' gestation should prompt screening for cystinuria at birth, while later observation (> 36 weeks) of this finding does not appear to be related to any disease. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal tumors of the choroid plexus: is differential diagnosis between papilloma and carcinoma possible?
Authors: Anselem O. , Mezzetta L. , Grangé G. , Zerah M. , Benard C. , Marcou V. , Fallet‐Bianco C. , Adamsbaum C. , Tsatsaris V.
Published: January 2011

Fetal choroid plexus tumors are uncommon. The prognosis is widely variable and depends on the histological findings: papilloma or carcinoma. We report a case of prenatal diagnosis of choroid plexus mass detected by ultrasound at 33 weeks of gestation. Prenatal (T1, T2, T2* and diffusion weighted sequences) magnetic resonance imaging (MRI) was used to rule out a hematoma. Follow‐up examination by ultrasound and MRI revealed a significant increase in the volume of the mass, suggesting a diagnosis of malignant tumor. A healthy neonate was delivered by Cesarean section at 38 weeks of gestation. Full surgical excision of the tumor was performed at 20 days after delivery and histological analysis revealed a papilloma. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Design of a tower and drive train damping controller for the three‐bladed controls advanced research turbine operating in design‐driving load cases
Authors: Darrow J. , Johnson K. , Wright A.
Published: January 2011

Wind turbines experience both fatigue and extreme loading, and individual components of a wind turbine are affected differently by these loads. The current practice to achieve the typical 20 year design life is to build a turbine with robust components that can withstand fatigue and extreme loads for this duration. Unfortunately, overbuilding of components may lead to higher‐than‐necessary initial capital costs. In this research, we studied design‐driving load cases and designed advanced control algorithms aimed at enabling a decrease in initial capital cost. Our approach used a subset of a full International Electrotechnical Commission loads case analysis and selected major components experiencing design‐driving extreme loads that can be alleviated using advanced control. We first describe the results from the loads case analysis and then discuss the components on which we focused the advanced control design. We next describe the controller design and finally compare the results from the advanced controller simulations with those using a baseline controller. The baseline consists of a nonlinear torque controller below rated wind speed and a proportional‐integral‐derivative‐like controller above rated and the advanced controller uses proportional feedback and state‐space design to reduce tower bending and drive train torsional loads. Copyright © 2011 John Wiley & Sons, Ltd.
Applications of tensor (multiway array) factorizations and decompositions in data mining
Authors: Mørup Morten
Published: January 2011

Tensor (multiway array) factorization and decomposition has become an important tool for data mining. Fueled by the computational power of modern computer researchers can now analyze large‐scale tensorial structured data that only a few years ago would have been impossible. Tensor factorizations have several advantages over two‐way matrix factorizations including uniqueness of the optimal solution and component identification even when most of the data is missing. Furthermore, multiway decomposition techniques explicitly exploit the multiway structure that is lost when collapsing some of the modes of the tensor in order to analyze the data by regular matrix factorization approaches. Multiway decomposition is being applied to new fields every year and there is no doubt that the future will bring many exciting new applications. The aim of this overview is to introduce the basic concepts of tensor decompositions and demonstrate some of the many benefits and challenges of modeling data multiway for a wide variety of data and problem domains. © 2011 John Wiley & Sons, Inc.WIREs Data Mining Knowl Discov2011 1 24‐40 DOI: 10.1002/widm.1

This article is categorized under:

Algorithmic Development > Scalable Statistical Methods

Technologies > Classification

Technologies > Machine Learning

Technologies > Structure Discovery and Clustering
Data mining of functional RNA structures in genomic sequences
Authors: Le Shu‐Yun , Shapiro Bruce A.
Published: January 2011

The normal functions of genomes depend on the precise expression of messenger RNAs and noncoding RNAs (ncRNAs) such as transfer RNAs and microRNAs in eukaryotes. These ncRNAs and functional RNA structures (FRSs) act as regulators or response elements for cellular factors and participate in transcription, posttranscriptional processing, and translation. Knowledge discovery of these FRSs in huge DNA/RNA sequence databases is a very important step to reach our goal of going from genomic sequence data to biological knowledge for understanding RNA‐based regulation. Analyses of a large number of FRSs have indicated that the FRS can be well characterized by some quantitative measures such as significance and well‐ordered scores of the local segment. Various data mining tools have been developed and successfully applied to FRS discovery in genomic sequence databases. Here, we summarize our efforts in the computational discovery of structured features of ncRNAs and FRSs within complex genomes by EDscan and SigED. © 2011 John Wiley & Sons, Inc. WIREs Data Mining Knowl Discov 2011 1 88–95 DOI: 10.1002/widm.13

This article is categorized under:

Algorithmic Development > Biological Data Mining

Algorithmic Development > Spatial and Temporal Data Mining

Application Areas > Health Care

Technologies > Structure Discovery and Clustering
Rough clustering
Authors: Lingras Pawan , Peters Georg
Published: January 2011

Traditional clustering partitions a group of objects into a number of nonoverlapping sets based on a similarity measure. In real world, the boundaries of these sets or clusters may not be clearly defined. Some of the objects may be almost equidistant from the center of multiple clusters. Traditional set theory mandates that these objects be assigned to a single cluster. Rough set theory can be used to represent the overlapping clusters. Rough sets provide more flexible representation than conventional sets, at the same time they are less descriptive than the fuzzy sets. This paper describes the basic concept of rough clustering based onk‐means, genetic algorithms, Kohonen self‐organizing maps, and support vector clustering. The discussion also includes a review of rough cluster validity measures, and applications of rough clustering to such diverse areas as forestry, medicine, medical imaging, web mining, super markets, and traffic engineering. © 2011 John Wiley & Sons, Inc.WIREs Data Mining Knowl Discov2011 1 64‐72 DOI: 10.1002/widm.16

This article is categorized under:

Technologies > Computational Intelligence

Technologies > Machine Learning

Technologies > Structure Discovery and Clustering
Severe ethanol stress induces assembly of stress granules in Saccharomyces cerevisiae
Authors: Kato Kenta , Yamamoto Yosuke , Izawa Shingo
Published: January 2011

Stress granules (SGs) and processing bodies (P bodies) are cytoplasmic domains and play a role in the control of translation and mRNA turnover in mammalian cells subjected to environmental stress. Recent studies have revealed that SGs also form in the budding yeast Saccharomyces cerevisiae in response to glucose depletion and robust heat shock. However, information about the types of stress that cause budding yeast SGs is quite limited. Here we demonstrate that severe ethanol stress generates budding yeast SGs in a manner independent of the phosphorylation of eIF2α. The concentration that generated budding yeast SGs (>10%) was higher than that causing P bodies (>6%), and P bodies were assembled prior to SGs. As well as mammalian SGs, the assembly of budding yeast SGs under ethanol stress was blocked by cycloheximide. On the other hand, the budding yeast SGs caused by ethanol stress contained eIF3c but not eIF3a and eIF3b, although the eIF3 complex is a core constituent of mammalian SGs. Moreover, null mutants (pbp1Δ, pub1Δ and tif4632Δ) with a strong reduction in SG formation did not resume proliferation after the elimination of ethanol stress, indicating that the formation of budding yeast SGs might play a role in sufficient recovery from ethanol stress. Copyright © 2011 John Wiley & Sons, Ltd.
Comprehensive phenotypic analysis of single‐gene deletion and overexpression strains of Saccharomyces cerevisiae
Authors: Yoshikawa Katsunori , Tanaka Tadamasa , Ida Yoshihiro , Furusawa Chikara , Hirasawa Takashi , Shimizu Hiroshi
Published: January 2011

We quantified the growth behaviour of all available single‐gene deletion and overexpression strains of budding yeast. Genome‐wide analyses enabled the extraction of the genes and identification of the functional categories for which genetic perturbation caused the change of growth behaviour. Statistical analyses revealed defective growth for 646 deletion and 1302 overexpression strains. We classified these deleted and overexpressed genes into known functional categories, and identified several functional categories having fragility and robustness for cellular growth. We also screened the deletion and overexpression strains that exhibited a significantly higher growth rate than the strain without genetic perturbation, and found that three deletion and two overexpression strains were high‐growth strains. The genes and functional categories identified in the analysis might provide useful information on designing industrially useful yeast strains. Copyright © 2011 John Wiley & Sons, Ltd.
Low ergosterol content in yeast adh1 mutant enhances chitin maldistribution and sensitivity to paraquat‐induced oxidative stress
Authors: Marisco G. , Saito S. T. , Ganda I. S. , Brendel M. , Pungartnik C.
Published: January 2011

Alcohol dehydrogenases catalyse the reversible oxidation of alcohols to aldehydes or ketones, with concomitant reduction of NAD+ or NADP+. Adh1p is responsible for the reduction of acetaldehyde to ethanol, while Adh2p catalyses the reverse reaction, the oxidation of ethanol to acetaldehyde. Lack of Adh1p shifts the cellular redox balance towards excess NADH/NADPH and acetaldehyde, while absence of Adh2p does the opposite. Yeast mutant adh1Δ had a slow growth rate, whereas adh2Δ grew like the isogenic wild‐type (WT) during prediauxic shift fermentative metabolism. After 48 h WT and mutants reached the same number of viable cells. When exponentially growing (LOG) cells were exposed to calcofluor white, only mutant adh1Δ displayed an irregular deposition of chitin. Quantitative analyses of both LOG and stationary‐phase cells showed that adh1Δ mutant contained significantly less ergosterol than cells of WT and adh2Δ mutant, whereas the erg3Δ mutant contained extremely low ergosterol pools. Both adh1Δ and adh2Δ mutants showed higher‐than‐WT resistance to heat shock and to H2O2 but had WT resistance when exposed to ultraviolet (UV) light and the DNA cross‐linking agent diepoxyoctane, indicating normal DNA repair capacity. Mutant adh1Δ was specifically sensitive to acetaldehyde and to membrane peroxidizing paraquat. Our results link the pleiotropic phenotype of adh1Δ mutants to low pools of ergosterol and to reductive stress, and introduce the two new phenotypes, resistance to heat shock and to H2O2, for the adh2Δ mutant, most probably related to increased ROS production in mitochondria, which leads to the induction of oxidative stress protection. Copyright © 2011 John Wiley & Sons, Ltd.
The First Cationic Complex of Tetravalent Cerium
Authors: Dröse Peter , Gottfriedsen Jochen , Hrib Cristian G. , Jones Peter G. , Hilfert Liane , Edelmann Frank T.
Published: January 2011

The recently reported cerium(IV) tripodal Schiff‐base complex (TRENDSAL)CeCl (TRENDSAL = [N{CH2CH2N=CH(C6H2tBu2‐3,5‐O‐2}3]3–) serves as excellent starting material for novel Ce4+ coordination compounds. The first cerium(IV) azide, (TRENDSAL)CeN3 and the first cationic cerium(IV) complex, [(TRENDSAL)Ce][BPh4] are both readily accessible from (TRENDSAL)CeCl via simple salt metathesis reaction.
Pressure at the Bowel Surface during Topical Negative Pressure Therapy of the Open Abdomen: An Experimental Study in a Porcine Model
Authors: Bjarnason Thordur , Montgomery Agneta , Hlebowicz Joanna , Lindstedt Sandra , Petersson Ulf
Published: January 2011

Background

Topical negative pressure (TNP) therapy is increasingly used in open abdomen management. It is not known to what extent this pressure propagates through the dressing to the bowel surface, potentially increasing the risk of bowel fistula formation. The present study in a porcine model was designed to evaluate pressure propagation.

Methods

A commercially available TNP therapy system (ABThera/VAC) was applied in six pigs after laparotomy. Pressure sensors were placed in predetermined positions in the dressing and in the abdominal cavity and the pressure was registered at TNP settings of −50, −75, −100, −125, and −150 mmHg. Next, after infusing 200 ml of saline into the abdomen through a catheter, the amount of fluid drained through the system during 10 min of TNP therapy was registered. Finally, pressure was measured above and below eight layers of paraffin gauzes during TNP therapy.

Results

Observed pressure within the outer two foams and the foam of the visceral protective layer correlated with preset TNP. The median pressure at the bowel surface was between −2 and −10 mmHg, regardless of preset TNP. Median fluid drainage was 95% of the infused fluid at −75 mmHg and 124% at −150 mmHg. Paraffin gauzes had a limited isolating effect, reducing the pressure by 13% in median.

Conclusions

Negative pressure reaching the bowel surface during TNP therapy with the ABThera system is limited for all TNP levels. Reduced therapy pressure does not lead to reduced pressure at the bowel surface. The system drains the abdominal cavity completely of fluid. Paraffin gauzes are of limited value as a means of pressure isolation.