bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous trace gas measurements using two Fourier transform spectrometers at Eureka, Canada during spring 2006, and comparisons with the ACE-FTS
Authors: Fu D. , Walker K. A. , Mittermeier R. L. , Strong K. , Sung K. , Fast H. , Bernath P. F. , Boone C. D. , Daffer W. H. , Fogal P. , Kolonjari F. , Loewen P. , Manney G. L. , Mikhailov O. , Drummond J. R.
Published: June 2011

Abstract. The 2006 Canadian Arctic ACE (Atmospheric Chemistry Experiment) Validation Campaign collected measurements at the Polar Environment Atmospheric Research Laboratory (PEARL, 86.42° W, 80.05° N, 610 m a.s.l.) at Eureka, Canada from 17 February to 31 March 2006. Two of the ten instruments involved in the campaign, both Fourier transform spectrometers (FTSs), were operated simultaneously, recording atmospheric solar absorption spectra. The first instrument was an ABB Bomem DA8 high-resolution infrared FTS. The second instrument was the Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the ground-based version of the satellite-borne FTS on the ACE satellite (ACE-FTS). From the measurements collected by these two ground-based instruments, total column densities of seven stratospheric trace gases (O3, HCl, ClONO2, HF, HNO3, NO2, and NO) were retrieved using the optimal estimation method and these results were compared. Since the two instruments sampled the same portions of atmosphere by synchronizing observations during the campaign and used consistent retrieval parameters, the biases in retrieved columns from the two spectrometers represent the instrumental differences. Mean differences in total column densities of O3, HCl, ClONO2, HF, HNO3, and NO2 from the observations between PARIS-IR and the DA8 FTS are 2.8 %, −3.2 %, −4.3 %, −1.5 %, −1.9 %, and −0.1 %, respectively. Partial column results from the ground-based spectrometers were also compared with partial columns derived from ACE-FTS version 2.2 (including updates for O3) profiles. Mean differences in partial column densities of O3, HCl, ClONO2, HF, HNO3, NO2, and NO from the measurements between ACE-FTS and the DA8 FTS are −5.9 %, −8.5 %, −11.8 %, −0.9 %, −6.6 %, −21.6 % and −7.6 % respectively. Mean differences in partial column densities of O3, HCl, ClONO2, HF, HNO3, NO2 from the measurements between ACE-FTS and the PARIS-IR are −5.2 %, −4.6 %, −2.3 %, −4.7 %, 5.7 % and −11.9 %, respectively. This work provides further evidence of the reliability of ACE-FTS measurements from the first three years of on-orbit observations. Column densities of O3, HCl, ClONO2, and HNO3 from the three FTSs were normalized with respect to HF and used to compare the time evolution of the chemical constituents in the atmosphere over Eureka during spring 2006.
Theoretical basis for convective invigoration due to increased aerosol concentration
Authors: Lebo Z. J. , Seinfeld J. H.
Published: June 2011

Abstract. The potential effects of increased aerosol loading on the development of deep convective clouds and resulting precipitation amounts are studied by employing the Weather Research and Forecasting (WRF) model as a detailed high-resolution cloud resolving model (CRM) with both detailed bulk and bin microphysics schemes. Both models include a physically-based activation scheme that incorporates a size-resolved aerosol population. We demonstrate that the aerosol-induced effect is controlled by the balance between latent heating and the increase in condensed water aloft, each having opposing effects on buoyancy. It is also shown that under polluted conditions, increases in the CCN number concentration reduce the cumulative precipitation due to the competition between the sedimentation and evaporation/sublimation timescales. The effect of an increase in the IN number concentration on the dynamics of deep convective clouds is small and the resulting decrease in domain-averaged cumulative precipitation is shown not to be statistically significant, but may act to suppress precipitation. It is also shown that even in the presence of a decrease in the domain-averaged cumulative precipitation, an increase in the precipitation variance, or in other words, andincrease in rainfall intensity, may be expected in more polluted environments, especially in moist environments. A significant difference exists between the predictions based on the bin and bulk microphysics schemes of precipitation and the influence of aerosol perturbations on updraft velocity within the convective core. The bulk microphysics scheme shows little change in the latent heating rates due to an increase in the CCN number concentration, while the bin microphysics scheme demonstrates significant increases in the latent heating aloft with increasing CCN number concentration. This suggests that even a detailed two-bulk microphysics scheme, coupled to a detailed activation scheme, may not be sufficient to predict small changes that result from perturbations in aerosol loading.
Eight-component retrievals from ground-based MAX-DOAS observations
Authors: Irie H. , Takashima H. , Kanaya Y. , Boersma K. F. , Gast L. , Wittrock F. , Brunner D. , Zhou Y. , Van Roozendael M.
Published: June 2011

Abstract. We attempt for the first time to retrieve lower-tropospheric vertical profile information for 8 quantities from ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations. The components retrieved are the aerosol extinction coefficients at two wavelengths, 357 and 476 nm, and NO2, HCHO, CHOCHO, H2O, SO2, and O3 volume mixing ratios. A Japanese MAX-DOAS profile retrieval algorithm, version 1 (JM1), is applied to observations performed at Cabauw, the Netherlands (51.97° N, 4.93° E), in June–July 2009 during the Cabauw Intercomparison campaign of Nitrogen Dioxide measuring Instruments (CINDI). Of the retrieved profiles, we focus here on the lowest-layer data (mean values at altitudes 0–1 km), where the sensitivity is usually highest owing to the longest light path. In support of the capability of the multi-component retrievals, we find reasonable overall agreement with independent data sets, including a regional chemical transport model (CHIMERE) and in situ observations performed near the surface (2–3 m) and at the 200-m height level of the tall tower in Cabauw. Plumes of enhanced HCHO and SO2 were likely affected by biogenic and ship emissions, respectively, and an improvement in their emission strengths is suggested for better agreement between CHIMERE simulations and MAX-DOAS observations. Analysis of air mass factors indicates that the horizontal spatial representativeness of MAX-DOAS observations is about 3–15 km (depending mainly on aerosol extinction), comparable to or better than the spatial resolution of current UV-visible satellite observations and model calculations. These demonstrate that MAX-DOAS provides multi-component data useful for the evaluation of satellite observations and model calculations and can play an important role in bridging different data sets having different spatial resolutions.
Deciphering the spatio-temporal complexity of climate change of the last deglaciation: a model analysis
Authors: Roche D. M. , Renssen H. , Paillard D. , Levavasseur G.
Published: June 2011

Abstract. Understanding the sequence of events occuring during the last major glacial to interglacial transition (21 ka BP to 9 ka BP) is a challenging task that has the potential to unveil the mechanisms behind large scale climate changes. Though many studies have focused on the understanding of the complex sequence of rapid climatic change that accompanied or interrupted the deglaciation, few have analysed it in a more theoretical framework with simple forcings. In the following, we address when and where the first significant temperature anomalies appeared when using slow varying forcing of the last deglaciation. We used here coupled transient simulations of the last deglaciation, including ocean, atmosphere and vegetation components to analyse the spatial timing of the deglaciation. To keep the analysis in a simple framework, we did not include freshwater forcings that potentially cause rapid climate shifts during that time period. We aimed to disentangle the direct and subsequent response of the climate system to slow forcing and moreover, the location where those changes are more clearly expressed. In a data – modelling comparison perspective, this could help understand the physically plausible phasing between known forcings and recorded climatic changes. Our analysis of climate variability could also help to distinguish deglacial warming signals from internal climate variability. We thus are able to better pinpoint the onset of local deglaciation, as defined by the first significant local warming and further show that there is a large regional variability associated with it, even with the set of slow forcings used here. In our model, the first significant hemispheric warming occurred simultaneously in the North and in the South and is a direct response to the obliquity forcing.
Reconstruction of southeast Tibetan Plateau summer cloud cover over the past two centuries using tree ring δ18O
Authors: Shi C. , Daux V. , Risi C. , Hou S.-G. , Stievenard M. , Pierre M. , Li Z. , Masson-Delmotte V.
Published: June 2011

Abstract. A tree-ring δ18O chronology of Linzhi spruce, spanning from AD 1781 to 2005, was developed in Bomi, Southeast Tibetan Plateau (TP). During the period with instrumental data (1961–2005), this record is strongly correlated with regional summer cloud cover, which is supported by a precipitation δ18O simulation conducted with the isotope-enabled atmospheric general circulation model LMDZiso. A 225-yr regional cloud cover reconstruction was therefore achieved. The observed cloud cover increased in the 1980s and this increase is not unprecedented in the entire reconstruction. The reconstructed cloud cover appears smaller and more stable in the 20th century than previously. A late 19th century decrease in our reconstructed cloud cover is consistent with a decrease in the TP glacier accumulation recorded in ice cores. Our data reveal a strong anomaly in the 1810s, which coincides with volcanic eruption in 1809 and the 1815 Tambora volcanic eruption.
Grasp planning for a reconfigurable parallel robot with an underactuated arm structure
Authors: Riedel M. , Nefzi M. , Corves B.
Published: June 2011

Abstract. In this paper, a novel approach of grasp planning is applied to find out the appropriate grasp points for a reconfigurable parallel robot called PARAGRIP (Parallel Gripping). This new handling system is able to manipulate objects in the six-dimensional Cartesian space by several robotic arms using only six actuated joints. After grasping, the contact elements at the end of the underactuated arm mechanisms are connected to the object which forms a closed loop mechanism similar to the architecture of parallel manipulators. As the mounting and grasp points of the arms can easily be changed, the manipulator can be reconfigured to match the user's preferences and needs. This paper raises the question, how and where these grasp points are to be placed on the object to perform well for a certain manipulation task. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.
The kinematic preshaping of triggered self-adaptive linkage-driven robotic fingers
Authors: Birglen L.
Published: June 2011

Abstract. In this paper, the issue of the kinematic – as opposed to dynamic – preshaping of self-adaptive robotic fingers driven by linkages is discussed. A method to obtain designs of these fingers capable of various behaviours during their closing motions is presented. The method is based on using triggered passive elements in carefully selected joints of the finger and the selection or optimization of geometric parameters to obtain particular kinematic relationships between the motions of the phalanges. This method is very general and can be applied to any self-adaptive robotic finger in order to obtain many different types of closing motions. Examples given in this paper are focusing on two different preshaping motions, the first one aims at allowing pinch grasps while the second mimics a human finger. The fundamental aim of this paper is to show that various preshapings of self-adaptive fingers are possible, not just one, and to give two step-by-step examples. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.
Continuum robots and underactuated grasping
Authors: Giri N. , Walker I.
Published: June 2011

Abstract. We discuss the capabilities of continuum (continuous backbone) robot structures in the performance of under-actuated grasping. Continuum robots offer the potential of robust grasps over a wide variety of object classes, due to their ability to adapt their shape to interact with the environment via non-local continuum contact conditions. Furthermore, this capability can be achieved with simple, low degree of freedom hardware. However, there are practical issues which currently limit the application of continuum robots to grasping. We discuss these issues and illustrate via an experimental continuum grasping case study. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.
Design and performance assessment of an underactuated hand for industrial applications
Authors: Meijneke C. , Kragten G. A. , Wisse M.
Published: June 2011

Abstract. The Delft Hand 2 (DH-2) is an underactuated robot hand meant for industrial applications, having six degrees of freedom (DoF), one actuator (DoA) and no sensors. It was designed to provide a cheap and robust hand to grasp a large range of objects without damaging them. The goal of this paper is to assess the design and performance of the DH-2, demonstrating how the design was optimized for its intended application area and how the hand was simplified to make it commercially attractive. Performance tests show that the DH-2 has a payload of 2 kg for an object range of 60 to 120 mm, it can close or open within 0.5 s, and it only uses open-loop control by means of the input voltage of the motor. The results demonstrate that the industrial need of a simple, cheap and effective robotic hand can be achieved with the principle of underactuation and the use of conventional components. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.
A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes
Authors: D'Ajello Caracciolo F. , Pignatelli A. , Speranza F. , Meloni A.
Published: June 2011

Abstract. Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleo)secular variation ((P)SV) are available. To this end, we re-evaluate the whole Italian geomagnetic directional dataset, consisting of 833 and 696 declination and inclination measurements, respectively, carried out since 1640 AD at several localities. All directions were relocated via the virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E), the rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method) by French data (for period 1670–1789), and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962). Using post-1825 declination values, we obtain a 0.46 ± 0.19° yr−1 westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000) and Pavon-Carrasco et al. (2009). However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yield the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by Jackson et al. (2000) yields more accurate inclination values, while the declinations from our drift-corrected curve seem to better represent the local field evolution, at least for the first half of the century.
Effect of Charge Recombination on the Fill Factor of Small Molecule Bulk Heterojunction Solar Cells
Authors: Zhang Yuan , Dang Xuan‐Dung , Kim Chunki , Nguyen Thuc‐Quyen
Published: June 2011

Solution‐processed organic BHJ solar cells based on 3,6‐bis[5‐(benzofuran‐2‐yl)thiophen‐2‐yl]‐2,5‐bis(2‐ethylhexyl)pyrrolo[3,4‐c]pyrrole‐1,4‐dione (DPP(TBFu)2) or poly(3‐hexylthiophene) blended with [6,6]‐phenyl‐C60(70) ‐butyric acid methyl ester (PC60(70) BM) behave differently under various irradiation intensities. Small molecule‐based DPP(TBFu)2:PC60 BM solar cells show up to 5.2% power conversion efficiency and a high fill factor at low light intensity. At 100 mW cm−2 illumination, the efficiency and fill factor decrease, resulting in stronger power losses. Impedance spectroscopy at various light intensities reveals that high charge recombination is the cause of the low fill factor in DPP(TBFu)2:PC60 BM.
Design Principles of FRET‐Based Dye‐Sensitized Solar Cells with Buried Quantum Dot Donors
Authors: Itzhakov Stella , Buhbut Sophia , Tauber Elad , Geiger Thomas , Zaban Arie , Oron Dan
Published: June 2011

In this article, the physics of FRET is demonstrated for an architecture of dye‐sensitized solar cells, in which the quantum dot “antennas” that serve as donors are incorporated into the solid titania electrode, providing isolation from electrolyte quenching, and potentially increased photostability. The energy transferred to the dye acceptor from the quantum dot donor, in addition to the direct light absorption by the dye, finally induce dye excitation and electron injection to the metal oxide semiconductor electrode. We use time‐resolved photoluminescence measurements to directly show achievement of FRET efficiencies of up to 70%, corresponding to over 80% internal quantum efficiency when considering radiative energy transfer as well. The various parameters governing the FRET efficiency and the requirements for high efficiency FRET‐based cells are discussed. Since both buried donors inside the electrode and donors solubilized in the electrolyte have both been shown to achieve high energy transfer efficiencies, and as the two methods take advantage of different available volumes of the electrode to introduce donors providing the excess absorption, synergy of the two methods is highly promising for achieving panchromatic absorption within a thin electrode.
A Theoretical Study of Hydrogen Transfer Catalyzed by an IrIII PC(sp3)P Pincer Complex
Authors: Kozuch Sebastian , Azerraf Clarite
Published: June 2011

A hydrogen transfer mechanism catalyzed by an IrIII PC(sp3)P pincer complex was studied by using DFT, and its efficiency was estimated by using the energetic span model. With the pristine complex, a hydrogen abstraction pathway could not be found, since a ligand dissociation to generate a vacant site is energetically costly. However, a nucleophilic attack of an alkoxide base (present in the reaction mixture) on the carbonyl ligand to form a carboalkoxy ligand generated an anionic catalyst that could easily provide the free site. From there, a hydride abstraction from an isopropyl ion (iPrO−) followed by a hydride transfer to acetophenone resulted in an efficient catalytic cycle.
Intermittent Drying: Energy Expenditure and Product Quality
Authors: Kowalski S. J. , Pawlowski A.
Published: June 2011

Several issues pertinent to intermittent drying of clay‐like materials were analyzed with respect to energy consumption, quality of dried products, and drying time. Experimental tests were performed on the cylindrically‐shaped kaolin samples for batch convective drying realized with both periodically alternated temperature and humidity of the drying air. To assess the benefits from intermittent drying, a series of tests were carried out at both parameters kept constant. The net energy necessary for material heating and moisture evaporation was numerically calculated based on the authors' model of drying kinetics, and related to the experimentally measured total electric energy consumption to evaluate the effectiveness of intermittent drying. The quality of dried samples was quantified in terms of crack intensity and magnitude. It was found that intermittent drying permits much better product quality with comparable drying time and energy consumption when drying occurs under constant conditions.
Manny's legacy: paying forward my personal therapy
Authors: Freeman Arthur
Published: June 2011

The lessons of childhood will often last a lifetime. Two lessons that I learned early in life were that loss can occur quickly, unexpectedly, and have monumental consequences such as when my father died when I was 9 years old. I also learned that losses can be assuaged or mitigated in many ways, not the least of which would be the replacement of my father with a father figure, who filled the needs of an adolescent and later an adult with a role model, keen insights, and emotional support. This article traces my experiences with personal therapy and addresses how lessons learned can be used and passed on to succeeding generations comprised of one's children and, in my case, my patients and students for the past 45 years. © 2011 Wiley Periodicals, Inc. J Clin Psychol: In Session 67:1–5, 2011.
Comparative analysis of two types of methanol dehydrogenase from Methylophaga aminisulfidivorans MPT grown on methanol
Authors: Kim Hee Gon , Han Gui Hwan , Kim Dockyu , Choi Jong‐Soon , Kim Si Wouk
Published: June 2011

Two types of methanol dehydrogenase (MDH) were obtained from a novel marine methylotrophic bacterium, Methylophaga aminisulfidivorans MPT, grown on methanol. Type I MDH consisted of two identical dimers of α (65.98 kDa) and β (7.58 kDa) subunits organized to form the α2β2tetramer. Type II MDH contained an additional MxaJ protein (27.86 kDa) and had more specific activity than type I MDH. The Km values of type I and II MDH for methanol under cytochrome cL reduction assay system were estimated to be 50.3 and 13.0 μM, respectively, and the isoelectric points of type I and II MDH were determined to be 5.4 and 5.8, respectively. The average molar ratios of α:β, α:MxaJ, and β:MxaJ in type II MDH were approximately 1:0.99, 1:0.41 and 1:0.42, respectively. Based on these results, the original conformation of the MDH of M. aminisulfidivorans MPTis most likely the α2β2‐MxaJ complex. During purification, the lysozyme and freeze‐thawing cell disruption method significantly increased the amount of type II MDH in the soluble fraction compared with strong physical disruption methods such as sonication and French Press. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prokaryotic diversity of an active mud volcano in the Usu City of Xinjiang, China
Authors: Yang Hong‐Mei , Lou Kai , Sun Jian , Zhang Tao , Ma Xiao‐Long
Published: June 2011

The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi‐arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluating management risks using landscape trajectory analysis: A case study of California fisher
Authors: Thompson Craig M. , Zielinski William J. , Purcell Kathryn L.
Published: June 2011

Ecosystem management requires an understanding of how landscapes vary in space and time, how this variation can be affected by management decisions or stochastic events, and the potential consequences for species. Landscape trajectory analysis, coupled with a basic knowledge of species habitat selection, offers a straightforward approach to ecological risk analysis and can be used to project the effects of management decisions on species of concern. The fisher (Martes pennanti) occurs primarily in late‐successional forests which, in the Sierra Nevada mountains, are susceptible to high‐intensity wildfire. Understanding the effects of fuels treatments and fire on the distribution of fisher habitat is a critical conservation concern. We assumed that the more a treated landscape resembled occupied female fisher home ranges, the more likely it was to be occupied by a female and therefore the lower the risk to the population. Thus, we characterized important vegetation attributes within the home ranges of 16 female fishers and used the distribution of these attributes as a baseline against which the effects of forest management options could be compared. We used principal components analysis to identify the major axes defining occupied female fisher home ranges and these, in addition to select univariate metrics, became our reference for evaluating the effects of landscape change. We demonstrated the approach at two management units on the Sierra National Forest by simulating the effects of both no action and forest thinning, with and without an unplanned fire, on vegetation characteristics over a 45‐yr period. Under the no action scenario, landscapes remained similar to reference conditions for approximately 30‐yr until forest succession resulted in a loss of landscape heterogeneity. Comparatively, fuel treatment resulted in the reduction of certain forest elements below those found in female fisher home ranges yet little overall change in habitat suitability. Adding a wildfire to both scenarios resulted in divergence from reference conditions, though in the no action scenario the divergence was 4× greater and the landscape did not recover within the 45‐yr timeframe. These examples demonstrate that combining the results of forest growth and disturbance modeling with habitat selection data may be used to quantify the potential effects of vegetation management activities on wildlife habitat. © 2011 The Wildlife Society.
Long‐term outcome after intrauterine laser treatment for twin–twin transfusion syndrome
Authors: Maschke Cornelia , Diemert Anke , Hecher Kurt , Bartmann Peter
Published: June 2011

Twin–twin transfusion syndrome (TTTS) is a severe complication occurring in about 10% of monochorionic twin pregnancies. The chronic unbalanced transfusion of blood across placental vascular communications from the donor to the recipient twin may lead to impairment of various organ systems in the affected twins. In Hamburg, Germany, since 1995 patients with TTTS were treated with fetoscopic laser coagulation as the first causal therapeutic strategy. All survivors after laser surgery were followed up in the University Children's Hospital in Bonn, Germany. In this article, we summarize long‐term follow‐up studies from our German study population and compare our results with data from the literature. Copyright © 2011 John Wiley & Sons, Ltd.
Achieving high‐growth‐rate in GaN homoepitaxy using high‐density nitrogen radical source
Authors: Kawai Yohjiro , Chen Shang , Honda Yoshio , Yamaguchi Masahito , Amano Hiroshi , Kondo Hiroki , Hiramatsu Mineo , Kano Hiroyuki , Yamakawa Koji , Den Shoji , Hori Masaru
Published: June 2011

The key issue in GaN growth by radio‐frequency plasma‐assisted molecular beam epitaxy is the low growth rate compared with that obtained using an ammonia source. To reduce the processing time and to improve the crystalline quality of the epilayer, a high‐density radical source (HDRS) with high stability has been developed. The growth rate of the GaN epilayer was improved using the HDRS rather than a conventional radical source. During the growth, a sharp streak pattern obtained by reflection high‐energy electron diffraction was maintained. An atomically smooth surface was confirmed by atomic force microscopy observation (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reliability study on micro‐structured InGaN light‐emitting diodes
Authors: Li Z. L. , Li K. H. , Choi H. W.
Published: June 2011

Micro‐structured InGaN light‐emitting diodes (µLED) are capable of delivering enhanced light output due to additional light extraction through exposed sidewalls. However, these sidewalls formed by plasma etching can potentially affect the lifetime and reliability of the devices as a result of plama damage. A study on the electrical characteristics and reliability of µLED arrays has been carried out in this work. Although improved optical performance can be expected based on previous studies, expanded device sidewalls prove to accelerate the rate of optical degradation, adversely affect the lifetimes of devices. Through precise current‐voltage measurement vertical current conduction along the plasma‐damaged sidewalls was identified as the key mechanism contributing to degraded reliability. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct study of nonlinear carrier recombination in InGaN quantum well structures
Authors: Malinauskas Tadas , Miasojedovas Saulius , Aleksiejūnas Ramūnas , Juršėnas Saulius , Jarašiūnas Kęstutis , Nomura Masahiro , Arakawa Yasuhiko , Shimura Tsutomu , Kuroda Kazuo
Published: June 2011

Direct measurements of carrier recombination dynamics in In0.1Ga0.9N/In0.03Ga0.97N multiple quantum well (QW) structures with different well thickness (d = 5.5, 17, 34 nm) are presented. The measurements by light‐induced picosecond transient grating and time‐resolved photoluminescence techniques revealed three contributing carrier recombination mechanisms at high carrier injections (“efficiency droop” conditions): stimulated emission (SE), bimolecular, and Shockley‐Read‐Hall. The study indicates on absence of Auger recombination rate with quadratic dependence, 1/τ ∝ N2, which was not observed up to ∼5x1019 cm‐3 excess carrier density (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Injection efficiency in AlGaN‐based UV laser diodes
Authors: Nagata Kengo , Takeda Kenichiro , Oshimura Yoshinori , Takehara Kosuke , Aoshima Hiroki , Ito Shun , Iwaya Motoaki , Takeuchi Tetsuya , Kamiyama Satoshi , Akasaki Isamu , Amano Hiroshi , Yoshida Harumasa , Kuwabara Masakazu , Yamashita Yoji , Kan Hirofumi
Published: June 2011

We evaluated AlGaN‐based 355 nm UV laser diodes prepared under two different Mg activation conditions. The annealing processes for Mg activation in p‐layers were carried out under N2 or O2 ambient to investigate the effect of the ambient gas on the laser characteristics. The threshold current densities and operating voltages of the UV laser diodes were improved by annealing under O2 compared with those under N2. We then estimated the injection efficiencies of the laser diode structures by considering the internal quantum efficiencies of optical excitation and electrical excitation. The internal quantum efficiency of the electrically excited spontaneous emission from the laser structure annealed under O2 reached 50% at a carrier density of 7.0×1018 cm‐3, while the structure annealed under N2 required a 1.8‐fold higher carrier density of 1.2×1019 cm‐3 to reach the same internal quantum efficiency. In addition, the internal quantum efficiency estimated from optical excitation reached 50% even at a carrier density of 3.0×1018 cm‐3. This implies that the injection efficiencies in the UV laser diode structures annealed under N2 and O2 were 25% and 45%, respectively. Mg activation by O2 annealing is effective for increasing the injection efficiency. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaNAs alloys over the whole composition range grown on crystalline and amorphous substrates
Authors: Yu K. M. , Novikov S. V. , Broesler R. , Levander A. X. , Liliental‐Weber Z. , Luckert F. , Martin R. W. , Dubon O. , Wu J. , Walukiewicz W. , Foxon C. T.
Published: June 2011

Using low temperature molecular beam epitaxy (LT‐MBE) technique we have overcome the miscibility gap of GaAs and GaN alloys and successfully synthesized GaN1‐xAsx alloys in the whole composition range on crystalline (sapphire and silicon) and amorphous (Pyrex glass) substrates. On the N‐rich side we found an increased incorporation of As with decreasing growth temperature. At high enough As content the films lose their crystallinity and become amorphous. On sapphire substrate, the alloys are amorphous in the composition range of 0.17<x<0.75. For the films grown on glass substrates, the composition range for amorphous alloys extends to x∼0.1. However, films grown on silicon shows small fraction of As‐rich and N‐rich GaNAs nanocrystals for films with As content up to 36%. These amorphous GaNAs films have smooth morphology, homogeneous composition and sharp, well defined optical absorption edges. The bandgap energy of the GaN1‐xAsx alloys covers a broad energy range from ∼3.4 eV in GaN to∼0.8 eV at x∼0.85. This provides an almost perfect fit to the solar spectrum offering the opportunity to design high efficiency multijunction solar cells using a single ternary alloy system. The amorphous nature of this alloy over a wide alloy range can also be advantageous since they can be deposited on low‐cost glass substrate. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of behavior factor of tunnel‐form concrete building structures using Applied Technology Council 63 methodology
Authors: Tavafoghi Alireza , Eshghi Sassan
Published: June 2011

Tunnel‐form construction system is used for buildings made up of slabs and walls. This system has represented fast construction technique, low cost and time saving in the construction period. However, there are no special requirements for seismic design of this type of buildings, and some provisions of the concrete bearing wall system are used. None of the seismic codes addresses the R factor for tunnel‐form buildings directly, and some doubts remained about prediction of the fundamental period. Meanwhile the force‐based methods, which depended on R factor and fundamental period, are still used for seismic design of this type of buildings. There is a need for evaluating the R factor for tunnel‐form buildings. The methodology was developed by the Applied Technology Council (ATC) entitled ATC‐63 Project for quantifying building system performance and response parameters for use in seismic design. Here, this methodology is used to estimate more reliable R factor for tunnel‐form buildings. An experimental program was carried out to decrease the uncertainty of finite element modeling and using it as a part of the methodology. A database was created, and some analyses were performed. The results of analysis were summarized to propose more accurate R factor for tunnel‐form buildings. Copyright © 2011 John Wiley & Sons, Ltd.
An analysis of mutualistic interactions between exotic ants and honeydew producers in the Yanbaru district of Okinawa Island, Japan
Authors: Tanaka Hirotaka , Ohnishi Hitoshi , Tatsuta Haruki , Tsuji Kazuki
Published: June 2011

Invasive exotic ants often have a mutualistic relationship with other insects excreting honeydew, and this is considered to play a key role in their invasion success. We investigated the multispecies association patterns between ants and hemipteran insects in the Yanbaru forests, Okinawa, Japan, an Asian biodiversity hotspot. We especially focused on roadside environments, which are the frontlines of invasion for exotic ants. We found that only a small number of herbaceous and pioneer plants were predominant on the roadsides. Four honeydew producers, Melanaphis formosana, Dysmicoccus sp. A, Heteropsylla cubana, and Sogata hakonensis, living on these roadside plants accounted for 94.9% of the total honeydew‐producer aggregations observed. Only a few exotic ants, such as Technomyrmex brunneus and Anoplolepis gracilipes, were observed with these honeydew‐producer aggregations, and densities of these ants and honeydew producers were often positively correlated. An ant exclusion experiment showed that exotic ant occurrence improved the survival of some of the hemipteran colonies. Interestingly, the abundance of native ants was not correlated with the abundance of honeydew producers, and the local density of Pheidole noda was negatively correlated with that of M. formosana. These findings, i.e., only a few ants, all exotic, tended to hemipteran honeydew producers despite the existence of many native ants, and the abundances of those exotic ants and those hemipteran insects had positive correlations, provide some insights into the mechanism of biological invasion and provide information for the management of exotic ants.
Bullshit, Social Integration, and Political Legitimation: Habermasian Reflections
Authors: Borman David A.
Published: June 2011

ABSTRACT: This paper proposes a Habermasian analysis of bullshit which diverges from the well-known account offered by Harry Frankfurt. It aims to show that Habermas’s theory of communicative action provides superior conceptual tools for such an analysis, but also that the phenomenon of bullshit ought to be deeply troubling to Habermasians. Bullshit frustrates the transition to discourse, interrupts the binding force of communicative action (the basis of Habermas’s account of social integration) and, if sufficiently widespread as to alter fundamental attitudes toward public speech, bullshit challenges the status of Habermas’s theory of communicative action as a reconstruction of the intuitive knowledge of competent speakers, which status is intended to justify its claim to provide the normative foundations for a critical theory of society in the Frankfurt School sense of an immanent critique.
Do molecules matter more than morphology? Promises and pitfalls in parasites
Authors: PERKINS S. L. , MARTINSEN E. S. , FALK B. G.
Published: June 2011

Systematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences – morphological and molecular data – as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.
Gay and lesbian carers: ageing in the shadow of dementia
Authors: PRICE ELIZABETH
Published: June 2011

This article reports on findings from a qualitative study, undertaken in England, which explored the experiences of 21 gay men and lesbian women who care, or cared, for a person with dementia. The aim of the study was to explore this experience through the lens of a person's gay or lesbian sexuality. The paper reports two related themes that emerged from the wider study – respondents' hopes, fears and plans for the future and, specifically, the way in which their caring experiences had coloured their views and expectations of how their own health and social care needs may be met. Respondents' narratives reflect a range of pervasive anxieties about the future. First, about the possibility that they might be diagnosed with a condition such as dementia and, consequently, the myriad ways in which their sexualities and lifestyle choices may be perceived and interpreted as they themselves age and, possibly, require health and/or social care and support. In light of these concerns, respondents reflected upon the need for specialist service provision for older gay and lesbian people – an idea that was, perhaps surprisingly, not universally welcomed.
China's export restriction policies: complying with ‘WTO plus’ or undermining multilateralism
Authors: KARAPINAR BARIS
Published: June 2011

Export restrictions imposed on various food products and natural resources have been subject to extensive public attention. Most recently, China's restrictions of its exports of certain minerals and rare earth metals have led to heated debates. The United States (US), European Union (EU), and Mexico have already filed a WTO dispute case against China on this matter. This paper describes the policy objectives and the global welfare implications of export restrictions. It summarizes the relevant WTO regulation, and offers a detailed analysis of the China–Raw Materials case which is before the Dispute Settlement Body (DSB). It argues that although export restrictions is arguably an area of ‘under-regulation’ or ‘regulatory deficiency’ in the WTO law, it is strongly biased against the late accession Members, including China. Yet, the way that China institutes its export restrictions raises serious questions about its role in the multilateral trading system, which it relies on for its economic prosperity. Hence, this is an area where China is likely to feel the implications of its so-called ‘WTO-plus’ commitments on its domestic and trade policies.
X-ray combined analysis of fiber-textured and epitaxial Ba(Sr,Ti)O3 thin films deposited by radio frequency sputtering
Authors: Rémiens D. , Yang L. , Ponchel F. , Légier J. F. , Chateigner D. , Wang G. , Dong X.
Published: June 2011

A complete study is given in this paper on the structural properties of Ba(Sr,Ti)O3 (BST) thin films which present various preferred orientations: (111) and (001) fiber and epitaxial textures. The films are deposited in situ at 800 °C by sputtering on Si/SiO2/TiOx/Pt substrates and the orientation is controlled by monitoring the concentration of O2 in the reactive plasma or by prior deposition of a very thin TiOx buffer layer between BST films and substrates. The epitaxial films are obtained on (001)-alpha-Al2O3 substrates covered with TiOx buffer layers. In order to analyze finely the preferred orientations, the texture, the microstructural features, and the anisotropy-related quantities such as residual stresses in the films, the conventional Bragg−Brentano θ - 2θ x-ray diffraction diagrams is shown not to be sufficient. So, we systematically used x-ray combined analysis, a recently developed methodology which gives access to precise determination of the structure (cell parameters and space group) of the films, their orientation distributions (texture strengths and types) and mean crystallite sizes, their residual stresses. This fine structural analysis shows important modifications between the film qualities which induce differences in BST films electrical behavior, permittivity, loss tangent, and tunability.
{111} local configurations: The main source of silicon defects during solid phase epitaxial regrowth modeled by lattice kinetic Monte Carlo
Authors: Martin-Bragado Ignacio
Published: June 2011

A lattice kinetic Monte Carlo model for defect generation during solid phase epitaxial regrowth (SPER) is presented. It assumes two simple causes for defective Si formation: amorphous atoms in local {111} configurations having a probability to become defective and random nucleation and growth creating alternative crystalline seeds. Simulations are compared with experimental results for (001) and (011) Si substrates with different topologies and aligned to ⟨100⟩ and ⟨110⟩ crystalline axes, showing the model accuracy and validating its assumptions. {111} local recrystallization is the main cause for defective Si generation during SPER, by providing the seeds for defects propagated by SPER.
Development of a magnetic resonance microscope using a high Tc bulk superconducting magnet
Authors: Ogawa Kyohei , Nakamura Takashi , Terada Yasuhiko , Kose Katsumi , Haishi Tomoyuki
Published: June 2011

We have developed the first magnetic resonance (MR) microscope using a high critical-temperature superconducting bulk magnet. The bulk magnet comprises six annular bulk superconductors (60 mm outer diameter, 28 mm inner diameter, 20 mm high) made of c-axis oriented single-domain EuBa2Cu3Oy crystals. The magnet was energized using a superconducting NMR magnet operating at 4.7 T. The inhomogeneity of the trapped magnetic field measured with MR imaging was 3.1 ppm (rms) in the ϕ6.2 mm×9.1 mm cylindrical region. Three-dimensional MR images of a chemically fixed mouse embryo acquired with voxels of (50 μm)3 demonstrated the potential of our system.
Diffraction less and strongly confined surface acoustic waves in domain inverted LiNbO3 superlattices
Authors: Yudistira Didit , Benchabane Sarah , Janner Davide , Pruneri Valerio
Published: June 2011

We show that an appropriate mass-loading, placed on the surface and in between the electrodes of a coplanar acoustic LiNbO3 superlattice, can counteract lateral diffraction of surface acoustic waves (SAWs). The strong confinement corresponds to a SAW mode, whose displacement is measured using laser interferometry. The proposed SAW confinement method has also potentials in acousto-optic devices, as we demonstrate a threefold reduction in the electrical power required for complete optical switching in mass-loaded superlattice with respect to similar unloaded structure. The devices have also the advantage not to suffer additional acoustic or optical loss due to the mass-loading structure.