bluuebunny/crossref_metadata_2025_split huggingface dataset:
Panel Conditioning in Longitudinal Studies: Evidence From Labor Force Items in the Current Population Survey
Authors: Halpern-Manners Andrew , Warren John Robert 
Published: August 2012

AbstractDoes participating in a longitudinal survey affect respondents’ answers to subsequent questions about their labor force characteristics? In this article, we investigate the magnitude of panel conditioning or time-in-survey biases for key labor force questions in the monthly Current Population Survey (CPS). Using linked CPS records for household heads first interviewed between January 2007 and June 2010, our analyses are based on strategic within-person comparisons across survey months and between-person comparisons across CPS rotation groups. We find considerable evidence for panel conditioning effects in the CPS. Panel conditioning downwardly biases the CPS-based unemployment rate, mainly by leading people to remove themselves from its denominator. Across surveys, CPS respondents (claim to) leave the labor force in greater numbers than otherwise equivalent respondents who are participating in the CPS for the first time. The results cannot be attributed to panel attrition or mode effects. We discuss implications for CPS-based research and policy as well as for survey methodology more broadly.
Micro-bubble morphologies following drop impacts onto a pool surface
Authors: Thoroddsen S. T. , Thoraval M.-J. , Takehara K. , Etoh T. G. 
Published: August 2012

AbstractWhen a drop impacts at low velocity onto a pool surface, a hemispheric air layer cushions and can delay direct contact. Herein we use ultra-high-speed video to study the rupture of this layer, to explain the resulting variety of observed distribution of bubbles. The size and distribution of micro-bubbles is determined by the number and location of the primary punctures. Isolated holes lead to the formation of bubble necklaces when the edges of two growing holes meet, whereas bubble nets are produced by regular shedding of micro-bubbles from a sawtooth edge instability. For the most viscous liquids the air film contracts more rapidly than the capillary–viscous velocity through repeated spontaneous ruptures of the edge. From the speed of hole opening and the total volume of micro-bubbles we conclude that the air sheet ruptures when its thickness approaches ${\ensuremath{\sim} }100~\mathrm{nm} $.
Modeling and robust backstepping control of an underactuated quadruped robot in bounding motion
Authors: Kazemi Hamed , Majd Vahid Johari , Moghaddam Majid M. 
Published: August 2012

SUMMARYIn this paper, a model-based exponential stabilization of a quadruped robot is studied in bounding motion. The dynamics of the five-link planar underactuated mechanical model of the quadruped robot with four actuated joints system is derived. It is shown that the dynamical equation of the proposed simplified model belongs to a class of second-order nonholonomic mechanical systems which cannot be stabilized by any smooth time-invariant state feedback. Utilizing a coordinate transformation based on the so-called normalized momentum, a robust backstepping control method is presented for the quadruped robot. Both theoretical analysis and numerical simulations show that the robust backstepping controller can stabilize the underactuated quadruped robot so that it could balance on its rear legs and track a desired trajectory. Despite the model parameter uncertainties, the robustness of the controller is maintained. The simulation results show the effectiveness of the proposed method.
Sketching across design domains: Roles and formalities
Authors: Eckert Claudia , Blackwell Alan , Stacey Martin , Earl Christopher , Church Luke 
Published: August 2012

AbstractTo complement studies on design sketching within particular phases of design processes in specific design domains, this paper analyzes descriptions of design processes given by designers from a wide variety of fields. This research forms part of a wider project on comparisons across design domains and draws attention to the many types and properties of sketches in different contexts. Further, it focuses on the multiple roles that sketching can take in idea generation, as well as in reasoning and communicating design ideas. In particular this paper examines how the different types and roles of sketches can be more or less formal and how this can lead to misunderstandings.
The influence of sketch quality on perception of product-idea creativity
Authors: Kudrowitz Barry , Te Paula , Wallace David 
Published: August 2012

AbstractThis paper explores the relationship between the quality of a sketch and how others perceive the creativity of the idea portrayed by the sketch. In this study, sketch quality is characterized through its line work, perspective, and proportions. Four different toaster ideas were each sketched by four people with different backgrounds and levels of sketching proficiency. Then, 360 reviewers ranked the toasters for idea creativity, referring to a set of four sketches: one sketch for each toaster concept. The level of sketch quality for each toaster concept was varied among one of four quality levels. Higher quality idea sketches were found to correlate with higher creativity rank (p> 0.005), and lower quality sketches correlated with a lower creativity rank (p> 0.0005). A toaster idea portrayed with the highest quality level of sketch was 2.3 times more likely to be ranked as the most creative idea within the given set of idea sketches. The results underscore the importance of how an idea is presented, and support the need for sketching instruction in engineering and design curriculum.
Sketch-based shape exploration using multiscale free-form surface editing
Authors: Orbay Günay , Yümer Mehmet Ersın , Kara Levent Burak 
Published: August 2012

AbstractThe hierarchical construction of solid models with current computer-aided design systems provide little support in creating and editing free-form surfaces commonly encountered in industrial design. In this work, we propose a new design exploration method that enables sketch-based editing of free-form surface geometries where specific modifications can be applied at different levels of detail. This multilevel detail approach allows the designer to work from existing models and make alterations at coarse and fine representations of the geometry, thereby providing increased conceptual flexibility during modeling. At the heart of our approach lies a multiscale representation of the geometry obtained through a spectral analysis on the discrete free-form surface. This representation is accompanied by a sketch-based surface editing algorithm that enables edits to be made at different levels. The seamless transfer of modifications across different levels of detail facilitates a fluid exploration of the geometry by eliminating the need for a manual specification of the shape hierarchy. We demonstrate our method with several design examples.
Validation of a quantitative FFQ for a study of diet and risk of colorectal adenoma among Japanese Brazilians
Authors: Pakseresht Mohammadreza , Miyajima Nelson Tomio , Shelton Andrew , Iwasaki Motoki , Tsugane Shoichiro , Le Marchand Loic , Sharma Sangita 
Published: August 2012

AbstractObjectiveTo assess the validity of a 161-item quantitative FFQ (QFFQ) that was developed to evaluate dietary risk factors for a colorectal adenoma case–control study.DesignA cross-sectional validation study of the QFFQ against 4 d food diary using Pearson correlation coefficients, cross-classification, weighted κ statistics and Bland–Altman plotting.SettingTwo hospitals in São Paulo, Brazil.SubjectsNinety-seven healthy Japanese-Brazilian adults (40–75 years) were recruited. One participant was excluded from the analysis due to unusual energy intake report.ResultsMean daily nutrient intakes from the QFFQ were higher than from the food diary. The mean Pearson correlation coefficient for nutrient intakes between the QFFQ and the average of the 4 d food diary was 0·43, and increased to 0·45 after correcting correlations for attenuation due to residual day-to-day variation in the food diary measurements. Adjustment for total energy and further adjustment for age and gender decreased the correlation; however, 77 % of observations remained in the same or adjacent quartiles with a mean weighted κ of 0·22. Bland–Altman plots on loge-transformed data showed no linear trend between the differences and means for energy, fat, protein, total folate and vitamin C. Compared with the food diary, the QFFQ showed consistently reasonable performance for dietary fibre, total folate, retinol, riboflavin and vitamin C.ConclusionsThis investigation supports the relative validity of the QFFQ as a method for assessing long-term dietary intake. The instrument will be a useful tool in the analysis of diet–adenoma associations in the case–control study.
How large are projected 21st century storm track changes?
Authors: Harvey B. J. , Shaffrey L. C. , Woollings T. J. , Zappa G. , Hodges K. I. 
Published: August 2012

Projected changes in the extra‐tropical wintertime storm tracks are investigated using the multi‐model ensembles from both the third and fifth phases of the World Climate Research Programme's Coupled Model Intercomparison Project (CMIP3 and CMIP5). The aim is to characterize the magnitude of the storm track responses relative to their present‐day year‐to‐year variability. For the experiments considered, the ‘middle‐of‐the‐road’ scenarios in each CMIP, there are regions of the Northern Hemisphere where the responses of up to 40% of the models exceed half of the inter‐annual variability, and for the Southern Hemisphere there are regions where up to 60% of the model responses exceed half of the inter‐annual variability.
Evolution of CIR storm on 22 July 2009
Authors: Perez J. D. , Grimes E. W. , Goldstein J. , McComas D. J. , Valek P. , Billor N. 
Published: August 2012

Global images of ion intensities are deconvolved from TWINS ENA images during the main and recovery phase of a CIR storm on 22 July 2009. The global spatial ion images taken at different times, along with solar wind data, geomagnetic activity indices, geosynchronous orbit observations, and in situ measurements from the THEMIS mission provide a picture of the evolution of the ring current during both the main phase and early recovery phase of the storm. Major features of the evolution are consistent with expectations based upon time dependent geomagnetic indices, e.g., SYM/H and ASY/H, and geosynchronous orbit detection of dipolarizations from GOES 11 and 12. Direct comparisons are made with in situ THEMIS ESA and SST spectral measurements. The peak energy of the ion spectrum in the ring current is seen to decrease in the recovery phase. The time evolution of the ion energy spectra over the range from 2.5 to 97.5 keV at the spatial peaks of the ring current in the inner magnetosphere obtained from ENA images is presented for the first time.
Super-resolution fluorescence imaging of organelles in live cells with photoswitchable membrane probes
Authors: Shim Sang-Hee , Xia Chenglong , Zhong Guisheng , Babcock Hazen P. , Vaughan Joshua C. , Huang Bo , Wang Xun , Xu Cheng , Bi Guo-Qiang , Zhuang Xiaowei 
Published: August 2012

Imaging membranes in live cells with nanometer-scale resolution promises to reveal ultrastructural dynamics of organelles that are essential for cellular functions. In this work, we identified photoswitchable membrane probes and obtained super-resolution fluorescence images of cellular membranes. We demonstrated the photoswitching capabilities of eight commonly used membrane probes, each specific to the plasma membrane, mitochondria, the endoplasmic recticulum (ER) or lysosomes. These small-molecule probes readily label live cells with high probe densities. Using these probes, we achieved dynamic imaging of specific membrane structures in living cells with 30–60 nm spatial resolution at temporal resolutions down to 1–2 s. Moreover, by using spectrally distinguishable probes, we obtained two-color super-resolution images of mitochondria and the ER. We observed previously obscured details of morphological dynamics of mitochondrial fusion/fission and ER remodeling, as well as heterogeneous membrane diffusivity on neuronal processes.
Structural divergence of paralogous S components from ECF-type ABC transporters
Authors: Berntsson Ronnie P.-A. , ter Beek Josy , Majsnerowska Maria , Duurkens Ria H. , Puri Pranav , Poolman Bert , Slotboom Dirk-Jan 
Published: August 2012

Energy coupling factor (ECF) proteins are ATP-binding cassette transporters involved in the import of micronutrients in prokaryotes. They consist of two nucleotide-binding subunits and the integral membrane subunit EcfT, which together form the ECF module and a second integral membrane subunit that captures the substrate (the S component). Different S components, unrelated in sequence and specific for different ligands, can interact with the same ECF module. Here, we present a high-resolution crystal structure at 2.1 Å of the biotin-specific S component BioY from
Lactococcus lactis
. BioY shares only 16% sequence identity with the thiamin-specific S component ThiT from the same organism, of which we recently solved a crystal structure. Consistent with the lack of sequence similarity, BioY and ThiT display large structural differences (rmsd = 5.1
Å
), but the divergence is not equally distributed over the molecules: The S components contain a structurally conserved N-terminal domain that is involved in the interaction with the ECF module and a highly divergent C-terminal domain that binds the substrate. The domain structure explains how the S components with large overall structural differences can interact with the same ECF module while at the same time specifically bind very different substrates with subnanomolar affinity. Solitary BioY (in the absence of the ECF module) is monomeric in detergent solution and binds D-biotin with a high affinity but does not transport the substrate across the membrane.
Structural investigations of a
Podoviridae streptococcus
phage C1, implications for the mechanism of viral entry
Authors: Aksyuk Anastasia A. , Bowman Valorie D. , Kaufmann Bärbel , Fields Christopher , Klose Thomas , Holdaway Heather A. , Fischetti Vincent A. , Rossmann Michael G. 
Published: August 2012

The
Podoviridae
phage C1 was one of the earliest isolated bacteriophages and the first virus documented to be active against streptococci. The icosahedral and asymmetric reconstructions of the virus were calculated using cryo-electron microscopy. The capsid protein has an HK97 fold arranged into a
T
= 4 icosahedral lattice. The C1 tail is terminated with a
φ
29-like knob, surrounded by a skirt of twelve long appendages with novel morphology. Several C1 structural proteins have been identified, including a candidate for an appendage. The crystal structure of the knob has an N-terminal domain with a fold observed previously in tube forming proteins of
Siphoviridae
and
Myoviridae
phages. The structure of C1 suggests the mechanisms by which the virus digests the cell wall and ejects its genome. Although there is little sequence similarity to other phages, conservation of the structural proteins demonstrates a common origin of the head and tail, but more recent evolution of the appendages.
Oxygen level: the dominant of resistive switching characteristics in cerium oxide thin films
Authors: Younis Adnan , Chu Dewei , Li Sean 
Published: August 2012

Abstract
Currently, resistive switching mechanisms in metal oxide thin films are not clearly understood due to lack of solid evidence. In this work, the switching behaviour of the Au/CeO2/conductive glass structure was analysed, where reproducible and pronounced resistive switching characteristics were obtained. The role of oxygen vacancies in switching characteristics was investigated. The concentration of oxygen vacancies in the CeO2 thin films was controlled by post-annealing and monitored by x-ray photon spectroscopy. The reduction in the switching ratio and the intensity of the peak associated with oxygen concentration O 1s level after annealing treatment confirmed the dominating role of oxygen vacancies in switching behaviour.
Electron temperature, ion density and energy influx measurements in a tubular plasma reactor for powder surface modification
Authors: Roth C , Oberbossel G , Rohr P Rudolf von 
Published: August 2012

Abstract
The tubular plasma reactor was designed for the continuous surface modification of fine powders in non-equilibrium RF discharges. So far, little has been known about the plasma characteristics of this inductively coupled reactor system. Therefore, moderate pressure argon–oxygen discharges, commonly used for powder processing, are investigated with tailor-made probe techniques. The influence of plasma power, system pressure, gas composition and mean gas velocity on the axial profiles of plasma parameters was studied. Electron temperature and positive ion density profiles were measured with a Langmuir double probe and the energy influx due to the plasma was determined by a new type of calorimetric probe. The limits for the E–H-mode transition are provided and photographs of the discharge are presented to illustrate the relationship between process parameters and plasma characteristics. Both, ion density and energy influx increased with rising plasma power. The axial energy influx profiles were in addition strongly influenced by the mean gas velocity. Based on these profiles the maximum transient particle temperature was calculated as a function of the particle diameter. Particle temperatures in the order of 100 °C were estimated, whereas the thermal load of the substrates rises with increasing plasma power, residence time and pressure.
Fiber texturing in nano-crystalline TiO2 thin films deposited at 150 °C by dc-reactive sputtering on fiber-textured [0 0 0 1] ZnO : Al substrates
Authors: Pellegrino Giovanna , Bongiorno Corrado , Ravesi Sebastiano , Alberti Alessandra 
Published: August 2012

Abstract
TiO2 thin films were deposited at an effective surface temperature of 150 °C by dc-reactive magnetron sputtering on ZnO : Al oriented substrates having a fiber texture along the [0 0 0 1] axis, and studied by transmission electron microscopy and x-ray diffraction analyses. The substrate texturing was used to tailor the TiO2 structure in such a way that a porous matrix made of anatase nano-grains (10 nm in diameter) is formed instead of an amorphous layer (as observed at 150 °C on glass). Additionally, we demonstrate that, by adding an ex situ 200 °C annealing, the anatase domains also gain a fiber texture with the axes aligned to that of the substrate. The TiO2/AZO structural coupling is expected to play a crucial role for the carrier transport through the interface as required in dye-sensitized solar cells. Moreover, the low temperatures used render the process compatible with commonly used plastics substrates.
Thermal evaporation and x-ray photostability of dodecyl-passivated silicon nanoparticles
Authors: Coxon Paul R , Ashby Shane P , Frogley Mark D , Chao Yimin 
Published: August 2012

Abstract
X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy have been used to study the makeup of thin films of 6.5 nm diameter dodecyl-capped silicon nanoparticles (SiNPs) formed in a one-pot synthesis method of micelle reduction. Thermostability measurements show the SiNPs undergo thermal desorption at ∼240 °C, a higher temperature than for SiNPs capped by shorter hydrocarbon layers owing to the greater size of the nanoparticle system in this case. Suspensions of SiNPs are found to evaporate in a UHV environment intact with the hydrocarbon passivating layer preserved and form thin films which are visualized with microimaging FTIR spectroscopy. The stability of the capping layer within thick SiNP films under extended exposure (up to 2160 s) to 140 eV photons has been examined where XPS spectra show the breakdown of the passivating layer allowing the underlying silicon core to undergo subsequent oxidation.
Structural Characterization of Arabidopsis Leaf Arabinogalactan Polysaccharides
Authors: Tryfona Theodora , Liang Hui-Chung , Kotake Toshihisa , Tsumuraya Yoichi , Stephens Elaine , Dupree Paul 
Published: August 2012

Abstract
Proteins decorated with arabinogalactan (AG) have important roles in cell wall structure and plant development, yet the structure and biosynthesis of this polysaccharide are poorly understood. To facilitate the analysis of biosynthetic mutants, water-extractable arabinogalactan proteins (AGPs) were isolated from the leaves of Arabidopsis (Arabidopsis thaliana) plants and the structure of the AG carbohydrate component was studied. Enzymes able to hydrolyze specifically AG were utilized to release AG oligosaccharides. The released oligosaccharides were characterized by high-energy matrix-assisted laser desorption ionization-collision-induced dissociation mass spectrometry and polysaccharide analysis by carbohydrate gel electrophoresis. The Arabidopsis AG is composed of a β-(1→3)-galactan backbone with β-(1→6)-d-galactan side chains. The β-(1→6)-galactan side chains vary in length from one to over 20 galactosyl residues, and they are partly substituted with single α-(1→3)-l-arabinofuranosyl residues. Additionally, a substantial proportion of the β-(1→6)-galactan side chain oligosaccharides are substituted at the nonreducing termini with single 4-O-methyl-glucuronosyl residues via β-(1→6)-linkages. The β-(1→6)-galactan side chains are occasionally substituted with α-l-fucosyl. In the fucose-deficient murus1 mutant, AGPs lack these fucose modifications. This work demonstrates that Arabidopsis mutants in AGP structure can be identified and characterized. The detailed structural elucidation of the AG polysaccharides from the leaves of Arabidopsis is essential for insights into the structure-function relationships of these molecules and will assist studies on their biosynthesis.
Survival of theAfrican white‐backed vultureGyps africanusin north‐easternSouthAfrica
Authors: Monadjem Ara , Botha Andre , Murn Campbell 
Published: August 2012

AbstractOld World vultures are in decline across their entire range. Although critical for the formulation of effective conservation measures, neither survival nor movement patterns of African vultures are adequately known. This paper presents survival and movement data on theAfrican white‐backed vultures (Gyps africanus) fromSouthAfrica. Survival estimates were modelled on resightings of tagged vultures. Birds were captureden masseand resighted betweenNovember 2005 andDecember 2010. A total of 93 adult and subadult birds were fitted with uniquely numbered patagial tags, which were resighted 3707 times(mean of 39.8 resightings per bird). The programmeMARKwas used to estimate survival. The best model was one where survival and recaptures varied only with time (e.g. year). However, owing to the fading (illegibility) of tags in later years, the relationship with time is probably spurious. The second best model was one where survival and recaptures varied with age and time. Annual survival estimates increased from 85.2% in second‐year birds to 99.9% in adults. This corresponds well with the survival of two otherGypsvultures that have been studied to date and underscores the point that additional mortality of adults in these long‐lived species will result in rapid population declines.