bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐dimensional hybrid models of H+‐He++ expanding solar wind plasma heating
Authors: Ofman L. , Viñas A. F. , Maneva Y.
Published: June 2014

Preferential heating and acceleration of the solar wind He++ ions compared to protons in fast solar wind streams have been known for decades, thanks to in situ spacecraft measurements at 0.29–5 AU. Turbulent magnetic field fluctuations with approximate power law spectra have been observed as well. However, the exact causes of these processes are still not known due to the lack of detailed information on the magnetic field fluctuations and ion velocity distributions in the acceleration region of the solar wind. Here the collisionless heating processes in expanding solar wind plasma are investigated using 2‐D hybrid modeling with parameters appropriate to the heliocentric distance of 10 RS. In this study the ion dynamics is described kinetically, while electrons are treated as a background massless fluid in an expanding solar wind model. The source of free energy for the heating is introduced through an initial nonequilibrium state of the plasma with large He++ ion temperature anisotropy or with super‐Alfvénic relative ion drift. We also employ an externally imposed spectrum of magnetic fluctuations in the frequency range below the proton gyroresonant frequency to heat the He++ ions. We investigate the effects of solar wind radial expansion by modeling several values of the expansion rate in a parametric study. We find that the preferential ion heating is attained in both nonexpanding and expanding solar wind models. Thus, the expansion has little effect on the preferential He++ ion heating by the processes considered here. Moreover, the expansion leads to faster evolution of the magnetosonic drift instability, reducing the drift velocity to lower values sooner, and the corresponding generation of the magnetic fluctuations that heat the ions, compared to the nonexpanding case. This is due to the reduction of the perpendicular particle velocities in the expanding (inflated) frame. For cases with little proton perpendicular heating, the solar wind expansion leads to the reduction of the proton temperature anisotropy to values less than one in the low‐βp∥ solar wind acceleration region consistent with some observed values. However, this effect must be offset by perpendicular proton heating—likely by the same process that heats the He++ ions to be consistent with the full range of observed proton perpendicular temperature values.
Period and damping factor of Pi2 pulsations during oscillatory flow braking in the magnetotail
Authors: Panov E. V. , Baumjohann W. , Nakamura R. , Kubyshkina M. V. , Glassmeier K.‐H. , Angelopoulos V. , Petrukovich A. A. , Sergeev V. A.
Published: June 2014

Using 25 observations of damped oscillatory flow behavior in the near‐Earth plasma sheet by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes during the 2008–2009 magnetotail seasons, we compare the oscillation period and the damping factor of the plasma sheet flows with those of the Pi2 magnetic pulsations on the ground at auroral and midlatitudes near the local time of the conjugate ionospheric THEMIS footprints. Whereas the damping of the plasma sheet flows and of the pulsations on the ground occurs on the same time scales, the frequency of the pulsations is on average twice the frequency of the plasma sheet flows. We conclude that larger‐amplitude ground pulsations at auroral latitudes were caused by the oscillatory flow braking in the plasma sheet, presumably through alternating field‐aligned currents as suggested by Panov et al. (2013c).
Seasonal variability of the East Greenland Coastal Current
Authors: Bacon Sheldon , Marshall Abigail , Holliday N. Penny , Aksenov Yevgeny , Dye Stephen R.
Published: June 2014

The East Greenland Coastal Current (EGCC) is characterized as cold, low‐salinity polar waters flowing equatorward on the east Greenland shelf. It is an important conduit of freshwater from the Arctic Ocean, but our present understanding of it is poor, outside of an assortment of measurements which stem mainly from summertime visits by research vessels. This manuscript first describes measurements from moored instruments deployed on the East Greenland shelf (∼63°N) between 2000 and 2004. The measurements are then used to show that a high‐resolution coupled ice‐ocean global general circulation model supports a realistic representation of the EGCC. The results show that the EGCC exists throughout the year and is stronger in winter than in summer. The model EGCC seawater transports are a maximum (minimum) in February (August), at 3.8 (1.9) × 106 m3 s−1. Freshwater transports, including modeled estimates of sea ice transport and referenced to salinity 35.0, are a maximum (minimum) in February (August) at 106 (59) × 103 m3 s−1. The model results show that wind and buoyancy forcing are of similar importance to EGCC transport. An empirical decomposition of the buoyancy‐forced transport into a buoyancy‐only component and a coupled wind and buoyancy component indicates the two to be of similar magnitude in winter. The model annual mean freshwater flux of ∼80–90 × 103 m3 s−1 approaches 50% of the net rate of Arctic freshwater gain, underlining the climatic importance of the EGCC.
Eddies in the Red Sea: A statistical and dynamical study
Authors: Zhan Peng , Subramanian Aneesh C. , Yao Fengchao , Hoteit Ibrahim
Published: June 2014

Sea level anomaly (SLA) data spanning 1992–2012 were analyzed to study the statistical properties of eddies in the Red Sea. An algorithm that identifies winding angles was employed to detect 4998 eddies propagating along 938 unique eddy tracks. Statistics suggest that eddies are generated across the entire Red Sea but that they are prevalent in certain regions. A high number of eddies is found in the central basin between 18°N and 24°N. More than 87% of the detected eddies have a radius ranging from 50 to 135 km. Both the intensity and relative vorticity scale of these eddies decrease as the eddy radii increase. The averaged eddy lifespan is approximately 6 weeks. AEs and cyclonic eddies (CEs) have different deformation features, and those with stronger intensities are less deformed and more circular. Analysis of long‐lived eddies suggests that they are likely to appear in the central basin with AEs tending to move northward. In addition, their eddy kinetic energy (EKE) increases gradually throughout their lifespans. The annual cycles of CEs and AEs differ, although both exhibit significant seasonal cycles of intensity with the winter and summer peaks appearing in February and August, respectively. The seasonal cycle of EKE is negatively correlated with stratification but positively correlated with vertical shear of horizontal velocity and eddy growth rate, suggesting that the generation of baroclinic instability is responsible for the activities of eddies in the Red Sea.
A catalog of moisture sources for continental climatic regions
Authors: Nieto Raquel , Castillo Rodrigo , Drumond Anita , Gimeno Luis
Published: June 2014

This technical note describes a catalog of moisture sources for two sets of continental climatic regions: one based on regions with similar late 20th century mean climate and similar projected late 21st century precipitation changes, and the other widely used in IPCC assessment reports. By illustrating with one region by classification, the European one was selected and we identify and characterize all the major sources of moisture, and analyze their interannual variability and the role of the three dominant modes of global climate variability, including the El Niño‐Southern Oscillation (ENSO) and the Northern and Southern Annular Modes (NAM, SAM). We also estimate the influence of those oceanic regions that will see the greatest increases in evaporation rate in future years.
Constraining mid to late Holocene relative sea level change in the southern equatorial Pacific Ocean relative to the Society Islands, French Polynesia
Authors: Rashid Rashid , Eisenhauer Anton , Stocchi Paolo , Liebetrau Volker , Fietzke Jan , Rüggeberg Andres , Dullo Wolf‐Christian
Published: June 2014

Precisely quantifying the current climate‐related sea level change requires accurate knowledge of long‐term geological processes known as Glacial Isostatic Adjustments (GIA). Although the major postglacial melting phase is likely to have ended ∼6–4 ka BP (before present), GIA is still significantly affecting the present‐day vertical position of the mean sea surface and the sea bottom. Here we present empirical rsl (relative sea level) data based on U/Th dated fossil corals from reef platforms of the Society Islands, French Polynesia, together with the corresponding GIA‐modeling. Fossil coral data constrain the timing and amplitude of rsl variations after the Holocene sea level maximum (HSLM). Upon correction for isostatic island subsidence, we find that local rsl was at least ∼1.5 ± 0.4 m higher than present at ∼5.4 ka. Later, minor amplitude variations occurred until ∼2 ka, when the rsl started dropping to its present position with a rate of ∼0.4 mm/yr. The data match with predicted rsl curves based on global ice‐sheet chronologies confirming the role of GIA‐induced ocean siphoning effect throughout the mid to late Holocene. A long lasting Late Holocene highstand superimposed with second‐order amplitudinal fluctuations as seen from our data suggest that the theoretical predicted timing of rsl change can still be refined pending future calibration.
Brittle‐viscous deformation, slow slip, and tremor
Authors: Fagereng Åke , Hillary Graeme W. B. , Diener Johann F. A.
Published: June 2014

Geophysical observations have illuminated a spectrum of fault slip styles from continuous aseismic sliding to fast earthquake slip. We study exhumed intercalated lenses of oceanic crust and sedimentary rocks, deformed to high shear strains. Deformation was partitioned between fractured, rigid blocks, with lengths of tens to hundreds of meters, and surrounding metapelites characterized by interconnected phyllosilicate networks. Under inferred conditions of low effective stress at temperatures > 500°C, locally and transiently elevated shear strain rate in phyllosilicates deforming by dislocation creep can reach those needed for transient slow slip. Concurrently, increased matrix strain rate likely stimulates brittle failure in rigid lenses. The ubiquitous presence of quartz veins and microfractures within rigid material provides evidence for brittle deformation occurring coincident with viscous shearing flow. We suggest that geophysically observed tremor and slow slip may be a manifestation of strain partitioning, where deformation is accommodated viscously in a matrix enveloping rigid lenses.
Empirical estimates of kinetic energy from some recent U.S. tornadoes
Authors: Fricker T. , Elsner J. B. , Camp P. , Jagger T. H.
Published: June 2014

Data from some recent tornado damage assessments are used to compute the percentage of damage path area by enhanced Fujita (EF) rating and to estimate kinetic energy. Only a small fraction of the damage area gets the highest damage rating, and this fraction is lower than a model used by the U.S. Nuclear Regulatory Commission. However, estimates of kinetic energy derived from a characteristic wind speed for each EF rating and the fraction of area with that rating match kinetic energy estimates using the model percentages. On average, the higher the EF rating, the larger the kinetic energy, but there is large variability in the relationship. The average total kinetic energy over the EF1 tornadoes examined in the study is 0.61 TJ, which compares with an average of 2.37 TJ, 40.1 TJ, 36.5 TJ, and 50.4 TJ for the EF2, EF3, EF4, and EF5 tornadoes, respectively. The most energetic tornado examined had a maximum damage rating of EF3.
Magnetic fluctuations embedded in dipolarization inside geosynchronous orbit and their associated selective acceleration of O+ ions
Authors: Nosé M. , Takahashi K. , Keika K. , Kistler L. M. , Koga K. , Koshiishi H. , Matsumoto H. , Shoji M. , Miyashita Y. , Nomura R.
Published: June 2014

We study magnetic fluctuations embedded in dipolarizations in the inner magnetosphere (a geocentric distance of ≤6.6 RE) and their associated ion flux changes, using the Engineering Test Satellite VIII and Active Magnetospheric Particle Tracer Explorers/CCE satellites. We select seven events of dipolarization that occur during the main phase of magnetic storms having a minimum value of the Dst index less than −40 nT. It is found that (1) all of the dipolarization events are accompanied by strong magnetic fluctuations with the major frequency close to the local O+ gyrofrequency; (2) the magnetic fluctuations appear with significant amplitude in the component nearly parallel to the local magnetic field; (3) the strong flux enhancement is seen in the energy range of 1–10 keV only for O+ ions. In terms of frequency and dominant components of the magnetic fluctuations, they are considered to be excited by the drift‐driven electromagnetic ion cyclotron (EMIC) instability that is recently identified with the linear theory. We perform particle tracing for H+ and O+ ions in the electromagnetic fields modeled by the linear dispersion relation of the drift‐driven EMIC instability. Results show that the O+ ions are accelerated to the energy range of 0.5–5 keV and undergo a significant modification of the spectral shape, while the H+ ions have no clear change of spectral shape, being consistent with the observations. We therefore suggest that the electromagnetic fluctuations associated with the dipolarizations can accelerate O+ ions locally and nonadiabatically in the inner magnetosphere. This selective acceleration of O+ ions may play a role in enhancing the O+ energy density in the storm time ring current.
The effect of background conditions on the ionospheric response to solar flares
Authors: Zhu Jie , Ridley Aaron J.
Published: June 2014

The ionospheric response to two X5 solar flares that occurred in different seasons was investigated using the global ionosphere‐thermosphere model. Two questions were investigated: (a) how do different solar flares with similar X‐ray peak intensities disturb the ionosphere during the same background and driving conditions? and (b) how do the geomagnetic field and season affect the ionospheric response to solar flares? These questions were investigated by exchanging the two X5 flares for each other so that there were two pairs of flares with (1) the same background conditions but different irradiances and (2) different background conditions but the same irradiance. The simulations showed that the different solar flares into the same background caused ionospheric disturbances of similar profiles but different magnitudes due to differences in the incident energies, while the same flare spectra caused perturbations of similar magnitudes but different profiles in different backgrounds. On the dayside, the response is primarily controlled by the total integrated energy of the flare, independent of the background. For the northern and southern polar regions, the response is strongly controlled by the solar zenith angle and the incident energy, while the background plays a secondary role. On the nightside, the background conditions, including the magnetic field and season, play a primary role, with the neutral winds and electrodynamics driving the ionospheric response.
The kinetic ballooning/interchange instability as a source of dipolarization fronts and auroral streamers
Authors: Pritchett P. L. , Coroniti F. V. , Nishimura Y.
Published: June 2014

The possibility that the dipolarization fronts (DFs) observed in the plasma sheet could be produced by the ballooning/interchange instability is explored using three‐dimensional electromagnetic particle‐in‐cell simulations. The localized interchange heads produced in the nonlinear stage of the instability exhibit the main near‐equatorial properties of a DF: the cross‐tail extent is on the order of 1 RE, the ramp‐ups in Bz and the magnitude of Ey as well as the sharp density decrease all occur on the ion inertial scale, while there is a more gradual increase in the bulk flow. The field‐aligned currents associated with the breakup of the head should produce a structuring of the corresponding auroral streamer in the ionosphere, a result that is confirmed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky imager data. The dissipation associated with the head occurs in electron‐scale regions in the center of the plasma sheet. Away from the center, the head is strongly modulated by waves with frequency on the order of the ion gyrofrequency. The strength of the accompanying Ey oscillations is in the range of 30–50 mV/m, and the δE/δB ratio is 3–4 times the local Alfvén speed. The waves appear to be produced by the electromagnetic current‐driven ion cyclotron instability.
Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm
Authors: Li W. , Thorne R. M. , Ma Q. , Ni B. , Bortnik J. , Baker D. N. , Spence H. E. , Reeves G. D. , Kanekal S. G. , Green J. C. , Kletzing C. A. , Kurth W. S. , Hospodarsky G. B. , Blake J. B. , Fennell J. F. , Claudepierre S. G.
Published: June 2014

Local acceleration driven by whistler‐mode chorus waves is fundamentally important for accelerating seed electron populations to highly relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus‐driven electron acceleration during the 17 March 2013 storm, when the Van Allen Probes observed very rapid electron acceleration up to several MeV within ~12 hours. A clear radial peak in electron phase space density (PSD) observed near L* ~4 indicates that an internal local acceleration process was operating. We construct the global distribution of chorus wave intensity from the low‐altitude electron measurements made by multiple Polar Orbiting Environmental Satellites (POES) satellites over a broad region, which is ultimately used to simulate the radiation belt electron dynamics driven by chorus waves. Our simulation results show remarkable agreement in magnitude, timing, energy dependence, and pitch angle distribution with the observed electron PSD near its peak location. However, radial diffusion and other loss processes may be required to explain the differences between the observation and simulation at other locations away from the PSD peak. Our simulation results, together with previous studies, suggest that local acceleration by chorus waves is a robust and ubiquitous process and plays a critical role in accelerating injected seed electrons with convective energies (~100 keV) to highly relativistic energies (several MeV).
Altitudinal dependence of evening equatorial F region vertical plasma drifts
Authors: Fejer B. G. , Hui D. , Chau J. L. , Kudeki E.
Published: June 2014

We use Jicamarca incoherent scatter radar measurements to study for the first time the altitudinal variations of late afternoon and early night equatorial F region vertical plasma drifts. We also present the initial vertical drift measurements over the altitudinal range from about 200 to 2000 km. These data show that the afternoon drifts decrease weakly with altitude. Near their evening prereversal enhancements, the vertical drifts generally increase with altitude below about the F layer peak, decrease with height near the F layer peak and above, and are nearly height independent in the (solar flux dependent) topside ionosphere. The transition altitudes from height‐decreasing to height‐independent evening upward drifts decrease with altitude from solar maximum to solar minimum. After their reversal to downward, the vertical drifts do not change much with height. The altitudinal dependence of the evening vertical drifts has large day‐to‐day variability and is closely related to the time dependence of the zonal drifts, as expected from the curl‐free electric field condition.
Increasing life expectancy of water resources literature
Authors: Heistermann M. , Francke T. , Georgi C. , Bronstert A.
Published: June 2014

In a study from 2008, Larivière and colleagues showed, for the field of natural sciences and engineering, that the median age of cited references is increasing over time. This result was considered counterintuitive: with the advent of electronic search engines, online journal issues and open access publications, one could have expected that cited literature is becoming younger. That study has motivated us to take a closer look at the changes in the age distribution of references that have been cited in water resources journals since 1965. Not only could we confirm the findings of Larivière and colleagues. We were also able to show that the aging is mainly happening in the oldest 10–25% of an average reference list. This is consistent with our analysis of top‐cited papers in the field of water resources. Rankings based on total citations since 1965 consistently show the dominance of old literature, including text books and research papers in equal shares. For most top‐cited old‐timers, citations are still growing exponentially. There is strong evidence that most citations are attracted by publications that introduced methods which meanwhile belong to the standard toolset of researchers and practitioners in the field of water resources. Although we think that this trend should not be overinterpreted as a sign of stagnancy, there might be cause for concern regarding how authors select their references. We question the increasing citation of textbook knowledge as it holds the risk that reference lists become overcrowded, and that the readability of papers deteriorates.
Estimating information entropy for hydrological data: One‐dimensional case
Authors: Gong Wei , Yang Dawen , Gupta Hoshin V. , Nearing Grey
Published: June 2014

There has been a recent resurgence of interest in the application of Information Theory to problems of system identification in the Earth and Environmental Sciences. While the concept of entropy has found increased application, little attention has yet been given to the practical problems of estimating entropy when dealing with the unique characteristics of two commonly used kinds of hydrologic data: rainfall and runoff. In this paper, we discuss four important issues of practical relevance that can bias the computation of entropy if not properly handled. The first (zero effect) arises when precipitation and ephemeral streamflow data must be viewed as arising from a discrete‐continuous hybrid distribution due to the occurrence of many zero values (e.g., days with no rain/no runoff). Second, in the widely used bin‐counting method for estimation of PDF's, significant error can be introduced if the bin width is not carefully selected. The third (measurement effect) arises due to the fact that continuously varying hydrologic variables can typically only be observed discretely to some degree of precision. The Fourth (skewness effect) arises when the distribution of a variable is significantly skewed. Here we present an approach that can deal with all four of these issues, and test them with artificially generated and real hydrological data. The results indicate that the method is accurate and robust.
Face of a fighter: Bizygomatic width as a cue of formidability
Authors: Zilioli Samuele , Sell Aaron N. , Stirrat Michael , Jagore Justin , Vickerman William , Watson Neil V.
Published: June 2014

Humans can accurately extract information about men's formidability from their faces; however, the actual facial cues that inform these judgments have not been established. Here, through three studies, we test the hypothesis that bizygomatic width (i.e. facial width‐to‐height ratio, fWHR) covaries with actual physical formidability (hypothesis #1) and that humans use this cue when making assessments of formidability (hypothesis #2). Our data confirm that fWHR is predictive of actual fighting ability among professional combatants (study 1). We further show that subjects' assessments of formidability covary with the target's fWHR on natural faces (study 2), computer‐generated images of strong and weak faces (study 2), and experimentally manipulated computer‐generated faces (study 3). These results support the hypothesis that bizygomatic width is a cue of formidability that is assessed during agonistic encounters. Aggr. Behav. 41:322–330, 2015. © 2014 Wiley Periodicals, Inc.
Using the Type II Cycloisomerization Reaction of 1,6‐Enynes as a Mechanistic Probe to Identify the Real Catalytic Species of GaX3 and InX3
Authors: Zhuo Lian‐Gang , Shi Yao‐Cheng , Yu Zhi‐Xiang
Published: June 2014

Previously, we found that InCl2+ is the real catalytic species in InCl3‐catalyzed type II cycloisomerization of 1,6‐enynes for generating nonconjugated dienes. We further used this cycloisomerization reaction as a mechanistic probe to study whether GaCl3, GaBr3, InBr3, InI3 also have GaCl2+, GaBr2+, InBr2+, and InI2+ as the real catalytic species. Experimental and computational results from the mechanistic probe reaction here support that the real catalytic species are positively charged GaCl2+, GaBr2+, InBr2+, and InI2+.
Bio‐composites for structural applications: Poly‐l‐lactide reinforced with long sisal fiber bundles
Authors: Prajer Marek , Ansell Martin P.
Published: June 2014

Fully bio‐based and biodegradable composites were compression molded from unidirectionally aligned sisal fiber bundles and a polylactide polymer matrix (PLLA). Caustic soda treatment was employed to modify the strength of sisal fibers and to improve fiber to matrix adhesion. Mechanical properties of PLLA/sisal fiber composites improved with caustic soda treatment: the mean flexural strength and modulus increased from 279 MPa and 19.4 GPa respectively to 286 MPa and 22 GPa at a fiber volume fraction of Vf = 0.6. The glass transition temperature decreased with increasing fiber content in composites reinforced with untreated sisal fibers due to interfacial friction. The damping at the caustic soda‐treated fibers‐PLLA interface was reduced due to the presence of transcrystalline morphology at the fiber to matrix interface. It was demonstrated that high strength, high modulus sisal‐PLLA composites can be produced with effective stress transfer at well‐bonded fiber to matrix interfaces. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40999.
A slow shape‐recovery polymer based on polylactic acid
Authors: Okamoto Hirotaka , Katagiri Yoshihide , Nakano Mitsuru , Usuki Arimitsu
Published: June 2014

Shape‐recovery materials are expected to have numerous applications as ductile structural compounds which can recover their shape after significant deformations. We report a new type of shape‐recovery polymer consisting of polylactic acid (PLA) derived from glucose compounded with a cinnamic acid ester derived from lignin. Unlike existing shape‐memory polymers, this shape‐recovery polymer exhibits a spontaneous but gradual recovery of its original dimensions, following elongation and release of stress, over a period ranging from several hours to days, without the requirement for external stimulus. In the case of a typical rubber or elastomer, shape‐recovery takes place almost instantaneously after deformation due to the energy stored by the material. Although the slow shape‐recovery polymer reported herein appears to exhibit plastic deformation as if the energy of elongation is lost, it eventually recovers from the deformation in the same manner as an elastic material. This material may have applicability to the energy‐absorbing and shape restoration automotive parts. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41004.
Primary Sjögren's Syndrome Is Characterized by Distinct Phenotypic and Transcriptional Profiles of IgD+ Unswitched Memory B Cells
Authors: Roberts Mustimbo E. P. , Kaminski Denise , Jenks Scott A. , Maguire Craig , Ching Kathryn , Burbelo Peter D. , Iadarola Michael J. , Rosenberg Alexander , Coca Andreea , Anolik Jennifer , Sanz Iñaki
Published: June 2014

Objective

The significance of distinct B cell abnormalities in primary Sjögren's syndrome (SS) remains to be established. We undertook this study to analyze the phenotype and messenger RNA (mRNA) transcript profiles of B cell subsets in patients with primary SS and to compare them with those in sicca syndrome patients and healthy controls.

Methods

CD19+ B cells from 26 patients with primary SS, 27 sicca syndrome patients, and 22 healthy controls were analyzed by flow cytometry. Gene expression profiles of purified B cell subsets (from 3–5 subjects per group per test) were analyzed using Affymetrix gene arrays.

Results

Patients with primary SS had lower frequencies of CD27+IgD− switched memory B cells and CD27+IgD+ unswitched memory B cells compared with healthy controls. Unswitched memory B cell frequencies were also lower in sicca syndrome patients and correlated inversely with serologic hyperactivity in both disease states. Further, unswitched memory B cells in primary SS had lower expression of CD1c and CD21. Gene expression analysis of CD27+ memory B cells separated patients with primary SS from healthy controls and identified a subgroup of sicca syndrome patients with a primary SS–like transcript profile. Moreover, unswitched memory B cell gene expression analysis identified 187 genes differentially expressed between patients with primary SS and healthy controls.

Conclusion

A decrease in unswitched memory B cells with serologic hyperactivity is characteristic of both established primary SS and a subgroup of sicca syndrome, which suggests the value of these B cells both as biomarkers of future disease progression and for understanding disease pathogenesis. Overall, the mRNA transcript analysis of unswitched memory B cells suggests that their activation in primary SS takes place through innate immune pathways in the context of attenuated antigen‐mediated adaptive signaling. Thus, our findings provide important insight into the mechanisms and potential consequences of decreased unswitched memory B cells in primary SS.
Interleukin‐21 Promotes Germinal Center Reaction by Skewing the Follicular Regulatory T Cell to Follicular Helper T Cell Balance in Autoimmune BXD2 Mice
Authors: Ding Yanna , Li Jun , Yang PingAr , Luo Bao , Wu Qi , Zajac Allan J. , Wildner Oliver , Hsu Hui‐Chen , Mountz John D.
Published: June 2014

Objective

Follicular regulatory T (Tfr) cells act as the regulatory counterpart of follicular helper T (Tfh) cells to suppress germinal center (GC) B cell differentiation. We recently showed that interleukin‐21 (IL‐21) promoted Tfh cell differentiation in autoimmune BXD2 mice that develop spontaneous GCs. This study was undertaken to determine the modulatory effects of IL‐21 on Tfr cells and the Tfr cell to Tfh cell balance in BXD2 mice.

Methods

The percentage and phenotype of Tfr cells were determined in BXD2 and BXD2‐IL21−/− mice. The effects of IL‐21 on Tfr cells and the Tfr cell:Tfh cell ratio were evaluated. Sorted Tfr cells from BXD2‐IL21−/− mice were cocultured with Tfh cells and B cells, or transferred into BXD2 mice to determine their function.

Results

The percentages and numbers of GC B cells and Tfh cells were significantly reduced, but the percentage of Tfr cells was 2‐fold higher in BXD2‐IL21−/− mice than in wild‐type BXD2 mice. Administration of AdIL‐21 to BXD2‐IL21−/− mice decreased the percentages and numbers of Tfr cells and the Tfr cell:Tfh cell ratio but increased the number of GC B cells in the spleen. Recombinant murine IL‐21 suppressed FoxP3 and significantly reduced Tgfb1, Il2, and Gitr but enhanced Il21, Il6, Pd1, Cxcr5, and Icos expression in Tfr cells. IL‐21 also counteracted Tfr cell–mediated inhibition of antibody secretion in the Tfh cell–B cell coculture system. Transfer of Tfr cells into young BXD2 mice reduced GC size and decreased the numbers of autoantibody‐producing B cells.

Conclusion

Our findings indicate that high levels of IL‐21 selectively enhance Tfh cell differentiation but inhibit Tfr cell commitment and the suppressive function of Tfr cells on Tfh cells and B cells, suggesting that IL‐21 skews the balance from Tfr cells to Tfh cells to promote autoreactive GC reactions in BXD2 mice.
Agreement Between Clinical Practice and Trained Central Reading in Reading of Sacroiliac Joints on Plain Pelvic Radiographs: Results From the DESIR Cohort
Authors: van den Berg Rosaline , Lenczner Grégory , Feydy Antoine , van der Heijde Désirée , Reijnierse Monique , Saraux Alain , Rahmouni Alain , Dougados Maxime , Claudepierre Pascal
Published: June 2014

Objective

To investigate the degree of agreement between local rheumatologists/radiologists and central trained readers (external standard) on the presence/absence of sacroiliitis on radiographs of the sacroiliac (SI) joints.

Methods

Patients with inflammatory back pain (duration ≥3 months but <3 years) suggestive of axial spondyloarthritis (SpA) were included in the Devenir des Spondylarthropathies Indifferérenciées Récentes (DESIR) cohort. Baseline radiographs of the SI joints were interpreted by 2 central readers (modified New York criteria); cases of disagreement were adjudicated by a third reader, yielding a positive or a negative result (central reading). The same radiographs were also interpreted by local radiologists/rheumatologists and were rated as “normal,” “doubtful sacroiliitis,” “obvious sacroiliitis,” or “SI joint fusion” (local reading); positive findings were defined as “at least unilateral obvious sacroiliitis,” “bilateral obvious sacroiliitis,” or “at least unilateral fusion.” Agreement and misclassifications between central readers and between central reading versus local reading were calculated (kappa values).

Results

Interreader agreement between the central readers was moderate (κ = 0.54); 108 of 688 radiographs (15.7%) were adjudicated. According to local reading (“at least unilateral obvious sacroiliitis”), 183 of the 688 patients (26.6%) had sacroiliitis, whereas according to central reading, 145 of 688 patients (21.1%) had sacroiliitis. Agreement between local reading and central reading was also moderate (κ = 0.55); 76 of 183 patients (41.5%) with “at least unilateral obvious sacroiliitis” (positive by local reading) and 32 of 109 patients (29.4%) with “bilateral obvious sacroiliitis” or “at least unilateral fusion” (positive by local reading) were rated as “negative” by central reading, and 38 of 505 patients (7.5%) and 68 of 579 patients (11.7%), respectively, without sacroiliitis (negative by local reading) were interpreted as “positive” by central reading.

Conclusion

In patients with recent‐onset inflammatory back pain, both trained readers and local rheumatologists/radiologists agreed only moderately on the recognition of radiographic sacroiliitis. A significant proportion of locally recognized ankylosing spondylitis (AS) patients were not confirmed as having AS by central reading (false positive), while a small minority of patients were false negative, indicating the necessity of reevaluating the role of radiographic sacroiliitis as diagnostic criterion for axial SpA.
Alpha C‐Telopeptide of Type I Collagen Is Associated With Subchondral Bone Turnover and Predicts Progression of Joint Space Narrowing and Osteophytes in Osteoarthritis
Authors: Huebner Janet L. , Bay‐Jensen Anne C. , Huffman Kim M. , He Yi , Leeming Diana J. , McDaniel Gary E. , Karsdal Morten A. , Kraus Virginia B.
Published: June 2014

Objective

To evaluate joint tissue remodeling using the urinary collagen biomarkers urinary α‐C‐telopeptide of type I collagen (α‐CTX) and urinary C‐telopeptide of type II collagen (CTX‐II) and to determine the association of these biomarkers with osteoarthritis (OA) severity, progression, and localized knee bone turnover.

Methods

Participants (n = 149) with symptomatic and radiographic knee OA underwent fixed‐flexion knee radiography at baseline and 3 years, and late‐phase bone scintigraphy of both knees at baseline, which were scored semiquantitatively for osteophyte and joint space narrowing (JSN) severity and uptake intensity, with scores summed across knees. Urinary concentrations of α‐CTX and CTX‐II were determined by enzyme‐linked immunosorbent assay. Immunohistochemical analysis of human OA knees was performed to localize the joint tissue origin of the biomarker epitopes.

Results

Urinary α‐CTX concentrations correlated strongly with the intensity of bone scintigraphic uptake and with JSN progression (risk ratio 13.2) and osteophyte progression (risk ratio 3). Urinary CTX‐II concentrations were strongly associated with intensity of bone scintigraphic uptake, with JSN and osteophyte severity, and with OA progression based on osteophyte score. Urinary α‐CTX localized primarily to high bone turnover areas in subchondral bone. CTX‐II localized to the bone–cartilage interface, the tidemark, and damaged articular cartilage.

Conclusion

Baseline urinary α‐CTX, which was localized to high turnover areas of subchondral bone, was associated with dynamic bone turnover of knees, as signified by scintigraphy, and progression of both osteophytes and JSN. Urinary CTX‐II correlated with JSN and osteophyte severity and progression of osteophytes. To our knowledge, this represents the first report of serologic markers reflecting subchondral bone turnover. These collagen markers may be useful for noninvasive detection and quantification of active subchondral bone turnover and joint remodeling in knee OA.
Content‐based citation analysis: The next generation of citation analysis
Authors: Ding Ying , Zhang Guo , Chambers Tamy , Song Min , Wang Xiaolong , Zhai Chengxiang
Published: June 2014

Traditional citation analysis has been widely applied to detect patterns of scientific collaboration, map the landscapes of scholarly disciplines, assess the impact of research outputs, and observe knowledge transfer across domains. It is, however, limited, as it assumes all citations are of similar value and weights each equally. Content‐based citation analysis (CCA) addresses a citation's value by interpreting each one based on its context at both the syntactic and semantic levels. This paper provides a comprehensive overview of CAA research in terms of its theoretical foundations, methodical approaches, and example applications. In addition, we highlight how increased computational capabilities and publicly available full‐text resources have opened this area of research to vast possibilities, which enable deeper citation analysis, more accurate citation prediction, and increased knowledge discovery.
Block Copolymer‐Derived Monolithic Polymer Films and Membranes Comprising Self‐Organized Cylindrical Nanopores for Chemical Sensing and Separations
Authors: Ito Takashi
Published: June 2014

Microphase separation of block copolymers (BCPs) has been extensively studied because it leads to the self‐assembled formation of periodic structures controlled on the scale of tens of nanometers. In particular, BCP‐derived cylindrical microdomains have attracted considerable interest for various applications owing to their well‐defined shapes of uniform and tunable diameters. This focus review highlights recent efforts to apply BCP‐derived monolithic films/membranes comprising cylindrical nanopores for chemical sensing and separations. The nanopores provide confined molecular pathways that exhibit enhanced selectivity based on steric, electrostatic, and chemical interactions, and thus, enable us to design unique electrochemical sensors and highly efficient separation membranes.
Electron Transport Characteristics of the Dimeric 1,4‐Benzenedithiol Junction
Authors: Wang Lin , Li Shu‐Ying , Yuan Jing‐He , Gu Jing‐Ying , Wang Dong , Wan Li‐Jun
Published: June 2014

Understanding the electron transport between single molecules connected through weak interaction is of great importance for molecular electronics. In this paper, we report measurements of the conductivity of the dimeric 1,4‐benzenedithiol (BDT) junction using the scanning tunneling microscopy (STM)‐based current–displacement I(s) method. The conductance was measured to be 6.14×10−6 G0, a value almost two orders of magnitude lower than that of the monomer BDT junction. In control experiments, the probability of junction formation decreased with the presence of tris(2‐chloroethyl) phosphate (TCEP), a reducing reagent for the disulfide bond. According to theoretical computations, the dihedral angle of the SS bond tends to take a perpendicular conformation. This non‐conjugated structure localizes the electron distribution and accounts for the low conductivity of the disulfide linkage.
Size‐Dependent Electrochemical Magnesium Storage Performance of Spinel Lithium Titanate
Authors: Wu Na , Yin Ya‐Xia , Guo Yu‐Guo
Published: June 2014

Li4Ti5O12 nanoparticles (LTO NPs) with different particle sizes were synthesized by a simple sol–gel progress. The effect of LTO particle size on the electrochemical behavior in Mg secondary batteries was investigated. Results showed that magnesium storage behaviors in LTO are strongly size dependent. The Mg2+ electrochemical insertion into LTO becomes notable only when the particle size is below 40 nm. Moreover, the theoretical maximum capacity of LTO can be reached in crystallite sizes less than 10 nm. LTO NPs with 7–8 nm in size exhibited a substantial reversible capacity of 175 mA h g−1 and outstanding cycling stability, maintaining 95 % capacity retention after 500 cycles. This result indicates that the LTO NPs with average particle size of 7–8 nm have high potential for use in high‐rate and durable Mg secondary batteries. These results provide insight into how confining particles to nanosize will be critical to the preparation of suitable electrode materials for Mg secondary batteries.
Ligand‐Free Palladium‐Catalyzed Aerobic Oxidative Coupling of Carboxylic Anhydrides with Arylboronic Acids
Authors: Yin Weiyan , He Haifeng , Zhang Yani , Long Tong
Published: June 2014

We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand‐free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.
Direct Synthesis of Hexagonal NaGdF4 Nanocrystals from a Single‐Source Precursor: Upconverting NaGdF4:Yb3+,Tm3+ and Its Composites with TiO2 for Near‐IR‐Driven Photocatalysis
Authors: Chen Ying , Mishra Shashank , Ledoux Gilles , Jeanneau Erwann , Daniel Marlene , Zhang Jinlong , Daniele Stéphane
Published: June 2014

A novel single‐source precursor NaGd(TFA)4(diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide‐doped upconverting nanocrystals (NCs) that convert near‐infrared radiation into shorter‐wavelength UV/visible light. These NCs were then used to prepare well‐characterized TiO2@NaGdF4:Yb3+,Tm3+ nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented.
Effects of Ce doping on the luminescent property of Ca3SiO4Cl2:Eu phosphor for green lighting
Authors: Chen Jingsheng
Published: June 2014

White light‐emitting diodes (LEDs) for green lighting are new solutions for energy saving and environmental protection. Ca3SiO4Cl2:Ce,Eu is an efficient phosphor for white LEDs. Effective energy transfer from Ce3+ to Eu2+ occurs in Ca3SiO4Cl2:Ce,Eu due to good spectrum overlap between the emission band of Ca3SiO4Cl2:Ce and the excitation band of Ca3SiO4Cl2:Eu, and hues vary systematically from blue to green at different Ce concentrations. A great improvement in the luminescent property of Ca3SiO4Cl2:Eu has been observed on Ce3+ doping, which is attributed to energy transfer from Ce3+ to Eu2+ and an increase in the number of luminescent centers (Eu2+) on Ce doping. The optimal sample has a quantum efficiency of up to 75%, and can be an efficient green phosphor for white LEDs. Copyright © 2014 John Wiley & Sons, Ltd.
Isoforms of wild type proteins often appear as low molecular weight bands on SDS‐PAGE
Authors: Zhang Ju , Lou Xiaomin , Shen Haihong , Zellmer Lucas , Sun Yuan , Liu Siqi , Xu Ningzhi , Liao D. Joshua
Published: June 2014

Immunoblotting, after polyacrylamide gel electrophoresis with sodium dodecyl sulfate (SDS‐PAGE), is a technique commonly used to detect specific proteins. SDS‐PAGE often results in the visualization of protein band(s) in addition to the one expected based on the theoretical molecular mass (TMM) of the protein of interest. To determine the likelihood of additional band(s) being nonspecific, we used liquid chromatography – mass spectrometry to identify proteins that were extracted from bands with the apparent molecular mass (MM) of 40 and 26 kD, originating from protein extracts derived from non‐malignant HEK293 and cancerous MDA‐MB231 (MB231) cells separated using SDS‐PAGE. In total, approximately 57% and 21% of the MS/MS spectra were annotated as peptides in the two cell samples, respectively. Moreover, approximately 24% and 36.2% of the identified proteins from HEK293 and MB231 cells matched their TMMs. Of the identified proteins, 8% from HEK293 and 26% from MB231 had apparent MMs that were larger than predicted, and 67% from HEK293 and 37% from MB231 exhibited smaller MM values than predicted. These revelations suggest that interpretation of the positive bands of immunoblots should be conducted with caution. This study also shows that protein identification performed by mass spectrometry on bands excised from SDS‐PAGE gels could make valuable contributions to the identification of cancer biomarkers, and to cancer‐therapy studies.
Online computer supported collaborative learning (CSCL) for engineering students: A case study in Malaysia
Authors: Balakrishnan Balamuralithara
Published: June 2014

Computer supported collaborative learning (CSCL) via online is an emerging paradigm of educational technology where people can learn together with the help of computer and its related applications. CSCL has become an important and appealing mode of learning across disciplines including engineering. Teamwork is one of the most important elements in engineering profession and collaborative learning is a natural choice for engineering education since it cultivates team among students. This study aims to better understand the adoption of CSCL using Google Docs among engineering students and its relationship with students' attitude toward computer for learning, prior experience of using CSCL tool—Google Docs‐ and students' different learning styles. The outcomes of this investigation suggest that students' attitude toward computer for learning and prior experience have a significant relationship with the students' adoption of CSCL. At the same time, students' different learning styles did not have any impact on the adoption of CSCL in their learning process. © 2014 Wiley Periodicals, Inc. Comput Appl Eng Educ 23:352–362, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21605