bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthetic modelling of the light-travel time effect of circumbinary planets
Authors: Hinse Tobias C. , Lee Jae Woo
Published: January 2014

In recent years several multi-body, circumbinary planets have been proposed to orbit short-period eclipsing binaries. In light of the recent discoveries based on the Kepler data, the existence of such systems seems plausible. However, performing a detailed dynamical analysis reveals that the majority of the proposed planetary systems follow highly unstable orbits. In order to solve the origin of this problem, we have started to model synthetic light-travel time signals of stable planetary systems. In particular, we aim to study the response of the model in various circumstances (e.g red/white noise level, various sampling frequencies, in-homogeneous data sets, baseline dependency.) This work will significantly increase the confidence with which model work is carried out for future systems and help towards an understaning when models break down (e.g resulting in unstable systems).
Doppler Tomographic Observations of Kepler-13b
Authors: Johnson Marshall C. , Cochran William D.
Published: January 2014

We present Doppler tomographic observations of the transiting planet Kepler-13b (aka KOI-13b), a highly inflated hot Jupiter orbiting the Teff=8500 K primary of a hierarchical triple stellar system. As the planet transits the rapidly rotating host star, it successively blocks regions of the stellar disk with different radial velocities, causing a “bump” in the stellar spectral line shape, which we resolve spectroscopically. The manner in which this perturbation moves across the stellar line during the transit gives information on the relative alignment between the stellar spin and planetary orbital angular momentum vectors. This is a powerful statistical probe of planetary migration processes, as the expected spin-orbit misalignment distributions from dynamically cold migration (disk interactions) and dynamically hot migration (planet-planet scattering, Kozai cycles) are significantly different: the former will lead to primarily aligned orbits; the latter to a wide distribution. Doppler tomography also promises to be a powerful technique for confirming transiting planet candidates around rapidly rotating stars like Kepler-13A, which are not amenable to radial velocity follow-up and thus are currently a poorly sampled region of parameter space.
Carbon and Oxygen in the Spectrum of HR 8799c
Authors: Konopacky Q. M. , Barman T. S. , Macintosh B. A. , Marois C.
Published: January 2014

The field of exoplanet spectroscopy has grown tremendously in the last decade. With the discovery of gas giant planets at wide separations from their host stars via direct imaging, it is now possible to obtain exoplanet spectra with unprecedented spectral resolution. We present a medium resolution spectrum of the directly imaged exoplanet HR 8799c. This K-band spectrum was obtained using the integral field spectrograph OSIRIS on the Keck II telescope. Our spectrum shows numerous, well-resolved molecular lines from water and carbon monoxide (CO). There is no clear evidence for methane absorption, in spite of a best fit temperature of ~1100 K. We find a best fit surface gravity log(g) ~ 4.0, consistent with the inferred young age for the system (~30 Myr), and a continuum morphology consistent with previously-inferred dust clouds. Using the water and CO lines, we are able to estimate the C/O ratio for this planet. We find a ratio slightly higher than stellar (~0.65), which provides hints about the planet's formation.
Dectection of Thermal Emission from WASP-3b
Authors: Rostron J. W. , Wheatley P. J.
Published: January 2014

We report secondary eclipse detections of the transiting hot Jupiter WASP-3b at 3.6, 4.5 and 8.0μm using the Spitzer Space Telescope's Infrared Array Camera. We find planet-to-star flux ratios of 0.210+0.043−0.029, 0.281+0.012−0.011 and 0.332+0.050−0.034% in the three bands respectively. Comparisons with 1D atmospheric models show these values strongly favour inefficient redistribution of heat around the planet and also favour the presence of a temperature inversion. In addition, WASP-3 probes the cut-off region of a proposed activity-inversion correlation and we find evidence of atmospheric differences between this system and a similarly active system, WASP-4.
Two Giant Planets Orbiting the K Giant Star η Cet
Authors: Trifonov T. , Reffert S. , Tan X. , Lee M. H. , Quirrenbach A.
Published: January 2014

We present evidence of a new planetary system around the K giant η Cet (HIP 5364, HD 6805, HR 334), based on 124 high-precision optical and infrared radial velocity data, taken at Lick Observatory (Hamilton) and at VLT (CRIRES). The best dynamical fit to the data is consistent with two massive planets (m1sini≈2.6MJup, m2sini≈3.3MJup) and with periods of P1≈407 days, P2≈740 days. To test the η Cet system's stability we perform ~ 10,000 dynamical investigations with maximum time spans of 108 years. We find that in case of moderate eccentricities, the planets can be effectively trapped in an anti-aligned stable 2:1 mean motion resonance (MMR), very close to the separatrix. A larger non-resonant stable region exists in low-eccentricity parameter space, although less probable than the 2:1 MMR region.
‘Dust around Nearby Stars’ The Survey Observational Results
Authors: Marshall Jonathan P.
Published: January 2014

In this conference proceedings we summarize the key observational findings of the Herschel DUNES survey. We found 31 discs in our sample, equating to an increased dust incidence with Herschel of 20.2 ±2.0% compared to previous measurement of ~12.5±5% with Spitzer for the same population of nearby, Sun-like stars. We identify no trend towards fewer discs around later spectral types, as had previously been reported for A-M stars. Around half of the discs exhibit extended emission, representing a vast improvement in the number of spatially resolved debris discs and thereby the quality of modelling that can be applied to those systems. We also identify unusual sub-groups of discs, including ‘steep SED’ sources with dust spectral indexes in the 70–160 μm range, steeper than the Rayleigh-Jeans tail which, whilst not unheard of, are more typically seen at sub-mm wavelengths and candidate ‘cold discs’ which are identified through their lack of significant excess emission at wavelengths shorter than 100 μm.
Searching for Faint Exozodiacal Disks: Keck Results and LBTI Status
Authors: Defrère D. , Hinz P. , Mennesson B. , Millan-Gabet R. , Skemer A. , Bailey V. , Rodigas T.J.
Published: January 2014

The possible presence of dust in the habitable zone around nearby main-sequence stars is considered as a major hurdle toward the direct imaging of Earth-like extrasolar planets with future dedicated space-based telescopes (e.g., Roberge et al. 2012). In this context, NASA has funded two ground-based mid-infrared nulling interferometers to combine the large apertures available at the Keck Observatory and the Large Binocular Telescope (LBT). In this poster, we present the preliminary results of the extended survey carried out with the Keck Interferometer Nuller (KIN) between 2008 and 2011 and describe the forthcoming LBTI survey.
Debris Disks and Multiplicity within the 75pc Volume-limited A-Star (VAST) Survey
Authors: De Rosa R. J. , Smith B. , Bulger J. , Patience J. , Marois C. , Song I. , Macintosh B. , Graham J. , Doyon R. , Bessell M.
Published: January 2014

We present the preliminary findings of an investigation of the multiplicity of debris disk stars identified within our Volume-limited A-star (VAST) multiplicity survey. Previous studies have produced conflicting results regarding the multiplicity fraction of debris disk-hosting stars compared with non-excess stars. By combining our large-scale volume-limited AO survey of A-type stars with the all-sky WISE catalogue, we have investigated the frequency of binary companions to a large sample of A-type stars with and without measured 22μm excess. The results of this study will allow for a greater understanding of the interaction between a companion star and a circumstellar debris disk, informing future study into the formation and stability of planetary-mass companions within binary systems.
Eccentricity Dependence on Iron Abundance
Authors: Taylor Stuart F.
Published: January 2014

The occurrence and eccentricity distribution of planets as a function of period is significantly different for iron-rich and iron-poor planet systems. We find that iron-poor stars with planets having periods between 525 and 600 days have higher eccentricity than such systems outside this range. If whole planet pollution causes the correlation of giant planet eccentricity with stellar iron abundance, then this cluster could be due to a paucity of pollution in this period range. Newly reported patterns of planet occurrence must result from planet system architectural features such as the snow line, followed by subsequent migration. Different results favor pollution or higher initial iron abundance causing the higher occurrence fraction of giant planets hosted by iron-rich stars, but the two explanations could be complementary. Relations between planet and stellar parameters are a major product of planet-finding, which promise further insights into star-planet system formation and evolution. Collaborators are sought to study these patterns. We expect a spirited debate over the relative contributions of initial abundances, disk accretion, and whole planet accretion.
Magnetism and the Invisible Man: The mysteries of coronal cavities
Authors: Gibson Sarah
Published: January 2014

Magnetism defines the complex and dynamic solar corona. Twists and tangles in coronal magnetic fields build up energy and ultimately erupt, hurling plasma into interplanetary space. These coronal mass ejections (CMEs) are transient riders on the ever-outflowing solar wind, which itself possesses a three-dimensional morphology shaped by the global coronal magnetic field. Coronal magnetism is thus at the heart of any understanding of the origins of space weather at the Earth. However, we have historically been limited by the difficulty of directly measuring the magnetic fields of the corona, and have turned to observations of coronal plasma to trace out magnetic structure. This approach is complicated by the fact that plasma temperatures and densities vary among coronal magnetic structures, so that looking at any one wavelength of light only shows part of the picture. In fact, in some regimes it is the lack of plasma that is a significant indicator of the magnetic field. Such a case is the coronal cavity: a dark, elliptical region in which strong and twisted magnetism dwells. I will elucidate these enigmatic features by presenting observations of coronal cavities in multiple wavelengths and from a variety of observing vantages, including unprecedented coronal magnetic field measurements now being obtained by the Coronal Multichannel Polarimeter (CoMP). These observations demonstrate the presence of twisted magnetic fields within cavities, and also provide clues to how and why cavities ultimately erupt as CMEs.
Large-amplitude longitudinal oscillations in solar prominences
Authors: Luna Manuel , Karpen Judith , Díaz Antonio , Knizhnik Kalman , Muglach Karin , Gilbert Holly , Kucera Therese
Published: January 2014

Large-amplitude longitudinal (LAL) prominence oscillations consist of periodic mass motions along a filament axis. The oscillations appear to be triggered by an energetic event, such as a microflare, subflare, or small C-class flare, close to one end of the filament. Observations reveal speeds of several tens to 100 km/s, periods of order 1 hr, damping times of a few periods, and displacements equal to a significant fraction of the prominence length. We have developed a theoretical model to explain the restoring force and the damping mechanism. Our model demonstrates that the main restoring force is the projected gravity in the flux tube dips where the threads oscillate. Although the period is independent of the tube length and the constantly growing mass, the motions are strongly damped by the steady accretion of mass onto the threads. We conclude that the LAL movements represent a collective oscillation of a large number of cool, dense threads moving along dipped flux tubes, triggered by a nearby energetic event. Our model yields a powerful seismological method for constraining the coronal magnetic field strength and radius of curvature at the thread locations.
Unusual migration of the prominence activities in recent solar cycles
Authors: Shimojo Masumi
Published: January 2014

We investigated the prominence eruptions and disappearances observed with the Nobeyama Radioheliograph during over 20 years for studying the anomaly of the recent solar cycle. Although the sunspot number of Cycle 24 is smaller than the previous one dramatically, the occurrence rate, size and radial velocity of the prominence activities are not changed significantly. We also found that the occurrence of the prominence activities in the northern hemisphere is normal from the duration of the cycle and the migration of the producing region of the prominence activities. On the other hand, the migration in the southern hemisphere significantly differs from that in the northern hemisphere and the previous cycles. Our results suggest that the anomalies of the global magnetic field distribution started at the solar maximum of Cycle 23.
The physical mechanisms that initiate and drive solar eruptions
Authors: Aulanier Guillaume
Published: January 2014

Solar eruptions are due to a sudden destabilization of force-free coronal magnetic fields. But the detailed mechanisms which can bring the corona towards an eruptive stage, then trigger and drive the eruption, and finally make it explosive, are not fully understood. A large variety of storage-and-release models have been developed and opposed to each other since 40 years. For example, photospheric flux emergence vs. flux cancellation, localized coronal reconnection vs. large-scale ideal instabilities and loss of equilibria, tether-cutting vs. breakout reconnection, and so on. The competition between all these approaches has led to a tremendous drive in developing and testing all these concepts, by coupling state-of-the-art models and observations. Thanks to these developments, it now becomes possible to compare all these models with one another, and to revisit their interpretation in light of their common and their different behaviors. This approach leads me to argue that no more than two distinct physical mechanisms can actually initiate and drive prominence eruptions: themagnetic breakoutand thetorus instability. In this view, all other processes (including flux emergence, flux cancellation, flare reconnection and long-range couplings) should be considered as various ways that lead to, or that strengthen, one of the aforementioned driving mechanisms.
3D reconstruction of erupting filaments with STEREO data
Authors: Li Ting , Zhang Jun
Published: January 2014

The launch of STEREO spacecraft in October 2006 provided an opportunity to view filament eruptions from two viewpoints giving new insights into their three-dimensional (3D) geometry and true trajectory. The kinematical parameters (velocity and acceleration vectors), the rotation motion, non-radial motion and the helical twist around the filament axis in 3D space have been obtained for the first time. All these properties of erupting filaments are very important to our understanding of the physical phenomena triggering the eruption and their early evolution. In the present paper we review different reconstruction techniques of erupting filaments and the main results obtained using the STEREO observations.
A solar tornado caused by flares
Authors: Panesar N. K. , Innes D. E. , Tiwari S. K. , Low B. C.
Published: January 2014

An enormous solar tornado was observed by SDO/AIA on 25 September 2011. It was mainly associated with a quiescent prominence with an overlying coronal cavity. We investigate the triggering mechanism of the solar tornado by using the data from two instruments: SDO/AIA and STEREO-A/EUVI, covering the Sun from two directions. The tornado appeared near to the active region NOAA 11303 that produced three flares. The flares directly influenced the prominence-cavity system. The release of free magnetic energy from the active region by flares resulted in the contraction of the active region field. The cavity, owing to its superior magnetic pressure, expanded to fill this vacated space in the corona. We propose that the tornado developed on the top of the prominence due to the expansion of the prominence-cavity system.
The promise of Bayesian analysis for prominence seismology
Authors: Arregui Iñigo , Ramos Andrés Asensio , Díaz Antonio J.
Published: January 2014

We propose and use Bayesian techniques for the determination of physical parameters in solar prominence plasmas, combining observational and theoretical properties of waves and oscillations. The Bayesian approach also enables to perform model comparison to assess how plausible alternative physical models/mechanisms are in view of data.
Estimation of Plasma Properties and Magnetic Field in a Prominence-like Structure as Observed by SDO/AIA
Authors: Dwivedi B. N. , Srivastava A. K. , Mohan Anita
Published: January 2014

We analyze a prominence-like cool plasma structure as observed by Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We perform the Differential Emission Measure (DEM) analysis using various filters of AIA, and also deduce the temperature and density structure in and around the observed flux-tube. In addition to deducing plasma parameters, we also find an evidence of multiple harmonics of fast magnetoacoustic kink waves in the observed prominence-like magnetic structure. Making use of estimated plasma parameters and observed wave parameters, under the baseline of MHD seismology, we deduce magnetic field in the flux-tube. The wave period ratio P1/P2 = 2.18 is also observed in the flux-tube, which carries the signature of magnetic field divergence where we estimate the tube expansion factor as 1.27. We discuss constraints in the estimation of plasma and magnetic field properties in such a structure in the current observational perspective, which may shed new light on the localized plasma dynamics and heating scenario in the solar atmosphere.
Kappa-distributions and Temperature Structure of the Prominence-Corona Transition Region
Authors: Dzifčáková Elena , Mackovjak Šimon , Heinzel Petr
Published: January 2014

The influence of the electron κ - distributions on the differential emission measure (DEM) of the prominence-corona transition region (PCTR) derived from observed line intensities has been investigated. An important consequence of the κ - distribution is formation of the emission lines in much wider temperature ranges. The implications for the formation temperature of the observed SDO/AIA band emissions are shown.
Observational Study of Large Amplitude Longitudinal Oscillations in a Solar Filament
Authors: Knizhnik Kalman , Luna Manuel , Muglach Karin , Gilbert Holly , Kucera Therese , Karpen Judith
Published: January 2014

On 20 August 2010 an energetic disturbance triggered damped large-amplitude longitudinal (LAL) oscillations in almost an entire filament. In the present work we analyze this periodic motion in the filament to characterize the damping and restoring mechanism of the oscillation. Our method involves placing slits along the axis of the filament at different angles with respect to the spine of the filament, finding the angle at which the oscillation is clearest, and fitting the resulting oscillation pattern to decaying sinusoidal and Bessel functions. These functions represent the equations of motion of a pendulum damped by mass accretion. With this method we determine the period and the decaying time of the oscillation. Our preliminary results support the theory presented by Luna and Karpen (2012) that the restoring force of LAL oscillations is solar gravity in the tubes where the threads oscillate, and the damping mechanism is the ongoing accumulation of mass onto the oscillating threads. Following an earlier paper, we have determined the magnitude and radius of curvature of the dipped magnetic flux tubes hosting a thread along the filament, as well as the mass accretion rate of the filament threads, via the fitted parameters.
Coronal Condensation in Funnel Prominences as Return Flows of the Chromosphere-Corona Mass Cycle
Authors: Liu Wei , Berger Thomas E. , Low B. C.
Published: January 2014

We present SDO/AIA observations of a potentially novel type of prominence, called “funnel prominence”, that forms out of coronal condensation at magnetic dips.

They can drain a large amount of mass (up to ~1015 g day−1) and may play an important role as return flows of the chromosphere-corona mass cycle.
Column Density Measurements of a Prominence Observed by AIA
Authors: McCauley Patrick I. , Su Yingna , DeLuca Edward , van Ballegooijen Adriaan
Published: January 2014

We present column density measurements of a polar crown prominence observed on March 9th, 2012 by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory. The structure was viewed on the east limb by AIA and erupted about 30 hours after the observations shown here. We estimate column density by approximating the obscured background emission to obtain an optical depth. This can then be combined with the absorption cross sections of neutral hydrogen and helium, along with the He:H abundance ratio, to calculate column density. We perform this calculation for the 171, 193, 211, and 335 Å AIA passbands.
HMI observations of two types of ephemeral regions
Authors: Yang Shuhong , Zhang Jun , Liu Yang
Published: January 2014

Using the magnetograms observed with the Helioseismic and Magnetic Imager, we statistically study the ephemeral regions (ERs) of the Sun. we notice that the areas with locations around S15° and N25° have larger ER number density, implying that the generation of ERs may be affected by the large-scale background fields from dispersed active regions. According to their evolution, the ERs can be classified into two types, i.e., normal ERs (2798 ones) and self-canceled ERs (190 ones). Submergence of initial magnetic flux loops connecting the opposite dipolar polarities may lead to the self-cancellation.
Characterization of intermittent structures in the solar wind
Authors: Nakwacki M. S. , Ruiz M. E. , Dasso S.
Published: January 2014

The solar wind (SW) is a suitable natural scenario to study the intermittent nature of magnetohydrodynamic (MHD) turbulence for systems with low dissipation rate. In particular, nonlinear wave-wave interactions can be characterized by the degree of phase correlation and by departures from Gaussianity of the magnetic field. In this work, we study in situ observations of magnetic field intensity from the spacecraft ACE, which is located near one astronomical unit from the Sun, in the SW near Earth. We compute the phase coherence index analyzing two sets of observations, each one consisting of approximately three months during 2008 and 2012, respectively. From these sets of data we characterize intermittent features of the magnetic field intensity corresponding to a solar maximum and a solar minimum.
Magnetic reconnection driven by filament eruption in the 7 June 2011 event
Authors: van Driel-Gesztelyi L. , Baker D. , Török T. , Pariat E. , Green L. M. , Williams D. R. , Carlyle J. , Valori G. , Démoulin P. , Matthews S. A. , Kliem B. , Malherbe J.-M.
Published: January 2014

During an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.
Diversity and methane oxidation of active epibiotic methanotrophs on live Shinkaia crosnieri
Authors: Watsuji Tomo-o , Yamamoto Asami , Takaki Yoshihiro , Ueda Kenji , Kawagucci Shinsuke , Takai Ken
Published: January 2014

Shinkaia crosnieri is a galatheid crab that predominantly dwells in deep-sea hydrothermal systems in the Okinawa Trough, Japan. In this study, the phylogenetic diversity of active methanotrophs in the epibiotic microbial community on the setae of S. crosnieri was characterized by reverse transcription-polymerase chain reaction (RT-PCR) of a functional gene (pmoA) encoding a subunit of particulate methane monooxygenase. Phylogenetic analysis of pmoA transcript sequences revealed that the active epibiotic methanotrophs on S. crosnieri setae consisted of gammaproteobacterial type Ia and Ib methanotrophs. The effect of different RNA stabilization procedures on the abundance of pmoA and 16S rRNA transcripts in the epibiotic community was estimated by quantitative RT-PCR. Our novel RNA fixation method performed immediately after sampling effectively preserved cellular RNA assemblages, particularly labile mRNA populations, including pmoA mRNA. Methane consumption in live S. crosnieri was also estimated by continuous-flow incubation under atmospheric and in situ hydrostatic pressures, and provided a clear evidence of methane oxidation activity of the epibiotic microbial community, which was not significantly affected by hydrostatic pressure. Our study revealed the significant ecological function and nutritional contribution of epibiotic methanotrophs to the predominant S. crosnieri populations in the Okinawa Trough deep-sea hydrothermal systems. In conclusion, our study gave clear facts about diversity and methane oxidation of active methanotrophs in the epibiotic community associated with invertebrates.
Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus
Authors: Pittera Justine , Humily Florian , Thorel Maxine , Grulois Daphné , Garczarek Laurence , Six Christophe
Published: January 2014

Marine Synechococcus cyanobacteria constitute a monophyletic group that displays a wide latitudinal distribution, ranging from the equator to the polar fronts. Whether these organisms are all physiologically adapted to stand a large temperature gradient or stenotherms with narrow growth temperature ranges has so far remained unexplored. We submitted a panel of six strains, isolated along a gradient of latitude in the North Atlantic Ocean, to long- and short-term variations of temperature. Upon a downward shift of temperature, the strains showed strikingly distinct resistance, seemingly related to their latitude of isolation, with tropical strains collapsing while northern strains were capable of growing. This behaviour was associated to differential photosynthetic performances. In the tropical strains, the rapid photosystem II inactivation and the decrease of the antioxydant β-carotene relative to chl a suggested a strong induction of oxidative stress. These different responses were related to the thermal preferenda of the strains. The northern strains could grow at 10 °C while the other strains preferred higher temperatures. In addition, we pointed out a correspondence between strain isolation temperature and phylogeny. In particular, clades I and IV laboratory strains were all collected in the coldest waters of the distribution area of marine Synechococus. We, however, show that clade I Synechococcus exhibit different levels of adaptation, which apparently reflect their location on the latitudinal temperature gradient. This study reveals the existence of lineages of marine Synechococcus physiologically specialised in different thermal niches, therefore suggesting the existence of temperature ecotypes within the marine Synechococcus radiation.
Substrate-induced Band Gap Renormalization in Semiconducting Carbon Nanotubes
Authors: Lanzillo Nicholas A. , Kharche Neerav , Nayak Saroj K.
Published: January 2014

The quasiparticle band gaps of semiconducting carbon nanotubes (CNTs) supported on a weakly-interacting hexagonal boron nitride (h-BN) substrate are computed using density functional theory and the GW Approximation. We find that the direct band gaps of the (7,0), (8,0) and (10,0) carbon nanotubes are renormalized to smaller values in the presence of the dielectric h-BN substrate. The decrease in the band gap is the result of a polarization-induced screening effect, which alters the correlation energy of the frontier CNT orbitals and stabilizes valence band maximum and conduction band minimum. The value of the band gap renormalization is on the order of 0.25 to 0.5 eV in each case. Accounting for polarization-induced band gap changes is crucial in comparing computed values with experiment, since nanotubes are almost always grown on substrates.
Parametrically Amplified Bright-state Polariton of Four- and Six-wave Mixing in an Optical Ring Cavity
Authors: Chen Haixia , Zhang Yiqi , Yao Xin , Wu Zhenkun , Zhang Xun , Zhang Yanpeng , Xiao Min
Published: January 2014

We report experimental studies of bright-state polaritons of four-wave mixing (FWM) and six-wave mixing (SWM) signals through cascade nonlinear optical parametric amplification processes in an atom-cavity composite system for the first time. Also, the coexisting cavity transmission modes of parametrically amplified FWM and SWM signals are observed. Finally, electromagnetically induced absorption by the FWM cavity modes in the probe beam is investigated. The investigations can find potential applications in multi-channel narrow-band long-distance quantum communication.
Label-free and real-time monitoring of trypsin activity in living cells by quantum-dot-based fluorescent sensors
Authors: Zhang Wenzhu , Zhang Ping , Zhang Shengzhou , Zhu Changqing
Published: January 2014

A quantum-dot-based fluorescence turn-on sensor was used for label-free and real-time monitoring of trypsin activity.
A facile colorimetric assay for determination of salicylic acid in tobacco leaves using titanium dioxide nanoparticles
Authors: Tseng Po-Jen , Wang Chiung-Yi , Huang Tzu-Yun , Chuang Yuan-Yu , Fu Shih-Feng , Lin Yang-Wei
Published: January 2014

Colorimetric sensing of salicylic acid in tobacco leavesin situusing TiO2NPs.
Nanoscale semiconductor devices as new biomaterials
Authors: Zimmerman John , Parameswaran Ramya , Tian Bozhi
Published: January 2014

Nanostructured semiconductor materials and devices hold great promise as unique biomaterials to advance biophysics, biology and medicine.
Effect of robust π–π stacking synthon on the formation of mercury coordination compounds; an unusual pseudo-square planar geometry
Authors: Khavasi Hamid Reza , Mir Mohammad Sadegh Bahareh
Published: January 2014

In this study, three Hg(ii) complexes, [HgCl2(L2-naph)]n, 1, [HgBr2(L2-naph)]n, 2 and [HgI2(L2-naph)2], 3 where L2-naph is N-(naphthalene-2-yl)pyrazine-2-carboxamide ligand have been synthesized and characterized.
Discovering Ce-rich oxygen evolution catalysts, from high throughput screening to water electrolysis
Authors: Haber Joel A. , Cai Yun , Jung Suho , Xiang Chengxiang , Mitrovic Slobodan , Jin Jian , Bell Alexis T. , Gregoire John M.
Published: January 2014

We report a new Ce-rich family of active oxygen evolution reaction (OER) catalysts composed of earth abundant elements, discovered using high-throughput methods.
Silicone passive equilibrium samplers as ‘chemometers’ in eels and sediments of a Swedish lake
Authors: Jahnke Annika , Mayer Philipp , McLachlan Michael S. , Wickström Håkan , Gilbert Dorothea , MacLeod Matthew
Published: January 2014

The potential of passive equilibrium sampling to study the thermodynamic controls on persistent organic chemicals in the environment is illustrated for bioaccumulation of HCB and PCBs in a Swedish lake.
Electrocarboxylation of acetophenone in ionic liquids: the influence of proton availability on product distribution
Authors: Zhao Shu-Feng , Horne Mike , Bond Alan M. , Zhang Jie
Published: January 2014

High-yield electrocarboxylation of acetophenone can be achieved in dry [BMPyrd][TFSI].
Transcriptionally correlated subcellular dynamics of MBNL1 during lens development and their implication for the molecular pathology of myotonic dystrophy type 1
Authors: Coleman Stewart M. , Prescott Alan R. , Sleeman Judith E.
Published: January 2014

DM1 (myotonic dystrophy type 1) is caused by elongation of a CTG repeat in the DMPK (dystrophia myotonica-protein kinase) gene. mRNA transcripts containing these CUGexp (CUG expansion) repeats form accumulations, or foci, in the nucleus of the cell. The pathogenesis of DM1 is proposed to result from inappropriate patterns of alternative splicing caused by sequestration of the developmentally regulated alternative splicing factor MBNL1 (muscleblind-like 1) by these foci. Since eye lens cataract is a common feature of DM1 we have examined the distribution and dynamics of MBNL1 in lens epithelial cell lines derived from patients with DM1. The results of the present study demonstrate that only a small proportion of nuclear MBNL1 accumulates in CUGexp pre-mRNA foci. MBNL1 is, however, highly mobile and changes localization in response to altered transcription and splicing activity. Moreover, immunolocalization studies in lens sections suggest that a change in MBNL1 distribution is important during lens growth and differentiation. Although these data suggest that the loss of MBNL1 function due to accumulation in foci is an unlikely explanation for DM1 symptoms in the lens, they do demonstrate a strong relationship between the subcellular MBNL1 localization and pathways of cellular differentiation, providing an insight into the sensitivity of the lens to changes in MBNL1 distribution.
Ultra-thin L1-FePt for perpendicular anisotropy L1-FePt/Ag/[Co/Pd]30 pseudo spin valves
Authors: Ho Pin , Han Guchang , He Kaihua , Chow Gan Moog , Chen Jing-Sheng
Published: January 2014

Perpendicular anisotropy L10-FePt/Ag/[Co/Pd]30 pseudo spin valves (PSVs) with ultra-thin L10-FePt alloy free layer possessing high anisotropy and thermal stability have been fabricated and studied. The thickness of the L10-FePt layer was varied between 2 and 4 nm. The PSV became increasingly decoupled with reduced L10-FePt thickness due to the larger difference between the coercivity of the L10-FePt and [Co/Pd]30 films. The PSV with an ultra-thin L10-FePt free layer of 2 nm displayed a high Ku of 2.21 × 107 ergs/cm3, high thermal stability of 84 and a largest giant magnetoresistance of 0.54%.
Tunnel magnetoresistance effect using perpendicularly magnetized tetragonal and cubic Mn-Co-Ga Heusler alloy electrode
Authors: Kubota T. , Mizukami S. , Ma Q. L. , Naganuma H. , Oogane M. , Ando Y. , Miyazaki T.
Published: January 2014

Epitaxially grown tetragonal and cubic Mn-Co-Ga thin films were fabricated onto single crystalline Cr (001) under a layer. High perpendicular magnetic anisotropy is achieved in the tetragonal Mn2.3Co0.4Ga1.3 film, and a small, unexpected perpendicular magnetic anisotropy was induced in the cubic Mn1.8Co1.2Ga1.0 film as well. The tunnel magnetoresistance (TMR) effect of the Mn-Co-Ga/MgO/CoFeB magnetic tunnel junctions (MTJs) were investigated. TMR ratios of 5% and 11% were observed at room temperature for the MTJs using tetragonal Mn2.3Co0.4Ga1.3 and cubic Mn1.8Co1.2Ga1.0 electrodes, respectively. The composition dependence is discussed briefly.
Songbird response to wildfire in mixed-conifer forest in south-western Oregon
Authors: Seavy Nathaniel E. , Alexander John D.
Published: January 2014

We used 1 year of pre-fire and 4 years of post-fire data to quantify changes in the occurrence of birds at burned and unburned sites in a southern Oregon watershed after a 2500-ha wildfire. Our objectives were to identify bird species that increased or decreased as a result of this mixed-severity fire. Of the 27 species we investigated, we found evidence for fire-induced changes in the proportion of sites occupied by 13 species. Of these, most (8 species) were species that occurred at fewer sites after the fire than before. These changes were consistent with changes in vegetation composition, which included a decrease in the cover of conifer species and an increase in the cover of broadleaf species. To evaluate the effect of the fire on other ecological conditions, we compared the abundance of nest predators and potential prey items (arthropod biomass) between burned and unburned areas in the 3rd and 4th years after the fire. We found little evidence that the abundance of nest predators differed between burned and unburned areas in either year. There was, however, substantial spatial and temporal variation in arthropod abundance. Hemipteran and coleopteran biomass was greater in burned areas in both the 3rd and 4th year after the fire, and overall arthropod biomass was greater in the 4th year after the fire. The spatial and temporal variability in the bird response to this fire illustrates the importance of before–after–control–impact and multi-year studies for understanding the effects of large-scale disturbances on avian community composition.
The fate of the primary cilium during myofibroblast transition
Authors: Rozycki Matthew , Lodyga Monika , Lam Jessica , Miranda Maria Zena , Fátyol Károly , Speight Pam , Kapus András
Published: January 2014

Myofibroblasts, the culprit of organ fibrosis, can originate from mesenchymal and epithelial precursors through fibroblast–myofibroblast and epithelial–myofibroblast transition (EMyT). Because certain ciliopathies are associated with fibrogenesis, we sought to explore the fate and potential role of the primary cilium during myofibroblast formation. Here we show that myofibroblast transition from either precursor results in the loss of the primary cilium. During EMyT, initial cilium growth is followed by complete deciliation. Both EMyT and cilium loss require two-hit conditions: disassembly/absence of intercellular contacts and transforming growth factor-β1 (TGFβ) exposure. Loss of E-cadherin–dependent junctions induces cilium elongation, whereas both stimuli are needed for deciliation. Accordingly, in a scratch-wounded epithelium, TGFβ provokes cilium loss exclusively along the wound edge. Increased contractility, a key myofibroblast feature, is necessary and sufficient for deciliation, since constitutively active RhoA, Rac1, or myosin triggers, and down-regulation of myosin or myocardin-related transcription factor prevents, this process. Sustained myosin phosphorylation and consequent deciliation are mediated by a Smad3-, Rac1-, and reactive oxygen species–dependent process. Transitioned myofibroblasts exhibit impaired responsiveness to platelet-derived growth factor-AA and sonic hedgehog, two cilium-associated stimuli. Although the cilium is lost during EMyT, its initial presence contributes to the transition. Thus myofibroblasts represent a unique cilium-less entity with profoundly reprogrammed cilium-related signaling.
Cardiovascular Medication Use Following Percutaneous Coronary Intervention: The Australian Experience
Authors: Cole Justin A. , Brennan Angela L. , Ajani Andrew E. , Yan Bryan P. , Duffy Stephen J. , Loane Philippa , Reid Christopher M. , Yudi Matias B. , New Gishel , Black Alexander , Shaw James , Clark David J. , Andrianopoulos Nick
Published: January 2014

Aims

Despite the guidelines, a “treatment gap” exists in the delivery of pharmacotherapy for secondary prevention. We aimed to analyze the trend in guideline‐based medication usage following percutaneous coronary intervention (PCI) using the Melbourne Interventional Group (MIG) registry over a 6‐year period (2005–2010).

Methods

The MIG registry prospectively collects demographical, clinical, and procedural characteristics of consecutive patients undergoing PCI. We assessed medication use (aspirin, clopidogrel, ACE inhibitors, angiotensin receptor blockers, beta‐blockers, and lipid‐lowering agents) at 30 days and 12 months in patients alive and able to provide the information.

Results

The cohort consists of 12,813 patients who underwent 14,787 consecutive interventional procedures. They comprised 76% males: 22% were elderly (≥75 years), 23% had diabetes, 2% had severe renal impairment, 2% had severe left ventricular dysfunction, 26% presented with STEMI, and 44% of patients received drug‐eluting stent. Follow‐up was complete for 97.8% of the cohort at 30 days (2.2% mortality) and 89.1% at 12 months (4% mortality). From 2005 to 2010, the percentage of patients taking all five classes of medications increased each year. In 2010 at 30 days, nearly 60% of patients took all five classes of medications, and by 12 months, 75% of patients were taking four or five classes of medications.

Conclusion

In conclusion, while the increasing use of cardiovascular medicines in an “at‐risk” Australian cohort is encouraging, a treatment gap appears to still exist.
Donation After Cardiac Death and the Emergency Department: Ethical Issues
Authors: Simon Jeremy R. , Schears Raquel M. , Padela Aasim I.
Published: January 2014

Organ donation after cardiac death (DCD) is increasingly considered as an option to address the shortage of organs available for transplantation, both in the United States and worldwide. The procedures for DCD differ from procedures for donation after brain death and are likely less familiar to emergency physicians (EPs), even as this process is increasingly involving emergency departments (EDs). This article explores the ED operational and ethical issues surrounding this procedure.
Retrospective Analysis of Etomidate Versus Ketamine for First‐pass Intubation Success in an Academic Emergency Department
Authors: Patanwala Asad E. , McKinney Courtney B. , Erstad Brian L. , Sakles John C.
Published: January 2014

Objectives

The objective of this study was to compare first‐pass intubation success between patients who received etomidate versus ketamine for rapid sequence intubation (RSI) in the emergency department (ED).

Methods

This was a retrospective analysis of prospectively collected data recorded in a quality improvement database between July 1, 2007, and December 31, 2012. The study was conducted in an academic ED in the United States. All patients who received etomidate or ketamine as part of RSI were included. The primary outcome measure was first‐pass success. A multivariate analysis was conducted to determine if sedative type was associated with first‐pass success, after adjusting for potential confounders and baseline differences.

Results

The final cohort consisted of 2,098 RSI procedures using either etomidate (n = 1,983) or ketamine (n = 115). First‐pass success occurred in 77.0% of patients in the etomidate group and 79.1% of patients in the ketamine group (difference = –2.1%; 95% CI = –5.5% to 9.8%). In the multivariate analysis, after adjusting for potential confounders, sedative type was not associated with first‐pass success (odds ratio = 0.89; 95% CI = 0.5 to 1.5; p = 0.632).

Conclusions

Etomidate and ketamine are associated with equivalent first‐pass success when used in RSI. Ketamine may be an appropriate alternative to etomidate for RSI in the ED.
Economic analysis comparing induction of labor and expectant management in women with preterm prelabor rupture of membranes between 34 and 37 weeks (PPROMEXIL trial)
Authors: Vijgen Sylvia M. C. , van der Ham David P. , Bijlenga Denise , van Beek Johannes J. , Bloemenkamp Kitty W. M. , Kwee Anneke , Groenewout Mariët , Kars Michael M. , Kuppens Simone , Mantel Gerald , Molkenboer Jan F. M. , Mulder Antonius L. M. , Nijhuis Jan G. , Pernet Paula J. M. , Porath Martina , Woiski Mallory D. , Weinans Martin J. N. , van Wijngaarden Wim J. , Wildschut Hajo I. J. , Akerboom Bertina , Sikkema J. Marko , Willekes Christine , Mol Ben W. J. , Opmeer Brent C. ,   The PPROMEXIL study group
Published: January 2014

Objective

To compare the costs of induction of labor and expectant management in women with preterm prelabor rupture of membranes (PPROM).

Design

Economic analysis based on a randomized clinical trial.

Setting

Obstetric departments of eight academic and 52 non‐academic hospitals in the Netherlands.

Population

Women withPPROMnear term who were not in labor 24 h afterPPROM.

Methods

A cost‐minimization analysis was done from a health care provider perspective, using a bottom‐up approach to estimate resource utilization, valued with unit‐costs reflecting actual costs.

Main outcome measures

Primary health outcome was the incidence of neonatal sepsis. Direct medical costs were estimated from start of randomization to hospital discharge of mother and child.

Results

Induction of labor did not significantly reduce the probability of neonatal sepsis [2.6% vs. 4.1%, relative risk 0.64 (95% confidence interval 0.25–1.6)]. Mean costs per woman were €8094 for induction and €7340 for expectant management (difference €754; 95% confidence interval −335 to 1802). This difference predominantly originated in the postpartum period, where the mean costs were €5669 for induction vs. €4801 for expectant management. Delivery costs were higher in women allocated to induction than in women allocated to expectant management (€1777 vs. €1153 per woman). Antepartum costs in the expectant management group were higher because of longer antepartum maternal stays in hospital.

Conclusions

In women with pregnancies complicated byPPROMnear term, induction of labor does not reduce neonatal sepsis, whereas costs associated with this strategy are probably higher.
Review article: the efficacy and safety of sofosbuvir, a novel, oral nucleotide NS5B polymerase inhibitor, in the treatment of chronic hepatitis C virus infection
Authors: Koff R. S.
Published: January 2014

Background

The treatment of chronic hepatitis C is changing rapidly.

Aim

To review clinical studies of the efficacy and safety of sofosbuvir‐containing regimens in the treatment of chronic hepatitis C.

Methods

Using PubMed and search terms ‘sofosbuvir,’ ‘emerging HCV treatment,’ and ‘HCV polymerase inhibitor,’ literature on the clinical development of sofosbuvir, as well as abstracts presented at the November 2013 annual meeting of the American Association for the Study of Liver Diseases (AASLD), was reviewed. The last search was undertaken on 15 November 2014.

Results

In a dose of 400 mg once daily, the drug has been safe and generally well tolerated with most adverse reactions attributable to the concurrent use of ribavirin or peginterferon plus ribavirin. A high barrier to resistance has been demonstrated. In genotype 1 (G1) patients, the addition of sofosbuvir to peginterferon plus ribavirin yielded sustained virological response rates at week 12 after discontinuation of treatment (SVR12) of about 90% with slightly lower levels in G1b and in patients with cirrhosis, but with no major impact of IL28B genotype, high viral load, body mass index (BMI), alanine aminotransferase (ALT) or race/ethnicity. In genotype 2 (G2), sofosbuvir and ribavirin for 12 weeks also resulted in SVR12 of 90% or better with little effect from cirrhosis. In contrast, genotype 3 (G3) was less responsive to 12 weeks of sofosbuvir plus ribavirin, especially in the presence of cirrhosis.

Conclusion

The efficacy and safety of sofosbuvir‐containing regimens with ribavirin alone or with peginterferon plus ribavirin signal a new era in treatment.