bluuebunny/crossref_metadata_2025 huggingface dataset:
Star-Planet Interaction: The Curious Case of the Planet Spoon-feeding Its Host Star (and Other Amenities)
Authors: Pillitteri Ignazio , Wolk S. J. , Maggio A. , Matsakos T.
Published: January 2016

We report two cases of Star-Planet Interaction (SPI) in two systems with hot Jupiters: HD 189733 and HD 17156. We used HST-COS to study the FUV variability of HD 189733 after the planetary eclipse. With the support of MHD simulations, we evince that material is likely evaporating from the planet and accreting onto the parent star. This produces a hot spot on the stellar surface, co-moving with the planetary motion and responsible of the X-ray and FUV variability at peculiar planetary phases. In HD 17156, which hosts a hot Jupiter in an eccentric orbit, we observed an enhancement of the X-ray activity at the passage of its planet at the periastron. The origin can be due to magnetic reconnection between the planetary and stellar magnetic fields, or due to material tidally stripped from the planet and accreting onto the star.
Rotation Periods of Nearby, Mid-to-late M Dwarfs from the MEarth Project
Authors: Newton Elisabeth R. , Irwin Jonathan , Charbonneau David , Berta-Thomspon Zachary K. , West Andrew A.
Published: January 2016

Field stars provide important constraints for the late stages of stars' angular momentum evolution. We measured rotation periods ranging from 0.1 to 150 days for approximately 450 mid-to-late M dwarfs using photometry from the MEarth transiting planet survey. We use parallaxes, proper motions, and radial velocities to calculate galactic kinematics for these solar neighborhood M dwarfs. The velocity dispersions increase towards longer rotation periods, indicating that there is a relationship between rotation and age for these stars.
HD 76582's Circumstellar Debris Disk
Authors: Marshall J. P.
Published: January 2016

The debris disk host star HD 76582 was observed at 450 μm and 850 μm as part of the JCMT/SCUBA-2 debris disk legacy survey ‘Sub-millimetre Observations of Nearby Stars’ (SONS). The sub-millimetre data are inconsistent with a disk undergoing a steady-state collisional cascade. Combining the sub-millimetre (sub-mm) measurements with mid- and far-infrared measurements from Spitzer and Herschel, we simultaneously model the disk's thermal emission and radial extent in a self-consistent manner.
Studying Young Stars with Large Spectroscopic Surveys
Authors: Martell Sarah L.
Published: January 2016

Galactic archaeology is the study of the history of star formation and chemical evolution in the Milky Way, based on present-day stellar populations. Studies of young stars are a key anchor point for Galactic archaeology, since quantities like the initial mass function and the star formation rate can be studied directly in young clusters and star forming regions. Conversely, massive spectroscopic Galactic archaeology surveys can be used as a data source for young star studies.
Magnetic Activity of Pre-main Sequence Stars near the Stellar-Substellar Boundary
Authors: Principe David , Kastner Joel. H. , Rodriguez David
Published: January 2016

X-ray observations of pre-main sequence (pre-MS) stars of M-type probe coronal emission and offer a means to investigate magnetic activity at the stellar-substellar boundary. Recent observations of main sequence (MS) stars at this boundary display a decrease in fractional X-ray luminosity (LX/Lbol) by almost two orders of magnitude for spectral types M7 and later. We investigate magnetic activity and search for a decrease in X-ray emission in the pre-MS progenitors of these MS stars. We present XMM-Newton X-ray observations and preliminary results for ~10 nearby (30-70 pc), very low mass pre-MS stars in the relatively unexplored age range of 10-30 Myr. We compare the fractional X-ray luminosities of these 10-30 Myr old stars to younger (1-3 Myr) pre-MS brown dwarfs and find no dependence on spectral type or age suggesting that X-ray activity declines at an age later than ~30 Myr in these very low-mass stars.
The Debris Disk Fraction for M-dwarfs in Nearby Young Moving Groups
Authors: Binks Alex
Published: January 2016

I present the first substantial work to measure the fraction of debris disks for M-dwarfs in nearby moving groups (MGs). Utilising the AllWISE IR catalog, 17 out of 151 MG members are found with an IR photometric excess indicative of disk structure. The M-dwarf debris disk fraction is ≲6 per cent in MGs younger than 40 Myr, and none are found in the groups older than 40 Myr. Simulations show, however, that debris disks around M-dwarfs are not present above a WISEW1-W4 colour of ~2.5, making calculating the absolute disk fractions difficult. The debris disk dissipation timescale appears to be faster than for higher-mass stars, and mechanisms such as enhanced stellar wind drag and/or photoevaporation could account for the more rapid decline of disks observed amongst M-dwarfs.
A Molecular Disk Survey of Low-Mass Stars in the TW Hya Association
Authors: Rodriguez David R. , van der Plas Gerrit , Kastner Joel H. , Schneider Adam C. , Faherty Jacqueline K. , Mardones Diego , Mohanty Subhanjoy , Principe David
Published: January 2016

We have carried out an ALMA Cycle 2 survey of 15 confirmed or candidate low-mass (<0.2M⊙) members of the TW Hya Association (TWA) with the goal of detecting line emission from CO molecular gas and continuum emission from cold dust. Our targets have spectral types of M4-L0 and hence represent the extreme low end of the TWA's mass function. The survey has yielded a detection of 12CO(2–1) emission around TWA 34. This newly discovered ~10 Myr-old molecular gas disk lies just ~50pc from Earth.
A Wide Angle Search for Hot Jupiters and Pre-Main Sequence Binaries in Young Stellar Associations
Authors: Oelkers Ryan J. , Macri Lucas M. , Marshall Jennifer L. , DePoy Darren L. , Colazo Carlos , Guzzo Pablo , Lambas Diego G. , Quiñones Ceci , Stringer Katelyn , Tapia Luis , Wisdom Colin
Published: January 2016

The past two decades have seen a significant advancement in the detection, classification and understanding of exoplanets and binary star systems. The vast majority of these systems consist of stars on the main sequence or on the giant branch, leading to a dearth of knowledge of properties at early times (<50 Myr). Only one transiting planet candidate and a dozen eclipsing binaries are known among pre-main sequence objects, yet these are the systems that can provide the best constraints on stellar and planetary formation models. We have recently completed a photometric survey of 3 young (<50 Myr), nearby (D<150 pc) moving groups with a small-aperture instrument, nicknamed “AggieCam”. We detected 7 candidate Hot Jupiters and over 200 likely pre-main sequence binaries, which are now being followed up photometrically and spectroscopically.
Modeling of a Giant Exoring System Around the Substellar Companion J1407b
Authors: Kenworthy Matthew A. , Mamajek Eric E.
Published: January 2016

We model the complex light curve of 1SWASP J140747.93-394542.6, a ~16 Myr old star in the Sco-Cen OB association, with a giant ring system that fills a significant fraction of the Hill sphere of an unseen secondary companion, J1407b. The best ring model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and the rings have an estimated total mass on the order of 1M⊕. The ring system has one clearly defined gap at 0.4 AU (61 million km), which we hypothesize is being cleared out by a < 0.8M⊕exosatellite orbiting around the secondary companion.
Two-temperature Debris Disks: Signposts for Directly Imaged Planets?
Authors: Kennedy Grant M. , Wyatt Mark C.
Published: January 2016

This work considers debris disks whose spectra can be modelled by dust emission at two different temperatures. These disks are typically assumed to be a sign of multiple belts, but only a few cases have been confirmed via high resolution observations. We derive the properties of a sample of two-temperature disks, and explore whether this emission can arise from dust in a single narrow belt. While some two-temperature disks arise from single belts, it is probable that most have multiple spatial components. These disks are plausibly similar to the outer Solar System's configuration of Asteroid and Edgeworth-Kuiper belts separated by giant planets. Alternatively, the inner component could arise from inward scattering of material from the outer belt, again due to intervening planets. For either scenario, the ratio of warm/cool component temperatures is indicative of the scale of outer planetary systems, which typically span a factor of about ten in radius.
Young Stars & Planets Near the Sun in 2015: Five Takeaways and Five Predictions
Authors: Liu Michael C.
Published: January 2016

I present a highly biased and skewed summary of IAU Symposium 314, “Young Stars and Planets Near the Sun,” held in May 2015. This summary includes some takeaway thoughts about the rapidly evolving state of the field, as well as some crowd-sourced predictions for progress over the next ~10 years. We predict the elimination of 1–2 of the currently recognized young moving groups, the addition of 3 or more new moving groups within 100 pc, the continued lack of a predictive theory of stellar mass, robust measurements of the gas and dust content of circumstellar disks, and an ongoing struggle to achieve a consensus definition for a planet.
A New, Young, Low-Mass Spectroscopic Binary Without a Home
Authors: Flagg Laura S. , Shkolnik Evgenya L. , Weinberger Alycia J. , Bowler Brendan P. , Kraus Adam L. , Liu Michael C.
Published: January 2016

We have discovered that 2MASS 08355977-3042306 is an accreting K7, double-lined, spectroscopic binary younger than ~20 Myr. The age of a dispersed young star can best be determined if it is a member of a known young moving group. However, the three dimensional space velocities (UVW) we calculate using radial velocity measurements, proper motions, and plausible photometric distances make membership in any known young moving group unlikely.
Cosmic Rays and the Origin of Volatiles in Protoplanetary Disks
Authors: Chaparro-Molano Germán , Kamp Inga
Published: January 2016

The origin of water and other volatiles in protoplanetary disks can be either interstellar or due to chemical processing during the protoplanetary disk phase. Depending on the strength of the ionization field present during this stage, an active chemical evolution in the protoplanetary disk midplane can lead to formation of complex volatiles on timescales shorter than the disk dissipation timescale. For this reason, we investigate the effects of cosmic rays and the usually neglected cosmic ray induced UV ionization field in time dependent chemical models of protoplanetary disks. These results are benchmarked against our current knowledge of the chemical composition of cometary ices. We conclude that water and other, more complex volatiles can be preserved in the ice mantles of dust grains. This ice mantle growth can also have a significant impact on the dust opacity and hence on the temperature profile of the disk midplane. This effect will be observable in the near future with ALMA.
Accretion, Disks, and Magnetic Activity in the TW Hya Association
Authors: Stelzer B. , Frasca A. , Alcalà J.M.
Published: January 2016

We present new photometric and spectroscopic data for the M-type members of the TW Hya association with the aim of a comprehensive study of accretion, disks and magnetic activity at the critical age of ~ 10 Myr where circumstellar matter disappears.
Mid-infrared Variability and Accretion in NGC 2264 Protostars
Authors: Terebey S. , Cody A. M. , Rebull L. M. , Stauffer J. R.
Published: January 2016

Variable mass accretion is thought to be an important aspect of protostar formation. Mid-infrared wavelength observations trace variations in accretion luminosity and thus can probe mass accretion on sub-AU scales. We present results from the Spitzer YSOVAR campaign towards Class I protostars in NGC 2264. The precise (0.02 mag) medium-cadence light curves at 3.6 and 4.5 microns show that young star variability is ubiquitous, with a variety of morphologies and time scales. A structure function analysis shows the light curves, on average, have a power-law behavior up to 30 days. The trend continues to longer timescales (years) for protostars (Class I), in contrast with the smaller brightness changes displayed by T Tauri stars (Class II). The power-law behavior suggests a stochastic process, such as turbulent mass accretion, drives the variability.
Comprehensive Census and Complete Characterization of Nearby Debris Disk Stars
Authors: Cotten Tara H. , Song Inseok
Published: January 2016

Debris disks are intimately linked to planetary system evolution since the rocky material surrounding the host stars is believed to be due to secondary generation from the collisions of planetesimals. With the conclusion and lack of future large scale infrared excess survey missions, it is time to summarize the history of using excess emission in the infrared as a tracer of debris and exploit all available data as well as provide a comprehensive study of the parameters of these important objects. We have compiled a catalog of infrared excess stars from peer-reviewed articles and performed an extensive search for new debris disks by cross-correlating the Tycho-2 and AllWISE catalogs. This study will conclude following the thorough examination of each debris disk star's parameters obtained through high-resolution spectroscopy at various facilities which is currently ongoing. We will maintain a webpage (www.debrisdisks.org) devoted to these infrared excess sources and provide various resources related to our catalog creation, SED fitting, and data reduction.
A Possible Dynamical History for the Fomalhaut System
Authors: Faramaz Virginie
Published: January 2016

Fomalhaut b was long thought to shape the eccentric debris belt in the Fomalhaut system, but its orbit was found to be too eccentric for it to be the dominant belt-shaping perturber. This indicates that Fomalhaut b is Earth-sized at most and that the belt-shaping perturber, hereafter named Fomalhaut c, remains to be discovered. In addition, since its orbit more or less crosses that of Fomalhaut b, it also indicates that the current configuration of the system is transient and was reached recently. In this talk, we show that this current configuration can be explained if Fomalhaut c is Saturn- to Neptune-sized, and Fomalhaut b originates from a mean-motion resonance with Fomalhaut c.
Photoevaporation and Disk Dispersal
Authors: Gorti Uma
Published: January 2016

Protoplanetary disks are depleted of their mass on short timescales by viscous accretion, which removes both gas and solids, and by photoevaporation which removes mainly gas. Photoevaporation may facilitate planetesimal formation by lowering the gas/dust mass ratio in disks. Disk dispersal sets constraints on planet formation timescales, and by controlling the availability of gas determines the type of planets that form in the disk. Photoevaporative wind mass loss rates are theoretically estimated to range from ~ 10−10 to 10−8M⊙, and disk lifetimes are typically ~ few Myr.
Gas Cavities inside Dust Cavities in Disks Inferred from ALMA Observations
Authors: van der Marel Nienke , van Dishoeck Ewine F. , Bruderer Simon , Pinilla Paola , van Kempen Tim , Perez Laura , Isella Andrea
Published: January 2016

Protoplanetary disks with cavities in their dust distribution, also named transitional disks, are expected to be in the middle of active evolution and possibly planet formation. In recent years, millimeter-dust rings observed by ALMA have been suggested to have their origin in dust traps, caused by pressure bumps. One of the ways to generate these is by the presence of planets, which lower the gas density along their orbit and create pressure bumps at the edge. We present spatially resolved ALMA Cycle 0 and Cycle 1 observations of CO and CO isotopologues of several famous transitional disks. Gas is found to be present inside the dust cavities, but at a reduced level compared with the gas surface density profile of the outer disk. The dust and gas emission are quantified using the physical-chemical modeling code DALI. In the majority of these disks we find clear evidence for a drop in gas density of at least a factor of 10 inside the cavity, whereas the dust density drops by at least a factor 1000. The CO isotopologue observations reveal that the gas cavities are significantly smaller than the dust cavities. These gas structures suggest clearing by one or more planetary-mass companions.
Gaia: The Astrometry Revolution
Authors: Sozzetti A. , Bonavita M. , Desidera S. , Gratton R. , Lattanzi M. G.
Published: January 2016

The power of micro-arcsecond (μas) astrometry is about to be unleashed. ESA's Gaia mission, now headed towards the end of the first year of routine science operations, will soon fulfil its promise for revolutionary science in countless aspects of Galactic astronomy and astrophysics. The potential of Gaia position measurements for important contributions to the astrophysics of planetary systems is huge. We focus here on the expectations for detection and improved characterization of ‘young’ planetary systems in the neighborhood of the Sun using a combination of Gaia μas astrometry and direct imaging techniques.
A Brief History of the Study of Nearby Young Moving Groups and Their Members
Authors: Kastner Joel H.
Published: January 2016

Beginning with the enigmatic (and now emblematic) TW Hya, the scutiny of individual stars and star-disk systems has both motivated and benefitted from the identification of nearby young moving groups (NYMGs). I briefly outline the emergence of this relatively new subfield of astronomy over the past two decades, and offer a few examples illustrating how the study of NYMGs and their members enables unique investigations of pre-main sequence stellar evolution, evolved protoplanetary disks, and young exoplanets.
Chemical tagging of FGK stars: Testing the Membership of Young Stellar Kinematics Groups
Authors: Montes D. , Tabernero H.M. , González Hernández J.I.
Published: January 2016

In this contribution talk we summarize the results of our ongoing project of detailed analysis of the chemical content (chemical tagging) as a promising powerful method to provide clear constraints on the membership of FGK kinematic candidates to stellar kinematic groups of different ages that can be used as an alternative or complementary to the methods that use kinematics, photometry or age indicators. This membership information is very important to better understand the star formation history in the solar neighborhood discerning between field-like stars (associated with dynamical resonances (bar) or spiral structure) and real physical structures of coeval stars with a common origin (debris of star-forming aggregates in the disk). We have already applied the chemical tagging method to constrain the membership of FGK candidate stars to the Hyades supercluster and the Ursa Major moving group and in this contribution we present the preliminary results of our study of the Castor moving group.
Direct Imaging of Exoplanets Living an Exciting Life
Authors: Chauvin G.
Published: January 2016

With the development of high contrast imaging techniques and instruments, vast efforts have been devoted during the past decades to detect and characterize lighter, cooler and closer companions to nearby stars, and ultimately image new planetary systems. Complementary to other planet-hunting techniques, this approach has opened a new astrophysical window to study the physical properties and the formation mechanisms of brown dwarfs and planets. In this review, I will briefly describe the different observing techniques and strategies used, the main samples of targeted nearby stars, finally the main results obtained so far about exoplanet discoveries characterization of their physical properties, and study of their occurrence and possible formation and evolution mechanisms.
The Evolution of Surface Magnetic Fields in Young Solar-type Stars
Authors: Folsom Colin P. , Petit Pascal , Bouvier Jérôme , Morin Julien , Lèbre Agnès , Donati Jean-François
Published: January 2016

Surface rotation rates of young solar-type stars display drastic changes at the end of the pre-main sequence through the early main sequence. This may trigger corresponding changes in the magnetic dynamos operating in these stars, which ought to be observable in their surface magnetic fields. We present here the first results of an observational effort aimed at characterizing the evolution of stellar magnetic fields through this critical phase. We observed stars from open clusters and associations, which range from 20 to 600 Myr, and used Zeeman Doppler Imaging to characterize their complex magnetic fields. We find a clear trend towards weaker magnetic fields for older ages, as well as a tight correlation between magnetic field strength and Rossby number over this age range. Comparing to results for younger T Tauri stars, we observe a very significant change in magnetic strength and geometry, as the radiative core develops during the late pre-main sequence.
Forecasting Eruptions at Restless Calderas
Authors: Wheeling Kate
Published: January 2016

Scientists review decades of data on swarms of earthquakes, surface deformation, degassing, and microgravity changes around calderas to determine when such forms of unrest may result in eruptions.
Arctic Research on Thin Ice: Consequences of Arctic Sea Ice Loss
Authors: Granskog Mats , Assmy Philipp , Gerland Sebastian , Spreen Gunnar , Steen Harald , Smedsrud Lars
Published: January 2016

Scientists embarked on a 6-month expedition in the Arctic Ocean to study the thinning sea ice cover, improve our understanding of sea ice loss effects, and help predict future changes.
AGU Signs Agreement with Council on Undergraduate Research
Authors: Buhrman Joan
Published: January 2016

Collaboration between the scientific society and the educational organization aims to foster research opportunities and diversity in undergraduate geoscience education.
Gyre-driven decay of the Earth’s magnetic dipole
Authors: Finlay Christopher C. , Aubert Julien , Gillet Nicolas
Published: January 2016

Direct observations indicate that the magnitude of the Earth’s magnetic axial dipole has decreased over the past 175 years; it is now 9% weaker than it was in 1840. Here we show how the rate of dipole decay may be controlled by a planetary-scale gyre in the liquid metal outer core. The gyre’s meridional limbs on average transport normal polarity magnetic flux equatorward and reverse polarity flux poleward. Asymmetry in the geomagnetic field, due to the South Atlantic Anomaly, is essential to the proposed mechanism. We find that meridional flux advection accounts for the majority of the dipole decay since 1840, especially during times of rapid decline, with magnetic diffusion making an almost steady contribution generally of smaller magnitude. Based on the morphology of the present field, and the persistent nature of the gyre, the current episode of dipole decay looks set to continue, at least for the next few decades.
Misorientation-angle-dependent electrical transport across molybdenum disulfide grain boundaries
Authors: Ly Thuc Hue , Perello David J. , Zhao Jiong , Deng Qingming , Kim Hyun , Han Gang Hee , Chae Sang Hoon , Jeong Hye Yun , Lee Young Hee
Published: January 2016

Grain boundaries in monolayer transition metal dichalcogenides have unique atomic defect structures and band dispersion relations that depend on the inter-domain misorientation angle. Here, we explore misorientation angle-dependent electrical transport at grain boundaries in monolayer MoS2 by correlating the atomic defect structures of measured devices analysed with transmission electron microscopy and first-principles calculations. Transmission electron microscopy indicates that grain boundaries are primarily composed of 5–7 dislocation cores with periodicity and additional complex defects formed at high angles, obeying the classical low-angle theory for angles <22°. The inter-domain mobility is minimized for angles <9° and increases nonlinearly by two orders of magnitude before saturating at ∼16 cm2 V−1 s−1 around misorientation angle≈20°. This trend is explained via grain-boundary electrostatic barriers estimated from density functional calculations and experimental tunnelling barrier heights, which are ≈0.5 eV at low angles and ≈0.15 eV at high angles (≥20°).
Graphene–ferroelectric metadevices for nonvolatile memory and reconfigurable logic-gate operations
Authors: Kim Woo Young , Kim Hyeon-Don , Kim Teun-Teun , Park Hyun-Sung , Lee Kanghee , Choi Hyun Joo , Lee Seung Hoon , Son Jaehyeon , Park Namkyoo , Min Bumki
Published: January 2016

Memory metamaterials are artificial media that sustain transformed electromagnetic properties without persistent external stimuli. Previous memory metamaterials were realized with phase-change materials, such as vanadium dioxide or chalcogenide glasses, which exhibit memory behaviour with respect to electrically/optically induced thermal stimuli. However, they require a thermally isolated environment for longer retention or strong optical pump for phase-change. Here we demonstrate electrically programmable nonvolatile memory metadevices realised by the hybridization of graphene, a ferroelectric and meta-atoms/meta-molecules, and extend the concept further to establish reconfigurable logic-gate metadevices. For a memory metadevice having a single electrical input, amplitude, phase and even the polarization multi-states were clearly distinguishable with a retention time of over 10 years at room temperature. Furthermore, logic-gate functionalities were demonstrated with reconfigurable logic-gate metadevices having two electrical inputs, with each connected to separate ferroelectric layers that act as the multi-level controller for the doping level of the sandwiched graphene layer.
Demonstration of a near-IR line-referenced electro-optical laser frequency comb for precision radial velocity measurements in astronomy
Authors: Yi X. , Vahala K. , Li J. , Diddams S. , Ycas G. , Plavchan P. , Leifer S. , Sandhu J. , Vasisht G. , Chen P. , Gao P. , Gagne J. , Furlan E. , Bottom M. , Martin E. C. , Fitzgerald M. P. , Doppmann G. , Beichman C.
Published: January 2016

An important technique for discovering and characterizing planets beyond our solar system relies upon measurement of weak Doppler shifts in the spectra of host stars induced by the influence of orbiting planets. A recent advance has been the introduction of optical frequency combs as frequency references. Frequency combs produce a series of equally spaced reference frequencies and they offer extreme accuracy and spectral grasp that can potentially revolutionize exoplanet detection. Here we demonstrate a laser frequency comb using an alternate comb generation method based on electro-optical modulation, with the comb centre wavelength stabilized to a molecular or atomic reference. In contrast to mode-locked combs, the line spacing is readily resolvable using typical astronomical grating spectrographs. Built using commercial off-the-shelf components, the instrument is relatively simple and reliable. Proof of concept experiments operated at near-infrared wavelengths were carried out at the NASA Infrared Telescope Facility and the Keck-II telescope.
Pd(II)-catalysed meta-C–H functionalizations of benzoic acid derivatives
Authors: Li Shangda , Cai Lei , Ji Huafang , Yang Long , Li Gang
Published: January 2016

Benzoic acids are highly important structural motifs in drug molecules and natural products. Selective C–H bond functionalization of benzoic acids will provide synthetically useful tools for step-economical organic synthesis. Although directortho-C–H functionalizations of benzoic acids or their derivatives have been intensely studied, the ability to activatemeta-C–H bond of benzoic acids or their derivatives in a general manner via transition-metal catalysis has been largely unsuccessful. Although chelation-assistedmeta-C–H functionalization of electron-rich arenes was reported, chelation-assistedmeta-C–H activation of electron-poor arenes such as benzoic acid derivatives remains a formidable challenge. Herein, we report a general protocol formeta-C–H olefination of benzoic acid derivatives using a nitrile-based sulfonamide template. A broad range of benzoic acid derivatives aremeta-selectively olefinated using molecular oxygen as the terminal oxidant. Themeta-C–H acetoxylation, product of which is further transformed at themeta-position, is also reported.
Rapid endothelial cytoskeletal reorganization enables early blood–brain barrier disruption and long-term ischaemic reperfusion brain injury
Authors: Shi Yejie , Zhang Lili , Pu Hongjian , Mao Leilei , Hu Xiaoming , Jiang Xiaoyan , Xu Na , Stetler R. Anne , Zhang Feng , Liu Xiangrong , Leak Rehana K. , Keep Richard F. , Ji Xunming , Chen Jun
Published: January 2016

The mechanism and long-term consequences of early blood–brain barrier (BBB) disruption after cerebral ischaemic/reperfusion (I/R) injury are poorly understood. Here we discover that I/R induces subtle BBB leakage within 30–60 min, likely independent of gelatinase B/MMP-9 activities. The early BBB disruption is caused by the activation of ROCK/MLC signalling, persistent actin polymerization and the disassembly of junctional proteins within microvascular endothelial cells (ECs). Furthermore, the EC alterations facilitate subsequent infiltration of peripheral immune cells, including MMP-9-producing neutrophils/macrophages, resulting in late-onset, irreversible BBB damage. Inactivation of actin depolymerizing factor (ADF) causes sustained actin polymerization in ECs, whereas EC-targeted overexpression of constitutively active mutant ADF reduces actin polymerization and junctional protein disassembly, attenuates both early- and late-onset BBB impairment, and improves long-term histological and neurological outcomes. Thus, we identify a previously unexplored role for early BBB disruption in stroke outcomes, whereby BBB rupture may be a cause rather than a consequence of parenchymal cell injury.
Not so simple, not so subtle: the interspecies competition between Bacillus simplex and Bacillus subtilis and its impact on the evolution of biofilms
Authors: Rosenberg Gili , Steinberg Nitai , Oppenheimer-Shaanan Yaara , Olender Tsvia , Doron Shany , Ben-Ari Julius , Sirota-Madi Alexandra , Bloom-Ackermann Zohar , Kolodkin-Gal Ilana
Published: January 2016

Bacillus subtilisbiofilms have a fundamental role in shaping the soil ecosystem. During this process, they unavoidably interact with neighbour bacterial species. We studied the interspecies interactions between biofilms of the soil-residing bacteriaB. subtilisand relatedBacillusspecies. We found that proximity between the biofilms triggered recruitment of motileB. subtiliscells, which engulfed the competingBacillus simplexcolony. Upon interaction,B. subtilissecreted surfactin and cannibalism toxins, at concentrations that were inert toB. subtilisitself, which eliminated theB. simplexcolony, as well as colonies ofBacillus toyonensis. Surfactin toxicity was correlated with the presence of short carbon-tail length isomers, and synergistic with the cannibalism toxins. Importantly, during biofilm development and interspecies interactions a subpopulation inB. subtilisbiofilm lost its native plasmid, leading to increased virulence against the competingBacillusspecies. Overall, these findings indicate that genetic programs and traits that have little effect on biofilm development when each species is grown in isolation have a dramatic impact when different bacterial species interact.
Intravenous immune globulin suppresses angiogenesis in mice and humans
Authors: Yasuma Reo , Cicatiello Valeria , Mizutani Takeshi , Tudisco Laura , Kim Younghee , Tarallo Valeria , Bogdanovich Sasha , Hirano Yoshio , Kerur Nagaraj , Li Shengjian , Yasuma Tetsuhiro , Fowler Benjamin J , Wright Charles B , Apicella Ivana , Greco Adelaide , Brunetti Arturo , Ambati Balamurali K , Helmers Sevim Barbasso , Lundberg Ingrid E , Viklicky Ondrej , Leusen Jeanette HW , Verbeek J Sjef , Gelfand Bradley D , Bastos-Carvalho Ana , De Falco Sandro , Ambati Jayakrishna
Published: January 2016

Human intravenous immune globulin (IVIg), a purified IgG fraction composed of ~60% IgG1 and obtained from the pooled plasma of thousands of donors, is clinically used for a wide range of diseases. The biological actions of IVIg are incompletely understood and have been attributed both to the polyclonal antibodies therein and also to their IgG (IgG) Fc regions. Recently, we demonstrated that multiple therapeutic human IgG1 antibodies suppress angiogenesis in a target-independent manner via FcγRI, a high-affinity receptor for IgG1. Here we show that IVIg possesses similar anti-angiogenic activity and inhibited blood vessel growth in five different mouse models of prevalent human diseases, namely, neovascular age-related macular degeneration, corneal neovascularization, colorectal cancer, fibrosarcoma and peripheral arterial ischemic disease. Angioinhibition was mediated by the Fc region of IVIg, required FcγRI and had similar potency in transgenic mice expressing human FcγRs. Finally, IVIg therapy administered to humans for the treatment of inflammatory or autoimmune diseases reduced kidney and muscle blood vessel densities. These data place IVIg, an agent approved by the US Food and Drug Administration, as a novel angioinhibitory drug in doses that are currently administered in the clinical setting. In addition, they raise the possibility of an unintended effect of IVIg on blood vessels.
Col4a1 mutations cause progressive retinal neovascular defects and retinopathy
Authors: Alavi Marcel V. , Mao Mao , Pawlikowski Bradley T. , Kvezereli Manana , Duncan Jacque L. , Libby Richard T. , John Simon W. M. , Gould Douglas B.
Published: January 2016

Mutations in collagen, type IV, alpha 1 (COL4A1), a major component of basement membranes, cause multisystem disorders in humans and mice. In the eye, these include anterior segment dysgenesis, optic nerve hypoplasia and retinal vascular tortuosity. Here we investigate the retinal pathology in mice carrying dominant-negative Col4a1 mutations. To this end, we examined retinas longitudinally in vivo using fluorescein angiography, funduscopy and optical coherence tomography. We assessed retinal function by electroretinography and studied the retinal ultrastructural pathology. Retinal examinations revealed serous chorioretinopathy, retinal hemorrhages, fibrosis or signs of pathogenic angiogenesis with chorioretinal anastomosis in up to approximately 90% of Col4a1 mutant eyes depending on age and the specific mutation. To identify the cell-type responsible for pathogenesis we generated a conditional Col4a1 mutation and determined that primary vascular defects underlie Col4a1-associated retinopathy. We also found focal activation of Müller cells and increased expression of pro-angiogenic factors in retinas from Col4a1+/Δex41mice. Together, our findings suggest that patients with COL4A1 and COL4A2 mutations may be at elevated risk of retinal hemorrhages and that retinal examinations may be useful for identifying patients with COL4A1 and COL4A2 mutations who are also at elevated risk of hemorrhagic strokes.
Correction: Corrigendum: HCRP-1 regulates cell migration and invasion via EGFR-ERK mediated up-regulation of MMP-2 with prognostic significance in human renal cell carcinoma
Authors: Chen Feifei , Deng Junpeng , Liu Xin , Li Wang , Zheng Junnian
Published: January 2016

Previous studies indicated a role of hepatocellular carcinoma-related protein-1(HCRP-1) in human cancers, however, its expression pattern in renal cell carcinoma (RCC) and the molecular mechanism of HCRP-1 on cancer progression have not been characterized. In the present study, HCRP-1 expression was examined in a RCC tissue microarray. The negative expression of HCRP-1 was significantly correlated with tumor grade (P = 0.002), TNM stage (P = 0.001) and pT status (P = 0.003). Furthermore, we showed a strong correlation between negative HCRP-1 expression and worse overall and disease-specific survival (P = 0.0003 and P = 0.0012, respectively). Knockdown of HCRP-1 promoted cell migration and invasion in 786-O and OS-RC-2 cell lines. HCRP-1 depletion increased matrix metalloproteinase (MMP)-2 protein level, with increased extracellular signal-regulatedkinase (ERK) phosphorylation, which could be reversed by ERK siRNA or ERK inhibitor, PD98059. Further analysis showed that HCRP-1 knockdown induced epidermal growth factor receptor (EGFR) phosphorylation. Treatment with EGFR inhibitor or EGFR siRNA blocked HCRP-1-mediated up-regulation of EGFR, ERK phosphorylation and MMP-2 expression. In summary, our results showed that negative HCRP-1 expression is an independent prognostic factor for RCC patients and promotes migration and invasion by EGFR-ERK-mediated up-regulation of MMP-2. HCRP-1 may serve as a therapeutic target for RCC.
Stearoyl-CoA desaturase-1 mediated cell apoptosis in colorectal cancer by promoting ceramide synthesis
Authors: Chen Ling , Ren Jie , Yang Longhe , Li Yanting , Fu Jin , Li Yuhang , Tian Yifeng , Qiu Funan , Liu Zuguo , Qiu Yan
Published: January 2016

Inhibition of stearoyl-CoA desaturase 1 (SCD1) has been found to effectively suppress tumor cell proliferation and induce apoptosis in numerous neoplastic lesions. However, mechanism underlying SCD1-mediated anti-tumor effect has maintained unclear. Herein, we reported endo-lipid messenger ceramides played a critical role in tumor fate modulated by SCD1 inhibition. In vitro study in colorectal cancer cells demonstrated inhibition of SCD1 activity promoted apoptosis attributed to mitochondria dysfunctions, upregulation of reaction oxygen species (ROS), alteration of mitochondrial transmembrane potential and translocation of mitochondrial protein cytochrome C. While these effects were mediated by intracellular ceramide signals through induction of ceramide biosynthesis, rather than exclusive SFA accumulation. In vivo study in xenograft colorectal cancer mice showed pharmacologic administration of SCD1 inhibitor A939 significantly delayed tumor growth, which was reversed by L-cycloserine, an inhibitor of ceramide biosynthesis. These results depicted the cross-talk of SCD1-mediated lipid pathway and endo-ceramide biosynthesis pathway, indicating roles of ceramide signals in SCD1-mediated anti-tumor property.
Secreted Thrombospondin-1 Regulates Macrophage Interleukin-1β Production and Activation through CD47
Authors: Stein Erica V. , Miller Thomas W. , Ivins-O’Keefe Kelly , Kaur Sukhbir , Roberts David D.
Published: January 2016

Thrombospondin-1 regulates inflammation by engaging several cell surface receptors and by modulating activities of other secreted factors. We have uncovered a novel role of thrombospondin-1 in modulating production and activation of the proinflammatory cytokine IL-1β by human and murine macrophages. Physiological concentrations of thrombospondin-1 limit the induction by lipopolysaccharide of IL-1β mRNA and total protein production by human macrophages. This inhibition can be explained by the ability of thrombospondin-1 to disrupt the interaction between CD47 and CD14, thereby limiting activation of NFκB/AP-1 by lipopolysaccharide. Only the CD47-binding domain of thrombospondin-1 exhibits this activity. In contrast, CD47, CD36 and integrin-binding domains of thrombospondin-1 independently enhance the inflammasome-dependent maturation of IL-1β in human THP-1 monocyte-derived macrophages. Correspondingly, mouse bone marrow-derived macrophages that lack either thrombospondin-1 or CD47 exhibit diminished induction of mature IL-1β in response to lipopolysaccharide. Lack of CD47 also limits lipopolysaccharide induction of IL-1β, NLRP3 and caspase-1 mRNAs. These data demonstrate that thrombospondin-1 exerts CD47-dependent and -independent pro-and anti-inflammatory effects on the IL-1β pathway. Therefore, thrombospondin-1 and its receptor CD47 may be useful targets for limiting the pro-inflammatory effects of lipopolysaccharide and for treating endotoxemia.
Capture and On-chip analysis of Melanoma Cells Using Tunable Surface Shear forces
Authors: Tsao Simon Chang-Hao , Vaidyanathan Ramanathan , Dey Shuvashis , Carrascosa Laura G. , Christophi Christopher , Cebon Jonathan , Shiddiky Muhammad J. A. , Behren Andreas , Trau Matt
Published: January 2016

With new systemic therapies becoming available for metastatic melanoma such as BRAF and PD-1 inhibitors, there is an increasing demand for methods to assist with treatment selection and response monitoring. Quantification and characterisation of circulating melanoma cells (CMCs) has been regarded as an excellent non-invasive candidate but a sensitive and efficient tool to do these is lacking. Herein we demonstrate a microfluidic approach for melanoma cell capture and subsequent on-chip evaluation of BRAF mutation status. Our approach utilizes a recently discovered alternating current electrohydrodynamic (AC-EHD)-induced surface shear forces, referred to as nanoshearing. A key feature of nanoshearing is the ability to agitate fluid to encourage contact with surface-bound antibody for the cell capture whilst removing nonspecific cells from the surface. By adjusting the AC-EHD force to match the binding affinity of antibodies against the melanoma-associated chondroitin sulphate proteoglycan (MCSP), a commonly expressed melanoma antigen, this platform achieved an average recovery of 84.7% from biological samples. Subsequent staining with anti-BRAFV600E specific antibody enabled on-chip evaluation of BRAFV600E mutation status in melanoma cells. We believe that the ability of nanoshearing-based capture to enumerate melanoma cells and subsequent on-chip characterisation has the potential as a rapid screening tool while making treatment decisions.
Expression of terminal oxidases under nutrient-starved conditions in Shewanella oneidensis: detection of the A-type cytochrome c oxidase
Authors: Le Laz Sébastien , kpebe Arlette , Bauzan Marielle , Lignon Sabrina , Rousset Marc , Brugna Myriam
Published: January 2016

Shewanellaspecies are facultative anaerobic bacteria that colonize redox-stratified habitats where O2and nutrient concentrations fluctuate. The model speciesShewanella oneidensisMR-1 possesses genes coding for three terminal oxidases that can perform O2respiration: abd-type quinol oxidase and cytochromecoxidases of thecbb3-type and the A-type. Whereas thebd- andcbb3-type oxidases are routinely detected, evidence for the expression of the A-type enzyme has so far been lacking. Here, we investigated the effect of nutrient starvation on the expression of these terminal oxidases under different O2tensions. Our results reveal that thebd-type oxidase plays a significant role under nutrient starvation in aerobic conditions. The expression of thecbb3-type oxidase is also modulated by the nutrient composition of the medium and increases especially under iron-deficiency in exponentially growing cells. Most importantly, under conditions of carbon depletion, high O2and stationary-growth, we report for the first time the expression of the A-type oxidase inS. oneidensis,indicating that this terminal oxidase is not functionally lost. The physiological role of the A-type oxidase in energy conservation and in the adaptation ofS. oneidensisto redox-stratified environments is discussed.
Generating trunk neural crest from human pluripotent stem cells
Authors: Huang Miller , Miller Matthew L. , McHenry Lauren K. , Zheng Tina , Zhen Qiqi , Ilkhanizadeh Shirin , Conklin Bruce R. , Bronner Marianne E. , Weiss William A.
Published: January 2016

Neural crest cells (NCC) are stem cells that generate different lineages, including neuroendocrine, melanocytic, cartilage and bone. The differentiation potential of NCC varies according to the level from which cells emerge along the neural tube. For example, only anterior “cranial” NCC form craniofacial bone, whereas solely posterior “trunk” NCC contribute to sympathoadrenal cells. Importantly, the isolation of human fetal NCC carries ethical and scientific challenges, as NCC induction typically occur before pregnancy is detectable. As a result, current knowledge of NCC biology derives primarily from non-human organisms. Important differences between human and non-human NCC, such as expression of HNK1 in human but not mouse NCC, suggest a need to study human NCC directly. Here, we demonstrate that current protocols to differentiate human pluripotent stem cells (PSC) to NCC are biased toward cranial NCC. Addition of retinoic acid drove trunk-related markers and HOX genes characteristic of a posterior identity. Subsequent treatment with bone morphogenetic proteins (BMPs) enhanced differentiation to sympathoadrenal cells. Our approach provides methodology for detailed studies of human NCC and clarifies roles for retinoids and BMPs in the differentiation of human PSC to trunk NCC and to sympathoadrenal lineages.
Autosomal gsdf acts as a male sex initiator in the fish medaka
Authors: Zhang Xi , Guan Guijun , Li Mingyou , Zhu Feng , Liu Qizhi , Naruse Kiyoshi , Herpin Amaury , Nagahama Yoshitaka , Li Jiale , Hong Yunhan
Published: January 2016

Sex is pivotal for reproduction, healthcare and evolution. In the fish medaka, the Y-chromosomal dmy (also dmrt1bY) serves the sex determiner, which activates dmrt1 for male sex maintenance. However, how dmy makes the male decision via initiating testicular differentiation has remained unknown. Here we report that autosomal gsdf serves a male sex initiator. Gene addition and deletion revealed that gsdf was necessary and sufficient for maleness via initiating testicular differentiation. We show that gsdf transcription is activated directly by dmy. These results establish the autosomal gsdf as the first male sex initiator. We propose that dmy determines maleness through activating gsdf and dmrt1 without its own participation in developmental processes of sex initiation and maintenance. gsdf may easily become a sex determiner or other autosomal genes can be recruited as new sex determiners to initiate gsdf expression. Our findings offer new insights into molecular mechanisms underlying sex development and evolution of sex-controlling genes in vertebrates.
Nonclassical light from a large number of independent single-photon emitters
Authors: Lachman Lukáš , Slodička Lukáš , Filip Radim
Published: January 2016

Nonclassical quantum effects gradually reach domains of physics of large systems previously considered as purely classical. We derive a hierarchy of operational criteria suitable for a reliable detection of nonclassicality of light from an arbitrarily large ensemble of independent single-photon emitters. We show, that such large ensemble can always emit nonclassical light without any phase reference and under realistic experimental conditions including incoherent background noise. The nonclassical light from the large ensemble of the emitters can be witnessed much better than light coming from a single or a few emitters.