bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamical evolution of dense star clusters in galactic nuclei
Authors: Haas Jaroslav , Šubr Ladislav 
Published: May 2014

AbstractBy means of direct numerical N-body modeling, we investigate the orbital evolution of an initially thin, central mass dominated stellar disk. We include the perturbative gravitational influence of an extended spherically symmetric star cluster and the mutual gravitational interaction of the stars within the disk. Our results show that the two-body relaxation of the disk leads to significant changes of its radial density profile. In particular, the disk naturally evolves, for a variety of initial configurations, a similar broken power-law surface density profile. Hence, it appears that the single power-law surface density profile ∝R−2 suggested by various authors to describe the young stellar disk observed in the Sgr A* region does not match theoretical expectations.
The Keplerian orbit of G2
Authors: Meyer L. , Ghez A. M. , Witzel G. , Do T. , Phifer K. , Sitarski B. N. , Morris M. R. , Boehle A. , Yelda S. , Lu J. R. , Becklin E. 
Published: May 2014

AbstractWe give an update of the observations and analysis of G2 – the gaseous red emission-line object that is on a very eccentric orbit around the Galaxy's central black hole and predicted to come within 2400 RS in early 2014. During 2013, the laser guide star adaptive optics systems on the W. M. Keck I and II telescopes were used to obtain three epochs of spectroscopy and imaging at the highest spatial resolution currently possible in the near-IR. The updated orbital solution derived from radial velocities in addition to Br-γ line astrometry is consistent with our earlier estimates. Strikingly, even ∼ 6 months before pericenter passage there is no perceptible deviation from a Keplerian orbit. We furthermore show that a proposed “tail” of G2 is likely not associated with it but is rather an independent gas structure. We also show that G2 does not seem to be unique, since several red emission-line objects can be found in the central arcsecond. Taken together, it seems more likely that G2 is ultimately stellar in nature, although there is clearly gas associated with it.
Near infrared variability of Sgr A* - spectral index measurements
Authors: Witzel G. , Morris M. , Ghez A. , Meyer L. , Becklin E. , Matthews K. , Lu J. R. , Do T. , Campbell R. 
Published: May 2014

AbstractWe discuss observations of Sagittarius A* with NACO@VLT in K-band and recent synchronous observations with NIRC2@Keck II and OSIRIS@Keck I in L′-band and H-band, respectively. The variability of Sagittarius A* in the near infrared is a continuous one-state process that can be described by a pure red-noise process having a timescale of a few hours. We describe this process and its properties in detail. Our newest observations with the Keck telescopes represent the first truly synchronous high cadence data set to test for time variability of the spectral index within the near infrared. We discovered a time-variable spectral index that might be interpreted as a time lag of the L′-band with respect to the H-band.
Exploring plasma evolution during Sagittarius A* flares
Authors: Dibi S. , Markoff S. , Belmont R. , Malzac J. , Barrière N. M. , Tomsick J. A. 
Published: May 2014

AbstractWe present a new way of describing the flares occurring from Sgr A* within a single zone with a self-consistent calculation of the particle distribution. The results allow us to give an interpretation to the flaring events generated very close to the supermassive black hole (SMBH) without assuming a specific particle distribution. We conclude that the flare data are more likely generated by a weakly magnetized plasma in which the particles flow in and out as expected from an accretion flow. Such a plasma, with prescription for non-thermal acceleration, injection, escape, and cooling losses, gives a spectrum with a break between the infra-red and the X-ray, allowing a better simultaneous match in the different wavelengths. The parameters favor the non-thermal synchrotron spectrum, and a decrease/increase of the magnetic field and plasma density are not favored for producing the flare event, but particle acceleration must be happening by other means. We show that under certain conditions, the real particle distribution can differ significantly from the standard distributions used in such studies.
Theory of G2 cloud multi-wavelength emission
Authors: Shcherbakov R. V. 
Published: May 2014

AbstractAn object called G2 was recently discovered moving towards the supermassive black hole in the Galactic center. G2 emits infrared (IR) lines and continuum, which allows constraining its properties. The question is still unresolved whether G2 has a central windy star or it is a coreless cloud. Assuming the object is a cloud originating near the apocenter I perform line/continuum IR diagnostics, revisit estimates of non-thermal emission from pericenter passage, and speculate about future observational prospects. This work is partially reported in Shcherbakov (2013) and partially consists of new ideas discussed at the conference.
Search for time lag in intra-day variability of Sgr A*
Authors: Miyazaki A. , Lee S. S. , Sohn B. W. , Jung T. , Tsuboi M. , Tsutsumi T. 
Published: May 2014

AbstractWe searched the time lag between the intra-day variables (IDVs) of Sagittarius A* at 22, 43, and 86 GHz bands using the Korean VLBI Network (KVN). The time lags between the IDV flare peaks at 22 and 43 GHz are reported, and they suggest that the flare emissions come from adiabatically expanding plasma blobs, ejected close to the Galactic center black hole. We searched the time lags between light curves at 90 and 102 GHz using the Nobeyama Millimeter Array, but could not find significant time lags. In order to detect the diversity of the time lags of Sgr A* flares, we performed observations of Sgr A* in the 22, 43, and 86 GHz bands using the KVN in the winter of 2013. Because the receiver system of KVN can observe Sgr A* in these three bands simultaneously, the KVN is very useful to detect the time lags of Sgr A* flares.
Monitoring observations of the interaction between Sgr A* and G2 with the Karl G. Jansky Very Large Array
Authors: Sjouwerman Loránt O. , Chandler Claire J. 
Published: May 2014

AbstractWe report on an ongoing community service observing program to follow the expected encounter of the G2 cloud with the black hole Sgr A* in 2013. The NRAO Karl G. Jansky Very Large Array (VLA) has been observing the Sgr A region since 2012 October on roughly a bi-monthly interval, each for two hours, cycling through eight observing bands at their default continuum frequencies, using 2 GHz of bandwidth. The data from the monitoring program are publicly available through the NRAO data archive immediately after observing has completed, and the flux densities are published by NRAO staff as soon as the data are reduced. The cumulative results of the monitoring effort are posted on the service observing web page https://science.nrao.edu/science/service-observing and so far do not indicate a significant brightening of the emission from the direction of Sgr A* over the period 2012 October to 2013 September, within the calibration uncertainties.
Discovery of a recombination dominant plasma: a relic of a giant flare of Sgr A*?
Authors: Nakashima S. , Nobukawa M. , Uchida H. , Tanaka T. , Tsuru T. G. , Koyama K. , Uchiyama H. , Murakami H. 
Published: May 2014

AbstractWe present the discovery of out-flow like plasma emissions with the Suzaku and ASCA data. Those plasmas have a size of ∼150 pc. Remarkably, the southern plasma is in a recombination dominant phase, which is not predicted by standard shock heating. A plausible scenario is either photoionization due to strong jet-like X-rays from Sgr A* or rapid cooling due to adiabatic expansion of a blowout plasma from the Galactic center about 105 years ago.
A new perspective on the radio active zone at the Galactic center – feedback from nuclear activities
Authors: Zhao J.-H. , Morris M. R. , Goss W. M. 
Published: May 2014

AbstractBased on our deep image of Sgr A using broadband data observed with the VLA† at 6 cm, we present a new perspective of the radio bright zone at the Galactic center. We further show the radio detection of the X-ray Cannonball, a candidate neutron star associated with the Galactic center SNR Sgr A East. The radio image is compared with the Chandra X-ray image to show the detailed structure of the radio counterparts of the bipolar X-ray lobes. The bipolar lobes are likely produced by the winds from the activities within Sgr A West, which could be collimated by the inertia of gas in the CND, or by the momentum driving of Sgr A*; and the poloidal magnetic fields likely play an important role in the collimation. The less-collimated SE lobe, in comparison to the NW one, is perhaps due to the fact that the Sgr A East SN might have locally reconfigured the magnetic field toward negative galactic latitudes. In agreement with the X-ray observations, the time-scale of ∼1 × 104 yr estimated for the outermost radio ring appears to be comparable to the inferred age of the Sgr A East SNR.
The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center
Authors: Neilsen J. , Nowak M. A. , Gammie C. , Dexter J. , Markoff S. , Haggard D. , Nayakshin S. , Wang Q. D. , Grosso N. , Porquet D. , Tomsick J. A. , Degenaar N. , Fragile P. C. , Houck J. C. , Wijnands R. , Miller J. M. , Baganoff F. K. 
Published: May 2014

AbstractOver the last decade, X-ray observations of Sgr A* have revealed a black hole in a deep sleep, punctuated roughly once per day by brief flares. The extreme X-ray faintness of this supermassive black hole has been a long-standing puzzle in black hole accretion. To study the accretion processes in the Galactic center, Chandra (in concert with numerous ground- and space-based observatories) undertook a 3 Ms campaign on Sgr A* in 2012. With its excellent observing cadence, sensitivity, and spectral resolution, this Chandra X-ray Visionary Project (XVP) provides an unprecedented opportunity to study the behavior of the closest supermassive black hole. We present a progress report from our ongoing study of X-ray flares, including the brightest flare ever seen from Sgr A*. Focusing on the statistics of the flares and the quiescent emission, we discuss the physical implications of X-ray variability in the Galactic center.
Time lags between starburst and AGN activity in galaxy mergers
Authors: Blank M. , Duschl W. J. 
Published: May 2014

AbstractWe show that the observed time lag between starburst and AGN activity can be explained by a viscous time lag the gas needs to flow through the AGN's accretion disk before reaching the central black hole. Our calculations reproduce the observed time lag and are in agreement with the observed correlation between black hole mass and stellar velocity dispersion.
Dark matter in the Galactic center
Authors: Linden Tim 
Published: May 2014

AbstractIn addition to boasting the highest density of baryonic matter in our galaxy, the center of the Milky Way is also believed to contain an extremely high density of dark matter particles. While dark matter is expected to be gravitationally subdominant to baryons near the Galactic center, many models allow for the annihilation of dark matter into standard model particles, a phenomenon which could be a significant source of high energy radiation in the Galactic center region. In fact, standard models of the dark matter density distribution and annihilation spectrum predict that dark matter at the Galactic center would (1) produce the brightest flux from dark matter annihilation of any region in the sky, and (2) contribute a significant portion of the total γ-ray luminosity observed within several degrees of the Galactic center by the Fermi/LAT. This makes the effort to understand and differentiate the morphologies and spectral features of dark matter and astrophysical γ-ray emission at the Galactic center potentially rewarding. Here, I will summarize the recent developments in indirect searches for dark matter annihilation at the Galactic center, and discuss several of the difficulties in producing accurate models of the high energy astrophysical emission. Finally, I will comment on current efforts to produce multi-wavelength models which better constrain or indicate a dark matter signal at the Galactic center.
Diffusion of cosmic-ray electrons in the Galactic centre molecular cloud G0.13–0.13
Authors: Lehmann Andrew , Wardle Mark 
Published: May 2014

AbstractThe Galactic center (GC) molecular cloud G0.13–0.13 exhibits a shell morphology in CS J = (1 − 0), with ∼ 105 solar masses and expansion speed ∼ 20 km s−1, yielding a total kinetic energy ∼ 1051 erg. Its morphology is also suggestive of an interaction with the nonthermal filaments of the GC arc. 74 MHz emission indicates the presence of a substantial population of low energy electrons permeating the cloud, which could either be produced by the interaction with the arc or accelerated in the shock waves responsible for the cloud's expansion. These scenarios are explored using time dependent diffusion models.With these diffusion models, we determine the penetration of low-energy cosmic-ray electrons accelerated into G0.13–0.13 and calculate the spatial distribution of the cosmic-ray ionization and heating rates. We show that the 6.4 keV Fe Kα line emission associated with the electron population provides an observational diagnostic to distinguish these two acceleration scenarios.We discuss the implications of our results for understanding the distinct character of clouds in the central molecular zone compared to clouds in the Galactic disk, and how GC nonthermal filaments interact with molecular clouds.
A new era for low frequency Galactic center transient monitoring
Authors: Kassim N. E. , Hyman S. D. , Intema H. , Lazio T. J. W. 
Published: May 2014

AbstractAn upgrade of the low frequency observing system of the VLA developed by NRL and NRAO, called low band (LB), will open a new era of Galactic center (GC) transient monitoring. Our previous searches using the VLA and GMRT have revealed a modest number of radio-selected transients, but have been severely sensitivity and observing time limited. The new LB system, currently accessing the 236--492 MHz frequency range, promises ≥5 × improved sensitivity over the legacy VLA system. The new system is emerging from commissioning in time to catch any enhanced sub-GHz emission from the G2 cloud event, and we review existing limits based on recent observations. We also describe a proposed 24/7 commensal system, called the LOw Band Observatory (LOBO). LOBO offers over 100 VLA GC monitoring hours per year, possibly revealing new transients and helping validate ASTRO2010's anticipation of a new era of transient radio astronomy. A funded LOBO pathfinder called the VLA Low Frequency Ionosphere and Transient Experiment (VLITE) is under development. Finally, we consider the impact of LB and LOBO on our GC monitoring program.
History as a laboratory to better understand the formation of institutions
Authors: VAN BAVEL BAS 
Published: May 2014

AbstractA main instrument for better understanding the formation of institutions, and explaining the differences in their long-run development between periods and societies, would be to use history as a laboratory, allowing us to test the hypotheses developed in the social sciences. This paper discusses the study by Douglas Allen,The Institutional Revolution, in that context, in order to identify some of the pitfalls in the current attempts by economists to use historical analysis. Next, the paper places his English case into a comparative perspective, helped by the recent insights gained by economic and social history, to see how these pitfalls can be avoided. Based on this, I argue for comparisons at the regional, national and global levels, and for a multidimensional view which includes social contextualization, combined with an open eye for discontinuity in long-run patterns, in order to avoid one-dimensional and teleological approaches to institutional change.
P53-regulated long non-coding RNA TUG1 affects cell proliferation in human non-small cell lung cancer, partly through epigenetically regulating HOXB7 expression
Authors: Zhang E-b , Yin D-d , Sun M , Kong R , Liu X-h , You L-h , Han L , Xia R , Wang K-m , Yang J-s , De W , Shu Y-q , Wang Z-x 
Published: May 2014

AbstractRecently, a novel class of transcripts, long non-coding RNAs (lncRNAs), is being identified at a rapid pace. These RNAs have critical roles in diverse biological processes, including tumorigenesis. Here we report that taurine-upregulated gene 1 (TUG1), a 7.1-kb lncRNA, recruiting and binding to polycomb repressive complex 2 (PRC2), is generally downregulated in non-small cell lung carcinoma (NSCLC) tissues. In a cohort of 192 NSCLC patients, the lower expression of TUG1 was associated with a higher TNM stage and tumor size, as well as poorer overall survival (P<0.001). Univariate and multivariate analyses revealed that TUG1 expression serves as an independent predictor for overall survival (P<0.001). Further experiments revealed that TUG1 expression was induced by p53, and luciferase and chromatin immunoprecipitation (ChIP) assays confirmed that TUG1 was a direct transcriptional target of p53. TUG1 knockdown significantly promoted the proliferation in vitro and in vivo. Moreover, the lncRNA-mediated regulation of the expression of HOX genes in tumorigenesis and development has been recently receiving increased attention. Interestingly, inhibition of TUG1 could upregulate homeobox B7 (HOXB7) expression; ChIP assays demonstrated that the promoter of HOXB7 locus was bound by EZH2 (enhancer of zeste homolog 2), a key component of PRC2, and was H3K27 trimethylated. This TUG1-mediated growth regulation is in part due to specific modulation of HOXB7, thus participating in AKT and MAPK pathways. Together, these results suggest that p53-regulated TUG1 is a growth regulator, which acts in part through control of HOXB7. The p53/TUG1/PRC2/HOXB7 interaction might serve as targets for NSCLC diagnosis and therapy.
Erratum: Phylogenetic distribution of three pathways for propionate production within the human gut microbiota
Authors: Reichardt Nicole , Duncan Sylvia H , Young Pauline , Belenguer Alvaro , McWilliam Leitch Carol , Scott Karen P , Flint Harry J , Louis Petra 
Published: May 2014

Abstract
Correction to: The ISME Journal (2014) 8, 1323–1335; doi:10.1038/ismej.2014.14; published online 20 February 2014 Since the publication of this article, the authors have identified two omissions within their paper, the main one being that the author affiliations were incomplete. The correct list is shown here.
What a Difference a Day Makes: Change in Memory for Newly Learned Word Forms Over 24 Hours
Authors: McGregor Karla K. 
Published: May 2014

Purpose
This study explored the role of time and retrieval experience in the consolidation of word forms.

Method
Participants were 106 adults trained on 16 novel word-referent pairs, then tested immediately and 24 hr later for recognition and recall of word forms. In the interim, tests were repeated 2 hr or 12 hr after training, or not at all, thus varying the amount and timing of retrieval experience.

Results
Recognition accuracy was stable and speed improved over the 24-hr period. But these manifestations of consolidation did not depend on interim retrieval experience; in fact, the 2-hr interim test interfered with improvements in speed. In contrast, the number of word forms recalled increased only with interim retrieval experiences, and the 12-hr interim test was more advantageous to recall than the 2-hr test.

Conclusions
After a word form is encoded, it can become stronger with time. Retrieval experience can also strengthen the trace, but, if retrieval occurs when the memory is still labile, it can be disruptive. This complex interplay between retrieval experience and time holds implications for measuring learning outcomes and for scheduling practice in classrooms and clinics.
Combining linkage and association mapping identifiesRECEPTOR-LIKE PROTEIN KINASE1as an essentialArabidopsisshoot regeneration gene
Authors: Motte Hans , Vercauteren Annelies , Depuydt Stephen , Landschoot Sofie , Geelen Danny , Werbrouck Stefaan , Goormachtig Sofie , Vuylsteke Marnik , Vereecke Danny 
Published: May 2014

SignificanceThe regeneration of entire plants from explants is an important step in plant production and plant transformation protocols. Despite recent advances in the knowledge on the molecular basis of regeneration, many aspects of the process and the causes of regeneration recalcitrance are still poorly understood. We combined linkage with association mapping to find genes underlying the natural variation of shoot regeneration inArabidopsis. With this approach, we identified and confirmed the involvement ofRECEPTOR-LIKE PROTEIN KINASE1as a previously unknown determinant of shoot regeneration. Because this gene is implicated in abscisic acid signaling, it seems that this hormone might be an important player in this developmental process.
Generation of bright isolated attosecond soft X-ray pulses driven by multicycle midinfrared lasers
Authors: Chen Ming-Chang , Mancuso Christopher , Hernández-García Carlos , Dollar Franklin , Galloway Ben , Popmintchev Dimitar , Huang Pei-Chi , Walker Barry , Plaja Luis , Jaroń-Becker Agnieszka A. , Becker Andreas , Murnane Margaret M. , Kapteyn Henry C. , Popmintchev Tenio 
Published: May 2014

Significance
Attosecond pulses driven by femtosecond lasers make it possible to capture the fastest electron dynamics in molecules and materials. To date, attosecond pulses driven by widely available 800-nm lasers were limited to the extreme UV region of the spectrum, which restricted the range of materials, liquid, and molecular systems that could be explored because of the limited penetrating power. Our recent work showed that longer-wavelength midinfrared driving lasers at wavelengths from 1 to 4 µm are optimal for generating shorter-wavelength, bright, soft X-ray beams. Here we show that longer-pulse-duration midinfrared lasers are also optimal for generating shorter-pulse-duration, attosecond, soft X-rays. This is an unexpected and beautiful convergence of physics: bright, soft X-ray high harmonics naturally emerge as isolated attosecond bursts.
Gesture, feature, autosegment
Authors: Ladd D. Robert 
Published: May 2014

AbstractThe Prague School concept of feature, which forms part of most mainstream phonological theories, is crucially ambiguous between two interpretations: are features attributes of segments (with segments remaining the primary elements of phonology), or are they autonomous atoms of phonology (with segments being composite or even epiphenomenal)? Early work in autosegmental phonology assumed the first view, and explored the properties of autonomous phonological elements (such as tones) that are neither ordered segments nor attributes of ordered segments. The second view (which is widely held but has never been properly theorized) underlies the ‘naturalness condition’, according to which phonological features must be phonetically definable. This condition is problematical and fails badly in describing the phonological structure of visual communication systems (including signed languages and writing). The naturalness condition should be abandoned and autosegments should be distinguished from features; phonetic description should be quantitative, and features should be seen as symbolic abstractions that characterize phonological segments