bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Angular Resolution Observations of Maser Kinematics Near Low Mass Young Stellar Objects
Authors: Marvel Kevin B. , Claussen Mark , Alwyn Wootten H. , Wilking Bruce 
Published: July 2016

With the advent of new correlators and dedicated arrays, spectral line VLBI is entering its ascendancy as a probe of a variety of interesting astrophysical environments. One of the most interesting environments where spectroscopic VLBI techniques are valuable are the regions directly coincident with forming stars. In these sources, water maser emission is observed when the outflowing jets of material interact with the surrounding medium. Observations of these water masers dramatically reveal the innermost regions of the star formation process at or below the 1-AU scale.We have found that the water masers clearly trace the jets at these scales. The masers show space motions on the order of 60 to 100 kms−1 and form within a few AU of the exciting protostar. By observing the distributions and motions of the water masers associated with these objects, we may be able to address in greater detail the collimation mechanism of the jets seen in these protostars.In this brief poster proceeding, we provide a summary image of the water masers associated with SVS13, the driving source for the HH 7-11 objects. We have also mapped the masers associated with IRAS 16293-2422, IRAS 05413-0104, IRAS 4A and IRAS 4B, both in the NGC 1333 star forming region. For further information on these sources, please contact any of the authors directly.
Microlensing: A Tool to Probe Distant Binary Populations
Authors: Di Stefano Rosanne 
Published: July 2016

Programs designed to observe gravitational microlensing are poised to provide a great deal of information about binary populations far from Earth, including those in the Galactic Bulge, in the Magellanic Clouds, in M31, and perhaps in other external galaxies. Because many millions of stars are monitored, microlensing observations allow us to study binaries in three ways: (1) when they are “involved” in a microlensing event (as either a lens or lensed source), (2) when variability due to binarity produces significant variations in the light curve, and (3) when light from a more distant star is attenuated or refracted by matter associated with the binary system (e.g., in a disk).Microlensing observations will discover large numbers of binaries and planetary systems in a variety of galactic environments. Thus, comparative statistical studies of binary properties (distributions of mass ratios and orbital separations) are possible.An intriguing sign that we have already begun to learn about binaries through microlensing observations comes from work indicating that all of the lenses detected to date may in fact be binaries. For observations along the direction of the Magellanic Clouds this would imply that, if the lenses are primarily located in the Halo, then MACHOs tend to be binaries. If, on the other hand, most of the lenses are located in the Magellanic Clouds, microlensing observations are giving us a unique way to explore a distant stellar population of binaries.
The Next Generation Space Telescope
Authors: Stockman H. S. , Mather John C. 
Published: July 2016

The Next Generation Space Telescope (NGST) will be an 8 m deployable telescope, radiatively cooled to 30 K and diffraction-limited at 2 μm, operating at the Sun-Earth Lagrangian point L2. It will be built by a partnership of NASA, ESA, and CSA (Canadian Space Agency). The camera sensitivity should be limited by the zodiacal light for wavelengths < 10 μm. The main scientific objectives are the study of the origin and evolution of galaxies, stars, and planets, beginning with the first luminous objects to form from the Big Bang. Other objectives include studies of dark matter, supernovae, the intergalactic medium, gamma ray bursts, star ages, and exobiology. The telescope will be operated like the Hubble Space Telescope (HST) by the Space Telescope Science Institute, with all observing programs openly solicited and selected by peer review.The NGST scientific requirements originated with the report of the Dressler Committee HST & Beyond. The instruments recommended by the Ad Hoc Science Working Group (ASWG) include 1) a wide field near infrared (NIR) camera with an 8K2 detector array covering 0.6 - 5 μm, 2) a multi-object NIR spectrograph capable of simultaneously observing > 100 objects with a resolution of R (λ/δλ) = 1000, and 3) a combined mid-infrared (MIR) camera and spectrograph from 5-27 μm, with a resolution of R > 1500.
Superluminal Gravitational Microlensing Events In PKS 0537-441 And Prospects For Future Detections
Authors: Surpi G.C. , Romero G.E. , Vucetich H. 
Published: July 2016

The BL-Lac object PKS 0537-441 has recently displayed strong intraday variability at 1.42 GHz on time scales of ∼ 104 s. Such kind of variability is hardly consistent with an intrinsic-to-source origin, since apparent brightness temperatures higher than 1021 K are implied for the emitting region in the source.An alternative explanation for this ultra-rapid radio variability in PKS 0537-441 is developed based on gravitational microlensing of a superluminal component in the blazar caused by compact objects in the halo of an intervening galaxy. The mass of the microlenses is estimated and the blazar is proposed as a good candidate in a systematic search for extragalactic MACHOs.
Gravitational Microlensing By Random Motion Of Stars: Movie and Analysis of Light Curves
Authors: Wambsganss Joachim , Kundić Tomislav 
Published: July 2016

We present a quantitative analysis of the effect of microlensing caused by random motion of individual stars in a galaxy lensing a background quasar. We calculate a large number of magnification patterns for positions of the stars slightly offset from one frame to the next, and thus obtain light curves for fixed quasar and galaxy positions, only due to the change in the relative star positions. These light curves are analyzed to identify microlensing events, which are then classified with respect to height, duration, and slope. These random motion microlensing events are compared with the corresponding ones caused by the bulk motion of the galaxy.We find that microlensing events produced by random motion of stars are shorter, steeper, and more frequent than bulk motion events, assuming the velocity dispersion of the stars equals the bulk velocity of the galaxy. The reason for this difference is that in the case of random motion, caustics can move with an arbitrarily high velocity, producing very short events, whereas in the comparison case for bulk motion a microlensing event can never be shorter than it takes a fold caustic, which moves with the velocity of the lensing galaxy projected onto the quasar plane, to cross the quasar. An accompanying video illustrates these results. For three different values of the surface mass density κ, it shows time sequences of 1000 magnification patterns for slowly changing lens positions, together with the positions and velocity vectors of the microlensing stars. The full paper including the video can be found in Wambsganss & Kundić (1995). A short version of the video is available as an MPEG movie under anonymous ftp at astro.princeton.edu, in the directory jkw/microlensing/moving_stars.
A VLBA 15 GHz Small Separation Gravitational Lens Survey
Authors: Patnaik A.R. , Garrett M.A. , Polatidis A. , Bagri D. 
Published: July 2016

We have embarked on a 15 GHz VLBA survey of 1000 flat spectrum sources. We present the results from a 24 hour pilot observing run in which 72 sources were mapped. The primary aims of this project are:
–to search for small separation (1-150 mas) gravitational lens systems–to identify targets for current mm and anticipated Space VLBI programs–a morphological classification of compact radio sources at relatively high frequency with sub-mas resolution.
High-Resolution Imaging of BL LAC Host Galaxies
Authors: Heidt J. , Pursimo T. , Sillanpää A. , Takalo L.O. , Nilsson K. 
Published: July 2016

We present high-resolution imaging of the BL Lac objects 1ES 0229+200 (z = 0.14), Markarian 421 (z = 0.031) and the prototype BL Lac (z = 0.069). Our goal is to study the properties of the host galaxies of this enigmatic sources and to compare them with their non-actice counterparts. The observations were carried out with the Nordical Optical Telescope (NOT) at La Palma under sub-arcsecond seeing conditions (FWHM < 0.″8). The surface brightness profiles of the host galaxies were analyzed as described in Bender and Möllenhoff (A&A, 177, 71 (1987)). After masking the disturbing field stars/galaxies isophotes were fitted by ellipses down to 20.5 mag/arccsec2 in Markarian 421, 23.5 mag/arcsec2 in BL Lac and 25.5 mag/arcsec2 in 1ES 0229+200. Additionally, we analyzed the surface brightness profile of the companion of Markarian 421.The surface brightness profiles of the host galaxies were analyzed as described in Bender and Möllenhoff (A & A, 177, 71 (1987)). After masking the disturbing field stars/galaxies isophotes were fitted by ellipses down to 20.5 mag/arccsec2 in Markarian 421, 23.5 mag/arccsec2 in BL Lac and 25.5 mag/arccsec2 in 1ES 0229+200. Additionally, we analyzed the surface brightness profile of the companion of Markarian 421.
X-Ray Emission in Absence of Flares Related to Hα Activity and Type III Burst Production
Authors: Kane S. R. , Kreplin R. W. , Martres M. J. , Pick M. , Soru-Escaut I. 
Published: July 2016

(Solar Phys.). The relationship between Hα absorption features, type III radio bursts and soft X-ray emission has been examined in order to determine the characteristics of the particle acceleration process operating when a Hα-flare may or may not be detectable. The Hα observations were made by Meudon Observatory with a Hα telescope fitted with a 0.75 Å band pass Lyot filter. During a 10 s period, three pictures were obtained – one at the Hα line center, one at Hα + 0.75 Å and one at Hα −0.75 Å. This sequence of three pictures was repeated every one minute. Each picture covered a rectangular area 18 × 24 mm2, the diameter of the complete solar image being 38 mm on this scale. In addition, Meudon Hα films of the whole solar disc were also used. The X-ray observations were made with the University of California (Berkeley) experiment aboard the OGO-5 satellite and the NRL experiment aboard Solrad-9. The wavelength range covered was 0.5–20 Å. The type III radio data was obtained from two sources: The 169 MHz radio-heliograph at Nancay which provided east–west position of the radio burst on the Sun with an accuracy of ~ 1′ and the radio spectra measured by various ground based observatories. The findings are as follows:Transient Hα activity observed in the absence of reported flares is associated with production of type III radio and soft X-ray emission. Since such optical phenomena are much more frequent than flares themselves, we conclude that instabilities generating fast particles may be produced in the corona in a quasi-continuous way with coincident perturbations in the lower solar atmosphere.The soft X-ray component is not necessarily the direct product of fast particles, but is probably associated with some type of heating since both the soft X-ray emission and the Hα features exhibit a comparable evolution. The type III bursts, when they are produced, occur near the maximum of this perturbation.We identify the transient Hα activity (emission or absorption) with the existence of a metastable situation which may or may not lead to the triggering of a flare.
26. Photospheric magnetic fields
Authors: Babcock H. W. , Babcock H. D. 
Published: July 2016

Since 1952 a total of 635 magnetograms of the sun have been obtained in a systematic investigation of weak magnetic fields in the photosphere. The frequent records give the location, polarity, and intensity of weak fields down to a fraction of 1 gauss, although with resolution limited to about 0·04 of the solar diameter.Confirmation of previously reported results in 1954 comes from continuation of the series and from observations with a second, improved magnetograph on Mount Wilson. Three types of field pattern are found: (1) the poloidal field in high heliographic latitudes, consistently positive in the north, negative in the south, with intensity of the order of 1 gauss; (2) BM (bipolar magnetic) regions, often weak and extended, but which when strong are associated with plages, spots, flares, coronal emission, chromospheric fine structure, and filaments; and (3) UM (unipolar magnetic) regions, rather extended and weak, occurring in low latitudes, and associated in time with 27-day recurrent geomagnetic storms and cosmic-ray fluctuations. Attention is directed to the probable disposition of the magnetic flux in the high atmosphere and in interplanetary space, consistent with the observed magnetic areas and with the restriction div H = 0.Alfvén has argued that the interpretation of the small Zeeman displacements is meaningless and irrelevant because the rather strong turbulent fields presumed to prevail in granules might be coupled systematically, in respect to magnetic polarity, with the intensity of the absorption lines used for measurement. But this would produce a bias, with a shift of zero point of magnetic intensity, for all observed fields on the disk, and no such bias is observed. The measurements, while limited in resolution, are on an absolute scale, and show, for the ‘quiet sun’, vast areas with only small random fields no greater than a few tenths of 1 gauss.
The Devil in Nationalism: Indigenous Heritage and the Challenges of Decolonization
Authors: Bigenho Michelle , Stobart Henry 
Published: July 2016

Abstract:In 2006, Bolivians began living under their first indigenous president and undergoing an explicitly pro-indigenous “process of change,” alongside much rhetoric of indigenous autonomy and state “decolonization.” However, this article suggests that this same government’s twenty-first century policies regarding intangible heritage and “culture” hardly mark a departure from mid-twentieth-century mestizo-dominated liberal nationalist projects. Through the ethnography of disputed cultural claims to folklore, such as those with Peru involving the devil dance, this article examines how proprietary nationalism is experienced and expressed among certain Bolivians. For example, indignant internationally touring folklore workers imagine a hyperreal scarcity of specific expressions that have become framed as “cultural resources” for the nation. Indeed, it is common to hear propertied language employed when international disputes heat up, as cultural images circulate at high speeds through social networks and digital media. Within these media platforms, the visual sensory mode often overshadows aural and kinesthetic ones, as socially interwoven music and dance expressions fade into the background and stand-alone images of spectacular costumes move forward.
Multiple capsid-stabilizing interactions revealed in a high-resolution structure of an emerging picornavirus causing neonatal sepsis
Authors: Shakeel Shabih , Westerhuis Brenda M. , Domanska Ausra , Koning Roman I. , Matadeen Rishi , Koster Abraham J. , Bakker Arjen Q. , Beaumont Tim , Wolthers Katja C. , Butcher Sarah J. 
Published: July 2016

AbstractThe poorly studied picornavirus, human parechovirus 3 (HPeV3) causes neonatal sepsis with no therapies available. Our 4.3-Å resolution structure of HPeV3 on its own and at 15 Å resolution in complex with human monoclonal antibody Fabs demonstrates the expected picornavirus capsid structure with three distinct features. First, 25% of the HPeV3 RNA genome in 60 sites is highly ordered as confirmed by asymmetric reconstruction, and interacts with conserved regions of the capsid proteins VP1 and VP3. Second, the VP0 N terminus stabilizes the capsid inner surface, in contrast to other picornaviruses where on expulsion as VP4, it forms an RNA translocation channel. Last, VP1’s hydrophobic pocket, the binding site for the antipicornaviral drug, pleconaril, is blocked and thus inappropriate for antiviral development. Together, these results suggest a direction for development of neutralizing antibodies, antiviral drugs based on targeting the RNA–protein interactions and dissection of virus assembly on the basis of RNA nucleation.
Optimizing laser-driven proton acceleration from overdense targets
Authors: Stockem Novo A. , Kaluza M. C. , Fonseca R. A. , Silva L. O. 
Published: July 2016

AbstractWe demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range.
Deciphering the transcriptomic response of Fusarium verticillioides in relation to nitrogen availability and the development of sugarcane pokkah boeng disease
Authors: Lin Zhenyue , Wang Jihua , Bao Yixue , Guo Qiang , Powell Charles A. , Xu Shiqiang , Chen Baoshan , Zhang Muqing 
Published: July 2016

AbstractPokkah boeng, caused by Fusarium verticillioides, is a serious disease in sugarcane industry. The disease severity is related to the sugarcane genotype as well as environmental considerations, such as nitrogen application. The impact of the nitrogen source (ammonium sulfate, urea, or sodium nitrate) on sugarcane pokkah boeng disease and its pathogen was investigated in planta and fungal growth and sporulation production was measured in vitro. The results showed that ammonium and nitrate were beneficial to fungal mycelium growth, cell densities and sporulation, which enhanced the disease symptoms of sugarcane pokkah boeng compared to urea fertilization. A total of 1,779 transcripts out of 13,999 annotated genes identified from global transcriptomic analysis were differentially expressed in F. verticillioides CNO-1 grown in the different sources of nitrogen. These were found to be involved in nitrogen metabolism, transport and assimilation. Many of these genes were also associated with pathogenicity based on the PHI-base database. Several transcription factors were found to be associated with specific biological processes related to nitrogen utilization. Our results further demonstrated that nitrogen availability might play an important role in disease development by increasing fungal cell growth as well as influencing the expression of genes required for successful pathogenesis.
Andrographolide derivative AL-1 ameliorates TNBS-induced colitis in mice: involvement of NF-кB and PPAR-γ signaling pathways
Authors: Yang Yali , Yan Hui , Jing Mei , Zhang Zaijun , Zhang Gaoxiao , Sun Yewei , Shan Luchen , Yu Pei , Wang Yuqiang , Xu Lipeng 
Published: July 2016

AbstractAndrographolide is a traditional herb medicine, widely used in Asia for conditions involving inflammation. The andrographlide-lipoic acid conjugate, AL-1, has been found being able to alleviate inflammation in our previous reports. Although the anti-inflammatory activity of AL-1 contributes to its cytoprotective effects, whether AL-1 can improve inflammatory bowel disease (IBD) and the underlying mechanisms of its action remain largely unknown. In this study, we investigated the anti-inflammatory effects of AL-1 in C57BL/6 mice with trinitrobenzenesulfonic acid (TNBS)-induced colitis. The body weight loss and length change of colon after TNBS instillation were more severe than those in normal mice. AL-1 treatment led to significant reductions in disease activity index (DAI), macroscopic score and colon mucosa damage index (CMDI) associated with TNBS administration. AL-1 inhibited the inflammatory response via lowering the level of inflammatory cytokines and myeloperoxidase (MPO) activity. AL-1 attenuated the expression of p-p65, p-IκBα and COX-2 in the colitis mice. The alleviation of colon injury by AL-1 treatment was also evidenced by the increased expression of PPAR-γ. These results indicated that AL-1 could protect intestinal tract from the injury induced by TNBS in mice, suggesting that AL-1 may have potential in treatment for IBD.
Coral reef degradation is not correlated with local human population density
Authors: Bruno John F. , Valdivia Abel 
Published: July 2016

AbstractThe global decline of reef-building corals is understood to be due to a combination of local and global stressors. However, many reef scientists assume that local factors predominate and that isolated reefs, far from human activities, are generally healthier and more resilient. Here we show that coral reef degradation is not correlated with human population density. This suggests that local factors such as fishing and pollution are having minimal effects or that their impacts are masked by global drivers such as ocean warming. Our results also suggest that the effects of local and global stressors are antagonistic, rather than synergistic as widely assumed. These findings indicate that local management alone cannot restore coral populations or increase the resilience of reefs to large-scale impacts. They also highlight the truly global reach of anthropogenic warming and the immediate need for drastic and sustained cuts in carbon emissions.
Protein Kinase C Epsilon Promotes Cerebral Ischemic Tolerance Via Modulation of Mitochondrial Sirt5
Authors: Morris-Blanco Kahlilia C. , Dave Kunjan R. , Saul Isabel , Koronowski Kevin B. , Stradecki Holly M. , Perez-Pinzon Miguel A. 
Published: July 2016

AbstractSirtuin 5 (SIRT5) is a mitochondrial-localized NAD+-dependent lysine desuccinylase and a major regulator of the mitochondrial succinylome. We wanted to determine whether SIRT5 is activated by protein kinase C epsilon (PKCε)-mediated increases in mitochondrial Nampt and whether SIRT5 regulates mitochondrial bioenergetics and neuroprotection against cerebral ischemia. In isolated mitochondria from rat cortical cultures, PKCε activation increased SIRT5 levels and desuccinylation activity in a Nampt-dependent manner. PKCε activation did not lead to significant modifications in SIRT3 activity, the major mitochondrial lysine deacetylase. Assessments of mitochondrial bioenergetics in the cortex of wild type (WT) and SIRT5−/− mice revealed that SIRT5 regulates oxygen consumption in the presence of complex I, complex II and complex IV substrates. To explore the potential role of SIRT5 in PKCε-mediated protection, we compared WT and SIRT5−/− mice by employing both in vitro and in vivo ischemia paradigms. PKCε-mediated decreases in cell death following oxygen-glucose deprivation were abolished in cortical cultures harvested from SIRT5−/− mice. Furthermore, PKCε failed to prevent cortical degeneration following MCAO in SIRT5−/− mice. Collectively this demonstrates that SIRT5 is an important mitochondrial enzyme for protection against metabolic and ischemic stress following PKCε activation in the brain.