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Item Classification of evoked responses to inverted faces reveals both spatial and temporal cortical response abnormalities in Autism spectrum disorder(Elsevier BV, 2021-01) Nunes, Adonay S.; Mamashli, Fahimeh; Kozhemiako, Nataliia; Khan, Sheraz; McGuiggan, Nicole M.; Losh, Ainsley; Joseph, Robert M.; Ahveninen, Jyrki; Doesburg, Sam M.; Hämäläinen, Matti S.; Kenet, Tal; Harvard Medical School; Boston University; Simon Fraser University; Department of Neuroscience and Biomedical EngineeringThe neurophysiology of face processing has been studied extensively in the context of social impairments associated with autism spectrum disorder (ASD), but the existing studies have concentrated mainly on univariate analyses of responses to upright faces, and, less frequently, inverted faces. The small number of existing studies on neurophysiological responses to inverted face in ASD have used univariate approaches, with divergent results. Here, we used a data-driven, classification-based, multivariate machine learning decoding approach to investigate the temporal and spatial properties of the neurophysiological evoked response for upright and inverted faces, relative to the neurophysiological evoked response for houses, a neutral stimulus. 21 (2 females) ASD and 29 (4 females) TD participants ages 7 to 19 took part in this study. Group level classification accuracies were obtained for each condition, using first the temporal domain of the evoked responses, and then the spatial distribution of the evoked responses on the cortical surface, each separately. We found that classification of responses to inverted neutral faces vs. houses was less accurate in ASD compared to TD, in both the temporal and spatial domains. In contrast, there were no group differences in the classification of evoked responses to upright neutral faces relative to houses. Using the classification in the temporal domain, lower decoding accuracies in ASD were found around 120 ms and 170 ms, corresponding the known components of the evoked responses to faces. Using the classification in the spatial domain, lower decoding accuracies in ASD were found in the right superior marginal gyrus (SMG), intra-parietal sulcus (IPS) and posterior superior temporal sulcus (pSTS), but not in core face processing areas. Importantly, individual classification accuracies from both the temporal and spatial classifiers correlated with ASD severity, confirming the relevance of the results to the ASD phenotype.Item The Connection between the Radio Jet and the γ-ray Emission in the Radio Galaxy 3C 120 and the Blazar CTA 102(2016-09-27) Casadio, Carolina; Gómez, José; Jorstad, Svetlana G.; Marscher, Alan P.; Grandi, Paola; Larionov, Valeri M.; Lister, Matthew; Smith, Paul S.; Gurwell, Mark A.; Lähteenmäki, Anne; Agudo, Iván; Molina, Sol N.; Bala, Vishal; Joshi, Manasvita; Taylor, Brian; Williamson, Karen E.; Kovalev, Yuri; Savolainen, Tuomas; Pushkarev, Alexander B.; Arkharov, Arkady A.; Blinov, Dmitry A.; Borman, George A.; Di Paola, Andrea; Grishina, Tatiana S.; Hagen-Thorn, Vladimir A.; Itoh, Ryosuke; Kopatskaya, Evgenia N.; Larionova, Elena G.; Larionova, Liudmila V.; Morozova, Daria; Rastorgueva-Foi, Elizaveta; Sergeev, Sergey G.; Tornikoski, Merja; Troitsky, Ivan; Thum, Clemens; Wiesemeyer, Helmut; Max-Planck-Institut für Radioastronomie; CSIC; Boston University; Istituto Nazionale di Astrofisica (INAF); St. Petersburg State University; Purdue University; University of Arizona; Harvard-Smithsonian Center for Astrophysics; Metsähovi Radio Observatory; Pulkovo Observatory; Crimean Astrophysical Observatory; Osservatorio Astronomico di Roma; Hiroshima University; Instituto de Radioastronomía Milimétrica; Department of Radio Science and EngineeringWe present multi-wavelength studies of the radio galaxy 3C 120 and the blazar CTA 102 during unprecedented γ-ray flares for both sources. In both studies the analysis of γ-ray data has been compared with a series of 43 GHz VLBA images from the VLBA-BU-BLAZAR program, providing the necessary spatial resolution to probe the parsec scale jet evolution during the high energy events. To extend the radio dataset for 3C 120 we also used 15 GHz VLBA data from the MOJAVE sample. These two objects which represent very different classes of AGN, have similar properties during the γ-ray events. The γ-ray flares are associated with the passage of a new superluminal component through the mm VLBI core, but not all ejections of new components lead to γ-ray events. In both sources γ-ray events occurred only when the new components are moving in a direction closer to our line of sight. We locate the γ-ray dissipation zone a short distance from the radio core but outside of the broad line region, suggesting synchrotron self-Compton scattering as the probable mechanism for the γ-ray production.Item Erratic flaring of BL LAC in 2012-2013(2016-01-10) Wehrle, Ann E.; Grupe, Dirk; Jorstad, Svetlana G.; Marscher, Alan P.; Gurwell, Mark; Baloković, Mislav; Hovatta, Talvikki; Madejski, Grzegorz M.; Harrison, Fiona H.; Stern, Daniel; Space Science Institute; Morehead State University; St. Petersburg State University; Boston University; Harvard-Smithsonian Center for Astrophysics; Cahill Center for Astronomy and Astrophysics; SLAC National Accelerator Laboratory; California Institute of TechnologyBL Lac, the eponymous blazar, flared to historically high levels at millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We present observations made with Herschel, Swift, NuSTAR, Fermi, the Submillimeter Array, CARMA, and the VLBA in 2012-2013, including three months with nearly daily sampling at several wavebands. We have also conducted an intensive campaign of 30 hr with every-orbit observations by Swift and NuSTAR, accompanied by Herschel, and Fermi observations. The source was highly variable at all bands. Time lags, correlations between bands, and the changing shapes of the spectral energy distributions can be explained by synchrotron radiation and inverse Compton emission from nonthermal seed photons originating from within the jet. The passage of four new superluminal very long baseline interferometry knots through the core and two stationary knots about 4 pc downstream accompanied the high flaring in 2012-2013. The seed photons for inverse Compton scattering may arise from the stationary knots and from a Mach disk near the core where relatively slow-moving plasma generates intense nonthermal radiation. The 95 spectral energy distributions obtained on consecutive days form the most densely sampled, broad wavelength coverage for any blazar. The observed spectral energy distributions and multi-waveband light curves are similar to simulated spectral energy distributions and light curves generated with a model in which turbulent plasma crosses a conical shock with a Mach disk.Item Finding low-tension communities(Society for Industrial and Applied Mathematics (SIAM), 2017) Galbrun, Esther; Golshan, Behzad; Gionis, Aristides; Terzi, Evimaria; INRIA Nancy; Recruit Institute of Technology; Adj. Prof. Gionis Aris group; Boston University; Department of Computer Science; Chawla, Nitesh; Wang, WeiMotivated by applications that arise in online social media and collaboration networks, there has been a lot of work on community-search. In this class of problems, the goal is to find a subgraph that satisfies a certain connectivity requirement and contains a given collection of seed nodes. In this paper, we extend the community-search problem by associating each individual with a profile. The profile is a numeric score that quantifies the position of an individual with respect to a topic. We adopt a model where each individual starts with a latent profile and arrives to a conformed profile through a dynamic conformation process, which takes into account the individual's social interaction and the tendency to conform with one's social environment. In this framework, social tension arises from the differences between the conformed profiles of neighboring individuals as well as from the differences between individuals' conformed and latent profiles. Given a network of individuals, their latent profiles and this conformation process, we extend the community- search problem by requiring the output subgraphs to have low social tension. From the technical point of view, we study the complexity of this problem and propose algorithms for solving it effectively. Our experimental evaluation in a number of social networks reveals the efficacy and efficiency of our methods.Item Micro-scale distribution of CA4+ in ex vivo human articular cartilage detected with contrast-enhanced micro-computed tomography imaging(2017-08-31) Karhula, Sakari S.; Finnilä, Mikko A.; Freedman, Jonathan D.; Kauppinen, Sami; Valkealahti, Maarit; Lehenkari, Petri; Pritzker, Kenneth P.H.; Nieminen, Heikki J.; Snyder, Brian D.; Grinstaff, Mark W.; Saarakkala, Simo; University of Oulu; Boston University; University of Toronto; Department of Neuroscience and Biomedical Engineering; Harvard UniversityContrast-enhanced micro-computed tomography (CEμCT) with cationic and anionic contrast agents reveals glycosaminoglycan (GAG) content and distribution in articular cartilage (AC). The advantage of using cationic stains (e.g., CA4+) compared to anionic stains (e.g., Hexabrix®), is that it distributes proportionally with GAGs, while anionic stain distribution in AC is inversely proportional to the GAG content. To date, studies using cationic stains have been conducted with sufficient resolution to study its distributions on the macro-scale, but with insufficient resolution to study its distributions on the micro-scale. Therefore, it is not known whether the cationic contrast agents accumulate in extra/pericellular matrix and if they interact with chondrocytes. The insufficient resolution has also prevented to answer the question whether CA4+ accumulation in chondrons could lead to an erroneous quantification of GAG distribution with low-resolution μCT setups. In this study, we use high-resolution μCT to investigate whether CA4+ accumulates in chondrocytes, and further, to determine whether it affects the low-resolution ex vivo μCT studies of CA4+ stained human AC with varying degree of osteoarthritis. Human osteochondral samples were immersed in three different concentrations of CA4+ (3 mgI/ml, 6 mgI/ml, and 24 mgI/ml) and imaged with high-resolution μCT at several timepoints. Different uptake diffusion profiles of CA4+ were observed between the segmented chondrons and the rest of the tissue. While the X-ray -detected CA4+ concentration in chondrons was greater than in the rest of the AC, its contribution to the uptake into the whole tissue was negligible and in line with macro-scale GAG content detected from histology. The efficient uptake of CA4+ into chondrons and surrounding territorial matrix can be explained by the micro-scale distribution of GAG content. CA4+ uptake in chondrons occurred regardless of the progression stage of osteoarthritis in the samples and the relative difference between the interterritorial matrix and segmented chondron area was less than 4%. To conclude, our results suggest that GAG quantification with CEμCT is not affected by the chondron uptake of CA4+. This further confirms the use of CA4+ for macro-scale assessment of GAG throughout the AC, and highlight the capability of studying chondron properties in 3D at the micro scale.Item Multiwavelength observations of the blazar BL Lacertae(2017) Feng, Q.; Jorstad, S. G.; Marscher, A. P.; Lister, M. L.; Kovalev, Y. Y.; Pushkarev, A. B.; Savolainen, T.; Agudo, I.; Molina, S. N.; Gomez, J. L.; Larionov, V. M.; Borman, G. A.; Mokrushina, A. A.; Smith, P. S.; McGill University; Boston University; Purdue University; RAS - P.N. Lebedev Physics Institute; Metsähovi Radio Observatory; Instituto de Astrofísica de Andalucía; CSIC; St. Petersburg State University; Crimean Astrophysical Observatory; University of Arizona; Department of Electronics and NanoengineeringObservations of fast TeV γ-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV γ-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at >200 GeV measured with the 4-minute binned light curve is (4.2 ±0.6) × 10-6 photons m-2 s-1, or ∼180% the Crab Nebula flux. Variability in GeV γ-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV γ-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks.Item Multiwavelength observations of the blazar BL Lacertae: a new fast TeV gamma-ray flare(2017) Feng, Q.; Jorstad, S. G.; Marscher, A. P.; Lister, M. L.; Kovalev, Y. Y.; Pushkarev, A. B.; Savolainen, T.; Agudo, I.; Molina, S. N.; Gomez, J. L.; Larionov, V. M.; Borman, G. A.; Mokrushina, A. A.; Smith, P. S.; McGill University; Boston University; Purdue University; Lebedev Physical Institute; Crimean Astrophysical Observatory; Department of Electronics and Nanoengineering; Instituto de Astrofisica de Andalucia (Spain); ITMO University; University of ArizonaObservations of fast TeV $\gamma$-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV $\gamma$-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at $>$200 GeV measured with the 4-minute binned light curve is $(4.2 \pm 0.6) \times 10^{-6} \;\text{photons} \;\text{m}^{-2}\, \text{s}^{-1}$, or $\sim$180% the Crab Nebula flux. Variability in GeV $\gamma$-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV $\gamma$-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks.Item Radio and γ-Ray Activity in the Jet of the Blazar S5 0716+714(IOP Publishing Ltd., 2022-01-01) Kim, Dae Won; Kravchenko, Evgeniya V.; Kutkin, Alexander M.; Böttcher, Markus; Gómez, José L.; Gurwell, Mark; Jorstad, Svetlana G.; Lähteenmäki, Anne; Marscher, Alan P.; Ramakrishnan, Venkatessh; Tornikoski, Merja; Trippe, Sascha; Weaver, Zachary; Williamson, Karen E.; Seoul National University; Moscow Institute of Physics and Technology; RAS - P.N. Lebedev Physics Institute; North West University; CSIC - Institute of Astrophysics of Andalusia; Harvard University; Boston University; Department of Electronics and Nanoengineering; Universidad de Concepción; Metsähovi Radio ObservatoryWe explore the connection between the γ-ray and radio emission in the jet of the blazar 0716+714 by using 15, 37, and 230 GHz radio and 0.1-200 GeV γ-ray light curves spanning 10.5 yr (2008-2019). We find significant positive and negative correlations between radio and γ-ray fluxes in different time ranges. The time delays between radio and γ-ray emission suggest that the observed γ-ray flares originated from multiple regions upstream of the radio core, within a few parsecs from the central engine. Using time-resolved 43 GHz Very Long Baseline Array maps we identified 14 jet components moving downstream along the jet. Their apparent speeds range from 6c to 26c, and they show notable variations in their position angles upstream from the stationary component (∼0.53 mas from the core). The brightness temperature declines as a function of distance from the core according to a power law that becomes shallower at the location of the stationary component. We also find that the periods at which significant correlations between radio and γ-ray emission occur overlap with the times when the jet was oriented to the north. Our results indicate that the passage of a propagating disturbance (or shock) through the radio core and the orientation of the jet might be responsible for the observed correlation between the radio and γ-ray variability. We present a scenario that connects the positive correlation and the unusual anticorrelation by combining the production of a flare and a dip at γ-rays by a strong moving shock at different distances from the jet apex.Item Substitutions of short heterologous DNA segments of intragenomic or extragenomic origins produce clustered genomic polymorphisms(NATL ACAD SCIENCES, 2016-12-27) Harms, Klaus; Lunnan, Asbjørn; Hülter, Nils; Mourier, Tobias; Vinner, Lasse; Andam, Cheryl P.; Marttinen, Pekka; Fridholm, Helena; Hansen, Anders Johannes; Hanage, William P.; Nielsen, Kaare Magne; Willerslev, Eske; Johnsen, Pal Jarle; University of Copenhagen; Arctic University of Norway; Kiel University; Oslo Metropolitan University; Department of Computer Science; Statens Serum Institut; Boston University; GenØk – Centre for BiosafetyIn a screen for unexplained mutation events we identified a previously unrecognized mechanism generating clustered DNA polymorphisms such as microindels and cumulative SNPs. The mechanism, short-patch double illegitimate recombination (SPDIR), facilitates short single-stranded DNA molecules to invade and replace genomic DNA through two joint illegitimate recombination events. SPDIR is controlled by key components of the cellular genome maintenance machinery in the gram-negative bacterium Acinetobacter baylyi. The source DNA is primarily intragenomic but can also be acquired through horizontal gene transfer. The DNA replacements are nonreciprocal and locus independent. Bioinformatic approaches reveal occurrence of SPDIR events in the gram-positive human pathogen Streptococcus pneumoniae and in the human genome.Item Unraveling the Innermost Jet Structure of OJ 287 with the First GMVA + ALMA Observations(IOP Publishing Ltd., 2022-06-01) Zhao, Guang Yao; Gómez, José L.; Fuentes, Antonio; Krichbaum, Thomas P.; Traianou, Efthalia; Lico, Rocco; Cho, Ilje; Ros, Eduardo; Komossa, S.; Akiyama, Kazunori; Asada, Keiichi; Blackburn, Lindy; Britzen, Silke; Bruni, Gabriele; Crew, Geoffrey B.; Dahale, Rohan; Dey, Lankeswar; Gold, Roman; Gopakumar, Achamveedu; Issaoun, Sara; Janssen, Michael; Jorstad, Svetlana; Kim, Jae Young; Koay, Jun Yi; Kovalev, Yuri Y.; Koyama, Shoko; Lobanov, Andrei P.; Loinard, Laurent; Lu, Ru Sen; Markoff, Sera; Marscher, Alan P.; Martí-Vidal, Iván; Mizuno, Yosuke; Park, Jongho; Savolainen, Tuomas; Toscano, Teresa; CSIC - Institute of Astrophysics of Andalusia; Max Planck Institute for Radio Astronomy; Massachusetts Institute of Technology; Academia Sinica - Institute of Astronomy and Astrophysics; Harvard University; National Institute for Astrophysics; Tata Institute of Fundamental Research; University of Southern Denmark; Boston University; Niigata University; Chinese Academy of Sciences; University of Amsterdam; Universidad de Valencia; Department of Electronics and NanoengineeringWe present the first very long baseline interferometric (VLBI) observations of the blazar OJ 287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on 2017 April 2. The participation of phased ALMA has not only improved the GMVA north-south resolution by a factor of ∼3, but has also enabled fringe detections with signal-to-noise ratios up to 300 at baselines longer than 2 Gλ. The high sensitivity has motivated us to image the data with newly developed regularized maximum likelihood imaging methods, revealing the innermost jet structure with unprecedentedly high angular resolution. Our images reveal a compact and twisted jet extending along the northwest direction, with two bends within the inner 200 μas, resembling a precessing jet in projection. The component at the southeastern end shows a compact morphology and high brightness temperature, and is identified as the VLBI core. An extended jet feature that lies at ∼200 μas northwest of the core shows a conical shape, in both total and linearly polarized intensity, and a bimodal distribution of the linear polarization electric vector position angle. We discuss the nature of this feature by comparing our observations with models and simulations of oblique and recollimation shocks with various magnetic field configurations. Our high-fidelity images also enabled us to search for possible jet features from the secondary supermassive black hole (SMBH) and test the SMBH binary hypothesis proposed for this source.Item X-Ray, UV, and Radio Timing Observations of the Radio Galaxy 3C 120(2018-11-10) Marscher, Alan P.; Jorstad, Svetlana G.; Williamson, Karen E.; Lähteenmäki, Anne; Tornikoski, Merja; Hunter, John M.; Leidig, Katya A.; Mobeen, Muhammad Zain; Vera, Rafael J.C.; Chamani, Wara; Boston University; Department of Electronics and Nanoengineering; Metsähovi Radio Observatory; Anne Lähteenmäki GroupWe report the results of monitoring of the radio galaxy 3C 120 with the Neil Gehrels Swift Observatory, Very Long Baseline Array, and Metsähovi Radio Observatory. The UV-optical continuum spectrum and R-band polarization can be explained by a superposition of an inverted-spectrum source with a synchrotron component containing a disordered magnetic field. The UV-optical and X-ray light curves include dips and flares, while several superluminal knots appear in the parsec-scale jet. The recovery time of the second dip was longer at UV-optical wavelengths, in conflict with a model in which the inner accretion disk (AD) is disrupted during a dip and then refilled from outer to inner radii. We favor an alternative scenario in which occasional polar alignments of the magnetic field in the disk and corona cause the flux dips and formation of shocks in the jet. Similar to observations of Seyfert galaxies, intra-band time lags of flux variations are longer than predicted by the standard AD model. This suggests that scattering or some other reprocessing occurs. The 37 GHz light curve is well-correlated with the optical-UV variations, with a ∼20 day delay. A radio flare in the jet occurred in a superluminal knot 0.14 milliarcseconds downstream of the 43 GHz "core," which places the site of the preceding X-ray/UV/optical flare within the core 0.5-1.3 pc from the black hole. The inverted UV-optical flare spectrum can be explained by a nearly monoenergetic electron distribution with energy similar to the minimum energy inferred in the TeV γ-ray emitting regions of some BL Lacertae objects.
