Polarimetry of optically selected BL Lacertae candidates from the SDSS

NASA Astrophysics Data System (ADS)

Heidt, J.; Nilsson, K.

2011-05-01

We present and discuss polarimetric observations of 182 targets drawn from an optically selected sample of 240 probable BL Lac candidates out of the SDSS compiled by Collinge et al. (2005, AJ, 129, 2542). In contrast to most other BL Lac candidate samples extracted from the SDSS, its radio- and/or X-ray properties have not been taken into account for its derivation. Thus, because its selection is based on optical properties alone, it may be less prone to selection effects inherent in other samples derived at different frequencies, so it offers a unique opportunity to extract the first unbiased BL Lac luminosity function that is suitably large in size. We found 124 out of 182 targets (68%) to be polarized, 95 of the polarized targets (77%) to be highly polarized (>4%). The low-frequency peaked BL Lac candidates in the sample are on average only slightly more polarized than the high-frequency peaked ones. Compared to earlier studies, we found a high duty cycle in high polarization (˜ 66+2-14% to be >4% polarized) in high-frequency peaked BL Lac candidates. This may come from our polarization analysis, which minimizes the contamination by host galaxy light. No evidence of radio-quiet BL Lac objects in the sample was found. Our observations show that the probable sample of BL Lac candidates of Collinge et al. (2005) indeed contains a large number of bona fide BL Lac objects. High S/N spectroscopy and deep X-ray observations are required to construct the first luminosity function of optically selected BL Lac objects and to test more stringently for any radio-quiet BL Lac objects in the sample. Based on observations collected with the NTT on La Silla (Chile) operated by the European Southern Observatory in the course of the observing proposal 082.B-0133.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofisica de Andalucia (CSIC).Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/529/A162

The Second Catalog Of Active Galactic Nuclei Detected By The Fermi Large Area Telescope

DOE PAGES

Ackermann, M.

2011-12-02

The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently we define a clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lacs), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars ofmore » unknown type (i.e., with broad-band blazar characteristics but with no optical spectral measurement yet), eight misaligned AGNs, four narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types and two starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency < 10 14 Hz, about half of the BL Lacs have a synchrotron-peak frequency > 10 15 Hz. The 2LAC represents a significant improvement relative to the First LAT AGN Catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broad-band data. Various properties, such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.« less

THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Ajello, M.; Allafort, A.

The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 {gamma}-ray sources located at high Galactic latitudes (|b| > 10 Degree-Sign ) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a Clean Sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157more » candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency <10{sup 14} Hz, about half of the BL Lac objects have a synchrotron-peak frequency >10{sup 15} Hz. The 2LAC represents a significant improvement relative to the first LAT AGN catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broadband data. Various properties, such as {gamma}-ray fluxes and photon power-law spectral indices, redshifts, {gamma}-ray luminosities, variability, and archival radio luminosities and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.« less

Are some BL Lac objects artefacts of gravitational lensing?

NASA Technical Reports Server (NTRS)

Ostriker, J. P.; Vietri, M.

1985-01-01

It is proposed here that a significant fraction of BL Lac objects are optically violently variable quasars whose continuum emission has been greatly amplified, relative to the line emission, by pointlike gravitational lenses in intervening galaxies. Several anomalous physical and statistical properties of BL Lacs can be understood on the basis of this model, which is immediately testable on the basis of absorption line studies and by direct imaging.

Clustering environments of BL Lac objects

NASA Technical Reports Server (NTRS)

Wurtz, Ronald; Ellingson, Erica; Stocke, John T.; Yee, H. K. C.

1993-01-01

We report measurements of the amplitude of the BL Lac galaxy spatial covariance function, B(gb), for the fields of five BL Lacertae objects. We present evidence for rich clusters around MS 1207+39 and MS 1407+59, and confirm high richness for the cluster containing H0414+009. We discuss the ease of 3C 66 A and find evidence for a poor cluster based on an uncertain redshift of z = 0.444. These data suggest that at least some BL Lac objects are consistent with being FR 1 radio galaxies in rich clusters.

GLAST answers about high-energy peaked BL Lacs: double-humped {gamma}-ray peak and extreme accelerators?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costamante, L.; Aharonian, F.; Khangulyan, D.

2007-07-12

An often overlooked fact is that the MeV-GeV emission from High-energy peaked BL Lacs (HBL) is basically unknown: there are only 3 objects of this type among all EGRET identified blazars with measured spectra. GLAST will be able to measure the spectrum for many of them, in particular TeV-blazars, and surprises are expected. GLAST will tell if the {gamma}-ray peak in some HBL is actually a ''double peak'', as suggested by the comparison of EGRET and HESS data in PKS 2155-304, We also remind and argue that a new class of BL Lacs could exist, where particles are shock-accelerated nearmore » the maximum possible rate, characterized by the synchrotron emission peaking in the GLAST band (100 MeV - few GeV). Such objects could easily have escaped detection or identification so far, and could now be unveiled by GLAST.« less

BL Lacertae Objects

NASA Technical Reports Server (NTRS)

Stocke, John T.

1998-01-01

This grant has contributed to one of the original goals of the NAS/LTSA program, the goal of junior faculty development. Below I briefly summarize the following major results on BL Lacertae Objects that we have obtained. An invited talk on BL Lac Objects at IAU 175 "Extragalactic Radio Sources" at Bologna Italy in October 1995 summarized some of these results. A second invited talk in Oct 1998 at Green Bamk, WVA presented other BL Lac results at the conference entitled: "Highly Redshifted Radio Lines". We have used the EMSS sample to measure the X-ray luminosity function and cosmological evolution of BL Lacs. A new large sample of XBLs has been discovered.

The Radio-optical Spectra of BL Lacs and Possible Relatives

NASA Astrophysics Data System (ADS)

Dennett-Thorpe, J.

I consider the suggestion that, in a complete sample of flat-spectrum radio sources with available optical spectra (Marcha et al 1996), the strong emission line objects, or those with passive elliptical spectra are close relatives of the BL Lacs. New observations at four frequencies from 8 to 43GHz are presented, together with evidence for radio variability. Combined with other radio and optical data from the literature, we are able to construct the non-thermal SEDs and use these to address the questions: are the optically passive objects potentially `unrecognised' BL Lacs (either intrinsically weak and/or hidden by starlight)? What is the relationship between the surprising number of strong emission-line objects and the BL Lacs?

Finding the rarest objects in the universe: A new, efficient method for discovering BL Lacertae objects

NASA Technical Reports Server (NTRS)

Stocke, John; Perlman, Eric; Granados, Arno; Schachter, Jonathan; Elvis, Martin; Urry, Meg; Impey, Chris; Smith, Paul

1993-01-01

We present a new, efficient method for discovering new BL Lac Objects based upon the results of the Einstein Extended Medium Sensitivity Survey (EMSS). We have found that all x-ray selected BL Lacs are radio emitters, and further, that in a 'color-color' diagram (radio/optical and optical/x-ray) the BL Lac Objects occupy an area distinct from both radio loud quasars and the radio quiet QSOs and Seyferts which dominate x-ray selected samples. After obtaining radio counterparts via VLA 'snapshot' observations of a large sample of unidentified x-ray sources, the list of candidates is reduced. These candidates then can be confirmed with optical spectroscopy and/or polarimetry. Since greater than 70 percent of these sources are expected to be BL Lacs, the optical observations are very efficient. We have tested this method using unidentified sources found in the Einstein Slew Survey. The 162 Slew Survey x-ray source positions were observed with the VLA in a mixed B/C configuration at 6 cm resulting in 60 detections within 1.5 position error circle radii. These x-ray/optical/radio sources were then plotted, and 40 BL Lac candidates were identified. To date, 10 candidates have been spectroscopically observed resulting in 10 new BL Lac objects! Radio flux, optical magnitude, and polarization statistics (obtained in white light with the Steward Observatory 2.3 m CCD polarimeter) for each are given.

On the surface density of X-ray selected BL Lacertae objects

NASA Technical Reports Server (NTRS)

Maccacaro, T.; Gioia, I. M.; Maccagni, D.; Stocke, J. T.

1984-01-01

Only a handful of BL Lac objects have been found as a result of systematic optical identification of serendipitous Einstein X-ray sources. By combining the data from two flux-limited complete X-ray surveys (the HEAO 1 A-2 and the Einstein Observatory Medium Sensitivity Survey) the surface density of X-ray emitting BL Lac objects is evaluated as a function of their X-ray flux. It is found that a single power law is not an acceptable representation of the BL Lac objects' X-ray log N-log S. The number-flux relationship is consistent with the Euclidean slope at 'high' flux levels but shows a drastic flattnring below fluxes of the order of 10 to the -12th ergs per sq cm/s. The implications of this result are briefly discussed with respect to the luminosity function, the cosmological evolution, and the X-ray to optical flux ratio in BL Lac objects.

Low-luminosity Blazars in Wise: A Mid-infrared View of Unification

NASA Astrophysics Data System (ADS)

Plotkin, Richard M.; Anderson, S. F.; Brandt, W. N.; Markoff, S.; Shemmer, O.; Wu, J.

2012-01-01

We use the preliminary data release from the Wide-Field Infrared Survey Explorer (WISE) to perform the first statistical study on the mid-infrared (IR) properties of a large number ( 102) of BL Lac objects -- low-luminosity Active Galactic Nuclei (AGN) with a jet beamed toward the Earth. As expected, many BL Lac objects are so highly beamed that their jet synchrotron emission dominates their IR spectral energy distributions (SEDs), and the shape of their SEDs in the IR correlates well with SED peak frequency. In other BL Lac objects, the jet is not strong enough to completely dilute the rest of the AGN, and we do not see observational signatures of the dusty torus from these weakly beamed BL Lac objects. While at odds with simple unification, the missing torus is consistent with recent suggestions that BL Lac objects are fed by radiatively inefficient accretion flows. We discuss implications on the ``nature vs. nurture" debate for FR I and FR II galaxies, and also on the standard orientation-based AGN unification model.

Soft X-Ray Observations of a Complete Sample of X-Ray--selected BL Lacertae Objects

NASA Astrophysics Data System (ADS)

Perlman, Eric S.; Stocke, John T.; Wang, Q. Daniel; Morris, Simon L.

1996-01-01

We present the results of ROSAT PSPC observations of the X-ray selected BL Lacertae objects (XBLs) in the complete Einstein Extended Medium Sensitivity Survey (EM MS) sample. None of the objects is resolved in their respective PSPC images, but all are easily detected. All BL Lac objects in this sample are well-fitted by single power laws. Their X-ray spectra exhibit a variety of spectral slopes, with best-fit energy power-law spectral indices between α = 0.5-2.3. The PSPC spectra of this sample are slightly steeper than those typical of flat ratio-spectrum quasars. Because almost all of the individual PSPC spectral indices are equal to or slightly steeper than the overall optical to X-ray spectral indices for these same objects, we infer that BL Lac soft X-ray continua are dominated by steep-spectrum synchrotron radiation from a broad X-ray jet, rather than flat-spectrum inverse Compton radiation linked to the narrower radio/millimeter jet. The softness of the X-ray spectra of these XBLs revives the possibility proposed by Guilbert, Fabian, & McCray (1983) that BL Lac objects are lineless because the circumnuclear gas cannot be heated sufficiently to permit two stable gas phases, the cooler of which would comprise the broad emission-line clouds. Because unified schemes predict that hard self-Compton radiation is beamed only into a small solid angle in BL Lac objects, the steep-spectrum synchrotron tail controls the temperature of the circumnuclear gas at r ≤ 1018 cm and prevents broad-line cloud formation. We use these new ROSAT data to recalculate the X-ray luminosity function and cosmological evolution of the complete EMSS sample by determining accurate K-corrections for the sample and estimating the effects of variability and the possibility of incompleteness in the sample. Our analysis confirms that XBLs are evolving "negatively," opposite in sense to quasars, with Ve/Va = 0.331±0.060. The statistically significant difference between the values for X-ray and radio-selected BL Lac objects remains a difficulty for models which unify these two types of objects. We have identified one addition to the sample, so that the sample now has 23 objects. We find no evidence for a substantial number of unidentified low-luminosity BL Lac objects hidden in our sample, as had been suggested by Browne & Marcha (1993) although a few such objects may be present.

BL Lacertae Objects Beyond Redshift 1.3 - UV-to-NIR Photometry and Photometric Redshift for Fermi/LAT Blazars

NASA Technical Reports Server (NTRS)

Rau, A.; Schady, P.; Greiner, J.; Salvato, M.; Ajello, M.; Bottacini, E.; Gehrels, N.; Afonso, P. M. J.; Elliott, J.; Filgas, R.;

VizieR Online Data Catalog: The CLASS BL Lac sample (Marcha+, 2013)

NASA Astrophysics Data System (ADS)

Marcha, M. J. M.; Caccianiga, A.

2014-04-01

This paper presents a new sample of BL Lac objects selected from a deep (30mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey). The sample is one of the largest well-defined samples in the low-power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the radio luminosity function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the luminosity function which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study, we extend for the first time the BL Lac RLF down to very low radio powers ~1022W/Hz, i.e. two orders of magnitude below the RLF currently available in the literature. In the process, we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low-luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at L~1025W/Hz in agreement with the predictions of the beaming model. (1 data file).

The environment of x ray selected BL Lacs: Host galaxies and galaxy clustering

NASA Technical Reports Server (NTRS)

Wurtz, Ron; Stocke, John T.; Ellingson, Erica; Yee, Howard K. C.

1993-01-01

Using the Canada-France-Hawaii Telescope, we have imaged a complete, flux-limited sample of Einstein Medium Sensitivity Survey BL Lacertae objects in order to study the properties of BL Lac host galaxies and to use quantitative methods to determine the richness of their galaxy cluster environments.

X-Ray Variability of BL Lac Objects

NASA Astrophysics Data System (ADS)

McHardy, Ian

I present an overview of the X-ray temporal and spectral variability of BL Lacs on both short and long timescales. The previously observed behaviour of short (~days) flares superimposed on a relatively steady `quiescent' level is still broadly correct. However, for the brighter BL Lacs, the well sampled lightcurves from the RXTE ASM show that the `quiescent' level also varies considerably on timescales of ~100 days in a manner similar to that seen in Optically Violently Variable Quasars (OVVs) such as 3C279 and 3C273. Possible reasons for this behaviour are discussed. For the large majority of BL Lacs the soft and medium energy X-ray bands are dominated by synchrotron emission and, unlike the case of OVVs, the emission mechanism is not in doubt. Most interest then centres on the structure of the emitting region, and the electron acceleration processes, particularly during outbursts. That structure, and the acceleration processes, can be investigated by consideration of the spectral variability during flares, which is not simple. I review the observations of spectral variability and consider the evidence for and against homogeneous models. I also briefly compare the X-ray spectral variability of BL Lacs with that of OVVs such as 3C273.

X-Ray and TeV Gamma-Ray Emission from Parallel Electron-Positron or Electron-Proton Beams in BL Lacertae Objects

NASA Astrophysics Data System (ADS)

Krawczynski, H.

2007-04-01

In this paper we discuss models of the X-ray and TeV γ-ray emission from BL Lac objects based on parallel electron-positron or electron-proton beams that form close to the central black hole, due to the strong electric fields generated by the accretion disk and possibly also by the black hole itself. Fitting the energy spectrum of the BL Lac object Mrk 501, we obtain tight constraints on the beam properties. Launching a sufficiently energetic beam requires rather strong magnetic fields close to the black hole (~100-1000 G). However, the model fits imply that the magnetic field in the emission region is only ~0.02 G. Thus, the particles are accelerated close to the black hole and propagate a considerable distance before instabilities trigger the dissipation of energy through synchrotron and self-Compton emission. We discuss various approaches to generate enough power to drive the jet and, at the same time, to accelerate particles to ~20 TeV energies. Although the parallel beam model has its own problems, it explains some of the long-standing problems that plague models based on Fermi-type particle acceleration, such as the presence of a very high minimum Lorentz factor of accelerated particles. We conclude with a brief discussion of the implications of the model for the difference between the processes of jet formation in BL Lac-type objects and those in quasars.

Time-dependent inhomogeneous jet models for BL Lac objects

NASA Technical Reports Server (NTRS)

Marlowe, A. T.; Urry, C. M.; George, I. M.

1992-01-01

Relativistic beaming can explain many of the observed properties of BL Lac objects (e.g., rapid variability, high polarization, etc.). In particular, the broadband radio through X-ray spectra are well modeled by synchrotron-self Compton emission from an inhomogeneous relativistic jet. We have done a uniform analysis on several BL Lac objects using a simple but plausible inhomogeneous jet model. For all objects, we found that the assumed power-law distribution of the magnetic field and the electron density can be adjusted to match the observed BL Lac spectrum. While such models are typically unconstrained, consideration of spectral variability strongly restricts the allowed parameters, although to date the sampling has generally been too sparse to constrain the current models effectively. We investigate the time evolution of the inhomogeneous jet model for a simple perturbation propagating along the jet. The implications of this time evolution model and its relevance to observed data are discussed.

Time-dependent inhomogeneous jet models for BL Lac objects

NASA Astrophysics Data System (ADS)

Marlowe, A. T.; Urry, C. M.; George, I. M.

1992-05-01

Relativistic beaming can explain many of the observed properties of BL Lac objects (e.g., rapid variability, high polarization, etc.). In particular, the broadband radio through X-ray spectra are well modeled by synchrotron-self Compton emission from an inhomogeneous relativistic jet. We have done a uniform analysis on several BL Lac objects using a simple but plausible inhomogeneous jet model. For all objects, we found that the assumed power-law distribution of the magnetic field and the electron density can be adjusted to match the observed BL Lac spectrum. While such models are typically unconstrained, consideration of spectral variability strongly restricts the allowed parameters, although to date the sampling has generally been too sparse to constrain the current models effectively. We investigate the time evolution of the inhomogeneous jet model for a simple perturbation propagating along the jet. The implications of this time evolution model and its relevance to observed data are discussed.

Constraining the red shifts of TeV BL Lac objects

NASA Astrophysics Data System (ADS)

Qin, Longhua; Wang, Jiancheng; Yan, Dahai; Yang, Chuyuan; Yuan, Zunli; Zhou, Ming

2018-01-01

We present a model-dependent method to estimate the red shifts of three TeV BL Lac objects (BL Lacs) through fitting their (quasi-)simultaneous multi-waveband spectral energy distributions (SEDs) with a one-zone leptonic synchrotron self-Compton model. Considering the impact of electron energy distributions (EEDs) on the results, we use three types of EEDs to fit the SEDs: a power-law EED with exponential cut-off (PLC), a log-parabola (PLLP) EED and the broken power-law (BPL) EED. We also use a parameter α to describe the uncertainties of the extragalactic background light models, as in Abdo et al. We then use a Markov chain Monte Carlo method to explore the multi-dimensional parameter space and obtain the uncertainties of the model parameters based on the observational data. We apply our method to obtain the red shifts of three TeV BL Lac objects in the marginalized 68 per cent confidence, and find that the PLC EED does not fit the SEDs. For 3C66A, the red shift is 0.14-0.31 and 0.16-0.32 in the BPL and PLLP EEDs. For PKS1424+240, the red shift is 0.55-0.68 and 0.55-0.67 in the BPL and PLLP EEDs. For PG1553+113, the red shift is 0.22-0.48 and 0.22-0.39 in the BPL and PLLP EEDs. We also estimate the red shift of PKS1424+240 in the high stage to be 0.46-0.67 in the PLLP EED, roughly consistent with that in the low stage.

OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. V. TNG, KPNO, AND OAN OBSERVATIONS OF BLAZAR CANDIDATES OF UNCERTAIN TYPE IN THE NORTHERN HEMISPHERE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Álvarez Crespo, N.; Massaro, F.; Masetti, N.

The extragalactic γ-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei. Many of the γ-ray sources included in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs) because there are no optical spectra available in the literature to confirm their nature. In 2013, we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the unidentified γ-ray sources to confirm their blazar nature. Whenever possible we also determine their redshifts. Here, we present the results of the observations carried out inmore » the northern hemisphere in 2013 and 2014 at the Telescopio Nazionale Galileo, Kitt Peak National Observatory, and Observatorio Astronómico Nacional in San Pedro Mártir. In this paper, we describe the optical spectra of 25 sources. We confirmed that all of the 15 BCUs observed in our campaign and included in our sample are blazars and we estimated the redshifts for three of them. In addition, we present the spectra for three sources classified as BL Lacs in the literature but with no optical spectra available to date. We found that one of them is a quasar (QSO) at a redshift of z = 0.208 and the other two are BL Lacs. Moreover, we also present seven new spectra for known blazars listed in the Roma-BZCAT that have an uncertain redshift or are classified as BL Lac candidates. We found that one of them, 5BZB J0724+2621, is a “changing look” blazar. According to the spectrum available in the literature, it was classified as a BL Lac, but in our observation we clearly detected a broad emission line that led us to classify this source as a QSO at z = 1.17.« less

Using the Markov chain Monte Carlo method to study the physical properties of GeV-TeV BL Lac objects

NASA Astrophysics Data System (ADS)

Qin, Longhua; Wang, Jiancheng; Yang, Chuyuan; Yuan, Zunli; Mao, Jirong; Kang, Shiju

2018-01-01

We fit the spectral energy distributions (SEDs) of 46 GeV-TeV BL Lac objects in the frame of leptonic one-zone synchrotron self-Compton (SSC) model and investigate the physical properties of these objects. We use the Markov chain Monte Carlo (MCMC) method to obtain the basic parameters, such as magnetic field (B), the break energy of the relativistic electron distribution (γ ^' }b), and the electron energy spectral index. Based on the modeling results, we support the following scenarios for GeV-TeV BL Lac objects. (1) Some sources have large Doppler factors, implying other radiation mechanism should be considered. (2) Compared with flat spectrum quasars (FSRQs), GeV-TeV BL Lac objects have weaker magnetic fields and larger Doppler factors, which cause the ineffective cooling and shift the SEDs to higher bands. Their jet powers are around 4.0 × 1045 erg s-1, compared with radiation power, 5.0 × 1042 erg s-1, indicating that only a small fraction of jet power is transformed into the emission power. (3) For some BL Lacs with large Doppler factors, their jet components could have two substructures, e.g., the fast core and the slow sheath. For most GeV-TeV BL Lacs, Kelvin-Helmholtz instabilities are suppressed by their higher magnetic fields, leading to micro-variability or intro-day variability in the optical bands. (4) Combined with a sample of FSRQs, an anti-correlation between the peak luminosity, Lpk, and the peak frequency, νpk, is obtained, favoring the blazar sequence scenario. In addition, an anti-correlation between the jet power, Pjet, and the break Lorentz factor, γb, also supports the blazar sequence.

New High-z BL Lacs Using the Photometric Method with Swift and SARA

NASA Astrophysics Data System (ADS)

Kaur, A.; Rau, A.; Ajello, M.; Domínguez, A.; Paliya, V. S.; Greiner, J.; Hartmann, D. H.; Schady, P.

2018-06-01

BL Lacertae (BL Lac) objects are prominent members of the third Fermi Large Area Telescope catalog of γ-ray sources. Half of the members of the BL Lac population (∼300) lack redshift measurements, which is due to the absence of lines in their optical spectra, thereby making it difficult to utilize spectroscopic methods. Our photometric dropout technique can be used to establish the redshift for a fraction of these sources. This work employed six filters mounted on the Swift-UVOT and four optical filters on two telescopes, the 0.65 m SARA-CTIO in Chile and 1.0 m SARA-ORM in the Canary Islands, Spain. A sample of 15 sources was extracted from the Swift archival data for which six filter UVOT observations were conducted. By complementing the Swift observations with the SARA ones, we were able to discover two high-redshift sources: 3FGL J1155.4-3417 and 3FGL J1156.7–2250 at z={1.83}-0.13+0.10 and z={1.73}-0.19+0.11, respectively, resulting from the dropouts in the power-law template fits to these data. The discoveries add to the important (26 total) sample of high-redshift BL Lacs. While the sample of high-z BL Lacs is still rather small, these objects do not seem to fit well within known schemes of the blazar population and represent the best probes of the extragalactic background light.

Optical polarimetry and photometry of X-ray selected BL Lacertae objects

NASA Technical Reports Server (NTRS)

Jannuzi, Buell T.; Smith, Paul S.; Elston, Richard

1993-01-01

We present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects. The monitored objects include a complete sample drawn from the Einstein Extended Medium Sensitivity Survey. We confirm the BL Lac identifications for 15 of these 22 objects. We include descriptions of the objects and samples in our monitoring program and of the existing complete samples of BL Lac objects, highly polarized quasars, optically violent variable quasars, and blazars.

A KPC-scale X-ray jet in the BL LAC Source S5 2007+777

NASA Technical Reports Server (NTRS)

Sambruna, Rita; Maraschi, Laura; Tavecchio, Fabrizio

2008-01-01

The BL Lac S3 2007++777, a classical radio-selected BL Lac from the sample of Stirkel et al. exhibiting an extended (19") radio jet. was observed with Chandra revealing an X-ray jet with simi1ar morphology. The hard X-ray spectrum and broad band SED is consistent with an IC/CMB origin for the X-ray emission, implying a highly relativistic flow at small angle to the line of sight with an unusually large deprojected length, 300 kpc. A structured jet consisting of a fast spine and slow wall is consistent with the observations.

RADIO-WEAK BL LAC OBJECTS IN THE FERMI ERA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; Marchesini, E. J.; D’Abrusco, R.

2017-01-10

The existence of “radio-weak BL Lac objects” (RWBLs) has been an open question, and has remained unsolved since the discovery that quasars could be radio-quiet or radio-loud. Recently, several groups identified RWBL candidates, mostly found while searching for low-energy counterparts of the unidentified or unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broadband spectral energy distribution, and their classification is mainly based on a featureless optical spectra. Motivated bymore » the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs, and BL Lacs using the [3.4]–[4.6]–[12] μ m color–color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with that of the BL Lac population.« less

Radio-weak BL Lac Objects in the Fermi Era

NASA Astrophysics Data System (ADS)

Massaro, F.; Marchesini, E. J.; D'Abrusco, R.; Masetti, N.; Andruchow, I.; Smith, Howard A.

2017-01-01

The existence of “radio-weak BL Lac objects” (RWBLs) has been an open question, and has remained unsolved since the discovery that quasars could be radio-quiet or radio-loud. Recently, several groups identified RWBL candidates, mostly found while searching for low-energy counterparts of the unidentified or unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broadband spectral energy distribution, and their classification is mainly based on a featureless optical spectra. Motivated by the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs, and BL Lacs using the [3.4]-[4.6]-[12] μm color-color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with that of the BL Lac population.

Transcriptomic Analysis of Lung Tissue from Cigarette Smoke-Induced Emphysema Murine Models and Human Chronic Obstructive Pulmonary Disease Show Shared and Distinct Pathways.

PubMed

Yun, Jeong H; Morrow, Jarrett; Owen, Caroline A; Qiu, Weiliang; Glass, Kimberly; Lao, Taotao; Jiang, Zhiqiang; Perrella, Mark A; Silverman, Edwin K; Zhou, Xiaobo; Hersh, Craig P

2017-07-01

Although cigarette smoke (CS) is the primary risk factor for chronic obstructive pulmonary disease (COPD), the underlying molecular mechanisms for the significant variability in developing COPD in response to CS are incompletely understood. We performed lung gene expression profiling of two different wild-type murine strains (C57BL/6 and NZW/LacJ) and two genetic models with mutations in COPD genome-wide association study genes (HHIP and FAM13A) after 6 months of chronic CS exposure and compared the results to human COPD lung tissues. We identified gene expression patterns that correlate with severity of emphysema in murine and human lungs. Xenobiotic metabolism and nuclear erythroid 2-related factor 2-mediated oxidative stress response were commonly regulated molecular response patterns in C57BL/6, Hhip +/- , and Fam13a -/- murine strains exposed chronically to CS. The CS-resistant Fam13a -/- mouse and NZW/LacJ strain revealed gene expression response pattern differences. The Fam13a -/- strain diverged in gene expression compared with C57BL/6 control only after CS exposure. However, the NZW/LacJ strain had a unique baseline expression pattern, enriched for nuclear erythroid 2-related factor 2-mediated oxidative stress response and xenobiotic metabolism, and converged to a gene expression pattern similar to the more susceptible wild-type C57BL/6 after CS exposure. These results suggest that distinct molecular pathways may account for resistance to emphysema. Surprisingly, there were few genes commonly modulated in mice and humans. Our study suggests that gene expression responses to CS may be largely species and model dependent, yet shared pathways could provide biologically significant insights underlying individual susceptibility to CS.

STRUCTURED JETS IN BL LAC OBJECTS: EFFICIENT PeV NEUTRINO FACTORIES?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavecchio, Fabrizio; Ghisellini, Gabriele; Guetta, Dafne

2014-09-20

The origin of high-energy neutrinos (0.1–1 PeV range) detected by IceCube remains a mystery. In this work, we explore the possibility that efficient neutrino production can occur in structured jets of BL Lac objects, characterized by a fast inner spine surrounded by a slower layer. This scenario has been widely discussed in the framework of the high-energy emission models for BL Lac objects and radio galaxies. One of the relevant consequences of a velocity structure is the enhancement of the inverse Compton emission caused by the radiative coupling of the two zones. We show that a similar boosting could occurmore » for the neutrino output of the spine through the photo-meson reaction of high-energy protons scattering off the amplified soft target photon field of the layer. Assuming the local density and the cosmological evolution of γ-ray BL Lac object derived from Fermi Large Area Telescope data, we calculate the expected diffuse neutrino intensity, which can match the IceCube data for a reasonable choice of parameters.« less

An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes?

NASA Astrophysics Data System (ADS)

Bonnoli, G.; Tavecchio, F.; Ghisellini, G.; Sbarrato, T.

2015-07-01

High-energy observations of extreme BL Lac objects, such as 1ES 0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic field estimate. However, the number of these extreme highly peaked BL Lac objects (EHBL) is still rather small. Aiming at increase their number, we selected a group of EHBL candidates starting from the BL Lac sample of Plotkin et al. (2011), considering those undetected (or only barely detected) by the Large Area Telescope onboard Fermi and characterized by a high X-ray versus radio flux ratio. We assembled the multiwavelength spectral energy distribution of the resulting nine sources, profiting of publicly available archival observations performed by Swift, GALEX, and Fermi satellites, confirming their nature. Through a simple one-zone synchrotron self-Compton model we estimate the expected very high energy flux, finding that in the majority of cases it is within the reach of present generation of Cherenkov arrays or of the forthcoming Cherenkov Telescope Array.

Active galaxies observed during the Extreme Ultraviolet Explorer all-sky survey

NASA Technical Reports Server (NTRS)

Marshall, H. L.; Fruscione, A.; Carone, T. E.

1995-01-01

We present observations of active galactic nuclei (AGNs) obtained with the Extreme Ultraviolet Explorer (EUVE) during the all-sky survey. A total of 13 sources were detected at a significance of 2.5 sigma or better: seven Seyfert galaxies, five BL Lac objects, and one quasar. The fraction of BL Lac objects is higher in our sample than in hard X-ray surveys but is consistent with the soft X-ray Einstein Slew Survey, indicating that the main reason for the large number of BL Lac objects in the extreme ulktraviolet (EUV) and soft X-ray bands is their steeper X-ray spectra. We show that the number of AGNs observed in both the EUVE and ROSAT Wide Field Camera surveys can readily be explained by modelling the EUV spectra with a simple power law in the case of BL Lac objects and with an additional EUV excess in the case of Seyferts and quasars. Allowing for cold matter absorption in Seyfert galaxy hosts drive up the inferred average continuum slope to 2.0 +/- 0.5 (at 90% confidence), compared to a slope of 1.0 usually found from soft X-ray data. If Seyfert galaxies without EUV excesses form a significant fraction of the population, then the average spectrum of those with bumps should be even steeper. We place a conservative limit on neutral gas in BL Lac objects: N(sub H) less than 10(exp 20)/sq cm.

The BL LAC phenomenon: X-ray observations of transition objects and determination of the x-ray spectrum of a complete sample of flat-spectrum radio sources

NASA Technical Reports Server (NTRS)

Worrall, Diana M.

1994-01-01

This report summarizes the activities related to two ROSAT investigations: (1) x-ray properties of radio galaxies thought to contain BL Lac type nuclei; and (2) x-ray spectra of a complete sample of flat-spectrum radio sources. The following papers describing the research are provided as attachments: Multiple X-ray Emission Components in Low Power Radio Galaxies; New X-ray Results on Radio Galaxies; Analysis Techniques for a Multiwavelength Study of Radio Galaxies; Separation of X-ray Emission Components in Radio Galaxies; X-ray Emission in Powerful Radio Galaxies and Quasars; Extended and Compact X-ray Emission in Powerful Radio Galaxies; and X-ray Spectra of a Complete Sample of Extragalactic Core-dominated Radio Sources.

Effective spectral index properties for Fermi blazars

NASA Astrophysics Data System (ADS)

Yang, JiangHe; Fan, JunHui; Liu, Yi; Zhang, YueLian; Tuo, ManXian; Nie, JianJun; Yuan, YuHai

2018-05-01

Blazars are a special subclass of active galactic nuclei with extreme observation properties. This subclass can be divided into two further subclasses of flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs) according to their emission line features. To compare the spectral properties of FSRQs and BL Lacs, the 1.4 GHz radio, optical R-band, 1 keV X-ray, and 1 GeV γ-ray flux densities for 1108 Fermi blazars are calculated to discuss the properties of the six effective spectral indices of radio to optical ( α RO), radio to X-ray ( α RX), radio to γ ray ( α Rγ), optical to X-ray ( α OX), optical to γ ray ( α Oγ), and X-ray to γ ray ( α Xγ). The main results are as follows: For the averaged effective spectral indices, \\overline {{α _{OX}}} > \\overline {{α _{Oγ }}} > \\overline {{α _{Xγ }}} > \\overline {{α _{Rγ }}} > \\overline {{α _{RX}}} > \\overline {{α _{RO}}} for samples of whole blazars and BL Lacs; \\overline {{α _{Xγ }}} ≈ \\overline {{α _{Rγ }}} ≈ \\overline {{α _{RX}}} for FSRQs and low-frequency-peaked BL Lacs (LBLs); and \\overline {{α _{OX}}} ≈ \\overline {{α _{Oγ }}} ≈ \\overline {{α _{Xγ }}} for high-synchrotron-frequency-peaked BL Lacs (HBLs). The distributions of the effective spectral indices involving optical emission ( α RO, α OX, and α Oγ) for LBLs are different from those for FSRQs, but if the effective spectral index does not involve optical emission ( α RX, α Rγ, and α Xγ), the distributions for LBLs and FSRQs almost come from the same parent population. X-ray emissions from blazars include both synchrotron and inverse Compton (IC) components; the IC component for FSRQs and LBLs accounts for a larger proportion than that for HBLs; and the radiation mechanism for LBLs is similar to that for FSRQs, but the radiation mechanism for HBLs is different from that for both FSRQs and LBLs in X-ray bands. The tendency of α Rγ decreasing from LBLs to HBLs suggests that the synchrotron self-Compton model explains the main process for highly energetic γ rays in BL Lacs.

Very high energy observations of the BL Lac objects 3C 66A and OJ 287

NASA Astrophysics Data System (ADS)

Lindner, T.; Hanna, D. S.; Kildea, J.; Ball, J.; Bramel, D. A.; Carson, J.; Covault, C. E.; Driscoll, D.; Fortin, P.; Gingrich, D. M.; Jarvis, A.; Mueller, C.; Mukherjee, R.; Ong, R. A.; Ragan, K.; Scalzo, R. A.; Williams, D. A.; Zweerink, J.

2007-11-01

Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we have observed the BL Lac objects 3C 66A and OJ 287. These are members of the class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three LBLs predicted by Costamante and Ghisellini [L. Costamante, G. Ghisellini, Astron. Astrophys. 384 (2002) 56] to be potential sources of very high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae, has recently been detected by the MAGIC collaboration [J. Albert et al., arXiv:astro-ph/0703084v1 (2007)]. Our observations have not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits assume a Crab-like energy spectrum with an effective energy threshold of 185 GeV.

γ-Ray And Parsec-Scale Jet Properties Of A Complete Sample Of Blazars From The Mojave Program

DOE PAGES

Lister, M. L.

2011-11-02

We investigate the Fermi LAT -ray and 15 GHz VLBA radio properties of a joint -ray- and radio-selected sample of AGNs obtained during the first 11 months of the Fermi mission (2008 Aug 4 - 2009 Jul 5). Our sample contains the brightest 173 AGNs in these bands above declination -30° during this period, and thus probes the full range of -ray loudness ( -ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least four orders ofmagnitude, reflecting a wide range of spectral energy distribution (SED) parameters in the bright blazar population. Themore » BL Lac objects, however, display a linear correlation of increasing -ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class. The synchrotron self-Compton model is favored for the -ray emission in these BL Lacs over external seed photon models, since the latter predict a dependence of Compton dominance on Doppler factor that would destroy any observed synchrotron SED peak - -ray loudness correlation. The high-synchrotron peaked (HSP) BL Lac objects are distinguished by lower than average radio core brightness temperatures, and none display large radio modulation indices or high linear core polarization levels. No equivalent trends are seen for the flat-spectrum radio quasars (FSRQ) in our sample. Given the association of such properties with relativistic beaming, we suggest that the HSP BL Lacs have generally lower Doppler factors than the lower-synchrotron peaked BL Lacs or FSRQs in our sample.« less

Gamma-Ray and Parsec-Scale Jet Properties of a Complete Sample of Blazars from the MOJAVE Program

NASA Technical Reports Server (NTRS)

Lister, M.L.; Aller, M.; Aller, H.; Hovatta, T.; Kellermann, K. I.; Kovalev, Y. Y.; Meyer, E. T.; Pushkarev, A. B.; Ros, E.; Ackermann, M.;

X-Ray Spectral Variability Signatures of Flares in BL Lac Objects

NASA Technical Reports Server (NTRS)

Boettcher, Markus; Chiang, James; White, Nicholas E. (Technical Monitor)

2002-01-01

We are presenting a detailed parameter study of the time-dependent electron injection and kinematics and the self-consistent radiation transport in jets of intermediate and low-frequency peaked BL Lac objects. Using a time-dependent, combined synchrotron-self-Compton and external-Compton jet model, we study the influence of variations of several essential model parameters, such as the electron injection compactness, the relative contribution of synchrotron to external soft photons to the soft photon compactness, the electron- injection spectral index, and the details of the time profiles of the electron injection episodes giving rise to flaring activity. In the analysis of our results, we focus on the expected X-ray spectral variability signatures in a region of parameter space particularly well suited to reproduce the broadband spectral energy distributions of intermediate and low-frequency peaked BL Lac objects. We demonstrate that SSC- and external-Compton dominated models for the gamma-ray emission from blazars are producing significantly different signatures in the X-ray variability, in particular in the soft X-ray light curves and the spectral hysteresis at soft X-ray energies, which can be used as a powerful diagnostic to unveil the nature of the high-energy emission from BL Lac objects.

The NuSTAR view on Hard-TeV BL Lacs

NASA Astrophysics Data System (ADS)

Costamante, L.; Bonnoli, G.; Tavecchio, F.; Ghisellini, G.; Tagliaferri, G.; Khangulyan, D.

2018-05-01

Hard-TeV BL Lacs are a new type of blazars characterized by a hard intrinsic TeV spectrum, locating the peak of their gamma-ray emission in the spectral energy distribution (SED) above 2-10 TeV. Such high energies are problematic for the Compton emission, using a standard one-zone leptonic model. We study six examples of this new type of BL Lacs in the hard X-ray band with NuSTAR. Together with simultaneous observations with the Neil Gehrels Swift Observatory, we fully constrain the peak of the synchrotron emission in their SED, and test the leptonic synchrotron self-Compton (SSC) model. We confirm the extreme nature of 5 objects also in the synchrotron emission. We do not find evidence of additional emission components in the hard X-ray band. We find that a one-zone SSC model can in principle reproduce the extreme properties of both peaks in the SED, from X-ray up to TeV energies, but at the cost of i) extreme electron energies with very low radiative efficiency, ii) conditions heavily out of equipartition (by 3 to 5 orders of magnitude), and iii) not accounting for the simultaneous UV data, which then should belong to a different emission component, possibly the same as the far-IR (WISE) data. We find evidence of this separation of the UV and X-ray emission in at least two objects. In any case, the TeV electrons must not "see" the UV or lower-energy photons, even if coming from different zones/populations, or the increased radiative cooling would steepen the VHE spectrum.

The NuSTAR view on hard-TeV BL Lacs

NASA Astrophysics Data System (ADS)

Costamante, L.; Bonnoli, G.; Tavecchio, F.; Ghisellini, G.; Tagliaferri, G.; Khangulyan, D.

2018-07-01

Hard-TeV BL Lacs are a new type of blazars characterized by a hard intrinsic TeV spectrum, locating the peak of their gamma-ray emission in the spectral energy distribution (SED) above 2-10 TeV. Such high energies are problematic for the Compton emission, using a standard one-zone leptonic model. We study six examples of this new type of BL Lacs in the hard X-ray band with NuSTAR. Together with simultaneous observations with the Neil Gehrels Swift Observatory, we fully constrain the peak of the synchrotron emission in their SED, and test the leptonic synchrotron self-Compton (SSC) model. We confirm the extreme nature of five objects also in the synchrotron emission. We do not find evidence of additional emission components in the hard X-ray band. We find that a one-zone SSC model can in principle reproduce the extreme properties of both peaks in the SED, from X-ray up to TeV energies, but at the cost of (i) extreme electron energies with very low radiative efficiency, (ii) conditions heavily out of equipartition (by three to five orders of magnitude), and (iii) not accounting for the simultaneous UV data, which then should belong to a different emission component, possibly the same as the far-IR (WISE) data. We find evidence of this separation of the UV and X-ray emission in at least two objects. In any case, the TeV electrons must not `see' the UV or lower energy photons, even if coming from different zones/populations, or the increased radiative cooling would steepen the very high energies spectrum.

Magnetic Fields in Blazar Jets: Radio and Optical Polarization over 20-30 Years

NASA Astrophysics Data System (ADS)

Caldwell, Caroline; Wills, B.; Wills, D.; Aller, H.; Aller, M.

2011-01-01

Blazars are highly active nuclei of distant galaxies. They produce synchrotron-emitting relativistic jets on scales of less than a parsec to many Kpc. When viewed head-on, as opposed to in the plane of the sky, the jet motion appears superluminal, and the emission is Doppler boosted. Blazars show rapid radio and optical variability in flux density and polarization. There are two types of blazars that can have strong synchrotron continua: non-BL Lac blazars with strong broad emission lines (quasars), and BL Lac objects with only weak lines. We have compiled optical linear polarization measurements of 22 blazars, incorporating much archival data from McDonald Observatory. While the optical data are somewhat sparsely sampled, The University of Michigan Radio Astronomical Observatory observed many blazars over 20-30 years, often well-sampled over days to weeks. These data enabled us to compare optical and radio polarization position angles. We constructed histograms of the separation of polarization position angles of the optical and radio. We found that in BL Lac objects, the histogram has a significant peak at zero separation. Since the polarization position angle indicates the direction perpendicular to the magnetic field vector, finding similar polarization position angles indicates a similar magnetic field at the origin of the optical and radio synchrotron radiation. Non-BL Lac blazars show peaks at zero and 90 degree separation of position angle. The 90 degree separation may be caused by optical depth effects within the jet. Although there are a few sources that do not strongly display the characteristics summarized by the histograms, most sources produce optical and radio polarization position angles that nearly coincide or are separated by 90 degrees. Using VLBA and VLA radio maps, we interpret the results in terms of the position angle of the jet in the sky plane.

Photometric Redshifts of High-z BL Lacs from 3FGL Catalog

NASA Astrophysics Data System (ADS)

Kaur, A.; Rau, Arne; Ajello, Marco; Paliya, Vaidehi; Hartmann, Dieter; Greiner, Jochen; Bolmer, Jan; Schady, Patricia

2017-08-01

Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broad-band filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far ultraviolet to the near-Infrared. We report results on 40 new Fermi detected BL Lacs with the photometric redshifts determinations for 5 sources, with 3FGL J1918.2-4110 being the most distance in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the Gamma-ray horizon due to the extragalactic background light.

Spectroscopic and polarimetric study of radio-quiet weak emission line quasars

NASA Astrophysics Data System (ADS)

Kumar, Parveen; Chand, Hum; Gopal-Krishna; Srianand, Raghunathan; Stalin, Chelliah Subramonian; Petitjean, Patrick

2018-04-01

A small subset of optically selected radio-quiet QSOs with weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with an infant/shielded broad line region (BLR). High polarisation (p > 3-4%), a hallmark of BL Lacs, can be used to test whether some optically selected ‘radio-quiet weak emission line QSOs’ (RQWLQs) show a fractional polarisation high enough to qualify as radio-quiet analogues of BL Lac objects. To check this possibility, we have made optical spectral and polarisation measurements of a sample of 19 RQWLQs. Out of these, only 9 sources show a non-significant proper motion (hence very likely extragalactic) and only two of them are found to have p > 1%. For these two RQWLQs, namely J142505.59+035336.2 and J154515.77+003235.2, we found the highest polarization to be 1.59±0.53%, which is again too low to classify them as (radio-quiet) BL Lacs, although one may recall that even genuine BL Lacs sometimes appear weakly polarised. We also present a statistical comparison of the optical spectral index, for a sample of 45 RQWLQs with redshift-luminosity matched control samples of 900 QSOs and an equivalent sample of 120 blazars, assembled from the literature. The spectral index distribution of RQWLQs is found to differ, at a high significance level, from that of blazars. This, too, is consistent with the common view that the mechanism of the central engine in RQWLQs, as a population, is close to that operating in normal QSOs and the primary difference between them is related to the BLR.

γ-Ray and Parsec-scale Jet Properties of a Complete Sample of Blazars From the MOJAVE Program

NASA Astrophysics Data System (ADS)

Lister, M. L.; Aller, M.; Aller, H.; Hovatta, T.; Kellermann, K. I.; Kovalev, Y. Y.; Meyer, E. T.; Pushkarev, A. B.; Ros, E.; MOJAVE Collaboration; Ackermann, M.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Boeck, M.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Chang, C. S.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Focke, W. B.; Fortin, P.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Kadler, M.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ozaki, M.; Paneque, D.; Parent, D.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Rainò, S.; Readhead, A.; Reimer, A.; Reimer, O.; Richards, J. L.; Ritz, S.; Sadrozinski, H. F.-W.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tosti, G.; Tramacere, A.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Zimmer, S.; Fermi LAT Collaboration

2011-11-01

We investigate the Fermi Large Area Telescope γ-ray and 15 GHz Very Long Baseline Array radio properties of a joint γ-ray and radio-selected sample of active galactic nuclei (AGNs) obtained during the first 11 months of the Fermi mission (2008 August 4-2009 July 5). Our sample contains the brightest 173 AGNs in these bands above declination -30° during this period, and thus probes the full range of γ-ray loudness (γ-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least 4 orders of magnitude, reflecting a wide range of spectral energy distribution (SED) parameters in the bright blazar population. The BL Lac objects, however, display a linear correlation of increasing γ-ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class. The synchrotron self-Compton model is favored for the γ-ray emission in these BL Lac objects over external seed photon models, since the latter predict a dependence of Compton dominance on Doppler factor that would destroy any observed synchrotron SED-peak-γ-ray-loudness correlation. The high-synchrotron peaked (HSP) BL Lac objects are distinguished by lower than average radio core brightness temperatures, and none display large radio modulation indices or high linear core polarization levels. No equivalent trends are seen for the flat-spectrum radio quasars (FSRQs) in our sample. Given the association of such properties with relativistic beaming, we suggest that the HSP BL Lac objects have generally lower Doppler factors than the lower-synchrotron peaked BL Lac objects or FSRQs in our sample.

{gamma}-RAY AND PARSEC-SCALE JET PROPERTIES OF A COMPLETE SAMPLE OF BLAZARS FROM THE MOJAVE PROGRAM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lister, M. L.; Hovatta, T.; Aller, M.

We investigate the Fermi Large Area Telescope {gamma}-ray and 15 GHz Very Long Baseline Array radio properties of a joint {gamma}-ray and radio-selected sample of active galactic nuclei (AGNs) obtained during the first 11 months of the Fermi mission (2008 August 4-2009 July 5). Our sample contains the brightest 173 AGNs in these bands above declination -30 Degree-Sign during this period, and thus probes the full range of {gamma}-ray loudness ({gamma}-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least 4 orders of magnitude, reflecting a wide range of spectral energy distribution (SED)more » parameters in the bright blazar population. The BL Lac objects, however, display a linear correlation of increasing {gamma}-ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class. The synchrotron self-Compton model is favored for the {gamma}-ray emission in these BL Lac objects over external seed photon models, since the latter predict a dependence of Compton dominance on Doppler factor that would destroy any observed synchrotron SED-peak-{gamma}-ray-loudness correlation. The high-synchrotron peaked (HSP) BL Lac objects are distinguished by lower than average radio core brightness temperatures, and none display large radio modulation indices or high linear core polarization levels. No equivalent trends are seen for the flat-spectrum radio quasars (FSRQs) in our sample. Given the association of such properties with relativistic beaming, we suggest that the HSP BL Lac objects have generally lower Doppler factors than the lower-synchrotron peaked BL Lac objects or FSRQs in our sample.« less

AGN jets under the microscope: A divide? Doctoral Thesis Award Lecture 2011

NASA Astrophysics Data System (ADS)

Karouzos, M.; Britzen, S.; Witzel, A.; Zensus, A. J.; Eckart, A.

2012-06-01

A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non-radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio-loud flat-spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat-spectrum radio-quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat-spectrum radio-quasars. This is interpreted as evidence for helically structured jets.

Empirical multi-wavelength prediction method for very high energy gamma-ray emitting BL Lacertae objects

NASA Astrophysics Data System (ADS)

Fallah Ramazani, V.; Lindfors, E.; Nilsson, K.

2017-12-01

Aim: We have collected the most complete multi-wavelength (6.0-6.0 × 10-18 cm) dataset of very high energy (VHE) γ-ray emitting (TeV) BL Lacs, which are the most numerous extragalactic VHE sources. Using significant correlations between different bands, we aim to identify the best TeV BL Lac candidates that can be discovered by the current and next generation of imaging air Cherenkov telescopes. Methods: We formed five datasets from lower energy data, i.e. radio, mid-infrared, optical, X-rays, and GeV γ-ray, and five VHE γ-ray datasets to perform a correlation study between different bands and to construct the prediction method. The low energy datasets were averaged for individual sources, while the VHE γ-ray data were divided into subsets according to the flux state of the source. We then looked for significant correlations and determined their best-fit parameters. Using the best-fit parameters we predicted the level of VHE γ-ray flux for a sample of 182 BL Lacs, which have not been detected at TeV energies. We identified the most promising TeV BL Lac candidates based on the predicted VHE γ-ray flux for each source. Results: We found 14 significant correlations between radio, mid-infrared, optical, γ-ray, and VHE γ-ray bands. The correlation between optical and VHE γ-ray luminosity is established for the first time. We attribute this to the more complete sample and more accurate handling of host galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE γ-ray flux is high enough for detection in less than 25 h with current imaging air Cherenkov telescopes. Full Tables A.1 and A.2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A68

BL Lacertae: X-ray spectral evolution and a black-hole mass estimate

NASA Astrophysics Data System (ADS)

Titarchuk, Lev; Seifina, Elena

2017-06-01

We present an analysis of the spectral properties observed in X-rays from active galactic nucleus BL Lacertae using RXTE, Suzaku, ASCA, BeppoSAX, and Swift observations. The total time covered by these observations is approximately 20 yr. We show strong observational evidence that this source undergoes X-ray spectral transitions from the low hard state (LHS) through the intermediate state (IS) to the high soft state (HSS) during these observations. During the RXTE observations (1997-2001, 180 ks, for a total 145 datasets), the source was approximately 75%, 20% and only 5% of the time in the IS, LHS, and HSS, respectively. We also used Swift observations (470 datasets, for a total 800 ks), which occurred during 12 yr (2005-2016), the broadband (0.3-200 keV) data of BeppoSAX (1997-2000, 160 ks), and the low X-ray energy (0.3-10 keV) data of ASCA (1995-1999, 160 ks). Two observations of Suzaku (2006, 2013; 50 ks) in combinations with long-term RXTE and Swift data-sets fortunately allow us to describe all spectral states of BL Lac. The spectra of BL Lac are well fitted by the so-called bulk motion Comptonization (BMC) model for all spectral states. We have established the photon index saturation level, Γsat = 2.2 ± 0.1, in the Γ versus mass accretion rate (Ṁ) correlation. This Γ - Ṁ correlation allows us to estimate the black-hole (BH) mass in BL Lac to be MBH 3 × 107M⊙ for a distance of 300 Mpc. For the BH mass estimate, we use the scaling method taking stellar-mass Galactic BHs 4U 1543-47 and GX 339-4 as reference sources. The Γ - Ṁ correlation revealed in BL Lac is similar to those in a number of stellar-mass Galactic BHs and two recently studied intermediate-mass extragalactic BHs. It clearly shows the correlation along with the very extended Γ saturation at 2.2. This is robust observational evidence for the presence of a BH in BL Lac. We also reveal that the seed (disk) photon temperatures are relatively low, of order of 100 eV, which are consistent with a high BH mass in BL Lac. It is worthwhile to emphasize that we found particular events when X-ray emission anti-correlates with radio emission. This effect indicates that mass accretion rate (and thus X-ray radiation) is higher when the mass outflow is lower.

Cloning, Purification, and Characterization of a Heterodimeric β-Galactosidase from Lactobacillus kefiranofaciens ZW3.

PubMed

He, Xi; Han, Ning; Wang, Yan-Ping

2016-01-01

Lactobacillus kefiranofaciens ZW3 was obtained from kefir grains, which have high lactose hydrolytic activity. In this study, a heterodimeric LacLM-type β-galactosidase gene (lacLM) from ZW3 was isolated, which was composed of two overlapping genes, lacL (1,884 bp) and lacM (960 bp) encoding large and small subunits with calculated molecular masses of 73,620 and 35,682 Da, respectively. LacLM, LacL, and LacM were expressed in Escherichia coli BL21(DE3) and these recombinant proteins were purified and characterized. The results showed that, compared with the recombinant holoenzyme, the recombinant large subunit exhibits obviously lower thermostability and hydrolytic activity. Moreover, the optimal temperature and pH of the holoenzyme and large subunit are 60°C and 7.0, and 50°C and 8.0, respectively. However, the recombinant small subunit alone has no activity. Interestingly, the activity and thermostability of the large subunit were greatly improved after mixing it with the recombinant small subunit. Therefore, the results suggest that the small subunit might play an important role in maintaining the stability of the structure of the catalytic center located in the large subunit.

The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey III. Optical Identifications and New Redshifts

NASA Technical Reports Server (NTRS)

Pursimo, Tapio; Ojha, Roopesh; Jauncey, David L.; Rickett, Barney J.; Dutka, Michael S.; Koay, Jun Yi; Lovell, James E. J.; Bignall, Hayley E.; Kedziora-Chudczer, Lucyna; Macquart, Jean-Pierre

2013-01-01

Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Microarcsecond Scintillation Induced Variability) survey of 443 at spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding that 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.

X-ray flux variability of active galactic nuclei observed using NuSTAR

NASA Astrophysics Data System (ADS)

Rani, Priyanka; Stalin, C. S.; Rakshit, Suvendu

2017-04-01

We present results of a systematic study of flux variability on hourly time-scales in a large sample of active galactic nuclei (AGN) in the 3-79 keV band using data from Nuclear Spectroscopic Telescope Array. Our sample consists of four BL Lac objects (BL Lacs), three flat spectrum radio quasars (FSRQs) 24 Seyfert 1, 42 Seyfert 2 and eight narrow line Seyfert 1 (NLSy1) galaxies. We find that in the 3-79 keV band, about 65 per cent of the sources in our sample show significant variations on hourly time-scales. Using the Mann-Whitney U-test and the Kolmogorov-Smirnov test, we find no difference in the variability behaviour between Seyfert 1 and 2 galaxies. The blazar sources (FSRQs and BL Lacs) in our sample are more variable than Seyfert galaxies that include Seyfert 1 and Seyfert 2 in the soft (3-10 keV), hard (10-79 keV) and total (3-79 keV) bands. NLSy1 galaxies show the highest duty cycle of variability (87 per cent), followed by BL Lacs (82 per cent), Seyfert galaxies (56 per cent) and FSRQs (23 per cent). We obtained flux doubling/halving time in the hard X-ray band less than 10 min in 11 sources. The flux variations between the hard and soft bands in all the sources in our sample are consistent with zero lag.

The flaring activity of Markarian 421 during April 2000

NASA Astrophysics Data System (ADS)

Fegan, D. J.; VERITAS Collaboration

2001-08-01

Evidence for correlated TeV γ and X-ray flaring of the extreme blazar Mrk421 during April 2000 is presented and discussed. The remarkably persistent TeV flare of April 30th 2000 (40 σ significance), exhibiting structure over almost six hours of continuous observation, is analysed in detail. 1 Extreme BL Lac objects The most extreme members of the Active Galactic Nucleus (AGN) family are BL Lac objects and optically violently variable (OVV) quasars, collectively known as blazars. These objects are dominated by the presence of relativistic jets. For jets fortuitously aligned with an observers line of sight, emission may exhibit dramatic variability over very short time scales, in turn implying remarkably compact emission regions. For blazars, the Spectral Energy Distribution (SED) is dominated by non-thermal continuum emission, extending from radio to TeV gamma rays. The broadband nature of the blazar emission offers unique insights into energetic physical processes at work in a very compact region, close to the base of the jet and near the underlying central engine, most likely a supermassive black hole. BL Lacs are very effectively characterized on the basis of their SED shape. X-ray and radio flux limited surveys apear to display a bimodal distribution of properties, with LBL (Low-energy peaked, or "Red" BL Lacs) having synchrotron peaks in the IR-optical bands, and HBL (High-energy peaked, or "Blue" BL Lacs) in the UV to soft X-ray band. Recent comprehensive surveys such as DXRBS, REX and RGB have extended, by almost two orders of magnitude, the range of observable synchrotron peak frequencies. For blazar class objects, broadband emission confirms that the synchrotron peak may span the entire IR Xray range, thus accounting for the multi-frequency emission properties of this class of object. Mrk421, Mrk501, 1ES2344 and 1H1426 all exhibit broadband emission properties, high

Characteristics of Gamma-Ray Loud Blazars in the VLBA Imaging and Polarimetry Survey

NASA Technical Reports Server (NTRS)

Linford, J. D.; Taylor, G. B.; Romani, R. W.; Healey, S. E.; Helmboldt, J. F.; Readhead, A. C.; Reeves, R.; Richards, J. L.; Cotter, G.

2010-01-01

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey. This large, flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong gamma-ray emission. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux. We find that the LAT-detected BL Lac objects tend to be similar to the non-LAT BL Lac objects, but that the LAT-detected FSRQs are often significantly different from the non-LAT FSRQs. The differences between the gamma-ray loud and quiet FSRQS can be explained by Doppler boosting; these objects appear to require larger Doppler factors than those of the BL Lac objects. It is possible that the gamma-ray loud FSRQs are fundamentally different from the gamma-ray quiet FSRQs. Strong polarization at the base of the jet appears to be a signature for gamma-ray loud AGNs.

Temporal Variation of HCO+ 1_0 Galactic Absorption Lines Toward NRAO 150 and BL Lac

NASA Astrophysics Data System (ADS)

Han, Junghwan; Yun, Youngjoo; Park, Yong-Sun

2017-12-01

We present observations of HCO^+ 1-0 absorption lines toward two extragalactic compact radio sources, NRAO 150 and BL Lac with the Korean VLBI Network in order to investigate their time variation over 20 years by Galactic foreground clouds. It is found that the line shape of -17 km s^{-1} component changed marginally during 1993-1998 period and has remained unaltered thereafter for NRAO 150. Its behavior is different from that of H_2CO 1_{10}-1_{11}, suggesting chemical differentiation on ˜ 20 AU scale, the smallest ever seen. On the other hand, BL Lac exhibits little temporal variation for the HCO^+ and H_2CO lines. Our observation also suggests that Korea VLBI Network performs reliably in the spectrum mode in that the shapes of the new HCO^+ 1-0 spectra are in good agreement with the previous ones to an accuracy of a few percent except the time varying component toward NRAO 150.

3FGLzoo: classifying 3FGL unassociated Fermi-LAT γ-ray sources by artificial neural networks

NASA Astrophysics Data System (ADS)

Salvetti, D.; Chiaro, G.; La Mura, G.; Thompson, D. J.

2017-09-01

In its first four years of operation, the Fermi-Large Area Telescope (LAT) detected 3033 γ-ray emitting sources. In the Fermi-LAT Third Source Catalogue (3FGL) about 50 per cent of the sources have no clear association with a likely γ-ray emitter. We use an artificial neural network algorithm aimed at distinguishing BL Lacs from FSRQs to investigate the source subclass of 559 3FGL unassociated sources characterized by γ-ray properties very similar to those of active galactic nuclei. Based on our method, we can classify 271 objects as BL Lac candidates, 185 as FSRQ candidates, leaving only 103 without a clear classification. We suggest a new zoo for γ-ray objects, where the percentage of sources of uncertain type drops from 52 per cent to less than 10 per cent. The result of this study opens up new considerations on the population of the γ-ray sky, and it will facilitate the planning of significant samples for rigorous analyses and multiwavelength observational campaigns.

[Analgesia evoked by combined effect of corvitin and low-intensity microwaves on acupuncture points in mice of different genetic strains with somatic pain].

PubMed

Hura, O V; Bahats'ka, O V; Lymans'kyĭ, Iu P

2011-01-01

The level of analgesia has been investigated in mice of two genotypes C57BL/6J Bl/6j and CBA/CaLac with the somatic pain caused by the formalin test after irradiation of acupuncture point E-36 by microwaves of low intensity (30-300 GHz, density of a stream of capacity of 3-10-9 B(T)/cm2) on a background entered corvitin (20 mg/kg). It is shown, that the action of these two factors causes significant analgesia with different levels: 43% in C57BL/6J Bl/6j mice and 33% in CBA/CaLac mice. The intensity of analgesia after action of microwaves and corvitin exceeds the level attained during separate use of these factors.

THE MICRO-ARCSECOND SCINTILLATION-INDUCED VARIABILITY (MASIV) SURVEY. III. OPTICAL IDENTIFICATIONS AND NEW REDSHIFTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pursimo, Tapio; Ojha, Roopesh; Jauncey, David L.

2013-04-10

Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Micro-Arcsecond Scintillation-Induced Variability) survey of 443 flat spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding thatmore » 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.« less

The X-ray view of radio-loud active galactic nuclei: The central engine and its environment

NASA Astrophysics Data System (ADS)

Donato, Davide

The non-thermal emission from many Active Galactic Nuclei (AGN) is obscured by optically thick circumnuclear matter, particularly at optical and ultraviolet wavelengths. In radio-loud (RL) sources, the AGN activity is coupled with the presence of a bipolar jet that emit radio through g-ray light which is relativistically beamed along the jet axes. The combination of absorption and beaming produces highly anisotropic radiation. The understanding of the origin and magnitude of this radiation allows astronomers to unify different classes of AGN; that is, to identify each single, underlying AGN type that gives rise to different classes through different orientations with respect to the jet axis. This is the fundamental notion behind what are called "unification models" of AGN. Although this general idea is well accepted, many aspects remain matter of debate. In fact, the explanation of the wide and complex variety of AGN phenomena must be searched in a combination of apparent differences (like orientation) and real differences in a number of physical parameters (like gas/dust content and distribution, luminosity, etc.). The goal of this thesis is to address some of the RL unification open questions using X-ray data. The improved sensitivity and angular resolution of a new generation of satellites, combined with the fact that X-rays provide useful information on a variety of AGN phenomena, will allow me to: (1) Study the broadband X-ray continua of BL Lacertae objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs); (2) Probe the emission from the very inner region of an AGN; (3) Determine the presence and characteristic of extended X-ray emission from the AGN environment. The results obtained from theses studies will provide me insights into (1) the X-ray average spectral properties of BL Lacs and FSRQs and the physical processes responsible of the emission; (2) the presence of the obscuring torus and the amount of absorption, (3) the nature of X-ray emission, and (4) the type of accretion and efficiency of the accretion process in Fanaroff-Riley I radio galaxies; (5) the properties of the gas in BL Lacs and (6) its effects on the AGN activity and jet properties.

Fermi LAT detection of a GeV flare from the high redshift BL Lac object PKS 2131-021

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-08-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object PKS 2131-021 (also known as 2FGL J2133.8-0154, Nolan et al. 2012, ApJS, 199, 31, and 4C -02.81) placed at radio coordinates R.A.: 323.5429567 deg, Dec.: -1.8881217 deg (J2000, Johnston et al. 1995, AJ, 110, 880).

Fermi LAT detection of a GeV flare from the BL Lac object Mrk 421

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2012-07-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object Mrk 421 (also known as 2FGL J1104.4+3812, Nolan et al. 2012, ApJS, 199, 31; R.A.= 11h04m27.3139s, Dec.= +38d12m31.799s, J2000.0, Fey et al. 2004, AJ, 127, 3587) at redshift z=0.03 (De Vaucouleurs et al.

Radio morphology and parent population of X-ray selected BL Lacertae objects

NASA Technical Reports Server (NTRS)

Laurent-Muehleisen, S. A.; Kollgaard, R. I.; Moellenbrock, G. A.; Feigelson, E. D.

1993-01-01

High-dynamic range (typically 1700:1) radio maps of 15 X-ray BL Lac (XBL) objects from the HEAO-1 Large Area Sky Survey are presented. Morphological characteristics of these sources are compared with Fanaroff-Riley (FR) class I radio galaxies in the context of unified schemes, with reference to one-sided kiloparsec-scale emission. Evidence that cluster membership of XBLs is significantly higher than previously thought is also presented. It is shown that the extended radio powers, X-ray emission, core-to-lobe ratios, and linear sizes of the radio selected BL Lac (RBL) and XBL populations are consistent with an FR I radio galaxy parent population. A source list and VLA observing log and map parameters are provided.

Host galaxy and environment of the BL Lacertae object PKS 0548-322: Observations with subarcsecond resolution

NASA Technical Reports Server (NTRS)

Falomo, Renato; Pesce, Joseph E.; Treves, Aldo

1995-01-01

We report on direct, subarcsecond resolution imaging of the nebulosity and spectroscopy of galaxies in the field of the BL Lacertae object PKS 0548-322. Surface photometry of the nebulosity is used to derive the properties of the host galaxy (M(sub V) = -23.4), which exhibits signs of interaction with a close companion galaxy at approximately 25 kpc. The radial brightness profile of the nebulosity is well fitted by the contribution of a bulge (r(exp 1/4)) plus a point source and a small internal disk. An analysis of the galaxies in the field shows that the source is located in a rich cluster of galaxies. Spectra of five galaxies in the field indicate that they are at the same redshift as the BL Lac object, thus supporting the imaging result of a surrounding cluster associated with the BL Lac. This cluster is most likely Abell S0549.

Search for Cross-Correlations of Ultrahigh-Energy Cosmic Rays with BL Lacertae Objects

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abu-Zayyad, T.; Amann, J. F.; Archbold, G.; Belov, K.; Belz, J. W.; BenZvi, S.; Bergman, D. R.; Blake, S. A.; Boyer, J. H.; Burt, G. W.; Cao, Z.; Connolly, B. M.; Deng, W.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G. A.; Hüntemeyer, P.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Knapp, B. C.; Loh, E. C.; Maestas, M. M.; Manago, N.; Mannel, E. J.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Roberts, M. D.; Rodriguez, D.; Sasaki, M.; Schnetzer, S. R.; Seman, M.; Sinnis, G.; Smith, J. D.; Snow, R.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Westerhoff, S.; Wiencke, L. R.; Zech, A.; HIRES Collaboration

2006-01-01

Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultrahigh-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lac objects and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lac objects from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data.

Mouse Leydig Cells with Different Androgen Production Potential Are Resistant to Estrogenic Stimuli but Responsive to Bisphenol A Which Attenuates Testosterone Metabolism

PubMed Central

Savchuk, Iuliia; Söder, Olle; Svechnikov, Konstantin

2013-01-01

It is well known that estrogens and estrogen-like endocrine disruptors can suppress steroidogenic gene expression, attenuate androgen production and decrease differentiation of adult Leydig cell lineage. However, there is no information about the possible link between the potency of Leydig cells to produce androgens and their sensitivity to estrogenic stimuli. Thus, the present study explored the relationship between androgen production potential of Leydig cells and their responsiveness to estrogenic compounds. To investigate this relationship we selected mouse genotypes contrasting in sex hormone levels and differing in testosterone/estradiol (T/E2) ratio. We found that two mouse genotypes, CBA/Lac and C57BL/6j have the highest and the lowest serum T/E2 ratio associated with increased serum LH level in C57BL/6j compared to CBA/Lac. Analysis of steroidogenic gene expression demonstrated significant upregulation of Cyp19 gene expression but coordinated suppression of LHR, StAR, 3βHSDI and Cyp17a1 in Leydig cells from C57BL/6j that was associated with attenuated androgen production in basal and hCG-stimulated conditions compared to CBA/Lac mice. These genotype-dependent differences in steroidogenesis were not linked to changes in the expression of estrogen receptors ERα and Gpr30, while ERβ expression was attenuated in Leydig cells from C57BL/6j compared to CBA/Lac. No effects of estrogenic agonists on steroidogenesis in Leydig cells from both genotypes were found. In contrast, xenoestrogen bisphenol A significantly potentiated hCG-activated androgen production by Leydig cells from C57BL/6j and CBA/Lac mice by suppressing conversion of testosterone into corresponding metabolite 5α-androstane-3α,17β-diol. All together our data indicate that developing mouse Leydig cells with different androgen production potential are resistant to estrogenic stimuli, while xenoestrogen BPA facilitates hCG-induced steroidogenesis in mouse Leydig cells via attenuation of testosterone metabolism. This cellular event can cause premature maturation of Leydig cells that may create abnormal intratesticular paracrine milieu and disturb proper development of germ cells. PMID:23967237

Suzaku observations of γ-ray bright radio galaxies: Origin of the x-ray emission and broadband modeling

DOE PAGES

Fukazawa, Yasushi; Finke, Justin; Stawarz, Łukasz; ...

2014-12-24

Here, we performed a systematic X-ray study of eight nearby γ-ray bright radio galaxies with Suzaku in order to understand the origins of their X-ray emissions. The Suzaku spectra for five of those have been presented previously, while the remaining three (M87, PKS 0625–354, and 3C 78) are presented here for the first time. Based on the Fe-K line strength, X-ray variability, and X-ray power-law photon indices, and using additional information on the [O III] line emission, we argue for a jet origin of the observed X-ray emission in these three sources. We also analyzed five years of Fermi Largemore » Area Telescope (LAT) GeV gamma-ray data on PKS 0625–354 and 3C 78 to understand these sources within the blazar paradigm. We found significant γ-ray variability in the former object. Overall, we note that the Suzaku spectra for both PKS 0625–354 and 3C 78 are rather soft, while the LAT spectra are unusually hard when compared with other γ-ray detected low-power (FR I) radio galaxies. We demonstrate that the constructed broadband spectral energy distributions of PKS 0625–354 and 3C 78 are well described by a one-zone synchrotron/synchrotron self-Compton model. The results of the modeling indicate lower bulk Lorentz factors compared to those typically found in other BL Lacertae (BL Lac) objects, but consistent with the values inferred from modeling other LAT-detected FR I radio galaxies. Interestingly, the modeling also implies very high peak (~10 16 Hz) synchrotron frequencies in the two analyzed sources, contrary to previously suggested scenarios for Fanaroff-Riley (FR) type I/BL Lac unification. Finally, we discuss the implications of our findings in the context of the FR I/BL Lac unification schemes.« less

Quasi-simultaneous observations of the BL Lac object MK 501 in X-ray, UV, visible, IR and radio frequencies

NASA Technical Reports Server (NTRS)

Kondo, D. M.; Worrall, D. M.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. H.; Oke, J. B.; Yee, H.; Neugebauer, G.; Matthews, K.; Feldman, P. A.

1980-01-01

Quasi-simultaneous observations of the BL Lacertae (Lac) objects MK 501 were performed for the first time at X-ray, ultraviolet, visible, infrared, and radio frequencies. The observed spectral slope from the X-ray to UV regions is positive and continuous, but that from the mid UV to visible light region becomes gradually flat and possibly turns down toward lower frequencies; the optical radio emission can not be accounted for by a single power law. Several theoretical models were considered for the emission mechanism. A quantitative comparison was performed with the synchrotron-self-Compton model; the total spectrum is found consistent with this model. The spectrum from visible light to X-ray is consistent with synchrotron radiation or with inverse-Compton scattering by a hot thermal cloud of electrons. The continuity of the spectral slope from X-ray to UV implied by the current data suggests that the previous estimates of the total luminosity of this BL Lac object is underestimated by a factor of about three or four.

An Analysis of Periodic Components in BL Lac Object S5 0716 +714 with MUSIC Method

NASA Astrophysics Data System (ADS)

Tang, J.

2012-01-01

Multiple signal classification (MUSIC) algorithms are introduced to the estimation of the period of variation of BL Lac objects.The principle of MUSIC spectral analysis method and theoretical analysis of the resolution of frequency spectrum using analog signals are included. From a lot of literatures, we have collected a lot of effective observation data of BL Lac object S5 0716 + 714 in V, R, I bands from 1994 to 2008. The light variation periods of S5 0716 +714 are obtained by means of the MUSIC spectral analysis method and periodogram spectral analysis method. There exist two major periods: (3.33±0.08) years and (1.24±0.01) years for all bands. The estimation of the period of variation of the algorithm based on the MUSIC spectral analysis method is compared with that of the algorithm based on the periodogram spectral analysis method. It is a super-resolution algorithm with small data length, and could be used to detect the period of variation of weak signals.

An Analysis of Light Periods of BL Lac Object S5 0716+714 with the MUSIC Algorithm

NASA Astrophysics Data System (ADS)

Tang, Jie

2012-07-01

The multiple signal classification (MUSIC) algorithm is introduced to the estimation of light periods of BL Lac objects. The principle of the MUSIC algorithm is given, together with a testing on its spectral resolution by using a simulative signal. From a lot of literature, we have collected a large number of effective observational data of the BL Lac object S5 0716+714 in the three optical wavebands V, R, and I from 1994 to 2008. The light periods of S5 0716+714 are obtained by means of the MUSIC algorithm and average periodogram algorithm, respectively. It is found that there exist two major periodic components, one is the period of (3.33±0.08) yr, another is the period of (1.24±0.01) yr. The comparison of the performances of periodicity analysis of two algorithms indicates that the MUSIC algorithm has a smaller requirement on the sample length, as well as a good spectral resolution and anti-noise ability, to improve the accuracy of periodicity analysis in the case of short sample length.

Multiwavelength Observations Of The Previously Unidentified Blazar RX J0648.7+1516

DOE PAGES

Aliu, E.

2011-11-15

We report on the VERITAS discovery of very-high-energy (VHE) gammaray emission above 200 GeV from the high-frequency-peaked BL Lac object RXJ0648.7+1516 (GBJ0648+1516), associated with 1FGL J0648.8+1516. The photon spectrum above 200 GeV is fit by a power law dN/dE = F0(E/E0) -Γ with a photon index Γ of 4.4 ± 0.8stat ± 0.3syst and a flux normalization F0 of (2.3±0.5stat ±1.2sys)×10 -11 TeV -1cm -2s -1 with E0 = 300 GeV. No VHE variability is detected during VERITAS observations of RXJ0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identification and spectroscopic redshift were obtainedmore » using the Shane 3–m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to sub-classify the blazar as a high-frequency-peaked BL Lac (HBL) object, including data from the MDM observatory, Swift -UVOT and XRT, and continuous monitoring at photon energies above 1 GeV from the Fermi Large Area Telescope (LAT). We find that in the absence of undetected, high-energy rapid variability, the one-zone synchrotron self-Compton model (SSC) overproduces the high-energy gamma-ray emission measured by the Fermi -LAT over 2.3 years. The SED can be parameterized satisfactorily with an external-Compton or lepto-hadronic model, which have two and six additional free parameters, respectively, compared to the one-zone SSC model.« less

VLBA Observations of Low Luminosity Flat Spectrum Radio Galaxies and BL Lac Objects: Polarisation Properties

NASA Astrophysics Data System (ADS)

Bondi, M.; Dallacasa, D.; Stanghellini, C.; Marchã, M. J. M.

We obtained two-epoch VLBA observations at 5 GHz of a list of radio galaxies drawn from the 200 mJy sample (Marcha et al. 1996). The objects selected for milli-arcsecond scale observations are classified, on the basis of their optical spectroscopic and polarimetric properties, as BL Lac objects, normal weak line radio galaxies, broad line radio galaxies, and transition objects (those with intermediate properties). We present preliminary results on the radio polarization properties, on the milli-arcsecond scale, of objects with different optical properties and discuss structural variations detected from the two epochs.

MAGIC detection of very high energy γ-ray emission from the low-luminosity blazar 1ES 1741+196

DOE PAGES

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; ...

2017-02-23

Here, we present the first detection of the nearby (z = 0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (E > 100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had suggested 1ES 1741+196 to be, along with several other high-frequency BL Lac sources, within the reach of MAGIC detectability. Its detection by MAGIC, later confirmed by VERITAS, helps to expand the small population of known TeV BL Lacs. The source was observed with the MAGIC telescopes between 2010 April and 2011 May, collecting 46 h of good quality data. Thesemore » observations led to the detection of the source at 6.0 σ confidence level, with a steady flux F(>100 GeV) = (6.4 ± 1.7stat ± 2.6syst) × 10–12 ph cm–2s–1 and a differential spectral photon index Γ = 2.4 ± 0.2stat ± 0.2syst in the range of ~80 GeV–3 TeV. To study the broad-band spectral energy distribution (SED) simultaneous with MAGIC observations, we use KVA, Swift/UVOT and XRT and Fermi/LAT data. One-zone synchrotron-self-Compton (SSC) modelling of the SED of 1ES 1741+196 suggests values for the SSC parameters that are quite common among known TeV BL Lacs except for a relatively low Doppler factor and slope of electron energy distribution. A thermal feature seen in the SED is well matched by a giant elliptical's template. As a result, this appears to be the signature of thermal emission from the host galaxy, which is clearly resolved in optical observations.« less

Optical polarization of high-energy BL Lacertae objects

NASA Astrophysics Data System (ADS)

Hovatta, T.; Lindfors, E.; Blinov, D.; Pavlidou, V.; Nilsson, K.; Kiehlmann, S.; Angelakis, E.; Fallah Ramazani, V.; Liodakis, I.; Myserlis, I.; Panopoulou, G. V.; Pursimo, T.

2016-12-01

Context. We investigate the optical polarization properties of high-energy BL Lac objects using data from the RoboPol blazar monitoring program and the Nordic Optical Telescope. Aims: We wish to understand if there are differences between the BL Lac objects that have been detected with the current-generation TeV instruments and those objects that have not yet been detected. Methods: We used a maximum-likelihood method to investigate the optical polarization fraction and its variability in these sources. In order to study the polarization position angle variability, we calculated the time derivative of the electric vector position angle (EVPA) change. We also studied the spread in the Stokes Q/I-U/I plane and rotations in the polarization plane. Results: The mean polarization fraction of the TeV-detected BL Lacs is 5%, while the non-TeV sources show a higher mean polarization fraction of 7%. This difference in polarization fraction disappears when the dilution by the unpolarized light of the host galaxy is accounted for. The TeV sources show somewhat lower fractional polarization variability amplitudes than the non-TeV sources. Also the fraction of sources with a smaller spread in the Q/I-U/I plane and a clumped distribution of points away from the origin, possibly indicating a preferred polarization angle, is larger in the TeV than in the non-TeV sources. These differences between TeV and non-TeV samples seem to arise from differences between intermediate and high spectral peaking sources instead of the TeV detection. When the EVPA variations are studied, the rate of EVPA change is similar in both samples. We detect significant EVPA rotations in both TeV and non-TeV sources, showing that rotations can occur in high spectral peaking BL Lac objects when the monitoring cadence is dense enough. Our simulations show that we cannot exclude a random walk origin for these rotations. Conclusions: These results indicate that there are no intrinsic differences in the polarization properties of the TeV-detected and non-TeV-detected high-energy BL Lac objects. This suggests that the polarization properties are not directly related to the TeV-detection, but instead the TeV loudness is connected to the general flaring activity, redshift, and the synchrotron peak location. The polarization curve data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A78

The X-ray spectra of the BL Lacertae objects PKS 0548 - 322 and 3C 66A

NASA Technical Reports Server (NTRS)

Maccacaro, T.; Maccagni, D.; Tarenghi, M.

1983-01-01

Einstein Observatory simultaneous imaging proportional counter and monitor proportional counter data are combined in order to derive the energy spectra of the BL Lac objects PKS 0548-322 and 3C 66A between 0.2 and 10 keV. While the latter is found to be variable in both intensity and spectral shape, the former, although constant in the present data, is found to have experienced a spectrum variation in view of results from other experiments. Attention is given to the implications of flux and spectral variability in BL Lac objects for models of X-ray emission mechanisms. It is suggested that the wide spread of the spectral index distribution is due to the detection of the highly variable synchrotron-produced X-rays that are generally undetected in QSOs.

Fermi-LAT detection of a GeV flare from the BL Lac object 1ES 2322-409

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2013-10-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the BL Lac object 1ES 2322-409 (also know as 2FGL J2324.7-4042, Nolan et al. 2012, ApJS, 199, 31, and as 1FHL J2324.6-4041, Ackermann et al., ApJS, submitted, arXiv:1306.6772), with 2MASS counterpart coordinates, (J2000.0), R.A.: 351.18612 deg, Dec: -40.68036 deg (Mao 2011, New Ast., 16, 503).

The Luminosity Function of the Host Galaxies of QSOs and BL Lac Objects

NASA Astrophysics Data System (ADS)

Carangelo, Nicoletta; Falomo, Renato; Treves, Aldo

A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties requires images of excellent quality in order to disentangle the light of the galaxy from that of the bright nucleus. To this aim HST has provided a major improvement of data on QSOs (Disney et al. 1995; Bahcall et al. 1996,1997; Boyce et al. 1998; McLure et al. 1999; Hamilton et al. 2000; Kukula et al. 2001) and BL Lacs (Scarpa et al. 2000, Urry et al. 2000).

VizieR Online Data Catalog: Fermi/non-Fermi blazars jet power and accretion (Chen+, 2015)

NASA Astrophysics Data System (ADS)

Chen, Y. Y.; Zhang, X.; Zhang, H. J.; Yu, X. L.

2017-11-01

We selected the sample using radio catalogues to get the widest possible sample of blazars based on their radio properties. We split them into Fermi-detected sources and non-Fermi detections. Massaro et al. (2009, J/A+A/495/691) created the "Multifrequency Catalogue of Blazars" (Roma-BZCAT), which classifies blazars into three main groups based on their spectral properties. In total, we have a sample containing 177 clean Fermi blazars (96 Fermi FSRQs and 81 Fermi BL Lacs) and 133 non-Fermi blazars (105 non-Fermi FSRQs and 28 non-Fermi BL Lacs). (2 data files).

Resolving the host galaxy of a distant blazar with LBT/LUCI 1 + ARGOS

NASA Astrophysics Data System (ADS)

Farina, E. P.; Georgiev, I. Y.; Decarli, R.; Terzić, T.; Busoni, L.; Gässler, W.; Mazzoni, T.; Borelli, J.; Rosensteiner, M.; Ziegleder, J.; Bonaglia, M.; Rabien, S.; Buschkamp, P.; Orban de Xivry, G.; Rahmer, G.; Kulas, M.; Peter, D.

2018-05-01

BL Lac objects emitting in the very high energy (VHE) regime are unique tools to peer into the properties of the extragalactic background light (EBL). However, due to the typical absence of features in their spectra, the determination of their redshifts has proven challenging. In this work, we exploit the superb spatial resolution delivered by the new Advanced Rayleigh guided Ground layer adaptive Optics System (ARGOS) at the Large Binocular Telescope to detect the host galaxy of HESS J1943+213, a VHE emitting BL Lac shining through the Galaxy. Deep H-band imaging collected during the ARGOS commissioning allowed us to separate the contribution of the nuclear emission and to unveil the properties of the host galaxy with unprecedented detail. The host galaxy is well fitted by a Sérsic profile with index of n ˜ 2 and total magnitude of HHost ˜ 16.15 mag. Under the assumption that BL Lac host galaxies are standard candles, we infer a redshift of z ˜ 0.21. In the framework of the current model for the EBL, this value is in agreement with the observed dimming of the VHE spectrum due to the annihilation of energetic photons on the EBL

The Spectral Energy Distribution of Fermi bright blazars

DOE PAGES

Abdo, A. A.; Ackermann, M.; Agudo, I.; ...

2010-05-13

We have conducted a detailed investigation of the broadband spectral properties of the γ-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi γ-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray/γ-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. The SED of these γ-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual log ν-log ν F ν representation, the typical broadband spectral signaturesmore » normally attributed to a combination of low-energy synchrotron radiation followed by inverse Compton emission of one or more components. Here, we have used these SED to characterize the peak intensity of both the low- and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, α ro, and optical to X-ray, α ox, spectral slopes) and from the γ-ray spectral index. Our data show that the synchrotron peak frequency (ν S peak) is positioned between 10 12.5 and 10 14.5 Hz in broad-lined flat spectrum radio quasars (FSRQs) and between 10 13 and 10 17 Hz in featureless BL Lacertae objects. We find that the γ-ray spectral slope is strongly correlated with the synchrotron peak energy and with the X-ray spectral index, as expected at first order in synchrotron-inverse Compton scenarios. However, simple homogeneous, one-zone, synchrotron self-Compton (SSC) models cannot explain most of our SED, especially in the case of FSRQs and low energy peaked (LBL) BL Lacs. More complex models involving external Compton radiation or multiple SSC components are required to reproduce the overall SED and the observed spectral variability. While more than 50% of known radio bright high energy peaked (HBL) BL Lacs are detected in the LBAS sample, only less than 13% of known bright FSRQs and LBL BL Lacs are included. This suggests that the latter sources, as a class, may be much fainter γ-ray emitters than LBAS blazars, and could in fact radiate close to the expectations of simple SSC models. We categorized all our sources according to a new physical classification scheme based on the generally accepted paradigm for Active Galactic Nuclei and on the results of this SED study. Since the LAT detector is more sensitive to flat spectrum γ-ray sources, the correlation between ν S peak and γ-ray spectral index strongly favors the detection of high energy peaked blazars, thus explaining the Fermi overabundance of this type of sources compared to radio and EGRET samples. Finally, this selection effect is similar to that experienced in the soft X-ray band where HBL BL Lacs are the dominant type of blazars.« less

The Spectral Energy Distribution of Fermi Bright Blazars

NASA Technical Reports Server (NTRS)

Abdo, A. A.; Ackermann, M.; Agudo, I.; Ajello, M.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Arkharov, A. A.; Axelsson, M.; Bach, U.;

Very high energy gamma-ray emission detected from PKS 1440-389 with H.E.S.S.

NASA Astrophysics Data System (ADS)

Hofmann, W.

2012-04-01

The BL Lac object PKS 1440-389, located at a tentative redshift of z=0.065 (6dF Galaxy Survey, Jones, D.H. et al. MNRAS 355, 747-763, 2004), has been reported as a hard (G=1.75+/-0.05), bright, and steady extragalactic source at GeV energies in the Fermi-LAT catalogue (2FGL J1443.9-3908, P.L. Nolan et al., 2012, ApJS, 199, 31). The extrapolation of the Fermi-LAT spectrum to very high energies (VHE; E> 100 GeV), together with its brightness in the radio and X-ray bands, makes this BL Lac object a good candidate for VHE emission.

Discovery of Very High Energy Gamma-Ray Emission from BL Lac object H1722+119 by the MAGIC Telescopes

NASA Astrophysics Data System (ADS)

Cortina, Juan

2013-05-01

H1722+119 is a BL Lac object, that was listed as candidate TeV blazar in Costamante & Ghisellini (2002) based on its X-ray and radio properties. Its redshift is uncertain; Sbarufatti et al. 2006 give z>0.17. The source has been detected by Fermi-LAT, in the Second Fermi Catalog with F(>1 GeV) (3.7+-0.3)e-09 cm^-2 s^-1 and with spectral index 1.92+-0.06. H1722+119 was observed for five nights by the MAGIC telescopes starting May 17th 2013 and collecting 11 hours of good quality data.

A revised and updated catalog of quasi-stellar objects

NASA Technical Reports Server (NTRS)

Hewitt, A.; Burbidge, G.

1993-01-01

The paper contains a catalog of all known quasi-stellar objects (QSOs) with measured emission redshifts, and BL Lac objects, complete to 1992 December 31. The catalog contains 7315 objects, nearly all QSOs including about 90 BL Lac objects. The catalog and references contain extensive information on names, positions, magnitudes, colors, emission-line redshifts, absorption, variability, polarization, and X-ray, radio, and infrared data. A key in the form of subsidiary tables enables the reader to relate the name of a given object to its coordinate name, which is used throughout the compilation. Plots of the Hubble diagram, the apparent magnitude distribution, the emission redshift distribution, and the distribution of the QSOs on the sky are also given.

First NuSTAR observations of the BL Lac - type blazar PKS 2155-304: constraints on the jet content and distribution of radiating particles

NASA Astrophysics Data System (ADS)

Madejski, Grzegorz; Nalewajko, Krzysztof; Madsen, Kristin; Chiang, James; Balokovic, Mislav; Paneque, David; Furniss, Amy; NuSTAR Team

2017-01-01

Current scenarios for emission mechanisms operating in relativistic jets in AGN involve synchrotron emission for the radio through UV spectrum, and inverse Compton for hard X-rays through γ-rays, but the particle content of relativistic jets - whether they are dominated by proton-electron, or e +/e- plasma - has not been established. Our first hard X-ray observations with NuSTAR of the BL Lac type blazar PKS 2155-304, augmented by XMM-Newton data, reveal the 0.5-60 keV spectrum as best-described by a soft power law component dominating below 10 keV (photon index of 3 at 2 keV), and a hard power-law tail (index 2), dominating in the 20-60 keV range. The hard X-ray tail can be smoothly joined to the quasi-simultaneous Fermi/LAT γ-ray spectrum by a synchrotron self-Compton component produced by an electron distribution with index p =2.2. The jet content needs to (globally) obey charge neutrality; assuming that the power-law electron distribution extends down to the Lorentz factor of 1, and one proton per electron, yields an unrealistically high total jet power of 1047 erg/s. This can be reduced by two orders of magnitude by considering a significant presence of e +/e- pairs with lepton-to-proton ratio of at least 30.

Magnetic Fields in Blazar Jets: Jet-Alignment of Radio and Optical Polarization over 20-30 Years

NASA Astrophysics Data System (ADS)

Wills, Beverley J.; Aller, M. F.; Caldwell, C.; Aller, H. D.

2012-01-01

Blazars are highly active nuclei of distant galaxies. They produce synchrotron-emitting relativistic jets on scales of less than a parsec to many Kpc. When viewed head-on, as opposed to in the plane of the sky, the jet motion appears superluminal, and the emission is Doppler boosted. Blazars show rapid radio and optical variability in flux density and polarization. There are two types of blazars that can have strong synchrotron continua: some quasars with strong broad emission lines, and BL Lac objects with weak or undetected broad lines. We have compiled optical linear polarization measurements of more than 100 blazars, including archival data from McDonald Observatory. While the optical data are somewhat sparsely sampled, The University of Michigan Radio Astronomical Observatory observed many blazars over 20-30 years, often well-sampled over days to weeks, enabling quasi-simultaneous comparison of optical and radio polarization position angles (EVPAs). We also collected data on jet direction -- position angles of the jet component nearest the radio core. The project is unique in examining the polarization and jet behavior over many years. BL Lac objects tend to have stable optically thin EVPA in the jet direction, meaning magnetic field is perpendicular to jet flow, often interpreted as the magnetic field compressed by shocks. In quasar-blazars optical and radio EVPA often changes between parallel or perpendicular to the jet direction, even in the same object. The underlying B field of the jet is is parallel to the flow, with approximately 90 degree changes resulting from shocks. For both BL Lac objects & quasars, the scatter in EVPA usually increases from low frequencies (4.8 GHz) through 14.5 GHz through optical. The wide optical-radio frequency range allows us to investigate optical depth effects and the spatial origin of radio and optical emission.

The first catalog of active galactic nuclei detected by the FERMI large area telescope

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-04-29

Here, we present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazarsmore » based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. Lastly, we compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.« less

Analysis of Microvariable Activity of BL Lacertae

NASA Astrophysics Data System (ADS)

Sadun, Alberto C.; Asadi-Zeydabadi, Masoud; Hindman, Lauren; Moody, J. Ward

2018-06-01

BL Lac is a low-frequency peaked blazar (LBL) which emits synchrotron radiation at near-IR and optical wavelengths. Therefore optical observations are helpful in, among other things, studying the acceleration and cooling timescales of the electrons in the relativistic jets. We have made very high cadence observations of BL Lac over a number of nights with the Remote Observatory for Variable Object Research (ROVOR). Each night shows secular drift as well as a number of microvariable events lasting only a few minutes each. These data were then processed, compiled, and analyzed in order to examine the underlying mechanism that resulted in such activity. A geometric model is introduced that has worked well in the past on other similar sources.Our relativistic jet model consists of a slowly varying beamed source that already appears bright because it lies nearly to our line of sight. From this, individual relativistic components are ejected a few degrees relative to the aforementioned beaming angle. This is what we believe is responsible for the microvariability emission.

Magnetic Black Hole Waves

NASA Image and Video Library

2015-07-09

This cartoon shows how magnetic waves, called Alfvén S-waves, propagate outward from the base of black hole jets. The jet is a flow of charged particles, called a plasma, which is launched by a black hole. The jet has a helical magnetic field (yellow coil) permeating the plasma. The waves then travel along the jet, in the direction of the plasma flow, but at a velocity determined by both the jet's magnetic properties and the plasma flow speed. The BL Lac jet examined in a new study is several light-years long, and the wave speed is about 98 percent the speed of light. Fast-moving magnetic waves emanating from a distant supermassive black hole undulate like a whip whose handle is being shaken by a giant hand, according to a study using data from the National Radio Astronomy Observatory's Very Long Baseline Array. Scientists used this instrument to explore the galaxy/black hole system known as BL Lacertae (BL Lac) in high resolution. http://photojournal.jpl.nasa.gov/catalog/PIA19822

Assessment of the Intestinal Barrier with Five Different Permeability Tests in Healthy C57BL/6J and BALB/cJ Mice.

PubMed

Volynets, Valentina; Reichold, Astrid; Bárdos, Gyöngyi; Rings, Andreas; Bleich, André; Bischoff, Stephan C

2016-03-01

Intestinal permeability is thought to be of major relevance for digestive and nutrition-related diseases, and therefore has been studied in numerous mouse models of disease. However, it is unclear which tools are the preferable ones, and how normal values should be defined. To compare different in vivo permeability tests in healthy mice of commonly used genetic backgrounds. We assessed the intestinal barrier in male and female C57BL/6J and BALB/cJ mice of different ages, using four orally administered permeability markers, FITC-dextran 4000 (FITC-D4000) and ovalbumin (OVA) measured in plasma, and polyethylene glycol (PEG) and lactulose/mannitol (Lac/Man) measured in urine, and by assessing lipopolysaccharide (LPS) in portal vein plasma. After gavage, FITC-D4000, OVA, Lac/Man, and PEG400, but not PEG4000, were detectable in plasma or urine. Female mice tended to have a higher permeability according to the FITC-D4000, OVA, and PEG400 tests, but the Lac/Man ratio was higher in males. No significant differences between the two mouse strains of young and old mice were observed except for mannitol recovery, which was higher in BALB/cJ mice compared to C57BL/6J mice (p < 0.05). Virtually no LPS was detected in healthy mice. For all markers, normal values have been defined based on 5th-95th percentile ranges of our data. Selected oral permeability tests, such as FITC-D4000, OVA, PEG400, and Lac/Man, as well as LPS measurements in portal vein plasma, could be suitable for the evaluation of the intestinal barrier in mice, if used in a standardized way.

Continuum radiation from active galactic nuclei: A statistical study

NASA Technical Reports Server (NTRS)

Isobe, T.; Feigelson, E. D.; Singh, K. P.; Kembhavi, A.

1986-01-01

The physics of the continuum spectrum of active galactic nuclei (AGNs) was examined using a large data set and rigorous statistical methods. A data base was constructed for 469 objects which include radio selected quasars, optically selected quasars, X-ray selected AGNs, BL Lac objects, and optically unidentified compact radio sources. Each object has measurements of its radio, optical, X-ray core continuum luminosity, though many of them are upper limits. Since many radio sources have extended components, the core component were carefully selected out from the total radio luminosity. With survival analysis statistical methods, which can treat upper limits correctly, these data can yield better statistical results than those previously obtained. A variety of statistical tests are performed, such as the comparison of the luminosity functions in different subsamples, and linear regressions of luminosities in different bands. Interpretation of the results leads to the following tentative conclusions: the main emission mechanism of optically selected quasars and X-ray selected AGNs is thermal, while that of BL Lac objects is synchrotron; radio selected quasars may have two different emission mechanisms in the X-ray band; BL Lac objects appear to be special cases of the radio selected quasars; some compact radio sources show the possibility of synchrotron self-Compton (SSC) in the optical band; and the spectral index between the optical and the X-ray bands depends on the optical luminosity.

POWERFUL HIGH-ENERGY EMISSION OF THE REMARKABLE BL Lac OBJECT S5 0716+714

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vittorini, V.; Chen, A. W.; Ferrari, A.

BL Lac objects of the intermediate subclass (IBLs) are known to emit a substantial fraction of their power in the energy range 0.1-10 GeV. Detecting gamma-ray emission from such sources provides therefore a direct probe of the emission mechanisms and of the underlying powerhouse. The gamma-ray satellite, AGILE, detected the remarkable IBL S5 0716+714 (z approx = 0.3) during a high state in the period from 2007 September-October, marked by two very intense flares reaching peak fluxes of 200 x 10{sup -8} photons cm{sup -2} s{sup -1} above 100 MeV, with simultaneous optical and X-ray observations. We present here amore » theoretical model for the two major flares and discuss the overall energetics of the source. We conclude that 0716+714 is among the brightest BL Lac's ever detected at gamma-ray energies. Because of its high power and lack of signs for ongoing accretion or surrounding gas, the source is an ideal candidate to test the maximal power extractable from a rotating supermassive black hole via the pure Blandford-Znajek (BZ) mechanism. We find that during the 2007 gamma-ray flares 0716+714 approached or just exceeded the upper limit set by BZ for a black hole of mass 10{sup 9} M{sub sun}.« less

The Spectral Energy Distributions of Blazars and the Connections among XBLs, RBLs, and OVV Quasars

NASA Astrophysics Data System (ADS)

Xie, Guangzhong; Dai, Benzhong; Liang, Enwei; Ma, Li; Jiang, Zejun

2001-06-01

In this paper, we introduce two composite spectral indices, αxox=αox-αx and αoro=αor-αo. In the composite color-color (αxoxαoro) diagram, there are three regions: (1) For XBLs and XBL-like RBLs, the values of αxox is in the range of -1.0 -0.0; (2) For RBLs, αxox is in 0.0-1.5, and αxox < -0.75; (3) For OVV quasars, αxox is in 0.0-1.5 and the αxox > -0.75. Our results support the conclusion that RBLs are intermediate between XBLs and OVV quasars, which has been given by Sambruna et al. (1996, AAA 65.159.120). On the other hand, based on the idea that a group of extragalactic objects which can be regarded as a category with similar physical properties must fit the same relation, using the HST new observational data, we found that there is a strong correlation between the apparent magnitude of the host galaxies and log z for all BL Lac objects (XBLs + RBLs), but OVV quasars lie about 4 magnitude above the Hubble line of 86 BL Lacs. This implies that all XBL-like and XBLs belong to a single category with similar physical properties, while OVV quasars and BL Lacs belong to different populations.

OPTICAL SPECTROSCOPY OF SDSS J004054.65-0915268: THREE POSSIBLE SCENARIOS FOR THE CLASSIFICATION. A z ∼ 5 BL LACERTAE, A BLUE FSRQ, OR A WEAK EMISSION LINE QUASAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landoni, M.; Zanutta, A.; Bianco, A.

2016-02-15

The haunt of high-redshift BL Lacerate objects is day by day more compelling to firmly understand their intrinsic nature and evolution. SDSS J004054.65-0915268 is, at the moment, one of the most distant BL Lac candidates, at z ∼ 5. We present a new optical-near-IR spectrum obtained with ALFOSC-NOT with a new, custom designed dispersive grating aimed to detect broad emission lines that could disprove this classification. In the obtained spectra, we do not detect any emission features and we provide an upper limit to the luminosity of the C iv broad emission line. Therefore, the nature of the object is then discussed,more » building the overall spectral energy distribution (SED) and fitting it with three different models. Our fits, based on SED modeling with different possible scenarios, cannot rule out the possibility that this source is indeed a BL Lac object, though the absence of optical variability and the lack of strong radio flux seem to suggest that the observed optical emission originates from a thermalized accretion disk.« less

Optical Spectroscopy of SDSS J004054.65-0915268: Three Possible Scenarios for the Classification. A z ˜ 5 BL Lacertae, a Blue FSRQ, or a Weak Emission Line Quasar

NASA Astrophysics Data System (ADS)

Landoni, M.; Zanutta, A.; Bianco, A.; Tavecchio, F.; Bonnoli, G.; Ghisellini, G.

2016-02-01

The haunt of high-redshift BL Lacerate objects is day by day more compelling to firmly understand their intrinsic nature and evolution. SDSS J004054.65-0915268 is, at the moment, one of the most distant BL Lac candidates, at z ˜ 5. We present a new optical-near-IR spectrum obtained with ALFOSC-NOT with a new, custom designed dispersive grating aimed to detect broad emission lines that could disprove this classification. In the obtained spectra, we do not detect any emission features and we provide an upper limit to the luminosity of the C IV broad emission line. Therefore, the nature of the object is then discussed, building the overall spectral energy distribution (SED) and fitting it with three different models. Our fits, based on SED modeling with different possible scenarios, cannot rule out the possibility that this source is indeed a BL Lac object, though the absence of optical variability and the lack of strong radio flux seem to suggest that the observed optical emission originates from a thermalized accretion disk.

Validation of antibiotic residue tests for dairy goats.

PubMed

Zeng, S S; Hart, S; Escobar, E N; Tesfai, K

1998-03-01

The SNAP test, LacTek test (B-L and CEF), Charm Bacillus sterothermophilus var. calidolactis disk assay (BsDA), and Charm II Tablet Beta-lactam sequential test were validated using antibiotic-fortified and -incurred goat milk following the protocol for test kit validations of the U.S. Food and Drug Administration Center for Veterinary Medicine. SNAP, Charm BsDA, and Charm II Tablet Sequential tests were sensitive and reliable in detecting antibiotic residues in goat milk. All three assays showed greater than 90% sensitivity and specificity at tolerance and detection levels. However, caution should be taken in interpreting test results at detection levels. Because of the high sensitivity of these three tests, false-violative results could be obtained in goat milk containing antibiotic residues below the tolerance level. Goat milk testing positive by these tests must be confirmed using a more sophisticated methodology, such as high-performance liquid chromatography, before the milk is condemned. LacTek B-L test did not detect several antibiotics, including penicillin G, in goat milk at tolerance levels. However, LacTek CEF was excellent in detecting ceftiofur residue in goat milk.

EGRET observations of the BL Lacertae objects 0716+714 and 0521-365

NASA Technical Reports Server (NTRS)

Lin, Y. C.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Mayer-Hasselwander, H. A.

1995-01-01

During the Compton Observatory's viewing programs Phase 1 (1991 April to 1992 November, also known as the All-Sky Survey) and Phase 2 (1992 November to 1993 September), the BL Lac object 0716+714 was in the field of view of the EGRET telescope a total of six times, three times in Phase 1 and three more times in Phase 2, while the BL Lac object 0521-365 was in the field of view of EGRET only once in Phase 1. The source 0716+714 was detected in high-energy gamma rays by EGRET at a flux level of (2.0 +/- 0.4) x 10(exp -7) photons/sq cm/s for E greater than 100 MeV with a 6 sigma significance when it was first observed by EGRET in 1992 January 10 to 23. The corresponding spectral slope of the photon number distribution is determined to be -2.04 +/- 0.33. The gamma-ray flux of 0716+714 showed considerable time variability in subsequent EGRET observations. But the spectral slope stayed about the same within the statistical uncertainties of the EGRET data. The average spectral slope of the four viewing periods during which the photon flux of 0716+714 stayed above the EGRET detection threshold is found to be -1.85 +/- 0.20 from the combined data. The source 0521+365 was detected by EGRET in 1992 May 14 to June 4 at a flux level of (1.8 +/- 0.5) x 10(exp -7) photons/sq cm/s for E greater than 100 MeV with a 4 sigma significance. The corresponding spectral slope of the photon number distribution is found to be 2.16 +/- 0.36. Details of the observations of these two BL Lac objects with the EGRET telescope are presented.

VizieR Online Data Catalog: SPIRE observations of Herschel-BAT sample (Shimizu+, 2016)

NASA Astrophysics Data System (ADS)

Shimizu, T. T.; Melendez, M.; Mushotzky, R. F.; Koss, M. J.; Barger, A. J.; Cowie, L. L.

2016-09-01

We selected our sample of 313 AGN from the 58 month Swift/BAT Catalogue (https://swift.gsfc.nasa.gov/results/bs58mon) (Baumgartner et al., 2012, in prep.), imposing a redshift cutoff of z<0.05. All different types of AGN were chosen only excluding Blazars/BL Lac objects which most likely introduce complicated beaming effects. To determine their AGN type, for 252 sources we used the classifications from the BAT AGN Spectroscopic Survey (Koss et al., in preparation) which compiled and analysed optical spectra for the Swift/BAT 70 month catalogue (Berney et al., 2015MNRAS.454.3622B). (2 data files).

Extraordinary Activity in the BL Lac Object OJ 287

NASA Astrophysics Data System (ADS)

Hughes, P. A.; Aller, H. D.; Aller, M. F.

We present the results of a wavelet transform analysis of data for the BL Lac object OJ 287 acquired as part of the UMRAO variability program. We find clear evidence for a persistent modulation of the total flux and polarization with period 1.66 years, and for another signal that dominates activity in the 1980s with period 1.12 years. It appears that the longer time scale periodicity is associated with an otherwise quiescent jet, and the shorter time scale activity is associated with the passage of a shock, or shocks. The periodic behavior in polarization exhibits excursions in U which correspond to a direction 45circ from the VLBI jet axis. This behavior suggests a small amplitude, cyclic variation in the flow direction in that part of the flow that dominates cm-wavelength emission.

Optical and X-ray observations of the two BL Lac objects OJ 287 and MS 1458+22

NASA Astrophysics Data System (ADS)

Massaro, E.; Giommi, P.; Perri, M.; Tagliaferri, G.; Nesci, R.; Tosti, G.; Ciprini, S.; Montagni, F.; Ravasio, M.; Ghisellini, G.; Frasca, A.; Marilli, E.; Valentini, G.; Kurtanidze, O. M.; Nikolashvili, M. G.

2003-02-01

We present the results of recent BeppoSAX observations of the two BL Lac objects OJ 287 and MS 1458+22 in bright optical states and of simultaneous photometric measurements in the bandpasses from I to U. OJ 287 was observed in November 2001 and MS 1458+22 in February of the same year. The X-ray flux of OJ 287 was rather low, F(2-10 keV) = (1.35+/-0.15)x 10-12 erg cm-2 s-1 and its spectrum is well described by a single power law with an energy index 0.45+/-0.08, flatter than that measured in the optical, equal to 1.53+/-0.03. The X-ray emission of MS 1458+22 was characterized by a low flux level of F(2-10 keV) = (7.5+/-0.6)x 10-13 erg cm-2 s-1, with a steeper spectral index of 1.71+/-0.15, while in the optical it was 0.99+/-0.06. We show that the broad-band SEDs of these two sources can be well represented by log-parabolic spectral laws and evaluate their parameters. This law, already observed for the synchrotron components of other BL Lac sources, can be explained if the emitting particles are accelerated by some statistical mechanism having a probability of energy gain that is a decreasing function of the energy itself.

Discovery of VHE γ -ray emission from the BL Lacertae object B3 2247+381 with the MAGIC telescopes

DOE PAGES

Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; ...

2012-03-02

Here, we study the non-thermal jet emission of the BL Lac object B3 2247+381 during a high optical state. The MAGIC telescopes observed the source during 13 nights between September 30th and October 30th 2010, collecting a total of 14.2 h of good quality very high energy (VHE) γ-ray data. Simultaneous multiwavelength data was obtained with X-ray observations by the Swift satellite and optical R-band observations at the KVA-telescope. We also use high energy γ-ray (HE, 0.1-100 GeV) data from the Fermi satellite. We also dedected the BL Lac object B3 2247+381 (z = 0.119) , for the first time,more » at VHE γ-rays at a statistical significance of 5.6σ. A soft VHE spectrum with a photon index of -3.2 ± 0.6 was determined. No significant short term flux variations were found. Finally, we model the spectral energy distribution using a one-zone SSC-model, which can successfully describe our data.« less

Soft X-ray spectrum of BL Lacertae object AO 0235+164 as a tracer of elemental abundances at z approximately 0.5

NASA Technical Reports Server (NTRS)

Madejski, Greg

1994-01-01

We report the soft X-ray spectrum of BL Lac object AO 0235+164, observed with the Einstein Observatory Imaging Proportional Counter (IPC). This object (z = 0.94) has an intervening galaxy (or a protogalactic disk) at z = 0.524 present in the line of sight, producing both radio and optical absorption lines in the background BL Lac continuum. The X-ray spectrum exhibits a substantial soft X-ray cutoff, corresponding to several times that expected from our own Galaxy; we interpret that excess cutoff as due to the intervening galaxy. The comparison of the hydrogen column density inferred from the 21 cm radio data and the X-ray absorption allows, in principle, the determination of the elemental abundances in the intervening galaxy. However, the uncertainties in both the H I spin temperature and X-ray spectral parameters only loosely restrict these abundances to be 2 +/- 1 solar, which even at the lower limit appears higher than that inferred from studies of samples of optical absoprtion-line systems.

Optical Variability of BL Lacertae During the Major Outburst of 1997

NASA Technical Reports Server (NTRS)

Ghosh, K. K.; Ramsey, B. D.; Sadun, A. C.; Soundararajaperumal, S.; Wang, J.

2000-01-01

We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 22 nights documenting major as well as minor outbursts. This has been combined, for purposes of multifrequency analysis, with published X-ray and T-ray data taken for an additional single night, On two nights in particular, including the night of the X-ray observations, a major outburst of about a full magnitude of variation was recorded. All the data have been analyzed with theoretical models. Attempts were made to use synchrotron self-Compton and external Comptonization models to explain the data; however, both classes of models were found lacking. More satisfactory results were obtained using an analytical model proposed by Wang et al. that involves the evolution of synchrotron spectra in a homogeneous jet due to the injection of relativistic electrons, taking into account radiation losses during the outbursts. It is hoped that the results of this study of BL Lac, an archetype for the class of blazars in general, represent a more generic phenomenon applicable to the entire class.

Optical Variability of BL Lacertae During the Major Outburst of 1997

NASA Technical Reports Server (NTRS)

Ghosh, K. K.; Ramsey, B. D.; Sadun, A. C.; Soundarajaperumal, S.; Wang, J.

1999-01-01

We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 12 nights documenting major as well as minor outbursts. This has been combined, for purposes of multifrequency analysis, with published X-ray and gamma ray data taken for an additional single night. On two nights in particular, which includes the night of the X-ray observations, a major outburst of about a full magnitude of variation was recorded. All the data have been analyzed with theoretical models. Attempts were made to use synchrotron self-Compton and external Comptonization models to explain the data; however both classes of models were found lacking. More satisfactory results were obtained using an analytical model proposed by Wang et al. that involves the evolution of synchrotron spectra in a homogeneous jet due to the injection of relativistic electrons, taking into account radiation losses during the outbursts. It is hoped that the results of this study of BL Lac, an archetype for the class of blazars in general, represent a more generic phenomenon applicable to the entire class.

Redshift determination of the BL Lac object 3C 66A by the detection of its host galaxy cluster at z = 0.340

NASA Astrophysics Data System (ADS)

Torres-Zafra, Juanita; Cellone, Sergio A.; Buzzoni, Alberto; Andruchow, Ileana; Portilla, José G.

2018-03-01

The BL Lac object 3C 66A is one of the most luminous extragalactic sources at TeV γ-rays (very high energy, i.e. E > 100 GeV). Since TeV γ-ray radiation is absorbed by the extragalactic background light (EBL), it is crucial to know the redshift of the source in order to reconstruct its original spectral energy distribution, as well as to constrain EBL models. However, the optical spectrum of this BL Lac is almost featureless, so a direct measurement of z is very difficult; in fact, the published redshift value for this source (z = 0.444) has been strongly questioned. Based on EBL absorption arguments, several constraints to its redshift, in the range 0.096 < z < 0.5, were proposed. Since these active galactic nuclei (AGNs) are hosted, typically, in early-type galaxies that are members of groups or clusters, we have analysed spectro-photometrically the environment of 3C 66A, with the goal of finding the galaxy group hosting this blazar. This study was made using optical images of a 5.5 × 5.5 arcmin2 field centred on the blazar, and spectra of 24 sources obtained with Gemini/GMOS-N multi-object spectroscopy. We found spectroscopic evidence of two galaxy groups along the blazar's line of sight: one at z ≃ 0.020 and the second one at z ≃ 0.340. The first one is consistent with a known foreground structure, while the second group presented here has six spectroscopically confirmed members. Their location along a red sequence in the colour-magnitude diagram allows us to identify 34 additional candidate members of the more distant group. The blazar's spectrum shows broad absorption features that we identify as arising in the intergalactic medium, thus allowing us to tentatively set a redshift lower limit at z_3C66A ≳ 0.33. As a consequence, we propose that 3C 66A is hosted in a galaxy that belongs to a cluster at z = 0.340.

p53 deficiency alters the yield and spectrum of radiation-induced lacZ mutants in the brain of transgenic mice

NASA Technical Reports Server (NTRS)

Chang, P. Y.; Kanazawa, N.; Lutze-Mann, L.; Winegar, R. A.

2001-01-01

Exposure to heavy particle radiation in the galacto-cosmic environment poses a significant risk in space exploration and the evaluation of radiation-induced genetic damage in tissues, especially in the central nervous system, is an important consideration in long-term manned space missions. We used a plasmid-based transgenic mouse model system, with the pUR288 lacZ transgene integrated in the genome of every cell of C57Bl/6(lacZ) mice, to evaluate the genetic damage induced by iron particle radiation. In order to examine the importance of genetic background on the radiation sensitivity of individuals, we cross-bred p53 wild-type lacZ transgenic mice with p53 nullizygous mice, producing lacZ transgenic mice that were either hemizygous or nullizygous for the p53 tumor suppressor gene. Animals were exposed to an acute dose of 1 Gy of iron particles and the lacZ mutation frequency (MF) in the brain was measured at time intervals from 1 to 16 weeks post-irradiation. Our results suggest that iron particles induced an increase in lacZ MF (2.4-fold increase in p53+/+ mice, 1.3-fold increase in p53+/- mice and 2.1-fold increase in p53-/- mice) and that this induction is both temporally regulated and p53 genotype dependent. Characterization of mutants based on their restriction patterns showed that the majority of the mutants arising spontaneously are derived from point mutations or small deletions in all three genotypes. Radiation induced alterations in the spectrum of deletion mutants and reorganization of the genome, as evidenced by the selection of mutants containing mouse genomic DNA. These observations are unique in that mutations in brain tissue after particle radiation exposure have never before been reported owing to technical limitations in most other mutation assays.

Parsec-Scale Kinematic and Polarization Properties of MOJAVE AGN Jets

NASA Astrophysics Data System (ADS)

Lister, Matthew L.

2013-12-01

We describe the parsec-scale kinematics and statistical polarization properties of 200 AGN jets based on 15 GHz VLBA data obtained between 1994 Aug 31 and 2011 May 1. Nearly all of the 60 most heavily observed jets show significant changes in their innermost position angle over a 12 to 16 year interval, ranging from 10° to 150° on the sky, corresponding to intrinsic variations of ~ 0.5° to ~ 2°. The BL Lac jets show smaller variations than quasars. Roughly half of the heavily observed jets show systematic position angle trends with time, and 20 show indications of oscillatory behavior. The time spans of the data sets are too short compared to the fitted periods (5 to 12 y), however, to reliably establish periodicity. The rapid changes and large jumps in position angle seen in many cases suggest that the superluminal AGN jet features occupy only a portion of the entire jet cross section, and may be energized portions of thin instability structures within the jet. We have derived vector proper motions for 887 moving features in 200 jets having at least five VLBA epochs. For 557 well-sampled features, there are sufficient data to additionally study possible accelerations. The moving features are generally non-ballistic, with 70% of the well-sampled features showing either significant accelerations or non-radial motions. Inward motions are rare (2% of all features), are slow (< 0.1 mas per y), are more prevalent in BL Lac jets, and are typically found within 1 mas of the unresolved core feature. There is a general trend of increasing apparent speed with distance down the jet for both radio galaxies and BL Lac objects. In most jets, the speeds of the features cluster around a characteristic value, yet there is a considerable dispersion in the distribution. Orientation variations within the jet cannot fully account for the dispersion, implying that the features have a range of Lorentz factor and/or pattern speed. Very slow pattern speed features are rare, comprising only 4% of the sample, and are more prevalent in radio galaxy and BL Lac jets. We confirm a previously reported upper envelope to the distribution of speed versus beamed luminosity for moving jet features. Below 1026 W Hz-1 there is a fall-off in maximum speed with decreasing 15 GHz radio luminosity. A preliminary analysis of the multi-epoch jet polarization properties indicates a wide range of behavior in the core electric vector position angles over time, with the latter remaining relatively stable in some jets, and varying rapidly in others. The fractional polarization level generally increases down the jet, and high-synchrotron peaked (HSP) blazars tend to have lower core fractional polarization levels. A general trend of decreasing maximum jet speed for higher synchrotron peaked blazars further suggests lower Doppler factors in the radio-emitting jets of HSP BL Lac objects.

ON ULTRA-HIGH-ENERGY COSMIC RAYS AND THEIR RESULTANT GAMMA-RAYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavish, Eyal; Eichler, David

2016-05-01

The Fermi Large Area Telescope collaboration has recently reported on 50 months of measurements of the isotropic extragalactic gamma-ray background (EGRB) spectrum between 100 MeV and 820 GeV. Ultra-high-energy cosmic ray (UHECR) protons interact with the cosmic microwave background photons and produce cascade photons of energies 10 MeV–1 TeV that contribute to the EGRB flux. We examine seven possible evolution models for UHECRs and find that UHECR sources that evolve as the star formation rate (SFR), medium low luminosity active galactic nuclei type-1 ( L = 10{sup 43.5} erg s{sup −1} in the [0.5–2] KeV band), and BL Lacertae objectsmore » (BL Lacs) are the most acceptable given the constraints imposed by the observed EGRB. Other possibilities produce too much secondary γ -radiation. In all cases, the decaying dark matter (DM) contribution improves the fit at high energy, but the contribution of still unresolved blazars, which would leave the smallest role for decaying DM, may yet provide an alternative improvement. The possibility that the entire EGRB can be fitted with resolvable but not-yet-resolved blazars, as recently claimed by Ajello et al., would leave little room in the EGRB to accommodate γ -rays from extragalactic UHECR production, even for many source evolution rates that would otherwise be acceptable. We find that under the assumption of UHECRs being mostly protons, there is not enough room for producing extragalactic UHECRs with active galactic nucleus, gamma-ray burst, or even SFR source evolution. Sources that evolve as BL Lacs, on the other hand, would produce much less secondary γ -radiation and would remain a viable source of UHECRs, provided that they dominate.« less

Spectroscopy of 10 γ -Ray BL Lac Objects at High Redshift

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paiano, Simona; Falomo, Renato; Landoni, Marco

2017-08-01

We present optical spectra with high signal-to-noise ratio of 10 BL Lac objects detected at GeV energies by the Fermi satellite (3FGL catalog), which previous observations suggested are at relatively high redshift. The new observations, obtained at the 10 m Gran Telescopio Canarias, allowed us to find the redshift for J0814.5+2943 ( z = 0.703), and we can set a spectroscopic lower limit for J0008.0+4713 ( z > 1.659) and J1107.7+0222 ( z > 1.0735) on the basis of Mg ii intervening absorption features. In addition we confirm the redshifts for J0505.5+0416 ( z = 0.423) and J1450+5200 ( zmore » > 2.470). Finally we contradict the previous z estimates for five objects (J0049.7+0237, J0243.5+7119, J0802.0+1005, J1109.4+2411, and J2116.1+3339).« less

Jet Power vs. Black Hole Mass in Blazars: Exploring the Relationship in the Context of the B-Z Mechanism

NASA Astrophysics Data System (ADS)

Fernandes, Sunil; Schlegel, E.

2012-01-01

Recently, a tentative negative correlation between jet power and BH mass in a sample of GeV-TeV BL Lac objects(Zhang et al 2011). It was suggested that spin energy extraction could play a significant role in producing the jets and the jets are not purely accretion driven. Broderick et al (2011) recently explored the relationship between jet power and radio core luminosity building on Blanford et al (1979) theoretical work. Using this work we have studied the relationship between radio core luminosity (as a stand in for jet power) and black hole mass and have found a possible positive correlation in a sample of nearby BL Lac objects. The present poster attempts to explore this relationship in the context of the Blanford-Znajek mechanism which predicts jet power increases with black hole mass, spin rate, and accretion rate.

VizieR Online Data Catalog: Swift and NuSTAR obs. of the BL Lac Mrk 421 (Kapanadze+, 2016)

NASA Astrophysics Data System (ADS)

Kapanadze, B.; Dorner, D.; Vercellone, S.; Romano, P.; Aller, H.; Aller, M.; Hughes, P.; Reynolds, M.; Kapanadze, S.; Tabagari, L.

2017-01-01

We retrieved the Swift-XRT data from the publicly available archive, maintained by HEASARC. We present the results of X-ray observations of the high-energy peaked BL Lac (HBL) source Mrk421 performed by Swift-XRT and NuSTAR during 2013 January-June. Along with the 0.3-10keV and 3-79keV data obtained with the Swift-XRT and NuSTAR instruments, we have processed and analyzed those obtained with the Ultraviolet-Optical Telescope (UVOT) and Large Area Telescope (LAT) onboard Fermi. We have also used the publicly available light curves from the observations performed with the Burst Alert Telescope (BAT) onboard Swift, Monitor of All Sky X-ray Image (MAXI), MAGIC, First G-APD Cherenkov Telescope (FACT), and the OVRO 40m telescope during the 2013 January-June period to draw conclusions about the interband correlations. (8 data files).

A hadronic origin for ultra-high-frequency-peaked BL Lac objects

NASA Astrophysics Data System (ADS)

Cerruti, M.; Zech, A.; Boisson, C.; Inoue, S.

2015-03-01

Current Cherenkov telescopes have identified a population of ultra-high-frequency peaked BL Lac objects (UHBLs), also known as extreme blazars, that exhibit exceptionally hard TeV spectra, including 1ES 0229+200, 1ES 0347-121, RGB J0710+591, 1ES 1101-232, and 1ES 1218+304. Although one-zone synchrotron-self-Compton (SSC) models have been generally successful in interpreting the high-energy emission observed in other BL Lac objects, they are problematic for UHBLs, necessitating very large Doppler factors and/or extremely high minimum Lorentz factors of the emitting leptonic population. In this context, we have investigated alternative scenarios where hadronic emission processes are important, using a newly developed (lepto-)hadronic numerical code to systematically explore the physical parameters of the emission region that reproduces the observed spectra while avoiding the extreme values encountered in pure SSC models. Assuming a fixed Doppler factor δ = 30, two principal parameter regimes are identified, where the high-energy emission is due to: (1) proton-synchrotron radiation, with magnetic fields B ˜ 1-100 G and maximum proton energies Ep; max ≲ 1019 eV; and (2) synchrotron emission from p-γ-induced cascades as well as SSC emission from primary leptons, with B ˜ 0.1-1 G and Ep; max ≲ 1017 eV. This can be realized with plausible, sub-Eddington values for the total (kinetic plus magnetic) power of the emitting plasma, in contrast to hadronic interpretations for other blazar classes that often warrant highly super-Eddington values.

Soft X-ray observations of two BL Lacertae objects - Markarian 421 and 501

NASA Technical Reports Server (NTRS)

Singh, K. P.; Garmire, G. P.

1985-01-01

This paper reports on the soft X-ray (0.15-2.8 keV) observations of two BL Lacertae-type objects, viz., Mrk 421 and Mrk 501. The observations were made with the low-energy detectors on the HEAO 1 satellite during the period 1977 August-1978 December. Steep, soft X-ray power-law spectra with photon index Gamma = 3 are found for both Mrk 421 and Mrk 501. The power-law models are found to give a significantly better fit than the thermal models to the observed pulse-height spectra of Mrk 421 and Mrk 501. Day-to-day soft X-ray (0.25 keV band) intensity variations are observed only in Mrk 501. No significant change is found in Gamma from both the BL Lac objects during the period of observations. However, the sum of all the X-ray observations from 1976 until 1980 can be understood in terms of two spectral components of variable intensity to account for the X-ray emission observed between 0.15 and 20 keV from Mrk 421 and Mrk 501.

A physical classification scheme for blazars

NASA Astrophysics Data System (ADS)

Landt, Hermine; Padovani, Paolo; Perlman, Eric S.; Giommi, Paolo

2004-06-01

Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marchã et al. We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]λ5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]λ5007-[OII]λ3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars.

Three new BL Lacertae objects in the Palomar-Green survey

NASA Technical Reports Server (NTRS)

Fleming, Thomas A.; Green, Richard F.; Jannuzi, Buell T.; Liebert, James; Smith, Paul S.; Fink, Henner

1993-01-01

We have identified three BL Lacertae objects in the Palomar-Green Survey which were previously misclassified as DC white dwarfs, namely PG 1246+586, PG 1424+240, and PG 1437+398. Our reclassification is based on the detection of these objects as x-ray sources in the ROSAT all-sky survey and upon our subsequent detection of intrinsic linearly polarized and variable optical emission from these sources. As a result of the ROSAT survey, the number of identified BL Lac objects in the Palomar-Green catalog of UV excess objects has been doubled. Corrected optical positions are presented for PG 1246+586 and PG 1437+398.

First NuSTAR Observations of the BL Lac-Type Blazar PKS 2155-304: Constraints on the Jet Content and Distribution of Radiating Particles

NASA Technical Reports Server (NTRS)

Madejski, G. M.; Nalewajko, K.; Madsen, K. K.; Chiang, J.; Balokovic, M.; Paneque, D.; Furniss, A. K.; Hayashida, M.; Urry, C. M.; Sikora, M.;

First NuSTAR Observations of the BL Lac-type Blazar PKS 2155-304: Constraints on the Jet Content and Distribution of Radiating Particles

NASA Astrophysics Data System (ADS)

Madejski, G. M.; Nalewajko, K.; Madsen, K. K.; Chiang, J.; Baloković, M.; Paneque, D.; Furniss, A. K.; Hayashida, M.; Urry, C. M.; Sikora, M.; Ajello, M.; Blandford, R. D.; Harrison, F. A.; Sanchez, D.; Giebels, B.; Stern, D.; Alexander, D. M.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Forster, K.; Giommi, P.; Grefenstette, B.; Hailey, C.; Hornstrup, A.; Kitaguchi, T.; Koglin, J. E.; Mao, P. H.; Miyasaka, H.; Mori, K.; Perri, M.; Pivovaroff, M. J.; Puccetti, S.; Rana, V.; Westergaard, N. J.; Zhang, W. W.; Zoglauer, A.

2016-11-01

We report the first hard X-ray observations with NuSTAR of the BL Lac-type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and γ-ray data from the Fermi Large Area Telescope, obtained in 2013 April when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5-60 keV, is best described by a model consisting of a log-parabola component with curvature β ={0.3}-0.1+0.2 and a (local) photon index 3.04 ± 0.15 at photon energy of 2 keV, and a hard power-law tail with photon index 2.2 ± 0.4. The hard X-ray tail can be smoothly joined to the quasi-simultaneous γ-ray spectrum by a synchrotron self-Compton component produced by an electron distribution with index p = 2.2. Assuming that the power-law electron distribution extends down to γ min = 1 and that there is one proton per electron, an unrealistically high total jet power of L p ˜ 1047 erg s-1 is inferred. This can be reduced by two orders of magnitude either by considering a significant presence of electron-positron pairs with lepton-to-proton ratio {n}{{e}+{{e}}-}/{n}{{p}}˜ 30, or by introducing an additional, low-energy break in the electron energy distribution at the electron Lorentz factor γ br1 ˜ 100. In either case, the jet composition is expected to be strongly matter-dominated.

The Evolution of Swift/BAT blazars and the origin of the MeV background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajello, M.; /SLAC /KIPAC, Menlo Park; Costamante, L.

2009-10-17

We use 3 years of data from the Swift/BAT survey to select a complete sample of X-ray blazars above 15 keV. This sample comprises 26 Flat-Spectrum Radio Quasars (FSRQs) and 12 BL Lac objects detected over a redshift range of 0.03 < z < 4.0. We use this sample to determine, for the first time in the 15-55 keV band, the evolution of blazars. We find that, contrary to the Seyfert-like AGNs detected by BAT, the population of blazars shows strong positive evolution. This evolution is comparable to the evolution of luminous optical QSOs and luminous X-ray selected AGNs. Wemore » also find evidence for an epoch-dependence of the evolution as determined previously for radio-quiet AGNs. We interpret both these findings as a strong link between accretion and jet activity. In our sample, the FSRQs evolve strongly, while our best-fit shows that BL Lacs might not evolve at all. The blazar population accounts for 10-20% (depending on the evolution of the BL Lacs) of the Cosmic X-ray background (CXB) in the 15-55 keV band. We find that FSRQs can explain the entire CXB emission for energies above 500 keV solving the mystery of the generation of the MeV background. The evolution of luminous FSRQs shows a peak in redshift (z{sub c} = 4.3 {+-} 0.5) which is larger than the one observed in QSOs and X-ray selected AGNs. We argue that FSRQs can be used as tracers of massive elliptical galaxies in the early Universe.« less

HESS J1943+213: A Non-classical High-frequency-peaked BL Lac Object

NASA Astrophysics Data System (ADS)

Straal, S. M.; Gabányi, K. É.; van Leeuwen, J.; Clarke, T. E.; Dubner, G.; Frey, S.; Giacani, E.; Paragi, Z.

2016-05-01

HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object, but that is also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported by some of the observed unusual characteristics. In order to finally classify and understand this object, we took a three-pronged approach, through time-domain, high angular resolution, and multi-frequency radio studies. First, our deep time-domain observations with the Arecibo telescope failed to uncover the putative pulsar powering the proposed PWN. We conclude with ˜70% certainty that HESS J1943+213 does not host a pulsar. Second, long-baseline interferometry of the source with e-MERLIN at 1.5 and 5 GHz shows only a core, that is, a point source at ˜ 1-100 mas resolution. Its 2013 flux density is about one-third lower than that detected in the 2011 observations with similar resolution. This radio variability of the core strengthens the HBL object hypothesis. Third, additional evidence against the PWN scenario comes from the radio spectrum we compiled. The extended structure follows a power-law behavior with spectral index α \\=\\-0.54+/- 0.04 while the core component displays a flat spectrum (α \\=\\-0.03+/- 0.03). In contrast, the radio synchrotron emission of PWNe predicts a single power-law distribution. Overall, we rule out the PWN hypothesis and conclude that the source is a BL Lac object. The consistently high fraction (70%) of the flux density from the extended structure then leads us to conclude that HESS J1943+213 must be a non-classical HBL object.

A KPC-Scale X-Ray Jet in the BL Lac Source S5 2007+777

NASA Technical Reports Server (NTRS)

Sambruna, Rita M.; Donato, Davide; Cheung, C.C.; Tavecchio, F.; Maraschi, L.

2008-01-01

X-ray jets in AGN are commonly observed in FRII and FRI radiogalaxies, but rarely in BL Lacs, most probably due to their orientation close to the line of sight and the ensuing foreshortening effects. Only three BL Lacs are known so far to contain a kpc-scale X-ray jet. In this paper, we present the evidence for the existence of a fourth extended X-ray jet in the classical radio-selected source S5 2007+777, which for its hybrid FRI/II radio morphology has been classified as a HYMOR (HYbrid MOrphology Radio source). Our Chandra ACISS observations of this source revealed an X-ray counterpart to the 19"-long radio jet. Interestingly, the X-ray properties of the kpc-scale jet in S5 2007+777 are very similar to those observed in FRII jets. First, the X-ray morphology closely mirrors the radio one, with the X-rays being concentrated in the discrete radio knots. Second, the X-ray continuum of the jet/brightest knot is described by a very hard power law, with photon index gamma(sub x) approximately 1. Third, the optical upper limit from archival HST data implies a concave radio-to-X-ray SED. If the X-ray emission is attributed to IC/CMB with equipartition, strong beaming (delta= 13) is required, implying a very large scale (Mpc) jet. The beaming requirement can be somewhat relaxed assuming a magnetic field lower than equipartition. Alternatively, synchrotron emission from a second population of very high-energy electrons is viable. Comparison to other HYMOR jets detected with Chandra is discussed, as well as general implications for the origin of the FRI/II division.

Research and characterisation of blazar candidates among the Fermi/LAT 3FGL catalogue using multivariate classifications

NASA Astrophysics Data System (ADS)

Lefaucheur, Julien; Pita, Santiago

2017-06-01

Context. In the recently published 3FGL catalogue, the Fermi/LAT collaboration reports the detection of γ-ray emission from 3034 sources obtained after four years of observations. The nature of 1010 of those sources is unknown, whereas 2023 have well-identified counterparts in other wavelengths. Most of the associated sources are labelled as blazars (1717/2023), but the BL Lac or FSRQ nature of 573 of these blazars is still undetermined. Aims: The aim of this study was two-fold. First, to significantly increase the number of blazar candidates from a search among the large number of Fermi/LAT 3FGL unassociated sources (case A). Second, to determine the BL Lac or FSRQ nature of the blazar candidates, including those determined as such in this work and the blazar candidates of uncertain type (BCU) that are already present in the 3FGL catalogue (case B). Methods: For this purpose, multivariate classifiers - boosted decision trees and multilayer perceptron neural networks - were trained using samples of labelled sources with no caution flag from the 3FGL catalogue and carefully chosen discriminant parameters. The decisions of the classifiers were combined in order to obtain a high level of source identification along with well controlled numbers of expected false associations. Specifically for case A, dedicated classifications were generated for high (| b | >10◦) and low (| b | ≤10◦) galactic latitude sources; in addition, the application of classifiers to samples of sources with caution flag was considered separately, and specific performance metrics were estimated. Results: We obtained a sample of 595 blazar candidates (high and low galactic latitude) among the unassociated sources of the 3FGL catalogue. We also obtained a sample of 509 BL Lacs and 295 FSRQs from the blazar candidates cited above and the BCUs of the 3FGL catalogue. The number of expected false associations is given for different samples of candidates. It is, in particular, notably low ( 9/425) for the sample of high-latitude blazar candidates from case A. Full Tables 5 and 7 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A86

The Gamma-Ray Bright BL Lac Object RX J1211+2242

NASA Technical Reports Server (NTRS)

Beckmann, V.; Favre, P.; Tavecchio, F.; Bussien, T.; Fliri, J.; Wolter, A.

2004-01-01

RX J1211+2242 is an optically faint (B approximately equal to 19.2mag) but X-ray bright (f2-10kev = 5 x l0(exp -12)erg per square centimeter per second) AGN, which has been shown to be a BL Lac object at redshift z = 0.455. The ROSAT X-ray, Calar Alto optical, and NVSS radio data suggest that the peak of the synchrotron emission of this object is at energies as high as several keV. BeppoSAX observations have been carried out simultaneously with optical observations in order to extend the coverage to higher energies. The new data indeed indicate a turn-over in the 2 - 10keV energy region. We propose that RX J1211+2242 is the counterpart of the unidentified EGRET source 3EG J1212+2304, making it a gamma-ray emitter with properties similar to, for example, Markarian 501 in its bright state, though being at a much larger distance.

Multiwavelength Observations of Markarian 421 During a TeV/X-Ray Flare

NASA Technical Reports Server (NTRS)

Bertsch, D. L.; Bruhweiler, F.; Macomb, D. J.; Cheng, K.-P.; Carter-Lewis, D. A.; Akerlof, C. W.; Aller, H. D.; Aller, M. F.; Buckley, J. H.; Cawley, M. F.

1995-01-01

A TeV flare from the BL Lac object Mrk 421 was detected in May of 1994 by the Whipple Observatory air Cherenkov experiment during which the flux above 250 GeV increased by nearly an order of magnitude over a 2-day period. Contemporaneous observations by ASCA showed the X-ray flux to be in a very high state. We present these results, combined with the first ever simultaneous or nearly simultaneous observations at GeV gamma-ray, UV, IR, mm, and radio energies for this nearest BL Lac object. While the GeV gamma-ray flux increased slightly, there is little evidence for variability comparable to that seen at TeV and X-ray energies. Other wavelengths show even less variability. This provides important constraints on the emission mechanisms at work. We present the multiwavelength spectrum of this gamma-ray blazar for both quiescent and flaring states and discuss the data in terms of current models of blazar emission.

Kepler Observations of Rapid Optical Variability in the BL Lac Object W2r192+42

NASA Technical Reports Server (NTRS)

R.Edelson; Mushotzky, R.; Vaughn, S.; Scargle, J.; Gandhi, P.; Malkan, M.; Baumgartner, W.

2013-01-01

We present the first Kepler monitoring of a strongly variable BL Lac, W2R1926+42. The light curve covers 181 days with approx. 0.2% errors, 30 minute sampling and >90% duty cycle, showing numerous delta-I/I > 25% flares over timescales as short as a day. The flux distribution is highly skewed and non-Gaussian. The variability shows a strong rms-flux correlation with the clearest evidence to date for non-linearity in this relation. We introduce a method to measure periodograms from the discrete autocorrelation function, an approach that may be well-suited to a wide range of Kepler data. The periodogram is not consistent with a simple power-law, but shows a flattening at frequencies below 7x10(exp -5) Hz. Simple models of the power spectrum, such as a broken power law, do not produce acceptable fits, indicating that the Kepler blazar light curve requires more sophisticated mathematical and physical descriptions than currently in use.

VizieR Online Data Catalog: Blazars equivalent widths and radio luminosity (Landt+, 2004)

NASA Astrophysics Data System (ADS)

Landt, H.; Padovani, P.; Perlman, E. S.; Giommi, P.

2004-07-01

Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marcha et al. (1996MNRAS.281..425M). We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS, Cat. and ) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]{lambda}5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]{lambda}5007-[OII]{lambda}3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars. (4 data files).

Mutation Spectrum Induced by Conazole Fungicides in LacI Transgenic C57BL/6 Mouse Liver.

EPA Science Inventory

Conazoles are antifungal agents used in both agricultural and pharmaceutical settings. Some conazoles, including propiconazole and triadimefon, induce hepatocellular tumors in mice, while other conazoles do not. We reported in a previous study that both propiconazole and triadime...

Optical Spectroscopic Observations of γ-Ray Blazar Candidates. III. The 2013/2014 Campaign in the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Landoni, M.; Massaro, F.; Paggi, A.; D'Abrusco, R.; Milisavljevic, D.; Masetti, N.; Smith, H. A.; Tosti, G.; Chomiuk, L.; Strader, J.; Cheung, C. C.

2015-05-01

We report the results of our exploratory program carried out with the southern Astrophysical Research telescope aimed at associating counterparts and establishing the nature of the Fermi Unidentified γ-ray Sources (UGSs). We selected the optical counterparts of six UGSs from the Fermi catalog on the basis of our recently discovered tight connection between infrared and γ-ray emission found for the γ-ray blazars detected by the Wide-Field Infrared Survey Explorer in its all-sky survey. We perform for the first time a spectroscopic study of the low-energy counterparts of the Fermi UGSs, in the optical band, confirming the blazar-like nature of the whole sample. We also present new spectroscopic observations of six active galaxies of uncertain type associated with Fermi sources which appear to be BL Lac objects. Finally, we report the spectra collected for six known γ-ray blazars belonging to the Roma BZCAT that were obtained to establish their nature or better estimate their redshifts. Two interesting cases of high redshift and extremely luminous BL Lac objects (z ≥ 1.18 and z ≥ 1.02, based on the detection of Mg ii intervening systems) are also discussed. Based on observations obtained at the southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

The Study on the Physical Properties of Blazar Jets

NASA Astrophysics Data System (ADS)

Kang, S. J.

2017-09-01

Active galactic nuclei (AGNs) belong to a special class of active galaxies, and have violent active phenomena and intense physical processes in the nuclei. Blazar is a subclass of AGNs, and has a relativistic jet with a small jet viewing angle. Therefore, the boosting effect is very important, and almost all the observed radiation is dominated by the jet. The relativistic jet physics is not very clear yet, such as the jet formation, collimation, and matter content etc. The multi-waveband radiation of blazar is dominated by jet, which provides an ideal laboratory for studying the jet physics. The first chapter of this thesis introduces the recent progress of AGNs and blazars. We further introduce the jet model that commonly used in blazars in the second chapter. In the third chapter, we fit simultaneously (or quasi-simultaneously) the multi-waveband spectral energy distributions (SEDs) for a sample of low-synchrotron-peaked (LSP) blazars with the jet model and χ2 procedure, which takes into account different soft photon fields (broad line region or a molecular torus). We find that the SED fitting with an external soft photon from IR torus is systematically better than that from the broad line region (BLR) based on a χ2 test, which suggests that the γ-ray emitting region most possibly stays outside the BLR. The minimum electron Lorentz factor, γmin, is constrained from the modeling of these LSP blazars with good soft X-ray data, and in a range from 5 to 160 (with a median value of 55), which plays a key role in jet power estimation. Assuming one-to-one ratio of proton and electron, we find that the jet power for LSP blazars is systematically higher than that of Fanaroff-Riley type II (FR II) radio galaxies. A possible reason for this is that there are some positrons in the jets of these blazars. If this is the case, the jet power will be reduced. Therefore, we propose a mixed composition of e±-p in the jets of these LSP blazars. If we assume that the jet power of LSP blazars is the same as that of FR IIs, we find that it is an electron-positron pair dominated leptonic jet in these blazars, and the number density of electron-positron pairs is several times higher than that of electron-proton pairs, but the jet power is still dominated by protons. For the high-synchrotron-peaked (HSP) BL Lac PKS 1424+240, the SED fitting with the synchrotron self-Compton (SSC) model gave unreasonable fitting parameters (e.g., a very large Doppler factor δ). In this work, we take into account the possible external soft photon field, and then fit the multi-waveband SEDs of blazar PKS 1424+240 with one-zone leptonic jet models in both states. We find the SSC+external-Compton (EC) model can give a better fitting result if the EC process is included. However, the needed energy density of external soft photon field (U_{ext}) is much lower than the typical value. This result is consistent with the results of some other BL Lacs, where the BLR or torus is very weak or disappearing. It means that there is evolution of the energy density of external soft photon field with decreasing of the luminosity of blazars (the flat spectrum radio quasars (FSRQs)-BL Lac: low energy peaked BL Lac (LBL)-intermediate energy peaked BL Lac (IBL)-high energy peaked BL Lac (HBL)). And on this basis, in the chapter 5, we further explore the possible evolution of the external soft photon field of blazars based on the EC process. We employ the one-zone homogeneous leptonic jet model and χ2 procedure to fit simultaneously or quasi-simultaneously multi-waveband SEDs for a sample of blazars with a wide distribution of luminosities. In our model, we set Uext as a free parameter. Studying the energy density of the external photon field in different subclasses of blazars, we find: (1) the Uext of the high luminosity blazar (FSRQs and LBLs) keeps roughly as a constant, which is, however, smaller than that constrained from BLR observations. Assuming IR as the source of soft photons, the Uext is roughly consistent with the torus observational result. This further supports the result that the external soft photon field may originate from torus, and the γ-ray emitting region of these LSP blazars locates outside the BLR. (2) For some IBLs, the EC process may be still needed, but the photon energy density is less than the typical values of the photon energy density of BLR (or dust torus), where the Uext decreases with decreasing of the luminosity. This evolution is consistent with the BLR or torus as directly constrained from the radio-quiet AGN. The final part summarizes the study on the subject, and makes some suggestions for further researches.

Detection of the BL Lac object 1ES 1426+428 in the Very High Energy gamma-ray band by the CAT Telescope from 1998-2000

NASA Astrophysics Data System (ADS)

Djannati-Ataï, A.; Khelifi, B.; Vorobiov, S.; Bazer-Bachi, R.; Chounet, L. M.; Debiais, G.; Degrange, B.; Espigat, P.; Fabre, B.; Fontaine, G.; Goret, P.; Gouiffes, C.; Masterson, C.; Piron, F.; Punch, M.; Rivoal, M.; Rob, L.; Tavernet, J.-P.

2002-08-01

The BL Lac Object 1ES 1426+428, at a red-shift of z=0.129, has been monitored by the CAT telescope from February 1998 to June 2000. The accumulation of 26 h of observations shows a gamma -ray signal of 321 events above 250 GeV at 5.2 standard deviations, determined using data analysis cuts adapted to a weak, steep-spectrum source. The source emission has an average flux of Phidiff(400 GeV)= 6.73+/-1.27stat+/-1.45syst*E-11 cm-2 s-1 TeV-1, and a very steep spectrum, with a differential spectral index of gamma =-3.60 +/- 0.57 which can be refined to gamma =-3.66 +/- 0.41 using a higher flux data subset. If, as expected from its broad-band properties, the Very High Energy emission is hard at the source, these observations support a strong absorption effect of gamma-rays by the Intergalactic Infrared field.

Contemporaneous broadband observations of three high-redshift BL Lac objects

DOE PAGES

Ackerman, M.

2016-03-20

We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects, 3FGL J0022.1-1855 (z=0.689), 3FGL J0630.9-2406 (z > ~1.239), and 3FGL J0811.2-7529 (z=0.774), detected by Fermi with relatively flat GeV spectra. By observing simultaneously in the near-IR to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the GeV Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, withmore » poorer fits for high UV models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest redshift source 3FGL J0630.9-2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components.« less

Multi-epoch intranight optical monitoring of eight radio-quiet BL Lac candidates

NASA Astrophysics Data System (ADS)

Kumar, P.; Gopal-Krishna; Stalin, C. S.; Chand, H.; Srianand, R.; Petitjean, P.

2017-10-01

For a new sample of eight weak-line quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time-scale (day/month/year-like). The sample consists exclusively of the WLQs that are not radio-loud and either have been classified as 'radio-weak probable BL Lac candidates' and/or are known to have exhibited at least one episode of large, blazar-like optical variability. Whereas only a hint of intranight variability is seen for two of these WLQs, J104833.5+620305.0 (z = 0.219) and J133219.6+622715.9 (z = 3.15), statistically significant internight variability at a few per cent level is detected for three of the sources, including the radio-intermediate WLQ J133219.6+622715.9 (z = 3.15) and the well-known bona fide radio-quiet WLQs J121221.5+534128.0 (z = 3.10) and WLQ J153259.9-003944.1 (z = 4.62). In the rest frame, this variability is intraday and in the far-ultraviolet band. On the time-scale of a decade, we find for three of the WLQs large brightness changes, amounting to 1.655 ± 0.009, 0.163 ± 0.010 and 0.144 ± 0.018 mag, for J104833.5+620305.0, J123743.1+630144.9 and J232428.4+144324.4, respectively. Whereas the latter two are confirmed radio-quiet WLQs, the extragalactic nature of J104833.5+620305.0 remains to be well established, thanks to the absence of any feature(s) in its available optical spectra. This study forms a part of our ongoing campaign of intranight optical monitoring of radio-quiet WLQs, in order to improve the understanding of this enigmatic class of active galactic nuclei and to look among them for a possible tiny, elusive population of radio-quiet BL Lacs.

Multiwavelength observations of the blazar 1ES 1011+496 in Spring 2008

NASA Astrophysics Data System (ADS)

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Di Pierro, F.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Eisenacher Glawion, D.; Godinović, N.; González Muñoz, A.; Guberman, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saito, T.; Satalecka, K.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; Lucarelli, F.; Pittori, C.; Vercellone, S.; Berdyugin, A.; Carini, M. T.; Lähteenmäki, A.; Pasanen, M.; Pease, A.; Sainio, J.; Tornikoski, M.; Walters, R.

2016-07-01

The BL Lac object 1ES 1011+496 was discovered at very high energy (VHE, E > 100GeV) γ-rays by Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) in Spring 2007. Before that the source was little studied in different wavelengths. Therefore, a multiwavelength (MWL) campaign was organized in Spring 2008. Along MAGIC, the MWL campaign included the Metsähovi Radio Observatory, Bell and Kungliga Vetenskapsakademien (KVA) optical telescopes and the Swift and AGILE satellites. MAGIC observations span from 2008 March to May for a total of 27.9 h, of which 19.4 h remained after quality cuts. The light curve showed no significant variability yielding an integral flux above 200 GeV of (1.3 ± 0.3) × 10-11 photons cm-2 s-1. The differential VHE spectrum could be described with a power-law function with a spectral index of 3.3 ± 0.4. Both results were similar to those obtained during the discovery. Swift X-ray Telescope observations revealed an X-ray flare, characterized by a harder-when-brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE γ-ray bands could be drawn. The contemporaneous spectral energy distribution shows a synchrotron-dominated source, unlike concluded in previous work based on non-simultaneous data, and is well described by a standard one-zone synchrotron self-Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects.

Internal absorption of gamma-rays in relativistic blobs of active galactic nuclei

NASA Astrophysics Data System (ADS)

Sitarek, Julian; Bednarek, Wlodek

2007-06-01

We investigate the production of gamma-rays in the inverse Compton (IC) scattering process by leptons accelerated inside relativistic blobs in jets of active galactic nuclei. Leptons are injected homogeneously inside the spherical blob and initiate IC e ± pair cascade in the synchrotron radiation (produced by the same population of leptons, SSC model), provided that the optical depth for gamma-rays is larger than unity. It is shown that for likely parameters internal absorption of gamma-rays has to be important. We suggest that new type of blazars might be discovered by the future simultaneous X-ray and γ-ray observations, showing peak emissions in the hard X-rays, and in the GeV γ-rays. Moreover, the considered scenario might be also responsible for the orphan X-ray flares recently reported from BL Lac type active galaxies.

Fermi LAT detection of increased gamma-ray activity from blazar S5 0716+71

NASA Astrophysics Data System (ADS)

Buson, S.

2014-04-01

The Large Area Telescope (LAT), one of two instruments on-board the Fermi Gamma-ray Space Telescope, has observed an increase in gamma-ray activity from a source positionally coincident with the BL Lac object S5 0716+71 (also known as 2FGL J0721.9+7120, Nolan et al. ...

The first Fermi multifrequency campaign on BL Lacertae: Characterizing the low-activity state of the eponymous blazar

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2011-03-10

Here, we report on observations of BL Lacertae during the first 18 months of Fermi LAT science operations and present results from a 48 day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low-activity state thanks to the coordinated observations of radio-band (Metsähovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH, and MDM), and X-ray ( RXTE and Swift) observatories. No variability was resolved in gamma rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderatemore » and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave, indicating the transition region between the low- and high-energy components of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the average magnetic field there to be less than 3 G. Over the following months, BL Lac appeared variable in gamma rays, showing flares (in 2009 April and 2010 January). There is no evidence for the correlation of gamma rays with the optical flux monitored from the ground in 18 months. The SED may be described by a single-zone or a two-zone synchrotron self-Compton (SSC) model, but a hybrid SSC plus external radiation Compton model seems to be preferred based on the observed variability and the fact that it provides a fit closest to equipartition.« less

Multiwavelength Observations of the Previously Unidentified Blazar RX J0648.7+1516

NASA Astrophysics Data System (ADS)

Aliu, E.; Aune, T.; Beilicke, M.; Benbow, W.; Böttcher, M.; Bouvier, A.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Cannon, A.; Cesarini, A.; Ciupik, L.; Connolly, M. P.; Cui, W.; Decerprit, G.; Dickherber, R.; Duke, C.; Errando, M.; Falcone, A.; Feng, Q.; Finnegan, G.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gillanders, G. H.; Godambe, S.; Griffin, S.; Grube, J.; Gyuk, G.; Hanna, D.; Hivick, B.; Holder, J.; Huan, H.; Hughes, G.; Hui, C. M.; Humensky, T. B.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Maier, G.; Majumdar, P.; McArthur, S.; McCann, A.; Moriarty, P.; Mukherjee, R.; Nelson, T.; Ong, R. A.; Orr, M.; Otte, A. N.; Park, N.; Perkins, J. S.; Pichel, A.; Pohl, M.; Prokoph, H.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Roache, E.; Rose, H. J.; Ruppel, J.; Saxon, D. B.; Sembroski, G. H.; Skole, C.; Smith, A. W.; Staszak, D.; Tešić, G.; Theiling, M.; Thibadeau, S.; Tsurusaki, K.; Tyler, J.; Varlotta, A.; Vassiliev, V. V.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Williams, D. A.; Zitzer, B.; VERITAS Collaboration; Ciprini, S.; Fumagalli, M.; Kaplan, K.; Paneque, D.; Prochaska, J. X.

2011-12-01

We report on the VERITAS discovery of very high energy (VHE) gamma-ray emission above 200 GeV from the high-frequency-peaked BL Lac (HBL) object RX J0648.7+1516 (GB J0648+1516), associated with 1FGL J0648.8+1516. The photon spectrum above 200 GeV is fitted by a power law dN/dE = F 0(E/E 0)-Γ with a photon index Γ of 4.4 ± 0.8stat ± 0.3syst and a flux normalization F 0 of (2.3 ± 0.5stat ± 1.2sys) × 10-11 TeV-1 cm-2 s-1 with E 0 = 300 GeV. No VHE variability is detected during VERITAS observations of RX J0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identification and spectroscopic redshift were obtained using the Shane 3 m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to subclassify the blazar as an HBL object, including data from the MDM observatory, Swift-UVOT, and X-Ray Telescope, and continuous monitoring at photon energies above 1 GeV from the Fermi Large Area Telescope (LAT). We find that in the absence of undetected, high-energy rapid variability, the one-zone synchrotron self-Compton (SSC) model overproduces the high-energy gamma-ray emission measured by the Fermi-LAT over 2.3 years. The spectral energy distribution can be parameterized satisfactorily with an external-Compton or lepto-hadronic model, which have two and six additional free parameters, respectively, compared to the one-zone SSC model.

Tetherin promotes the innate and adaptive cell-mediated immune response against retrovirus infection in vivo.

PubMed

Li, Sam X; Barrett, Bradley S; Heilman, Karl J; Messer, Ronald J; Liberatore, Rachel A; Bieniasz, Paul D; Kassiotis, George; Hasenkrug, Kim J; Santiago, Mario L

2014-07-01

Tetherin/BST-2 is a host restriction factor that could directly inhibit retroviral particle release by tethering nascent virions to the plasma membrane. However, the immunological impact of Tetherin during retrovirus infection remains unknown. We now show that Tetherin influences antiretroviral cell-mediated immune responses. In contrast to the direct antiviral effects of Tetherin, which are dependent on cell surface expression, the immunomodulatory effects are linked to the endocytosis of the molecule. Mice encoding endocytosis-competent C57BL/6 Tetherin exhibited lower viremia and pathology at 7 d postinfection with Friend retrovirus (FV) compared with mice encoding endocytosis-defective NZW/LacJ Tetherin. Notably, antiretroviral protection correlated with stronger NK cell responses. In addition, Friend retrovirus infection levels were significantly lower in wild-type C57BL/6 mice than in Tetherin knockout mice at 2 wk postinfection, and antiretroviral protection correlated with stronger NK cell and virus-specific CD8+ T cell responses. The results demonstrate that Tetherin acts as a modulator of the cell-mediated immune response against retrovirus infection in vivo.

JET PROPERTIES OF GeV-SELECTED RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXIES AND POSSIBLE CONNECTION TO THEIR DISK AND CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao-Na; Lin, Da-Bin; Liang, En-Wei

The observed spectral energy distributions of five GeV-selected narrow-line Seyfert 1 (NLS1) galaxies are fitted with a model including the radiation ingredients from the relativistic jet, the accretion disk, and the corona. We compare the properties of these GeV NLS1 galaxies with flat spectrum radio quasars (FSRQs), BL Lacertae objects (BL Lacs), and radio-quiet (RQ) Seyfert galaxies, and explore possible hints for jet-disk/corona connection. Our results show that the radiation physics and the jet properties of the GeV NLS1 galaxies resemble that of FSRQs. The luminosity variations of PMN J0948+0022 and 1H 0323+342 at the GeV band is tightly correlatedmore » with the beaming factor (δ), similar to that observed in FSRQ 3C 279. The accretion disk luminosities and the jet powers of the GeV NLS1 galaxies cover both the ranges of FSRQs and BL Lacs. With the detection of bright corona emission in 1H 0323+342, we show that the ratio of the corona luminosity (L {sub corona}) to the accretion disk luminosity (L {sub d}) is marginally within the high end of this ratio distribution for an RQ Seyfert galaxy sample, and the variation of jet luminosity may connect with L {sub corona}. However, it is still unclear whether a system with a high L {sub corona}/L {sub d} ratio prefers to power a jet.« less

Development of amnesia in different mouse strains.

PubMed

Sinovyev, D R; Dubrovina, N I; Kulikov, A V

2009-05-01

We studied passive avoidance retrieval after amnestic stimulation (arrest in unsafe section of the experimental setup) in C57Bl/6J, BALB/c, CBA/Lac, AKR/J, DBA/2J, C3H/HeJ, and ASC/Icg mice. We demonstrated resistance to amnestic stimulation in mice with high predisposition to freezing reaction (ASC/Icg) and memory deficit in other mouse strains.

Microbial β-Galactosidase of Pediococcus pentosaceus ID-7: Isolation, Cloning, and Molecular Characterization.

PubMed

Lee, Ji-Yeong; Kwak, Mi-Sun; Roh, Jong-Bok; Kim, Kwang; Sung, Moon-Hee

2017-03-28

Pediococcus pentosaceus ID-7 was isolated from kimchi, a Korean fermented food, and it showed high activity for lactose hydrolysis. The β-galactosidase of P. pentosaceus ID-7 belongs to the GH2 group, which is composed of two distinct proteins. The heterodimeric LacLM type of β-galactosidase found in P. pentosaceus ID-7 consists of two genes partially overlapped, lacL and lacM encoding LacL (72.2 kDa) and LacM (35.4 kDa). In this study, Escherichia coli MM294 was used for the production of LacL, LacM, and LacLM. These three types of recombinant proteins were expressed, purified, and characterized. The specific activities of LacLM and LacL were 339 and 31 U/mg, respectively. However, activity was not detected with LacM alone. The optimal pH of LacLM and LacL was pH 7.5 and pH 7.0, and the optimal temperature of LacLM and LacL was 40°C and 50°C, respectively. The optimal temperature changes indicate that LacLM is able to achieve higher activity at a relatively lower temperature. LacLM was strongly activated by Mg 2+ , Mn 2+ , and Zn 2+ , which was not true for LacL. Consistent with this, EDTA strongly inactivated LacLM and LacL, but the presence of reducing agents did not dramatically alter the activity. Taken together, multiple alignment of amino acid sequences and phylogenetic analysis results of LacL and LacM of P. pentosaceus ID-7 suggest the evolution of LacL into LacLM and that the use of divalent metal ions results in higher activity.

Kiloparsec Jet Properties of Hybrid, Low-, and High-Synchrotron-Peaked Blazars

NASA Astrophysics Data System (ADS)

Stanley, Ethan C.

Blazars are a rare class of active galactic nucleus (AGN) with relativistic jets closely aligned with the line of sight. Many aspects of the environments and kiloparsec-scale jet structure are not fully understood. Hybrid and high synchrotron peaked (HSP) blazars are two types of blazar that provide unique opportunities to study these jets. Hybrid blazars appear to have jets of differing morphology on each side of their core, suggesting that external factors shape their jet morphology. Three hybrid sources were investigated in radio, optical, and X-ray wavelengths: 8C 1849+670, PKS 2216-038, and PKS 1045-188. For all three, X-ray emission was detected only from the approaching jet. All three had jet radio flux densities and emission mechanisms similar to higher-power FR II sources, but two had approaching jets similar to lower-power FR I sources. None of the three showed definitive signs of asymmetry in their external environments. These results agree with previous multiwavelength studies of hybrid sources that show a dominance of FR I approaching jets and FR II emission mechanisms. With the addition of these three hybrid sources, 13 have been studied in total. Eleven have FR I approaching jets, and eight of those have FR II emission mechanisms. These trends may be due to small number statistics, or they may indicate other factors are creating hybrid-like appearances. High synchrotron peaked blazars are defined by the frequency of the peak of their jet synchrotron emission. Some have shown extreme variability which would imply incredibly-powerful and well-aligned jets, but VLBA observations have measured only modest jet speeds. A radio survey was performed to measure the extended radio luminosity of a large sample of HSP sources. These sources were compared to the complete radio flux density limited MOJAVE 1.5 Jy sample. Flat spectrum radio quasars (FSRQs) showed significant overlap with low synchrotron peaked (LSP) BL Lacs in multiple parameters, which may suggest that many FSRQs are "masquerading'' as LSP BL Lacs. HSP BL Lacs showed slightly lower extended radio luminosities and significantly lower maximum apparent jet speeds, suggesting that they are intrinsically weaker sources. There was a good correlation between maximum apparent jet speed and extended radio luminosity, which supports using the extended radio luminosity as a measure of intrinsic jet power. There was a lack of TeV-detected sources with higher extended radio luminosities, which suggests TeV emission may favor low power jets or high synchrotron peak frequencies. The apparent low power of HSP sources and TeV-detected sources questions any model of TeV emission and variability that depends on the jet (or a part of it) being intrinsically powerful.

Testing the Pairs-Reflection Model with X-Ray Spectral Variability and X-Ray Properties of Complete Samples of Radio-Selected BL Lacertae Objects

NASA Astrophysics Data System (ADS)

Urry, C. Megan

1997-01-01

This grant was awarded to Dr. C. Megan Urry of the Space Telescope Science Institute in response to two successful ADP proposals to use archival Ginga and Rosat X-ray data for 'Testing the Pairs-Reflection model with X-Ray Spectral Variability' (in collaboration with Paola Grandi, now at the University of Rome) and 'X-Ray Properties of Complete Samples of Radio-Selected BL Lacertae Objects' (in collaboration with then-graduate student Rita Sambruna, now a post-doc at Goddard Space Flight Center). In addition, post-docs Joseph Pesce and Elena Pian, and graduate student Matthew O'Dowd, have worked on several aspects of these projects. The grant was originally awarded on 3/01/94; this report covers the full period, through May 1997. We have completed our project on the X-ray properties of radio-selected BL Lacs.

Radio Telescope Reveals Secrets of Massive Black Hole

NASA Astrophysics Data System (ADS)

2008-04-01

At the cores of many galaxies, supermassive black holes expel powerful jets of particles at nearly the speed of light. Just how they perform this feat has long been one of the mysteries of astrophysics. The leading theory says the particles are accelerated by tightly-twisted magnetic fields close to the black hole, but confirming that idea required an elusive close-up view of the jet's inner throat. Now, using the unrivaled resolution of the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), astronomers have watched material winding a corkscrew outward path and behaving exactly as predicted by the theory. Galactic core and jet Artist's conception of region near supermassive black hole where twisted magnetic fields propel and shape jet of particles (Credit: Marscher et al., Wolfgang Steffen, Cosmovision, NRAO/AUI/NSF). Click on image for high-resolution file. Watch Video of Black-Hole-Powered Jet (Credit: Cosmovision, Wolfgang Steffen) Download: NTSC Format (90MB) | PAL Format (90MB) "We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything we see supports the idea that twisted, coiled magnetic fields are propelling the material outward," said Alan Marscher, of Boston University, leader of an international research team. "This is a major advance in our understanding of a remarkable process that occurs throughout the Universe," he added. Marscher's team studied a galaxy called BL Lacertae (BL Lac), some 950 million light-years from Earth. BL Lac is a blazar, the most energetic type of black-hole-powered galactic core. A black hole is a concentration of mass so dense that not even light can escape its gravitational pull. Supermassive black holes in galaxies' cores power jets of particles and intense radiation in similar objects including quasars and Seyfert galaxies. Material pulled inward toward the black hole forms a flattened, rotating disk, called an accretion disk. As the material moves from the outer edge of the disk inward, magnetic field lines perpendicular to the disk are twisted, forming a tightly-coiled bundle that, astronomers believe, propels and confines the ejected particles. Closer to the black hole, space itself, including the magnetic fields, is twisted by the strong gravitational pull and rotation of the black hole. Theorists predicted that material moving outward in this close-in acceleration region would follow a corkscrew-shaped path inside the bundle of twisted magnetic fields. They also predicted that light and other radiation emitted by the moving material would brighten when its rotating path was aimed most directly toward Earth. Marscher and his colleagues predicted there would also be a flare later when the material hits a stationary shock wave called the "core" some time after it has emerged from the acceleration region. "That behavior is exactly what we saw," Marscher said, when his team followed an outburst from BL Lac. In late 2005 and early 2006, the astronomers watched BL Lac with an international collection of telescopes as a knot of material was ejected outward through the jet. As the material sped out from the neighborhood of the black hole, the VLBA could pinpoint its location, while other telescopes measured the properties of the radiation emitted from the knot. Bright bursts of light, X-rays, and gamma rays came when the knot was precisely at locations where the theories said such bursts would be seen. In addition, the alignment of the radio and light waves -- a property called polarization -- rotated as the knot wound its corkscrew path inside the tight throat of twisted magnetic fields. "We got an unprecedented view of the inner portion of one of these jets and gained information that's very important to understanding how these tremendous particle accelerators work," Marscher said. In addition to the continent-wide VLBA, an array of 10 radio telescopes spread from Hawaii to the Virgin Islands, the team used telescopes at the Steward Observatory, the Crimean Astrophysical Observatory, Lowell Observatory, Perugia University Astronomical Observatory, Abastumani Astrophysical Observatory, NASA's Rossi X-Ray Timing Explorer, the University of Michigan Radio Astronomy Observatory, and the Metsahovi Radio Observatory. The astronomers reported their findings in the April 24 issue of the journal Nature. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The Millimeter-Radio Emission of BL Lacertae During Two γ-ray Outbursts

NASA Astrophysics Data System (ADS)

Kim, Dae-Won; Trippe, Sascha; Lee, Sang-Sung; Park, Jong-Ho; Kim, Jae-Young; Algaba, Juan-Carlos; Hodgson, Jeffrey A.; Kino, Motoki; Zhao, Guang-Yao; Wajima, Kiyoaki; Kang, Sincheol; Oh, Junghwan; Lee, Taeseok; Byun, Do-Young; Kim, Soon-Wook; Kim, Jeong-Sook

2017-12-01

We present a study of the inexplicit connection between radio jet activity and γ-ray emission of BL Lacertae (BL Lac; 2200+420). We analyze the long-term millimeter activity of BL Lac via interferometric observations with the Korean VLBI Network (KVN) obtained at 22, 43, 86, and 129 GHz simultaneously over three years (from January 2013 to March 2016); during this time, two γ-ray outbursts (in November 2013 and March 2015) can be seen in γ-ray light curves obtained from Fermi observations. The KVN radio core is optically thick at least up to 86 GHz; there is indication that it might be optically thin at higher frequencies. To first order, the radio light curves decay exponentially over the time span covered by our observations, with decay timescales of 411±85 days, 352±79 days, 310±57 days, and 283±55 days at 22, 43, 86, and 129 GHz, respectively. Assuming synchrotron cooling, a cooling time of around one year is consistent with magnetic field strengths B=2 μT and electron Lorentz factors γ=10,000. Taking into account that our formal measurement errors include intrinsic variability and thus over-estimate the statistical uncertainties, we find that the decay timescale τ scales with frequency ν like τ∝ν^{-0.2}. This relation is much shallower than the one expected from opacity effects (core shift), but in agreement with the (sub-)mm radio core being a standing recollimation shock. We do not find convincing radio flux counterparts to the γ-ray outbursts. The spectral evolution is consistent with the 'generalized shock model' of Valtaoja et al. (1992). A temporary increase in the core opacity and the emergence of a knot around the time of the second γ-ray event indicate that this γ-ray outburst might be an 'orphan' flare powered by the 'ring of fire' mechanism.

Lateral Attitude Change.

PubMed

Glaser, Tina; Dickel, Nina; Liersch, Benjamin; Rees, Jonas; Süssenbach, Philipp; Bohner, Gerd

2015-08-01

The authors propose a framework distinguishing two types of lateral attitude change (LAC): (a) generalization effects, where attitude change toward a focal object transfers to related objects, and (b) displacement effects, where only related attitudes change but the focal attitude does not change. They bring together examples of LAC from various domains of research, outline the conditions and underlying processes of each type of LAC, and develop a theoretical framework that enables researchers to study LAC more systematically in the future. Compared with established theories of attitude change, the LAC framework focuses on lateral instead of focal attitude change and encompasses both generalization and displacement. Novel predictions and designs for studying LAC are presented. © 2014 by the Society for Personality and Social Psychology, Inc.

[Action of red polarized light on the acupuncture point E-36 increases analgesic effect of corvitin].

PubMed

Tamarova, Z A; Lymans'kyĭ, Iu P; Kostiuk, O I; Mitruzaeva, V A; Lymans'ka, L I

2010-01-01

In experiments on mice of lines C57BL/6J and CBA/CaLac, the possibility of strengthening of analgesic effect of corvitin by the action of red polarized light (PL) on the acupoint (AP) E-36 was studied. The pain behavioral response (licking of the painful area) was caused by injection of 5% formalin in hind limb (0.25 microl subcutaneously). The duration of pain response was studied before and after systemic introduction of corvitin (10 mg/kg, intraperitoneal) or joint use of corvitin and red PL (10 minute session). It is established, that after application of red PL on the antinociceptive AP E-36 in all animals an authentic strengthening of antinociceptive effect of corvitin takes place. In C57BL/6J mice, application of corvitin alone weakened the pain response by 29.7% and during combined use of red PL and corvitin, it grew up to 53.1%. Mice of line CBA/CaLac were less sensitive both to corvitin, and PL. In this line, corvitin used alone reduced the duration of pain response by 14%, and by 32.4% during combined use with red PL. Non-traumatic, without side effects, the method of influence by low-intensive PL can be recommended to patients accepting corvitin for strengthening its efficiency.

Multi-wavelength study of flaring activity in BL Lac object S5 0716+714 during the 2015 outburst

DOE PAGES

Chandra, Sunil; Zhang, Haocheng; Kushwaha, Pankaj; ...

2015-08-17

We present a detailed investigation of the flaring activity observed from a BL Lac object, S5 0716+714 , during its brightest ever optical state in the second half of 2015 January. Observed almost simultaneously in the optical, X-rays, and γ-rays, a significant change in the degree of optical polarization (PD) and a swing in the position angle (PA) of polarization were recorded. A TeV (VHE) detection was also reported by the MAGIC consortium during this flaring episode. Two prominent sub-flares, peaking about five days apart, were seen in almost all of the energy bands. The multi-wavelength light curves, spectral energymore » distribution, and polarization are modeled using the time-dependent code developed by Zhang et al. This model assumes a straight jet threaded by large-scale helical magnetic fields taking into account the light travel time effects, incorporating synchrotron flux and polarization in 3D geometry. Furthermore, the rapid variation in PD and rotation in PA are most likely due to reconnections happening in the emission region in the jet, as suggested by the change in the ratio of toroidal to poloidal components of the magnetic field during the quiescent and flaring states.« less

Determination of the Point-Spread Function for the FERMI Large Area Telescope from On-Orbit Data and Limits on Pair Halos of Active Galactic Nuclei

DOE PAGES

Ackermann, M.; Ajello, M.; Allafort, A.; ...

2013-02-15

We present the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from ≈20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of γ rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broadermore » than the pre-launch PSF. We checked for dependence of the PSF on the class of γ-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. Finally, we found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229+200 and 1ES0347–121.« less

Long Term Observations of B2 1215+30 with VERITAS

NASA Astrophysics Data System (ADS)

Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bird, R.; Bouvier, A.; Buckley, J. H.; Bugaev, V.; Cesarini, A.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dumm, J.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gérard, L.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Hughes, G.; Humensky, T. B.; Kaaret, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Madhavan, A. S.; Maier, G.; Majumdar, P.; McArthur, S.; McCann, A.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Orr, M.; Otte, A. N.; Park, N.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Saxon, D. B.; Sembroski, G. H.; Skole, C.; Smith, A. W.; Soares-Furtado, M.; Staszak, D.; Telezhinsky, I.; Tešić, G.; Theiling, M.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Welsing, R.; Williams, D. A.; Zitzer, B.; VERITAS Collaboration; Böttcher, M.; Fumagalli, M.; Jadhav, J.

2013-12-01

We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHEs; E > 100 GeV) by VERITAS with a significance of 8.9σ and showed clear variability on timescales larger than months. In 2011, the source was found to be in a relatively bright state and a power-law fit to the differential photon spectrum yields a spectral index of 3.6 ± 0.4stat ± 0.3syst with an integral flux above 200 GeV of (8.0 ± 0.9stat ± 3.2syst) × 10-12 cm-2 s-1. No short term variability could be detected during the bright state in 2011. Multi-wavelength data were obtained contemporaneously with the VERITAS observations in 2011 and cover optical (Super-LOTIS, MDM, Swift/UVOT), X-ray (Swift/XRT), and gamma-ray (Fermi-LAT) frequencies. These were used to construct the spectral energy distribution (SED) of B2 1215+30. A one-zone leptonic model is used to model the blazar emission and the results are compared to those of MAGIC from early 2011 and other VERITAS-detected blazars. The SED can be reproduced well with model parameters typical for VHE-detected BL Lac objects.

Comparison of Optical and Multi-Waveband Variations of Selected Gamma-ray Bright Blazars in 2012

NASA Astrophysics Data System (ADS)

Schultz, Benjamin; Jorstad, S. G.; Marscher, A. P.; Williamson, K. E.; Walker, G. E.

2013-01-01

We present multi-wavelength observations of several gamma-ray bright blazars. We combine optical data obtained with the 17-inch CCD telescope of Maria Mitchell Observatory with space- and ground-based observations carried out with a variety of instruments. These include a number of other optical telescopes, the Fermi Gamma-Ray Space Telescope at photon energies of 0.1-200 GeV, and the Swift satellite at 0.3-10 keV plus optical and UV wavelengths. Three of the observed blazars proved to be particularly active - BL Lac, Mrk501, and CTA-102. BL Lac was of special interest, displaying remarkable activity in multiple wavelengths during this observation period, including the optical, in which it underwent its largest observed flare in a number of years. In addition, CTA-102 has recently undergone an unprecedented multi-wavelength outburst. We cross-correlate the variations in the different wavebands in an effort to guide theoretical interpretations of the optical and high-energy emission from blazars. This project was supported by NSF/REU grant AST-0851892 and the Nantucket Maria Mitchell Association. The research at Boston University was supported in part by NSF grant AST-0907893 and by NASA through Fermi grant NNX11AQ03G.

Multi-wavelength study of flaring activity in BL Lac object S5 0716+714 during the 2015 outburst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandra, Sunil; Zhang, Haocheng; Kushwaha, Pankaj

We present a detailed investigation of the flaring activity observed from a BL Lac object, S5 0716+714 , during its brightest ever optical state in the second half of 2015 January. Observed almost simultaneously in the optical, X-rays, and γ-rays, a significant change in the degree of optical polarization (PD) and a swing in the position angle (PA) of polarization were recorded. A TeV (VHE) detection was also reported by the MAGIC consortium during this flaring episode. Two prominent sub-flares, peaking about five days apart, were seen in almost all of the energy bands. The multi-wavelength light curves, spectral energymore » distribution, and polarization are modeled using the time-dependent code developed by Zhang et al. This model assumes a straight jet threaded by large-scale helical magnetic fields taking into account the light travel time effects, incorporating synchrotron flux and polarization in 3D geometry. Furthermore, the rapid variation in PD and rotation in PA are most likely due to reconnections happening in the emission region in the jet, as suggested by the change in the ratio of toroidal to poloidal components of the magnetic field during the quiescent and flaring states.« less

MULTI-WAVELENGTH STUDY OF FLARING ACTIVITY IN BL Lac OBJECT S5 0716+714 DURING THE 2015 OUTBURST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandra, Sunil; Kushwaha, Pankaj; Singh, K. P.

We present a detailed investigation of the flaring activity observed from a BL Lac object, S5 0716+714 , during its brightest ever optical state in the second half of 2015 January. Observed almost simultaneously in the optical, X-rays, and γ-rays, a significant change in the degree of optical polarization (PD) and a swing in the position angle (PA) of polarization were recorded. A TeV (VHE) detection was also reported by the MAGIC consortium during this flaring episode. Two prominent sub-flares, peaking about five days apart, were seen in almost all of the energy bands. The multi-wavelength light curves, spectral energymore » distribution, and polarization are modeled using the time-dependent code developed by Zhang et al. This model assumes a straight jet threaded by large-scale helical magnetic fields taking into account the light travel time effects, incorporating synchrotron flux and polarization in 3D geometry. The rapid variation in PD and rotation in PA are most likely due to reconnections happening in the emission region in the jet, as suggested by the change in the ratio of toroidal to poloidal components of the magnetic field during the quiescent and flaring states.« less

Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies

NASA Technical Reports Server (NTRS)

Kondo, Y.; Worrall, D. M.; Oke, J. B.; Yee, H. K. C.; Neugebauer, G.; Matthews, K.; Feldman, P. A.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. R. H.

1981-01-01

Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescope at Green Bank (4750 MHz) and the 46-m radio telescope at the Algonquin Observatory (10275 and 10650 MHz). The quasi-simultaneously observed spectral slope is found to be positive and continuous from the X-ray to the UV, but to gradually flatten and possibly turn down from the mid-UV to the visible; the optical-radio emission cannot be accounted for by a single power law. The total spectrum is shown to be compatible with a synchrotron self-Compton emission mechanism, while the spectrum from the visible to the X-ray is consistent with synchrotron radiation or inverse-Compton scattering by a hot thermal electron cloud. The continuity of the spectrum from the UV to the X-ray is noted to imply a total luminosity greater than previous estimates by a factor of 3-4.

Accretion processes of radio galaxies at high energies

NASA Astrophysics Data System (ADS)

de Jong, Sandra

2013-10-01

AGN are the luminous (L>10^42 erg/s) cores of active galaxies, powered by accretion onto the central super massive black hole, either via an accretion disk or via a radiatively inefficient accretion flow. There are still several open questions, for example on the launching of jets, which are present in about 10% of the AGN. Another question appeared with the Fermi/LAT gamma-ray survey, which detected many blazars but also a small group of radio galaxies. Radio galaxies are postulated to be blazars where the observer sees the jet at an angle θ>10 degrees allowing a view of both jet and core, rather than only the jet as is the case with blazars. Radio galaxies are divided into two classes, depending on the radio luminosity of the jets. The Fanaroff-Riley I (FR-I) sources have jets that are bright near the core, where the FR-IIs display extended edge-brightened jets. The FR-I sources are connected to the BL Lacs, which are low-luminosity blazars. FR-II types are thought to be the parent population of the luminous FSRQ, which are also blazars. This thesis presents a study of gamma-ray bright radio galaxies. By analysing X-ray and gamma-ray data in addition to creating broad-band spectral energy distributions (SEDs), we studied two examples of this new class of sources. For the FR-II source 3C 111 we analysed Suzaku/XIS and PIN and INTEGRAL IBIS/ISGRI observations to create a X-ray spectrum. We also used a Swift/BAT spectrum from the 58-month survey. The 0.4-200 keV spectrum of the source shows both thermal, Seyfert-like signatures such as an iron K-α line, and non-thermal jet features. We also analysed gamma-ray data from Fermi/LAT. The gamma-ray and X-ray data are combined with historical radio, infrared and optical observations to build the SED, which can be well represented with a non-thermal jet model. The bolometric luminosity of 3C111 is rather low, and the SED model shows rather a BL Lac type than the expected FSRQ. The next source we studied is the nearby FR-I M87. This source has been detected ! in gamma-rays and in the TeV band, but so far not in the hard X-rays (>10 keV). The first part of our analysis was focused on setting an upper limit to the hard X-ray emission of this source, using INTEGRAL IBIS/ISGRI observations. In addition to the standard method we applied several techniques in the analysis process, such as pointing selection and shadowgram treatment, in order to decrease the noise level of the result. Using 5.1 Ms of ISGRI data we determined a 3σ upper limit to the average 20-60 keV flux of f < 3x10^-12 erg/cm^2/s. We have also analysed Suzaku/PIN observations, where we detected M87 for the first time in the hard X-ray band, with a flux of f=1.3x 10^-11 erg/cm^2/s. between 20 and 60 keV. This detection indicates a flare, since the flux is significantly higher than the derived average upper limit. We also analysed Fermi/LAT data and combined this with the X-ray upper limits and historical radio, infrared and optical observations to build a SED. The SED can be modelled as a BL Lac source, which is expected since M87 is a FR-I type. We then also examined the general aspects of gamma-ray bright radio galaxies. Most of these objects are of the FR-I type, and the core of at least one FR-II, 3C 111, is rather BL Lac-like than the expected FSRQ. For the other FR-II sources this might also be the case. The gamma-ray emission originates from the jet, similar as in the case of blazars. Due to the large jet angle, the emission is not observed to be boosted. However, since the gamma-ray emission originates near the black hole, either reflection or a large opening angle can explain the observations. In addition, I contributed to the study of a possible dark matter halo observed with Fermi/LAT in the vicinity of the Virgo cluster. Our work has shown that a population of point sources contributes to this emission. In this thesis, the result of an extended emission analysis and the search for possible counter parts of new sources are presented. ! Finally, the detection of two new X-ray sources using Swift is reported here for the first time. These sources, the BL Lac object BZB J1552+0850 and the Seyfert galaxy LSBC F727-V01, are both located within the 95% error circle of the Fermi/LAT source 2FGL J1551.9+0855. We analysed the X-ray data from the XRT and UV data from the UVOT. The likely counterpart of the Fermi source is rather the blazer BZB J1552+0850, since Seyfert galaxies are rarely gamma-ray emitters. To understand the gamma-ray bright radio galaxies, X-ray observations can be used to can characterise these sources. Using for example the new generation of instruments, such as NuSTAR and ASTRO-H, will help with their superior resolution to distinguish between thermal and non-thermal emission in the X-ray spectrum. Additionally, building SEDs from simultaneous multi-wavelength observations will help constrain the broad-band emission. This will also help to pinpoint the counter part of Fermi/LAT detected sources, which is not trivial due to the large uncertainty in position

Long term monitoring of Gamma-Ray emission from the BL Lacertae object (1ES 2200+420)

NASA Astrophysics Data System (ADS)

Gunawardhana, Isuru; VERITAS Collaboration

2016-03-01

Blazars are a class of Active Galactic Nuclei (AGN) that have relativistic jets pointing along the observer line of sight. Blazars exhibit variable emission extending from radio to TeV energies. The variability timescale of the TeV flux is a key component of understanding the location of the very high energy emission zones. Deep observations of the quiescent state measurements are also required to disentangle the flaring state emission from quiescent state emission, a prerequisite for understanding the origin of blazar spectral variability. BL Lacertae (also known as 1ES 2200+420), as the namesake for all BL Lac objects, is a prime example of one such blazar. The VERITAS Observatory, an Imaging Atmospheric Cherenkov Telescope (IACT) array sensitive to gamma rays in the range from 85 GeV to 30 TeV, dedicates approximately 110 hours per year on deep observations of known gamma-ray blazars. In this talk, I will describe the TeV photon flux variability of BL Lacertae measured by VERITAS from 2013 to 2015.

Olsenella umbonata sp. nov., a microaerotolerant anaerobic lactic acid bacterium from the sheep rumen and pig jejunum, and emended descriptions of Olsenella, Olsenella uli and Olsenella profusa.

PubMed

Kraatz, Mareike; Wallace, R John; Svensson, Liselott

2011-04-01

Strain A2 is an anaerobic, variably Gram-stain-positive, non-spore-forming, small and irregularly rod-shaped bacterium from the ruminal fluid of a sheep that has been described informally as a representative of 'Olsenella (basonym Atopobium) oviles'. Three phenotypically similar bacterial strains (lac15, lac16 and lac31(T)) were isolated in concert with Veillonella magna lac18(T) from the mucosal jejunum of a pig. A phylogenetic analysis based on 16S rRNA gene sequences revealed that strains A2, lac15, lac16 and lac31(T) formed a genetically coherent group (100 % interstrain sequence similarity) within the bigeneric Olsenella-Atopobium branch of the family Coriobacteriaceae, class Actinobacteria. This group was most closely related to the type strains of the two recognized Olsenella species, namely Olsenella uli (sequence similarity of 96.85 %) and Olsenella profusa (sequence similarity of 97.20 %). The sequence similarity to the type strain of Atopobium minutum, the type species of the genus Atopobium, was 92.33 %. Unlike those of O. uli and O. profusa, outgrown colonies of strains A2, lac15, lac16 and lac31(T) were opaque and greyish-white with an umbonate elevation on solid culture media. The four novel strains were characterized as being well-adapted and presumably indigenous to the gastrointestinal tract of homoeothermic vertebrates: they were mesophilic, microaerotolerant, neutrophilic and acidotolerant, bile-resistant, mucin-utilizing and markedly peptidolytic lactic acid bacteria. The results of DNA-DNA hybridizations, cellular fatty acid analysis and other differential phenotypic (physiological and biochemical) tests confirmed that strains A2, lac15, lac16 and lac31(T) represent a novel species of the genus Olsenella. On the basis of the genotypic and phenotypic results, we therefore describe Olsenella umbonata sp. nov., with lac31(T) ( = CCUG 58604(T)  = DSM 22620(T)  = JCM 16156(T)) as the type strain and A2 ( = CCUG 58212  = DSM 22619  = JCM 16157) as an additionally available reference strain. Also, based on our data, we propose emended descriptions of the genus Olsenella and the species Olsenella uli and Olsenella profusa.

A Mouse Model of Acinetobacter baumannii-Associated Pneumonia Using a Clinically Isolated Hypervirulent Strain

PubMed Central

Harris, Greg; Kuo Lee, Rhonda; Lam, Christopher K.; Kanzaki, Gregory; Patel, Girishchandra B.; Xu, H. Howard

2013-01-01

Acinetobacter baumannii is an important emerging pathogen in health care-acquired infections and is responsible for severe nosocomial and community-acquired pneumonia. Currently available mouse models of A. baumannii pneumonia show poor colonization with little to no extrapulmonary dissemination. Here, we describe a mouse model of A. baumannii pneumonia using a clinical isolate (LAC-4 strain) that reliably reproduces the most relevant features of human pulmonary A. baumannii infection and pathology. Using this model, we have shown that LAC-4 infection induced rapid bacterial replication in the lungs, significant extrapulmonary dissemination, and severe bacteremia by 24 h postintranasal inoculation. Infected mice showed severe bronchopneumonia and dilatation and inflammatory cell infiltration in the perivascular space. More significantly, 100% of C57BL/6 and BALB/c mice succumbed to 108 CFU of LAC-4 inoculation within 48 h. When this model was used to assess the efficacy of antimicrobials, all mice treated with imipenem and tigecycline survived a lethal intranasal challenge, with minimal clinical signs and body weight loss. Moreover, intranasal immunization of mice with formalin-fixed LAC-4 protected 40% of mice from a lethal (100× 100% lethal dose) intraperitoneal challenge. Thus, this model offers a reproducible acute course of A. baumannii pneumonia without requiring additional manipulation of host immune status, which will facilitate the development of therapeutic agents and vaccines against A. baumannii pneumonia in humans. PMID:23689726

A-3 scientific results - extragalactic

NASA Technical Reports Server (NTRS)

Schwartz, D. A.

1979-01-01

The results of the HEAO A-3 experiment are summarized. Specific contributions of the experiment to extragalactic astronomy are emphasized. The discovery of relatively condensed X-ray emission in the cores of those clusters of galaxies which are dominated by a giant elliptical or cD galaxy, the discovery of extended X-ray emitting plasma in groups of galaxies, and the demonstration that BL Lac objects are a class of X-ray sources are among the topics discussed.

Studies of the jet in BL Lacertae. I. Recollimation shock and moving emission features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, M. H.; Hovatta, T.; Meier, D. L.

2014-06-01

Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at a position angle of –166.°6 that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical two-dimensional relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock (RCS). Because of this, and the closemore » analogy to the jet feature HST-1 in M87, we identify the standing feature in BL Lac as an RCS. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in which the slowest moving feature is a slow-mode wave, and the fastest feature is a fast-mode wave. In the model, the beam has Lorentz factor Γ{sub beam}{sup gal}≈3.5 in the frame of the host galaxy and the fast mode wave has Lorentz factor Γ{sub Fwave}{sup beam}≈1.6 in the frame of the beam. This gives a maximum apparent speed for the moving features, β{sub app} = v{sub app}/c = 10. In this model the Lorentz factor of the pattern in the galaxy frame is approximately three times larger than that of the beam itself.« less

Transmission of Atherosclerosis Susceptibility with Gut Microbial Transplantation*

PubMed Central

Gregory, Jill C.; Buffa, Jennifer A.; Org, Elin; Wang, Zeneng; Levison, Bruce S.; Zhu, Weifei; Wagner, Matthew A.; Bennett, Brian J.; Li, Lin; DiDonato, Joseph A.; Lusis, Aldons J.; Hazen, Stanley L.

2015-01-01

Recent studies indicate both clinical and mechanistic links between atherosclerotic heart disease and intestinal microbial metabolism of certain dietary nutrients producing trimethylamine N-oxide (TMAO). Here we test the hypothesis that gut microbial transplantation can transmit choline diet-induced TMAO production and atherosclerosis susceptibility. First, a strong association was noted between atherosclerotic plaque and plasma TMAO levels in a mouse diversity panel (n = 22 strains, r = 0.38; p = 0.0001). An atherosclerosis-prone and high TMAO-producing strain, C57BL/6J, and an atherosclerosis-resistant and low TMAO-producing strain, NZW/LacJ, were selected as donors for cecal microbial transplantation into apolipoprotein e null mice in which resident intestinal microbes were first suppressed with antibiotics. Trimethylamine (TMA) and TMAO levels were initially higher in recipients on choline diet that received cecal microbes from C57BL/6J inbred mice; however, durability of choline diet-dependent differences in TMA/TMAO levels was not maintained to the end of the study. Mice receiving C57BL/6J cecal microbes demonstrated choline diet-dependent enhancement in atherosclerotic plaque burden as compared with recipients of NZW/LacJ microbes. Microbial DNA analyses in feces and cecum revealed transplantation of donor microbial community features into recipients with differences in taxa proportions between donor strains that were transmissible to recipients and that tended to show coincident proportions with TMAO levels. Proportions of specific taxa were also identified that correlated with plasma TMAO levels in donors and recipients and with atherosclerotic lesion area in recipients. Atherosclerosis susceptibility may be transmitted via transplantation of gut microbiota. Gut microbes may thus represent a novel therapeutic target for modulating atherosclerosis susceptibility. PMID:25550161

Radio variability in complete samples of extragalactic radio sources at 1.4 GHz

NASA Astrophysics Data System (ADS)

Rys, S.; Machalski, J.

1990-09-01

Complete samples of extragalactic radio sources obtained in 1970-1975 and the sky survey of Condon and Broderick (1983) were used to select sources variable at 1.4 GHz, and to investigate the characteristics of variability in the whole population of sources at this frequency. The radio structures, radio spectral types, and optical identifications of the selected variables are discussed. Only compact flat-spectrum sources vary at 1.4 GHz, and all but four are identified with QSOs, BL Lacs, or other (unconfirmed spectroscopically) stellar objects. No correlation of degree of variability at 1.4 GHz with Galactic latitude or variability at 408 MHz has been found, suggesting that most of the 1.4-GHz variability is intrinsic and not caused by refractive scintillations. Numerical models of the variability have been computed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Jun-Qing; Cuoco, Alessandro; Branchini, Enzo

Building on our previous cross-correlation analysis (Xia et al. 2011) between the isotropic γ-ray background (IGRB) and different tracers of the large-scale structure of the universe, we update our results using 60 months of data from the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi). For this study, we perform a cross-correlation analysis both in configuration and spherical harmonics space between the IGRB and objects that may trace the astrophysical sources of the IGRB: QSOs in the Sloan Digital Sky Survey (SDSS) DR6, the SDSS DR8 Main Galaxy Sample, luminous red galaxies (LRGs) in the SDSS catalog, infrared-selected galaxies in the Two Micron All Sky Survey (2MASS), and radio galaxies in the NRAO VLA Sky Survey (NVSS). The benefit of correlating the Fermi-LAT signal with catalogs of objects at various redshifts is to provide tomographic information on the IGRB, which is crucial in separating the various contributions and clarifying its origin. The main result is that, unlike in our previous analysis, we now observe a significant (>3.5σ) cross-correlation signal on angular scales smaller than 1° in the NVSS, 2MASS, and QSO cases and, at lower statistical significance (~3.0σ), with SDSS galaxies. The signal is stronger in two energy bands, E > 0.5 GeV and E > 1 GeV, but it is also seen at E > 10 GeV. No cross-correlation signal is detected between Fermi data and the LRGs. These results are robust against the choice of the statistical estimator, estimate of errors, map cleaning procedure, and instrumental effects. Finally, we test the hypothesis that the IGRB observed by Fermi-LAT originates from the summed contributions of three types of unresolved extragalactic sources: BL Lacertae objects (BL Lacs), flat spectrum radio quasars (FSRQs), and star-forming galaxies (SFGs). Finally, we find that a model in which the IGRB is mainly produced by SFGs (more » $$72_{-37}^{+23}$$% with 2σ errors), with BL Lacs and FSRQs giving a minor contribution, provides a good fit to the data. We also consider a possible contribution from misaligned active galactic nuclei, and we find that, depending on the details of the model and its uncertainty, they can also provide a substantial contribution, partly degenerate with the SFG one.« less

Spectroscopic monitoring of the BL Lac object AO 0235+164

NASA Astrophysics Data System (ADS)

Raiteri, C. M.; Villata, M.; Capetti, A.; Heidt, J.; Arnaboldi, M.; Magazzù, A.

2007-03-01

Aims:Spectroscopic monitoring of BL Lac objects is a difficult task that nonetheless can provide important information on the different components of the active galactic nucleus. Methods: We performed optical spectroscopic monitoring of the BL Lac object AO 0235+164 (z=0.94) with the VLT and TNG telescopes from Aug. 2003 to Dec. 2004, during an extended WEBT campaign. The flux of this source is both contaminated and absorbed by a foreground galactic system at z=0.524, the stars of which can act as gravitational micro-lenses. Results: In this period the object was in an optically faint, though variable state, and a broad Mg II emission line was visible at all epochs. The spectroscopic analysis reveals an overall variation in the Mg II line flux of a factor 1.9, while the corresponding continuum flux density changed by a factor 4.3. Most likely, the photoionising radiation can be identified with the emission component that was earlier recognised to be present as a UV-soft-X-ray bump in the source spectral energy distribution and that is visible in the optical domain only in very faint optical states. We estimate an upper limit to the broad line region (BLR) size of a few light months from the historical minimum brightness level; from this we infer the maximum amplification of the Mg II line predicted by the microlensing scenario. Conclusions: .Unless we have strongly overestimated the size of the BLR, only very massive stars could significantly magnify the broad Mg II emission line, but the time scale of variations due to these (rare) events would be of several years. In contrast, the continuum flux, coming from much smaller emission regions in the jet, could be affected by microlensing from the more plausible MACHO deflectors, with variability time scales of the order of some months. Based on observations collected at the European Southern Observatory, Chile (ESO Programme 71.A-0174), and on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Systematic Analysis of the Pleurotus ostreatus Laccase Gene (PoLac) Family and Functional Characterization of PoLac2 Involved in the Degradation of Cotton-Straw Lignin.

PubMed

Jiao, Xiaoyu; Li, Guoqing; Wang, Yan; Nie, Fan; Cheng, Xi; Abdullah, Muhammad; Lin, Yi; Cai, Yongping

2018-04-11

Fungal laccases play important roles in the degradation of lignocellulose. Although some PoLac s have been reported in several studies, still no comprehensive bioinformatics study of the LAC family in Pleurotus ostreatus has been reported. In this study, we identified 12 laccase genes in the whole genome sequence of P. ostreatus and their physical characteristics, gene distribution, phylogenic relationships, gene structure, conserved motifs, and cis-elements were also analyzed. The expression patterns of 12 PoLac genes at different developmental stages and under different culture substrates were also analyzed. The results revealed that PoLac2 and PoLac12 may be involved in the degradation of lignin and the formation of the fruiting body, respectively. Subsequently, we overexpressed PoLac2 in P. ostreatus by the Agrobacterium tumefaciens -mediated transformation (ATMT) method. The transformants' laccase activity increased in varying degrees, and the gene expression level of PoLac2 in transformants was 2-8 times higher than that of the wild-type strain. Furthermore, the lignin degradation rate by transgenic fungus over 30 days was 2.36-6.3% higher than that of wild-type. Our data show that overexpression of PoLac2 significantly enhanced the lignin degradation of cotton-straw. To our knowledge, this study is the first report to demonstrate the functions of PoLac2 in P. ostreatus .

Comparison Of Optical, UV, X-ray, And Gamma-ray Variations Of Selected Blazars In 2011

NASA Astrophysics Data System (ADS)

Consiglio, Santina; Marscher, A. P.; Jorstad, S. G.; Walker, G.

2012-01-01

We present multi-wavelength observations of several gamma-ray bright blazars. We combine optical data obtained at Maria Mitchell Observatory on Nantucket Island with space- and ground-based observations carried out with a variety of instruments. These include a number of other optical telescopes, the Fermi Gamma-ray Space Telescope at photon energies of 0.1-200 GeV, the Rossi X-Ray Timing Explorer at 2.4-10 keV, and the Swift satellite at 0.3-10 keV plus optical and UV wavelengths. Three of the observed blazars proved to be particularly active - BL Lac, 3C 279, and PKS 1510-089. BL Lac was of special interest, varying greatly in optical brightness from night to night. In addition, as reported by the VERITAS group, it exhibited a remarkable, short-lived flare at TeV gamma-ray energies on one of the nights. We cross-correlate the variations in the different wavebands in an effort to guide theoretical interpretations of the optical and high-energy emission from blazars. This project was supported by NSF/REU grant AST-0851892 and by the Nantucket Maria Mitchell Association. The research at Boston University was supported in part by NSF grants AST-0907893, and by NASA through Fermi grants NNX08AV65G and NNX11AQ03G.

SIMULTANEOUS B'V'R' MONITORING OF BL LACERTAE OBJECT S5 0716+714 AND DETECTION OF INTER-BAND TIME DELAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Jianghua; He Xiangtao; Boettcher, Markus

We present the results of our optical monitoring of the BL Lac object S5 0716+714 over seven nights in 2006 December. The monitoring was carried out simultaneously at three optical wavelengths with a novel photometric system. The object did not show large-amplitude internight variations during this period. Intranight variations were observed on four nights and probably on one more. Strong bluer-when-brighter chromatism was detected on both intranight and internight timescales. The intranight variation amplitude decreases in the wavelength sequence of B', R', and V'. Cross-correlation analyses revealed that the variability at the B' and V' bands leads that at themore » R' band by about 30 minutes on one night.« less

Recombinant levels of Escherichia coli K-12 mutants deficient in various replication, recombination, or repair genes.

PubMed Central

Zieg, J; Maples, V F; Kushner, S R

1978-01-01

Escherichia coli strains containing mutations in lexA, rep, uvrA, uvrD, uvrE, lig, polA, dam, or xthA were constructed and tested for conjugation and transduction proficiencies and ability to form Lac+ recombinants in an assay system utilizing a nontandem duplication of two partially deleted lactose operons (lacMS286phi80dIIlacBK1). lexA and rep mutants were as deficient (20% of wild type) as recB and recC strains in their ability to produce Lac+ progeny. All the other strains exhibited increased frequencies of Lac+ recombinant formation, compared with wild type, ranging from 2- to 13-fold. Some strains showed markedly increased conjugation proficiency (dam uvrD) compared to wild type, while others appeared deficient (polA107). Some differences in transduction proficiency were also observed. Analysis of the Lac+ recombinants formed by the various mutants indicated that they were identical to the recombinants formed by a wild-type strain. The results indicate that genetic recombination in E. coli is a highly regulated process involving multiple gene products. PMID:350859

The Origin of Mutants Under Selection: How Natural Selection Mimics Mutagenesis (Adaptive Mutation)

PubMed Central

Maisnier-Patin, Sophie; Roth, John R.

2015-01-01

Selection detects mutants but does not cause mutations. Contrary to this dictum, Cairns and Foster plated a leaky lac mutant of Escherichia coli on lactose medium and saw revertant (Lac+) colonies accumulate with time above a nongrowing lawn. This result suggested that bacteria might mutagenize their own genome when growth is blocked. However, this conclusion is suspect in the light of recent evidence that revertant colonies are initiated by preexisting cells with multiple copies the conjugative F′lac plasmid, which carries the lac mutation. Some plated cells have multiple copies of the simple F′lac plasmid. This provides sufficient LacZ activity to support plasmid replication but not cell division. In nongrowing cells, repeated plasmid replication increases the likelihood of a reversion event. Reversion to lac+ triggers exponential cell growth leading to a stable Lac+ revertant colony. In 10% of these plated cells, the high-copy plasmid includes an internal tandem lac duplication, which provides even more LacZ activity—sufficient to support slow growth and formation of an unstable Lac+ colony. Cells with multiple copies of the F′lac plasmid have an increased mutation rate, because the plasmid encodes the error-prone (mutagenic) DNA polymerase, DinB. Without DinB, unstable and stable Lac+ revertant types form in equal numbers and both types arise with no mutagenesis. Amplification and selection are central to behavior of the Cairns–Foster system, whereas mutagenesis is a system-specific side effect or artifact caused by coamplification of dinB with lac. Study of this system has revealed several broadly applicable principles. In all populations, gene duplications are frequent stable genetic polymorphisms, common near-neutral mutant alleles can gain a positive phenotype when amplified under selection, and natural selection can operate without cell division when variability is generated by overreplication of local genome subregions. PMID:26134316

The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data.

PubMed

Fan; Strauss; Gunn; Lupton; Carilli; Rupen; Schmidt; Moustakas; Davis; Annis; Bahcall; Brinkmann; Brunner; Csabai; Doi; Fukugita; Heckman; Hennessy; Hindsley; Ivezic; Knapp; Lamb; Munn; Pauls; Pier; Rockosi; Schneider; Szalay; Tucker; York

1999-12-01

We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

A Search for Short Timescale Microvariability in Active Galactic Nuclei in the Ultraviolet

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.; Clark, L. Lee

2003-01-01

We observed four AGNs (the type-1 Seyfert systems 3C249.1, NGC 6814 and Mrk 205, and the BL Lac object 3C371) using the High Speed Photometer on the Hubble Space Telescope to search for short timescale microvariability in the W. Continuous observations of 3 0 0 0 s duration were obtained for each system on several consecutive HST orbits using a 1 s sample time in a 1400 - 3000 2 bandpass. variability > 0.3 % (0 . 003 mag) was detected in any AGN on timescales shorter than 1500 s. The distribution of photon arrival times observed from each source was consistent with Poisson statistics. Because of HST optical problems, the limit on photometric variability at longer timescales is less precise. These results restrict models of supermassive black holes as the central engine of an AGN and the diskoseismology oscillations of any accretion disk around such a black hole.

VizieR Online Data Catalog: Blazars in the Swift-BAT hard X-ray sky (Maselli+, 2010)

NASA Astrophysics Data System (ADS)

Maselli, A.; Cusumano, G.; Massaro, E.; La Parola, V.; Segreto, A.; Sbarufatti, B.

2010-06-01

We reported the list of hard X-ray blazars obtained adopting sigma=3 as detection threshold: with this choice a number of three spurious sources over a total of 121 blazars is expected. Each blazar is identified by a three-letter code, where the first two are BZ for blazar and the third one specifies the type, followed by the truncated equatorial coordinates (J2000). The codes are defined in the "Note (1)" below. We obtained 69 FSRQs, 24 BL Lac objects and 28 blazars of uncertain classification, representing 4.4%, 2.4% and 11.0% of the corresponding populations classified in the BZCAT, respectively. This sample has been compared with other lists and catalogues found in literature (Tueller et al., 2010, Cat. J/ApJS/186/378, Ajello et al. 2009ApJ...699..603A, Cusumano et al., 2010, Cat. J/A+A/510/A48). (1 data file).

Milagro Observations of Potential TeV Emitters

NASA Astrophysics Data System (ADS)

Abeysekara, Anushka; Linnemann, James

2012-03-01

We searched for point sources in Milagro sky maps at the locations in four catalogs of potential TeV emitting sources. Our candidates are selected from the Fermi 2FGL pulsars, Fermi 2FGL extragalactic sources, TeVCat extragalactic sources, and from the BL Lac TeV Candidate list published by Costamante and Ghisellini in 2002. The False Discovery Rate (FDR) statistical procedure is used to select the sources. The FDR procedure controls the fraction of false detections. Our results are presented in this talk.

MAGIC discovers VHE gamma-ray emission from the blazar 1ES 1727+502

NASA Astrophysics Data System (ADS)

Mariotti, Mose

2011-11-01

The MAGIC Collaboration reports the discovery of Very High Energy (VHE; E>100 GeV) gamma-ray emission from the BL Lac object 1ES 1727+502 (also known as OT546) with redshift z=0.055. The source was selected from the compilation of Costamante, L. & Ghisellini, G. 2002, A&A, 384, 56. Previous observations with the single MAGIC-I telescope yielded an upper limit on the level of 11.8% of the Crab Nebula flux above 140 GeV (J.

GSFC Contributions to the NATO X-ray Astronomy Institute, Erice, July 1979. [X-ray spectra of supernova remants, galactic X-ray sources, active galactic nuclei, and clusters of galaxies

NASA Technical Reports Server (NTRS)

Holt, S. S.; Mushotzky, R. F.

1979-01-01

An overview of X-ray astronomical spectroscopy in general is presented and results obtained by HEAO 1 and 2 as well as earlier spacecraft are examined. Particular emphasis is given to the spectra of supernova remnants; galactic binary X-ray sources, cataclysmic variables, bulges, pulsars, and stars; the active nuclei of Seyfert 1 galaxy, BL Lac, and quasars; the diffuse X-ray background; and galactic clusters.

Extent of warm haloes around medium-redshift galaxies

NASA Technical Reports Server (NTRS)

Burbidge, E. M.; Barlow, T. A.; Cohen, R. D.; Junkkarinen, V. T.; Womble, D. S.

1989-01-01

The properties of low-to-medium ionization gaseous haloes around galaxies are briefly reviewed. New observations concerning such haloes are presented. For the galaxy-QSO pair in the field of the radio source 3C303, the higher-redshift QSO has been found to show Mg II absorption at the lower redshift of the faint nearby galaxy. Secondly, new data are presented on one of the galaxies in the environment of the well-known BL Lac object AO 0235 + 164.

VizieR Online Data Catalog: SDSS optically selected BL Lac candidates (Kuegler+, 2014)

NASA Astrophysics Data System (ADS)

Kuegler, S. D.; Nilsson, K.; Heidt, J.; Esser, J.; Schultz, T.

2014-11-01

The data that we use for variability and host galaxy analysis were presented in Paper I (Heidt & Nilsson, 2011A&A...529A.162H, Cat. J/A+A/529/A162). Alltogether, 123 targets were observed at the ESO New Technology Telescope (NTT) on La Silla, Chile during Oct. 2-6, 2008 and Mar. 28-Apr. 1, 2009. The observations were made with the EFOSC2 instrument through a Gunn-r filter (#786). (2 data files).

Group II metabotropic glutamate receptor type 2 allosteric potentiators prevent sodium lactate-induced panic-like response in panic-vulnerable rats

PubMed Central

Johnson, Philip L; Fitz, Stephanie D; Engleman, Eric A; Svensson, Kjell A; Schkeryantz, Jeffrey M; Shekhar, Anantha

2015-01-01

Rats with chronic inhibition of GABA synthesis by infusion of l-allyglycine, a glutamic acid decarboxylase inhibitor, into their dorsomedial/perifornical hypothalamus are anxious and exhibit panic-like cardio-respiratory responses to treatment with intravenous (i.v.) sodium lactate (NaLac) infusions, in a manner similar to what occurs in patients with panic disorder. We previously showed that either NMDA receptor antagonists or metabotropic glutamate receptor type 2/3 receptor agonists can block such a NaLac response, suggesting that a glutamate mechanism is contributing to this panic-like state. Using this animal model of panic, we tested the efficacy of CBiPES and THIIC, which are selective group II metabotropic glutamate type 2 receptor allosteric potentiators (at 10–30mg/kg i.p.), in preventing NaLac-induced panic-like behavioral and cardiovascular responses. The positive control was alprazolam (3mg/kg i.p.), a clinically effective anti-panic benzodiazepine. As predicted, panic-prone rats given a NaLac challenge displayed NaLac-induced panic-like cardiovascular (i.e. tachycardia and hypertensive) responses and “anxiety” (i.e. decreased social interaction time) and “flight” (i.e. increased locomotion) -associated behaviors; however, systemic injection of the panic-prone rats with CBiPES, THIIC or alprazolam prior to the NaLac dose blocked all NaLac-induced panic-like behaviors and cardiovascular responses. These data suggested that in a rat animal model, selective group II metabotropic glutamate type 2 receptor allosteric potentiators show an anti-panic efficacy similar to alprazolam. PMID:22914798

Regulation of lac Operon Expression: Reappraisal of the Theory of Catabolite Repression

PubMed Central

Wanner, Barry L.; Kodaira, Ryoji; Neidhardt, Frederick C.

1978-01-01

The physiological state of Escherichia coli with respect to (permanent) catabolite repression was assessed by measuring the steady-state level of β-galactosidase in induced or in constitutive cells under a variety of growth conditions. Four results were obtained. (i) Catabolite repression had a major effect on fully induced or constitutive expression of the lac gene, and the magnitude of this effect was found to be dependent on the promoter structure; cells with a wild-type lac promoter showed an 18-fold variation in lac expression, and cells with the lacP37 (formerly lac-L37) promoter exhibited several hundred-fold variation. (ii) Exogenous adenosine cyclic 3′,5′-monophosphoric acid (cAMP) could not abolish catabolite repression, even though several controls demonstrated that cAMP was entering the cells in significant amounts. (Rapid intracellular degradation of cAMP could not be ruled out.) (iii) Neither the growth rate nor the presence of biosynthetic products altered the degree of catabolite repression; all variation could be related to the catabolites present in the growth medium. (iv) Slowing by imposing an amino acid restriction decreased the differential rate of β-galactosidase synthesis from the wild-type lac promoter when bacteria were cultured in either the absence or presence of cAMP; this decreased lac expression also occurred when the bacteria harbored the catabolite-insensitive lacP5 (formerly lacUV5) promoter mutation. These findings support the idea that (permanent) catabolite repression is set by the catabolites in the growth medium and may not be related to an imbalance between catabolism and anabolism. PMID:214424

The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?

NASA Astrophysics Data System (ADS)

Balmaverde, B.; Capetti, A.

2006-02-01

This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. We selected two samples with 5 GHz VLA radio flux measurements down to 1 mJy, reaching levels of radio luminosity as low as 1036 erg s-1. In Paper I we presented a study of the surface brightness profiles for the 65 objects with available archival HST images out of the 116 radio-detected galaxies. We classified early-type galaxies into "core" and "power-law" galaxies, discriminating on the basis of the slope of their nuclear brightness profiles, following the Nukers scheme. Here we focus on the 29 core galaxies (hereafter CoreG). We used HST and Chandra data to isolate their optical and X-ray nuclear emission. The CoreG invariably host radio-loud nuclei, with an average radio-loudness parameter of Log R = L5 {GHz} / LB ˜ 3.6. The optical and X-ray nuclear luminosities correlate with the radio-core power, smoothly extending the analogous correlations already found for low luminosity radio-galaxies (LLRG) toward even lower power, by a factor of ˜ 1000, covering a combined range of 6 orders of magnitude. This supports the interpretation of a common non-thermal origin of the nuclear emission also for CoreG. The luminosities of the nuclear sources, most likely dominated by jet emission, set firm upper limits, as low as L/L_Edd ˜ 10-9 in both the optical and X-ray band, on any emission from the accretion process. The similarity of CoreG and LLRG when considering the distributions host galaxies luminosities and black hole masses, as well as of the surface brightness profiles, indicates that they are drawn from the same population of early-type galaxies. LLRG represent only the tip of the iceberg associated with (relatively) high activity levels, with CoreG forming the bulk of the population. We do not find any relationship between radio-power and black hole mass. A minimum black hole mass of M_BH = 108 M⊙ is apparently associated with the radio-loud nuclei in both CoreG and LLRG, but this effect must be tested on a sample of less luminous galaxies, likely to host smaller black holes. In the unifying model for BL Lacs and radio-galaxies, CoreG likely represent the counterparts of the large population of low luminosity BL Lac now emerging from the surveys at low radio flux limits. This suggests the presence of relativistic jets also in these quasi-quiescent early-type "core" galaxies.

High-frequency predictions for number counts and spectral properties of extragalactic radio sources. New evidence of a break at mm wavelengths in spectra of bright blazar sources

NASA Astrophysics Data System (ADS)

Tucci, M.; Toffolatti, L.; de Zotti, G.; Martínez-González, E.

2011-09-01

We present models to predict high-frequency counts of extragalactic radio sources using physically grounded recipes to describe the complex spectral behaviour of blazars that dominate the mm-wave counts at bright flux densities. We show that simple power-law spectra are ruled out by high-frequency (ν ≥ 100 GHz) data. These data also strongly constrain models featuring the spectral breaks predicted by classical physical models for the synchrotron emission produced in jets of blazars. A model dealing with blazars as a single population is, at best, only marginally consistent with data coming from current surveys at high radio frequencies. Our most successful model assumes different distributions of break frequencies, νM, for BL Lacs and flat-spectrum radio quasars (FSRQs). The former objects have substantially higher values of νM, implying that the synchrotron emission comes from more compact regions; therefore, a substantial increase of the BL Lac fraction at high radio frequencies and at bright flux densities is predicted. Remarkably, our best model is able to give a very good fit to all the observed data on number counts and on distributions of spectral indices of extragalactic radio sources at frequencies above 5 and up to 220 GHz. Predictions for the forthcoming sub-mm blazar counts from Planck, at the highest HFI frequencies, and from Herschel surveys are also presented. Appendices are available in electronic form at http://www.aanda.org

Radio and γ -Ray Variability in the BL Lac PKS 0219−164: Detection of Quasi-periodic Oscillations in the Radio Light Curve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatta, Gopal, E-mail: gopalbhatta716@gmail.com; Mt. Suhora Observatory, Pedagogical University, ul. Podchorazych 2, 30-084 Kraków

In this work, we explore the long-term variability properties of the blazar PKS 0219−164 in the radio and the γ -ray regime, utilizing the OVRO 15 GHz and the Fermi /LAT observations from the period 2008–2017. We found that γ -ray emission is more variable than the radio emission implying that γ -ray emission possibly originated in more compact regions while the radio emission represented continuum emission from the large-scale jets. Also, in the γ -ray, the source exhibited spectral variability, characterized by the softer-when-brighter trend, a less frequently observed feature in the high-energy emission by BL Lacs. In radio,more » using Lomb–Scargle periodogram and weighted wavelet z -transform, we detected a strong signal of quasi-periodic oscillation (QPO) with a periodicity of 270 ± 26 days with possible harmonics of 550 ± 42 and 1150 ± 157 day periods. At a time when detections of QPOs in blazars are still under debate, the observed QPO with high statistical significance (∼97%–99% global significance over underlying red-noise processes) and persistent over nearly 10 oscillations could make one of the strongest cases for the detection of QPOs in blazar light curves. We discuss various blazar models that might lead to the γ -ray and radio variability, QPO, and the achromatic behavior seen in the high-energy emission from the source.« less

ERRATIC FLARING OF BL LAC IN 2012–2013: MULTIWAVELENGTH OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehrle, Ann E.; Grupe, Dirk; Jorstad, Svetlana G.

2016-01-10

BL 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 inversemore » 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.« less

Two modes of control of pilA, the gene encoding type 1 pilin in Escherichia coli.

PubMed Central

Orndorff, P E; Spears, P A; Schauer, D; Falkow, S

1985-01-01

Type 1 piliation in Escherichia coli is subject to metastable regulation at the transcriptional level (B. I. Eisenstein, Science 214:337-339, 1981). However, the genes controlling in this fashion are not known. We present evidence that the pilA gene, encoding the structural subunit of type 1 pili, is subject to metastable transcriptional regulation. A pilA'-lacZ fusion, constructed in vitro on a recombinant plasmid, was used in conjunction with a recBC sbcB mutant of E. coli K-12 to introduce the fusion into the chromosomal region encoding Pil. This fusion was found to be subject to metastable transcriptional control. The rate of switching from the Lac+ to the Lac- phenotype was 4 X 10(-4) per cell per generation and 6.2 X 10(-4) in the opposite direction. A ca. 10-fold difference in beta-galactosidase activity was observed between phenotypically "ON" (Lac+) and "OFF" (Lac-) populations. P1 transduction experiments showed that the element determining the ON or OFF phenotype was tightly linked to pilA. In addition to the metastable regulation of pilA, a second type of transcriptional regulation was effected by the product of a gene, hyp, adjacent to pilA. By using a recombinant plasmid containing just a pilA'-lacZ fusion and the putative pilA promoter, we found that a lesion in hyp conferred a beta-galactosidase activity about fivefold higher than that of a strain possessing the parental hyp gene. Mutants constructed to have a pilA'-lacZ fusion and a hyp::Tn5-132 mutation in the chromosome exhibited a frequency of switching from Lac+ to Lac- and vice versa indistinguishable from that of the parental strain. However, in the ON mode, hyp::Tn5-132 mutants showed a twofold-higher beta-galactosidase activity. Thus, hyp does not appear to affect metastable variation but does affect the level of transcription of the pilA gene in the ON (transcribed) mode. Images PMID:3930469

agr-Dependent Interactions of Staphylococcus aureus USA300 with Human Polymorphonuclear Neutrophils

PubMed Central

Pang, Yun Yun; Schwartz, Jamie; Thoendel, Matthew; Ackermann, Laynez W.; Horswill, Alexander R.; Nauseef, William M.

2010-01-01

The emergence of serious infections due to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has fueled interest in the contributions of specific staphylococcal virulence factors to clinical disease. To assess the contributions of agr-dependent factors to the fate of organisms in polymorphonuclear neutrophils (PMN), we examined the consequences for organism and host cells of feeding PMN with wild-type CA-MRSA (LAC) or CA-MRSA (LAC agr KO) at different multiplicities of infection (MOIs). Phagocytosed organisms rapidly increased the transcription of RNAIII in a time- and MOI-dependent fashion; extracellular USA300 (LAC) did not increase RNAIII expression despite having the capacity to respond to autoinducing peptide-enriched culture medium. HOCl-mediated damage and intracellular survival were the same in the wild-type and USA300 (LAC agr KO). PMN lysis by ingested USA300 (LAC) was time- and MOI-dependent and, at MOIs >1, required α-hemolysin (hla) as USA300 (LAC agr KO) and USA300 (LAC hla KO) promoted PMN lysis only at high MOIs. Taken together, these data demonstrate activation of the agr operon in human PMN with the subsequent production of α-hemolysin and PMN lysis. The extent to which these events in the phagosomes of human PMN contribute to the increased morbidity and mortality of infections with USA300 (LAC) merits further study. PMID:20829608

TOMOGRAPHY OF THE FERMI-LAT γ-RAY DIFFUSE EXTRAGALACTIC SIGNAL VIA CROSS CORRELATIONS WITH GALAXY CATALOGS

DOE PAGES

Xia, Jun-Qing; Cuoco, Alessandro; Branchini, Enzo; ...

2015-03-24

Building on our previous cross-correlation analysis (Xia et al. 2011) between the isotropic γ-ray background (IGRB) and different tracers of the large-scale structure of the universe, we update our results using 60 months of data from the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi). For this study, we perform a cross-correlation analysis both in configuration and spherical harmonics space between the IGRB and objects that may trace the astrophysical sources of the IGRB: QSOs in the Sloan Digital Sky Survey (SDSS) DR6, the SDSS DR8 Main Galaxy Sample, luminous red galaxies (LRGs) in the SDSS catalog, infrared-selected galaxies in the Two Micron All Sky Survey (2MASS), and radio galaxies in the NRAO VLA Sky Survey (NVSS). The benefit of correlating the Fermi-LAT signal with catalogs of objects at various redshifts is to provide tomographic information on the IGRB, which is crucial in separating the various contributions and clarifying its origin. The main result is that, unlike in our previous analysis, we now observe a significant (>3.5σ) cross-correlation signal on angular scales smaller than 1° in the NVSS, 2MASS, and QSO cases and, at lower statistical significance (~3.0σ), with SDSS galaxies. The signal is stronger in two energy bands, E > 0.5 GeV and E > 1 GeV, but it is also seen at E > 10 GeV. No cross-correlation signal is detected between Fermi data and the LRGs. These results are robust against the choice of the statistical estimator, estimate of errors, map cleaning procedure, and instrumental effects. Finally, we test the hypothesis that the IGRB observed by Fermi-LAT originates from the summed contributions of three types of unresolved extragalactic sources: BL Lacertae objects (BL Lacs), flat spectrum radio quasars (FSRQs), and star-forming galaxies (SFGs). Finally, we find that a model in which the IGRB is mainly produced by SFGs (more » $$72_{-37}^{+23}$$% with 2σ errors), with BL Lacs and FSRQs giving a minor contribution, provides a good fit to the data. We also consider a possible contribution from misaligned active galactic nuclei, and we find that, depending on the details of the model and its uncertainty, they can also provide a substantial contribution, partly degenerate with the SFG one.« less

Fermi LAT detection of renewed GeV flaring activity from PKS 0426-380

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2012-12-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the BL Lac object PKS 0426-380 (also known as 2FGL J0428.6-3756, Nolan et al. 2012, ApJS, 199, 31, and RX J0428.6-3756) with radio coordinates R.A.: 67.16843 deg, Dec: -37.93877 deg, J2000 (Johnston et al. 1995, AJ, 110, 880) and redshift z=1.111 (Heidt et al....

Voids as alternatives to dark energy and the propagation of γ rays through the universe.

PubMed

DeLavallaz, Arnaud; Fairbairn, Malcolm

2012-04-27

We test the opacity of a void universe to TeV energy γ rays having obtained the extragalactic background light in that universe using a simple model and the observed constraints on the star formation rate history. We find that the void universe has significantly more opacity than a Λ cold dark matter universe, putting it at odds with observations of BL-Lac objects. We argue that while this method of distinguishing between the two cosmologies contains uncertainties, it circumvents any debates over fine-tuning.

Observations of blazars with ASCA

NASA Technical Reports Server (NTRS)

Makino, F.; Edelson, R.; Fujimoto, R.; Kii, T.; Idesawa, E.; Makishima, K.; Takahashi, T.; Sasaki, K.; Kamae, T.; Kubo, H.;

The Effect of Blazar Spectral Breaks on the Blazar Contribution to the Extragalactic Gamma-Ray Background

NASA Technical Reports Server (NTRS)

Venters, Tonia M.; Pavlidou, Vasiliki

2011-01-01

The spectral shapes of the contributions of different classes of unresolved gamma-ray emitters can provide insight into their relative contributions to the extragalactic gamma-ray background (EGB) and the natures of their spectra at GeV energies, We calculate the spectral shapes of the contributions to the EGB arising from BL Lacertae type objects (BL Lacs) and flat-spectrum radio quasars (FSRQs) assuming blazar spectra can be described as broken power laws, We fit the resulting total blazar spectral shape to the Fermi Large Area Telescope measurements of the EGB, finding that the best-fit shape reproduces well the shape of the Fermi EGB for various break scenarios. We conclude that a scenario in which the contribution of blazars is dominant cannot be excluded on spectral grounds alone, even if spectral breaks are shown to be common among Fermi blazars. We also find that while the observation of a featureless (within uncertainties) power-law EGB spectrum by Fermi does not necessarily imply a single class of contributing unresolved sources with featureless individual spectra, such an observation and the collective spectra of the separate contributing populations determine the ratios of their contributions. As such, a comparison with studies including blazar gamma-ray luminosity functions could have profound implications for the blazar contribution to the EGB, blazar evolution, and blazar gamma-ray spectra and emission.

Measuring persistent temporomandibular joint nociception in rats and two mice strains.

PubMed

Kramer, Phillip R; Kerins, Carolyn A; Schneiderman, Emet; Bellinger, Larry L

2010-04-19

Temporomandibular joint (TMJ) pain has been reported to last for prolonged periods in humans. In rodents a variety of methods have been used to measure TMJ nociception, but for most of these methods the period of measurement has been minutes to a couple of hours. In addition, most measurement protocols required restraint or training of the animal. Previous studies from our laboratory demonstrated that feeding behavior, particularly meal duration, was an indicator of TMJ nociception in unrestrained and untrained male and female Sprague-Dawley rats for up to two days. In this study, we first found that injection of complete Freund's adjuvant (CFA) into the TMJ of rats significantly lengthened meal duration for 19 days and also decreased meal frequency for 42 days. Interestingly, the meal duration varied significantly from day to day within the 19 day period. TMJ interleukin-1 beta (IL-1 beta) and calcitonin gene-related peptide (CGRP) were significantly elevated in the TMJ tissues of CFA-injected animals and the level of these markers was attenuated as the meal duration decreased with time. Control animals injected with saline into the TMJ or CFA into the knee did not show a significant lengthening in meal duration but did show a decrease in meal frequency. In a second study, DBA/1LacJ mice given TMJ CFA injections showed a significantly lengthened meal duration on four of the seven days measured using end-of-the meal definition of 5 or 10 min. No other meal pattern changed significantly. Two days post-CFA injection, the DBA/1LacJ mice showed significantly elevated interleukin-6 (IL-6), but not elevated IL-1 beta. Seven days post-injection, both IL-6 and IL-1 beta were significantly elevated. No change in CGRP was detected. In this study C57Bl/6 mice also received TMJ CFA injections, but they did not show a lengthening in any meal pattern or significant increases in IL-1 beta, IL-6 or CGRP. Our data show, for the first time, that meal duration can be used to measure CFA-induced nociception in the TMJ over the course of several weeks in unrestrained rats and for up to seven days in the DBA/1LacJ mouse strain. In addition, C57Bl/6 mice are resistant to CFA-induced TMJ nociception at the same dose used in the DBA/1LacJ mice. (c) 2010 Elsevier Inc. All rights reserved.

Modeling the Lac repressor-operator assembly: The influence of DNA looping on Lac repressor conformation

PubMed Central

Swigon, David; Coleman, Bernard D.; Olson, Wilma K.

2006-01-01

Repression of transcription of the Escherichia coli Lac operon by the Lac repressor (LacR) is accompanied by the simultaneous binding of LacR to two operators and the formation of a DNA loop. A recently developed theory of sequence-dependent DNA elasticity enables one to relate the fine structure of the LacR–DNA complex to a wide range of heretofore-unconnected experimental observations. Here, that theory is used to calculate the configuration and free energy of the DNA loop as a function of its length and base-pair sequence, its linking number, and the end conditions imposed by the LacR tetramer. The tetramer can assume two types of conformations. Whereas a rigid V-shaped structure is observed in the crystal, EM images show extended forms in which two dimer subunits are flexibly joined. Upon comparing our computed loop configurations with published experimental observations of permanganate sensitivities, DNase I cutting patterns, and loop stabilities, we conclude that linear DNA segments of short-to-medium chain length (50–180 bp) give rise to loops with the extended form of LacR and that loops formed within negatively supercoiled plasmids induce the V-shaped structure. PMID:16785444

Jet Precession Driven by a Supermassive Black Hole Binary System in the BL Lac Object PG 1553+113

NASA Astrophysics Data System (ADS)

Caproni, Anderson; Abraham, Zulema; Motter, Juliana Cristina; Monteiro, Hektor

2017-12-01

The recent discovery of a roughly simultaneous periodic variability in the light curves of the BL Lac object PG 1553+113 at several electromagnetic bands represents the first case of such odd behavior reported in the literature. Motivated by this, we analyzed 15 GHz interferometric maps of the parsec-scale radio jet of PG 1553+113 to verify the presence of a possible counterpart of this periodic variability. We used the Cross-entropy statistical technique to obtain the structural parameters of the Gaussian components present in the radio maps of this source. We kinematically identified seven jet components formed coincidentally with flare-like features seen in the γ-ray light curve. From the derived jet component positions in the sky plane and their kinematics (ejection epochs, proper motions, and sky position angles), we modeled their temporal changes in terms of a relativistic jet that is steadily precessing in time. Our results indicate a precession period in the observer’s reference frame of 2.24 ± 0.03 years, compatible with the periodicity detected in the light curves of PG 1553+113. However, the maxima of the jet Doppler boosting factor are systematically delayed relative to the peaks of the main γ-ray flares. We propose two scenarios that could explain this delay, both based on the existence of a supermassive black hole binary system in PG 1553+113. We estimated the characteristics of this putative binary system that also would be responsible for driving the inferred jet precession.

Long-term spectral and temporal behavior of the high-frequency peaked BL LAC object 1ES 1959+650

NASA Astrophysics Data System (ADS)

Backes, M.; Uellenbeck, M.; Hayashida, M.; Satalecka, K.; Tescaro, D.; Terzić, T.; MAGIC Collaboration; Fuhrmann, L.; Nestoras, I.; F-GAMMA project; Lähteenmäki, A.; Tornikoski, M.; Nieppola, E.; Metsähovi; Böttcher, M.; Collmar, W.; Weidinger, M.

2012-12-01

The high-frequency peaked BL Lac object 1ES 1959+650 is well-known for an exceptional outburst, which was observed at very high energy (VHE) γ-rays by the Whipple 10m and HEGRA telescopes in 2002. Remarkably, this outburst lacked associated X-ray emission (a socalled "orphan flare") and by this cannot easily be described by standard Synchrotron Self Compton (SSC) models. Models based on hadronic emission processes have also been proposed to explain the observed behavior. Subsequent multi-wavelength observations during a low flux state at TeV energies in 2006 can, instead, be explained by a standard single-zone SSC model. In this context, 1ES 1959+650 has been regularly monitored by the MAGIC telescope since 2005. During these years, no significant variation in the VHE γ-ray flux has been observed. The low energy part of this is in very good agreement with the high-energy part of the time-integrated energy spectrum as measured by Fermi-LAT. Based on this constant flux level in VHE γ-rays, we assembled the time-integrated spectral energy distribution (SED) of 1ES 1959+650 from radio to VHE γ-rays. Despite the non-variability at very high energies, significant flux and spectral variations have been observed at optical and X-ray frequencies in the meanwhile. Furthermore, the shape of the SED at high energy γ-rays as measured by Fermi-LAT is essentially flat which cannot be explained by either conventional single-zone SSC models, or models invoking external radiation fields (EC).

Characterizing the γ-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT

NASA Astrophysics Data System (ADS)

H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'C.; Dubus, G.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hadasch, D.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.

2017-02-01

Studying the temporal variability of BL Lac objects at the highest energies provides unique insights into the extreme physical processes occurring in relativistic jets and in the vicinity of super-massive black holes. To this end, the long-term variability of the BL Lac object PKS 2155-304 is analyzed in the high (HE, 100 MeV < E < 300 GeV) and very high energy (VHE, E > 200 GeV) γ-ray domain. Over the course of 9 yr of H.E.S.S. observations the VHE light curve in the quiescent state is consistent with a log-normal behavior. The VHE variability in this state is well described by flicker noise (power-spectral-density index ) on timescales larger than one day. An analysis of 5.5 yr of HE Fermi-LAT data gives consistent results (, on timescales larger than 10 days) compatible with the VHE findings. The HE and VHE power spectral densities show a scale invariance across the probed time ranges. A direct linear correlation between the VHE and HE fluxes could neither be excluded nor firmly established. These long-term-variability properties are discussed and compared to the red noise behavior (β 2) seen on shorter timescales during VHE-flaring states. The difference in power spectral noise behavior at VHE energies during quiescent and flaring states provides evidence that these states are influenced by different physical processes, while the compatibility of the HE and VHE long-term results is suggestive of a common physical link as it might be introduced by an underlying jet-disk connection.

Fermi-LAT and Swift-XRT observe exceptionally high activity from the nearby TeV blazar Mrk421

NASA Astrophysics Data System (ADS)

Paneque, D.; D'Ammando, F.; Orienti, M.; Falcon, A.

2013-04-01

The high-synchrotron-peaked BL Lac Mrk421 (also known as 2FGL J1104.4+3812, Nolan et al. 2012, ApJS, 199, 31; R.A.= 11h04m27.3139s, Dec.= +38d12m31.799s, J2000.0, Fey et al. 2004, AJ, 127, 3587), at redshift z=0.03, is the subject of an extensive multi-year and multi-instrument program that aims at characterizing with exquisite detail the temporal evolution of the blazar emission across the electromagnetic spectrum.

Optical Spectra of Four Objects Identified with Variable Radio Sources

NASA Astrophysics Data System (ADS)

Chavushyan, V.; Mujica, R.; Gorshkov, A. G.; Konnikova, V. K.; Mingaliev, M. G.

2000-06-01

We obtained optical spectra of four objects identified with variable radio sources. Three objects (0029+0554, 0400+0550, 2245+0500) were found to be quasars with redshifts of 1.314, 0.761, and 1.091. One object (2349+0534) has a continuum spectrum characteristic of BL Lac objects. We analyze spectra of the radio sources in the range 0.97-21.7 GHz for the epoch 1997 and in the range 3.9-11.1 GHz for the epoch 1990, as well as the pattern of variability of their flux densities on time scales of 1.5 and 7 years.

The X-ray spectra of blazars: Analysis of the complete EXOSAT archive

NASA Technical Reports Server (NTRS)

Sambruna, Rita M.; Barr, Paul; Giommi, Paolo; Maraschi, Laura; Tagliaferri, Gianpiero; Treves, Aldo

1994-01-01

We analyzed the 0.1-10 keV spectra of 26 blazars (21 BL Lac objects and 5 highly polarized quasars), on the basis of 93 exposures taken from the EXOSAT archives. Fits were performed first with a single power-law model. Indications are found that better fits can be obtained with models where the slope steepens at higher energies. We therefore considered a broken power law and found that in a large fraction of the spectra the fit is significantly improved. Fits with a power law + oxygen edge at 0.6 keV are also explored.

Simultaneous Planck , Swift , and Fermi observations of X-ray and γ -ray selected blazars

DOE PAGES

Giommi, P.; Polenta, G.; Lähteenmäki, A.; ...

2012-05-22

We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and γ-ray bands, with additional 5GHz flux-density limits to ensure a good probability of a Planck detection. We compare our results to those of a companion paper presenting simultaneous Planck and multi-frequency observations of 104 radio-loud northern active galactic nuclei selected at radio frequencies. While we confirm several previous results, our unique data set allows us to demonstrate that the selection method strongly influences the results, producing biases that cannot be ignored. Almost all themore » BL Lac objects have been detected by the Fermi Large AreaTelescope (LAT), whereas 30% to 40% of the flat-spectrum radio quasars (FSRQs) in the radio, soft X-ray, and hard X-ray selected samples are still below the γ-ray detection limit even after integrating 27 months of Fermi-LAT data. The radio to sub-millimetre spectral slope of blazars is quite flat, with >α> ~ 0 up to about 70GHz, above which it steepens to ~ -0.65. The BL Lacs have significantly flatter spectra than FSRQs at higher frequencies. The distribution of the rest-frame synchrotron peak frequency (ν peak S) in the spectral energy distribution (SED) of FSRQs is the same in all the blazar samples with peak S> = 10 13.1 ± 0.1 Hz, while the mean inverse Compton peak frequency, >ν peak IC>, ranges from 1021 to 1022 Hz. The distributions of ν peak S and ν peak IC of BL Lacs are much broader and are shifted to higher energies than those of FSRQs; their shapes strongly depend on the selection method. The Compton dominance of blazars, defined as the ratio of the inverse Compton to synchrotron peak luminosities, ranges from less than 0.2 to nearly 100, with only FSRQs reaching values larger than about 3. Its distribution is broad and depends strongly on the selection method, with γ-ray selected blazars peaking at ~7 or more, and radio-selected blazars at values close to 1, thus implying that the common assumption that the blazar power budget is largely dominated by high-energy emission is a selection effect. A comparison of our multi-frequency data with theoretical predictions shows that simple homogeneous SSC models cannot explain the simultaneous SEDs of most of the γ-ray detected blazars in all samples. The SED of the blazars that were not detected by Fermi-LAT may instead be consistent with SSC emission. Our data challenge the correlation between bolometric luminosity and ν peak S predicted by the blazar sequence.« less

Optical monitoring of Active Galactic Nuclei from ARIES

NASA Astrophysics Data System (ADS)

Gopal-Krishna; Wiita, Paul Joseph

2018-04-01

This overview provides a historical perspective highlighting the pioneering role which the fairly modest observational facilities of ARIES have played since the 1990s in systematically characterizing the optical variability on hour-like time scale (intra-night optical variability, or INOV) of several major types of high-luminosity Active Galactic Nuclei (AGN). Such information was previously available only for blazars. Similar studies have since been initiated in at least a dozen countries, giving a boost to AGN variability research. Our work has, in particular, provided strong indication that mild INOV occurs in radio-quiet QSOs (amplitude up to 3 – 5 % and duty cycle 10%) and, moreover, has demonstrated that similarly mild INOV is exhibited even by the vast majority of radio-loud quasars which possess powerful relativistic jets (even including many that are beamed towards us). The solitary outliers are blazars, the tiny strongly polarized subset of powerful AGN, which frequently exhibit a pronounced INOV. Among the blazars, BL Lac objects often show a bluer-when-brighter chromatic behavior, while the flat spectrum radio quasars seem not to. Quantifying any differences of INOV among the major subclasses of non-blazar type AGNs will require dedicated monitoring programs using 2 - 3 metre class telescopes.

Blazar flaring patterns (B-FlaP) classifying blazar candidate of uncertain type in the third Fermi-LAT catalogue by artificial neural networks

NASA Astrophysics Data System (ADS)

Chiaro, G.; Salvetti, D.; La Mura, G.; Giroletti, M.; Thompson, D. J.; Bastieri, D.

2016-11-01

The Fermi-Large Area Telescope (LAT) is currently the most important facility for investigating the GeV γ-ray sky. With Fermi-LAT, more than three thousand γ-ray sources have been discovered so far. 1144 (˜40 per cent) of the sources are active galaxies of the blazar class, and 573 (˜20 per cent) are listed as blazar candidate of uncertain type (BCU), or sources without a conclusive classification. We use the empirical cumulative distribution functions and the artificial neural networks for a fast method of screening and classification for BCUs based on data collected at γ-ray energies only, when rigorous multiwavelength analysis is not available. Based on our method, we classify 342 BCUs as BL Lacs and 154 as flat-spectrum radio quasars, while 77 objects remain uncertain. Moreover, radio analysis and direct observations in ground-based optical observatories are used as counterparts to the statistical classifications to validate the method. This approach is of interest because of the increasing number of unclassified sources in Fermi catalogues and because blazars and in particular their subclass high synchrotron peak objects are the main targets of atmospheric Cherenkov telescopes.

SYSTEMATIC STUDY OF GAMMA-RAY-BRIGHT BLAZARS WITH OPTICAL POLARIZATION AND GAMMA-RAY VARIABILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Itoh, Ryosuke; Fukazawa, Yasushi; Kanda, Yuka

Blazars are highly variable active galactic nuclei that emit radiation at all wavelengths from radio to gamma rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies, and it also varies dramatically. The polarization of blazars is of interest for understanding the origin, confinement, and propagation of jets. However, even though numerous measurements have been performed, the mechanisms behind jet creation, composition, and variability are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars between 2008 July and 2014 December to investigate the mechanisms of variability and search formore » a basic relation between the several subclasses of blazars. We identify a correlation between the maximum degree of optical linear polarization and the gamma-ray luminosity or the ratio of gamma-ray to optical fluxes. Since the maximum polarization degree depends on the condition of the magnetic field (chaotic or ordered), this result implies a systematic difference in the intrinsic alignment of magnetic fields in parsec-scale relativistic jets between different types of blazars (flat-spectrum radio quasars vs. BL Lacs) and consequently between different types of radio galaxies (FR I versus FR II).« less

Lysines 72, 80 and 213 and aspartic acid 210 of the Lactococcus lactis LacR repressor are involved in the response to the inducer tagatose-6-phosphate leading to induction of lac operon expression.

PubMed

van Rooijen, R J; Dechering, K J; Niek, C; Wilmink, J; de Vos, W M

1993-02-01

Site-directed mutagenesis of the Lactococcus lactis lacR gene was performed to identify residues in the LacR repressor that are involved in the induction of lacABCDFEGX operon expression by tagatose-6-phosphate. A putative inducer binding domain located near the C-terminus was previously postulated based on homology studies with the Escherichia coli DeoR family of repressors, which all have a phosphorylated sugar as inducer. Residues within this domain and lysine residues that are charge conserved in the DeoR family were changed into alanine or arginine. The production of the LacR mutants K72A, K80A, K80R, D210A, K213A and K213R in the LacR-deficient L.lactis strain NZ3015 resulted in repressed phospho-beta-galactosidase (LacG) activities and decreased growth rates on lactose. Gel mobility shift assays showed that the complex between a DNA fragment carrying the lac operators and LacR mutants K72A, K80A, K213A and D210A did not dissociate in the presence of tagatose-6-phosphate, in contrast to wild type LacR. Other mutations (K62A/K63A, K72R, K73A, K73R, T212A, F214R, R216R and R216K) exhibited no gross effects on inducer response. The results strongly suggest that the lysines at positions 72, 80 and 213 and aspartic acid at position 210 are involved in the induction of lac operon expression by tagatose-6-phosphate.

Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations

DOE PAGES

D'Ammando, F.; Antolini, E.; Tosti, G.; ...

2013-03-20

Here, we report on multiwavelength observations of the blazar PKS 0537-441 (z = 0.896) obtained from microwaves through γ-rays by Submillimeter Array, Rapid Eye Mounting, Automatic Telescope for Optical Monitoring (ATOM), Swift and Fermi mostly during 2008 August–2010 April. Strong variability has been observed in γ-rays, with two major flaring episodes (2009 July and 2010 March) and a harder-when-brighter behaviour, quite common for flat spectrum radio quasars and low-synchrotron-peaked BL Lacertae objects (BL Lacs), in 2010 March. In the same way, the spectral energy distribution (SED) of the source cannot be modelled by a simple synchrotron self-Compton model, as opposedmore » to many BL Lacs, but the addition of an external Compton component of seed photons from a dust torus is needed. The 230 GHz light curve showed an increase simultaneous with the γ-ray one, indicating co-spatiality of the mm and γ-ray emission region likely at large distance from the central engine. The low, average, and high activity SED of the source could be fit changing only the electron distribution parameters, but two breaks in the electron distribution are necessary. The ensuing extra spectral break, located at near-infrared (NIR)–optical frequencies, together with that in γ-rays seem to indicate a common origin, most likely due to an intrinsic feature in the underlying electron distribution. An overall correlation between the γ-ray band with the R band and K band has been observed with no significant time lag. On the other hand, when inspecting the light curves on short time-scales some differences are evident. In particular, flaring activity has been detected in NIR and optical bands with no evident γ-ray counterparts in 2009 September and November. Moderate variability has been observed in X-rays with no correlation between flux and photon index. Finally, an increase of the detected X-ray flux with no counterpart at the other wavelengths has been observed in 2008 October, suggesting once more a complex correlation between the emission at different energy bands.« less

Observations and analysis activities of the International Ultraviolet Explorer satellite telescope

NASA Technical Reports Server (NTRS)

Shull, J. Michael

1996-01-01

The funds from this grant were used to support observations and analysis with the International Ultraviolet Explorer (IUE) satellite telescope. The main area of scientific research concerned the variability analyses of ultraviolet spectra of Active Galactic Nuclei, primarily quasars, Seyfert galaxies, and BL Lacertae objects. The Colorado group included, at various times, the P.I. (J.M. Shull), Research Associate Dr. Rick Edelson, and graduate students Jon Saken, Elise Sachs, and Steve Penton. A portion of the work was also performed by CU undergraduate student Cheong-ming Fu. A major product of the effort was a database of all IUE spectra of active galactic nuclei. This database is being analyzed to obtain spectral indices, line fluxes, and continuum fluxes for over 500 AGN. As a by-product of this project, we implemented a new, improved technique of spectral extraction of IUE spectra, which has been used in several AGN-WATCH campaigns (on the Seyfert galaxy NGC 4151 and on the BL Lac object PKS 2155-304).

Detection of Possible Quasi-periodic Oscillations in the Long-term Optical Light Curve of the BL Lac Object OJ 287

NASA Astrophysics Data System (ADS)

Bhatta, G.; Zola, S.; Stawarz, Ł.; Ostrowski, M.; Winiarski, M.; Ogłoza, W.; Dróżdż, M.; Siwak, M.; Liakos, A.; Kozieł-Wierzbowska, D.; Gazeas, K.; Debski, B.; Kundera, T.; Stachowski, G.; Paliya, V. S.

2016-11-01

The detection of periodicity in the broadband non-thermal emission of blazars has so far been proven to be elusive. However, there are a number of scenarios that could lead to quasi-periodic variations in blazar light curves. For example, an orbital or thermal/viscous period of accreting matter around central supermassive black holes could, in principle, be imprinted in the multi-wavelength emission of small-scale blazar jets, carrying such crucial information about plasma conditions within the jet launching regions. In this paper, we present the results of our time series analysis of the ˜9.2 yr long, and exceptionally well-sampled, optical light curve of the BL Lac object OJ 287. The study primarily used the data from our own observations performed at the Mt. Suhora and Kraków Observatories in Poland, and at the Athens Observatory in Greece. Additionally, SMARTS observations were used to fill some of the gaps in the data. The Lomb-Scargle periodogram and the weighted wavelet Z-transform methods were employed to search for possible quasi-periodic oscillations in the resulting optical light curve of the source. Both methods consistently yielded a possible quasi-periodic signal around the periods of ˜400 and ˜800 days, the former with a significance (over the underlying colored noise) of ≥slant 99 % . A number of likely explanations for this are discussed, with preference given to a modulation of the jet production efficiency by highly magnetized accretion disks. This supports previous findings and the interpretation reported recently in the literature for OJ 287 and other blazar sources.

A Multiwavelength Study of Flaring Activity in the High-energy Peaked BL Lac Object 1ES 1959+650 During 2015–2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Navpreet; Chandra, S.; Baliyan, Kiran S

We present the results from a multiwavelength study of the flaring activity in the high-energy peaked BL Lac object 1ES 1959+650 during 2015 January–2016 June. The source underwent two major outbursts, during 2015 March and 2015 October, across the whole electromagnetic spectrum (EMS). We used data from Fermi -LAT and Swift -XRT/UVOT, and optical data from Mt. Abu InfraRed Observatory and Steward Observatory to look for possible correlations between the emissions at different energies and the nature of the variability during the flaring state. During the 2015 October outburst, the nightly averaged V -band brightest magnitude, 14.45(0.03), and faintest magnitude,more » 14.45(0.03), were recorded. Apart from long-term flares, rapid and short-term variabilities were noticed at all energies. Our study suggests that the flaring activities at all frequencies, with diverse flare durations and time lags, are correlated. The magnetic field strength is estimated to be 4 G using the synchrotron-cooling timescale (2.3 hr), and the upper limits on the sizes of both emission regions, γ -ray and optical, are estimated to be of the order of 10{sup 16} cm. The quasi-simultaneous flux enhancements in 15 GHz and VHE γ -ray emissions indicate a fresh injection of plasma into the jet, which interacts with a standing submillimeter core, resulting in co-spatial emissions across the EMS. The synchrotron peak shifts to higher frequency in the spectral energy distribution while the γ -ray spectra softens during the flaring. The shape of the inverse-Compton spectra indicates a change in the particle energy distribution pre- and post-flare.« less

On the Redshift of TeV BL Lac Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paiano, Simona; Falomo, Renato; Landoni, Marco

2017-03-10

We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV energies, aiming to determine or constrain their redshift. This is of fundamental importance for the interpretation of their emission models and for population studies and is also mandatory for studying the interaction of high-energy photons with the extragalactic background light using TeV sources. Optical spectra with high signal-to-noise ratios in the range 4250–10000 Å were obtained to search for faint emission or absorption lines from both the host galaxy and themore » nucleus. We determine a new redshift for PKS 1424+240 ( z = 0.604) and a tentative one for 1ES 0033+595 ( z = 0.467). We are able to set new spectroscopic redshift lower limits for three other sources on the basis of Mg ii and Ca ii intervening absorption features: BZB J1243+3627 ( z > 0.483), BZB J1540+8155 ( z > 0.672), and BZB 0J2323+4210 ( z > 0.267). We confirm previous redshift estimates for four blazars: S3 0218+357 ( z = 0.944), 1ES 1215+303 ( z = 0.129), W Comae ( z = 0.102), and MS 1221.8+2452 ( z = 0.218). For the remaining targets, in seven cases (S2 0109+22, 3C 66A, VER J0521+211, S4 0954+65, BZB J1120+4214, S3 1227+25, BZB J2323+4210), we do not validate the proposed redshift. Finally, for all sources of still-unknown redshift, we set a lower limit based on the minimum equivalent width of absorption features expected from the host galaxy.« less

A Multiwavelength Study of Flaring Activity in the High-energy Peaked BL Lac Object 1ES 1959+650 During 2015-2016

NASA Astrophysics Data System (ADS)

Kaur, Navpreet; Chandra, S.; Baliyan, Kiran S.; Sameer; Ganesh, S.

2017-09-01

We present the results from a multiwavelength study of the flaring activity in the high-energy peaked BL Lac object 1ES 1959+650 during 2015 January-2016 June. The source underwent two major outbursts, during 2015 March and 2015 October, across the whole electromagnetic spectrum (EMS). We used data from Fermi-LAT and Swift-XRT/UVOT, and optical data from Mt. Abu InfraRed Observatory and Steward Observatory to look for possible correlations between the emissions at different energies and the nature of the variability during the flaring state. During the 2015 October outburst, the nightly averaged V-band brightest magnitude, 14.45(0.03), and faintest magnitude, 14.45(0.03), were recorded. Apart from long-term flares, rapid and short-term variabilities were noticed at all energies. Our study suggests that the flaring activities at all frequencies, with diverse flare durations and time lags, are correlated. The magnetic field strength is estimated to be 4 G using the synchrotron-cooling timescale (2.3 hr), and the upper limits on the sizes of both emission regions, γ-ray and optical, are estimated to be of the order of 1016 cm. The quasi-simultaneous flux enhancements in 15 GHz and VHE γ-ray emissions indicate a fresh injection of plasma into the jet, which interacts with a standing submillimeter core, resulting in co-spatial emissions across the EMS. The synchrotron peak shifts to higher frequency in the spectral energy distribution while the γ-ray spectra softens during the flaring. The shape of the inverse-Compton spectra indicates a change in the particle energy distribution pre- and post-flare.

Extracorporeal circulation as a new experimental pathway for myoblast implantation in mdx mice.

PubMed

Torrente, Y; D'Angelo, M G; Del Bo, R; DeLiso, A; Casati, R; Benti, R; Corti, S; Comi, G P; Gerundini, P; Anichini, A; Scarlato, G; Bresolin, N

1999-01-01

The deficiency of dystrophin, a sarcolemmal associated protein, is responsible for Duchenne muscular dystrophy (DMD). Gene replacement is attractive as a potential therapy. In this article, we describe a new method for myoblast transplantation and expression of dystrophin in skeletal muscle tissue of dystrophin-deficient mdx mouse through iliac vessels extracorporeal circulation. We evaluated the extracorporeal circulation as an alternative route of delivering myoblasts to the target tissue. Two series of experiments were performed with the extracorporeal circulation. In a first series, L6 rat myoblasts, transfected with LacZ reporter gene, were perfused in limbs of 15 rats. In the second series, the muscle limbs of three 6-8-week-old mdx were perfused with myoblasts of donor C57BL10J mice. Before these perfusions, the right tibialis anterior (TA) muscle of the rats and mdx was injected three times at several sites with bupivacaine (BPVC) and hyaluronidase. The ability of injected cells to migrate in the host tissue was assessed in rats by technetium-99m cell labeling. No radioactivity was detected in the lungs, bowels, and liver of animals treated with extracorporeal circulation. The tissue integration and viability of the myoblasts were ultimately confirmed by genetic and histochemical analysis of LacZ reporter gene. Following a single extracorporeal perfusion of myoblasts from donor C57BL10J, sarcolemmal expression of dystrophin was observed in clusters of myofibers in tibialis anterior muscles previously treated with BPVC and hyaluronidase. Furthermore, large clusters of dystrophin-positive fibers were observed in muscles up to 21 days after repeated treatments. These clusters represented an average of 4.2% of the total muscle fibers. These results demonstrate that the extracorporeal circulation allows selective myoblast-mediated gene transfer to muscles, opening new perspectives in muscular dystrophy gene therapy.

Does the Blazar Gamma-ray Spectrum Harden with Increasing Flux? - Analysis of Nine Years of EGRET Data

NASA Technical Reports Server (NTRS)

Nandikotkur, Giridhar; Jahoda, Keith M.; Hartman, R. C.; Mukherjee, R.; Sreekumar, P.; Boettcher, M.

2007-01-01

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) discovered gamma-ray emission from more than 67 blazars during its nine-year lifetime. We conducted an exhaustive search of the EGRET archives and selected all the blazars that were observed multiple times and were bright enough to enable a spectral analysis using standard powerlaw models. The sample consists of 18 flat-spectrum radio quasars (FSRQs), 6 low-frequency-peaked BL Lacs (LBLs) and 2 high-frequency-peaked BL Lacs (HBLs). We do not detect any clear pattern in'the variation of spectral index with flux. Some of the blazars do not show any statistical evidence for spectral variability. The spectrum hardens with increasing flux in a few cases. There is also evidence for a flux-hardness anticorrelation at lo\\v fluxes in five blazars. The well observed blazars (3C 279,3C 273, PKS 0528-i-134, PKS 1622-297, PKS 0208- 512) do not show any overall trend in the long-term spectral dependence on flux, but the sample shows a mixture of hard and soft states. We observed spectral hysteresis at weekly timescales in all the three FSRQs for which data from flares lasting for 3 approx. 4 weeks were available. All three sources show a counterclockwise rotation despite the widely different flux profiles. Hysteresis in the spectral index vs. flux space has never been observed in FSRQs in gamma-rays at weekly timescales. itre analyze the observed spectral behavior in the context of various inverse-Compton mechanisms believed to be responsible for emission in the EGRET energy range. Our analysis uses the EGRET skymaps that were regenerated to include the changes in performance during the mission.

VERITAS Detection of γ-Ray Flaring Activity From the BL Lac Object 1ES 1727+502 During Bright Moonlight Observations

NASA Astrophysics Data System (ADS)

Archambault, S.; Archer, A.; Beilicke, M.; Benbow, W.; Bird, R.; Biteau, J.; Bouvier, A.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Håkansson, N.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Pohl, M.; Popkow, A.; Prokoph, H.; Pueschel, E.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vincent, S.; Wakely, S. P.; Weinstein, A.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zitzer, B.; Veritas Collaboration; Hughes, Z. D.

2015-08-01

During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHEs, E\\gt 100 GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations with the VERITAS telescopes in the standard configuration are performed only with a moon illumination less than 35% of full moon. Since 2012, the VERITAS collaboration has implemented a new observing mode under bright moonlight, by either reducing the voltage applied to the PMTs (reduced-high-voltage; RHV configuration), or by utilizing UV-transparent filters. While these operating modes result in lower sensitivity and increased energy thresholds, the extension of the available observing time is useful for monitoring variable sources such as blazars and sources requiring spectral measurements at the highest energies. In this paper we report the detection of γ-ray flaring activity from the BL Lac object 1ES 1727+502 during RHV observations. This detection represents the first evidence of VHE variability from this blazar. The integral flux is (1.1+/- 0.2)× {10}-11 {{cm}}-2 {{{s}}}-1 above 250 GeV, which is about five times higher than the low-flux state. The detection triggered additional VERITAS observations during standard dark-time. Multiwavelength observations with the FLWO 48″ telescope, and the Swift and Fermi satellites are presented and used to produce the first spectral energy distribution (SED) of this object during γ-ray flaring activity. The SED is then fitted with a standard synchrotron-self-Compton model, placing constraints on the properties of the emitting region and of the acceleration mechanism at the origin of the relativistic particle population in the jet.

The Ionization Source in the Nucleus of M84

NASA Technical Reports Server (NTRS)

Bower, G. A.; Green, R. F.; Quillen, A. C.; Danks, A.; Malumuth, E. M.; Gull, T.; Woodgate, B.; Hutchings, J.; Joseph, C.; Kaiser, M. E.

2000-01-01

We have obtained new Hubble Space Telescope (HST) observations of M84, a nearby massive elliptical galaxy whose nucleus contains a approximately 1.5 X 10(exp 9) solar mass dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph (STIS) spectrum provides the first clear detection of emission lines in the blue (e.g., [0 II] lambda 3727, HBeta and [0 III] lambda lambda4959,5007), which arise from a compact region approximately 0".28 across centered on the nucleus. Our Near Infrared Camera and MultiObject Spectrometer (NICMOS) images exhibit the best view through the prominent dust lanes evident at optical wavelengths and provide a more accurate correction for the internal extinction. The relative fluxes of the emission lines we have detected in the blue together with those detected in the wavelength range 6295 - 6867 A by Bower et al. indicate that the gas at the nucleus is photoionized by a nonstellar process, instead of hot stars. Stellar absorption features from cool stars at the nucleus are very weak. We update the spectral energy distribution of the nuclear point source and find that although it is roughly flat in most bands, the optical to UV continuum is very red, similar to the spectral energy distribution of BL Lac. Thus, the nuclear point source seen in high-resolution optical images is not a star cluster but is instead a nonstellar source. Assuming isotropic emission from this source, we estimate that the ratio of bolometric luminosity to Eddington luminosity is about 5 x 10(exp -7). However, this could be underestimated if this source is a misaligned BL Lac object, which is a possibility suggested by the spectral energy distribution and the evidence of optical variability we describe.

Food-grade host/vector expression system for Lactobacillus casei based on complementation of plasmid-associated phospho-beta-galactosidase gene lacG.

PubMed

Takala, T M; Saris, P E J; Tynkkynen, S S H

2003-01-01

A new food-grade host/vector system for Lactobacillus casei based on lactose selection was constructed. The wild-type non-starter host Lb. casei strain E utilizes lactose via a plasmid-encoded phosphotransferase system. For food-grade cloning, a stable lactose-deficient mutant was constructed by deleting a 141-bp fragment from the phospho-beta-galactosidase gene lacG via gene replacement. The deletion resulted in an inactive phospho-beta-galactosidase enzyme with an internal in-frame deletion of 47 amino acids. A complementation plasmid was constructed containing a replicon from Lactococcus lactis, the lacG gene from Lb. casei, and the constitutive promoter of pepR for lacG expression from Lb. rhamnosus. The expression of the lacG gene from the resulting food-grade plasmid pLEB600 restored the ability of the lactose-negative mutant strain to grow on lactose to the wild-type level. The vector pLEB600 was used for expression of the proline iminopeptidase gene pepI from Lb. helveticus in Lb. casei. The results show that the food-grade expression system reported in this paper can be used for expression of foreign genes in Lb. casei.

[Effect of genotype and day or night time of testing on mice behavior in the light-dark box and the open-field tests].

PubMed

Morozova, M V; Kulikov, A V

2010-01-01

The light-dark box (LDB) and the open-field (OF) tests are widespread experimental models for studying locomotion and anxiety in laboratory rats and mice. The fact that rodents are nocturnal animals and more active at night raises a critical question of whether behavioral experiments carried out in the light phase are methodologically correct. Parameters of behavior of four mouse strains (C57BL/6J, DBA2/J, AKR/J and CBA/LacJ) in the light-dark box and open-field tests in the light and dark phases were compared. No significant influence of the phase of testing on anxiety in LDB and OF tests was revealed. In the OF test CBA mice showed increased locomotor activity, whereas AKR and C57BL/6 mice showed increased defecation in the dark phase. It was concluded that: 1) the phase of testing is not crucial for the expression of anxiety in LDB and OF; 2) the sensitivity to the phase of testing depends on the genotype; 3) the indices of behavior in the genotypes sensitive to the phase of testing (locomotion in the CBA and defecation in the AKR and C57BL/6 mouse strains) are increased in the dark phase.

The Blazar 3C 66A in 2003-2004: hadronic versus leptonic model fits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reimer, A.; Joshi, M.; Boettcher, M.

2008-12-24

The low-frequency peaked BL Lac object 3C 66A was the subject of an extensive multi-wavelength campaign from July 2003 till April 2004, which included quasi-simultaneous observations at optical, X-rays and very high energy gamma-rays. Here we apply the hadronic Synchrotron-Proton Blazar (SPB) model to the observed spectral energy distribution time-averaged over a flaring state, and compare the resulting model fits to those obtained from the application of the leptonic Synchrotron-Self-Compton (SSC) model. The results are used to identify diagnostic key predictions of the two blazar models for future multi-wavelength observations.

Plasmid linkage of the D-tagatose 6-phosphate pathway in Streptococcus lactis: effect on lactose and galactose metabolism.

PubMed Central

Crow, V L; Davey, G P; Pearce, L E; Thomas, T D

1983-01-01

The three enzymes of the D-tagatose 6-phosphate pathway (galactose 6-phosphate isomerase, D-tagatose 6-phosphate kinase, and tagatose 1,6-diphosphate aldolase) were absent in lactose-negative (Lac-) derivatives of Streptococcus lactis C10, H1, and 133 grown on galactose. The lactose phosphoenolpyruvate-dependent phosphotransferase system and phospho-beta-galactosidase activities were also absent in Lac- derivatives of strains H1 and 133 and were low (possibly absent) in C10 Lac-. In all three Lac- derivatives, low galactose phosphotransferase system activity was found. On galactose, Lac- derivatives grew more slowly (presumably using the Leloir pathway) than the wild-type strains and accumulated high intracellular concentrations of galactose 6-phosphate (up to 49 mM); no intracellular tagatose 1,6-diphosphate was detected. The data suggest that the Lac phenotype is plasmid linked in the three strains studied, with the evidence being more substantial for strain H1. A Lac- derivative of H1 contained a single plasmid (33 megadaltons) which was absent from the Lac- mutant. We suggest that the genes linked to the lactose plasmid in S. lactis are more numerous than previously envisaged, coding for all of the enzymes involved in lactose metabolism from initial transport to the formation of triose phosphates via the D-tagatose 6-phosphate pathway. Images PMID:6294064

Variable gamma-ray sky at 1 GeV

NASA Astrophysics Data System (ADS)

Pshirkov, M. S.; Rubtsov, G. I.

2013-01-01

We search for the long-term variability of the gamma-ray sky in the energy range E > 1 GeV with 168 weeks of the gamma-ray telescope Fermi-LAT data. We perform a full sky blind search for regions with variable flux looking for deviations from uniformity. We bin the sky into 12288 pixels using the HEALPix package and use the Kolmogorov-Smirnov test to compare weekly photon counts in each pixel with the constant flux hypothesis. The weekly exposure of Fermi-LAT for each pixel is calculated with the Fermi-LAT tools. We consider flux variations in a pixel significant if the statistical probability of uniformity is less than 4 × 10-6, which corresponds to 0.05 false detections in the whole set. We identified 117 variable sources, 27 of which have not been reported variable before. The sources with previously unidentified variability contain 25 active galactic nuclei (AGN) belonging to the blazar class (11 BL Lacs and 14 FSRQs), one AGN of an uncertain type, and one pulsar PSR J0633+1746 (Geminga).

X-ray spectra and time variability of active galactic nuclei

NASA Technical Reports Server (NTRS)

Mushotzky, R. F.

1984-01-01

The X-ray spectra of broad line active galactic nuclei (AGN) of all types (Seyfert I's, NELG's, broadline radio galaxies) are well fit by a power law in the .5 to 100 keV band of man energy slope alpha = .68 + or - .15. There is, as yet, no strong evidence for time variability of this slope in a given object. The constraints that this places on simple models of the central energy source are discussed. BL Lac objects have quite different X-ray spectral properties and show pronounced X-ray spectral variability. On time scales longer than 12 hours most radio quiet AGN do not show strong, delta I/I .5, variability. The probability of variability of these AGN seems to be inversely related to their luminosity. However characteristics timescales for variability have not been measured for many objects. This general lack of variability may imply that most AGN are well below the Eddington limit. Radio bright AGN tend to be more variable than radio quiet AGN on long, tau approx 6 month, timescales.

Simultaneous Planck, Swift, and Fermi Observations of X-ray and Gamma-ray Selected Blazars

NASA Technical Reports Server (NTRS)

Giommi, P.; Polenta, G.; Laehteenmaeki, A.; Thompson, D. J.; Capalbi, M.; Cutini, S.; Gasparrini, D.; Gonzalez, Nuevo, J.; Leon-Tavares, J.; Lopez-Caniego, M.;

Understanding nature's particle accelerators using high energy gamma-ray survey instruments

NASA Astrophysics Data System (ADS)

Abeysekara, Anushka Udara

Nature's particle accelerators, such as Pulsars, Pulsar Wind Nebulae, Active Galactic Nuclei and Supernova Remnants accelerate charged particles to very high energies that then produce high energy photons. The particle acceleration mechanisms and the high energy photon emission mechanisms are poorly understood phenomena. These mechanisms can be understood either by studying individual sources in detail or, alternatively, using the collective properties of a sample of sources. Recent development of GeV survey instruments, such as Fermi-LAT, and TeV survey instruments, such as Milagro, provides a large sample of high energy gamma-ray flux measurements from galactic and extra-galactic sources. In this thesis I provide constraints on GeV and TeV radiation mechanisms using the X-ray-TeV correlations and GeV-TeV correlations. My data sample was obtained from three targeted searches for extragalactic sources and two targeted search for galactic sources, using the existing Milagro sky maps. The first extragalactic candidate list consists of Fermi-LAT GeV extragalactic sources, and the second extragalactic candidate list consists of TeVCat extragalactic sources that have been detected by Imaging Atmospheric Cerenkov Telescopes (IACTs). In both extragalactic candidate lists Markarian 421 was the only source detected by Milagro. A comparison between the Markarian 421 time-averaged flux, measured by Milagro, and the flux measurements of transient states, measured by IACTs, is discussed. The third extragalactic candidate list is a list of potential TeV emitting BL Lac candidates that was synthesized using X-ray observations of BL Lac objects and a Synchrotron Self-Compton model. Milagro's sensitivity was not sufficient to detect any of those candidates. However, the 95% confidence flux upper limits of those sources were above the predicted flux. Therefore, these results provide evidence to conclude that the Synchrotron Self-Compton model for BL Lac objects is still a viable model. Targeted searches for galactic candidates were able to measure TeV emission associated with 14 Fermi-LAT GeV pulsars. In this thesis I also presented a new multi-wavelength technique that I developed to isolate the flux correlation factor (fΩ ) of pulsars as a function of pulsar spin down luminosity. The correlation between fΩ and pulsar spin-down luminosity for a Fermi-LAT GeV pulsar sample was measured using the measurements obtained in the Milagro targeted search performed for galactic sources and from the literature. The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap and One Pole Caustic models for pulsar emission in the energy range of 0.1 to 100 GeV. However, these simulated models failed to explain many other important pulsar population characteristics. Therefore, further improvements on the galactic pulsar population simulations are needed to provide tighter constraints.

Simultaneous Planck, Swift, and Fermi Observations of X-Ray and gamma-Ray Selected Blazars

NASA Technical Reports Server (NTRS)

Giommi, P.; Polenta, G.; Laehteenmaeki, A.; Thompson, D. J.; Capalbi, M.; Cutini, S.; Gasparrini, D.; Gonzalez-Nuevo, J.; Leon-Tavares, J.; Lopez-Caniego, M.;

Helicobacter pylori β1,3-N-acetylglucosaminyltransferase for versatile synthesis of type 1 and type 2 poly-LacNAcs on N-linked, O-linked and I-antigen glycans

PubMed Central

Peng, Wenjie; Pranskevich, Jennifer; Nycholat, Corwin; Gilbert, Michel; Wakarchuk, Warren; Paulson, James C; Razi, Nahid

2012-01-01

Poly-N-acetyllactosamine extensions on N- and O-linked glycans are increasingly recognized as biologically important structural features, but access to these structures has not been widely available. Here, we report a detailed substrate specificity and catalytic efficiency of the bacterial β3-N-acetylglucosaminyltransferase (β3GlcNAcT) from Helicobacter pylori that can be adapted to the synthesis of a rich diversity of glycans with poly-LacNAc extensions. This glycosyltransferase has surprisingly broad acceptor specificity toward type-1, -2, -3 and -4 galactoside motifs on both linear and branched glycans, found commonly on N-linked, O-linked and I-antigen glycans. This finding enables the production of complex ligands for glycan-binding studies. Although the enzyme shows preferential activity for type 2 (Galβ1-4GlcNAc) acceptors, it is capable of transferring N-acetylglucosamine (GlcNAc) in β1-3 linkage to type-1 (Galβ1-3GlcNAc) or type-3/4 (Galβ1-3GalNAcα/β) sequences. Thus, by alternating the use of the H. pylori β3GlcNAcT with galactosyltransferases that make the β1-4 or β1-3 linkages, various N-linked, O-linked and I-antigen acceptors could be elongated with type-2 and type-1 LacNAc repeats. Finally, one-pot incubation of di-LacNAc biantennary N-glycopeptide with the β3GlcNAcT and GalT-1 in the presence of uridine diphosphate (UDP)-GlcNAc and UDP-Gal, yielded products with 15 additional LacNAc units on the precursor, which was seen as a series of sequential ion peaks representing alternative additions of GlcNAc and Gal residues, on matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Overall, our data demonstrate a broader substrate specificity for the H. pylori β3GlcNAcT than previously recognized and demonstrate its ability as a potent resource for preparative chemo-enzymatic synthesis of complex glycans. PMID:22786570

[Study of the immunological mechanism of anti-tumor effects of 5-FU by establishing EL4 tumor-bearing mouse models].

PubMed

Li, Mo-Lin; Li, Chuan-Gang; Shu, Xiao-Hong; Li, Ming-Xia; Jia, Yu-Jie; Qin, Zhi-Hai

2007-11-01

To investigate the immunological mechanism of anti-tumor effect of 5-FU by establishing lymphoma EL4 tumor-bearing mouse models in wild type C57BL/6 mice and nude C57BL/6 mice, respectively. The mouse lymphoma EL4 cells were inoculated subcutaneously into wild type C57BL/6 mice (immune-competent mice). Twelve days later, 5-FU of different doses was administered intraperitoneally to treat these wild type C57BL/6 tumor-bearing mice. The size of tumors in the wild type C57BL/6 mice was observed and recorded to explore the minimal dose of 5-FU that could cure the tumor-bearing mice. Then the same amount of EL4 tumor cells was inoculated subcutaneously into wild type C57BL/6 mice and nude C57BL/6 mice (T cell-deficient mice) simultaneously, which had the same genetic background of C57BL/6. Twelve days later, 5-FU of the minimal dose was given intraperitoneally to treat both the wild type and nude C57BL/6 tumor-bearing mice. The size of tumors in the two different types of mice was observed and recorded. A single dose of 5-FU (75 mg/kg) cured both the EL4 tumor-bearing wild type C57BL/6 mice and the EL4 tumor-bearing nude C57BL/6 mice in the first week. Two weeks after 5-FU treatment, all of the nude mice died of tumor relapse while most of the wild type C57BL/6 mice were fully recovered. A single dose of 5-FU has marked anti-tumor effects on lymphoma EL4 tumor-bearing C57BL/6 mice with or without T lymphocytes. The relapse of tumors after 5-FU treatment might be related to the function of T lymphocytes.

Fourier analysis of blazar variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finke, Justin D.; Becker, Peter A., E-mail: justin.finke@nrl.navy.mil

Blazars display strong variability on multiple timescales and in multiple radiation bands. Their variability is often characterized by power spectral densities (PSDs) and time lags plotted as functions of the Fourier frequency. We develop a new theoretical model based on the analysis of the electron transport (continuity) equation, carried out in the Fourier domain. The continuity equation includes electron cooling and escape, and a derivation of the emission properties includes light travel time effects associated with a radiating blob in a relativistic jet. The model successfully reproduces the general shapes of the observed PSDs and predicts specific PSD and timemore » lag behaviors associated with variability in the synchrotron, synchrotron self-Compton, and external Compton emission components, from submillimeter to γ-rays. We discuss applications to BL Lacertae objects and to flat-spectrum radio quasars (FSRQs), where there are hints that some of the predicted features have already been observed. We also find that FSRQs should have steeper γ-ray PSD power-law indices than BL Lac objects at Fourier frequencies ≲ 10{sup –4} Hz, in qualitative agreement with previously reported observations by the Fermi Large Area Telescope.« less

THE OPTICAL MICROVARIABILITY AND SPECTRAL CHANGES OF THE BL LACERTAE OBJECT S5 0716+714

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poon, H.; Fu, J. N.; Fan, J. H.

We monitored the BL Lac object S5 0716+714 in the optical band during 2008 October and December and 2009 February with a best temporal resolution of about 5 minutes in the BVRI bands. Four fast flares were observed with amplitudes ranging from 0.3 to 0.75 mag. The source remained active during the whole monitoring campaign, showing microvariability in all days except for one. The overall variability amplitudes are {delta}B {approx} 0fm89, {delta}V {approx} 0fm80, {delta}R {approx} 0fm73, and {delta}I{approx} 0fm51. Typical timescales of microvariability range from 2 to 8 hr. The overall V - R color index ranges from 0.37more » to 0.59. Strong bluer-when-brighter chromatism was found on internight timescales. However, a different spectral behavior was found on intranight timescales. A possible time lag of {approx}11 minutes between B and I bands was found on one night. The shock-in-jet model and geometric effects can be applied to explain the source's intranight behavior.« less

First analysis of eight Algol-type binaries: EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri

NASA Astrophysics Data System (ADS)

Zasche, P.

2016-01-01

The available photometry from the online databases were used for the first light curve analysis of eight eclipsing binary systems EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri. All these stars are of Algol-type, having the detached components and the orbital periods from 0.92 to 6.8 days. For the systems EI Aur and BP Dra the large amount of the third light was detected during the light curve solution. Moreover, 468 new times of minima for these binaries were derived, trying to identify the period variations. For the systems XY Dra and VX Lac the third bodies were detected with the periods 17.7, and 49.3 years, respectively.

[Establishment of EL4 tumor-bearing mouse models and investigation on immunological mechanisms of anti-tumor effect of melphalan].

PubMed

Li, Mo-lin; Li, Chuan-gang; Shu, Xiao-hong; Jia, Yu-jie; Qin, Zhi-hai

2006-03-01

To establish mouse lymphoma EL4 tumor-bearing mouse models in wild type C57BL/6 mice and nude C57BL/6 mice respectively, and to further investigate the immunological mechanisms of anti-tumor effect of melphalan. Mouse lymphoma EL4 cells were inoculated subcutaneously into wild type C57BL/6 mice (immune-competent mice). Twelve days later, melphalan of different doses were administered intraperitoneally to treat these wild type C57BL/6 tuomr-bearing mice. Tumor sizes were observed and recorded subsequently to find out the minimal dose of melphalan that could cure the tuomr-bearing mice. Then the same amount of EL4 tumor cells were inoculated subcutaneously into wild type C57BL/6 mice and nude C57BL/6 mice (T cell-deficient mice) simultaneously, which had the same genetic background of C57BL/6. Twelve days later, melphalan of the minimal dose was given intraperitoneally to treat both the wild type and nude C57BL/6 tuomr-bearing mice. Tumor sizes were observed and recorded in these two different types of mice subsequently. A single dose of melphalan (7.5 mg/kg) could cure EL4 tumor-bearing wild type C57BL/6 mice, but could not induce tumor regression in EL4 tumor-bearing nude C57BL/6 mice. A single dose of melphalan has obvious anti-tumor effect on mouse lymphoma EL4 tumor-bearing wild type C57BL/6mice, which requires the involvement of T lymphocytes in the host probably related to their killing functions.

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

NASA Astrophysics Data System (ADS)

Titov, O.; Pursimo, T.; Johnston, Helen M.; Stanford, Laura M.; Hunstead, Richard W.; Jauncey, David L.; Zenere, Katrina A.

2017-04-01

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ˜160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Pursimo, T.

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radiomore » sources.« less

Multiwavelength studies of the blazars detected by AGILE

NASA Astrophysics Data System (ADS)

Filippo D'Ammando

2010-02-01

The discovery of emission in the gamma-ray domain from many Active Galactic Nuclei (AGNs) by EGRET on board the Compton Gamma-Ray Observatory and the Cherenkov Telescopes was one of the most breakthrough of high energy astrophysics in the last 20 years, leading to the identification of a new class of AGNs: the blazars. Blazars are the most extreme subclass of AGNs, characterized by the emission of strong non-thermal radiation across the entire electromagnetic spectrum, from radio to very high gamma-ray energies. This emission is interpreted as the result of the electromagnetic radiation from a relativistic jet that is viewed closely aligned to the line of sight of the observer, thus causing strong relativistic amplification. Considering that the large fraction of the total power of blazars is emitted in the gamma-rays, information in this energy band is crucial to study the different radiation models. More than ten years after the EGRET era, the AGILE satellite (and subsequently also the Fermi satellite) filled the gap in the MeV-GeV band giving further impulse to the study of the high-energy astrophysics phenomena in blazars. However, notwithstanding the importance of the information provided by the gamma-ray observations, correlated multiwavelength studies are the key to achieve a better understanding of the structure of the inner jet, the origin of the seed photons for the inverse Compton process and the emission mechanisms at work in blazars. Since its launch in April 2007, the AGILE satellite detected several blazars in high activity state: PKS 1510-089, S5 0716+714, 3C 454.3, 3C 273, 3C 279, W Comae, Mrk 421 and PG 1553+113. In this Thesis I will present the most interesting results on multifrequency analysis of these sources detected by AGILE in gamma-rays, together with the multiwavelength data from other observatories such as Spitzer, Swift, RXTE, Suzaku, INTEGRAL, MAGIC, VERITAS, as well as radio-to-optical coverage by means of GASP-WEBT and REM. This large multifrequency coverage gave me the opportunity to study the Spectral Energy Distributions (SEDs) of these sources from radio to gamma-rays, the correlated variability in different energy bands and to investigate the mechanisms responsible for their emission, uncovering in some cases a more complex behaviour with respect to the standard models. The intense gamma-ray flares of S5 0716+714 observed by AGILE in September and October 2007 are among the highest fluxes detected by a BL Lac object and considering the redshift of the source (z = 0.31) the total power transported in the jet during these episodes approaches or slightly exceeds the maximum power generated by a spinning black hole of 10^9 solar masses, challenging the Blandford-Znajek mechanism and confirming the extreme energetics during these flares. The modeling of the SEDs of S5 0716+714 indicated as, even if the broad band emission appears in agreement with the synchrotron self Compton (SSC) paradigm, a more complex model with two SSC components is needed to interpret our data. The case of S5 0716+714 is not unique among the BL Lac objects, also for the multifrequency observation of Mrk 421 and W Comae in June 2008 a one-zone SSC model seems to be a good representation of the broad band spectrum, but the observations collected during the multiwavelength campaigns seem to open to more complex interpretations of the data. Moreover, the dominant emission mechanism in the gamma-ray band for Flat Spectrum Radio Quasars (FSRQs) is the inverse Compton scattering of external photons from the broad line region, but in some particular states also the contribution of seed photons from a hot corona (3C 454.3 in December 2007) or the accretion disk (3C 279) are shown to be important. Therefore, from the modeling of the different SEDs of BL Lacs and FSRQs observed by AGILE seems to emerge that the SSC and the external Compton (EC) frameworks, respectively, are good approximation for describing on average the high activity states of the two flavours of blazars, but going into details of the single observation more complex scenarios sometimes are requested. The possibility to obtain information over the entire electromagnetic spectrum during the multifrequency campaigns organized by AGILE gave me also the opportunity to investigate in some blazars the presence of Seyfert-like features, such as the little and big blue bumps (PKS 1510-089) and the Compton reflection component (3C 273). Moreover, we revealed in the FSRQ PKS 1510-089 some features typical of High-frequency peaked BL Lac objects, such a X-ray harder-when-brighter behaviour during March 2008 and a shift of the synchrotron peak towards higher frequencies during the huge flare of March 2009. Emission in optical and gamma-ray bands seems to be correlated during high activity states of blazars, but not strongly, with a possible lag of the gamma-ray flux with respect to optical one less than one day, both for FSRQs (e.g. 3C 454.3) and BL Lacs (S5 0716+714). On the other hand, during March 2009 a possible delay of the optical emission with respect to the gamma-ray one is detected for PKS 1510-089, suggesting a more complex behaviour in the optical/gamma-ray correlation, especially for FSRQs, where also a contribution of the thermal disk emission is clearly visible.

Over-expression of phage HK022 Nun protein is toxic for Escherichia coli

PubMed Central

Uc-Mass, Augusto; Khodursky, Arkady; Brown, Lewis; Gottesman, Max E.

2008-01-01

The Nun protein of coliphage HK022 excludes superinfecting λ phage. Nun recognizes and binds to the N utilization (nut) sites on phage λ nascent RNA and induces transcription termination. Over-expression of Nun from a high-copy plasmid is toxic for E.coli, despite the fact that nut sites are not encoded in the E.coli genome. Cells expressing Nun cannot exit stationary phase. Toxicity is related to transcription termination, since host and nun mutations that block termination also suppress cell killing. Nun inhibits expression of wild-type lacZ, but not lacZ expressed from the Crp/cAMP–independent lacUV5 promoter. Microarray and proteomics analyses show Nun down-regulates crp and tnaA. Crp over-expression and high indole concentrations partially reverse Nun-mediated toxicity and restore lacZ expression. PMID:18571198

A-type Lamins Form Distinct Filamentous Networks with Differential Nuclear Pore Complex Associations.

PubMed

Xie, Wei; Chojnowski, Alexandre; Boudier, Thomas; Lim, John S Y; Ahmed, Sohail; Ser, Zheng; Stewart, Colin; Burke, Brian

2016-10-10

The nuclear lamina is a universal feature of metazoan nuclear envelopes (NEs) [1]. In mammalian cells, it appears as a 10-30 nm filamentous layer at the nuclear face of the inner nuclear membrane (INM) and is composed primarily of A- and B-type lamins, members of the intermediate filament family [2]. While providing structural integrity to the NE, the lamina also represents an important signaling and regulatory platform [3]. Two A-type lamin isoforms, lamins A and C (LaA and LaC), are expressed in most adult human cells. Encoded by a single gene, these proteins are largely identical, diverging only in their C-terminal tail domains. By contrast with that of LaC, the unique LaA tail undergoes extensive processing, including farnesylation and endo-proteolysis [4, 5]. However, functional differences between LaA and LaC are still unclear. Compounding this uncertainty, the structure of the lamina remains ill defined. In this study, we used BioID, an in vivo proximity-labeling method to identify differential interactors of A-type lamins [6]. One of these, Tpr, a nuclear pore complex (NPC) protein, is highlighted by its selective association with LaC. By employing superresolution microscopy, we demonstrate that this Tpr association is mirrored in enhanced interaction of LaC with NPCs. Further superresolution studies visualizing both endogenous A- and B-type lamins have allowed us to construct a nanometer-scale model of the mammalian nuclear lamina. Our data indicate that different A- and B-type lamin species assemble into separate filament networks that together form an extended composite structure at the nuclear periphery providing attachment sites for NPCs, thereby regulating their distribution. Copyright © 2016 Elsevier Ltd. All rights reserved.

A study of the properties of tablets from coprocessed dry binders composed of alpha-lactose monohydrate and different types of cellulose.

PubMed

Muzíková, J; Zvolánková, J

2007-12-01

The paper evaluates the differences between the properties of tablets from two coprocessed dry binders based on alpha-lactose monohydrate and cellulose, MicroceLac 100 and Cellactose 80. The substances differ in the type of contained cellulose; MicroceLac 100 contains 25% of microcrystalline cellulose, Cellactose 80, 25% of powdered cellulose. The properties under study included the tensile strength and disintegration time in dependence on compression force, addition of two concentrations of the lubricant sodium stearylfumarate (Pruv) and a 50% addition of the active ingredients ascorbic acid and acetylsalicylic acid. Using one of the compression forces, the effect of Pruv and magnesium stearate on the above-mentioned properties were compared. In the compression forces of 6 and 8 kN the strength of the compacts from pure Cellactose 80 was lower than that of those from MicroceLac 100 both without and with the lubricant. The lubricant sensitivity of dry binders depended on compression force. Pruv decreased the strength of compacts less than magnesium stearate. The tablets from Cellactose 80 possessed a longer disintegration time than those from MicroceLac 100, excepting the tableting materials containing 0.4 Pruv with a compression force of 6 kN. Disintegration time was prolonged with the use of sodium stearylfumarate and it was increased with compression force much more markedly in the case of Cellactose 80. In the presence of ascorbic acid, the strength of tablets was decreased in the case of both dry binders, but it was higher with MicroceLac100, disintegration time was very short and independent of the type of the dry binder. In the case of acetylsalicylic acid, the strength of tablets was higher with a lesser influence of the type of the dry binder, and disintegration time was longer and especially in the case of Cellactose 80 increased with increasing concentration of Pruv.

Seeing Red and Shooting Blanks: A Study of Red Quasars and Blank Field X-Ray Sources

NASA Technical Reports Server (NTRS)

Elvis, Martin; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

We have identified a population of 'blank field sources' (or 'blanks') among the ROSAT (Roentgen Satellite) bright unidentified X-ray sources with faint optical counterparts. The extreme X-ray over optical flux ratio of blank field sources is not compatible with the main classes of X-ray emitters except for extreme BL Lacertae objects at fx/fv is equal to or less than 35. From the analysis of ROSAT archival data we found evidence for only three sources, out of 16, needing absorption in excess of the Galactic value and no indication of variability. We also found evidence for an extended nature for only one of the five blanks with a serendipitous HRI (High Resolution Imager) detection; this source (1WGA J1226.9+3332) was confirmed as a z=0.89 cluster of galaxies. Palomar images reveal the presence of a red (O - E is equal to or greater than 2) counterpart in the X-ray error circle for six blanks. The identification process brought to the discovery of another high z cluster of galaxies, one (possibly extreme) BL Lac and two apparently normal type 1 AGNs (Active Galactic Nuclei). These AGNs, together with four more AGN-like objects seem to form a well defined group: they present type 1 X-ray spectra but red Palomar counterparts. We discuss the possible explanations for the discrepancy between the X-ray and optical data, among which: a suppressed big blue bump emission, an extreme dust to gas (approximately 40 - 60 the Galactic ratio) ratio value and a high redshift (z is greater than or equal to 3.5) QSO (Quasi-Stellar Object) nature. These AGN-like blanks seem to be the bright (and easier to study) analogs of the sources which are being found in deep Chandra observations. Five more blanks have a still an unknown nature.

Science with the ASTRI mini-array for the Cherenkov Telescope Array: blazars and fundamental physics

NASA Astrophysics Data System (ADS)

Bonnoli, Giacomo; Tavecchio, Fabrizio; Giuliani, Andrea; Bigongiari, Ciro; Di Pierro, Federico; Stamerra, Antonio; Pareschi, Giovanni; Vercellone, Stefano; ASTRI Collaboration; CTA Consortium

2016-05-01

ASTRI (“Astronomia a Specchi con Tecnologia Replicante Italiana”) is a flagship project of the Italian Ministry of Research (MIUR), devoted to the realization, operation and scientific validation of an end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array (CTA). The ASTRI SST-2M telescope prototype is characterized by a dual mirror, Schwarzschild-Couder optical design and a compact camera based on silicon photo-multipliers. It will be sensitive to multi-TeV very high energy (VHE) gamma rays up to 100 TeV, with a PSF ~ 6’ and a wide (9.6°) unaberrated optical field of view. Right after validation of the design in single-dish observations at the Serra La Nave site (Sicily, Italy) during 2015, the ASTRI collaboration will be able to start deployment, at the final CTA southern site, of the ASTRI mini-array, proposed to constitute the very first CTA precursor. Counting 9 ASTRI SST-2M telescopes, the ASTRI mini-array will overtake current IACT systems in differential sensitivity above 5 TeV, thus allowing unprecedented observations of known and predicted bright TeV emitters in this band, including some extragalactic sources such as extreme high-peaked BL Lacs with hard spectra. We exploited the ASTRI scientific simulator ASTRIsim in order to understand the feasibility of observations tackling blazar and cosmic ray physics, including discrimination of hadronic and leptonic scenarios for the VHE emission from BL Lac relativistic jets and indirect measurements of the intergalactic magnetic field and of the extragalactic background light. We selected favorable targets, outlining observation modes, exposure times, multi-wavelength coverage needed and the results expected. Moreover, the perspectives for observation of effects due to the existence of axion-like particles or to Lorentz invariance violations have been investigated.

Near-infrared and gamma-ray monitoring of TANAMI gamma-ray bright sources

DOE PAGES

Nesci, R.; Tosti, G.; Pursimo, T.; ...

2013-06-18

Context. We present that spectral energy distribution and its variability are basic tools for understanding the physical processes operating in active galactic nuclei (AGN). Aims. In this paper we report the results of a one-year near-infrared (NIR) and optical monitoring of a sample of 22 AGN known to be gamma-ray emitters, aimed at discovering correlations between optical and gamma-ray emission. Methods. We observed our objects with the Rapid Eye Mount (REM) telescope in J,H,K, and R bands nearly twice every month during their visibility window and derived light curves and spectral indexes. We also analyzed the gamma-ray data from themore » Fermi gamma-ray Space Telescope, making weekly averages. Results. Six sources were never detected during our monitoring, proving to be fainter than their historical Two micron all sky survey (2MASS) level. All of the sixteen detected sources showed marked flux density variability, while the spectral indexes remained unchanged within our sensitivity limits. Steeper sources showed, on average, a larger variability. From the NIR light curves we also computed a variability speed index for each detected source. Only one source (PKS 0208-512) underwent an NIR flare during our monitoring. Half of the sources showed a regular flux density trend on a one-year time scale, but do not show any other peculiar characteristic. The broadband spectral index α ro appears to be a good proxy of the NIR spectral index only for BL Lac objects. No clear correlation between NIR and gamma-ray data is evident in our data, save for PKS 0537-441, PKS 0521-360, PKS 2155-304, and PKS 1424-418. In conclusion, the gamma-ray/NIR flux ratio showed a large spread, QSO being generally gamma-louder than BL Lac, with a marked correlation with the estimated peak frequency (ν peak) of the synchrotron emission.« less

Gamma-Ray Light Curves And Variability Of Bright Fermi -Detected Blazars

DOE PAGES

Abdo, A. A.

2010-09-22

This paper presents light curves as well as the first systematic characterization of variability of the 106 objects in the high-confidence Fermi Large Area Telescope Bright AGN Sample (LBAS). Weekly light curves of this sample, obtained during the first 11 months of the Fermi survey (2008 August 4-2009 July 4), are tested for variability and their properties are quantified through autocorrelation function and structure function analysis. For the brightest sources, 3 or 4 day binned light curves are extracted in order to determine power density spectra (PDSs) and to fit the temporal structure of major flares. More than 50% ofmore » the sources are found to be variable with high significance, where high states do not exceed 1/4 of the total observation range. Variation amplitudes are larger for flat spectrum radio quasars and low/intermediate synchrotron frequency peaked BL Lac objects. Autocorrelation timescales derived from weekly light curves vary from four to a dozen of weeks. Variable sources of the sample have weekly and 3-4 day bin light curves that can be described by 1/f α PDS, and show two kinds of gamma-ray variability: (1) rather constant baseline with sporadic flaring activity characterized by flatter PDS slopes resembling flickering and red noise with occasional intermittence and (2)—measured for a few blazars showing strong activity—complex and structured temporal profiles characterized by long-term memory and steeper PDS slopes, reflecting a random walk underlying mechanism. The average slope of the PDS of the brightest 22 FSRQs and of the 6 brightest BL Lacs is 1.5 and 1.7, respectively. The study of temporal profiles of well-resolved flares observed in the 10 brightest LBAS sources shows that they generally have symmetric profiles and that their total duration vary between 10 and 100 days. Results presented here can assist in source class recognition for unidentified sources and can serve as reference for more detailed analysis of the brightest gamma-ray blazars.« less

Distributions of Gamma-Ray Bursts and Blazars in the L p-E p-Plane and Possible Implications for their Radiation Physics

NASA Astrophysics Data System (ADS)

Lyu, Fen; Liang, En-Wei; Liang, Yun-Feng; Wu, Xue-Feng; Zhang, Jin; Sun, Xiao-Na; Lu, Rui-Jing; Zhang, Bing

2014-09-01

We present a spectral analysis for a sample of redshift-known gamma-ray bursts (GRBs) observed with Fermi/GBM. Together with the results derived from our systematical spectral energy distribution modeling with the leptonic models for a Fermi/LAT blazar sample, we compare the distributions of the GRBs and the blazars by plotting the synchrotron peak luminosity (L s) and the corresponding peak photon energy E s of blazars in the L p-E p-plane of GRBs, where L p and E p are the peak luminosity and peak photon energy of the GRB time-integrated νf ν spectrum, respectively. The GRBs are in the high-L p, high-E p corner of the plane and a tight L p-E p relation is found, i.e., L_p\\propto E_p2.13^{+0.54-0.46}. Both flat spectrum radio quasars (FSRQs) and low-synchrotron peaking BL Lac objects (LBLs) are clustered in the low-E p, low-L p corner. Intermediate- and high-synchrotron peaking BL Lac objects (IBLs and HBLs) have E s ~ 2 × 10-3-102 keV and L s ~ 1044-1047 erg s-1, but no dependence of L s on E s is found. We show that the tight Lp -Ep relation of GRBs is potentially explained with the synchrotron radiation of fast-cooling electrons in a highly magnetized ejecta, and the weak anti-correlation of L s-E s for FSRQs and LBLs may be attributed to synchrotron radiation of slow-cooling electrons in a moderately magnetized ejecta. The distributions of IBLs and HBLs in the L p-E p-plane may be interpreted with synchrotron radiation of fast-cooling electrons in a matter-dominated ejecta. These results may present a unified picture for the radiation physics of relativistic jets in GRBs and blazars within the framework of the leptonic synchrotron radiation models.

MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524

DOE PAGES

Aleksi , J.; Ansoldi, S.; Antonelli, L. A.; ...

2015-05-29

The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) γ-rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. In this paper, we analysed multiwavelength observations from γ-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a γ-ray signal above 250 GeV of (3.7more » ± 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9σ. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE γ-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 ± 0.29 between ~150 GeV and 1 TeV and an integral flux of (9.3 ± 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. Lastly, the broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected.« less

PKS 2005-489 at VHE: four years of monitoring with HESS and simultaneous multi-wavelength observations

NASA Astrophysics Data System (ADS)

H.E.S.S. Collaboration; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Benbow, W.; Bernlöhr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Costamante, L.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göring, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Keogh, D.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Marandon, V.; Martineau-Huynh, O.; Marcowith, A.; Masbou, J.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Oña Wilhelmi, E.; Orford, K. J.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Renaud, M.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J. L.; Sol, H.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Superina, G.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.

2010-02-01

Aims: Our aim is to study the very high energy (VHE; E>100 GeV) γ-ray emission from BL Lac objects and the evolution in time of their broad-band spectral energy distribution (SED). Methods: VHE observations of the high-frequency peaked BL Lac object PKS 2005-489 were made with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Three simultaneous multi-wavelength campaigns at lower energies were performed during the HESS data taking, consisting of several individual pointings with the XMM-Newton and RXTE satellites. Results: A strong VHE signal, ~17σ total, from PKS 2005-489 was detected during the four years of HESS observations (90.3 h live time). The integral flux above the average analysis threshold of 400 GeV is ~3% of the flux observed from the Crab Nebula and varies weakly on time scales from days to years. The average VHE spectrum measured from ~300 GeV to ~5 TeV is characterized by a power law with a photon index, Γ = 3.20± 0.16_stat± 0.10_syst. At X-ray energies the flux is observed to vary by more than an order of magnitude between 2004 and 2005. Strong changes in the X-ray spectrum (ΔΓX ≈ 0.7) are also observed, which appear to be mirrored in the VHE band. Conclusions: The SED of PKS 2005-489, constructed for the first time with contemporaneous data on both humps, shows significant evolution. The large flux variations in the X-ray band, coupled with weak or no variations in the VHE band and a similar spectral behavior, suggest the emergence of a new, separate, harder emission component in September 2005. Supported by CAPES Foundation, Ministry of Education of Brazil.Now at Harvard-Smithsonian Center for Astrophysics, Cambridge, USA.Now at W.W. Hansen Experimental Physics Laboratory & Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, USA.

VERITAS Observations of the BL Lac Object PG 1553+113

NASA Astrophysics Data System (ADS)

Aliu, E.; Archer, A.; Aune, T.; Barnacka, A.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gillanders, G. H.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Håkansson, N.; Hanna, D.; Holder, J.; Hughes, G.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Kumar, S.; Lang, M. J.; Madhavan, A.; McArthur, S.; McCann, A.; Meagher, K.; Millis, J.; Moriarty, P.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Orr, M.; Otte, A. N.; Park, N.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Pueschel, E.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sembroski, G. H.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vassiliev, V. V.; Wakely, S. P.; Weinstein, A.; Welsing, R.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

2015-01-01

We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 ± 0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 ± 0.06) × 10-11 photons cm-2 s-1, corresponding to 6.9% of the Crab Nebula flux. We also present the combined γ-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV. The data are well fit by a power law with an exponential cutoff at 101.9 ± 3.2 GeV. The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the γ-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z > 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z <= 0.62. A strongly elevated mean flux of (2.50 ± 0.14) × 10-11 photons cm-2 s-1 (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44 +/- 0.71) × 10-11 {photons} {cm}-2 {s}-1 (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a χ2 probability for a steady flux of 0.03%.

Coarse-grained Simulations of Sugar Transport and Conformational Changes of Lactose Permease

NASA Astrophysics Data System (ADS)

Liu, Jin; Jewel, S. M. Yead; Dutta, Prashanta

2016-11-01

Escherichia coli lactose permease (LacY) actively transports lactose and other galactosides across cell membranes through lactose/H+ symport process. Lactose/H+ symport is a highly complex process that involves sugar translocation, H+ transfer, as well as large-scale protein conformational changes. The complete picture of lactose/H+ symport is largely unclear due to the complexity and multiscale nature of the process. In this work, we develop the force field for sugar molecules compatible with PACE, a hybrid and coarse-grained force field that couples the united-atom protein models with the coarse-grained MARTINI water/lipid. After validation, we implement the new force field to investigate the transport of a β-D-galactopyranosyl-1-thio- β-D-galactopyranoside (TDG) molecule across a wild-type LacY during lactose/H+ symport process. Results show that the local interactions between TDG and LacY at the binding pocket are consistent with the X-ray experiment. Protonation of Glu325 stabilizes the TDG and inward-facing conformation of LacY. Protonation of Glu269 induces a dramatic protein structural reorganization and causes the expulsion of TDG from LacY to both sides of the membrane. The structural changes occur primarily in the N-terminal domain of LacY. This work is supported by NSF Grants: CBET-1250107 and CBET -1604211.

[Effect of Transcutaneous Acupoint Electrical Stimulation on Hemodynamic Fluctuation Caused by Loosing Tourniquet in Elderly Patients Undergoing Knee Joint Replacement].

PubMed

Liang, Han-Sheng; Feng, Yi

2017-12-25

To observe the effect of transcutaneous acupoint electrical stimulation (TAES) on hemodynamic fluctuation caused by loosing tourniquet in the elderly patients undergoing knee joint replacement. A total of 60 ASA (America Society Anesthesiologist) I or II elderly patients for elective knee joint replacement surgery were randomly divided into control group (30 cases) and TAES group (30 cases). Patients of both groups were treated by intravenous anesthesia, and monitored with bispectral index (BIS, between 45－60) for anesthesia depth, stroke volume variation (SVV) for fluid management, mean arterial pressure (MAP) and cardiac index (CI) for hemodynamic fluctuation evaluation, and with analgesia nociception index (ANI, between 50－70) for remifentanil dosage adjustment. TAES (2 Hz/100 Hz, 8－20 mA) was applied to bilateral Xinshu (BL 15), Feishu (BL 13), Neiguan (PC 6) and Hegu (LI 4) acupoints for 30 min first (followed by anesthesia induction and operation), and given continuously until 15 min after tourniquet loosing. Patients of the control group were only given with electrodes attachment without electrical stimulation. The levels of MAP, CI, and arterial blood pH, PaCO 2 , PaO 2 , base excess (BE) and lactic acid (Lac) 1 min before, and 5 and 15 min after tourniquet loosing, and the dosages of remifentanil and ephedrine after tourniquet loosing were recorded. The changed levels of MAP, CI and blood Lac at 5 min after tourniquet loosing (relevant to the baseline levels), and blood Lac content at 15 min after tourniquet loosing (relevant to 5 min after tourniquet loosing) were significantly lower in the TAES group than in the control group ( P <0.05), but the levels of MAP and CI at 15 min after tourniquet loosing (relevant to 5 min following tourniquet loosing) were significantly higher in the TAES group than in the control group ( P <0.05), suggesting an improvement of blood pressure, cardiac function and substance metabolism after TAES. Moreover, the dosages of remifentanil and ephedrine after tourniquet loosing were considerably lower in the TAES group than in the control group ( P <0.05), suggesting a better stabilization of hemodynamics after TAES. No significant differences were found between the two groups in the levels of blood pH, PaCO 2 , PaO 2 and BE at 5 and 15 min after tourniquet loosing ( P >0.05). TAES has a positive effect on hemodynamics fluctuation caused by loosing tourniquet in the aged patients undergoing knee joint replacement.

Period Variations of the Eclipsing Binary Systems T LMi and VX Lac

NASA Astrophysics Data System (ADS)

Yılmaz, M.; İzci, D. D.; Gümüş, D.; Özavci, İ.; Selam, S. O.

2015-07-01

We present a period analysis of the two Algol-type eclipsing binary systems T LMi and VX Lac using all available times of minimum in the literature, as well as new minima obtained at the Ankara University Kreiken Observatory. The period analysis of T LMi suggests mass transfer between the components and also a third body that is dynamically bound to the binary system. The analysis of VX Lac also suggests mass transfer between the components, and the presence of a third and a fourth body under the assumption of a Light-Time Effect. In addition, the periodic variation of VX Lac was examined under the hypothesis of magnetic activity, and the corresponding parameters were derived. We report here the orbital parameters for both systems, along with the ones related to mass transfer, and those for the third and fourth bodies.

The mutY gene: a mutator locus in Escherichia coli that generates G.C----T.A transversions.

PubMed Central

Nghiem, Y; Cabrera, M; Cupples, C G; Miller, J H

1988-01-01

We have used a strain with an altered lacZ gene, which reverts to wild type via only certain transversions, to detect transversion-specific mutators in Escherichia coli. Detection relied on a papillation technique that uses a combination of beta-galactosides to reveal blue Lac+ papillae. One class of mutators is specific for the G.C----T.A transversion as determined by the reversion pattern of a set of lacZ mutations and by the distribution of forward nonsense mutations in the lacI gene. The locus responsible for the mutator phenotype is designated mutY and maps near 64 min on the genetic map of E. coli. The mutY locus may act in a similar but reciprocal fashion to the previously characterized mutT locus, which results in A.T----C.G transversions. Images PMID:3128795

Effects of young barley leaf extract and antioxidative vitamins on LDL oxidation and free radical scavenging activities in type 2 diabetes.

PubMed

Yu, Y-M; Chang, W-C; Chang, C-T; Hsieh, C-L; Tsai, C E

2002-04-01

The effects of supplementation of young barley leaf extract (BL) and/or antioxidative vitamins C and E on different low-density lipoprotein (LDL) subfractions susceptibility to oxidation and free radical scavenging activities in patients with type 2 diabetes were evaluated. Thirty-six type 2 diabetic patients were enrolled in this study. The subjects received one of the following supplements daily for 4 weeks: 15 g BL, 200 mg vitamin C and 200 mg vitamin E (CE), or BL plus CE (BL + CE). The lucigenin-chemiluminescence (CL) and luminol-CL levels in blood were significantly reduced in all groups. Vitamin E content of LDL subfractions increased significantly following supplements, especially for BL + CE group. The percent increase of lag times in the BL + CE was significantly higher than those in the BL or CE group. The antioxidative effect of BL + CE was the greatest for small, dense LDL (Sd-LDL) with further increases in percentage of lag times 4 folds compared to BL alone. Our results indicate that supplementation with BL may help to scavenge oxygen free radicals, save the LDL-vitamin E content, and inhibit LDL oxidation. Furthermore, the addition of vitamins C and E to BL can inhibit the Sd-LDL oxidation more effectively, which may protect against vascular diseases in type 2 diabetic patients.

The effects of Eph-ephrin mutations on pre-pulse inhibition in mice.

PubMed

Liuzzo, Andrea; Gray, Lincoln; Wallace, Matthew; Gabriele, Mark

2014-08-01

Eph-ephrin signaling is known to be important in directing topographic projections in the afferent auditory pathway, including connections to various subdivisions of the inferior colliculus (IC). The acoustic startle-response (ASR) is a reliable reflexive behavioral response in mammals elicited by an unexpected intense acoustic startle-eliciting stimulus (ES). It is mediated by a sub-cortical pathway that includes the IC. The ASR amplitude can be measured with an accelerometer under the subject and can be decreased in amplitude by presenting a less intense, non-startling stimulus 5-300ms before the ES. This reflexive decrement in ASR is called pre-pulse inhibition (PPI) and indicates that the relatively soft pre-pulse was heard. PPI is a general trait among mammals. Mice have been used recently to study this response and to reveal how genetic mutations affect neural circuits and hence the ASR and PPI. In this experiment, we measured the effect of Eph-ephrin mutations using control mice (C57BL/6J), mice with compromised EphA4 signaling (EphA4(lacZ/+), EphA4(lacZ/lacZ)), and knockout ephrin-B3 mice (ephrin-B3 (+/-, -/-)). Control and EphA4(lacZ/+s)trains showed robust PPI (up to 75% decrement in ASR) to an offset of a 70dB SPL background noise at 50ms before the ES. Ephrin-B3 knockout mice and EphA4 homozygous mutants were only marginally significant in PPI (<25% decrement and <33% decrement, respectively) to the same conditions. This decrement in PPI highlights the importance of ephrin-B3 and EphA4 interactions in ordering auditory behavioral circuits. Thus, different mutations in certain members of the signaling family produce a full range of changes in PPI, from minimal to nearly maximal. This technique can be easily adapted to study other aspects of hearing in a wider range of mutations. Along with ongoing neuroanatomical studies, this allows careful quantification of how the auditory anatomical, physiological and now behavioral phenotype is affected by changes in Eph-ephrin expression and functionality. Copyright © 2014 Elsevier Inc. All rights reserved.

Biosynthesis of the carbohydrate antigenic determinants, Globo H, blood group H, and Lewis b: a role for prostate cancer cell alpha1,2-L-fucosyltransferase.

PubMed

Chandrasekaran, E V; Chawda, Ram; Locke, Robert D; Piskorz, Conrad F; Matta, Khushi L

2002-03-01

Prostate carcinoma LNCaP cells were unique among several human cancer cell lines which include two other prostate cancer cell lines, PC-3 and DU-145, in expressing alpha1,2-L-fucosyltransferase (FT) as an exclusive FT activity. Affinity gel-GDP and Sephacryl S100 HR columns were used for a partial purification of this enzyme from 3.9 x 10(9) LNCaP cells (approximately 200-fold; 40% yield). The K(m) value (2.7 mM) for the LacNAc type 2 acceptor was quite similar to the one reported for the cloned blood group H gene-specified alpha1,2-FT [Chandrasekaran et al. (1996) Biochemistry 35, 8914-8924]. N-Ethylmaleimide was a potent inhibitor (K(i ) 12.5 microM). The enzyme showed four-fold acceptor preference for the LacNAc type 2 unit in comparison to the T-hapten in mucin core 2 structure. Its main features were similar to those of the cloned enzyme: (1) C-6 sulfation of terminal Gal in the LacNAc unit increased the acceptor efficiency, whereas C-6 sialylation abolished acceptor ability; (2) C-6 sulfation of GlcNAc in LacNAc type 2 decreased by 80% the acceptor ability, whereas LacNAc type 1 was unaffected; (3) Lewis x did not serve as an acceptor; (4) the C-4 hydroxyl rather than the C-6 hydroxyl group of the GlcNAc moiety in LacNAc type1 was essential for activity; and (5) the acrylamide copolymer of Galbeta1,3GlcNAcbeta-O-Al was the best acceptor among the acrylamide copolymers. Additionally, highly significant biological features of alpha1,2FT were identified in the present study. The synthesis of Globo H and Lewis b determinants became evident from the fact that Galbeta1,3GalNAcbeta1,3Galalpha-O-Me and Galbeta1,3(Fucalpha1,4)Glc-NAcbeta1,3Galbeta-O-Me served as high-affinity acceptors for this enzyme. Further, D-Fucbeta1,3Gal-NAcbeta1,3Galalpha-O-Me was a very efficient acceptor, indicating that the C-6 hydroxyl group of the terminal Gal moiety in Globo H is not essential for the enzyme activity. Thus, the present study was able to demonstrate three different catalytic roles of LNCaP alpha1,2-FT, namely, the expressions of blood group H, Lewis b from Lewis a, and Globo H.

Generation of complete source samples from the Slew Survey

NASA Technical Reports Server (NTRS)

Schachter, Jonathan

1992-01-01

The Einstein Slew Survey consists of 819 bright X-ray sources, of which 636 (or 78 percent) are identified with counterparts in standard catalogs. We argue for the importance of bright X-ray surveys, and compare the slew results to the ROSAT all-sky survey. Also, we discuss statistical techniques for minimizing confusion in arcminute error circles in digitized data. We describe the 238 Slew Survey AGN, clusters, and BL Lac objects identified to date and their implications for logN-logS and source evolution studies. Also given is a catalog of 1075 sources detected in the Einstein Imaging Proportional Counter (IPC) Slew Survey of the X-ray sky. Five hundred fifty-four of these sources were not previously known as X-ray sources.

Blazars in Hard X-rays

NASA Astrophysics Data System (ADS)

Ghisellini, Gabriele

2009-05-01

Although blazars are thought to emit most of their luminosity in the γ-ray band, there are subclasses of them very prominent in hard X-rays. These are the best candidates to be studied by Simbol-X. They are at the extremes of the blazar sequence, having very small or very high jet powers. The former are the class of TeV emitting BL Lacs, whose synchrotron emission often peaks at tens of keV or more. The latter are the blazars with the most powerful jets, have high black hole masses accreting at high (i.e. close to Eddington) rates. These sources are predicted to have their high energy peak even below the MeV band, and therefore are very promising candidates to be studied with Simbol-X.

Evidence for a QPO structure in the TeV and X-ray light curve during the 1997 high state γ emission of Mkn 501

NASA Astrophysics Data System (ADS)

Kranich, D.

1999-08-01

The BL Lac Object Mkn 501 was in a state of high activity in the TeV range in 1997. During this time Mkn 501 was observed by all Cherenkov-Telescopes of the HEGRA-Collaboration. Part of the data were also taken during moonshine thus providing a nearly continuous coverage for this object in the TeV-range. We have carried out a QPO analysis and found evidence for a 23 day periodicity. We applied the same analysis on the 'data by dwell' x-ray lightcurve from the RXTE/ASM database and found also evidence for the 23 day periodicity. The combined probability was -.

A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30

DOE PAGES

Abeysekara, A. U.; Archambault, S.; Archer, A.; ...

2017-02-21

We report that B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale ofmore » $$\\lt 3.6\\,\\mathrm{hr}$$. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. Lastly, when interpreted in the framework of a one-zone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor $$\\delta \\gt 10$$, and an electron population with spectral index $$p\\lt 2.3$$.« less

Discovery of a new TeV gamma-ray source: VER J0521+211

DOE PAGES

Archambault, S.; Arlen, T.; Aune, T.; ...

2013-09-27

Here, we report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 ± 0.13 stat ± 0.78 sys) × 10 –11 cm –2 s –1 above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, frommore » optical to TeV, with a peak flux corresponding to ~0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.« less

Enhanced expression of cro-beta-galactosidase fusion proteins under the control of the PR promoter of bacteriophage lambda.

PubMed Central

Zabeau, M; Stanley, K K

1982-01-01

Hybrid plasmids carrying cro-lacZ gene fusions have been constructed by joining DNA segments carrying the PR promoter and the start of the cro gene of bacteriophage lambda to the lacZ gene fragment carried by plasmid pLG400 . Plasmids in which the translational reading frames of the cro and lacZ genes are joined in-register (type I) direct the synthesis of elevated levels of cro-beta-galactosidase fusion protein amounting to 30% of the total cellular protein, while plasmids in which the genes are fused out-of-register (type II) produce a low level of beta-galactosidase protein. Sequence rearrangements downstream of the cro initiator AUG were found to influence the efficiency of translation, and have been correlated with alterations in the RNA secondary structure of the ribosome-binding site. Plasmids which direct the synthesis of high levels of beta-galactosidase are conditionally lethal and can only be propagated when the PR promoter is repressed. Deletion of sequences downstream of the lacZ gene restored viability, indicating that this region of the plasmid encodes a function which inhibits the growth of the cells. The different applications of these plasmids for expression of cloned genes are discussed. Images Fig. 6. PMID:6327257

Probing the EBL Evolution at High Redshift Using GRBs Detected with the Fermi-LAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, A.; Ajello, M.; Omodei, N.

The extragalactic background light (EBL), from ultraviolet to infrared wavelengths, is predominantly due to emission from stars, accreting black holes and reprocessed light due to Galactic dust. The EBL can be studied through the imprint it leaves, via γ–γ absorption of high-energy photons, in the spectra of distant γ-ray sources. The EBL has been probed through the search for the attenuation it produces in the spectra of BL Lacertae (BL Lac) objects and individual γ-ray bursts (GRBs). GRBs have significant advantages over blazars for the study of the EBL especially at high redshifts. Here we analyze a combined sample ofmore » 22 GRBs, detected by the Fermi Large Area Telescope between 65 MeV and 500 GeV. We report a marginal detection (at the ~2.8σ level) of the EBL attenuation in the stacked spectra of the source sample. This measurement represents a first constraint of the EBL at an effective redshift of ~1.8. Here, we combine our results with prior EBL constraints and conclude that Fermi-LAT is instrumental to constrain the UV component of the EBL. We discuss the implications on existing empirical models of EBL evolution.« less

Studies of BL Lacertae objects with the Einstein Observatory - The soft X-ray spectra of OJ 287 and PKS 0735+178

NASA Technical Reports Server (NTRS)

Madejski, Greg M.; Schwartz, Daniel A.

1988-01-01

Accurate, soft X-ray spectra of two BL Lac objects, OJ 287 and PKS 0735+178, are presented. The X-ray spectra are well described by a power-law model with a low-energy cutoff consistent with photoelectric absorption within the Galaxy. The best-fit values of the energy spectral index in the 0.2-4.0 keV band are 0.91 and 0.76 respectively. The X-ray flux from OJ 287 is variable by a ratio of three from low to high state; PKS 0735+178 shows no indication of X-ray variability. The X-ray emission in OJ 287 is interpreted to be due to the synchrotron process from a volume common with either a beamed radio component or a stationary optical component. In PKS 0735+178, where the X-ray emission is most likely due to the Compton process operating in one of the VLBI radio components. The synchrotron self-Compton process with modest kinematic Doppler factors predicts the measured X-ray flux from PKS 0735+178 and lower than the measured flux in OJ 287.

PKS 2155-304 relativistically beamed synchrotron radiation from BL LAC object

NASA Technical Reports Server (NTRS)

Urry, C. M.; Mushotzky, R. F.

1981-01-01

The newly discovered BL Lacertae object, PKS 2155-304, was observed with the medium and high intensity energy detectors of the HEAO-1 A2 experiment. The variability by a factor of two in less than a day reported by Snyder, et al (1979) is confirmed. Two spectra, obtained a year apart, while the satellite was in scanning mode, are well fit by simple power laws with energy spectral index alpha sub 1 equals approximately 1.4. A third spectrum, of higher statistical quality, obtained while the satellite was pointed at its source, has has two components. An acceptable fit was obtained using a two power law model, with indices alpha sub 1 equals 2.0 (+1.2, -0.6) and alpha sub 2 equals -1.5 (+1.5, -2.3). An interpretation of the overall spectrum from radio through X-rays in terms of a synchrotron self-Compton model gives a good description of the data if allowance is made for relativistic beaming. Thus, from a consideration of the spectrum, combined with an estimate of the size of the source, the presence of jets is inferred without their observation.

Probing the EBL Evolution at High Redshift Using GRBs Detected with the Fermi-LAT

DOE PAGES

Desai, A.; Ajello, M.; Omodei, N.; ...

2017-11-17

The extragalactic background light (EBL), from ultraviolet to infrared wavelengths, is predominantly due to emission from stars, accreting black holes and reprocessed light due to Galactic dust. The EBL can be studied through the imprint it leaves, via γ–γ absorption of high-energy photons, in the spectra of distant γ-ray sources. The EBL has been probed through the search for the attenuation it produces in the spectra of BL Lacertae (BL Lac) objects and individual γ-ray bursts (GRBs). GRBs have significant advantages over blazars for the study of the EBL especially at high redshifts. Here we analyze a combined sample ofmore » 22 GRBs, detected by the Fermi Large Area Telescope between 65 MeV and 500 GeV. We report a marginal detection (at the ~2.8σ level) of the EBL attenuation in the stacked spectra of the source sample. This measurement represents a first constraint of the EBL at an effective redshift of ~1.8. Here, we combine our results with prior EBL constraints and conclude that Fermi-LAT is instrumental to constrain the UV component of the EBL. We discuss the implications on existing empirical models of EBL evolution.« less

Isolating LacZ-expressing cells from mouse inner ear tissues using flow cytometry.

PubMed

Jan, Taha A; Chai, Renjie; Sayyid, Zahra N; Cheng, Alan G

2011-12-23

Isolation of specific cell types allows one to analyze rare cell populations such as stem/progenitor cells. Such an approach to studying inner ear tissues presents a unique challenge because of the paucity of cells of interest and few transgenic reporter mouse models. Here, we describe a protocol using fluorescence-conjugated probes to selectively label LacZ-positive cells from the neonatal cochleae. The most common underlying pathology of sensorineural hearing loss is the irreversible damage and loss of cochlear sensory hair cells, which are required to transduce sound waves to neural impulses. Recent evidence suggests that the murine auditory and vestibular organs harbor stem/progenitor cells that may have regenerative potential. These findings warrant further investigation, including identifying specific cell types with stem/progenitor cell characteristics. The Wnt signaling pathway has been demonstrated to play a critical role in maintaining stem/progenitor cell populations in several organ systems. We have recently identified Wnt-responsive Axin2-expressing cells in the neonatal cochlea, but their function is largely unknown. To better understand the behavior of these Wnt-responsive cells in vitro, we have developed a method of isolating Axin2-expressing cells from cochleae of Axin2-LacZ reporter mice. Using flow cytometry to isolate Axin2-LacZ positive cells from the neonatal cochleae, we could in turn execute a variety of experiments on live cells to interrogate their behavior as stem/progenitor cells. Here, we describe in detail the steps for the microdissection of neonatal cochlea, dissociation of these tissues, labeling of the LacZ-positive cells using a fluorogenic substrate, and cell sorting. Techniques for dissociating cochleae into single cells and isolating cochlear cells via flow cytometry have been described. We have made modifications to these techniques to establish a novel protocol to isolate LacZ-expressing cells from the neonatal cochlea.

LacR Is a Repressor of lacABCD and LacT Is an Activator of lacTFEG, Constituting the lac Gene Cluster in Streptococcus pneumoniae

PubMed Central

Afzal, Muhammad; Shafeeq, Sulman

2014-01-01

Comparison of the transcriptome of Streptococcus pneumoniae strain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose revealed the elevated expression of various genes and operons, including the lac gene cluster, which is organized into two operons, i.e., lac operon I (lacABCD) and lac operon II (lacTFEG). Deletion of the DeoR family transcriptional regulator lacR that is present downstream of the lac gene cluster revealed elevated expression of lac operon I even in the absence of lactose. This suggests a function of LacR as a transcriptional repressor of lac operon I, which encodes enzymes involved in the phosphorylated tagatose pathway in the absence of lactose or galactose. Deletion of lacR did not affect the expression of lac operon II, which encodes a lactose-specific phosphotransferase. This finding was further confirmed by β-galactosidase assays with PlacA-lacZ and PlacT-lacZ in the presence of either lactose or glucose as the sole carbon source in the medium. This suggests the involvement of another transcriptional regulator in the regulation of lac operon II, which is the BglG-family transcriptional antiterminator LacT. We demonstrate the role of LacT as a transcriptional activator of lac operon II in the presence of lactose and CcpA-independent regulation of the lac gene cluster in S. pneumoniae. PMID:24951784

Measurement and properties of the dose-area product ratio in external small-beam radiotherapy.

PubMed

Niemelä, Jarkko; Partanen, Mari; Ojala, Jarkko; Sipilä, Petri; Björkqvist, Mikko; Kapanen, Mika; Keyriläinen, Jani

2017-06-21

In small-beam radiation therapy (RT) the measurement of the beam quality parameter, i.e. the tissue-phantom ratio or TPR 20,10 , using a conventional point detector is a challenge. To obtain reliable results, one has to consider potential sources of error, including volume averaging and adjustment of the point detector into the narrow beam. To overcome these challenges, a different type of beam quality parameter in small beams was studied, namely the dose-area product ratio, or DAPR 20,10 . With this method, the measurement of a dose-area product (DAP) using a large-area plane-parallel chamber (LAC) eliminates the uncertainties in detector positioning and volume averaging that are present when using a point detector. In this study, the properties of the DAPR 20,10 of a cone-collimated 6 MV photon beam were investigated using Monte Carlo (MC) calculations and the obtained values were compared to measurements obtained using two LAC detectors, PTW Type 34073 and PTW Type 34070. In addition, the possibility of determining the DAP using EBT3 film and a Razor diode detector was studied. The determination of the DAPR 20,10 value was found to be feasible in external small-beam radiotherapy using cone-collimated beams with diameters from 4-40 mm, based on the results of the two LACs, the MC calculations and the Razor diode. The measurements indicated a constant DAPR 20,10 value for fields 20-40 mm in diameter, with a maximum relative change of 0.6%, but an increase of 7.0% for fields from 20-4 mm in diameter for the PTW Type 34070 chamber. Simulations and measurements showed an increase of DAPR 20,10 with increasing LAC size or dose integral area for the studied 4-40 mm cone-collimated 6 MV photon beams. This has the consequence that there should be a reference to the size of the used LAC active area or the DAP integration area with the reported DAPR 20,10 value.

Deep Eutectic Solvents (DESs) for the Isolation of Willow Lignin (Salix matsudana cv. Zhuliu)

PubMed Central

Li, Tengfei; Liu, Yu; Lou, Rui; Yang, Guihua; Chen, Jiachuan; Saeed, Haroon A. M.

2017-01-01

Deep eutectic solvents (DESs) are a potentially high-value lignin extraction methodology. DESs prepared from choline chloride (ChCl) and three hydrogen-bond donors (HBD)—lactic acid (Lac), glycerol, and urea—were evaluated for isolation of willow (Salix matsudana cv. Zhuliu) lignin. DESs types, mole ratio of ChCl to HBD, extraction temperature, and time on the fractionated DES-lignin yield demonstrated that the optimal DES-lignin yield (91.8 wt % based on the initial lignin in willow) with high purity of 94.5% can be reached at a ChCl-to-Lac molar ratio of 1:10, extraction temperature of 120 °C, and time of 12 h. Fourier transform infrared spectroscopy (FT-IR) , 13C-NMR, and 31P-NMR showed that willow lignin extracted by ChCl-Lac was mainly composed of syringyl and guaiacyl units. Serendipitously, a majority of the glucan in willow was preserved after ChCl-Lac treatment. PMID:29143790

Transcription of two adjacent carbohydrate utilization gene clusters in Bifidobacterium breve UCC2003 is controlled by LacI- and repressor open reading frame kinase (ROK)-type regulators.

PubMed

O'Connell, Kerry Joan; Motherway, Mary O'Connell; Liedtke, Andrea; Fitzgerald, Gerald F; Paul Ross, R; Stanton, Catherine; Zomer, Aldert; van Sinderen, Douwe

2014-06-01

Members of the genus Bifidobacterium are commonly found in the gastrointestinal tracts of mammals, including humans, where their growth is presumed to be dependent on various diet- and/or host-derived carbohydrates. To understand transcriptional control of bifidobacterial carbohydrate metabolism, we investigated two genetic carbohydrate utilization clusters dedicated to the metabolism of raffinose-type sugars and melezitose. Transcriptomic and gene inactivation approaches revealed that the raffinose utilization system is positively regulated by an activator protein, designated RafR. The gene cluster associated with melezitose metabolism was shown to be subject to direct negative control by a LacI-type transcriptional regulator, designated MelR1, in addition to apparent indirect negative control by means of a second LacI-type regulator, MelR2. In silico analysis, DNA-protein interaction, and primer extension studies revealed the MelR1 and MelR2 operator sequences, each of which is positioned just upstream of or overlapping the correspondingly regulated promoter sequences. Similar analyses identified the RafR binding operator sequence located upstream of the rafB promoter. This study indicates that transcriptional control of gene clusters involved in carbohydrate metabolism in bifidobacteria is subject to conserved regulatory systems, representing either positive or negative control.

Restoration of parathyroid function after change of phosphate binder from calcium carbonate to lanthanum carbonate in hemodialysis patients with suppressed serum parathyroid hormone.

PubMed

Inaba, Masaaki; Okuno, Senji; Nagayama, Harumi; Yamada, Shinsuke; Ishimura, Eiji; Imanishi, Yasuo; Shoji, Shigeichi

2015-03-01

Control of phosphate is the most critical in the treatment of chronic kidney disease with mineral and bone disorder (CKD-MBD). Because calcium-containing phosphate binder to CKD patients is known to induce adynamic bone disease with ectopic calcification by increasing calcium load, we examined the effect of lanthanum carbonate (LaC), a non-calcium containing phosphate binder, to restore bone turnover in 27 hemodialysis patients with suppressed parathyroid function (serum intact parathyroid hormone [iPTH] ≦ 150 pg/mL). At the initiation of LaC administration, the dose of calcium-containing phosphate binder calcium carbonate (CaC) was withdrawn or reduced based on serum phosphate. After initiation of LaC administration, serum calcium and phosphate decreased significantly by 4 weeks, whereas whole PTH and iPTH increased. A significant and positive correlation between decreases of serum calcium, but not phosphate, with increases of whole PTH and iPTH, suggested that the decline in serum calcium with reduction of calcium load by LaC might increase parathyroid function. Serum bone resorption markers, such as serum tartrate-resistant acid phosphatase 5b, and N-telopeptide of type I collagen increased significantly by 4 weeks after LaC administration, which was followed by increases of serum bone formation markers including serum bone alkaline phosphatase, intact procollagen N-propeptide, and osteocalcin. Therefore, it was suggested that LaC attenuated CaC-induced suppression of parathyroid function and bone turnover by decreasing calcium load. In conclusion, replacement of CaC with LaC, either partially or totally, could increase parathyroid function and resultant bone turnover in hemodialysis patients with serum iPTH ≦ 150 pg/mL. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Experimental identification of specificity determinants in the domain linker of a LacI/GalR protein: bioinformatics-based predictions generate true positives and false negatives.

PubMed

Meinhardt, Sarah; Swint-Kruse, Liskin

2008-12-01

In protein families, conserved residues often contribute to a common general function, such as DNA-binding. However, unique attributes for each homolog (e.g. recognition of alternative DNA sequences) must arise from variation in other functionally-important positions. The locations of these "specificity determinant" positions are obscured amongst the background of varied residues that do not make significant contributions to either structure or function. To isolate specificity determinants, a number of bioinformatics algorithms have been developed. When applied to the LacI/GalR family of transcription regulators, several specificity determinants are predicted in the 18 amino acids that link the DNA-binding and regulatory domains. However, results from alternative algorithms are only in partial agreement with each other. Here, we experimentally evaluate these predictions using an engineered repressor comprising the LacI DNA-binding domain, the LacI linker, and the GalR regulatory domain (LLhG). "Wild-type" LLhG has altered DNA specificity and weaker lacO(1) repression compared to LacI or a similar LacI:PurR chimera. Next, predictions of linker specificity determinants were tested, using amino acid substitution and in vivo repression assays to assess functional change. In LLhG, all predicted sites are specificity determinants, as well as three sites not predicted by any algorithm. Strategies are suggested for diminishing the number of false negative predictions. Finally, individual substitutions at LLhG specificity determinants exhibited a broad range of functional changes that are not predicted by bioinformatics algorithms. Results suggest that some variants have altered affinity for DNA, some have altered allosteric response, and some appear to have changed specificity for alternative DNA ligands.

Louisiana SIP: LAC 33:III Ch. 5 Section 509. Prevention of Significant Deterioration; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) and 1991-07-01 (LAc57) and 1996-12-16 (LAc69) to 2011-08-17 (LAd36 - Revised)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch. 5 Section 509. Prevention of Significant Deterioration; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) and 1991-07-01 (LAc57) and 1996-12-16 (LAc69) to 2011-08-17 (LAd36 - Revised)

Effects of TGF-β signaling blockade on human A549 lung adenocarcinoma cell lines.

PubMed

Xu, Cheng-Cheng; Wu, Lei-Ming; Sun, Wei; Zhang, Ni; Chen, Wen-Shu; Fu, Xiang-Ning

2011-01-01

Transforming growth factor β (TGF-β) is overexpressed in a wide variety of cancer types including lung adenocarcinoma (LAC), and the TGF-β signaling pathway plays an important role in tumor development. To determine whether blockade of the TGF-β signaling pathway can inhibit the malignant biological behavior of LAC, RNA interference (RNAi) technology was used to silence the expression of TGF-β receptor, type II (TGFβRII) in the LAC cell line, A549, and its effects on cell proliferation, invasion and metastasis were examined. Three specific small interfering RNAs (siRNAs) designed for targeting human TGFβRII were transfected into A549 cells. The expression of TGFβRII was detected by Western blot analysis. Cell proliferation was measured by MTT and clonogenic assays. Cell apoptosis was assessed by flow cytometry. The invasion and metastasis of A549 cells were investigated using the wound healing and Matrigel invasion assays. The expression of PI3K, phosphorylated Smad2, Smad4, Akt, Erk1/2, P38 and MMPs was detected by Western blot analysis. The TGFβRII siRNA significantly reduced the expression of TGFβRII in A549 cells. The knockdown of TGFβRII in A549 cells resulted in the suppression of cell proliferation, invasion and metastasis and induced cell apoptosis. In addition to the Smad-dependent pathway, independent pathways including the Erk MAPK, PI3K/Akt and p38 MAPK pathways, as well as the expression of MMPs and VEGF, were inhibited. In conclusion, TGF-β signaling is required for LAC progression. Therefore, the blockade of this signaling pathway by the down-regulation of TGFβRII using SiRNA may provide a potential gene therapy for LAC.

Two genetically separable phases of growth inhibition induced by blue light in Arabidopsis seedlings

NASA Technical Reports Server (NTRS)

Parks, B. M.; Cho, M. H.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

1998-01-01

High fluence-rate blue light (BL) rapidly inhibits hypocotyl growth in Arabidopsis, as in other species, after a lag time of 30 s. This growth inhibition is always preceded by the activation of anion channels. The membrane depolarization that results from the activation of anion channels by BL was only 30% of the wild-type magnitude in hy4, a mutant lacking the HY4 BL receptor. High-resolution measurements of growth made with a computer-linked displacement transducer or digitized images revealed that BL caused a rapid inhibition of growth in wild-type and hy4 seedlings. This inhibition persisted in wild-type seedlings during more than 40 h of continuous BL. By contrast, hy4 escaped from the initial inhibition after approximately 1 h of BL and grew faster than wild type for approximately 30 h. Wild-type seedlings treated with 5-nitro-2-(3-phenylpropylamino)-benzoic acid, a potent blocker of the BL-activated anion channel, displayed rapid growth inhibition, but, similar to hy4, these seedlings escaped from inhibition after approximately 1 h of BL and phenocopied the mutant for at least 2.5 h. The effects of 5-nitro-2-(3-phenylpropylamino)-benzoic acid and the HY4 mutation were not additive. Taken together, the results indicate that BL acts through HY4 to activate anion channels at the plasma membrane, causing growth inhibition that begins after approximately 1 h. Neither HY4 nor anion channels appear to participate greatly in the initial phase of inhibition.

Disruption of LACCASE4 and 17 Results in Tissue-Specific Alterations to Lignification of Arabidopsis thaliana Stems[W

PubMed Central

Berthet, Serge; Demont-Caulet, Nathalie; Pollet, Brigitte; Bidzinski, Przemyslaw; Cézard, Laurent; Le Bris, Phillipe; Borrega, Nero; Hervé, Jonathan; Blondet, Eddy; Balzergue, Sandrine; Lapierre, Catherine; Jouanin, Lise

2011-01-01

Peroxidases have been shown to be involved in the polymerization of lignin precursors, but it remains unclear whether laccases (EC 1.10.3.2) participate in constitutive lignification. We addressed this issue by studying laccase T-DNA insertion mutants in Arabidopsis thaliana. We identified two genes, LAC4 and LAC17, which are strongly expressed in stems. LAC17 was mainly expressed in the interfascicular fibers, whereas LAC4 was expressed in vascular bundles and interfascicular fibers. We produced two double mutants by crossing the LAC17 (lac17) mutant with two LAC4 mutants (lac4-1 and lac4-2). The single and double mutants grew normally in greenhouse conditions. The single mutants had moderately low lignin levels, whereas the stems of lac4-1 lac17 and lac4-2 lac17 mutants had lignin contents that were 20 and 40% lower than those of the control, respectively. These lower lignin levels resulted in higher saccharification yields. Thioacidolysis revealed that disrupting LAC17 principally affected the deposition of G lignin units in the interfascicular fibers and that complementation of lac17 with LAC17 restored a normal lignin profile. This study provides evidence that both LAC4 and LAC17 contribute to the constitutive lignification of Arabidopsis stems and that LAC17 is involved in the deposition of G lignin units in fibers. PMID:21447792

The statistics of gravitational lenses. III - Astrophysical consequences of quasar lensing

NASA Technical Reports Server (NTRS)

Ostriker, J. P.; Vietri, M.

1986-01-01

The method of Schmidt and Green (1983) for calculating the luminosity function of quasars is combined with gravitational-lensing theory to compute expected properties of lensed systems. Multiple quasar images produced by galaxies are of order 0.001 of the observed quasars, with the numbers over the whole sky calculated to be (0.86, 120, 1600) to limiting B magnitudes of (16, 19, 22). The amount of 'false evolution' is small except for an interesting subset of apparently bright, large-redshift objects for which minilensing by starlike objects may be important. Some of the BL Lac objects may be in this category, with the galaxy identified as the parent object really a foreground object within which stars have lensed a background optically violent variable quasar.

Shared or Integrated: Which Type of Integration is More Effective Improves Students’ Creativity?

NASA Astrophysics Data System (ADS)

Mariyam, M.; Kaniawati, I.; Sriyati, S.

2017-09-01

Integrated science learning has various types of integration. This study aims to apply shared and integrated type of integration with project based learning (PjBL) model to improve students’ creativity on waste recycling theme. The research method used is a quasi experiment with the matching-only pre test-post test design. The samples of this study are 108 students consisting of 36 students (experiment class 1st), 35 students (experiment class 2nd) and 37 students (control class 3rd) at one of Junior High School in Tanggamus, Lampung. The results show that there is difference of creativity improvement in the class applied by PjBL model with shared type of integration, integrated type of integration and without any integration in waste recycling theme. Class applied by PjBL model with shared type of integration has the higher creativity improvement than the PjBL model with integrated type of integration and without any integration. Integrated science learning using shared type only combines 2 lessons, hence an intact concept is resulted. So, PjBL model with shared type of integration more effective improves students’ creativity than integrated type.

Highly efficient gene transfer into adult ventricular myocytes by recombinant adenovirus.

PubMed Central

Kirshenbaum, L A; MacLellan, W R; Mazur, W; French, B A; Schneider, M D

1993-01-01

Molecular dissection of mechanisms that govern the differentiated cardiac phenotype has, for cogent technical reasons, largely been undertaken to date in neonatal ventricular myocytes. To circumvent expected limitations of other methods, the present study was initiated to determine whether replication-deficient adenovirus would enable efficient gene transfer to adult cardiac cells in culture. Adult rat ventricular myocytes were infected, 24 h after plating, with adenovirus type 5 containing a cytomegalovirus immediate-early promoter-driven lacZ reporter gene and were assayed for the presence of beta-galactosidase 48 h after infection. The frequency of lacZ+ rod-shaped myocytes was half-maximal at 4 x 10(5) plaque-forming units (PFU) and approached 90% at 1 x 10(8) PFU. Uninfected cells and cells infected with lacZ- virus remained colorless. Beta-galactosidase activity concurred with the proportion of lacZ+ cells and was contingent on the exogenous lacZ gene. At 10(8) PFU/dish, cell number, morphology, and viability each were comparable to uninfected cells. Thus, adult ventricular myocytes are amenable to efficient gene transfer with recombinant adenovirus. The relative uniformity for gene transfer by adenovirus should facilitate tests to determine the impact of putative regulators upon the endogenous genes and gene products of virally modified adult ventricular muscle cells. Images PMID:8326005

LC–MS/MS Quantitation of Esophagus Disease Blood Serum Glycoproteins by Enrichment with Hydrazide Chemistry and Lectin Affinity Chromatography

PubMed Central

2015-01-01

Changes in glycosylation have been shown to have a profound correlation with development/malignancy in many cancer types. Currently, two major enrichment techniques have been widely applied in glycoproteomics, namely, lectin affinity chromatography (LAC)-based and hydrazide chemistry (HC)-based enrichments. Here we report the LC–MS/MS quantitative analyses of human blood serum glycoproteins and glycopeptides associated with esophageal diseases by LAC- and HC-based enrichment. The separate and complementary qualitative and quantitative data analyses of protein glycosylation were performed using both enrichment techniques. Chemometric and statistical evaluations, PCA plots, or ANOVA test, respectively, were employed to determine and confirm candidate cancer-associated glycoprotein/glycopeptide biomarkers. Out of 139, 59 common glycoproteins (42% overlap) were observed in both enrichment techniques. This overlap is very similar to previously published studies. The quantitation and evaluation of significantly changed glycoproteins/glycopeptides are complementary between LAC and HC enrichments. LC–ESI–MS/MS analyses indicated that 7 glycoproteins enriched by LAC and 11 glycoproteins enriched by HC showed significantly different abundances between disease-free and disease cohorts. Multiple reaction monitoring quantitation resulted in 13 glycopeptides by LAC enrichment and 10 glycosylation sites by HC enrichment to be statistically different among disease cohorts. PMID:25134008

Evaluation of anaerobic threshold in non-pregnant and pregnant rats.

PubMed

Netto, Aline Oliveira; Macedo, Nathália C D; Gallego, Franciane Q; Sinzato, Yuri K; Volpato, Gustavo T; Damasceno, Débora C

2017-01-01

Several studies present different methodologies and results about intensity exercise, and many of them are performed in male rats. However, the impact of different type, intensity, frequency and duration of exercise on female rats needs more investigation. From the analysis of blood lactate concentration during lactate minimum test (LacMin) in the swimming exercise, the anaerobic threshold (AT) was identified, which parameter is defined as the transition point between aerobic and anaerobic metabolism. LacMin test is considered a good indicator of aerobic conditioning and has been used in prescription of training in different exercise modalities. However, there is no evidence of LacMin test in female rats. The objective was to determine AT in non-pregnant and pregnant Wistar rats. The LacMin test was performed and AT defined for mild exercise intensity was from a load equivalent to 1% of body weight (bw), moderate exercise as carrying 4% bw and severe intensity as carrying 7% bw. In pregnant rats, the AT was reached at a lower loading from 5.0% to 5.5% bw, while in non-pregnant the load was from 5.5% to 6.0% bw. Thus, this study was effective to identify exercise intensities in pregnant and non-pregnant rats using anaerobic threshold by LacMin test.

Investigating Self-Perceptions and Resilience in Looked after Children

ERIC Educational Resources Information Center

Honey, Kyla L.; Rees, Paul; Griffey, Simon

2011-01-01

The perceptions of Looked After Children (LAC; n = 51), their Designated Teachers (DTs), and a sample of non-LAC (n = 99) were elicited. LAC held more positive self-perceptions than the non-LAC, and similarly positive ratings were given for the LAC by their DTs; but LAC held lower career aspirations than the non-LAC. LAC differed in their levels…

X-ray structure of a two-domain type laccase: a missing link in the evolution of multi-copper proteins.

PubMed

Komori, Hirofumi; Miyazaki, Kentaro; Higuchi, Yoshiki

2009-04-02

A multi-copper protein with two cupredoxin-like domains was identified from our in-house metagenomic database. The recombinant protein, mgLAC, contained four copper ions/subunits, oxidized various phenolic and non-phenolic substrates, and had spectroscopic properties similar to common laccases. X-ray structure analysis revealed a homotrimeric architecture for this enzyme, which resembles nitrite reductase (NIR). However, a difference in copper coordination was found at the domain interface. mgLAC contains a T2/T3 tri-nuclear copper cluster at this site, whereas a mononuclear T2 copper occupies this position in NIR. The trimer is thus an essential part of the architecture of two-domain multi-copper proteins, and mgLAC may be an evolutionary precursor of NIR.

Multiwavelength Observations of the Blazar BL Lacertae: A New Fast TeV Gamma-Ray Flare

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Benbow, W.; Bird, R.; Brantseg, T.; Brose, R.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Connolly, M. P.; Cui, W.; Daniel, M. K.; Falcone, A.; Feng, Q.; Finley, J. P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Gunawardhana, I.; Hütten, M.; Hanna, D.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kertzman, M.; Krennrich, F.; Lang, M. J.; Lin, T. T. Y.; McArthur, S.; Moriarty, P.; Mukherjee, R.; O’Brien, S.; Ong, R. A.; Otte, A. N.; Park, N.; Petrashyk, A.; Pohl, M.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rulten, C.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Wakely, S. P.; Weinstein, A.; Wells, R. M.; Wilcox, P.; Williams, D. A.; Zitzer, B.; The VERITAS Collaboration; Jorstad, S. G.; Marscher, A. P.; Lister, M. L.; Kovalev, Y. Y.; Pushkarev, A. B.; Savolainen, T.; Agudo, I.; Molina, S. N.; Gómez, J. L.; Larionov, V. M.; Borman, G. A.; Mokrushina, A. A.; Tornikoski, M.; Lähteenmäki, A.; Chamani, W.; Enestam, S.; Kiehlmann, S.; Hovatta, T.; Smith, P. S.; Pontrelli, P.

2018-04-01

Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of ∼2.3 hr and a decay time of ∼36 min. The peak flux above 200 GeV is (4.2 ± 0.6) × 10‑6 photon m‑2 s‑1 measured with a 4-minute-binned light curve, corresponding to ∼180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.

FERMI LARGE AREA TELESCOPE VIEW OF THE CORE OF THE RADIO GALAXY CENTAURUS A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdo, A. A.; Ackermann, M.; Ajello, M.

2010-08-20

We present {gamma}-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the {gamma}-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum ({Gamma} = 2.67 {+-}more » 0.10{sub stat} {+-} 0.08{sub sys} where the photon flux is {Phi} {proportional_to} E {sup -{Gamma}}). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). We fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the {gamma}-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy cosmic-rays, as hinted at by results from the Auger observatory.« less

Fermi Large Area Telescope View of the Core of the Radio Galaxy Centaurus A

NASA Astrophysics Data System (ADS)

Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Cominsky, L. R.; Conrad, J.; Costamante, L.; Davis, D. S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Falcone, A.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hase, Hayo; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Itoh, R.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kishishita, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Müller, C.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Pagani, C.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Plötz, C.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stawarz, L.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

2010-08-01

We present γ-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the γ-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum (Γ = 2.67 ± 0.10stat ± 0.08sys where the photon flux is Φ vprop E -Γ). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). We fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the γ-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy cosmic-rays, as hinted at by results from the Auger observatory.

VERITAS OBSERVATIONS OF THE BL LAC OBJECT PG 1553+113

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliu, E.; Archer, A.; Beilicke, M.

2015-01-20

We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 ± 0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 ± 0.06) × 10{sup –11} photons cm{sup –2} s{sup –1}, corresponding to 6.9% of the Crab Nebula flux. We also present the combined γ-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV.more » The data are well fit by a power law with an exponential cutoff at 101.9 ± 3.2 GeV. The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the γ-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z > 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z ≤ 0.62. A strongly elevated mean flux of (2.50 ± 0.14) × 10{sup –11} photons cm{sup –2} s{sup –1} (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44±0.71)×10{sup −11} photons cm{sup −2} s{sup −1} (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a χ{sup 2} probability for a steady flux of 0.03%.« less

FERMI Large Area Telescope View of the 1 Core of the Radio Galaxy Centaurus A

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-07-29

We present γ-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the γ-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum (Γ = 2.67 ±more » 0.10 stat ± 0.08 sys where the photon flux is Φ ∝ E –Γ). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). Here, we fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the γ-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy cosmic-rays, as hinted at by results from the Auger observatory.« less

Transcription of Two Adjacent Carbohydrate Utilization Gene Clusters in Bifidobacterium breve UCC2003 Is Controlled by LacI- and Repressor Open Reading Frame Kinase (ROK)-Type Regulators

PubMed Central

O'Connell, Kerry Joan; O'Connell Motherway, Mary; Liedtke, Andrea; Fitzgerald, Gerald F.; Ross, R. Paul; Stanton, Catherine; Zomer, Aldert

2014-01-01

Members of the genus Bifidobacterium are commonly found in the gastrointestinal tracts of mammals, including humans, where their growth is presumed to be dependent on various diet- and/or host-derived carbohydrates. To understand transcriptional control of bifidobacterial carbohydrate metabolism, we investigated two genetic carbohydrate utilization clusters dedicated to the metabolism of raffinose-type sugars and melezitose. Transcriptomic and gene inactivation approaches revealed that the raffinose utilization system is positively regulated by an activator protein, designated RafR. The gene cluster associated with melezitose metabolism was shown to be subject to direct negative control by a LacI-type transcriptional regulator, designated MelR1, in addition to apparent indirect negative control by means of a second LacI-type regulator, MelR2. In silico analysis, DNA-protein interaction, and primer extension studies revealed the MelR1 and MelR2 operator sequences, each of which is positioned just upstream of or overlapping the correspondingly regulated promoter sequences. Similar analyses identified the RafR binding operator sequence located upstream of the rafB promoter. This study indicates that transcriptional control of gene clusters involved in carbohydrate metabolism in bifidobacteria is subject to conserved regulatory systems, representing either positive or negative control. PMID:24705323

Lightning Arrestor Connectors Production Readiness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marten, Steve; Linder, Kim; Emmons, Jim

2008-10-20

The Lightning Arrestor Connector (LAC), part “M”, presented opportunities to improve the processes used to fabricate LACs. The A## LACs were the first production LACs produced at the KCP, after the product was transferred from Pinnellas. The new LAC relied on the lessons learned from the A## LACs; however, additional improvements were needed to meet the required budget, yield, and schedule requirements. Improvement projects completed since 2001 include Hermetic Connector Sealing Improvement, Contact Assembly molding Improvement, development of a second vendor for LAC shells, general process improvement, tooling improvement, reduction of the LAC production cycle time, and documention of themore » LAC granule fabrication process. This report summarizes the accomplishments achieved in improving the LAC Production Readiness.« less

[Role of the sweet taste receptor in glucose metabolism: no sweets for diabetes?].

PubMed

Nomura, Masatoshi; Kawahara, Yuta

2015-01-01

Type 2 diabetes is closely associated with our daily diets and has become a global health problem with increasing number of patients. Maintaining energy homeostasis is essentially required for the treatment of diabetes. Energy metabolism starts with taking in a meal. Nutrients including amino acids, fatty acids and glucose in the digest have been shown to act on the neuroendocrine cells in the gastrointestinal (GI) tract, and thereby play important roles in energy homeostasis. Therefore, the GI tract is now recognized as a sensor system for nutrient signals. Taste receptor type 1 member 2 (T1R2) is known to function as a co-receptor with T1R3 to detect sweet chemicals in the taste buds. It has been proposed that the T1R2/T1R3 receptor complex acts as sweet sensor in the intestine, and plays a pivotal role in sensing sugars and maintaining glucose homeostasis through incretin secretion. To clarify the physiological roles of T1R2 in glucose homeostasis, T1r2-lacZ knock-in/knock-out mice were generated. We found lacZ gene expression in the GI tract where T1r3 expression has been reported. Interestingly, the T1r2-lacZ knock-in mice showed impaired glucose tolerance on oral glucose challenge but not on intraperitoneal injection. However, the fasting glucose level in T1r2-lacZ knock-in mice was comparable to that in wild type mice. These results suggest an important role of the sweet taste receptor system in the intestine when stimulated by glucose. Therefore, the roles of T1R2 will be presented and the mechanism for metabolic homeostasis will be discussed.

Various mutations compensate for a deleterious lacZα insert in the replication enhancer of M13 bacteriophage

PubMed Central

Zygiel, Emily M.; Noren, Karen A.; Adamkiewicz, Marta A.; Aprile, Richard J.; Bowditch, Heather K.; Carroll, Christine L.; Cerezo, Maria Abigail S.; Dagher, Adelle M.; Hebert, Courtney R.; Hebert, Lauren E.; Mahame, Gloria M.; Milne, Stephanie C.; Silvestri, Kelly M.; Sutherland, Sara E.; Sylvia, Alexandria M.; Taveira, Caitlyn N.; VanValkenburgh, David J.; Noren, Christopher J.

2017-01-01

M13 and other members of the Ff class of filamentous bacteriophages have been extensively employed in myriad applications. The Ph.D. series of phage-displayed peptide libraries were constructed from the M13-based vector M13KE. As a direct descendent of M13mp19, M13KE contains the lacZα insert in the intergenic region between genes IV and II, where it interrupts the replication enhancer of the (+) strand origin. Phage carrying this 816-nucleotide insert are viable, but propagate in E. coli at a reduced rate compared to wild-type M13 phage, presumably due to a replication defect caused by the insert. We have previously reported thirteen compensatory mutations in the 5’-untranslated region of gene II, which encodes the replication initiator protein gIIp. Here we report several additional mutations in M13KE that restore a wild-type propagation rate. Several clones from constrained-loop variable peptide libraries were found to have ejected the majority of lacZα gene in order to reconstruct the replication enhancer, albeit with a small scar. In addition, new point mutations in the gene II 5’-untranslated region or the gene IV coding sequence have been spontaneously observed or synthetically engineered. Through phage propagation assays, we demonstrate that all these genetic modifications compensate for the replication defect in M13KE and restore the wild-type propagation rate. We discuss the mechanisms by which the insertion and ejection of the lacZα gene, as well as the mutations in the regulatory region of gene II, influence the efficiency of replication initiation at the (+) strand origin. We also examine the presence and relevance of fast-propagating mutants in phage-displayed peptide libraries. PMID:28445507

Various mutations compensate for a deleterious lacZα insert in the replication enhancer of M13 bacteriophage.

PubMed

Zygiel, Emily M; Noren, Karen A; Adamkiewicz, Marta A; Aprile, Richard J; Bowditch, Heather K; Carroll, Christine L; Cerezo, Maria Abigail S; Dagher, Adelle M; Hebert, Courtney R; Hebert, Lauren E; Mahame, Gloria M; Milne, Stephanie C; Silvestri, Kelly M; Sutherland, Sara E; Sylvia, Alexandria M; Taveira, Caitlyn N; VanValkenburgh, David J; Noren, Christopher J; Hall, Marilena Fitzsimons

2017-01-01

M13 and other members of the Ff class of filamentous bacteriophages have been extensively employed in myriad applications. The Ph.D. series of phage-displayed peptide libraries were constructed from the M13-based vector M13KE. As a direct descendent of M13mp19, M13KE contains the lacZα insert in the intergenic region between genes IV and II, where it interrupts the replication enhancer of the (+) strand origin. Phage carrying this 816-nucleotide insert are viable, but propagate in E. coli at a reduced rate compared to wild-type M13 phage, presumably due to a replication defect caused by the insert. We have previously reported thirteen compensatory mutations in the 5'-untranslated region of gene II, which encodes the replication initiator protein gIIp. Here we report several additional mutations in M13KE that restore a wild-type propagation rate. Several clones from constrained-loop variable peptide libraries were found to have ejected the majority of lacZα gene in order to reconstruct the replication enhancer, albeit with a small scar. In addition, new point mutations in the gene II 5'-untranslated region or the gene IV coding sequence have been spontaneously observed or synthetically engineered. Through phage propagation assays, we demonstrate that all these genetic modifications compensate for the replication defect in M13KE and restore the wild-type propagation rate. We discuss the mechanisms by which the insertion and ejection of the lacZα gene, as well as the mutations in the regulatory region of gene II, influence the efficiency of replication initiation at the (+) strand origin. We also examine the presence and relevance of fast-propagating mutants in phage-displayed peptide libraries.

The Vibrio parahaemolyticus ToxRS Regulator Is Required for Stress Tolerance and Colonization in a Novel Orogastric Streptomycin-Induced Adult Murine Model

PubMed Central

Whitaker, W. Brian; Parent, Michelle A.; Boyd, Aoife; Richards, Gary P.

2012-01-01

Vibrio parahaemolyticus, a marine bacterium, is the causative agent of gastroenteritis associated with the consumption of seafood. It contains a homologue of the toxRS operon that in V. cholerae is the key regulator of virulence gene expression. We examined a nonpolar mutation in toxRS to determine the role of these genes in V. parahaemolyticus RIMD2210633, an O3:K6 isolate, and showed that compared to the wild type, ΔtoxRS was significantly more sensitive to acid, bile salts, and sodium dodecyl sulfate stresses. We demonstrated that ToxRS is a positive regulator of ompU expression, and that the complementation of ΔtoxRS with ompU restores stress tolerance. Furthermore, we showed that ToxRS also regulates type III secretion system genes in chromosome I via the regulation of the leuO homologue VP0350. We examined the effect of ΔtoxRS in vivo using a new orogastric adult murine model of colonization. We demonstrated that streptomycin-treated adult C57BL/6 mice experienced prolonged intestinal colonization along the entire intestinal tract by the streptomycin-resistant V. parahaemolyticus. In contrast, no colonization occurred in non-streptomycin-treated mice. A competition assay between the ΔtoxRS and wild-type V. parahaemolyticus strains marked with the β-galactosidase gene lacZ demonstrated that the ΔtoxRS strain was defective in colonization compared to the wild-type strain. This defect was rescued by ectopically expressing ompU. Thus, the defect in stress tolerance and colonization in ΔtoxRS is solely due to OmpU. To our knowledge, the orogastric adult murine model reported here is the first showing sustained intestinal colonization by V. parahaemolyticus. PMID:22392925

Metabolic engineering of Escherichia coli to produce 2'-fucosyllactose via salvage pathway of guanosine 5'-diphosphate (GDP)-l-fucose.

PubMed

Chin, Young-Wook; Seo, Nari; Kim, Jae-Han; Seo, Jin-Ho

2016-11-01

2'-Fucosyllactose (2-FL) is one of the key oligosaccharides in human milk. In the present study, the salvage guanosine 5'-diphosphate (GDP)-l-fucose biosynthetic pathway from fucose was employed in engineered Escherichia coli BL21star(DE3) for efficient production of 2-FL. Introduction of the fkp gene coding for fucokinase/GDP-l-fucose pyrophosphorylase (Fkp) from Bacteroides fragilis and the fucT2 gene encoding α-1,2-fucosyltransferase from Helicobacter pylori allows the engineered E. coli to produce 2-FL from fucose, lactose and glycerol. To enhance the lactose flux to 2-FL production, the attenuated, and deleted mutants of β-galactosidase were employed. Moreover, the 2-FL yield and productivity were further improved by deletion of the fucI-fucK gene cluster coding for fucose isomerase (FucI) and fuculose kinase (FucK). Finally, fed-batch fermentation of engineered E. coli BL21star(DE3) deleting lacZ and fucI-fucK, and expressing fkp and fucT2 resulted in 23.1 g/L of extracellular concentration of 2-FL and 0.39 g/L/h productivity. Biotechnol. Bioeng. 2016;113: 2443-2452. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

CONSTRAINTS ON THE INTERGALACTIC MAGNETIC FIELD WITH GAMMA-RAY OBSERVATIONS OF BLAZARS

DOE PAGES

Finke, Justin D.; Reyes, Luis C.; Georganopoulos, Markos; ...

2015-11-12

Distant BL Lacertae objects emit γ rays which interact with the extragalactic background light (EBL), creating electron-positron pairs, and reducing the flux measured by ground-based imaging atmospheric Cherenkov telescopes (IACTs) at very-high energies (VHE). These pairs can Comptonscatter the cosmic microwave background, creating a γ-ray signature at slightly lower energies observable by the Fermi Large Area Telescope (LAT). This signal is strongly dependent on the intergalactic magnetic field (IGMF) strength (B) and its coherence length (LB). We use IACT spectra taken from the literature for 5 VHE-detected BL Lac objects, and combine it with LAT spectra for these sources tomore » constrain these IGMF parameters. Low B values can be ruled out by the constraint that the cascade flux cannot exceed that observed by the LAT. High values of B can be ruled out from the constraint that the EBL-deabsorbed IACT spectrum cannot be greater than the LAT spectrum extrapolated into the VHE band, unless the cascade spectrum contributes a sizable fraction of the LAT flux. We rule out low B values (B . 10 -19 G for LB ≥ 1 Mpc) at > 5σ in all trials with different EBL models and data selection, except when« less

Evaluating the potential of immobilized bacterial consortium for black liquor biodegradation.

PubMed

Paliwal, Rashmi; Uniyal, Shivani; Rai, J P N

2015-05-01

Two indigenous bacterial strains, Bacillus megaterium ETLB-1 (accession no. KC767548) and Pseudomonas plecoglossicida ETLB-3 (accession no. KC767547), isolated from soil contaminated with paper mill effluent, were co-immobilized on corncob cubes to investigate their biodegradation potential against black liquor (BL). Results exhibit conspicuous reduction in color and lignin of BL upto 913.46 Co-Pt and 531.45 mg l(-1), respectively. Reduction in chlorophenols up to 12 mg l(-1) was recorded with highest release of chloride ions, i.e., 1290 mg l(-1). Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (LAC) was recorded as 5.06, 8.13, and 8.23 U ml(-1), respectively, during the treatment. Scanning electron microscopy (SEM) revealed successful immobilization of bacterial strains in porous structures of biomaterial. Gas chromatography/mass spectroscopy (GC/MS) showed formation of certain low molecular weight metabolites such as 4-hydroxy-benzoic acid, 3-hydroxy-4-methoxybenzaldehyde, ferulic acid, and t-cinnamic acid and removal of majority of the compounds (such as teratogenic phthalate derivatives) during the period of treatment. Results demonstrated that the indigenous bacterial consortium possesses excellent decolorization and lignin degradation capability which enables its commercial utilization in effluents treatment system.

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

DOE PAGES

Wilson, Charlotte M.; Klingeman, Dawn M.; Schlachter, Caleb; ...

2016-12-21

Organisms regulate gene expression in response to the environment to coordinate metabolic reactions.Clostridium thermocellumexpresses enzymes for both lignocellulose solubilization and its fermentation to produce ethanol. In one LacI regulator termed GlyR3 inC. thermocellumATCC 27405 we identified a repressor of neighboring genes with repression relieved by laminaribiose (a β-1,3 disaccharide). To better understand the threeC. thermocellumLacI regulons, deletion mutants were constructed using the genetically tractable DSM1313 strain. DSM1313lacIgenes Clo1313_2023, Clo1313_0089, and Clo1313_0396 encode homologs of GlyR1, GlyR2, and GlyR3 from strain ATCC 27405, respectively. Furthermore, growth on cellobiose or pretreated switchgrass was unaffected by any of the gene deletions under controlled-pHmore » fermentations. Global gene expression patterns from time course analyses identified glycoside hydrolase genes encoding hemicellulases, including cellulosomal enzymes, that were highly upregulated (5- to 100-fold) in the absence of each LacI regulator, suggesting that these were repressed under wild-type conditions and that relatively few genes were controlled by each regulator under the conditions tested. Clo1313_2022, encoding lichenase enzyme LicB, was derepressed in a ΔglyR1strain. Higher expression of Clo1313_1398, which encodes the Man5A mannanase, was observed in a ΔglyR2strain, and α-mannobiose was identified as a probable inducer for GlyR2-regulated genes. For the ΔglyR3strain, upregulation of the two genes adjacent toglyR3in thecelC-glyR3-licAoperon was consistent with earlier studies. Electrophoretic mobility shift assays have confirmed LacI transcription factor binding to specific regions of gene promoters. IMPORTANCEUnderstandingC. thermocellumgene regulation is of importance for improved fundamental knowledge of this industrially relevant bacterium. Most LacI transcription factors regulate local genomic regions; however, a small number of those genes encode global regulatory proteins with extensive regulons. This study indicates that there are small specificC. thermocellumLacI regulons. Finally, the identification of LacI repressor activity for hemicellulase gene expression is a key result of this work and will add to the small body of existing literature on the area of gene regulation inC. thermocellum.« less

A comparative study of thermochemical and cold plasma treatment on lignin-based activated carbon for adsorbing Fe(III)

NASA Astrophysics Data System (ADS)

Shi, Shukai; Wang, Xin; Chen, Weimin; Chen, Minzhi; Zhou, Xiaoyan

2018-05-01

The as-prepared lignin-based activated carbon (LAC) was post-treated by urea and radio-frequency cold plasma separately. The obtained results demonstrated that the BET surface and total volumes of the LAC and plasma-treated LACs were greater than the urea-modified sample. The analysis of surface elemental composition showed that the nitrogen content of urea-modified LAC and nitrogen plasma-treated LAC are 3.79% and 2.62% higher than that of original LAC respectively, while the oxygen content of air plasma-treated LAC is 10.23% higher than that of original LAC. The Fe(III) ions adsorbed studies with pseudo-second order kinetic model revealed that urea-modified LAC had faster chemisorption rates while air plasma-treated LAC had larger adsorption capacity within 3 h. Moreover, the adsorption capacity and chemisorption rates of LAC post-treated by nitrogen plasma are inferior to the air plasma-treated LAC.

Genome engineering using a synthetic gene circuit in Bacillus subtilis.

PubMed

Jeong, Da-Eun; Park, Seung-Hwan; Pan, Jae-Gu; Kim, Eui-Joong; Choi, Soo-Keun

2015-03-31

Genome engineering without leaving foreign DNA behind requires an efficient counter-selectable marker system. Here, we developed a genome engineering method in Bacillus subtilis using a synthetic gene circuit as a counter-selectable marker system. The system contained two repressible promoters (B. subtilis xylA (Pxyl) and spac (Pspac)) and two repressor genes (lacI and xylR). Pxyl-lacI was integrated into the B. subtilis genome with a target gene containing a desired mutation. The xylR and Pspac-chloramphenicol resistant genes (cat) were located on a helper plasmid. In the presence of xylose, repression of XylR by xylose induced LacI expression, the LacIs repressed the Pspac promoter and the cells become chloramphenicol sensitive. Thus, to survive in the presence of chloramphenicol, the cell must delete Pxyl-lacI by recombination between the wild-type and mutated target genes. The recombination leads to mutation of the target gene. The remaining helper plasmid was removed easily under the chloramphenicol absent condition. In this study, we showed base insertion, deletion and point mutation of the B. subtilis genome without leaving any foreign DNA behind. Additionally, we successfully deleted a 2-kb gene (amyE) and a 38-kb operon (ppsABCDE). This method will be useful to construct designer Bacillus strains for various industrial applications. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Application of Zoning and ``Limits of Acceptable Change'' to Manage Snorkelling Tourism

NASA Astrophysics Data System (ADS)

Roman, George S. J.; Dearden, Philip; Rollins, Rick

2007-06-01

Zoning and applying Limits of Acceptable Change (LAC) are two promising strategies for managing tourism in Marine Protected Areas (MPAs). Typically, these management strategies require the collection and integration of ecological and socioeconomic data. This problem is illustrated by a case study of Koh Chang National Marine Park, Thailand. Biophysical surveys assessed coral communities in the MPA to derive indices of reef diversity and vulnerability. Social surveys assessed visitor perceptions and satisfaction with conditions encountered on snorkelling tours. Notably, increased coral mortality caused a significant decrease in visitor satisfaction. The two studies were integrated to prescribe zoning and “Limits of Acceptable Change” (LAC). As a biophysical indicator, the data suggest a LAC value of 0.35 for the coral mortality index. As a social indicator, the data suggest that a significant fraction of visitors would find a LAC value of under 30 snorkellers per site as acceptable. The draft zoning plan prescribed four different types of zones: (I) a Conservation Zone with no access apart from monitoring or research; (II) Tourism Zones with high tourism intensities at less vulnerable reefs; (III) Ecotourism zones with a social LAC standard of <30 snorkellers per site, and (IV) General Use Zones to meet local artisanal fishery needs. This study illustrates how ecological and socioeconomic field studies in MPAs can be integrated to craft zoning plans addressing multiple objectives.

Application of zoning and "limits of acceptable change" to manage snorkelling tourism.

PubMed

Roman, George S J; Dearden, Philip; Rollins, Rick

2007-06-01

Zoning and applying Limits of Acceptable Change (LAC) are two promising strategies for managing tourism in Marine Protected Areas (MPAs). Typically, these management strategies require the collection and integration of ecological and socioeconomic data. This problem is illustrated by a case study of Koh Chang National Marine Park, Thailand. Biophysical surveys assessed coral communities in the MPA to derive indices of reef diversity and vulnerability. Social surveys assessed visitor perceptions and satisfaction with conditions encountered on snorkelling tours. Notably, increased coral mortality caused a significant decrease in visitor satisfaction. The two studies were integrated to prescribe zoning and "Limits of Acceptable Change" (LAC). As a biophysical indicator, the data suggest a LAC value of 0.35 for the coral mortality index. As a social indicator, the data suggest that a significant fraction of visitors would find a LAC value of under 30 snorkellers per site as acceptable. The draft zoning plan prescribed four different types of zones: (I) a Conservation Zone with no access apart from monitoring or research; (II) Tourism Zones with high tourism intensities at less vulnerable reefs; (III) Ecotourism zones with a social LAC standard of <30 snorkellers per site, and (IV) General Use Zones to meet local artisanal fishery needs. This study illustrates how ecological and socioeconomic field studies in MPAs can be integrated to craft zoning plans addressing multiple objectives.

Desulfovibrio zosterae sp. nov., a new sulfate reducer isolated from surface-sterilized roots of the seagrass Zostera marina.

PubMed

Nielsen, J T; Liesack, W; Finster, K

1999-04-01

A sulfate-reducing bacterium, designated strain lacT, was isolated from surface-sterilized roots of the benthic macrophyte Zostera marina. Cells were motile by means of a single polar flagellum. Strain lacT utilized lactate, pyruvate, malate, ethanol, L-alanine, fumarate, choline and fructose with sulfate as electron acceptor. In addition, fumarate, pyruvate and fructose were also degraded without an external electron acceptor. Sulfate could be substituted with thiosulfate, sulfite and elemental sulfur. Optimal growth was observed between 32.5 and 34.5 degrees C, at an NaCl concentration of 0.2 M and in a pH range between 6.8 and 7.3. The G + C content of the DNA was 42.7 +/- 0.2 mol%. Desulfoviridin and catalase were present. Strain lacT contained c-type cytochromes. Comparative 16S rRNA gene sequence analysis and the fatty acid pattern grouped this isolate into the genus Desulfovibrio. However, strain lacT differs from all other described Desulfovibrio species on the bases of its 16S rRNA gene sequence, the G + C content, its cellular lipid pattern and the utilization pattern of substrates. These characteristics establish strain lacT (= DSM 11974T) as a novel species of the genus Desulfovibrio, for which the name Desulfovibrio zosterae sp. nov. is proposed.

A helper virus-free HSV-1 vector containing the vesicular glutamate transporter-1 promoter supports expression preferentially in VGLUT1-containing glutamatergic neurons.

PubMed

Zhang, Guo-rong; Geller, Alfred I

2010-05-17

Multiple potential uses of direct gene transfer into neurons require restricting expression to specific classes of glutamatergic neurons. Thus, it is desirable to develop vectors containing glutamatergic class-specific promoters. The three vesicular glutamate transporters (VGLUTs) are expressed in distinct populations of neurons, and VGLUT1 is the predominant VGLUT in the neocortex, hippocampus, and cerebellar cortex. We previously reported a plasmid (amplicon) Herpes Simplex Virus (HSV-1) vector that placed the Lac Z gene under the regulation of the VGLUT1 promoter (pVGLUT1lac). Using helper virus-free vector stocks, we showed that this vector supported approximately 90% glutamatergic neuron-specific expression in postrhinal (POR) cortex, in rats sacrificed at either 4 days or 2 months after gene transfer. We now show that pVGLUT1lac supports expression preferentially in VGLUT1-containing glutamatergic neurons. pVGLUT1lac vector stock was injected into either POR cortex, which contains primarily VGLUT1-containing glutamatergic neurons, or into the ventral medial hypothalamus (VMH), which contains predominantly VGLUT2-containing glutamatergic neurons. Rats were sacrificed at 4 days after gene transfer, and the types of cells expressing ss-galactosidase were determined by immunofluorescent costaining. Cell counts showed that pVGLUT1lac supported expression in approximately 10-fold more cells in POR cortex than in the VMH, whereas a control vector supported expression in similar numbers of cells in these two areas. Further, in POR cortex, pVGLUT1lac supported expression predominately in VGLUT1-containing neurons, and, in the VMH, pVGLUT1lac showed an approximately 10-fold preference for the rare VGLUT1-containing neurons. VGLUT1-specific expression may benefit specific experiments on learning or specific gene therapy approaches, particularly in the neocortex. Copyright 2010 Elsevier B.V. All rights reserved.

Mouse models of aerosol-acquired tularemia caused by Francisella tularensis types A and B.

PubMed

Fritz, David L; England, Marilyn J; Miller, Lynda; Waag, David M

2014-10-01

After preliminary assessment of virulence in AKR/J, DBA/1, BALB/c, and C57BL/6 mice, we investigated histopathologic changes in BALB/c and C57BL/6 mice infected with type A (strain SCHU S4) or type B (strain 425) Francisella tularensis by aerosol exposure. In mice exposed to type A infection, changes in histologic presentation were not apparent until day 3 after infection, when pyogranulomatous inflammation was detected in spleens and livers of BALB/c mice, and in lungs and spleens of C57BL/6 mice. Histopathologic changes were most severe and widespread in both mouse strains on day 5 after infection and seemed to completely resolve within 22 d of challenge. BALB/c mice were more resistant than C57BL/6 mice in lethal-dose calculations, but C57BL/6 mice cleared the infection more rapidly. Mice similarly challenged with type B F. tularensis also developed histopathologic signs of infection beginning on day 3. The most severe changes were noted on day 8 and were characterized by granulomatous or pyogranulomatous infiltrations of the lungs. Unlike type A infection, lesions due to type B did not resolve over time and remained 3 wk after infection. In type B, but not type A, infection we noted extensive inflammation of the heart muscle. Although no microorganisms were found in tissues of type A survivors beyond 9 d after infection, mice surviving strain 425 infection had a low level of residual infection at 3 wk after challenge. The histopathologic presentation of tularemia caused by F. tularensis types A and B in BALB/c and C57BL/6 mice bears distinct similarities to tularemia in humans.

MAXI/GSC detection of a rapid X-ray brightening from Mrk 421

NASA Astrophysics Data System (ADS)

Tachibana, Y.; Ueda, Y.; Negoro, H.; Ueno, S.; Tomida, H.; Ishikawa, M.; Sugawara, Y.; Isobe, N.; Shimomukai, R.; Mihara, T.; Sugizaki, M.; Nakahira, S.; Iwakiri, W.; Shidatsu, M.; Yatabe, F.; Takao, Y.; Matsuoka, M.; Kawai, N.; Sugita, S.; Yoshii, T.; Harita, S.; Muraki, Y.; Morita, K.; Yoshida, A.; Sakamoto, T.; Serino, M.; Kawakubo, Y.; Kitaoka, Y.; Hashimoto, T.; Tsunemi, H.; Yoneyama, T.; Nakajima, M.; Kawase, T.; Sakamaki, A.; Hori, T.; Tanimoto, A.; Oda, S.; Morita, T.; Yamada, S.; Tsuboi, Y.; Nakamura, Y.; Sasaki, R.; Kawai, H.; Sato, T.; Yamauchi, M.; Hanyu, C.; Hidaka, K.; Kawamuro, T.; Yamaoka, K.

2018-01-01

MAXI/GSC is detecting a bright X-ray flare from the BL Lac object Mrk 421. The MAXI daily fluxes for the last 5 days are following: MJD & emsp; 2-4 keV (mCrab) & emsp; 4-10 keV (mCrab) 58131 & emsp; 53 +- 5 & emsp; 52 +- 6 58132 & emsp; 34 +- 5 & emsp; 29 +- 5 58133 & emsp; 56 +- 5 & emsp; 53 +- 6 58134 & emsp; 91 +- 7 & emsp; 98 +- 7 58135 & emsp; 106 +- 8 & emsp; 124 +- 9 The current flux is comparable with the peak daily flux in the brightest X-ray flare from this object ever since the beginning of the MAXI observation (156 +- 11 mCrab in 1.5-10 keV on 2010 February 16, ATEL #2444; Isobe et al. 2010 PASJ 52, L55), and the X-ray brightening is still ongoing.

QUASI-PERIODIC OSCILLATIONS OF {approx}15 MINUTES IN THE OPTICAL LIGHT CURVE OF THE BL LAC S5 0716+714

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, Bindu; Gupta, Alok C.; Joshi, U. C.

Over the course of 3 hr on 2008 December 27, we obtained optical (R band) observations of the blazar S5 0716+714 at a very fast cadence of 10 s. Using several different techniques, we find fluctuations with an approximately 15 minute quasi-period to be present in the first portion of these data at a >3{sigma} confidence level. This is the fastest quasi-periodic oscillation that has been claimed to be observed in any blazar at any wavelength. While these data are insufficient to strongly constrain models for such fluctuations, the presence of such a short timescale when the source is notmore » in a very low state seems to favor the action of turbulence behind a shock in the blazar's relativistic jet.« less

Multiwavelength and Statistical Research in Space Astrophysics

NASA Technical Reports Server (NTRS)

Feigelson, Eric D.

1997-01-01

The accomplishments in the following three research areas are summarized: multiwavelength study of active galactic nuclei; magnetic activity of young stellar objects; and statistical methodology for astronomical data analysis. The research is largely based on observations of the ROSAT and ASCA X-ray observatories, complemented by ground-based optical and radio studies. Major findings include: discovery of inverse Compton X-ray emission from radio galaxy lobes; creation of the largest and least biased available sample of BL Lac objects; characterization of X-ray and nonthermal radio emission from T Tauri stars; obtaining an improved census of young stars in a star forming region and modeling the star formation history and kinematics; discovery of X-ray emission from protostars; development of linear regression methods and codes for interpreting astronomical data; and organization of the first cross-disciplinary conferences for astronomers and statisticians.

Inactivation of carotenoid-producing and albino strains of Neurospora crassa by visible light, blacklight, and ultraviolet radiation.

PubMed Central

Blanc, P L; Tuveson, R W; Sargent, M L

1976-01-01

Suspensions of Neurospora crassa conidia were inactivated by blacklight (BL) radiation (300 to 425 nm) in the absence of exogenous photosensitizing compounds. Carotenoid-containing wild-type conidia were less sensitive to BL radiation than albino conidia, showing a dose enhancement factor (DEF) of 1.2 for dose levels resulting in less than 10% survival. The same strains were about equally sensitive to shortwave ultraviolet (UV) inactivation. The kinetics of BL inactivation are similar to those of photodynamic inactivation by visible light in the presence of a photosensitizing dye (methylene blue). Only limited inactivation by visible light in the absence of exogenous photosensitizers was observed. BL and UV inactivations are probably caused by different mechanisms since wild-type conidia are only slightly more resistant to BL radiation (DEF = 1.2 at 1.0% survival) than are conidia from a UV-sensitive strain (upr-1, uvs-3). The BL-induced lethal lesions are probably no cyclobutyl pyrimidine dimers since BL-inactivated Haemophilus influenzae transforming deoxyribonucleic acid is not photoreactivated by N. crassa wild-type enzyme extracts, whereas UV-inactivated transforming deoxyribonucleic acid is photoreactivable with this treatment. PMID:128556

The mouse Gtl2 gene is differentially expressed during embryonic development, encodes multiple alternatively spliced transcripts, and may act as an RNA.

PubMed

Schuster-Gossler, K; Bilinski, P; Sado, T; Ferguson-Smith, A; Gossler, A

1998-06-01

We have isolated a novel mouse gene (Gtl2) from the site of a gene trap integration (Gtl2lacZ) that gave rise to developmentally regulated lacZ expression, and a dominant parental-origin-dependent phenotype. Heterozygous Gtl2lacZ mice that inherited the transgene from the father showed a proportionate dwarfism phenotype, whereas the penetrance and expressivity of the phenotype was strongly reduced in Gtl2lacZ mice that inherited the transgene from the mother. Gtl2 expression is highly similar to the beta-galactosidase staining pattern, and is down-regulated but not abolished in mice carrying the Gtl2lacZ insertion. In early postimplantation embryos, Gtl2 is expressed in the visceral yolk sac and embryonic ectoderm. During subsequent development and organogenesis, Gtl2 transcripts are abundant in the paraxial mesoderm closely correlated with myogenic differentiation, in parts of the central nervous system, and in the epithelial ducts of developing excretory organs. The Gtl2 gene gives rise to various differentially spliced transcripts, which contain multiple small open reading frames (ORF). However, none of the ATG codons of these ORFs is in the context of a strong Kozak consensus sequence for initiation of translation, suggesting that Gtl2 might function as an RNA. Nuclear Gtl2 RNA was detected in a temporally and spatially regulated manner, and partially processed Gtl2 transcripts were readily detected in Northern blot hybridizations of polyadenylated RNA, suggesting that primary Gtl2 transcripts are differently processed in various cell types during development. Gtl2 transcript levels are present in parthenogenic embryos but may be reduced, consistent with the pattern of inheritance of the Gtl2lacZ phenotype.

Lactose metabolism by Staphylococcus aureus: characterization of lacABCD, the structural genes of the tagatose 6-phosphate pathway.

PubMed Central

Rosey, E L; Oskouian, B; Stewart, G C

1991-01-01

The nucleotide and deduced amino acid sequences of the lacA and lacB genes of the Staphylococcus aureus lactose operon (lacABCDFEG) are presented. The primary translation products are polypeptides of 142 (Mr = 15,425) and 171 (Mr = 18,953) amino acids, respectively. The lacABCD loci were shown to encode enzymes of the tagatose 6-phosphate pathway through both in vitro studies and complementation analysis in Escherichia coli. A serum aldolase assay, modified to allow detection of the tagatose 6-phosphate pathway enzymes utilizing galactose 6-phosphate or fructose phosphate analogs as substrate, is described. Expression of both lacA and lacB was required for galactose 6-phosphate isomerase activity. LacC (34 kDa) demonstrated tagatose 6-phosphate kinase activity and was found to share significant homology with LacC from Lactococcus lactis and with both the minor 6-phosphofructokinase (PfkB) and 1-phosphofructokinase (FruK) from E. coli. Detection of tagatose 1,6-bisphosphate aldolase activity was dependent on expression of the 36-kDa protein specified by lacD. The LacD protein is highly homologous with LacD of L. lactis. Thus, the lacABCD genes comprise the tagatose 6-phosphate pathway and are cotranscribed with genes lacFEG, which specify proteins for transport and cleavage of lactose in S. aureus. PMID:1655695

Genome-Wide Identification and Characterization of Novel Laccase Genes in the White-Rot Fungus Flammulina velutipes

PubMed Central

Kim, Hong-Il; Kwon, O-Chul; Kong, Won-Sik; Lee, Chang-Soo

2014-01-01

The aim of this study was to identify and characterize new Flammulina velutipes laccases from its whole-genome sequence. Of the 15 putative laccase genes detected in the F. velutipes genome, four new laccase genes (fvLac-1, fvLac-2, fvLac3, and fvLac-4) were found to contain four complete copper-binding regions (ten histidine residues and one cysteine residue) and four cysteine residues involved in forming disulfide bridges, fvLac-1, fvLac-2, fvLac3, and fvLac-4, encoding proteins consisting of 516, 518, 515, and 533 amino acid residues, respectively. Potential N-glycosylation sites (Asn-Xaa-Ser/Thr) were identified in the cDNA sequence of fvLac-1 (Asn-454), fvLac-2 (Asn-437 and Asn-455), fvLac-3 (Asn-111 and Asn-237), and fvLac4 (Asn-402 and Asn-457). In addition, the first 19~20 amino acid residues of these proteins were predicted to comprise signal peptides. Laccase activity assays and reverse transcription polymerase chain reaction analyses clearly reveal that CuSO4 affects the induction and the transcription level of these laccase genes. PMID:25606003

Engineering an allosteric transcription factor to respond to new ligands.

PubMed

Taylor, Noah D; Garruss, Alexander S; Moretti, Rocco; Chan, Sum; Arbing, Mark A; Cascio, Duilio; Rogers, Jameson K; Isaacs, Farren J; Kosuri, Sriram; Baker, David; Fields, Stanley; Church, George M; Raman, Srivatsan

2016-02-01

Genetic regulatory proteins inducible by small molecules are useful synthetic biology tools as sensors and switches. Bacterial allosteric transcription factors (aTFs) are a major class of regulatory proteins, but few aTFs have been redesigned to respond to new effectors beyond natural aTF-inducer pairs. Altering inducer specificity in these proteins is difficult because substitutions that affect inducer binding may also disrupt allostery. We engineered an aTF, the Escherichia coli lac repressor, LacI, to respond to one of four new inducer molecules: fucose, gentiobiose, lactitol and sucralose. Using computational protein design, single-residue saturation mutagenesis or random mutagenesis, along with multiplex assembly, we identified new variants comparable in specificity and induction to wild-type LacI with its inducer, isopropyl β-D-1-thiogalactopyranoside (IPTG). The ability to create designer aTFs will enable applications including dynamic control of cell metabolism, cell biology and synthetic gene circuits.

Engineering an allosteric transcription factor to respond to new ligands

PubMed Central

Taylor, Noah D; Garruss, Alexander S; Moretti, Rocco; Chan, Sum; Arbing, Mark A; Cascio, Duilio; Rogers, Jameson K; Isaacs, Farren J; Kosuri, Sriram; Baker, David; Fields, Stanley; Church, George M; Raman, Srivatsan

2016-01-01

Genetic regulatory proteins inducible by small molecules are useful synthetic biology tools as sensors and switches. Bacterial allosteric transcription factors (aTFs) are a major class of regulatory proteins, but few aTFs have been redesigned to respond to new effectors beyond natural aTF-inducer pairs. Altering inducer specificity in these proteins is difficult because substitutions that affect inducer binding may also disrupt allostery. We engineered an aTF, the Escherichia coli lac repressor, LacI, to respond to one of four new inducer molecules: fucose, gentiobiose, lactitol or sucralose. Using computational protein design, single-residue saturation mutagenesis or random mutagenesis, along with multiplex assembly, we identified new variants comparable in specificity and induction to wild-type LacI with its inducer, isopropyl β-D-1-thiogalactopyranoside (IPTG). The ability to create designer aTFs will enable applications including dynamic control of cell metabolism, cell biology and synthetic gene circuits. PMID:26689263

Behavioral characterization of mice deficient in the phosphodiesterase-10A (PDE10A) enzyme on a C57/Bl6N congenic background.

PubMed

Siuciak, Judith A; McCarthy, Sheryl A; Chapin, Douglas S; Martin, Ashley N; Harms, John F; Schmidt, Christopher J

2008-02-01

The phenotype of genetically modified animals is strongly influenced by both the genetic background of the animal as well as environmental factors. We have previously reported the behavioral and neurochemical characterization of PDE10A knockout mice maintained on a DBA1LacJ (PDE10A(DBA)) genetic background. The aim of the present studies was to assess the behavioral and neurochemical phenotype of PDE10A knockout mice on an alternative congenic C57BL/6N (PDE10A(C57)) genetic background. Consistent with our previous results, PDE10A(C57) knockout mice showed a decrease in exploratory locomotor activity and a delay in the acquisition of conditioned avoidance responding. Also consistent with previous studies, the elimination of PDE10A did not alter basal levels of striatal cGMP or cAMP or affect behavior in several other well-characterized behavioral assays. PDE10A(C57) knockout mice showed a blunted response to MK-801, although to a lesser degree than previously observed in the PDE10A(DBA) knockout mice, and no differences were observed following a PCP challenge. PDE10A(C57) knockout mice showed a significant change in striatal dopamine turnover, which was accompanied by an enhanced locomotor response to AMPH, These studies demonstrate that while many of the behavioral effects of the PDE10A gene deletion appear to be independent of genetic background, the impact of the deletion on behavior can vary in magnitude. Furthermore, the effects on the dopaminergic system appear to be background-dependent, with significant effects observed only in knockout mice on the C57BL6N genetic background.

Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis.

PubMed

Lü, Shiyou; Song, Tao; Kosma, Dylan K; Parsons, Eugene P; Rowland, Owen; Jenks, Matthew A

2009-08-01

Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8/LACS1, one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C(24)) were elevated more than 155%. The C(16) cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C(18) monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C(20)-C(30), with highest activity for C(30) acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C(16) but not C(18) cutin monomers are reduced in lacs1, and C(16) acids are the next most preferred acid (behind C(30)) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C(16) monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C(16)) fatty acids for cutin synthesis.

[Searching for Rare Celestial Objects Automatically from Stellar Spectra of the Sloan Digital Sky Survey Data Release Eight].

PubMed

Si, Jian-min; Luo, A-li; Wu, Fu-zhao; Wu, Yi-hong

2015-03-01

There are many valuable rare and unusual objects in spectra dataset of Sloan Digital Sky Survey (SDSS) Data Release eight (DR8), such as special white dwarfs (DZ, DQ, DC), carbon stars, white dwarf main-sequence binaries (WDMS), cataclysmic variable (CV) stars and so on, so it is extremely significant to search for rare and unusual celestial objects from massive spectra dataset. A novel algorithm based on Kernel dense estimation and K-nearest neighborhoods (KNN) has been presented, and applied to search for rare and unusual celestial objects from 546 383 stellar spectra of SDSS DR8. Their densities are estimated using Gaussian kernel density estimation, the top 5 000 spectra in descend order by their densities are selected as rare objects, and the top 300 000 spectra in ascend order by their densities are selected as normal objects. Then, KNN were used to classify the rest objects, and simultaneously K nearest neighbors of the 5 000 rare spectra are also selected as rare objects. As a result, there are totally 21 193 spectra selected as initial rare spectra, which include error spectra caused by deletion, redden, bad calibration, spectra consisting of different physically irrelevant components, planetary nebulas, QSOs, special white dwarfs (DZ, DQ, DC), carbon stars, white dwarf main-sequence binaries (WDMS), cataclysmic variable (CV) stars and so on. By cross identification with SIMBAD, NED, ADS and major literature, it is found that three DZ white dwarfs, one WDMS, two CVs with company of G-type star, three CVs candidates, six DC white dwarfs, one DC white dwarf candidate and one BL Lacertae (BL lac) candidate are our new findings. We also have found one special DA white dwarf with emission lines of Ca II triple and Mg I, and one unknown object whose spectrum looks like a late M star with emission lines and its image looks like a galaxy or nebula.

Rapid, synchronous, and stable induction of type 1 piliation in Escherichia coli by using a chromosomal lacUV5 promoter.

PubMed Central

Woodall, L D; Russell, P W; Harris, S L; Orndorff, P E

1993-01-01

Type 1 pili are filamentous proteinaceous appendages produced by certain members of the family Enterobacteriaceae. In Escherichia coli, the adhesive properties of these pili are due to the binding of at least one minor pilus component to mannose, a sugar common to cell surface molecules of many eukaryotic cells. The study of pilus assembly may be benefited by a rapid way of inducing pilus synthesis de novo. We describe herein the construction and characterization of a strain in which piliation can be rapidly induced by the addition of lactose or its analog isopropyl-beta-D-thiogalactopyranoside. This was accomplished by placing the chromosomal fimA gene (encoding the major structural subunit of pili) under lacUV5 promoter control. Further experiments suggested that transcription of genes downstream of fimA, whose products are required for normal pilus assembly and function, may also be controlled by the lacUV5 promoter. The construction described herein may have a variety of applications apart from aiding the study of pilus assembly since its adhesive properties can be rapidly and easily turned on and off. Images PMID:8097517

Louisiana SIP: LAC 33:III Ch. 14 Subchap A, 1401 to 1415--Determining Conformity of General Federal Actions to State or Federal Implementation Plans; SIP effective 1996-11-12 (LAc67) and 1998-05-08 (LAc75)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch. 14 Subchap A, 1401 to 1415--Determining Conformity of General Federal Actions to State or Federal Implementation Plans; SIP effective 1996-11-12 (LAc67) and 1998-05-08 (LAc75)

Novel interactions of complex carbohydrates with peanut (PNA), Ricinus communis (RCA-I), Sambucus nigra (SNA-I) and wheat germ (WGA) agglutinins as revealed by the binding specificities of these lectins towards mucin core-2 O-linked and N-linked glycans and related structures.

PubMed

Chandrasekaran, E V; Xue, Jun; Xia, Jie; Khaja, Siraj D; Piskorz, Conrad F; Locke, Robert D; Neelamegham, Sriram; Matta, Khushi L

2016-10-01

Plant lectins through their multivalent quaternary structures bind intrinsically flexible oligosaccharides. They recognize fine structural differences in carbohydrates and interact with different sequences in mucin core 2 or complex-type N-glycan chain and also in healthy and malignant tissues. They are used in characterizing cellular and extracellular glycoconjugates modified in pathological processes. We study here, the complex carbohydrate-lectin interactions by determining the effects of substituents in mucin core 2 tetrasaccharide Galβ1-4GlcNAcβ1-6(Galβ1-3)GalNAcα-O-R and fetuin glycopeptides on their binding to agarose-immobilized lectins PNA, RCA-I, SNA-I and WGA. Briefly, in mucin core 2 tetrasaccharide (i) structures modified by α2-3/6-Sialyl LacNAc, LewisX and α1-3-Galactosyl LacNAc resulted in regular binding to PNA whereas compounds with 6-sulfo LacNAc displayed no-binding; (ii) strucures bearing α2-6-sialyl 6-sulfo LacNAc, or 6-sialyl LacdiNAc carbohydrates displayed strong binding to SNA-I; (iii) structures with α2-3/6-sialyl, α1-3Gal LacNAc or LewisX were non-binder to RCA-I and compounds with 6-sulfo LacNAc only displayed weak binding; (iv) structures containing LewisX, 6-Sulfo LewisX, α2-3/6-sialyl LacNAc, α2-3/6-sialyl 6-sulfo LacNAc and GalNAc Lewis-a were non-binding to WGA, those with α1-2Fucosyl, α1-3-Galactosyl LacNAc, α2-3-sialyl T-hapten plus 3'/6'sulfo LacNAc displayed weak binding, and compounds with α2-3-sialyl T-hapten, α2.6-Sialyl LacdiNAc, α2-3-sialyl D-Fucβ1-3 GalNAc and Fucα-1-2 D-Fucβ-1-3GalNAc displaying regular binding and GalNAc LewisX and LacdiNAc plus D-Fuc β-1-3 GalNAcα resulting in tight binding. RCA-I binds Fetuin triantennary asialoglycopeptide 100 % after α-2-3 and 25 % after α-2-6 sialylation, 30 % after α-1-2 and 100 % after α-1-3 fucosylation, and 50 % after α-1-3 galactosylation. WGA binds 3-but not 6-Fucosyl chitobiose core. Thus, information on the influence of complex carbohydrate chain constituents on lectin binding is apparently essential for the potential application of lectins in glycoconjugate research.

Cooperative DNA binding of heterologous proteins: Evidence for contact between the cyclic AMP receptor protein and RNA polymerase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Y.L.; Garges, S.; Adhya, S.

1988-06-01

Four cAMP-independent receptor protein mutants (designated CRP* mutants) isolated previously are able to activate in vivo gene transcription in the absence of cAMP and their activity can be enhanced by cAMP or cGMP. One of the four mutant proteins, CRP*598 (Arg-142 to His, Ala-144 to Thr), has been characterized with regard to its conformational properties and ability to bind to and support abortive initiation from the lac promoter. Binding of wild-type CRP to its site on the lac promoter and activation of abortive initiation by RNA polymerase on this promoter are effected by cAMP but not by cGMP. CRP*598 canmore » activate lacP{sup +}-directed abortive initiation in the presence of cAMP and less efficiently in the presence of cGMP or in the absence of cyclic nucleotide. DNase I protection (footprinting) indicates that cAMP-CRP* binds to its site on the lac promoter whereas unliganded CRP* and cGMP-CRP* form a stable complex with the ({sup 32}P)lacP{sup +} fragment only in the presence of RNA polymerase, showing cooperative binding of two heterologous proteins. This cooperative binding provides strong evidence for a contact between CRP and RNA polymerase for activation of transcription. Although cGMP binds to CRP, it cannot replace cAMP in effecting the requisite conformational transition necessary for site-specific promoter binding.« less

A selective, non-peptide CRF receptor 1 antagonist prevents sodium lactate-induced acute panic-like responses.

PubMed

Shekhar, Anantha; Johnson, Philip L; Fitz, Stephanie D; Nakazato, Atsuro; Chaki, Shigeyuki; Steckler, Thomas; Schmidt, Mark

2011-04-01

Corticotropin releasing factor (CRF) is implicated in a variety of stress-related disorders such as depression and anxiety, and blocking CRF receptors is a putative strategy for treating such disorders. Using a well-studied animal model of panic, we tested the efficacy of JNJ19567470/CRA5626, a selective, non-peptidergic CRF type 1 receptor (CRF1) antagonist (3, 10 and 40 mg/kg intraperitoneal injection), in preventing the sodium lactate (NaLac)-induced panic-like behavioural and cardiovascular responses. Adult male rats with chronic reduction of GABA levels (by inhibition of GABA synthesis with l-allyglycine, a glutamic acid decarboxylase inhibitor) in the dorsomedial/perifornical hypothalamus are highly anxious and exhibit physiological and behavioural responses to intravenous NaLac infusions similar to patients with panic disorder. These 'panic-prone' rats pre-treated with vehicle injections displayed NaLac-induced increases in autonomic responses (i.e. tachycardia and hypertensive responses), anxiety-like behaviour in the social interaction test, and flight-like increases in locomotor activity. However, systemically injecting such panic-prone rats with the highest dose of CRF1 receptor antagonist prior to NaLac infusions blocked all NaLac-induced behaviour and cardiovascular responses. These data suggest that selective CRF1 receptor antagonists could be a novel target for developing anti-panic drugs that are as effective as benzodiazepines in acute treatment of a panic attack without the deleterious side-effects (e.g. sedation and cognitive impairment) associated with benzodiazepines.

Risk factors for human papillomavirus exposure and co-factors for cervical cancer in Latin America and the Caribbean.

PubMed

Almonte, Maribel; Albero, Ginesa; Molano, Mónica; Carcamo, César; García, Patricia J; Pérez, Gonzalo

2008-08-19

The incidence of cervical cancer in Latin America and the Caribbean (LAC) is among the highest in the world. Because there are major demographic shifts happening in LAC countries (population growth, urbanization and ageing) cervical cancer incidence and mortality will likely continue to be a significant public health problem. Overall human papillomavirus (HPV) prevalence in the LAC general population has been found to be 2-fold higher than the average worldwide prevalence. The large HPV and cancer burden may be explained by the highly prevalent HPV variants of HPV types -16 and 18, which have an increased oncogenic potential. Given the major mode of transmission of genital HPV is sexual, certain, patterns of sexual behaviour (early age at first sexual intercourse, number of sexual partners and sexual behaviour of the partner) are associated with an increased risk of HPV genital acquisition. Although HPV infection is necessary for carcinogenesis, certain co-factors (high parity, long term use of oral contraceptives, smoking and co-infection with the human immunodeficiency virus (HIV)) help in the progression from infection to cancer. Many studies that have contributed to this evidence have been carried out in LAC and are reviewed and summarised in this article. Since HPV vaccines will likely take years to implement, and many more years to show impact on disease, cervical cancer screening programmes remain as the key intervention to control disease in LAC in the years to come.

Hereditary tyrosinemia type I: strong association with haplotype 6 in French Canadians permits simple carrier detection and prenatal diagnosis.

PubMed Central

Demers, S. I.; Phaneuf, D.; Tanguay, R. M.

1994-01-01

Hereditary tyrosinemia type 1 (HT1), a severe inborn error of tyrosine catabolism, is caused by deficiency of the terminal enzyme, fumarylacetoacetate hydrolase (FAH). The highest reported frequency of HT1 is in the French Canadian population, especially in the Saguenay-Lac-St-Jean region. Using human FAH cDNA probes, we have identified 10 haplotypes with TaqI, KpnI, RsaI, BglII, and MspI RFLPs in 118 normal chromosomes from the French Canadian population. Interestingly, in 29 HT1 children, a prevalent haplotype, haplotype 6, was found to be strongly associated with the disease, at a frequency of 90% of alleles, as compared with approximately 18% in 35 control individuals. This increased to 96% in the 24 patients originating from Saguenay-Lac-St-Jean. These results suggest that one or only a few prevailing mutations are responsible for most of the HT1 cases in Saguenay-Lac-St-Jean. Since most patients were found to be homozygous for a specific haplotype in this population, FAH RFLPs have permitted simple carrier detection in nine different informative HT1 families, with a confidence level of 99.9%. Heterozygosity rate values obtained from 52 carriers indicated that approximately 88% of families at risk from Saguenay-Lac-St-Jean are fully or partially informative. Prenatal diagnosis was also achieved in an American family. Analysis of 24 HT1 patients from nine countries gave a frequency of approximately 52% for haplotype 6, suggesting a relatively high association, worldwide, of HT1 with this haplotype. Images Figure 1 PMID:7913582

ERE environment- and cell type-specific transcriptional effects of estrogen in normal endometrial cells.

PubMed

Lascombe, I; Sallot, M; Vuillermoz, C; Weisz, A; Adessi, G L; Jouvenot, M

1998-04-30

Our previous results have suggested a repression of E2 (17beta-estradiol) effect on the c-fos gene of cultured guinea-pig endometrial cells. To investigate this repression, the expression of three human c-fos gene recombinants, pFC1-BL (-2250/+41), pFC2-BL (-1400/+41) and pFC2E (-1300/-1050 and -230/+41), known to be E2-responsive in Hela cells, was studied in stromal (SC) and glandular epithelial cells (GEC). In both cellular types, pFC1-BL was not induced by E2, even in the presence of growth factors or co-transfected estrogen receptor. The pattern of pFC2-BL and pFC2E expression was strikingly different and depended on the cellular type: pFC2-BL and pFC2E induction was restricted to the glandular epithelial cells and did not occur in the SCs. We argue for a repression of E2 action which is dependent on the estrogen-responsive cis-acting element (ERE) environment and also cell type-specific involving DNA/protein and/or protein/protein interactions with cellular type-specific factors.

lac operon induction in Escherichia coli: Systematic comparison of IPTG and TMG induction and influence of the transacetylase LacA.

PubMed

Marbach, Anja; Bettenbrock, Katja

2012-01-01

Most commonly used expression systems in bacteria are based on the Escherichia coli lac promoter. Furthermore, lac operon elements are used today in systems and synthetic biology. In the majority of the cases the gratuitous inducers IPTG or TMG are used. Here we report a systematic comparison of lac promoter induction by TMG and IPTG which focuses on the aspects inducer uptake, population heterogeneity and a potential influence of the transacetylase, LacA. We provide induction curves in E. coli LJ110 and in isogenic lacY and lacA mutant strains and we show that both inducers are substrates of the lactose permease at low inducer concentrations but can also enter cells independently of lactose permease if present at higher concentrations. Using a gfp reporter strain we compared TMG and IPTG induction at single cell level and showed that bimodal induction with IPTG occurred at approximately ten-fold lower concentrations than with TMG. Furthermore, we observed that lac operon induction is influenced by the transacetylase, LacA. By comparing two Plac-gfp reporter strains with and without a lacA deletion we could show that in the lacA(+) strain the fluorescence level decreased after few hours while the fluorescence further increased in the lacA(-) strain. The results indicate that through the activity of LacA the IPTG concentration can be reduced below an inducing threshold concentration-an influence that should be considered if low inducer amounts are used. Copyright © 2011 Elsevier B.V. All rights reserved.

Crystal Structure and Substrate Specificity of D-Galactose-6-Phosphate Isomerase Complexed with Substrates

PubMed Central

Lee, Jung-Kul; Pan, Cheol-Ho

2013-01-01

D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays. PMID:24015281

Genome sequences of two closely related strains of Escherichia coli K-12 GM4792.

PubMed

Zhang, Yan-Cong; Zhang, Yan; Zhu, Bi-Ru; Zhang, Bo-Wen; Ni, Chuan; Zhang, Da-Yong; Huang, Ying; Pang, Erli; Lin, Kui

2015-01-01

Escherichia coli lab strains K-12 GM4792 Lac(+) and GM4792 Lac(-) carry opposite lactose markers, which are useful for distinguishing evolved lines as they produce different colored colonies. The two closely related strains are chosen as ancestors for our ongoing studies of experimental evolution. Here, we describe the genome sequences, annotation, and features of GM4792 Lac(+) and GM4792 Lac(-). GM4792 Lac(+) has a 4,622,342-bp long chromosome with 4,061 protein-coding genes and 83 RNA genes. Similarly, the genome of GM4792 Lac(-) consists of a 4,621,656-bp chromosome containing 4,043 protein-coding genes and 74 RNA genes. Genome comparison analysis reveals that the differences between GM4792 Lac(+) and GM4792 Lac(-) are minimal and limited to only the targeted lac region. Moreover, a previous study on competitive experimentation indicates the two strains are identical or nearly identical in survivability except for lactose utilization in a nitrogen-limited environment. Therefore, at both a genetic and a phenotypic level, GM4792 Lac(+) and GM4792 Lac(-), with opposite neutral markers, are ideal systems for future experimental evolution studies.

Extraction of organic materials from red water by metal-impregnated lignite activated carbon.

PubMed

Wei, Fangfang; Zhang, Yihe; Lv, Fengzhu; Chu, Paul K; Ye, Zhengfang

2011-12-15

Extraction of organic materials from 2,4,6-trinitrotoluene (TNT) red water by lignite activated carbon (LAC) impregnated with Cu(2+), Ba(2+), Sn(2+), Fe(3+), Ca(2+) and Ag(+) was investigated. The affinity to organic materials in red water was found to follow the order: Cu/LAC>Sn/LAC>Ag/LAC>Ba/LAC>Fe/LAC>Ca/LAC, which was explained by the hard and soft acid base (HSAB) theory. Cu(2+) showed the best performance and several parameters were further studied. X-ray photoelectron spectroscopy (XPS) verified effective loading of Cu(2+) on the LAC surface. The water quality before and after treated by Cu/LAC was evaluated using high performance liquid chromatograph, Gas Chromatography/Mass Spectroscopy (GC/MS), UV-vis spectroscopy and other analyses. The extraction performances and mechanism of organic materials on Cu/LAC were investigated through static methods. The experimental results showed that Cu/LAC possessed stronger extraction ability for the sulfonated nitrotoluenes than the non-sulfonated nitrotoluenes, the kinetic data fitted the pseudo-second-order kinetic model well. In addition, the leaching out of Cu(2+) from Cu/LAC was found much lower in the 100 times diluted red water (0.074%) than in the raw water (10.201%). Column adsorptions with more concentrated red water were also studied. Finally, Cu/LAC was observed to possess excellent reusability as well. Copyright © 2011 Elsevier B.V. All rights reserved.

Physical Parameters of Components in Close Binary Systems: IV

NASA Astrophysics Data System (ADS)

Gazeas, K. D.; Baran, A.; Niarchos, P.; Zola, S.; Kreiner, J. M.; Ogloza, W.; Rucinski, S. M.; Zakrzewski, B.; Siwak, M.; Pigulski, A.; Drozdz, M.

2005-03-01

The paper presents new geometric, photometric and absolute parameters, derived from combined spectroscopic and photometric solutions, for ten contact binary systems. The analysis shows that three systems (EF Boo, GM Dra and SW Lac) are of W-type with shallow to moderate contact. Seven systems (V417 Aql, AH Aur, YY CrB, UX Eri, DZ Psc, GR Vir and NN Vir) are of A-type in a deep contact configuration. For six systems (V417 Aql, YY CrB, GM Dra, UX Eri, SW Lac and GR Vir) a spot model is introduced to explain the O'Connell effect in their light curves. The photometric and geometric elements of the systems are combined with the spectroscopic data taken at David Dunlap Observatory to yield the absolute parameters of the components.

Identification and characterization of a locus which regulates multiple functions in Pseudomonas tolaasii, the cause of brown blotch disease of Agaricus bisporus.

PubMed Central

Grewal, S I; Han, B; Johnstone, K

1995-01-01

Pseudomonas tolaasii, the causal agent of brown blotch disease of Agaricus bisporus, spontaneously gives rise to morphologically distinct stable sectors, referred to as the phenotypic variant form, at the margins of the wild-type colonies. The phenotypic variant form is nonpathogenic and differs from the wild type in a range of biochemical and physiological characteristics. A genomic cosmid clone (pSISG29) from a wild-type P. tolaasii library was shown to be capable of restoring a range of characteristics of the phenotypic variant to those of the wild-type form, when present in trans. Subcloning and saturation mutagenesis analysis with Tn5lacZ localized a 3.0-kb region from pSISG29, designated the pheN locus, required for complementation of the phenotypic variant to the wild-type form. Marker exchange of the Tn5lacZ-mutagenized copy of the pheN locus into the wild-type strain demonstrated that a functional copy of the pheN gene is required to maintain the wild-type pathogenic phenotype and that loss of the pheN gene or its function results in conversion of the wild-type form to the phenotypic variant form. The pheN locus contained a 2,727-bp open reading frame encoding an 83-kDa protein. The predicted amino acid sequence of the PheN protein showed homology to the sensor and regulator domains of the conserved family of two component bacterial sensor regulator proteins. Southern hybridization analysis of pheN genes from the wild type and the phenotypic variant form revealed that DNA rearrangement occurs within the pheN locus during phenotypic variation. Analysis of pheN expression with a pheN::lacZ fusion demonstrated that expression is regulated by environmental factors. These results are related to a model for control for phenotypic variation in P. tolaasii. PMID:7642492

Discovery of Very High Energy Gamma-Ray Emission from Rbs 0723 with the Magic Telescopes

NASA Astrophysics Data System (ADS)

Mirzoyan, Razmik

2014-01-01

The MAGIC collaboration reports the discovery of very high energy (VHE; E>100 GeV) gamma-ray emission from RBS 0723 (RA: 08:47:12.9 DEC: +11:33:50, J2000.0) RBS 0723 is a BL Lac object at redshift z=0.198. The source has been detected by Fermi-LAT, in the Second Fermi-LAT source Catalogue (2FGL; Nolan et al. 2012) with F(>1 GeV) = (5.3+-1.2)e-10 cm^-2 s^-1 and with photon index 1.48+-0.16. It also belongs to the first Fermi-LAT catalog of >10 GeV sources (1FHL; Ackermann et al, 2013), showing a hard (photon index = 1.4 +- 0.4) and bright (photon flux = 9.6e-11 ph cm^-2 s^-1) emission above 10 GeV, and identified as a good candidate for VHE detection.

VLA observations of a complete sample of extragalactic X-ray sources. II

NASA Technical Reports Server (NTRS)

Schild, R.; Zamorani, G.; Gioia, I. M.; Feigelson, E. D.; Maccacaro, T.

1983-01-01

A complete sample of 35 X-ray selected sources found with the Einstein Observatory has been observed with the Very Large Array at 6 cm to investigate the relationship between radio and X-ray emission in extragalactic objects. Detections include three active galactic nuclei (AGNs), two clusters or groups of galaxies, two individual galaxies, and two BL Lac objects. The frequency of radio emission in X-ray selected AGNs is compared with that of optically selected quasars using the integral radio-optical luminosity function. The result suggests that the probability for X-ray selected quasars to be radio sources is higher than for those optically selected. No obvious correlation is found in the sample between the richness of X-ray luminosity of the cluster and the presence of a galaxy with radio luminosity at 5 GHz larger than 10 to the 30th ergs/s/Hz.

DERIVATION OF A RELATION FOR THE STEEPENING OF TeV-SELECTED BLAZAR {gamma}-RAY SPECTRA WITH ENERGY AND REDSHIFT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stecker, Floyd William; Scully, Sean T.

2010-02-01

We derive a relation for the steepening of blazar {gamma}-ray spectra between the multi-GeV Fermi energy range and the TeV energy range observed by atmospheric Cerenkov telescopes. The change in spectral index is produced by two effects: (1) an intrinsic steepening, independent of redshift, owing to the properties of emission and absorption in the source and (2) a redshift-dependent steepening produced by intergalactic pair production interactions of blazar {gamma}-rays with low-energy photons of the 'intergalactic background light' (IBL). Given this relation, with good enough data on the mean {gamma}-ray spectral energy distribution of TeV-selected BL Lac objects, the redshift evolutionmore » of the IBL can, in principle, be determined independently of stellar evolution models. We apply our relation to the results of new Fermi observations of TeV-selected blazars.« less

A change in the X-ray spectrum of MK 421

NASA Technical Reports Server (NTRS)

Mushotzky, R. F.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.

1979-01-01

HEAO-1 experiment A-2 observations of the BL Lac object MK421 in May 1978 show a marked spectral change from the OSO-8 observations of May 1977. The source was not detected above 10 keV in May 1978. The 2-10 keV spectrum could be well fit by a power law of energy slope 2.2 is less than or minus 4.2; thermal bremsstrahlung models with T less than 2 X 10 to the 7th power deg K are also acceptable. There was no indication of any low energy turnover, so that the inferred column density N sub H is less than 7 X 10 to the 21st power at/sq cm. The total flux is consistent with an extrapolation of the UV data from IUE, but the slope is not consistent with the UV slope. Possible models for the origin of the spectral transition are discussed.

OPTICAL SPECTRA OF CANDIDATE SOUTHERN HEMISPHERE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Jauncey, D. L.; Johnston, H. M.

2011-11-15

We present the results of spectroscopic observations of the optical counterparts of 47 southern radio sources from the candidate International Celestial Reference Catalogue as part of a very long baseline interferometry (VLBI) program to strengthen the celestial reference frame, especially in the south. We made the observations with the 3.58 m European Southern Observatory New Technology Telescope. We obtained redshifts for 30 quasars and one radio galaxy, with a further seven objects being probable BL Lac objects with featureless spectra. Of the remainder, four were clear misidentifications with Galactic stars and five had low signal-to-noise spectra and could not bemore » classified. These results, in combination with new VLBI data of the radio sources with redshifts more than 2, add significantly to the existing data needed to refine the distribution of source proper motions over the celestial sphere.« less

Linear Polarization Properties of Parsec-Scale AGN Jets

NASA Astrophysics Data System (ADS)

Pushkarev, Alexander; Kovalev, Yuri; Lister, Matthew; Savolainen, Tuomas; Aller, Margo; Aller, Hugh; Hodge, Mary

2017-12-01

We used 15 GHz multi-epoch Very Long Baseline Array (VLBA) polarization sensitive observations of 484 sources within a time interval 1996--2016 from the MOJAVE program, and also from the NRAO data archive. We have analyzed the linear polarization characteristics of the compact core features and regions downstream, and their changes along and across the parsec-scale active galactic nuclei (AGN) jets. We detected a significant increase of fractional polarization with distance from the radio core along the jet as well as towards the jet edges. Compared to quasars, BL Lacs have a higher degree of polarization and exhibit more stable electric vector position angles (EVPAs) in their core features and a better alignment of the EVPAs with the local jet direction. The latter is accompanied by a higher degree of linear polarization, suggesting that compact bright jet features might be strong transverse shocks, which enhance magnetic field regularity by compression.

From radio to TeV: the surprising spectral energy distribution of AP Librae

DOE PAGES

Sanchez, D. A.; Giebels, B.; Fortin, P.; ...

2015-10-17

Following the discovery of high-energy (HE; E > 10 MeV) and very-high-energy (VHE; E > 100 GeV) γ-ray emission from the low-frequency-peaked BL Lac (LBL) object AP Librae, its electromagnetic spectrum is studied over 60 octaves in energy. Contemporaneous data in radio, optical and UV together with the (non-simultaneous) γ-ray data are used to construct the most precise spectral energy distribution of this source. We found that the data was modelled with difficulties with single-zone homogeneous leptonic synchrotron self-Compton (SSC) radiative scenarios due to the unprecedented width of the HE component when compared to the lower-energy component. Furthermore, the twomore » other LBL objects also detected at VHE appear to have similar modelling difficulties. Nevertheless, VHE γ-rays produced in the extended jet could account for the VHE flux observed by HESS.« less

Optical Spectroscopic Survey of a Sample of Unidentified Fermi Objects

NASA Astrophysics Data System (ADS)

Paiano, Simona; Falomo, Renato; Franceschini, Alberto; Treves, Aldo; Scarpa, Riccardo

2017-12-01

We present optical spectroscopy secured at the 10 m Gran Telescopio Canarias of the counterparts of 20 extragalactic γ-ray sources detected by the Fermi satellite. The observations allow us to investigate the nature of these sources and to determine their redshift. We find that all optical counterparts have a spectrum that is consistent with a BL Lac object nature. We are able to determine the redshift for 11 objects and set spectroscopic redshift limits for five targets. The optical spectrum is found featureless for only four sources. In the latter cases, we can set lower limits on the redshift based on the assumption that they are hosted by a typical massive elliptical galaxy whose spectrum is diluted by the nonthermal continuum. The observations allow us to unveil the nature of these gamma-ray sources and provide a sanity check of a tool to discover the counterparts of γ-ray emitters/blazars based on their multiwavelength emission.

MULTIWAVELENGTH EVIDENCE FOR QUASI-PERIODIC MODULATION IN THE GAMMA-RAY BLAZAR PG 1553+113

DOE PAGES

Ackerman, M.

2015-11-10

We report for the first time a γ-ray and multiwavelength nearly-periodic oscillation in an active galactic nucleus. Using the Fermi Large Area Telescope (LAT) we have discovered an apparent quasi-periodicity in the γ-ray flux (E > 100 MeV) from the GeV/TeV BL Lac object PG 1553+113. The marginal significance of the 2.18±0.08 year-period γ-ray cycle is strengthened by correlated oscillations observed in radio and optical fluxes, through data collected in the OVRO, Tuorla, KAIT, and CSS monitoring programs and Swift UVOT. The optical cycle appearing in ~ 10 years of data has a similar period, while the 15 GHz oscillationmore » is less regular than seen in the other bands. Further long-term multi-wavelength monitoring of this blazar may discriminate among the possible explanations for this quasi-periodicity.« less

The Properties of Extragalactic Radio Jets

NASA Astrophysics Data System (ADS)

Finke, Justin

2018-01-01

I show that by assuming a standard Blandford-Konigl jet, it is possible to determine the speed (bulk Lorentz factor) and orientation (angle to the line of sight) of self-similar parsec-scale blazar jets by using four measured quantities: the core radio flux, the extended radio flux, the magnitude of the core shift between two frequencies, and the apparent jet opening angle. Once the bulk Lorentz factor and angle to the line of sight of a jet are known, it is possible to compute their Doppler factor, magnetic field, and intrinsic jet opening angle. I use data taken from the literature and marginalize over nuisance parameters associated with the electron distribution and equipartition, to compute these quantities, albeit with large errors. The results have implications for the resolution of the TeV BL Lac Doppler factor crisis and the production of jets from magnetically arrested disks.

EMITTING ELECTRONS AND SOURCE ACTIVITY IN MARKARIAN 501

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mankuzhiyil, Nijil; Ansoldi, Stefano; Persic, Massimo

2012-07-10

We study the variation of the broadband spectral energy distribution (SED) of the BL Lac object Mrk 501 as a function of source activity, from quiescent to flaring. Through {chi}{sup 2}-minimization we model eight simultaneous SED data sets with a one-zone synchrotron self-Compton (SSC) model, and examine how model parameters vary with source activity. The emerging variability pattern of Mrk 501 is complex, with the Compton component arising from {gamma}-e scatterings that sometimes are (mostly) Thomson and sometimes (mostly) extreme Klein-Nishina. This can be seen from the variation of the Compton to synchrotron peak distance according to source state. Themore » underlying electron spectra are faint/soft in quiescent states and bright/hard in flaring states. A comparison with Mrk 421 suggests that the typical values of the SSC parameters are different in the two sources: however, in both jets the energy density is particle-dominated in all states.« less

MULTIWAVELENGTH EVIDENCE FOR QUASI-PERIODIC MODULATION IN THE GAMMA-RAY BLAZAR PG 1553+113

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Buehler, R.; Ajello, M.

2015-11-10

We report for the first time a γ-ray and multiwavelength nearly periodic oscillation in an active galactic nucleus. Using the Fermi Large Area Telescope we have discovered an apparent quasi-periodicity in the γ-ray flux (E > 100 MeV) from the GeV/TeV BL Lac object PG 1553+113. The marginal significance of the 2.18 ± 0.08 year period γ-ray cycle is strengthened by correlated oscillations observed in radio and optical fluxes, through data collected in the Owens Valley Radio Observatory, Tuorla, Katzman Automatic Imaging Telescope, and Catalina Sky Survey monitoring programs and Swift-UVOT. The optical cycle appearing in ∼10 years of datamore » has a similar period, while the 15 GHz oscillation is less regular than seen in the other bands. Further long-term multiwavelength monitoring of this blazar may discriminate among the possible explanations for this quasi-periodicity.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanaka, Masayuki; Nakaoka, Tatsuya; Kawabata, Miho

We present the early-phase spectra and the light curves of the broad-lined (BL) supernova (SN) 2016coi from t = 7 to 67 days after the estimated explosion date. This SN was initially reported as a BL Type SN Ic (SN Ic-BL). However, we found that spectra up to t = 12 days exhibited the He i λ 5876, λ 6678, and λ 7065 absorption lines. We show that the smoothed and blueshifted spectra of normal SNe Ib are remarkably similar to the observed spectrum of SN 2016coi. The line velocities of SN 2016coi were similar to those of SNe Ic-BLmore » and significantly faster than those of SNe Ib. Analyses of the line velocity and light curve suggest that the kinetic energy and the total ejecta mass of SN 2016coi are similar to those of SNe Ic-BL. Together with BL SNe 2009bb and 2012ap, for which the detection of He i was also reported, these SNe could be transitional objects between SNe Ic-BL and SNe Ib, and be classified as BL Type “Ib” SNe (SNe “Ib”-BL). Our work demonstrates the diversity of the outermost layer in BL SNe, which should be related to the variety of the evolutionary paths.« less

Transcriptional and functional analysis of galactooligosaccharide uptake by lacS in Lactobacillus acidophilus

PubMed Central

Andersen, Joakim M.; Barrangou, Rodolphe; Abou Hachem, Maher; Lahtinen, Sampo; Goh, Yong Jun; Svensson, Birte; Klaenhammer, Todd R.

2011-01-01

Probiotic microbes rely on their ability to survive in the gastrointestinal tract, adhere to mucosal surfaces, and metabolize available energy sources from dietary compounds, including prebiotics. Genome sequencing projects have proposed models for understanding prebiotic catabolism, but mechanisms remain to be elucidated for many prebiotic substrates. Although β-galactooligosaccharides (GOS) are documented prebiotic compounds, little is known about their utilization by lactobacilli. This study aimed to identify genetic loci in Lactobacillus acidophilus NCFM responsible for the transport and catabolism of GOS. Whole-genome oligonucleotide microarrays were used to survey the differential global transcriptome during logarithmic growth of L. acidophilus NCFM using GOS or glucose as a sole source of carbohydrate. Within the 16.6-kbp gal-lac gene cluster, lacS, a galactoside-pentose-hexuronide permease-encoding gene, was up-regulated 5.1-fold in the presence of GOS. In addition, two β-galactosidases, LacA and LacLM, and enzymes in the Leloir pathway were also encoded by genes within this locus and up-regulated by GOS stimulation. Generation of a lacS-deficient mutant enabled phenotypic confirmation of the functional LacS permease not only for the utilization of lactose and GOS but also lactitol, suggesting a prominent role of LacS in the metabolism of a broad range of prebiotic β-galactosides, known to selectively modulate the beneficial gut microbiota. PMID:22006318

Considerations for practice-based research: a cross-sectional survey of chiropractic, acupuncture and massage practices.

PubMed

Floden, Lysbeth; Howerter, Amy; Matthews, Eva; Nichter, Mark; Cunningham, James K; Ritenbaugh, Cheryl; Gordon, Judith S; Muramoto, Myra L

2015-05-02

Complementary and alternative medicine (CAM) use has steadily increased globally over the past two decades and is increasingly playing a role in the healthcare system in the United States. CAM practice-based effectiveness research requires an understanding of the settings in which CAM practitioners provide services. This paper describes and quantifies practice environment characteristics for a cross-sectional sample of doctors of chiropractic (DCs), licensed acupuncturists (LAcs), and licensed massage therapists (LMTs) in the United States. Using a cross-sectional telephone survey of DCs (n = 32), LAcs (n = 70), and LMTs (n = 184) in the Tucson, AZ metropolitan area, we collected data about each location where practitioners work, as well as measures on practitioner and practice characteristics including: patient volume, number of locations where practitioners worked, CAM practitioner types working at each location, and business models of practice. The majority of practitioners reported having one practice location (93.8% of DCs, 80% of LAcs and 59.8% of LMTs) where they treat patients. Patient volume/week was related to practitioner type; DCs saw 83.13 (SD = 49.29) patients/week, LAcs saw 22.29 (SD = 16.88) patients/week, and LMTs saw 14.21 (SD =10.25) patients per week. Practitioners completed surveys for N = 388 practice locations. Many CAM practices were found to be multidisciplinary and/or have more than one practitioner: 9/35 (25.7%) chiropractic practices, 24/87 (27.6%) acupuncture practices, and 141/266 (53.0%) massage practices. Practice business models across CAM practitioner types were heterogeneous, e.g. sole proprietor, employee, partner, and independent contractor. CAM practices vary across and within disciplines in ways that can significantly impact design and implementation of practice-based research. CAM research and intervention programs need to be mindful of the heterogeneity of CAM practices in order to create appropriate interventions, study designs, and implementation plans.

What are the blood lead levels of children living in Latin America and the Caribbean?

PubMed

Olympio, Kelly Polido Kaneshiro; Gonçalves, Cláudia Gaudência; Salles, Fernanda Junqueira; Ferreira, Ana Paula Sacone da Silva; Soares, Agnes Silva; Buzalaf, Marília Afonso Rabelo; Cardoso, Maria Regina Alves; Bechara, Etelvino José Henriques

2017-04-01

Information on the prevalence of lead exposure is essential to formulate efficient public health policies. Developed countries have implemented successful public policies for the prevention and control of lead poisoning. In the United States, Canada, Japan and the European Union, for instance, periodically repeated prevalence studies show that blood lead levels (BLLs) in children have decreased overall. Although BLL of Latino children in the U.S. have also dropped in recent years, the geometric mean remains higher than that of white children. Little is known about lead exposure in children in Latin America and the Caribbean (LAC). In this review, we responded to two questions: What is currently known about lead sources and levels in children in LAC? Are there public policies to prevent children's exposure to lead in LAC? We conducted a literature review covering the period from January 2000 to March 2014 in the PubMed and Lilacs databases to obtain English, Portuguese and Spanish language studies reporting the prevalence of BLLs in children aged 0-18years living in LAC countries. No specific analytical method was selected, and given the scarcity of data, the study was highly inclusive. Fifty-six papers were selected from 16 different LAC countries. The children's BLLs found in this review are high (≥10μg/dL) compared to BLLs for the same age group in the U. S. However, most studies reported an association with some type of "lead hot spot", in which children can be exposed to lead levels similar to those of occupational settings. Only Peru and Mexico reported BLLs in children from population-based studies. Most BLLs prevalence studies carried out in LAC were in areas with known emission sources. The percentage of children at risk of lead poisoning in LAC is unknown, and probably underestimated. Thus, there is an urgent need to establish public health policies to quantify and prevent lead poisoning, specifically by prioritizing the identification and control of "hot spots". Copyright © 2017 Elsevier Ltd. All rights reserved.

Methylobacterium pseudosasicola sp. nov. and Methylobacterium phyllostachyos sp. nov., isolated from bamboo leaf surfaces.

PubMed

Madhaiyan, Munusamy; Poonguzhali, Selvaraj

2014-07-01

Two strains of Gram-negative, methylotrophic bacteria, isolated because of their abilities to promote plant growth, were subjected to a polyphasic taxonomic study. The isolates were strictly aerobic, motile, pink-pigmented, facultatively methylotrophic, non-spore-forming rods. The chemotaxonomic characteristics of the isolates included the presence of C18 : 1ω7c as the major cellular fatty acid. The DNA G+C contents of strains BL36(T) and BL47(T) were 69.4 and 69.8 mol%, respectively. 16S rRNA gene sequence analysis of strains BL36(T) and BL47(T) placed them under the genus Methylobacterium, with the pairwise sequence similarity between them and the type strains of closely related species ranging from 97.2 to 99.0%. On the basis of their phenotypic and phylogenetic distinctiveness and the results of DNA-DNA hybridization analysis, the isolates represent two novel species within the genus Methylobacterium, for which the names Methylobacterium pseudosasicola sp. nov. (type strain BL36(T) = NBRC 105203(T) = ICMP 17621(T)) and Methylobacterium phyllostachyos sp. nov. (type strain BL47(T) = NBRC 105206(T) = ICMP 17619(T)) are proposed. © 2014 IUMS.

Constraints on the Intergalactic Magnetic Field with Gamma-Ray Observations of Blazars

NASA Astrophysics Data System (ADS)

Finke, Justin D.; Reyes, Luis C.; Georganopoulos, Markos; Reynolds, Kaeleigh; Ajello, Marco; Fegan, Stephen J.; McCann, Kevin

2015-11-01

Distant BL Lacertae objects emit γ-rays that interact with the extragalactic background light (EBL), creating electron-positron pairs, and reducing the flux measured by ground-based imaging atmospheric Cherenkov telescopes (IACTs) at very-high energies (VHE). These pairs can Compton-scatter the cosmic microwave background, creating a γ-ray signature at slightly lower energies that is observable by the Fermi Large Area Telescope (LAT). This signal is strongly dependent on the intergalactic magnetic field (IGMF) strength (B) and its coherence length (LB). We use IACT spectra taken from the literature for 5 VHE-detected BL Lac objects and combine them with LAT spectra for these sources to constrain these IGMF parameters. Low B values can be ruled out by the constraint that the cascade flux cannot exceed that observed by the LAT. High values of B can be ruled out from the constraint that the EBL-deabsorbed IACT spectrum cannot be greater than the LAT spectrum extrapolated into the VHE band, unless the cascade spectrum contributes a sizable fraction of the LAT flux. We rule out low B values (B ≲ 10-19 G for LB ≥ 1 Mpc) at >5σ in all trials with different EBL models and data selection, except when using >1 GeV spectra and the lowest EBL models. We were not able to constrain high values of B.

Multiwavelength monitoring of the BL Lacertae object PKS 2155-304. 3: Ground-based observations in 1991 November

NASA Technical Reports Server (NTRS)

Courvoisier, T. J.-L.; Blecha, A.; Bouchet, P.; Bratschi, P.; Carini, M. T.; Donahue, M.; Edelson, R.; Feigelson, E. D.; Filippenko, A. V.; Glass, I. S.

1995-01-01

We present ground-based observations of the BL Lac object PKS 2155-304 during 1991 November. These data were obtained as part of a large international campaign of observations spanning the electro-magnetic spectrum from the radio waves to the X-rays. The data presented here include radio and UBVRI fluxes, as well as optical polarimetry. The U to I data show the same behavior in all bands and that only upper limits to any lag can be deduced from the cross-correlation of the light curves. The spectral slope in the U-I domain remained constant on all epochs but 2. There is no correlation between changes in the spectral slope and large variations in the total or polarized flux. The radio flux variations did not follow the same pattern of variability as the optical and infrared fluxes. The polarized flux varied by a larger factor than the total flux. The variations of the polarized flux are poorly correlated with those of the total flux in the optical (and hence UV domain; see the accompanying paper by Edelson et al.) nor with those of the soft X-rays. We conclude that the variability of PKS 2155-304 in the optical and near-infrared spectral domains are easier to understand in the context of variable geometry or bulk Lorentz factor than of variable electron acceleration and cooling rates.

Louisiana SIP: LAC 33:III Ch. 7 - Table 2 - Ambient Air--Methods of Contaminant Measurements; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) to 2011-08-03 (LAd34 - Moved to Section 711 and revised [adds PM-2.5])

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch. 7 - Table 2 - Ambient Air--Methods of Contaminant Measurements; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) to 2011-08-03 (LAd34 - Moved to Section 711 and revised [adds PM-2.5])

Louisiana SIP: LAC 33:III Ch. 7 Section 709. Measurement of Concentrations PM10, SO2, Carbon Monoxide, Atmospheric Oxidants, Nitrogen Oxides, and Lead; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) to 2011-08-03 (LAd34 - Revised)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch. 7 Section 709. Measurement of Concentrations PM10, SO2, Carbon Monoxide, Atmospheric Oxidants, Nitrogen Oxides, and Lead; SIP effective 1989-05-08 (LAc49) and 1989-08-14 (LAc50) to 2011-08-03 (LAd34 - Revised)

Distinct signatures for mutator sensitivity of lacZ reversions and for the spectrum of lacI/lacO forward mutations on the chromosome of nondividing Escherichia coli.

PubMed Central

Bharatan, Shanti M; Reddy, Manjula; Gowrishankar, J

2004-01-01

A conditional lethal galE(Ts)-based strategy was employed in Escherichia coli, first to eliminate all growth-associated chromosomal reversions in lacZ or forward mutations in lacI/lacO by incubation at the restrictive temperature and subsequently to recover (as papillae) spontaneous mutations that had arisen in the population of nondividing cells after shift to the permissive temperature. Data from lacZ reversion studies in mutator strains indicated that the products of all genes for mismatch repair (mutHLS, dam, uvrD), of some for oxidative damage repair (mutMT), and of that for polymerase proofreading (dnaQ) are required in dividing cells; some others for oxidative damage repair (mutY, nth nei) are required in both dividing and nondividing cells; and those for alkylation damage repair (ada ogt) are required in nondividing cells. The spectrum of lacI/lacO mutations in nondividing cells was distinguished both by lower frequencies of deletions and IS1 insertions and by the unique occurrence of GC-to-AT transitions at lacO +5. In the second approach to study mutations that had occurred in nondividing cells, lacI/lacO mutants were selected as late-arising papillae from the lawn of a galE+ strain; once again, transitions at lacO +5 were detected among the mutants that had been obtained from populations initially grown on poor carbon sources such as acetate, palmitate, or succinate. Our results indicate that the lacO +5 site is mutable only in nondividing cells, one possible mechanism for which might be that random endogenous alkylation (or oxidative) damage to DNA in these cells is efficiently corrected by the Ada Ogt (or Nth Nei) repair enzymes at most sites but not at lacO +5. Furthermore, the late-arising papillae from the second approach were composed almost exclusively of dominant lacI/lacO mutants. This finding lends support to "instantaneous gratification" models in which a spontaneous lesion, occurring at a random site in DNA of a nondividing cell, is most likely to be fixed as a mutation if it allows the cell to immediately exit the nondividing state. PMID:15020459

Long-range transcriptional interference in E. coli used to construct a dual positive selection system for genetic switches

PubMed Central

Hoffmann, Stefan A.; Kruse, Sabrina M.; Arndt, Katja M.

2016-01-01

Abstract We have investigated transcriptional interference between convergent genes in E. coli and demonstrate substantial interference for inter-promoter distances of as far as 3 kb. Interference can be elicited by both strong σ70 dependent and T7 promoters. In the presented design, a strong promoter driving gene expression of a ‘forward’ gene interferes with the expression of a ‘reverse’ gene by a weak promoter. This arrangement allows inversely correlated gene expression without requiring further regulatory components. Thus, modulation of the activity of the strong promoter alters expression of both the forward and the reverse gene. We used this design to develop a dual selection system for conditional operator site binding, allowing positive selection both for binding and for non-binding to DNA. This study demonstrates the utility of this novel system using the Lac repressor as a model protein for conditional DNA binding, and spectinomycin and chloramphenicol resistance genes as positive selection markers in liquid culture. Randomized LacI libraries were created and subjected to subsequent dual selection, but mispairing IPTG and selection cues in respect to the wild-type LacI response, allowing the isolation of a LacI variant with a reversed IPTG response within three rounds of library generation and dual selection. PMID:26932362

Exploration of Structural Changes in Lactose Permease on Sugar Binding and Proton Transport through Atomistic Simulations

NASA Astrophysics Data System (ADS)

Liu, Jin; Jewel, Yead; Dutta, Prashanta

2017-11-01

Escherichia coli lactose permease (LacY) actively transports lactose and other galactosides across cell membranes through lactose/H+ symport process. Lactose/H+ symport is a highly complex process that involves large-scale protein conformational changes. The complete picture of lactose/H+ symport is largely unclear. In this work, we develop the force field for sugar molecules compatible with PACE, a hybrid and coarse-grained force field that couples the united-atom protein models with the coarse-grained MARTINI water/lipid. After validation, we implement the new force field to investigate the binding of a β-D-galactopyranosyl-1-thio- β-D-galactopyranoside (TDG) molecule to a wild-type LacY. Transitions from inward-facing to outward-facing conformations upon TDG binding and protonation of Glu269 have been achieved from microsecond simulations. Both the opening of the periplasmic side and closure of the cytoplasmic side of LacY are consistent with experiments. Our analysis suggest that the conformational changes of LacY are a cumulative consequence of inter-domain H-bonds breaking at the periplasmic side, inter-domain salt-bridge formation at the cytoplasmic side, as well as the TDG orientational changes during the transition. This work is supported by US National Science Foundation under Grant No. CBET-1604211.

Adenovirus-mediated p53 gene delivery inhibits 9L glioma growth in rats.

PubMed

Badie, B; Drazan, K E; Kramar, M H; Shaked, A; Black, K L

1995-06-01

Adenoviral vectors have recently been shown to effectively deliver genes into a variety of tissues. Since these vectors have some advantages over the more extensively investigated retroviruses, we studied the effect of two replication-defective adenovectors bearing human wild type tumor suppressor gene p53 (Adp53) and Escherichia coli beta-galactosidase gene (AdLacZ) on 9L glioma cells. Successful in vitro gene transfer was shown by DNA polymerase chain reaction (PCR), and expression was confirmed by reverse transcriptase RNA PCR and Western blot analyses. Transduction of 9L cells with the Adp53 inhibited cell growth and induced phenotypic changes consistent with cell death at low titers, while AdLacZ caused cytopathic changes only at high titers. Stereotactic injection of AdLacZ (10(7) plaque forming units) into tumor bed stained 25 to 30% of tumor cells at the site of vector delivery. Injection of Adp53 (10(7) plaque forming units), but not AdLacZ (controls), into established 4-day old 9L glioma brain tumors decreased tumor volume by 40% after 14 days. As a step toward gene therapy of brain tumors using replication-defective adenoviruses, these data support the use of tumor suppressor gene transfer for in vivo treatment of whole animal brain tumor models.

Studies on the Nucleotide Sequence, Transcription and Deletion Analysis of the BmNPV Protein Kinase Gene.

PubMed

Zhang, Chuan-Xi; Hu, Cui; Wu, Xiang-Fu

1998-01-01

The coding region of BmvPK-1 gene of Bombyx mori NPV (Strain ZJ8) is 828 nt long and encodes a 276 aa polypeptide with predicted molecular mass of 32 kD. Dot blot analysis showed its mRNA to be gene is first detectable at 18 h p.i. and reaching the highest transcriptional level at 48 h p.i. The result suggested that BmvPK-1 gene is a late or very late gene. The most conserved 365 bp of the BmvPK-1 gene was deleted in a transfer vector (pUCPK-lac), and a report gene (lacZ) was inserted in the deleted position. Cotransfection of BmN cells with pUCPK-lac DNA and BmNPV DNA resulted in the recombinant virus which expressed detectable product of lacZ gene. But the virus with the deleted BmvPK-1 gene could not be isolated from the wild BmNPV by plaque purification method. The result showed that the BmvPK-1 gene deleted virus can multiply only with the help of the product of this gene from the wild type virus, and the gene is necessary for the virus to finish its life cycle in the cultured cells.

An Analysis of Ball Lightning-Aircraft Incidents

NASA Astrophysics Data System (ADS)

Doe, R. K.; Keul, A. G.; Bychkov, V.

2009-12-01

Lightning is a rare but regular phenomenon for air traffic. Research and design have created aircraft that withstand average lightning strikes. Ball lightning (BL), a metastable, rare lightning type, is also observed from (and within) aircraft. Science and the media focused on individual BL incidents and did not analyze general patterns. Lacking established incident reporting channels, most BL observations are still passed on as “aviation lore”. To overcome this unsatisfactory condition, the authors collected and analyzed an international data bank of 87 BL-aircraft case histories from 1938 to 2007. 37 Russian military and civil BL reports were provided by the third author. Of the whole sample, 36 (41%) cases occurred over Russia/RF/SU, 24 (28%) over USA/Canada, 23 (26%) over Europe, and 4 (5%) over Asia/Pacific. Various types of military (US: C-54/141, B-52, KC-97/135 Stratotankers, C130, P-3 Orion, RF/SU: PO-2, IL, SU, TU, MIG; Nimrod, Saab-105) and civilian aircraft (US: DC-3/6, Metroliner, B-727/737/757/777, RF/SU: AN, TU; VC-10, Fokker F-28, CRJ-200), as well as general aviation (C-172, Falcon-20), were involved. BL reports show a flat annual April to August maximum. At BL impact, 15 aircraft were climbing, 7 descending; most were at cruising altitude. 42 (48%) reported BL outside the aircraft, 37 (43%) inside, 7 (8%) both in-and outside. No damage was reported in 34 (39%) cases, 39 objects (45%) caused minor damage, 11 major damage (13%), 3 even resulted in military aircraft losses. 3 objects caused minor, 1 major crew injury. 23 damage cases were associated with BL inside the fuselage; all 4 crew injury cases were of that BL type. Mean size is described as 25 cm, sometimes over 1 m, color 30% in the yellow-red, 10% in the blue-green spectral region, 8% white, duration around 10 seconds, sometimes over 1 minute. 33 (38%) incidents ended with an explosion of the object. Thunderstorm conditions were reported by 25 (29%) of the observers, 9 (10%) said there was no thunderstorm. Results on lightning-aircraft interaction (Rakov & Uman, 2003) are compared with BL reports (e.g. flight level - BL maxima at 1000 and 3000 m). BL is seen as an atmospheric electrical phenomenon, in some cases after an initial cloud-aircraft lightning flash, in other cases originating without a lightning flash. Because of this, aircraft BL is also of interest for BL theories. Approximately 50% occur inside the airframe, some causing minor damage, potentially threatening to crew and passengers. Structural damage highlighted by mass media is extremely rare. Although BL constitutes no major air traffic risk, the authors suggest routine BL incident/accident reporting and BL damage/injury investigation. Aircrews should be briefed about possible BL within the fuselage. After a BL occurrence, airline passengers should be informed and debriefed.

H.E.S.S. discovery of very high energy γ-ray emission from PKS 0625-354

NASA Astrophysics Data System (ADS)

H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hadasch, D.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu; Kosack, K.; Krakau, S.; Kraus, M.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morâ, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.

2018-05-01

PKS 0625-354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index Γ = 2.84 ± 0.50stat ± 0.10syst and normalization (at E0 = 1.0 TeV) N0(E0) = (0.58 ± 0.22stat ± 0.12syst) × 10-12 TeV-1 cm-2 s-1. Multiwavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT γ-ray and Swift-XRT X-ray energy bands. Having a good multiwavelength coverage from radio to very high energy, we performed a broad-band modelling from two types of emission scenarios. The results from a one zone lepto-hadronic and a multizone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multizone model. Models associated to the X-ray variability constraint support previous results, suggesting a BL Lac nature of PKS 0625-354 with, however, a large-scale jet structure typical of a radio galaxy.

[Retrospective analysis of the value of arterial blood lactate level and its clearance rate on the prognosis of septic shock patients].

PubMed

Bao, Lei; Zhang, Min; Yan, Peixia; Wu, Xiaoyan; Shao, Jun; Zheng, Ruiqiang

2015-01-01

To explore the prognostic value of arterial blood lactate ( Lac ) levels and lactate clearance rate ( LCR ) in the patients with septic shock. A retrospective study was conducted. Clinical data of 94 septic patients admitted in the Department of Critical Care Medicine in Subei People's Hospital from January 2011 to June 2014 were analyzed. The arterial blood Lac levels at the moment of diagnosis of septic shock ( incipient value, 0 hour ) and early-stage after treatment ( 3, 6 and 24 hours ) were reviewed, and individual LCR was calculated at 3, 6, 24 hours for each patient. According to the outcome in intensive care unit ( ICU ), patients were divided into survival group ( n = 48 ) and death group ( n = 46 ). The Lac and LCR at different time points in two groups were analyzed, and the relationships between them and outcome were analyzed. The receiver-operating characteristic ( ROC ) curve was plotted to assess the value of Lac and LCR at different time points for predicting the outcome. Lac level after treatment in survival group was significantly lower than incipient value, but there was no obvious change in death group. Compared with death group, early Lac levels ( mmol/L ) in survival group were significantly reduced ( 0 hour: 3.80±2.14 vs. 5.75±3.21, 3 hours: 2.05±1.04 vs. 5.03±2.53, 6 hours: 1.80±0.77 vs. 4.40±2.02, 24 hours: 1.35±0.43 vs. 4.90±2.72, P<0.05 or P<0.01 ), the LCR was significantly increased [ 3 hours: 50.00 ( 72.35 )% vs. 13.51 ( 20.67 )%, 6 hours: 41.43 ( 58.42 )% vs. 22.00 ( 22.31 )%, 24 hours: 58.73 ( 29.94 )% vs. 18.92 ( 47.28 )%, P<0.05 or P<0.01 ]. The Lac levels at all time points were positively correlated with the outcome, and 6-hour and 24-hour LCR were negatively correlated with the outcome. According to the incipient Lac level, patients were divided into low Lac group ( Lac<2 mmol/L ), mild Lac group ( Lac 2-3 mmol/L ) and high Lac group ( Lac ≥ 4 mmol/L ). The mortality in low Lac group, mild Lac group, high Lac group was gradually increased [ 23.07% ( 6/26 ), 50.00% ( 8/16 ), 61.54% ( 32/52 ), χ(2) = 10.270, P = 0.006 ]. ROC curves demonstrated that the area under ROC curve ( AUC ) of 24-hour Lac was the largest, 0.944, and it was more sensitive and specific in the prognosis evaluation ( 100% and 78.3%, respectively ). According to the cut-off value of 24-hour Lac as 2.35 mmol/L, patients were divided into high Lac and low Lac groups, and mortality rate in high Lac group was significantly higher than that in low Lac group [ 100.0% ( 36/36 ) vs. 17.24% ( 10/58 ), χ(2) = 30.441,P = 0.000 ]. The AUC of 24-hour LCR was the largest, 0.865, and it was more sensitive and specific for the prognosis evaluation ( 83.3% and 91.3%, respectively ). According to the cut-off value of 24-hour LCR as 36.8%, patients were divided into high LCR group and low LCR group, and mortality rate in low LCR group was significantly higher than that in high LCR group [ 84.00% ( 42/50 ) vs. 9.09% ( 4/44 ), χ(2) = 26.278, P = 0.000 ]. Early high Lac in patients with septic shock prompts a poor prognosis, and 24-hour Lac levels and LCR are indicators of assessment of clinical therapeutic effect and prognosis of patients with septic shock.

Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

DOE PAGES

Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; ...

2015-05-27

Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Here, the goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These mechanisms may also apply to more distant blazars that cannot be studied with the same level of detail. A flare occurring in March 2010 was observed for 13 consecutive days (from MJD 55 265 to MJD 55 277) with unprecedented wavelength coverage from radiomore » to very high energy (VHE; E> 100 GeV) γ-rays with MAGIC, VERITAS, Whipple, Fermi-LAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We modeled the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigated the physical parameters, and evaluated whether the observed broadband SED variability can be associated with variations in the relativistic particle population. As a result, the activity of Mrk 421 initially was high and then slowly decreased during the 13-day period. The flux variability was remarkable at the X-ray and VHE bands, but it was minor or not significant at the other bands. The variability in optical polarization was also minor. These observations revealed an almost linear correlation between the X-ray flux at the 2–10 keV band and the VHE γ-ray flux above 200 GeV, consistent with the γ-rays being produced by inverse-Compton scattering in the Klein-Nishina regime in the framework of SSC models. The one-zone SSC model can describe the SED of each day for the 13 consecutive days reasonably well, which once more shows the success of this standard theoretical scenario to describe the SEDs of VHE BL Lacs such as Mrk 421. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission, while the other smaller zone, which is spatially separated from the first, contributes to the daily variable emission occurring at X-rays and VHE γ-rays. The second blob is assumed to have a smaller volume and a narrow electron energy distribution with 3 × 104« less

Beware of your Cre-Ation: lacZ expression impairs neuronal integrity and hippocampus-dependent memory.

PubMed

Reichel, J M; Bedenk, B T; Gassen, N C; Hafner, K; Bura, S A; Almeida-Correa, S; Genewsky, A; Dedic, N; Giesert, F; Agarwal, A; Nave, K-A; Rein, T; Czisch, M; Deussing, J M; Wotjak, C T

2016-10-01

Expression of the lacZ-sequence is a widely used reporter-tool to assess the transgenic and/or transfection efficacy of a target gene in mice. Once activated, lacZ is permanently expressed. However, protein accumulation is one of the hallmarks of neurodegenerative diseases. Furthermore, the protein product of the bacterial lacZ gene is ß-galactosidase, an analog to the mammalian senescence-associated ß-galactosidase, a molecular marker for aging. Therefore we studied the behavioral, structural and molecular consequences of lacZ expression in distinct neuronal sub-populations. lacZ expression in cortical glutamatergic neurons resulted in severe impairments in hippocampus-dependent memory accompanied by marked structural alterations throughout the CNS. In contrast, GFP expression or the expression of the ChR2/YFP fusion product in the same cell populations did not result in either cognitive or structural deficits. GABAergic lacZ expression caused significantly decreased hyper-arousal and mild cognitive deficits. Attenuated structural and behavioral consequences of lacZ expression could also be induced in adulthood, and lacZ transfection in neuronal cell cultures significantly decreased their viability. Our findings provide a strong caveat against the use of lacZ reporter mice for phenotyping studies and point to a particular sensitivity of the hippocampus formation to detrimental consequences of lacZ expression. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Light Curve and Orbital Period Analysis of VX Lac

NASA Astrophysics Data System (ADS)

Yılmaz, M.; Nelson, R. H.; Şenavcı, H. V.; İzci, D.; Özavcı, İ.; Gümüş, D.

2017-04-01

In this study, we performed simultaneously light curve and radial velocity, and also period analyses of the eclipsing binary system VX Lac. Four color (BVRI) light curves of the system were analysed using the W-D code. The results imply that VX Lac is a classic Algol-type binary with a mass ratio of q=0.27, of which the less massive secondary component fills its Roche lobe. The orbital period behaviour of the system was analysed by assuming the light time effect (LITE) from a third body. The O-C analysis yielded a mass transfer rate of dM/dt=1.86×10-8M⊙yr-1 and the minimal mass of the third body to be M3=0.31M⊙. The residuals from mass transfer and the third body were also analysed because another cyclic variation is seen in O-C diagram. This periodic variation was examined under the hypotheses of stellar magnetic activity and fourth body.

Engineering an allosteric transcription factor to respond to new ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Noah D.; Garruss, Alexander S.; Moretti, Rocco

Genetic regulatory proteins inducible by small molecules are useful synthetic biology tools as sensors and switches. Bacterial allosteric transcription factors (aTFs) are a major class of regulatory proteins, but few aTFs have been redesigned to respond to new effectors beyond natural aTF-inducer pairs. Altering inducer specificity in these proteins is difficult because substitutions that affect inducer binding may also disrupt allostery. In this paper, we engineered an aTF, the Escherichia coli lac repressor, LacI, to respond to one of four new inducer molecules: fucose, gentiobiose, lactitol and sucralose. Using computational protein design, single-residue saturation mutagenesis or random mutagenesis, along withmore » multiplex assembly, we identified new variants comparable in specificity and induction to wild-type LacI with its inducer, isopropyl β-D-1-thiogalactopyranoside (IPTG). Finally, the ability to create designer aTFs will enable applications including dynamic control of cell metabolism, cell biology and synthetic gene circuits.« less

Engineering an allosteric transcription factor to respond to new ligands

DOE PAGES

Taylor, Noah D.; Garruss, Alexander S.; Moretti, Rocco; ...

2015-12-21

Genetic regulatory proteins inducible by small molecules are useful synthetic biology tools as sensors and switches. Bacterial allosteric transcription factors (aTFs) are a major class of regulatory proteins, but few aTFs have been redesigned to respond to new effectors beyond natural aTF-inducer pairs. Altering inducer specificity in these proteins is difficult because substitutions that affect inducer binding may also disrupt allostery. In this paper, we engineered an aTF, the Escherichia coli lac repressor, LacI, to respond to one of four new inducer molecules: fucose, gentiobiose, lactitol and sucralose. Using computational protein design, single-residue saturation mutagenesis or random mutagenesis, along withmore » multiplex assembly, we identified new variants comparable in specificity and induction to wild-type LacI with its inducer, isopropyl β-D-1-thiogalactopyranoside (IPTG). Finally, the ability to create designer aTFs will enable applications including dynamic control of cell metabolism, cell biology and synthetic gene circuits.« less

Pearson-Readhead Survey Sources. II. The Long-Term Centimeter-Band Total Flux and Linear Polarization Properties of a Complete Radio Sample

NASA Astrophysics Data System (ADS)

Aller, M. F.; Aller, H. D.; Hughes, P. A.

2003-03-01

Using UMRAO centimeter-band total flux density and linear polarization monitoring observations of the complete Pearson-Readhead extragalactic source sample obtained between 1984 August and 2001 March, we identify the range of variability in extragalactic objects as functions of optical and radio morphological classification and relate total flux density variations to structural changes in published coeval VLBI maps in selected objects. As expected, variability is common in flat- or inverted-spectrum (α<=0.5) core-dominated QSOs and BL Lac objects. Unexpectedly, we find flux variations in several steep-spectrum sample members, including the commonly adopted flux standard 3C 147. Such variations are characteristically several-year rises or declines or infrequent outbursts, requiring long-term observations for detection: we attribute them to the brightening of weak core components, a change that is suppressed by contributions from extended structure in all but the strongest events, and identify a wavelength dependence for the amplitude of this variability consistent with the presence of opacity in some portions of the jet flow. One morphological class of steep-spectrum objects, the compact symmetric objects (CSOs), characteristically shows only low-level variability. We examine the statistical relation between fractional polarization and radio class based on the data at 14.5 and 4.8 GHz. The blazars typically exhibit flat-to-inverted polarization spectra, a behavior attributed to opacity effects. Among the steep-spectrum objects, the lobe-dominated FR I galaxies have steep fractional polarization spectra, while the FR II galaxies exhibit fractional polarization spectra ranging from inverted to steep, with no identifiable common property that accounts for the range in behavior. For the CSO/gigahertz-peaked spectrum sources, we verify that the fractional polarizations at 4.8 GHz are only of the order of a few tenths of a percent, but at 14.5 GHz we find significantly higher polarizations, ranging from 1% to 3%; this frequency dependence supports a scenario invoking Faraday depolarization by a circumnuclear torus. We have identified preferred orientations of the electric vector of the polarized emission (EVPA) at 14.5 and 4.8 GHz in roughly half of the objects and compared these with orientations of the flow direction indicated by VLBI morphology. When comparing the distributions of the orientation offsets for the BL Lac objects and the QSOs, we find differences in both range and mean value, in support of intrinsic class differences. In the shock-in-jet scenario, we attribute this to the allowed range of obliquities of shocks developing in the flow relative to the flow direction: in the BL Lac objects the shocks are nearly transverse to the flow direction, while in the QSOs they include a broader range of obliquities and can be at large angles to it. The fact that we find long-term stability in EVPA over many events implies that a dominant magnetic field orientation persists; in the core-dominated objects, with small contribution from the underlying quiescent jet, this plausibly suggests that the magnetic field has a long-term memory, with subsequent shock events exhibiting similar EVPA orientation, or, alternatively, the presence of a standing shock in the core. We have looked for systematic, monotonic changes in EVPA, which might be expected in the emission from a precessing jet, a model currently invoked for some AGNs; none were identified. Further, we carried out a Scargle periodogram analysis of the total flux density observations, but found no strong evidence for periodicity in any of the sample sources. The only well-established case in support of both jet precession and periodic variability remains the non-sample member OJ 287.

The Impact of Developmental Education at Triton College.

ERIC Educational Resources Information Center

Chand, Sunil

1985-01-01

Describes the following aspects of the Developmental Education Program at Triton College: student placement, courses, faculty selection, reading and writing instruction, mathematics instruction, the Learning Assistance Center (LAC), LAC tutoring, LAC special projects, LAC management, special needs assistance program for disabled students, and…

An acid-stable bacterial laccase identified from the endophyte Pantoea ananatis Sd-1 genome exhibiting lignin degradation and dye decolorization abilities.

PubMed

Shi, Xiaowei; Liu, Qian; Ma, Jiangshan; Liao, Hongdong; Xiong, Xianqiu; Zhang, Keke; Wang, Tengfei; Liu, Xuanmin; Xu, Ting; Yuan, Shanshan; Zhang, Xin; Zhu, Yonghua

2015-11-01

Isolation and identification of a novel laccase (namely Lac4) with various industrial applications potentials from an endophytical bacterium. Endophyte Sd-1 cultured in rice straw showed intra- and extra-cellular laccase activities. Genomic analysis of Sd-1 identified four putative laccases, Lac1 to Lac4. However, only Lac4 contains the complete signature sequence of laccase and shares at most 64 % sequence identity with other characterized bacterial multi-copper oxidases. Recombinant Lac4 can oxidize non-phenolic and phenolic compounds under acidic conditions and at 30-50 °C; Km values of Lac4 for ABTS at pH 2.5 and for guaiacol at pH 4.5 were 1 ± 0.15 and 6.1 ± 1.7 mM, respectively. The activity of Lac4 was stimulated by 0.8 mM Cu(2+) and 5 mM Fe(2+). In addition, Lac4 could decolorize various synthetic dyes and exhibit the degradation rate of 38 % for lignin. The data suggest that Lac4 possesses promising biotechnological potentials.

r/K-like trade-off and voltinism discreteness: The implication to allochronic speciation in the fall webworm, Hyphantria cunea complex (Arctiidae).

PubMed

Yang, Fan; Kawabata, Eriko; Tufail, Muhammad; Brown, John J; Takeda, Makio

2017-12-01

North America has distinct types of Hyphantria moths (Arctiidae) characterized by red (RD)- and black (BL)-headed larvae, of which the taxonomic status is unresolved. Genetic divergence of 26 populations, based on 710 bp of the mtCOI sequence, showed two phylogenetic lineages, which could not be connected in the haplotype network with 95% confidence. The two lineages are separated by 3.1% sequence divergence and should be considered for full species status. The estimated split occurred 1.2-1.6 million years ago. The range of the RD type covered most of the continent, whereas that of the BL type was limited to eastern deciduous forests. Several biological characteristics were differentiated in the zone of cohabitation where BL had more annual generations than RD. Spring emergence of BL precedes that of RD in the field by at least 1 month, because the diapause in BL was shallow, whereas it was deep in RD. Voltinism requires discreteness of numbers, which functions as a sink of hybrids between the two parental lines that have distinct but equally adaptive reproductive strategies; BL may be more r-strategist-like and RD more K-strategist-like, because fast-developing BL has multivoltine life cycle, investing less silk proteins as the round-the-clock feeder, and slow-developing RD univoltine one investing more silk as the nocturnal feeder. Also, intensity of diapause, deep in RD and weak in BL, was grossly different, which may enforce segregation of spring adults. Allochronic speciation avoiding coincidental occurrence of adult stages is therefore the most likely scenario. Because the adults never meet in nature, large morphological differentiation is not required.

Effect of the inclusion of chestnut in the finishing diet on volatile compounds during the manufacture of dry-cured "Lacón" from Celta pig breed.

PubMed

Lorenzo, José M; Franco, Daniel; Carballo, Javier

2014-01-01

The effect of the finishing diet on the volatile compounds throughout the manufacture of dry-cured "lacón" (a Spanish traditional meat product), from the Celta pig breed was studied. Thirty-six pigs were separated into three groups according to the type of feeding during the finish-fattening period of three months (concentrate, mixed diet and chestnut). From the pigs of each diet, four batches of dry-cured "lacón" were manufactured. From each batch, samples of fresh meat, meat after salting, after post-salting, and after 14, 28, 56 and 84 days of drying-ripening were taken. Volatiles were extracted by a purge-and-trap method and analyzed by gas chromatographic/mass spectrometry (GC/MS). Seventy-six volatile compounds were identified and quantified from dry-cured "lacón" samples in pigs finished with chestnut, eighty-two for concentrate fed pigs and eighty in pigs fed with the mixed diet. The number of identified volatile compounds increased during the manufacturing process; at 84 days of drying-ripening, in the dry-cured "lacón" samples from pigs finished with concentrate, mixed diet and chestnut, 54, 58 and 62 volatile compounds were detected, respectively. The most abundant group of flavour compounds at the end of the manufacturing process was hydrocarbons in the three feeding systems, followed by aldehydes, ketones and alcohols. Discriminant analysis selected six variables (dodecane, butadienol, pentenol, 2-pentenal, decen-3-ona and pyridine-2-methyl) and calculated two discriminating functions which allowed verification of chestnut in the finishing diet. © 2013.

Three-dimensional graphene networks as a new substrate for immobilization of laccase and dopamine and its application in glucose/O2 biofuel cell.

PubMed

Zhang, Yijia; Chu, Mi; Yang, Lu; Tan, Yueming; Deng, Wenfang; Ma, Ming; Su, Xiaoli; Xie, Qingji

2014-08-13

We report here three-dimensional graphene networks (3D-GNs) as a novel substrate for the immobilization of laccase (Lac) and dopamine (DA) and its application in glucose/O2 biofuel cell. 3D-GNs were synthesized with an Ni(2+)-exchange/KOH activation combination method using a 732-type sulfonic acid ion-exchange resin as the carbon precursor. The 3D-GNs exhibited an interconnected network structure and a high specific surface area. DA was noncovalently functionalized on the surface of 3D-GNs with 3,4,9,10-perylene tetracarboxylic acid (PTCA) as a bridge and used as a novel immobilized mediating system for Lac-based bioelectrocatalytic reduction of oxygen. The 3D-GNs-PTCA-DA nanocomposite modified glassy carbon electrode (GCE) showed stable and well-defined redox current peaks for the catechol/o-quinone redox couple. Due to the mediated electron transfer by the 3D-GNs-PTCA-DA nanocomposite, the Nafion/Lac/3D-GNs-PTCA-DA/GCE exhibited high catalytic activity for oxygen reduction. The 3D-GNs are proven to be a better substrate for Lac and its mediator immobilization than 2D graphene nanosheets (2D-GNs) due to the interconnected network structure and high specific surface area of 3D-GNs. A glucose/O2 fuel cell using Nafion/Lac/3D-GNs-PTCA-DA/GCE as the cathode and Nafion/glucose oxidase/ferrocence/3D-GNs/GCE as the anode can output a maximum power density of 112 μW cm(-2) and a short-circuit current density of 0.96 mA cm(-2). This work may be helpful for exploiting the popular 3D-GNs as an efficient electrode material for many other biotechnology applications.

MicroRNA528 Affects Lodging Resistance of Maize by Regulating Lignin Biosynthesis under Nitrogen-Luxury Conditions.

PubMed

Sun, Qing; Liu, Xiaogang; Yang, Juan; Liu, Wenwen; Du, Qingguo; Wang, Hongqiu; Fu, Chunxiang; Li, Wen-Xue

2018-06-04

Lodging under nitrogen (N)-luxury conditions substantially reduces crop yield and seed quality. However, the molecular mechanisms of plant lodging resistance remain largely unclear, especially in maize. We report here that the expression of ZmmiR528, a monocot-specific microRNA, is induced by N luxury but reduced by N deficiency. We show by the thioacidolysis and acetyl bromide analysis that N luxury significantly reduces the generation of H, G, and S monomers of the lignin as well as its total content in maize shoots. We further demonstrate that ZmLACCASE3 (ZmLAC3) and ZmLACCASE5 (ZmLAC5), which encode the copper-containing laccases, are the targets of ZmmiR528. In situ hybridization showed that ZmmiR528 is mainly expressed in maize vascular tissues. Knockdown of ZmmiR528 or overexpression of ZmLAC3 significantly increased the lignin content and rind penetrometer resistance of maize stems. In contrast, transgenic maize plants overexpressing ZmmiR528 had reduced lignin content and rind penetrometer resistance and were prone to lodging under N-luxury conditions. RNA-sequencing analysis revealed that ZmPAL7 and ZmPAL8 are upregulated in transgenic maize lines downregulating ZmmiR528. Under N-luxury conditions, the expression levels of ZmPALs were much higher in ZmmiR528-knockdown lines than in the wild type and transgenic maize lines overexpressing ZmmiR528. Taken together, these results indicate that, by regulating the expression of ZmLAC3 and ZmLAC5, ZmmiR528 affects maize lodging resistance under N-luxury conditions. Copyright © 2018 The Author. Published by Elsevier Inc. All rights reserved.

Low Level Exposure to Sulfur Mustard: Development of a SOP for Analysis of Albumin Adducts and of a System for Non-Invasive Diagnosis on Skin

DTIC Science & Technology

2004-12-01

were primarily responsible for the organic chemistry and the analytical chemistry, and to Dr. F . Bikker, Mrs. Roos Mars and Mrs. Helma van Dijk for...study as hosts for bacteriophages: TG1 [K-12 A(lac-pro) supE thi hsdD5/ F ’ traD36proA+ B+ laclq lacZ AM 15] and HB2151 [K-12 ara A(lac-pro) thi/ F ’ proA+ B...TG1 [K-12 A(lac-pro) supE thi hsdD5/ F ’ traD36 proA+ B+ lacPq lacZ AM15] and HB2151 [K-12 ara A(lac-pro) thi/ F ’ proA+ B+ laclq Z AM15]. Both strains were

Adaptive Evolution of the Streptococcus pyogenes Regulatory Aldolase LacD.1

PubMed Central

Cusumano, Zachary

2013-01-01

In the human-pathogenic bacterium Streptococcus pyogenes, the tagatose bisphosphate aldolase LacD.1 likely originated through a gene duplication event and was adapted to a role as a metabolic sensor for regulation of virulence gene transcription. Although LacD.1 retains enzymatic activity, its ancestral metabolic function resides in the LacD.2 aldolase, which is required for the catabolism of galactose. In this study, we compared these paralogous proteins to identify characteristics correlated with divergence and novel function. Surprisingly, despite the fact that these proteins have identical active sites and 82% similarity in amino acid sequence, LacD.1 was less efficient at cleaving both fructose and tagatose bisphosphates. Analysis of kinetic properties revealed that LacD.1's adaptation was associated with a decrease in kcat and an increase in Km. Construction and analysis of enzyme chimeras indicated that non-active-site residues previously associated with the variable activities of human aldolase isoenzymes modulated LacD.1's affinity for substrate. Mutant LacD.1 proteins engineered to have LacD.2-like levels of enzymatic efficiency lost the ability to function as regulators, suggesting that an alteration in efficiency was required for adaptation. In competition under growth conditions that mimic a deep-tissue environment, LacD.1 conferred a significant gain in fitness that was associated with its regulatory activity. Taken together, these data suggest that LacD.1's adaptation represents a form of neofunctionalization in which duplication facilitated the gain of regulatory function important for growth in tissue and pathogenesis. PMID:23316044

A chemometric approach for optimizing protein covalent immobilization on magnetic core-shell nanoparticles in view of an alternative immunoassay.

PubMed

Teste, Bruno; Vial, Jérôme; Descroix, Stéphanie; Georgelin, Thomas; Siaugue, Jean-Michel; Petr, Jan; Varenne, Anne; Hennion, Marie-Claire

2010-06-15

A chemometric approach was developed to optimize the grafting of a bovine milk allergen: alpha-Lactalbumin (alpha-Lac) on colloidal functionalized magnetic core-shell nanoparticles (MCSNP). Such nanoparticles, functionalized with polyethyleneglycol and amino groups, exhibit a 30nm physical diameter and behave as a quasi-homogeneous system. The alpha-Lac immobilization was achieved through the covalent binding between MCSNP amino groups and alpha-Lac carboxylic moieties using the well-known tandem carbodiimide (EDC) and hydroxysulfosuccinimide (NHS). In this study, a chemometric approach was employed to highlight the parameters influencing the number of grafted proteins on the MCSNP. Three factors were evaluated: the ratio in concentration between EDC and alpha-Lac, between NHS and EDC and the concentration of alpha-Lac. After a first full factorial design to delimit the region of the space where the optimum could be located, a central composite design was then carried out to predict the best grafting conditions. It was established and experimentally confirmed that the optimum parameters are [EDC]/[alpha-Lac]=25; [NHS]/[EDC]=1.55 and alpha-Lac=24.85nmolmL(-1). In these optimal conditions, MCSNP surface was successfully saturated with alpha-Lac (34 alpha-Lac/MCSNP) with a high reproducibility (RSD=2%). The colloidal stability of MCSNP grafted with alpha-Lac as well as the immunological interactions using anti alpha-Lac antibody were then investigated in different buffers. The results emphasized that a 50mM MES buffer (pH 6) allows an efficient immune capture and a satisfying colloidal stability which provide an immunological interaction in homogeneous liquid phase.

Nonlinear convective pulsation models of type II Cepheids

NASA Astrophysics Data System (ADS)

Smolec, Radoslaw

2015-08-01

We present a grid of nonlinear convective pulsation models of type-II Cepheids: BL Her stars, W Vir stars and RV Tau stars. The models cover a wide range of masses, luminosities, effective temperatures and chemical compositions. The most interesting result is detection of deterministic chaos in the models. Different routes to chaos are detected (period doubling, intermittent route) as well as variety of phenomena intrinsic to chaotic dynamics (periodic islands within chaotic bands, crisis bifurcation, type-I and type-III intermittency). Some of the phenomena (period doubling in BL Her and in RV Tau stars, irregular pulsation of RV Tau stars) are well known in the pulsation of type-II Cepheids. Prospects of discovering the other are briefly discussed. Transition from BL Her type pulsation through W Vir type till RV Tau type is analysed. In the most luminous models a dynamical instability is detected, which indicates that pulsation driven mass loss is important process occurring in type-II Cepheids.

Somato-synaptic variation of GABA(A) receptors in cultured murine cerebellar granule cells: investigation of the role of the alpha6 subunit.

PubMed

Mellor, J R; Wisden, W; Randall, A D

2000-07-10

Electrophysiological investigation of cultured cerebellar murine granule cells revealed differences between the GABA(A) receptors at inhibitory synapses and those on the cell body. Specifically, mIPSCs decayed more rapidly than cell body receptors deactivated, the mean single channel conductance at the synapse (32 pS) was greater than that at cell body (21 pS) and only cell body receptors were sensitive to Zn(2+) (150 microM), which depressed response amplitude by 82+/-5% and almost doubled the rate of channel deactivation. The GABA(A) receptor alpha6 subunit is selectively expressed in cerebellar granule cells. Although concentrated at synapses, it is also found on extrasynaptic membranes. Using a mouse line (Deltaalpha6lacZ) lacking this subunit, we investigated its role in the somato-synaptic differences in GABA(A) receptor function. All differences between cell body and synaptic GABA(A) receptors observed in wild-type (WT) granule cells persisted in Deltaalpha6lacZ cells, thus demonstrating that they are not specifically due to the cellular distribution of the alpha6 subunit. However, mIPSCs from WT and Deltaalpha6lacZ cells differed in both their kinetics (faster decay in WT cells) and underlying single channel conductance (32 pS WT, 25 pS Deltaalpha6lacZ). This provides good evidence for a functional contribution of the alpha6 subunit to postsynaptic GABA(A) receptors in these cells. Despite this, deactivation kinetics of mIPSCs in WT and Deltaalpha6lacZ granule cells exhibited similar benzodiazepene (BDZ) sensitivity. This suggests that the enhanced BDZ-induced ataxia seen in Deltaalpha6lacZ mice may reflect physiological activity at extrasynaptic receptors which, unlike those at synapses, display differential BDZ-sensitivity in WT and Deltaalpha6lacZ granule cells (Jones, A.M., Korpi, E.R., McKernan, R.M., Nusser, Z., Pelz, R., Makela, R., Mellor, J.R., Pollard, S., Bahn, S., Stephenson, F.A., Randall, A.D., Sieghart, W., Somogyi, P., Smith, A.J.H., Wisden, W., 1997. Ligand-gated ion channel partnerships: GABA(A) receptor alpha(6) subunit inactivation inhibits delta subunit expression. Journal of Neuroscience 17, 1350-1362).

Optimization of Ligninolytic Enzyme Activity and Production Rate with Ceriporiopsis subvermispora for Application in Bioremediation by Varying Submerged Media Composition and Growth Immobilization Support

PubMed Central

Babič, Janja; Likozar, Blaž; Pavko, Aleksander

2012-01-01

Response surface methodology (central composite design of experiments) was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM), where the highest experimentally obtained activities and productivities were 41 U L−1 and 16 U L−1 day−1 for laccase (Lac), and 193 U L−1 and 80 U L−1 day−1 for manganese peroxidase (MnP). Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM). Enzyme activities in culture filtrate were 152 U L−1 for Lac and 58 U L−1 for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR) was decolorized faster and more efficiently than Copper(II)phthalocyanine (CuP) with BWCM (80% and 60%), since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes. PMID:23109859

Application of the central composite design to optimize the preparation of novel micelles of harmine.

PubMed

Bei, Yong-Yan; Zhou, Xiao-Feng; You, Ben-Gang; Yuan, Zhi-Qiang; Chen, Wei-Liang; Xia, Peng; Liu, Yang; Jin, Yong; Hu, Xiao-Juan; Zhu, Qiao-Ling; Zhang, Chun-Ge; Zhang, Xue-Nong; Zhang, Liang

2013-01-01

Lactose-palmitoyl-trimethyl-chitosan (Lac-TPCS), a novel amphipathic self-assembled polymer, was synthesized for administration of insoluble drugs to reduce their adverse effects. The central composite design was used to study the preparation technique of harmine (HM)-loaded self-assembled micelles based on Lac-TPCS (Lac-TPCS/HM). Three preparation methods and single factors were screened, including solvent type, HM amount, hydration volume, and temperature. The optimal preparation technique was identified after investigating the influence of two independent factors, namely, HM amount and hydration volume, on four indexes, ie, encapsulation efficiency (EE), drug-loading amount (LD), particle size, and polydispersity index (PDI). Analysis of variance showed a high coefficient of determination of 0.916 to 0.994, thus ensuring a satisfactory adjustment of the predicted prescription. The maximum predicted values of the optimal prescription were 91.62%, 14.20%, 183.3 nm, and 0.214 for EE, LD, size, and PDI, respectively, when HM amount was 1.8 mg and hydration volume was 9.6 mL. HM-loaded micelles were successfully characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and a fluorescence-quenching experiment. Sustained release of Lac-TPCS/HM reached 65.3% in 72 hours at pH 7.4, while free HM released about 99.7% under the same conditions.

Posttranslationally caused bioluminescence burst of the Escherichia coli luciferase reporter strain.

PubMed

Ideguchi, Yamato; Oshikoshi, Yuta; Ryo, Masashi; Motoki, Shogo; Kuwano, Takashi; Tezuka, Takafumi; Aoki, Setsuyuki

2016-01-01

We continuously monitored bioluminescence from a wild-type reporter strain of Escherichia coli (lacp::luc+/WT), which carries the promoter of the lac operon (lacp) fused with the firefly luciferase gene (luc+). This strain showed a bioluminescence burst when shifted into the stationary growth phase. Bioluminescence profiles of other wild-type reporter strains (rpsPp::luc+ and argAp::luc+) and gene-deletion reporter strains (lacp::luc+/crp- and lacp::luc+/lacI-) indicate that transcriptional regulation is not responsible for generation of the burst. Consistently, changes in the luciferase protein levels did not recapitulate the profile of the burst. On the other hand, dissolved oxygen levels increased over the period across the burst, suggesting that the burst is, at least partially, caused by an increase in intracellular oxygen levels. We discuss limits of the firefly luciferase when used as a reporter for gene expression and its potential utility for monitoring metabolic changes in cells.

Design and application of a lactulose biosensor.

PubMed

Wu, Jieyuan; Jiang, Peixia; Chen, Wei; Xiong, Dandan; Huang, Linglan; Jia, Junying; Chen, Yuanyuan; Jin, Jian-Ming; Tang, Shuang-Yan

2017-04-07

In this study the repressor of Escherichia coli lac operon, LacI, has been engineered for altered effector specificity. A LacI saturation mutagenesis library was subjected to Fluorescence Activated Cell Sorting (FACS) dual screening. Mutant LacI-L5 was selected and it is specifically induced by lactulose but not by other disaccharides tested (lactose, epilactose, maltose, sucrose, cellobiose and melibiose). LacI-L5 has been successfully used to construct a whole-cell lactulose biosensor which was then applied in directed evolution of cellobiose 2-epimerase (C2E) for elevated lactulose production. The mutant C2E enzyme with ~32-fold enhanced expression level was selected, demonstrating the high efficiency of the lactulose biosensor. LacI-L5 can also be used as a novel regulatory tool. This work explores the potential of engineering LacI for customized molecular biosensors which can be applied in practice.

Evaluation of coloring efficacy of lac dye in comminuted meat product.

PubMed

Divya; Singh, R P; Baboo, B; Prasad, K M

2011-06-01

Effect of incorporation of graded levels (4, 6, 8, 10, 25 ppm) of lac dye on coloring efficacy and possible use of this natural color in processed meat products was studied. Inclusion of lac dye at different concentrations did not affect the pH significantly whereas a linear increase in the Lovibond red color unit of chicken nuggets was noted with raising the level of lac dye from 4 to 10 ppm. The sensory rating for color was highest at addition level of 25 ppm of lac dye and it was comparable to color score of the product containing 200 ppm sodium nitrite. Lac dye inclusion in nuggets at all concentrations studied had better antimicrobial properties as compared to 200 ppm sodium nitrite. It was concluded that lac dye from 10 to 25 ppm could be incorporated in comminuted meat products as a natural colorant with antimicrobial action.

The business of refractive laser assisted cataract surgery (ReLACS).

PubMed

Berdahl, John P; Jensen, Matthew P

2014-01-01

Refractive Laser Assisted Cataract Surgery (ReLACS) combines the femtosecond laser with other noncovered tests and services in an attempt to reduce spectacle dependence in combination with cataract surgery. Significant interest is present among ophthalmologists who are considering adopting this technology, however significant capital outlays and continuing expenses can make the decision to adopt ReLACS foreboding. We review the financial considerations of ReLACS and review the trends seen in early adopters of this technology. Recent findings have shown that ReLACS is a growing segment of cataract surgery. Most practices who have implemented the technology have broken even and have a positive outlook on the financial return of implementing the ReLACS program. The average break-even analysis point for practices is around 230 cases a year. ReLACS is growing and appears to be a financial viable approach for many practices.

Patterns of expression of position-dependent integrated transgenes in mouse embryo.

PubMed Central

Bonnerot, C; Grimber, G; Briand, P; Nicolas, J F

1990-01-01

The abilities to introduce foreign DNA into the genome of mice and to visualize gene expression at the single-cell level underlie a method for defining individual elements of a genetic program. We describe the use of an Escherichia coli lacZ reporter gene fused to the promoter of the gene for hypoxanthine phosphoribosyl transferase that is expressed in all tissues. Most transgenic mice (six of seven) obtained with this construct express the lacZ gene from the hypoxanthine phosphoribosyltransferase promoter. Unexpectedly, however, the expression is temporally and spatially regulated. Each transgenic line is characterized by a specific, highly reproducible pattern of lacZ expression. These results show that, for expression, the integrated construct must be complemented by elements of the genome. These elements exert dominant developmental control on the hypoxanthine phosphoribosyltransferase promoter. The expression patterns in some transgenic mice conform to a typological marker and in others to a subtle combination of typology and topography. These observations define discrete heterogeneities of cell types and of certain structures, particularly in the nervous system and in the mesoderm. This system opens opportunities for developmental studies by providing cellular, molecular, and genetic markers of cell types, cell states, and cells from developmental compartments. Finally this method illustrates that genes transduced or transposed to a different position in the genome acquire different spatiotemporal specificities, a result that has implications for evolution. Images PMID:1696727

Regulation and Adaptive Evolution of Lactose Operon Expression in Lactobacillus delbrueckii

PubMed Central

Lapierre, Luciane; Mollet, Beat; Germond, Jacques-Edouard

2002-01-01

Lactobacillus delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis are both used in the dairy industry as homofermentative lactic acid bacteria in the production of fermented milk products. After selective pressure for the fast fermentation of milk in the manufacture of yogurts, L. delbrueckii subsp. bulgaricus loses its ability to regulate lac operon expression. A series of mutations led to the constitutive expression of the lac genes. A complex of insertion sequence (IS) elements (ISL4 inside ISL5), inserted at the border of the lac promoter, induced the loss of the palindromic structure of one of the operators likely involved in the binding of regulatory factors. A lac repressor gene was discovered downstream of the β-galactosidase gene of L. delbrueckii subsp. lactis and was shown to be inactivated by several mutations in L. delbrueckii subsp. bulgaricus. Regulatory mechanisms of the lac gene expression of L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis were compared by heterologous expression in Lactococcus lactis of the two lac promoters in front of a reporter gene (β-glucuronidase) in the presence or absence of the lac repressor gene. Insertion of the complex of IS elements in the lac promoter of L. delbrueckii subsp. bulgaricus increased the promoter's activity but did not prevent repressor binding; rather, it increased the affinity of the repressor for the promoter. Inactivation of the lac repressor by mutations was then necessary to induce the constitutive expression of the lac genes in L. delbrueckii subsp. bulgaricus. PMID:11807052

Evidence that selected amplification of a bacterial lac frameshift allele stimulates Lac(+) reversion (adaptive mutation) with or without general hypermutability.

PubMed Central

Slechta, E Susan; Liu, Jing; Andersson, Dan I; Roth, John R

2002-01-01

In the genetic system of Cairns and Foster, a nongrowing population of an E. coli lac frameshift mutant appears to specifically accumulate Lac(+) revertants when starved on medium including lactose (adaptive mutation). This behavior has been attributed to stress-induced general mutagenesis in a subpopulation of starved cells (the hypermutable state model). We have suggested that, on the contrary, stress has no direct effect on mutability but favors only growth of cells that amplify their leaky mutant lac region (the amplification mutagenesis model). Selection enhances reversion primarily by increasing the mutant lac copy number within each developing clone on the selection plate. The observed general mutagenesis is attributed to a side effect of growth with an amplification-induction of SOS by DNA fragments released from a tandem array of lac copies. Here we show that the S. enterica version of the Cairns system shows SOS-dependent general mutagenesis and behaves in every way like the original E. coli system. In both systems, lac revertants are mutagenized during selection. Eliminating the 35-fold increase in mutation rate reduces revertant number only 2- to 4-fold. This discrepancy is due to continued growth of amplification cells until some clones manage to revert without mutagenesis solely by increasing their lac copy number. Reversion in the absence of mutagenesis is still dependent on RecA function, as expected if it depends on lac amplification (a recombination-dependent process). These observations support the amplification mutagenesis model. PMID:12136002

Antisense RNA: effect of ribosome binding sites, target location, size, and concentration on the translation of specific mRNA molecules.

PubMed

Daugherty, B L; Hotta, K; Kumar, C; Ahn, Y H; Zhu, J D; Pestka, S

1989-01-01

A series of plasmids were constructed to generate RNA complementary to the beta-galactosidase messenger RNA under control of the phage lambda PL promoter. These plasmids generate anti-lacZ mRNA bearing or lacking a synthetic ribosome binding site adjacent to the lambda PL promoter and/or the lacZ ribosome binding site in reverse orientation. Fragments of lacZ DNA from the 5' and/or the 3' region were used in these constructions. When these anti-mRNA molecules were produced in Escherichia coli 294, maximal inhibition of beta-galactosidase synthesis occurred when a functional ribosome binding site was present near the 5' end of the anti-mRNA and the anti-mRNA synthesized was complementary to the 5' region of the mRNA corresponding to the lacZ ribosome binding site and/or the 5'-coding sequence. Anti-mRNAs producing maximal inhibition of beta-galactosidase synthesis exhibited an anti-lacZ mRNA:normal lacZ mRNA ratio of 100:1 or higher. Those showing lower levels of inhibition exhibited much lower anti-lacZ mRNA:normal lacZ mRNA ratios. A functional ribosome binding site at the 5'-end was found to decrease the decay rate of the anti-lacZ mRNAs. In addition, the incorporation of a transcription terminator just downstream of the antisense segment provided for more efficient inhibition of lacZ mRNA translation due to synthesis of smaller and more abundant anti-lacZ mRNAs. The optimal constructions produced undetectable levels of beta-galactosidase synthesis.

Proteins mediating DNA loops effectively block transcription.

PubMed

Vörös, Zsuzsanna; Yan, Yan; Kovari, Daniel T; Finzi, Laura; Dunlap, David

2017-07-01

Loops are ubiquitous topological elements formed when proteins simultaneously bind to two noncontiguous DNA sites. While a loop-mediating protein may regulate initiation at a promoter, the presence of the protein at the other site may be an obstacle for RNA polymerases (RNAP) transcribing a different gene. To test whether a DNA loop alters the extent to which a protein blocks transcription, the lac repressor (LacI) was used. The outcome of in vitro transcription along templates containing two LacI operators separated by 400 bp in the presence of LacI concentrations that produced both looped and unlooped molecules was visualized with scanning force microscopy (SFM). An analysis of transcription elongation complexes, moving for 60 s at an average of 10 nt/s on unlooped DNA templates, revealed that they more often surpassed LacI bound to the lower affinity O2 operator than to the highest affinity Os operator. However, this difference was abrogated in looped DNA molecules where LacI became a strong roadblock independently of the affinity of the operator. Recordings of transcription elongation complexes, using magnetic tweezers, confirmed that they halted for several minutes upon encountering a LacI bound to a single operator. The average pause lifetime is compatible with RNAP waiting for LacI dissociation, however, the LacI open conformation visualized in the SFM images also suggests that LacI could straddle RNAP to let it pass. Independently of the mechanism by which RNAP bypasses the LacI roadblock, the data indicate that an obstacle with looped topology more effectively interferes with transcription. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

Extraordinary Activity in the BL Lacertae Object OJ 287

NASA Astrophysics Data System (ADS)

Hughes, Philip A.; Aller, Hugh D.; Aller, Margo F.

1998-08-01

We use a continuous wavelet transform to analyze more than two decades of data for the BL Lac object OJ 287 acquired as part of the University of Michigan Radio Astronomy Observatory (UMRAO) variability program. We find clear evidence for a persistent modulation of the total flux and polarization with period ~1.66 yr and for another signal that dominates activity in the 1980s with period ~1.12 yr. The relationship between these two variations can be understood in terms of a ``shock-in-jet'' model, in which the longer timescale periodicity is associated with an otherwise quiescent jet and the shorter timescale activity is associated with the passage of a shock. The different periodicities of these two components may reflect different internal conditions of the two flow domains leading to different wave speeds or different contractions of a single underlying periodicity due to the different Doppler factors of the two flow components. We suggest that the modulation arises from a wave driven by some asymmetric disturbance close to the central engine. The periodic behavior in polarization exhibits excursions in U that correspond to a direction ~45° from the VLBI jet axis. This behavior is not explained by the random walk in the Q-U plane that is expected from models in which a pattern of randomly aligned magnetic field elements propagate across the visible portion of the flow and suggests a small amplitude, cyclic variation in the flow direction in that part of the flow that dominates centimeter wavelength emission.

Water quality and hydrology of the Lac Vieux Desert watershed, Gogebic County, Michigan, and Vilas County, Wisconsin, 2002-04

USGS Publications Warehouse

Weaver, T.L.; Neff, B.P.; Ellis, J.M.

2005-01-01

Lac Vieux Desert is a prominent 6.6 square-mile lake that straddles the Michigan-Wisconsin border and forms the headwaters of the Wisconsin River. For generations, the Lac Vieux Desert Band of Lake Superior Chippewa Indians have used Lac Vieux Desert and the surrounding area for growing and harvesting wild rice, and hunting and fishing. The Lac Vieux Desert Band is concerned about the impact of lake-stage regulation on hydrology and ecology, and the impact on water quality of development along and near the shore, and recreational watercraft use and sport fishing. In 2005, the U.S. Geological Survey completed a water-resources investigation of the Lac Vieux Desert watershed in cooperation with the Lac Vieux Desert Band of Lake Superior Chippewa Indians.Water quality of Lac Vieux Desert is typical of many lakes in the northern United States. Trophic State Index calculations classify Lac Vieux Desert as a highly productive eutrophic lake. The pH of water in Lac Vieux Desert ranged from 6.5 to 9.5, and specific conductance ranged from 62 to 114 µs/cm. Chloride concentration was less than 1.5 mg/L, indicating little effect from septic-tank or road-salt input. Results indicate that the water can be classified as soft, with hardness concentrations reported as calcium carbonate ranging from 29 to 49 mg/L. Concentrations of calcium, magnesium, chloride, and other dissolved solids ranged from 47 to 77 mg/L. Alkalinity of Lac Vieux Desert ranged from 27 to 38 mg/L.Pervasive aquatic blooms, including a bloom noted during the September 2003 sampling, are apparently common in late summer. Biological productivity at Lac Vieux Desert does not appear to have changed appreciably between 1973 and 2004. In the current study, total phosphorus concentrations ranged from 0.01 to 0.064 mg/L and dissolved nitrite plus nitrate nitrogen concentrations ranged from at, or below detection limit to 0.052 mg/L. Overabundance of nutrients in Lac Vieux Desert, particularly nitrogen and phosphorus, could result in considerable degradation in lake-water quality.The estimated water balance includes the following inputs from the surrounding watershed: direct precipitation (35 percent); runoff, composed of streamflow and overland flow (50 percent); and ground-water flow (15 percent). Outputs from Lac Vieux Desert include streamflow into the Wisconsin River (68 percent) and evaporation from the lake surface (32 percent). Seasonal regulation of Lac Vieux Desert outflow results in an artificially high lake stage throughout the year, except from late winter to very early spring, prior to snowmelt and runoff. Regulation of Lac Vieux Desert outflow causes Wisconsin River streamflow to be artificially low during spring and summer and artificially high in fall and winter.Recent studies indicate that lake-level regulation over the past century may have affected wild rice growth and propagation in Lac Vieux Desert. As per licensing agreement between the Federal Energy Regulatory Commission and the Wisconsin Valley Improvement Company (operators of the dam at the outlet), the maximum lake level of Lac Vieux Desert was lowered about 0.8 feet to investigate the relation between lake-level regulation and propagation of wild rice from 2003 through 2012. Recent plantings of wild rice by the Lac Vieux Desert Band have been successful, indicating that suitable habitat and hydrologic regime were present in 2004-05.

Type-Specific HPV Prevalence in Cervical Cancer and High-Grade Lesions in Latin America and the Caribbean: Systematic Review and Meta-Analysis

PubMed Central

Ciapponi, Agustín; Bardach, Ariel; Glujovsky, Demián; Gibbons, Luz; Picconi, María Alejandra

2011-01-01

Background Cervical cancer is a major public health problem in Latin America and the Caribbean (LA&C), showing some of the highest incidence and mortality rates worldwide. Information on HPV type distribution in high-grade cervical lesions (HSIL) and invasive cervical cancer (ICC) is crucial to predict the future impact of HPV16/18 vaccines and screening programmes, and to establish an appropriate post-vaccinal virologic surveillance. The aim was to assess the prevalence of HPV types in HSIL and ICC in studies in LA&C. Methods and Findings We performed a systematic review, following the MOOSE guidelines for systematic reviews of observational studies, and the PRISMA statement for reporting systematic reviews and meta-analyses. Inclusion criteria were at least ten cases of HSIL/ICC, and HPV-type elicitation. The search, without language restrictions, was performed in MEDLINE, Cochrane Library, EMBASE, LILACS from inception date to December 2009, proceedings, reference lists and consulting experts. A meta-analysis was performed using arc-sine transformations to stabilize the variance of simple proportions. Seventy-nine studies from 18 countries were identified, including 2446 cases of HSIL and 5540 of ICC. Overall, 46.5% of HSIL cases harbored HPV 16 and 8.9% HPV18; in ICC, 53.2% of cases harbored HPV 16 and13.2% HPV 18. The next five most common types, in decreasing frequency, were HPV 31, 58, 33, 45, and 52. Study's limitations comprise the cross-sectional design of most included studies and their inherent risk of bias, the lack of representativeness, and variations in the HPV type-specific sensitivity of different PCR protocols. Conclusions This study is the broadest summary of HPV type distribution in HSIL and ICC in LA&C to date. These data are essential for local decision makers regarding HPV screening and vaccination policies. Continued HPV surveillance would be useful, to assess the potential for changing type-specific HPV prevalence in the post-vaccination era in Latin America. PMID:21991313

The impact of dnaKJ overexpression on recombinant protein solubility results from antagonistic effects on the control of protein quality.

PubMed

Petersson, Lisa; Carrió, M Mar; Vera, Andrea; Villaverde, Antonio

2004-04-01

We have produced increasing levels of DnaK and its co-chaperone DnaJ along with the model VP1LAC misfolding-prone protein, to explore the role of DnaK on the management of Escherichia coli inclusion bodies. While relative solubility of VP1LAC is progressively enhanced, the heat-shock response is down-regulated as revealed by decreasing levels of GroEL. This is accompanied by an increasing yield of VP1LAC and a non-regular evolution of its insoluble fraction, at moderate levels of DnaK resulting in more abundant inclusion bodies. Also, the impact of chaperone co-expression is much more pronounced in wild type cells than in a DnaK- mutant, probably due to the different background of heat shock proteins in these cells. The involvement of DnaK in the supervision of misfolding proteins is then pictured as a dynamic balance between its immediate holding and folding activities, and the side-effect downregulation of the heat shock response though the limitation of other chaperone and proteases activities.

Mouse alpha1(I)-collagen promoter is the best known promoter to drive efficient Cre recombinase expression in osteoblast.

PubMed

Dacquin, Romain; Starbuck, Michael; Schinke, Thorsten; Karsenty, Gérard

2002-06-01

Cell- and time-specific gene inactivation should enhance our knowledge of bone biology. Implementation of this technique requires construction of transgenic mouse lines expressing Cre recombinase in osteoblasts, the bone forming cell. We tested several promoter fragments for their ability to drive efficient Cre expression in osteoblasts. In the first mouse transgenic line, the Cre gene was placed under the control of the 2.3-kb proximal fragment of the alpha1(I)-collagen promoter, which is expressed at high levels in osteoblasts throughout their differentiation. Transgenic mice expressing this transgene in bone were bred with the ROSA26 reporter (R26R) strain in which the ROSA26 locus is targeted with a conditional LacZ reporter cassette. In R26R mice, Cre expression and subsequent Cre-mediated recombination lead to expression of the LacZ reporter gene, an event that can be monitored by LacZ staining. LacZ staining was detected in virtually all osteoblasts of alpha1(I)-Cre;R26R mice indicating that homologous recombination occurred in these cells. No other cell type stained blue. In the second line studied, the 1.3-kb fragment of osteocalcin gene 2 (OG2) promoter, which is active in differentiated osteoblasts, was used to drive Cre expression. OG2-Cre mice expressed Cre specifically in bone. However, cross of OG2-Cre mice with R26R mice did not lead to any detectable LacZ staining in osteoblasts. Lastly, we tested a more active artificial promoter derived from the OG2 promoter. The artificial OG2-Cre transgene was expressed by reverse transcriptase-polymerase chain reaction in cartilage and bone samples. After cross of the artificial OG2-Cre mice with R26R mice, we detected a LacZ staining in articular chondrocytes but not in osteoblasts. Our data suggest that the only promoter able to drive Cre expression at a level sufficient to induce recombination in osteoblasts is the alpha1(I)-collagen promoter. Copyright 2002 Wiley-Liss, Inc.

Data Collection: A Cybernetic Aspect of a Learning Assistance Center.

ERIC Educational Resources Information Center

Devirian, Margaret Coda

Data collection and analysis as a cybernetic aspect of a Learning Assistance Center (LAC) is discussed. Using the LAC at California State University Long Beach (CSULB) as a model, the LAC is defined as a support, delivery, and referral service for the entire campus community. A LAC is held accountable to itself and its users through a cybernetics…

The Health Role of Local Area Coordinators in Scotland: A Mixed Methods Study

ERIC Educational Resources Information Center

Brown, Michael; Karatzias, Thanos; O'Leary, Lisa

2013-01-01

The study set out to explore whether local area coordinators (LACs) and their managers view the health role of LACs as an essential component of their work and identify the health-related activities undertaken by LACs in Scotland. A mixed methods cross-sectional phenomenological study involving local authority service managers (n = 25) and LACs (n…

The Post-Dam System. Volume 4. Relational Data Base Management System (RDBMS)

DTIC Science & Technology

1992-10-01

15 THEN LOAD item FROM b15.mat ENDIF IF vfle EQ 16 THEN LOAD item FROM b16 .mat ENDIF IF vfle EQ 17 THEN LOAD item FROM b17.mat ENDIF IF vfle EQ 18...vple EQ 16 THEN LOAD reqet FROM bl6 .eqp ENDIF IF vple EQ 17 THEN LOAD reqet FROM bl7.eqp ENDIF IF vple EQ 18 THEN LOAD reqet FROM bl8.eqp ENDIF IF vple...b3.out ENDIF IF tWle EQ 14 THEN TYPE b14.out ENDIF IF tWle EQ 15 THEN 70 TYPE bIS.out ENDIF IF tfle EQ 16 THEN TYPE b16 .out ENDIF IF tfle EQ 17 THEN

Increased circular RNA hsa_circ_0012673 acts as a sponge of miR-22 to promote lung adenocarcinoma proliferation.

PubMed

Wang, Xiyong; Zhu, Xiaoli; Zhang, Hongming; Wei, Shuzhen; Chen, Yan; Chen, Yang; Wang, Fei; Fan, Xiaobo; Han, Shuhua; Wu, Guoqiu

2018-02-19

Recent reports have indicated that circular RNA (circRNA) may regulate Lung adenocarcinoma (LAC) development. Our previous studies showed that hsa_circ_0012673 was up-regulated in a circRNA microarray. However, its expression level in LAC has not been verified, and the underlying molecular mechanisms in LAC are unknown. In this study, we found that the expression of hsa_circ_0012673 was up-regulated in LAC tissues compared to pair-matched adjacent non-tumor tissues (P = 0.0079), and that the expression level was associated with tumour size (P = 0.015). Furthermore, hsa_circ_0012673 was primarily localized in the cytoplasm and promoted cell proliferation of LAC cells by sponging miR-22, which targeted erb-b2 receptor tyrosine kinase 3 (ErbB3) in LAC. Hsa_circ_0012673 promotes LAC proliferation by suppressing miR-22, which targets ErbB3. Copyright © 2018 Elsevier Inc. All rights reserved.

Enhanced phenol removal in an innovative lignite activated coke-assisted biological process.

PubMed

Zhang, Chen; Li, Jianfeng; Cheng, Fangqin; Liu, Yu

2018-07-01

In this study, a lignite activated coke (LAC)-assisted activated sludge (AS) process was developed for enhancing biodegradation of phenol, while the effects of LAC on sludge properties and microbial community structure were investigated. It was found that more than 90% of phenol was removed within 1 h in the LAC/AS, which was 3 times higher than the conventional AS process. Moreover, the floc size and settleability were also significantly improved in the LAC/AS. These results suggested that LAC could serve as the nucleating agent to promote the formation of compact floc, which was beneficial for toxicity mitigation and system stability. The microbial community analysis by 16S high-throughput pyrosequencing technology further revealed a more abundant bacterial richness and diversity in the LAC/AS process loaded with phenol, while some phenol degraders, such as Propionibacteriaceae were enriched. Engineering implications further suggests the LAC-assisted AS process is technically sound and economically viable. Copyright © 2018 Elsevier Ltd. All rights reserved.

Light absorbing carbon emissions from commercial shipping

NASA Astrophysics Data System (ADS)

Lack, Daniel; Lerner, Brian; Granier, Claire; Baynard, Tahllee; Lovejoy, Edward; Massoli, Paola; Ravishankara, A. R.; Williams, Eric

2008-07-01

Extensive measurements of the emission of light absorbing carbon aerosol (LAC) from commercial shipping are presented. Vessel emissions were sampled using a photoacoustic spectrometer in the Gulf of Mexico region. The highest emitters (per unit fuel burnt) are tug boats, thus making significant contributions to local air quality in ports. Emission of LAC from cargo and non cargo vessels in this study appears to be independent of engine load. Shipping fuel consumption data (2001) was used to calculate a global LAC contribution of 133(+/-27) Ggyr-1, or ~1.7% of global LAC. This small fraction could have disproportionate effects on both air quality near port areas and climate in the Arctic if direct emissions of LAC occur in that region due to opening Arctic sea routes. The global contribution of this LAC burden was investigated using the MOZART model. Increases of 20-50 ng m-3 LAC (relative increases up to 40%) due to shipping occur in the tropical Atlantic, Indonesia, central America and the southern regions of South America and Africa.

Synchrotron and Synchrotron Self-Compton Spectral Signatures and Blazar Emission Models

NASA Technical Reports Server (NTRS)

Chiang, James; Boettcher, Markus; White, Nicholas E. (Technical Monitor)

2002-01-01

We find that energy losses due to synchrotron self-Compton (BBC) emission in Blazar jets can produce distinctive signatures in the time-averaged synchrotron and SSC spectra of these objects. For a fairly broad range of particle injection distributions, SSC-loss-dominated synchrotron emission exhibits a spectral dependence Fv approximately v (exp -3/2). The presence or absence of this dependence in the optical and ultraviolet spectra of flat-spectrum radio quasars such as PC 279 and in the soft X-ray spectra of high-frequency BL Lac objects such as Mark 501 gives a robust measure of the importance of SSC losses. Furthermore, for partially cooled particle distributions, spectral breaks of varying sizes can appear in the synchrotron and SSC spectra and will be related to the spectral indices of the emission below the break. These spectral signatures place constraints on the size scale and the nonthermal particle content of the emitting plasma, as well as the observer orientation relative to the jet axis.

An RXTE Study of M87 and the Core of the Virgo Cluster

NASA Technical Reports Server (NTRS)

Reynolds, Christopher S.; Heinz, Sebastian; Fabian, Andrew C.; Begelman, Mitchell C.

1998-01-01

We present hard X-ray observations of the nearby radio galaxy M87 and the core of the Virgo cluster using the Rossi X-ray Timing Explorer. These are the first hard X-ray observations of M87 not affected by contamination from the nearby Seyfert 2 galaxy NGC 4388. Thermal emission from Virgo's intracluster medium is clearly detected and has a spectrum indicative of kT approx. = 2.5 keV plasma with approximately 25% cosmic abundances. No non-thermal (power-law) emission from M87 is detected in the hard X-ray band, with fluctuations in the Cosmic X-ray Background being the limiting factor. Combining with ROSAT data, we infer that the X-ray spectrum of the M87 core and jet must be steep (Gamma(sub core) greater than 1.90 and Gamma(sub jet) greater than 1.75), and we discuss the implications of this result. In particular, these results are consistent with M87 being a mis-aligned BL-Lac object.

Development of a spectral break in the nonthermal emission of AO 0235+164

NASA Technical Reports Server (NTRS)

Odell, S. L.; Puschell, J. J.; Stein, W. A.; Warner, J. W.

1977-01-01

Results are reported for braod-band photometry of the BL Lac object AO 0235+164 carried out over the spectral range from 0.36 to 3.5 microns in December 1975 and in October and November 1976. It is found that the continuum of this object steepened at visible wavelengths between December 1975 and October 1976, but maintained a relatively constant slope in the near-IR despite a factor-of-ten decrease in flux from the maximum level. Visible-wavelength data are cited which appear to suggest that the steepening of the visible spectrum occurred in less than 300 days, while the near-IR level may have been nearly constant. It is shown that the observed change in the spectral shape of the visible-wavelength continuum cannot be explained in terms of a 'composite' model consisting of an unchanging galaxy and a varying nonthermal source with constant spectral index. Two other general classes of models are considered: intrinsic variability and extrinsic modulation.

An RXTE Study of M87 and the Core of the Virgo Cluster

NASA Technical Reports Server (NTRS)

Reynolds, Christopher S.; Heinz, Sebastian; Fabian, Andrew C.; Begelman, Mitchell C.

1998-01-01

We present hard X-ray observations of the nearby radio galaxy M87 and the core of the Virgo cluster using the Rossi X-ray 7Tming Explorer. These are the first hard X-ray observations of M87 not affected by contamination from the nearby Seyfert 2 galaxy NGC 4388. Thermal emission from Virgo's intracluster medium is clearly detected and has a spectrum indicative of kT is approximately equal to 2.5 keV plasma with approximately 25% cosmic abundances. No non-thermal (power-law) emission from M87 is detected in the hard X-ray band, with fluctuations in the Cosmic X-ray Background being the limiting factor. Combining with ROSAT data, we infer that the X-ray spectrum of the M87 core and jet must be steep (Gamma (sub core) > 1.90 and Gamma (sub jet) > 1.75), and we discuss the implications of this result. In particular, these results are consistent with M87 being a mis-aligned BL-Lac object.

VizieR Online Data Catalog: Gamma-ray bright blazars spectrophotometry (Williamson+, 2014)

NASA Astrophysics Data System (ADS)

Williamson, K. E.; Jorstad, S. G.; Marscher, A. P.; Larionov, V. M.; Smith, P. S.; Agudo, I.; Arkharov, A. A.; Blinov, D. A.; Casadio, C.; Efimova, N. V.; Gomez, J. L.; Hagen-Thorn, V. A.; Joshi, M.; Konstantinova, T. S.; Kopatskaya, E. N.; Larionova, E. G.; Larionova, L. V.; Malmrose, M. P.; McHardy, I. M.; Molina, S. N.; Morozova, D. A.; Schmidt, G. D.; Taylor, B. W.; Troitsky, I. S.

2017-03-01

Since 2007, we have been collecting multi-waveband fluxes, polarization measurements, and radio images of blazars to provide the data for understanding the physics of the jets (see, e.g., Marscher 2012, arXiv:1201.5402). This study includes 28 of the original 30 objects selected for the monitoring campaign, confirmed as γ-ray sources by EGRET (Energetic γ-Ray Experiment Telescope) on the Compton Gamma Ray Observatory, have an R-band brightness exceeding 18 mag (bright enough for optical polarization measurements at a 1-2 m class optical telescope without needing excessive amounts of telescope time), exceed 0.5 Jy at 43 GHz, and have a declination accessible to the collaboration's observatories (> - 30°). Three additional BL Lacs (1055+018, 1308+326, and 1749+096) and two FSRQs (3C345 and 3C446) included in this analysis were among those added when they were detected as γ-ray sources by the Fermi LAT (Abdo et al. 2009, J/ApJ/700/597). (4 data files).

Medium-resolution far-ultraviolet spectroscopy of PKS 2155-304

NASA Technical Reports Server (NTRS)

Appenzeller, I.; Mandel, H.; Krautter, J.; Bowyer, S.; Hurwitz, M.; Grewing, M.; Kramer, G.; Kappelmann, N.

1995-01-01

Using the Berkeley spectrometer of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) we observed the 87-117 nm UV spectrum of the BL Lac object PKS 2155-304 with about 0.5 A resolution. In addition to the expected interstellar lines we detected higher quantum number counterparts of the intergalactic Lyman alpha lines discovered earlier with IUE and the Hubble Space Telescope (HST) in the direction of PKS 2155-304. The Lyman discontinuities indicate for three of the redshifted clouds a combined H I column density of 2-5 x 10(exp 16)/sq cm, while the column density for another cloud appears to be well below 5 x 10(exp 15)/sq cm. No siginificant O VI absorption in the galactic halo toward PKS 2155-304 could be detected from our data. Assuming that saturation effects are negligible for these weak features, we obtain for the O VI column density toward PKS 2155-304 a 3 sigma upper limit of 2.7 x 10(exp 14)/sq cm.

S5 0716+714: GeV variability study

DOE PAGES

Rani, B.; Krichbaum, T. P.; Lott, B.; ...

2013-02-19

The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV–300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. In addition, we also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from amore » simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. Finally, we discuss several possible scenarios to explain the observed spectral break.« less

S5 0716+714: GeV variability study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, B.; Krichbaum, T. P.; Lott, B.

The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV–300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. In addition, we also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from amore » simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. Finally, we discuss several possible scenarios to explain the observed spectral break.« less

Results from the energetic gamma-ray experiment telescope (EGRET) on the Compton Observatory

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Bertsch, D. L.; Dingus, B.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) covers the high energy gamma ray energy range, approximately 30 MeV to 30 GeV, with a sensitivity considerably greater than earlier high energy gamma-ray satellites. Thus far, 4 pulsars have been detected and their properties measured, including in 3 cases the energy spectrum as a function of phase. The details of the galactic plane are being mapped and a spectra of the center region has been obtained in good agreement with that expected from cosmic ray interactions. The Magellanic clouds have been examined with the Large Magellanic Cloud (LMC) having been detected at a level consistent with it having a cosmic ray density compatible with quasi-stable equilibrium. Sixteen Active Galactic Nuclei (AGN's) have been seen thus far with a high degree of certainty including 12 quasars and 4 BL Lac objects, but no Seyferts. Time variation has been detected in some of these AGN's

Characteristics of randomized trials published in Latin America and the Caribbean according to funding source.

PubMed

Reveiz, Ludovic; Sangalang, Stephanie; Glujovsky, Demian; Pinzon, Carlos E; Asenjo Lobos, Claudia; Cortes, Marcela; Cañón, Martin; Bardach, Ariel; Bonfill, Xavier

2013-01-01

Few studies have assessed the nature and quality of randomized controlled trials (RCTs) in Latin America and the Caribbean (LAC). The aims of this systematic review are to evaluate the characteristics (including the risk of bias assessment) of RCT conducted in LAC according to funding source. A review of RCTs published in 2010 in which the author's affiliation was from LAC was performed in PubMed and LILACS. Two reviewers independently extracted data and assessed the risk of bias. The primary outcomes were risk of bias assessment and funding source. A total of 1,695 references were found in PubMed and LILACS databases, of which 526 were RCTs (N = 73.513 participants). English was the dominant publication language (93%) and most of the RCTs were published in non-LAC journals (84.2%). Only five of the 19 identified countries accounted for nearly 95% of all RCTs conducted in the region (Brazil 70.9%, Mexico 10.1%, Argentina 5.9%, Colombia 3.8%, and Chile 3.4%). Few RCTs covered priority areas related with Millennium Development Goals like maternal health (6.7%) or high priority infectious diseases (3.8%). Regarding children, 3.6% and 0.4% RCT evaluated nutrition and diarrhea interventions respectively but none pneumonia. As a comparison, aesthetic and sport related interventions account for 4.6% of all trials. A random sample of RCTs (n = 358) was assessed for funding source: exclusively public (33.8%); private (e.g. pharmaceutical company) (15.3%); other (e.g. mixed, NGO) (15.1%); no funding (35.8%). Overall assessments for risk of bias showed no statistically significant differences between RCTs and type of funding source. Statistically significant differences favoring private and others type of funding was found when assessing trial registration and conflict of interest reporting. Findings of this study could be used to provide more direction for future research to facilitate innovation, improve health outcomes or address priority health problems.

Characteristics of Randomized Trials Published in Latin America and the Caribbean According to Funding Source

PubMed Central

Reveiz, Ludovic; Sangalang, Stephanie; Glujovsky, Demian; Pinzon, Carlos E.; Asenjo Lobos, Claudia; Cortes, Marcela; Cañón, Martin; Bardach, Ariel; Bonfill, Xavier

2013-01-01

Introduction Few studies have assessed the nature and quality of randomized controlled trials (RCTs) in Latin America and the Caribbean (LAC). Methods and Findings The aims of this systematic review are to evaluate the characteristics (including the risk of bias assessment) of RCT conducted in LAC according to funding source. A review of RCTs published in 2010 in which the author's affiliation was from LAC was performed in PubMed and LILACS. Two reviewers independently extracted data and assessed the risk of bias. The primary outcomes were risk of bias assessment and funding source. A total of 1,695 references were found in PubMed and LILACS databases, of which 526 were RCTs (N = 73.513 participants). English was the dominant publication language (93%) and most of the RCTs were published in non-LAC journals (84.2%). Only five of the 19 identified countries accounted for nearly 95% of all RCTs conducted in the region (Brazil 70.9%, Mexico 10.1%, Argentina 5.9%, Colombia 3.8%, and Chile 3.4%). Few RCTs covered priority areas related with Millennium Development Goals like maternal health (6.7%) or high priority infectious diseases (3.8%). Regarding children, 3.6% and 0.4% RCT evaluated nutrition and diarrhea interventions respectively but none pneumonia. As a comparison, aesthetic and sport related interventions account for 4.6% of all trials. A random sample of RCTs (n = 358) was assessed for funding source: exclusively public (33.8%); private (e.g. pharmaceutical company) (15.3%); other (e.g. mixed, NGO) (15.1%); no funding (35.8%). Overall assessments for risk of bias showed no statistically significant differences between RCTs and type of funding source. Statistically significant differences favoring private and others type of funding was found when assessing trial registration and conflict of interest reporting. Conclusion Findings of this study could be used to provide more direction for future research to facilitate innovation, improve health outcomes or address priority health problems. PMID:23418566

Identification and Characterization of Genes Required for Early Myxococcus xanthus Developmental Gene Expression

PubMed Central

Guo, Dongchuan; Wu, Yun; Kaplan, Heidi B.

2000-01-01

Starvation and cell density regulate the developmental expression of Myxococcus xanthus gene 4521. Three classes of mutants allow expression of this developmental gene during growth on nutrient agar, such that colonies of strains containing a Tn5 lac Ω4521 fusion are Lac+. One class of these mutants inactivates SasN, a negative regulator of 4521 expression; another class activates SasS, a sensor kinase-positive regulator of 4521 expression; and a third class blocks lipopolysaccharide (LPS) O-antigen biosynthesis. To identify additional positive regulators of 4521 expression, 11 Lac− TnV.AS transposon insertion mutants were isolated from a screen of 18,000 Lac+ LPS O-antigen mutants containing Tn5 lac Ω4521 (Tcr). Ten mutations identified genes that could encode positive regulators of 4521 developmental expression based on their ability to abolish 4521 expression during development in the absence of LPS O antigen and in an otherwise wild-type background. Eight of these mutations mapped to the sasB locus, which encodes the known 4521 regulators SasS and SasN. One mapped to sasS, whereas seven identified new genes. Three mutations mapped to a gene encoding an NtrC-like response regulator homologue, designated sasR, and four others mapped to a gene designated sasP. One mutation, designated ssp10, specifically suppressed the LPS O-antigen defect; the ssp10 mutation had no effect on 4521 expression in an otherwise wild-type background but reduced 4521 developmental expression in the absence of LPS O antigen to a level close to that of the parent strain. All of the mutations except those in sasP conferred defects during growth and development. These data indicate that a number of elements are required for 4521 developmental expression and that most of these are necessary for normal growth and fruiting body development. PMID:10913090

ALMACAL IV: A catalogue of ALMA calibrator continuum observations

NASA Astrophysics Data System (ADS)

Bonato, M.; Liuzzo, E.; Giannetti, A.; Massardi, M.; De Zotti, G.; Burkutean, S.; Galluzzi, V.; Negrello, M.; Baronchelli, I.; Brand, J.; Zwaan, M. A.; Rygl, K. L. J.; Marchili, N.; Klitsch, A.; Oteo, I.

2018-05-01

We present a catalogue of ALMA flux density measurements of 754 calibrators observed between August 2012 and September 2017, for a total of 16,263 observations in different bands and epochs. The flux densities were measured reprocessing the ALMA images generated in the framework of the ALMACAL project, with a new code developed by the Italian node of the European ALMA Regional Centre. A search in the online databases yielded redshift measurements for 589 sources (˜78 per cent of the total). Almost all sources are flat-spectrum, based on their low-frequency spectral index, and have properties consistent with being blazars of different types. To illustrate the properties of the sample we show the redshift and flux density distributions as well as the distributions of the number of observations of individual sources and of time spans in the source frame for sources observed in bands 3 (84-116 GHz) and 6 (211-275 GHz). As examples of the scientific investigations allowed by the catalogue we briefly discuss the variability properties of our sources in ALMA bands 3 and 6 and the frequency spectra between the effective frequencies of these bands. We find that the median variability index steadily increases with the source-frame time lag increasing from 100 to 800 days, and that the frequency spectra of BL Lacs are significantly flatter than those of flat-spectrum radio quasars. We also show the global spectral energy distributions of our sources over 17 orders of magnitude in frequency.

The high-energy γ -ray emission of AP Librae

DOE PAGES

Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; ...

2014-12-10

In this paper, the γ-ray spectrum of the low-frequency-peaked BL Lac (LBL) object AP Librae is studied, following the discovery of very-high-energy (VHE; E> 100 GeV) γ-ray emission up to the TeV range by the H.E.S.S. experiment. This makes AP Librae one of the few VHE emitters of the LBL type. The measured spectrum yields a flux of (8.8 ± 1.5 stat ± 1.8 sys) × 10 -12 cm -2 s -1 above 130 GeV and a spectral index of Γ = 2.65 ± 0.19 stat ± 0.20 sys. This study also makes use of Fermi-LAT observations in the highmore » energy (HE, E> 100 MeV) range, providing the longest continuous light curve (5 years) ever published on this source. The source underwent a flaring event between MJD 56 306–56 376 in the HE range, with a flux increase of a factor of 3.5 in the 14 day bin light curve and no significant variation in spectral shape with respect to the low-flux state. While the H.E.S.S. and (low state) Fermi-LAT fluxes are in good agreement where they overlap, a spectral curvature between the steep VHE spectrum and the Fermi-LAT spectrum is observed. Finally, the maximum of the γ-ray emission in the spectral energy distribution is located below the GeV energy range.« less

VizieR Online Data Catalog: CRTS close supermassive black hole binaries (Graham+, 2015)

NASA Astrophysics Data System (ADS)

Graham, M. J.; Djorgovski, S. G.; Stern, D.; Drake, A. J.; Mahabal, A. A.; Donalek, C.; Glikman, E.; Larson, S.; Christensen, E.

2016-02-01

CRTS leverages the Catalina Sky Survey data streams from three telescopes - the 0.7m Catalina Sky Survey Schmidt and 1.5m Mount Lemmon Survey telescopes in Arizona, and the 0.5m Siding Springs Survey Schmidt in Australia - used in a search for Near-Earth Objects, operated by Lunar and Planetary Laboratory at University of Arizona. CRTS covers up to ~2500deg2 per night, with four exposures per visit, separated by 10-min, over 21 nights per lunation. All data are automatically processed in real-time, and optical transients are immediately distributed using a variety of electronic mechanisms. The data are broadly calibrated to Johnson V (see Drake et al., 2013, Cat. J/ApJ/763/32 for details) and the full CRTS data set contains time series for approximately 500 million sources. The Million Quasars (MQ) catalogue v3.7 contains all spectroscopically confirmed type 1 QSOs (309525), AGN (21728) and BL Lacs (1573) in the literature up to 2013 November 26 and formed the basis for the results of Graham et al. (2015Natur.518...74G). We have extended this with 297301 spectroscopically identified quasars in the SDSS Data Release 12 (Paris et al., in preparation). We cross-matched this combined quasar list against the CRTS data set with a 3-arcsec matching radius and find that 334446 confirmed quasars are covered by the full CRTS. Our final sample consists of 111 quasars. (2 data files).

Louisiana SIP: LAC 33:III Ch 21 Subchap J, 2147--Limiting Volatile Organic Compound (VOC) Emissions from Reactor Processes and Distillation Operations in Synthetic Organic Chemical manufacturing Industry (SOCMI); SIP effective 1998-02-02 (LAc74) to more..

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch 21 Subchap J, 2147--Limiting Volatile Organic Compound (VOC) Emissions from Reactor Processes and Distillation Operations in Synthetic Organic Chemical manufacturing Industry (SOCMI); SIP effective 1998-02-02 (LAc74) more...

"Phloem sap analysis of Schleichera oleosa (Lour) Oken, Butea monosperma (Lam) Taub. and Ziziphus mauritiana (Lam) and hemolymph of Kerria lacca (Kerr) using HPLC and tandem mass spectrometry".

PubMed

Vashishtha, Amit; Rathi, Brijesh; Kaushik, Sandeep; Sharma, K K; Lakhanpaul, Suman

2013-10-01

Females of lac insects especially of Kerria lacca (Kerr) secret a resin known as lac for their own protection, which has tremendous applications. Lac insect completes its lifecycle on several host taxa where it exclusively feeds on phloem sap but Schleichera oleosa (Lour.) Oken, Butea monosperma (Lam.) and Ziziphus mauritiana (Lam.) are its major hosts. Analysis of phloem sap constituents as well as hemolymph of lac insect is important because it ultimately gets converted into lac by insect intervention. Main phloem sap constituent's viz. sugars and free amino acids and hemolymph of lac insect were analyzed using HPLC and tandem mass spectrometry, respectively. The results were transformed to relative percentage of the total sugars and free amino acids analyzed in each sample for comparison among lac insect hemolymph and the phloem sap of the three different host taxa. Sucrose (58.9 ± 3.6-85.6 ± 0.9) and trehalose (62.3 ± 0.4) were the predominant sugars in phloem sap of three taxa and hemolymph of lac insect, respectively. Glutamic acid (33.1 ± 1.4-39.8 ± 1.4) was found to be main amino acid among the phloem sap of three taxa while tyrosine (61 ± 2.6) was the major amino acid in hemolymph of lac insect. The relative percentage of non-essential amino acids (60.8 %-69.9 %) was found to be more in all the three host taxa while essential amino acids (30.1 %-35.4 %) were present at a lower relative percentage. In contrast to this, the relative percentage of essential amino acids (81.9 %) was observed to be higher as compared to non-essential amino acids (17.7 %) in lac insect hemolymph. These results led to the detection of lac insect's endosymbionts. Moreover, this study revealed a clue regarding the importance of development of a synthetic diet for this insect so that a precise pathway of lac biosynthesis could be investigated for thorough understanding.

Mechanisms of allele-selective down-regulation of HLA class I in Burkitt's lymphoma.

PubMed

Imreh, M P; Zhang, Q J; de Campos-Lima, P O; Imreh, S; Krausa, P; Browning, M; Klein, G; Masucci, M G

1995-07-04

Burkitt lymphomas (BL) that arise in HLA-AII-positive individuals are characterized by selective loss/down-regulation of the HLA AII polypeptide. We have investigated the molecular basis of such down-regulation by comparing 5 pairs of BL lines and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL) derived from the normal B cells of the same individuals. The presence of apparently intact HLA AII genes was confirmed in all 5 BL/LCL pairs by polymerase chain reaction (PCR) typing and by Southern-blot hybridization with HLA A locus-specific probes. Northern-blot analysis with locus- and allele-specific probes revealed a significantly lower expression or absence of AII-specific mRNA in all 5 BL lines compared to the corresponding LCLs. Up-regulation of AII-specific mRNA was achieved by IFN alpha treatment of 2 BL lines with low HLA AII expression (BL-28 and BL-72) while the treatment had no effect in 3 BL lines (WWI-BL, WW2-BL and BL41) that did not express the endogenous gene. HLA AII expression was restored by transfection of the gene in WWI-BL whereas transfectants of BL-41 remained AII-negative. An HLA-AII-promoter-driven chloramphenicol acetyl transferase reporter gene (pAIICAT) was active in WWI-BL but not in BL-41. HLA-AII was expressed in hybrids of BL-41 with an AII-positive LCL, while expression of the endogenous HLA AII gene could not be restored by fusion of BL-41 with an AII-negative LCL, although an adequate set of transcription factors was present in the hybrid. Our results suggest that genetic defects and lack of transcription factors may contribute to the selective down-regulation of HLA AII in BL cells.

Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.

PubMed

Sutherland, K; del Río, J C

2014-04-18

A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. Copyright © 2014 Elsevier B.V. All rights reserved.

Interstitial ion homeostasis and acid-base balance are maintained in oedematous brain of mice with acute toxic liver failure.

PubMed

Obara-Michlewska, Marta; Ding, Fengfei; Popek, Mariusz; Verkhratsky, Alexei; Nedergaard, Maiken; Zielinska, Magdalena; Albrecht, Jan

2018-05-14

Acute toxic liver failure (ATLF) rapidly leads to brain oedema and neurological decline. We evaluated the ability of ATLF-affected brain to control the ionic composition and acid-base balance of the interstitial fluid. ATLF was induced in 10-12 weeks old male C57Bl mice by single intraperitoneal (i.p.) injection of 100 μg/g azoxymethane (AOM). Analyses were carried out in cerebral cortex of precomatous mice 20-24 h after AOM administration. Brain fluid status was evaluated by measuring apparent diffusion coefficient [ADC] using NMR spectroscopy, Evans Blue extravasation, and accumulation of an intracisternally-injected fluorescent tracer. Extracellular pH ([pH] e ) and ([K + ] e ) were measured in situ with ion-sensitive microelectrodes. Cerebral cortical microdialysates were subjected to photometric analysis of extracellular potassium ([K + ] e ), sodium ([Na + ] e ) and luminometric assay of extracellular lactate ([Lac] e ). Potassium transport in cerebral cortical slices was measured ex vivo as 86 Rb uptake. Cerebral cortex of AOM-treated mice presented decreased ADC supporting the view that ATLF-induced brain oedema is primarily cytotoxic in nature. In addition, increased Evans blue extravasation indicated blood brain barrier leakage, and increased fluorescent tracer accumulation suggested impaired interstitial fluid passage. However, [K + ] e , [Na + ] e , [Lac] e , [pH] e and potassium transport in brain of AOM-treated mice was not different from control mice. We conclude that in spite of cytotoxic oedema and deregulated interstitial fluid passage, brain of mice with ATLF retains the ability to maintain interstitial ion homeostasis and acid-base balance. Tentatively, uncompromised brain ion homeostasis and acid-base balance may contribute to the relatively frequent brain function recovery and spontaneous survival rate in human patients with ATLF. Copyright © 2018. Published by Elsevier Ltd.

Intestinal stem cells remain viable after prolonged tissue storage

PubMed Central

Fuller, Megan K.; Faulk, Denver M.; Sundaram, Nambirajan; Mahe, Maxime M.; Stout, Kara M.; von Furstenberg, Richard J.; Smith, Brian J.; McNaughton, Kirk K.; Shroyer, Noah F.; Helmrath, Michael A.; Henning, Susan J.

2013-01-01

Intestinal stem cells (ISCs) are responsible for renewal of the epithelium both during normal homeostasis and following injury. As such they have significant therapeutic potential. However, it is unknown whether ISCs can survive tissue storage. We hypothesized that, although the majority of epithelial cells may die, ISCs would remain viable for at least 24 h at 4°C. To explore this hypothesis, jejuni of C57Bl6/J or Lgr5-LacZ mice were removed and either processed immediately or placed in phosphate buffered saline (PBS) at 4°C. Delayed isolations of epithelia were performed after 24, 30, or 48 h storage. At the light microscope level, despite extensive apoptosis of villus epithelial cells, small intestinal crypts remained morphologically intact through 30 h and ISCs were identifiable via Lgr5-LacZ positivity. Electron microscopy showed that ISCs retain high integrity through 24 h. When assessed by flow cytometry, ISCs were more resistant to degeneration than the rest of the epithelium, including neighboring Paneth cells, with higher viability across all time points. Culture of isolated crypts showed no loss of capacity to form complex enteroids after 24 h tissue storage, with efficiencies after 7 days of culture remaining above 80%. By 30 h storage, efficiencies declined but budding capability was retained. We conclude that, with delay in isolation, ISCs remain viable and retain their proliferative capacity. In contrast, the remainder of the epithelium, including the Paneth cells, exhibits degeneration and programmed cell death. If these findings are recapitulated with human tissue, storage at 4°C may offer a valuable temporal window for harvest of crypts or ISCs for therapeutic application. PMID:23820734

Differences in lupus anticoagulant final conclusion through clotting time or Rosner index for mixing test interpretation.

PubMed

Depreter, Barbara; Devreese, Katrien M J

2016-09-01

Lupus anticoagulant (LAC) testing includes a screening, mixing and confirmation step. Although recently published guidelines on LAC testing are a useful step towards standardization, a lack of consensus remains whether to express mixing tests in clotting time (CT) or index of circulating anticoagulant (ICA). The influence of anticoagulant therapy, e.g. vitamin K antagonists (VKA) or direct oral anticoagulants (DOAC) on both methods of interpretation remains to be investigated. The objective of this study was to contribute to a simplification and standardization of the LAC three-step interpretation on the level of the mixing test. Samples from 148 consecutive patients with LAC request and prolonged screening step, and 77 samples from patients non-suspicious for LAC treated with VKA (n=37) or DOAC (n=30) were retrospectively evaluated. An activated partial thromboplastin time (aPTT) and dilute Russell's viper venom time (dRVVT) were used for routine LAC testing. The supplemental anticoagulant samples were tested with dRVVT only. We focused on the interpretation differences for mixing tests expressed as CT or ICA and compared the final LAC conclusion within each distinct group of concordant and discordant mixing test results. Mixing test interpretation by CT resulted in 10 (dRVVT) and 16 (aPTT) more LAC positive patients compared to interpretation with ICA. Isolated prolonged dRVVT screen mix ICA results were exclusively observed in samples from VKA-treated patients without suspicion for LAC. We recommend using CT in respect to the 99th percentile cut-off for interpretation of mixing steps in order to reach the highest sensitivity and specificity in LAC detection.

Lactation induces increases in the RANK/RANKL/OPG system in maxillary bone.

PubMed

Macari, Soraia; Sharma, Lavanya A; Wyatt, Amanda; da Silva, Janine Maíra; Dias, George J; Silva, Tarcília A; Szawka, Raphael E; Grattan, David R

2018-05-01

The underlying causes of maxillary bone loss during lactation remain poorly understood. We evaluated the impact of lactation on physiological and mechanically-induced alveolar bone remodeling. Nulliparous non-lactating (N-LAC) and 21-day lactating (LAC) mice underwent mechanically-induced bone remodeling by orthodontic tooth movement (OTM). Micro-computed tomography (microCT) was performed in the maxilla, femur and vertebra. Tartrate-resistant-acid phosphatase (TRAP) and Masson's trichrome labelling was performed in the maxillary bone and gene expression was determined in the periodontal ligament. The effect of prolactin on osteoclast (OCL) and osteoblast (OBL) differentiation was also investigated in N-LAC and LAC mice. Lactation increased alveolar bone loss in the maxilla, femur and vertebra, while OTM was enhanced. The number of OCL and OBL was higher in the maxilla of LAC mice. OTM increased OCL in both groups; while OBL was increased only in N-LAC but not in LAC mice, in which cell numbers were already elevated. The alveolar bone loss during lactation was associated with increased expression of receptor activator of nuclear factor-KappaB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in the maxilla. OTM induced the same responses in N-LAC mice, whereas it had no further effect in LAC mice. Lactation enhanced differentiation of OCL and OBL from bone marrow cells, and prolactin recapitulated OCL differentiation in N-LAC mice. Thus, lactation increases physiological maxillary bone remodeling and OTM, and both require activation of RANK/RANKL/OPG system. These findings expand our knowledge of lactation-induced osteopenia and have possible impact on clinical practice regarding orthodontic treatments and dental implants in lactating women. Copyright © 2018 Elsevier Inc. All rights reserved.

Identification of a Dehydrogenase Required for Lactose Metabolism in Caulobacter crescentus▿ †‡

PubMed Central

Arellano, Benjamin H.; Ortiz, Janett D.; Manzano, Janet; Chen, Joseph C.

2010-01-01

Caulobacter crescentus, which thrives in freshwater environments with low nutrient levels, serves as a model system for studying bacterial cell cycle regulation and organelle development. We examined its ability to utilize lactose (i) to gain insight into the metabolic capacities of oligotrophic bacteria and (ii) to obtain an additional genetic tool for studying this model organism, aiming to eliminate the basal enzymatic activity that hydrolyzes the chromogenic substrate 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside (X-gal). Using a previously isolated transposon mutant, we identified a gene, lacA, that is required for growth on lactose as the sole carbon source and for turning colonies blue in the presence of X-gal. LacA, which contains a glucose-methanol-choline (GMC) oxidoreductase domain, has homology to the flavin subunit of Pectobacterium cypripedii's gluconate dehydrogenase. Sequence comparisons indicated that two genes near lacA, lacB and lacC, encode the other subunits of the membrane-bound dehydrogenase. In addition to lactose, all three lac genes are involved in the catabolism of three other β-galactosides (lactulose, lactitol, and methyl-β-d-galactoside) and two glucosides (salicin and trehalose). Dehydrogenase assays confirmed that the lac gene products oxidize lactose, salicin, and trehalose. This enzymatic activity is inducible, and increased lac expression in the presence of lactose and salicin likely contributes to the induction. Expression of lacA also depends on the presence of the lac genes, implying that the dehydrogenase participates in induction. The involvement of a dehydrogenase suggests that degradation of lactose and other sugars in C. crescentus may resemble a proposed pathway in Agrobacterium tumefaciens. PMID:20190087

[Clinical Advantages and Acupoint Selection of Treatment of Chronic Functional Constipation with Acupuncture Therapy].

PubMed

Yu, Zhi; Xu, Bin

2016-08-25

Abundant clinical practice has showed that acupuncture therapy has some distinct advantages in the treatment of chronic functional constipation (CFC), such as faster positive effect, shorter course of treatment, long-term post-effect, etc. In the present paper, the authors reviewed progresses of researches in clinical treatment of CFC with acupuncture therapy in recent years. Results of clinical trials indicated that among the 3 types (slow transit, outlet obstruction and mixed type) of constipation, acupuncture therapy showed a better effect for slow transit constipation by improving severity, increasing defecation frequency, reducing abdominal distension, easing patients' psychological discomfort and raising daily life activity, probably by ameliorating colonic motility, enteric nervous system function and neurotransmitter secretion (vasoactive intestinal peptide, acetylcholine, substance P, nitrix oxide,etc.). Most of the chosen acupoints (ST 25, SP 15, SP 14, CV 6, BL 25, BL 23, etc.) are located in the projection region of colon. For outlet obstruction defecation, the effect of acupuncture is relatively better for chalasia type, in spite of generally being poorer in the efficacy. Majority of the selected acupoints (GV 1, BL 32, BL 33, BL 30, etc.)are located near the pelvic floor region. In addition, the clinical therapeutic effects of acupuncture need being confirmed by more large sample, multiple centers randomized controlled trials.

A biosensor based on Coriolopsis gallica laccase immobilized on nitrogen-doped multiwalled carbon nanotubes and graphene oxide for polyphenol detection

PubMed Central

Aguila, Sergio A; Shimomoto, David; Ipinza, Franscisco; Bedolla-Valdez, Zaira I; Romo-Herrera, José; Contreras, Oscar E; Farías, Mario H; Alonso-Núñez, Gabriel

2015-01-01

The use of nanomaterials allows the design of ultrasensitive biosensors with advantages in the detection of organic molecules. Catechol and catechin are molecules that occur naturally in fruits, and their presence in products like dyes and wines affects quality standards. In this study, catechol and catechin were measured at the nanoscale by means of cyclic voltammetry. The oxidation of Coriolopsis gallica laccase immobilized on nitrogen-doped multiwalled carbon nanotubes (Lac/CNx-MWCNT) and on graphene oxide (Lac/GO) was used to measure the concentrations of catechol and catechin. Nitrogen-doped multiwalled carbon nanotubes (CNx-MWCNT) were synthesized by spray pyrolysis and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). Covalently bonded hybrids with laccase (Lac/CNx-MWCNT and Lac/GO) were generated. Catalytic activity of free enzymes determined with syringaldazine yielded 14 584 UmL−1. With Lac/CNx-MWCNT at concentrations of 6.4 mmol L−1 activity was 9326 U mL−1, while enzyme activity measured with Lac/GO at concentration of 6.4 mmol L−1 was 9 234 U mL−1. The Lac/CNx-MWCNT hybrid showed higher stability than Lac/GO at different ethyl alcohol concentrations. The Lac/CNx-MWCNT hybrid can measure concentrations, not previously reported, as low as 1 × 10−8 mol L−1 by measuring the electric current responses. PMID:27877839

A biosensor based on Coriolopsis gallica laccase immobilized on nitrogen-doped multiwalled carbon nanotubes and graphene oxide for polyphenol detection

NASA Astrophysics Data System (ADS)

Aguila, Sergio A.; Shimomoto, David; Ipinza, Franscisco; Bedolla-Valdez, Zaira I.; Romo-Herrera, José; Contreras, Oscar E.; Farías, Mario H.; Alonso-Núñez, Gabriel

2015-10-01

The use of nanomaterials allows the design of ultrasensitive biosensors with advantages in the detection of organic molecules. Catechol and catechin are molecules that occur naturally in fruits, and their presence in products like dyes and wines affects quality standards. In this study, catechol and catechin were measured at the nanoscale by means of cyclic voltammetry. The oxidation of Coriolopsis gallica laccase immobilized on nitrogen-doped multiwalled carbon nanotubes (Lac/CNx-MWCNT) and on graphene oxide (Lac/GO) was used to measure the concentrations of catechol and catechin. Nitrogen-doped multiwalled carbon nanotubes (CNx-MWCNT) were synthesized by spray pyrolysis and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). Covalently bonded hybrids with laccase (Lac/CNx-MWCNT and Lac/GO) were generated. Catalytic activity of free enzymes determined with syringaldazine yielded 14 584 UmL-1. With Lac/CNx-MWCNT at concentrations of 6.4 mmol L-1 activity was 9326 U mL-1, while enzyme activity measured with Lac/GO at concentration of 6.4 mmol L-1 was 9 234 U mL-1. The Lac/CNx-MWCNT hybrid showed higher stability than Lac/GO at different ethyl alcohol concentrations. The Lac/CNx-MWCNT hybrid can measure concentrations, not previously reported, as low as 1 × 10-8 mol L-1 by measuring the electric current responses.

Louisiana SIP: LAC 33:III Ch. 7 Section 701. Purpose and Information Regarding Standards for PM10, SO2, CO, Atmospheric Oxidants, NOx and Pb; SIP effective 1989-05-08 (LAc49) to 2011-08-03 (LAd34 - Revised)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch. 7 Section 701. Purpose and Information Regarding Standards for PM10, SO2, CO, Atmospheric Oxidants, NOx and Pb; SIP effective 1989-05-08 (LAc49) to 2011-08-03 (LAd34 - Revised)

K88 Fimbrial Adhesin Targeting of Microspheres Containing Gentamicin Made with Albumin Glycated with Lactose.

PubMed

Sarabia-Sainz, Andre-I; Sarabia-Sainz, Hector Manuel; Montfort, Gabriela Ramos-Clamont; Mata-Haro, Veronica; Guzman-Partida, Ana María; Guzman, Roberto; Garcia-Soto, Mariano; Vazquez-Moreno, Luz

2015-09-16

The formulation and characterization of gentamicin-loaded microspheres as a delivery system targeting enterotoxigenic Escherichia coli K88 (E. coli K88) was investigated. Glycated albumin with lactose (BSA-glucose-β (4-1) galactose) was used as the microsphere matrix (MS-Lac) and gentamicin included as the transported antibiotic. The proposed target strategy was that exposed galactoses of MS-Lac could be specifically recognized by E. coli K88 adhesins, and the delivery of gentamicin would inhibit bacterial growth. Lactosylated microspheres (MS-Lac1, MS-Lac2 and MS-Lac3) were obtained using a water-in-oil emulsion, containing gentamicin, followed by crosslinking with different concentrations of glutaraldehyde. Electron microscopy displayed spherical particles with a mean size of 10-17 µm. In vitro release of gentamicin from MS-Lac was best fitted to a first order model, and the antibacterial activity of encapsulated and free gentamicin was comparable. MS-Lac treatments were recognized by plant galactose-specific lectins from Ricinus communis and Sophora japonica and by E. coli K88 adhesins. Results indicate MS-Lac1, produced with 4.2 mg/mL of crosslinker, as the best treatment and that lactosylated microsphere are promising platforms to obtain an active, targeted system against E. coli K88 infections.

K88 Fimbrial Adhesin Targeting of Microspheres Containing Gentamicin Made with Albumin Glycated with Lactose

PubMed Central

Sarabia-Sainz, Andre-i; Sarabia-Sainz, Hector Manuel; Ramos-Clamont Montfort, Gabriela; Mata-Haro, Veronica; Guzman-Partida, Ana María; Guzman, Roberto; Garcia-Soto, Mariano; Vazquez-Moreno, Luz

2015-01-01

The formulation and characterization of gentamicin-loaded microspheres as a delivery system targeting enterotoxigenic Escherichia coli K88 (E. coli K88) was investigated. Glycated albumin with lactose (BSA-glucose-β (4-1) galactose) was used as the microsphere matrix (MS-Lac) and gentamicin included as the transported antibiotic. The proposed target strategy was that exposed galactoses of MS-Lac could be specifically recognized by E. coli K88 adhesins, and the delivery of gentamicin would inhibit bacterial growth. Lactosylated microspheres (MS-Lac1, MS-Lac2 and MS-Lac3) were obtained using a water-in-oil emulsion, containing gentamicin, followed by crosslinking with different concentrations of glutaraldehyde. Electron microscopy displayed spherical particles with a mean size of 10–17 µm. In vitro release of gentamicin from MS-Lac was best fitted to a first order model, and the antibacterial activity of encapsulated and free gentamicin was comparable. MS-Lac treatments were recognized by plant galactose-specific lectins from Ricinus communis and Sophora japonica and by E. coli K88 adhesins. Results indicate MS-Lac1, produced with 4.2 mg/mL of crosslinker, as the best treatment and that lactosylated microsphere are promising platforms to obtain an active, targeted system against E. coli K88 infections. PMID:26389896

Lactosylated Gramicidin-based lipid nanoparticles (Lac-GLN) for targeted delivery of anti-miR-155 to hepatocellular carcinoma

PubMed Central

Zhang, Mengzi; Zhou, Xiaoju; Wang, Bo; Yung, Bryant C.; Lee, Ly J.; Ghoshal, Kalpana; Lee, Robert J.

2013-01-01

Lactosylated gramicidin-containing lipid nanoparticles (Lac-GLN) were developed for delivery of anti-microRNA-155 (anti-miR-155) to hepatocellular carcinoma (HCC) cells. MiR-155 is an oncomiR frequently elevated in HCC. The Lac-GLN formulation contained N-lactobionyl-dioleoyl phosphatidylethanolamine (Lac-DOPE), a ligand for the asialoglycoprotein receptor (ASGR), and an antibiotic peptide gramicidin A. The nanoparticles exhibited a mean particle diameter of 73 nm, zeta potential of +3.5 mV, anti-miR encapsulation efficiency of 88%, and excellent colloidal stability at 4°C. Lac-GLN effectively delivered anti-miR-155 to HCC cells with a 16.1- and 4.1-fold up-regulation of miR-155 targets C/EBPβ and FOXP3 genes, respectively, and exhibited significant greater efficiency over Lipofectamine 2000. In mice, intravenous injection of Lac-GLN containing Cy3-anti-miR-155 led to preferential accumulation of the anti-miR-155 in hepatocytes. Intravenous administration of 1.5 mg/kg anti-miR-155 loaded Lac-GLN resulted in up-regulation of C/EBPβ and FOXP3 by 6.9- and 2.2- fold, respectively. These results suggest potential application of Lac-GLN as a liver-specific delivery vehicle for anti-miR therapy. PMID:23567045

Predictors of public support for nutrition-focused policy, systems and environmental change strategies in Los Angeles County, 2013

PubMed Central

Robles, Brenda; Kuo, Tony

2017-01-01

Background Since 2010, federal and local agencies have invested broadly in a variety of nutrition-focused policy, systems and environmental change (PSE) initiatives in Los Angeles County (LAC). To date, little is known about whether the public supports such efforts. We address this gap in the literature by examining predictors of support for a variety of PSEs. Methods Voters residing in LAC (n=1007) were randomly selected to participate in a cross-sectional telephone survey commissioned by the LAC Department of Public Health. The survey asked questions about attitudes towards the obesity epidemic, nutrition knowledge and behaviours, public opinions about changing business practices/government policies related to nutrition, and sociodemographics. A factor analysis informed outcome variable selection (ie, type of PSEs). Multivariable regression analyses were performed to examine predictors of public support. Predictors in the regression models included (primary regressor) community economic hardship; (control variables) political affiliation, sex, age, race and income; and (independent variables) perceptions about obesity, perceived health and weight status, frequency reading nutrition labels, ease of finding healthy and unhealthy foods, and food consumption behaviours (ie, fruit and vegetables, non-diet soda, fast-food and sit-down restaurant meals). Results 3 types of PSE outcome variables were identified: promotional/incentivising, limiting/restrictive and business practices. Community economic hardship was not found to be a significant predictor of public support for any of the 3 PSE types. However, Republican party affiliation, being female and perceiving obesity as a serious health problem were. Conclusions These findings have implications for public health practice and community planning in local health jurisdictions. PMID:28087545

Predictors of public support for nutrition-focused policy, systems and environmental change strategies in Los Angeles County, 2013.

PubMed

Robles, Brenda; Kuo, Tony

2017-01-13

Since 2010, federal and local agencies have invested broadly in a variety of nutrition-focused policy, systems and environmental change (PSE) initiatives in Los Angeles County (LAC). To date, little is known about whether the public supports such efforts. We address this gap in the literature by examining predictors of support for a variety of PSEs. Voters residing in LAC (n=1007) were randomly selected to participate in a cross-sectional telephone survey commissioned by the LAC Department of Public Health. The survey asked questions about attitudes towards the obesity epidemic, nutrition knowledge and behaviours, public opinions about changing business practices/government policies related to nutrition, and sociodemographics. A factor analysis informed outcome variable selection (ie, type of PSEs). Multivariable regression analyses were performed to examine predictors of public support. Predictors in the regression models included (primary regressor) community economic hardship; (control variables) political affiliation, sex, age, race and income; and (independent variables) perceptions about obesity, perceived health and weight status, frequency reading nutrition labels, ease of finding healthy and unhealthy foods, and food consumption behaviours (ie, fruit and vegetables, non-diet soda, fast-food and sit-down restaurant meals). 3 types of PSE outcome variables were identified: promotional/incentivising, limiting/restrictive and business practices. Community economic hardship was not found to be a significant predictor of public support for any of the 3 PSE types. However, Republican party affiliation, being female and perceiving obesity as a serious health problem were. These findings have implications for public health practice and community planning in local health jurisdictions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Laccase 1 gene from Plutella xylostella (PxLac1) and its functions in humoral immune response.

PubMed

Wang, Ze-Hua; Hu, Rong-Min; Ye, Xi-Qian; Huang, Jian-Hua; Chen, Xue-Xin; Shi, Min

Laccase (EC 1.10.3.2) is a phenoloxidase found in many insect species. The Laccase 1 gene from Plutella xylostella (PxLac1) was cloned, and its expression patterns and functions were determined using qPCR and RNAi methods. The results showed that the expression levels of PxLac1 were consistently high in all larval stages, and the most abundant was in the midgut during the 4th instar stage. Moreover, the expression of PxLac1 was up-regulated in response to bacterial infection, and decreased 24 h after being parasitized by Cotesia vestalis. Further analyses indicated that the effect of parasitization on PxLac1 was induced by active C. vestalis Bracovirus (CvBV). Haemocyte-free hemolymph phenoloxidase (PO) activity was suppressed when PxLac1 was treated with RNAi. Our results provide evidence for a connection between the Laccase 1 gene and insect immunity, and revealed that parasitoid polydnavirus suppresses host PO activity via PxLac1 regulation. Copyright © 2018. Published by Elsevier Ltd.

AlloRep: A Repository of Sequence, Structural and Mutagenesis Data for the LacI/GalR Transcription Regulators.

PubMed

Sousa, Filipa L; Parente, Daniel J; Shis, David L; Hessman, Jacob A; Chazelle, Allen; Bennett, Matthew R; Teichmann, Sarah A; Swint-Kruse, Liskin

2016-02-22

Protein families evolve functional variation by accumulating point mutations at functionally important amino acid positions. Homologs in the LacI/GalR family of transcription regulators have evolved to bind diverse DNA sequences and allosteric regulatory molecules. In addition to playing key roles in bacterial metabolism, these proteins have been widely used as a model family for benchmarking structural and functional prediction algorithms. We have collected manually curated sequence alignments for >3000 sequences, in vivo phenotypic and biochemical data for >5750 LacI/GalR mutational variants, and noncovalent residue contact networks for 65 LacI/GalR homolog structures. Using this rich data resource, we compared the noncovalent residue contact networks of the LacI/GalR subfamilies to design and experimentally validate an allosteric mutant of a synthetic LacI/GalR repressor for use in biotechnology. The AlloRep database (freely available at www.AlloRep.org) is a key resource for future evolutionary studies of LacI/GalR homologs and for benchmarking computational predictions of functional change. Copyright © 2015 Elsevier Ltd. All rights reserved.

CRISPR-based screening of genomic island excision events in bacteria.

PubMed

Selle, Kurt; Klaenhammer, Todd R; Barrangou, Rodolphe

2015-06-30

Genomic analysis of Streptococcus thermophilus revealed that mobile genetic elements (MGEs) likely contributed to gene acquisition and loss during evolutionary adaptation to milk. Clustered regularly interspaced short palindromic repeats-CRISPR-associated genes (CRISPR-Cas), the adaptive immune system in bacteria, limits genetic diversity by targeting MGEs including bacteriophages, transposons, and plasmids. CRISPR-Cas systems are widespread in streptococci, suggesting that the interplay between CRISPR-Cas systems and MGEs is one of the driving forces governing genome homeostasis in this genus. To investigate the genetic outcomes resulting from CRISPR-Cas targeting of integrated MGEs, in silico prediction revealed four genomic islands without essential genes in lengths from 8 to 102 kbp, totaling 7% of the genome. In this study, the endogenous CRISPR3 type II system was programmed to target the four islands independently through plasmid-based expression of engineered CRISPR arrays. Targeting lacZ within the largest 102-kbp genomic island was lethal to wild-type cells and resulted in a reduction of up to 2.5-log in the surviving population. Genotyping of Lac(-) survivors revealed variable deletion events between the flanking insertion-sequence elements, all resulting in elimination of the Lac-encoding island. Chimeric insertion sequence footprints were observed at the deletion junctions after targeting all of the four genomic islands, suggesting a common mechanism of deletion via recombination between flanking insertion sequences. These results established that self-targeting CRISPR-Cas systems may direct significant evolution of bacterial genomes on a population level, influencing genome homeostasis and remodeling.

Brain metabolite changes in patients with type 2 diabetes and cerebral infarction using proton magnetic resonance spectroscopy.

PubMed

Zhang, Min; Sun, Xinhai; Zhang, Zhengjun; Meng, Qiang; Wang, Yuzhong; Chen, Jing; Ma, Xueqin; Geng, Houfa; Sun, Lin

2014-01-01

The aim of this study was to investigate the possible brain metabolic alterations in patients with type 2 diabetes mellitus (T2DM) and cerebral infarction (DMCI) using proton magnetic resonance spectroscopy (MRS). Thirty-four patients with T2DM and DMCI were scanned together with 33 patients with nondiabetic cerebral infarction (NDCI) on a 1.5-T MRI/MRS imager. Voxels were placed in the infarcted area and the contralateral normal area in the basal ganglia. N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, and lactate (Lac)/Cr ratios were calculated. Cerebral NAA/Cr ratios in the infarcted area were lower than those in the contralateral normal area of the NDCI group. There was a significant decrease in NAA/Cr in the infarcted area of the DMCI group as compared with the infarcted area of the NDCI group. NAA/Cr ratios in the contralateral normal area of DMCI group were lower than those of the NDCI group. Lac/Cr ratios were increased in the infarcted area of both the DMCI group and NDCI group, and Lac/Cr ratios tended to be higher in the infarcted area of the DMCI group than those of the NDCI group. Glycosylated hemoglobin (HbA1c) levels were negatively correlated with NAA/Cr ratios. The study suggested that the metabolite changes were different between DMCI patients and NDCI patients, which may provide important information in the treatment of DMCI.

On Three-dimensional Structures in Relativistic Hydrodynamic Jets

NASA Astrophysics Data System (ADS)

Hardee, Philip E.

2000-04-01

The appearance of wavelike helical structures on steady relativistic jets is studied using a normal mode analysis of the linearized fluid equations. Helical structures produced by the normal modes scale relative to the resonant (most unstable) wavelength and not with the absolute wavelength. The resonant wavelength of the normal modes can be less than the jet radius even on highly relativistic jets. High-pressure regions helically twisted around the jet beam may be confined close to the jet surface, penetrate deeply into the jet interior, or be confined to the jet interior. The high-pressure regions range from thin and ribbon-like to thick and tubelike depending on the mode and wavelength. The wave speeds can be significantly different at different wavelengths but are less than the flow speed. The highest wave speed for the jets studied has a Lorentz factor somewhat more than half that of the underlying flow speed. A maximum pressure fluctuation criterion found through comparison between theory and a set of relativistic axisymmetric jet simulations is applied to estimate the maximum amplitudes of the helical, elliptical, and triangular normal modes. Transverse velocity fluctuations for these asymmetric modes are up to twice the amplitude of those associated with the axisymmetric pinch mode. The maximum amplitude of jet distortions and the accompanying velocity fluctuations at, for example, the resonant wavelength decreases as the Lorentz factor increases. Long-wavelength helical surface mode and shorter wavelength helical first body mode generated structures should be the most significant. Emission from high-pressure regions as they twist around the jet beam can vary significantly as a result of angular variation in the flow direction associated with normal mode structures if they are viewed at about the beaming angle θ=1/γ. Variation in the Doppler boost factor can lead to brightness asymmetries by factors up to 6 as long-wavelength helical structure produced by the helical surface mode winds around the jet. Higher order surface modes and first body modes produce less variation. Angular variation in the flow direction associated with the helical mode appears consistent with precessing jet models that have been proposed to explain the variability in 3C 273 and BL Lac object AO 0235+164. In particular, cyclic angular variation in the flow direction produced by the normal modes could produce the activity seen in BL Lac object OJ 287. Jet precession provides a mechanism for triggering the helical modes on multiple length scales, e.g., the galactic superluminal GRO J1655-40.

Optical monitoring of BL Lac object S5 0716+714 and FSRQ 3C 273 from 2000 to 2014

NASA Astrophysics Data System (ADS)

Yuan, Yu-Hai; Fan, Jun-hui; Tao, Jun; Qian, Bo-Chen; Costantin, Denise; Xiao, Hu-Bing; Pei, Zhi-Yuan; Lin, Chao

2017-09-01

Context. Using the 1.56 m telescope at the Shanghai Observatory (ShAO), China, we monitored two sources, BL Lac object S5 0716+714 and flat spectrum radio quasar (FSRQ) 3C 273. For S5 0716+714, we report 4969 sets of CCD (Charge-coupled Device) photometrical optical observations (1369 for V band, 1861 for R band and 1739 for I band) in the monitoring time from Dec. 4, 2000 to Apr. 5, 2014. For 3C 273, we report 460 observations (138 for V band, 146 for R band and 176 for I band) in the monitoring time from Mar. 28, 2006 to Apr. 9, 2014. Aims: The observations provide us with a large amount of data to analyze the short-term and long-term optical variabilities. Based on the variable timescales, we can estimate the central black hole mass and the Doppler factor. An abundance of multi-band observations can help us to analyze the relations between the brightness and spectrum. Methods: We use Gaussian fitting to analyze the intra-day light curves and obtain the intra-day variability (IDV) timescales. We use the discrete correlation function (DCF) method and Jurkevich method to analyze the quasi-periodic variability. Based on the VRI observations, we use the linear fitting to analyze the relations between brightness and spectrum. Results: The two sources both show IDV properties for S5 0716+714. The timescales are in the range from 17.3 min to 4.82 h; for 3C 273, the timescale is ΔT = 35.6 min. Based on the periodic analysis methods, we find the periods PV = 24.24 ± 1.09 days, PR = 24.12 ± 0.76 days, PI = 24.82 ± 0.73 days for S5 0716+714, and P = 12.99 ± 0.72, 21.76 ± 1.45 yr for 3C 273. The two sources displayed the "bluer-when-brighter" spectral evolution properties. Conclusions: S5 0716+714 and 3C 273 are frequently studied objects. The violent optical variability and IDV may come from the jet. Gaussian fitting can be used to analyze IDVs. The relations between brightness (flux density) and spectrum are strongly influenced by the frequency. A table of the individual photometry measurements is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A43

The preventive role of levosimendan against bleomycin-induced pulmonary fibrosis in rats.

PubMed

Gürbüzel, Mehmet; Sayar, Ilyas; Cankaya, Murat; Gürbüzel, Ahmet; Demirtas, Levent; Bakirci, Eftal Murat; Capoglu, Ilyas

2016-04-01

In this study, the effects of levosimendan used in the treatment of acute congestive heart failure upon pulmonary fibrosis in rats induced with bleomycin (BL) were analyzed. A total of 33 male Sprague-Dawley type rats were categorized into five groups randomly. About 2.5U/kg BL was intratracheally administered to the rats in the BL, BL+L1, BL+L2, and BL+L3 groups, and 0.9% saline was intratracheally administered at the same rate to the control group. 0.3, 1, and 3mg/kg levosimendan was intraperitoneally administered to the BL+L1, BL+L2, and BL+L3 groups, respectively. Blood and tissue samples were taken from the rats euthanized to determine the changes in erythrocyte enzyme activities and to conduct histopathological evaluations after 14 days. With values between 0 and 3, histopathological scoring damage was assessed by the presence of inflammation and fibrosis in a semiquantitative manner. Compared with those in the C group, glutathione reductase (GR) and Catalase (CAT) enzymes decreased in the BL group; compared with that in the BL group, GR increased in the BL+L1 and BL+L3 groups, 6-phosphogluconate dehydrogenase (6PGD) increased in the BL+L3 group, and CAT increased in the BL+L2 and BL+L3 groups (p<0.05). In the histopathological evaluation, fibrosis occurred in all rats in the BL group, and tissue damage was noticed to be generally less in the BL+L1, BL+L2, and BL+L3 groups (p<0.001). The results obtained from biochemical and histopathological evaluations indicate that levosimendan had an anti-fibrotic effect without a dose-dependent response on pulmonary fibrosis. Copyright © 2015 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Inverse Optimization: A New Perspective on the Black-Litterman Model.

PubMed

Bertsimas, Dimitris; Gupta, Vishal; Paschalidis, Ioannis Ch

2012-12-11

The Black-Litterman (BL) model is a widely used asset allocation model in the financial industry. In this paper, we provide a new perspective. The key insight is to replace the statistical framework in the original approach with ideas from inverse optimization. This insight allows us to significantly expand the scope and applicability of the BL model. We provide a richer formulation that, unlike the original model, is flexible enough to incorporate investor information on volatility and market dynamics. Equally importantly, our approach allows us to move beyond the traditional mean-variance paradigm of the original model and construct "BL"-type estimators for more general notions of risk such as coherent risk measures. Computationally, we introduce and study two new "BL"-type estimators and their corresponding portfolios: a Mean Variance Inverse Optimization (MV-IO) portfolio and a Robust Mean Variance Inverse Optimization (RMV-IO) portfolio. These two approaches are motivated by ideas from arbitrage pricing theory and volatility uncertainty. Using numerical simulation and historical backtesting, we show that both methods often demonstrate a better risk-reward tradeoff than their BL counterparts and are more robust to incorrect investor views.

Sex discrimination potential of buccolingual and mesiodistal tooth dimensions.

PubMed

Acharya, Ashith B; Mainali, Sneedha

2008-07-01

Tooth crown dimensions are reasonably accurate predictors of sex and are useful adjuncts in sex assessment. This study explores the utility of buccolingual (BL) and mesiodistal (MD) measurements in sex differentiation when used independently. BL and MD measurements of 28 teeth (third molars excluded) were obtained from a group of 53 Nepalese subjects (22 women and 31 men) aged 19-28 years. Stepwise discriminant analyses were undertaken separately for both types of tooth crown variables and their accuracy in sex classification compared with one another. MD dimensions had recognizably greater accuracy (77.4-83%) in sex identification than BL measurements (62.3-64.2%)--results that are consistent with previous reports. However, the accuracy of MD variables is not high enough to warrant their exclusive use in odontometric sex assessment--higher accuracy levels have been obtained when both types of dimensions were used concurrently, implying that BL variables contribute to sex assessment to some extent. Hence, it is inferred that optimal results in dental sex assessment are obtained when both MD and BL variables are used together.

Preparation of a Ammonia-Treated Lac Dye and Structure Elucidation of Its Main Component.

PubMed

Nishizaki, Yuzo; Ishizuki, Kyoko; Akiyama, Hiroshi; Tada, Atsuko; Sugimoto, Naoki; Sato, Kyoko

2016-01-01

Lac dye and cochineal extract contain laccaic acids and carminic acid as the main pigments, respectively. Both laccaic acids and carminic acid are anthraquinone derivatives. 4-Aminocarminic acid (acid-stable carmine), an illegal colorant, has been detected in several processed foods. 4-Aminocarminic acid is obtained by heating cochineal extract (carminic acid) in ammonia solution. We attempted to prepare ammonia-treated lac dye and to identify the structures of the main pigment components. Ammonia-treated lac dye showed acid stability similar to that of 4-aminocarminic acid. The structures of the main pigments in ammonia-treated lac dye were analyzed using LC/MS. One of the main pigments was isolated and identified as 4-aminolaccaic acid C using various NMR techniques, including 2D-INADEQUATE. These results indicated that ammonia-treatment of lac dye results in the generation of 4-aminolaccaic acids.

Measuring the lactate-to-creatine ratio via 1H NMR spectroscopy can be used to noninvasively evaluate apoptosis in glioma cells after X-ray irradiation.

PubMed

Li, Hongxia; Cui, Yi; Li, Fuyan; Shi, Wenqi; Gao, Wenjing; Wang, Xiao; Zeng, Qingshi

2018-01-01

Radiotherapy is among the commonly applied treatment options for glioma, which is one of the most common types of primary brain tumor. To evaluate the effect of radiotherapy noninvasively, it is vital for oncologists to monitor the effects of X-ray irradiation on glioma cells. Preliminary research had showed that PKC-ι expression correlates with tumor cell apoptosis induced by X-ray irradiation. It is also believed that the lactate-to-creatine (Lac/Cr) ratio can be used as a biomarker to evaluate apoptosis in glioma cells after X-ray irradiation. In this study, we evaluated the relationships between the Lac/Cr ratio, apoptotic rate, and protein kinase C iota (PKC-ι) expression in glioma cells. Cells of the glioma cell lines C6 and U251 were randomly divided into 4 groups, with every group exposed to X-ray irradiation at 0, 1, 5, 10 and 15 Gy. Single cell gel electrophoresis (SCGE) was conducted to evaluate the DNA damage. Flow cytometry was performed to measure the cell cycle blockage and apoptotic rates. Western blot analysis was used to detect the phosphorylated PKC-ι (p-PKC-ι) level. 1 H NMR spectroscopy was employed to determine the Lac/Cr ratio. The DNA damage increased in a radiation dose-dependent manner ( p  < 0.05). With the increase in X-ray irradiation, the apoptotic rate also increased (C6, p  < 0.01; U251, p  < 0.05), and the p-PKC-ι level decreased (C6, p  < 0.01; U251, p  < 0.05). The p-PKC-ι level negatively correlated with apoptosis, whereas the Lac/Cr ratio positively correlated with the p-PKC-ι level. The Lac/Cr ratio decreases with an increase in X-ray irradiation and thus can be used as a biomarker to reflect the effects of X-ray irradiation in glioma cells.

Synthesis of biotinylated glycoconjugates and their use in a novel ELISA for direct comparison of HIV-1 Gp120 recognition of GalCer and related carbohydrate analogues.

PubMed

McReynolds, K D; Hadd, M J; Gervay-Hague, J

1999-01-01

As part of our program directed toward the design and synthesis of high-affinity ligands for the GalCer-binding site on the HIV cell surface glycoprotein, gp120, we required a reliable method for qualitatively assessing relative binding affinities for related analogues. Due to the hydrophilic nature of these synthetic conjugates, difficulties were encountered with typical ELISA methods, which rely upon hydrophobic interactions to anchor the ligand to a microtiter plate. Other types of assays were also problematic due to nonspecific binding of gp120. Therefore, we developed a general method for plating water-soluble ligands on microtiter plates using biotin/NeutrAvidin recognition for adhesion. A water-soluble GalCer analogue was prepared by conjugating psychosine to biotin using a novel tetraethylene glycol linker. In a similar manner, LacCer and GlcCer analogues were prepared and these conjugates were plated into microtiter wells containing NeutrAvidin. Unoccupied sites were blocked using biotin functionalized as a primary amide. Gp120 binding to galactosyl sphingosine, GalSph (19), GlcSph (22), and LacSph (23) conjugates was assessed through incubation with recombinant HRP-gp120. It was determined that LacSph has the strongest interaction with gp120. The binding affinities of GalSph and GlcSph were similar to each other and less strong than LacSph. These data contradict earlier studies where HPTLC showed that LacCer and GlcCer do not significantly bind gp120. They also contradict liposome-based assays that reported psychosine is not recognized by gp120. The extent of plating for each biotinylated molecule was quantified using HRP-biotin, allowing direct comparison of ligand plating efficiencies for the first time. Several other synthetic biotin conjugates were prepared and tested, demonstrating the feasibility of performing ELISA on water-soluble ligands.

Comparative genome analysis of Streptococcus infantarius subsp. infantarius CJ18, an African fermented camel milk isolate with adaptations to dairy environment.

PubMed

Jans, Christoph; Follador, Rainer; Hochstrasser, Mira; Lacroix, Christophe; Meile, Leo; Stevens, Marc J A

2013-03-22

Streptococcus infantarius subsp. infantarius (Sii) belongs to the Streptococcus bovis/Streptococcus equinus complex associated with several human and animal infections. Sii is a predominant bacterium in spontaneously fermented milk products in Africa. The genome sequence of Sii strain CJ18 was compared with that of other Streptococcus species to identify dairy adaptations including genome decay such as in Streptococcus thermophilus, traits for its competitiveness in spontaneous milk fermentation and to assess potential health risks for consumers. The genome of Sii CJ18 harbors several unique regions in comparison to Sii ATCC BAA-102T, among others an enlarged exo- and capsular polysaccharide operon; Streptococcus thermophilus-associated genes; a region containing metabolic and hypothetical genes mostly unique to CJ18 and the dairy isolate Streptococcus gallolyticus subsp. macedonicus; and a second oligopeptide transport operon. Dairy adaptations in CJ18 are reflected by a high percentage of pseudogenes (4.9%) representing genome decay which includes the inactivation of the lactose phosphotransferase system (lacIIABC) by multiple transposases integration. The presence of lacS and lacZ genes is the major dairy adaptation affecting lactose metabolism pathways also due to the disruption of lacIIABC.We constructed mutant strains of lacS, lacZ and lacIIABC and analyzed the resulting strains of CJ18 to confirm the redirection of lactose metabolism via LacS and LacZ.Natural competence genes are conserved in both Sii strains, but CJ18 contains a lower number of CRISPR spacers which indicates a reduced defense capability against alien DNA. No classical streptococcal virulence factors were detected in both Sii strains apart from those involved in adhesion which should be considered niche factors. Sii-specific virulence factors are not described. Several Sii-specific regions encoding uncharacterized proteins provide new leads for virulence analyses and investigation of the unclear association of dairy and clinical Sii with human diseases. The genome of the African dairy isolate Sii CJ18 clearly differs from the human isolate ATCC BAA-102T. CJ18 possesses a high natural competence predisposition likely explaining the enlarged genome. Metabolic adaptations to the dairy environment are evident and especially lactose uptake corresponds to S. thermophilus. Genome decay is not as advanced as in S. thermophilus (10-19%) possibly due to a shorter history in dairy fermentations.

Comparative genome analysis of Streptococcus infantarius subsp. infantarius CJ18, an African fermented camel milk isolate with adaptations to dairy environment

PubMed Central

2013-01-01

Background Streptococcus infantarius subsp. infantarius (Sii) belongs to the Streptococcus bovis/Streptococcus equinus complex associated with several human and animal infections. Sii is a predominant bacterium in spontaneously fermented milk products in Africa. The genome sequence of Sii strain CJ18 was compared with that of other Streptococcus species to identify dairy adaptations including genome decay such as in Streptococcus thermophilus, traits for its competitiveness in spontaneous milk fermentation and to assess potential health risks for consumers. Results The genome of Sii CJ18 harbors several unique regions in comparison to Sii ATCC BAA-102T, among others an enlarged exo- and capsular polysaccharide operon; Streptococcus thermophilus-associated genes; a region containing metabolic and hypothetical genes mostly unique to CJ18 and the dairy isolate Streptococcus gallolyticus subsp. macedonicus; and a second oligopeptide transport operon. Dairy adaptations in CJ18 are reflected by a high percentage of pseudogenes (4.9%) representing genome decay which includes the inactivation of the lactose phosphotransferase system (lacIIABC) by multiple transposases integration. The presence of lacS and lacZ genes is the major dairy adaptation affecting lactose metabolism pathways also due to the disruption of lacIIABC. We constructed mutant strains of lacS, lacZ and lacIIABC and analyzed the resulting strains of CJ18 to confirm the redirection of lactose metabolism via LacS and LacZ. Natural competence genes are conserved in both Sii strains, but CJ18 contains a lower number of CRISPR spacers which indicates a reduced defense capability against alien DNA. No classical streptococcal virulence factors were detected in both Sii strains apart from those involved in adhesion which should be considered niche factors. Sii-specific virulence factors are not described. Several Sii-specific regions encoding uncharacterized proteins provide new leads for virulence analyses and investigation of the unclear association of dairy and clinical Sii with human diseases. Conclusions The genome of the African dairy isolate Sii CJ18 clearly differs from the human isolate ATCC BAA-102T. CJ18 possesses a high natural competence predisposition likely explaining the enlarged genome. Metabolic adaptations to the dairy environment are evident and especially lactose uptake corresponds to S. thermophilus. Genome decay is not as advanced as in S. thermophilus (10-19%) possibly due to a shorter history in dairy fermentations. PMID:23521820

Louisiana SIP: LAC 33:III Ch 23 Subchap B, §2303--Aluminum Plants, §2303 Standards for Horizontal Stud Soderberg Primary Aluminum Plants and Prebake Primary Aluminum Plants; SIP effective 1989-05-08 (LAc49) to 2011-08-03 (LAad34 - Revised)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch 23 Subchap B, §2303--Aluminum Plants, §2303 Standards for Horizontal Stud Soderberg Primary Aluminum Plants and Prebake Primary Aluminum Plants; SIP effective 1989-05-08 (LAc49) to 2011-08-03 (LAad34 - Revised)

LACCASE Is Necessary and Nonredundant with PEROXIDASE for Lignin Polymerization during Vascular Development in Arabidopsis[C][W

PubMed Central

Zhao, Qiao; Nakashima, Jin; Chen, Fang; Yin, Yanbin; Fu, Chunxiang; Yun, Jianfei; Shao, Hui; Wang, Xiaoqiang; Wang, Zeng-Yu; Dixon, Richard A.

2013-01-01

The evolution of lignin biosynthesis was critical in the transition of plants from an aquatic to an upright terrestrial lifestyle. Lignin is assembled by oxidative polymerization of two major monomers, coniferyl alcohol and sinapyl alcohol. Although two recently discovered laccases, LAC4 and LAC17, have been shown to play a role in lignin polymerization in Arabidopsis thaliana, disruption of both genes only leads to a relatively small change in lignin content and only under continuous illumination. Simultaneous disruption of LAC11 along with LAC4 and LAC17 causes severe plant growth arrest, narrower root diameter, indehiscent anthers, and vascular development arrest with lack of lignification. Genome-wide transcript analysis revealed that all the putative lignin peroxidase genes are expressed at normal levels or even higher in the laccase triple mutant, suggesting that lignin laccase activity is necessary and nonredundant with peroxidase activity for monolignol polymerization during plant vascular development. Interestingly, even though lignin deposition in roots is almost completely abolished in the lac11 lac4 lac17 triple mutant, the Casparian strip, which is lignified through the activity of peroxidase, is still functional. Phylogenetic analysis revealed that lignin laccase genes have no orthologs in lower plant species, suggesting that the monolignol laccase genes diverged after the evolution of seed plants. PMID:24143805

Poly-LacNAc as an Age-Specific Ligand for Rotavirus P[11] in Neonates and Infants

PubMed Central

Liu, Yang; Huang, Pengwei; Jiang, Baoming; Tan, Ming; Morrow, Ardythe L.; Jiang, Xi

2013-01-01

Rotavirus (RV) P[11] is an unique genotype that infects neonates. The mechanism of such age-specific host restriction remains unknown. In this study, we explored host mucosal glycans as a potential age-specific factor for attachment of P[11] RVs. Using in vitro binding assays, we demonstrated that VP8* of a P[11] RV (N155) could bind saliva of infants (60.3%, N = 151) but not of adults (0%, N = 48), with a significantly negative correlation between binding of VP8* and ages of infants (P<0.01). Recognition to the infant saliva did not correlate with the ABO, secretor and Lewis histo-blood group antigens (HBGAs) but with the binding of the lectin Lycopersicon esculentum (LEA) that is known to recognize the oligomers of N-acetyllactosamine (LacNAc), a precursor of human HBGAs. Direct evidence of LacNAc involvement in P[11] binding was obtained from specific binding of VP8* with homopolymers of LacNAc in variable lengths through a glycan array analysis of 611 glycans. These results were confirmed by strong binding of VP8* to the Lec2 cell line that expresses LacNAc oligomers but not to the Lec8 cell line lacking the LacNAc. In addition, N155 VP8* and authentic P[11] RVs (human 116E and bovine B223) hemagglutinated human red blood cells that are known to express poly-LacNAc. The potential role of poly-LacNAc in host attachment and infection of RVs has been obtained by abrogation of 116E replication by the PAA-conjugated poly-LacNAc, human milk, and LEA positive infant saliva. Overall, our results suggested that the poly-LacNAc could serve as an age-specific receptor for P[11] RVs and well explained the epidemiology that P[11] RVs mainly infect neonates and young children. PMID:24244290

The evaluation of acute physiology and chronic health evaluation II score, poisoning severity score, sequential organ failure assessment score combine with lactate to assess the prognosis of the patients with acute organophosphate pesticide poisoning.

PubMed

Yuan, Shaoxin; Gao, Yusong; Ji, Wenqing; Song, Junshuai; Mei, Xue

2018-05-01

The aim of this study was to assess the ability of acute physiology and chronic health evaluation II (APACHE II) score, poisoning severity score (PSS) as well as sequential organ failure assessment (SOFA) score combining with lactate (Lac) to predict mortality in the Emergency Department (ED) patients who were poisoned with organophosphate.A retrospective review of 59 stands-compliant patients was carried out. Receiver operating characteristic (ROC) curves were constructed based on the APACHE II score, PSS, SOFA score with or without Lac, respectively, and the areas under the ROC curve (AUCs) were determined to assess predictive value. According to SOFA-Lac (a combination of SOFA and Lac) classification standard, acute organophosphate pesticide poisoning (AOPP) patients were divided into low-risk and high-risk groups. Then mortality rates were compared between risk levels.Between survivors and non-survivors, there were significant differences in the APACHE II score, PSS, SOFA score, and Lac (all P < .05). The AUCs of the APACHE II score, PSS, and SOFA score were 0.876, 0.811, and 0.837, respectively. However, after combining with Lac, the AUCs were 0.922, 0.878, and 0.956, respectively. According to SOFA-Lac, the mortality of high-risk group was significantly higher than low-risk group (P < .05) and the patients of the non-survival group were all at high risk.These data suggest the APACHE II score, PSS, SOFA score can all predict the prognosis of AOPP patients. For its simplicity and objectivity, the SOFA score is a superior predictor. Lac significantly improved the predictive abilities of the 3 scoring systems, especially for the SOFA score. The SOFA-Lac system effectively distinguished the high-risk group from the low-risk group. Therefore, the SOFA-Lac system is significantly better at predicting mortality in AOPP patients.

A diverse range of bacterial and eukaryotic chitinases hydrolyzes the LacNAc (Galβ1-4GlcNAc) and LacdiNAc (GalNAcβ1-4GlcNAc) motifs found on vertebrate and insect cells.

PubMed

Frederiksen, Rikki F; Yoshimura, Yayoi; Storgaard, Birgit G; Paspaliari, Dafni K; Petersen, Bent O; Chen, Kowa; Larsen, Tanja; Duus, Jens Ø; Ingmer, Hanne; Bovin, Nicolai V; Westerlind, Ulrika; Blixt, Ola; Palcic, Monica M; Leisner, Jørgen J

2015-02-27

There is emerging evidence that chitinases have additional functions beyond degrading environmental chitin, such as involvement in innate and acquired immune responses, tissue remodeling, fibrosis, and serving as virulence factors of bacterial pathogens. We have recently shown that both the human chitotriosidase and a chitinase from Salmonella enterica serovar Typhimurium hydrolyze LacNAc from Galβ1-4GlcNAcβ-tetramethylrhodamine (LacNAc-TMR (Galβ1-4GlcNAcβ(CH2)8CONH(CH2)2NHCO-TMR)), a fluorescently labeled model substrate for glycans found in mammals. In this study we have examined the binding affinities of the Salmonella chitinase by carbohydrate microarray screening and found that it binds to a range of compounds, including five that contain LacNAc structures. We have further examined the hydrolytic specificity of this enzyme and chitinases from Sodalis glossinidius and Polysphondylium pallidum, which are phylogenetically related to the Salmonella chitinase, as well as unrelated chitinases from Listeria monocytogenes using the fluorescently labeled substrate analogs LacdiNAc-TMR (GalNAcβ1-4GlcNAcβ-TMR), LacNAc-TMR, and LacNAcβ1-6LacNAcβ-TMR. We found that all chitinases examined hydrolyzed LacdiNAc from the TMR aglycone to various degrees, whereas they were less active toward LacNAc-TMR conjugates. LacdiNAc is found in the mammalian glycome and is a common motif in invertebrate glycans. This substrate specificity was evident for chitinases of different phylogenetic origins. Three of the chitinases also hydrolyzed the β1-6 bond in LacNAcβ1-6LacNAcβ-TMR, an activity that is of potential importance in relation to mammalian glycans. The enzymatic affinities for these mammalian-like structures suggest additional functional roles of chitinases beyond chitin hydrolysis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Prevalence of ligamentum arteriosum calcification on multi-section spiral CT and digital radiography.

PubMed

Hong, Gil-Sun; Goo, Hyun Woo; Song, Jae-Woo

2012-06-01

To investigate the prevalence of ligamentum arteriosum calcification (LAC) on multi-section spiral CT and digital radiography. Five hundred and eight children and 232 adults who performed multi-section chest CT were included in this study and were divided into nine age groups: A (0-5 years), B (6-10 years), C (11-15 years), D (16-20 years), E (21-30 years), F (31-40 years), G (41-50 years), H (51-60 years), and I (61-70 years). Two radiologists assessed the presence of LAC on axial and coronal CT images, defined as focal calcific density on both or on one plane with attenuation >100 Hounsfield unit. The prevalence of LAC on CT was compared between children and adults, and between unenhanced and enhanced CT in children. The prevalence of LAC on digital radiography was evaluated in 476 children. The prevalence of definite LAC on unenhanced multi-section CT was significantly higher in children (37.8 %) than in adults (11.2 %) (P < 0.001), with prevalences in groups: A through I of 35.8, 48.7, 35.1, 28.6, 25.0, 10.2, 15.5, 7.8, and 5.6 %, respectively. The prevalences of indeterminate LAC in age groups A-I on unenhanced multi-section CT were 4.5, 12.8, 8.1, 19.0, 0.0, 0.0, 0.0, 2.0, and 1.9 %. In children, the prevalence of LAC was significantly higher on unenhanced than on enhanced CT (37.8 vs. 16.4 %, P < 0.001). The prevalence of LAC on digital radiography was 3.6 % in children. LAC is frequently observed in children and adults on multi-section spiral CT, more frequently than previously reported. Compared with that on multi-section spiral CT, the prevalence of LAC on digital radiography is substantially low.

A portable bioluminescence engineered cell-based biosensor for on-site applications.

PubMed

Roda, Aldo; Cevenini, Luca; Michelini, Elisa; Branchini, Bruce R

2011-04-15

We have developed a portable biosensing device based on genetically engineered bioluminescent (BL) cells. Cells were immobilized on a 4 × 3 multiwell cartridge using a new biocompatible matrix that preserved their vitality. Using a fiber optic taper, the cartridge was placed in direct contact with a cooled CCD sensor to image and quantify the BL signals. Yeast and bacterial cells were engineered to express recognition elements, whose interaction with the analyte led to luciferase expression, via reporter gene technology. Three different biosensors were developed. The first detects androgenic compounds using yeast cells carrying a green-emitting P. pyralis luciferase regulated by the human androgen receptor and a red mutant of the same species as internal vitality control. The second biosensor detects two classes of compounds (androgens and estrogens) using yeast strains engineered to express green-or red-emitting mutant firefly luciferases in response to androgens or estrogens, respectively. The third biosensor detects lactose analogue isopropyl β-d-1-thiogalactopyranoside using two E. coli strains. One strain exploits the lac operon as recognition element for the expression of P. pyralis luciferase. The other strain serves as a vitality control expressing Gaussia princeps luciferase, which requires a different luciferin substrate. The immobilized cells were stable for up to 1 month. The analytes could be detected at nanomolar levels with good precision and accuracy when the specific signal was corrected using the internal vitality control. This portable device can be used for on-site multiplexed bioassays for different compound classes. Copyright © 2011 Elsevier B.V. All rights reserved.

Louisiana SIP: LAC 33:III Ch 61 Subchap A, §6121 to § 6131--Method 43 - Capture Efficiency Test Procedures; SIP effective 1994-06-06 (LAc60) to to 2011-08-03 (LAd34 - Moved to Chap 21 Subchap N §§ 2155-2160 and revised)

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch 61 Subchap A, §6121 to § 6131--Method 43 - Capture Efficiency Test Procedures; SIP effective 1994-06-06 (LAc60) to to 2011-08-03 (LAd34 - Moved to Chap 21 Subchap N §§ 2155-2160 and revised)

BIG LEAF is a regulator of organ size and adventitious root formation in poplar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yordanov, Yordan S.; Ma, Cathleen; Yordanova, Elena

Here we report the discovery through activation tagging and subsequent characterization of the BIG LEAF (BL) gene from poplar. In poplar, BL regulates leaf size via positively affecting cell proliferation. Up and downregulation of the gene led to increased and decreased leaf size, respectively, and these phenotypes corresponded to increased and decreased cell numbers. BL function encompasses the early stages of leaf development as native BL expression was specific to the shoot apical meristem and leaf primordia and was absent from the later stages of leaf development and other organs. Consistently, BL downregulation reduced leaf size at the earliest stagesmore » of leaf development. Ectopic expression in mature leaves resulted in continued growth most probably via sustained cell proliferation and thus the increased leaf size. In contrast to the positive effect on leaf growth, ectopic BL expression in stems interfered with and significantly reduced stem thickening, suggesting that BL is a highly specific activator of growth. Additionally, stem cuttings from BL overexpressing plants developed roots, whereas the wild type was difficult to root, demonstrating that BL is a positive regulator of adventitious rooting. Large transcriptomic changes in plants that overexpressed BL indicated that BL may have a broad integrative role, encompassing many genes linked to organ growth. Here, we conclude that BL plays a fundamental role in control of leaf size and thus may be a useful tool for modifying plant biomass productivity and adventitious rooting.« less

BIG LEAF is a regulator of organ size and adventitious root formation in poplar

PubMed Central

Yordanov, Yordan S.; Ma, Cathleen; Yordanova, Elena; Meilan, Richard; Strauss, Steven H.; Busov, Victor B.

2017-01-01

Here we report the discovery through activation tagging and subsequent characterization of the BIG LEAF (BL) gene from poplar. In poplar, BL regulates leaf size via positively affecting cell proliferation. Up and downregulation of the gene led to increased and decreased leaf size, respectively, and these phenotypes corresponded to increased and decreased cell numbers. BL function encompasses the early stages of leaf development as native BL expression was specific to the shoot apical meristem and leaf primordia and was absent from the later stages of leaf development and other organs. Consistently, BL downregulation reduced leaf size at the earliest stages of leaf development. Ectopic expression in mature leaves resulted in continued growth most probably via sustained cell proliferation and thus the increased leaf size. In contrast to the positive effect on leaf growth, ectopic BL expression in stems interfered with and significantly reduced stem thickening, suggesting that BL is a highly specific activator of growth. In addition, stem cuttings from BL overexpressing plants developed roots, whereas the wild type was difficult to root, demonstrating that BL is a positive regulator of adventitious rooting. Large transcriptomic changes in plants that overexpressed BL indicated that BL may have a broad integrative role, encompassing many genes linked to organ growth. We conclude that BL plays a fundamental role in control of leaf size and thus may be a useful tool for modifying plant biomass productivity and adventitious rooting. PMID:28686626

BIG LEAF is a regulator of organ size and adventitious root formation in poplar

DOE PAGES

Yordanov, Yordan S.; Ma, Cathleen; Yordanova, Elena; ...

2017-07-07

Here we report the discovery through activation tagging and subsequent characterization of the BIG LEAF (BL) gene from poplar. In poplar, BL regulates leaf size via positively affecting cell proliferation. Up and downregulation of the gene led to increased and decreased leaf size, respectively, and these phenotypes corresponded to increased and decreased cell numbers. BL function encompasses the early stages of leaf development as native BL expression was specific to the shoot apical meristem and leaf primordia and was absent from the later stages of leaf development and other organs. Consistently, BL downregulation reduced leaf size at the earliest stagesmore » of leaf development. Ectopic expression in mature leaves resulted in continued growth most probably via sustained cell proliferation and thus the increased leaf size. In contrast to the positive effect on leaf growth, ectopic BL expression in stems interfered with and significantly reduced stem thickening, suggesting that BL is a highly specific activator of growth. Additionally, stem cuttings from BL overexpressing plants developed roots, whereas the wild type was difficult to root, demonstrating that BL is a positive regulator of adventitious rooting. Large transcriptomic changes in plants that overexpressed BL indicated that BL may have a broad integrative role, encompassing many genes linked to organ growth. Here, we conclude that BL plays a fundamental role in control of leaf size and thus may be a useful tool for modifying plant biomass productivity and adventitious rooting.« less

BIG LEAF is a regulator of organ size and adventitious root formation in poplar.

PubMed

Yordanov, Yordan S; Ma, Cathleen; Yordanova, Elena; Meilan, Richard; Strauss, Steven H; Busov, Victor B

2017-01-01

Here we report the discovery through activation tagging and subsequent characterization of the BIG LEAF (BL) gene from poplar. In poplar, BL regulates leaf size via positively affecting cell proliferation. Up and downregulation of the gene led to increased and decreased leaf size, respectively, and these phenotypes corresponded to increased and decreased cell numbers. BL function encompasses the early stages of leaf development as native BL expression was specific to the shoot apical meristem and leaf primordia and was absent from the later stages of leaf development and other organs. Consistently, BL downregulation reduced leaf size at the earliest stages of leaf development. Ectopic expression in mature leaves resulted in continued growth most probably via sustained cell proliferation and thus the increased leaf size. In contrast to the positive effect on leaf growth, ectopic BL expression in stems interfered with and significantly reduced stem thickening, suggesting that BL is a highly specific activator of growth. In addition, stem cuttings from BL overexpressing plants developed roots, whereas the wild type was difficult to root, demonstrating that BL is a positive regulator of adventitious rooting. Large transcriptomic changes in plants that overexpressed BL indicated that BL may have a broad integrative role, encompassing many genes linked to organ growth. We conclude that BL plays a fundamental role in control of leaf size and thus may be a useful tool for modifying plant biomass productivity and adventitious rooting.

Major Cardiovascular Risk Factors in Latin America: A Comparison with the United States. The Latin American Consortium of Studies in Obesity (LASO)

PubMed Central

Chirinos, Julio A.; Gómez, Luis F.; Perel, Pablo; Pichardo, Rafael; González, Angel; Sánchez, José R.; Ferreccio, Catterina; Aguilera, Ximena; Silva, Eglé; Oróstegui, Myriam; Medina-Lezama, Josefina; Pérez, Cynthia M.; Suárez, Erick; Ortiz, Ana P.; Rosero, Luis; Schapochnik, Noberto; Ortiz, Zulma; Ferrante, Daniel; Casas, Juan P.

2013-01-01

Background Limited knowledge on the prevalence and distribution of risk factors impairs the planning and implementation of cardiovascular prevention programs in the Latin American and Caribbean (LAC) region. Methods and Findings Prevalence of hypertension, diabetes mellitus, abnormal lipoprotein levels, obesity, and smoking were estimated from individual-level patient data pooled from population-based surveys (1998–2007, n = 31,009) from eight LAC countries and from a national survey of the United States (US) population (1999–2004) Age and gender specific prevalence were estimated and age-gender adjusted comparisons between both populations were conducted. Prevalence of diabetes mellitus, hypertension, and low high-density lipoprotein (HDL)-cholesterol in LAC were 5% (95% confidence interval [95% CI]: 3.4, 7.9), 20.2% (95% CI: 12.5, 31), and 53.3% (95% CI: 47, 63.4), respectively. Compared to LAC region’s average, the prevalence of each risk factor tended to be lower in Peru and higher in Chile. LAC women had higher prevalence of obesity and low HDL-cholesterol than men. Obesity, hypercholesterolemia, and hypertriglyceridemia were more prevalent in the US population than in LAC population (31 vs. 16.1%, 16.8 vs. 8.9%, and 36.2 vs. 26.5%, respectively). However, the prevalence of low HDL-cholesterol was higher in LAC than in the US (53.3 vs. 33.7%). Conclusions Major cardiovascular risk factors are highly prevalent in LAC region, in particular low HDL-cholesterol. In addition, marked differences do exist in this prevalence profile between LAC and the US. The observed patterns of obesity-related risk factors and their current and future impact on the burden of cardiovascular diseases remain to be explained. PMID:23349785

Analysis of the initiation of nuclear pore assembly by ectopically targeting nucleoporins to chromatin

PubMed Central

Schwartz, Michal; Travesa, Anna; Martell, Steven W; Forbes, Douglass J

2015-01-01

Nuclear pore complexes (NPCs) form the gateway to the nucleus, mediating virtually all nucleocytoplasmic trafficking. Assembly of a nuclear pore complex requires the organization of many soluble sub-complexes into a final massive structure embedded in the nuclear envelope. By use of a LacI/LacO reporter system, we were able to assess nucleoporin (Nup) interactions, show that they occur with a high level of specificity, and identify nucleoporins sufficient for initiation of the complex process of NPC assembly in vivo. Eleven nucleoporins from different sub-complexes were fused to LacI-CFP and transfected separately into a human cell line containing a stably integrated LacO DNA array. The LacI-Nup fusion proteins, which bound to the array, were examined for their ability to recruit endogenous nucleoporins to the intranuclear LacO site. Many could recruit nucleoporins of the same sub-complex and a number could also recruit other sub-complexes. Strikingly, Nup133 and Nup107 of the Nup107/160 subcomplex and Nup153 and Nup50 of the nuclear pore basket recruited a near full complement of nucleoporins to the LacO array. Furthermore, Nup133 and Nup153 efficiently targeted the LacO array to the nuclear periphery. Our data support a hierarchical, seeded assembly pathway and identify Nup133 and Nup153 as effective “seeds” for NPC assembly. In addition, we show that this system can be applied to functional studies of individual nucleoporin domains as well as to specific nucleoporin disease mutations. We find that the R391H cardiac arrhythmia/sudden death mutation of Nup155 prevents both its subcomplex assembly and nuclear rim targeting of the LacO array. PMID:25602437

Major cardiovascular risk factors in Latin America: a comparison with the United States. The Latin American Consortium of Studies in Obesity (LASO).

PubMed

Miranda, J Jaime; Herrera, Victor M; Chirinos, Julio A; Gómez, Luis F; Perel, Pablo; Pichardo, Rafael; González, Angel; Sánchez, José R; Ferreccio, Catterina; Aguilera, Ximena; Silva, Eglé; Oróstegui, Myriam; Medina-Lezama, Josefina; Pérez, Cynthia M; Suárez, Erick; Ortiz, Ana P; Rosero, Luis; Schapochnik, Noberto; Ortiz, Zulma; Ferrante, Daniel; Casas, Juan P; Bautista, Leonelo E

2013-01-01

Limited knowledge on the prevalence and distribution of risk factors impairs the planning and implementation of cardiovascular prevention programs in the Latin American and Caribbean (LAC) region. Prevalence of hypertension, diabetes mellitus, abnormal lipoprotein levels, obesity, and smoking were estimated from individual-level patient data pooled from population-based surveys (1998-2007, n=31,009) from eight LAC countries and from a national survey of the United States (US) population (1999-2004) Age and gender specific prevalence were estimated and age-gender adjusted comparisons between both populations were conducted. Prevalence of diabetes mellitus, hypertension, and low high-density lipoprotein (HDL)-cholesterol in LAC were 5% (95% confidence interval [95% CI]: 3.4, 7.9), 20.2% (95% CI: 12.5, 31), and 53.3% (95% CI: 47, 63.4), respectively. Compared to LAC region's average, the prevalence of each risk factor tended to be lower in Peru and higher in Chile. LAC women had higher prevalence of obesity and low HDL-cholesterol than men. Obesity, hypercholesterolemia, and hypertriglyceridemia were more prevalent in the US population than in LAC population (31 vs. 16.1%, 16.8 vs. 8.9%, and 36.2 vs. 26.5%, respectively). However, the prevalence of low HDL-cholesterol was higher in LAC than in the US (53.3 vs. 33.7%). Major cardiovascular risk factors are highly prevalent in LAC region, in particular low HDL-cholesterol. In addition, marked differences do exist in this prevalence profile between LAC and the US. The observed patterns of obesity-related risk factors and their current and future impact on the burden of cardiovascular diseases remain to be explained.

Laser-Assisted Cold-Sprayed Corrosion- and Wear-Resistant Coatings: A Review

NASA Astrophysics Data System (ADS)

Olakanmi, E. O.; Doyoyo, M.

2014-06-01

Laser-assisted cold spray (LACS) process will be increasingly employed for depositing coatings because of its unique advantages: solid-state deposition of dense, homogeneous, and pore-free coatings onto a range of substrates; and high build rate at reduced operating costs without the use of expensive heating and process inert gases. Depositing coatings with excellent performance indicators via LACS demands an accurate knowledge and control of processing and materials' variables. By varying the LACS process parameters and their interactions, the functional properties of coatings can be manipulated. Moreover, thermal effect due to laser irradiation and microstructural evolution complicate the interpretation of LACS mechanical deformation mechanism which is essential for elucidating its physical phenomena. In order to provide a basis for follow-on-research that leads to the development of high-productivity LACS processing of coatings, this review focuses on the latest developments in depositing corrosion- and wear-resistant coatings with the emphasis on the composition, structure, and mechanical and functional properties. Historical developments and fundamentals of LACS are addressed in an attempt to describe the physics behind the process. Typical technological applications of LACS coatings are also identified. The investigations of all process sequences, from laser irradiation of the powder-laden gas stream and the substrate, to the impingement of thermally softened particles on the deposition site, and subsequent further processes, are described. Existing gaps in the literature relating to LACS-dependent microstructural evolution, mechanical deformation mechanisms, correlation between functional properties and process parameters, processing challenges, and industrial applications have been identified in order to provide insights for further investigations and innovation in LACS deposition of wear- and corrosion-resistant coatings.

Crystal structure of VmoLac, a tentative quorum quenching lactonase from the extremophilic crenarchaeon Vulcanisaeta moutnovskia

PubMed Central

Hiblot, Julien; Bzdrenga, Janek; Champion, Charlotte; Chabriere, Eric; Elias, Mikael

2015-01-01

A new representative of the Phosphotriesterase-Like Lactonases (PLLs) family from the hyperthermophilic crenarchaeon Vulcanisaeta moutnovskia has been characterized and crystallized. VmoLac is a native, proficient lactonase with promiscuous, low phosphotriesterase activity. VmoLac therefore represents an interesting candidate for engineering studies, with the aim of developing an efficient bacterial quorum-quenching agent. Here, we provide an extensive biochemical and kinetic characterization of VmoLac and describe the X-ray structures of the enzyme bound to a fatty acid and to its cognate substrate 3-oxo-C10 AHL (Acyl-Homoserine Lactone). The structures highlight possible structural determinants that may be involved in its extreme thermal stability (Tm = 128°C). Moreover, the structure reveals that the substrate binding mode of VmoLac significantly differs from those of its close homologues, possibly explaining the substrate specificity of the enzyme. Finally, we describe the specific interactions between the enzyme and its substrate, and discuss the possible lactone hydrolysis mechanism of VmoLac. PMID:25670483

Plasticity of laccase generated by homeologous recombination in yeast.

PubMed

Cusano, Angela M; Mekmouche, Yasmina; Meglecz, Emese; Tron, Thierry

2009-10-01

Laccase-encoding sequences sharing 65-71% identity were shuffledin vivo by homeologous recombination. Yeast efficiently repaired linearized plasmids containing clac1, clac2 or clac5 Trametes sp. C30 cDNAs using a clac3 PCR fragment. From transformants secreting active variants, three chimeric laccases (LAC131, LAC232 and LAC535), each resulting from double crossovers, were purified, and their apparent kinetic parameters were determined using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) and syringaldazine (SGZ) as substrates. At acidic pH, the apparent kinetic parameters of the chimera were not distinguishable from each other or from those obtained for the LAC3 enzyme used as reference. On the other hand, the pH tolerance of the variants was visibly extended towards alkaline pH values. Compared to the parental LAC3, a 31-fold increase in apparent k(cat) was observed for LAC131 at pH 8. This factor is one of the highest ever observed for laccase in a single mutagenesis step.

Solving a discrete model of the lac operon using Z3

NASA Astrophysics Data System (ADS)

Gutierrez, Natalia A.

2014-05-01

A discrete model for the Lcac Operon is solved using the SMT-solver Z3. Traditionally the Lac Operon is formulated in a continuous math model. This model is a system of ordinary differential equations. Here, it was considerated as a discrete model, based on a Boolean red. The biological problem of Lac Operon is enunciated as a problem of Boolean satisfiability, and it is solved using an STM-solver named Z3. Z3 is a powerful solver that allows understanding the basic dynamic of the Lac Operon in an easier and more efficient way. The multi-stability of the Lac Operon can be easily computed with Z3. The code that solves the Boolean red can be written in Python language or SMT-Lib language. Both languages were used in local version of the program as online version of Z3. For future investigations it is proposed to solve the Boolean red of Lac Operon using others SMT-solvers as cvc4, alt-ergo, mathsat and yices.

Plasma concentrations of glucagon-like peptide 1 and 2 in calves fed calf starters containing lactose.

PubMed

Inabu, Y; Saegusa, A; Inouchi, K; Koike, S; Oba, M; Sugino, T

2017-11-01

The objective of this study was to evaluate the effects of lactose inclusion in calf starters on plasma glucagon-like peptide (GLP)-1 and GLP-2 concentrations and gastrointestinal tract development in calves. Holstein bull calves (n = 45) were raised on an intensified nursing program using milk replacer containing 28.0% CP and 15.0% fat, and were fed a texturized calf starter containing 0 (control), 5.0 (LAC5), or 10.0% (LAC10; n = 15 for each treatment) lactose on a DM basis. Lactose was included in the starter by partially replacing dry ground corn in pelleted portion of the starter. All calf starters were formulated with 23.1% CP. The ethanol-soluble carbohydrate concentrations of the control, LAC5, and LAC10 starters were 7.3, 12.3, and 16.8% on a DM basis, respectively. Starch concentrations of the control, LAC5, and LAC10 starters were 29.7, 27.0, and 21.4% on a DM basis, respectively. All calves were fed treatment calf starters ad libitum. Blood samples were obtained weekly from 1 to 11 wk of age, and used to measure plasma GLP-1, GLP-2, and insulin concentrations, serum β-hydroxybutyrate (BHB) concentration, and blood glucose concentration. At 80 d of age, calves were euthanized, and weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine tissue were measured. Serum BHB concentration was higher for calves fed the LAC10 (171 μmol/L) starter than for those fed the control (151 μmol/L) and LAC5 (145 μmol/L) starters. Plasma GLP-1 and GLP-2 concentrations did not differ between treatments. However, relative to the baseline (1 wk of age), the plasma GLP-1 concentration was higher for the LAC10 (125.9%) than for the LAC5 (68.2%) and control (36.8%), and for the LAC5 than for the control (36.8%). Moreover, similar differences between treatments were observed for GLP-2 concentration relative to the baseline (88.2, 76.9, and 74.9% for LAC10, LAC5, and control treatments, respectively). The serum BHB concentration was positively correlated with the plasma GLP-1 concentration (r = 0.428). Furthermore, the plasma GLP-1 concentration was positively correlated with the insulin concentration (r = 0.793). The weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine were not affected by the treatments. In conclusion, inclusion of lactose in calf starters resulted in higher plasma GLP-1 and GLP-2 concentrations, and BHB might be associated with higher plasma GLP-1 concentration. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Laccase Down-Regulation Causes Alterations in Phenolic Metabolism and Cell Wall Structure in Poplar1

PubMed Central

Ranocha, Philippe; Chabannes, Matthieu; Chamayou, Simon; Danoun, Saïda; Jauneau, Alain; Boudet, Alain-M.; Goffner, Deborah

2002-01-01

Laccases are encoded by multigene families in plants. Previously, we reported the cloning and characterization of five divergent laccase genes from poplar (Populus trichocarpa) xylem. To investigate the role of individual laccase genes in plant development, and more particularly in lignification, three independent populations of antisense poplar plants, lac3AS, lac90AS, and lac110AS with significantly reduced levels of laccase expression were generated. A repression of laccase gene expression had no effect on overall growth and development. Moreover, neither lignin content nor composition was significantly altered as a result of laccase suppression. However, one of the transgenic populations, lac3AS, exhibited a 2- to 3-fold increase in total soluble phenolic content. As indicated by toluidine blue staining, these phenolics preferentially accumulate in xylem ray parenchyma cells. In addition, light and electron microscopic observations of lac3AS stems indicated that lac3 gene suppression led to a dramatic alteration of xylem fiber cell walls. Individual fiber cells were severely deformed, exhibiting modifications in fluorescence emission at the primary wall/middle lamella region and frequent sites of cell wall detachment. Although a direct correlation between laccase gene expression and lignification could not be assigned, we show that the gene product of lac3 is essential for normal cell wall structure and integrity in xylem fibers. lac3AS plants provide a unique opportunity to explore laccase function in plants. PMID:12011346

Troponin T3 expression in skeletal and smooth muscle is required for growth and postnatal survival: characterization of Tnnt3(tm2a(KOMP)Wtsi) mice.

PubMed

Ju, Yawen; Li, Jie; Xie, Chao; Ritchlin, Christopher T; Xing, Lianping; Hilton, Matthew J; Schwarz, Edward M

2013-09-01

The troponin complex, which consists of three regulatory proteins (troponin C, troponin I, and troponin T), is known to regulate muscle contraction in skeletal and cardiac muscle, but its role in smooth muscle remains controversial. Troponin T3 (TnnT3) is a fast skeletal muscle troponin believed to be expressed only in skeletal muscle cells. To determine the in vivo function and tissue-specific expression of Tnnt3, we obtained the heterozygous Tnnt3+/flox/lacZ mice from Knockout Mouse Project (KOMP) Repository. Tnnt3(lacZ/+) mice are smaller than their WT littermates throughout development but do not display any gross phenotypes. Tnnt3(lacZ/lacZ) embryos are smaller than heterozygotes and die shortly after birth. Histology revealed hemorrhagic tissue in Tnnt3(lacZ/lacZ) liver and kidney, which was not present in Tnnt3(lacZ/+) or WT, but no other gross tissue abnormalities. X-gal staining for Tnnt3 promoter-driven lacZ transgene expression revealed positive staining in skeletal muscle and diaphragm and smooth muscle cells located in the aorta, bladder, and bronchus. Collectively, these findings suggest that troponins are expressed in smooth muscle and are required for normal growth and breathing for postnatal survival. Moreover, future studies with this mouse model can explore TnnT3 function in adult muscle function using the conditional-inducible gene deletion approach Copyright © 2013 Wiley Periodicals, Inc.

Structural dynamics of the lac repressor-DNA complex revealed by a multiscale simulation.

PubMed

Villa, Elizabeth; Balaeff, Alexander; Schulten, Klaus

2005-05-10

A multiscale simulation of a complex between the lac repressor protein (LacI) and a 107-bp-long DNA segment is reported. The complex between the repressor and two operator DNA segments is described by all-atom molecular dynamics; the size of the simulated system comprises either 226,000 or 314,000 atoms. The DNA loop connecting the operators is modeled as a continuous elastic ribbon, described mathematically by the nonlinear Kirchhoff differential equations with boundary conditions obtained from the coordinates of the terminal base pairs of each operator. The forces stemming from the looped DNA are included in the molecular dynamics simulations; the loop structure and the forces are continuously recomputed because the protein motions during the simulations shift the operators and the presumed termini of the loop. The simulations reveal the structural dynamics of the LacI-DNA complex in unprecedented detail. The multiple domains of LacI exhibit remarkable structural stability during the simulation, moving much like rigid bodies. LacI is shown to absorb the strain from the looped DNA mainly through its mobile DNA-binding head groups. Even with large fluctuating forces applied, the head groups tilt strongly and keep their grip on the operator DNA, while the remainder of the protein retains its V-shaped structure. A simulated opening of the cleft of LacI by 500-pN forces revealed the interactions responsible for locking LacI in the V-conformation.

Synergistically enhanced stability of laccase immobilized on synthesized silver nanoparticles with water-soluble polymers.

PubMed

Cunha, M N M; Felgueiras, H P; Gouveia, I; Zille, A

2017-06-01

Silver nanoparticles (AgNPs) were synthesized by citrate reduction method in the presence of polymers, poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and chitosan, used as stabilizing agents, and an oxidoreductase enzyme, laccase (Lac), with the goal of expanding the NPs antimicrobial action. AgNPs were characterized by UV-vis spectrometry, dynamic light scattering and transmission electron microscopy. As protecting agents, PEG and PVA promoted the formation of spherical uniformly-shaped, small-sized, monodispersed AgNPs (≈20nm). High Mw polymers were established as most effective in producing small-sized NPs. Chitosan's viscosity led to the formation of aggregates. Despite the decrease in Lac activity registered for the hybrid formulation, AgNPs-polymer-Lac, a significant augment in stability over time (up to 13days, at 50°C) was observed. This novel formulation displays improved synergistic performance over AgNPs-Lac or polymer-Lac conjugates, since in the former the Lac activity becomes residual at the end of 3days. By enabling many ionic interactions, chitosan restricted the mass transfer between Lac and substrate and, thus, inhibited the enzymatic activity. These hybrid nanocomposites made up of inorganic NPs, organic polymers and immobilized antimicrobial oxidoreductive enzymes represent a new class of materials with improved synergistic performance. Moreover, the Lac and the AgNPs different antimicrobial action, both in time and mechanism, may also constitute a new alternative to reduce the probability of developing resistance-associated mutations. Copyright © 2017 Elsevier B.V. All rights reserved.

32 CFR 154.8 - Types and scope of personnel security investigations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... interview, NAC, LACs, credit checks, developed character references (3), employment records checks... interview. While the kind of coverage provided for by the SBI determines eligibility for access to SCI, DoD... requiring resolution in the case concerned and generally consist of record checks and/or interviews with...

32 CFR 154.8 - Types and scope of personnel security investigations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... interview, NAC, LACs, credit checks, developed character references (3), employment records checks... interview. While the kind of coverage provided for by the SBI determines eligibility for access to SCI, DoD... requiring resolution in the case concerned and generally consist of record checks and/or interviews with...

Clinical Chemistry Reference Intervals for C57BL/6J, C57BL/6N, and C3HeB/FeJ Mice (Mus musculus)

PubMed Central

Otto, Gordon P; Rathkolb, Birgit; Oestereicher, Manuela A; Lengger, Christoph J; Moerth, Corinna; Micklich, Kateryna; Fuchs, Helmut; Gailus-Durner, Valérie; Wolf, Eckhard; de Angelis, Martin Hrabě

2016-01-01

Although various mouse inbred strains are widely used to investigate disease mechanisms and to establish new therapeutic strategies, sex-specific reference intervals for laboratory diagnostic analytes that are generated from large numbers of animals have been unavailable. In this retrospective study, we screened data from more than 12,000 mice phenotyped in the German Mouse Clinic from January 2006 through June 2014 and selected animals with the genetic background of C57BL/6J, C57BL/6N, or C3HeB/FeJ. In addition, we distinguished between the C57BL/6NTac substrain and C57BL/6N mice received from other vendors. The corresponding data sets of electrolytes (sodium, potassium, calcium, chloride, inorganic phosphate), lipids (cholesterol, triglyceride), and enzyme activities (ALT, AST, ALP, α-amylase) and urea, albumin, and total protein levels were analyzed. Significant effects of age and sex on these analytes were identified, and strain- or substrain- and sex-specific reference intervals for 90- to 135-d-old mice were calculated. In addition, we include an overview of the literature that reports clinical chemistry values for wild-type mice of different strains. Our results support researchers interpreting clinical chemistry values from various mouse mutants and corresponding wild-type controls based on the examined strains and substrains. PMID:27423143

Clinical Chemistry Reference Intervals for C57BL/6J, C57BL/6N, and C3HeB/FeJ Mice (Mus musculus).

PubMed

Otto, Gordon P; Rathkolb, Birgit; Oestereicher, Manuela A; Lengger, Christoph J; Moerth, Corinna; Micklich, Kateryna; Fuchs, Helmut; Gailus-Durner, Valérie; Wolf, Eckhard; Hrabě de Angelis, Martin

2016-01-01

Although various mouse inbred strains are widely used to investigate disease mechanisms and to establish new therapeutic strategies, sex-specific reference intervals for laboratory diagnostic analytes that are generated from large numbers of animals have been unavailable. In this retrospective study, we screened data from more than 12,000 mice phenotyped in the German Mouse Clinic from January 2006 through June 2014 and selected animals with the genetic background of C57BL/6J, C57BL/6N, or C3HeB/FeJ. In addition, we distinguished between the C57BL/6NTac substrain and C57BL/6N mice received from other vendors. The corresponding data sets of electrolytes (sodium, potassium, calcium, chloride, inorganic phosphate), lipids (cholesterol, triglyceride), and enzyme activities (ALT, AST, ALP, α-amylase) and urea, albumin, and total protein levels were analyzed. Significant effects of age and sex on these analytes were identified, and strain- or substrain- and sex-specific reference intervals for 90- to 135-d-old mice were calculated. In addition, we include an overview of the literature that reports clinical chemistry values for wild-type mice of different strains. Our results support researchers interpreting clinical chemistry values from various mouse mutants and corresponding wild-type controls based on the examined strains and substrains.

Investigation of drug-excipient compatibility using rheological and thermal tools

NASA Astrophysics Data System (ADS)

Trivedi, Maitri R.

HYPOTHESIS: We plan to investigate a different approach to evaluate drug-excipient physical compatibility using rheological and thermal tools as opposed to commonly used chemical techniques in pharmaceutical industry. This approach offers practical solutions to routinely associated problems arising with API's and commonly used hydrates forms of excipients. ABSTRACT: Drug-Excipient compatibility studies are an important aspect of pre-formulation and formulation development in pharmaceutical research and development. Various approaches have been used in pharmaceutical industry including use of thermal analysis and quantitative assessment of drug-excipient mixtures after keeping the samples under stress environment depending upon the type of formulation. In an attempt to provide better understanding of such compatibility aspect of excipients with different properties of API, various rheological and thermal studies were conducted on binary mixtures of excipients which exist in different hydrates. Dibasic Calcium Phosphate (DCP, anhydrous and dihydrate forms) and Lactose (Lac, anhydrous and monohydrate) were selected with cohesive API's (Acetaminophen and Aspirin). Binary mixtures of DCP and Lac were prepared by addition of 0% w/w to 50% w/w of the API into each powder blend. Rheological and thermal aspects were considered using different approaches such as powder rheometer, rotational shear cell and traditional rheometery approaches like angle of repose (AOR), hausner's ratio (HR) and cares index (CI). Thermal analysis was conducted using modulated differential scanning calorimetry (MDSC) and thermal effusivity. The data suggested that the powder rheometer showed distinctive understanding in the flowability behavior of binary mixtures with addition of increasing proportion of API's than traditional approaches. Thermal approaches revealed the potential interaction of water of crystallization DCP-D with the API (APAP) while such interactions were absent in DCP-A, while in case of Lac-M and Lac-A, interaction with water of crystallization were not present. Binary mixtures prepared with DCP-D were better flowable while blends with DCP-A were better in stability (physical), compressibility and permeability. Similarly binary mixtures prepared with Lac-M were better flowable and stable in physical compatibility as compared to Lac-A. Lac-A were better in compressibility and permeability. Second part of these research included understanding the powder behavior from wet granulation point of view. Wet granulation includes the formation of agglomerates with powders to form granules in order to have better flowability, content uniformity and compressibility of granular mass. End point determination of powders involving change in powder energies and compressibility, permeability along with thermal analyses were conducted. The effects of water of crystallization on end point determination was studied and based on which overall effects on drug-excipient compatibility using different hydrate forms of excipients were evaluated.

Latin America: A Development Pole for Phenomics

PubMed Central

Camargo, Anyela V.; Lobos, Gustavo A.

2016-01-01

Latin America and the Caribbean (LAC) has long been associated with the production and export of a diverse range of agricultural commodities. Due to its strategic geographic location, which encompasses a wide range of climates, it is possible to produce almost any crop. The climate diversity in LAC is a major factor in its agricultural potential but this also means climate change represents a real threat to the region. Therefore, LAC farming must prepare and quickly adapt to an environment that is likely to feature long periods of drought, excessive rainfall and extreme temperatures. With the aim of moving toward a more resilient agriculture, LAC scientists have created the Latin American Plant Phenomics Network (LatPPN) which focuses on LAC's economically important crops. LatPPN's key strategies to achieve its main goal are: (1) training of LAC members on plant phenomics and phenotyping, (2) establish international and multidisciplinary collaborations, (3) develop standards for data exchange and research protocols, (4) share equipment and infrastructure, (5) disseminate data and research results, (6) identify funding opportunities and (7) develop strategies to guarantee LatPPN's relevance and sustainability across time. Despite the challenges ahead, LatPPN represents a big step forward toward the consolidation of a common mind-set in the field of plant phenotyping and phenomics in LAC. PMID:27999577

Latin America: A Development Pole for Phenomics.

PubMed

Camargo, Anyela V; Lobos, Gustavo A

2016-01-01

Latin America and the Caribbean (LAC) has long been associated with the production and export of a diverse range of agricultural commodities. Due to its strategic geographic location, which encompasses a wide range of climates, it is possible to produce almost any crop. The climate diversity in LAC is a major factor in its agricultural potential but this also means climate change represents a real threat to the region. Therefore, LAC farming must prepare and quickly adapt to an environment that is likely to feature long periods of drought, excessive rainfall and extreme temperatures. With the aim of moving toward a more resilient agriculture, LAC scientists have created the Latin American Plant Phenomics Network (LatPPN) which focuses on LAC's economically important crops. LatPPN's key strategies to achieve its main goal are: (1) training of LAC members on plant phenomics and phenotyping, (2) establish international and multidisciplinary collaborations, (3) develop standards for data exchange and research protocols, (4) share equipment and infrastructure, (5) disseminate data and research results, (6) identify funding opportunities and (7) develop strategies to guarantee LatPPN's relevance and sustainability across time. Despite the challenges ahead, LatPPN represents a big step forward toward the consolidation of a common mind-set in the field of plant phenotyping and phenomics in LAC.

Population Dynamics of a Lac(-) Strain of Escherichia Coli during Selection for Lactose Utilization

PubMed Central

Foster, P. L.

1994-01-01

During selection for lactose utilization, Lac(+) revertants of FC40, a Lac(-) strain of Escherichia coli, appear at a high rate. Yet, no Lac(+) revertants appear in the absence of lactose, or in its presence if the cells have another, unfulfilled requirement for growth. This study investigates more fully the population dynamics of FC40 when incubated in the absence of a carbon source or when undergoing selection for lactose utilization. In the absence of a carbon source, the viable cell numbers do not change over 6 days. When incubated in liquid lactose medium, Lac(-) cells do not undergo any measurable increase in numbers or in turbidity for at least 2 days. When FC40 is plated on lactose minimum medium in the presence of scavenger cells, the upper limit to the amount of growth of Lac(-) cells during 5 days is one doubling, and there is no evidence for turnover (i.e., a balance between growth and death). The presence of a minority population that could form microcolonies was not detected. The implications of these results, plus the fact that the appearance of Lac(+) revertants during lactose selection is nearly constant with time, are discussed in reference to several models that have been postulated to account for adaptive mutations. PMID:7828809

Unraveling the nexus between water and food security in Latin America and the Caribbean: regional and global implications

NASA Astrophysics Data System (ADS)

Willaarts, Barbara; Garrido, Alberto; Soriano, Barbara; De Stefano, Lucia; López Gunn, Elena; Aldaya, Maite; Martínez-Santos, Pedro; Llamas, Ramon

2014-05-01

Latin American and the Caribbean (LAC) is a water and land abundant region, and plays a key role in meeting global food and water security. During the last decade, LAC has experience a rapid socio-economic growth, largely sustained by its competitive advantage in the production and exports of agricultural and mining products and by the high commodity prices in the global market. This study seeks to quantify the contribution of LAC's agriculture to global food and water security, i.e. virtual water trade, and evaluate the environmental and societal implications for regional development. Results show that between 2000 and 2011, LAC has increase its agricultural production 27%, and it now accounts for nearly 18% of the global agricultural market. As a result, the agricultural water footprint (WF) of LAC was augmented 65%; and yet, nearly 19% to 44% of the actual agricultural WF - depending on the countries - is virtual water exported to third countries. In fact, almost 50% of the increase in global virtual water trade during the last decade, corresponds to LAC. Such global contribution has significant implications for regional water and food security. From an environmental perspective, crop expansion (mostly rain-fed) resulted in the deforestation of nearly 1 million km2, turning this region into the second most important deforestation hotspots worldwide. This land clearing is having large impacts of ecosystem services, e.g. carbon sequestration, water quality or biodiversity conservation. From a socio-economic perspective, increasing agricultural production has improved regional food security indicators, although one every seven children is still stunted in LAC and nearly 10% of the population remains undernourished. Dietary shifts and socio-cultural factors also lag behind the growing problem of malnutrition in the region, i.e. overweight and obesity. Improvements of water access and sanitation, have had a positive impact on food security indicators, especially among the high-income LAC countries. We conclude that despite the large contribution of LAC's agriculture to global water and food security, this goal is at present intensively tapping into LAC's natural capital. Also, regional improvements in water security have improved, but important goals remain and new challenges are emerging. Water governance in LAC is evolving to address the challenges posed by rapid socio-economic changes, however, as is often the case, the implementation of reforms lags behind.

Ephrin-B2 Reverse Signaling Is Required for Topography but Not Pattern Formation of Lateral Superior Olivary Inputs to the Inferior Colliculus

PubMed Central

Wallace, Matthew M.; Kavianpour, Sarah M.; Gabriele, Mark L.

2014-01-01

Graded and modular expressions of Eph-ephrins are known to provide positional information for the formation of topographic maps and patterning in the developing nervous system. Previously we have shown that ephrin-B2 is expressed in a continuous gradient across the tonotopic axis of the central nucleus of the inferior colliculus (CNIC), whereas patterns are discontinuous and modular in the lateral cortex of the IC (LCIC). The present study explores the involvement of ephrin-B2 signaling in the development of projections to the CNIC and LCIC arising from the lateral superior olivary nuclei (LSO) prior to hearing onset. Anterograde and retrograde fluorescent tracing methods in neonatal fixed tissue preparations were used to compare topographic mapping and the establishment of LSO layers/modules in wild-type and ephrin-B2lacZ/+ mice (severely compromised reverse signaling). At birth, pioneer LSO axons occupy the ipsilateral IC in both groups but are delayed contralaterally in ephrin-B2lacZ/+ mutants. By the onset of hearing, both wild-type and mutant projections form discernible layers bilaterally in the CNIC and modular arrangements within the ipsilateral LCIC. In contrast, ephrin-B2lacZ/+ mice lack a reliable topography in LSO-IC projections, suggesting that fully functional ephrin-B2 reverse signaling is required for normal projection mapping. Taken together, these ephrin-B2 findings paired with known coexpression of EphA4 suggest the importance of these signaling proteins in establishing functional auditory circuits prior to experience. PMID:23042409

Ephrin-B2 reverse signaling is required for topography but not pattern formation of lateral superior olivary inputs to the inferior colliculus.

PubMed

Wallace, Matthew M; Kavianpour, Sarah M; Gabriele, Mark L

2013-05-01

Graded and modular expressions of Eph-ephrins are known to provide positional information for the formation of topographic maps and patterning in the developing nervous system. Previously we have shown that ephrin-B2 is expressed in a continuous gradient across the tonotopic axis of the central nucleus of the inferior colliculus (CNIC), whereas patterns are discontinuous and modular in the lateral cortex of the IC (LCIC). The present study explores the involvement of ephrin-B2 signaling in the development of projections to the CNIC and LCIC arising from the lateral superior olivary nuclei (LSO) prior to hearing onset. Anterograde and retrograde fluorescent tracing methods in neonatal fixed tissue preparations were used to compare topographic mapping and the establishment of LSO layers/modules in wild-type and ephrin-B2(lacZ/+) mice (severely compromised reverse signaling). At birth, pioneer LSO axons occupy the ipsilateral IC in both groups but are delayed contralaterally in ephrin-B2(lacZ/+) mutants. By the onset of hearing, both wild-type and mutant projections form discernible layers bilaterally in the CNIC and modular arrangements within the ipsilateral LCIC. In contrast, ephrin-B2(lacZ/+) mice lack a reliable topography in LSO-IC projections, suggesting that fully functional ephrin-B2 reverse signaling is required for normal projection mapping. Taken together, these ephrin-B2 findings paired with known coexpression of EphA4 suggest the importance of these signaling proteins in establishing functional auditory circuits prior to experience. Copyright © 2012 Wiley Periodicals, Inc.

Eye drop delivery of nano-polymeric micelle formulated genes with cornea-specific promoters.

PubMed

Tong, Yaw-Chong; Chang, Shwu-Fen; Liu, Chia-Yang; Kao, Winston W-Y; Huang, Chong Heng; Liaw, Jiahorng

2007-11-01

This study evaluates the eye drop delivery of genes with cornea-specific promoters, i.e., keratin 12 (K12) and keratocan (Kera3.2) promoters, by non-ionic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) polymeric micelles (PM) to mouse and rabbit eyes, and investigates the underlying mechanisms. Three PM-formulated plasmids (pCMV-Lac Z, pK12-Lac Z and pKera3.2-Lac Z) containing the Lac Z gene for beta-galactosidase (beta-Gal) whose expression was driven by the promoter of either the cytomegalovirus early gene, the keratin 12 gene or the keratocan gene, were characterized by critical micelle concentration (CMC), dynamic light scattering (DLS), and atomic force microscopy (AFM). Transgene expression in ocular tissue after gene delivery was analyzed by 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-Gal) color staining, 1,2-dioxetane beta-Gal enzymatic activity measurement, and real-time polymerase chain reaction (PCR) analysis. The delivery mechanisms of plasmid-PM on mouse and rabbit corneas were evaluated by EDTA and RGD (arginine-glycine-aspartic acid) peptide. The sizes of the three plasmid-PM complexes were around 150-200 nm with unimodal distribution. Enhanced stability was found for three plasmid-PM formulations after DNase I treatment. After six doses of eye drop delivery of pK12-Lac Z-PM three times a day, beta-Gal activity was significantly increased in both mouse and rabbit corneas. Stroma-specific Lac Z expression was only found in pKera3.2-Lac Z-PM-treated animals with pretreatment by 5 mM EDTA, an opener of junctions. Lac Z gene expression in both pK12-Lac Z-PM and pKera3.2-Lac Z-PM delivery groups was decreased by RGD peptide pretreatment. Cornea epithelium- and stroma-specific gene expression could be achieved using cornea-specific promoters of keratin 12 and keratocan genes, and the gene was delivered with PM formulation through non-invasive, eye drop in mice and rabbits. The transfection mechanism of plasmid-PM may involve endocytosis and particle size dependent paracellular transport. 2007 John Wiley & Sons, Ltd

Polymeric bionanocomposite cast thin films with in situ laccase-catalyzed polymerization of dopamine for biosensing and biofuel cell applications.

PubMed

Tan, Yueming; Deng, Wenfang; Li, Yunyong; Huang, Zhao; Meng, Yue; Xie, Qingji; Ma, Ming; Yao, Shouzhuo

2010-04-22

We report here on the facile preparation of polymer-enzyme-multiwalled carbon nanotubes (MWCNTs) cast films accompanying in situ laccase (Lac)-catalyzed polymerization for electrochemical biosensing and biofuel cell applications. Lac-catalyzed polymerization of dopamine (DA) as a new substrate was examined in detail by UV-vis spectroscopy, cyclic voltammetry, quartz crystal microbalance, and scanning electron microscopy. Casting the aqueous mixture of DA, Lac and MWCNTs on a glassy carbon electrode (GCE) yielded a robust polydopamine (PDA)-Lac-MWCNTs/GCE that can sense hydroquinone with 643 microA mM(-1) cm(-2) sensitivity and 20-nM detection limit (S/N = 3). The DA substrate yielded the best biosensing performance, as compared with aniline, o-phenylenediamine, or o-aminophenol as the substrate for similar Lac-catalyzed polymerization. Casting the aqueous mixture of DA, glucose oxidase (GOx), Lac, and MWCNTs on a Pt electrode yielded a robust PDA-GOx-Lac-MWCNTs/Pt electrode that exhibits glucose-detection sensitivity of 68.6 microA mM(-1) cm(-2). In addition, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) was also coimmobilized to yield a PDA-Lac-MWCNTs-ABTS/GCE that can effectively catalyze the reduction of O(2), and it was successfully used as the biocathode of a membraneless glucose/O(2) biofuel cell (BFC) in pH 5.0 Britton-Robinson buffer. The proposed biomacromolecule-immobilization platform based on enzyme-catalyzed polymerization may be useful for preparing many other multifunctional polymeric bionanocomposites for wide applications.

Aflatoxin B₁ and M₁ Degradation by Lac2 from Pleurotus pulmonarius and Redox Mediators.

PubMed

Loi, Martina; Fanelli, Francesca; Zucca, Paolo; Liuzzi, Vania C; Quintieri, Laura; Cimmarusti, Maria T; Monaci, Linda; Haidukowski, Miriam; Logrieco, Antonio F; Sanjust, Enrico; Mulè, Giuseppina

2016-08-23

Laccases (LCs) are multicopper oxidases that find application as versatile biocatalysts for the green bioremediation of environmental pollutants and xenobiotics. In this study we elucidate the degrading activity of Lac2 pure enzyme form Pleurotus pulmonarius towards aflatoxin B₁ (AFB₁) and M₁ (AFM₁). LC enzyme was purified using three chromatographic steps and identified as Lac2 through zymogram and LC-MS/MS. The degradation assays were performed in vitro at 25 °C for 72 h in buffer solution. AFB₁ degradation by Lac2 direct oxidation was 23%. Toxin degradation was also investigated in the presence of three redox mediators, (2,2'-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]) (ABTS) and two naturally-occurring phenols, acetosyringone (AS) and syringaldehyde (SA). The direct effect of the enzyme and the mediated action of Lac2 with redox mediators univocally proved the correlation between Lac2 activity and aflatoxins degradation. The degradation of AFB₁ was enhanced by the addition of all mediators at 10 mM, with AS being the most effective (90% of degradation). AFM₁ was completely degraded by Lac2 with all mediators at 10 mM. The novelty of this study relies on the identification of a pure enzyme as capable of degrading AFB₁ and, for the first time, AFM₁, and on the evidence that the mechanism of an effective degradation occurs via the mediation of natural phenolic compounds. These results opened new perspective for Lac2 application in the food and feed supply chains as a biotransforming agent of AFB₁ and AFM₁.

Lupus anticoagulant: a multicenter study for a standardized and harmonized reporting.

PubMed

Poz, Alessandra; Pradella, Paola; Azzarini, Gabriella; Santarossa, Liliana; Bardin, Cristina; Zardo, Lorena; Giacomello, Roberta

2016-03-01

Laboratory assessment of Lupus anticoagulant (LAC) is very challenging because of inter and intralaboratory variability, which makes it difficult to standardize and harmonize results expression. Five hospital laboratories in North-eastern Italy shared their efforts and their experience in a cross-laboratory study, conducting the diagnostic process as homogeneously as possible and providing a better interpretation for LAC positivity. Hundred normal samples from healthy subjects (20 from each center) were processed to confirm negative upper limits and calculate positivity cutoffs of LAC integrated assays, that is dilute Russell's viper venom time (dRVVT) and silica clotting time (SCT). Moreover, 311 samples previously diagnosed by the laboratories as positive for LAC were analyzed to characterize different positivity levels for each assay. As far as the analysis of healthy subjects is concerned, negative upper limits are set at 1.17 and 1.19 for dRVVT and SCT screen ratio, respectively. Positivity cutoffs are set at 1.20 for dRVVT and 1.23 for SCT, expressed as Test Ratio calculated on screen and confirm integrated tests. Positive results for each integrated assay are subsequently divided into three subgroups: weak, moderate and strong; the results obtained are presented as a score proposal that can provide LAC interpretation. The combined use of both dRVVT and SCT assays and the definition of different positivity levels may lead to clearer, more objective LAC reporting. An interpretative table for LAC-proposed score provides LAC-positive results and it is now adopted by all centers involved in the study.

Microbial keratitis in los angeles: the doheny eye institute and the los angeles county hospital experience.

PubMed

Sand, Daniel; She, Rosemary; Shulman, Ira A; Chen, David S; Schur, Mathew; Hsu, Hugo Y

2015-05-01

To evaluate the spectrum and antibiotic susceptibility panel of infectious keratitis at a major tertiary care referral eye center and a major county hospital in Southern California. Retrospective case series. All cultured infectious keratitis cases from July 1, 2008, through December 31, 2012, from the Doheny Eye Institute (DEI) and the Los Angeles County + University of Southern California Medical Center (LAC+USC) were evaluated. Microbiology records were reviewed retrospectively. Microbial isolates as well as antibiotic susceptibility patterns were analyzed. One hundred eighty-four (63%) of 290 cases showed positive culture results at DEI and 152 (82%) of 186 cases showed positive culture results at LAC+USC. Gram-positive pathogens were found to be the most common at both DEI (70%) and LAC+USC (68%), with coagulase-negative Staphylococcus being the most common gram-positive organism (58% at DEI and 44% at LAC+USC). Pseudomonas aeruginosa was the most common gram-negative organism (57% at DEI and 43% at LAC+USC). Ciprofloxacin and levofloxacin susceptibility for all tested pathogens was 73% at DEI and 81% at LAC+USC (P = 0.16). Oxacillin-resistant Staphylococcus aureus (ORSA) was found in 42% of cases at DEI and in 45% of cases at LAC+USC (P = 1.00). There is no significant difference in the spectrum of pathogens or antibiotic susceptibility of pathogens at DEI versus LAC+USC, and ORSA was found in approximately half of all S. aureus samples. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Indian Americans at Mille Lacs.

ERIC Educational Resources Information Center

Holbert, Victoria L.; And Others

The Training Center for Community Programs prepared a report on the Mille Lacs (Chippewa) Reservation in Minnesota. Data for the report were from 2 separate sources: a survey conducted by the Training Center with the assistance of the Mille Lacs community action program (1967) and an attitudinal survey conducted by Victoria Holbert during 1969.…

Program Evaluation of Community College Learning Assistance Centers: What Do LAC Directors Think?

ERIC Educational Resources Information Center

Franklin, Doug; Blankenberger, Bob

2016-01-01

Objective: This study seeks to determine the nature of current program evaluation practices for learning assistance centers (LACs), the practices being used for program evaluation, and whether LAC directors believe their practices are appropriate for evaluating program effectiveness. Method: We conducted a survey (n = 61) of community college LAC…

Lactose-induced cell death of beta-galactosidase mutants in Kluyveromyces lactis.

PubMed

Lodi, Tiziana; Donnini, Claudia

2005-05-01

The Kluyveromyces lactis lac4 mutants, lacking the beta-galactosidase gene, cannot assimilate lactose, but grow normally on many other carbon sources. However, when these carbon sources and lactose were simultaneously present in the growth media, the mutants were unable to grow. The effect of lactose was cytotoxic since the addition of lactose to an exponentially-growing culture resulted in 90% loss of viability of the lac4 cells. An osmotic stabilizing agent prevented cells killing, supporting the hypothesis that the lactose toxicity could be mainly due to intracellular osmotic pressure. Deletion of the lactose permease gene, LAC12, abolished the inhibitory effect of lactose and allowed the cell to assimilate other carbon substrates. The lac4 strains gave rise, with unusually high frequency, to spontaneous mutants tolerant to lactose (lar1 mutation: lactose resistant). These mutants were unable to take up lactose. Indeed, lar1 mutation turned out to be allelic to LAC12. The high mutability of the LAC12 locus may be an advantage for survival of K. lactis whose main habitat is lactose-containing niches.

Spectroscopy and formation of lanthanum-hydrocarbon radicals formed by association and carbon-carbon bond cleavage of isoprene

NASA Astrophysics Data System (ADS)

Cao, Wenjin; Hewage, Dilrukshi; Yang, Dong-Sheng

2018-05-01

La atom reaction with isoprene is carried out in a laser-vaporization molecular beam source. The reaction yields an adduct as the major product and C—C cleaved and dehydrogenated species as the minor ones. La(C5H8), La(C2H2), and La(C3H4) are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of all three species exhibit a strong origin band and several weak vibronic bands corresponding to La-ligand stretch and ligand-based bend excitations. La(C5H8) is a five-membered metallacycle, whereas La(C2H2) and La(C3H4) are three-membered rings. All three metallacycles prefer a doublet ground state with a La 6s1-based valence electron configuration and a singlet ion. The five-membered metallacycle is formed through La addition and isoprene isomerization, whereas the two three-membered rings are produced by La addition and insertion, hydrogen migration, and carbon-carbon bond cleavage.