Extended radio emission in BL Lac objects - I: the images

We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope (WSRT) at 1.40 GHz. In this paper we present high sensitivity images at arcsecond resolution of the 18 objects showing extended structure in our images, and of another source from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey (Becker et al. 1995). In general our high sensitivity images reveal an amount of extended emission larger than previously reported. In some objects the luminosity of the extended structure is comparable with that of FR~II radio sources. A future paper will be devoted to the interpretation of these results.Comment: 12 pages, 35 figures, to appear on A&A Supp. Ser., postscript file with figures included available at http://www.ira.noto.cnr.it/staff/carlo/ds1030.ps.g

Bendings of radio jets in BL Lacertae objects I: EVN and MERLIN observations

Several blazars, and BL Lac objects in particular, show a misalignment between the jet orientation on parsec and kiloparsec scales. Some authors (i.e. Conway & Murphy, 1993) have attempted to explain this behaviour invoking helical jets for misalignment angles around 90\degr, showing how in this case there are interesting implications for the understanding of the medium into which the jet is expanding. By comparing sensitive VLA observations (Cassaro et al., 1999) with images available in the literature for the BL Lac objects from the 1-Jy Sample (Stickel et al., 1991), it is clear that there is a wide range of misalignments between the initial jet direction and the kpc-scale jet, when detected. We have carried out VLBI observations of these BL Lac objects, in order to investigate the spatial evolution of the radio jets from few tens to hundreds of mas, and to search for helical jets in this class of sources. We present here the first dataset obtained from EVN+MERLIN observations at 5 GHz for seven objects. From these observations we never have a clear detection of helical jets, we only have a possible signature of their presence in 2 objects. In only one of the sources with a misalignment angle around 90\degr the presence of helical jets can be ruled out. This implies that it is not possible to invoke helical jets to explain the morphology of all the sources showing a misalignment of about 90\degr between the parsec and the kiloparsec scale jets.Comment: 12 pages, 9 figures, latex, accepted by Astronomy & Astrophysic

Alteração da fertilidade do solo cultivado com cafeeiro conilon submetido a três níveis de fertilização com NPK.

Os solos do Estado de Rondônia, na extensão Noroeste do território brasileiro, apresentam grande variabilidade física e química. Na região norte do estado, onde se localiza o Munícipio de Porto Velho, os solos são, em sua maioria, ácidos, com porcentagem de saturação por alumínio acima de 50%, de baixa fertilidade química apresentando valores baixos para soma de bases, capacidade de troca de cátions e saturação por bases. O objetivo neste estudo foi avaliar as alterações na fertilidade do solo cultivado com cafeeiro ?Conilon? submetido à fertilização química com NPK. Os tratamentos estudados foram três níveis de fertilização com N, P e K (N1: 90-50-150; N2: 150-90-270 e N3: 210-130-390 kg ha-1) combinados com três camadas de avaliação 0-10; 10-20 e 20-40 cm de profundidade. O experimento foi conduzido em esquema de parcelas subdivididas 3x3 com três repetições no delineamento de blocos casualizados. Avaliou-se os atributos químicos do solo pH e os teores de P, K, Ca Mg, Al+H, Al, MO e V (%). Os atributos químicos dos solos não foram influenciados pelos três níveis de fertilizantes (NPK) empregados aos 14 meses após a implantação. Os atributos químicos do solo apresentaram condições mais favoráveis na camada superficial (0-10 e 10-20 cm), em relação à camada de 20-40 cm

Attenuated PGC-1 alpha Isoforms following Endurance Exercise with Blood Flow Restriction

Introduction: Exercise performed with blood flow restriction simultaneously enhances the acute responses to both myogenic and mitochondrial pathways with roles in training adaptation. We investigated isoform-specific gene expression of the peroxisome proliferator-activated receptor gamma (PPARG) coactivator 1 and selected target genes and proteins regulating skeletal muscle training adaptation. Methods: 9 healthy, untrained males participated in a randomized, counter-balanced, cross-over design in which each subject completed a bout of low-intensity endurance exercise performed with blood flow restriction (15 min cycling at 40% of VO2peak, BFR-EE), endurance exercise (30 min cycling at 70% of VO2peak, EE) or resistance exercise (4 x 10 repetitions of leg press at 70% of 1-repetition maximum, RE) separated by at least one week recovery. A single resting muscle biopsy (vastus lateralis) was obtained two weeks before the first exercise trial (rest) and 3 h after each boat. Results: Total PGC-1α mRNA abundance, along with all four isoforms, increased above rest with EE only (P<0.05) being higher than BFR-EE (P<0.05). PGC-1α1, 2 and 4 were higher after EE compared to RE (P<0.05). EE also increased VEGF, Hif-1α and MuRF-1 mRNA abundance above rest (P<0.05) while COXIV mRNA expression increased with EE compared to BFR-EE (P<0.05). Conclusion: The attenuated expression of all four PGC- 1α isoforms when endurance exercise is performed with blood flow restriction suggests this type of exercise provides an insufficient stimulus to activate the signaling pathways governing mitochondrial and angiogenesis responses observed with moderate- to high intensity endurance exercise

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

The high brightness temperatures, $T_\mathrm{b}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240,000 km we find two characteristic angular scales in the quasar core, about 100 $\mu$as and 10 $\mu$as. Some indications of scattering substructure are found. Very high brightness temperatures, $T_\mathrm{b}\geq 10^{13}$ K, are estimated at 4.8 GHz and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.Comment: 14 pages, 9 figure

Noto Station Status Report

The Noto VLBI station was fully operational in 2012, and the upgrade projects could be restarted, involving mainly the receiver area. Another important improvement was the activation of the 1 Gbps network

Understanding the nature of FRII optical nuclei: a new diagnostic plane for radio galaxies

We extend our study of the nuclei of 3CR FR II radio galaxies through HST optical images up to z=0.3. In the majority of them an unresolved nucleus (central compact core, CCC) is found. We analyze their position in the plane formed by the radio and optical nuclear luminosities in relation to their optical spectral properties. The broad-lined objects (BLO) have the brightest nuclei: they are present only at optical luminosities nu L_nu > 4 X 10^42 erg s^-1 which we suggest might represent a threshold in the radiative efficiency combined to a small range of black hole masses. About 40 % of the high and low excitation galaxies (HEG and LEG) show CCC which resemble those previously detected in FR I galaxies, in apparent contrast to the unification model. The equivalent width of the [OIII] emission line (with respect to the nuclear luminosity) reveals the nature of these nuclei, indicating that the nuclei of HEG are obscured to our line of sight and only scattered radiation is observed. This implies that the population of FR II is composed by objects with different nuclear properties, and only a fraction of them can be unified with quasars.Comment: 11 pages, 6 figures, in press on Astronomy & Astrophysics, minor changes have been mad

Low Power Compact Radio Galaxies at High Angular Resolution

We present sub-arcsecond resolution multi-frequency (8 and 22 GHz) VLA images of five low power compact (LPC) radio sources, and phase referenced VLBA images at 1.6 GHz of their nuclear regions. At the VLA resolution we resolve the structure and identify component positions and flux densities. The phase referenced VLBA data at 1.6 GHz reveals flat-spectrum, compact cores (down to a few milliJansky) in four of the five sources. The absolute astrometry provided by the phase referencing allows us to identify the center of activity on the VLA images. Moreover, these data reveal rich structures, including two-sided jets and secondary components. On the basis of the arcsecond scale structures and of the nuclear properties, we rule out the presence of strong relativistic effects in our LPCs, which must be intrinsically small (deprojected linear sizes <~ 10 kpc). Fits of continuous injection models reveal break frequencies in the GHz domain, and ages in the range 10^5-10^7 yrs. In LPCs, the outermost edge may be advancing more slowly than in more powerful sources or could even be stationary; some LPCs might also have ceased their activity. In general, the properties of LPCs can be related to a number of reasons, including, but not limited to: youth, frustration, low kinematic power jets, and short-lived activity in the radio.Comment: 15 pages, 9 .eps figures, accepted by A&

Comparison of Adaptive Control Architectures for Flutter Suppression

A study is conducted to derive and implement a state feedback model reference adaptive control (MRAC) solutions for a 2-D aeroelastic nonlinear system and in evaluating the robustness of different control strategies to damage leading to the deterioration of the structural stiffness characteristics. The standard MRAC, a modified MRAC and the adaptive controller are the three model reference adaptive control solutions analyzed. The standard direct MRAC solution serves as the threshold to assess whether or not the more complex algorithms are an effective improvement to it