A kpc-scale X-ray jet in the BL Lac source S5 2007+777

X-ray jets in AGN are commonly observed in FRII and FRI radio-galaxies, 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 ACIS-S 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_x~1, although the uncertainties are large. 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.Comment: Accepted for publication in ApJ, 19 pages, 3 figure

Deep Chandra and multicolor HST observations of the jets of 3C 371 and PKS 2201+044

This paper presents multiwavelength imaging and broad-band spectroscopy of the relativistic jets in the two nearby radio galaxies 3C 371 and PKS 2201+044, acquired with Chandra, HST, VLA, and Merlin. Radio polarization images are also available. The two sources stand out as "intermediate'' between FRIs and FRIIs; their cores are classified as BL Lacs, although broad and narrow optical emission lines were detected at times. The multiwavelength images show jet morphologies with the X-ray emission peaking closer to the nucleus than the longer wavelengths. The jets are resolved at all wavelengths in a direction perpendicular to the jet axis. The jets SEDs are consistent with a single spectral component from radio to X-rays, interpreted as synchrotron emission. The SEDs show a progressive softening from the inner to the outer regions of the jet, indicating that the electron break energy moves to lower energies with distance from the core. Overall, the X-ray and multiwavelength properties of the jets of 3C 371 and PKS 2201+044 appear intermediate between those of FRIs and FRIIs.Comment: Accepted for publication in ApJ; 28 pages (emulateapj5), 17 figure

Mechanisms of 2n potato pollen formation in dihaploid Solanum tuberosum L. x S. chacoense Bitt. hybrid clones.

The backcrosses of dihaploid Solanum tuberosum with wild species hybrids generating tetraploids progenies require the formation of non-reduced pollen. In this work, the mechanisms responsible for the formation of 2n pollen in 28 dihaploid Solanum tuberosum x Solanum chacoense hybrids were studied. Four mechanisms were found: parallelspindles (ps), fused spindles (fs), premature cytokinesis-1 (pc-1) and premature cytokinesis-2 (pc-2). The ps mechanism was the most frequent, being found in 23 of the 28 assessed clones. The ps and fs mechanisms led to the formation of dyads by first division restitution (FDR), transferring about 80% of the heterozygosity to the progenies. The pc-1 and pc-2 mechanisms also led to the formation of dyads, but they were genetically equivalent to second division restitution (SDR), transferring only 40% of the heterozygosity to the progenies. Occurrence of FDR and SDR were shown to be associated in 12 clones, indicating that the clones can produce non-reduced microspores by more than one mechanism. However, only one mechanism is functional in a single pollen-grain mother-cell. Clones 9-2, 9-3, 9-6 and 15-15 are recommended for use in 4x x 2x matings

Fat-free noncontrast whole-heart CMR with fast and power-optimized off-resonant water excitation pulses

Background: Cardiovascular MRI (CMR) faces challenges due to the interference of bright fat signals in visualizing anatomical structures. Effective fat suppression is crucial when using whole-heart CMR. Conventional methods often fall short due to rapid fat signal recovery and water-selective off-resonant pulses come with tradeoffs between scan time and RF energy deposit. A lipid-insensitive binomial off-resonant (LIBOR) RF pulse is introduced, addressing concerns about RF energy and scan time for CMR at 3T. Methods: A short LIBOR pulse was developed and implemented in a free-breathing respiratory self-navigated whole-heart sequence at 3T. A BORR pulse with matched duration, as well as previously used LIBRE pulses, were implemented and optimized for fat suppression in numerical simulations and validated in healthy subjects (n=3). Whole-heart CMR was performed in healthy subjects (n=5) with all four pulses. The SNR of ventricular blood, skeletal muscle, myocardium, and subcutaneous fat, and the coronary vessel sharpness and length were compared. Results: Experiments validated numerical findings and near homogeneous fat suppression was achieved with all pulses. Comparing the short pulses (1ms), LIBOR reduced the RF power two-fold compared with LIBRE, and three-fold compared with BORR, and LIBOR significantly decreased overall fat SNR. The reduction in RF duration shortened the whole-heart acquisition from 8.5min to 7min. No significant differences in coronary arteries detection and sharpness were found when comparing all four pulses. Conclusion: LIBOR enabled whole-heart CMR under 7 minutes at 3T, with large volume fat signal suppression, while reducing RF power compared with LIBRE and BORR. LIBOR is an excellent candidate to address SAR problems encountered in CMR where fat suppression remains challenging and short RF pulses are required.Comment: 25 pages, 7 figures, 2 table

High performance bilayer-graphene Terahertz detectors

We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity $\sim 1.2V/W (1.3 mA/W)$ and a noise equivalent power $\sim 2\times 10^{-9} W/Hz^{-1/2}$ in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems.Comment: 8 pages, 5 figures. Submitted to Applied Physics Letter

Lagrangian phase transitions in nonequilibrium thermodynamic systems

In previous papers we have introduced a natural nonequilibrium free energy by considering the functional describing the large fluctuations of stationary nonequilibrium states. While in equilibrium this functional is always convex, in nonequilibrium this is not necessarily the case. We show that in nonequilibrium a new type of singularities can appear that are interpreted as phase transitions. In particular, this phenomenon occurs for the one-dimensional boundary driven weakly asymmetric exclusion process when the drift due to the external field is opposite to the one due to the external reservoirs, and strong enough.Comment: 10 pages, 2 figure

Multi-time delay, multi-point Linear Stochastic Estimation of a cavity shear layer velocity from wall-pressure measurements

Multi-time-delay Linear Stochastic Estimation (MTD-LSE) technique is thoroughly described, focusing on its fundamental properties and potentialities. In the multi-time-delay ap- proach, the estimate of the temporal evolution of the velocity at a given location in the flow field is obtained from multiple past samples of the unconditional sources. The technique is applied to estimate the velocity in a cavity shear layer flow, based on wall-pressure measurements from multiple sensor

Anomalous Aharonov--Bohm gap oscillations in carbon nanotubes

The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observation of the Aharonov-Bohm effect at the nano--scale. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. Using an ab-initio approach based on Density Functional Theory we show that this assumption fails at the nano-scale inducing important corrections to the physics of the Aharonov-Bohm effect. Curvature effects and electronic density spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations. We predict the key phenomenological features of this anomalous Aharonov-Bohm effect in semi-conductive and metallic tubes and the existence of a large metallic phase in the low flux regime of Multi-walled nanotubes, also suggesting possible experiments to validate our results.Comment: 7 figure

Janus Configurations, Chern-Simons Couplings, And The Theta-Angle in N=4 Super Yang-Mills Theory

We generalize the half-BPS Janus configuration of four-dimensional N=4 super Yang-Mills theory to allow the theta-angle, as well as the gauge coupling, to vary with position. We show that the existence of this generalization is closely related to the existence of novel three-dimensional Chern-Simons theories with N=4 supersymmetry. Another closely related problem, which we also elucidate, is the D3-NS5 system in the presence of a four-dimensional theta-angle.Comment: 66 p