Mergers of neutron stars (NS ϩ NS) or neutron stars and stellar-mass black holes (NS ϩ BH) eject a small fraction of matter with a subrelativistic velocity. Upon rapid decompression, nuclear-density medium condenses into neutron-rich nuclei, most of them radioactive. Radioactivity provides a long-term heat source for the expanding envelope. A brief transient has a peak luminosity in the supernova range, and the bulk of radiation in the UVoptical domain. We present a very crude model of the phenomenon, and simple analytical formulae that can be used to estimate the parameters of a transient as a function of poorly known input parameters. The mergers may be detected with high-redshift supernova searches as rapid transients, many of them far away from the parent galaxies. It is possible that the mysterious optical transients detected by Schmidt et al. are related to neutron star mergers, since they typically have no visible host galaxy.

Based on a spectral analysis of the X-ray continuum that employs a fully relativistic accretion disk model, we conclude that the compact primary of the binary X-ray source GRS 1915+105 is a rapidly rotating Kerr black hole. We find a lower limit on the dimensionless spin parameter of a à > 0:98. Our result is robust in the sense that it is independent of the details of the data analysis and insensitive to the uncertainties in the mass and distance of the black hole. Furthermore, our accretion disk model includes an advanced treatment of spectral hardening. Our data selection relies on a rigorous and quantitative definition of the thermal state of black hole binaries, which we used to screen all of the available RXTE and ASCA data for the thermal state of GRS 1915+105. In addition, we focus on those data for which the accretion disk luminosity is less than 30% of the Eddington luminosity. We argue that these low-luminosity data are most appropriate for the thin -disk model that we employ. We assume that there is zero torque at the inner edge of the disk, as is likely when the disk is thin, although we show that the presence of a significant torque does not affect our results. Our model and the model of the relativistic jets observed for this source constrain the distance and black hole mass and could thus be tested by determining a VLBA parallax distance and improving the measurement of the mass function. Finally, we comment on the significance of our results for relativistic jet and core-collapse models and for the detection of gravitational waves.

We use a ray-tracing technique to compute the observed spectrum of a thin accretion disk around a Kerr black hole. We include all relativistic effects such as frame-dragging, Doppler boost, gravitational redshift, and bending of light by the gravity of the black hole. We also include self-irradiation of the disk as a result of light deflection. Assuming that the disk emission is locally blackbody, we show how the observed spectrum depends on the spin of the black hole, the inclination of the disk, and the torque at the inner edge of the disk. We find that the effect of a nonzero torque on the spectrum can, to a good approximation, be absorbed into a zero-torque model by adjusting the mass accretion rate and the normalization. We describe a computer model, called KERRBB, which we have developed for fitting the spectra of black hole X-ray binaries. Using KERRBB within the Xray data reduction package XSPEC, and assuming a spectral hardening factor f col = 1.7, we analyze the spectra of three black hole X-ray binaries: 4U1543-47, XTE J1550-564, and GRO J1655-40. We estimate the spin parameters of the black holes in 4U1543-47 and GRO J1655-40 to be a/M ∼ 0.6 and ∼ 0.6 − 0.7, respectively. If f col ∼ 1.5 − 1.6, as in a recent study, then we find a/M ∼ 0.7 − 0.8 and ∼ 0.8 − 0.9, respectively. These estimates are subject to additional uncertainties in the assumed black hole masses, distances and disk inclinations.

We fit X-ray spectral data in the thermal-dominant, or high-soft, state of two dynamically confirmed black holes, GRO J1655Ϫ40 and 4U 1543Ϫ47, and estimate the dimensionless spin parameters { a/M of the two holes. a * For GRO J1655Ϫ40, using a spectral hardening factor computed for a non-LTE relativistic accretion disk, we estimate ∼ 0.75 and ∼ 0.65-0.75, respectively, from ASCA and RXTE data. For 4U 1543Ϫ47, we estimate ∼ a a a * * * 0.75-0.85 from RXTE data. Thus, neither black hole has a spin approaching the theoretical maximum p 1. a *

We present a new sample of 116 double-peaked Balmer line Active Galactic Nuclei (AGNs) selected from the Sloan Digital Sky Survey. Double-peaked emission lines are believed to originate in the accretion disks of AGN, a few hundred gravitational radii (R G ) from the supermassive black hole. We investigate the properties of the candidate disk emitters with respect to the full sample of AGN over the same redshifts, focusing on optical, radio and X-ray flux, broad line shapes and narrow line equivalent widths and line flux-ratios. We find that the disk-emitters have medium luminosities (∼10 44 erg s −1 ) and FWHM on average six times broader than the AGN in the parent sample. The double-peaked AGN are 1.6 times more likely to be radio-sources and are predominantly (76%) radio quiet, with about 12% of the objects classified as LINERs. Statistical comparison of the observed double-peaked line profiles with those produced by axisymmetric and non-axisymmetric accretion disk models allows us to impose constraints on accretion disk parameters. The observed Hα line profiles are consistent with accretion disks with inclinations smaller than 50 • , surface emissivity slopes of 1.0-2.5, outer radii larger than ∼2000R G , inner radii between 200-800R G , and local turbulent broadening of 780-1800 km s −1 . The comparison suggests that 60% of accretion disks require some form of asymmetry (e.g., elliptical disks, warps, spiral shocks or hot spots).

Background-Angiotensin II-induced hypertension is associated with NAD(P)H oxidase-dependent superoxide production in the vessel wall. Vascular superoxide level is also increased in deoxycorticosterone acetate (DOCA)-salt hypertension, which is associated with a markedly depressed plasma renin activity because of sodium retention. However, the mechanisms underlying superoxide production in low-renin hypertension are undefined. Methods and Results-This study investigated (1) whether and how endothelin-1 (ET-1), which is increased in DOCA-salt hypertensive rats, contributes to arterial superoxide generation and (2) the effect of gene transfer of manganese superoxide dismutase and endothelial nitric oxide synthase. Both superoxide and ET-1 levels were significantly elevated in carotid arteries of DOCA-salt rats compared with that of the sham-operated controls. ET-1 concentration-dependently stimulated superoxide production in vitro in carotid arteries of normotensive rats. The increase in arterial superoxide in both ET-1-treated normotensive and DOCA-salt rats was reversed by a selective ET A receptor antagonist, ABT-627, the flavoprotein inhibitor diphenyleneiodonium, and the NADPH oxidase inhibitor apocynin but not by the nitric oxide synthase inhibitor N -L-arginine methyl ester or the xanthine oxidase inhibitor allopurinol. Furthermore, in vivo blockade of ET A receptors significantly reduced arterial superoxide levels, with a concomitant decrease of systolic blood pressure in DOCA-salt rats. Ex vivo gene transfer of manganese superoxide dismutase or endothelial nitric oxide synthase also suppressed superoxide levels in carotid arteries of DOCA-salt rats. Conclusions-These findings suggest that ET-1 augments vascular superoxide production at least in part via an ET A /NADPH oxidase pathway in low-renin mineralocorticoid hypertension.

Site-specific and rare cutting nucleases are valuable tools for genome engineering. The generation of double-strand DNA breaks (DSBs) promotes homologous recombination in eukaryotes and can facilitate gene targeting, additions, deletions, and inactivation. Zinc finger nucleases have been used to generate DSBs and subsequently, for genome editing but with low efficiency and reproducibility. The transcription activator-like family of type III effectors (TALEs) contains a central domain of tandem repeats that could be engineered to bind specific DNA targets. Here, we report the generation of a Hax3-based hybrid TALE nuclease with a userselected DNA binding specificity. We show that the engineered TALE nuclease can bind to its target sequence in vitro and that the homodimeric TALE nuclease can cleave double-stranded DNA in vitro if the DNA binding sites have the proper spacing and orientation. Transient expression assays in tobacco leaves suggest that the hybrid nuclease creates DSB in its target sequence, which is subsequently repaired by nonhomologous end-joining repair. Taken together, our data show the feasibility of engineering TALE-based hybrid nucleases capable of generating site-specific DSBs and the great potential for site-specific genome modification in plants and eukaryotes in general. molecular scissors | nontransgenic mutagenesis | artificial activators

Targeted genome editing in plants will not only facilitate functional genomics studies but also help to discover, expand, and create novel traits of agricultural importance (Pennisi, 2010). The most widely used approach for editing plant genomes involves generating targeted double-strand DNA breaks (DSBs) and harnessing the two main DSB repair pathways: imprecise non-homologous end joining and precise homology-directed repair (Voytas, 2013). Enzymes that specifically bind the userselected genomic sequences to create DSBs can be generated de novo as synthetic bimodular proteins containing a DNAbinding module, engineered to bind a user-defined sequence, along with a DNA-cleaving module, capable of making DSBs. Several classes of nucleases have been developed with DNAbinding domains engineered to confer sequence specificity, including homing endonucleases, zinc finger nucleases (ZFNs), and transcription activator-like effector nucleases (TALENs). Customization of these genome editing platforms, however, requires protein engineering, a time-consuming and laborintensive process (Puchta and Fauser, 2014). Furthermore, delivery of genome engineering reagents into plant cells is a major barrier to the effective use of these technologies for creating novel traits (Baltes et al., 2014).