Effect of various stresses on the incorporation of [3H]orotic acid into goldfish brain RNA

The effect of a number of stresses on the incorporation of [5-3H]orotic acid into total goldfish brain RNA and its pyrimidine precursors is reported. The ratio of labeling of the uridylate and cytidylate moieties of the RNA (U/C) varied as a function of the temperature and duration of the experiment. The ratio was elevated when fish were subjected to pentylenetetrazol-induced convulsions or to mild electrical shock, with or without training of an avoidance conditioning task. The increase in ratio in all cases resulted from a decrease in cytidylate labeling. In experiments where this decrease was marked, a substantial decrease in the labeling of total RNA was seen as well. The observation that the increase in U/C was greater when increased numbers of fish were shocked per tank eventually led to the finding that addition of carbon dioxide to tank water results in a decrease in labeling of cytidylate isolated from RNA hydrolysates, as well as decreased labeling of cytidine precursors of RNA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34119/1/0000403.pd

Spectropolarimetry of high-redshift obscured and red quasars

Spectropolarimetry is a powerful technique that has provided critical support for the geometric unification model of local active galactic nuclei. In this paper, we present optical (rest-frame UV) Keck spectropolarimetry of five luminous obscured (Type 2) and extremely red quasars (ERQs) at z~2.5. Three objects reach polarization fractions of >10% in the continuum. We propose a model in which dust scattering is the dominant scattering and polarization mechanism in our targets, though electron scattering cannot be completely excluded. Emission lines are polarized at a lower level than is the continuum. This suggests that the emission-line region exists on similar spatial scales as the scattering region. In three objects we detect an intriguing 90 degree swing in the polarization position angle as a function of line-of-sight velocity in the emission lines of Ly-alpha, CIV and NV. We interpret this phenomenon in the framework of a geometric model with an equatorial dusty scattering region in which the material is outflowing at several thousand km/sec. Emission lines may also be scattered by dust or resonantly. This model explains several salient features of observations by scattering on scales of a few tens of pc. Our observations provide a tantalizing view of the inner region geometry and kinematics of high-redshift obscured and extremely red quasars. Our data and modeling lend strong support for toroidal obscuration and powerful outflows on the scales of the UV emission-line region, in addition to the larger scale outflows inferred previously from the optical emission-line kinematics.Comment: 26 pages, MNRAS, in pres

Femtosecond Dynamics of Dioxygen - Picket-Fence Cobalt Porphyrins: Ultrafast Release of O_2 and the Nature of Dative Bonding

The ultrafast release of O_2 from the O_2 adduct of picket-fence cobalt porphyrin (see picture) has been probed in real time, and has a total reaction time of 2 ps, without subsequent recombination over several nanoseconds. The dynamics of this ultrafast release of O_2 shows that relaxation within the porphyrin system (200 fs) precedes porphyrin-to-metal electron transfer, but the latter occurs at an enhanced rate (500 fs as opposed to the more usual 1 – 2 ps) because of the dative bonding of cobalt and O_2, which gives the adduct ground state significant Co^(III)−O_2^− character

Psychopaths show enhanced amygdala activation during fear conditioning

Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into primary and secondary psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional fearlessness, while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC) for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths

Femtosecond Dynamics and Electrocatalysis of the Reduction of O_2: Tetraruthenated Cobalt Porphyrins

Recently we reported the femtosecond dynamics of some porphyrin molecules. These studies elucidated the elementary steps involved in intramolecular relaxation and charge transfer (CT) in cobalt tetraphenylporphyrin (CoTPP) from the porphyrin π (a_(2u)) system to the Co(d_z^2). Our interest in the dynamics of intramolecular electron transfer stems from recent studies of cobalt porphyrins that were modified by attachment of Ru(II) or Os(II) complexes to the periphery of the porphyrin ring. These modified cobalt porphyrins exhibit high catalytic activity for the electroreduction of O_2 directly to H_2O, a process that most monomeric cobalt porphyrins are unable to accomplish. The mechanism by which the modified cobalt porphyrins achieve the direct, four-electron reduction of O_2 has been suggested to involve back-bonding interactions among the attached Ru(II) and Os(II) centers, the porphyrin ring, and the Co(II) ion at its center

Femtosecond Dynamics and Electrocatalysis of the Reduction of O_2: Tetraruthenated Cobalt Porphyrins

Recently we reported the femtosecond dynamics of some porphyrin molecules. These studies elucidated the elementary steps involved in intramolecular relaxation and charge transfer (CT) in cobalt tetraphenylporphyrin (CoTPP) from the porphyrin π (a_(2u)) system to the Co(d_z^2). Our interest in the dynamics of intramolecular electron transfer stems from recent studies of cobalt porphyrins that were modified by attachment of Ru(II) or Os(II) complexes to the periphery of the porphyrin ring. These modified cobalt porphyrins exhibit high catalytic activity for the electroreduction of O_2 directly to H_2O, a process that most monomeric cobalt porphyrins are unable to accomplish. The mechanism by which the modified cobalt porphyrins achieve the direct, four-electron reduction of O_2 has been suggested to involve back-bonding interactions among the attached Ru(II) and Os(II) centers, the porphyrin ring, and the Co(II) ion at its center