Biochemistry of fruit ripening Seymour, G.B; Taylor, J.E; Tucker, G.A. (eds.) (Horticulture Research International, Littlehampton, West Sussex (United Kingdom))
1993
Book
We report upper limits on the polarization of the cosmic microwave background radiation (CMBR) as measured with the Cosmic Background Imager (CBI), a 13 element interferometer that operates in the ...26-36 GHz band and is sited on Llano de Chajnantor in northern Chile. The array consists of 90 cm Cassegrain antennas mounted on a steerable platform that can be rotated about the optical axis to facilitate polarization observations. The CBI employs single-mode circularly polarized receivers, and it samples multipoles from l similar to 400 to l similar to 3500. The polarization data were calibrated on 3C 279 and Taurus A. The polarization observations consist of 278 hr of data on two fields taken in 2000, during the first CBI observing season. A joint likelihood analysis of the two fields yields three upper limits (95% confidence limit) for Cl super(EE) = C super(EE)l(l + 1)/2 pi under the assumption that Cl super(BB) identical with 0: 49.0 mu K super(2) (l = 603), 164 mu K super(2) (l = 1144), and 630 mu K super(2) (l = 2048).
Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anthocyanins. Flavonols are required for functional pollen in maize whereas anthocyanins are non-essential ...pigments. A cDNA for F3H was isolated from Zea mays using a heterologous sequence from Antirrhinum majus. Comparison of the deduced amino acid sequence of maize F3H with other F3H sequences confirmed that the protein is highly conserved among widely divergent plant species. The F3H gene is present in a single copy located at the tip of chromosome 2S. High levels of F3H gene expression were detected in pigmented husk and 26-day postpollination kernels; lower levels in 18-day postpollination kernels and in coleoptiles of germinating seedlings. Slot blot analysis showed that F3H transcript levels in young seedlings are increased by high fluence-rate white light treatment in the presence of the anthocyanin regulatory gene -r. HPLC analysis of extracts from developmentally staged anthers showed that flavonol accumulation begins at the uninucleate microspore stage, continues until maturity, and is not controlled by -r. When the expression pattern of several flavonoid biosynthetic genes was analyzed during microsporogenesis, only F3H transcript accumulation was coordinate with the appearance of flavonols in anthers.
Context. This is the second in a series of papers presenting VLBI observations of the 293 Caltech-Jodrell Bank Flat-spectrum (hereafter CJF) sources and their analysis. Aims. We obtain a consistent ...motion dataset large enough to allow the systematic properties of the population to be studied. Methods. We present detailed kinematic analysis of the complete flux-density limited CJF survey. We computed 2D kinematic models based on the optimal model-fitting parameters of multi-epoch VLBA observations. This allows us to calculate not only radial, but also orthogonal motions, and thus to study curvature and acceleration. Statistical tests of the motions measured and their reliability were performed. A correlation analysis between the derived apparent motions, luminosities, spectral indices, and core dominance and the resulting consequences is described. Results. With at least one velocity in each of the 237 sources, this sample is much larger than any available before, so it allows a meaningful statistical investigation of apparent motions and any possible correlations with other parameters in AGN jets. The main results to emerge are as follows: – In general motions are not consistent with a single uniform velocity applicable to all components along a jet. – We find a slight trend towards a positive outward acceleration and also adduce some evidence for greater acceleration in the innermost regions. – We find a lack of fast components at physical distances less than a few pc from the reference feature. – Only ~4% of the components from galaxies and <2% of those from quasars undergo large bends i.e. within $15^\circ$ of ±$90^\circ$. – The distribution of radial velocities shows a broad distribution of velocities (apparent velocities up to 30 c). Fifteen percent of the best-sampled jet components exhibit low velocities that may need to be explained in a different manner to the fast motions. – Some negative superluminal motions are seen, and in 15 cases (6%) these are definitely significant. – We find a strong correlation between the 5 GHz luminosity and the apparent velocity. – The CJF galaxies, on average, show slower apparent jet-component velocities than the quasars. – The mean velocity in the VLBA 2 cm survey (Kellermann et al. 2004, ApJ, 609, 539) is substantially higher than in the CJF survey, the ratio could be roughly a factor of 1.5-2. This supports the observed trend toward increasing apparent velocity with increasing observing frequency. Conclusions. This AGN survey provides the basis for any statistical analysis of jet and jet-component properties.
We present X-ray and radio observations of the recently-discovered bow shock pulsar wind nebula associated with PSR J0002+6216, characterizing the PWN morphology, which was unresolved in previous ...studies. The multi-frequency, multi-epoch Very Large Array radio observations reveal a cometary tail trailing the pulsar and extending up to 5.3', with multiple kinks along the emission. The presented radio continuum images from multi-configuration broadband VLA observations are one of the first results from the application of multi-term multi-frequency synthesis deconvolution in combination with the awproject gridder implemented in the Common Astronomy Software Applications package (CASA). The X-ray emission observed with Chandra extends to only 21'', fades quickly, and has some hot spots present along the extended radio emission. These kinks could indicate the presence of density variation in the local ISM or turbulence. The bow shock standoff distance estimates a small bow shock region with a size 0.003-0.009 pc, consistent with the pulsar spin-down power of Edot=1.51x10^35 ergs/s estimated from timing. The high-resolution radio image reveals the presence of an asymmetry in the bow shock region which is also present in the X-ray image. The broadband radio image shows an unusually steep spectrum along with a flat-spectrum sheath, which could indicate varying opacity or energy injection into the region. Spatially-resolved X-ray spectra provide marginal evidence of synchrotron cooling along the extended tail. Our analysis of the X-ray data also shows that this pulsar has a low spin-down power and one of the lowest X-ray efficiencies observed in these objects.
The Belle II silicon vertex detector assembly and mechanics Adamczyk, K.; Aihara, H.; Angelini, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2017, Volume:
845
Journal Article
Peer reviewed
The Belle II experiment at the asymmetric SuperKEKB collider in Japan will operate at an instantaneous luminosity approximately 50 times greater than its predecessor (Belle). The central feature of ...the experiment is a vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is CP violation asymmetry in the decays of beauty and charm hadrons, which hinges on a precise charged-track vertex determination and low-momentum track measurement. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision 3D coordinate measurements of the final SVD modules.
Finally, some results from the latest test-beam are reported.
In rats with microdialysis probes in the nucleus accumbens (NAc) or prefrontal cortex (PFC), intraperitoneally (IP) delivered morphine on the 8th day of escalating doses decreased extracellular ACh ...in the NAc. On day 9, naloxone (5 mg/kg) precipitated withdrawal and increased the release of ACh. When morphine and methylnaloxonium were given locally into the NAc by reverse dialysis, the opiate again decreased extracellular ACh, and the opiate antagonist increased it. These effects were proportional to the dose of local infusions. Local morphine had the same ACh-lowering effect in morphine-dependent and nondependent rats, whereas local methylnaloxonium increased extracellular ACh significantly more in morphine-dependent animals. Systemic and local effects on ACh systems in the PFC were more complicated and showed some relation to locomotor activity. The results suggest that intrinsic ACh neurons in the NAc have a special relationship to opiate reinforcement such that extracellular ACh is low in response to morphine and high during withdrawal. Thus, low ACh may correlate with opiate reward, and high ACh with aversion.
PDF
