267 research outputs found
Distribution and Intracellular Localization of Titanium in Plants After Titanium Treatment
The physiological role of titanium in plants has not been elucidated yet, but a higher rate of growth , greater chlorophyll content and higher productivity, among others , may be attributed to this element. We have investigated the distribution of titanium in wheat seedlings after Titavit (a Ti ·ascorbate containing plant conditioner) treatment applied either through the leaf or through the root. In field experiments, we also sprayed spinach plants with Titavit. We have found a practically unidirectional tran slocation of Ti from the shoot into the root, and a preferential local ization of Ti in the nuclear cell fraction as seen by JCP-AES (inductively coupled plasma atomic emission spectrometry). Electron microscopic X·ray microanalysis after chemical fixation showed little or no accumulation of Ti in the cells of the treated organs . However, if there was in appreciable Xray emission at 4.5 keV (Ti), it was recorded from the nucleoplasm and nucleolus. The comparison of ICPAES and X-ray analyses leads us to the conclusion that the majority of Ti may be in a diffusible form in the treated cells, except the nuclei, where Ti may be bound firmly
Compact binary waveform recovery from the cross-correlated data of two detectors by matched filtering with spinning templates
We investigate whether the recovery chances of highly spinning waveforms by matched filtering with randomly chosen spinning waveforms generated with the LAL package are improved by a cross-correlation of the simulated output of the L1 and H1 LIGO detectors. We find that a properly defined correlated overlap improves the mass estimates and enhaces the recovery of spin angles
Semi-transparent brane-worlds
We study the evolution of a closed Friedmann brane perturbed by the Hawking
radiation escaping a bulk black hole. The semi-transparent brane absorbes some
of the infalling radiation, the rest being transmitted across the brane to the
other bulk region. We characterize the cosmological evolution in terms of the
transmission rate . For small values of a critical-like
behaviour could be observed, when the acceleration due to radiation pressure
and the deceleration induced by the increasing self-gravity of the brane
roughly compensate each other, and cosmological evolution is approximately the
same as without radiation. Lighter (heavier) branes than those with the
critical energy density will recollapse slower (faster). This feature is
obstructed at high values of , where the overall effect of the
radiation is to speed-up the recollapse. We determine the maximal value of the
transmission rate for which the critical-like behaviour is observed. We also
study the effect of transmission on the evolution of different source terms of
the Friedmann equation. We conclude that among all semi-transparent branes the
slowest recollapse occurs for light branes with total absorption.Comment: 15 pages, 8 figure
On the validity of the 5-dimensional Birkhoff theorem: The tale of an exceptional case
The 5-dimensional (5d) Birkhoff theorem gives the class of 5d vacuum
space-times containing spatial hypersurfaces with cosmological symmetries. This
theorem is violated by the 5d vacuum Gergely-Maartens (GM) space-time, which is
not a representant of the above class, but contains the static Einstein brane
as embedded hypersurface. We prove that the 5d Birkhoff theorem is still
satisfied in a weaker sense: the GM space-time is related to the degenerated
horizon metric of certain black-hole space-times of the allowed class. This
result resembles the connection between the Bertotti-Robinson space-time and
the horizon region of the extremal Reissner-Nordstrom space-time in general
relativity.Comment: 13 pages; v2: title amended, to be published in Classical and Quantum
Gravit
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