43,864 research outputs found
Osmotic regulation of alpha-amylase synthesis and polyribosome formation in aleurone cells of barley.
Water stress inhibits the gibberellic acid (GA(3))-induced synthesis of alpha-amylase in aleurone layers of barley (Hordeum vulgare L.). Electron microscope evidence indicates that the effect of water stress induced by 0.6 M solutions of polyethylene glycol (PEG) is to reduce the binding of ribosomes to the endoplasmic reticulum. This was confirmed by sucrose density gradient centrifugation of polyribosome preparations from stressed cells. The reduction in polyribosome formation does not result from reduced ribosome activity as measured by [(3)H]peptidylpuromycin formation. Thus, calculation of percent active ribosomes shows that osmoticum has little effect on the ability of ribosomes to incorporate puromycin into nascent protein. Water stress does not cause a marked decrease in the total RNA level of aleurone cells. Estimates of total RNA in postmitochondrial supernatant fractions from stressed cells show only a reduction of 8-9% relative to the control. Membrane synthesis measured by [(14)C]choline incorporation is depressed by 15% in cells stressed with 0.6 M PEG for 2.5 hours
Application of dimensional analysis and group theory to the solution of ordinary and partial differential equations Final report, 17 Jan. 1966 - 16 Jan. 1967
Dimensional analysis and group theory methods of solving ordinary and partial differential equation
Comparison of data on Mutation Frequencies of Mice Caused by Radiation - Low Dose Model -
We propose LD(Low Dose) model, the extension of LDM model which was proposed
in the previous paper [Y. Manabe et al.: J. Phys. Soc. Jpn. 81 (2012) 104004]
to estimate biological damage caused by irradiation. LD model takes account of
all the considerable effects including cell death effect as well as
proliferation, apoptosis, repair. As a typical example of estimation, we apply
LD model to the experiment of mutation frequency on the responses induced by
the exposure to low levels of ionizing radiation. The most famous and extensive
experiments are those summarized by Russell and Kelly [Russell, W. L. & Kelly,
E. M: Proc. Natl Acad. Sci. USA 79 (1982) 539-541], which are known as
'Mega-mouse project'. This provides us with important information of the
frequencies of transmitted specific-locus mutations induced in mouse
spermatogonia stem-cells. It is found that the numerical results of the
mutation frequency of mice are in reasonable agreement with the experimental
data: the LD model reproduces the total dose and dose rate dependence of data
reasonably. In order to see such dose-rate dependence more explicitly, we
introduce the dose-rate effectiveness factor (DREF). This represents a sort of
preventable effects such as repair, apoptosis and death of broken cells, which
are to be competitive with proliferation effect of broken cells induced by
irradiation.Comment: subimitting to J. Phys. Soc. Jpn, 32 pages, 8 figure
Experimental evidence for kin-biased helping in a cooperatively breeding vertebrate
The widespread belief that kin selection is necessary for the evolution of cooperative breeding in vertebrates has recently been questioned. These doubts have primarily arisen because of the paucity of unequivocal evidence for kin preferences in cooperative behaviour. Using the cooperative breeding system of long-tailed tits (Aegithalos caudatus) in which kin and non-kin breed within each social unit and helpers are failed breeders, we investigated whether helpers preferentially direct their care towards kin following breeding failure. First, using observational data, we show that not all failed breeders actually become helpers, but that those that do help usually do so at the nest of a close relative. Second, we confirm the importance of kinship for helping in this species by conducting a choice experiment. We show that potential helpers do not become helpers in the absence of close kin and, when given a choice between helping equidistant broods belonging to kin and non-kin within the same social unit, virtually all helped at the nest of kin. This study provides strong evidence that kinship plays an essential role in the maintenance of cooperative breeding in this species
Application of the scalar and vector potentials to the aerodynamics of jets
The applicability of a method based on the Stokes potentials (vector and scalar potentials) to computations associated with the aerodynamics of jets was examined. The aerodynamic field near the nozzle could be represented and that the influence of a nonuniform velocity profile at the nozzle exit plane could be determined. Also computations were made for an axisymmetric jet exhausting into a quiescient atmosphere. The velocity at the axis of the jet, and the location of the half-velocity points along the jet yield accurate aerodynamic field computations. Inconsistencies among the different theoretical characterizations of jet flowfields are shown
Line Emission in the Brightest Cluster Galaxies of the NOAO Fundamental Plane and Sloan Digital Sky Surveys
We examine the optical emission line properties of Brightest Cluster Galaxies
(BCGs) selected from two large, homogeneous datasets. The first is the X-ray
selected National Optical Astronomy Observatory Fundamental Plane Survey
(NFPS), and the second is the C4 catalogue of optically selected clusters built
from the Sloan Digital Sky Survey Data Release ~3 (SDSS DR3). Our goal is to
better understand the optical line emission in BCGs with respect to properties
of the galaxy and the host cluster. Throughout the analysis we compare the line
emission of the BCGs to that of a control sample made of the other bright
galaxies near the cluster centre. Overall, both the NFPS and SDSS show a modest
fraction of BCGs with emission lines (~15%). No trend in the fraction of
emitting BCGs as a function of galaxy mass or cluster velocity dispersion is
found. However we find that, for those BCGs found in cooling flow clusters,
71^{+9}_{-14}% have optical emission. Furthermore, if we consider only BCGs
within 50kpc of the X-ray centre of a cooling flow cluster, the emission-line
fraction rises further to 100^{+0}_{-15}%. Excluding the cooling flow clusters,
only ~10% of BCGs are line emitting, comparable to the control sample of
galaxies. We show that the physical origin of the emission line activity
varies: in some cases it has LINER-like line ratios, whereas in others it is a
composite of star-formation and LINER-like activity. We conclude that the
presence of emission lines in BCGs is directly related to the cooling of X-ray
gas at the cluster centre.Comment: Accepted for publication in MNRAS. 13 pages mn2e style with 7 figures
and 2 table
Alternator and voltage regulator-exciter for a Brayton cycle space power system. Volume 2 - Unbalanced electromagnetic forces
Unbalanced electromagnetic forces in Brayton cycle turboalternator for space power syste
A Mathematical Model for Estimating Biological Damage Caused by Radiation
We propose a mathematical model for estimating biological damage caused by
low-dose irradiation. We understand that the Linear Non Threshold (LNT)
hypothesis is realized only in the case of no recovery effects. In order to
treat the realistic living objects, our model takes into account various types
of recovery as well as proliferation mechanism, which may change the resultant
damage, especially for the case of lower dose rate irradiation. It turns out
that the lower the radiation dose rate, the safer the irradiated system of
living object (which is called symbolically "tissue" hereafter) can have
chances to survive, which can reproduce the so-called dose and dose-rate
effectiveness factor (DDREF).Comment: 22 pages, 6 Figs, accepted in Journal of the Physical Society of
Japa
Direct dialling of Haar random unitary matrices
Random unitary matrices find a number of applications in quantum information
science, and are central to the recently defined boson sampling algorithm for
photons in linear optics. We describe an operationally simple method to
directly implement Haar random unitary matrices in optical circuits, with no
requirement for prior or explicit matrix calculations. Our physically-motivated
and compact representation directly maps independent probability density
functions for parameters in Haar random unitary matrices, to optical circuit
components. We go on to extend the results to the case of random unitaries for
qubits
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