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1.
H Gavish I Bab A Tartakovsky M Chorev N Mansur Z Greenberg M Namdar-Attar A Muhlrad 《Canadian Metallurgical Quarterly》1997,36(48):14883-14888
The osteogenic growth peptide (OGP) is a 14mer mitogen of osteoblastic and fibroblastic cells. Physiologically, OGP is present in high abundance in human and other mammalian sera. Most of the serum OGP is complexed noncovalently to heat sensitive, high molecular weight OGP-binding proteins (OGPBPs). Changes in serum OGP levels that follow bone marrow ablation and the low doses of exogenous OGP required for the stimulation of bone formation suggest a regulatory role for the OGPBPs. In the present work, the OGP binding activity was monitored by competitive binding to [3-125I(Tyr10)]-sOGP and the corresponding complexes were demonstrated on nondenaturing cathodic polyacrylamide gel electrophoresis. We show that OGP binds to both native and activated human plasma alpha 2-macroglobulin (alpha 2M). alpha 2M was also immunoidentified in reduced and nonreduced SDS-polyacrylamide gel electrophoresis of OGP-affinity purified plasma-derived proteins. Immunoreactive OGP was detected in commercial preparations of both forms of alpha 2M; OGP was purified to homogeneity from the commercial preparation of activated alpha 2M. In MC3T3 E1 cells, native alpha 2M, at concentrations < 50 ng/mL, had a substantially increased mitogenic effect in the presence of synthetic, native-like, OGP (sOGP). Similar amounts of activated alpha 2M inhibited the sOGP proliferative effect. These results suggest that the native alpha 2M enhances the immediate availability of OGP to its target cells. Activated alpha 2M may participate in the removal of OGP from the system. 相似文献
2.
Although past research has described changes in the density of the peripheral benzodiazepine receptor in brain and in peripheral organs in response to stressors and steroid hormone exposure, their combined influence had yet to be determined. This study examined the effect of swim-stress as a function of ovarian hormone administration on the binding of an isoquinoline carboxamide derivative, [3H]PK 11195, in brain and peripheral tissues. In olfactory bulb and adrenal gland, stress increased peripheral benzodiazepine receptor density in ovariectomized rats with and without estradiol and progesterone replacement injection, even when compared with unstressed animals treated with hormones, where estradiol + progesterone decreased peripheral benzodiazepine receptor number in olfactory bulb, but estradiol and estradiol + progesterone increased it in adrenal gland. In frontal cortex, stress decreased peripheral benzodiazepine receptor number, an effect that was reversed by estradiol. In hippocampus estradiol decreased peripheral benzodiazepine receptor density in unstressed animals and estradiol + progesterone decreased peripheral benzodiazepine receptor number in unstressed and stressed animals. In cerebellum, stress, estradiol and estradiol + progesterone alone decreased peripheral benzodiazepine receptor density. In uterus of unstressed controls, estradiol + progesterone increased peripheral benzodiazepine receptor density, and stress produced a further increase in steroid-treated females. Stress did not affect peripheral benzodiazepine receptor density in kidney, except in animals that received estradiol + progesterone injections, where swim-stress produced a significant decrease in peripheral benzodiazepine receptor density. Thus, steroid hormones regulate peripheral benzodiazepine receptor density in endocrine organs and brain, and the hormonal state of the organism modifies the peripheral benzodiazepine receptor response to stress in a tissue- and brain region-specific manner, suggesting that the peripheral benzodiazepine receptor may play a pivotal role in an integrated response to stress. 相似文献
3.
On ternary complementary sequences 总被引:1,自引:0,他引:1
Gavish A. Lempel A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1994,40(2):522-526
A pair of real-valued sequences A=(a1,a2,...,aN) and B=(b1,b 2,...,bN) is called complementary if the sum R(·) of their autocorrelation functions RA(·) and RB(·) satisfies R(τ)=RA(τ)+R B(τ)=Σi=1N$ -τaiai+τ+Σj=1 N-τbjbj+τ=0, ∀τ≠0. In this paper we introduce a new family of complementary pairs of sequences over the alphabet α3=+{1,-1,0}. The inclusion of zero in the alphabet, which may correspond to a pause in transmission, leads both to a better understanding of the conventional binary case, where the alphabet is α2={+1,-1}, and to new nontrivial constructions over the ternary alphabet α3. For every length N, we derive restrictions on the location of the zero elements and on the form of the member sequences of the pair. We also derive a bound on the minimum number of zeros necessary for the existence of a complementary pair of length N over α3. The bound is tight, as it is met by some of the proposed constructions, for infinitely many lengths 相似文献
4.
In this work, we consider the problem of solving , , where b
(k+1) = f(x
(k)). We show that when A is a full matrix and , where depends on the specific software and hardware setup, it is faster to solve for by explicitly evaluating the inverse matrix A
−1 rather than through the LU decomposition of A. We also show that the forward error is comparable in both methods, regardless of the condition number of A. 相似文献
5.
I. Visoly‐Fisher K.D. Dobson J. Nair E. Bezalel G. Hodes D. Cahen 《Advanced functional materials》2003,13(4):289-299
CdTe/CdS solar cells were subjected to heat stress at 200 °C in the dark under different environments (in N2 and in air), and under illumination (in N2). We postulate that two independent mechanisms can explain degradation phenomena in these cells: i) Excessive Cu doping of CdS: Accumulation of Cu in the CdS with stress, in the presence of Cl, will increase the photoconductivity of CdS. With limited amounts of Cu in CdS, this does NOT affect the photovoltaic behavior, but explains the crossover of light/dark current–voltage (J–V) curves. Overdoping of CdS with Cu can be detrimental to cell performance by creating deep acceptor states, acting as recombination centers, and compensating donor states. Under illumination, the barrier to Cu cations at the cell junction is reduced, and, therefore, Cu accumulation in the CdS is enhanced. Recovery of light‐stress induced degradation in CdTe/CdS cells in the dark is explained by dissociation of the acceptor defects. ii) Back contact barrier: Oxidation of the CdTe back surface in O2/H2O‐containing environment to form an insulating oxide results in a back‐contact barrier. This barrier is expressed by a rollover in the J–V curve. Humidity is an important factor in air‐induced degradation, as it accelerates the oxide formation. Heat treatment in the dark in inert atmosphere can stabilize the cells against certain causes of degradation, by completing the back contact anneal. 相似文献
6.
A new approach to the joint selection of primary and secondary routes in a network with unreliable components is presented. The mathematical model captures the changes in the operational characteristics of the network as it adapts to failures. Lagrangian relaxation and subgradient optimization techniques are used to obtain good heuristic solutions to the problem, as well as lower bounds to be used as benchmarks against which the quality of the solution is assessed. Results of numerical experiments are reported, and directions for further enhancements of the model are discussed 相似文献
7.
8.
LEOS communication systems are rapidly moving from dream to reality. When operational, the LEOS systems can offer mobile and
fixed‐site communications between any two points on the globe. Yet, many LEOS system design issues remain unresolved. Some
of the planned systems, such as Iridium and Teledesic, rely on intersatellite communication to provide space based routing
from origin to destination while others, like Globalstar, use ground based routing. This paper investigates the effect of
satellite crosslink design on user‐to‐user delay and satellite power consumption. Delay is an important measure of quality
of service and may have a significant impact on system revenues. The results indicate that the choice of crosslink architecture
has a large effect on user‐to‐user delay. In a polar orbit LEOS system, there will be two seams from pole to pole 180° apart,
where satellites in orbits on opposing sides of the seam move in opposite directions. It is demonstrated that the ability
to maintain communication links across the seams is of relatively minor importance for user‐to‐user delay. Finally, the choice
of crosslink pattern and crosslink antenna technology is shown to have no significant impact on satellite power consumption
or on LEOS system capacity.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Bulletin of Engineering Geology and the Environment - Coreholes can be used to determinein situ fracture (or joint) system, state of stress, and rock permeability by utilizing only one set of... 相似文献
10.
Eleven samples of illites were separated from limestones which have undergone variable degrees of metamorphism and analyzed by X-ray diffraction to give twelve orders of the (001) reflections. The observed structure factors were calculated with a computer and compared to calculated structure factors of a hypothetical model through a process of “refinement”. The variable parameters in the process of “refinement” were: the distance of OH, Si and O from the center of the unit cell, the temperature coefficient, and the amount of K+ and Fe+3 in the lattice of the unit cell. A one-dimensional Fourier synthesis calculated the electron densities along the C axis within the unit cell. The percent 2M polymorph in the illites, as well as the oxygen isotope ratio of the limestones from which the illites were extracted, was also calculated. These two parameters were used as indicators of the degree of metamorphism of the samples collected. There is an inverse correlation between the proportion of 2M polymorphs and the O18/O16 ratio. There is no clear correlation between the amount of K+ in the lattice and the degree of metamorphism of the samples. There is an increase of Fe+3 substituted in the octahedral layer of the illite, with an increased degree of metamorphism of the limestones. 相似文献