22,317 research outputs found
Device for suppressing sound and heat produced by high-velocity exhaust jets Patent
Device for adding water to high velocity exhaust jets to reduce velocity, noise, and temperatur
Predicted acoustical performance of the S-IC SOUND suppressor
Scale model acoustical tests for predicting performance of S-IC static test facility sound suppresso
Consequences of Postnatally Elevated Insulin-Like Growth Factor-II in Transgenic Mice: Endocrine Changes and Effects on Body and Organ Growth.
Insulin-like growth factor-II (IGF-II) is an important regulator of
embryonic growth and differentiation, but its function in postnatal life
is unclear. To address this point, we generated transgenic mice harboring
fusion genes in which a human IGF-II complementary DNA is
placed under the transcriptional control of the rat phosphoenolpyruvate
carboxykinase promoter. Transgene-specific messenger RNA was detected
in liver, kidney, and several parts of the gut. Serum IGF-II levels
in transgenic mice were 2-3 times higher than those in controls and
increased after starvation. Circulating IGF-I correlated negatively and
IGF-binding protein-2 (IGFBP-2) positively with IGF-II levels, suggesting
that IGF-I is displaced from IGFBPs by IGF-II and that IGFII
is a major regulator of IGFBP-2. Serum levels of IGFBP-3 and
IGFBP-4 tended to be higher in phosphoenolpyruvate carboxykinase-
IGF-II transgenic mice than in controls, as evaluated by ligand blot
analysis. Starvation reduced serum IGF-I, but increased IGFBP-2 in
transgenic mice more markedly than in controls. Fasting insulin levels
were significantly reduced in transgenic mice, whereas glucose levels
were not influenced by elevated IGF-II. The body growth of 4- and 12-
week-old mice was not significantly influenced by elevated IGF-II, but
transgenic mice displayed increased kidney and testis weight at the age
of 4 weeks, and increased adrenal weight at the age of 12 weeks. Our
results demonstrate that elevated IGF-II in postnatal life has multiple
endocrine consequences and subtle time-specific effects on organ
growth
Negative differential conductance induced by spin-charge separation
Spin-charge states of correlated electrons in a one-dimensional quantum dot
attached to interacting leads are studied in the non-linear transport regime.
With non-symmetric tunnel barriers, regions of negative differential
conductance induced by spin-charge separation are found. They are due to a
correlation-induced trapping of higher-spin states without magnetic field, and
associated with a strong increase in the fluctuations of the electron spin.Comment: REVTEX, 4 pages including 3 figures; Accepted for publication on
Physical Review Letter
Localized low-frequency Neumann modes in 2d-systems with rough boundaries
We compute the relative localization volumes of the vibrational eigenmodes in
two-dimensional systems with a regular body but irregular boundaries under
Dirichlet and under Neumann boundary conditions. We find that localized states
are rare under Dirichlet boundary conditions but very common in the Neumann
case. In order to explain this difference, we utilize the fact that under
Neumann conditions the integral of the amplitudes, carried out over the whole
system area is zero. We discuss, how this condition leads to many localized
states in the low-frequency regime and show by numerical simulations, how the
number of the localized states and their localization volumes vary with the
boundary roughness.Comment: 7 pages, 4 figure
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