53 research outputs found
Uncertainty estimates and L_2 bounds for the Kuramoto-Sivashinsky equation
We consider the Kuramoto-Sivashinsky (KS) equation in one spatial dimension
with periodic boundary conditions. We apply a Lyapunov function argument
similar to the one first introduced by Nicolaenko, Scheurer, and Temam, and
later improved by Collet, Eckmann, Epstein and Stubbe, and Goodman, to prove
that ||u||_2 < C L^1.5. This result is slightly weaker than that recently
announced by Giacomelli and Otto, but applies in the presence of an additional
linear destabilizing term. We further show that for a large class of Lyapunov
functions \phi the exponent 1.5 is the best possible from this line of
argument. Further, this result together with a result of Molinet gives an
improved estimate for L_2 boundedness of the Kuramoto-Sivashinsky equation in
thin rectangular domains in two spatial dimensions.Comment: 17 pages, 1 figure; typos corrected, references added; figure
modifie
Hsp70 in mitochondrial biogenesis
The family of hsp70 (70 kilodalton heat shock protein) molecular chaperones plays an essential and diverse role in cellular physiology, Hsp70 proteins appear to elicit their effects by interacting with polypeptides that present domains which exhibit non-native conformations at distinct stages during their life in the cell. In this paper we review work pertaining to the functions of hsp70 proteins in chaperoning mitochondrial protein biogenesis. Hsp70 proteins function in protein synthesis, protein translocation across mitochondrial membranes, protein folding and finally the delivery of misfolded proteins to proteolytic enzymes in the mitochondrial matrix
AGILE detection of extreme gamma-ray activity from the blazar PKS 1510-089 during March 2009. Multifrequency analysis
We report on the extreme gamma-ray activity from the FSRQ PKS 1510-089
observed by AGILE in March 2009. In the same period a radio-to-optical
monitoring of the source was provided by the GASP-WEBT and REM. Moreover,
several Swift ToO observations were triggered, adding important information on
the source behaviour from optical/UV to hard X-rays. We paid particular
attention to the calibration of the Swift/UVOT data to make it suitable to the
blazars spectra. Simultaneous observations from radio to gamma rays allowed us
to study in detail the correlation among the emission variability at different
frequencies and to investigate the mechanisms at work. In the period 9-30 March
2009, AGILE detected an average gamma-ray flux of (311+/-21)x10^-8 ph cm^-2
s^-1 for E>100 MeV, and a peak level of (702+/-131)x10^-8 ph cm^-2 s^-1 on
daily integration. The gamma-ray activity occurred during a period of
increasing activity from near-IR to UV, with a flaring episode detected on
26-27 March 2009, suggesting that a single mechanism is responsible for the
flux enhancement observed from near-IR to UV. By contrast, Swift/XRT
observations seem to show no clear correlation of the X-ray fluxes with the
optical and gamma-ray ones. However, the X-ray observations show a harder
photon index (1.3-1.6) with respect to most FSRQs and a hint of
harder-when-brighter behaviour, indicating the possible presence of a second
emission component at soft X-ray energies. Moreover, the broad band spectrum
from radio-to-UV confirmed the evidence of thermal features in the optical/UV
spectrum of PKS 1510-089 also during high gamma-ray state. On the other hand,
during 25-26 March 2009 a flat spectrum in the optical/UV energy band was
observed, suggesting an important contribution of the synchrotron emission in
this part of the spectrum during the brightest gamma-ray flare, therefore a
significant shift of the synchrotron peak.Comment: 13 pages, 7 figures, 3 tables. Accepted for publication in Astronomy
and Astrophysic
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The use of freeze-dried allogeneic bone in oral and maxillofacial surgery
Clinical experience with 36 cases using freeze-dried allogeneic bone is reported. Its use in a variety of surgeries, including ridge augmentation, mandibular and maxillary osteotomies, mandibular reconstruction, midfacial advancement and obliteration of cystic cavities was associated with a minimal incidence of complications and excellent host acceptance. The collection of bone under sterile conditions and the rigid criteria for the tissue banking process are shown to account for this host compatibility and low complication rate. The physiochemical and biologic properties of freeze-dried allogeneic bone are discussed. This material provides unique practical advantages leading to long-term stability
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