2,256 research outputs found
Utjecaj sedimentne reologije i antiklinalne bazenske topografije na karakteristike gibanja tla
A very peculiar damage patterns have been reported during Northridge earthquake of 1994 and Nisqually earthquake of 2001 caused by basement focusing. Similarly, basement de-focusing may cause lesser damage than the expectations but such inferences have not been reported. Further, as far as we know, no theoretical study related to de-focusing effects of anticlinal basement topography (ABT) is available in the literature. In order to fulfill this gap, this article presents the combined effects of sediment rheology and ABT on the SH-and SV-waves characteristics. The simulated results revealed an increase of de-amplification factors with distance travelled in basin above the ABT. The computed snapshots also confirmed amplitude de-amplification, diffraction and mode conversion of SV-wave. Elastic response revealed that the de-amplification factors caused by ABT were not frequency dependent. The average spectral de-amplification factors were more or less same for both the waves even after strong mode conversion of SV-wave at the lower part of ABT. Based on simulated results, it was inferred that the incorporation of effects of ABT in seismic hazard assessment is equally important as that of synclinal asement topography (SBT) effects for cost effective earthquake engineering.Fokusiranje potresnih valova topografijom pripadnih strukturnih bazena uzrokova¬lo je neobičnu razdiobu šteta koja je opažena nakon potresa u Northridgeu 1994. i Nisqualliyu 2001. godine. U skladu s time moguće je očekivati i defokusiranje valova potresa antiklinalnom bazenskom topografijom (ABT), ali, koliko nam je poznato, do sada nije objavljena niti jedna studija koja bi se bavila tim problemom. Kako bismo ispunili tu prazninu, ovdje smo razmotrili kombinirani utjecaj reologije sedimenata i ABT na svojstva SH i SV-valova. Rezultati simulacije ukazuju na povećanje deamplifikacije s udaljenosti koju valovi prevale u bazenu iznad ABT. Sintetizirani seizmogrami također potvrđuju deamplifikaciju amplituda, difrakciju te konverziju modova u slučaju SV-valova. Deam¬plifikacija ne ovisi o frekvenciji. Prosječni spektralni faktori deamplifikacije su gotovo jednaki za obje vrste valova, čak i nakon jake konverzije SV-valova u donjim dijelovima ABT. Na temelju simulacija zaključeno je da su efekti ABT u procjeni potresne opas¬nosti za učinkovito porotupotresno projektiranje jednako važni kao i efekti sinklinalne topografije (SBT)
A 33 year constancy of the X-ray coronae of AR Lac and eclipse diagnosis of scale height
Extensive X-ray and extreme ultraviolet (EUV) photometric observations of the
eclipsing RS CVn system AR Lac were obtained over the years 1997 to 2013 with
the Chandra X-ray Observatory Extreme Ultraviolet Explorer. During primary
eclipse, HRC count rates decrease by ~40%. A similar minimum is seen during one
primary eclipse observed by EUVE but not in others owing to intrinsic source
variability. Little evidence for secondary eclipses is present in either the
X-ray or EUV data, reminiscent of earlier X-ray and EUV observations. Primary
eclipses allow us to estimate the extent of a spherically symmetric corona on
the primary G star of about 1.3Rsun, or 0.86Rstar, and indicate the G star is
likely brighter than the K component by a factor of 2-5. Brightness changes not
attributable to eclipses appear to be dominated by stochastic variability and
are generally non-repeating. X-ray and EUV light curves cannot therefore be
reliably used to reconstruct the spatial distribution of emission assuming only
eclipses and rotational modulation are at work. Moderate flaring is observed,
where count rates increase by up to a factor of three above quiescence.
Combined with older ASCA, Einstein, EXOSAT, ROSAT and Beppo-SAX observations,
the data show that the level of quiescent coronal emission at X-ray wavelengths
has remained remarkably constant over 33 years, with no sign of variation due
to magnetic cycles. Variations in base level X-ray emission seen by Chandra
over 13 years are only ~10%, while variations back to pioneering Einstein
observations in 1980 amount to a maximum of 45% and more typically about 15%.Comment: To appear in the Astrophysical Journa
Sentiment analysis on predicting presidential election: Twitter used case
© Springer Nature Switzerland AG 2020. Twitter is a popular tool for social interaction over the Internet. It allows users to share/post opinions, social media events, and interact with other political and ordinary people. According to Statista web site 2019 statistical report, it estimated that the number of users on Twitter had grown dramatically over the past couple of years to research 300 million users. Twitter has become the largest source of news and postings for key presidents and political figures. Referring to the Trackalytics 2019 report, the recent president of the USA had posted 4,000 tweets per year, which indicates an average of 11–12 tweets per day. Our research proposes a technique that extracts and analyzes tweets from blogs and predicts election results based on tweets analysis. It assessed the people’s opinion and studied the impact that might predict the final results for the Turkey 2018 presidential election candidates. The final results were compared with the actual election results and had a high accuracy prediction percentage based on the collected 22,000 tweets
Parity Fluctuations Between Coulomb Blockaded Superconducting Islands
We find that if two superconducting islands of different number parity are
linked by a tunnel junction the unpaired electron in the odd island has a
tendency to tunnel into the even island. This process leads to fluctuations in
time of the number parity of each island, giving rise to a random telegraph
noise spectrum with a characteristic frequency that has an unusual temperature
dependence. This new phenomenon should be observable in a Cooper-pair pump and
similar single-electron tunneling devices.Comment: 4 pages, self-unpacking uuencoded gz-compressed postscript file with
3 figures included; also available at
http://www.lassp.cornell.edu/janko/publications.htm
The Group of 20 transnational policy community: governance networks, policy analysis and think tanks
Effect of Level Statistics on Superconductivity in Ultrasmall Metallic Grains
We examine the destruction of superconducting pairing in metallic grains as
their size is decreased for both even and odd numbers of electrons. This occurs
when the average level spacing d is of the same order as the BCS order
parameter. The energy levels of these grains are randomly distributed according
to random matrix theory, and we must work statistically. We find that the
average value of the critical level spacing is larger than for the model of
equally spaced levels for both parities, and derive numerically the
probabilities that a grain of mean level spacing d shows pairing.Comment: 12 pages, 2 PostScript files, RevTex format, submitted to PR
Stability of Lysozyme in Aqueous Extremolyte Solutions during Heat Shock and Accelerated Thermal Conditions
The purpose of this study was to investigate the stability of lysozyme in aqueous solutions in the presence of various
extremolytes (betaine, hydroxyectoine, trehalose, ectoine, and firoin) under different stress conditions. The stability of
lysozyme was determined by Nile red Fluorescence Spectroscopy and a bioactivity assay. During heat shock (10 min at
70uC), betaine, trehalose, ectoin and firoin protected lysozyme against inactivation while hydroxyectoine, did not have a
significant effect. During accelerated thermal conditions (4 weeks at 55uC), firoin also acted as a stabilizer. In contrast,
betaine, hydroxyectoine, trehalose and ectoine destabilized lysozyme under this condition. These findings surprisingly
indicate that some extremolytes can stabilize a protein under certain stress conditions but destabilize the same protein
under other stress conditions. Therefore it is suggested that for the screening extremolytes to be used for protein
stabilization, an appropriate storage conditions should also be taken into account
Andreev Scattering and the Kondo Effect
We examine the properties of an infinite- Anderson impurity coupled to
both normal and superconducting metals. Both the cases of a quantum dot and a
quantum point contact containing an impurity are considered; for the latter, we
study both one and two-channel impurities. Using a generalization of the
noncrossing approximation which incorporates multiple Andreev reflection, we
compute the impurity spectral function and the linear-response conductance of
these devices. We find generically that the Kondo resonance develops structure
at energies corresponding to the superconducting gap, and that the magnitude of
the resonance at the Fermi energy is altered. This leads to observable changes
in the zero-bias conductance as compared to the case with no superconductivity.Comment: 8 pages, 7 figures; expanded version to appear in PR
Macropinocytosis renders a subset of pancreatic tumor cells resistant to mTOR inhibition
Pancreatic ductal adenocarcinoma (PDAC) features a near-universal mutation in KRAS. Additionally, the tumor suppressor PTEN is lost in ∼10% of patients, and in mouse models, this dramatically accelerates tumor progression. While oncogenic KRAS and phosphatidylinositol 3-kinase (PI3K) cause divergent metabolic phenotypes individually, how they synergize to promote tumor metabolic alterations and dependencies remains unknown. We show that in KRAS-driven murine PDAC cells, loss of Pten strongly enhances both mTOR signaling and macropinocytosis. Protein scavenging alleviates sensitivity to mTOR inhibition by rescuing AKT phosphorylation at serine 473 and consequently cell proliferation. Combined inhibition of mTOR and lysosomal processing of internalized protein eliminates the macropinocytosis-mediated resistance. Our results indicate that mTORC2, rather than mTORC1, is an important regulator of protein scavenging and that protein-mediated resistance could explain the lack of effectiveness of mTOR inhibitors in certain genetic backgrounds. Concurrent inhibition of mTOR and protein scavenging might be a valuable therapeutic approach
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