746 research outputs found
Finite Element Analysis of the Displacement Adjustment Scheme for Column Bases of a 10000 m3 Spherical Tank During Whole-body Heat Treatment
AbstractThe stress of spherical tank and displacement of column bases were calculated by finite element method, considering the uneven gravity loads on support columns which was caused by manufacturing and setting errors. The preliminary displacement adjustment scheme for column bases was made, according to the safety range of column bases displacement which was determined by the maximum stress restricted by allowable stress at the set heat treatment temperatures. The final scheme was made after checking the preliminary scheme. The method of making adjustment scheme of column bases for a 10000m3 spherical tank during the whole-body heat treatment may provide a reference for other large spherical tank
Why Quantum Bit Commitment And Ideal Quantum Coin Tossing Are Impossible
There had been well known claims of unconditionally secure quantum protocols
for bit commitment. However, we, and independently Mayers, showed that all
proposed quantum bit commitment schemes are, in principle, insecure because the
sender, Alice, can almost always cheat successfully by using an
Einstein-Podolsky-Rosen (EPR) type of attack and delaying her measurements. One
might wonder if secure quantum bit commitment protocols exist at all. We answer
this question by showing that the same type of attack by Alice will, in
principle, break any bit commitment scheme. The cheating strategy generally
requires a quantum computer. We emphasize the generality of this ``no-go
theorem'': Unconditionally secure bit commitment schemes based on quantum
mechanics---fully quantum, classical or quantum but with measurements---are all
ruled out by this result. Since bit commitment is a useful primitive for
building up more sophisticated protocols such as zero-knowledge proofs, our
results cast very serious doubt on the security of quantum cryptography in the
so-called ``post-cold-war'' applications. We also show that ideal quantum coin
tossing is impossible because of the EPR attack. This no-go theorem for ideal
quantum coin tossing may help to shed some lights on the possibility of
non-ideal protocols.Comment: We emphasize the generality of this "no-go theorem". All bit
commitment schemes---fully quantum, classical and quantum but with
measurements---are shown to be necessarily insecure. Accepted for publication
in a special issue of Physica D. About 18 pages in elsart.sty. This is an
extended version of an earlier manuscript (quant-ph/9605026) which has
appeared in the proceedings of PHYSCOMP'9
Three-dimensional Optical-resolution Photoacoustic Microscopy
Optical microscopy, providing valuable insights at the cellular and organelle levels, has been widely recognized as an enabling biomedical technology. As the mainstays of in vivo three-dimensional (3-D) optical microscopy, single-/multi-photon fluorescence microscopy and optical coherence tomography (OCT) have demonstrated their extraordinary sensitivities to fluorescence and optical scattering contrasts, respectively. However, the optical absorption contrast of biological tissues, which encodes essential physiological/pathological information, has not yet been assessable.
The emergence of biomedical photoacoustics has led to a new branch of optical microscopy optical-resolution photoacoustic microscopy (OR-PAM), where the optical irradiation is focused to the diffraction limit to achieve cellular1 or even subcellular level lateral resolution. As a valuable complement to existing optical microscopy technologies, OR-PAM brings in at least two novelties. First and most importantly, OR-PAM detects optical absorption contrasts with extraordinary sensitivity (i.e., 100%). Combining OR-PAM with fluorescence microscopy or with optical-scattering-based OCT (or with both) provides comprehensive optical properties of biological tissues. Second, OR-PAM encodes optical absorption into acoustic waves, in contrast to the pure optical processes in fluorescence microscopy and OCT, and provides background-free detection. The acoustic detection in OR-PAM mitigates the impacts of optical scattering on signal degradation and naturally eliminates possible interferences (i.e., crosstalks) between excitation and detection, which is a common problem in fluorescence microscopy due to the overlap between the excitation and fluorescence spectra.
Unique for optical absorption imaging, OR-PAM has demonstrated broad biomedical applications since its invention, including, but not limited to, neurology, ophthalmology, vascular biology, and dermatology. In this video, we teach the system configuration and alignment of OR-PAM as well as the experimental procedures for in vivo functional microvascular imaging
Evaluation in vitro de lâactivitĂ© des Ă©corces de tige de Anogeissus leiocarpus (DC) Guill. et Perr. (Combretaceae) sur des bactĂ©ries responsables de maladies courantes en Afrique et criblage phytochimique
Les bactĂ©ries sont Ă lâorigine de rĂ©el problĂšme de santĂ© publique Ă cause de leur implication dans de nombreuses maladies. Leur rĂ©sistance aux antibiotiques est devenue lâun des problĂšmes les plus importants dans la lutte contre les maladies infectieuses dans le monde. Lâobjectif de ce travail est dâĂ©valuer lâactivitĂ© antibactĂ©rienne des extraits hexanique, mĂ©thanolique 70% (v/v) et aqueux des Ă©corces de tige de Anogeissus leiocarpus (DC) Guill. et Perr. (Combretaceae), une plante mĂ©dicinale de la flore ivoirienne, contre les bactĂ©ries des genres Staphylococcus, Pseudomonas et les entĂ©robactĂ©ries (Shigella sp., Salmonella Typhimurium, Escherichia coli et Proteus mirabilis) par la mĂ©thode de diffusion en milieu gĂ©losĂ© dans des cupules et la mĂ©thode de macro-dilution en milieu liquide . Les extraits aqueux et mĂ©thanolique 70% (v/v) ont Ă©tĂ© retenus pour la dĂ©termination des paramĂštres antibactĂ©riens (CMI et CMB), en raison de leurs activitĂ©s sur lâensemble des bactĂ©ries sĂ©lectionnĂ©es. Par ailleurs, une analyse qualitative par chromatographie sur couche mince (CCM), effectuĂ©e sur les diffĂ©rents extraits, a permis de dĂ©tecter plusieurs groupes de composĂ©s chimiques parmi lesquels les saponosides, les tanins, les flavonoĂŻdes, les polyphĂ©nols, les alcaloĂŻdes et les sesquiterpĂšnes dont des effets antibactĂ©riens sont connus. Les CMI obtenues, sont comprises entre 0,7 ± 0,0 et 12,5 ± 0,0 mg/ml. Quant aux CMB, elles varient de 3,1 ± 0,0 Ă 25,0 ± 0,0 mg/ml. Ce travail justifie lâutilisation traditionnelle de Anogeissus leiocarpus dans le traitement de diverses pathologies et plus particuliĂšrement celles dâorigine bactĂ©rienne.Mots clĂ©s : AntibactĂ©rienne, Anogeissus leiocarpus, flore ivoirienne, analyse qualitative
Identification of essential histidine residues in a recombinant alpha-amylase of thermophilic and alkaliphilic Bacillus sp strain TS-23
To understand the structure-function relationships of a truncated Bacillus sp. strain TS-23 alpha-amylase, each of His-137, His-191, His-239, His-269, His-305, His-323, His-361, His-436, and His-475 was replaced with leucine. The molecular masses of the purified wild-type and mutant enzymes were approximately 54 kDa. The specific activity of His323Leu and His436Leu was decreased by more than 52%, while His239Leu, His305Leu, and His475Leu showed activity similar to that of the wild-type enzyme. As compared with the wild-type enzyme, His323Leu and His436Leu exhibited a 62% decrease in the value of k(cat)/K-m. Alterations in His-191, His-239, His-305, and His-475 did not cause a significant change in the K-m or k(cat) values. At 70degreesC, a decreased half-life was observed in His436Leu. These results indicate that His-137, His-269, and His-361 of Bacillus sp. strain TS-23 alpha-amylase are important for proper catalytic activity and that His-436 may contribute to the thermostability of the enzyme
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays
By analyzing about 33 data sample collected at and around 3.773
GeV with the BES-II detector at the BEPC collider, we directly measure the
branching fractions for the neutral and charged inclusive semimuonic decays
to be and , and determine the ratio of the two branching
fractions to be
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
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