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The effect of quantum collapse and revival is a fascinating interference phenomenon. In this paper the phenomenon is demonstrated analytically and numerically for a simple system, a slightly anharmonic Hamiltonian. The initial wave-function is a displaced ground state of a harmonic oscillator. Possible experimental realizations for cold atoms are discussed in detail., 18 pages, 2 figures

Background Human apurinic/apyrimidinic endonuclease APE1 is one of participants of the DNA base excision repair pathway. APE1 processes AP-sites and many other types of DNA damage via hydrolysis of the phosphodiester bond on the 5′ side of the lesion. APE1 also acts as an endoribonuclease, i.e., can cleave undamaged RNA. Methods Using pre-steady-state kinetic analysis we examined the role of certain catalytically important amino acids in APE1 enzymatic pathway and described their involvement in the mechanism of the target nucleotide recognition. Results Comparative analysis of the cleavage efficiency of damaged DNAs containing an abasic site, 5,6-dihydrouridine, or α-anomer of adenosine as well as 3′-5′-exonuclease degradation of undamaged DNA and endonuclease hydrolysis of RNA substrates by mutant APE1 enzymes containing a substitution of an active-site amino acid residue (D210N, N212A, T268D, M270A, or D308A) was performed. Detailed pre–steady-state kinetics of conformational changes of the enzyme and of DNA substrate molecules during recognition and cleavage of the abasic site were studied. Conclusions It was revealed that substitution T268D significantly disturbed initial DNA binding, whereas Asn212 is critical for the DNA-bending stage and catalysis. Substitution D210N increased the binding efficacy and blocked the catalytic reaction, but D308A decreased the binding efficacy owing to disruption of Mg2+ coordination. Finally, the substitution of Met270 also destabilized the enzyme–substrate complex but did not affect the catalytic reaction. Significance It was found that the tested substitutions of the active-site amino acid residues affected different stages of the complex formation process as well as the catalytic reaction.

Contemporary EUS-guided FNA techniques involve the use of a needle, with an air column within the lumen, with or without suction. We describe a novel technique with an aim to improve the quality of the aspirate.To compare a novel "wet suction" technique (WEST) with the conventional FNA technique (CFNAT) of EUS-guided FNA using a 22-gauge FNA needle.Prospective, single-blind, and randomized trial.Two large tertiary-care hospitals.All consecutive adult patients presenting for EUS with possible FNA of solid lesions were offered the chance to participate in the study.All lesions were sampled with the same needle by using alternating techniques. Patients were randomized to the WEST versus the CFNAT for the first pass. If the first pass was made with the WEST, the second pass was made with the CFNAT, and subsequent passes were made in an alternating manner by using the same sequence. All FNAs were performed using 22-gauge needles.Specimen adequacy, cellularity, and blood contamination of EUS-guided FNA aspirates graded on a predefined scale.The WEST yielded significantly higher cellularity in a cell block compared with the CFNAT, with a mean cellularity score of 1.82±0.76 versus 1.45±0.768 (P.0003). The WEST cell block resulted in a significantly better specimen adequacy of 85.5% versus 75.2% (P.035). There was no difference in the amount of blood contamination between the 2 techniques.Lack of cross check and grading by a second cytopathologist.The novel WEST resulted in significantly better cellularity and specimen adequacy in cell blocks of EUS-guided FNA aspirate of solid lesions than the CFNAT.

The quantum fidelity was introduced by Peres to study some fingerprints of classically chaotic behavior in the quantum dynamics of the corresponding systems. In the present paper the signatures of classical dynamics near elliptic points and of interactions between particles are characterized for kicked systems. In particular, the period of the fidelity resulting of the interactions is found using analytical and numerical calculations. A mechanism leading to the oscillations with the intermediate period is proposed. It is of a classical origin and results of the interplay between the oscillations of the width of the wave packets and the rotation of their center around the elliptic fixed point.

A spectrophotometric assay for plasmin and plasminogen-derived activity in dairy products was optimised and extended to determine plasmin and plasminogen-derived activity in turbid samples of dairy products. The method was validated by assessing reproducibility, repeatability, level of detection and recovery of plasmin activity in different sample matrices. Plasmin activity in raw milk was not affected by skimming, but decreased by 30% in pasteurised and homogenised whole milk, leading to an underestimation of plasmin activity. The effects of dissociation of plasmin and caseins by epsilon-aminocaproic acid (EACA) plus NaCl on the plasmin activity were investigated. Comparison of pasteurised milk with a micellar casein solution showed that the dissociation of plasmin and caseins on adding EACA and NaCl decreases interference by caseins, but increases inhibition of plasmin with serum-based inhibitory components. The level of detection and repeatability of this method for plasmin activity analysis were improved compared with previous spectrophotometric assays. (C) 2014 Elsevier Ltd. All rights reserved. (Less)

During the rapid filling phase of the heart cycle, the internal volumes of the two ventricular cavities approximately double, while the intraventricular pressures rise typically only by an amount of less than 1 kPa. Such a small pressure increase cannot be the sole driving mechanism for the large inflow of blood associated with ventricular expansion during this period. Instead, the rapid filling phase is to be interpreted as being mediated primarily by the heart recoiling elastically from its contracted state, causing blood to be aspirated rapidly into the ventricles. In order to study the role of this mechanism, elastic finite element (FE) simulations of ventricular expansion were performed, taking into account the large deformations occurring during this period and the effective compressibility of the myocardium due to intramural fluid flow. Thereby, a realistic three-dimensional geometry derived from magnetic resonance imaging (MRI) measurements of both human ventricles was used. To validate our FE analyses, the results were compared with published measurements relating to the rapid filling phase of the human left ventricle. Our study shows that, under normal physiological conditions, ventricular aspiration plays a key role in the ventricular filling process.

During the rapid diastolic filling phase at rest, the ventricles of the human heart double approximately in volume. In order to investigate whether the ventricular filling pressures measured under physiological conditions can give rise to such an extensive augmentation in ventricular volumes, a finite element model of the human right and left ventricles has been developed, taking into account the nonlinear mechanical behavior and effective compressibility of the myocardial tissue. The results were compared with the filling phase of the human left ventricle as extrapolated from measurements documented in the literature. We arrived at the conclusion that the ventricular pressures measured during the rapid filling phase cannot be the sole cause of the rise of the observed ventricular volumes. We rather advocate the assumption that further dilating mechanisms might be part of ventricular activity thus heralding a multiple function of the ventricular muscle body. A further result indicates that under normal conditions the influence of the viscoelasticity of the tissue should not be disregarded in ventricular mechanics.

Tyrosine phosphorylation of phospholipase Cgamma2 (PLCgamma2) is a crucial activation switch that initiates and maintains intracellular calcium mobilization in response to B cell antigen receptor (BCR) engagement. Although members from three distinct families of non-receptor tyrosine kinases can phosphorylate PLCgamma in vitro, the specific kinase(s) controlling BCR-dependent PLCgamma activation in vivo remains unknown. Bruton's tyrosine kinase (Btk)-deficient human B cells exhibit diminished inositol 1,4,5-trisphosphate production and calcium signaling despite a normal inducible level of total PLCgamma2 tyrosine phosphorylation. This suggested that Btk might modify a critical subset of residues essential for PLCgamma2 activity. To evaluate this hypothesis, we generated site-specific phosphotyrosine antibodies recognizing four putative regulatory residues within PLCgamma2. Whereas all four sites were rapidly modified in response to BCR engagement in normal B cells, Btk-deficient B cells exhibited a marked reduction in phosphorylation of the Src homology 2 (SH2)-SH3 linker region sites, Tyr(753) and Tyr(759). Phosphorylation of both sites was restored by expression of Tec, but not Syk, family kinases. In contrast, phosphorylation of the PLCgamma2 carboxyl-terminal sites, Tyr(1197) and Tyr(1217), was unaffected by the absence of functional Btk. Together, these data support a model whereby Btk/Tec kinases control sustained calcium signaling via site-specific phosphorylation of key residues within the PLCgamma2 SH2-SH3 linker.