Reexamination of helium fine structure

In order to explain discrepancies between theoretical predictions and experimental data for the helium fine structure, we check and recalculate all theoretical contributions up to orders m\alpha^7 and m^2/M\alpha^6. The previous result for the m\alpha^7 correction is improved by a much more accurate calculation of relativistic corrections to the Bethe logarithm. The theoretical values of the 2^3P_0-2^3P_1 and 2^3P_1-2^3P_2 fine structure intervals in helium are, correspondingly, \nu_{01} = 29616946.2(1.6) kHz and \nu_{12} = 2291177.3(1.6) kHz, with the uncertanties being due to higher-order effects. For the small interval \nu_{12}, the theoretical value agrees with the experimental data, whereas for the large interval \nu_{01}, a discrepancy of about 3 standard deviations is present.Comment: 19 page

Cardiomyocyte stiffness in diastolic heart failure

Background - Heart failure with preserved left ventricular (LV) ejection fraction (EF) is increasingly recognized and usually referred to as diastolic heart failure (DHF). Its pathogenetic mechanism remains unclear, partly because of a lack of myocardial biopsy material. Endomyocardial biopsy samples obtained from DHF patients were therefore analyzed for collagen volume fraction (CVF) and sarcomeric protein composition and compared with control samples. Single cardiomyocytes were isolated from these biopsy samples to assess cellular contractile performance. Methods and Results - DHF patients (n=12) had an LVEF of 71 ± 11%, an LV end-diastolic pressure (LVEDP) of 28±4 mm Hg, and no significant coronary artery stenoses. DHF patients had higher CVFs (7.5±4.0%, P<0.05) than did controls (n=8, 3.8±2.0%), and no conspicuous changes in sarcomeric protein composition were detected, Cardiomyocytes, mechanically isolated and treated with Triton X-100 to remove all membranes, were stretched to a sarcomere length of 2.2 μm and activated with solutions containing varying [Ca2+]. Compared with cardiomyocytes of controls, cardiomyocytes of DHF patients developed a similar total isometric force at maximal [Ca2+], but their resting tension (Fpassive) in the absence of Ca2+ was almost twice as high (6.6±3.0 versus 3.5±1.7 kN/m2, P<0.001). F passive and CVF combined yielded stronger correlations with LVEDP than did either alone. Administration of protein kinase A (PKA) to DHF cardiomyocytes lowered Fpassive to control values. Conclusions - DHF patients had stiffer cardiomyocytes, as evident from a higher F passive, at the same sarcomere length. Together with CVF, F passive determined in vivo diastolic LV dysfunction. Correction of this high Fpassive by PKA suggests that reduced phosphorylation of sarcomeric proteins is involved in DHF

Synthesis and Characterization of Periodic Polypeptides Containing Repeating —(AlaGly)_xGluGly— Sequences

We have expressed in E. coli a series of periodic polypeptides represented by sequence 1. Our objective has been an understanding of the role of chemical sequence in determining the chain folding behavior of periodic macromolecules. Molecular organization has been examined by infrared spectroscopy and ^1H and ^(13)C NMR methods and a preliminary model of the folded structure has been developed

Dynamics of Sleep-Wake Transitions During Sleep

We study the dynamics of the awakening during the night for healthy subjects and find that the wake and the sleep periods exhibit completely different behavior: the durations of wake periods are characterized by a scale-free power-law distribution, while the durations of sleep periods have an exponential distribution with a characteristic time scale. We find that the characteristic time scale of sleep periods changes throughout the night. In contrast, there is no measurable variation in the power-law behavior for the durations of wake periods. We develop a stochastic model which agrees with the data and suggests that the difference in the dynamics of sleep and wake states arises from the constraints on the number of microstates in the sleep-wake system.Comment: Final form with some small corrections. To be published in Europhysics Letters, vol. 57, issue no. 5, 1 March 2002, pp. 625-63

Projectile Coherence Effects in Simple Atomic Systems

Recent studies of projectile coherence effects in ion-atom collisions are presented. For intermediate-energy proton collisions an extensive literature provides strong support for the importance of such effects. In this regime coherence effects are now used as a tool to study the few-body dynamics very sensitively. In contrast, for high-energy ion impact the literature is much sparser and here an important role of coherence effects cannot be regarded as being established. In this context, a recent claim that in COLTRIMS experiments the coherence properties are determined only by the target beam is rebutted

Repetitive levosimendan treatment in the management of advanced heart failure

Inotropes may be an appropriate treatment for patients with advanced heart failure (AdHF) who remain highly symptomatic despite optimized standard therapies. Objectives for inotrope use in these situations include relief of symptoms and improvement of quality of life, and reduction in unplanned hospitalizations and the costs associated with such episodes. All of these goals must be attained without compromising survival. Encouraging findings with intermittent cycles of intravenous levosimendan have emerged from a range of exploratory studies and from three larger controlled trials (LevoRep, LION-HEART, and LAICA) which offered some evidence of clinical advantage. In these settings, however, obtaining statistically robust data may prove elusive due to the difficulties of endpoint assessment in a complex medical condition with varying presentation and trajectory. Adoption of a composite clinical endpoint evaluated in a hierarchical manner may offer a workable solution to this problem. Such an instrument can explore the proposition that repetitive administration of levosimendan early in the period after discharge from an acute episode of worsening heart failure may be associated with greater subsequent clinical stability vis-à-vis standard therapy. The use of this methodology to develop a 'stability score' for each patient means that all participants in such a trial contribute to the overall outcome analysis through one or more of the hierarchical endpoints; this has helpful practical implications for the number of patients needed and the length of follow-up required to generate endpoint data. The LeoDOR study (NCT03437226), outlined in this review, has been designed to explore this new approach to outcome assessment in AdHF

Peculiar properties of the cluster-cluster interaction induced by the Pauli exclusion principle

Role of the Pauli principle in the formation of both the discrete spectrum and multi-channel states of the binary nuclear systems composed of clusters is studied in the Algebraic Version of the resonating-group method. Solutions of the Hill-Wheeler equations in the discrete representation of a complete basis of the Pauli-allowed states are discussed for 4He+n, 3H+3H, and 4He+4He binary systems. An exact treatment of the antisymmetrization effects are shown to result in either an effective repulsion of the clusters, or their effective attraction. It also yields a change in the intensity of the centrifugal potential. Both factors significantly affect the scattering phase behavior. Special attention is paid to the multi-channel cluster structure 6He+6He as well as to the difficulties arising in the case when the two clustering configurations, 6He+6He and 4He+8He, are taken into account simultaneously. In the latter case the Pauli principle, even in the absence of a potential energy of the cluster-cluster interaction, leads to the inelastic processes and secures an existence of both the bound state and resonance in the 12Be compound nucleus.Comment: 17 pages, 14 figures, 1 table; submitted to Phys.Rev.C Keywords: light neutron-rich nuclei, cluster model