Smale-Williams solenoids in autonomous system with saddle equilibrium.

We construct an autonomous low-dimensional system of differential equations by replacement of real-valued variables with complex-valued variables in a self-oscillating system with homoclinic loops of a saddle. We provide analytical and numerical indications and argue that the emerging chaotic attractor is a uniformly hyperbolic chaotic attractor of Smale-Williams type. The four-dimensional phase space of the flow consists of two parts: a vicinity of a saddle equilibrium with two pairs of equal eigenvalues where the angular variable undergoes a Bernoulli map, and a region which ensures that the trajectories return to the origin without angular variable changing. The trajectories of the flow approach and leave the vicinity of the saddle equilibrium with the arguments of complex variables undergoing a Bernoulli map on each return. This makes possible the formation of the attractor of a Smale-Williams type in Poincaré cross section. In essence, our model resembles complex amplitude equations governing the dynamics of wave envelops or spatial Fourier modes. We discuss the roughness and generality of our scheme.

Features of a chaotic attractor in a quasiperiodically driven nonlinear oscillator.

Transition to chaos via the destruction of a two-dimensional torus is studied numerically using an example of the Hénon map and the Toda oscillator under quasiperiodic forcing and also experimentally using an example of a quasi-periodically excited RL-diode circuit. A feature of chaotic dynamics in these systems is the fact that the chaotic attractor in them has an additional zero Lyapunov exponent, which strictly follows from the structure of mathematical models. In the process of research, the influence of feedback is studied, in which the frequency of one of the harmonics of external forcing becomes dependent on a dynamic variable. Charts of dynamic regimes were constructed, examples of typical oscillation modes were given, and the spectrum of Lyapunov exponents was analyzed. Numerical simulations confirm that chaos resulting from the cascade of torus doubling has a close to the zero Lyapunov exponent, beside the trivial zero exponent.

First Measurement of a Long-Lived π

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π^{+}π^{-} atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 µm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n_{A}^{L}=436_{-61}^{+157}|_{tot}, the lifetime of the 2p state is found to be τ_{2p}=(0.45_{-0.30}^{+1.08}|_{tot})×10^{-11} s, not contradicting the corresponding QED 2p state lifetime τ_{2p}^{QED}=1.17×10^{-11} s. This lifetime value is three orders of magnitude larger than our previously measured value of the π^{+}π^{-} atom ground state lifetime τ=(3.15_{-0.26}^{+0.28}|_{tot})×10^{-15} s. Further studies of long-lived π^{+}π^{-} atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

[Short- and long-term outcomes of laparoscopic interventions in patients with colon cancer: single-centre experience]. / Neposredstvennye i otdalennye rezul'taty laparoskopicheskikh vmeshatel'stv u patsientov s rakom obodochnoi kishki: opyt odnogo tsentra.

OBJECTIVE: To compare short- and long-term outcomes of treatment in patients with colon cancer undergoing laparoscopic and open surgery. MATERIAL AND METHODS: There were 281 patients with colon cancer. All patients underwent open (n=144, 51.2%) or laparoscopic (n=137, 48.8%) procedures. Short- and long-term outcomes of treatment were compared in both groups. RESULTS: There were no significant differences in sex, age, body mass index, location of tumors and tumor differentiation grade in both groups. Conversion was required in 10 (7.2%) cases. The median of duration of surgery was greater for laparoscopic procedures (150 min vs. 130 min; p<0.001). Intraoperative blood loss was significantly less in laparoscopic surgery (100 ml vs. 300 ml; p=0.001). Postoperative mortality was similar (3.5% vs. 2.5%; p=0.5) while incidence of postoperative complications was significantly lower after laparoscopic interventions (13.1% vs. 22.2%; p=0.04). There was earlier recovery of the gastrointestinal tract after laparoscopic procedures (2.1±0.9 days vs. 3.6±1.5 days, respectively; p<0.001). The postoperative hospital-stay was significantly less in the 2nd group (p<0.001). Two-year disease -free and overall survival was similar in both groups. CONCLUSION: Laparoscopic interventions for colon cancer are followed by similar overall and disease-free 2-year survival and better early outcomes.

Observation of π

The observation of hydrogenlike πK atoms, consisting of π^{-}K^{+} or π^{+}K^{-} mesons, is presented. The atoms are produced by 24 GeV/c protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. The breakup (ionization) of πK atoms in the same targets yields characteristic πK pairs, called "atomic pairs," with small relative momenta Q in the pair center-of-mass system. The upgraded DIRAC experiment observed 349±62 such atomic πK pairs, corresponding to a signal of 5.6 standard deviations. This is the first statistically significant observation of the strange dimesonic πK atom.

Exact solutions of the generalized nonlinear Schrödinger equation with distributed coefficients.

A broad class of exact self-similar solutions to the nonlinear Schrödinger equation (NLSE) with distributed dispersion, nonlinearity, and gain or loss has been found describing both periodic and solitary waves. Appropriate solitary wave solutions applying to propagation in optical fibers and optical fiber amplifiers with these distributed parameters have also been studied in detail. These solutions exist for physically realistic dispersion and nonlinearity profiles. They correspond either to compressing or spreading solitary pulses which maintain a linear chirp or to chirped oscillatory solutions. The stability of these solutions has been confirmed by numerical simulations of the NLSE with perturbed initial conditions. These self-similar propagation regimes are expected to find practical application in both optical fiber amplifier systems and in fiber compressors.

Self-similar solutions of the generalized Schrödinger equation with distributed coefficients.

We present approximate but nevertheless highly accurate self-similar solutions to the generalized linear Schrödinger Equation appropriate to the description of pulse propagation in an optical fibre under the influence of distributed dispersion and gain or attenuation. These new similariton solutions apply for any shape of linearly chirped pulse for any dispersion and gain profiles and are indistinguishable from numerically generated solutions in the majority of practical applications.

[Resolution of the fluorescence and absorption spectra of chlorophyll a in the cell into its components]. / Razlozhenie na komponenty spektrov fluorestsentsii i pogloshcheniia khlorofilla a v kletke.

The total number, band widths, absorption and fluorescence peak positions of universal forms of chlorophyll a in vivo were identified by means of computer curve analysis, Stepanov's relation and low temperature derivative spectroscopy. The identified pigment forms are as follows: Chl669(661), Chl676(674), Chl686(680), Chl691(687), Chl697(691), Chl706(698), Chl715(702) Chl726(709), Chl738(715) and Chl750--755(720--724) (the lower index--absorption peak position, the upper one--fluorescence peak position). The O--O electronic transitions vibronic bands energy one of the forms of chlorphyll alpha enumerated above changes for constant equal 140 cm--1.

[Dependence of the intensity of growth processes on the potential difference at the cytoplasmic membrane]. / Zavisimost' intensivnosti rostovykh protsessov ot raznosti potentsialov na tsioplazmaticheskoi membrane.

The growth of organisms is a dynamic process of interrelated fluxes of substances and energy which most often proceeds in the steady-state conditions, the energy-dependent process being predominant. The rate of growth is directly proportional to the potential difference at the plasma membrane, created essentially by a passive influx of energy substance to the cell oxidative system which is a limiting link of its energization. The formation of potential difference is influenced by concentrations of biomass and energy substrate at the plasma membrane, as well as the values of electric capacity of the membrane and rate constants for the electric charge formation and expenditure.

[Possibilities of Holter ECG monitoring in detecting arrhythmia and myocardial ischemia in persons with ischemic heart disease risk factors]. / Vozmozhnosti kholterovskogo monitorirovaniia EKG v vyiavlenii narushenii ritma i ishemii miokarda u lits s faktorami riska ishemicheskoi bolezni serdtsa.

Holter's ECG monitoring was used to investigate 140 males showing no clinical signs of coronary disease, while having 1 to 5 coronary risk factors (hypodynamia, arterial hypertension, smoking, hypercholesterolemia). Supraventricular rhythm disorders were recorded in 86%, and ventricular ones, in 69%. Transitory ST depression was detected in 15% of the cases, appearing in response to physical (90%) of mental (9%) stress or spontaneously in 1%. Ninety percent of ischemic attacks were asymptomatic. Ischemic ECG changes were nearly twice as frequent in patients with 3 to 5 coronary risk factors, as compared to those with 1 or 2 risk factors. It is therefore suggested that asymptomatic coronary disease can be suspected in some of the patients with coronary risk factors. This suspicion is confirmed by positive bicycle ergometric test in 53% of the individuals with changed Holter's ECG monitoring data. Combined use of Holter's ECG monitoring and bicycle ergometry increases twofold the detectability of electrocardiographic abnormalities.

[Moderate arterial hypertension during its natural course and in drug correction]. / Umerennaia arterial'naia gipertoniia pri estestvennom techenii i medikamentoznoi korrektsii.

The clinical and morbid anatomy data on 295 patients with arterial hypertension were examined. Two hundred patients had moderate hypertension with the diastolic pressure under 110 mm Hg. Of these, 103 patients had received rauwolfia drugs and 13 patients had been given hypothiazide in addition. Eighty patients who died before 1953 had not received any specific hypotensive drugs. Early hypotensive therapy of moderate hypertension was noted to promote a decrease in arterial blood pressure to normal and to raise the mean lifespan by 8 years. Furthermore the number of fatal brain strokes and myocardial infarctions decreased almost 2-fold.

Exact self-similar solutions of the generalized nonlinear Schrödinger equation with distributed coefficients.

A broad class of exact self-similar solutions to the nonlinear Schrödinger equation (NLSE) with distributed dispersion, nonlinearity, and gain or loss has been found. Appropriate solitary wave solutions applying to propagation in optical fibers and optical fiber amplifiers with these distributed parameters have also been studied. These solutions exist for physically realistic dispersion and nonlinearity profiles in a fiber with anomalous group velocity dispersion. They correspond either to compressing or spreading solitary pulses which maintain a linear chirp or to chirped oscillatory solutions. The stability of these solutions has been confirmed by numerical simulations of the NLSE.

Self-similar propagation of high-power parabolic pulses in optical fiber amplifiers.

Self-similarity techniques are used to study pulse propagation in a normal-dispersion optical fiber amplifier with an arbitrary longitudinal gain profile. Analysis of the nonlinear Schrödinger equation that describes such an amplifier leads to an exact solution in the high-power limit that corresponds to a linearly chirped parabolic pulse. The self-similar scaling of the propagating pulse in the amplifier is found to be determined by the functional form of the gain profile, and the solution is confirmed by numerical simulations. The implications for achieving chirp-free pulses after compression of the amplifier output are discussed.