Rydberg-induced solitons: three-dimensional self-trapping of matter waves

We propose a scheme for the creation of stable three-dimensional bright solitons in Bose-Einstein condensates, i.e., the matter-wave analog of so-called spatiotemporal "light bullets." Off-resonant dressing to Rydberg nD states is shown to provide nonlocal attractive interactions, leading to self-trapping of mesoscopic atomic clouds by a collective excitation of a Rydberg atom pair. We present detailed potential calculations and demonstrate the existence of stable solitons under realistic experimental conditions by means of numerical simulations.

Rotating soliton solutions in nonlocal nonlinear media

We discuss generic properties of rotating nonlinear wave solutions, the so called azimuthons, in nonlocal media. Variational methods allow us to derive approximative values for the rotating frequency, which is shown to depend crucially on the nonlocal response function. Further on, we link families of azimuthons to internal modes of classical non-rotating stationary solutions, namely vortex and multipole solitons. This offers an exhaustive method to identify azimuthons in a given nonlocal medium.

Solitons in one-dimensional nonlinear Schrödinger lattices with a local inhomogeneity

In this paper we analyze the existence, stability, dynamical formation, and mobility properties of localized solutions in a one-dimensional system described by the discrete nonlinear Schrödinger equation with a linear point defect. We consider both attractive and repulsive defects in a focusing lattice. Among our main findings are (a) the destabilization of the on-site mode centered at the defect in the repulsive case, (b) the disappearance of localized modes in the vicinity of the defect due to saddle-node bifurcations for sufficiently strong defects of either type, (c) the decrease of the amplitude formation threshold for attractive and its increase for repulsive defects, and (d) the detailed elucidation as a function of initial speed and defect strength of the different regimes (trapping, trapping and reflection, pure reflection, and pure transmission) of interaction of a moving localized mode with the defect.

Nonlocal stabilization of nonlinear beams in a self-focusing atomic vapor

We show that ballistic transport of optically excited atoms in an atomic vapor provides a nonlocal nonlinearity which stabilizes the propagation of vortex beams and higher order modes in the presence of a self-focusing nonlinearity. Numerical experiments demonstrate stable propagation of higher order nonlinear states (dipole, vortices, and rotating azimuthons) over a hundred diffraction lengths, before dissipation leads to decay of these structures.

[Intraalveolar hemorrhage as a cause of acute respiratory failure in catastrophic antiphospholipid syndrome]

We report the case of a catastrophic antiphospholipid syndrome (CAPS), which developed without a known cause in a 38-year old man. Primary antiphospholipid syndrome was diagnosed one year earlier. Clinical manifestations of CAPS were dominated by diffuse intraalveolar haemorrhage leading to acute respiratory failure and renal failure. Syndrome of multiorgan failure developed despite the treatment with plasmapheresis, high doses of glycocorticosteroids, an intravenous gammaglobulins. The patient died 6 weeks after the admission.

Solitons in nonlocal nonlinear media: exact solutions

We investigate the propagation of one-dimensional bright and dark spatial solitons in a nonlocal Kerr-like media, in which the nonlocality is of general form. We find an exact analytical solution to the nonlinear propagation equation in the case of weak nonlocality. We study the properties of these solitons and show their stability.

Dynamics of formation and interaction of photorefractive screening solitons

An experimental and numerical investigation of the dynamical, time-dependent effects accompanying the formation and interaction of two-dimensional spatial screening solitons in a photorefractive strontium barium niobate crystal is performed. These effects include initial diffraction, collapse to the soliton shape, the oscillation of beam diameters, beam bending, and the rotation, twisting, and turning of soliton pairs. The dynamics of complex spiraling of two incoherent solitons is considered in more detail.

Asymmetric partially coherent solitons in saturable nonlinear media

We investigate theoretically properties of partially coherent solitons in optical nonlinear media with slow saturable nonlinearity. We have found numerically that such a medium can support spatial solitons which are asymmetric in shape and are composed of only a finite number of modes associated with the self-induced waveguide. It is shown that these asymmetric spatial solitons can propagate many diffraction lengths without changes, but that collisions change their shape and may split them apart.

Partially coherent solitons of variable shape in a slow Kerr-like medium: exact solutions

We carry out a theoretical investigation of the properties of partially coherent solitons for media which have a slow Kerr-like nonlinearity. We find exact solutions of the Nth-order Manakov equations in a general form. These describe partially coherent solitons (PCSs) and their collisions. In fact, the exact solutions allow us to analyze important properties of PCSs such as stationary profiles of the spatial beams and effects resulting from their collisions. In particular, we find, analytically, the number of parameters that control the soliton shape. We present profiles which are symmetric as well as those which are asymmetric. We also find that collisions allow the profiles to remain stationary but cause their shapes to change.

Annihilation of photorefractive solitons

We investigate experimentally the interaction of two-dimensional solitary beams in photorefractive strontium barium niobate crystal. We show that simultaneous collision of many solitons can result in complete annihilation of some of them. This effect depends on the relative phases of the solitons and may be useful for application in the formation of multiport waveguide junctions.

Fusion and birth of spatial solitons upon collision

We study experimentally the collision of photorefractive screening solitons in a strontium barium niobate crystal. Depending on the relative phase of the solitons and their intersecting angle, such effects as soliton birth, energy exchange, and soliton fusion have been observed.

Multimode structure of bright and dark vector solitons in photorefractive media

We study coupled solitary waves in a photorefractive medium. For a special orientation of a cubic photorefractive crystal, stationary wave propagation in the form of coupled dark and bright solitons is possible. We classify these solutions and study their stability, using numerical simulations.

Instabilities of dark solitons

Optical dark solitons described by the generalized nonlinear Schrödinger equation are discussed, and the criterion of soliton instability is presented. This analytical criterion is confirmed numerically for an exactly solvable model of nonlinear saturation.

Wave mixing and beam profile control in a photorefractive waveguide

Photorefractive wave mixing in a waveguide geometry with nonguided external pumps has been studied experimentally and theoretically. Guided beam amplification has been obtained in an iron-doped lithium niobate waveguide. Additionally, photorefractive grating couplers that allow the transverse profile of the decoupled guided beam to be controlled are demonstrated.

Solitonlike optical switching in a circular fiber array

We show numerically that a solitonlike propagation behavior in a self-focusing nonlinear fiber array can be used for efficient optical switching. Initial phase modulation of only five fibers is used for switching control.

Thrombinogenesis and its pharmacological modulation in atherosclerosis

Appearance of thrombin in circulating blood can be monitored in the clinical setting by measuring specific thrombin markers, such as fibrinopeptide A, thrombin-antithrombin III or prothrombin fragment 1 + 2. In myocardial infarction monitoring of thrombin activity is of growing clinical interest. High levels of thrombin markers indicate an increased risk to a patient with myocardial infarction. Persistent, high thrombin marker levels, despite heparin anticoagulation, point to ongoing thrombin generation that may necessitate more anticoagulation, increased antiplatelet treatment, angioplasty or, in the future, use of new antithrombotic drugs. Recently, new sensitive methods have been developed to study the reaction of thrombin generation in clotting blood. These methods permitted to demonstrate that, aspirin, contrary to several other antiplatelet drugs, delay the process of thrombin formation. Continuous dampening of thrombin formation by aspirin might be one of the mechanisms responsible for its prophylactic and therapeutic efficacy. Hypercholesterolemic subjects might profit less than others from this type of treatment, since aspirin dampening effects are not so evident in hypercholesterolemia.

[Treatment of respiratory tract infections with pefloxacin]

Pefloxacin, a 4-quinolone derivative, was administered in the dose of 800-1200 mg for the mean of 12 days to 24 patients with respiratory tract infection complicating chronic bronchial asthma or chronic obstructive lung disease. Patients with positive sputum culture and bacteria sensitive to pefloxacin were included in the study. Total eradication of the offending microorganisms was achieved in 54% of patients, and partial--in the next 20%. A poor efficacy of pefloxacin against Streptococcus species has been confirmed. In a few cases we have observed the development of resistance of isolated bacteria to pefloxacin during the course of treatment.

[Netilmicin in the treatment of bacterial respiratory tract infections]

Netilmicin - a semisynthetic aminoglycoside - was administered to 33 patients with the acute or chronic lower respiratory tract or pulmonary infections in a daily dose of 5 mg/kg body weight for 10 days. A principle criterium of patients classification to netilmicin therapy were sensitive bacterial strains either in sputum or in BAL liquid. A significant clinical improvement was noted in 88% of the treated patients. However, elimination of pathogens from the sputum was achieved only in 52% of these patients. No improvement was observed in 4% of the treated patients. No adverse reactions were noted. Netilmicin proved safe and effective antibacterial agent in patients with respiratory infections.

Prostacyclin for ischemic ulcers in peripheral arterial disease. A random assignment, placebo controlled study

A 72 h infusion of prostacyclin or placebo was given into femoral artery as a treatment for ischemic ulcers in 30 patients with peripheral arterial disease. Patients were well matched for age, sex, type and localization of disease, rest pain, number and area of ulcers, calf blood flow and previous sympathectomies. They had no diabetes mellitus, gangrene or marked aorto-iliac involvement. Six weeks after the infusion there was a significant difference in ulcer area between the two groups (p less than 0.02, t unpaired test): mean ulcer area decreased (p less than 0.02, t paired test) in the prostacyclin-treated group, but not in the placebo group (p greater than 0.05, t paired test). Thus, intra-arterial infusion of prostacyclin promotes healing of ischemic ulcers in non-diabetic patients with peripheral arterial disease without gangrene.

Treatment with prostacyclin of various forms of spontaneous angina pectoris not responding to placebo

We studied the effects of prostacyclin on the frequency, duration and severity of ischemic attacks in spontaneous angina. Twenty-seven patients who did not respond to 48 hours infusion of placebo, received after a two-day observation period, 48 hours infusion of prostacyclin at an average rate of 4.0 ng/kg/min. Prostacyclin decreased number of ischemic attacks in only one of four patients with Prinzmetal angina, and was without any effect in five other patients whose attacks were associated with increase in blood pressure and heart rate. However, in 12 of 18 patients with coronary atherosclerosis, whose attacks were characterized by ST-segment depression without increase in heart rate or blood pressure, and often occurred at night, prostacyclin consistently diminished both frequency of anginal attacks and nitroglycerin consumption. This improvement lasted from 10 days to 3 months. Healing of endothelial damage by prostacyclin could explain the favorable therapeutic response in this subset of patients with spontaneous angina.