Energy Flow Puzzle of Soliton Ratchets

We study the mechanism of directed energy transport for soliton ratchets. The energy flow appears due to the progressive motion of a soliton (kink) which is an energy carrier. However, the energy current formed by internal system deformations (the total field momentum) is zero. We solve the underlying puzzle by showing that the energy flow is realized via an {\it inhomogeneous} energy exchange between the system and the external ac driving. Internal kink modes are unambiguously shown to be crucial for that transport process to take place. We also discuss effects of spatial discretization and combination of ac and dc external drivings.Comment: 4 pages, 3 figures, submitted to PR

Theory of radiation trapping by the accelerating solitons in optical fibers

We present a theory describing trapping of the normally dispersive radiation by the Raman solitons in optical fibers. Frequency of the radiation component is continuously blue shifting, while the soliton is red shifting. Underlying physics of the trapping effect is in the existence of the inertial gravity-like force acting on light in the accelerating frame of reference. We present analytical calculations of the rate of the opposing frequency shifts of the soliton and trapped radiation and find it to be greater than the rate of the red shift of the bare Raman soliton. Our findings are essential for understanding of the continuous shift of the high frequency edge of the supercontinuum spectra generated in photonic crystal fibers towards higher frequencies.Comment: Several misprints in text and formulas corrected. 10 pages, 9 figures, submitted to Phys. Rev.

Analysis of the Degree of Involvement of the Lower Limb Muscles in the Pathological Process in Adolescents with Idiopathic Scoliosis

Background. The problem of the effect of adolescent idiopathic scoliosis on the functional condition of the lower limb muscles is still highlighted insufficiently.Aim. Analysis of the degree of involvement of the lower limb muscles in the pathological process in adolescents with idiopathic scoliosis.Methods. A comparative analysis has been made on the results of examination of 209 adolescents: 25 adolescents with idiopathic scoliosis; 170 normal adolescents; 14 adolescents with congenital scoliosis. The moments of force ofthe lower limb muscles were evaluated using dynamometric stands. Electrophysiological characteristics of the lower limb muscles were registered by the method of global and stimulation electroneuromyography.Results. The decrease in the amplitude of voluntary EMG of the femoral muscles in adolescents with idiopathic and congenital scoliosis is accompanied by dropping the moments of force relative to the values of the control group. The leg muscles are characterized by the preservation of the values of force at the level of normal test subjects under the conditions of the reduced voluntary EMG of high frequency. The amplitude of the M-responses of the indicator muscles and the values of the excitation propagation velocity along the motor fibers were also preserved. There are no statistically significant correlations between the amount of the spine deformity, on the one hand, and the values of asymmetry of the characteristics of the muscles in adolescents with idiopathic scoliosis.Conclusion. In adolescents with idiopathic scoliosis the function of femoral muscles is decreased, and there is no relationship between the amount of the spine deformity and the values of asymmetry of the characteristics of the lower limb muscles. The similar character of muscle function changes in adolescents with idiopathic and congenital scoliosis can testify that the cause of the observed changes is not the disease etiology, but the insufficient level of motor activity

Spatial patterns of dissipative polariton solitons in semiconductor microcavities

We report propagating bound microcavity polariton soliton arrays consisting of multipeak structures either along (x) or perpendicular (y) to the direction of propagation. Soliton arrays of up to five solitons are observed, with the number of solitons controlled by the size and power of the triggering laser pulse. The breakup along the x direction occurs when the effective area of the trigger pulse exceeds the characteristic soliton size determined by polariton-polariton interactions. Narrowing of soliton emission in energymomentum space indicates phase locking between adjacent solitons, consistent with numerical modeling which predicts stable multihump soliton solutions. In the y direction, the breakup originates from inhomogeneity across the wave front in the transverse direction which develops into a stable array only in the solitonic regime via phase-dependent interactions of propagating fronts

Survival of percutaneous implants under various mechanical loading to the bone

Objective The purpose of the study was to explore bone formation processes and survival of percutaneous implants under various external compression of the bone. Material and methods 30 chinchilla male rabbits were used in the study. Tibia of the species was amputated at the upper third and an implant was surgically implanted with the distal part extending through the skin. A compression device was attached to the implant and loading provided to the bone next day after surgery. Five magnitudes of compression loading were used for animals subdivided into 5 groups comprising 6 species in each of the groups. Compression device with constantly maintained loading was attached to the limb during 6 weeks. Results Animals of groups I and II showed no case of the implant falling out throughout the whole period of observation. An implant fell out of the bone in one species of Group III after 56-day implantation, two and four species of Groups IV and V, correspondingly, 3 to 4 days after removal of compression device. Osseointegration was shown to improve in species of Groups I and II due to active angiogenesis in peri-implantation area. Conclusion Therefore loads of greater than 105260 Н/m2 applied to the bone result in decreased implant osseointegration whereas less intensive loading tends to improve osseointegratio

Spatial patterns of dissipative polariton solitons in semiconductor microcavities

We report propagating bound microcavity polariton soliton arrays consisting of multipeak structures either along (x) or perpendicular (y) to the direction of propagation. Soliton arrays of up to five solitons are observed, with the number of solitons controlled by the size and power of the triggering laser pulse. The breakup along the x direction occurs when the effective area of the trigger pulse exceeds the characteristic soliton size determined by polariton-polariton interactions. Narrowing of soliton emission in energy-momentum space indicates phase locking between adjacent solitons, consistent with numerical modeling which predicts stable multihump soliton solutions. In the y direction, the breakup originates from inhomogeneity across the wave front in the transverse direction which develops into a stable array only in the solitonic regime via phase-dependent interactions of propagating fronts.</p

Observation of bright polariton solitons in a semiconductor microcavity

Microcavity polaritons are composite half-light half-matter quasi-particles, which have recently been demonstrated to exhibit rich physical properties, such as non-equilibrium Bose-Einstein condensation, parametric scattering and superfluidity. At the same time, polaritons have some important advantages over photons for information processing applications, since their excitonic component leads to weaker diffraction and stronger inter-particle interactions, implying, respectively, tighter localization and lower powers for nonlinear functionality. Here we present the first experimental observations of bright polariton solitons in a strongly coupled semiconductor microcavity. The polariton solitons are shown to be non-diffracting high density wavepackets, that are strongly localised in real space with a corresponding broad spectrum in momentum space. Unlike solitons known in other matter-wave systems such as Bose condensed ultracold atomic gases, they are non-equilibrium and rely on a balance between losses and external pumping. Microcavity polariton solitons are excited on picosecond timescales, and thus have significant benefits for ultrafast switching and transfer of information over their light only counterparts, semiconductor cavity lasers (VCSELs), which have only nanosecond response time

Renal failure and leukocytosis are predictors of a complicated course of clostridium difficile infection if measured on day of diagnosis

Nonsevere Clostridium difficile infection (CDI) and severe CDI, which carries a higher risk than nonsevere CDI for treatment failure and CDI recurrence, are difficult to distinguish at the time of diagnosis. To investigate the prognostic value of 3 markers of severe CDI suggested by recent guidelines (fever, leukocytosis, and renal failure), we used the database of 2 randomized controlled trials, which contained information for 1105 patients with CDI. Leukocytosis (risk ratio [RR], 2.29; 95% confidence interval [CI], 1.63–3.21) and renal failure (RR, 2.52; 95% CI, 1.82–3.50) were associated with treatment failure. Fever, although associated with treatment failure (RR, 2.45; 95% CI, 1.07–5.61), was rare. Renal failure was the only significant predictor of recurrence (RR, 1.45; 95% CI, 1.05–2.02). Different timing of measurements of leukocyte count and serum creatinine level around the CDI diagnosis led to a different severity classification in many cases. In conclusion, both leukocytosis and renal failure are useful predictors, although timing of measurement is important