Experimental demonstration of optical stochastic cooling

Particle accelerators and storage rings have been transformative instruments of discovery, and, for many applications, innovations in particle-beam cooling have been a principal driver of that success¹. Stochastic cooling (SC), one of the most important conceptual and technological advances in this area^2–6, cools a beam through granular sampling and correction of its phase-space structure, thus bearing resemblance to a ‘Maxwell’s demon’. The extension of SC from the microwave regime up to optical frequencies and bandwidths has long been pursued, as it could increase the achievable cooling rates by three to four orders of magnitude and provide a powerful tool for future accelerators. First proposed nearly 30 years ago, optical stochastic cooling (OSC) replaces the conventional microwave elements of SC with optical-frequency analogues and is, in principle, compatible with any species of charged-particle beam^7,8. Here we describe a demonstration of OSC in a proof-of-principle experiment at the Fermi National Accelerator Laboratory’s Integrable Optics Test Accelerator^9,10. The experiment used 100-MeV electrons and a non-amplified configuration of OSC with a radiation wavelength of 950 nm, and achieved strong, simultaneous cooling of the beam in all degrees of freedom. This realization of SC at optical frequencies serves as a foundation for more advanced experiments with high-gain optical amplification, and advances opportunities for future operational OSC systems with potential benefit to a broad user community in the accelerator-based sciences.

Stochastic cooling at optical frequencies is demonstrated in an experiment at the Fermi National Accelerator Laboratory’s Integrable Optics Test Accelerator, substantially increasing the bandwidth of stochastic cooling compared with conventional systems.

Entropic characterization of the coil-stretch transition of polymers in random flows

Polymer molecules in a flow undergo a coil-stretch phase transition on an increase of the velocity gradients. Model-independent identification and characterization of the transition in a random flow has been lacking so far. Here we suggest to use the entropy of the extension statistics as a proper measure due to strong fluctuations around the transition. We measure experimentally the entropy as a function of the local Weisenberg number and show that it has a maximum, which identifies and quantifies the transition. We compare the new approach with the traditional one based on the theory using either linear Oldroyd-B or nonlinear finite extensible nonlinear elastic polymer models.

PRO-INFLAMMATORY EFFECTS OF EXPERIMENTAL HYPERTHYROIDISM IN COLON OF MICE (IMMUNOHISTOCYTOCHEMICAL STUDY)

Thyroid hormones can exert responses in various immune cells affecting several inflammation-related processes. The interactions between the endocrine and immune systems have been shown to contribute to pathophysiological conditions. Aim of study - to answer the question if hyper- or/and hypothyroid state can be as provoking factor for inflammation in colon. The study was performed on 60 mature male mice of the inbred line C3H-A. On male mice was reproduced a model of experimental hyperthyroidism and hypothyroidism by oral intake of L-thyroxin and propylthyouracil, accordingly. By the 22nd week of the experiment all animals were sacrificed. The rectum was removed for histo- and immunocytochemical examination. In histological examination in hyperthyroid group the hypertrophy of the mucous membrane of the colon is detected. Simultaneously the frequency of cell mitosis is increased. Among the epithelium glands of the colon can clearly be seen apoptotic bodies. Moderate or expressed infiltration by lymphocytes and plasma cells is elucidated in mucous membrane of colon relatively to mucous membrane of colon of euthyroid group i.e. control one. In hyporthyroid group the hyportrophy of the mucous membrane of the colon was detected. The lymphocytic infiltration is not found. In immunocytochemical examination the frequency of CD20 and CD56 positive cells was significantly higher (>23%) in cytological preparation of membrane mucous of colon from hyperthyroid mice (p<0.01). Meanwhile CD20 and CD56 positive cells were detected in single cases in cytological preparation of membrane mucous of colon from hypothyroid mice. The same observation was done for healthy membrane mucous from control (euthyroid) group. It is possible that the thyroid status is one of the factors modulating the inflammation. This discussion is far from over, because it is unclear whether prolonged hyperthyroidism can actually activate pro-inflammatory reactions, which subsequently, in turn, activate carcinogenesis.

Investigation of the Influence of the Conditioning Medium Factors Obtained During the Cultivation of Bone Marrow Mesenchymal Stem Cells on the Course of Severe Local Radiation Injuries of Skin in Rats

Purpose: Study of the effect of paracrine factors, produced by MMSC of bone marrow during the cultivation, on the severity of local radiation injuries in the conditions of application in the early periods after irradiation. Material and methods: Experiments were performed on rats of the breed Wistar weighing 280 g. Rats were exposed locally in iliolumbar region of the back using X-ray machine LNC-268 (RAP 100-10) at a dose of 110 Gy (30 kV tube voltage, current 6.1 mA, filter Al 0.1 mm thick), dose rate is 21.4 Gy/min. Area of the irradiation field was 8.2–8.5 cm2. The conditioned medium obtained by culturing MMSC of rats’ bone marrow was administered in dose 1.0 ml (total protein 8 mg/ml) at 1, 3, 6, 8 and 10 days after irradiation. The severity of radiation damage to the skin and the effects of therapy were evaluated in dynamics by clinical manifestations, using planimetry and histological methods. Results: It was shown that in control animals and in rats, with the introduction of the conditioned medium, the values of the skin lesion area in the period up to the 29th day after irradiation practically did not differ, gradually decreasing in control animals from 5.9 ± 0.6 cm2 to 2.2 ± 0.3 cm2 at the 15th and 29th days after irradiation, respectively. Then, in the control group, the lesion area ranged from 1.4 ± 0.6 cm2 on the 50th day to 1.9 ± 0.8 cm2 on the 71st day. In the experimental group of animals, with the introduction of factors of the conditioning medium, a decrease in the area of the lesion and a stable dynamics of healing of radiation ulcers, beginning from the 36th day, there was a gradual decrease in the area of the lesion, which reached 0.2 ± 0.1 cm2 by the 71st day after irradiation. On the 64–71th day after irradiation, the difference between the areas of skin lesion in the experimental and control groups was statistically significant, p <0.05. The histological analysis showed that the use of paracrine factors obtained from MMSC in the process of cultivation significantly reduces the severity of the inflammatory reaction and accelerates the regeneration processes. Conclusion: Thus, the introduction of conditioned medium factors obtained during the cultivation of mesenchymal stem cells of the bone marrow facilitates a more easy flow of the pathological process and the healing of radiation ulcers after local radiation damage to the skin of rats. Apparently, the favorable effect of paracrine factors introduced in the early periods after irradiation, with severe local radiation injuries, is associated with their effect on pathological processes in the inflammatory-destructive stage.

A storage ring experiment to detect a proton electric dipole moment

A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of 10^-29 e ⋅ cm by using polarized "magic" momentum 0.7 GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the standard model at the scale of 3000 TeV.

Inelastic collapse and near-wall localization of randomly accelerated particles

Inelastic collapse of stochastic trajectories of a randomly accelerated particle moving in half-space z>0 has been discovered by McKean [J. Math. Kyoto Univ. 2, 227 (1963)] and then independently rediscovered by Cornell et al. [Phys. Rev. Lett. 81, 1142 (1998)PRLTAO0031-900710.1103/PhysRevLett.81.1142]. The essence of this phenomenon is that the particle arrives at the wall at z=0 with zero velocity after an infinite number of inelastic collisions if the restitution coefficient β of particle velocity is smaller than the critical value β_{c}=exp(-π/sqrt[3]). We demonstrate that inelastic collapse takes place also in a wide class of models with spatially inhomogeneous random forcing and, what is more, that the critical value β_{c} is universal. That class includes an important case of inertial particles in wall-bounded random flows. To establish how inelastic collapse influences the particle distribution, we derive the exact equilibrium probability density function ρ(z,v) for the particle position and velocity. The equilibrium distribution exists only at β<β_{c} and indicates that inelastic collapse does not necessarily imply near-wall localization.

Spectroscopy of Mn atoms isolated in solid ⁴He

We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to those of an inner-shell transition in Ba studied earlier. At the same time, they are more strongly perturbed than the corresponding transitions in Au and Cu under the same conditions. We suggest a qualitative explanation of these observations based on the atomic bubble model. Our results also suggest that the inner-shell transitions of Mn in solid He are more strongly perturbed than the same lines of Mn isolated in solid Ar or Kr matrices.

Spectroscopy of gold atoms isolated in liquid and solid 4He matrices

We present a systematic experimental study of absorption and fluorescence spectra of Au atoms in bulk liquid and solid helium matrices. The results are compared to the spectra of Cu atoms studied earlier. We investigate the dependence of the observed spectral lineshapes on the helium pressure. The observed splitting of the 5d(10)6p - 5d(9)6s(2) transitions of Au in hcp solid He gives evidence for an anisotropic trapping site structure formed either by a non-spherical atomic bubble or a four-vacancy center.

Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films

Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10(8) cm(-2)), in the case of hydrogen-treated ND seeding particles, to very high values of 10(11) cm(-2) for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young's moduli of more than 1000 GPa.

Successful treatment of localised radiation lesions in rats and humans by mesenchymal stem cell transplantation

Transplantation of mesenchymal stem cells (MSCs), at early and later stages after local exposure of rats to 140 Gy 90Sr/90Y beta radiation, was found to stimulate recovery of damaged skin. The area of local radiation injuries (LRIs) and accelerated healing of radiation ulcers was obtained. Clinical evolution showed the high efficiency of the transplantations of autologous MSCs for the treatment of deep beam ulcers, usually refractive to standard conservative treatment. Analogous to our results in the rats the authors obtained promising results with the application of MSCs for the treatment of severe LRIs in two human patients. Their radiation ulcers showed complete healing after stem cell application. Thus, further developments should determine the best possible conditions for MSC use in LRI treatment.

First observation of intrabeam stripping of negative hydrogen in a superconducting linear accelerator

We report on an experiment in which a negative hydrogen ion beam in the Spallation Neutron Source (SNS) linear accelerator was replaced with a beam of protons with similar size and dynamics. Fractional beam loss in the superconducting part of the SNS accelerator was measured to be at least 2×10(-5) for the H(-) beam, and it was an order of magnitude lower for the protons. Also beam loss has a stronger dependence on intensity with H(-) than with proton beams. These measurements verify a recent theoretical explanation of unexpected beam losses in the SNS superconducting linear accelerator based on an intrabeam stripping mechanism for negative hydrogen ions. This previously unidentified mechanism for beam loss is important for the design of new high current linear ion accelerators and the performance improvement of existing machines.

Spectroscopy of Cs2, RbCs, and Rb2 in solid 4He

We present comparative experimental and theoretical studies of the absorption and fluorescence spectra of the alkali-metal dimer molecules Cs(2) and RbCs immersed in a solid helium matrix, thereby extending our recent observations of Rb(2) in solid (4)He. The laser-excited molecular states are mostly quenched by the interaction with the He matrix. The quenching efficiently populates the second lowest excited state of the molecule, i.e., (1)  (3)Π((u)) that is metastable in the homonuclear dimers. Molecular excitation and emission bands are modeled by calculating Franck-Condon factors that give a reasonable agreement with the experimental findings.

Current reversals in a rocking ratchet: dynamical versus symmetry-breaking mechanisms

Directed transport in ratchets is determined by symmetry breaking in a system out of equilibrium. A hallmark of rocking ratchets is current reversals: an increase in the rocking force changes the direction of the current. In this work for a biharmonically driven spatially symmetric rocking ratchet we show that a class of current reversal is precisely determined by symmetry breaking, thus creating a link between dynamical and symmetry-breaking mechanisms.

Giant enhancement of electric field between two close metallic grains due to plasmonic resonance

We theoretically examine plasmonic resonance between two close metallic grains separated by a gap of width much less than the length of the incident electromagnetic wave. Resonance conditions are established and the electric field enhancement is found. Our general arguments are confirmed by analytic solution of the problem for simplest geometries. We discuss an extension of our results to more complex cases.

Universal velocity profile for coherent vortices in two-dimensional turbulence

Two-dimensional turbulence generated in a finite box produces large-scale coherent vortices coexisting with small-scale fluctuations. We present a rigorous theory explaining the eta=1/4 scaling in the V is proportional to r(-eta) law of the velocity spatial profile within a vortex, where r is the distance from the vortex center. This scaling, consistent with earlier numerical and laboratory measurements, is universal in its independence of details of the small-scale injection of turbulent fluctuations and details of the shape of the box.

Positive ion induced solidification of 4He

We have observed bulk solidification of 4He induced by nucleation on positive alkali ions in pressurized superfluid helium. The ions are extracted into the liquid from alkali-doped solid He by a static electric field. The experiments prove the existence of charged particles in a solid structure composed of doped He that was recently shown to coexist with superfluid helium below the He solidification pressure. This supports our earlier suggestion that the Coulomb interaction of positive ions surrounded by a solid He shell (snowballs) and electrons trapped in spherical cavities (electron bubbles), together with surface tension, is responsible for the stability of that structure against melting. We have determined the density of charges in the sample by two independent methods.

Sapphire-GaN-based planar integrated free-space optical system

We report on the design and fabrication of a planar integrated free-space optical system working on the basis of binary phase diffractive optical elements (DOEs) realized in GaN on a sapphire substrate. Group III-nitride/sapphire substrates enable the parallel monolithic integration of passive microoptical elements like lenses and gratings as demonstrated here and optoelectronic devices like light emitters and photodetectors on a single wafer. We present an approach for the simultaneous optimization of the efficiency of transmissive and reflective diffractive optical elements processed in a single lithographic etching step.

Gating ratchet for cold atoms

We demonstrate experimentally a gating ratchet with cold rubidium atoms in a driven near-resonant optical lattice. A single-harmonic periodic modulation of the optical potential depth is applied, together with a single-harmonic rocking force. Directed motion is observed as a result of the breaking of the symmetries of the system.

Patch coalescence as a mechanism for eukaryotic directional sensing

Eukaryotic cells possess a sensible chemical compass allowing them to orient toward sources of soluble chemicals. The extracellular chemical signal triggers separation of the cell membrane into two domains populated by different phospholipid molecules and oriented along the signal anisotropy. We propose a theory of this polarization process, which is articulated into subsequent stages of germ nucleation, patch coarsening, and merging into a single domain. We find that the polarization time, t{epsilon}, depends on the anisotropy degree through the power law t{epsilon} infinity epsilon{-2}, and that in a cell of radius R there should exist a threshold value epsilon{th} infinity R{-1} for the smallest detectable anisotropy.

Dynamics of energy condensation in two-dimensional turbulence

We report a numerical study, supplemented by phenomenological explanations, of "energy condensation" in forced 2D turbulence in a biperiodic box. Condensation is a finite size effect which occurs after the standard inverse cascade reaches the size of the system. It leads to the emergence of a coherent vortex dipole. We show that the time growth of the dipole is self-similar, and it contains most of the injected energy, thus resulting in an energy spectrum which is markedly steeper than the standard k{-5/3} one. Once the coherent component is subtracted, however, the remaining fluctuations have a spectrum close to k{-1}. The fluctuations decay slowly as the coherent part grows.

Effects of surface tension on immiscible Rayleigh-Taylor turbulence

We present phenomenology describing the internal structure of a turbulent zone, produced as the result of the push of a heavy fluid into a light one, for the case of immiscible fluids. One finds that the Kolmogorov cascade is realized within a range that grows with time, viz., scales between the mixing zone width, L proportional variant t(2), and the viscous scale, eta proportional variant t(-1/4). Surface-tension effects lead to formation of an emulsionlike state. Density fluctuations on scales larger than the typical drop size, l, are governed by the Obukhov-Corrsin cascade. If l >> eta, a wave energy cascade, related to capillary waves propagating along the surfaces of drops, is formed at scales below l, l proportional variant t(-2/5).

Probability of anomalously large bit-error rate in long haul optical transmission

We consider a linear model of optical transmission through a fiber with birefringent disorder in the presence of amplifier noise. Both disorder and noise are assumed to be weak, i.e., the average bit-error rate (BER) is small. The probability distribution function (PDF) of rare violent events leading to the values of BER much larger than its typical value is estimated. We show that the PDF has a long algebraic-like tail.

Boundary effects on chaotic advection-diffusion chemical reactions

A theory of a fast binary chemical reaction, A+B-->C, in a statistically stationary bounded chaotic flow at large Peclet number Pe and large Damköhler number Da is described. The first stage correspondent to formation of the developed lamellar structure in the bulk part of the flow is terminated by an exponential decay, proportional, variant exp((-lambdat) (where lambda is the Lyapunov exponent of the flow), of the chemicals in the bulk. The second and the third stages are due to the chemicals remaining in the boundary region. During the second stage, the amounts of A and B decay proportional, variant 1/sqrt[t], whereas the decay law during the third stage is exponential, proportional, variant exp((-gammat), where gamma approximately lambda/sqrt[Pe].

Shedding and interaction of solitons in weakly disordered optical fibers

The propagation of the soliton pattern through optical fiber with weakly disordered dispersion coefficient is considered. Solitons perturbed by this disorder radiate and, as a consequence, decay. The average radiation profile is found. Emergence of a long-range intrachannel interaction between the solitons (mediated by this radiation) is reported. We show that soliton in a multisoliton pattern experiences a random jitter: intersoliton separation is zero mean Gaussian random field. Fluctuations of this separation are estimated by deltay approximately Dz(2)square root mu, where D measures the disorder strength, z is the propagation distance, and mu stands for the transmission rate (number of solitons per unit length of the fiber). Direct numerical simulations are used to validate theoretical predictions for single soliton decay and two-soliton interaction. Relevance of these results to fiber optics communication technology is discussed.

Decay of scalar turbulence revisited

We demonstrate that at long times the rate of passive scalar decay in a turbulent, or simply chaotic, flow is dominated by regions where mixing is less efficient. We examine two situations. The first is of a spatially homogeneous stationary turbulent flow with both viscous and inertial scales present. It is shown that at large times scalar fluctuations decay algebraically in time at all spatial scales. The second example explains chaotic stationary flow in a disk/pipe. The boundary region of the flow controls the long-time decay, which is algebraic at some transient times, but becomes exponential, with the decay rate dependent on the scalar diffusion coefficient, at longer times.

Turbulence of polymer solutions

We investigate high-Reynolds-number turbulence in dilute polymer solutions. We show the existence of a critical value of the Reynolds number, which separates two different regimes. In the first regime, below the transition, the influence of the polymer molecules on the flow is negligible, so they can be regarded as passively embedded in the flow. This case admits a detailed investigation of the statistics of the polymer elongations. The second state is realized when the Reynolds number is larger than the critical value. This regime is characterized by the strong back reaction of polymers on the flow. We establish some properties of the statistics of the stress and velocity in this regime and discuss its relation to the drag reduction phenomenon.

Statistics of soliton-bearing systems with additive noise

We present a consistent method to calculate the probability distribution of soliton parameters in systems with additive noise. Even though the noise is weak, we are interested in probabilities of large fluctuations (generally non-Gaussian) which are beyond perturbation theory. Our method is a development of the instanton formalism (method of optimal fluctuation) based on a saddle-point approximation in the path integral. We first solve a fundamental problem of soliton statistics governed by a noisy nonlinear Schrödinger equation. We then apply our method to optical soliton transmission systems using signal control elements (filters and amplitude and phase modulators).

Turbulent dynamics of polymer solutions

We study properties of dilute polymer solutions. The probability density function (PDF) of polymer end-to-end extensions R in turbulent flows is examined. We show that if the value of the Lyapunov exponent lambda is smaller than the inverse molecular relaxation time 1/tau then the PDF has a strong peak at the equilibrium size R0 and a power tail at R>>R0. This confirms and extends the results of J. L. Lumley [Symp. Math. 9, 315 (1972)]. There is no essential influence of polymers on the flow in this regime. At lambdatau>1 the majority of molecules is stretched to the linear size R(op)>>R0, which can be much smaller than the maximal length of the molecules due to their back reaction.

Early diagnosis of coxarthrosis (in-shoe plantar pressure measurements)

INTRODUCTION:: Plantar pressure measurement during walking adds dynamic functional data to evaluation of gait disorders of teenagers with coxarthrosis. The duration of the complete gait cycle, its phases (stance and swing phase for right and left feet, double support) and phases of roll-over process are found useful in many clinical applications. METHODS:: In-shoe measurements were completed with Pedar system (99 element capacitive insoles from Novel, Munich, Germany) for 38 teenagers from military school (controls) and 29 teenagers with coxarthrosis. The data from 3 - 5 trials for each subject were collected. The distance was about 10 m, no requirements to the speed and step length were established. Special software was developed. RESULTS:: Time parameters for the complete gait cycle, its phases, phases of roll-over-process were calculated both for the controls and the teenagers with coxarthrosis It was found that stance phase and heel contact phase are decreased for the teenagers with coxarthrosis. DISCUSSION:: Decrease of stance phase, insufficient loading of the heel and decrease of heel contact time are a result of attempts to compensate the painfulness in the hip joint during walking. CONCLUSION:: Time parameters of the complete gait cycle and its phases may be useful in early diagnosis of coxarthrosis and evaluation of efficiency of the treatment.

Transformation and average as handy tools for pressure measurement data analysis

INTRODUCTION:: Pressure measurement data underneath[Table: see text] the foot represent usually a large number of data files which is equal to double product of the number of the subjects in study and of the number of the trials for each foot. Besides, 'normal' parameters are necessary to compare the results for the controls and for the subjects in study. Statistical parameters (mean values and standard deviations) are not very convenient when it is required to establish cartographical and geometrical parameters or peak pressures, maximum forces, contact areas, contact time and others for foot typing or as a standard. Sometimes it is reasonable to obtain average pressure data as a base for further data analysis. But taking into account that pressure distribution pattern may differ by its length, width and angle of the inclination of the foot axis to the horizontal it was necessary to solve a problem of transformation of any pressure picture to the given length and width (for vertical location of the foot axis). METHODS:: The transformed coordinates X(*) and Y(*) are defined from the following system of equations: X = Y(*) x width/width(*) x sina + X(*) x length/length(*) x cosa + X(o) Y = Y(*) x width/width(*) x cosa - X(*) x length/length(*) x sina + Y(o) where X(o), Y(o) -- the coordinates of the origin; width, length, a -- parameters of the initial pressure picture; width(*), length(*) -- parameters of the transformed pressure picture. X, Y -- are real values but the values of pressure are defined only in the integer coordinates. One of the main parts of average is a reduction of the time process to any number of frames. If N(max) is a maximum number of frames in one of the data files than all other data files must be transformed with accordance to the following formulas: for j-th frame the value of pressure for sensor with coordinates x, y is: P(*1)(xy) (j) = P(1)(xy) (i) x ki + P(1)(xy) (i+1) x k(i+1), where P(1)(xy) (i) -- pressure for sensor with coordinates x, y of the 1-th initial time process; j = 0, ellipsis, N(max) -1; j-th frame corresponds to i-th frame in the initial time process as i = integer(j) x (N -1)/(N(max) -1), N -- a number of frames in initial time process; coefficients k(i) and k(i+1) are equal to k(i) = j x (N -1)/(N(max) -1) -- I, k(i+1) = 1 - ki. Then the values of pressure are averaged: P(*)(xy) (j) = 1 / L x S P(1)(xy) (j), where L is a number of data files. Corresponding software was developed. RESULTS AND DISCUSSION:: 38 files of pressure measurement data of the teenagers from military school were chosen for transformation and average. Statistical errors of transformation and average were calculated for each data file (for peak pressure, force and area) and for all parameters from two software packages: Novel-win v.95.121 and Novel-ortho v.95.121. The maximum errors are for peak pressures (about 7%-10%) and contact areas (about 6%). CONCLUSION:: Transformation and average programs can be successfully used for data analysis additionally to traditional statistical software: groupmask evaluation program.

Velocity of the cop as a reliable parameter for early diagnosis of coxarthrosis

INTRODUCTION:: The first symptoms of the degenerative disease of hip joint appear very early when people are about 14 years old. But clinical and X-ray characters manifest themselves insufficiently: temporary slight pains in hip joints on loading, insignificant painfulness along posterior surface of the joint during palpation, slight lameness on the diseased side. The purpose of this study was to try to involve gait analysis in the clinical research of the teenagers with coxarthrosis and to define the parameters which may be used for early diagnosis of coxarthrosis. METHODS:: 38 male military school teen-agers which have no history in the foot disorders and 20 male and 9 female with coxarthrosis were used for study. Plantar pressure distribution measurements were performed with the mini-emed system (Novel, Munich, Germany). Five dynamic records of each foot were made on the pressure platform (28 x 60 sensors, resolution -- 3 sensors/cm(2), sampling frequency -- 16 Hz). Three trials of gait were accomplished by each subject with inserted insoles (99 sensors in each insole) at the distance about 10 m. Novel-win v.95.121 and Novel-ortho v.95.121 packages were used for data analysis. RESULTS:: For the teenagers with coxarthrosis the loading of heel area is significantly less (< = 15 N/cm(2)), maximum force is generally less. Contact time (in percent of roll-over-process) in the forefoot and toes is increased and is equal to 100% very often. The most interesting results are obtained for the curves of the velocity of the centres of pressure versus time. For the controls this curve has one or two maxima (during 50%-70% of roll-over-process when heel, midfoot and sometimes forefoot are loaded), then a short period of insignificant changes of the velocity (up to 88%-94% of roll-over-process when only forefoot and toes are loaded) and last a very short period of its increase (toe-off phase). For the most part of the teenagers with coxarthrosis this curve seems to be monotonous, oscillating near its mean value line. DISCUSSION:: These disturbances may be explained by valgus deviation of the neck of femur and insufficient function of the muscles of buttocks as a consequence of its lever web decrease. The muscle forces (particularly abducted muscles) are decreased (about 10%-15%). These data are consistent with previous reported findings. CONCLUSION:: To compensate for the painfulness in the diseased hip joint the teenagers load rearfoot and forefoot less than in the 'normal' foot, increasing contact time in the forefoot. As a consequence of disturbances in hip joint a pathway of the centre of pressure is longer than in 'norm' and its velocity changes oscillating near the mean value when for 'normal' teenagers three definite intervals of its change are viewed. Therefore the first symptoms of displastic coxarthrosis of teenagers may be revealed from plantar pressure measurements by analysing the character of time dependence the velocity of the centres of pressure and loading of different areas of the foot (force and contact time). Additionally, functional state of hip joint muscles, X-ray and clinical symptoms, heat radiation and laser biophotometry data give an opportunity to define the character of locomotor function disorders.