Long-range particle correlations and wavelets

The problem of long-range correlations of particles produced in high- energy collisions is discussed. Long-range correlations involve large groups of particles. Among them are, e.g., those correlations which lead to ring-like and elliptic flow shapes of individual high-multiplicity events in the polar+azimuthal angles plane. The \w method of \an which allows to disentangle various patterns has been proposed and applied to some central lead-lead collisions at energy 158 GeV per nucleon. Previous attempts to find out the ring-like correlations and recent results on \w \an of high- energy nuclei interactions are reviewed.Comment: 21 pages, 5 Figs, Latex, to be published in Physics- Uspekhi, Nov.200

Angular Correlations in Gluon Production at High Energy

We present a general, model independent argument demonstrating that gluons produced in high energy hadronic collision are necessarily correlated in rapidity and also in the emission angle. The strength of the correlation depends on the process and on the structure/model of the colliding particles. In particular we argue that it is strongly affected (and underestimated) by factorized approximations frequently used to quantify the effect.Comment: 12 page

Histological Imaging of Unstained Cancer Tissue Samples by Circularly Polarized Light

AbstractWe introduce a high-resolution polarization imaging approach for automatic stand-alone classification of the unstained breast cancer tissue blocks by using K-means cluster analysis of the Stokes vectors projected on the Poincaré sphere.Abstract We introduce a high-resolution polarization imaging approach for automatic stand-alone classification of the unstained breast cancer tissue blocks by using K-means cluster analysis of the Stokes vectors projected on the Poincaré sphere

Dynamic evaluation of blood flow microcirculation by combined use of the laser Doppler flowmetry and high-speed videocapillaroscopy methods

AbstractThe dynamic light scattering methods are widely used in biomedical diagnostics involving evaluation of blood flow. However, there exist some difficulties in quantitative interpretation of backscattered light signals from the viewpoint of diagnostic information. This study considers the application of the high‐speed videocapillaroscopy (VCS) method that provides the direct measurement of the red blood cells (RBCs) velocity into a capillary. The VCS signal presents true oscillation nature of backscattered light caused by moving RBCs. Thus, the VCS signal can be assigned as a reference one with respect to more complicated signals like in laser Doppler flowmetry (LDF). An essential correlation between blood flow velocity oscillations in a separate human capillary and the integral perfusion estimate obtained by the LDF method has been found. The observation of blood flow by the VCS method during upper arm occlusion has shown emergence of the reverse blood flow effect in capillaries that corresponds to the biological zero signal in the LDF. The reverse blood flow effect has to be taken into account in interpretation of LDF signals.Abstract The dynamic light scattering methods are widely used in biomedical diagnostics involving evaluation of blood flow. However, there exist some difficulties in quantitative interpretation of backscattered light signals from the viewpoint of diagnostic information. This study considers the application of the high‐speed videocapillaroscopy (VCS) method that provides the direct measurement of the red blood cells (RBCs) velocity into a capillary. The VCS signal presents true oscillation nature of backscattered light caused by moving RBCs. Thus, the VCS signal can be assigned as a reference one with respect to more complicated signals like in laser Doppler flowmetry (LDF). An essential correlation between blood flow velocity oscillations in a separate human capillary and the integral perfusion estimate obtained by the LDF method has been found. The observation of blood flow by the VCS method during upper arm occlusion has shown emergence of the reverse blood flow effect in capillaries that corresponds to the biological zero signal in the LDF. The reverse blood flow effect has to be taken into account in interpretation of LDF signals

Imaging of early stage breast cancer with circularly polarized light

AbstractIn this study, we utilize the properties of polarized light for the analysis of paraffin-embedded breast cancer samples. We perform the measurements of the full Stokes vector of back-reflected radiation and calculate the degree of polarization as a diagnostic criterion for the separation of healthy and cancer sample sections. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The degree of the polarization of the reflected light was found to be the most sensitive parameter for the reliable differentiation of tissue. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The highest contrast between cancerous and normal regions was observed for the probing wavelength of 450 nm. The degree of the polarization of the reflected light was found to be the most sensitive parameter. Mapping the Stokes vectors of backscattered light on a Poincaré sphere helps to highlight the changes of polarization state.Abstract In this study, we utilize the properties of polarized light for the analysis of paraffin-embedded breast cancer samples. We perform the measurements of the full Stokes vector of back-reflected radiation and calculate the degree of polarization as a diagnostic criterion for the separation of healthy and cancer sample sections. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The degree of the polarization of the reflected light was found to be the most sensitive parameter for the reliable differentiation of tissue. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The highest contrast between cancerous and normal regions was observed for the probing wavelength of 450 nm. The degree of the polarization of the reflected light was found to be the most sensitive parameter. Mapping the Stokes vectors of backscattered light on a Poincaré sphere helps to highlight the changes of polarization state

Diagnosis of Skin Vascular Complications Revealed by Time-Frequency Analysis and Laser Doppler Spectrum Decomposition

Nowadays, photonics-based techniques are used extensively in various applications, including functional clinical diagnosis, progress monitoring in treatment, and provision of metrological control. In fact, in the frame of practical implementation of optical methods, such as laser Doppler flowmetry (LDF), the qualitative interpretation and quantitative assessment of the detected signal remains vital and urgently required. In the conventional LDF approach, the key measured parameters, index of microcirculation and perfusion rate, are proportional to an averaged concentration of red blood cells (RBC) and their average velocity within a diagnostic volume. These quantities compose mixed signals from different vascular beds with a range of blood flow velocities and are typically expressed in relative units. In the current paper we introduce a new signal processing approach for the decomposition of LDF power spectra in terms of ranging blood flow distribution by frequency series. The developed approach was validated in standard occlusion tests conducted on healthy volunteers, and applied to investigate the influence of local pressure rendered by a probe on the surface of the skin. Finally, in limited clinical trials, we demonstrate that the approach can significantly improve the diagnostic accuracy of detection of microvascular changes in the skin of the feet in patients with Diabetes Mellitus type 2, as well as age-specific changes. The results obtained show that the developed approach of LDF signal decomposition provides essential new information about blood flow and blood microcirculation and has great potential in the diagnosis of vascular complications associated with various diseases

Spatial heterogeneity of cutaneous blood flow respiratory-related oscillations quantified via laser speckle contrast imaging

LSCI technique provides experimental data which can be considered in the context of spatial blood flow coherency. Analysis of vascular tone oscillations gives additional information to ensure a better understanding of the mechanisms affecting microvascular physiology. The oscillations with different frequencies are due to different physiological mechanisms. The reasons for the generation of peripheral blood flow oscillations in the 0.14–0.6 Hz frequency band are as follows: cardio-respiratory interactions, pressure variations in the venous part of the circulatory system, and the effect of the sympathetic nervous system on the vascular tone. Earlier, we described the spatial heterogeneity of around 0.3 Hz oscillations and this motivated us to continue the research to find the conditions for the occurrence of spatial phase synchronization. For this purpose, a number of physiological tests (controlled respiration, breath holder, and venous occlusion tests) which influence the blood flow oscillations of 0.14–0.6 Hz were considered, an appropriate measurement system and the required data processing algorithms were developed. At spontaneous respiration, the oscillations with frequencies around 0.3 Hz were stochastic, whereas all the performed tests induced an increase in spatial coherence. The protocols and methods proposed here can help to clarify whether the heterogeneity of respiratory-related blood flow oscillations exists on the skin surface

Wavelet Analysis of the Temporal Dynamics of the Laser Speckle Contrast in Human Skin

Objective: Spectral analysis of laser Doppler flowmetry (LDF) signals has been widely used in studies of physiological vascular function regulation. An alternative to LDF is the laser speckle contrast imaging method (LSCI), which is based on the same physical principle. In contrast to LDF, LSCI provides non-scanning full-field imaging of a relatively wide skin area and offers high spatial and temporal resolutions, which allows visualization of microvascular structure. This circumstance, together with a large number of works which had shown the effectiveness of temporal LSCI analysis, gave impetus to experimental studies of the relation between LDF and LSCI used to monitor the temporal dynamics of blood flow. Methods: Continuous wavelet transform was applied to construct a time-frequency representation of a signal. Results: Analysis of 10 minute LDF and LSCI output signals recorded simultaneously revealed rather high correlation between oscillating components. It was demonstrated for the first time that the spectral energy of oscillations in the 0.01-2 Hz frequency range of temporal LSCI recordings carries the same information as the conventional LDF recordings and hence it reflects the same physiological vascular tone regulation mechanisms. Conclusion: The approach proposed can be used to investigate speckle pattern dynamics by LSCI in both normal and pathological conditions. Significance: The results of research on the influence of spatial binning and averaging on the spectral characteristics of perfusion monitored by LSCI are of considerable interest for the development of LSCI systems optimized to evaluate temporal dynamics

Laser doppler spectrum decomposition applied in diagnostics of microcirculatory disturbances

Laser Doppler flowmetry (LDF) is widely used to study blood microcirculation in the skin. However, during tradition signal processing based on the integral estimations of the power spectrum of detector photocurrent, the significant part of the information about the skin blood ow is lost. In this study, we propose to analyse the distribution of the blood perfusion over the Doppler shift frequencies, which correlate with the RBC velocity. This approach provides localisation of the blood ow oscillations in different subranges of the Doppler shift. The method applied together with the wavelet analysis has been tested in healthy volunteers and patients with psoriasis on the unaffected surface of the skin. It was revealed, that the significant difference in the amplitude of myogenic oscillations is allocated in the region of the low frequency Doppler shift (1-200 Hz). This frequency region can be associated with the signal from slow components of the skin microcirculation, that can point out on a different state of the lymphatic system of the skin in psoriasis

Evaluation of microvascular disturbances in rheumatic diseases by analysis of skin blood flow oscillations

Laser Doppler flowmetry (LDF), tissue reflectance oximetry (TRO) and pulse oximetry (PO) and cold pressor test (CPT) were used to assess the microcirculation parameters and the activation of regulatory mechanisms. LDF and TRO samples wavelet transform in the frequency bands 0.01-2 Hz was used to evaluate microvascular disturbances in rheumatic diseases and to assess the vascular involvement in the pathological process. The spectral components of LDF and TRO signals associated with endothelial, adrenergic, intrinsic smooth muscle, respiratory and cardiac activities were analyzed. Significant difference between healthy and rheumatology subjects was identified in perfusion parameters. Spectral analysis of the LDF signal revealed significant difference between two group of high (<0.1 Hz) frequency pulsations. Based on the analysed of the perfusion and amplitudes oscillation in the frequency band the decision rule for detection microvascular disturbances were synthesized. The perfusion parameter and amplitude oscillation associated with cardiac activities included in the decision rule. Based on the measured parameters and the result of wavelet transform LDF- and TRO-signals the parameters for detection of complications associated with microvascular disturbances and their possible causes were proposed