Backscattering Differential Ghost Imaging in Turbid Media

In this Letter we present experimental results concerning the retrieval of images of absorbing objects immersed in turbid media via differential ghost imaging (DGI) in a backscattering configuration. The method has been applied, for the first time to our knowledge, to the imaging of small thin black objects located at different depths inside a turbid solution of polystyrene nanospheres and its performances assessed via comparison with standard imaging techniques. A simple theoretical model capable of describing the basic optics of DGI in turbid media is proposed.Comment: 5 pages, 6 figure

Image transfer through a chaotic channel by intensity correlations

The three-wave mixing processes in a second-order nonlinear medium can be used for imaging protocols, in which an object field is injected into the nonlinear medium together with a reference field and an image field is generated. When the reference field is chaotic, the image field is also chaotic and does not carry any information about the object. We show that a clear image of the object be extracted from the chaotic image field by measuring the spatial intensity correlations between this field and one Fourier component of the reference. We experimentally verify this imaging protocol in the case of frequency downconversion.Comment: 17 pages, 7 figure

Dynamic heterodyne near field scattering

The technique heterodyne near field scattering (HNFS), originally developed for low-angle static light scattering, has also been implemented for carrying out dynamic light scattering. While the classical dynamic light scattering method measures the intensity-intensity correlation function, dynamic HNFS gives directly the field-field correlation function, without any assumption on the statistical properties of the sample, as the ones required by the Siegert relation. The technique has been tested with calibrated Brownian particles and its performances compared to those of the classical dynamic light scattering method.The technique heterodyne near field scattering (HNFS), originally developed for low-angle static light scattering, has also been implemented for carrying out dynamic light scattering. While the classical dynamic light scattering method measures the intensity-intensity correlation function, dynamic HNFS gives directly the field-field correlation function, without any assumption on the statistical properties of the sample, as the ones required by the Siegert relation. The technique has been tested with calibrated Brownian particles and its performances compared to those of the classical dynamic light scattering method. \ua9 2008 American Institute of Physics

Experimental evidence of high-resolution ghost imaging and ghost diffraction with classical thermal light

High-resolution ghost image and ghost diffraction experiments are performed by using a single source of thermal-like speckle light divided by a beam splitter. Passing from the image to the diffraction result solely relies on changing the optical setup in the reference arm, while leaving untouched the object arm. The product of spatial resolutions of the ghost image and ghost diffraction experiments is shown to overcome a limit which was formerly thought to be achievable only with entangled photons.Comment: 5 pages, 4 figure

Heterodyne near-field scattering: A technique for complex fluids

The heterodyne near-field scattering (HNFS) technique for studying complex fluids such as colloidal systems was discussed. A different data reduction scheme was adopted which allowed the improvement in performance of the technique, at levels of sensitivity and accuracy much higher than those achievable with classical low-angle light scattering instrumentation. It was observed that this method also relaxes the requirements on the optical/mechanical stability of the experimental setup and allows for a real time analysis. Nonstationary samples, such as aggregating colloidal solutions, were also investigated, and their kinetics quantitatively characterized

Heterodyne speckle velocimetryof Poiseuille flow

We review the technique named heterodyne speckle velocimetry and present two applications for testing the method with a fluid moving under the conditions of Poiseuille flow. The fluid was seeded with small tracking particles diameter 300 nm and fluxed between the two parallel planes of a cell with constant or variable cross section. In the first case the velocity distribution was constant along the direction parallel to the planes and was in excellent agreement with the expected Poiseuille profile along the orthogonal direction. In the second case, where velocity gradients were present also along the planes, the technique was able to reconstruct both the orthogonal Poiseuille profile and the in-plane two dimensional mapping of the velocity vectors, with the possibility of measuring the fluid flux within an accuracy of 1%

Coherent imaging of a pure phase object with classical incoherent light

By using the ghost imaging technique, we experimentally demonstrate the reconstruction of the diffraction pattern of a {\em pure phase} object by using the classical correlation of incoherent thermal light split on a beam splitter. The results once again underline that entanglement is not a necessary feature of ghost imaging. The light we use is spatially highly incoherent with respect to the object ($\approx 2 \mu$m speckle size) and is produced by a pseudo-thermal source relying on the principle of near-field scattering. We show that in these conditions no information on the phase object can be retrieved by only measuring the light that passed through it, neither in a direct measurement nor in a Hanbury Brown-Twiss (HBT) scheme. In general, we show a remarkable complementarity between ghost imaging and the HBT scheme when dealing with a phase object.Comment: 13 pages, 11 figures. Published in Physical Review A. Replaced version fixes some problems with Figs. 1, 4 and 1

B Lymphocytes as Targets of the Immunomodulatory Properties of Human Amniotic Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSC) from the amniotic membrane of human term placenta (hAMSC), and the conditioned medium generated from their culture (CM-hAMSC) offer significant tools for their use in regenerative medicine mainly due to their immunomodulatory properties. Interestingly, hAMSC and their CM have been successfully exploited in preclinical disease models of inflammatory and autoimmune diseases where depletion or modulation of B cells have been indicated as an effective treatment, such as inflammatory bowel disease, lung fibrosis, would healing, collagen-induced arthritis, and multiple sclerosis. While the interactions between hAMSC or CM-hAMSC and T lymphocytes, monocytes, dendritic cells, and macrophages has been extensively explored, how they affect B lymphocytes remains unclear. Considering that B cells are key players in the adaptive immune response and are a central component of different diseases, in this study we investigated the in vitro properties of hAMSC and CM-hAMSC on B cells. We provide evidence that both hAMSC and CM-hAMSC strongly suppressed CpG-activated B-cell proliferation. Moreover, CM-hAMSC blocked B-cell differentiation, with an increase of the proportion of mature B cells, and a reduction of antibody secreting cell formation. We observed the strong inhibition of B cell terminal differentiation into CD138+ plasma cells, as further shown by a significant decrease of the expression of interferon regulatory factor 4 (IRF-4), PR/SET domain 1(PRDM1), and X-box binding protein 1 (XBP-1) genes. Our results point out that the mechanism by which CM-hAMSC impacts B cell proliferation and differentiation is mediated by secreted factors, and prostanoids are partially involved in these actions. Factors contained in the CM-hAMSC decreased the CpG-uptake sensors (CD205, CD14, and TLR9), suggesting that B cell stimulation was affected early on. CM-hAMSC also decreased the expression of interleukin-1 receptor-associated kinase (IRAK)-4, consequently inhibiting the entire CpG-induced downstream signaling pathway. Overall, these findings add insight into the mechanism of action of hAMSC and CM-hAMSC and are useful to better design their potential therapeutic application in B-cell mediated diseases