Correlation plenoptic imaging

Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in classical imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this paper, we demonstrate that the momentum/position correlation of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging.Comment: 6 pages, 3 figure

Deformation of a flexible fiber in a viscous flow past an obstacle

We study the deformation and transport of elastic fibers in a viscous Hele-Shaw flow with curved streamlines. The variations of the global velocity and orientation of the fiber follow closely those of the local flow velocity. The ratios of the curvatures of the fibers by the corresponding curvatures of the streamlines reflect a balance between elastic and viscous forces: this ratio is shown experimentally to be determined by a dimensionless {\it Sperm number} $Sp$ combining the characteristic parameters of the flow (transverse velocity gradient, viscosity, fiber diameter/cell gap ratio) and those of the fiber (diameter, effective length, Young's modulus). For short fibers, the effective length is that of the fiber; for long ones, it is equal to the transverse characteristic length of the flow. For $S\_p \lesssim 250$, the ratio of the curvatures increases linearly with $Sp$; For $S\_p \gtrsim 250$, the fiber reaches the same curvature as the streamlines

Signal-to-noise properties of correlation plenoptic imaging with chaotic light

Correlation Plenoptic Imaging (CPI) is a novel imaging technique, that exploits the correlations between the intensity fluctuations of light to perform the typical tasks of plenoptic imaging (namely, refocusing out-of-focus parts of the scene, extending the depth of field, and performing 3D reconstruction), without entailing a loss of spatial resolution. Here, we consider two different CPI schemes based on chaotic light, both employing ghost imaging: the first one to image the object, the second one to image the focusing element. We characterize their noise properties in terms of the signal-to-noise ratio (SNR) and compare their performances. We find that the SNR can be significantly higher and easier to control in the second CPI scheme, involving standard imaging of the object; under adequate conditions, this scheme enables reducing by one order of magnitude the number of frames for achieving the same SNR.Comment: 12 pages, 3 figure

Exploring plenoptic properties of correlation imaging with chaotic light

In a setup illuminated by chaotic light, we consider different schemes that enable to perform imaging by measuring second-order intensity correlations. The most relevant feature of the proposed protocols is the ability to perform plenoptic imaging, namely to reconstruct the geometrical path of light propagating in the system, by imaging both the object and the focusing element. This property allows to encode, in a single data acquisition, both multi-perspective images of the scene and light distribution in different planes between the scene and the focusing element. We unveil the plenoptic property of three different setups, explore their refocusing potentialities and discuss their practical applications.Comment: 9 pages, 4 figure

Correlation Plenoptic Imaging With Entangled Photons

Plenoptic imaging is a novel optical technique for three-dimensional imaging in a single shot. It is enabled by the simultaneous measurement of both the location and the propagation direction of light in a given scene. In the standard approach, the maximum spatial and angular resolutions are inversely proportional, and so are the resolution and the maximum achievable depth of focus of the 3D image. We have recently proposed a method to overcome such fundamental limits by combining plenoptic imaging with an intriguing correlation remote-imaging technique: ghost imaging. Here, we theoretically demonstrate that correlation plenoptic imaging can be effectively achieved by exploiting the position-momentum entanglement characterizing spontaneous parametric down-conversion (SPDC) photon pairs. As a proof-of-principle demonstration, we shall show that correlation plenoptic imaging with entangled photons may enable the refocusing of an out-of-focus image at the same depth of focus of a standard plenoptic device, but without sacrificing diffraction-limited image resolution.Comment: 12 pages, 5 figure

Intestinal perforation after surgical treatment for incisional hernia. iatrogenic or idiopathic?

Intestinal perforation (IP) is a life-threatening gastroenterological condition requiring urgent surgical care, which may present itself as an uncommon complication following incisional hernia repair surgery, most often because of iatrogenic traumatism occurring during the procedure. However, we report a case where a spontaneous onset can be hypothesised. A 60-years-old patient underwent repair of an abdominal laparocele, through rectus abdominis muscle plasty, 5 years after development of an incisional hernia due to exploratory laparotomy for the treatment of acute appendicitis. Xipho-pubic scar was excised and umbilicus and supra-umbilical hernia sac dissected, a linear median incision was performed along the sub-umbilical linea alba, reaching preperitoneal plane to assess any intestinal loop adherence to the abdominal wall. After limited viscerolysis, abdominal wall defect was corrected by 'rectus abdominis muscle plasty' and umbilicus reconstruction by Santanelli technique. Postoperative course was uneventful until Day 29, with sudden onset of epigastric pain, fever and bulge. Sixty cubic centimeter pus was drained percutaneously and cavity was rinsed with a 50% H2O2 and H2O V-V solution until draining clear fluid. Symptoms recurred two days later, while during rinsing presented dyspnoea. X-Ray and CT scan diagnosed IP, and she underwent under emergency an exploratory laparotomy, leading to right hemicolectomy extended to last ileal loops and middle third of the transverse, right monolateral salpingo-ovariectomy and a temporary ileostomy by general surgeon. Twenty-three days later an ileostomy reversal surgery was performed and 8 days after she was discharged. At latest follow-up patient showed fair conditions, complaining abdominal pain and diarrhoea, attributable to the extensive intestinal resection. IP following incisional hernia repair, is reported as uncommon and early postoperative complication. In our case, the previous regular postoperative course with late onset lead us to hypothesise a possible idiopathic etiopathogenesis, because of a strangulation followed by gangrene and abscess formation, which might begin before the incisional hernia repair and unnoticed at the time surgery was performed

Final results of an experiment to search for 2beta processes in zinc and tungsten with the help of radiopure ZnWO4 crystal scintillators

A search for the double beta decay of zinc and tungsten isotopes has been performed with the help of radiopure ZnWO4 crystal scintillators (0.1-0.7 kg) at the Gran Sasso National Laboratories of the INFN. The total exposure of the low background measurements is 0.529 kg yr. New improved half-life limits on the double beta decay modes of 64Zn, 70Zn, 180W, and 186W have been established at the level of 10^{18}-10^{21} yr. In particular, limits on double electron capture and electron capture with positron emission in 64Zn have been set: T_{1/2}(2\nu 2K) > 1.1 10^{19} yr, T_{1/2} (0\nu 2\epsilon) > 3.2 10^{20} yr, T_{1/2} (2\nu \epsilon \beta^+) > 9.4 10^{20} yr, and T_{1/2} (0\nu \epsilon \beta^+) > 8.5 10^{20} yr, all at 90% C.L. Resonant neutrinoless double electron capture in 180W has been restricted on the level of T_{1/2} (0\nu 2\epsilon) > 1.3 10^{18} yr. A new half-life limit on alpha transition of 183W to the metastable excited level 1/2^- 375 keV of 179Hf has been established: T_{1/2} > 6.7 10^{20} yr.Comment: This is an author-created, un-copyedited version of an article published in J. Phys. G: Nucl. Part. Phys. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at doi: 10.1088/0954-3899/38/11/11510

Deep eutectic solvents: a structural point of view on the role of the cation

In this work we have developed an analytical procedure to identify metal ion coordination geometries in liquid media based on the calculation of Combined Distribution Functions (CDFs) starting from Molecular Dynamics (MD) simulations. CDFs provide a fingerprint which can be easily and unambiguously assigned to a reference polyhedron. The CDF analysis has been tested on five systems and has proven to reliably identify the correct geometries of several ion coordination complexes. This tool is simple and general and can be efficiently applied to different MD simulations of liquid systems

Walking the tightrope: Circular economy breadth and firm economic performance

The circular economy (CE) can bring benefits but also pitfalls to the production processes, affecting a firm's economic performance. Using data from European SMEs, we empirically investigate, from the perspective of self-determination theory, the extent to which the breadth of CE activities, that is, the number of CE activities undertaken by a firm, affects a firm's economic performance. Our study theorizes and shows that there is an inverted U-shaped effect brought about by the number of CE activities on economic performance. This research advances our scientific understanding of the CE and provides managers with suggestions on how to maximize the benefits generated by the CE in terms of economic performance by implementing the right amount of CE activities

Diffraction-limited plenoptic imaging with correlated light

Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field (DOF). To increase resolution, high numerical apertures (NA) are needed, but the associated large angular uncertainty results in a limited range of depths that can be put in sharp focus. Plenoptic imaging was introduced a few years ago to remedy this trade off. To this aim, plenoptic imaging reconstructs the path of light rays from the lens to the sensor. However, the improvement offered by standard plenoptic imaging is practical and not fundamental: the increased DOF leads to a proportional reduction of the resolution well above the diffraction limit imposed by the lens NA. In this paper, we demonstrate that correlation measurements enable pushing plenoptic imaging to its fundamental limits of both resolution and DOF. Namely, we demonstrate to maintain the imaging resolution at the diffraction limit while increasing the depth of field by a factor of 7. Our results represent the theoretical and experimental basis for the effective development of the promising applications of plenoptic imaging.Comment: 10 pages, 10 figure