Postoperative urinary leakage after bilateral totally extraperitoneal herniorrhaphy in a patient with a healed cystostomy and appendectomy: A case report.

We report a case of postoperative urinary leakage after bilateral laparoscopic totally extraperitoneal (TEP) herniorrhaphy. A man in his upper 80s with a healed cystostomy and appendectomy underwent bilateral TEP herniorrhaphy. Urinary leakage was noted by ultrasound examination 4 days after bilateral TEP. Cystography and computed tomography conclusively confirmed a 6-mm extraperitoneal fistula at the site of the previous cystostomy. The fistula involved the anterior bladder wall and was associated with an extended urinoma. The patient was treated by indwelling catheterization using a Foley catheter and repeated ultrasound-guided puncture and aspiration of the inguinal effusion at the bedside. The patient was completely healed 69 days after the operation with no mesh infection or bladder dysfunction. We believe that urinary leakage is possible after TEP herniorrhaphy in patients with a healed suprapubic cystostomy. Therefore, indwelling catheterization using a Foley catheter should be implemented before surgery, and the Foley catheter can be removed within 1 week after surgery if no postoperative urinary leakage is observed. A history of suprapubic cystotomy should not be regarded as a contraindication for TEP surgery. This is the first report of urinary leakage after bilateral TEP herniorrhaphy in a patient with a healed cystostomy and appendectomy.

Twin-Field Quantum Key Distribution without Phase Locking.

Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here, we propose and demonstrate an approach to recover the single-photon interference pattern and realize TF-QKD without phase locking. Our approach separates the communication time into reference frames and quantum frames, where the reference frames serve as a flexible scheme for establishing the global phase reference. To do so, we develop a tailored algorithm based on fast Fourier transform to efficiently reconcile the phase reference via data postprocessing. We demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers. At 50-km standard fiber, we produce a high secret key rate (SKR) of 1.27 Mbit/s, while at 504-km standard fiber, we obtain the repeaterlike key rate scaling with a SKR of 34 times higher than the repeaterless secret key capacity. Our work provides a scalable and practical solution to TF-QKD, thus representing an important step towards its wide applications.

Long range 3D imaging through atmospheric obscurants using array-based single-photon LiDAR.

Single-photon light detection and ranging (LiDAR) has emerged as a strong candidate technology for active imaging applications. In particular, the single-photon sensitivity and picosecond timing resolution permits high-precision three-dimensional (3D) imaging capability through atmospheric obscurants including fog, haze and smoke. Here we demonstrate an array-based single-photon LiDAR system, which is capable of performing 3D imaging in atmospheric obscurant over long ranges. By adopting the optical optimization of system and the photon-efficient imaging algorithm, we acquire depth and intensity images through dense fog equivalent to 2.74 attenuation lengths at distances of 13.4 km and 20.0 km. Furthermore, we demonstrate real-time 3D imaging for moving targets at 20 frames per second in mist weather conditions over 10.5 km. The results indicate great potential for practical applications of vehicle navigation and target recognition in challenging weather.

Long-range photon-efficient 3D imaging without range ambiguity.

Single-photon light detection and ranging (LiDAR) has broad applications ranging from remote sensing to target recognition. In most cases, however, the repetition period of the pulsed laser limits the maximum distance that can be unambiguously determined. The relative distances are normally obtained using a depth map. Here, we propose and demonstrate a photon-efficient three-dimensional (3D) imaging framework which permits the operation of high laser pulse repetition rates for long-range depth imaging without range ambiguity. Our approach uses only one laser period per pixel and borrows the information from neighboring pixels to reconstruct the absolute depth map of the scene. We demonstrate the absolute depth map recovery at ranges between 2.2 km and 13.8 km using ∼1.41 signal photons per pixel. We also show the capability to image the absolute distances of moving targets in real time.

Boosting Photon-Efficient Image Reconstruction With A Unified Deep Neural Network.

Photon-efficient imaging, which captures 3D images with single-photon sensors, has enabled a wide range of applications. However, two major challenges limit the reconstruction performance, i.e., the low photon counts accompanied by low signal-to-background ratio (SBR) and the multiple returns. In this paper, we propose a unified deep neural network that, for the first time, explicitly addresses these two challenges, and simultaneously recovers depth maps and intensity images from photon-efficient measurements. Starting from a general image formation model, our network is constituted of one encoder, where a non-local block is utilized to exploit the long-range correlations in both spatial and temporal dimensions of the raw measurement, and two decoders, which are designed to recover depth and intensity, respectively. Meanwhile, we investigate the statistics of the background noise photons and propose a noise prior block to further improve the reconstruction performance. The proposed network achieves decent reconstruction fidelity even under extremely low photon counts / SBR and heavy blur caused by the multiple-return effect, which significantly surpasses the existing methods. Moreover, our network trained on simulated data generalizes well to real-world imaging systems, which greatly extends the application scope of photon-efficient imaging in challenging scenarios with a strict limit on optical flux. Code is available at https://github.com/JiayongO-O/PENonLocal.

Frequency-modulated continuous-wave 3D imaging with high photon efficiency.

Frequency-modulated continuous-wave (FMCW) light detection and ranging (LIDAR), which offers high depth resolution and immunity to environmental disturbances, has emerged as a strong candidate technology for active imaging applications. In general, hundreds of photons per pixel are required for accurate three-dimensional (3D) imaging. When it comes to the low-flux regime, however, depth estimation has limited robustness. To cope with this, we propose and demonstrate a photon-efficient approach for FMCW LIDAR. We first construct a FMCW LIDAR setup based on single-photon detectors where only a weak local oscillator is needed for the coherent detection. Further, to realize photon-efficient imaging, our approach borrows the data from neighboring pixels to enhance depth estimates, and employs a total-variation seminorm to smooth out the noise on the recovered depth map. Both simulation and experiment results show that our approach can produce high-quality 3D images from ∼10 signal photons per pixel, increasing the photon efficiency by 10-fold over the traditional processing method. The high photon efficiency will be valuable for low-power and rapid FMCW applications.

Non-line-of-sight imaging over 1.43 km.

Non-line-of-sight (NLOS) imaging has the ability to reconstruct hidden objects from indirect light paths that scatter multiple times in the surrounding environment, which is of considerable interest in a wide range of applications. Whereas conventional imaging involves direct line-of-sight light transport to recover the visible objects, NLOS imaging aims to reconstruct the hidden objects from the indirect light paths that scatter multiple times, typically using the information encoded in the time-of-flight of scattered photons. Despite recent advances, NLOS imaging has remained at short-range realizations, limited by the heavy loss and the spatial mixing due to the multiple diffuse reflections. Here, both experimental and conceptual innovations yield hardware and software solutions to increase the standoff distance of NLOS imaging from meter to kilometer range, which is about three orders of magnitude longer than previous experiments. In hardware, we develop a high-efficiency, low-noise NLOS imaging system at near-infrared wavelength based on a dual-telescope confocal optical design. In software, we adopt a convex optimizer, equipped with a tailored spatial-temporal kernel expressed using three-dimensional matrix, to mitigate the effect of the spatial-temporal broadening over long standoffs. Together, these enable our demonstration of NLOS imaging and real-time tracking of hidden objects over a distance of 1.43 km. The results will open venues for the development of NLOS imaging techniques and relevant applications to real-world conditions.

Compact long-range single-photon imager with dynamic imaging capability.

Single-photon light detection and ranging (LiDAR) has emerged as a strong candidate technology for active imaging applications. Benefiting from the single-photon sensitivity in detection, long-range active imaging can be realized with a low-power laser and a small-aperture transceiver. However, existing kilometer-range active imagers are bulky and have a long data acquisition time. Here we present a compact co-axial single-photon LiDAR system for kilometer-range 3D imaging. A fiber-based transceiver with a 2.5 cm effective aperture was employed to realize a robust and compact architecture, while a tailored temporal filtering approach guaranteed the high signal-to-noise level. Moreover, a micro-electro-mechanical system scanning mirror was adopted to achieve fast beam scanning. In experiment, high-resolution 3D images of different targets up to 12.8 km were acquired to demonstrate the long-range imaging capability. Furthermore, it exhibits the ability to achieve dynamic imaging at five frames per second over a distance of ∼1km. The results indicate potential in a variety of applications such as remote sensing and long-range target detection.

Compressed sensing for active non-line-of-sight imaging.

Non-line-of-sight (NLOS) imaging techniques have the ability to look around corners, which is of growing interest for diverse applications. We explore compressed sensing in active NLOS imaging and show that compressed sensing can greatly reduce the required number of scanning points without the compromise of the imaging quality. Particularly, we perform the analysis for both confocal NLOS imaging and active occlusion-based periscopy. In experiment, we demonstrate confocal NLOS imaging with only 5 × 5 scanning points for reconstructing a three-dimensional hidden image which has 64 × 64 spatial resolution. The results show that compressed sensing can reduce the scanning points and the total capture time, while keeping the imaging quality. This will be desirable for high speed NLOS applications.

Super-resolution single-photon imaging at 8.2 kilometers.

Single-photon light detection and ranging (LiDAR), offering single-photon sensitivity and picosecond time resolution, has been widely adopted for active imaging applications. Long-range active imaging is a great challenge, because the spatial resolution degrades significantly with the imaging range due to the diffraction limit of the optics, and only weak echo signal photons can return but mixed with a strong background noise. Here we propose and demonstrate a photon-efficient LiDAR approach that can achieve sub-Rayleigh resolution imaging over long ranges. This approach exploits fine sub-pixel scanning and a deconvolution algorithm tailored to this long-range application. Using this approach, we experimentally demonstrated active three-dimensional (3D) single-photon imaging by recognizing different postures of a mannequin model at a stand-off distance of 8.2 km in both daylight and night. The observed spatial (transversal) resolution is ∼5.5 cm at 8.2 km, which is about twice of the system's resolution. This also beats the optical system's Rayleigh criterion. The results are valuable for geosciences and target recognition over long ranges.

High-speed robust polarization modulation for quantum key distribution.

Polarization modulation plays a key role in polarization-encoding quantum key distribution (QKD). Here, we report a new, to the best of our knowledge, polarization modulation scheme based on an inherently stable Sagnac interferometer. The presented scheme is free of polarization mode dispersion and calibration as well as insensitive to environmental influences. Successful experiments at a repetition frequency of 1.25 GHz have been conducted to demonstrate the feasibility and stability of the scheme. The measured average quantum bit-error rate of the four polarization states is as low as 0.27% for 80 consecutive minutes without any adjustment. This high-speed intrinsically stable polarization modulation can be widely applied to many polarization-encoding QKD systems, such as BB84, MDI, etc.

Bell Test over Extremely High-Loss Channels: Towards Distributing Entangled Photon Pairs between Earth and the Moon.

Quantum entanglement was termed "spooky action at a distance" in the well-known paper by Einstein, Podolsky, and Rosen. Entanglement is expected to be distributed over longer and longer distances in both practical applications and fundamental research into the principles of nature. Here, we present a proposal for distributing entangled photon pairs between Earth and the Moon using a Lagrangian point at a distance of 1.28 light seconds. One of the most fascinating features in this long-distance distribution of entanglement is as follows. One can perform the Bell test with human supplying the random measurement settings and recording the results while still maintaining spacelike intervals. To realize a proof-of-principle experiment, we develop an entangled photon source with 1 GHz generation rate, about 2 orders of magnitude higher than previous results. Violation of Bell's inequality was observed under a total simulated loss of 103 dB with measurement settings chosen by two experimenters. This demonstrates the feasibility of such long-distance Bell test over extremely high-loss channels, paving the way for one of the ultimate tests of the foundations of quantum mechanics.

Experimental free-space quantum key distribution with efficient error correction.

We report a 17-km free-space quantum key distribution (QKD) experiment using an engineering model of the space-bound optical transmitter and a ground station for satellite-ground QKD. The final key rate of ~ 0.5 kbps is achieved in this experiment with the quantum bit error rate (QBER) of ~ 3.4%. An efficient error correction algorithm, Turbo Code, is employed. Compared with the current error correction algorithm of Cascade, a high-efficiency error correction is realized by Turbo Code with only one-time data exchange. For a low QBER, with only one-time data exchange, the final key rates based on Turbo code are similar with Cascade. As the QBER increases, Turbo Code gives higher final key rates than Cascade. Our results experimentally demonstrate the feasibility of satellite-ground QKD and show that the efficient error correction based on Turbo Code is potentially useful for the satellite-ground quantum communication.

Satellite-to-ground quantum key distribution.

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

Segmentation and reconstruction of hepatic veins and intrahepatic portal vein based on the coronal sectional anatomic dataset.

Three-dimensional (3D) reconstruction of intrahepatic vessels is very useful in visualizing the complex anatomy of hepatic veins and intrahepatic portal vein. It also provides a 3D anatomic basis for diagnostic imaging and surgical operation on the liver. In the present study, we built a 3D digitized model of hepatic veins and intrahepatic portal vein based on the coronal sectional anatomic dataset of the liver. The dataset was obtained using the digital freezing milling technique. The pre-reconstructed structures were identified and extracted, and then were segmented by the method of manual intervention. The digitized model of hepatic veins and intrahepatic portal vein was established using 3D medical visualization software. This model facilitated a continuous and dynamic displaying of the hepatic veins and intrahepatic portal vein at different orientations, which demonstrated the complicated relationship of adjacent hepatic veins and intrahepatic portal vein realistically in the 3D space. This study indicated that high-quality 2D images, precise data segmentation, and suitable 3D reconstruction methods ensured the reality and accuracy of the digital visualized model of hepatic veins and intrahepatic portal vein.

Chemiluminescent detection of DNA hybridization using gold nanoparticles as labels.

A chemiluminescent (CL) detection method has been developed for DNA hybridization. The assay relies on a sandwich-type DNA hybridization in which gold nanoparticles modified with alkylthiol-capped oligonucleotide strands are used as probes to monitor the presence of the specific target DNA. The AuCl(4)(-), which is the dissolving product of the gold nanoparticles anchored on the DNA hybrids, serves as an analyte in the H(2)O(2)-luminol- AuCl(4)(-) CL reaction for the indirect measurement of the target DNA. The combination of the remarkable sensitivity of the CL analysis with the large number of AuCl(4)(-) released from each DNA hybrid allows a detection limit at levels as low as 0.1 pM of the target DNA. Moreover, with a further silver amplification step, the detection limit will be pushed down to the femtomolar domain.

A chemiluminescent metalloimmunoassay based on silver deposition on colloidal gold labels.

A sensitive chemiluminescent (CL) immunoassay of human immunoglobulin (IgG) which combined the inherent high sensitivity of CL analysis with the dramatic signal amplification of silver precipitation on colloidal gold tags was developed. First, the sandwich-type complex was formed in this protocol by the primary antibody immobilized on the polystyrene wells, the analyte in the sample, and the secondary antibody labeled with colloidal gold. Second, the colloidal gold was treated by an Ag(+) reduction solution, which resulted in the catalytic precipitation of silver on the surface of colloidal gold. Third, a large number of Ag(+) were oxidatively released in HNO(3) solution from the silver metal anchored on the sandwich-type complexes and then the human IgG was indirectly determined by a sensitive combined CL reaction of Ag(+)-K(2)S(2)O(8)-Mn(2+)- H(3)PO(4)-luminol. The chemiluminescence intensity depends linearly on the logarithm of the concentration of human IgG over the range of 0.02-50ngml(-1) and detection limit (3sigma) is 0.005ngml(-1) (i.e., approximately 3x10(-14)M, 3amol in 100-mul sample). This assay has been successfully applied to the determination of human IgG in human serum samples and showed great potential for numerous applications in immunoassay.

[Study on interaction of adriamycin and DNA with a resonance light scattering technique and its DNA analytical application].

The interaction of adriamycin (ADM) and DNA results in strongly enhanced resonance light scattering (RLS) spectra characterized by two peaks at 322 and 564 nm, respectively. The interaction of ADM and DNA was investigated by using absorption spectra, fluorescence spectra, and RLS spectra. The results indicate that RLS spectra have the highest sensitivity. It was found that the enhanced RLS intensity at 322 nm was proportional to the concentration of DNA in the range of 0-8.0 microg x mL(-1). An RLS method for the determination of DNA was accordingly described. The limit of determination was 36.8 and 40.1 ng x mL(-1) for calf thymus DNA and fish sperm DNA, respectively. The proposed method has a high sensitivity and good selectivity due to the specificity of the interaction of ADM and DNA.

[Determination of trace elements hg and Rh in gelatin by inductively coupled plasma emission spectrometry--applying MSF model to improve the precision and detection limit].

Using ICP-AES, the method was developed to quantitatively determine the trace elements Hg and Rh in gelatin for the first time. The unknown samplers were processed with the wet digestion method. Multiple trace elements in gelatin could be quantitatively determined by ICP-AES at the same time. Applying the MSF model, the method to correct the spectral interference and the background was discussed. The result's precision and detection limit could be greatly improved by MSF model. The results of the experiment showed that the method features high accuracy, rapidity, high performance and a wide linear dynamic range, and the results were very satisfactory.