Measuring the orbital angular momentum of generalized higher-order twisted partially coherent beams.

Recently a new family of partially coherent fields incorporating generalized inseparable cross-coupled phases named generalized higher-order twisted partially coherent beams (GHTPCBs) have been introduced. The twist factor u is a key parameter that not only quantifies the strength of the generalized cross-coupled phase for a given order, but also determines the amount of the concomitant orbital angular momentum (OAM). In this paper, we propose a simple and reliable method to measure the factor u using a two-pinhole mask. Without need of complicated optical system, it only requires to capture the far-field diffraction intensity distribution of the GHTPCB passing through the mask. By analyzing the Fourier spectrum of the intensity distribution, the value of twist factor can be derived nearly in real time. The influence of the separation distance between two pinholes and the pinholes' diameter and position on the measurement accuracy are thoroughly studied both in theory and experiment. The experimental results agree well with the theoretical results. Our methodology can also be extended to measure the sole factor of similar position dependent phases such as the topological charge of a vortex phase.

Transthoracic single-port-assisted laparoscopic gastrectomy versus laparoscopic transhiatal approach for Siewert type II adenocarcinoma of the esophagogastric junction: a single-center retrospective study.

BACKGROUND: The surgical approach for patients with Siewert type II AEG remains controversial. Several studies have described a new laparoscopic radical resection approach of Siewert type II AEG through the left diaphragm. However, the technical safety and feasibility of the new surgical approach compared with the transhiatal approach have not yet been tested. STUDY DESIGN: We retrospectively reviewed patients with AEG who underwent TSLG and LTH operations in the Guangdong Provincial Hospital of Chinese Medicine between January 2017 and April 2021. Histologically confirmed AEG and D2 lymphadenectomy with curative R0 patients were included, and patients with Siewert I/III AEG or distant metastasis were excluded. Blood loss, the amount of harvested lymph node, and complications related to surgery were evaluated. RESULTS: A total of 99 patients with Siewert type II AEG were analyzed, 44 in the TSLG group and 55 in the LTH group. There was no difference in clinicopathological features between the two groups. The more harvested lymph node (23.33 ± 11.41 vs. 32.18 ± 12.85, p < 0.01), lower mediastinal lymph node (1.07 ± 2.08 vs. 3.25 ± 3.31, p < 0.01), and longer proximal margin length (3.08 ± 1.19 vs. 4.47 ± 0.95 cm, p < 0.01) were observed in the TSLG group. The rate of cure (R0 gastrectomy) in the TSLG group was higher than that in the LTH group (100% vs. 89.09%, p = 0.03). CONCLUSION: The TSLG approach is associated with improved surgical views, simplified lymphatic dissection in the inferior mediastinum, and more reliable margins. TSLG surgery may be an effective addition to LTH surgery, particularly when lower mediastinal lymph node metastases are suspected.

Second-order statistics of a Hermite-Gaussian correlated Schell-model beam carrying twisted phase propagation in turbulent atmosphere.

We investigate the second-order statistics of a twisted Hermite-Gaussian correlated Schell-model (THGCSM) beam propagation in turbulent atmosphere, including the spectral density, degree of coherence (DOC), root mean square (r.m.s.) beam wander and orbital angular momentum (OAM) flux density. Our results reveal that the atmospheric turbulence and the twist phase play a role in preventing the beam splitting during beam propagation. However, the two factors have opposite effects on the evolution of the DOC. The twist phase preserves the DOC profile invariant on propagation, whereas the turbulence degenerates the DOC. In addition, the influences of the beam parameters and the turbulence on the beam wander are also studied through numerical examples, which show that the beam wander can be reduced by modulating the initial parameters of the beam. Further, the behavior of the z-component OAM flux density in free space and in atmosphere is thoroughly examined. We show that the direction of the OAM flux density without the twist phase will be suddenly inversed at each point across the beam section in the turbulence. This inversion only depends on the initial beam width and the turbulence strength, and in turn, it offers an effective protocol to determine the turbulence strength by measuring the propagation distance where the direction of OAM flux density is inversed.

Status and influencing factors of lower limb amputation in patients with diabetic foot ulcer.

To investigate the influencing factors of lower limb amputation in patients with diabetic foot ulcers. Patients with diabetic foot ulcers who were hospitalised in a tertiary general hospital in Guizhou Province from January 2019 to March 2022 were retrospectively collected. Sociological information of the general population, comorbidities, laboratory-related indicators, and information on the specialty situation, using univariate analysis and multifactor analysis, compared the influencing factors of amputation and non-amputee patients. A total of 205 patients with diabetic foot and 69 ampute patients (33.7%) were enrolled. The univariate analysis found that the decrease in HDL cholesterol levels was associated with the occurrence of lower extremity amputation, and logistic stepwise regression analysis showed that HDL-C was inversely correlated with the amputation rate of patients with diabetic foot ulcers, and the risk of amputation at low levels of HDL-C was 2.452 times higher than that of high-level HDL-C (95% CI: 1.105-5.846). Decreased HDL cholesterol levels are an independent predictor of amputation in patients with diabetic foot ulcers.

Combined transcriptome and metabolome analysis revealed pathways involved in improved salt tolerance of Gossypium hirsutum L. seedlings in response to exogenous melatonin application.

BACKGROUND: Salinization is major abiotic stress limiting cotton production. Melatonin (MT) has been implicated in salt stress tolerance in multiple crops including upland cotton. Here, we explored the transcriptomic and metabolomic response of a salt-tolerant self-bred high-yielding cotton line SDS-01, which was exogenously sprayed with four MT concentrations (50, 100, 200, and 500 µM). RESULTS: Here we found that MT improves plant biomass and growth under salt stress. The combined transcriptome sequencing and metabolome profiling approach revealed that photosynthetic efficiency is improved by increasing the expressions of chlorophyll metabolism and antenna proteins in MT-treated seedlings. Additionally, linoleic acid and flavonoid biosynthesis were improved after MT treatment. The Na+/K+ homeostasis-related genes were increasingly expressed in salt-stressed seedlings treated with MT as compared to the ones experiencing only salt stress. Melatonin treatment activated a cascade of plant-hormone signal transduction and reactive oxygen scavenging genes to alleviate the detrimental effects of salt stress. The global metabolome profile revealed an increased accumulation of flavonoids, organic acids, amino acids and derivatives, saccharides, and phenolic acids in MT-treated seedlings. Interestingly, N, N'-Diferuloylputrescine a known antioxidative compound was highly accumulated after MT treatment. CONCLUSION: Collectively, our study concludes that MT is a salt stress regulator in upland cotton and alleviates salt-stress effects by modulating the expressions of photosynthesis (and related pathways), flavonoid, ROS scavenging, hormone signaling, linoleic acid metabolism, and ion homeostasis-related genes.

Radially polarized twisted partially coherent vortex beams.

We introduce a new type of partially coherent vector beam, named the radially polarized twisted partially coherent vortex (RPTPCV) beam. Such a beam carries the twist phase and the vortex phase simultaneously, and the initial state of polarization (SOP) is radially polarized. On the basis of the pseudo-modal expansion and fast Fourier transform algorithm, the second-order statistics such as the spectral density, the degree of polarization (DOP) and the SOP, propagation through a paraxial ABCD optical system are investigated in detail through numerical examples. The results reveal that the propagation properties of the RPTPCV beam closely depends on the handedness of the twist phase and the vortex phase. When the handedness of the two phases is same, the beam profile is easier to remain a dark hollow shape and the beam spot rotates faster during propagation, compared to the partially coherent vortex beam or the RPTPCV beam with the opposite handedness of the two phases. In addition, the same handedness of two phases resists the coherence induced de-polarization of the beam upon propagation, and the SOP is also closely related to the handedness, topological charge of the vortex phase and the twist factor of the twist phase, providing an efficient way to modulate the beam's DOP and SOP in the output plane. Moreover, we establish an experiment setup to generate the RPTPCV beam. The average spectral density and the polarization properties are examined in the experiment. The experimental results agree reasonable well with the theoretical predictions. Our results will be useful for particle manipulating, free-space optical communications, and polarization lidar systems.

Twisted elliptical multi-Gaussian Schell-model beams and their propagation properties: reply.

The correction pointed out by Nemes [J. Opt. Soc. Am. A39, 667 (2022)JOAOD60740-323210.1364/JOSAA.435756] to our paper [J. Opt. Soc. Am. A37, 89 (2020)JOAOD60740-323210.1364/JOSAA.37.000089] is welcome. The author claims that the beam propagation factors Mx2, My2 are inadequate to characterize twisted elliptical multi-Gaussian Schell-model (TEMGSM) beams, which are introduced in our paper. Further, the author points out that there are two pairs of independent, normalized invariants to classify the TEMGSM beams. In this reply, we present the numerical example of the normalized intrinsic propagation invariants of the TEMGSM beams.

Polar-UEP spinal concatenated encoding in free-space optical communication.

Aiming at the poor bit error rate (BER) performance of spinal code in free-space optical communication, a polar-UEP (unequal error protection) spinal concatenated coding scheme for free-space optical communication is proposed. This work combines the unequal error protection characteristics of spinal codes and the construction characteristics of polar codes, using bit sorting and interleaving, to give the best protection of the polar code's information bits, and the bits that are prone to error. Simulation results show that the bit error rate performance of the more important bits and the less important bits of the polar-UEP spinal concatenated code is better than that of the spinal code. When the turbulence intensity is 0.1, compared with the fixed rate coding scheme such as the polar code, the concatenated code generates 0.7 dB-1.2 dB gain at a BER of 10-4. Besides, its BER under different turbulence intensity is lower than that of the spinal code and polar code, and this provides a solution for the efficient application of the spinal code in free-space optical communication.

Research on Performance of Cooperative FSO Communication System Based on Hierarchical Modulation and Physical Layer Network Code.

To solve the problem that the channel conditions in asymmetric cooperative FSO communication systems are not fully utilized, and the data reliability deteriorates due to high-order modulation, we proposed a layered modulation, joint physical-layer network coding scheme. In this scheme, we first designate the data priority of the information to be transmitted at the source node. Then, the transmission power of different proportions is allocated to the data based on its priority. Then, the modulated data is sent to each node, and physical-layer network coding is performed on the received data at the relay node. Finally, the relay node sends the encoded information to the destination node, and the destination node recovers the original information using the physical-layer network coding scheme. The simulation results showed that when the average signal-to-noise ratio of the channel was 15 dB, the BER of the cooperative FSO communication system could be reduced to below 10-8. In the strong atmospheric turbulence channel, the cooperative FSO communication system can obtain a signal-to-noise ratio gain of about 1.5 dB. Under strong atmospheric turbulence, this scheme could also improve the average channel capacity performance of a cooperative FSO communication system.

Energy Efficiency Optimization for SWIPT-Enabled IoT Network with Energy Cooperation.

As an advanced technology, simultaneous wireless information and power transfer (SWIPT), combined with the internet of things (IoT) devices, can effectively extend the online cycle of the terminal. To cope with the fluctuation of energy harvesting by the hybrid access points (H-AP), the energy cooperation base station is introduced to realize the sharing of renewable energy. In this paper, we study the SWIPT-enabled IoT networks with cooperation. Our goal is to maximize the energy efficiency of the system, and at the same time, we need to meet the energy harvesting constraints, user quality of service (QoS) constraints and transmission power constraints. We jointly solve the power allocation, time switching and energy cooperation problems. Because this problem is a nonlinear programming problem, it is difficult to solve directly, so we use the alternating variable method, the iterative algorithm is used to solve the power allocation and time switching problem, and the matching algorithm is used to solve the energy cooperation problem. Simulation results show that the proposed algorithm has obvious advantages in energy efficiency performance compared with the comparison algorithm. At the same time, it is also proved that the introduction of energy cooperation technology can effectively reduce system energy consumption and improve system energy efficiency.

Self-reconstruction of twisted Laguerre-Gaussian Schell-model beams partially blocked by an opaque obstacle.

Twisted Laguerre-Gaussian Schell model (TLGSM) beams are a novel type of partially coherent beams, which carry the twist phase and the vortex phase simultaneously. In this paper, the self-reconstruction (SR) of the TLGSM beam partially blocked by an opaque obstacle and propagating through a thin lens focusing system is studied in detail. Implementing the pseudo-mode expansion method, we represent the TLGSM beam as a superposition of spatially coherent modes, which is applicable for calculating the cross spectral density (CSD) and spectral degree of coherence (SDOC) of such a beam using the Fourier transform. The numerical results reveal that the twist parameter, a measure of the strength of a twist phase, determines the characteristics of the SR. In the case of the topological charge of the vortex is positive, the SR capability of spectral density is significantly improved with the increase of the twist parameter. The physical mechanism behind these phenomena is analyzed in detail from the point view of mode expansion. Further, the dependence of the side ring intensity and SR capability of the SDOC on the twist parameter are also investigated. It is found that the SR capability and side ring intensity of the SDOC are simultaneously enhanced for a large twist parameter, providing an efficient way to determine the number of topological charge. Our study results may find application in communication and information recovery applications.

Twisted elliptical multi-Gaussian Schell-model beams and their propagation properties.

We introduce a new kind of partially coherent source whose cross-spectral density (CSD) function is described as the incoherent superposition of elliptical twisted Gaussian Schell-model sources with different beam widths and transverse coherence widths, named twisted elliptical multi-Gaussian Schell-model (TEMGSM) beams. Analytical expression for the CSD function propagating through a paraxial ABCD optical system is derived with the help of the generalized Collins formula. Our results show that the TEMGSM beam is capable of generating a flat-topped elliptical beam profile in the far field, and the beam spot during propagation exhibits clockwise/anti-clockwise rotation with respect to its propagation axis. In addition, the analytical expressions for the orbital angular momentum (OAM) and the propagation factor are also derived by means of the Wigner distribution function. The influences of the twisted factor and the beam index on the OAM and the propagation factor are studied and discussed in detail.

Generating bona fide twisted Gaussian Schell-model beams.

We experimentally realize bona fide twisted Gaussian Schell-model (TGSM) beams by converting an anisotropic GSM beam into a TGSM beam with a set of just three cylindrical lenses. In contrast to the previously reported experimental technique for generating TGSM beams, we are able to explicitly generate anisotropic GSM beams with simultaneously controlled beam widths and transverse coherence lengths along two mutually orthogonal directions, prior to converting them to genuine TGSM beams.

Twisted Laguerre-Gaussian Schell-model beam and its orbital angular moment.

It is well known that a light beam with vortex phase or twist phase carries orbital angular momentum (OAM), while twist phase only exists in a partially coherent beam. In this paper, we introduce a new partially coherent beam, named twisted Laguerre-Gaussian Schell-model (TLGSM) beam. This TLGSM beam carries both vortex phase and twist phase. Further, the evolutional properties of the spectral density and spectral degree of coherence (SDOC)] of the TLGSM beam passing through a paraxial ABCD optical system are explored in detail. Our results reveal that the vortex and twist phases' handedness significantly affects the evolution properties. When the twist phase's handedness is the same as that of the vortex phase, the beam profile maintains a dark hollow shape during propagation and the side rings in SDOC are suppressed; however, when the handedness of two phases is opposite, then the beam shape evolves into a Gaussian shape and the side rings in SDOC are enhanced. Furthermore, we obtain the analytical expression for the OAM of the TLGSM beam. It is found that the vortex phase's and twist phase's contributions to the OAM are interrelated, which greatly increases the amount of OAM. In addition, the OAM variation of the TLGSM beam passing through an anisotropic optical system is also explored in detail. Our results will be useful for information transfer and optical manipulations.

High-quality partially coherent Bessel beam array generation: erratum.

In this erratum, we correct mistakes in Eqs. (6), (8), and (9), typo in Eq. (11), as well as lattice period magnitudes and units in Fig. 1. We also update the funding information in Opt. Lett.43, 3188 (2018)OPLEDP0146-959210.1364/ol.43.003188.

High-quality partially coherent Bessel beam array generation.

We propose a protocol for generating high-quality, partially coherent (quasi-)Bessel beam arrays with controllable beam order and spatial distributions. Our protocol involves, apart from beam intensity shaping, coherence engineering of recently introduced optical coherence lattices. Our theoretical results are validated with the experimental realization of partially coherent Bessel beam arrays. The novel beam arrays are anticipated to be useful for multi-particle trapping and micromanipulation, optical metrology and microscopy, as well as for 3D imaging.

NPTX1 inhibits colon cancer cell proliferation through down-regulating cyclin A2 and CDK2 expression.

Colon cancer is the third most common malignancy and one of the leading causes of cancer-associated mortality worldwide. Neuronal pentraxin 1 (NPTX1) is associated with tumor progression in some types of tumors. However, its expression and role in colon cancer has not been yet reported. Here we observed that NPTX1 was down-regulated in colon cancer. Additionally, we explored the functional significance of NPTX1 in colon cancer. We found that over-expression of NPTX1 inhibited colon cancer cell growth by performing MTT, colony formation, Edu corporation assays, and cell cycle analysis. In vivo mouse experiments also confirmed the anti-proliferative role of NPTX1 in colon cancer. Further mechanistic study showed that over-expression of NPTX1 inhibited the expression of cyclin A2 and CDK2 in colon cancer cells, thereby regulating the Rb-E2F signaling. In summary, these findings reveal that NPTX1 suppress the colon cancer cell growth and might serve as a useful potential target for treatment of colon cancer.

Efficient tensor approach for simulating paraxial propagation of arbitrary partially coherent beams.

Complicated partially coherent beams (PCBs) are useful in many applications, such as free-space optical communications, particle trapping and optical imaging, while usually it is hard to derive analytical propagation formulae for such beams, and one has to fall back on numerical methods. The conventional numerical methods have some intrinsic drawbacks. In this paper, we introduce an efficient tensor approach (ETA) for simulating paraxial propagation of arbitrary PCBs. The ETA is a direct reconstruction of the propagated PCB without aliasing and rippling problems, and the algorithm is simple and robust with a tensor/matrix multiplication as the main calculation. The validity of ETA is verified through comparing simulation results with analytical results, numerical integration results and experimental results, respectively. The ETA provides a fast and reliable way for simulating paraxial propagation of arbitrary PCBs.

Wideband tunable optoelectronic oscillator based on the deamplification of stimulated Brillouin scattering.

A wideband tunable optoelectronic oscillator (OEO) based on the deamplification of stimulated Brillouin scattering (SBS) is proposed and experimentally demonstrated. A tunable single passband microwave photonic filter (MPF) utilizing phase modulation and SBS deamplification is used to realize the tunability of the OEO. Theoretical analysis of the MPF and phase noise performance of the OEO are presented. The frequency response of the MPF is determined by the + 1st sideband attenuation due to SBS deamplification and phase shift difference between the two sidebands due to chromatic dispersion and SBS. The close-in (< 1 MHz) phase noise of the proposed OEO is shown to be dominated by the laser frequency noise via phase shift of SBS. The conversion of the laser frequency noise to the close-in phase noise of the proposed OEO is effectively reduced compared with the OEO based on amplification by SBS. Tunable 7 to 40 GHz signals are experimentally obtained. The single-sideband (SSB) phase noise at 10 kHz offset is -128 dBc/Hz for 10.30 GHz signal. Compared with the OEO based on SBS amplification, the proposed OEO can achieve a phase noise performance improvement beyond 20 dB at 10 kHz offset. The maximum frequency and power drifts at 10.69 GHz are within 1 ppm and 1.4 dB during 1000 seconds, respectively. To achieve better close-in phase noise performance, lower frequency noise laser and higher pump power are preferred. The experimental results agree well with the theoretical models.

Statistical properties of a radially polarized twisted Gaussian Schell-model beam in an underwater turbulent medium.

Average intensity and the normalized powers of the completely polarized and the completely unpolarized portions of a radially polarized twisted Gaussian Schell-model (TGSM) beam propagating in underwater turbulence are examined. In our formulation, our previously obtained atmospheric turbulence solution for the same radially polarized TGSM beam using the extended Huygens-Fresnel principle is utilized, with the inclusion of our recently derived expression for the atmospheric turbulence structure constant in terms of underwater turbulence parameters. Effects of the rate of dissipation of mean-squared temperature, rate of dissipation of kinetic energy per unit mass of fluid, kinematic viscosity, and the contribution of the temperature-to-salinity ratio to the refractive index spectrum on the average intensity, and the normalized powers of the completely polarized and completely unpolarized portions of a radially polarized TGSM beam propagating in underwater turbulence are presented.