PS Technique Research Articles

Comparison of purse-string technique vs linear suture for skin closure after ileostomy reversal. A randomized controlled trial.

Protective stoma after rectal surgery has been associated with important complications. The most common is surgical site infection (SSI) high rates after stoma reversal reported in literature. Our study compared the rate of SSI of two skin closure techniques, linear closure, and purse string closure. We carried out a single center, prospective, randomized controlled trial in the Department of Colorectal Surgery of Fondazione Policlinico Campus Bio-Medico of Rome between January 2018 through December 2021, to compare LC vs PS closure of ileostomy sites. A total of 117 patients (53.84% male) with a mean age of 65.68 ± 14.33years were finally evaluated in the study. 58 patients were included in the PS group and 59 patients in the LC one. There was a marked difference in the SSI rate between the two arms of the study: 3 of 58 patients in the purse-string arm versus 11 of 59 in the control arm (p = 0.043). The outcome of cosmesis was also higher in PS, with a statistical significance (mean ± DS 4,01 ± 0,73 for PS group vs mean ± DS 2,38 ± 0,72 for LC group, p < 0,001). Our study demonstrated that the PS technique had a significantly lower incidence of stoma site SSI compared with LC technique. Our findings are in line with other randomized studies and suggest that PS closure could be considered as standard of care for wound closure after ileostomy reversal.

Two-Lane DNN Equalizer Using Balanced Random-Oversampling for W-Band PS-16QAM RoF Delivery over 4.6 km

For W-band long-range mm-wave wireless transmission systems, nonlinearity issues resulting from photoelectric devices, optical fibers, and wireless power amplifiers can be handled by deep learning equalization algorithms. In addition, the PS technique is considered an effective measure to further increase the capacity of the modulation-constraint channel. However, since the probabilistic distribution of m-QAM varies with the amplitude, there have been difficulties in learning valuable information from the minority class. This limits the benefit of nonlinear equalization. To overcome the imbalanced machine learning problem, we propose a novel two-lane DNN (TLD) equalizer using the random oversampling (ROS) technique in this paper. The combination of PS at the transmitter and ROS at the receiver improved the overall performance of the W-band wireless transmission system, and our 4.6-km ROF delivery experiment verified its effectiveness for the W-band mm-wave PS-16QAM system. Based on our proposed equalization scheme, we achieved single-channel 10-Gbaud W-band PS-16QAM wireless transmission over a 100 m optical fiber link and a 4.6 km wireless air-free distance. The results show that compared with the typical TLD without ROS, the TLD-ROS can improve the receiver‘s sensitivity by 1 dB. Furthermore, a reduction of 45.6% in complexity was achieved, and we were able to reduce training samples by 15.5%. Considering the actual wireless physical layer and its requirements, there is much to be gained from the joint use of deep learning and balanced data pre-processing techniques.

Beyond 200 Gbit/s/λ VSB PS-PAM8 Employing Joint Neural Network Equalization at C-band

We experimentally demonstrate a high-speed vestigial sideband (VSB) probability shaping 8-ary pulse amplitude modulation (PS-PAM8) system at C-Band. The strong-coupled linear and nonlinear impairments in high-speed VSB transmission systems lead to performance degradation. Neural network-based equalization has been widely adopted in the optical transmission system. However, the effective combination of linear and nonlinear impairment compensation in NN equalization has not been discussed intensively. In this experiment, we have proposed an equalizer based on the joint neural network (JNN) to compensate for the linear and nonlinear impairments. With the proposed JNN equalizer and PS technique, 92 GBaud PS-PAM8 signals can be delivered over 10 km standard single mode fiber (SSMF). Given the forward error correction (FEC) overhead and the entropy of PS-PAM8 signals, the net bit rate can reach 207 Gbit/s/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> , satisfying the demand for a 200 Gbit/s/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> data connection.

124.8-Gbit/s PS-256QAM Signal Wireless Delivery Over 104 m in a Photonics-Aided Terahertz-Wave System

We experimentally demonstrate 16-GBaud probabilistic shaped 256-ary quadrature amplitude modulationsignal transmission over 104-m wireless distance at 339 GHz in a photonics-aided terahertz (THz)-wave communication system. Thanks to the pair of poly tetra fluoroethylene lenses and PS technique, we successfully achieve a record single line rate of 124.8 Gbit/s and net spectral efficiency of 6.2 bit/s/Hz. To the best of our current knowledge, it is the first time to achieve >100 m and >100 Gbit/s single-carrier 256QAM THz-wave signal wireless delivery.

352-Gbit/s single line rate THz wired transmission based on PS-4096QAM employing hollow-core fiber

We successfully demonstrate 32-Gbaud Probabilistically Shaped 4096-ary Quadrature Amplitude Modulation (PS-4096QAM) TeraHertz (THz) signal wired transmission at 325 ​GHz over the 1-m Hollow-Core Fiber (HCF) in a photon-assisted THz-wave communication system. By employing advanced Digital Signal Processing (DSP) and the PS technique, the 352-Gbit/s line rate (288-Gbit/s net rate) delivery with a net Spectral Efficiency (SE) of 9 bit/s/Hz is realized in the experiment, satisfying the 0.86-Normalized Generalized Mutual Information (NGMI) Low-Density Parity-Check (LDPC) threshold. © 2021 Elsevier Science. All rights reserved.

MER Signal Acquisition of STN-DBS Biomarkers in Parkinson`s: A machine learning auto regression approach

Microelectrode recording (MER) or microelectrode signals recording of local field potentials by means of subthalamic-nuclei deep brain stimulation is highly successful for construing or deducing Parkinson disease (PD) signal analysis acquiescent to elucidation are fetching ever more germane. These signals are supposed to emulate STN neurons action-potential movement and, these potential frequency modulations are coupled to spiking-events. The method uses auto regression stochastic (random nature) model machine learning approach and, other standard techniques as of system identification field. A usual conventional local field potential implication involves computing spectral-densities, i.e., power (P S Ds) of these signals—waveforms, that confines power on different frequencies. But, P S D s is second-order statistics might not confine non trivial temporal-dependencies which subsist in unprocessed data. Hence, we suggest L F Ps technique which is valuable in support of relating or unfolding distinctive plus sole features of temporal-dependencies in L F P waveforms. This technique is derived as of auto-regression (A R) modeling originating as of the systems plus control theory in fastidious systems-identification. We have distinctively, built A R models of L F P movement activity plus inferred, and also verified statistically major differentiations in temporal-dependencies among damaged tissues of nuclei plus protective areas in Parkinson`s receiving innocuous microelectrodes via deep brain stimulator (D BS). Differentiations in spectral-densities of field-waveforms amid the two conglomerates were not statistically-significant.

Wireless Powered Cooperative Communication Using Two Relays: Protocol Design and Performance Analysis

This paper develops an adaptive cooperative transmission scheme with relays harvesting wireless energy. Two relays are adopted to alternately forward source data to the destination using the two-path successive relaying (TPSR) protocol. When one relay forwards previous data along with source transmitting current data, using the power-splitting technique, the other relay will harvest energy and decode the current data from the received composite signal. If the TPSR cannot be performed due to the failure of data decoding at either relay, the decode-and-forward (DF) protocol will be performed by selecting a better relay. If one relay joins in the DF relaying, it will harvest energy and decode source data using the PS technique, while the other relay will always harvest energy from the received signal. If neither TPSR nor DF relaying can be performed, the source will transfer wireless power to both relays. The transmit powers of relays and the PS ratio are judiciously determined through analyzing the occurrence probability, average power fading, and success probability of each case. Numerical results show that our adaptive relaying scheme can achieve a much higher throughput than the single-relay DF scheme and the TPSR-only scheme.

APPLICATION OF EXTENDED KALMAN FILTER IN PERSISTANT SCATTERER INTERFEROMETRY TO ENHACE THE ACCURACY OF UNWRAPPING PROCESS

Abstract. In interferometry technique, phases have been modulated between 0-2π. Finding the number of integer phases missed when they were wrapped is the main goal of unwrapping algorithms. Although the density of points in conventional interferometry is high, this is not effective in some cases such as large temporal baselines or noisy interferograms. Due to existing noisy pixels, not only it does not improve results, but also it leads to some unwrapping errors during interferogram unwrapping. In PS technique, because of the sparse PS pixels, scientists are confronted with a problem to unwrap phases. Due to the irregular data separation, conventional methods are sterile. Unwrapping techniques are divided in to path-independent and path-dependent in the case of unwrapping paths. A region-growing method which is a path-dependent technique has been used to unwrap PS data. In this paper an idea of EKF has been generalized on PS data. This algorithm is applied to consider the nonlinearity of PS unwrapping problem as well as conventional unwrapping problem. A pulse-pair method enhanced with singular value decomposition (SVD) has been used to estimate spectral shift from interferometric power spectral density in 7*7 local windows. Furthermore, a hybrid cost-map is used to manage the unwrapping path. This algorithm has been implemented on simulated PS data. To form a sparse dataset, A few points from regular grid are randomly selected and the RMSE of results and true unambiguous phases in presented to validate presented approach. The results of this algorithm and true unwrapped phases were completely identical.

Atmospheric phase screen correction in ground-based SAR with PS technique.

Ground-based synthetic aperture radar (GBSAR) is a powerful tool used in monitoring structures, such as bridges and dams. However, despite the extremely short range of GBSAR interferometry, the atmosphere effects cannot be neglected. The permanent scatterer technique is an effective operational tool that utilizes a long series of SAR data and detects information with high accuracy. An algorithm based on the permanent scatterer technique is developed in accordance with the phase model used in GBSAR interferometry. In this study, atmospheric correction is carried out on a real campaign (Geheyan Dam, China). The atmosphere effects created using this method, which utilizes SAR data, can be reduced effectively compared to when plumb line data are used.

Internalization of the PDZ and its photodynamic effect on the growth of ATCC and clinical strains of E. coli and S. aureus

The treatment of bacterial infections has been a challenge after the end of the ‘era of antibiotics’. Bacteria are capable of causing many infectious diseases; therefore, with the increasing number of bacteria becoming resistant, development of alternative therapies is needed to minimize, or even eliminate the use of antibiotics. Photodynamic therapy (PDT) is a promising alternative to fight microorganism. In view of the increasing emergence of resistant bacteria and the limitations of conventional treatment, this study evaluated the effect of photodynamic therapy with photodithazine (PDZ) in inactivating bacterial strains of E. coli and S. aureus in vitro, comparing the behavior of clinical and ATCC strains. Confocal microscopy analysis was performed to determine the internalization of the PS and spectrophotometric technique was used to determine the growth of bacteria in vitro. PDT using PDZ was able to reduce the growth of S. aureus strains using the incubation time of 24 h, whereas no satisfactory results were obtained with 15 min incubation. The E. coli strains, tested at two incubation times, did not affectively reduce bacterial growth. Therefore, it is concluded that PDT using PDZ is viable when applied to the S. aureus strains, when suitable incubation times are used.

Modélisation par éléments finis de l’ostéosynthèse rachidienne cervicale postérieure

Background contextDespite largely, used in the past, biomechanical test, to investigate the fixation techniques of subaxial cervical spine, information is lacking about the internal structural response to external loading. It is not yet clear which technique represents the best choice and whether stabilization devices can be efficient and beneficial for three-column injuries (TCI). HypothesisThe different posterior cervical fixation techniques (pedicle screw PS, lateral mass screw LS, and transarticular screw TS) have respective indications. Materials and methodsA detailed, geometrically accurate, nonlinear C3–C7 finite element model FEM had been successfully developed and validated. Then three FEMs were reconstructed from different fixation techniques after C4–C6 TCI. A compressive preload of 74N combined with a pure moment of 1.8 Nm in flexion, extension, left–right lateral bending, and left–right axial rotation was applied to the FEMs. ResultsThe ROM results showed that there were obvious significant differences when comparing the different fixation techniques. PS and TS techniques can provide better immediate stabilization, compared to LS technique. The stress results showed that the variability of von Mises stress in the TS fixation device was minimum and LS fixation device was maximum. Furthermore, the screws inserted by TS technique had high stress concentration at the middle part of the screws. Screw inserted by PS and LS techniques had higher stress concentration at the actual cap–rod–screw interface. ConclusionsThe research considers that spinal surgeon should first consider using the TS technique to treat cervical TCI. If PS technique is used, we should eventually prolong the need for external bracing in order to reduce the higher risk of fracture on fixation devices. If LS technique is used, we should add anterior cervical operation for acquire a better immediate stabilization.

Finite element analysis of posterior cervical fixation

Background contextDespite largely, used in the past, biomechanical test, to investigate the fixation techniques of subaxial cervical spine, information is lacking about the internal structural response to external loading. It is not yet clear which technique represents the best choice and whether stabilization devices can be efficient and beneficial for three-column injuries (TCI). HypothesisThe different posterior cervical fixation techniques (pedicle screw PS, lateral mass screw LS, and transarticular screw TS) have respective indications. Materials and methodsA detailed, geometrically accurate, nonlinear C3–C7 finite element model (FEM) had been successfully developed and validated. Then three FEMs were reconstructed from different fixation techniques after C4–C6 TCI. A compressive preload of 74N combined with a pure moment of 1.8 Nm in flexion, extension, left–right lateral bending, and left–right axial rotation was applied to the FEMs. ResultsThe ROM results showed that there were obvious significant differences when comparing the different fixation techniques. PS and TS techniques can provide better immediate stabilization, compared to LS technique. The stress results showed that the variability of von Mises stress in the TS fixation device was minimum and LS fixation device was maximum. Furthermore, the screws inserted by TS technique had high stress concentration at the middle part of the screws. Screw inserted by PS and LS techniques had higher stress concentration at the actual cap–rod–screw interface. ConclusionsThe research considers that spinal surgeon should first consider using the TS technique to treat cervical TCI. If PS technique is used, we should eventually prolong the need for external bracing in order to reduce the higher risk of fracture on fixation devices. If LS technique is used, we should add anterior cervical operation for acquire a better immediate stabilization.

Fuzzy ruling between core porosity and petrophysical logs: Subtractive clustering vs. genetic algorithm–pattern search

Abstract Porosity, the void portion of reservoir rocks, determines the volume of hydrocarbon accumulation and has a great control on assessment and development of hydrocarbon reservoirs. Accurate determination of porosity from core analysis is highly cost, time, and labor intensive. Therefore, the mission of finding an accurate, fast and cheap way of determining porosity is unavoidable. On the other hand, conventional well log data, available in almost all wells contain invaluable implicit information about the porosity. Therefore, an intelligent system can explicate this information. Fuzzy logic is a powerful tool for handling geosciences problem which is associated with uncertainty. However, determination of the best fuzzy formulation is still an issue. This study purposes an improved strategy, called hybrid genetic algorithm–pattern search (GA–PS) technique, against the widely held subtractive clustering (SC) method for setting up fuzzy rules between core porosity and petrophysical logs. Hybrid GA–PS technique is capable of extracting optimal parameters for fuzzy clusters (membership functions) which consequently results in the best fuzzy formulation. Results indicate that GA–PS technique manipulates both mean and variance of Gaussian membership functions contrary to SC that only has a control on mean of Gaussian membership functions. A comparison between hybrid GA–PS technique and SC method confirmed the superiority of GA–PS technique in setting up fuzzy rules. The proposed strategy was successfully applied to one of the Iranian carbonate reservoir rocks.

Direct Thrombus Retrieval Using the Reperfusion Catheter of the Penumbra System: Forced-Suction Thrombectomy in Acute Ischemic Stroke

Although the PS has been the most promising mechanical thrombectomy device in terms of recanalization rates, even the PS cannot recanalize all cases of occlusion. Under such circumstances, we simply modified the PS, identified certain advantages, and applied this modification as a primary technique for recanalization. Here we describe and discuss the technical details and results of our preliminary experience. This study included 22 consecutive patients with acute ischemic stroke secondary to large-artery occlusion who underwent modified thrombectomy by using the PS for recanalization. Direct wedging between the tip of the reperfusion catheter and the proximal part of the clot followed by forceful suction by using a 20- or 50-mL syringe is a unique feature of this technique. What is distinctive is that this does not require use of a separator or aspiration pump. All treated vessels (100%) were successfully recanalized. A TICI scale of 2b or 3 was achieved in 81.9% of patients. A 3-month favorable functional outcome (mRS score, 0-2) was achieved in 45.5% of patients. The only procedural complication was a transient dissection of the proximal ICA, which developed while advancing the guide catheter. Forced-suction thrombectomy is a simple modification of the PS. On the basis of our data, this technique allows safe and effective revascularization in acute large-vessel occlusion. Thus, for achieving the best outcome, the modified PS technique is proposed as a viable option for acute stroke management, either by itself or in conjunction with other devices or drugs.

Mitigation of Atmospheric Water-vapour Effects on Spaceborne Interferometric SAR Imaging through the MM5 Numerical Model

Synthetic Aperture Radar (InSAR) imaging is a well established technique to derive useful products for several land applications. One of the major limitations of InSAR is due to atmospheric efiects, and in particular to high water vapor variability. In this work, we make an experimental analysis to research the capability of Numerical Weather Prediction (NWP) models as MM5 to produce high resolution (1km{500m) maps of Integrated Water Vapor (IWV) in the atmosphere to mitigate the well-known disturbances that afiect the radar signal while traveling from the sensor to the ground and back. Experiments have been conducted over the area surrounding Rome using ERS data acquired during the three days phase in '94 and using Envisat data acquired in recent years. By means of the PS technique SAR data have been processed and the Atmospheric Phase Screen (APS) of Slave images with respect to a reference Master have been extracted. MM5 provides realistic water vapor distribution flelds that can be converted into electromagnetic slant delays. PSInSAR APS's have then been compared to MM5 IWV maps revealing interesting results. MM5 IWV maps have a much lower resolution than PSInSAR APS's: the turbulent term of the atmospheric vapor fleld cannot be well resolved by MM5, at least with the low resolution ECMWF inputs. However, the vapor distribution term that depends on the local topography has been found quite in accordance. In this work, we will present experimental results as well as discussions over the adopted processing strategy.

D-InSAR Technique for Land Subsidence Monitoring

The land subsidence has been a global disastrous problem, and the conventional geodetic technique is highly incompetent in the large-scale and serious land deformation monitoring. The D-InSAR technique has been widely applied and deeply researched in the field of the land deformation monitoring. This article first puts forward one of the methods known as time series radar interferometry based on permanent scatterers technique, and then, applies the time series analysis method into D-InSAR. This paper takes the phase difference of two nearer permanent scatterers in an interferogram as research object; therefore, the atmospheric delay impact can be eliminated. In the research, there are several steps including preprocessing radar images, selecting the PS points, combination of PS points, computing the variance of the phase difference for two PS points, integer least-squares adjustment, obtaining land subsidence velocity and so forth. The land subsidence data and the distribution map obtained in this paper by adapting this method to the experiment of Tianjin area subsidence monitoring have been proved to be satisfactory. The method for eliminating the atmospheric delay impact accurately has been realized by combining the time seriesmethod with PS technique. At the same time, it was confirmed that the time series for InSAR is a feasible and effective method for monitoring land deformation. Moreover, it can be concluded from the result obtained in the paper that the selection of PS points is so important that it is worthy studying further on.

Stress Dependence of Optically Active Diamagnetic Point Defects in Silicon Oxynitride

The cathodoluminescence (CL) spectrum arising from diamagnetic point defects of silicon oxynitride lattice was analyzed to extract quantitative information on local stress fields stored on the surface of a silicon nitride polycrystal. A calibration procedure was preliminarily made to obtain a relationship between CL spectral shift and applied stress, according to the piezo-spectroscopic effect. In this calibration procedure, we used the uniaxial stress field developed in a rectangular bar loaded in a four-point flexural jig. Stress dependence was clearly detected for the most intense spectral band of a doublet arising from diamagnetic ([triple bond]Si-Si[triple bond]) defects, which was located at around 340 nm. The shallow nature of the electron probe enabled the characterization of surface stress fields with sub-micrometer-order spatial resolution. As applications of the PS technique, the CL emission from [triple bond]Si-Si[triple bond] defects was used as a stress probe for visualizing the residual stress fields stored at grain-boundary regions and at the tip of a surface crack propagated in polycrystalline silicon nitride.

Satellite observation of coal mining subsidence by persistent scatterer analysis

Ground subsidence persistently occurs in abandoned coal mining areas. This paper presents an investigation of ground subsidence measurement using persistent scatterers recorded by space-borne synthetic aperture radar (SAR). During the period from November 1992 to October 1998, twenty-five JERS-1 SAR interferometric pairs were obtained and used to measure subsidence in the Gaeun coal mining area, Korea. To validate the subsidence estimated by the persistent scatterers SAR interferometry (PS technique), the results were compared with the degree of crack level obtained by a 1997 field survey. The study area was divided into five classes based on measured crack levels. The line-of-sight (LOS) subsidence rate of each group was estimated by the phase of 135 scatterers selected from the five classes. The maximum subsidence was measured by radar as 11.2 cm over 6 yr. The mean subsidence rate of one class was found to be 0.5 cm/yr where cracks most severely developed. The radar-estimated subsidence agrees well with the degree of crack level. The PS technique is useful for the measurement of ground subsidence in abandoned coal mining areas, even in mountainous regions.

Use of Permanent Scatterers technique for large-scale mass movement investigation

In the Oltrepo Pavese (Northern Italy), several areas subjected to risk assessment according to Italian law are located around a highly fractured sandstone slabs (M. Vallassa Sandstone) lying on a deformable clayey substratum (Epiligurian Sequence). The structural and geomorphologic surveys and comparison with results obtained by some authors in similar geological contexts indicate the possible presence of deep-seated gravitational deformations, which could be classified as lateral spread. The potentiality of the Permanent Scatterers technique has been explored by the authors for investigating large slope displacements in the Oltrepo Pavese. The Permanent Scatterers analysis was combined with in situ conventional geomorphological, structural and geotechnical studies. Test sites, corresponding to sandstone slabs and areas classified at high risk from the institutional authorities, were selected. A geological model of each test area was obtained from the integration of the geological–geomorphological character of the site with the geotechnical data (boreholes, piezometers and laboratory tests). The PS technique allows to detect and delimit the unstable area and to identify some zones within the mass movement characterized by different displacements rates, and thus different degree of hazard.

Preparation of Nitride Fuel by Spark Plasma Sintering Technique

AbstractSPS technique was applied for fabrication of UN pellets. The dense sample was obtained with relatively low sintering temperature without any milling process and sintering additive, indicating that the SPS technique is suitable for fabrication of nitride fuel. The thermal conductivity and Young's modulus in axial direction were higher than those of reported values. EBSP analysis and electronic calculation supposed that weak grain orientation in [100] direction of the sample lead to these higher values.