Purpose
The aim of this study was to develop and validate a nomogram to assist physicians making further decisions on the requirement of a radical surgery for T1 colorectal cancer (CRC) after local ...excision through preoperative prediction of lymph node metastasis (LNM).
Methods
A total of 141 T1 CRC patients were enrolled from January 2013 to August 2020. The independent predictive parameters were determined in multivariate analyses. The nomogram was constructed based on predictors of LNM and its performance was evaluated with respect to its calibration, discrimination, and decision curve analysis. Internal validation by bootstrapping was performed to verify the applicability of the nomogram.
Results
cN in CT/MRI (N+), histologic type (poorly differentiated, mucinous adenocarcinoma, and signet-ring cell carcinoma), tumor budding (G3), and lymphovascular invasion were identified in the multivariable analysis (
p
<0.05). The developed nomogram incorporated these four predictors and it yielded good discrimination and calibration, with an area under the curve (AUC) of 0.89 (95% confidence interval CI: 0.80–0.97). However, the Japanese guideline yielded an AUC of 0.75 (95% CI: 0.63–0.87). A decision curve analysis showed that the predictive scoring system had a high clinical application value, and the nomogram conferred a greater benefit than the Japanese guideline did (range of threshold within 10%–80%).
Conclusions
This study proposed a novel predictive model to assist physicians in making treatment decisions regarding additional surgery after local excision.
In this work, a new and simple frequency quadrupling scheme of generating quadrature phase shift keying (QPSK) modulated vector millimeter-wave signal based on a dual-parallel polarization modulator ...is proposed, which can avoid the problem of Mach–Zehnder modulator (MZM) offset point drifting. To eliminate constellation overlapping of the generated vector millimeter-wave signal caused by phase multiplication in the process of frequency multiplication, precoding assisted technique is adopted. The principle and feasibility of the proposed scheme is deduced by detailed mathematical formula. Simulations are done to generate 40 GHz QPSK modulated vector millimeter-wave signals using a 10 GHz radio frequency source and the BER performance is analyzed in detail. The results show that BER of the generated 5/10-Gbit/s vector millimeter-wave signal is below
3.8
×
10
-
3
, when the input optical power for into photo-detector is higher than − 24.25 dBm.
This paper focuses on the complexity issue of relay selection for fifth-generation (5G) large-scale secure two-way amplify-and-forward (TWR-AF) relay systems with massive relays and eavesdroppers. A ...novel and distributed relay selection criterion i.e., low-complexity relay selection criterion (LRSC) is proposed to maximize the overall secrecy performance. Utilizing LRSC, the calculations of sources' received signal-to-noise ratios (SNRs), the channel estimation, and the knowledge of the relay-eavesdropper links are not required. Particularly, a relay is selected based on the received power of relays and the average knowledge of the source-eavesdropper links. These low-complexity properties make LRSC more attractive for 5G large-scale networks. Moreover, the secrecy outage probability and the impact of the eavesdropper density on the secrecy performance are presented, and some useful insights are obtained. Simulation results highlight the effectiveness of our relay selection design.
Three low-complexity relay-selection strategies, namely, selective amplify and forward (S-AF), selective decode and forward (S-DF), and amplify and forward with partial relay selection (PRS-AF) in a ...spectrum-sharing scenario are studied. First, we consider a scenario where perfect channel state information (CSI) is available. For these scenarios, the respective asymptotic outage behaviors of the secondary systems are analyzed, from which the diversity and coding gains are derived and compared. Unlike the coding gain, which is shown to be very sensitive with the position of the primary receiver, the diversity gain of the secondary system is the same as the nonspectrum-sharing system. In addition, depending on the cooperative strategy employed, an increase in the number of relays may lead to severe loss of the coding gain. Afterwards, the impacts of imperfect CSI regarding the interference and transmit channels on the outage behavior of the secondary systems are analyzed. On one hand, the imperfect CSI concerning the interference channels only affects the outage performance of the primary system, whereas it has no effect on the diversity gain of the secondary system. On the other hand, the imperfect CSI concerning the transmit channels of the secondary systems may reduce the diversity gain of the three relay-selection strategies to unity, which is validated by both theoretical and numerical results.
Considering a dual-hop energy-harvesting (EH) relaying system, this paper advocates novel relaying protocols based on adaptive time-switching (TS) for amplify-and-forward and decode-and-forward ...modes, respectively. The optimal TS factor is first studied, which is adaptively adjusted based on the dual-hop channel state information (CSI), accumulated energy, and threshold signal-to-noise ratio (SNR), to achieve the maximum throughput efficiency per block. To reduce the CSI overhead at the EH relay, a low-complexity TS factor design is presented, which only needs single-hop CSI to determine the TS factor. Theoretical results show that, in comparison with the conventional solutions, the proposed optimal/low-complexity TS factor can achieve higher limiting throughput efficiency for sufficiently small threshold SNR. As the threshold SNR approaches infinity, the throughput efficiency of the proposed optimal/low-complexity TS factor tends to zero in a much slower pace than that of the conventional solutions. Simulation results are presented to corroborate the proposed methodology.
This paper explores covert broadcast communication in a challenging situation in which the transmitter, Alice, faces uncertainty regarding the position of the passive adversary, Willie. In this ...situation, controlling the signal exposure becomes difficult. Specifically, this paper focuses on the cases where Alice can delimit the suspicious areas where Willie may be located. The suspicious areas can have arbitrary number and shapes. Under the Rician fading model, the analytical expression of Willie’s detection performance is derived. Then, the transmit power, the beamforming direction, and the number of channel uses are jointly designed to minimize the optimal Willie’s detection performance among all the possible positions of Willie, on the premise of satisfying receivers’ quality-of-service requirements. To tackle the formulated knotty problem with an infinite number of irregular and discontinuous Willie’s possible positions, the continuous nature of the antenna pattern is exploited to convert the original problem into the one with a finite number of possible positions, by sampling the suspicious areas. Then, different algorithms are developed to address the resultant non-convex optimization problem for single-antenna Willie and multi-antenna Willie, respectively. Numerical results demonstrate significant performance gains of the proposed scheme over the widely-adopted maximum ratio transmission scheme, which indicates that simply adjusting the main lobe towards the receiver is indeed far away from optimum and shows the importance of leveraging Alice’s limited knowledge of Willie’s position.
Natural electric field frequency selection method was proposed by Chinese scholars in the 1980s on the basis of imitating the field observation method of the magnetotelluric method (MT). It can only ...measure the magnetotelluric field components of one or several frequencies on the surface to determine the existence of underground geological bodies. This method has played an important role in shallow groundwater exploration. This paper mainly discusses the application of frequency selection method in the exploration of underground hot water in the Maoyanhe Scenic spot, Zhangjiajie City, Hunan Province, in order to illustrate the effectiveness of the frequency selection method in water exploration. According to the situation of the construction site, nearly 20 geophysical prospecting survey lines of varying lengths were laid flexibly within the red line of the Maoyan River Scenic Spot. Firstly, three-frequency (170 Hz, 67 Hz and 25 Hz) measurements were carried out on each survey line to preliminarily determine the possible horizontal location of underground hot water. Secondly, in the vicinity of the low potential anomaly of the three-frequency curve, the fine measurement by using multi-frequency bipolar profile method was further carried out. The specific distribution of underground hot water was determined based on the principle of frequency domain sounding and the static effect characteristics of the electromagnetic method so as to provide a scientific basis for the drilling layout. Finally, the reliability of the frequency selection method is verified by two verification boreholes. The results indicate that the frequency selection method is one of the effective geophysical exploration methods in groundwater exploration.
Interference Analysis in Wireless Power Transfer Yunfei Chen; da Costa, Daniel Benevides; Haiyang Ding
IEEE communications letters,
2017-Oct., 2017-10-00, Letnik:
21, Številka:
10
Journal Article
Recenzirano
This letter studies the effect of co-channel interference (CCI) generated by wireless power transfer on information delivery for three widely used setups, i.e., power beacon (PB), hybrid access point ...(HAP), and simultaneous wireless information and power transfer (SWIPT). It focuses on the comparison of CCI from these three schemes in terms of the average interference power, the ergodic capacity, and the bit error rate. Numerical results show that the extra interference caused by wireless power transfer indeed degrades the system performance. Moreover, SWIPT has the largest degradation, while PB and HAP have the same degradation when proper parameters are chosen.
Polyols with different number of hydroxyl groups were synthesized from ricinoleic acid and oleic acid. These plant oil derived polyols can be used as plasticizers and combined with ethyl cellulose ...(EC) through supramolecular system to prepare ethyl cellulose composite films. The morphology, thermal stability and mechanical properties of the prepared ethyl cellulose films were studied in detail to indicate the plasticizing efficiency of these polyols and the effect of the number of hydroxyl groups in polyols on EC composite film’s properties. With the addition of polyols, the tensile strength of EC composite films decreased, while the elongation at break increased. The elongation at break of EC composite films can be improved by 11–12 times when the polyols contain 1–3 hydroxyl groups. Thus, the plant oil derived polyols with 1–3 hydroxyl groups can be used as plasticizers for EC films. In addition, molecular dynamic simulations were performed to further probe the effects of the number of hydroxyl groups in polyols on EC composite film’s properties.
Graphic abstract
Novel functional dynamic covalent-bonded polymer networks (DCPN) containing dynamic disulfide bonds were prepared from castor oil via a simple process. Firstly, UV-curable castor-oil-based ...polyurethane acrylate (COPUA) containing disulfide bonds and unsaturated double bonds was synthesized, then added with glycidyl methacrylate (GMA) to reduce viscosity (named COPUA-GMA) and mixed with different proportions of glycidyl esters containing unsaturated double bonds to form a series of UV-cured polymers named COPUA-GMA-EP. FTIR and NMR demonstrated the target pre-polymers and DCPNs were successfully synthesized. The DCPNs possessed controllable mechanical properties. Tensile tests showed the polymers had a range of tunable stiffness and flexibility. The COPUA-GMA-EP-2 copolymerized system containing 50 wt% COPUA-GMA had relatively excellent tensile strength of 11.8 MPa and elongation at break of 72.3%. Thermal analysis showed that DCPNs had excellent thermal stability, and COPUA-GMA-EP-2 had higher crosslinking density. Importantly, COPUA-GMA-EP-2 displayed excellent shape memory properties with Rf of 98.9% and Rr of 79.0%. Meanwhile, this DCPN exhibited certain self-healing properties. The DCPNs will be widely applied with good prospects owing to their excellent UV-curable, eco-friendly and shape memory properties.
Display omitted
•Novel castor oil based functional dynamic covalent-bonded polymer networks (DCPNs) were prepared via a simple UV cured process.•The fabricated DCPNs contained reactive dynamic disulfide bonds.•The obtained DCPNs possessed controllable mechanical properties with a range of tunable stiffness and flexibility.•The designed DCPNs had excellent shape memory properties and certain scratch self-healing properties.•The prepared DCPNs were of potential application value owing to their excellent eco-friendly and shape memory properties.
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