Cancellation Effect Research Articles

Prioritizing Surgical Cancellation Factors Based on a Fuzzy Best-Worst Method: A Case Study

Abstract Surgery is a potent source of income, and surgical cancellation is a significant issue for hospitals. Surgical cancellation costs a lot to both patients and hospitals. Reducing a surgical cancellation rate has a substantial effect on improving hospital management. This paper considers both the effects of surgical cancellation on patients and hospitals. In addition, it presents a fuzzy best-worst method (BWM) based on a failure mode and effect analysis (FMEA) method to evaluate surgical cancellation factors. To achieve this aim, the FMEA and three effective criteria are taken into consideration. The psychological impact of surgical cancellation is one of the effective criteria, which has never considered as the involved criterion. Finally, a real case study in a Shariati hospital in Tehran is conducted to demonstrate the application of the proposed method.

Steady hydrodynamic interaction between human swimmers.

This study focuses on the hydrodynamic interaction between two or three human swimmers in competitive swimming. Although the swimming performance of a single swimmer has been widely examined, studies on the interaction between multiple competitive swimmers are very rare. Experiments showed evidence that the drag of a swimmer could be modified by the existence of the other adjacent competitors (Chatard & Wilson. 2003 Med. Sci. Sports Exerc. 35, 1176–1181. (doi:10.1249/01.MSS.0000074564.06106.1F)). The following questions arise: (1) what mechanism determines the interaction; (2) which position experiences drag reduction or drag increase; (3) how much can drag be reduced or increased in a formation? According to the authors' knowledge, such questions have not been addressed by any published literature. Therefore, the main purpose of this study is to find the mechanism of the hydrodynamic interaction between human swimmers and to quantify this interactive effect by using a steady potential flow solver. The free-surface effect was fully taken into account in our calculations. We firstly calculated the wave drag of a swimmer swimming solely in an open swimming pool. Then we calculated the wave drag of the same swimmer when he/she swam in the wake region of one or two leading swimmers. The results showed that the hydrodynamic interaction made a significant contribution to the drafter's wave drag. By following a leading swimmer, a drafter at wave-riding positions could save up to 63% of their wave drag at speed of 2.0 m s−1 and lateral separation of 2.0 m. Particularly, when a drafter is following two side-by-side leaders, the drag reduction could even be doubled. To the authors' knowledge, this study is the first to demonstrate that the hydrodynamic interaction between human swimmers can best be described and explained in terms of wave interference effect on the free water surface. When the wave cancellation effect is observed, the wave drag of a drafter could be minimized, and this wave cancellation effect can be achieved only when the drafter is in a wave-riding position.

NOMA-Aided Cell-Free Massive MIMO Systems

A cell-free massive multiple-input multiple-output system with non-orthogonal multiple-access (NOMA) is investigated. An achievable sum rate is derived and compared against the orthogonal multiple access (OMA) counterpart. Thereby, the detrimental effects of intra-cluster pilot contamination, inter-cluster interference and imperfect successive interference cancellation (SIC) are investigated. The number of users served simultaneously by NOMA can be significantly higher than that of OMA. Nevertheless, the achievable sum rate of NOMA can be lower than that of OMA even in the regime of low number of users due to intra-cluster pilot contamination and error propagation of imperfect SIC.

A Modified Bridge Switch-Type Flux-Coupling Nonsuperconducting Fault Current Limiter for Suppression of Fault Transients

This paper proposes a modified bridge switch-type flux-coupling nonsuperconducting fault current limiter (BSFC-NSFCL) for suppressing the fault current and voltage sag. A flux-coupling reactor and a bidirectional bridge switch are combined to perform the functions of steady-state line current sharing and fault current suppression. The modified BSFC-NSFCL mainly utilizes the magnetic flux cancellation effect to make the limiter behave as a short circuit on the circuit during normal operation. Hence, there is almost no impact on the power system when the limiter is used. When a fault event occurs, the bridge switch turns off immediately, and then, the magnetic flux cancellation effect disappears. Thus, the impedance of primary coil inserts into the circuit to restrict the fault current and voltage sag phenomena. Once the fault is removed, the bridge switch turns on again, and the BSFC-NSFCL recovers to the normal operation. The modified NSFCL is more cost-effective and easy to be implemented than the flux-coupling superconducting fault current limiter. Theoretical analysis for the BSFC-NSFCL has been fully developed and proven by MATLAB software. Finally, the analytical, simulated, and experimental results have been carried out to verify the feasibility and performance of the proposed BSFC-NSFCL.

Sharp commutator estimates via harmonic extensions

We give an alternative proof of several sharp commutator estimates involving Riesz transforms, Riesz potentials, and fractional Laplacians. Our methods only involve harmonic extensions to the upper half-space, integration by parts, and trace space characterizations.The commutators we investigate are Jacobians, more generally Coifman–Rochberg–Weiss commutators, Chanillo’s commutator with the Riesz potential, Coifman–McIntosh–Meyer, Kato–Ponce–Vega type commutators, the fractional Leibniz rule, and the Da Lio–Rivière three-term commutators. We also give a new limiting L1-estimate for a double commutator of Coifman–Rochberg–Weiss-type, and several intermediate estimates.The beauty of our method is that all those commutator estimates, which are originally proven by various specific methods or by general para-product arguments, can be obtained purely from integration by parts and trace theorems. Another interesting feature is that in all these cases the “cancellation effect” responsible for the commutator estimate simply follows from the product rule for classical derivatives and can be traced in a precise way.

Contribution assessment of antenna structure and in-gap photocurrent in terahertz radiation of photoconductive antenna

Photoconductive antenna (PCA) is one of the most widely used terahertz (THz) devices nowadays. Although PCAs have been extensively studied through both theoretical analysis and device design, there still lacks a common agreement upon the mechanism of THz radiation. One of the central questions is how to distinguish and assess the contribution of the antenna structure and in-gap photocurrent to the overall radiation of a PCA. In this work, a three-dimensional full-wave model was first used to quantify the overall far-field radiation of PCAs. The commercial solver (i.e., HFSS) and the Hertzian dipole approximation method were then applied to quantify the far-field radiation solely from the antenna structure and in-gap photocurrent, respectively. The contribution of the antenna structure and in-gap photocurrent can therefore be distinguished by comparing the simulation results among the three methods. The results suggest that, although the THz radiation originates from laser-excited photocurrent within the gap, the overall THz radiation of a PCA is predominated by the antenna structure. As a validation, the cancellation effect was predicated by numerical simulation of coplanar stripline PCA and confirmed with experiment using butterfly shaped stripline PCA. The presented work uncovers the details of the underlying radiation mechanism of the PCA. This could inspire PCA design that aims for engineering the radiation properties of a PCA for specific applications.

Dynamic responses of a floating tidal turbine with 6-DOF prescribed floater motions

This study aims to reveal the dynamic response and power output characteristics of a floating tidal turbine with prescribed motions in six degrees of freedom. Floater motions were calculated in the time domain based on linear potential theory. Both wave-induced inflow fields and floater motions are considered in a modified blade element momentum theory model for rotor load simulation. Generator power production and loads on a reference tidal turbine system were investigated. The torque and thrust response spectra are found to be dominated by floater-motion-induced contributions, and two response peaks can be clearly identified. A cancellation effect occurs between direct wave effects and floater-motion-induced loads, and horizontal and vertical rotor positions can significantly affect the dynamic responses of the blade loads; the rotor should be placed close to the floater centre to avoid large floater-motion-induced velocity on the blade section. Sensitivity studies are carried out with varying significant wave heights and peak periods. These results may contribute to a general understanding of floater-induced dynamic loads on floating tidal turbines in a random sea.

Pebble dynamics and accretion on to rocky planets – I. Adiabatic and convective models

We present nested-grid, high-resolution hydrodynamic simulations of gas and particle dynamics in the vicinity of Mars- to Earth-mass planetary embryos. The simulations extend from the surface of the embryos to a few vertical disk scale heights, with \rev{a spatial} dynamic range \rev{of} $\sim\! 1.4\times 10^5$. Our results confirm that "pebble"-sized particles are readily accreted, with accretion rates continuing to increase up to metre-size "boulders" for a 10\% MMSN surface density model. The gas mass flux in and out of the Hill sphere is consistent with the Hill rate, $\Sigma\Omega R_\mathrm{H}^2 = 4\, 10^{-3}$ M$_\oplus$ yr$^{-1}$. While smaller size particles mainly track the gas, a net accretion rate of $\approx 2\,10^{-5}$ M$_\oplus$ yr$^{-1}$ is reached for 0.3--1 cm particles, even though a significant fraction leaves the Hill sphere again. Effectively all pebble-sized particles that cross the Bondi sphere are accreted. The resolution of these simulations is sufficient to resolve accretion-driven convection. Convection driven by a nominal accretion rate of $10^{-6}$ M$_\oplus$ yr$^{-1}$ does not significantly alter the pebble accretion rate. We find that, due to cancellation effects, accretion rates of pebble-sized particles are nearly independent of disk surface density. As a result, we can estimate accurate growth times for specified particle sizes. For 0.3--1 cm size particles, the growth time from a small seed is $\sim$0.15 million years for an Earth mass planet at 1 AU and $\sim$0.1 million years for a Mars mass planet at 1.5 AU.

Exclusive production of Bc mesons in e+e− colliders**Supported by Natural Science Foundation of Shandong Province, China (ZR2015AQ006), National Natural Science Foundation of China (11521505, 11621131001, 11447009, 11505098, 11765012), R. H. Li is partly supported by the plan of Young Creative Talents under the Talent of the Prairie project of the Inner Mongolia

Within the framework of the perturbative QCD approach, we calculate the time-like form factors F(Q2) and A2(Q2). We include relativistic corrections and QCD corrections, either of which can give about 20% correction to the leading-order contribution, but there are cancellation effects between them. We calculate the cross sections of the processes. The cross sections are enhanced at the Z pole to be σPP(Q = mZ) ∼ 1.3 × 10−5 pb and σPV(Q = mZ) ∼ 2.5 × 10−5pb, which are still too small to be detected by proposed e+e− colliders such as the Circular Electron Positron Collider.

A Novel ICI Triple Cancellation Scheme in Fast Time-varying Environment for OFDM Systems

In fast time-varying environment, orthogonal frequency division multiplexing (OFDM) systems lose the orthogonality between subcarriers due to the Doppler effect, resulting in inter-carrier interference (ICI), which greatly affects the performance of the communication system. Based on the analysis of the principle of ICI generation in time-varying environment, an ICI triple cancellation scheme is proposed to reduce the ICI of the OFDM systems in fast time-varying environment. In the scheme, the ICI self-cancellation modulation is performed at the transmitter of the OFDM system. Then, the time-varying channel is modeled as a linearly time-varying (LTV) model for ICI dual cancellation. Finally, the ICI self-cancellation demodulation is executed at the receiver of the system. Simulation experiment results show that the proposed ICI triple cancellation scheme can achieve a better effect of ICI cancellation than ICI self-cancellation scheme and ICI dual cancellation scheme, improving the performance of the communication system.

Leaving the Shadows of US Bankruptcy Law: A Proposal to Divide the Realms of Insolvency and Restructuring Law

Insolvency law used to be a set of rules that govern the way a debtor is treated once he became insolvent and stopped trading. Certain mechanisms respond to this incident in order to safeguard a fair treatment of all creditors and other stakeholders with the aim of minimizing the damage. Modern insolvency laws do more. They have been endowed with tools that shall allow for a restructuring of the business of the failing debtor, often combining the common tools of insolvency law, e.g. a collective stay, with new tools to facilitate a restructuring agreement. But why wait until a debtor is insolvent? The idea of early redress to a business failure has led to a number of legislative pre-insolvency initiatives that make such tools available to debtors that are not yet insolvent. The result is a mixture of insolvency and restructuring law that has grown guided by practical needs rather than doctrinal approaches. In this paper, a doctrinal approach is proposed that offers a clear distinction between insolvency and restructuring law. Based on the description of the debt cancellation effect as the common function of all insolvency and restructuring proceedings, the different mechanisms that both types of procedures use lead to a clear categorization of insolvency and restructuring proceedings and their governing law and principles.

Performance analysis of decode-and-forward partial relay selection in NOMA systems with RF energy harvesting

In this paper, we investigate a dual hop communication decode-and-forward scheme relay system where a source node wants to transmit simultaneously two symbols to two desired destinations with the help of one selected energy constraint relay node. The power for operation of relay is come from the ambient radio frequency energy harvesting and the non-orthogonal multiple access technology is applied. We mathematically evaluate the impact of partial relay selection on the system performance by considering the undecodable probability of symbol for which symbols can not be decoded at the relay node or two destinations. Furthermore, the undecodable probability and the ergodic capacity are analyzed under the effect of imperfect and perfect successive interference cancellation (SIC). The results of theoretical analysis is similar to the simulation results, especially in the high region of transmit power. It verifies the correctness of mathmatical closed-form in our analysis. The results also show that the performance of the system are significantly influenced by the efficiency of SIC technology and the number of relay nodes.

Nanosecond bipolar pulse generators for bioelectrics

Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range.

Elective Surgery Cancellations During the Time Between Scheduling and Operation

Surgery cancellations cause harm to patients, extra work for preoperative staff, and financial loss for organizations. Day of surgery cancellations are a widely used indicator for operative effectiveness, but there is a lack of knowledge concerning the effects of cancellations during earlier stages of a patient's preoperative waiting period. The purpose of this study was to measure the reasons, frequencies, and timing of elective surgery cancellations after scheduling. Qualitative prospective follow-up study. Data were collected during a 2-month period in 13 operative specialties by a semistructured follow-up form and analyzed by inductive content analyses and statistical methods. Most of the cancellations occurred before the day of surgery and appeared because patients were not in a suitable condition for the planned operation or because of lack of organizational resources. More attention should be focused on patients' suitability and organizational resources in earlier stages of preoperative period.

Chiral pair of Fermi arcs, anomaly cancellation, and spin or valley Hall effects in Weyl metals with broken inversion symmetry

Anomaly cancelation has been shown to occur in time-reversal symmetry-broken Weyl metals, which explains the existence of a Fermi arc. We extend this result in the case of inversion symmetry-broken Weyl metals. Constructing a minimal model that takes a double pair of Weyl points, we demonstrate the anomaly cancelation explicitly. This demonstration explains why a chiral pair of Fermi arcs appear in inversion symmetry-broken Weyl metals. In particular, we find that this pair of Fermi arcs gives rise to either "quantized" spin Hall or valley Hall effects, which corresponds to the "quantized" version of the charge Hall effect in time-reversal symmetry-broken Weyl metals.

Summation and Cancellation Effects on QRS and ST-Segment Changes Induced by Simultaneous Regional Myocardial Ischemia

Simultaneous ischemia in two myocardial regions is a potentially lethal clinical condition often unrecognized whose corresponding electrocardiographic (ECG) patterns have not yet been characterized. Thus, this study aimed to determine the QRS complex and ST-segment changes induced by concurrent ischemia in different myocardial regions elicited by combined double occlusion of the three main coronary arteries. For this purpose, 12 swine were randomized to combination of 5-min single and double coronary artery occlusion: Group 1: left Circumflex (LCX) and right (RCA) coronary arteries (n = 4); Group 2: left anterior descending artery (LAD) and LCX (n = 4) and; Group 3: LAD and RCA (n = 4). QRS duration and ST-segment displacement were measured in 15-lead ECG. As compared with single occlusion, double LCX+RCA blockade induced significant QRS widening of about 40 ms in nearly all ECG leads and magnification of the ST-segment depression in leads V1–V3 (maximal 228% in lead V3, p < 0.05). In contrast, LAD+LCX or LAD+RCA did not induce significant QRS widening and markedly attenuated the ST-segment elevation in precordial leads (maximal attenuation of 60% in lead V3 in LAD+LCX and 86% in lead V5 in LAD+RCA, p < 0.05). ST-segment elevation in leads V7–V9 was a specific sign of single LCX occlusion. In conclusion, concurrent infero-lateral ischemia was associated with a marked summation effect of the ECG changes previously elicited by each single ischemic region. By contrast, a cancellation effect on ST-segment changes with no QRS widening was observed when the left anterior descending artery was involved.

A novel generation method of oscillatory rotating eddy current for crack orientation determination and detection in metal plates

A novel generation method of oscillatory rotating eddy current (OREC) is proposed to solve the problems in the conventional rotating eddy current (REC) method. Although the REC method can provide the uniform sensitivity to all the cracks with different distribution angles in non-ferromagnetic materials, eddy current signal patterns can be applied only in the rough quantification of crack orientation. In ferromagnetic materials, due to the cancellation effect between the magnetic flux leakage and eddy current mechanisms, when the angle between the crack direction and the excitation current direction was about 45°, it was difficult to detect the crack with the conventional REC method. Therefore, amplitude-modulated excitation currents were introduced into the REC test and then oscillatory rotating eddy current are induced to interact with the cracks in the study. The frequency of the modulation signal determined the spatial rotation speed of the OREC field. Then, the compound profiles of the detected carrier signals were extracted and redrawn in the polar diagram to demonstrate 8-shaped or 4-Pl signal patterns. Finally, the angle between straight lines connecting the maximum signal positions of 8-shaped or 4-Pl trajectories was estimated as the feature parameter for determining crack orientation. The feature parameter was used to characterize all the cracks with different distribution angles in both non-ferromagnetic and ferromagnetic materials. The proposed OREC method realized an angular resolution of 15° in crack orientation determination.

Comparing Gait with Multiple Physical Asymmetries Using Consolidated Metrics.

Physical changes such as leg length discrepancy, the addition of a mass at the distal end of the leg, the use of a prosthetic, and stroke frequently result in an asymmetric gait. This paper presents a metric that can potentially serve as a benchmark to categorize and differentiate between multiple asymmetric bipedal gaits. The combined gait asymmetry metric (CGAM) is based on modified Mahalanobis distances, and it utilizes the asymmetries of gait parameters obtained from motion capture and force data recorded during human walking. The gait parameters that were used in this analysis represent spatio-temporal, kinematic, and kinetic parameters. This form of a consolidated metric will help researchers identify overall gait asymmetry by showing them if the overall gait symmetry is improving and avoid the case where one parameter's symmetry is improving while another is getting worse. The CGAM metric successfully served as a measure for overall symmetry with eleven different gait parameters and successfully showed differences among gait with multiple physical asymmetries. The results showed that mass at the distal end had a larger magnitude on overall gait asymmetry compared to leg length discrepancy. It also showed that the combined effects are varied based on the cancelation effect between gait parameters. The metric was also successful in delineating the differences of prosthetic gait and able-bodied gait at three different walking velocities.

Angular ellipticity correlations in a composite alignment model for elliptical and spiral galaxies and inference from weak lensing

We investigate a physical, composite alignment model for both spiral and elliptical galaxies and its impact on cosmological parameter estimation from weak lensing for a tomographic survey. Ellipticity correlation functions and angular ellipticity spectra for spiral and elliptical galaxies are derived on the basis of tidal interactions with the cosmic large-scale structure and compared to the tomographic weak lensing signal. We find that elliptical galaxies cause a contribution to the weak-lensing dominated ellipticity correlation on intermediate angular scales between $\ell\simeq40$ and $\ell\simeq400$ before that of spiral galaxies dominates on higher multipoles. The predominant term on intermediate scales is the negative cross-correlation between intrinsic alignments and weak gravitational lensing (GI-alignment). We simulate parameter inference from weak gravitational lensing with intrinsic alignments unaccounted; the bias induced by ignoring intrinsic alignments in a survey like Euclid is shown to be several times larger than the statistical error and can lead to faulty conclusions when comparing to other observations. The biases generally point into different directions in parameter space, such that in some cases one can observe a partial cancellation effect. Furthermore, it is shown that the biases increase with the number of tomographic bins used for the parameter estimation process. We quantify this parameter estimation bias in units of the statistical error and compute the loss of Bayesian evidence for a model due to the presence of systematic errors as well as the Kullback-Leibler divergence to quantify the distance between the true model and the wrongly inferred one.

Matrix product algorithm for stochastic dynamics on networks applied to nonequilibrium Glauber dynamics.

We introduce and apply an efficient method for the precise simulation of stochastic dynamical processes on locally treelike graphs. Networks with cycles are treated in the framework of the cavity method. Such models correspond, for example, to spin-glass systems, Boolean networks, neural networks, or other technological, biological, and social networks. Building upon ideas from quantum many-body theory, our approach is based on a matrix product approximation of the so-called edge messages-conditional probabilities of vertex variable trajectories. Computation costs and accuracy can be tuned by controlling the matrix dimensions of the matrix product edge messages (MPEM) in truncations. In contrast to Monte Carlo simulations, the algorithm has a better error scaling and works for both single instances as well as the thermodynamic limit. We employ it to examine prototypical nonequilibrium Glauber dynamics in the kinetic Ising model. Because of the absence of cancellation effects, observables with small expectation values can be evaluated accurately, allowing for the study of decay processes and temporal correlations.