Abnormal Mode Research Articles

Topology‐Induced Phase Transitions in Spin‐Orbit Photonics

AbstractSpin‐controlled vortex generation and spin‐Hall effect, two distinct effects discovered in optics, have been extensively studied recently. However, while physical origins of two effects are both due to spin‐orbit interactions, their inherent connections remain obscure which also hinders further explorations on the manipulations of them. Here, in studying the scattering of a spin‐polarized light beam at sharp interfaces, an intriguing phase transition between vortex generation and spin‐Hall shift trigged by varying the incidence angle is revealed. After reflection/refraction, the beam contains two components: normal and abnormal modes acquiring spin‐redirection‐Berry phases and Pancharatnam–Berry phases, respectively. Inside the abnormal beam, two classes of wave components gain Pancharatnam–Berry phases with distinct topological natures, generating intrinsic and extrinsic orbital angular momenta (OAM), respectively. Enlarging incidence angle changes the relative portions of these two contributions, making the abnormal beam undergo a phase transition from vortex generation to spin‐Hall shift. Such intriguing effect is experimentally observed at a purposely designed metamaterial slab, exhibiting efficiency enhanced by several‐thousand times compared to that at a conventional slab. These findings unify two previously discovered effects in a single framework, reinterpret previous results with clearer pictures, and shed light on understanding other physical effects involving the competition between intrinsic and extrinsic OAM.

The impact of polymers’ supramolecular structure on water vapour sorption and drug release from films on the basis of some polysaccharide

The article establishes the relationship between supramolecular film structure of some polysaccharides and their diffusion characteristics. The differences in the supramolecular film structures, in their turn, are associated with the differences in the structural-physical state of the solutions the films are made from and the time of the film dry out. It was established that in a definite area of concentrations of polymer solutions there was a sharp increase in viscosity due to the interaction of the macromolecular chains and mass scale formation of molecular aggregates in the solution. As a result, the polysaccharide solutions of different concentration differ from the structural-physical point of view. It was proved that the polymer concentration in the initial solution contributes greatly to the structure of the films formed, and the changes in the supramolecular structure of the film samples have an impact on the diffusion characteristics. It was established that the values of the diffusion coefficients determined in the experiments depend on the polymer concentration in the initial solution and the thickness of the film samples. It was also showed that the diffusion processes do not follow the Fick's law and occur in an abnormal diffusion mode.

On Detecting Abnormal Access for Online Ideological and Political Education

With the development and spread of networks, online education has become a new way in education. The online education platform encounters a large number of concurrent visiting, while the system must guarantee network security in the process of online education. The network visiting requests are real-time and dynamic in online education. In order to detect network intrusion and abnormal access in real time and adapt to the dynamic changes of network visiting requests, this paper adopts a data stream-based network intrusion detection method to monitor and manage online education visiting. First, a knowledge library is constructed by normal visiting mode and abnormal visiting mode. Second, the dissimilarity between data point and data cluster is used to measure the similarity between normal mode and abnormal mode. Lastly, the knowledge library is updated to reflect the changes of network in online education system by re-clustering. The proposed method is evaluated on a real dataset.

Revisiting the anomalous spin-Hall effect of light near the Brewster angle

Optical spin-Hall effect (SHE) exhibits many intriguing features as a linearly polarized (LP) light beam strikes an interface at incident angles around the Brewster angle, but the underlying physics remains obscure. Here, we elucidate the physics through reanalyzing this problem employing rigorous calculations and the Berry phase concept. As a circularly polarized (CP) light beam strikes an optical interface, the reflected light beam contains two components, a spin-flipped abnormal mode acquiring geometric phases (thus exhibiting a spin-Hall shift) and a spin-maintained normal mode without such phases. Strengths of these two modes are determined by the incident angle and the optical properties of the interface. Under the LP incidence, however, a spin component inside the reflected light beam must be the sum of normal and abnormal components of reflected light beams corresponding to CP incidences with different helicity, which thus sensitively depends on the incident angle. In particular, at incident angles near the Brewster one, reflection coefficients for two CP components exhibit opposite signs, leading to significant destructive interferences between normal and abnormal modes, finally generating highly deformed reflected light patterns with anomalously enhanced spin-Hall shifts. These findings can be extended to both reflected and transmitted cases with Brewster-like behaviors. Our analyses reinterpret previously discovered effects, providing an alternative understanding on the SHE of light.

A Novel Adaptive Super-Twisting Sliding Mode Control Scheme with Time-Delay Estimation for a Single Ducted-Fan Unmanned Aerial Vehicle

This article proposes a novel adaptive super-twisting sliding mode control scheme with a time-delay estimation technique (ASTSMC-TDE) to control the yaw angle of a single ducted-fan unmanned aerial vehicle system. Such systems are highly nonlinear; hence, the proposed control scheme is a combination of several control schemes; super-twisting sliding mode, TDE technique to estimate the nonlinear factors of the system, and an adaptive sliding mode. The tracking error of the ASTSMC-TDE is guaranteed to be uniformly ultimately bounded using Lyapunov stability theory. Moreover, to enhance the versatility and the practical feasibility of the proposed control scheme, a comparison study between the proposed controller and a proportional-integral-derivative controller (PID) is conducted. The comparison is achieved through two different scenarios: a normal mode and an abnormal mode. Simulation and experimental tests are carried out to provide an in-depth investigation of the performance of the proposed ASTSMC-TDE control system.

Preventive protection of marine electrical power system from the transition of generating sets to motoring mode

The approaches that ensure the trouble-free operation of marine power system in abnormal modes were considered. Such modes are usually associated with the system elements failure during operation. Particular attention was paid to the processes occurring in the circuit during transition of one of the generators to the motoring operation mode. The relevance of the considered marine power system issue was substantiated. According to the research results, using time-delay when generating a signal to disable a failed unit operating with reverse power can contribute to defect development in the primary motor. Moreover, time-delay can also lead to zero voltage in the marine electric power system. This circumstance creates the possibility of an emergency that can potentially lead to a shipping accident with the most serious consequences. The problem of timely shutdown of a faulty electrical machine before its transition to the motoring mode is defined in the research, as well as the overload prevention problem for primary motors remaining in working condition. An original diagnostic indicator was proposed based on study, which allows identifying the inoperative state of generator unit during operation. The new approach was developed, which implements the preventive control method for the marine power system in case of element failure. The forecasting of the system operation modes in case of a generator set failure, and its structural adaptation to the occurred malfunction is carried out. In contrast to the existing methods, the practical implementation of the proposed solution will allow accident-free transition of marine power system to a partially operational state without the emergency. This will have a beneficial effect on the safety of ship as a whole.

Special Aspects of Using the Wind Power Plants In the Power Supply System

The paper describes special aspects of using the wind power plants (wind turbines) in the power grid. The paper provides the classification and schematic presentation of AC wind turbines, analyzes the role, place and performance of wind power plants in Smart Grid systems with a large share of renewable energy sources. The authors also reviews a detailed analysis of existing AC wind turbines in this paper. Recommendations are given for how to enhance the wind power plants in smart grids in terms of reliability, and introduce the hardware used in the generation, conversion and interface systems into the existing power grid. After the wind power plants had been put online, the relevance of the Smart Grid concept for existing power grids was obvious. The execution of such projects is assumed to be financially costly, requires careful study, and development of flexible algorithms, but in some cases this may be the only approach. The analysis of using wind turbines shows that the structural configuration of wind power plants can be based on the principles known in the power engineering. The approaches may differ, not fundamentally, but in engineering considerations. it is necessary to point out that the method of controlling dual-power machines is quite comprehensive so that their wide use will face operational problems caused by the lack of highly professional specialists in electric drives. Therefore, it seems advisable to use square-cage asynchronous generators in wide applications. The paper shows that as the renewable energy sources are largely used in power grids, there is an issue of maintaining the power generation at a required level considering the variability of incoming wind energy. This results in the malfunctions in the operation of relay protection devices and emergency control automatics (RP and ECA), and the complicated control. Also, the standards of the CIS countries and regulatory documents miss the requirements for the wind turbine protections, taking into account their specialty causing the inefficient standard protective logic, which does not work correctly in a number of abnormal and emergency operating modes, and especially Smart Grid in power grids.

CRITICAL ANALYSIS OF SUTIKA PARICHARYA AND ITS SIGNIFICANCE IN MODERN ERA IN SAFE MOTHERHOOD

Mortality and morbidity of mother are most challenging problems of our country. In our day to day life, we see many mothers complaining of increase in their physical problems like back-ache, anemia, joint pains and many other infections after puerperium. Frequent post-partum morbidity and its association with adverse perinatal outcome suggest the need for post-partum care in developing countries for both mother and baby. Lady after delivery of placenta is called as Sutika (puerperal woman). Sutikakala (duration of puerperium) is the period following childbirth during which all body tissues revert back approximately to a pre-pregnant state. Duration of this period varies according to different Ayurvedic classics. It is well known that certain psycho-somatic changes take place during Sutikakala such as loss of weight, loss of body fluid, lacerated genital tract, constipation, mental stress etc. Most of these changes lead to ati-aptarparpana (emaciation) of mother during Sutikakala. This status causes Vata-vriddhi which is responsible for different types of health problems such as puerperal sepsis, Stanyadushti (vitiated breast milk), anaemia, prolapse of uterus etc. According to Kashyapa Samhita, treatment of Sutika is as difficult as cleaning of unclean, tattered and old cloth. In olden days, ladies used to follow strict guidelines during early postpartum days i.e. in Sutikakala, which helped them for early recovery from stress and strain caused during delivery. It also improves the quality and quantity of breast milk and it also avoids various neonatal infections. Mothers who breast feed their babies are at low risk for breast cancer. In modern era due to changing lifestyle and Mithya aahaar-vihaar (abnormal dietetics and mode of Life), pregnant lady is usually prone to Vataprakopa. Many modern Sutika feel ancient guidelines during early puerperal days as age old and time consuming to follow. Hence, guided Sutika paricharya with logical use of classical referenced medicine would be the proper solution to avoid psycho-somatic disorders in order to promote early recovery of mother.

DETECTION OF ANOMALIES IN THE INFO-COMMUNICATION SYSTEM USING THE INFORMATIVE SEQUENCE METHOD

The article deals with the method of detection and determination of anomalies or damages in info communication system. As a part of development of the mentioned method, the mathematical apparatus of assuring the high property of system’s robustness was taken into consideration. One of the approaches to increase the robustness of the damage detection system, offered in the article, is to minimize the sum of the indices of the generalized probability in the time interval that is being used in relation to the unknown parameters. To reduce real-time computing costs, it is proposed to minimize the functionality at certain intervals. Under the initial conditions of the minimization procedure, it is recommended to accept the data obtained from the previous implementation of this procedure. To simplify the damage detection procedure, it is necessary to analyze the decomposition coefficients simultaneously with the generation of generalized plausibility indices, which is due to a more progressive change of these coefficients in the normal mode of operation than in the abnormal mode, as well as noise level.

Perspectives on the Structural Health Monitoring of Bridges by Synthetic Aperture Radar

Large infrastructures need continuous maintenance because of materials degradation due to atmospheric agents and their persistent use. This problem makes it imperative to carry out persistent monitoring of infrastructure health conditions in order to guarantee maximum safety at all times. The main issue of early warning infrastructure fault detection is that expensive in-situ distributed monitoring sensor networks have to be installed. On the contrary, the use of satellite data has made it possible to use immediate and low-cost techniques in recent years. In this regard, the potential of spaceborne Synthetic Aperture Radar for the monitoring of critical infrastructures is demonstrated in geographically extended areas, even in the presence of clouds, and in really tough weather. A complete procedure for damage early-warning detection is designed, by using micro-motion (m-m) estimation of critical sites, based on modal proprieties analysis. Particularly, m-m is processed to extract modal features such as natural frequencies and mode shapes generated by vibrations of large infrastructures. Several study cases are here considered and the “Morandi” Bridge (Polcevera Viaduct) in Genoa (Italy) is analyzed in depth highlighting abnormal vibration modes during the period before the bridge collapsed.

An intelligent decision-making strategy based on the forecast of abnormal operating mode for iron ore sintering process

The abnormal operating mode of the iron ore sintering process will produce sinter ore with low yield and poor quality. It is of high economic value to ensure that the sintering process runs under normal operating mode. An intelligent decision-making strategy based on the forecast of the abnormal operating mode for the iron ore sintering process is presented in this paper. First, a fuzzy rule-based model is used to construct the forecast model of operating mode, of which inputs are selected by the one-way analysis of variance. Then, an intelligent decision-making strategy for operating parameters is proposed based on the priority. Finally, experiments are performed by using the actual running data collecting from the industrial site. The originality of this study comes with establishing a fuzzy rule-based model to forecast the operating mode and designing an intelligent decision-making strategy based on priority to improve the abnormal operating mode. The result shows that the constructed forecast model of operating mode forecasts well in abnormal operating mode. The proposed intelligent decision-making strategy can effectively improve abnormal operating mode, which has a good application prospect in the iron ore sintering process.

The Mode Switching in Pulsar J1326–6700

Abstract We report on a detailed study of the mode switching in pulsar J1326−6700 by analyzing the data acquired from the Parkes 64 m radio telescope at 1369 MHz. During the abnormal mode, the emission at the central and trailing components becomes extremely weak. Meanwhile, the leading emission shifts toward earlier longitude by almost 2°, and remains in this position for typically less than a minute. The mean flux density of the normal mode is almost five times that of the abnormal mode. Our data show that, for PSR J1326−6700, 85% of the time was spent in the normal mode and 15% was in the abnormal mode. The intrinsic distributions of mode timescales can be well described by Weibull distributions, which present a certain amount of memory in mode switching. Furthermore, a quasiperiodicity has been identified in the mode switching in pulsar J1326−6700. The estimated delay emission heights based on the kinematical effects indicate that the abnormal mode may have originated from higher altitude than the normal mode.

Algebraic Method of Nonparametric Identification of Abnormal Modes of the Power System as a Dynamic MIMO System

An approach is proposed to identify abnormal modes of a power system in real time, using only the data of synchronized vector measurements and that does not require a priori information about the parameters of its mathematical model. The algorithmic base of the method is the algebraic criterion of consistency of the linear matrix equation for the identification of the mathematical model of the power system; it does not imply the solution of parametric identification or prediction problems, does not use statistical calculations, and does not require preliminary training or long-term tuning. The effectiveness of the method is demonstrated by the example of detecting the moment an emergency situation arises in the Omsk power system.

Two-stage autoignition and combustion mode evolution in boundary layer flows above a cold flat plate

Boundary layers are omnipresent in fundamental kinetic experimental facilities and practical combustion engines, which can cause ambiguity and misleading results in kinetic target acquisition and even abnormal engine combustion. In this paper, using n-heptane as a representative large hydrocarbon fuel exhibiting pronounced low-temperature chemistry (LTC), two-dimensional numerical simulation is conducted to resolve the transient autoignition phenomena affected by a boundary layer. We focus on the ignition characteristics and the subsequent combustion mode evolution of a hot combustible mixture flowing over a colder flat plate in an isobaric environment. For cases with autoignition occurring within the boundary layer, similarity is observed in the first-stage ignition as manifested by a constant temperature at all locations. The first-stage ignition is found to be rarely affected by heat and radical loss within the boundary layer. While for the main ignition event, an obvious dependence of ignition process on boundary layer thickness is identified, where the thermal-chemical process exhibits similarity at locations with similar boundary layer thickness, and the main ignition tends to first occur within the boundary layer at the domain end and generates a C-shape reaction front. It is found that sequential spontaneous autoignition is the dominant subsequent combustion mode at high-pressure conditions. At low to intermediate pressures, auto-ignition assisted flame propagation is nevertheless the dominant mode for combustion evolution. This research identifies novel features of autoignition and the subsequent combustion mode evolution affected by a cold, fully developed boundary layer, and provides useful guidance to the interpretation of abnormal combustion and combustion mode evolution in boundary layer flows.

Stability of skyrmion formation and its abnormal dynamic modes in magnetic nanotubes

We studied the stability of skyrmion formation and its abnormal dynamic motions in magnetic nanotubes with perpendicular magnetic anisotropy with respect to the tube surface. Unlike planar geometry, skyrmions, which are formed in an elliptical shape, are stabilized, to a greater or lesser degree, by the curved geometry, depending on the sign of the Dzyaloshinskii-Moriya Interaction (DMI) constant. The positive and negative signs of the DMI constant play a crucial role in the formation of skyrmions on the curved surface. These effects become stronger as the diameter of the tube decreases, quantitatively evidencing that the curvature-induced DM-like interaction also contributes to the stability of skyrmion formation. The dynamic modes of the skyrmion in the tubes are found to be as follows: two in-plane gyration modes in the counterclockwise (CCW) and clockwise (CW) rotation senses, and one out-of-plane breathing mode. On the other hand, in contrast to the planar geometry, the initial CCW gyration motion turns out to be a linear translational motion in the circumferential direction of the tube for cases where the strength of axial AC magnetic fields is greater than a threshold field strength. The direction of the translational motions is determined by the skyrmion helicity governed by the sign of the interfacial DMI constant. This work provides further physical insight into the static and dynamic properties of skyrmions formed in curved-geometry systems and also suggests its potential application to information processing devices.

Multi-pattern failure modes and wear mechanisms of WC-Co tools in dry turning Ti–6Al–4V

Tool wear and catastrophic failure are key issues in industrial manufacturing process due to increasing the production costs and destroying the surface quality. A series of multiple factors including physical process, chemical reaction and thermo-mechanical phenomena are responsible for the occurrence of tool wear process. The aim of this work focused on the multi-pattern analysis of failure modes and wear mechanisms during turning titanium alloy Ti–6Al–4V with the ultrafine cemented carbide cutting tool. Firstly, tool failure modes were investigated categorically according to the various wear regions including cutting edges, rake faces, and flank faces. The normal wear modes such as crater wear, flank wear, BUE, micro-chipping and abnormal wear modes including plastic deformation, flaking, and catastrophic failure were described in detail. Secondly, the tool wear mechanisms were analyzed, including the mechanical-induced abrasion, heat-induced adhesion and diffusion, chemical-induced oxidation. Depending on the cutting conditions, the tool wear mechanisms were the combination of various wear factors, and single or multiple factors might dominate in the cutting process. According to the failure modes and wear mechanisms, a comprehensive evolution mapping of tool wear process was established to explain the relationships among machining process, failure modes, and wear mechanisms. This work provided important experimental basis for designing tool materials and developing high-speed cutting technology.

Simulation study of excimer VUV emission from xenon microhollow cathode discharge in the self-pulsing regime

A volume-averaged model is employed to study the dynamics of a microhollow cathode discharge in xenon operating in the self-pulsing regime. The numerical results revealed that the discharge voltage initially increases during the abnormal mode when the discharge current is quite low. Then, the discharge is transferred to a normal mode in which the current shows a steep growth to extremely high values. The results also indicated that the self-pulsing frequency increases with an increase in the input voltage at constant pressure. However, an increase in pressure at a constant input voltage leads to a reduced self-pulsing frequency. The strongest vacuum ultraviolet emission is attributed to xenon triplet excimers at a wavelength of 173 nm. An increase in the input voltage enhances the average densities of the xenon excimers, but has almost no effect on the maximum densities. Compared to the input voltage, an increase of the pressure has a much stronger effect on both the maximum and average densities, such that the maximum density of the triplet excimer is increased from 1.48×1017 m−3 at P = 30 Torr to 2×1021 m−3 at P = 250 Torr. A comparison between the self-pulsing and stationary regimes shows that the maximum densities of the excimers at the self-pulsing regime are an order of magnitude higher than those of the stationary regime. Furthermore, the average densities of the excimers in the self-pulsing regime are higher than those of the stationary regime at higher input voltages. However, the reverse is true for lower voltages.

Cyclic strain amplitude-dependent fatigue mechanism of gradient nanograined Cu

Different grain coarsening behaviors (i.e. abnormal and homogeneous) are prevalently observed in gradient nanograined (GNG) Cu under stress controlled high-cycle and strain controlled low-cycle fatigue tests, respectively. In this paper, to comprehensively understand the intrinsic fatigue mechanism of gradient nanograined structures, both high and low cycle fatigue behaviors of GNG Cu are investigated under strain-controlled fatigue tests with a wide strain amplitude ranges. Cyclic behavior transition from abnormal grain coarsening at small strain amplitude to homogeneous grain coarsening at large strain amplitude is observd in GNG Cu. Microstrucural analysis reveals that the grain coarsening behavior in either abnormal or normal (homogeneous) mode is closely related to the spatial distribution of the cyclic plastic strain in the GNG layer (localized or delocalized) under cyclic loading. Such unique cyclic strain amplitude-dependent fatigue behavior is inherent to the gradient nanostructure, which fundamentally differs from the conventional strain localizing mechanism in metals with homogeneous structures under cyclic loading.

High resolution digital imaging of India ink stained (HiReD-IIIs) rabbit knee articular cartilage reveals site-specific damage patterns at different stages of progression

Purpose: Human articular cartilage (hAC) exhibits degeneration that is site-specific and exhibits six characteristic patterns of early surface damage. These hAC patterns were distinguished by staining the cartilage surface with India Ink and photographing en face with film providing ∼(4 um)2 pixel resolution. However, the mechanisms for the initiation and progression of such damage are unclear. Modern 2-D digital imaging allows quantitative imaging over large areas, and 3D histology (3DH) allows structural visualization at ∼(0.5-1 μm)3 voxel resolution. Animal models of post-traumatic osteoarthritis (PTOA) may help elucidate the underlying mechanical and/or biological mechanisms of such damage. In the rabbit ACL transection (rACLT) model of PTOA, cartilage damage progresses steadily over 9 weeks. The aims of the present study were to analyze site-specific AC damage at four weeks after rACLT by (1) High Resolution Digital Imaging of India Ink Staining (designated here as HiReD-IIIS, “hired eyes”), (2) elucidate the 3D pattern of surface damage by 3DH, and (3) assess the extent of inhomogeneity and anisotropy of cartilage surface damage at weight-bearing sites. Methods: Rabbit Samples. With IACUC approval, ten adult female New Zealand White rabbits (11-19 mo, weight = 3.8-5.2 kg) were subjected to unilateral (right knee) ACLT to induce PTOA. At day 28, rabbits were sacrificed, the ACLT and contralateral non-operated left (CTRL) knees were harvested, and the FCs were exposed. High Resolution Digital Imaging. AC surfaces were aligned, dabbed with a 1:5 dilution of India Ink in phosphate buffered saline (PBS) + proteinase inhibitors, and digitally imaged at high resolution (4 μm)2/pixel. Custom Image Processing. Gray-scale images were normalized to 0 (darkest) and 1 (brightest) using standards, and cropped to isolate the weight bearing regions: posteromedial [PostMed] and posterolateral [PostLat] on each condyle. Surface damage area was calculated in two locations of the size ∼15mm2 on a) medial and b) lateral aspects of each weight bearing region (PostMed-M, PostMed-L, PostLat-M and PostLat-L) using 2-D morphometric analysis (adaptive thresholding by mean, despeckling, and morphological operations [closing]), normalized to the overall selected condyle area. The overall surface damage orientation, defined relative to horizontal axis ranging from [-90o, 90o], was approximated by vector analysis. Statistics. Damage area data are shown as mean ± SE. At each weight bearing region, ACLT and CTRL were compared for normalized damage area by two-way ANOVA, and for damage area and orientation association by Pearson correlation. Significance was taken as p<0.05. Results: HiReD-IIIS revealed site-specific articular cartilage (AC) deterioration patterns (Figure 1) including [1-TCL] transverse curvilinear lines (perpendicular to articulation axis), [2-PCL] parallel curvilinear lines (parallel to articulation axis), [3-RST] reticular sawtooth, and [4-R] ravine (tortuous/curvilinear contours), in the (L)ateral and (M)edial femoral condyle (FC) load-bearing regions, confirmed by 3DH. ACLT induced detectable damage, increasing normalized damage area (Figure 2A) by 4-30% in PostLat-M site, with 80% of the FCs’ lesion area concentrated between 5-25%, as compared to CTRL (p<0.0001). Surface damage patterns in all locations had an increasing trend in area with PostLat-M and PostMed-L reaching a maximum of 35% and 23%, respectively. Damage area was negatively correlated with the overall lesion orientation in the PostLat-L region (r = -0.66). Surface damage, R, was the primary pattern at PostLat-M, appearing at different states of progression. On PostLat-L, normalized damage areas of <5% and 5-18% corresponded with TCL and RST patterns, respectively (Figure 2B). On PostMed-L, lesion areas of <10% matched with PCL and TCL, and ≥10% with RST patterns. Conclusions: The integrated high-resolution image acquisition and morphometric lesion analysis revealed (1) a trajectory for evolution of TCL into RST in the PostLat-L and of TCL and PCL into RST on the PostMed-L regions, and (2) progressive occurrence of site-specific lesions that are more prominent on the PostMed-L and PostLat-M, which could be indicative of altered contact between joint constituents, leading to abnormal loading modes and directions in a destabilized joint.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Cervical maturation using mifepristone in women with normal pregnancies at or beyond term

ObjectiveThe aim of our study was to evaluate the efficacy and safety of oral mifepristone use for cervical ripening and the initiation of labor in women with normal pregnancies at or beyond term. Study designWe conducted a monocentric, prospective, comparative study on the induction of labor in women with an unfavorable cervix after 37 or more weeks of gestation in the Franck Joly Hospital, French Guiana.The immediate induction of labor by mifepristone was compared to expectant management and the induction of labor with routine cervical ripening agents during two consecutive periods. During the first period, patients received mifepristone (600 mg orally at the moment of enrollment) and were evaluated after 48 h. In the second period, patients did not receive any drugs and were evaluated after 48 h of expectant management. Primary outcomesSpontaneous labor or a Bishop Score ≥6 within 48 h of mifepristone administration. Secondary outcomesenrollment-induction to delivery interval, rate of failed induction, doses of prostaglandin used, mode of delivery, requirement of oxytocin augmentation, and neonatal outcomes. ResultsThis study enrolled 231 women, 108 in the first and 123 in the second period undergoing induced labor at term caused by various obstetric conditions. There were no significant differences between groups for age, body mass index, gravida, parity, the initial Bishop Score, scarred uterus, or post-term pregnancy.There were statistically significant differences between the two groups concerning spontaneous labor and/ or a Bishop Score ≥6 within 48 h (p < 10-3) and received doses of misoprostol (p = 0.01). Patients receiving mifepristone were 10 times more likely to be in labor after 48 h of inclusion (RR = 9.98, CI 95 % = [4.47–22.29]).The enrollment-induction to delivery interval was significantly shorter for the mifepristone group (p < 0.001). There were no other differences in mode of delivery, placenta abnormalities or neonatal outcomes. ConclusionMifepristone efficiently induced cervical ripening and labor initiation in women with normal pregnancies at or beyond term. It may offer an alternative method to the classic induction especially for patients seeking spontaneous labor.