bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined event‐ and self‐triggered control approach with guaranteed finite‐gain stability for uncertain linear systems
Authors: Kishida Masako , Kögel Markus , Findeisen Rolf
Published: May 2017

A networked control strategy that maintains the finite‐gain stability for uncertain linear systems is proposed. The focus is placed on the reduction of the communication and energy usage that are required for the sampling and control signal updates. The approach differs from many existing approaches in that it computes the time instance of the sampling and the time instance of the control signal update separately; a self‐trigger condition is used to determine the time instance of sampling, while an event‐trigger condition is used at every time of sampling to decide if a new control signal should be transmitted to the actuator. This approach not only reduces the number of the control signal updates compared with the case of using only the standard self‐triggered control, but also allows one to balance the cost associated with the sampling and the cost associated with the control signal update. The approach and its benefits are illustrated by simulations.
Fault detection for discrete‐time Lipschitz non‐linear systems in finite‐frequency domain
Authors: Gu Ying , Yang Guang‐Hong
Published: May 2017

In this study, the problem of fault detection (FD) observer design for discrete‐time Lipschitz non‐linear systems with finite‐frequency specifications is investigated. The finite‐frequency and indices are introduced to measure the robustness to unknown disturbances and the sensitivity to faults, respectively. Based on the use of a reformulated Lipschitz property, the non‐linear error dynamics are transformed into a linear parameter varying (LPV) system. A new lemma is proposed to characterise the system performances in finite‐frequency domain. To reduce the conservativeness of the multi‐objective problem, slack variable techniques are used to obtain the sufficient conditions for the design of FD observer which are derived in terms of linear matrix inequalities (LMIs). The proposed design method can provide less restrictive LMI conditions and achieve a better FD performance than the existing one in full frequency domain. Two numerical examples are given to show the effectiveness and superiority of the new results.
p th moment exponential stabilisation of hybrid stochastic differential equations by feedback controls based on discrete‐time state observations with a time delay
Authors: Zhu Quanxin , Zhang Qiuyan
Published: May 2017

The authors are concerned with the stability of hybrid stochastic differential equations by feedback controls based on discrete‐time state observations. Under some reasonable conditions, they establish an upper bound on the duration between two consecutive state observations. Moreover, we can design the discrete‐time state feedback control to stabilise the given hybrid stochastic differential equations in the sense of p th moment exponential stability by developing a new theory. In comparison to the results given in the previous literature, this study has two new characteristics: (i) the stability criterion concerns p th moment exponential stability, which is different from the existing works; (ii) discrete‐time state observations depend on time delays.
Discrete current control with improved disturbance rejection for surface‐mounted permanent magnet synchronous machine at high speed
Authors: Liao Yong , Li Fu , Lin Hao , Zhang Jimiao
Published: May 2017

The virtual resistance technique has been widely adopted to improve the disturbance rejection of the complex vector decoupling approach for surface‐mounted permanent magnet synchronous machines at high speed. Its gain selection, however, has only been discussed in the continuous domain. In this study, the virtual resistance technique is analysed directly in the discrete domain. Theoretical analyses demonstrate that there is a definite upper limit for the virtual resistance selection which is only dependent on the ratio between the time constant of the machine and the sampling period. A new discrete current controller is proposed to improve the command tracking and the disturbance rejection of the current loop. A trade‐off is made between the rapidity and the robustness of the proposed controller in order to achieve a parameter error tolerance of 50%. Experimental results verify that the proposed controller gains better performance at high speed, i.e. a higher bandwidth of 0.135fs without overshoots and fewer oscillations, than the controllers designed in the continuous domain. Even deadbeat responses, to both the reference signals and the disturbance, can be achieved by the proposed controller at its limits.
Analysis and implement of the single‐phase voltage‐controlled grid‐connected inverter
Authors: He Chaojie , Zhao Jinbin , Zhang Shuaitao , Ushiki Shuuichi
Published: May 2017

This study describes the design and implementation of an inverter control algorithm with both the inverter inner controllable impedance and governor‐free characteristics. The inverter controlled as a voltage supply works with open‐loop power control in grid‐connected operation. It is realised that a pulse‐width modulation inverter mimics the primary frequency and voltage modulation characterised similarly to a synchronous generator. On the basis of the proposed control algorithm, the inner controllable impedance and governor‐free characteristics are analysed mathematically. Simultaneously, the authors analyse the output power characteristics of the proposed inverter and the level of the decoupled power control for designing the inner controllable impedance. When the inverter connects with the stiff grid, it will appear as the output current deviation problem. The generation mechanism of the dc component from the proposed inverter is clearly identified. The current deviation compensation control is analysed and implemented to solve it. Simulations and experimental results are given to verify the idea.
Design of LCL‐filter considering the control impact for grid‐connected inverter with one current feedback only
Authors: Xu Jinming , Xie Shaojun , Huang Liuliu , Ji Lin
Published: May 2017

An LCL‐filter draws much attention in grid‐connected applications, but the design faces challenges. The LCL and controller parameters are interdependent and inter‐restricted as the grid current quality and control stability rely on the parameters of them both. In the past, researchers found that extra sensors or complex algorithms were required for the stability when the LCL parameters were designed independently. Consequently, the system cost and complexity were increased. Indeed, the LCL‐filter with the delay‐dependent single‐loop current control can be stable if the LCL parameters are properly selected. Based on this thought, this study proposes to design the LCL parameters by considering their impact on the stability and dynamic of the inverter. Extra sensors or complex algorithms are no longer required. Based on establishing the model of the single‐loop inverter‐side current controlled inverter, the criteria of LCL design are obtained in order to improve the stability and the rejections of low‐order and switching current harmonics. Based on those design criteria, a step‐by‐step procedure is proposed. Selected results have been provided to demonstrate the effectiveness of the proposed design.
New bidirectional multilevel inverter topology with staircase cascading for symmetric and asymmetric structures
Authors: Samsami Hosein , Taheri Asghar , Samanbakhsh Rahim
Published: May 2017

Inverters, as one of the key components of electrical systems, have experienced a great evolution in the last decade, and their performance improvement is a challenge even today, leading to many researches on topologies and control schemes. This study introduces a new multilevel converter topology which is able to supply bidirectional current loads. The proposed structure has fewer power electronic devices such as power switches, driver circuits, power diodes, and DC voltage sources and, can be designed in both symmetric and asymmetric structures. In order to increase the number of output levels and the proposed basic unit development, modular expansion or cascading methods can be used. This study demonstrates that the aforementioned methods have the best results in asymmetric and symmetric structures of the proposed topology, respectively. The comparison between the proposed converter and some previous topologies shows that it has better conditions with respect to the used semiconductor count, switching and conduction losses, and total blocking voltage. The operation and performance of the proposed multi‐level converter have been ascertained through simulations and verified experimentally for a single‐phase symmetric thirty‐one‐level inverter which shows the proposed converter's ability in smooth sinusoidal output voltage generation with minimum total harmonic distortion.
Battery and supercapacitor for photovoltaic energy storage: a fuzzy logic management
Authors: Cabrane Zineb , Ouassaid Mohammed , Maaroufi Mohamed
Published: May 2017

This study presents an approach of the voltage regulation of DC bus for the photovoltaic energy storage by using a combination of batteries and supercapacitors (SCs). The batteries are used to meet the energy requirements for a relatively long duration, whereas the SCs are used to meet the instantaneous power demand. The energy management strategy is developed to manage the power flows between the storage devices by choosing the optimal operating mode, thereby to ensuring the continuous supply of the load by maintaining the state‐of‐charge (SoC) of SCs (SoCsc) and the SoC of the batteries (SoCbat) at acceptable levels. This energy management strategy is performed by using the fuzzy logic supervisor. The validation results prove the effectiveness of the proposed strategy.
Research on a double float system for direct drive wave power conversion
Authors: Liu Chunyuan , Yu Haitao , Liu Qiang , Zhong Weibo , Zhu He
Published: May 2017

The development and reasonable utilisation of wave energy have great realistic significance for solving environment pollution and energy crisis. A direct‐drive system with no middle conversion devices such as gear and turbine, which has a simple structure and good stability, is widely applied to wave power systems. First, the study analysed the structure of a tubular permanent magnet linear generator. The structure of short primary and long secondary is chosen for wave power systems because of the convenience of installation and higher power density. Then, based on finite‐element analysis, the structure of the generator is optimised by parametric analysis and genetic algorithm. A prototype is manufactured according to the optimised size, and the electromagnetic parameters are measured to verify the accuracy of simulation. Finally, a double floating direct‐drive wave power system is installed in the port of Lian Yungang, China, and the system is tested by still and dynamic water; the results show that the system can effectively convert wave energy into electricity.
Application of Edge theorem for robust stability analysis of a power system with participating wind power plants in automatic generation control task
Authors: Toulabi Mohammadreza , Bahrami Shahab , Ranjbar Ali Mohammad
Published: May 2017

This study investigates the dynamic participation of wind power plants (WPPs) in the automatic generation control (AGC) task. The pre‐specified model of wind farm in the AGC studies has been used. It is shown that operating of WPPs at the command mode results in a significant improvement in the frequency behaviour of power system due to their faster response. However, the WPPs may change their operation mode from the command mode to the maximum power point mode according to the wind speed conditions and load variations. This reduces the improvement in the frequency response. In this condition, the shortage in the wind power should be compensated by the conventional units. Thus, the share of different units becomes uncertain (but bounded) when the WPPs participate in the AGC task. To address this challenge, this study provides the robust stable frequency operation of power system under uncertain shares of different units in the AGC task using the Edge theorem. Simulations are performed on an IEEE 39‐bus test system connected to some wind farms in different buses. Results confirm the robust stability of the underlying power system, and hence, the effective capability of the wind farms to participate in the AGC task.
PV plant digital mapping for modules’ defects detection by unmanned aerial vehicles
Authors: Grimaccia Francesco , Leva Sonia , Niccolai Alessandro
Published: May 2017

Nowadays plant monitoring and control of renewable energy sources can take advantage of the use of unmanned aerial technologies. This manuscript aims to develop an image post‐processing tool for remote aerial images able to help operation and maintenance operators in photovoltaic (PV) defects detection using light unmanned aerial vehicles (UAVs). In particular, PV systems deployed in the field in the last ten years show often critical behaviour with a range of failures able to compromise the performance and energy yield of the power plants, thus they can greatly benefit of such novel technologies and tools. The described procedures are here tested on real plant data, with different kind of sensors, in order to find out potential advantages in fast fault detection tasks, using an automatic system for PV plants’ mapping. The results of this research will be reported in order to provide an understanding of potential impact of image processing techniques based on UAV in the renewable energy sector.
Portfolio theory applied to solar and wind resources forecast
Authors: Lima Marcello Anderson F.B. , Carvalho Paulo C.M. , Carneiro Tatiane C. , Leite Josileudo R. , de Bessa Neto Luiz J. , Rodrigues Géssica K.L. , de Melo Francisco E.
Published: May 2017

Power generation from decentralised renewable energy (RE) sources has been increasingly used worldwide. The authors apply portfolio theory (PT) to solar and wind resource forecast, combining those two intermittent RE sources in different percentages to investigate the resultant effects on the prediction error with the use of a proposed impact factor. They use solar and wind data from a weather station in Brazil's Northeast region. The use of PT to improve resource forecast of the specific solar and wind conditions found in that Brazilian region is a pioneer project and an original contribution of their research. Traditionally, PT has been used in the finance sector to reduce investment risks by diversifying applications. Considering predictability, the efficient frontier indicates an optimum portfolio for the period under investigation composed by 30% solar and 70% wind resource, obtained by the smallest calculated standard deviation. The obtained average forecast error for wind speed was −1.54% and for solar irradiance was 3.16%; the average forecast error resulting from the integration of 30% solar and 70% wind was −0.13%. This study innovates by using PT to solar and wind forecast in the planning phase, before the installation of wind and solar plants.
Source enumeration via GBIC with a statistic for sphericity test in white Gaussian and non‐Gaussian noise
Authors: Liu Yanyan , Sun Xiaoying , Zhao Shishun
Published: May 2017

We propose a source enumeration method via the generalised Bayesian information criterion (GBIC) based on a statistic for sphericity test in the white Gaussian and non‐Gaussian noise under a large array with few samples. Instead of joint probability of observations or sample eigenvalue distribution, the proposed method is based on a statistic for testing the sphericity of a positive definite covariance matrix, to overcome the limitation of the Gaussian observations assumption. Under the white noise assumption, the covariance matrix of the noise subspace components of the observations is proportional to an identity matrix, and this identity structure can be tested by a statistic for sphericity test. The observations are decomposed into signal and noise subspace components under a presumptive number of sources. When the presumptive noise subspace components do not contain signals, the corresponding statistic for sphericity test will have a certain Gaussian distribution, and the number of sources can be estimated via the GBIC with the test statistic. Simulation results demonstrate that the proposed method provides high detection probability in both the Gaussian and the non‐Gaussian noise, and performs better when the number of samples is less than the number of array sensors compared with other methods.
Simulation framework for compressive sensing‐based through‐wall detection of moving targets
Authors: Dang Vinh , Kilic Ozlem
Published: May 2017

Detection of moving targets in cluttered environments is important in numerous applications, such as disaster search‐and‐rescue, law enforcement, urban warfare and so on. One of the popular techniques employed for this purpose is the use of stepped‐frequency continuous‐wave radar due to its low cost and reduced complexity. However, the stepped‐frequency radar suffers from long data acquisition time. This study focuses on the detection of moving targets in cluttered medium; such as behind walls, using stepped‐frequency radar enhanced by compressive sensing (CS). The application of CS enables the reconstruction of the target space using fewer frequencies, which decreases the acquisition time. This study presents simulation results that demonstrate the applicability of CS to stepped‐frequency radar measurements in accurately locating and tracking targets behind walls. The plane‐wave spectrum approach is employed in conjunction with through‐wall transmission coefficients for calculating the scattered fields of targets behind the wall. The received voltage at the antenna terminals is then computed by adopting the concept of complex antenna factor frequently used in Electromagnetic Compatibility (EMC) community, which fully takes into account the antenna effects, enabling an accurate simulation.
Methodology for reducing the filtering capacitor in low‐flicker LED drivers
Authors: Shagerdmootaab Ali , Moallem Mehrdad
Published: May 2017

The amount of light flicker in an AC–DC light‐emitting diode (LED) driver is dependent on the size of filter capacitors. In this study, a study is conducted on reducing the size of filter capacitor in an AC–DC buck–boost/flyback LED driver using flicker index and per cent flicker light measures. Using this approach, a procedure for minimising the filter capacitance is presented. It is then concluded that relatively small filter capacitors such as film or ceramic capacitors can be chosen while meeting light flicker requirements. Hence, an LED drive with a longer lifetime can be achieved when compared with a driver using electrolytic capacitors. Experimental studies are presented for a 20 W AC–DC buck–boost/flyback LED driver prototype which utilises ceramic capacitors for driving Cree CR22‐32L and XLamp XP‐G LED strings.
Effect of oleic acid on the stability and rheology of nanoaluminium/JP‐10 bi‐phase system
Authors: Chen Bing Hong , Liu Jian Zhong , Yao Feng , Li He Ping , Zhou Jun Hu
Published: May 2017

Aluminium (Al) nanoparticles absorbed by oleic acid (OA) were prepared to study the effect and mechanism of OA on the stability and rheology of a nanoAl/exo‐tetrahydrodicyclopentadiene (JP‐10) bi‐phase system. The absorption layer was characterised by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and energy dispersive X‐ray spectroscopy. The effect of OA on the stability and rheology of nanoAl/JP‐10 suspensions was measured. Results show that OA reduces the surface tension of JP‐10 and the contact angle between the two phases. The absorption of OA on the surface of the particles occurred through the reaction between the −COOH of OA the −OH of Al particles. The amount of absorption increased as the concentration of OA increased. Adding OA enhanced the stability of the nanoAl/JP‐10 bi‐phase systems by hindering particles aggregation. A suspension with 5.0% solid load demonstrated no clear layer separation 1 month after preparation with 1.0% OA. OA also reduced the viscosity of the systems. A 0.5% concentration of OA is best for a system with 20% solid load. The viscosity‐reducing effect of OA was determined by its comparative amount, and the ratio of OA/Al should be above 2.5%.
Real-Time Methylation-Specific Polymerase Chain Reaction for MGMT Promoter Methylation Clinical Testing in Glioblastoma
Authors: Ida Cristiane M , Butz Malinda L , Jenkins Robert B , Sarkaria Jann N , Kitange Gaspar J , Giannini Caterina , Kipp Benjamin R
Published: May 2017

Objectives

To develop and evaluate a real-time methylation-specific polymerase chain reaction (RT-MSP) MGMT assay, with a particular focus on small biopsies and indeterminate testing results.

Methods

We assessed formalin-fixed paraffin-embedded glioblastoma or gliosarcoma specimens (n = 641). A test-validation group (n = 51) with previously obtained reference laboratory (RL) results was used to determine performance characteristics of the RT-MSP assay. An indeterminate (equivocal) category was established for cases that could not be clearly classified as positive or negative.

Results

Overall agreement of RT-MSP and RL results was 91% (41/45 nonindeterminate cases). Discordant cases were tested by pyrosequencing, and results were most concordant with RT-MSP. Among cases with limited amounts of tissue (n = 7), six yielded valid results by RT-MSP (all negative); the single invalid result consisted of a stereotactic biopsy specimen obtained 14 years prior. A subset of indeterminate cases obtained during clinical testing (n = 18/575 [3%]) was also evaluated by pyrosequencing and showed a heterogeneous pattern of methylation across the eight interrogated CpG sites.

Conclusions

The RT-MSP assay that we developed in-house is a robust clinical detection method for the heterogeneous process of MGMT promoter methylation in glioblastoma.
Application of the cghRA framework to the genomic characterization of Diffuse Large B-Cell Lymphoma
Authors: Mareschal Sylvain , Ruminy Philippe , Alcantara Marion , Villenet Céline , Figeac Martin , Dubois Sydney , Bertrand Philippe , Bouzelfen Abdelilah , Viailly Pierre-Julien , Penther Dominique , Tilly Hervé , Bastard Christian , Jardin Fabrice
Published: May 2017

Motivation

Although sequencing-based technologies are becoming the new reference in genome analysis, comparative genomic hybridization arrays (aCGH) still constitute a simple and reliable approach for copy number analysis. The most powerful algorithms to analyze such data have been freely provided by the scientific community for many years, but combining them is a complex scripting task.

Results

The cghRA framework combines a user-friendly graphical interface and a powerful object-oriented command-line interface to handle a full aCGH analysis, as is illustrated in an original series of 107 Diffuse Large B-Cell Lymphomas. New algorithms for copy-number calling, polymorphism detection and minimal common region prioritization were also developed and validated. While their performances will only be demonstrated with aCGH, these algorithms could actually prove useful to any copy-number analysis, whatever the technique used.

Availability and implementation

R package and source for Linux, MS Windows and MacOS are freely available at http://bioinformatics.ovsa.fr/cghRA.

Supplementary information

Supplementary data are available at Bioinformatics online.
Corynebacterium kroppenstedtii Is an Emerging Cause of Mastitis Especially in Patients With Psychiatric Illness on Antipsychotic Medication
Authors: Wong Sally C. Y. , Poon Rosana W. S. , Chen Jonathan H. K. , Tse Herman , Lo Janice Y. C. , Ng Tak-Keung , Au Jonathan C. K. , Tse Cindy W. S. , Cheung Ingrid Y. Y. , Yuk Man-Ting , Luk Wei-Kwang , Yuen Kwok-Yung
Published: May 2017

This retrospective study of patients with Corynebacterium kroppenstedtii infections revealed a predominance of mastitis and a potential association with psychiatric illnesses. At least one third of our patients with C kroppenstedtii mastitis had psychiatric illness, and >92% received antipsychotic medications. Drug-induced hyperprolactinemia may be an important modifiable risk factor in these patients.
Early Intensive Leg Training to Enhance Walking in Children With Perinatal Stroke: Protocol for a Randomized Controlled Trial
Authors: Hurd Caitlin , Livingstone Donna , Brunton Kelly , Teves Michelle , Zewdie Ephrem , Smith Allison , Ciechanski Patrick , Gorassini Monica A. , Kirton Adam , Watt Man-Joe , Andersen John , Yager Jerome , Yang Jaynie F.
Published: May 2017

Background. Development of motor pathways is modulated by activity in these pathways, when they are maturing (ie, critical period). Perinatal stroke injures motor pathways, including the corticospinal tracts, reducing their activity and impairing motor function. Current intervention for the lower limb emphasizes passive approaches (stretching, braces, botulinum toxin injections). The study hypothesis was that intensive, early, child–initiated activity during the critical period will enhance connectivity of motor pathways to the legs and improve motor function.

Objective. The study objective was to determine whether early intervention with intensive activity is better than standard care, intervention delivered during the proposed critical period is better than after, and the outcomes are different when the intervention is delivered by a physical therapist in an institution vs. a parent at home.

Design. A prospective, delay-group, single-blind, randomized controlled trial (RCT) and a parallel, cohort study of children living beyond commuting distance and receiving an intervention delivered by their parent.

Setting. The RCT intervention was provided in university laboratories, and parent training was provided in the childs home.

Participants. Children 8 months to 3 years old with MRI-confirmed perinatal ischemic stroke and early signs of hemiparesis.

Intervention. Intensive, play-based leg activity with weights for the affected leg and foot, 1 hour/day, 4 days/week for 12 weeks.

Measurements. The primary outcome was the Gross Motor Function Measure-66 score. Secondary outcomes were motion analysis of walking, full-day step counts, motor evoked potentials from transcranial magnetic stimulation, and patellar tendon reflexes.

Limitations. Inter-individual heterogeneity in the severity of the stroke and behavioral differences are substantial but measurable. Differences in intervention delivery and assessment scoring are minimized by standardization and training.

Conclusions. The intervention, contrary to current practice, could change physical therapy interventions for children with perinatal stroke.
Using AFP Levels to Aid in Pre-Operative Planning for Sonographically Ambiguous Teratomas [6OP]
Authors: Walker Andrea , Castaneda Antonio , Mostofizadeh Sayedamin , Emily Prendergast , Cortessis Victoria K. , Holschneider Christine
Published: May 2017

INTRODUCTION:

To define a pre-operative serum alpha feto-protein (AFP) value that distinguishes mature cystic teratomas (MCT) from immature teratomas (IT) among ultrasonographically ambiguous teratomas.

METHODS:

In a three-institution retrospective cohort study, patients undergoing surgery for MCT or IT were reviewed to identify those with ambiguous teratomas on preoperative ultrasound. The receiver-operating curve (ROC) optimized to institution A preoperative AFP levels was used to determine a cut-off value distinguishing benign from malignant tumors, which was validated at institutions B and C.

RESULTS:

Of 379 Institution A patients, 347 had a sonographic diagnosis of MCT (pathology confirmed). 30 had sonographically ambiguous teratomas and preoperative AFP levels; pathology revealed 25 MCT and 5 IT. Median serum AFP for MCT [1.5 ng/mL (IQR 1.05 -2.45 ng/mL)] was significantly lower than for IT [27.0 ng/mL (IQR 8.65 - 193.7 ng/mL)] (p less than 0.001). Area under the ROC was greatest (0.984) for using an AFP cut-off value of 4.15 ng/mL, which was 100% sensitive and 92.0% specific for IT. In the validation cohort from Institutions B and C (N = 1,091; 157 sonographically ambiguous and AFP drawn; 144 MCT, 13 IT), preoperative AFP exceeded 4.15 ng/mL in 10 of 13 with malignant tumors and 13 of 144 with benign tumors, yielding 77% sensitivity, 91% specificity, 44% PPV and 98% NPV. The 3 cases with AFP below the discriminatory zone had grade 1 stage 1A disease.

CONCLUSION:

An AFP cut-off of 4.15ng/mL offers excellent NPV and sensitivity, reducing instances in which a general gynecologist would unknowingly operate on a malignant tumor.
Lower Limb Compression Prevents Hypotension After Epidural in Labor Patients: A Randomized Controlled Trial [7OP]
Authors: Steinmetz Margaret M. , Shelton James A. , Watt Stacey A. , Johnson Jeffrey R.
Published: May 2017

INTRODUCTION:

Approximately 30% of patients who elect to have epidural anesthesia during labor experience hypotension, potentially causing complications for both mother and fetus. We evaluated whether lower limb compression at the time of epidural would decrease maternal hypotension.

METHODS:

A multisite randomized controlled trial was conducted. Term, singleton parturients requesting epidural were recruited and randomized into one of three arms: control, thrombo-embolic deterrent (TED) stockings, or sequential compression device (SCD). Hospital protocol was followed for intravenous fluid hydration prior to epidural placement. Blood pressures were evaluated at 1, 5, 15, 30, 45, and 60 minutes following administration of epidural bolus. Hypotension was defined as a decrease in either systolic or diastolic blood pressure of greater than 20% from baseline, which was the average of the three blood pressures obtained prior to the epidural. Analysis was based on intention to treat.

RESULTS:

Data from 71 patients were analyzed: 27 controls, 21 TEDs, and 23 SCDs. Demographics were similar across groups. Hypotension occurred in 66.7% of patients in the control arm compared to 52.4% of patients in the TED arm, and 30.4% in the SCD arm (P=.038). Logistic regression controlling for clinical site, delivery method, maternal age, gestational age at delivery, and maternal BMI did not affect the results.

CONCLUSION:

Lower limb compression using SCDs significantly decreased the incidence of maternal hypotension in laboring patients receiving epidural anesthesia. Our incidence of maternal hypotension was higher than what is reported in the literature.
Do 30-Day Postpartum Readmissions Rates Vary by Site of Care for Vulnerable Patients? [9OP]
Authors: Ranjit Anju , Zogg Cheryl , Witkop Catherine , Little Sarah , Haider Adil H. , Robinson Julian N.
Published: May 2017

INTRODUCTION:

To determine 30-day readmission rates following delivery in the United States, assess for access-based differences in readmission rates, and determine if differences vary by site of care.

METHODS:

We used Nationwide Readmissions Database to identify deliveries between January-October 2013. We categorized Medicaid, uninsured, and low-income patients as “vulnerable” and ranked hospitals by the proportion of vulnerable patients that they served. Differences in 30-day readmissions among higher (more than 74th percentile) versus lower (1-74th) vulnerable patient-serving hospitals were compared using multivariable logistic regression. Models adjusted for differences in patient demographics, comorbidities, pregnancy risk-status, type of deliveries, and hospital characteristics.

RESULTS:

A total of 1,392,622 deliveries were included, weighted to represent 3,932,181 deliveries nationwide. In 2013, 136 women/10,000 deliveries (1.4%) were readmitted within 30 post-discharge days. The most common reasons for readmissions were wound infection(n=1733, 9.1%), endometritis (n=1454, 7.7%), and hypertension(n=1181, 6.2%). A total of 732,441 (52.6%) deliveries were to vulnerable patients; 505,807 (36.3%) received care at hospitals managing a higher proportion of such patients. 30-day readmissions were higher among vulnerable patients (1.5% vs. 1.1%, OR [95% CI]: 1.39 [1.33-1.45]).

CONCLUSION:

Vulnerable patients experienced higher 30-day readmission rates, regardless of site of care. While differences were marginally pronounced at hospitals managing a lower proportion of vulnerable patients, the ubiquitousness of the finding across institutions speaks to the pervasive need to address disparities in perinatal care.
Secondary Benefits of CenteringPregnancy Care in an Adolescent Pregnant Population [10OP]
Authors: Roussos-Ross Dikea , O'Shea Tina , Ramos Mariana
Published: May 2017

INTRODUCTION:

CenteringPregnancy (CP), a group prenatal care model, has reported improved birth-related outcomes, specifically in preterm deliveries. Limited data exists, however, reporting additional benefits seen in patients receiving prenatal care within this model.

METHODS:

With IRB approval, a chart review was conducted comparing pregnancy related outcomes in patients who received care through the CenteringPregancy model vs the Traditional Prenatal Care model in our Women's Health Clinics at UF Health. A total of 20 patients, ages 18-21 received care via CP from March 2015–May 2016. These patients were compared to a random sample of 20 patients ages 18-21 who received care via the Traditional model from January 2014-December 2014.

RESULTS:

Although both groups showed similar breastfeeding initiation rates (95% CP vs 90% Control), the CP group showed significantly more breastfeeding at 6 weeks postpartum (42% vs 20%). Additionally, the CP group had significantly more adolescent patients elect LARC (32% vs 0%). Finally, the CP group showed significantly higher rates of immunizations in pregnancy: Influenza vaccine rates (45% CP, vs 30% Control) and TDaP vaccine rates (60% CP vs 35% Control).

CONCLUSION:

The CenteringPregnancy model may offer additional benefits in adolescent mothers, specifically: breastfeeding, contraception, and vaccination rates. Offering adolescent mothers group care allows for greater time with their provider, which in turn may lead to increased knowledge and understanding of health and pregnancy related outcomes. The outcomes noted in this study are promising and additional data may reveal that CenteringPregnancy may offer improved overall care in this population.
Long-Term Consequences of Extended Endocrine Strategies for Premenopausal Breast Cancer [11OP]
Authors: Kwon Janice S. , Pansegrau Gary , Nourmoussavi Melica , Hammond Geoffrey , Carey Mark
Published: May 2017

INTRODUCTION:

Breast cancer is the most common cancer among women in America, and gynecologists often encounter these women in their practice. After 5 years of adjuvant tamoxifen, women with ER+ breast cancer benefit from extended endocrine therapy, either with tamoxifen or an aromatase inhibitor (AI). For premenopausal women, ovarian ablation (OA) is required before starting an AI, but there is concern about the long-term outcomes (osteoporosis, heart disease) and costs of OA.

METHODS:

A Markov Monte Carlo simulation model estimated the costs and benefits of extended endocrine strategies in a hypothetical cohort of premenopausal women with ER+ cancer: (1) no further treatment; (2) tamoxifen for 5 years; (3) OA followed by AI for 5 years (OA/AI). Effectiveness was measured in years of life expectancy gain. Monte Carlo simulation estimated the number of adverse events and deaths from each strategy in the American population over a 40-year horizon.

RESULTS:

Tamoxifen for 5 more years yielded a higher average discounted life expectancy gain than OA/AI (16.57 vs. 16.34 years) at lower average cost ($2,976 vs. $10,150). For 18,000 ER+ premenopausal women diagnosed annually, the simulation estimated 12,526, 11,508, and 10,289 deaths after no further treatment, tamoxifen and OA/AI respectively, but another 2,139 deaths from long-term consequences of OA. According to sensitivity analyses, women had to be over 50.8 years of age before OA/AI became cost-effective.

CONCLUSION:

As extended endocrine therapy for premenopausal ER+ breast cancer, another 5 years of tamoxifen is more effective and less costly than ovarian ablation followed by 5 years of aromatase inhibitor.
Post-partum Management of Chorioamnionitis: Efficacy of Continuation of Antibiotics After Delivery [13OP]
Authors: Goldberg Aaron , Malik Meher
Published: May 2017

INTRODUCTION:

Chorioamnionitis, or infection of the fetal membranes, effects approximately 10% of laboring women. Antibiotic treatment prior to delivery reduces both maternal and neonatal infectious complications. Continuation of maternal treatment after delivery is standard practice yet has not been demonstrated effective at reducing post-partum endometritis or other complications and is based on expert opinion.

METHODS:

Following IRB approval, between March 2012 and October 2013, women delivering vaginally with chorioamnionitis meeting inclusion criteria and consenting to participate were randomized to receive antibiotics until afebrile for 24 hours following delivery or a single antibiotic dose following delivery. Outcomes include endometritis, post-partum fever, maternal length of stay, and total doses of antibiotics. Chorioamnionitis diagnosis and treatment was standardized across both groups. A systematic review of existing research was also conducted given the limited number of participants.

RESULTS:

Forty-six women were randomized, 23 in each group. Groups were similar in demographic and intrapartum characteristics. Those receiving a single antibiotic dose after delivery reviewed fewer total antibiotic doses (3.00 ± 1.00 vs. 7.04 ± 1.15, p less than 0.001). There were no significant differences for length of stay and no participants experienced treatment failures requiring resumption of antibiotics for endometritis or fevers. Four existing randomized trials with similar design including 305 women delivering vaginally also demonstrated no difference in postpartum complications among treatment groups.

CONCLUSION:

Antibiotics may be safely stopped following vaginal delivery in women with chorioamnionitis. Current practice of prolonged antibiotic treatment is not evidence based and should be reconsidered. Further research is warranted.
Comparing Diagnosis, Management, and Outcomes of Fetal Growth Restriction Using Hadlock vs. Fenton Growth Curves [14OP]
Authors: Rajaram Akhila M. , Strassberg Emmie R. , Paglia Michael J. , Bringman Jay J. , Neubert A. George , Mackeen A. Dhanya , Schuster Meike
Published: May 2017

INTRODUCTION:

Fetal growth restriction (FGR) is defined as an estimated fetal weight (EFW)

METHODS:

All singleton pregnancies at our institution were included that were diagnosed with FGR per Hadlock between 6/2014-5/2015. The EFWs were applied to the Fenton curve to reassess the diagnosis of FGR, as well as the number of abnormal umbilical artery Doppler (UAD) measurements, incidence of small for gestational age (SGA) neonates (birth weight

RESULTS:

A 77.3% reduction in FGR diagnosis was noted from 110 pregnancies identified by Hadlock to 25 pregnancies identified by Fenton. If the Fenton curve was applied, the number of iatrogenic deliveries for FGR would have been 19 (instead of 62) in the cohort (p=0.0243). There were no differences in the number of absent or reversed UAD identified, SGA deliveries, antenatal steroid administered or NICU admission. There were no stillbirths/neonatal deaths in our cohort.

CONCLUSION:

By applying the Fenton growth curve, the number of FGR diagnoses is reduced without a resultant increase in perinatal morbidity; additionally, the burden of antenatal testing, ultrasounds, and iatrogenic deliveries is also reduced.
An Examination of Posttraumatic Stress Disorder (PTSD) Among Women Living With HIV (WLHIV) [15OP]
Authors: Ereme Keemi , Cardin Noa , McCaul Mary E. , Hutton Heidi E.
Published: May 2017

INTRODUCTION:

The purpose of this study is to quantify the prevalence of PTSD in WLHIV in a high risk population. WLHIV have a prevalence of PTSD that is five time higher than in the general population. A diagnosis of PTSD in WLHIV is associated with poor antiretroviral treatment (ART) adherence, alcohol dependence, and negative health outcomes.

METHODS:

369 WLHIV were recruited from April 2006 to July 2010 from the Johns Hopkins HIV Clinic in Baltimore, MD. The Structured Clinical Interview for the DSM IV (SCID) was used to determine psychiatric diagnoses. All participants were categorized as having: no trauma, trauma, or PTSD. SCIDS were processed using double blind coding. We controlled for age, race, and illicit drug use.

RESULTS:

The majority of women experienced at least one trauma (82.3%). About half of the study sample met criteria for lifetime PTSD (43.1%) and 20% met criteria for current PTSD (19.9%). The most common traumas were rape (39.3%), physical assault (28.7%), and seeing violence (17.1%). One third of all rapes occurred before the age of 17 (34.7%). Molestation was also prominent in this sample with 10.8% reporting inappropriate sexual conduct under the age of 15. Major depressive disorder (MDD) was the most frequent co-morbid psychiatric diagnosis (lifetime MDD= 48.6%; current MDD=12.3%).

CONCLUSION:

Findings from this study demonstrate the need for PTSD and trauma screening in the integrative treatment of WLHIV for better health outcomes and the avoidance of behaviors that negatively impact health and longevity.
Adherence to Recommended Cervical Cancer Screening Based on Human Papillomavirus Vaccination Status [17OP]
Authors: Terk Daniel , Bonham Adrienne , Caveglia Sarah , Li Dongmei , Prast Brendan , Day Serena
Published: May 2017

INTRODUCTION:

Human Papillomavirus (HPV) vaccination and routine cervical cytology both aim to prevent cervical cancer, however limited data exists for how vaccination affects patient behavior. The objective of this study is to examine if adherence to cervical cancer screening is affected by HPV vaccination.

METHODS:

Retrospective chart review was completed using billing data for cervical cytology and HPV vaccination from 2006 to 2010. These years were chosen because the HPV vaccine was released in 2006, and annual cervical cytology was recommended until 2010. Participants were included based on birth year, ensuring participants were old enough to obtain cervical cancer screening and young enough to receive the HPV vaccine. For inclusion two or more cervical cytology samples were needed, and vaccination status confirmed via billing data or chart review. Adherence to cervical cancer screening was assessed using a ratio of appropriately timed pap smears to all pap smears in the study period.

RESULTS:

2,397 charts were reviewed, 943 were included, of these 350 were vaccinated and 593 were unvaccinated. Adherence to screening was not affected by overall vaccination status. For the sub-group of women vaccinated mid-study, adherence was compared before and after vaccination and it was found that these women were significantly less likely to be adherent after vaccination (N=140, adjusted OR 0.19, CI 0.08 - 0.49).

CONCLUSION:

Comparing patterns of adherence to cervical cancer screening before and after vaccination shows that women were less likely to adhere to screening guidelines after HPV vaccination. This may represent an unintended consequence of the HPV vaccination program.
Increased Incidence of Endometrial Cancer Following the WHI: An Assessment of Risk Factors [18OP]
Authors: Constantine Ginger , Kessler Grant , Goldstein Steven R.
Published: May 2017

INTRODUCTION:

The US incidence of Type I Endometrial cancer (EC) dramatically increased following the Women’s Health Initiative (WHI). While most cancer rates are decreasing, EC incidence increased from 2003 to 2013. EC rates were stable 1992 to 2002, prior to the announcement of WHI results. Potential etiologies for this increase are examined, including compounded hormone therapy use, which may not provide adequate endometrial protection.

METHODS:

EC incidence was obtained from Surveillance, Epidemiology, and End Result Program database from 1975 through 2013. The incidence of risk factors thought to be associated with EC, including age, obesity, race, number of menstrual cycles, gravidity and parity, metabolic syndromes (diabetes mellitus, PCOS), diet and exercise, and medications (hormone therapy including FDA-approved and unapproved [compounded] estrogens and progesterone, tamoxifen, and hormonal contraceptives) were evaluated and temporal trends were compared to EC trends.

RESULTS:

Endometrial cancer rates were constant from 1992 to 2002 in women 50-74 years of age, but have increased 2.5% annually with a 10% increase from 2006 to 2012 (test for trend 0.82). The greatest percentage of new cases was in women 55-64 years of age. Use of estrogen and progestin combinations have decreased while risk factors remained constant or decreased during the same time; however, obesity and compounded hormone use have increased coincident with the EC increase.

CONCLUSION:

EC increased post-2002 following the WHI, which may be multifactorial. The combination of an increase in obesity concurrent with decreasing exogenous progesterone and an increase in compounded hormone therapy is a public health issue requiring further evaluation.
Detection of Fetal Fraction During Noninvasive Prenatal Screening in HIV Infected Pregnant Women [21OP]
Authors: Aziz Aleha , Van Arsdale Anne , Klugman Susan , Wright Rodney L.
Published: May 2017

INTRODUCTION:

To describe the reliability of Noninvasive Prenatal Screening (NIPS) in HIV infected (HIV+) pregnant women. NIPS analyzes cell free fetal DNA which circulates in maternal plasma but originates from the placenta and is quantitated as “fetal fraction” (FF). Sensitivity of NIPS increases with FF. NIPS reliability decreases in certain situations, such as obesity, due to decreased FF. Our study aims to determine if immune system alterations such as HIV or antiretroviral medications impact FF.

METHODS:

A 2:1 matched case-control study was carried out comparing 20 HIV+ pregnant women to 40 without HIV undergoing NIPS. Univariable and multivariable conditional logistic regression was fit to assess the association between demographic and clinical variables, and FF. Immune status and antiretroviral medications were evaluated in correlation with FF in HIV+ patients.

RESULTS:

HIV+ patients receiving integrase inhibitors (INI) had lower mean FF than those without INI - 6.18 (SD 3.68) versus 12.87 (SD 6.03) (p= 0.006). HIV + patients with an undetectable viral load (VL) at NIPS had a lower median FF than those with a detectable VL – 6.5 versus 11.8 (p=0.28). INI users had a significantly lower median VL at NIPS compared to non-INI users (p=0.02).

CONCLUSION:

Integrase inhibitors may play a role in reliability of NIPS in HIV+ women, as reflected by lower FF for patients taking INI. INI use is increasing due to their tolerability and potency, thereby potentially making our findings more significant. Further study is needed to fully elucidate the mechanism for INI and decreased FF.