bluuebunny/crossref_metadata_2025 huggingface dataset:
Size and Topology Optimization of Inertial Amplification Induced Phononic Band Gap Structures
Authors: Yuksel Osman , Yilmaz Cetin
Published: January 2018

In this study, inertial amplification induced phononic band gaps are attained by performing structural optimization on a compliant unit cell mechanism of a one-dimensional periodic structure. First of all, stop band characteristics of the lumped parameter model of the unit cell mechanism is discussed. Next, the distributed parameter model of the compliant unit cell is presented. In order to obtain wide and deep inertial amplification induced stop bands, both size and topology optimization methods are utilized considering the distributed parameter model of the unit cell mechanism. The band gap characteristics of the infinite periodic size and topologically optimized mechanisms are compared. Moreover, vibration transmissibility of the finite periodic size and topologically optimized mechanisms are calculated and the effect of number of unit cells is discussed. Finally, a parametric study is carried out to demonstrate the effect of topology optimization design space volume fraction on the band gap limits.
A Hybrid Methodology Combining Functional and Probabilistic Analysis to Assess the Maintenance Plan of a Natural Gas Transmission System: A Turbo-Compressor Power Pack Case Study
Authors: Ferrans Orlando , Aparicio Walter , Martínez Andrea , Audivet Cinthia , Pinzón Horacio , Sanjuán Marco
Published: January 2018

A probabilistic analysis is an approach that allows to identify whether if preventive, predictive and corrective maintenance practices are efficient for keeping the overall system safety. The implementation of methodologies that evaluate the maintenance plans are a way to improve existing programs. Promigas S.A. E.S.P. is a company that must guarantee the reliability and availability of its natural gas transmission systems to its consumers. Therefore, since 2009, the company has implemented reliability centered maintenance practices to achieve it. However, considering the current scenario of the natural gas in Colombia and according to the growth plans of the company, it is necessary to guarantee that the reliability and availability indexes remain close to 100%. To achieve the aforementioned objective, it is necessary to diagnose the current maintenance plan. We propose a hybrid methodology combining functional and probabilistic analysis to assess the maintenance plan of a natural gas transmission system, specifically a turbo-compressor power pack. The proposed methodology includes a new priorization method to identify and select critical components and its critical failure modes, through a qualitative functional and quantitative characterization of the subsystems that conform the turbo-compressor power pack. The probabilistic analyses were simulated for five time periods: one, three, six, nine and thirteen years. The results allow to conclude in terms of availability that while the maintenance plan is optimal for the first-time period, from the second time period the preventive and predictive maintenance practices must be optimized increasing resources or modifying the equipment intervention frequencies.
Analysis of Wind Turbine Capacity Factor Improvement by Correcting Yaw Error Using LIDAR
Authors: Bakhshi Roozbeh , Sandborn Peter
Published: January 2018

Yaw error is the angle between a turbine’s rotor central axis and the wind flow. The presence of yaw error results in lower power production from turbines. Yaw error also puts extra loads on turbine components, which in turn, lowers their reliability. In this study we develop a stochastic model to calculate the average capacity factor of a 50 turbine offshore wind farm and investigate the effects of minimizing the yaw error on the capacity factor. In this paper, we define the capacity factor in terms of energy production, which is consistent with the common practice of wind farms (rather than the power production capacity factor definition that is used in textbooks and research articles). The benefit of using the energy production is that it incorporates both the power production improvements and downtime decreases.

For minimizing the yaw error, a nacelle mounted LIDAR is used. While the LIDAR is on a turbine, it collects wind speed and direction data for a period of time, which is used to calculate a correction bias for the yaw controller of the turbine, then it will be moved to another turbine in the farm to perform the same task.

The results of our investigation shows that although the improvements of the capacity factor are less than the theoretical values, the extra income from the efficiency improvements is larger than the cost of the LIDAR.
Dynamic Modulus Predictive Model Based on Artificial Neural Network for the Superpave Asphalt Mixtures of New Mexico
Authors: Rahman A. S. M. Asifur , Tarefder Rafiqul A.
Published: January 2018

In this study, a new dynamic modulus predictive model for the Superpave asphalt-aggregate mixtures of New Mexico is developed based on the artificial neural network methodology. A total of 54 plant-produced asphalt-aggregate mixtures from all over the state were collected, compacted, cored, and sawed to cylindrical test specimens in the laboratory to conduct dynamic modulus testing at different temperatures and loading frequencies. A database containing 1,620 dynamic moduli with phase angles was then used to develop this artificial neural network based predictive model. A neural architecture with 2 twelve-node hidden layers was found to be remarkably suitable for predicting the dynamic modulus and phase angle of asphalt concrete. Statistical evaluation showed that a fairly accurate estimation of dynamic modulus can be attained by using this model.
Behavior of Bubbles Separated by a Cross-Shaped Obstacle Placed in a Circular Flow Channel
Authors: Takase Kazuyuki , Nguyen Hiep H. , Takase Gaku , Hiraki Yoshihisa
Published: January 2018

Clarifying two-phase flow characteristics in a nuclear reactor core is important in particular to enhance the thermo-fluid safety of nuclear reactors. Moreover, bubbly flow data in subchannels with spacers are needed as validation data for current CFD codes like a direct two-phase flow analysis code. In order to investigate the spacer effect on the bubbly flow behavior in a subchannel of the nuclear reactor, bubble dynamics around the simply simulated spacer was visually observed by a high speed camera. Furthermore, the void fraction and interfacial velocity distributions just behind the simulated spacer were measured quantitatively by using a wire-mesh sensor system with three wire-layers in the flow direction. From the present study, bubble separation behavior dependence upon the spacer shape was clarified.
Investigating Thermal Performance of PCM Plates for Free Cooling Applications in South Africa
Authors: Madyira Daniel M. , Mukhodobwane Ranwedzi P. , Jen Tien C.
Published: January 2018

Free cooling involves using a thermal energy storage medium such as a phase change material (PCM) in order to store the ambient “cold” during the night when ambient air temperatures are lower compared to the indoor building temperatures and release this stored “cold” by using a heat transfer fluid (i.e. air) into the building during the day when higher ambient temperatures are experienced especially during the summer months. This paper assesses the free cooling potential in South Africa by using a set of Rubitherm RT25HC PCM plates. The performance of these PCM plates is assessed by benchmarking the ambient air cooled by the PCM plates during the day against the defined thermal comfort temperatures requirements. The influence of varying the air flow rate on the availability of thermal comfort temperatures at the PCM rig outlet is also studied. The results clearly show the potential of using PCM’s as a means of cooling higher ambient air temperature which is experienced in hot summer months to within thermal comfort temperatures for human occupancy in a building.
Acoustic Pressure Fields Generated With a High Frequency Acoustic Levitator
Authors: Sracic Michael W. , Petrie Jordan D. , Moroder Henry A. , Koniecko Ryan T. , Abramczyk Andrew R. , Suthar Kamlesh
Published: January 2018

Acoustic levitation is an advantageous particle positioning mechanism currently employed for applications of x-ray spectroscopy and micro-material manufacturing[1], [2]. By levitating a particle using only acoustic pressure waves, one eliminates the need for a container or other physical structure which may contaminate the specimen. Unfortunately, the pressure field generated by a standing acoustic wave is susceptible to periodic instabilities, and a particle that is levitated in this field tends to vibrate. The amplitude of the vibration is largest in the directions that are orthogonal to the axis in which the acoustic wave is generated. Therefore, by generating additional acoustic waves in each orthogonal axis, the vibration amplitude of the levitated particle is significantly reduced. The authors have shown this phenomenon to be true in a previous study[3].

In this paper, the authors explore the details of the pressure field that is generated with the device. A single degree-of-freedom relationship is developed between the acoustic field pressure, the location of the levitated particle, and the mechanical vibration needed to produce levitation. In order to levitate a 100 micrometer diameter water droplet at 55 kilohertz, the calculations suggest that the transducer must achieve an average surface vibration amplitude of at least 6.43 micrometers. This mechanical vibration must produce a root means-squared pressure amplitude of 933 Pascal. Under these conditions, the particle will levitate approximately 0.4 millimeters below a zero pressure node.

To validate the use of the single degree of freedom relationships and to explore the acoustic field for one, two, and three-axis levitation, the authors designed and prototyped an acoustic levitator capable of generating standing waves in three orthogonal directions. Using a simple electrical control circuit, the acoustic wave transducers of each axis can be turned on individually or simultaneously. An experiment was developed to measure the pressure of the acoustic field using a microphone. Preliminary pressure magnitude results were measured for one-axis levitation along the center of the vertical axis of the levitator. The measurements suggest that the theoretical development provides a valid first approximation for the pressure magnitude and required mechanical vibration amplitude.
Preliminary Nondestructive Testing Analysis on 3D Printed Structure Using Pulsed Thermography
Authors: Pierce James R. , Crane Nathan B.
Published: January 2018

Additive Manufacturing (AM) processes have vastly improved over the years and 3D-printed parts are no longer solely being used for prototyping but also as final products. Where AM parts are used in low-volume products, nondestructive testing is critical to validate product performance. This paper will discuss using an infrared thermography technique known as Pulsed Thermography (PT) based on the analysis of a theoretical one-dimensional solution as a nondestructive testing method for quantitatively measuring defect depths within a 3D-printed part made from a thermoplastic ABS. This method has previously been applied to composites, ceramics, and metals for quantification of defects, but no work has been done for thermoplastic 3D printed parts. This technique can potentially be integrated into existing equipment for online monitoring during part construction. This paper will demonstrate the ability of a low-cost PT system to characterize the surface of 3D-printed parts and detect the effect of common parameter variations. The capability of a PT system as a viable NDT method to quantitatively analyze a 3D-printed part would allow for post process quality control in comparison to initial design and simulation.
Students’ Perceptions and Effects Towards New Teaching Approach in Energy and Environment
Authors: Ferreira Manuel E. , Leão Celina P.
Published: January 2018

This paper presents the results of a new teaching approach in the Energy and Environment 6, in the 5th and last year of the Integrated Master in Mechanical Engineering of University of Minho. This curricular unit focus on the fossil fuel resources and combustion. For a Mechanical Engineering starting his/her career this status quo can be seen as an opportunity rather than a barrier. Thus, the students were invited to do a research on several subjects with the purpose to find challenges and opportunities to be addressed. The final purpose of this project was to give motivation to the students in order to find ideas for new products, services, technologies, etc., to develop in their future career, based on the idea of finding things they should do for the world rather than ask others what to do. Summing up, to promote innovation and entrepreneurship. The results of the questionnaire to obtain students’ perceptions towards the implementation of this new teaching approach and assessment methodology in order to improve and apply it in the future are discussed showing a positive result.
Predicting the Failure Probability and Reliability Based Design, Optimization for Pipelines
Authors: Memon Shabbir , Mohammed Obaidur Rahman , Roozbahani Hamid , Lankarani Hamid M.
Published: January 2018

A probabilistic model is developed in this study for calculating the failure probability and finding the associated reliability for a given pipeline in a plant affected by the time-dependent failure by corrosion. This is accomplished by applying a probabilistic approach to the Shell-92 pipeline failure prediction model. The Monte Carlo simulation scheme is used to predict the probability of failure. The life cycle cost is also estimated based on predicted probability density function, which shows that failure cost is dominating the maintenance cost in overall life cycle cost. A sensitivity analysis is also carried out to investigate the influence of corrosion parameters on the probability of failure which reflects the effect of axial-radial corrosion rates and depth-length of corrosion defect on failure probability. At the end, optimized corrosion rates are also predicted using the reliability based design and optimization (RBDO) technique, in which the probabilistic constraint has been utilized based on the Shell-92 pipeline failure prediction model.
Effect of Temperature on the Evolved Microstructure During Laser Beam Forming of Sheet Steels
Authors: Akinlabi Stephen , Mashinini Madindwa , Akinlabi Esther
Published: January 2018

Laser Beam Forming (LBF) being a novel technique and non-contact manufacturing process, employs laser beam as the tool of shaping and bending metal sheets into different shapes and curvatures for various applications. LBF is a high-temperature process, where rapid heating and cooling occurs causing microstructural changes like dynamic recrystallization and phase changes. The study becomes necessary to ensure that the structural integrity of the processed material is not compromised. Hence, the investigation focuses on the effect of temperature on the developed microstructure during the LBF process. The design of experiment was considered, using three levels and five factors. The experimentally measured curvatures were validated with the predicted measured curvatures, which were found to be in agreement. The result shows that the developed ferrite and pearlite grains were due to the heating and cooling. Furthermore, the average grain sizes at a low energy density of about 355°C and high energy density of about 747°C were found to be about 10 μm and 6 μm respectively. It is implied that the high temperature from the high laser energy aided the deformation of the grains significantly. However, such high temperature must be closely monitored so to avoid metallurgical notches in the processed component.
Fuzzy Controller for Active Vibration Control of Cylindrical Shells
Authors: Li Hua , Hu Kaiming
Published: January 2018

Cylindrical shells are widely used engineering structures, such as pipelines, tubes, submarine shells, etc. The active vibration control of these structures are important methods for ensuring their performance. In this paper, a fuzzy logic controller was proposed for the active vibration control of cylindrical shells. Piezoelectric actuators were laminated on the shell surface for the generation of control force. Then, the mathematical model of the model control force were given based the inverse piezoelectric effects and modal summation method. The transfer equation of the controlled system was derived from the modal equation. The fuzzy logic controller was then designed, in which the centroid method was used for defuzification. The proposed controller was then implemented in Matlab/Simulink environment, followed by case studies to evaluate its performance. Numerical results shown the effectiveness of fuzzy logic controller on active vibration of smart cylindrical shells. For all evaluated cases, more than 33% of amplitude reduction were achieved.
Thermal Discomfort Detection Using Thermal Imaging
Authors: Burzo Mihai , Abouelenien Mohamed , Van Alstine David , Rusinek Kristen
Published: January 2018

Effective energy management in the buildings is one of the key factors impacting the overall energy consumption, and thus has important consequences on climate and the environment. Detecting human thermal discomfort can be potentially used to reduce energy consumption in both buildings and vehicles, while maintaining the thermal comfort sensation of the occupants. This paper proposes a non-contact approach that relies on the thermal features obtained from thermal imaging (owing to its advantage as a noninvasive and noncontact method), in order to automatically detect the thermal discomfort level without any explicit input from the user. This research makes three contributions. First, a novel dataset of thermal recordings of 50 subjects is collected. Second, we extract and analyze features from two different thermal cameras in order to accurately detect the thermal discomfort levels of subjects. Third, we explore the capabilities of the cameras features in detecting seven levels of comfort/discomfort levels within the three categories of comfortable, cold, and hot. Our approach is expected to enable innovative adaptive control scenarios for enclosed environments as well as an important reduction in energy consumption in both buildings and vehicles.
Heat Capacity of Nanoconfined Liquid: A Molecular Dynamics Simulation
Authors: Mahmud Rifat , Morshed A. K. M. Monjur , Paul Titan C.
Published: January 2018

Equilibrium molecular dynamics (EMD) simulations aiming to investigate the effect of confinement gap thickness on constant volume molar heat capacity (Cv) of the confined liquid in nanoscale have been carried out by simultaneously controlling the density and temperature of the liquid domain. Simplified Lennard-Jones (LJ) molecular model is used to model the system where the liquid is entrapped between two flat solid surfaces separated by a distance varying from 0.585 nm to 27.8 nm. Molar heat capacity of the bulk liquid has been evaluated using fluctuation formula which matches greatly with the NIST data and published literatures. But in case of confined liquid, molar heat capacity is observed to vary significantly with the gap thickness. For a specific range of gap thickness, molar heat capacity of the confined liquid is found higher than that of the bulk. But molar heat capacity of the nanogap confined liquid becomes independent of the gap thickness and approaches to that of the bulk liquid as gap thickness is greater than this specific range (6.14 nm for 100 K temperature of the confined liquid).
Optical and Infrared Study of the Effect of a High Electric Field on the Pool Boiling Behavior of a Sub-Cooled Dielectric Liquid
Authors: Sargunanathan Sathiyanathan , Basavanna Abhishek , Dhillon Navdeep S. , Mahmoudi Seyed Reza
Published: January 2018

The formation and departure of bubbles on hot surfaces is of fundamental significance in many engineering applications including in boiling heat transfer. Both the bubble growth behavior and the boiling heat transfer performance parameters are affected by different variables and conditions, an interesting one of which is the electric field. Understanding its effect is of considerable significance, as it has been observed experimentally that the application of an electric field can lead to a significant enhancement in the boiling critical heat flux of a dielectric fluid. Although the exact physical mechanism behind this effect is not well understood, we hypothesize that it could be correlated to the effect of the electric field on individual evaporating bubbles and their altered interactions with the boiling surface. In this study, we employ optical and infrared imaging techniques to experimentally illustrate the effect of an applied electric field on the behavior of bubbles in sub-cooled pool boiling of a dielectric liquid (HFE-7100). Results indicate that bubble nucleation behavior, bubble geometry, and the bubble three-phase contact line dynamics are all simultaneously affected by the electric field. To help explain the experimental results, we further implement a CFD numerical model of an individual vapor bubble in the presence of an applied electric field.
Advanced Heat Transfer Devices for Aerospace Applications
Authors: Kasim Kawthar , Muley Arun , Stoia Michael , Ladeinde Foluso
Published: January 2018

Aerospace system efficiency improvement and capacity growth has fueled demand for innovative, affordable and scalable thermal management technologies. Recent advancements in additive manufacturing (AM) and materials has extended the thermal design space for heat exchangers, cold plates, heat sinks, and heat pipes. Novel heat transfer enhancement techniques, along with design and system interface innovations, offer attractive cooling solutions for use in numerous aircraft systems. These advances are becoming increasingly relevant in aircraft systems as customers are demanding the use of air-cooling instead of liquid-cooling with minimal impact on overall energy conversion efficiency, installed volume and weight.

This paper provides an overview of Boeing-led advances in analysis, design, fabrication and testing of next generation heat transfer devices. A case study is presented to provide insight into a methodology for selection of heat transfer surfaces and design optimization for an air-to-air heat exchanger. Design considerations are presented for additive manufacturing of the thermal management devices using a range of high performance materials including aluminum, titanium, stainless steel, and conductive polymer composites.
A Simplified Analytical Model of Rolling/Sliding Behavior and Friction in Four-Point-Contact Ball Bearings and Screws
Authors: Lin Bo , Duan Molong , Okwudire Chinedum E. , Wou Jason S.
Published: January 2018

Four-point contact between ball and raceways is common in machine elements like ball bearings and ball screws. The ideal four-point-contact machine element is designed with pure rolling (i.e., no sliding at contact points) to minimize friction. However, this ideal may not always be achieved, leading to sliding and higher frictional forces. In this paper, a simplified analytical model for rolling/sliding behavior and friction in four-point contact is developed, based on Coulomb friction model and rigid body assumption. It is found that pure rolling is only possible when the contact-point geometry satisfies a certain relationship. When pure rolling condition fails to hold, the sliding contact point(s) can be determined analytically as a function of contact forces and contact angles. Case studies are presented to demonstrate how the proposed model could elucidate the roles of misalignments, manufacturing errors and loading conditions on rolling/sliding behavior and friction.
The largest deep-ocean silicic volcanic eruption of the past century
Authors: Carey Rebecca , Soule S. Adam , Manga Michael , White James D. L. , McPhie Jocelyn , Wysoczanski Richard , Jutzeler Martin , Tani Kenichiro , Yoerger Dana , Fornari Daniel , Caratori-Tontini Fabio , Houghton Bruce , Mitchell Samuel , Ikegami Fumihiko , Conway Chris , Murch Arran , Fauria Kristen , Jones Max P. , Cahalan Ryan , McKenzie Warren
Published: January 2018

A submersible study of the products of a large submarine eruption demonstrates the influence of the ocean on eruption dynamics.
Organic matter in extraterrestrial water-bearing salt crystals
Authors: Chan Queenie H. S. , Zolensky Michael E. , Kebukawa Yoko , Fries Marc , Ito Motoo , Steele Andrew , Rahman Zia , Nakato Aiko , Kilcoyne A. L. David , Suga Hiroki , Takahashi Yoshio , Takeichi Yasuo , Mase Kazuhiko
Published: January 2018

Abundant organic compounds were detected in brine-bearing halite crystals from a hydrovolcanically active asteroid.
Mobile nanotweezers for active colloidal manipulation
Authors: Ghosh Souvik , Ghosh Ambarish
Published: January 2018

Mobile nanotweezers integrate plasmonic nanostructures with magnetic, helical microrobots for manipulation of nano-objects.
Violence against children in South Africa: the cost of inaction to society and the economy
Authors: Hsiao Celia , Fry Deborah , Ward Catherine L , Ganz Gary , Casey Tabitha , Zheng Xiaodong , Fang Xiangming
Published: January 2018

Despite the extent and magnitude of violence against children in South Africa, political and financial investments to prevent violence against children remain low. A recent costing study investigating the social burden and economic impact of violence against children in South Africa found notable reductions to mental and physical health outcomes in the population if children were prevented from experiencing violence, neglect and witnessing family violence. The results showed, among others, that drug abuse in the entire population could be reduced by up to 14% if sexual violence against children could be prevented, self-harm could be reduced by 23% in the population if children did not experience physical violence, anxiety could be reduced by 10% if children were not emotionally abused, alcohol abuse could be reduced by 14% in women if they did not experience neglect as children, and lastly, interpersonal violence in the population could be reduced by 16% if children did not witness family violence. The study further estimated that the cost of inaction in 2015 amounted to nearly 5% of the country’s gross domestic product. These findings show that preventing children from experiencing and witnessing violence can help to strengthen the health of a nation by ensuring children reach their full potential and drive the country’s economy and growth. The paper further discusses ways in which preventing and ending violence against children may be prioritised in South Africa through, for instance, intersectoral collaboration and improving routine monitoring data, such as through the sustainable development goals.
How will the sustainable development goals deliver changes in well-being? A systematic review and meta-analysis to investigate whether WHOQOL-BREF scores respond to change
Authors: Skevington Suzanne M , Epton Tracy
Published: January 2018

Introduction

The Sustainable Development Goals (SDGs) 2015 aim to ‘…promote well-being for all’, but this has raised questions about how its targets will be evaluated. A cross-cultural measure of subjective perspectives is needed to complement objective indicators in showing whether SDGs improve well-being. The WHOQOL-BREF offers a short, generic, subjective quality of life (QoL) measure, developed with lay people in 15 cultures worldwide; 25 important dimensions are scored in environmental, social, physical and psychological domains. Although validity and reliability are demonstrated, clarity is needed on whether scores respond sensitively to changes induced by treatments, interventions and major life events. We address this aim.

Methods

The WHOQOL-BREF responsiveness literature was systematically searched (Web of Science, PubMed, EMBASE and Medline). From 117 papers, 15 (24 studies) (n=2084) were included in a meta-analysis. Effect sizes (Cohen’s d) assessed whether domain scores changed significantly during interventions/events, and whether such changes are relevant and meaningful to managing clinical and social change.

Results

Scores changed significantly over time on all domains: small to moderate for physical (d=0.37; CI 0.25 to 0.49) and psychological QoL (d=0.22; CI 0.14 to 0.30), and small for social (d=0.10; CI 0.05 to 0.15) and environmental QoL (d=0.12; CI 0.06 to 0.18). More importantly, effect size was significant for every domain (p<0.001), indicating clinically relevant change, even when differences are small. Domains remained equally responsive regardless of sample age, gender and evaluation interval.

Conclusion

International evidence from 11 cultures shows that all WHOQOL-BREF domains detect relevant, meaningful change, indicating its suitability to assess SDG well-being targets.
Prevalence and burden of chronic kidney disease among the general population and high-risk groups in Africa: a systematic review
Authors: Abd ElHafeez Samar , Bolignano Davide , D’Arrigo Graziella , Dounousi Evangelia , Tripepi Giovanni , Zoccali Carmine
Published: January 2018

Objectives

While increasing attention is paid to the rising prevalence of chronic diseases in Africa, there is little focus on chronic kidney disease (CKD). This systematic review assesses CKD burden among the general population and high-risk groups on the entire African continent.

Design, setting and participants

We searched Medline and PubMed databases for articles published between 1 January 1995 and 7 April 2017 by sensitive search strategies focusing on CKD surveys at the community level and high-risk groups. In total, 7918 references were evaluated, of which 7766 articles were excluded because they did not meet the inclusion criteria. Thus, 152 studies were included in the final analysis.

Outcome measurement

The prevalence of CKD in each study group was expressed as a range and pooled prevalence rate of CKD was calculated as a point estimate and 95% CI. No meta-analysis was done. Data were presented for different populations.

Results

In the community-level studies, based on available medium-quality and high-quality studies, the prevalence of CKD ranged from 2% to 41% (pooled prevalence: 10.1%; 95% CI 9.8% to 10.5%). The prevalence of CKD in the high-risk groups ranged from 1% to 46% (pooled prevalence: 5.6%; 95% CI 5.4% to 5.8%) in patients with HIV (based on available medium-quality and high-quality studies), 11%–90% (pooled prevalence: 24.7%; 95% CI 23.6% to 25.7%) in patients with diabetes (based on all available studies which are of low quality except four of medium quality) and 13%–51% (pooled prevalence: 34.5%; 95 % CI 34.04% to 36%) in patients with hypertension (based on all available studies which are of low quality except two of medium quality).

Conclusion

In Africa, CKD is a public health problem, mainly attributed to high-risk conditions as hypertension and diabetes. The poor data quality restricts the validity of the findings and draws the attention to the importance of designing future robust studies.
Assessing the effectiveness of a patient-centred computer-based clinic intervention,Health-E You/Salud iTu,to reduce health disparities in unintended pregnancies among Hispanic adolescents: study protocol for a cluster randomised control trial
Authors: Tebb Kathleen P. , Rodriguez Felicia , Pollack Lance M. , Trieu Sang Leng , Hwang Loris , Puffer Maryjane , Adams Sally , Ozer Elizabeth M. , Brindis Claire D.
Published: January 2018

Introduction

Teen pregnancy rates in the USA remain higher than any other industrialised nation, and pregnancies among Hispanic adolescents are disproportionately high. Computer-based interventions represent a promising approach to address sexual health and contraceptive use disparities. Preliminary findings have demonstrated that theHealth-E You/Salud iTu,computer application (app) is feasible to implement, acceptable to Latina adolescents and improves sexual health knowledge and interest in selecting an effective contraceptive method when used in conjunction with a healthcare visit. The app is now ready for efficacy testing. The purpose of this manuscript is to describe patient-centred approaches used both in developing and testing theHealth-E Youapp and to present the research methods used to evaluate its effectiveness in improving intentions to use an effective method of contraception as well as actual contraceptive use.

Methods and analysis

This study is designed to assess the effectiveness of a patient-centred computer-based clinic intervention,Health-E You/Salud iTu, on its ability to reduce health disparities in unintended pregnancies among Latina adolescent girls. This study uses a cluster randomised control trial design in which 18 school-based health centers from the Los Angeles Unified School District were randomly assigned, at equal chance, to either the intervention (Health-E Youapp) or control group. Analyses will examine differences between the control and intervention group’s knowledge of and attitudes towards contraceptive use, receipt of contraception at the clinic visit and self-reported use of contraception at 3-month and 6-month follow-ups. The study began enrolling participants in August 2016, and a total of 1400 participants (700 per treatment group) are expected to be enrolled by March 2018.

Ethics and dissemination

Ethics approval was obtained through the University of California, San Francisco Institutional Review Board. Results of this trial will be submitted for publication in peer-reviewed journals. This study is registered with the US National Institutes of Health.

Trial registration number

NCT02847858.
Improving the Written Medical Handover
Authors: Martin Rhys , Huddart Melanie , Garbett Cara , Storr Wendell , Watts Olivia , Gupta Sanjeev
Published: January 2018

The handover of large numbers of medical patients, during on call periods when staffing levels are reduced, is a challenge for all acute medical services. At the Royal Cornwall Hospital, a large district general hospital, we identified that foundation doctors were reviewing medical inpatients during weekend on call periods with limited written handover information. We chose to address this problem by developing an intervention, a weekend handover sticker, and piloting it. We used the review of documentation to measure improvement and feedback from users to assess the processes involved. Use of the weekend handover form improved the written communication between weekday and weekend teams. The number of weekend plans documented in the notes increased from 15% to 84% and the provision of a patient summary within the last 7 days increased from 26% to 94%. The feedback from users confirmed it was a useful intervention and 100% (15/15) of doctors and nurses responded positively to the question “Do you think the weekend sticker should be introduced and used at the weekend for all medical patients?” The feedback also identified concerns regarding additional workload for weekday ward staff and this has led to ongoing work to try and ensure that the weekend handover form continues to be used effectively to maintain an improved level of written handover information for on call staff. While we have not included a direct measure of patient care, we hope that by improving the quality of written handover information we are acting to ensure patient information is shared effectively, with likely positive impact on patient care.
Short-term risk of cardiovascular readmission following a hypertensive disorder of pregnancy
Authors: Jarvie Jennifer L , Metz Torri D , Davis Melinda B , Ehrig Jessica C , Kao David P
Published: January 2018

Objective

Women with pregnancies complicated by hypertensive disorders of pregnancy (HDP) have increased long-term cardiovascular (CV) risk. We sought to determine if they demonstrate increased short-term CV risk.

Methods

Using administrative records, all hospital-based deliveries in Florida from 2004 to 2010 and subsequent readmission to any Florida hospital within 3 years of index delivery were identified. Deliveries and clinical diagnoses were determined using International Classification of Diseases, Ninth Revision, Clinical Modification codes. HDP included pregnancies complicated by gestational hypertension, pre-eclampsia or eclampsia. Outcomes were CV readmission (acute myocardial infarction, stroke or heart failure), non-CV readmission and any readmission within 3 years of delivery excluding subsequent deliveries. Associations were determined using multivariate logistic regression.

Results

Among 1 452 926 records from delivering mothers of singleton infants (mean age 27.2±6.2 years; 52% white, 23% African American (AA), 18% Hispanic), there were 4054 CV and 259 252 non-CV readmissions. Women with HDP had higher CV readmission rates (6.4 vs 2.5/1000 deliveries; P<0.001). AA women had higher rates of CV readmission than whites or Hispanics (6.8 vs 1.7 vs 1.0/1000 deliveries, respectively; P<0.001). Women with HDP had higher multivariate risk of CV readmission (OR 2.41; 95% CI 2.08 to 2.80) and any readmission (OR 1.13; 95% CI 1.10 to 1.15). Compared with whites, AA women had higher risk for CV readmission (OR 3.60; 95% CI 3.32 to 3.90) after adjustment for HDP.

Conclusion

Women with HDP had twice the risk of CV readmission within 3 years of delivery, with higher rates among AA women. More work is needed to explore preventive strategies for HDP-associated events.
Biological Responses to Asbestos Inhalation and Pathogenesis of Asbestos-Related Benign and Malignant Disease
Authors: Solbes Eduardo , Harper Richart W
Published: January 2018

Asbestos comprises a group of fibrous minerals that are naturally occurring in the environment. Because of its natural properties, asbestos gained popularity for commercial applications in the late 19th century and was used throughout the majority of the 20th century, with predominant use in the construction, automotive, and shipbuilding industries. Asbestos has been linked to a spectrum of pulmonary diseases, such as pleural fibrosis and plaques, asbestosis, benign asbestos pleural effusion, small cell lung carcinoma, non-small cell lung carcinoma, and malignant mesothelioma. There are several mechanisms through which asbestos can lead to both benign and malignant disease, and they include alterations at the chromosomal level, activation of oncogenes, loss of tumor suppressor genes, alterations in cellular signal transduction pathways, generation of reactive oxygen and nitrogen species, and direct mechanical damage to cells from asbestos fibers. While known risk factors exist for the development of asbestos-related malignancies, there are currently no effective means to determine which asbestos-exposed patients will develop malignancy and which will not. There are also no established screening strategies to detect asbestos-related malignancies in patients who have a history of asbestos exposure. In this article, we present a case that highlights the different biological responses in human hosts to asbestos exposure.
Intrathecal baclofen therapy versus conventional medical management for severe poststroke spasticity: results from a multicentre, randomised, controlled, open-label trial (SISTERS)
Authors: Creamer Michael , Cloud Geoffrey , Kossmehl Peter , Yochelson Michael , Francisco Gerard E , Ward Anthony B , Wissel Jörg , Zampolini Mauro , Abouihia Abdallah , Berthuy Nathalie , Calabrese Alessandra , Loven Meghann , Saltuari Leopold
Published: January 2018

Background

Intrathecal baclofen (ITB) is a treatment option for patients with severe poststroke spasticity (PSS) who have not reached their therapy goal with other interventions.

Methods

’Spasticity In Stroke–Randomised Study' (SISTERS) was a randomised, controlled, open-label, multicentre phase IV study to evaluate the efficacy and safety of ITB therapy versus conventional medical management (CMM) with oral antispastic medications for treatment of PSS. Patients with chronic stroke with spasticity in ≥2 extremities and an Ashworth Scale (AS) score ≥3 in at least two affected muscle groups in the lower extremities (LE) were randomised (1:1) to ITB or CMM. Both treatment arms received physiotherapy throughout. The primary outcome was the change in the average AS score in the LE of the affected body side from baseline to month 6. Analyses were performed for all patients as randomised (primary analysis) and all randomised patients as treated (safety analysis).

Results

Of 60 patients randomised to ITB (n=31) or CMM (n=29), 48 patients (24 per arm) completed the study. The primary analysis showed a significant effect of ITB therapy over CMM (mean AS score reduction, −0.99 (ITB) vs −0.43 (CMM); Hodges-Lehmann estimate, −0.667(95.1%CI −1.0000 to −0.1667); P=0.0140). More patients reported adverse events while receiving ITB (24/25 patients, 96%; 149 events) compared with CMM (22/35, 63%; 77 events), although events were generally consistent with the known safety profile of ITB therapy.

Conclusions

These data support the use of ITB therapy as an alternative to CMM for treatment of generalised PSS in adults.

Trial registration number

NCT01032239; Results.
Sex-stratified analysis of national trends and outcomes in isolated tricuspid valve surgery
Authors: Chandrashekar Pranav , Fender Erin Amanda , Zack Chad J , Reddy Yogesh N V , Bennett Courtney E , Prasad Megha , Al-Hijji Mohammed A , Stulak John M , Miller Virginia M
Published: January 2018

Objective

Female sex is a known risk factor for cardiac surgery, and tricuspid valve (TV) disease is more common in women. There are few data on sex-stratified surgical outcomes for isolated TV surgery. An administrative database was used to compare acute in-hospital outcomes between men and women undergoing isolated TV surgery.

Methods

Patients aged >18 who underwent TV repair or replacement from 2004 to 2013 were identified using the National Inpatient Sample. Patients were excluded if they had congenital heart disease, endocarditis, or were undergoing concomitant cardiac surgeries except coronary bypass. Results were weighted to represent national averages. Sex-stratified analysis was performed using propensity score matching to compare in-hospital mortality, postoperative complications and hospital costs.

Results

Over 10 years, women represented 58% of the 5005 TV surgeries performed. With propensity matching, hospital mortality (7.9% vs 7.7%; P=0.99) and median length of stay (11 vs 11 days; P=0.99) were similar between men and women. However, median hospital charges were higher for men ($166 000 vs $155 000; P=0.04).

Conclusion

Isolated TV surgery is rare, but women more commonly undergo the procedure. In-hospital mortality was similar between men and women after propensity matching, but remains markedly high for both men and women in comparison to that reported for left-sided isolated valve surgery.
Impact of nutritional indices on mortality in patients with heart failure
Authors: Yoshihisa Akiomi , Kanno Yuki , Watanabe Shunsuke , Yokokawa Tetsuro , Abe Satoshi , Miyata Makiko , Sato Takamasa , Suzuki Satoshi , Oikawa Masayoshi , Kobayashi Atsushi , Yamaki Takayoshi , Kunii Hiroyuki , Nakazato Kazuhiko , Suzuki Hitoshi , Ishida Takafumi , Takeishi Yasuchika
Published: January 2018

Background

Malnutrition is a common condition that is associated with adverse prognosis in patients with heart failure (HF). The Prognostic Nutritional Index (PNI), Geriatric Nutritional Risk Index (GNRI) and controlling nutritional status (CONUT) have all been used as objective indices for evaluating nutritional status. We aimed to clarify the relationship between these nutritional indices and the parameters of inflammatory markers, cardiac function and exercise capacity, as well as to compare the ability of these indexes for predicting mortality.

Methods

We evaluated PNI, GNRI and CONUT in consecutive 1307 patients with HF.

Results

First, there were significant correlations between nutritional indices and the following: C reactive protein; tumour necrosis factor-α; adiponectin; B-type natriuretic peptide; troponin I; inferior vena cava diameter and peak VO2(P<0.05, respectively). Second, in the Kaplan-Meier analysis (follow-up 1146 days), all-cause mortality progressively increased from normal to mild, moderate and severe disturbance groups in the indices (log-rank, P<0.01, respectively). In the Cox proportional hazard analysis, each index was an independent predictor of all-cause mortality in patients with HF (P<0.001, respectively). Third, receiver operating curve demonstrated that the areas under the curve of PNI and GNRI were larger than that of CONUT score (P<0.05, respectively).

Conclusion

Patients with HF being malnourished had higher mortality accompanied by higher levels of C reactive protein, tumour necrosis factor-α, adiponectin, B-type natriuretic peptide, troponin I, right-sided volume overload and impaired exercise capacity, rather than left ventricular systolic function. Additionally, PNI and GNRI were superior to CONUT score in predicting mortality in patients with HF.
Prognosis of patients with secondary mitral regurgitation and reduced ejection fraction
Authors: Mowakeaa Samer , Dwivedi Aeshita , Grossman Jason R , Parikh Gaurav , Curillova Zelmira , Aragam Krishna G , Elmariah Sammy , Kinlay Scott , Aragam Jayashri
Published: January 2018

Objective

The impact of the severity of secondary mitral regurgitation (MR) on the risk of death and heart failure (HF) hospitalisations in patients with reduced left ventricular (LV) systolic function is poorly defined. The study sought to identify the incremental risk of secondary MR in patients with reduced LV systolic function.

Methods

We studied 615 consecutive patients with LV ejection fraction ≤35% by transthoracic echocardiography at a single medical centre. Patients were divided into three groups of no MR, mild, or moderate to severe MR. The median follow-up was 2.9 years. The primary endpoint was a composite of death or HF hospitalisations.

Results

Compared with patients with no MR, the risk of death or HF hospitalisations was higher for mild MR (HR 1.7, P=0.003) and moderate to severe MR (HR 2.7, P<0.001). The risk was also higher for the component endpoints of HF hospitalisations (mild MR: HR 2.3, P=0.001; moderate to severe MR: HR 3.5, P<0.001) and death (mild MR: HR 1.6, P=0.033; moderate to severe MR: HR 2.6, P<0.001). After adjustment for other covariates, MR was no longer significantly associated with death or HF hospitalisations, or death alone, but remained significantly associated with HF hospitalisations (mild MR: HR 1.7, P=0.028; moderate to severe MR: HR 2.2, P=0.002).

Conclusions

In patients with reduced LV systolic function, secondary MR is associated with an increased risk of HF hospitalisations but not death.