bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Method for Eyring Shear-Thinning Models in Elliptical Contacts Thermal Elastohydrodynamic Lubrication
Authors: Liu Xiaoling , Ma Mingming , Yang Peiran , Guo Feng
Published: March 2018

A new method for solving the shear stress and the effective viscosity of Eyring shear-thinning fluid in thermal elastohydrodynamic lubrication (EHL) was proposed and applied to two models. Model 1 is the thermal EHL model with one-direction velocity, and model 2 is the spinning thermal EHL model in which the velocity varies with coordinates. Comparisons between the new and the existing method were carried out. Results show that only replacing the shear strain rate of model 1 with that of model 2, the shear stress and the effective viscosity of model 2 for Eyring shear-thinning fluid can be obtained. For model 1, results obtained with the two methods are the same. The new method can be qualified and applied into model 2. It is proved that the new method has higher efficiency for shear-thinning fluid than the existing method. Therefore, the new method is more efficient and can be used for spinning Eyring shear-thinning thermal EHL.
Thermal Analysis of an Oil Jet-Dry Sump Transmission Gear Under Mixed-Elastohydrodynamic Conditions
Authors: Fatourehchi Ehsan , Shahmohamadi Hamed , Mohammadpour Mahdi , Rahmani Ramin , Theodossiades Stephanos , Rahnejat Homer
Published: March 2018

Improved fuel efficiency and reduced emissions are key drivers for modern drivetrain systems. Therefore, in recent years, dry sumps with air–oil mist lubrication have been used for efficient transmission design in order to reduce the churning losses. With dry sumps, appropriate cooling measures should be implemented to dissipate the generated contact heat in an efficient manner. This paper integrates a tribological model with three-dimensional (3D) thermofluid analysis in order to predict the heat generated in the lubricated meshing gear contacts and its dissipation rate by an impinging oil jet in air–oil mist environment. Such an approach has not hitherto been reported in literature. The results show that the generated heat under realistic conditions cannot be entirely dissipated by the impinging oil jet in the air–oil mist transmission casing. Numerical results are used to derive extrapolated regressed equations for heat transfer purposes for time-efficient analysis. These conform well with the detailed numerical results.
Actuation of Higher Harmonics in Large Arrays of Micromechanical Cantilevers for Expanded Resonant Peak Separation
Authors: Dick Nir , Grutzik Scott , Wallin Christopher B. , Robert Ilic B. , Krylov Slava , Zehnder Alan T.
Published: March 2018

A large array of elastically coupled micro cantilevers of variable length is studied experimentally and numerically. Full-scale finite element (FE) modal analysis is implemented to determine the spectral behavior of the array and to extract a global coupling matrix. A compact reduced-order (RO) model is used for numerical investigation of the array's dynamic response. Our model results show that at a given excitation frequency within a propagation band, only a finite number of beams respond. Spectral characteristics of individual cantilevers, inertially excited by an external piezoelectric actuator, were measured in vacuum using laser interferometry. The theoretical and experimental results collectively show that the resonant peaks corresponding to individual beams are clearly separated when operating in vacuum at the third harmonic. Distinct resonant peak separation, coupled with the spatially confined modal response, make higher harmonic operation of tailored, variable-length cantilever arrays well suited for a variety of resonant-based sensing applications.
Modeling and Analysis of Nonlinear Wave Propagation in One-Dimensional Phononic Structures
Authors: Liu M. , Zhu W. D.
Published: March 2018

Different from elastic waves in linear periodic structures, those in phononic crystals (PCs) with nonlinear properties can exhibit more interesting phenomena. Linear dispersion relations cannot accurately predict band-gap variations under finite-amplitude wave motions; creating nonlinear PCs remains challenging and few examples have been studied. Recent studies in the literature mainly focus on discrete chain-like systems; most studies only consider weakly nonlinear regimes and cannot accurately obtain some relations between wave propagation characteristics and general nonlinearities. This paper presents propagation characteristics of longitudinal elastic waves in a thin rod and coupled longitudinal and transverse waves in an Euler–Bernoulli beam using their exact Green–Lagrange strain relations. We derive band structure relations for a periodic rod and beam and predict their nonlinear wave propagation characteristics using the B-spline wavelet on the interval (BSWI) finite element method. Influences of nonlinearities on wave propagation characteristics are discussed. Numerical examples show that the proposed method is more effective for nonlinear static and band structure problems than the traditional finite element method and illustrate that nonlinearities can cause band-gap width and location changes, which is similar to results reported in the literature for discrete systems. The proposed methodology is not restricted to weakly nonlinear systems and can be used to accurately predict wave propagation characteristics of nonlinear structures. This study can provide good support for engineering applications, such as sound and vibration control using tunable band gaps of nonlinear PCs.
Mapping the Efficiency of a Double Acting, Single-Rod Hydraulic-Actuator Using a Critically Centered Four-Way Spool Valve and a Load-Sensing Pump
Authors: Manring Levi H. , Manring Noah D.
Published: March 2018

In this paper, an efficiency map is created for a double-acting, single-rod hydraulic-actuator using a critically centered four-way spool valve and a load-sensing pump. The purpose of this research is to provide an understanding of the performance of a valve-controlled hydraulic actuator under all operating conditions. This paper considers a four-quadrant set of operating conditions, where each quadrant represents a different combination of actuator retraction or extension and overrunning or resistive loading. This four-quadrant efficiency map is the first presentation of its kind in the literature, and clearly demonstrates the performance characteristics and limitations for this hydraulic system. For its most common operation of an actuator extending under a resistive load, the map shows that this system can operate at over 82% efficiency and can move large loads. The map also shows physical limitations for the system, such as maximum pressure limits, maximum displacement limits, and valve limits. The efficiency map is plotted in nondimensional form, which presents the most general understanding of system performance and also allows dimensional values to be reconstructed for a similar system of any size.
On the Development of a New Master Device Used for Medical Tasks
Authors: Saafi Houssem , Laribi Med Amine , Zeghloul Said , Arsicault Marc
Published: March 2018

This paper discusses the design of a new spherical parallel manipulator (SPM), which is used as a master device for medical tasks. This device is obtained by changing the kinematics of a classic SPM to eliminate the singularity from the device's useful workspace. The kinematic models of the new device are studied. The geometric parameters of the new device are optimized to eliminate the singularity. A prototype of the new master device is presented. Experiments are carried out using the device which allowed the control of a surgical robot.
Passive Compliance Control of Redundant Serial Manipulators
Authors: Rice Jacob J. , Schimmels Joseph M.
Published: March 2018

Passive compliance control is an approach for controlling the contact forces between a robotic manipulator and a stiff environment. This paper considers passive compliance control using redundant serial manipulators with real-time adjustable joint stiffness. Such manipulators can control the elastic behavior of the end-effector by adjusting the manipulator configuration and by adjusting the intrinsic joint stiffness. The end-effector's time-varying elastic behavior is a beneficial quality for constrained manipulation tasks such as opening doors, turning cranks, and assembling parts. The challenge in passive compliance control is finding suitable joint commands for producing the desired time-varying end-effector position and compliance (task manipulation plan). This problem is addressed by extending the redundant inverse kinematics (RIK) problem to include compliance. This paper presents an effective method for simultaneously attaining the desired end-effector position and end-effector elastic behavior by tracking a desired variation in both the position and the compliance. The set of suitable joint commands is not unique; the method resolves the redundancy by minimizing the actuator velocity norm. The method also compensates for joint deflection due to known external loads, e.g., gravity.
Setup of the Supercritical CO2 Test Facility “SCARLETT” for Basic Experimental Investigations of a Compact Heat Exchanger for an Innovative Decay Heat Removal System
Authors: Flaig Wolfgang , Mertz Rainer , Starflinger Joerg
Published: March 2018

Supercritical fluids show great potential as future coolants for nuclear reactors, thermal power, and solar power plants. Compared to the subcritical condition, supercritical fluids show advantages in heat transfer due to thermodynamic properties near the critical point. A specific field of interest is an innovative decay heat removal system for nuclear power plants, which is based on a turbine-compressor system with supercritical CO2 as the working fluid. In case of a severe accident, this system converts the decay heat into excess electricity and low-temperature waste heat, which can be emitted to the ambient air. To guarantee the retrofitting of this decay heat removal system into existing nuclear power plants, the heat exchanger (HE) needs to be as compact and efficient as possible. Therefore, a diffusion-bonded plate heat exchanger (DBHE) with mini channels was developed and manufactured. This DBHE was tested to gain data of the transferable heat power and the pressure loss. A multipurpose facility has been built at Institut für Kernenergetik und Energiesysteme (IKE) for various experimental investigations on supercritical CO2, which is in operation now. It consists of a closed loop where the CO2 is compressed to supercritical state and delivered to a test section in which the experiments are run. The test facility is designed to carry out experimental investigations with CO2 mass flows up to 0.111 kg/s, pressures up to 12 MPa, and temperatures up to 150 °C. This paper describes the development and setup of the facility as well as the first experimental investigation.
Effect of Lead-Bismuth Eutectic Oxygen Concentration on the Onset of Dissolution Corrosion in 316 L Austenitic Stainless Steel at 450 °C
Authors: Klok Oksana , Lambrinou Konstantina , Gavrilov Serguei , Lim Jun , De Graeve Iris
Published: March 2018

This work focuses on the effect of dissolved oxygen concentration in liquid lead-bismuth eutectic (LBE) on the onset of dissolution corrosion in a solution-annealed 316 L austenitic stainless steel. Specimens made of the same 316 L stainless steel heat were exposed for 1000 h at 450 °C to static liquid LBE with controlled concentrations of dissolved oxygen, i.e., 10−5, 10−6, and 10−7 mass%. The corroded 316 L steel specimens were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). A complete absence of dissolution corrosion was observed in the steel specimens exposed to liquid LBE with 10−5 and 10−6 mass% oxygen. In the same specimens, isolated “islands” of FeCr-containing oxides were also detected, indicating the localized onset of oxidation corrosion under these exposure conditions. On the other hand, dissolution corrosion with a maximum depth of 59 μm was detected in the steel specimen exposed to liquid LBE with 10−7 mass% oxygen. This suggests that the threshold oxygen concentration associated with the onset of dissolution corrosion in this 316 L steel heat lies between 10−6 and 10−7 mass% oxygen for the specific exposure conditions (i.e., 1000 h, 450 °C, static liquid LBE).
Influence of Selected Gasification Parameters on Syngas Composition From Biomass Gasification
Authors: Al-Zareer Maan , Dincer Ibrahim , Rosen Marc A.
Published: March 2018

In this study, the syngas composition exiting a biomass gasifier is investigated to determine the effect of varying selected gasification parameters. The gasification parameters considered are the mass flow rate of steam, the gasification agent, the mass flow rate of oxygen, the gasification oxidant, and the type of biomass. The syngas composition is represented by its hydrogen, carbon monoxide, carbon dioxide, and water fractions. The oxygen fed to the gasifier is produced using a cryogenic air separation unit (CASU). The gasifier and the air separation unit are modeled and simulated with aspenplus, where the gasification reactions are carried out based on the Gibbs free energy minimization approach. Finally, the syngas composition for the different types of biomass as well as the different compositions of the three types of the biomass considered are compared in terms of chemical composition. It was found that for each type of biomass and at a specified steam flow rate there is an air to the air separation unit where the gasification of the biomass ends and biomass combustion starts and as the volatile matter in the biomass increases the further the shifting point occur, meaning at higher air flow rate. It was found for the three considered biomass types and their four mixtures that, as the volatile matter in the biomass increases, more hydrogen is observed in the syngas. An optimum biomass mixture can be achieved by determining the right amount of each type of biomass based on the reported sensitivity analysis.
Experimental Study of Transient Hydrodynamics in a Spouted Bed of Polydisperse Particles
Authors: Bai Ling , Shi Weidong , Zhou Ling , Zhang Lingjie , Li Wei , Agarwal Ramesh K.
Published: March 2018

In industrial processes such as chemical looping combustion, single-component spouted beds of monodisperse particles are very rarely used but the spouted beds of polydisperse particles have been widely used. The flow characteristics of polydisperse particles are much more complex than the single particle fraction in a fluidized bed. To investigate the gas–solid two-phase flow characteristics of the particles with different diameters in a spouted bed, the segregation and mixing characteristics, bubble morphology, minimum spouting velocity, and pressure fluctuations of the particles with different sizes under different superficial gas velocities are studied experimentally. The results show that higher the initial bed height and larger the volume fraction of the bigger particles, higher is the minimum spouting velocity. Moreover, the magnitude of the minimum spouting velocity increases exponentially with increase in the volume fraction of the bigger particles. At low superficial gas velocity, there is a clear trend of segregation between the particles of different diameters. At moderate superficial gas velocity, the mixing trend among particles of different diameters is enhanced, and the pressure fluctuations in the bed present some degree of regularity. At high superficial gas velocity, the particles of different diameters tend to separate again, the pressure fluctuations become intense, and the particle flow turns into a turbulent state. Furthermore, when the bed becomes stable, the particles of different diameters distribute within the bed with regular stratification.
An Experimental Investigation of Early Flame Development in an Optical Spark Ignition Engine Fueled With Natural Gas
Authors: Dumitrescu Cosmin E. , Padmanaban Vishnu , Liu Jinlong
Published: March 2018

Improved internal combustion engine simulations of natural gas (NG) combustion under conventional and advanced combustion strategies have the potential to increase the use of NG in the transportation sector in the U.S. This study focused on the physics of turbulent flame propagation. The experiments were performed in a single-cylinder heavy-duty compression-ignition (CI) optical engine with a bowl-in piston that was converted to spark ignition (SI) NG operation. The size and growth rate of the early flame from the start of combustion (SOC) until the flame filled the camera field-of-view were correlated to combustion parameters determined from in-cylinder pressure data, under low-speed, lean-mixture, and medium-load conditions. Individual cycles showed evidence of turbulent flame wrinkling, but the cycle-averaged flame edge propagated almost circular in the two-dimensional (2D) images recorded from below. More, the flame-speed data suggested different flame propagation inside a bowl-in piston geometry compared to a typical SI engine chamber. For example, while the flame front propagated very fast inside the piston bowl, the corresponding mass fraction burn was small, which suggested a thick flame region. In addition, combustion images showed flame activity after the end of combustion (EOC) inferred from the pressure trace. All these findings support the need for further investigations of flame propagation under conditions representative of CI engine geometries, such as those in this study.
Correlating Quantitative Risk Assessment and Exergy Analysis for Accounting Inefficiency in Process Hazards: A Case Study
Authors: Cassetti G. , Bellina M. C. , Colombo E.
Published: March 2018

The core of the work is the investigation of the possible correlation between the thermodynamics and the hazards of a process. The objective is understanding the role of inefficiency in hazards consequences. To investigate such correlation, a case study from oil and gas sector is developed, where exergy analysis is used to study the thermodynamics of the process and a simplified quantitative risk assessment (QRA) is performed to evaluate the consequences of identified hazards. The thermo-economic approach is then used to correlate the two analyses. Through the analysis, the authors want to identify those components where hazardous consequences may be affected by inefficiency, aiming to reduce the risk of fatalities in processes by operating on the process itself or suggesting possible alternative strategies. The purpose of the paper is also to propose for further investigation on the correlation between inefficiency and process hazards.
Integration of Soiling-Rate Measurements and Cleaning Strategies in Yield Analysis of Parabolic Trough Plants
Authors: Wolfertstetter Fabian , Wilbert Stefan , Dersch Jürgen , Dieckmann Simon , Pitz-Paal Robert , Ghennioui Abdellatif
Published: March 2018

The issue of reflector soiling becomes more important as concentrating solar thermal power plants (CSP) are being implemented at sites subject to high dust loads. In an operational power plant, a trade-off between reducing cleaning costs and cleaning related collector availability on the one hand and keeping the solar field cleanliness (ξfield) high to minimize soiling induced losses on the other hand must be found. The common yield analysis software packages system advisor model (SAM) and greenius only allow the input of a constant mean ξfield and constant cleaning costs. This oversimplifies real conditions because soiling is a highly time-dependent parameter and operators might adjust cleaning activities depending on factors such as soiling rate and irradiance. In this study, time-dependent soiling and cleaning data are used for modeling the yield of two parabolic trough plant configurations at two sites in Spain and Morocco. We apply a one-year soiling rate dataset in daily resolution measured with the tracking cleanliness sensor (TraCS). We use this as a basis to model the daily evolution of the cleanliness of each collector of a solar field resulting from the application of various cleaning strategies (CS). The thus obtained daily average ξfield is used to modify the inputs to the yield analysis software greenius. The cleaning costs for each CS are subtracted from the project's financial output parameters to accurately predict the yield of a CSP project over its lifetime. The profits obtained with different CSs are compared in a parameter variation analysis for two sites and the economically best CS is identified. The profit can be increased by more than 2.6% by the application of the best strategy relative to a reference strategy that uses a constant cleaning frequency. The error in profit calculated with constant soiling and cleaning parameters compared to the simulation with variable soiling and cleaning can be as high as 9.4%. With the presented method, temporally variable soiling rates and CS can be fully integrated to CSP yield analysis software, significantly increasing its accuracy. It can be used to determine optimum cleaning parameters.
Advanced Cooling in Gas Turbines 2016 Max Jakob Memorial Award Paper
Authors: Han Je-Chin
Published: March 2018

Gas turbines have been extensively used for aircraft engine propulsion, land-based power generation, and industrial applications. Power output and thermal efficiency of gas turbines increase with increasing turbine rotor inlet temperatures (RIT). Currently, advanced gas turbines operate at turbine RIT around 1700 °C far higher than the yielding point of the blade material temperature about 1200 °C. Therefore, turbine rotor blades need to be cooled by 3–5% of high-pressure compressor air around 700 °C. To design an efficient turbine blade cooling system, it is critical to have a thorough understanding of gas turbine heat transfer characteristics within complex three-dimensional (3D) unsteady high-turbulence flow conditions. Moreover, recent research trend focuses on aircraft gas turbines that operate at even higher RIT up to 2000 °C with a limited amount of cooling air, and land-based power generation gas turbines (including 300–400 MW combined cycles with 60% efficiency) burn alternative syngas fuels with higher heat load to turbine components. It is important to understand gas turbine heat transfer problems with efficient cooling strategies under new harsh working environments. Advanced cooling technology and durable thermal barrier coatings (TBCs) play most critical roles for development of new-generation high-efficiency gas turbines with near-zero emissions for safe and long-life operation. This paper reviews basic gas turbine heat transfer issues with advanced cooling technologies and documents important relevant papers for future research references.
Microstructural Characterization of Thermal Damage on Silicon Wafers Sliced Using Wire-Electrical Discharge Machining
Authors: Joshi Kamlesh , Bhandarkar Upendra , Samajdar Indradev , Joshi Suhas S.
Published: March 2018

Slicing of Si wafers through abrasive processes generates various surface defects on wafers such as cracks and surface contaminations. Also, the processes cause a significant material loss during slicing and subsequent polishing. Recently, efforts are being made to slice very thin wafers, and at the same time understand the thermal and microstructural damage caused due to sparking during wire-electrical discharge machining (wire-EDM). Wire-EDM has shown potential for slicing ultra-thin Si wafers of thickness < 200 μm. This work, therefore, presents an extensive experimental work on characterization of the thermal damage due to sparking during wire-EDM on ultra-thin wafers. The experiments were performed using Response surface methodology (RSM)-based central composite design (CCD). The damage was mainly characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The average thickness of thermal damage on the wafers was observed to be ∼16 μm. The damage was highly influenced by exposure time of wafer surface with EDM plasma spark. Also, with an increase in diameter of plasma spark, the surface roughness was found to increase. TEM micrographs have confirmed the formation of amorphous Si along with a region of fine grained Si entrapped inside the amorphous matrix. However, there were no signs of other defects like microcracks, twin boundaries, or fracture on the surfaces. Micro-Raman spectroscopy revealed that in order to slice a wafer with minimum residual stresses and very low presence of amorphous phases, it should be sliced at the lowest value of pulse on-time and at the highest value of open voltage (OV).
Iso-Planar Feed Vector-Fields-Based Streamline Tool Path Generation for Five-Axis Compound Surface Machining With Torus-End Cutters
Authors: Sun Shuoxue , Sun Yuwen , Xu Jinting , Lee Yuan-Shin
Published: March 2018

This paper presents a new vector-field-based streamline smoothing method in the parametric space and a tool orientation optimization technique for five-axis machining of complex compound surfaces with torus-end cutters. Iso-planar tool path is widely used in the machining of various types of surfaces, especially for the compound surface with multiple patches, but the operations of intersecting the compound surface with a series of planes have depended considerably on the complicated optimization methods. Instead of intersecting the surface directly with planes, a novel and effective tool path smoothing method is presented, based on the iso-planar feed vector fields, for five-axis milling of a compound surface with torus-end cutters. The iso-planar feed vector field in the parametric domain is first constructed in the form of stream function that is used to generate the candidate streamlines for tool path generation. Then, a G1 blending algorithm is proposed to blend the vector fields within the adjacent parametric domains to ensure smooth transition of cross-border streamlines. Based on the smoothened streamlines in the parametric domains, pathlines along with their correspondent side sizes are selected as desirable tool paths. Concerning a high performance machining, detailed computational techniques to determine the tool axis orientation are also presented to ensure, at each cutter contact (CC) point, the torus-end cutter touches the part surface closely without gouging. Both the computational results and machined examples are demonstrated for verification and validation of the proposed methods.
Design, Modeling, and Characterization of a 10 kWe Metal Halide High Flux Solar Simulator
Authors: Siegel Nathan P. , Roba Jeffrey P.
Published: March 2018

We present the design and characterization of a high flux solar simulator (HFSS) based on metal halide lamps and built from commercially available components. The HFSS that we present was developed to support the evaluation of a solar thermochemical reactor prototype. The HFSS consists of an array of four independent lamp/reflector modules aimed at a common target location. Each module contains one 2500 We lamp and one electroformed ellipsoidal reflector having an interfocal distance of 813 mm. The modules are oriented with an angle relative to the target surface normal vector of 24.5 deg. Design simulations predicted that the peak flux of this HFSS would be 2980 kWth/m2, with a total power delivered to a 6-cm target of 3.3 kWth, for a transfer efficiency of 33.3%. Experimental characterization of the HFSS using optical flux mapping and calorimetry showed that the peak flux at the focal plane reached 2890±170 kWth/m2, while the total power delivered was 3.5±0.21 kWth for a transfer efficiency of 35.3%. The HFSS was built at a material cost of ∼$2700.00/module and a total hardware cost of ∼$11,000.00 for the four-lamp array. A seven-lamp version of this HFSS is predicted to deliver 5.6 kWth to a 6 cm diameter target at a peak flux of 4900 kWth/m2 at a hardware cost of ∼$19,000.00 ($3400.00/kWth delivered, $1100.00/kWe).
Repopulating retinal microglia restore endogenous organization and function under CX3CL1-CX3CR1 regulation
Authors: Zhang Yikui , Zhao Lian , Wang Xu , Ma Wenxin , Lazere Adam , Qian Hao-hua , Zhang Jun , Abu-Asab Mones , Fariss Robert N. , Roger Jerome E. , Wong Wai T.
Published: March 2018

Chemokine signaling via CX3CL1-CX3CR1 helps regulate homeostasis in the population of microglia in the adult mouse retina.
Bats without borders: Predators learn novel prey cues from other predatory species
Authors: Patriquin Krista J. , Kohles Jenna E. , Page Rachel A. , Ratcliffe John M.
Published: March 2018

Bats learn about novel acoustic prey cues as quickly from heterospecifics as from conspecifics.
Exploration of underwater life with an acoustically controlled soft robotic fish
Authors: Katzschmann Robert K. , DelPreto Joseph , MacCurdy Robert , Rus Daniela
Published: March 2018

A soft robot fish swims independently in three dimensions and enables studies of aquatic life in natural coral reef habitats.
Near-Complete Genome Sequence of a Novel Single-Stranded RNA Virus Discovered in Indoor Air
Authors: Rosario Karyna , Fierer Noah , Breitbart Mya
Published: March 2018

Viral metagenomic analysis of heating, ventilation, and air conditioning (HVAC) filters recovered the near-complete genome sequence of a novel virus, named HVAC-associated
R
NA
v
irus 1 (HVAC-RV1). The HVAC-RV1 genome is most similar to those of picorna-like viruses identified in arthropods but encodes a small domain observed only in negative-sense single-stranded RNA viruses.
Expectations for nursing care in newborn units in Kenya: moving from implicit to explicit standards
Authors: Murphy Georgina A V , Omondi Gregory B , Gathara David , Abuya Nancy , Mwachiro Jacintah , Kuria Rose , Tallam-Kimaiyo Edna , English Mike
Published: March 2018

Neonatal mortality currently accounts for 45% of all child mortality in Kenya, standing at 22 per 1000 live births. Access to basic but high quality inpatient neonatal services for small and sick newborns will be key in reducing neonatal mortality. Neonatal inpatient care is reliant on nursing care, yet explicit nursing standards for such care do not currently exist in Kenya. We reviewed the Nursing Council of Kenya ‘Manual of Clinical Procedures’ to identify tasks relevant for the care of inpatient neonates. An expert advisory group comprising major stakeholders, policy-makers, trainers, and frontline health-workers was invited to a workshop with the purpose of defining tasks for which nurses are responsible and the minimum standard with which these tasks should be delivered to inpatient neonates in Kenyan hospitals. Despite differences in opinions at the beginning of the process, consensus was reached on the minimum standards of neonatal nursing. The key outcome was a comprehensive list and grouping of neonatal nursing task and the minimum frequency with which these tasks should be performed. Second, a simple categorisation of neonatal patients based on care needs was agreed. In addition, acceptable forms of task sharing with other cadres and the patient’s family for the neonatal nursing tasks were agreed and described. The process was found to be acceptable to policy-makers and practitioners, who recognised the value of standards in neonatal nursing to improve the quality of neonatal inpatient care. Such standards could form the basis for audit and quality evaluation.
Republished: Development of an Intracranial Dural Arteriovenous Fistula after Venous Sinus Stenting for Idiopathic Intracranial Hypertension
Authors: Buell Thomas J , Raper Daniel M , Ding Dale , Chen Ching-Jen , Liu Kenneth C
Published: March 2018

We report a case in which an intracranial dural arteriovenous fistula (DAVF) developed after endovascular treatment of a patient with idiopathic intracranial hypertension with venous sinus stenting (VSS). The pathogenesis may involve hemodynamic alterations secondary to increased poststenting venous sinus pressure, which may cause new arterial ingrowth into the fistulous sinus wall without capillary interposition. Despite administration of dual antiplatelet therapy, there may also be subclinical cortical vein thrombosis that contributed to DAVF formation. In addition to the aforementioned mechanisms, increased inflammation induced by VSS may upregulate vascular endothelial growth factor and platelet-derived growth factor expression and also promote DAVF pathogenesis. Since VSS has been used to obliterate DAVFs, DAVF formation after VSS may seem counterintuitive. Previous stents have generally been closed cell, stainless steel designs used to maximize radial compression of the fistulous sinus wall. In contrast, our patient’s stent was an open cell, self-expandable nitinol design (Protégé Everflex). Neurointerventionalists should be aware of this potential, although rare complication of DAVF formation after VSS.
Effectiveness of training workplace managers to understand and support the mental health needs of employees: a systematic review and meta-analysis
Authors: Gayed Aimée , Milligan-Saville Josie S , Nicholas Jennifer , Bryan Bridget T , LaMontagne Anthony D , Milner Allison , Madan Ira , Calvo Rafael A , Christensen Helen , Mykletun Arnstein , Glozier Nicholas , Harvey Samuel B
Published: March 2018

Managers are in an influential position to make decisions that can impact on the mental health and well-being of their employees. As a result, there is an increasing trend for organisations to provide managers with training in how to reduce work-based mental health risk factors for their employees. A systematic search of the literature was conducted to identify workplace interventions for managers with an emphasis on the mental health of employees reporting directing to them. A meta-analysis was performed to calculate pooled effect sizes using the random effects model for both manager and employee outcomes. Ten controlled trials were identified as relevant for this review. Outcomes evaluating managers’ mental health knowledge (standardised mean difference (SMD)=0.73; 95% CI 0.43 to 1.03; p<0.001), non-stigmatising attitudes towards mental health (SMD=0.36; 95% CI 0.18 to 0.53; p<0.001) and improving behaviour in supporting employees experiencing mental health problems (SMD=0.59; 95% CI 0.14 to 1.03; p=0.01) were found to have significant pooled effect sizes favouring the intervention. A significant pooled effect was not found for the small number of studies evaluating psychological symptoms in employees (p=0.28). Our meta-analysis indicates that training managers in workplace mental health can improve their knowledge, attitudes and self-reported behaviour in supporting employees experiencing mental health problems. At present, any findings regarding the impact of manager training on levels of psychological distress among employees remain preliminary as only a very limited amount of research evaluating employee outcomes is available. Our review suggests that in order to understand the effectiveness of manager training on employees, an increase in collection of employee level data is required.
Risk of fall in patients with COPD
Authors: Hakamy Ali , Bolton Charlotte E , Gibson Jack E , McKeever Tricia M
Published: March 2018

A matched cohort study was conducted to determine the incidence of falls in patients following a diagnosis of COPD using a UK primary care database. 44 400 patients with COPD and 175 545 non-COPD subjects were identified. The incidence rate of fall per 1000 person-years in patients with COPD was higher (44.9; 95% CI 44.1 to 45.8) compared with non-COPD subjects (24.1; 95% CI 23.8 to 24.5) (P<0.0001). Patients with COPD were 55% more likely to have an incident record of fall than non-COPD subjects (adjusted HR, 1.55; 95% CI 1.50 to 1.59). The greater falls risk in patients with COPD needs consideration and modifiable factors addressed.
Plasmid persistence: costs, benefits, and the plasmid paradox
Authors: Carroll Amanda C. , Wong Alex
Published: March 2018

Plasmids are extrachromosomal DNA elements that can be found throughout bacteria, as well as in other domains of life. Nonetheless, the evolutionary processes underlying the persistence of plasmids are incompletely understood. Bacterial plasmids may encode genes for traits that are sometimes beneficial to their hosts, such as antimicrobial resistance, virulence, heavy metal tolerance, and the catabolism of unique nutrient sources. In the absence of selection for these traits, however, plasmids generally impose a fitness cost on their hosts. As such, plasmid persistence presents a conundrum: models predict that costly plasmids will be lost over time or that beneficial plasmid genes will be integrated into the host genome. However, laboratory and comparative studies have shown that plasmids can persist for long periods, even in the absence of positive selection. Several hypotheses have been proposed to explain plasmid persistence, including host-plasmid co-adaptation, plasmid hitchhiking, cross-ecotype transfer, and high plasmid transfer rates, but there is no clear evidence that any one model adequately resolves the plasmid paradox.
Canonical quantization of the covariant fields on de Sitter space–times
Authors: Cotaescu Ion I.
Published: March 2018

The properties of the covariant quantum fields on de Sitter space–times are investigated focusing on the isometry generators and Casimir operators in order to establish the equivalence among the covariant representations and the unitary irreducible ones of the de Sitter isometry group. For the Dirac quantum field, it is shown that the spinor covariant representation, transforming the Dirac field under de Sitter isometries, is equivalent with a direct sum of two unitary irreducible representations of the [Formula: see text] group, transforming alike the particle and antiparticle field operators in momentum representation. Their basis generators and Casimir operators are written down finding that the covariant representations are equivalent with unitary irreducible ones from the principal series whose canonical weights are determined by the fermion mass and spin.
HAUSDORFF DIMENSION OF JULIA SETS OF QUADRATIC POLYNOMIALS
Authors: MARTÍNEZ LUIS MANUEL , BLÉ GAMALIEL
Published: March 2018

The Hausdorff dimension of Julia sets of expanding maps can be computed by the eigenvalue algorithm. In this work, an implementation of this algorithm for quadratic polynomial, that allows the calculation of the Hausdorff dimension of Julia sets for complex parameters, is done. In particular, the parameters in a neighborhood of the parabolic parameter [Formula: see text] are analyzed and a small oscillation in Hausdorff dimension is shown.
PRECISE CALCULATION OF HAUSDORFF DIMENSION OF APOLLONIAN GASKET
Authors: BAI ZAI-QIAO , FINCH STEVEN R.
Published: March 2018

A transfer operator method is proposed to calculate [Formula: see text], the Hausdorff dimension of the Apollonian gasket. Compared with previous operator-based methods, we make two improvements in this paper. We adopt an infinite set of contractive Möbius transformations (rather than a finite set of parabolic ones) to generate the Apollonian gasket. We also apply an efficient finite matrix approximation of an infinite sum of infinite-dimensional operators. By using this method, a high precision estimate of [Formula: see text] is obtained: [Formula: see text]
COMPLEXITY-BASED ANALYSIS OF THE DIFFERENCE IN SPEECH-EVOKED AUDITORY BRAINSTEM RESPONSES (s-ABRs) BETWEEN BINAURAL AND MONAURAL LISTENING CONDITIONS
Authors: MOZAFFARILEGHA MARJAN , NAMAZI HAMIDREZA , AHADI MOHSEN , JAFARI SAJAD
Published: March 2018

One of the important research areas in behavioral neuroscience is to investigate the brain response to different types of stimuli. Speech-evoked Auditory Brainstem Response (s-ABR) is a tool to study the brainstem processing of speech sounds. During years, scientists have employed different techniques to analyze the influence of auditory stimulation on s-ABR signal in different conditions. One important category of works, which aroused the attention of scientists, has been the analysis of the variations of s-ABR signal in binaural and monaural stimulations. In this research, we analyze the variations of s-ABR signal due to auditory stimulation in the form of speech syllable, in binaural and monaural (right or left ear) listening conditions. For this purpose, we have employed fractal analysis in order to analyze the complexity of s-ABR signal in three stimulation conditions (both ears, right ear, left ear). The results of our analysis showed that s-ABR signal in case of binaural stimulation shows significant lower complexity compared to monaural stimulation. In comparison of s-ABR signals between left ear and right ear using fractal dimension, no significant difference was observed.
Synthesis of MoSe2/SrTiO3 Heterostructures with Enhanced Ultraviolet-Light-Driven and Visible-Light-Driven Photocatalytic Properties
Authors: Zhou Xingwang , Yao Jun , Yang Ming , Ma Jiangquan , Zhou Qingwei , Ou Ershen , Zhang Zhen , Sun Xueni
Published: March 2018

In this research, a series of novel MoSe2/SrTiO3 heterostructures were successfully prepared by a two-step hydrothermal method. The samples were characterized by XRD, UV-Vis, SEM, TEM, EDS and XPS. Results showed that the degradation of MO under UV is better than that under the visible light. And, MoSe2 loaded on SrTiO3 under UV irradiation demonstrated a higher catalytic activity. The degradation rate of methyl orange was 99.46% for MoSe2/SrTiO3 under the optimum loading weight (0.1[Formula: see text]wt.%). This is mainly because the combination of MoSe2 and SrTiO3 prevents electrons and holes recombination in SrTiO3 and [Formula: see text]O[Formula: see text] appears in the system. In general, MoSe2/SrTiO3 heterostructures have good environmental friendliness for photocatalytic degradation.
THE IMPACT OF CARBON TAXATION AND REVENUE RECYCLING ON U.S. INDUSTRIES
Authors: MACALUSO NICK , TULADHAR SUGANDHA , WOOLLACOTT JARED , MCFARLAND JAMES R. , CREASON JARED , COLE JEFFERSON
Published: March 2018

This paper provides a detailed, cross-model analysis and discussion of the implications of carbon tax scenarios on changes in sectoral output, energy production and consumption and the competitiveness of the United States’ economy. Our analysis focuses on the broad patterns apparent across models in both qualitative and quantitative terms at the sector level, with a focus on energy-intensive, trade-exposed sectors. We identify how variations in carbon tax trajectories and different options for using the revenue from the tax drive these results.
THE INTERGENERATIONAL INCIDENCE OF GREEN TAX REFORM
Authors: RAUSCH SEBASTIAN , YONEZAWA HIDEMICHI
Published: March 2018

We examine the lifetime incidence and intergenerational distributional effects of an economy-wide carbon tax swap using a numerical dynamic general equilibrium model with overlapping generations of the U.S. economy. We highlight various fundamental choices in policy design including (1) the level of the initial carbon tax, (2) the growth rate of the carbon tax trajectory of over time, and (3) alternative ways for revenue recycling. Without revenue recycling, we find that generations born before the tax is introduced experience smaller welfare losses, or even gain, relative to future generations. For sufficiently low growth rates of the tax trajectory, the impacts for distant future generations decrease over time. For future generations born after the introduction of the tax, the negative welfare impacts are the smallest (largest) when revenues are recycled through lowering pre-existing capital income taxes (through per-capita lump-sum rebates). For generations born before the tax is introduced, we find that lump-sum rebates favor very old generations and labor (capital) income tax recycling favors very young generations (generations of intermediate age).
U.S. CARBON TAX SCENARIOS AND BIOENERGY
Authors: SANDS RONALD D.
Published: March 2018

This paper documents application of the Future Agricultural Resources Model (FARM) to stylized carbon tax scenarios specified by the Stanford Energy Modeling Forum (EMF). Model results show that the method of tax revenue recycling makes a difference. Either labor-tax, or capital-tax, recycling can reduce the welfare cost of a carbon tax policy relative to lump sum recycling. Of the two tax recycling options, reducing capital taxes provides the greater reduction in welfare costs. However, carbon tax revenues decline with stringent carbon dioxide (CO2) emission targets and the availability of a negative-emissions technology such as bio-electricity with CO2 capture and storage (BECCS). As BECCS expands, net carbon tax revenues peak and decline due to an offsetting subsidy for carbon sequestration, limiting the potential for labor- or capital-tax recycling to reduce welfare costs of a climate policy.
Neural Mechanisms of Social Cognition in Primates
Authors: Wittmann Marco K. , Lockwood Patricia L. , Rushworth Matthew F.S.
Published: March 2018

Activity in a network of areas spanning the superior temporal sulcus, dorsomedial frontal cortex, and anterior cingulate cortex is concerned with how nonhuman primates negotiate the social worlds in which they live. Central aspects of these circuits are retained in humans. Activity in these areas codes for primates’ interactions with one another, their attempts to find out about one another, and their attempts to prevent others from finding out too much about themselves. Moreover, important features of the social world, such as dominance status, cooperation, and competition, modulate activity in these areas. We consider the degree to which activity in these regions is simply encoding an individual's own actions and choices or whether this activity is especially and specifically concerned with social cognition. Recent advances in comparative anatomy and computational modeling may help us to gain deeper insights into the nature and boundaries of primate social cognition.
Increased urinary angiotensin converting enzyme 2 and neprilysin in patients with type 2 diabetes
Authors: Gutta Sridevi , Grobe Nadja , Kumbaji Meenasri , Osman Hassan , Saklayen Mohammad , Li Gengxin , Elased Khalid M.
Published: March 2018

Angiotensin converting enzyme 2 (ACE2) and neprilysin (NEP) are metalloproteases that are highly expressed in the renal proximal tubules. ACE2 and NEP generate renoprotective angiotensin (1–7) from angiotensin II and angiotensin I, respectively, and therefore could have a major role in chronic kidney disease (CKD). Recent data demonstrated increased urinary ACE2 in patients with diabetes with CKD and kidney transplants. We tested the hypothesis that urinary ACE2, NEP, and a disintegrin and metalloproteinase 17 (ADAM17) are increased and could be risk predictors of CKD in patients with diabetes. ACE2, NEP, and ADAM17 were investigated in 20 nondiabetics (ND) and 40 patients with diabetes with normoalbuminuria (Dnormo), microalbuminuria (Dmicro), and macroalbuminuria (Dmacro) using ELISA, Western blot, and fluorogenic and mass spectrometric-based enzyme assays. Logistic regression model was applied to predict the risk prediction. Receiver operating characteristic curves were drawn, and prediction accuracies were calculated to explore the effectiveness of ACE2 and NEP in predicting diabetes and CKD. Results demonstrated that there is no evidence of urinary ACE2 and ADAM17 in ND subjects, but both enzymes were increased in patients with diabetes, including Dnormo. Although there was no detectable plasma ACE2 activity, there was evidence of urinary and plasma NEP in all the subjects, and urinary NEP was significantly increased in Dmicro patients. NEP and ACE2 showed significant correlations with metabolic and renal characteristics. In summary, urinary ACE2, NEP, and ADAM17 are increased in patients with diabetes and could be used as early biomarkers to predict the incidence or progression of CKD at early stages among individuals with type 2 diabetes.